GB2048740A - Hydropunch for use in Press Installations - Google Patents

Abstract

A hydropunch for an hydraulic metal working press having a die 2 comprises a cylinder 1, a ram 3 reciprocable within the cylinder 1 and dividing the cylinder interior into upper and lower chambers 6, 5, an actuator 4 for controlling supply of compressed gas to chamber 6 from a receiver 8, and means for returning the ram to its upper position including a closed chamber 14 communicating with the lower chamber 5 through ducts 16 and a valve 17 for communicating the upper chamber 6 with atmosphere under the control of actuator 4. As shown the apparatus includes a non- return valve 20 which allows gas to enter chamber 15 from chamber 5 when the ram is in its lower end position. Liquid 12 transfers the energy of ram 3 to workpiece 13. <IMAGE>

Description

SPECIFICATION Hydropunch for use in Press Installations This invention relates to a hydropunch for hydraulic metal working presses.

The invention can advantageously be used for the manufacture of fast-acting hydraulic presses effective for punching sheet materials through elastic, hydroelastic (through fluid via elastic diaphragm), and fluid media.

In addition, this invention can find application in the manufacture of pneumatic percussion press installations.

According to the invention there is provided a hydropunch for a press, comprising a cylinder, a ram reciprocable along the cylinder and dividing the interior of the cylinder into first and second chambers, means for supplying compressed gas to the first chamber for driving the ram from an initial position towards one end of the cylinder, and means for returning the ram to said initial position including a closed chamber communicating with the second chamber and valve means operable to connect the first chamber with atmosphere.

The means for returning the ram to its initial position makes it possible to eliminate a valveand-pipeline system, thereby ensuring, on the one hand, a simple and reliable construction and, on the other, precluding leakage of compressed gas, such as through gaps in a slide valve, and loss of energy due to occur during the passage of gas through pipelines.

It is advantageous to utilize used compressed gas to ensure a faster return of the ram. To this end, a non-return valve for admitting the used gas to the closed chamber, is preferably located at a distance from the said one end of the cylinder that gas can flow from the first chamber into the closed chamber when the ram is in an end of stroke position opposite the initial position.

It is also preferred to have the closed chamber arranged concentrically with the cylinder at the one end and to have this chamber connected through ducts with the second chamber of the cylinder. This will reduce both the travelling path and leakage of air on its way from the second chamber to the closed chamber during the operating and return strokes of the ram.

To render the construction more simple, the said valve means can be accommodated in an opening, provided in a cover closing the end of the cylinder opposite said one end. The construction is further simplified if the cover includes a passage for supplying compressed air to the first chamber.

To ensure a reliable return of the ram, it is possible to provide a non-return valve through which compressed gas is admitted into a portion of the second chamber which is to be filled with a fluid to act as the working medium.

The invention will now be described in more detail. by way of example only, with reference to the accomany;ng drawings, in which: Fig. 1 is a longitudinal sectional view of a hydropunch for use in a press, according to the invention: Fig. 2 is a partial longitudinal sectional view of same provided with a non-return valve for admitting compressed gas therethrough into the chamber to be filled with a working fluid.

The hydropunch, illustrated, is a part of a hydraulic press.

The hydropunch comprises a cylinder, 1 one end of which faces a die 2 of a hydraulic press The cylinder 1 accommodates a ram 3 provided with an actuator 4 and a means enabling its return to original position. As the ram 3 is displaced, it forms a below-the-ram chamber 5 and an above-the-ram chamber 6. When in its upper position, the ram 3 is retained in position by means of a collet 7, which also functions as a shock-absorber, with the ram 3 returning to its original position (lifted) on completion of the operating stroke. Mounted on the upper end of the cylinder 1, opposing the other end facing the die 2, is the ram actuator 4. The hydropunch also includes a compressed gas receiver 8 arranged concentrically with and surrounding the cylinder 1. The receiver 8 communicates with the abovethe-ram chamber of the cylinder 1 via a duct 9.

There is also provided a cover 10 intended for closing both the cylinder 1 and receiver 8. The end of the cylinder 1, facing the die 2, adjoins a high pressure chamber II filled with an elastic medium (fluid) 12, serving as the working body through which energy is transferred from the ram 2 to a workpiece 13 positioned on the die 2.

According to the invention, the means for returning the ram 3 to its original position comprises a closed chamber 14 arranged concentrically with the cylinder 1 at the end thereof facing the die 2. The chamber 14 has its interior 15 in communication with the below-theram chamber 6 of the cylinder 1 via ducts 16. The ram return means also has a valve 17 adapted to communicate the above-the-ram chamber 6 of the cylinder 1 with the atmosphere. The valve 17 is set in an opening, formed in the cover 10, and communicates with the above-the-ram chamber of the cylinder 1 via a duct 1 8. The valve 17 is opened by means of a cam 19 connected with a rod of a cylinder of the ram actuating means (not shown).

The means for returning the ram 3 to its original position incorporates a non-return valve 20 built in the wall of the cylinder 1 at a distance from the end thereof facing the die 2, approximately equal to the height of the ram 3.

The non-return valve 20 is intended to admit the used gas into the closed chamber 14.

As an alternative to an elastic medium (rubber), use can be made of a hydro-elastic medium (fluid separated from the workpiece by an elastic diaphragm), or of a fluid filling the high-pressure chamber after the die with the workpiece are pressed against the above chamber.

In the event of using a fluid as the working body, use can be made of a non-return valve 21 (Fig. 2) set in the body of the chamber 11 and intended for admitting compressed gas from a receiver 22 under the ram 3 and into the chamber 1 1 which is filled with the fluid 23. The fluid is fed into the chamber 11 through a nozzle 24 connected to a fluid supply system, extending through the closed chamber 14 and provided with a non-return valve 25.

The hydropunch of the invention operates in the following manner.

Shown in Fig. 1 is the final moment of returning of the ram 3 to its original position, with the duct 9 closed and the valve 17 open and compressed gas passes from the chamber 15, forcing the ram 3 to move upward. At the end of the upward stroke the ram 3 comes into engagement with the collet 7 and, having its kinetic energy damped, is held therewith. To initiate an operating stroke of the ram 3, the ram actuating means 4 makes the duct 9 opened with the help of the rod of its cylinder (not shown). At the same time, the upwardly moving cam 19 releases the valve 17, thereby isolating the abovethe-ram chamber 6 of the cylinder 1 from the atmosphere. With the duct 9 open, the compressed gas from the receiver 8 is adrnitted to the above-the-ram chamber 6 and forces the ram 3 downwards.In the course of the downward movement of the ram 3, the air in the below-the-ram chamber 5 of the cylinder 1 is being forced out and through the ducts 16 is admitted into the interior 15 of the closed chamber 14. On reaching its extreme downward position, the ram 3 imparts a blow against the elastic medium 12 thereby converting the energy, accumulated during its downward movement, into an impulsive pressure, thereby effecting the deformation of the workpiece on the die 2.

When the ram 3 reaches its lowest position, the compressed gas effecting the downward movement of the ram 3 is admitted through the non-return valve 20 into the interior 1 5 of the chamber 14.

The ram actuating means 4 having a portion of the compressed gas admitted into the above-theram chamber 6, closes, in the first place, the duct 9, thereafter makes the valve 17 opened through pressing thereon by the cam 19 thus communicating the above-the-ram chamber 6 of the cylinder 1 via the duct 18 with atmosphere.

On having given up its energy for effecting deformation of the workpiece, the ram is forced upward by the compressed as from the chamber 15 until it comes into engagement with the collet 7. Thus, the operating cycle is completed and the hydropunch is set for next cycle.

Another embodiment of the hydropunch according to the invention for effecting a similar operation wherein a fluid is used as an alternative working medium operates in the following manner.

The workpiece 13 is fixed in position on the die 2 and both are pressed against the high pressure chamber II, whereupon the fluid 23 through nonreturn valve 25 is fed thereinto via the nozzle 24 in the amount sufficient to fill in the interior of the chamber 11. On gaining momentum after being actuated, the ram imparts a blow against the fluid 23 which results in the deformation of the workpiece and in further lowering of the ram below the level of the ducts 16 to a depth, determined by the amount of the workpiece deformation. In order to lift the ram 3, compressed gas is fed from the interior of the receiver 22 and is admitted through the valve 26 to the chamber 11 filled by liquid in an amount not exceeding that of gas required for lifting the ram 3 to a height at which the lower end of the ram 3 is higher and above the lower edge of the ducts 16 (the volume of the receiver is determined in accordance with this requirement).

Further upward movement of the ram 3 to its original position, until its engagement with the collet 7, is carried out under the effect of compressed gas available in the interior 1 5 of the closed chamber 14.

Such construction of the hydropunch for operating with a fluid employed as a working medium ensures a reliable return of the ram to its original position even in those instances wherein large amounts of reduction are involved.

Claims (7)

Claims

1. A hydropunch for a press, comprising a cylinder, a ram reciprocable along the cylinder and dividing the interior of the cylinder into first and second chambers, means for supplying compressed gas to the first chamber for driving the ram from an initial position towards one end of the cylinder, and means for returning the ram to said initial position including a closed chamber communicating with the second chamber and valve means operable to connect the first chamber with atmosphere.

2. A hydropunch according to claim 1, wherein means for controlling actuation of the ram is arranged on the end of the cylinder opposite said one end, the gas supply means includes a compressed gas receiver for communicating with the first chamber of said cylinder under control of said control means, and said valve means is also controlled by the control means.

3. A hydropunch as claimed in claim 1 or 2, wherein the closed chamber is concentric with the cylinder adjacent the said one end thereof, and the closed chamber is connected to the second chamber by ducts provided in the cylinder wall.

4. A hydropunch as claimed in any one of claims 1 to 3, wherein the said valve means is located in an opening provided in a cover closing the end of cylinder opposite said one end.

5. A hydropunch as claimed in any one of claims 1 to 4, wherein the ram return means includes a non-return valve arranged to admit gas into said closed chamber, for the cylinder, said valve being located at such a distance from the said one end of the cylinder that gas can flow from the first chamber into the closed chamber via the valve when the ram is in an end position opposite the initial position.

6. A hydropunch as claimed in any one of claims 1 to 5, wherein the ram return means includes a non-return valve for admitting compressed gas to a portion of the second chamber to be filled with a fluid for use as a working medium.

7. A hydropunch for a press, substantially as herein described with reference to the drawings.