Hydraullic Press

8/14/2019 Hydraullic Press

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C H I T K A R A I N S T I T U T E O F E N G I N E E R I N G A N D

T E C H N O L O G Y Page

ACKNOWLEDGEMENT

It is our privilege to express profound gratitude and admiration to our

esteemed Project in charge Mr. Nitin Singla, whose unlimited

guidance, innovative ideas and tireless efforts helped along the way in

completing the project.

It gives me immense pleasure to put on record my sincere thanks to

.our Supervisor officer. I had the privilege of starting and

completing my Final Year Project.

This fruitful, as it has given me the feel of the part of an industry and

has helped me to understand the engineering profession in the better

way.


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DECLARATION

We hereby declare that the project work titled, Hydraulic Press

submitted as part of Bachelors degree in Mechanical engineering at

Chitkara Institute of Engineering and Technology, Punjab, is an

authentic record of our own work carried out under the supervision of

Er. Nitin Singla.

Place:Chitkara Institute of Engineering and Technology

Verified by:

Date:

Name(s):Abhinav Kumar Sharma (L-7005111107)Anuj Grover

Avinash Bhama (L-7005111110)Ayush MahajanParul GuptaSahil MoryaShashi Shekhar

Signature of Supervisor:

Signature(s):


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C ONTENTS

Title Page No.

Declaration IAcknowledgement IIList of Abbreviations IIIList of Figures and Tables IV

1. Introduction

1.1 subheading 1

1.2 subheading 31.2.1 sub-subheading 4

2. Literature Survey 6

** The important/relevant content from the previously submitted

literature survey report can be added in this section.

3. Work Done 18

4.Conclusion and Future Scope 30

References

*Give sub headings and sub-sub headings specified wherever necessary in the same format as

in 1.


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INTRODUCTION

Fluid power is the technology of exploiting the properties of fluids to generate,

control, and transmit power as a result of the pressurization of fluids.Fluid power is

a term which was created to include the generation, control, and application of

smooth, effective power of pumped or compressed fluids (either liquids or gases)

when this power is used to provide force and motion to mechanisms. This force

and motion may be in the form of pushing, pulling, rotating, regulating, or driving.

Fluid power includes hydraulics, which involves liquids, and pneumatics, which

involves gases. Liquids and gases are similar in many respects.

As the term fluid refers either to gases or to liquids, fluid power is also subdivided

into the categories ofhydraulics andpneumatics. The differences being that with

hydraulics the medium used is a liquid (i.e. mineral oil or water) and for pneumatics it

is a gas (i.e. air or another inert gas).

A fluid power system with a pump or prime mover motor or IC engine converts

mechanical energy in to fluid energy. This fluid flow is used to actuate a device.

In fluid power, hydraulics is used for the generation, control, and transmission of

power by the use ofpressurized liquids.

Hydraulic topics range through most science and engineering disciplines, and cover

concepts such as pipe flow, dam design, fluidics and fluid control etc.

The extensive use of hydraulics and pneumatic to transmit power is due to the fact

that properly constructed fluid power systems possess number of favorable

characteristics. They eliminate the need for complicated systems of gears, cams, and

levers. Motion can be trans-mitted without the slack inherent in the use of

solid machine parts. The fluids used are not subject to breakage as are mechanical

parts, and the mechanisms are not subjected to great wear. The different parts of a

fluid power system can be conveniently located at widely separated points, since

the forces generated are rapidly transmitted over considerable distances with

small loss. These forces can be conveyed up and down or around corners with small

loss in efficiency and without complicated mechanisms. Very large forces can be
http://en.wikipedia.org/wiki/Fluidhttp://en.wikipedia.org/wiki/Hydraulicshttp://en.wikipedia.org/wiki/Pneumaticshttp://en.wikipedia.org/wiki/Fluid_powerhttp://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Flowhttp://en.wikipedia.org/wiki/Damhttp://en.wikipedia.org/wiki/Fluidicshttp://en.wikipedia.org/wiki/Hydraulicshttp://en.wikipedia.org/wiki/Pneumaticshttp://en.wikipedia.org/wiki/Fluid_powerhttp://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Flowhttp://en.wikipedia.org/wiki/Damhttp://en.wikipedia.org/wiki/Fluidicshttp://en.wikipedia.org/wiki/Fluid


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controlled by much smaller ones and can be transmitted through comparatively

small lines and orifices. If the system is well adapted to the work it is required to

perform, and if it is not misused, it can provide smooth, flexible, uniform

action without vibration, and is unaffected by variation of load. In case of an

overload, an automatic release of pressure can be guaranteed, so that the system

is protected against breakdown or strain. Fluid power systems can provide widely

variable motions in both rotary and straight-line trans-mission of power. The need for

control by hand can be minimized. In addition, fluid power systems are

economical to operate. The question may arise as to why hydraulics is used in some

applications and pneumatics in others. Many factors are considered by the user and/or

the manufacturer when determining which type of system to use in a specific

application. There are no hard and fast rules to follow; however, past

experience has provided some sound ideas that are usually considered when such

decisions are made. If the application requires speed, a medium amount of

pressure, and only fairly accurate control, a pneumatic system maybe used. If the

application requires only a medium.

Hydraulics includes the manner in which liquids act in tanks and pipes,

deals with their properties, and explores ways to take advantage of these properties.


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SURVEY

Our survey is regarding Hydraulic system. Because for much accuracy and power we

use the Hydraulic system. For the Hydraulic Press we had visited many places in

Punjab where we found its applications. In market various specifications of the

Hydraulic Presses are available. These specifications are according to the type of

work taken from the Press.

We had studied the constructional features for the Press which we are going to Start.These Presses are according to the Pressure created inside cylinder and work

requirements. In its work it has to press a sheet of thickness 20 gauge (up to 1mm). So

we have selected a cylinder who can generate a Pressure of up to 2000 kg say 2 tons.

For this we had searched, analyzed, construct the type of requirements used which

will help us in making complete specified Hydraulic Press of Bench Type.

From our study,the hydraulic system theory proves that in a hydraulic cylinder, the

force that can be exerted by the cylinder is dependent on the bore size, length ofstroke as well as the pressure exerted by the pump. Also the speed at which the piston

in the pump will move depends on the flow rate from the pump as well as the area of

the cylinder.

We have studied throughout the fluids used in the Hydraulic system for the generation

of amount of power needed.

The study of liquids is divided into two main parts:

Liquids at rest (hydrostatics) and liquids in motion (hydraulics).

The effects of liquids at rest can often be expressed by simple formulas. The effects of

liquids in motion are more difficult to express due to frictional and other factors

whose actions cannot be expressed by simple mathematics.

There have been many liquids we had studied for use in hydraulic systems. Currently,

in todays generation liquids being used include mineral oil, water, phosphate ester,


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water-based ethylene glycol compounds, and silicone fluids. The three most common

types of hydraulic liquids are petroleum-based, synthetic fire-resistant, and water-

based fire-resistant.

We will discuss the analyzed part in the later section.

HYDRAULIC PRESS

The hydraulic press is one of the oldest of the basic machine tools. In its modernform, is well adapted to presswork ranging from coining jewelry to forging aircraft

parts. Modern hydraulic presses are, in some cases, better suited to applicationswhere the mechanical press has been traditionally more popular.

Pascal Law:Pascal's Principle and Hydraulics

Hydraulic systems use a incompressible fluid, such as oil or water, to transmit forcesfrom one location to another within the fluid. Most aircraft use hydraulics in the

braking systems and landing gear. Pneumatic systems use compressible fluid, such as

air, in their operation. Some aircraft utilize pneumatic systems for their brakes,

landing gear and movement of flaps.

Pascal's law states that when there is an increase in pressure at any point in a

confined fluid, there is an equal increase at every other point in the container.

A container, as shown below, contains a fluid. There is an increase in pressure as thelength of the column of liquid increases, due to the increased mass of the fluid above.

For example, in the figure below, P3 would be the highest value of the three pressure

readings, because it has the highest level of fluid above it.


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If the above container had an increase in overall pressure, that same added pressure

would affect each of the gauges (and the liquid throughout) the same. For example

P1, P2, P3 were originally 1, 3, 5 units of pressure, and 5 units of pressure were added

to the system, the new readings would be 6, 8, and 10.

Advantages of Hydraulic Presses

The mechanical press has been the first choice of many press users for years. The

training of tool and die makers and manufacturing engineers in North America has

been oriented toward applying mechanical presses to sheet-metal press working.

Modern hydraulic presses offer good performance and reliability. Widespread

application of other types of hydraulic power equipment in manufacturing requires

maintenance technicians who know how to service hydraulic components. New fast

acting valves, electrical components, and more efficient hydraulic circuits have

enhanced the performance capability of hydraulic presses.

Factors That May Favor the Use of a Hydraulic Press

Factors that may favor the use of hydraulic presses over their mechanical counterparts

may include the following:

1. Depending on the application, a hydraulic press may cost less than an equivalentmechanical press.

2. In small lot production where hand feeding and single stroking occurs, production

rates equal to mechanical presses are achieved.

3. Single stroking does not result in additional press wear.

4. Die shut heights variations do not change the force applied.

5. There is no tonnage curve de-rating factor.

6. Forming and drawing speeds can be accurately controlled throughout the stroke.

7. Hydraulic presses with double actions and or hydraulic die cushions are capable

of forming and drawing operations that would not be possible in a mechanical

press.

Unique Features of Hydraulic PressesIn most hydraulic presses, full force is available throughout the stroke.


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Figure illustrates why the rated force capacity of a mechanical press is available only

near the bottom of the stroke. The full force of a hydraulic press can be delivered at

any point in the stroke. This feature is a very important characteristic of most

hydraulic presses.

Deep drawing and forming applications often require large forces very high in the

press stroke. Some mechanical presses do not develop enough force high enough in

the downward stroke to permit severe drawing and forming applications such as

inverted draw dies to be used without danger of press damage. But we are not

concerning with the invert of the die direction.

Hydraulic Presses Have Full Force through the Stroke

The rated capacity of a mechanical press is available only at the bottom of the stroke.

The full force of a simple hydraulic press can be delivered at any point in the stroke.

Another advantage is that the stroke may be adjusted by the user to match the

requirements of the job. Only enough stroke length to provide part clearance is

required. Limiting the actual stroke will permit faster cycling rates and also reduce

energy consumption.

The desired pre-set hydraulic pressure provides a fixed working force. When

changing dies, different shut heights do not require fine shut height adjustment.


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Different tool heights or varying thicknesses of material have no effect on the proper

application of force.

The availability of full machine force at any point in the stroke is very useful in deep

drawing applications. High force and energy requirements usually are needed

throughout the stroke. The ram speed can also be adjusted to a constant value that is

best for the material requirements.

Built-in Overload Protection

The force that a hydraulic press can exert is limited to the pressure applied to the total

piston area. The applied pressure is generally limited by one or more relief valves.

A mechanical press usually can exert several times the rated maximum force in the

event of an accidental overload. This extreme overload often results in severe press

and die damage. Mechanical presses can become stuck on bottom due to large

overloads, such as part ejection failures or die setting errors.

Hydraulic presses may incorporate tooling safety features. The full force can be set to

occur only at die closure. Should a foreign object be encountered high in the stroke,

the ram can be programmed to retract quickly to avoid tooling damage.

LubricationHydraulic presses have very few moving parts. Those parts that do move, operate in a

flood of pressurized oil, which serves as a built-in lubrication system. Should leakage

occur, it is usually caused by the failure of an easily repairable part such as the ram

packing, or a loose fitting.

Advantages of Adjustable Force

The force of a hydraulic press can be programmed in the same way that the

movements of the press are preset. In simple presses, the relief valve system that

functions to provide overload protection may also serve to set the pressure

adjustment. This allows the press to be set to exert a maximum force of less than

press capacity.


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Figure shows Cutting soft materials and laminating work may require a low force

capacity machine with a large bed area such as the one illustrated in this simplified

drawing.

Press Construction Depends on the Type of Work PerformedThe bed size, stroke length, speed, and tonnage of a hydraulic press are not

necessarily interdependent. Press construction depends upon the amount of total

force required and the size of dies to be used.

Figure illustrates a large bed size press having low force capacity. Note the small

cylinder size. Some uses for these presses include cutting and pressing soft materials

such as fabric, and in wood or plastic laminating applications.


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DESIGNING PROCESS

Key Guide Lines for Press SelectionFigures illustrate how bed size does not directly relate to press force capacity.

Both if these illustrations show presses that use the tie rods for ram guiding which is

suitable for jobs that do not produce lateral or side loads. Hydraulic presses are

available in many types of construction which is also true of mechanical presses.

There are many factors to consider when deciding between a hydraulic and

mechanical press. These include stroke length, actual force requirements, and the

required production rate.

Hydraulic Press Speeds

Most press users are accustomed to describing press speeds in terms of strokes per

minute. Speed is easily determined with a mechanical press. It is always part of the

machine specifications.

The number of strokes per minute made by a hydraulic press is determined by

calculating a separate time for each phase of the ram stroke. First, the rapid advance

time is calculated. Next the pressing time or work stroke is determined. If a dwell is

used that time is also added. Finally the return stroke time is added to determine the

total cycle time. The hydraulic valve reaction delay time is also a factor that should

be included for an accurate total time calculation.

These factors are calculated in order to determine theoretical production rates when

evaluating a new process. In the case of jobs that are in operation, measuring the

cycle rate with a stopwatch is sufficient.

Most hydraulic presses are not considered high speed machines. In the automaticmode, however, hydraulic presses operate in the 20 to 100 stroke per minute range or

higher. These speeds normally are sufficient for hand fed work. The resulting

production rate speeds are comparable to that of mechanical OBI and OBS presses

used single stroking applications. Here, there is no additional clutch and brake wear

to consider in the case of the hydraulic machine.


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Force Requirements

When choosing between a mechanical or hydraulic press for an application a numberof items should be considered. The force required to do the same job is equal for each

type of press. The same engineering formulas are used.

There is always a possibility that an existing job operated in a mechanical press

requires 20 to 30 % more force than the rated machine capacity. The overloading

problem may go unnoticed, although excessive machine wear will result. If the job is

placed in a hydraulic press of the same rated capacity, there will not be enough force

to do the job. Always make an accurate determination of true operating forces to

avoid this problem. Press that Uses the Tie Rod for Ram Guiding

Machine Speed

The forming speed and impact at bottom of stroke may produce different results in

mechanical presses than their hydraulic counterparts. Each material and operation to

form it has an optimal forming rate. For example, drop hammers and some

mechanical presses seem to do a better job on soft jewelry pieces and jobs where

coining is required. In some cases, a sharper coined impression may be obtained at a

rapid forming rate. In deep drawing, controllable hydraulic press velocity and full

force throughout the stroke may produce different results. Often parts that cannot be

formed on a mechanical press with existing tooling can be formed in a hydraulic press

that has controllable force throughout the press stroke and variable blank holder

pressure as a function of the ram position in the press stroke.

The Type of Press Frame

Like the mechanical press, open gap-frame machines provide easy access from three

sides. Four-column presses such as the machine shown in Figure insure even pressure

distribution provided that there is little or no off-center loading.

Some two piston presses similar to the design feature a system of linear position

transducers and servo valves to vary the force to each piston in order to maintain the

ram level with the bed. How well such a system works depends on the accuracy of


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the position sensors and reaction speed of the servo valving. If snap through energy

release is involved, the servo system may not be able to react quickly enough to

prevent ram tipping that may be harmful to the press, tooling and process.

Press Quality

Since the applications for hydraulic presses ranges all the way from simple hand

pumped maintenance presses, to machines having very high force capacities, types of

construction and desirable features varies accordingly.

Here are just a few design and construction questions that will

provide a basis for comparison of one machine with another.

Frame:

Compare the weight if possible. Try to determine the character of the frame

construction. If a weldment, look at the plate thicknesses, extent of ribbing, and stress

relieving.

Cylinder and slide construction:

The cylinder size, type of construction used, and availability of service parts are

important. Also determine how well the ram travel is guided.

Maximum System Pressure:

The pressure at which the press delivers full tonnage is important. The most common

range for industrial presses is from 1000 psi (6,894 kPa) to 3000 psi (20,682 kPa).

Some machines operate at substantially higher pressures. Higher pressures may

accelerate wear. Make sure that replacement parts are readily available.

Horsepower:

The duration, length, and speed of the pressing stroke are the major factors that

determine the required horsepower.

Speed:

Take the time to calculate the speed based on the operations you intend to perform.

There are wide variations in hydraulic press speeds.


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