DE1752608A1 - Press cushions or the like, in particular for drawing presses - Google Patents

Description

DIPL.-ING. GÜNTHER SCHMITZ-HELPF DIFL.-ING. HANS VOIiLBACII PATENT LAWYERS

5 COLOGNE, Gereonshof 38 Telephone (92) 21 30 32

June 20, 1968

Official sign

E. W. Bliss

Applicant in: Q _ompany file no. ^ 8062 Vo / S

Press cushions or the like., In particular for drawing presses M.

The invention relates to a closed structural unit Press cushion or the like, in particular for drawing presses, which is provided with a chamber that forms a pressure cushion. Preferably is the press cushion according to the invention or the like, for such Pressing determined that holds down on downward rods ering a drawing die or a drawing punch, although the device according to the invention is also used in other presses

M a press cushion or a mold cushion can be used. ^

The press tools or porms used in presses usually have hold-down rings or other auxiliary elements that are controlled to a certain extent by a press cushion which is arranged below the press bed. These press or Pormenkiesen are of different types; In general, they consist of two telescopically inserted or joined sleeves, which have a pressure pad chamber between their front walls

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form, which is filled with a compressible pressure medium, so that the upper sleeve is pushed upwards. On this top sleeve rests a number of rods which protrude downwards from the ram or the mold inside the press. The rods have an effect movable elements within the form or the like. so together that the sleeve after the rods during the downstroke of the press is pressed down. During the downward movement of the upper sleeve, the pressure medium in the pressure pad chamber is compressed, so that the bars are pushed upward from the upper sleeve during the upward stroke of the press. That in the chamber of the pressure pad The volume of air or other compressible pressure medium located is so large that one for the downwardly protruding Rods sufficiently large pretensioning force is achieved.

In these known devices, it is used as a repair tool subjected or replaced, the pressure or pressure pad must be lowered into the rest position. This usually takes place in that the pressure pad chamber is vented Wd in a pressure-relieved manner will. However, this requires a relatively long time in the known devices; in addition, the big one must then Volume of the pressure pad can be refilled with the pressure medium. For the venting and subsequent filling of the pressure pad chamber To reduce the amount of time required, feed conduits with large conduit cross-sections are used However, hoses are expensive; In addition, the hereby achieved

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Time saving for lowering the press cushion into the rest position and the later lifting of the same into the working position is relatively small. To eliminate these disadvantages, one has proposed a pressure medium storage container near the stamp pad to store, which is connected to the pressure pad chamber via a valve, so that when the pressure pad is lowered, the Pressure medium flows through the open valve into the storage container. The valve is then closed, so that the pressure medium remains in the reservoir. To raise the press cushion again, the valve is opened, so that the pressure medium again can flow back into the pressure pad chamber. These devices require considerable construction costs and are accordingly high Costs"

I ^v Lan has already proposed to design the device described above in such a way that the storage container with the valve is housed inside the press or pressure gravel itself. In this case, there is no connection line between the storage container and the pressure pad chamber. The disadvantage here, however, is that the valve located between the storage container and the press cushion must be actuated mechanically from the outside of the press cushion. It is therefore necessary to arrange a rod or some other valve operating device inside the press cushion. If the valve is damaged, the entire press cushion must be removed for repair purposes.

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The arrangement of the valve device inside the cushion is conditional In addition, difficulties in accommodating hydraulic control devices or hydraulic hold-down devices, which are in the generally be provided when using a press cushion. The hydraulic control device is used to control the upward s movement of the press cushion so that it is slightly out of phase with the upward stroke of the press. The hydraulic one Hold-down device is used to lock the cushion in the lowered rest position.

The main object of the invention is to address these disadvantages the previously known press or drawing cushion or the like. to be remedied with structurally simple means.

The device according to the invention is generally characterized in that that the pressure pad chamber is divided into separate pressure chambers or a further pressure chamber is assigned to it, that the one of the two pressure chambers or the chamber can be relieved of pressure and the pressure spaces or the chamber and the pressure space assigned to it can be changed in their volume content as a function of pressure. It will In this way, a reservoir is created in which, when the press cushion is lowered or the pressure chamber is vented, the Pressure medium remains in stock and its pressure medium content together with that in the other pressure space or in the pressure chamber Pressure medium forms the pressure cushion which absorbs the external load and causes the prestress. As for the lowering of the Druck- or Pressenkiseens only one of the two pressure rooms from

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Pressure needs to be relieved or vented, the Carry out the lowering process very quickly, so can also accomplish the "charging" of the pressure pad extremely quickly, since in this case only a fraction of the total pressure medium content of the pressure pad needs to be refilled. It is also advantageous that the pressure medium or air requirement is only very low.

In a structurally advantageous manner, the interior of the pressure cushion m is divided by a movable «/ and, preferably a piston or a memorandum, into two pressure chambers, which are sealed against each other, but connected via the movable wall depending on pressure, so that both pressure chambers together or the Pressure medium contained in both pressure areas together form the pressure pad. The invention thus offers the possibility of using the interior or the pressure chamber of the pressure pad fully for pressure relief, but at the same time using a part of this pressure chamber as a storage container, which in this case also has the function of a pressure pad. It is advisable to arrange the arrangement in such a way that the largest possible volume of one pressure space, which also functions as a reservoir, from which the pressure medium does not escape when the pressure pad is lowered, is significantly larger than the largest possible volume of the other pressure space.

The pressure pad is expediently of a cylinder sleeve or the like.

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and one opposite this movable telescopic sleeve or the like. educated, these two sleeve or cylinder parts between their bottom or end walls form a pressure chamber that over the movable wall is divided into the two pressure spaces mentioned. One of these two pressure chambers, specifically the one in the volume smaller pressure chamber is to reset the telescopic sleeve or the like. relieved of pressure in the rest position or can be vented, while the pressure medium in the other pressure chamber remains stored therein. To prevent the moving Partition wall during pressure relief or venting of one pressure space under the internal pressure of the other pressure space as above far adjusted that the return movement of the telescopic sleeve or the like. is prevented, an expansion limitation, "preferably in the form of a stop or the like. Provided. In the case of a vertical arrangement of the two pressure chambers, the upper pressure chamber for lowering the pressure cushion can advantageously be relieved of pressure or vented, while the pressure space below forms the aforementioned storage space.

According to a further feature of the invention, the two are mentioned Pressure chambers connected to one another via a pressure medium connection, with an automatically operating shut-off device being provided is that the pressure medium connection between these pressure chambers at Pressure relief of one pressure room automatically, locks off. The pressure medium connection is preferably made via the piston, the

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here it is arranged so that it is in the Huendstellung the pressure medium connection closes automatically.

Exemplary embodiments of the invention are shown in the drawing. Bs show:

Pig. 1 schematically in a 'file section a first embodiment the invention;

Fig. 2 also in section a second embodiment of the - Invention;

Pig. 3-5, each in a partial section, structural changes to the devices shown in FIGS. 1 and 2;

Pig. 6 shows a further exemplary embodiment of the invention in section;

Pig. 7 shows the embodiment according to Pig. 6 in another operating position;

8 and 9, in section, a further embodiment of the invention in different operating positions.

In the drawing, in which some preferred embodiments of the ™ Invention are reproduced, FIG. 1 shows a drawing or press cushion A designed as a closed structural unit, which is mounted on a support plate B which is fastened to the lower frame of the press (not shown) by means of bolts 10 and 12. How such pressure pads work in connection with the Presee is generally known, so that a detailed

* clarification may be superfluous. . · ■

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The press or mold cushion (hereinafter referred to as the pressure cushion) has a stationary sleeve 20, which is attached to its lower face 22 on a lower end wall 24 by means of an

number around the sleeve arranged screw bolts 26 is attached. The wall 24 is correspondingly by means of bolts 28 on the support plate B attached. A seal, such as an O-ring seal 30, is disposed between the pad 22 and the end wall 24. the On its cylindrical outer surface, the sleeve 20 forms a bearing surface 32 which ends at a recess 34 which has a stop shoulder 36 forms. Near the top of the sleeve 20 is a diameter 38 is arranged. The upper end of the sleeve has a relatively large opening 40, the circumference of a Plansch 42 is limited, which forms a lower stop shoulder 44.

On the sleeve 20, a sleeve 50 is guided telescopically in both stroke directions. The sleeve 50, which forms the lifting-movable working element of the pressure pad, has a base 52. With its inner surface 54, it is guided in a sliding manner on the lateral surface 32. A stop 56 arranged at the end of the sleeve interacts with the stop 36 in such a way that the sleeve 50 cannot be pulled off the sleeve 20. The end wall or bottom 52 has an end face 58 which can come into contact with the lower bands of actuating rods 60. These

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As is known in presses, bars are associated with the various elements connected, which are arranged within the form or the press tool mounted on the base of the press.

The sleeves 20 and 50 form an internal pressure pad chamber 70, which is filled with pressurized pressure medium via a supply line 72. The line 72 has a branch 74, which is connected to the bottom of the chamber 70, and another branch line 76, which is connected to the top of the chamber 70 in Connection. The latter connection is made via a channel 80, a line 82 and a check valve 84 and a Control valve 86. The valve 86 is adjustable so that it connects the line 82 to a drain line 88. In line 74 can a check valve can also be arranged.

The pressure pad described so far differs with one exception of the pressure medium supply system and the flange 44 are only insignificantly different from the pressure pad of the usual design.

In operation, the rods 60 are connected to certain elements within the mold, such as ejector pins or a pull ring. At the The downstroke of the press that closes the mold the rods 60 the sleeve 50 from the starting position a in the lower lowered position b downwards. During this process, a Pressure on the pressure chamber 70. Presses on the upward stroke of the press the pressure acting in the pressure chamber 70 moves the sleeve 50 back into

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their starting position a. The rods 60 are raised here, depending on the element they control the required Make punctures within the press tool. This process is repeated with every press cycle. The pressure medium volume inside chamber 70 is approximately V when sleeve 50 is in position a. In the lowered position b of the sleeve is the volume of the chamber 70 corresponding to V,. The volume difference during normal operation of pressure pad A

is accordingly V minus V,.
away

According to the invention, the sleeve 20 is movable in the vertical direction with a Wall. 90 is provided in the form of a piston which has a piston skirt 94 with a circumferential seal 96 on its piston crown 92. A spring 98 pushes the piston 90 upwards., The movable wall or the piston 90 divides the chamber 70 into an upper pressure chamber 100 and a lower pressure chamber 102. The lower pressure chamber has a variable volume V, which is dependent on the position of the piston 90 in the sleeve 20. The volume V \ is always considerably smaller than the volume V and, in the exemplary embodiment shown in FIG. 1, also smaller than the volume V. The piston 90 accordingly forms two separate, mutually insulated Pressure spaces within the pressure chamber 70.

In operation, the sleeve 50 moves during normal operation of the pressure cushion A between the two band positions a and b.

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This has the consequence that that located in the pressure chambers 100 and 102 Pressure medium is alternately compressed and expanded. In this mode of operation, the piston 90 oscillates within the sleeve 20. In the embodiment according to FIG. 1, there is no pressure medium connection between the pressure chambers 100 and 102. The two Pressure chambers are only connected to one another as a function of pressure via the piston 90 acted upon on both sides. How the mit The effect of a pressure cushion filled with air or another pressure medium is practically the same as that of a pressure cushion, which does not have a piston 90 or the like. having.

If a mold lying in the press is to be repaired or replaced, the pressure pad must be lowered. This is achieved in that the pressure chamber 100 is vented by actuating the valve 86 accordingly. If the pressure in the pressure chamber 100 drops, the piston 90 moves upwards against the stop 44 under the action of the pressure medium in the pressure chamber 102 Pressure pad so that it does not need to be replaced when the pressure pad is activated later. In order to activate the pressure pad, the valve 86 is brought into the position shown in FIG. 1, in which the pressure medium reaches the upper pressure chamber 100 via the supply line 52 and the channel CO. This brings the pressure gravel back into its working position.

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It can be seen that during this process only the volume of air required to fill the pressure chamber 100 is supplied must be, although the pressure pad in operation against the entire volume of the pressure medium located in the two spaces 100 and 102 is working. Since only a small volume of air is required to activate the pressure cushion, this is necessary for filling it up as well as the relieving of the pressure pad required period of time extremely small. The wall or the piston 90 seals the When the pressure pad is lowered, the pressure chamber 102 decreases towards the outside. Since no pressure can thus build up in the pressure chamber 100, there remains the pressure pad is lowered under all circumstances during the replacement or repair of the mold. The one in Pig. I pictured In addition, the device does not require any expensive valve devices within the pressure pad or other devices for an inner reservoir which receives the pressure medium when the pressure pad is lowered and it when it is activated again of the pressure pad returns to this.

In Pig. 2 is a modified embodiment of that shown in FIG preferred device according to the invention. The sleeve 20 is attached to a bearing plate 110 here, which has a has a relatively large opening 112. A hydraulic locking device 120 of largely conventional design is attached to the underside of plate 110. The control rod 122 the hydraulic locking device extends from the

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Bottom 52 of the sleeve 50 through, an opening 124 of the with a seal 126 and through an opening 130 of the device 120 downwards. In the hydraulic locking device 120 is the usual working piston 134. The lower area of the sleeve 20, in the hydraulic pressure medium 136 is, is via a line 138 to the interior of the locking device 120 connected. The arrangement of the piston 90 thus results in a unit designed as a closed structural unit Pressure cushion, which is provided with a hydraulic locking device of conventional type, without this a significant change in the pressure pad is required. This is a particular advantage, as in certain establishments Hydraulic locking devices must be provided to hold the pressure pad during certain sections of a cycle or in its inoperative state during various operations of the press to keep the division.

In FIG. 3 , a modified embodiment of the piston 90 is shown. The piston 90a is here on the circumference with a seal 140 and with spaced- apart flat seals 142 and 146 or the like. provided through which the piston rod 122 is passed. A spring 146 surrounding the piston rod 122 presses the piston 90a into its upper position.

In the embodiment according to FIG. 4 there is one hydraulic actuating

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device or the like. (snubber) 150 below the bottom wall of the sleeve 20 arranged. The control rod 122 has a piston 134 at the lower end; it is connected to the floor 52, as in FIG. 2 shown. The hydraulic adjusting device 150 or the like. is with a control valve device 152, so that the movement of the sleeve 50 is controlled on the upstroke after the working stroke. This causes an abrupt upward movement of the rods 60 during the operation of the Druckk ^ ssens according to FIGS. 1 and 2 prevented. This embodiment according to FIG. 4 shows that it is possible without difficulty to use the pressure pad according to the invention to connect hydraulic starting or adjusting device of conventional design. . ·

In the embodiment according to FIG. 5, the fixedly arranged sleeve 160 has an inner flange 162 with a circumferential seal 164 arranged on the underside. The piston 170, which is movable in both stroke directions, is provided with a downwardly projecting rod 172 which engages in a bore 174 in which a spring 176 lies. The bore 174 is closed on the underside by means of a plate 178. The piston 170 has a number of circumferential grooves 180 which create a pressure "connection" between the upper pressure space 182 and the "lower pressure area 184 within the sleeve" 160. The "a j & rfang disordered Hilt *" 180 are sealed when the piston 170 is in an upper stroke position against the seal I64. Will deageaäü b «i diewr execution form the

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Pressure pad lowered, so the pressure chamber 182 between the cylindrical Sleeve 160 and the (not shown) sleeve 50 ent-. ventilates, whereby a pressure difference is formed on the piston 170, under the action of which the piston is pressed up against the seal 164. The pressure in the pressure chamber 184 keeps the piston in the sealing position until the pressure chamber 182 is pressurized again by introducing a pressure medium. During operation in this embodiment there is a pressure medium connection between the upper pressure chamber 182 and the lower pressure chamber 184 the movable piston 170.

In the embodiment according to aen Pig. 6 and 7, a stationary sleeve 190 is provided with an upper opening 192 which is covered by a flexible membrane 194. A rigid perforated plate 196 is attached to the sleeve 190 above the membrane. The membrane divides the stationary sleeve into two separate, mutually sealed pressure medium spaces 200 and 202. In the arrangement j; em according to I ¹ Xg. 6, the pressure in the pressure chamber 202 is essentially zero. The membrane 194 deforms downwards when the sleeve 50 is pressed downwards by the rods 60 while the pressure pad is loaded. During the upward movement of the rods 60, the membrane forms back upwards again.

If the pressure chamber 202 inside the sleeve 50 is vented, see above the pressure medium remains enclosed in the pressure chamber 200; the membrane 194 moves upwards in contact with the

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Plate 196 as shown in FIG.

A similar device is shown in FIGS. At this Embodiment, a stationary sleeve 210 is provided with an arm star 212 on which a rod guide 214 is mounted. The rod 122 of a hydraulic adjusting device (Fig. 4) or a hydraulic locking device is in this guide sealed by means of seals 216, 218. Since a central guide is used, there is a circular opening 220 at the top the stationary sleeve, which is sealed by means of a circular membrane 222. Above the membrane is a circular one Perforated plate 224 attached, which limits the upward movement or the masking of the membrane 222 upward. the Membrane divides the interior of the stationary sleeve into separate, mutually sealed spaces 230 and 232. Is the space 232 relieved of pressure, the membrane is in its upper position according to FIG. 8.

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Claims (13)

Claims A press cushion or the like designed as a closed structural unit, in particular for drawing presses, with a chamber forming a pressure cushion, characterized in that the chamber (70) is divided into separate pressure spaces (100, 102; 182, 184; 200, 202; 230, 232 ) subdivided or a further pressure chamber is assigned to it, that the pressure chambers or the chamber and the pressure chamber can be changed in% of their volume content as a function of pressure and that one of the two pressure chambers can be relieved of pressure. 2. Apparatus according to claim 1, characterized in that the pressure pad of a cylinder sleeve (20, 160, 190, 210) or the like. and one opposite this movable telescopic sleeve (50) or the like. is formed, which enclose a chamber (70) which is divided into separate pressure chambers (100, 102; 182, 184; 200, 202; 230, 232), one of which for resetting the telescopic λ sleeve (50) in the rest position can be relieved of pressure or vented, while the other has a pressure-dependent variable volume with an expansion limit (44 _f 196, 224). 3. Apparatus according to claim 1 or 2, characterized in that the pressure pad chamber (70) through a rigid wall movable in the chamber, preferably a piston (90, 170) into two pressure spaces is divided. 1098? 3 / (K31 4. Apparatus according to claim 3 »characterized in that the expansion limitation consists of a stop (44) which is above the movable wall or the piston (90, 170) on the cylinder sleeve is arranged. 5. Device according to one of claims 1-4, characterized in that that the movable wall or the piston (90, 170) is guided with a piston skirt (94) in the cylinder sleeve (20, 160). 6. Device according to one of claims 1-5, characterized in that that the upper pressure chamber (100, 182, 200, 232) can be relieved of pressure in order to lower the telescopic sleeve (50). 7. Device according to one of claims 1-6, characterized in that that the telescopic sleeve (50) or the like. is cup-shaped and the cylinder sleeve closed at the bottom on its top overlaps. 8. Device according to one of claims 1-7, characterized in that that the one pressure chamber, preferably the upper pressure chamber of the pressure pad, independently of the other pressure chamber with the pressurized compressible pressure medium can be filled. 9. Device according to one of claims 1-7, characterized in that the two pressure chambers (200, 202; 230, 232) by a deformable ^ intermediate wall, preferably in F _o rm a diaphragm (194, 222) are separated from each other. 10982 3/0431 10. The device according to claim 9, characterized in that a perforated membrane supporting the expansion limit Plate (196, 224) is provided. 11. Device according to one of claims 1-10, characterized in that that the volume (V) of the one pressure chamber (102) in all operating states is significantly smaller than the total volume (V) both pressure chambers, but in all operating 3. stands is considerably larger than the volume (V,) of the other m pressure chamber of the pressure cushion. 12. Device according to one of claims 1-11, characterized in that that the two "pressure spaces (182, 184) have a pressure medium connection are connected to each other and that an automatic shut-off device is provided, which the pressure medium connection of the two pressure chambers when the pressure in one of the pressure chambers (182) is relieved. ■ 13. The device according to claim 12, characterized in that the M Druckmittelverbinaung (180) on the piston (170) is arranged so that it is automatically closed in the stroke end position of aes piston. 1 0 9 r ■ ^ / 0 / _; ' Blank page