HPS’S CYLINDER SELECTION · HPS’S CYLINDER SELECTION THE CYLINDER MATERIAL AND COMPONENTS The...

HPS’S CYLINDER SELECTION

CYLINDERS TYPE CATEGORIES

Basically, there are three type cylinders categories.

� 1) BLOC CYLINDERS

� 2) STANDARDIZED CYLINDERS

� 3) AUTO LOCKING CYLINDERS

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� 1) BLOC CYLINDERS � 2) STANDARDIZED CYLINDERS


Use this cylinder to avoid all piping around the tools.

In This family we have 4 different TYPES.

A) Common Bloc Cylinder >> VBL & VBM

B) Small Series Low Cost >> VCN & VXP

C) Average Series Medium Cost >> VBG, VPC & VCR

D) High Series High Quality >> SP2, VSM & VPM

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� 2) STANDARDIZED CYLINDERS � 3) AUTO LOCKING CYLINDERS

In This family we have 2 different TYPES*.

A) European Standard CNOMO >> HVB

B) International Standard ISO 6020/2 >> H160 co

• Other models are produce be HPS, please contact our sales department.

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� 2) STANDARDIZED CYLINDERS


In This family we have 2 different TYPES.

A) With PIPING & COMPACT >> HRBN

B) Without PIPING >> HRB*

• For the HRB the delivery time is 10 weeks.

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THE CYLINDER MATERIAL AND COMPONENTS

The following chart show the material used for the components of each single cylinder.

COMPONENT MATERIAL

VB

L

VB

M

VC

N

VX

P

VB

G

VP

C

VC

R

SP

2

VS

M

VP

M

HV

B

H1

60

co

HR

BN

Rod 42CD4 hardened and chrome-plated

steel X X X X X X X X X X X X X

Piston

C35E steel X X X X X X X X X X X X

Aluminium (For Magnetic detection) X X X X X X X X X X X

Body

C35E Steel X X X X X X X X X X X X

Stainless Steel (For Magnetic detection)

X X

Aluminium (For Magnetic detection) X X X X X X X X X

Head C35E Steel X X X X X X X X X X X X X

Bottom C35E Steel X X X X X X X X X

Seals

NITRIL (0° < 80°) X X X X X X X X X X X X X

VITON (0° < 160°) X X X X X X X X X X X X X

O-Ring

NITRIL (0° < 80°) X X X X X X X X X X X X X

VITON (0° < 160°) X X X X X X X X X X X X X

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3 TYPES OF DETECTION

ELECTRO/MECANICAL---MAGNETIC---INDUCTIVE

ELECTRO/MECANICAL MAGNETIC INDUCTIVE

ADVANTAGE Simple/reliable/polluted environment No & clean Contact No & clean Contact

DISAVANTAGE Cost/Cumbersome Aluminium Body,

low temperature &

Clean environment

Clean environment

& low temperature

VALUE *** * **

ELECTRO/MECANICAL

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MAGNETIC

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INDUCTIVE

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GENERAL CYLINDER OPERATION ASPECTS

Operating

Principles

A fluid is introduced into a cylindrical chamber where

a sliding piston is free to move. The force exerted by

the fluid on the piston surface generates a working

pressure on the contact are and causes the piston to

move along a specific length of space called stroke.

Force The fluid introduced in the cylinder exerts a force on

the piston surface and causes the piston movement.

Flow Volume of oil that flows into and out of the cylinder

during a unit of time (e.g l/min). Due to different

chamber volumes, at the same flow value, the cylinder

gains greater speed when the piston goes back.

Logically speed is strictly connected to the flow value.

Piston Speed Piston speed is the piston motion rapidity along a given

length of movement (stroke). The speed value is

strictly connected to the cylinder oil flow. Speed is one

of the important factors which determine the cylinder

life. In fact, at given piston impact speed against the

cylinder head will cause permanent damages such as

deformations, breakages, leakages etc...

Pressure Pressure of the oil introduced to – extracted from the

cylinder heads ports. The value is determined by the

nominal pressure of the hydraulic system connected to

the cylinder.

Piston

Cushioning

Cushioning is the result effect of mounting a cushion

bushing on the piston rod and a flow adjusting screw

(in the cylinder heads). In fact, during the piston

motion, the presence of the cushion bushing causes the

generation of a deceleration force at a certain position

along the stroke.

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SELECTING A CYLINDER FOR GENERAL APPLICATION

CONSIDERATIONS ABOUT THE FORCES

The main FORCES exercised during the piston movement are basically TWO.

Look at the following chart to know about them.

PUSH FORCE (Thrust) Force that the fluid exercises on the full piston surface

PULL FORCE (Traction) Force that the fluid exercises on a reduced piston surface

For the cylinder selection you will consider the PUSH and the PULL FORCE.

The PUSH FORCE is BIGGER than the PULL FORCE, since pressure acts on the whole piston area only

on the forward stroke. In fact, on the return stroke pressure does not act on the rod section, which must be

obviously subtracted from the whole piston area.

We must remember that forces are derived from the general formula.

F= P x A

F= Force in Kg

P= bar (Kg/cm²)

A= area in cm²

When you have to select a cylinder, you have to:

1) Consider the FORCES that will be applied to the cylinders (or that your cylinder will apply) in your

particular application and verify, using the manufacturer’s specification, that the CYLINDER

CHOSEN IS SUITABLE.

2) Decide which cylinder family use. (3 different family’s)

3) Decide whether to use a cylinder with DETECTION (3 different family’s)

4) Decide whether to use a cylinder with piston CUSHIONING or not.

PUSH PULL

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STEPS TO SELECT HPS’S CYLINDERS

3 STEPS TO SELECT CYLINDERS FOR MOULD HYDRAULIC SYSTEMS

STEP 1: Select cylinder family on the basis of the following factors.

• PRESSURE of the application hydraulic system

• Movement SPEED requested by the application.

• SPACE to locate the cylinder in the tool.

• Working TEMPERATURE of the system where the cylinder will be located.

• Necessary cylinder STROKE.

• MOUNTING TYPE.

• Pulling and pushing FORCES.

PRESSURE

Two main pressure values are to be considered on injection moulds.

Operating pressure, given by the hydraulic system power circuit

Cylinder pressure, exercised by the cylinder to keep in place mould component and counteract

mould inner pressure on a specific portion surface.

SPEED

You have to verify and calculate the speed if you have long stroke.

For lees than 200mm stroke it’s not necessary.

SPACE

The volume and space allocate for the cylinder can define the type. With or without piping.

TEMPERATURE

The plastic material high temperature is essentially conveyed by heat conduction to outside

area of the mould through the cylinder rod. The temperature in this particular area must be

considered to select the right cylinder and seals. Electronic sensors are very sensitive to high

temperature. Ensure temperature never exceeded 70/80° centigrade.

STROKE

In mould application there are no particular strokes. For safety reasons it’s suitable to have

+1mm stroke in both side of the cylinder. For example the needed stroke is 100mm order

102mm and located the cylinder with 1mm safety stroke in piston side and 1mm safety stroke

in rod side.

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MOUNTING TYPE Generally, hydraulic cylinders for moulds are used in a vertical or horizontal position and

perpendicular to the axis of the injection machine. Bloc cylinder with out and in oil direct from

the tool are the most common on moulds.

DIRECT FROM THE TOOL

TRADITIONAL

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FORCES

Three types of forces must be considered when selecting a cylinder for injection mould applications.

1) PUSH FORCE (Thrust) DYNAMIC. Push Force exercised by the cylinder to move ejection plates or other moving mould components. In these

cases inertial force and kinetic energy must be considered to prevent damages selecting the proper cylinder.

2) PULL FORCE (Traction). To move back the mould sliding system to release and/or expel the plastic component solidified on the

slider. When that slider has to be extracted, the solidified material exercises a gripping force, that the

cylinder pull force must win, in order to carry out the slider.

Part

Slider

Cavity

CYLINDER

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3) STATIC PUSH FORCE. To keep in place the mould sliding system when plastic material is injected and counteracts the force

exercised by the material on the mould inner surface during the injection time.

The various plastic materials exercise different forces inside the tool. For common plastic use 700bar

pressure inside the tool to calculate the dimension of the cylinder. For specific plastic ask the plastic

supplier.

Don’t forget you have to have the following option in the injection machine: Core Pressure during the

injection time.

General formula:

CF= P1xS1 > ((P2xS2) x2) = IF

P1 = 100bar

P2 = 700bar

REMEMBER! You can use HRB or HRBN to avoid all of these problems.

CYLINDER

Slider

Cavity INJECTION FORCE = IF

CYLINDER FORCE = CF

P1 (bar)

P2 (bar)

S1

S2

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STEP 2: Verify the range of the cylinder.

Now you have to define is your cylinder will be to one tool who will work on Great,

Average or small series.

This point is very important to obtain the right product with the right price.

Don’t forget:

GREAT AVERAGE SMALL

SP2 VCR

VSM VBG VCN

VPM VPC VXP

VBL VBL VBL

HVB HVB

H160 H160

STEP 3: Verify safe cylinder operation.

Validate:

The power needed

The speed

The material

The environment

CONGRATULATION YOU HAVE CHOSE YOUR HPS CYLINDER.

HPS’S CYLINDER SELECTION · HPS’S CYLINDER SELECTION THE CYLINDER MATERIAL AND COMPONENTS The...

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