“ANALYSIS OF GEAR MANUFACTURING IN PRODUCTION LINE”

SUBMITTED BY:

• ARVIND RAJPUT(110480119018)

• MILAN PATEL(110480119033)

• AKASH PATEL(110480119013)

• DHARMESH DHANDHUKIYA(110480119073)

GUIDED BY :

• Mrs. VIBHA PATEL

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ABSTRACT In the respective company, where we had gone through industrial visit, we observed that at the time of manufacturing of gear in the inspection department, I came across problem of rejection gear because of internal crack in the tooth root, and the chipping on the tip of tooth.Here on the bases of literature review, we have an idea that impregnates the use of Shot peening treatment and carburizing treatment ,by employing this the internal crack of tooth-rooth and chipping of tooth is removed.Accordingly, the surface of the gear is carburized and the gear is strengthened by imparting residual stress, with the residual stress in the region With a surface depth of 5 µm to 20 µm being —1000MPa or less, and the residual stress in the region with a surface depth of 50 µm to 150 µm being —1000 MPa or greater.We are sure that with the help of solution company gain some profit by impletation of the of the Shot peening treatment and get a proper solution.

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INTRODUCTION Gears are used extensively for transmission of power. They find application in : Automobile, gear boxes, machine tool geared motors etc, agricultural machinery. To meet the strenuous service conditions the gears should have : robust construction, reliable performance, high efficiency, economy and long life. The gear drive should ensure high load carrying capacity at constant velocity ratio. To meet all above conditions, the gear manufacture has become a highly specialized.

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GEARS : Basic Features

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Common types of GEARS

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General Application of GEARS Speed and feed gear boxes in machine tools. Gear boxes of automobiles. Speed drives in textile, jute and similar machineries. Speed and feed drives of various material forming machines. Machineries for mining, tea processing etc. Industrial robots and toys. Precision equipment ; Clocks, Watches, meters etc

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Specification of GearsGears are general specified by : Types of the Gear; e.g., spur, bevel , spiral etc. Material; Metal( Fe, Non Fe), nonmetal, composite. Size or major dimensions; m, z_g, θ, b, B. Geometry; pressure angle, A, B etc. Special features, if any;

● bevelling● crowning● tooth rounding

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Manufacture of GEARSManufacturing stages, depending upon, types, material, and desired quality of Gears;

Preforming the blanks with or without teeth. Annealing of the blank, if required. Preparation of the finished blank by machining. Production or finishing of preformed teeth by machining or rolling. Full or surface hardening of the machined teeth, if required. Finishing of teeth. Inspection of the finished gear.

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LITRETURE REVIEW1. Multiple operation gear manufacturing apparatus with common work axis [EP 1843869 A2] :The Author Brian M. Fitzgerald, Jeffrey A. Rynders has work is related to component manufacture methods, machinery and tooling and more particularly to an improved gear manufacture method, tooling and machinery. Mass production of components, such as gears and the like, typically includes a series of machines integrally linked in a production line. Such machines may include cutters, grinders, shavers, heat treat and the like. Generally, a raw component is loaded at the beginning of the line and each machine performs a specific manufacturing process on the raw component, ultimately producing a finished product. Each step of the process includes an associated cycle-time. The cycle-time is the amount of time it takes a particular machine to perform its process, including loading and unloading of a component. The cycle-time translates directly into manufacturing costs and thus component price. In addition to cycle-times, each machine has associated costs.Therefore, it is desirable in the industry to provide improved machinery for producing components, such as gears. The improved machinery should limit the need for additional, supporting machines, reduce the overall capital investment and maintenance costs, as well as reduce the cycle time of component manufacture.

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LITRETURE REVIEW 2. Method for manufacturing multi-stage gear, and multi-stage gear [EP 2730811 A1] : The author Takuya Sukeda has work is related to a method for manufacturing a multistage

gear including gears having different diameters formed on an outer peripheral surface of a hollow cylindrical workpiece, and the multi-stage gear.

the problem of providing a method for manufacturing a multi-stage gear for which there is

no gap between a smalldiameter gear and a large-diameter gear, and addresses the problem of providing this multi-stage gear. This method manufactures a multi-stage gear by forming gears having different diameters on the outer circumferential surface of a hollow cylindrical member to be processed, and has a first step wherein a smalldiameter gear is formed on the outer circumferential surface, a second step wherein the ends of the member to be processed undergo plastic deformation and the diameters thereof are enlarged to form large-diameter gear parts, and a third step wherein large-diameter gears are formed by cutting the large-diameter gear parts.

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LITRETURE REVIEW

3. Gear designing method, gear manufacturing method, and gear manufactured by the same method [US 6080199 A] :

The author Mitsuhiro Umeyama, Masana Kato, Katsumi Inoue has work is related to a method of designing a gear, a method of manufacturing the gear, and the gear manufactured by the manufacturing method, and more particularly, to techniques for efficient and easy designing an manufacturing of gears which have a reduced gear noise.

Amplitude of transmission error of tooth pair of a gear is obtained in relation to actual contact ratio (εr) which is an angular range (θr) of actual contact of the surfaces of the tooth pair divided by an angular pitch (θp) of the gear. The specifications and/or tooth surface modification of the gear is/are are determined so as to reduce the transmission error amplitude under non-load condition in which the actual contact ratio (εr) is 1.0. Alternatively, the specifications and/or tooth surface modifications is/are determined so as to increase an effective contact ratio (εn) which is an angular range (θn) divided by the angular pitch (θp), the angular range (θn) corresponding to a portion of a path of the tooth contact point in which an edge contact of the tooth pair does not take place at the tooth top or at the ends of the face width of the teeth. These arrangements permit efficient and easy designing of a gear having a reduced noise, without simulations or tests.

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LITRETURE REVIEW 4. Toothed gear manufacturing method [US 6449846 B2] : The author David B. Dooner, Ali A. Seireg has work is related to toothed elements and their manufacture.

In particular, it relates to optimize designing methods and machinery for manufacture of toothed gears and gear cutters, molds or dies without limitation to cylindrical or conical surface geometry of present gear-making machinery and related methods.

A method for manufacturing a variable-diameter gear pair operable with a conjugate action therebetween

includes the steps of providing a first workpiece and a second workpiece, each having a minor and a major diameter portion in spaced relation therefrom along a longitudinal axis. At least one gear tooth is formed within the first (second) workpiece for forming at least one first (second) gear body, wherein the at least one gear tooth within the first (second) at least one gear body curves outwardly in a radial and axial direction from the longitudinal axis, and wherein each of the at least one gear tooths includes a width dimension that changes in size between the minor and major diameter portions. Each of the first and second at least one gear bodies has the variable diameter and variable pitch for forming a gear pair operable with each other with a conjugate action there between.

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LITRETURE REVIEW 5. Composite gear and method of making same [ EP 0894212 B1] : The author John D. Santi has given a composite gear that includes one or more metal stamped plates

(18, 20), and two thermoplastic layers (12, 14) disposed on opposite sides of the plates. Apertures (34) are provided in the stamped metal plates so that the molten thermoplastic material may flow through the apertures and anchor the two thermoplastic layers to each other as well as to the metal plates. The composite gear has composite gear teeth (11) which consist of one or more metal gear teeth portions sandwiched between two thermoplastic gear teeth portions. The thermoplastic gear teeth portions extend outwardly from the metal gear teeth portions so that the thermoplastic teeth portions absorb loads under normal operating conditions. Under abnormal conditions such as when an abrupt stop occurs, the thermoplastic portions of the gear teeth are compressed and the higher torque forces resulting from the abnormal condition are absorbed by the metal gear teeth portions. Unique tooling and manufacturing methods are also described to enable the composite gear to be made without over molding the metal gear teeth portions.

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LITRETURE REVIEW 6. Gear making process[ US 5390414 A] :

The author Bohdan Lisowsky has given a method of manufacturing a helical gear

allowing strategic placement of a hardenable wear-resistant and high strength layer at predetermined locations on the gear. The method includes the steps of forming a gear core preform having the general shape of the helical gear and positioning the gear core preform within an elastomeric mold having the specific shape of the helical gear. The method also includes the steps of filling the mold at the predetermined locations with the hardenable metallurgical material and densifying the gear core preform and the metallurgical material. Lastly, the method also includes the step of heat treating the densified gear core preform and metallurgical material, to obtain the helical gear having a wear-resistant layer at the predetermined locations. A helical gear formed according to method is also provided.

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LITRETURE REVIEW 7. Helical gear and method of manufacturing the same[CA 2660672 C] : The author a Shinji Kitaoka, Keisuke Atsumi, Koji Takaira,Seiji Hiroshima, Takaaki

Shimizu has given a method of manufacturing a helical gear, includes a gear cutting process for forming a roughly-processed gear by applying a gear cutting to an outer circumferential surface of a blank, and a tooth surface forming process for forming a tooth surface by pressing a rolling die against a roughly-processed tooth surface of the roughly-processed gear, wherein a length of a portion of the roughly-processed tooth surface, to which a plastic deformation is applied by the rolling die, in a face width direction is formed to be shorter than a length of a face width of the roughly-processed tooth surface.

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LITRETURE REVIEW 8. Herringbone gear teeth and method for manufacturing same[EP 1552191 B1] : The author David L. Jinkins, Kenneth O. Beckman, Scott A. Franks, Arthur L. Nelson has

given a method of manufacturing herringbone gears starting with non-hardened cylindrical stock material, establishing a relief notch for each tooth in the cylindrical stock where the two helices meet, roughing the double helical teeth, and case-hardening the gear teeth. The teeth are then finished using high accuracy Cubic Boron Nitride (CBN)-faced cutters with the relief notch allowing run-out of the cutters.

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LITRETURE REVIEW 9. High density dual helical gear[US 7854995 B1] : The author Gary L. Anderson’s present invention relates to a low cost technique for

manufacturing dual helical gears, such as herringbone gears, from powder metals. The dual helical gears made by this technique are of high density (greater than 92% of theoretical density) and offer superior strength. The present invention more specifically discloses a forged metal herringbone gear which is comprised of a body and a plurality of teeth wherein the metal has a density of greater than 92% of theoretical and wherein the grain in the teeth is one range higher on the ASTM E 112 grain size chart than the grain in the body of the gear.

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LITRETURE REVIEW 10. Method and apparatus of quench hardening of gear teeth surfaces[US 5213636 A] : The author Ronald R. Akers, William D. West has given a method for induction heating

and quench hardening of helical gears provides a hardness pattern uniformly distributed to a controlled depth across and between the teeth surfaces by means of axial scanning of the workpiece and uniform quenching. Uniform quenching is achieved by directing jets of quench fluid at the workpiece toothed surface at angles horizontally offset from the radial direction.

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LITRETURE REVIEW

11. Method of induction hardening of gear teeth[US 4589935 A] : The author John R. A. Scott disclosed a process and apparatus for induction hardening of the flank, root and tip surfaces of gear teeth

so as to provide a surface-hardened layer along said surfaces. An electrically energizable inductor head carries out movement along the space between a pair of adjacent gear teeth, the inductor head having an external profile matching the profile of the space between the gear teeth. Guides maintain clearances between the inductor head and the tooth surfaces, during movement of the inductor head, the clearance being a minimum between the inductor head and the root surface and varying in predetermined manner along the flank surfaces to achieve heating along the flanks and root surfaces to a uniform predetermined temperature. Jets of coolant are directed to the surfaces of the unheated flanks, tips, heated flanks and root of the pair of gear teeth to achieve rapid cooling of said surfaces. The gear is immersed in mineral oil or other non-aqueous quenching agent. The height of the inductor head is less than the depth of the space between the root and tip surfaces of each pair of gear teeth. The operating parameters of (a) the predetermined clearances, (b) the rate of electrical energy supplied to, and the speed of movement of the inductor head and (c) the rate of cooling, are controlled to form a uniform thickness surface-hardened layer from tip to tip along the flanks and root surfaces of the pair of gear teeth, the surface-hardened layer having an internal structure which imparts the equivalent of a built-in compressive stress in its surface, at least in the region of the root curve and its transition to the flank surfaces. This compressive stress enables each tooth to withstand tensile stresses which are applied to gear teeth, when intermeshing gear teeth apply fatigue bending loads to each other.

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LITRETURE REVIEW 12. Method for producing fully dense powdered metal helical gear[US 6044555 A] : The author Nedward A. Jacob, Jerome E. Muroski has given a method for producing a fully dense powdered

metal helical gear can include the steps of placing powdered metal in a preform die wherein it can be compacted axially by rotating punches to create a helical gear preform. Next the preform can be sintered. The preform can then be heated to an appropriate temperature and inserted into a hot forming die wherein it can be impacted axially by rotating punches to fully densify the helical gear preform. Next the densified helical gear can be inserted in a burnishing die where it can be forced through a helical profiled die cavity to impart more precise external dimensions. Process temperatures and impact forces can vary depending on the properties of the powdered metal and desired characteristics of the finished part. Secondary treatments, such as rolling, shaving, heat treating, chining to length and inner diameter sizing can be subsequently performed.

Problem Statements

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Firstly, gear strength depends on fatigue fracture of tooth surface caused by contact surface pressure

in addition to the tooth-root bending fatigue strength. Secondly, When the region at a depth of 20 um or less from the surface is applied with higher residual

stress in order to enhance the tooth-root bending fatigue strength, this leads to a problem with tooth-tip chipping.

Thirdly, During gear hobbing the size of a gear is measured throughout the production run as a

process control by the operator. As shown in Figure 1, this measurement is normally done using balls or pins of a specified diameter to contact the gear tooth profile at the pitch diameter. For larger gears a span measurement over several gear teeth will be done. Size changes from a “cold” morning startup to normal operating temperature. The machine system may be thermally unstable. Record the size change over time versus temperature of the machine and/or cutting fluid. A “warm up” period may be required for your particular machine. Also, certain gear machines have thermal sensor(s) for automatic adjustment of the machine size, and this system may have failed.

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A Tooth-tip cross section of a gear immediately before a tooth tip is chipped is checked by a micrograph shown in FIG. a. This shows, as traced in FIG. b

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OBJECTIVES

From problem statement the objective of work the following steps needs to be perform : Carburizing Treatment Shot Peening Treatment X-Ray Stress Analyzer C.A.E. Analysis

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Shot Peening B-Treatment Process

In the shot peening B-treatment, residual stress is applied to a region at a different depth is shown in fig.

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Shot Peening C-Treatment Process

In the shot peening C-treatment, residual stress is applied to a region at a different depth is shown in fig.

In the gear strengthened by applying residual stress to the gear having a carburized surface, the residual stress in the region at a different depth is as follow:

At a depth of 5 µm or more but 20 µm or less from the surface is —l400 MPa or less so that When a tooth of the gear is subjected to repeated stress, the repeated stress is canceled out by compressive stress to prevent surface cracks in the surface of a tooth root and improve a strengthening rate of the gear.

The residual stress in the region at a depth of 50 µm or more but 150 µm or less from the surface is —l000 MPa or more to prevent inner cracks and restrain tooth-tip chipping.

Thus, no cracks occur in the surface of a tooth root. This can prevent tooth-root fatigue fracture.

Possible Solution for Problem Statment

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CONCLUTION

In conclusion, the theoretical and experimental results of the research project have shown that the initiation of internal cracks and high cycle fatigue of case hardened gears not only depends on the residual stress condition or the presence of inclusions. It seems rather to be an interaction of state of load stress, state of residual compressive stress and critical inclusions in the material. Occurrence of the tooth-tip chipping is prevented. No crack is occurring in the surface of tooth-root.