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* GB784953 (A)
Description: GB784953 (A) ? 1957-10-23
Improvements in or relating to composite metal product making process andapparatus
Description of GB784953 (A)
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PATENT SPECIFICATION Date of Application and filing Complete Specification: June 10, 1955. 784,953 No 16732/55. Application made in United States of America on June 10, 1954. Complete Specification Published: Oct 23, 1957. Index at acceptance:-Classes 82 ( 2), E 3, M; 83 ( 2), A( 26:83:124); and 83 ( 4), S( 2 B:20. 4). International Classification:-B 23 k, p, C 23 g. COMPLETE SPECIFICATION Improvements in or relating to Composite Metal Product Making Process and Apparatus We, BRIDGEPORT BRASS COMPANY, a corporation organised under the laws of the State of Connecticut, United States of America, of Bridgeport, State of Conneeticut, United States of America, do hereby declare the invention, for which we pray that a patent may be
granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a composite metal product making process and apparatus invented particularly for use in manufacturing cladmetal flat sheet producs. One of the objects is to provide a process and apparatus for making flat sheet cladmetal products commercially in a reliable manner Another object is to produce cladmetal having a copper or cuprous metal base clad on one or both sides with a layer of stainless metal, as exemplified by stainless steel, which is so thin that if the base metal exhibits orange peeling when drawn this defect will be visible on the stainless metal surface, in such a manner that the cladmetal base has a sufficiently fine grain size to avoid this kind of trouble and with the stainless layer or layers bonded to the copper or cuprous base strongly enough to avoid separation during drawing of the cladmetal The term " cuprous metal " is intended to mean bronze, brass, copper or similar metals which produce large grain crystal structures when heated which cause surface defects when later deep drawn into hollow-ware or the like A further object is to attain this secondly stated kind of product reliably and in a commercially practical manner Other objects may be inferred from the following disclosure. The present invention provides a process for making a composite metal product which comprises superimposing first and second metal-layers with brazing material lPrictpositioned between the layers' mutually facing surfaces to form an assembly, and subjecting said assembly to heat and pressure characterized by enclosing the assembly in a casing provided with a flexible 50 diaphragm located so that the inner one Qu its sides can apply pressure to the side of the first of said layers, which is flexible, opposite to the mutually facing surfaces of the layers, evacuating or partially evacu 55 ating said easing and applying sufficient fluid pressure to the diaphragm's other side and a substantially equal and opposite pressure to the second layer to cause said surfaces to conform with each other sub 60 stantially throughout by flexing of the diaphragm and the flexible layer, and while said casing is evacuated or partially evacuated and while applying said pressures, heating said surfaces and the braz 65 ing material to brazing temperature and thereafter permitting them to cool to form a solid bond between said surfaces, and thereafter admitting atmospheric pressure into said easing 70 The present invention also provides a composite metal product making apparatus for applying brazing heat and pressure to first andosecond metal layers with brazing material positioned between the layers' 75 mutually facing surfaces forming an assembly, said apparatus comprising a substantially fluid-tight easing
provided with a flexible diaphragm located so that the inner one of its sides can apply pressure to 80 the side of the first of said layers, which is flexible, opposite to the mutually facing surfaces of said layers, said easing having an outlet for evacuation thereof, said apparatus also including a heatable liquid 85 bath into which said casing with the assemblv therein is adapted to be immersed so that when the liquid is heated and the casing is evacuated the assembly will be subjected to heat and fluid pressure wil 190 784,953 be applied to the diaphragm's outer side and said apparatus also including means to apply substantially equal and opposite pressure to the second layer. S A specific example of the composite metal product making apparatus as it is used in practising the new process is illustrated by the accompanying drawings in which:Fig 1 is a plan view of the easing; Fig 2 is a cross section taken on the line 2-2 in Fig 1; and Fig 3 is a view showing the apparatus with the easing imrmersed in a bath of heating liquid, the bath components being in section and the easing itself being in elevation. Two layers are involved when producing duplex cladmetal while three layers are involved when making triplex cladmetal In all eases the outermost layer or layers are within the thickness ranges of sheet metal gauges They must be thin enough to flex appreciably when subjected on one side only to fluid pressure no higher than atmospheric pressure with the flexure occurring with relative freedom between relatively short span lengths The base metal is ordinarily substantially thicker than the cladding metal In most instances the total thickness of all of the layers when superimposed, to make one cladmetal product, is thin enough to have the flexibility just described. The base metal particularly contemplated is copper or cuprous It may be any high-copper or copper base alloy which is suitable for drawing and forming when properly processed The base metal must be eapable of being brazed The stainless metal, with which the base metal is clad on one or both sides, may be either of those known under the Registered Trade Marks "Inconel" and ',S Ionel," or Zireonium, but the metal particularly contemplated is stainless steel The stainless material should be suitably processed to provide it with adequate drawing properties because the cladding procedure of the present invention ordinarily does not provide for enough heating to affect the properties of the stainless materials For example, if stainless steel is used it should be annealed so that it will draw properly. It is to be-understood that the present invention does not necessitate any further thie ckness reduetion of the metal layers and that, therefore, the cladmetal components may be sheet metal which has
previously been worked fully to the gauge desired. Preferably a plurality of such cladmetal assemblies are piled flatly on top of one another Eaeh assembly comprises the base metal layer and one or two cladding layers with the brazing material interposed appropriately When piled or stacked the total thickness of the stack should not provide such stiffness that the interfaces of the individual sheets fail to conform throughout their areas when sub 70 jected to flexing pressures no higher than atmospheric pressure In practising the invention when using 024 " thick copper sheets and 015 " stainless steel sheets, it has been found to be practical to stack as 75 many as 20 duplex assemblies or 16 triplex assemblies However, the permissible thickness of the stack depends on the flatness of the sheet components, sheets of good flatness permitting thicker stacks 80 than do sheets that tend to curve somewhat Sheets having lengthwise or transverse gauge variations which are substantial may also limit the permissible stack thickness 85 The casing can also be provided with a second flexible diaphragm, in which case a plurality of the assemblies can he arranged face to face to form a pack located so that the first and second diaphragms of the 90 casing apply pressure respectively to opposite ends of the pack throughout the extent of the sides of the outer and layers thereof. Eaeh assembly may comprise one layer of cuprous alloy and at least one layer of 95 non-cuprous stainless alloy. Such a stack is placed inside the easing shown by the drawings There is no brazing material between the interfacing surfaces of adjacent cladmetal assemblies 100 The brazing material is initially interposed between the mutually facing surfaces of the layers prior to the formation of each assembly by apply a flux including a volatile liquid earrier to one of the sur 105 faces, positioning the surface horizontally and facing upwardly, ereating a falling shower of the brazing metal particles over the surface so that the particles fall on the surface, and thereafter driving off the 110 volatile liquid. This casing or fixture comprises two rigid metal rings 1 which are of the same diameters and between which two flexible sheet metal diaphragms 2 are clamped, the 115 diaphragms being spaced apart by a ring 3 The mutually abutting surfaces of the rings 1, the diaphragms 2 and of the ring 3 are smoothly finished so that with adequate clamping pressure on the rings 1 120 the fixture is made air-tight or nearly so. The elamping pressure is applied to the rings 1 by a series of peripherally interspaced clamps 4 which may be in the nature of C clamps produeing pressure by 125 means of cams 5 which mhay be turned by radially projecting studs 6 A pipe or the like may be slipped over these studs to swing them so as to get rood elamping pressure and when
required to release the 130 784,953 clamps. The ring 2 has a radially extending hole. 7 formed through it so as to open between the diaphragms 2, and a metal tube 8 is S secured in this hole 7 to the ring 3 This tube extends to a source of vacuum which is sufficient to remove substantially all of the atmosphere between the two diaphragms 2, the clamps 4 maintaining the fixture air-tight. Since the sheet metal diaphragms 2 may be made quite thin they are very flexible and, therefore, transmit the atmospheric pressure directly to the stack of cladmetal assemblies The outside layers form the opposite ends of the stack and since all of the cladmetal assemblies are flexible the atmospheric pressure distributes itself throughout the stack In this fashion the atmospheric pressure flexes each and every layer as required to cause their interfaces to conform with each other Thus all of the interfaces are brought into contact with each other. It can be seen that the stack of cladmetal assemblies forms what is in effect a sheet metal pack The brazing material is interposed between the interfaces which are to be bonded together to form the desired cladmetal. The use of brazing to bond the cladmetal layers together has the advantage that the temperatures required for brazing are much lower than welding temperatures. Copper and copper alloys are subject to orange peeling when drawn after the metal has been maintained at high temperatures long enough to cause the necessary increase in the grain size of the metal and which is responsible for the appearance of this kind of defect Brazing temperatures, by selection of proper brazing materials, are low enough to avoid this trouble if the necessary heat can be imparted to the brazing material rapidly enough and removed rapidly enough Objectionable grain growth requires both temperature and time to develop. With the stack or pack enclosed in the fixture the latter may be immersed in a hot liquid 9 as is shown in Fig 3 A molten salt may be used, which may be contained in a suitable tank 10 suspended in a tank heating furnace 11 During this time the tube 8 is maintained in connection with the source of vacuum so that the cladmetal pack is maintained under atmospheric pressure. It can be seen that in this fashion heat is placed in the pack very rapidly It is practically as though the pack were suspended directly in the heating liquid bath, but all of this time various layers of the cladmetal are forced into face-to-face contact throughout their entire extents by the continuously maintained atmospheric pressure This not only assures uniform brazing throughout but it also assures a good
thermal conduction throughout the entire pack Thus the heat gets to the brazing 70 material rapidly so as to fuse the latter as required for brazing, and as soon as this condition is effected the fixture is removed promptly from the heating liquid so that it may be permitted to cool in the open air 75 or by quenching in oil or water Cooling is rapid because of the good conduction path previously mentioned, the vacuum being maintained during this cooling period After the brazing material solidi 80 fies the vacuum is terminated, the clamps 4 are released, and the diaphragms 2 are separated from the pack which then consists of a stack of finished cladmetal sheets. Due to the rapidity of the heating and 85 cooling both the temperature and time factors may be kept at values assuring against undue grain growth on the part of the copper or copper alloy components. Therefore, the resulting cladmetal sheet 90 may be drawn deeply, if desired, without the development of orange peeling such as would show through the stainless cladding when the latter is thin Consequently, articles deep drawn from this material do 95 not require extensive grinding such as is necessary to provide a good finish when the orange peeling visibly marks the outside of the stainless component. It has been found desirable to use a 100 brazing material which comprises a mixture of flux and brazing metal particles with the flux and particles substantially uniformly distributed between the surfaces, which are to be brazed together, in 105 relative proportions forming a bond between these surfaces consisting of the fused slag in a highly dispersed phase mingled with a matrix of the brazing metal This requires the use of only a very 110 small amount of brazing metal in each instance and, therefore, makes it possible to use a brazing metal having a large silver content and consequently which fuses at a relatively low temperature The tendency 115 towards grain growth is, of course, reduced by the use of the lowest possible brazing temperatures. The practice of the present invention has shown that the commercial production 120 of the desired kind of cladmetal, having a copper or copper alloy base and a thin stainless clad layer and which is suitable for deep drawing, is aided substantially by following rather carefully certain opera 125 tional details These are explained in connection with the following description of a specific example of the present invention. In this specific example the product made has a copper base and a stainless 130 784,953 steel cladding on one or both sides The copper is sheet metal which is 024 " thiek and the stainless steel is sheet metal which is 015 " thiek The cladmnetal is in the form of disks which are 121-" in diameter and are intended to be deep drawn into hollowware in the form of domestic cooking utensils It is necessary
that the cladmetal layers be bonded together firmly enough not to separate during this drawing and it is very preferable that the copper component have a fine enough grain size to prevent it from developing the orange peel defect to a degree sufficient to form corresponding marks on the outside of the stainless layer If this difficulty occurs the marks must be removed from the stainless surface by extensive and, therefore, expensive grinding The stainless steel may be A I S I types 301, 302 304, 305 or 430 processed so as to develop their deep drawing properties. The copper component may be OFHC (i e, oxygen free, high conductivity) copper, 10 B & S numbers hard All the aforementioned designations are standard terms in the United States of America, the metals all being commercially available. However, it is to be noted that any stainless steel or other relatively stainless metal may comprise the cladding layer If a softer temper is used care should be taken to assure that the copper has a grain size suitable for deep drawing without the development of orange peeling or other surface defects It is considered very preferable to start with copper containing considerable cold-work strain so as to be certain of a fine grain in the final product, assuming that a brazing material is used requiring brazing temperatures above the recrystallization temperature of the copper. Al 11 of these cladmetal components are pre-cuet into disks of the previously stated diameter and in all cases their surfaces are thoroughly degreased This may be done by the use of vapor methods, electrolvtic methods or in any way effecting o O thorough degreasing Degreasing may be satisfactorily effected by soaking the disks in an aqueous solution containing from 4 to 8 ounces of sodium hydroxide per gallon of water, the solution being maintained at temperatures from 160 to 200 F The soaking time depends on the extent of the contamination which must be removed. It is also necessary to remove surface oxides from the pre-ent disks There are various known ways for removing such oxides. For example, one method of removing the surface oxides from the copper disks is by immersing the disks in a solution consisting of 2 gallons of sulphuric acid, 1 gallon of nitric acid, 1 quart of water and fluid ounce of hydrochloric acid, the solution being used at room temperature. In the ease of the stainless steel disks they may be treated b immersing them in a 70 water solution of 40 % hydrochloric acid, by volume maintained at 1555 F. In case the work is proceeding rapidly the stainless and copper disks may be simply washed and dried, after they are 75 cleaned and their surface oxides are removed If operations are such that it may be
necessary to store the disks long enough for oxides to form on their surfaces to a material degree, the disks may be thor-80 oughlyv rinsed in water rinsed quickly through two or more baths of anhvdrous methyl alcohol and then stored in the final alcohol bath. In the practice of the present invention 85 it is to be understood that the sheet metal components have smooth surfaces Rouol surfaces are undesirable The usual smoothness obtained by finished rolling methods at the mill is satisfactory Clean 90 ing and surface deoxidation methods which might unduly roughen the disk surfaces should be avoided. As the next step the inside surface of each of the dried stainless steel disks is 95 smoothly coated with a brazing flux solution including a volatile liquid permitting drying after application The flux should be suitable to promote good brazing The follo Ming solution, by weight, has been 100 used satisfactorily:Potassium Hydroxide 1 part "Handy Flux" 9 parts Water 91 parts The "Handy Flux" component, manufac 105 tured by Handy and Harman, has the following (dry basis analysis:Potassium Fluoride 40 % Boric Acid 30 % Sodium Borate 30 % 110 This flux solution is uniformly applied to the inside surface of each stainless disk layer This may be done by rotating the disk and applying the solution with a brush, or spraying or other methods may 115 be used In case the disks have been stored in the alcohol they may be either dried or wet with the flux while still wet with the alcohol It may also be possible to store the disks in water since this pro 120 teets their surfaces for reasonable time periods, and in such a case also they may be either dried or directly eoated with the flux solution. The stainless steel disks are positioned 125 horizontally with their sides uppermost which are wet with the flux solution and brazing metal powder in the form of an airborne shower is permitted to fall on their wet surfaces The brazing powder 130 784,953 should be of adequately small particle size to fall uniformly The shower may be created by blowing the plowder upwardly into a tower and permitting the powder to fall on the disks 300 mesh and 150 mesh particle sizes have been successfully used. The physical properties of the wet flux layer should be such as to anchor the particles of brazing powder which fall uniformly on the disk surfaces throughout their extents If the wet flux layer is too thick in dimension or too fluid or too low in viscosity it will permit the particles to float together so as to form lumps The viscosity and thickness of the flux coating should be adjusted so that there is no tendency for the brazing metal particles to wash about when the disks are tipped slightly The proportions of the flux and water components of the fluxing solution may be varied as required for the just
mentioned purpose. It is also necessary to adjust the thickness of the flux coating and its composition and tbe density with which the brazing particles are distributed These factors should be adjusted so that after the disks are brazed together to make the cladmetal, the bond between the layers is in the form of a flux slag which forms a highly dispersed phase mingled with a matrix of the brazing metal and which does not interfere materially with the brazed bond during the deep drawing of the cladmetal disks The appearance of the bond may be examined by pulling apart the layers of the finished cladmetal, which is possible by using adequate force, and using this as a guide, proper adjustments in the applications of the flux solution and the brazing particles may be made Relatively little brazing metal is required and its use should be limited preferably to the minimum required to effect an adequate bond. The brazing metal used should be a lowtemperature brazing alloy These usually contain silver and are relatively expensive but the small amount used by the present invention makes such brazing metal practical One such alloy that has been used is "Easy-Flo," a proprietary brazing alloy manufactured by Handy and Harman, having a melting range between 1160 and 11750 F and having the following composition, by weight:Silver 50 % Copper 15 5 %'. Zinc 16 5 % Cadmium 18 % This "Easy-Flo" alloy has a minimum tensile strength of 60,000 p s i It may be obtained in powder form of varying degrees of fineness. Other brazing alloys may be used providing they have melting range temperatures low enough to permit their use with the previously described pressure-brazing procedure, using the special fixture, in such a fashion that brazing may be effected 70 without resorting to temperature and time factors causing the grain size of the copper to grow to an objectionable degree. The various disks are assembled by superimposing one on another, in their 75 proper relation, whereby to form a pack which is then placed in the fixture previously described and pressure-brazed in the described manner. With the metal specifically disclosed 80 hereinabove, namely, the stainless steel and copper components, proper brazing is effected by maintaining the molten bath 9, which may be a suitable salt, at a temperature of around 1450 F, and by allowing 85 the fixture, containing the pack, to remain in the bath until the pack reaches a temperature throughout high enough to fuse the brazing material component The thin sheet metal diaphragms and the fact that 90 all of the cladmetal layers are in tight contact throughout their areas, permit rapid attainment of adequate brazing temperaf tures throughout
the pack's thickness As soon as the brazing temperature is reached 95 throughout, the fixture is removed from the molten salt bath and without relaxing on the vacuum the fixture and its pack are permitted to cool Preferably the fixture is quenched in oil or water so as to get the 100 copper component rapidly below its temperature of rapid grain growth. Since the copper components started out with a relatively high temper, the described brazing temperatures are high 105 enough to effect recrystallization of the eopper's grain structure The recrystallized grains are, of course, very fine and before they can grow to an objectionable size the fixture and pack may be removed 110 from the heating liquid and quenched. It is to be understood that the metal from which the described fixture is constructed and the nature of the molten salt bath should be such as to avoid rapid de 115 struction of the fixture Ordinarily the fixture may be reused a number of times. The described fixture and process may be used to clad base metal which is too thick to flex under the atmospheric pres 120 sure, providing the cladding metal is flexible to this degree In such an instance only a single triplex product or two duplex products can be produced at one time within the fixture Cladmetal of great sur 125 face area can be produced by the use of an appropriately sized fixture and a heating bath of adequate size Cladmetal pieces of small area may conveniently be arranged within the fixture as a number of trans 130 784,953 versely interspaced piles with the diaphragms bearing against the ends of all of the piles In all cases the entire pile and the cladmetal components should be 5thin enough to permit the atmospheric pressure to flex the components sufficiently to conform their interfaces with each other throughout their areas In this fashion each pile or pack is in effect made into a solid block of metal until atmospheric pressure is returned to the inside of the fixture. When the base metal is thick and not intended to be deep drawn or formed it is immaterial whether or not a large grain size is developed, and in some eases an orange peel effect may not be of importance even though it is developed Also this kind of defect may not be a problem when the base metal is other than copper. However, one great advantage of the present invention is its ability to clad eopper or cuprous alloys without incidentally developing a grain size large enough to cause the orange peel effect during deep drawing and forming. It is to be understood that when referring to "fine" grain size that this means a grain size small enough to prevent orange peeling under the conditions of gauge, type and form of the drawing or forming and similar factors involved.
The brazing powder must be uniformly distributed and other methods for applying it may be praeticable For example, electrostatic deposition methods have been used. Tightness of the described fixture may be enhanced by the use of a thin layer of heavy oil of the type intended for high temperature lubricating use A graphited oil may be used When such material is applied between the inter-faces of the diaphragms and rings substantial airtightness results. Due to the rapidity with which the brazing cycle is completed it is unnecessary to use a stainless steel of the type stabilized against carbide precipitation, with its attendant higher cost as compared to ordinary stainless steel. It has been indicated that low-temperature brazing alloys are ordinarily of relatively high silver content This does not mean that the silver content necessarily must be high in all eases and it is possible that satisfactory brazing alloys may be developed which contain little or no silver but which have an adequately low mielting range together with the required strength. When using the fixture the atmospheric pressure bears on the hot liquid and it is the latter that presses the diaphragms together Thus, the cladmetal components inside of the fixture are pressed together, in effect, by the hot liquid which, therefore, applies both the brazing heat and the pressure. It is apparent from the foregoing that when reference is made herein to the outer 70 most layers as being within sheet metal gauges, or thin enough to flex under atmospheric pressure, that either of the layers of a duplex product, for example, may be the outermost layer referred to Ordin 75 arily this would be the layer exposed to conditions requiring a stainless characteristic and, therefore, it has been called the outermost layer At least one of the lavers should have the flexibility described 80 The pressure used should be sufficient to flex this layer and since atmospheric pressure is used the maximum stiffness of the outermost layer is fixed by this factor. With thinner and more flexible sheet 85 material a lesser pressure becomes sufficient, such as is obtained by partial evacuation of the described fixture The amount of pressure required is easily determined because insufficient pressure is made 90 evident by unbonded areas in the final product, showing incomplete face-to-face contact throughout the layers while in thefixture. The liquid heating bath may be a molten 95 salt of the type used in heat treating In order to minimize damage to the fixture, the salt should preferably be neutral, that is neither oxidizing nor carburizing in its effect on the fixture The salt should 100 possess the usual properties characteristic of good heat treating salts in
that it should provide good heat transfer be chemically stable and free from objectionable fumes at operating temperature, be readily re 15 movable from heat treated parts and be suitably fluid at the operating temperature This last characteristic is particularly important in the cladding process as described above It has been found in 110 practising the present invention that a fixture imperfectly sealed before immersion in the salt bath will often show a decided improvement in the quality of the seal as shown by a decrease of internal pressure, 115 after being placed in the molten salt This phenomenon is attributed to the action of the salt bath in freezing around the fixture and sealing off small leaks During continued immersion of the fixture in the salt 120 bath the initial crust of frozen salts around the fixture remielts but even in its molten state the salt is effective in sealing off small leaks in the fixture Chlorile salts have been successfully used A mix 125 ture of 60 % sodium chloride and 40 % potassium chloride by weigh+ is preferret. altihough 45 % sodium chloride and 5 % potassium chloride has been successfully used Other salt mixtures or different 130 784,953 types of heating baths may prove to be I suitable.
* GB784954 (A)
Description: GB784954 (A) ? 1957-10-23
Description of GB784954 (A)
PATENT SPECIFICATION Date of Application and filing Complete Specification: July 14, 1955. 784,954 No 20456/55.
Application made in United States of America on Aug 16, 1954. Complete Specification Published: Oct 23, 1957. Index at acceptance:-Classes 79 ( 2), C( 4:14:19); and 124, C 2 C. International Classification:-B 25 d, B 62 d. COMPLETE SPECIFICATION Drill Carriage I, JOHN WOODFIN BURRESS, a Citizen of the United States of America of P O Box 719, Roanoke, State of Virginia, United States of America, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a wagon drill carriage and more specifically provides an improved mounting for a rock drill wherein the drill and the feeding mechanism therefor is supported in the desired position in a most satisfactory manner and yet may be moved to a new location in an expeditious manner. An object of this invention is to provide a drill carriage mounted on endless trackways that form traction members for the carriage and are driven through the use of air operated motors. Another object of this invention is to provide an improved drill carriage mounted on tread-like traction members wherein the traction members are movable in a vertical plane whereby retaining the drill in the desired position regardless of the slope of the supporting surface engaged by the traction members. Another object of the invention is to provide an improved drill carriage mounted on tread-like traction members wherein the drill supporting arm may be adjusted to a predetermined angle and maintained in that position by fluid actuated means as the traction members move in separate vertical planes during the travel of the carriage over uneven ground. From one aspect, a drill carriage according to the invention comprises a transverse axle, a pair of elongated frame members each pivotally secured to one end of the axle, an endless flexible tread supported on each of the frame members, power means for independent driving the treads, a support lPrice I = arm secured to the axle for adjustably supporting a drill, and means for adjusting the axle in relation to the frame members having the treads thereont. From another aspect, the invention pro 50 vides a drill carriage comprising a pair of spaced elongated longitudinal frame members, ground engaging means movably supporting said frame members, a transverse member pivotally interconnecting said frame 55 members for permitting vertical swinging movement of said frame members, means for supporting a drill from said transverse member, and means for adjusting the transverse member in relation to the frame members 60
From yet another aspect, a drill carriage according to the invention comprises a pair of elongated mobile frame members, a transverse axle interconnecting said frame members, said frame members being pivotally 65 attached to said axle for free swinging movement in a vertical plane, and a drill supporting arm rigid with said axle to permit unrestricted relative movement between the drill supporting arm and the frame members, 70 and means for rotating the axle in relation to the frame members for varying the angle of the supporting arm. The drill carriage may be ef tubular construction to permit the passage of air to 75 various air operated motor thereon, thereby eliminating any excessive air hose and preventing any chaffing and pinching damage to said air hose. It may also have a transverse axle mount go ing endless treads on each end thereof wherein the treads are independently movable about the axle in a vertical plane and the central portion of the axle is provided with an extending arm for supporting the drill, Hi drill motor and drill control mechanism. Further, on a drill carriage that is operated by air motors the carriage may be provided with a drawbar for attachment of an air compressor thereby making the carriage 90 784,954 self-driven thereby eliminating the use of a separate power instrument, such as a tractor, for moving the carriage to a desired location. Other important features of the present invention will be found in its relatively simple construction, ruggedness, its adaptability to various terrains, its ability to be selfpropelled its ease of operation and its relatively inexpensive initial cost of manufacture and low maintenance cost. Other parts of the invention are embodied in the preferred form which will now be described in some detail with reference to the accompanying drawings in which:Fig I is a side elevational view showing the drill carriage of the present invention, with the drill and control mechanism mounted thereon; Fig 2 is a top plan view of the construction of Fig 1 showing the relationship of the endless treads and other structural features of the carriage of the present invention: Fig 3 is a front elevational view showing the carriage of the present invention with the drill and drill control mechanism removed and showing the dotted line adjustment positions of the endless tread; Fig 4 is a longitudinal, vertical sectional view taken substantially upon a plane passing along section line 4-4 of Fig 3 showing the structural details of the tubular axle, tubular supporting arm and other structural features: Fig 5 is a longitudinal vertical section taken substantially upon a plane passing along section line 5-5 of Fig 2 showing the structural
details of the tread adjusting mechanism and the adjusted positions of the tread; Fig 6 is a transverse, vertical sectional view taken substantially upon a plane passing along section line 6-6 of Fig 2 showing the structural details of the tubular axle for permitting the passage of air therethrough for driving the propelling motors and the drill control motor; and Fig 7 is a schematic side elevational view showing the carriage of the present invention with the drill positioned in substantially horizontal position. Referring now specifically to the drawings, it will be seen that the numeral 10 generally designates the wagon drill carriage of the present invention for supporting a rock drill generally indicated by the numeral 12 along with the control mechanism and the driving mechanism therefor. The drill mechanism 12 generally includes a drill 14, a drill driving motor 16, an elongated frame member 18 having an endless chain therein for moving the drill 14 and the drill driving motor 16 for advancing the drill 14 as desired A control motor 20 is provided for advancing the drill 14 The motor 16 for the drill 14 and the motor 20 for controlling the position of the drill 14 are driven by air from suitable flexible hoses 22. Further, a suitable control valve is provided for controlling the action of the drill and the position of the drill and the frame 18 70 is pivotally secured to a supporting arm 24 for positioning at any position in a vertical plane wherein the drill 14 may be utilized in various positions as desired in various drilling operations 75 The carriage 10 for supporting the drilling mechanism 18 includes a generally tubular, horizontally disposed, transverse axle 26 (Fig 6) journalled in bearings 28 on the upper surface of oppositely disposed sup-80 porting frames 30 The supporting frames are generally elongated and include an enlarged idler roller 32 (Figs 1 and 4) at the fornvard end thereof and an enlarged driving sprocket 34 at the rear end thereof 85 for receiving an endless tread chain 36 having traction blocks 38 thereon constructed of suitable resilient material The members 32 and 34 form a guide and driving means for the endless tread 36 and smaller idler pulley 90 is provided for positioning centrally under the upper run c' the endless tread 36 wherein the tread 36 will be driven by the sprocket 34 at the rear thereof thereby driving the carriage 10 over the ground The axle 26 is 95 provided at each end with a cap 42 (Fig 6) for securing the bearings 28 on the end of the axle 26. Each of the sprockets 34 is provided with an inwardly extending shaft 44 (Fig 6) hav 100 ing an enlarged sprocket gear 46 (Fig 5) on the end thereof that is in alignment with a smaller drive sprocket 48 A sprocket chain encircles the smaller drive sprocket 48 and the
enlarged sprocket 46 The sprocket 105 48 is secured to the driveshaft of an air motor 52 (Figs 1 and 4) having a control valve operated by a handle 54 and an inlet conduit 56 (see Fig 1) connected to one motor whereby the air motor 52 is driven 110 thereby driving the tread 36 An air motor 52 is positioned at each side of the carriage and is mounted on suitable brackets 58 (Fig 2) The two air motors 52 drive the treads 36 in independent relation and indivi 115 dually of each other wherein by manipulation of the control valve handles 54 the direction of movement of the carriage 10 may be easily guided, reversed or changed. The tubular axle 26 (Fig 6) is provided 120 with an enlarged central portion 60 that has a nair of lugs 62 extending from one side thereof The drill carriage support arm 24 (Fig 4) extends from this portion 60 and is provided with a longitudinal passage 64 125 that is in communication with the tubular passage 66 in the centre of the tubular axle 26 Adjacent the outer end of the drill support arm 24 is a fitting 68 that is attached to an air hose 70 (Fig 1) for supplying the 130 784,954 control motor 20 on the drill mechanism 18. The entire carriage 10 is supplied with air from an air inlet line 72 (Figs 2 and 4) that is connected with an oil cylinder 74 and the oil cylinder 74 (Fig 4) is in communication with the interior of the tubular axle 26 by a conduit 76 (Fig 2) The conduit 76 is attached to a fitting 78 adjacent one end of the axle and the air proceeds through the passage 66 (Fig 4) into the passage 64 in the support member and also passes through a fitting 78 at the other end of the axle 26 into the fluid conduit 56 (Fig 1) that supplies one of the motors 52 The other air motor 52 is supplied from a direct take-off from the oil cylinder 74 A line 80 by-passes. the oil cylinder 74 and is connected to a flexible hose 82 that supplies air for blowing out the hole that is being drilled by the drill 14 As this blow-out air is necessary and the oil that is normally in the air that passes through the oil cylinder 74 is undesirable, the air for blowing out the hole drilled by the drill is in a clean condition. Secured between the lugs 62 (Fig 6) on the axle 26 is a drawbar 84 (Figs 1 and 4) having a suitable hitch 86 on, the end thereof wherein a wheeled air compressor may be attached thereby providing a self-propelled unit wherein the air compressor will supply air through the inlet line 72 for driving the motors 52 and operating the drill mechanism 18. Secured between the brackets 58 (Fig 2) for supporting the motors 52, is a transverse rod 88 having a sliding collar 90 provided with upstanding lugs 92 for supporting and guiding the drawbar 84 during manoeuvering of the carriage 10 thereby assuring that the drawbar 84 will not become entangled with the other mechanism of the carriage and
assuring that the drawbar 84 will within limits pivot about pivot bolts 94 (Fig. 4) thereby retaining the compressor in the desired relation to the carriage 10. The outer end of the support member 24 is provided with an enlarged yoke 96 (Fig. 2) having a bearing 98 for pivotally supporting a bearing 100 that supports the elongated frame 18 wherein the elongated frame 18 is adjustably secured to the support member 24 for manipulation of the drill 14 in the desired manner. In order to retain the support arm (or member) 24 in a constant angular relation to the ground, means is provided for pivoting the supporting frame and the treads 36 about the bearing 28 thereby retaining the arm 24 in an angular position regardless of the ter6 rain on which the carriage 10 is supported during the drilling and moving operation. This is accomplished by the provision of a pair of spacer sleeves 102 rotatably mounted on the axle 26 and a pair of sleeves 104 (Fig. 5) keyed to the axle 26 by a key 106 and clamp means 108 Each of the sleeves 104 is provided with an enlarged offset arm 110 having lugs 112 thereon for receiving a pivot bolt 114 Each of the frames 30 is provided with an inwardly projecting bracket 116 70 (Fig 3) having upstanding lugs 118 (Fig 4) thereon for receiving a pivot bolt 120 (Fig. 2) A double-acting hydraulic cylinder 122 is provided with a projecting lug 124 (Fig. 2) that is pivoted on the pivot bolt 114 (Fig 75 4) on the projecting arm 110 A piston rod 126 projects from the cylinder 122 and includes a pivot lug 128 (Fig 2) pivotally mounted on the pivot bolt 120 on the bracket 118 Each of the piston and cylinder 80 arrangements is provided with interconnecting conduits 130 for expanding and contracting the piston 126 in relation to the cylinder 122 A manually actuated hydraulic pump 132 is provided on a bracket 134 that is 85 secured to a mounting arm 136 extending from the bracket 116 to the sleeve 102 It will be seen that each bracket 116 is provided with a brace arm 136 wherein the sleeves 102 will pivot with the endless tread 90 36 The manual-hydraulic pump 132 is provided with an operating handle 138 and a control valve 140 for manipulating the expansion and contraction of the pistons 126 through suitable conduits 95 The drill carriage unit 10 of the present invention includes a pair of spaced elongated frames 30, each including a movable endless crawler tread 36, each frame 30 being mounted for free pivotal movement, in a vertical 100 plan, about the ends of a connecting axle 26 with the latter being independently rotatable with the respect to
the tread frames The treads 36 are individually movable about the frames by separate driving motors 52, each 105 being supported by and movable with the frame 30 These motors 52 may be operated independently of each other, in the same or opposite directions at varying speeds or in the same direction at a common speed, the 110 purpose being to propel and steer the unit over the ground. Affixed at right angles to the axle 26 and midway between the spaced treads is an outwardly projecting arm 24 to the extreme end 115 of which is detachably secured a rock drill unit 12 and it will be apparent that upon rotary movement of the axle 26 with respect to the treads 36 the arm 24 may be adjusted at any desired angle, holding the drill unit 120 12 in its proper drilling position. Rotary movement of the axle 26 to the treads 36 is accomplished by a pair of hydraulically expansible cylinders and pistons 122 forming separate units, the cylinder of 125 each unit being pivotally connected to an upstanding arm 124 detachably secured, in a fixed relation, to the axle 26 adjacent the tread frame 30 while the piston is connected through a piston rod 126 to a bracket 116 130 784,954 formed on the tread frame 30 Pressure fluid is supplied to the cylinders through hand operated pump 132 at which time there is a movement of the piston relative to the cylinder separating the two and imparting a rotary movement of the axle 26 and the arm 24 The cylinders 122 are connected in such a manner that operation of one pump serves to supply operating fluid to both cylinders. When the axle 26 has been rotated and the arm 24 positioned at the desired drilling angle a suitable hand operated valve in a pipe connection between the two cylinders is closed confining within the cylinders and their connections the desired amount of pressure fluid. When the arm 24 has been adjusted to its proper drilling angle and the unit is moved over uneven ground causing the treads 36 to move up and down in their separate vertical planes the pistons and cylinders are moved one to the other, causing a surging action or a transfer of fluid from one cylinder to the other, the result being that the arm 24 is maintained at the desired angle regardless of the positions assumed by the treads 36 in following the ground surface. Obviously, suitable grease fittings, and lubrication lines may be provided where needed and where it is deemed necessary and the particular arrangement of the air conduits may be altered as deemed necessary in order to facilitate the supply of air to the various air motors in the most efficient manner with the minimum number of long exposed air hoses thereby eliminating all possible damage to said air hoses. In operation, the drill carriage of the present invention may be self-propelled adjusted and operated by a single person wherein the
drill carriage may proceed to the point of drilling and the drill together with the supporting frame therefor may be easily driven and set up to the desired position and the carriage together with the drill support arm maintained in a stable, rigid condition by adjusting the vertical swinging position of the tracks 36 thereby permitting the drilling operation to be conducted with a maximum of efficiency and a minimum of labour and damage to the drilling equipment. While only air operated motors have been illustrated for operation of the drill and drill carriage, it will be understood that other sources of power may be used in some circumstances In some drilling areas an air supply may not be readily available and it will be desirable to use other sources of power This is especially true of drilling operations in mines where an electric supply is usually available In this case and in other conditions, electric motors may be provided for driving the drill carriage and operating the drill. From the foregoing, the construction and operation of the device will be readily understood and further explanation is believed to be unnecessary However, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to 70 limit the invention to the exact construction shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the appended claims 75
* GB784955 (A)
Description: GB784955 (A) ? 1957-10-23
A new or improved method of making circular sound tracks
Description of GB784955 (A)
PATENT SPECIFICATION Date of Application and filing Complete Specification: July 29, 1955. r)2 2 f 1 Application made in France on Sept10, 1954. Complete Specification Published: Oct 23, 1957. Index at acceptance:-Class 40 ( 2), D 3 C 3 (C:J 1). International Classification:-C 10 j. 784,955 No 22010/55. COMPLETE SPECIFICATION A New or Improved Method of Making Circular Sound Tracks I, YVES LEMOINE, of Marigny, DeuxSevres, France, of French nationality, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a method of making circular sound tracks which is particularly suitable for producing modulating discs for photo-electric musical instruments. It is known that such musical instruments comprise a light source emitting a parallel light beam in the path of which shutters can be moved to control the passage of one or several spots falling on one or several tracks of a modulating disc and thence onto a photo-electric cell. It will be evident that for good sound quality each track must be as regular as possible, that is to say it must consist of a certain number of signals of determined form distributed regularly round a circumference. In the production of these tracks, expedients have hitherto been tried to obtain regularity The method basically surest for theoretically reliable and cheap reproduction of the discs consists in photographing the tracks on a sensitive plate In practice the method meets with grave difficulties owing the the relatively large size of the surface of the disc. The method which has been the most satisfactory in principle up to now has been to photograph at regular intervals a light source of determined shape mounted on the end of a clock hand so as to obtain a series of identical signals at regular intervals on the same plate This method is evidentally very slow. Another method that has previously been proposed employs a rotatable shutter for varying the quantity of light projected onto a scanning spot on a photographic disc rotated at a speed equal to a sub-multiple of the speed of rotation of the shutter. lPrice 3/6 l According to the invention, each sound track is recorded by projecting a series of images of a wave form onto a photographic disc by modulating a light source at a constant frequency whilst moving the light 50 source in a circular path relatively to the disc
at a speed of rotation equal to a sub-multiple of the frequency of modulation of the light source. The images may be projected images of a 55 prepared wave form such that the wave length of each image is equal to the circumference of the circular track divided by the ratio of the speed of rotation of the light source to the frequency of modulation Al 60 ternatively, they may be formed by the trace of a variable light spot projected onto the disc from the variable light source. The change from one note to another is effected by changing the track To pass from 65 one track to another in accordance with the invention therefore, it is sufficient to alter the distance of the light source from the axis of rotation at the same time altering the excitation frequency of the light source so 70 as to alter the number of complete wave forms in the track correspondingly. In the same way an alteration of timbre is obtained by altering the shape of the prepared wave form by changing a diaphragm 75 arranged in the optical system that forms the image of the light source on the disc. From a practical point of view, the light source should be sufficiently stable and durable to give satisfactory and economical op 85 eration It is advantageous, but not essential, to use a gas tube fed from a frequency stabilised oscillatory circuit The stability is regulated by means of an amplifier and a loud speaker which enables the corresponding 85 note to be heard and verified by the production of a stationary stroboscopic image of the track. As previously indicated, instead of being built up from successive images of a pre 90 784,955 pared wave form the sound track may be a trace of a variable light spot projected from the modulated light source It may thus take the form of a continuous band of variable optical density This could for example be a band of constant width having an optical density which varies from one cross section to another but remains constant throughout any given cross section Or it could be composed of a clear part separated from a dark part by a wavy line, the mean density of the clear and dark parts in any transverse section being equal to the above-mentioned constant density throughout a given section of a band of the type previously referred to. (Bands of the last-mentioned type are also known as "variable surface tracks" as compared with "variable density tracks" properly so called) In both cases, the variation in the density of the track corresponds to the modulation of the illumination of a gas-tube or even of an incandescent lamp by means of a stroboscopic system as described above. Another modification consists in the employment of a musical note having a single very stable frequency for producing a number of tracks
The single note is recorded on a magneto phone strip and then the strip is scanned at different speeds so as to obtain notes of different frequencies Control of the scanning speed is obtained by means of a synchronous motor fed by an oscillator of variable frequency which is itself very stable. The modulation voltage obtained as the output of the magnetic recorder-reproducer, after suitable amplification, is applied to a gas-tube (or incandescent lamp) the image of the light from which, thus modulated, is applied to the)photographic disc previously described. This process could be extended to the reproduction of any tone, starting from the registration of the above-mentioned tone on a magnetic strip. It is even possible to group on the same strip not only several tones of the same pitch and different timbres but also several notes of different frequencies the track thus formed corresponding in the photo-electric musical instrument to the emission of the corresponding chord. It will thus be seen that this method has a practically unlimited field of application, the discs being equally useful in photo-electric organs, or considered as novel musical instruments themselves. Finally, instead of a disc, any solid of revolution, for example a cylinder or cone, can be used as the support for the tracks, and could thus carry a greater number of tracks than a disc. The invention will be better understood from the following description with reference to the accompanying drawing which shows a diagrammatic section of a simple construction for carrying out the method of the invention. This drawing shows a circular photo. graphic plate 2 and a circular plate 3 moun 70 ted in a fixed frame 1, the plate 3 being coaxial with the plate 2 and carrying a light source 4 The light source 4 is fixed to the plate 3 by any convenient means which will enable its distance from the axis of rotation 75 to be adjusted An image of a prepared wave form is projected on to the plate 2 by an optical system 5 having a diaphragm 6 which carries the prepared wave form. The plate 3 is driven through a suitable 80 transmission such as a belt 8 by a synchronous motor 9 The lamp 4 is connected through a rotatable contact device, not shown, to an oscillatory circuit 10 which also feeds an amplifier 11 and loudspeaker 12 for 85 verifying the frequency It is to be observed that, in order that the successive images of the prepared wave form may join up correctly, the wave-length of each image must be equal to the circumference of the circular 90 path divided by the ratio of the speed of rotation of the
light source to the frequency of the modulation. As previously explained, the oscillation frequency of the circuit 10, checked by com 95 paring the note given by the loud-speaker 12 with a tuned musical instrument, determines the number of signals 7 on the plate 2 as a function of the speed of rotation of the plate 3 On the one hand, the note is altered by 100 adjusting the distance of the lamp 4 from the axis and the oscillation frequency of 10 and on the other hand, the tone is altered by changing the diaphragm 6. For example, to register a track contain 105 ing 220 wave-lengths, the oscillator 10 is adjusted to 1100 cycles per second The plate 3 rotates at the rate of 5 revolutions per second The number of wave-lengths on the plate 2 is thus equal to 100:5 = 220 For 110 a clear track it is naturally necessary that the 220 wave forms should be produced at fixed points, that is that the track should be truly immobile The immobility can easily be checked by the naked eye with the aid of 115 persistence of vision. The construction in which the light source rotates and the photographic plate is fixed could evidently be replaced by an inverse construction in which only the photographic 120 plate rotates. Instead of the gas-tube any other light source that can be excited with a controllable frequency may be used. In the alternative form of the invention in 125 which the images of wave forms are traces of a variable light spot, the diaphragm 6 with its prepared wave form is omitted and its place is taken by some device which focusses a scanning spot on to the disc The 130 784,955 scanning spot is modulated in accordance with the desired wave form and thus produces a continuous trace on the disc which is photographically recorded in known manner.
* GB784956 (A)
Description: GB784956 (A) ? 1957-10-23
Spherical roller bearing
Description of GB784956 (A)
PATENT SPECIFICATION 47 4 v Y & ft Or, " 4 784,956 Date of filing Complete Specification: Feb 6, 1956. Application Dote: Aug 5, 1955. Complete Specification Published: Oct 23, 1957. Index at acceptance:-Class 12 ( 1), A 5 C( 1: 3). International Classification:-FO 6 c. COMPLETE SPECIFICATION Spherical Roller Bearing I, TOM EDGERTON CLARKE,HIRST, 163 Woodside Avenue, Coventry, British, do hereby declare the invention, for which I pray that a patent may be granted,to me, and the method by which it is to be performed, to be particularly described in, and by the following statemernt: This invention relates to spherical roller bearings My object being to produce a bearing of high load capacity to function efficiently at high speed and,o allow the outer or inner races of the bearing to move longitudinally relative to one another to accommodate thermal expansion in regard to the longitudinal position of bearing housing or shaft A further object of the invention is to reduce many causes of friction in a bearing by allowing for roller distortion when under load, by the roller tracks formation, by waisted shouldered pins and cage construction. On the accompanying drawings Fig 1 is a side view, Fig 2 a section with cylindrical inner race track on Line A O B of Fig 1, Fig 2 A a section with cylindrical outer race track Fig 3 la section and end view of the roller, Fig 4 a section and end view of the waisted roller pins, Fig 5 a plan view of the rollers on the race tracks, Fig 6 a section showing the alternative construction of a roller with cylindrical end extensions free to rotate im cage side members, Fig 7 a section with such cage side members held together by shouldered pins On all views the same numbers will refer to the same part. On, Fig 2, 1 is the outer member of the bearing with the radius 'C of the outer race track struck from the centre of the bearing and the inner race track cylindrical for an application where it is desired this outer memher may be required to move axially relative to the inner member Alternatively on Fig. 2 A, 1 is the outer member of the bearing with the race track cylindrical for an application where it is desired the inner member may be required to move axially relative to the outer member, and the
inner race track 2 of the bearing has a radius D struck from a lPrice 3 s 6 d l centre on the centre line of the bearing The radius C and the radius D are each greater than the radius E of the roller shown in Fig 3 50 On Fig 2 and 2 A, 3 is the hollow roller, 4 is the waisted shoulder pin and is shown with its ends rivetted or spun over to take hold of the cage side member 5 On Fig 4 is shown the diameter at F to be greaterthan 55 at the centre line G with the shape from points J to K may be of radius H struck from centre line G and these waisted shouldered roller pins may have a central hole. Fig:6 shows the assembly of the alternative 60 roller,as 3 A with cylindrical extensions free to rotate in cage side members Fig,7 is shown the assembly of the alternative shouldered pin 4 A in cage side members 5.
* GB784957 (A)
Description: GB784957 (A) ? 1957-10-23
Description of GB784957 (A)
PATENT SPECIFICATION Date of Application and filing Complete Specification: Aug 8, 1955. 784,957 No 22755/55. Application made in United States of America on Sept 14, 1954. Complete Specification Published: Oct 23, 1957. Index at acceptance:-Class 37, D 3 (B:E:G 2:G 3:1 H 2:H 3 H 4:H 5). International Classification:-D 011 l, 011. COMPLETE SPECIFICATION Dry Capacitor We, P R MALLORY & Co, INC, a Corporation organized and
existing under the Laws of the State of Delaware, United States of America, located at 3029, East Washington Street, Indianapolis 6, State of Indiana, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to dry capacitors, and more particularly to capacitors employing film forming electrodes, such as tantalum. An object of the invention is to provide an improved high capacity condenser employing dry solid elements. A specific object is the provision of improved tantalum capacitors which are free of liquid electrolyte, which are rugged, which may be operated over a wide range of temperature, and which may be simply and economically manufactured. Further objects will be apparent from the disclosure and the drawing which illustrates a view of a tantalum capacitor embodying the invention. Broadly, the invention comprises a capacitor having one or more film forming electrodes, such as tantalum, in intimate contact with a sulphate, such as tin, bismuth or antimony sulphate. We have found that the characteristics of tin sulphate are such as to provide a low resistance electrolytically conductive element which, in contact with anodized element of a metal such as tantalum, allows the provision of an electrolytic capacitance without the presence of an aqueous electrolyte. In a preferred combination for use as a direct current condenser, an anodized disc of tantalum is held in pressure contact with a disc of tin sulphate (Sn SOQ), the opposite surface of which is in contact with an inert non-film forming electrode such as graphite. Tin sulphate is the preferred solid ionic conlPrice, ductor and film maintaining element Although not as desirable, the hygroscopic sulphates such as bismuth or antimony sulphate can be used in some applications under specially controlled conditions 50 Tantalum is the preferred anode material but other suitable film forming metals may, be used For the cathode, graphite may be used as well as silver or silver coated metals or cast non-porous silicon 55 Tantalum directly forms a polarizing layer when connected as the anode in contact with tin sulphate; alternatively the tantalum may be anodized prior to assembly in a suitable aqueous solution, such as sulphuric acid 60 In order to obtain maximum capacitance from tantalum, which is expensive, it is preferable to use both sides, as by clamping it between two tin sulphate discs The capacitance of the tantalum may be increased by 65 etching electrolytically in an acid fluoride salt. In order to describe an embodiment of the invention in detail,
reference is made to the accompanying drawing in which non-porous graphite discs 1 and 2 are in contact with tin 70 sulphate discs 3 and 4, which contact opposite sides of anodized tantalum disc 5 In the preparation of the tin sulphate elements, a pressure of 20,000 lbs per square inch is applied in order to obtain hard and strong 75 discs The elements are mounted on rivet 6 which is insulated from the elements by plastic sleeve 8 of polyethylene or a higher temperature inert insulator, if desired Negative terminal 7 is placed under the rivet to 80 provide contact with the graphite discs, the positive terminal being provided by a tab extending from the tantalum disc and on which is pressed a solderable metal element 9 to facilitate connecting in a circuit After 85 the unit is assembled, the rivet is pressed to firmly bind the assembly together. In order to avoid atmospheric moisture effects, the entire assembly can be dipped in a silicone varnish and baked hard, or covered 90 784,957 with a plastic casting of an epoxy resin. Other suitable enclosures may also be employed. The capacitance of the unit is equivalent to that obtained from tantalum in an aqueous electrolyte. The structure illustrated in the drawing is shown merely as an example and the units may be constructed in various forms Very low series resistance can be obtained by pressing the tin sulphate into a glass fibre or plastic screen at high pressure to provide a very thin element For some applications, the cathode may be in the form of a cup of cast non-porous commercial silicon which also serves as the cell container. For alternating current operation, the capacitors are constructed with two filmforminj electrodes of equal area in contact with the sulphate.