FR2582060A1 - PRESSURE AMPLIFIER SYSTEM - Google Patents

Abstract

THE PRESSURE AMPLIFIER SYSTEM ACCORDING TO THE PRESENT INVENTION INCLUDES FOUR PISTON AND CYLINDER ASSEMBLIES 3, 1A; 4, 2; 6, 2; 21, 1B COAXIALLY ALIGNED. THE PISTON OF THE FIRST ASSEMBLY MOVES A COMMON PISTON ROD UNDER THE ACTION OF PRIMARY FLUID PRESSURE. THE PISTON 4 OF THE SECOND ASSEMBLY IS SOLID WITH THE PISTON ROD 6 AND HAS A FLUID PASSAGE 18 TO BE ABLE TO CONTINUE TO MOVE IN THE DIRECTION OF THE WORKING STROKE AND SO AS TO BRING THE WORKING FLUID AT AN AMPLIFIED PRESSURE. AT A PREDETERMINED POINT OF THE WORKING STROKE, THE THIRD PISTON AND CYLINDER ASSEMBLY RAISES THE PRESSURE OF THE WORKING FLUID TO A HIGHER LEVEL. THE FOURTH SET CONSISTS OF A FLOATING PISTON 21 AND CYLINDER 1B IN FLUID COMMUNICATION WITH THE CYLINDERS OF THE SECOND AND THIRD SETS DURING THE WORKING STROKE BEFORE REACHING THIS PREDETERMINED POINT. A VALVE 14 ALLOWS THE PRIMARY FLUID PRESSURE TO BE APPLIED TO THE FOURTH PISTON FOR A PERIOD OF TIME BEFORE THE PRIMARY FLUID PRESSURE IS APPLIED TO THE PISTON OF THE FIRST ASSEMBLY. APPLICATIONS: AMONG OTHERS, CLAMPING OF PARTS IN PUNCHING PRESSES.

Description

Pressure booster system.

  the present invention relates to fittings

  of hydraulic cylinder pressure amplifiers

  nant for use in punching presses and other similar machines. The invention relates, more

  particularly to a pressure amplification system

  sion using a plurality of piston and cylinder arrangements capable of carrying, for example, a working fluid at three different pressure levels or stages. Pressure booster systems carrying a working fluid at two levels or pressure stages are known from Canadian patents

1,052,234 and 1,132,441.

  Known pressure booster systems use a coaxial arrangement of three sets of piston and cylinder, the pistons of which move together due to the fact that they are all mounted on a common piston rod. A first piston and cylinder arrangement, actuated by a pressure, for example a compressed air pressure, displaces the pistons of the three coaxial assemblies in the direction of the working stroke so as to act on a working fluid contained in the second and third cylinders which are provided with fluid communication during, at least,

  the initial part of the working race.

  The second piston-cylinder assembly of the agen-

  cement is provided with a means of escape, thanks to an adjustment

  loosely between the piston and the cylinder or to leakage holes made through the second piston. The second piston-cylinder assembly brings the working fluid to a first pressure level and, as a result of the leakage which occurs in this assembly, the rod

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  common piston moves in the direction of the working stroke, so that the third piston-cylinder assembly comes into operation and provides the second level of pressure, i.e. the final pressure of the driving stroke. In the operation of known systems, the first level is generally used to block the workpiece on the press table by means of an ejection plate and the second level is used for the action

of punching.

  Although known systems give full-

  satisfaction, it is desirable to incorporate a pressure intensifier system which may be

  combined with an integrated plunger system that pre-

  feels a longer working stroke so that, for example, it is easier to insert the parts into the place where the punching is carried out

  or remove them. We can get this result, well-

  tensioned, using known systems by increasing the length of the working stroke. However, there are

  is a waste of energy, and generally

  rale, pressure boosting devices more

larger than is desirable.

  This is why an object of the present invention

  tion is to provide a pressure booster which allows to carry a working fluid at three pressure levels. Another object of the present invention is to provide a pressure booster which can have a longer working stroke than the normal stroke or a greater displacement of the working fluid

  with minimal additional energy use.

  According to the present invention, a

  fourth piston-cylinder assembly with coa-

  xial known, this fourth assembly being provided with what is called a floating piston which is put into operation initially by applying to it by switching the main pressure to pass the working fluid from the fourth cylinder, which at the start of the working stroke is in fluid communication with the second cylinder (and the third cylinder), in the second and third cylinders so as to apply to the latter a first pressure level equal to that of the primary source. This first pressure level is sufficient to compensate for the floating, that is to say to move the plunger over a free travel distance in order to bring it against a part lying on

the table of a machine tool.

  Then apply the primary pressure to the

  piston of the first piston-cylinder assembly of the

  coaxial cement to move the piston rod, joint

  with the second and third pistons, in the di-

  rection of the working stroke. Amplified pressure

  is applied to the working fluid by the second

  seems piston-cylinder. As a result of the diversion leak

  vation of this assembly, the pistons and the conti

  move to move in the direction of the working stroke, so as to then close the communication between the second and fourth cylinders by means of the third piston which penetrates into the third cylinder and which acts as a sealing element between the second and fourth cylinder. Then, the pressure exerted on the working fluid is determined by the third piston-cylinder assembly and the final pressure level is obtained. The useful working surfaces of the second and third pistons are chosen so that the final pressure level is the highest, the two levels corresponding to pressures higher than those produced by the pressure source

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  primary thanks to the floating piston. In this way, an amplifier with three pressure stages is obtained with the possibility of a long stroke at low pressure.

  so as to conserve energy and allow simulta-

  Clearly a larger free space between a working plunger and a press table. The present invention will now be described with reference to the figures of the drawings, among which: FIG. 1 shows the pressure amplifier before the start of a working stroke; figure 2 shows the pressure booster

  to the floating piston from which the main pressure is applied

  cipal; and Figures 3 and 4 show the pressure intensifier in intermediate and final positions

  that it occupies in the direction of the displacement race

pistons.

  Referring to Figure 1, it can be seen that the pressure intensifying apparatus is shown in its rest position from which a working stroke begins. The apparatus includes an arrangement of multiple piston-cylinder assemblies including an enclosure 1, 2, shown in a stepped form, well

  that this is only essential for economic reasons

crumb of matter and weight.

  The upper part 1 of larger diameter of the envelope comprises a piston-cylinder assembly 1 (a), 3 (first piston-cylinder assembly) actuated by

  a primary pressure source (air), this part

  carrying a pressure inlet orifice 13 connected to a

  primary pressure source line 15 through

  diary of a control valve 14. A return spring 7 is disposed between the piston 3 and the bottom wall 1 (c) of the piston-cylinder assembly 1 (a), 3. The piston 3 258o2060 is mounted on a rod 6 piston with part of smaller diameter which extends downwards

in cylinder 2.

  A fourth piston-cylinder assembly 21, 1 (b) is disposed immediately below the first piston-cylinder assembly. The piston 21 is a "floating piston" which can slide on a smooth bearing 5 which surrounds the piston rod 6. The bearing 5 could be eliminated, but its use facilitates an overall shortening of the device, given that the reduction in diameter of the rod 6 must be taken into account to avoid a blockage between the piston 21 and the rod 6. The cylinder 1 (b) is provided with an orifice 12 for the entry of the pressure from the primary source via a valve or distributor 14, the primary pressure thus being applied to the upper side of the piston 21. The cylinder 1 (b), below the piston 21, is filled with a working fluid which communicates, via the passage 22, with the space surrounding the rod section 20 of reduced diameter and via the holes of leak 18, 19 formed in the piston 4, with the fluid

  working 11 located in cylinder 2.

  A second piston-cylinder assembly 4, 2 is arranged below the cylinder 1 (b). The piston 4 is rigidly fixed to the reduced diameter portion 20 of the rod 6. The piston 4 is provided with a metering hole 18 and two other leakage holes 19 which can be closed by a valve plate 16 which can be moved axially over a reduced diameter part of the piston 4. The valve plate 16 is fixed on the

  rod part 20 using a thrust washer 17.

  A third piston-cylinder assembly is constituted by a piston rod 6 (piston) and a cylinder 2 comprising the opening 23 formed in the

  partition 1 (d) for the piston rod 6.

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  In a preferred embodiment of the invention,

  vention, the lower end of the cylinder 2 comprises a plunger 9 and a plunger actuating piston 8 fixed to the latter. A plunger return spring is provided, as shown in 10, so that when a working stroke is finished, the plunger is brought back to the upper limit of its stroke, thereby releasing a part to allow removal. Instead of the spring 10, compressed air can be used to

diver recall.

  It should be noted that instead of using

  a plunger system integrated into the layout, we can

  would take the working fluid 11 so as to supply it, under its working pressure, to a

remote diver.

  During system operation, the pressure

  primary pressure, normally compressed air pressure, is applied, via a conduit 15 at the start of a triggered working stroke, either by an operator or automatically, to the upper side of the floating piston 21 which immediately moves to the

  low, at a predetermined speed which depends on the pressure

  air as well as passage 22, so as to

  tread the working fluid 11 through the passage 22, the space surrounding the reduced diameter portion 20 of the piston rod 6, the holes 19 made in the piston 4 so as to instantly move the piston 8 of the plunger

  down under reduced pressure.

  After a delay that can be programmed in

  the valve 14 and which is sufficient to allow a de-

  complete placement of the floating piston 21 downwards, air pressure is applied to the upper side of the piston 3 which moves the piston rod 6 downwards in

  bringing with it the piston 4. the piston 4, which pre-

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  feels a reduced working surface with respect to the piston 3, applies an amplified pressure to the working fluid 11. After a predetermined displacement of the pistons 3 and 5 downwards, the part of the diameter of the piston rod 6 of the piston which is not reduced in diameter enters the sealing zone 23 of the partition 1 (d) and the pressure exerted on the working fluid 11 applied to the piston 8 of the plunger is again amplified in the ratio existing between the working areas of the pistons 3 and 6 (area of the straight section of rod 6), so that the total working pressure is available

  for the final operation to be performed on the part.

  Then, the valve 14 is actuated so as to release the air pressure exerted on the pistons 3 and 21. The piston 3 is recalled in its. position of

  departure by return spring 7, while the res-

  plunger return spell 10 exerts on the plunger piston 8 a return pressure which discharges the oil through the return holes 19 of the piston 4, so as to return the floating piston 21 to its position

  departure. It will be understood that the pistons 3 and 8 do not fall out.

  not necessarily place together during the race of

  reminder, since each is actuated by a res-

separate recall spell.

  It is now clear that the arrangement of

  piston and cylinder sockets according to the present in-

  vention exerts on the working fluid 11 and, by con-

  sequent, on the piston 8 of the plunger, three pressure levels, that is to say the primary pressure (air), the first amplified pressure resulting from the ratio between the useful working areas of the pistons 3 and 4

  the strongly amplified final pressure resulting from the

  port between the working areas of the piston 3

and piston rod 6.

  It is understood that the description which

  above has been given for illustrative purposes only

  and not limiting and that variants or modifications

  can be brought in as part of the pro

invention.

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Claims (5)

  1. Pressure booster system for   bringing the pressure of a fluid to several levels,   taking first, second and third sets of piston and cylinder (3, la; 4, 2; 6, 2) aligned coaxia-   the pistons (4, 6) of the second and third sets   sembles being rigidly attached to a piston rod   mune (6), the first piston (3) having a larger working surface area than that of the second piston (4), a working fluid chamber located between the cylinders of the first and second sets and through which the rod passes (6) piston, the cylinder of the second assembly being provided with a fluid connection between itself and the fluid chamber, the fluid chamber and the cylinder of the second assembly containing a   common working fluid, the piston rod (6) comprises   as a part of reduced section between the first and   second sets, the reduced section part is   in the fluid connection when the piston rod is in its non-actuated position of a working cycle, so that there is communication   fluid between the chamber and the cylinder of the second   seems, the third set of piston and cylinder (6, 2) being constituted by the section part not   reduction of the piston rod and by the fluid connection   dique, respectively, the third set of piston and cylinder becoming active only in a predetermined position of the piston rod in the direction of   the working stroke, in relation to the position not ac-   the second set of piston and cylinder   with limited working fluid leakage   in a working stroke to allow the piston rod to continue to move in the direction of the working stroke under the pressure of a primary fluid pressure applied to the first set of piston and cylinder to generate a working cycle , a fourth set of piston and cylinder (21, 1 (b)) being disposed between the first and second sets of   piston and cylinder (3, la), the piston (21) of the fourth   th assembly being a floating piston surrounding the common piston rod (6) in the zone of reduced section at the start of a working stroke and which can be moved axially along this rod, a valve means (14) being adjustable to provide, at the start of a work stroke, the primary fluid pressure at the   piston floating so as to move it in the direction   tion of the working stroke to discharge the common working fluid through the fluid connection in the second cylinder, the valve (14) can then be actuated to apply the primary fluid pressure to the first piston so as to move this piston in the direction of the working stroke and to provide a first amplification of the pressure of the working fluid in the cylinder of the second set by a joint displacement of the piston of the second set in   the direction of the working race and after the shift   cement of the piston rod in the direction of the   working stroke over a distance beyond the posi-   predetermined tion, the pressure of the working fluid in the cylinder of the second set being further increased mainly by the single third set of   piston and cylinder, and means present for use   read the working fluid under pressure.   2. System according to claim 1, character-   laughed at by the fact that the fluid leakage is ensured by   a loose fit between the piston (4) and the lindre (2) of the second set.   3. System according to claim 1, character-   laughed at by the fact that the fluid leakage is ensured by a pressure leakage hole (18) made through the piston of the second set.   4. System according to any one of claims 1, 2, or 3, characterized in that the second set of piston and cylinder is provided with a pressure relief valve (16) which becomes   active during the work cycle return stroke.   5. System according to any one of the claims.   cations 1, 2 or 3, characterized in that in the valve means (14) a delay is programmed to automatically apply the primary fluid pressure to the first piston after a predetermined time following the application of the pressure to the fourth piston (21).