EP0173184B1 - Power press, particularly for use in drawing and deep-drawing operations - Google Patents

Description

The invention relates to a press, in particular for drawing and deep-drawing operations, with a tool part designed as a ram, with a tool part designed as a punch, and with a sheet metal or hold-down device used to hold the sheet-like workpiece to be deformed, between its lower part facing away from the tool part to be held and the press frame or table supporting it, for supporting the sheet metal or hold-down device, a plurality of pressure-adjustable intermediate members distributed over the surface of the sheet metal or hold-down device are arranged, and with a holding block against which the plunger can rest firmly during the pressing process.

Such a press is known for example from GB-A-1 369 112. Here, the plunger is adjustably arranged on an upper plate and opposite it is the movable drawing punch, which is located inside an annular housing. The plunger is connected to the piston of a hydraulic piston-cylinder unit via a rod for its actuation. A viscous liquid acts as a sheet metal or hold-down device and is located in chambers of the housing, which are open towards the ram. During a machining operation, the workpiece is arranged between the plunger and the housing, the viscous liquid being pressurized so that it directly acts on one side surface of the workpiece and presses it against the punch with its opposite side surface. The pressure for the sheet metal or. Viscous liquid forming hold-downs provide several intermediate members which are designed as pistons running in the housing, the pressure of the liquid being able to be varied in accordance with their respective displacement position.

The intermediate members designed as pistons are connected to a hydraulic piston-cylinder unit via actuating rods, and depending on the position of the actuating piston there is a more or less high fluid pressure of the sheet metal or hold-down device. Since the sheet metal or hold-down device is made of viscous material, it is possible to compensate for different workpiece thicknesses, but it is disadvantageous that there is always an even pressure distribution, so that the workpiece surface as a whole is subjected to constant sheet metal holder pressure. This makes it impossible to partially influence the drawing behavior of the individual workpieces, since the same holding pressure is set at every point. In the press according to GB-A-1 369 112, it is therefore necessary to provide various inlet and outlet openings on the workpiece side in order to influence the flow behavior of the workpieces on the housing which receives the viscous liquid, with a certain flow pressure additionally being generated by the flowing liquid becomes. However, this method is very complex, especially since the arrangement of the openings is only suitable for a specific workpiece. In addition, the known press is very complicated in construction and that problems can arise due to the use of the liquid, which prohibit its use in large-scale production.

It is therefore the object of the invention to provide a press according to the type mentioned at the outset, which has a simpler, less susceptible construction and in which the sheet metal or hold-down device both compensates for different material thicknesses of the workpiece and also the partial drawing or Flow behavior of the workpiece can be influenced in a simple manner.

This object is achieved in that the sheet metal or hold-down device is a solid body, on the lower part of which the separately elastic intermediate members rest with a support surface and that the support force of the individual intermediate members exerted on the sheet metal or hold-down device can be adjusted independently of one another. This results in a simpler construction of the press, since the use of a solid body as a sheet metal or hold-down device makes complex sealing measures unnecessary. In order nevertheless to be able to take into account different material thicknesses on the part of the respective workpiece, the respective intermediate members which bear against the sheet metal or hold-down device and act on it are each designed separately, that is to say separately, in an elastically resilient manner. This allows the sheet metal or hold-down device to adapt automatically to a certain extent to the material thickness. Since, in addition, the supporting force exerted by the individual intermediate members on the sheet metal or hold-down device can be adjusted independently of one another, it is possible to apply individual portions of the sheet-metal or hold-down device to different extents, so that the holding force acting on the workpiece can be partially changed . The latter is particularly advantageous if the depth of draw exerted by the stamp varies over the stamp surface, since here the choice of different holding pressures can influence the reflow behavior of the workpiece as required. It is also advantageous that the sheet metal or. Hold-down pressure can be changed very quickly, so that different types of workpieces can be drawn one after the other without having to make changes to the sheet metal or hold-down device, as in the prior art.

Advantageous developments of the invention are set out in the subclaims.

In the development according to claim 2, the elasticity of the intermediate links results from that they are themselves elastic-resilient, so that no additional spring elements are required.

The development according to claim 3 describes simple ways to vary the support force of the individual links.

The developments according to claims 4 to 7 describe simple ways to hold the intermediate links on the press.

In the development according to claim 8, the desired resilient property can be achieved by using additional resilient, elastic spring elements. The spring elements can be mechanically resilient or fluidic, e.g. B. be hydraulically resilient.

In the development according to claim 9, trouble-free automatic operation of the press is required, which above all allows use in mass production.

The further developments according to claims 12 to 14 describe advantageous intermediate elements in terms of their construction, the elasticity being able to be changed simply by using more or fewer pressure plates.

• Fig. 1 einen Teil einer Pressenanordnung in einer Seitenansicht teilweise geschnitten und in schematischer Darstellung,
• Fig. 2 einen Vergleich zwischen nach altem System arbeitenden Pressen (Fig. 2a) und nach einem Ausführungsbeispiel der Erfindung räumlich besser nutzbaren Presse (Fig. 2b) in einer Seitenansicht und in schematischer Darstellung, teilweise geschnitten,
• Fig. 3a und
• Fig. 3b die Ausbildung der Zwischenglieder als verschiebbare Einzelblöcke (Fig. 3a) bzw. als fester Blechhalterblock (Fig. 3b) jeweils in einer Seitenansicht im Schnitt und in schematischer Darstellung,
• Fig. 4 das Hydraulikschema einer mit mehreren Zwischengliedern versehenen, stufenlos einstellbaren Blechhalterung in schematischer Darstellung,
• Fig. 5 die Anordnung bei stufenloser Regelung über die Elastiblock-Vorspannung und
• Fig. 6 die Anordnung bei stufenloser Regelung über ein Druckmittelventil, diese beiden letztgenannten Anordnungen jeweils in einer schematischen Darstellung.

Exemplary embodiments of the subject matter of the invention are shown in the drawing. Show it:

• 1 shows a part of a press arrangement in a side view, partially in section and in a schematic illustration,
• 2 shows a comparison between presses operating according to the old system (FIG. 2a) and press (FIG. 2b), which can be used more spatially according to one embodiment of the invention, in a side view and in a schematic representation, partly in section,
• 3a and
• 3b the formation of the intermediate links as displaceable individual blocks (FIG. 3a) or as a fixed sheet metal holder block (FIG. 3b) in each case in a side view in section and in a schematic representation,
• 4 shows a schematic illustration of the hydraulic diagram of a continuously adjustable sheet metal holder provided with a plurality of intermediate members,
• Fig. 5 shows the arrangement with stepless control via the elastiblock bias and
• Fig. 6 shows the arrangement with stepless control via a pressure medium valve, these two latter arrangements each in a schematic representation.

The arrangement shown in FIG. 1 is a press, in particular for drawing and deep-drawing operations, which has an upper part 1, which can also be referred to as a ram, and a lower tool part or drawing punch 2. 3 is the die, which is connected to the upper part 1. To hold the sheet-like workpiece 4 to be deformed, a sheet metal or hold-down device 5 is used, which contains at least one sub-section 55 which is supported on the press table 6 or on the tool base frame 11. The arrangement is such that a plurality of intermediate elements 7 are interposed between the lower part 55 of the sheet metal or hold-down device 5 and the press table 6 or underframe 11 supporting them, which are elastic and resilient and are evenly distributed over the surface of the sheet metal or hold-down device . 8 is the transfer plate for drawing, 9 the cylinder or cylinders producing the drawing movement from which the drawing pressure P2 is exerted 5 is the sheet metal holder, 10 is an adjustable holding block, 11 is the press frame. 12 is a possible connecting line for pulling with hydraulic counter-rotation, wherein the cylinder or cylinders 9 can also be arranged directly on or in the table 6.

The intermediate links 7, the elasticity or spring force of which can be changed or adjusted, as will be explained later, can be installed in the lower part 55 of the sheet metal or hold-down device 5 on its side facing the support surface, but they can also be installed in the press plate on the The side facing the sheet metal or hold-down device can be installed, furthermore they can be installed in the tool base frame 11 on the side facing the sheet metal or hold-down device or they can be seated in a split sheet holder near the sheet holder area. Finally, they can also be attached to the press plate or to the lower part of the tool on the side facing the sheet metal or hold-down device, they can be arranged displaceably and possibly centered, but they can also be inserted in bores on the corresponding support, or in or between top 1 and die 3.

The sheet holder is underlaid on the table with elastic intermediate members 7, so-called pressure lenses. The result is an elastic sheet metal holder which can be acted upon differently in some cases. The intermediate links 7 can be mechanically z. B. with spindles or wedges, but they can also be set hydraulically or pneumatically with pressure reading via load cells. Finally, additional resilient elements can be used to compensate for differences in thickness in the sheet. This results in a significantly better draw ratio, fewer rejects, fewer draw sequences.

As can be seen from FIG. 4, the carrier can be provided with a whole series of intermediate members 15, in which case these intermediate members can be acted upon in various ways become, you can adapt to all possible circumstances in this way, such. B. the pressure setting of the intermediate members 15 depending on the press stroke directly or indirectly or independently of the press stroke z. B. done via hydraulic or mechanical elements. It is particularly useful if the pressure setting of the individually arranged or grouped intermediate members 15 can be changed appropriately according to a program, for. B. can be continuously adjusted, what z. B. is possible if, according to FIG. 4, the intermediate elements 15 are connected to a manifold 16 and a pressure adjustment servo valve 17 is switched on in the connection between the manifold 16 and the pressure unit 18. In this way, it is possible that the intermediate links enable the adjustment to different press elasticities, for production reasons, preferably up to automatic, program-based adaptation.

The intermediate members 15 can, for. B. are biased by mechanical or hydraulic adjusting elements, for. B. over spindles or wedges. It can also - to compensate for differences in the thickness of the workpiece to be deformed, eg. B. in sheet thickness, additional resilient, elastic spring elements are provided with which the carrier for the intermediate members is equipped, such additional spring elements can be assigned to the intermediate members. These additional spring elements can be designed to be mechanically resilient; B. be hydraulically resilient.

3a and 3b, the above-mentioned intermediate members can consist of a cylinder 20 and one in this under the action of pressure medium, at 22, in the direction of the sheet metal and hold-down to piston 24 adjustable according to arrow 23, which have a pin 25 (a holding and biasing screw) is connected to a pressure plate 26, a block 28 consisting of a series of stacked discs 27 made of elastic material being interposed between the pressure plate and the piston. Here, the arrangement is such that the pressure plate is guided in the end region of the cylinder 20 facing the sheet metal or hold-down device and is movable with the piston 24, i.e. moves with the latter when it is adjusted under the pressure of the medium, and with this piston under Interposition of the block 28 consisting of stacked disks 27 made of elastic material is connected via the pin 25 in such a way that, due to the elasticity of the block, a slight, resilient relative movement between the pressure plate 26 and the piston 24 is possible, the cylinder in the plate - End holder or end area facing away opens a supply line 29 for the pressure medium. Here, the cylinder 20 sits with its lower region in a cylindrical bore 30 on the upper part of the associated support or plate 31, the supply line 29 for the pressure medium z. B. runs as a hole in the carrier or in the block or in the plate to the cylinder. 3a, the same parts are provided with the same reference numerals. Here, the cylinder or an in-line cylinder 20 is slidably guided with its lower region on the surface of the associated carrier 31, in which it sits in a block 32, which is displaceable on the surface of the carrier 31, the flexibly designed feed line 33 in this block 32 is connected.

The plunger can e.g. B. can only be set up by means of a small pressure holder pump to maintain the closing pressure, which is to be regarded as a further advantage of the subject of the invention. The intermediate links 7 can, for. B. via metering and pressure display manifold blocks or via a pressure adjustment valve battery connected to the pressure source. In Fig. 5 it is shown how stepless regulation takes place via the elastiblock pretension, 40 is the line to the tank, 41 is the line to the servo valve, 42 is the valve for lowering or releasing the pressure, 43 for regulating the pressure, 44 is the connection to the sheet metal holder cylinder, 45 the pressure gauge. While the continuous control via the elastiblock pretension is shown in FIG. 5, a continuous control via a pressure reducing valve is shown in FIG. This pressure reducing or regulating valve is shown at 47, 48 is the manometer. These controls can be controlled electronically digitally or incrementally in the same way with the program.

FIGS. 2a and 2b show a comparison of the two systems to be compared here: FIG. 2a shows a press arrangement that works according to the conventional system, and FIG. 2b shows a press arrangement that works according to an exemplary embodiment of the invention Drawing stamp shown at 50. It follows from this comparison that with two presses of the same size, one of which works according to one embodiment of the invention (2b) and the other according to conventional methods (2a), with the press working according to one embodiment of the invention with the same dimension Z larger parts can be pulled.

Claims (18)

1. A press, in particular for drawing and deep- drawing operations, with a tool part designed as a ram (1), a tool part designed as a punch (2) and a sheet or blank holder (5) for holding the sheet- metal component to be formed, a plurality of pressure-adjustable intermediate members (7; 15; 20; 24 to 26) being distributed across the surface of the sheet or blank holder between its lower section (55) remote from the tool part to be held and the press frame (11) or bed (6) to support the sheet or blank holder, and with a retaining block (10) against which the ram (1) can rest securely during the pressing process, characterised in that the sheet or blank holder (5) is a solid body against the lower section (55) of which the separate resilient intermediate members (7; 15; 20; 24 to 26) rest with a supporting face, and in that the supporting forces exerted on the sheet or blank holder (5) by each individual intermediate member (7; 15; 20; 24 to 26) are independently adjustable.

2. A press according to Claim 1, characterised in that the intermediate members (7; 15; 20; 24 to 26) are in themselves resilient, their resilience or spring force being variable, measurable and adjustable.

3. A press according to Claim 1 or 2, characterised in that the intermediate members (7; 15; 20; 24 to 26) are pre-loaded against the sheet or blank holder (5) by mechanical adjusting elements such as spindles or wedges, or by fluidic, in particular hydraulic, adjusting elements.

4. A press according to any of Claims 1 to 3, characterised in that the intermediate members (7; 15; 20; 24 to 26) are mounted in the lower section (55) of the sheet or blank holder (5) adjacent to the press frame (11) or bed (6).

5. A press according to any of Claims 1 to 3, characterised in that the intermediate members (7; 15; 20; 24 to 26) are mounted in that side of the press frame (11) or bed (6) which is adjacent to the sheet or blank holder (5).

6. A press according to Claim 4 or 5, characterised in that the intermediate members (7; 15; 20; 24 to 26) are installed in bores in the associated carrier, the lower section (55) or the press frame (11) or bed (6).

7. A press according to Claim 4 or 5, characterised in that the intermediate members (7; 15; 20; 24 to 26) are movably installed on the associated carrier, the lower section (55) or the

press frame (11) or bed (6).

8. A press according to any of Claims 1 to 7, characterised in that resilient spring elements are arranged between each intermediate member (7; 15; 20; 24 to 26) and the adjacent lower section (55) of the sheet or blank holder (5) or the press frame (11) or bed (6).

9. A press according to any of Claims 1 to 8, characterised in that the pressure of the supporting force of the intermediate members (7; 15; 20; 24 to 26) is adjusted directly or indirectly in dependence of the press stroke by means of hydraulic or mechanical elements, for instance by re-setting at each stroke, or independently of the press stroke directly or indirectly by means of hydraulic or mechanical elements, the pressure adjustment of individual intermediate members (7; 15; 20; 24 to 26) or of groups thereof being suitably governed by a programme for adjustment or variation, for instance infinite variation.

10. A press according to any of Claims 1 to 9, characterised in that the ram (1) is designed to hold the pressure constant by means of a small pressure maintenance pump.

11. A press according to any of Claims 1 to 10, characterised in that the intermediate members (7; 15; 20; 24 to 26) are connected to the pressure source by way of a pressure adjusting valve set or a metering and indicating manifold block.

12. A press according to any of Claims 1 to 11, characterised in that the intermediate members (7) consist of a cylinder (20) and a piston (24) movable therein towards the sheet or blank holder (5) under the influence of a pressure medium, the piston being connected to a pressure plate (26) by a pin (25) or the like, a block (28) consisting of a stack of disks (27) of an elastic material being interposed between the pressure plate (26) and the piston (24).

13. A press according to Claim 12, characterised in that the pressure plate (26) is guided in the end section of the cylinder (20) adjacent to the sheet or blank holder (5) to move with the piston (24) and is connected thereto by means of a centring device (25) with the interposition of the block (28) of stacked disks (27) of an elastic material, allowing for a slight relative movement between the pressure plate (26) and the piston (24), a feed line (29) for the pressure medium terminating in the end section of the cylinder (20) remote from the sheet or blank holder (5).

14. A press according to Claim 12 or 13, characterised in that the lower section of the cylinder (20) either sits in a cylindrical bore in the upper part of the press frame (11) or bed (6), the feed line for the pressure medium being represented, for instance, by a bore in the press frame leading to the cylinder (29), or the lower section of the cylinder (20) sits in a slide block guided on the surface of the press frame (11) or bed (6), the flexible feed line for the pressure medium extending through the slide block and opening into the lower end section of the cylinder (29).

15. A press according to any of Claims 1 to 14, characterised in that the retaining block (10) is adjustable and lockable relative to the ram (1).

16. A press according to Claim 15, characterised in that the retaining block (10) is adjustably mounted on the press frame (11) or bed (6).

17. A press according to Claim 15 or 16, characterised in that the retaining block (10) acts in conjunction with the lower face of the ram (1) carrying the die (3).

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