EP0835699B1 - Hydraulic deep drawing apparatus - Google Patents

Abstract

The device is arranged so that a hold-down force for the deep drawing of a workpiece (19) is divided between an outer load area and an inner load area. The outer load area is subjected to a controlled base load by a number of hydraulic hold-down cylinders (13), which act on a tool base plate (11) that is arranged below a hold-down plate (10). The inner load area includes a number of multi-point pressure or forming pins (5,20), which act directly on the hold-down plate. The pins are energised individually or in groups by controlled short stroke hydraulic cylinders (14).

Description

The invention relates to a hydraulic deep-drawing device in presses for drawing sheet metal parts after Preamble of claim 1.

A hydraulic deep-drawing device according to the generic term of claim 1 is known from DE-OS 44 35 069. This invention was based on the task of the press together with the hydroelastic puller shape that existing without expensive customization Tools of the previous conventional deep drawing forming technology can be used with the aim that such older tools with the claim of a modern CNC-controlled, divided into fields of force Multi-point unit can be driven.

A major advantage of the invention according to DE 44 35 069 is that that tools from conventional single-acting presses without cumbersome and expensive customization for one process-guided deep drawing with CNC-controlled Multi-point force control can be used. Unsolved is the problem of the different flow behavior of the Workpiece sheets, for example in the manufacture of Double sink with different sink geometries z. B. the pool distance, the depth, the radii and the Sheet thickness and different material qualities of the Workpiece, that is, it must be in the well-known manner the critical flow front areas shredded paper under the Sheet metal plate or the drawing ring are placed. Especially this requires a lot of effort when running in new tools time expenditure and is only partially reproducible.

The invention has for its object a hydraulic To create deep-drawing device with which a reproducible Thermoforming with a wide variety of knitting parameters such as Material properties, greasing, lubrication, temperature etc. in terms of shape and quality of the workpiece is possible without a constant manual correction to Example by placing pieces of paper under it, necessary is.

This task is due to the features of Claim 1 soldered.

The solution according to the invention is particularly a reproducible drawing of the workpiece sheet without Paper shredded pad enables. A simple and reproducible pulling is achieved in that the outer Knitting ring over the tool base plate on the Sheet metal holding plate with an adjustable base load component Sheet metal holding force is applied, that is, the pressure bolts do not act on the sheet metal holding plate, but on flat surfaces Surfaces of the tool base plate. For the inner wreath on the other hand, according to the drawing ring geometry Target points or target areas individually or in groups can be controlled. This can be done by high concentration of forces in the critical areas, for example in the area of a bridge Double sink, the inflow of the board material braked and by appropriate adjustment of the force profiles in the hydraulic short stroke cylinders along the Drawing ring contour can be controlled.

An advantage with the invention The multi-point system is thus the separation of the sheet metal holding function in two different functional levels. A hydraulic circuit acts as a basic load (outer effective ring) on the Tool base plate that is below the actual one Sheet metal holding plate is arranged, this base load itself in an adjustable, even sheet metal holding force complete sheet metal impact. In addition to this functional level different short-stroke cylinders combined in groups act (inner knitting ring) close to the drawing ring radius the sheet metal holding plate. These short stroke cylinders precisely control the flow of the Material in the critical areas near the forming zone.

For this purpose, the short-stroke pistons of the short-stroke cylinders are advantageously included a large effective area equipped with pressure bolts Optimal effective points, fixed on the active surface of the short-stroke pistons to reach. The multipoint unit is convenient designed for making parts of a Workpiece family, it can be used in whole or in part for the Be adaptable to other families of workpiece parts, using the existing electrical and hydraulic Control and regulating devices of the press. The order A separate multi-point unit ensures reproducible Transfer of the desired sheet metal holding force by the Ram reached a distance of Δs from the workpiece. This Locking the plunger thus also secures when it is introduced large eccentric load reproducible operating conditions without tipping. The ram is eccentric Load moment only slightly affected. In particular, the Sheet metal holding force distribution not during the drawing process changed by tilting the ram.

This stage of development of the multi-point control system according to the invention consisting of a hydraulic press, one Multi-point unit for the sheet metal holder function and flexible Forming elements as drawing punch drives offer the possibility a reproducible thermoforming process for difficult Parts. Based on the principle of separating the Sheet holding function from the ram function, one to the Multi-point unit and forming elements adapted to the part geometry, which can be positioned so that a centric Force application is improved Process stability achieved. The introduction of a Press control via computer ensures simple Handling the complex parameter settings. The consequence are reduced setting times, minimized Material consumption as well as a reduction in Rejection rate. Especially the application in the field of Forming stainless steel kitchen sinks confirms that Improvement in process control.

Further features and advantages of the invention result from the dependent claims and from the description of a Exemplary embodiment with reference to the drawing.

Figur 1

die Presse mit der erfindungsgemäßen Tiefzieheinrichtung im Aufriß,

Figur 2

die Vielpunkteinheit mit Ziehwerkzeug aus Figur 1 in größerem Maßstab,

Figur 3a

die Vielpunkt-Kontrolleinheit nach Figur 1 und Schnitt A-A aus Figur 3b,

Figur 3b

die Anordnung der Kurzhubzylinder für den äußeren und inneren Wirkkranz im Grundriß für ein Teil mit rechteckiger Kontur,

Figur 4a

die Ausbildung eines runden Druckbolzens in mittiger Anordnung auf der Wirkfläche der Kurzhubkolben im Grundriß,

Figur 4b

die Ausbildung eines rechteckigen Druckbolzens in mittiger Anordnung auf der Wirkfläche der Kurzhubkolben im Grundriß,

Figur 4c

die Ausbildung eines runden Druckbolzens in außermittiger Anordnung auf der Wirkfläche der Kurzhubkolben im Grundriß,

Figur 4d

die Ausbildung eines rechteckigen Druckbolzens in außermittiger Anordnung auf der Wirkfläche der Kurzhubkolben im Grundriß,

Figur 5a

die Ausbildung einer Vielpunkteinheit mit nebeneinander angeordneten, auswechselbaren Modulstreifen,

Figur 5b

eine weitere Ausbildung einer Vielpunkteinheit mit beliebig angeordneten Modulstreifen auf einer gemeinsamen Trägerplatte,

Figur 5c

eine andere Ausbildung einer Vielpunkteinheit mit unterschiedlichen Modulstreifenausführungen, beliebig angeordnet auf einer gemeinsamen Trägerplatte,

Figur 6a

Druckprofile während des Ziehweges,

Figur 6b

die Bildschirmdarstellung der Parameter,

Figur 7a

die Werkzeuggrundplatte mit eingesteckten Druckbolzen und der Kurzhubkolbenposition für den inneren Wirkkranz für eine Doppelbeckenspüle,

Figur 7b

die Werkzeuggrundplatte mit eingesteckten Druckbolzen und der Kurzhubkolbenposition für den inneren Wirkkranz für eine Einbeckenspüle,

Figur 8a

in perspektivischer Darstellung die Anordnung der Umformzylinder in der Tischplatte,

Figur 8b

den verschiebbaren Umformzylinder mit Umformkolben in der Führung der Tischplatte im Grundriß und

Figur 8c

nach Figur 8b die Anordnung zweier Umformzylinder mit Umformkolben in der Tischplatte.

Show it:

Figure 1

the press with the deep-drawing device according to the invention in elevation,

Figure 2

the multipoint unit with drawing tool from Figure 1 on a larger scale,

Figure 3a

the multi-point control unit according to FIG. 1 and section AA from FIG. 3b,

Figure 3b

the arrangement of the short-stroke cylinders for the outer and inner knitting ring in the plan for a part with a rectangular contour,

Figure 4a

the formation of a round pressure pin in a central arrangement on the active surface of the short-stroke piston in the plan,

Figure 4b

the formation of a rectangular pressure pin in a central arrangement on the active surface of the short-stroke piston in the plan,

Figure 4c

the formation of a round pressure pin in an eccentric arrangement on the active surface of the short-stroke piston in the plan,

Figure 4d

the formation of a rectangular pressure bolt in an eccentric arrangement on the active surface of the short-stroke piston in the plan,

Figure 5a

the formation of a multi-point unit with interchangeable, interchangeable module strips,

Figure 5b

a further embodiment of a multi-point unit with arbitrarily arranged module strips on a common carrier plate,

Figure 5c

another design of a multi-point unit with different module strip designs, arranged arbitrarily on a common carrier plate,

Figure 6a

Pressure profiles during the drawing path,

Figure 6b

the screen display of the parameters,

Figure 7a

the tool base plate with inserted pressure bolts and the short-stroke piston position for the inner working ring for a double basin sink,

Figure 7b

the tool base plate with inserted pressure bolts and the short-stroke piston position for the inner working ring for a single sink,

Figure 8a

the arrangement of the forming cylinders in the table top in a perspective representation,

Figure 8b

the sliding forming cylinder with forming piston in the guide of the table top in plan and

Figure 8c

8b shows the arrangement of two forming cylinders with forming pistons in the table top.

The drawing shows one in FIG Deep-drawing device in a press 1 in the closed Working position before the deep-drawing process, without workpiece 19. The press 1 assumes the function of a guard locking or Tool clamping device. That is, the locking cylinder 2 have the function of the dead weight of ram 3 and Intermediate plate 4 and 8 drawing ring vertically in the course of a Hydraulic opening or closing movement. In closed position are the spacers 21, the forming forces occurring during the deep drawing forming process and Sheet holder forces (process forces), recorded statically. If necessary, instead of in the lower closed position the spacers 21 is a hydraulically controlled mechanical locking unit can be used so that the forces occurring between the lower table construction of the press frame 7 and the ram 3 are collected.

The drawing tool and the multi-point unit 12 are shown in FIG shown larger in detail. The lower half of the tool consists of the elements punch 9, Sheet metal holding plate 10, the tool base plate 11, the Push pin 5 and form pin 20. The multi-point unit 12 includes the short stroke cylinders 13 with the short-stroke pistons 14. With the The intermediate plate 4 is the drawing ring 8 as in one conventional version firmly connected and with the ram 3 can be raised and lowered.

The short-stroke pistons 14 of the exchangeable multi-point unit 12 are designed to be more similar for a product family Parts but with different dimensions can be used. The relationship is most important for implementation between product shape (for example, rectangular shape of the Drawing ring 8) and the cylinder positions to the material flow in the areas of pressure and tension areas in the the most efficient way to control. Compared to the concepts of conventional simple and The short-stroke cylinder principle also has double-acting presses an installed stroke of just a few millimeters Advantage of more flexibility with regard to placement of the Actuators relative to the workpiece geometry. That is achieved in combination with an improved dynamic behavior of the hydraulic system, and realizes the possibility the programming of complex sheet metal holding force profiles, which exactly meet the requirement for each stage of the drawing process are necessary.

The holding force of the short-stroke cylinder 13 is in an outer Knitted ring 25 and an inner ring 26, where the outer knitting ring 25 with an adjustable, constant base load with the pressure bolts 6 the tool base plate 11 acts while the action points of the inner knitting ring 26 via the pressure pin 5 and form pin 20 through appropriately shaped openings in the Tool base plate 11 act on the sheet metal holding plate 10 and specifically regulated individually or in groups are acted upon. Figures 3a and 3b are knitted rings 25 and 26, delimited from one another by the dividing line 30 (thickly dashed), clearly shown. In the narrow Grid enclose the short-stroke cylinders 13 with the Short stroke piston 14, the drawing ring contour 18 according to the pulling workpiece. The table top 15 (see also FIG. 8a and 8b) mainly has in the middle of the clamping surface Cutouts with guides 24 for the housing 23 of the Forming cylinder / piston 16/17. Depending on the geometry of the Drawing punches 9 can be correspondingly many hydraulic Forming piston 17 may be provided. This arrangement of movable cylinder units as Pull drives, placed in the lower crosshead of the press, takes over the pulling function for parts with different Geometries. By separating the drag function from the Multi-point unit 12 can easily press 1 to different Product groups are adjusted by the multi-point unit 12 replaced and the positions of the forming cylinder / piston 16/17 can be adjusted.

The functional sequence of a deep-drawing process is as follows: When the press 1 is open, the flat workpiece 19 is placed on the Sheet metal holding plate 10 and the lowered punch 9 placed. The plunger 3 is then turned on in a rapid closing movement Guide rails 22 hydraulically or mechanically except for one small gap, Δs, from about 0.5 mm to 5 mm just above the Workpiece 19 lowered. The plunger 3 is either supported by spacers 21, the set Ram force is above the total process force 3 got to. Alternatively, the ram can be fixed using a mechanical / hydraulic locking unit. In Figure 1, the gap distance s is drawn, the same the sheet thickness of the workpiece 19 plus the gap Δs. By locking the plunger 3 with a gap distance Δs to the workpiece 19 also results in the very fast Closing movement no dynamic impact on the Workpiece 19. Elaborate pre-acceleration procedures Conventional die cushion plates are hereby omitted. After Fixing or locking the plunger 3 are the Short stroke 13 and short stroke piston 14 hydraulic activated. The sheet metal holding plate 10 is made according to the Gap distance Δs hydraulically increased so that the workpiece 19 is pressed against the drawing ring 8. Is the gap Δs hydraulically bridged and the setpoints of the Short stroke 13 or cylinder groups reached begins immediately the punch movement for the drawing stroke. During the Deep-drawing stroke, the pressures in the short-stroke cylinders 13th or groups of cylinders according to the different Material flow in the area of tension and compression (for example in the pressure forming area material thickening by concentric confluence of the material and Material thickening in the frame flange) by a Computer control changed. The pressure bolts 5 and form bolts 20 corresponding to the respective tensile and compression areas are along the drawing ring contour 18 of the Sink geometry arranged.

As can be seen from FIGS. 3 and 4, the Short-stroke piston 14 equipped with such a large effective area, that the pressure pin 5 or the form pin 20 in the Tool base plate 11 also eccentrically according to the Drawing ring geometry 18 or drawing die contour on the Active surfaces of the short-stroke piston 14 in the short-stroke cylinder 13 can be arranged. For that, of course, the Tool base plate 11 according to the shape of the pressure bolts 5 and molded bolts 20 are made. The shaped bolts 20 the workpiece shape or the drawing ring contour 18 be adjusted accordingly. Figures 5a, 5b and 5c as well 7a and 7b show the possibility as through different application of the pressure pin 5 and form pin 20 on the active surfaces of the short-stroke cylinder 13 Adaptation to similar workpieces from a family of parts is guaranteed, the multi-point unit 12 of several Interchangeable module strips 27 can be assembled can and therefore for the production of different Workpieces 19 with different dimensions is useful. The Figures 5a, 5b and 5c each show in elevation and side elevation the construction of a tool base plate 11 by interchangeable module strips 27 or by interchangeable modules 28 and 28 ', the corresponding of a workpiece 19 of a subfamily on the carrier plate 29 are fixable.

FIG. 6a shows the pressure profiles during the drawing path, while Figure 6b shows how by entering Tool parameters in a calculator and programmable Representation on the workpiece families can be displayed and are developable.

In FIG. 6b, the starting values in KN when pulling a double sink with different large basins are shown on the monitor as an example. The following states can also be displayed in the field at the bottom left: Ram down rapid traverse Multipoint start value reached Pull path reached Ram at a distance Forming element c active discharge Ram pressure reached Forming elements A / B active Ram rapid traverse upwards

Claims (7)

1. A hydraulic deep drawing device in presses for drawing sheet metal parts having a sheet holding plate (10) supported with respect to hydraulic short stroke pressure cylinders (13) which set the holding force for deep drawing the workpiece (19), and drawing punches (9) which are movably guided by hydraulic forming cylinders (16) in the drawing direction, a drawing ring (8) disposed above the sheet holding plate (10), a tool base plate (11) disposed below the sheet holding plate (10), and a multipoint unit (12) with a plurality of short stroke cylinders (13) in multipoint drive according to the drawing ring contour (18) and a ram (3) guided in a press frame (7), with the ram (3) moving downward until shortly before contact with the workpiece (19) and being able to be fixed positively or nonpositively to the press frame (7) at a gap spacing Δs from the workpiece (19), whereupon the hydraulically activated short stroke cylinders (13) bridge the gap spacing Δs and, by means of the sheet holding plate (10), press the workpiece (19) against the drawing ring (8), wherein the short stroke cylinders (13) of the multipoint unit are split into an outer effect ring (25) and an inner effect ring (26), with the tool base plate (11) being loaded hydraulically by the short stroke cylinders (13) of the outer effect ring (25) with an adjustable basic load via the short stroke pistons by means of pressure pins (6), whereas the short stroke cylinders (13) of the inner effect ring (26) act upon the sheet holding plate (10) directly above the short stroke piston (14) by means of pressure/shaping pins (5; 20) in effective points and each individually or in groups in a purposefully controlled manner.
2. A hydraulic deep drawing device as claimed in claim 1, wherein the pressure/shaping pins (5 or 20) of the inner effect ring (26) can be fixed in a centric or eccentric manner on the effective surface of the short stroke piston which is arranged in a sufficiently large manner.
3. A hydraulic deep drawing device as claimed in claim 2, wherein an adaptation to similar workpieces (19) of a family of parts is possible by means of different arrangements of the pressure/shaping pins (5 or 20) on the effective surfaces of the short stroke pistons (14).
4. A hydraulic deep drawing device as claimed in the claims 1 to 3, wherein the multipoint unit (12) consists of two or more change modules (27, 28 or 28') and is suitable for the production of different workpieces by means of variable composition.
5. A hydraulic deep drawing device as claimed in the claims 1 to 4, wherein one or more shaping cylinders (16) with their housing (23) are arranged displaceably and interchangeably as a unit in guide means (24) of the table plate (15).
6. A hydraulic deep drawing device as claimed in the claims 1 to 5, wherein the pressure/shaping pins (5; 20) for the inner effect ring (26) are constructed or shaped to correspond to the associated drawing ring contour (18).
7. A hydraulic deep drawing device as claimed in claim 1, wherein a press control unit with entry of the tool parameters occurring during the drawing process into a computer for setting programmable force profiles in the hydraulic short stroke cylinders (13) along the drawing ring contour (18) of the inner effect ring (26) and for visual representation of the tool parameters during the sheet holding and shaping operation on a monitor and the storage of tool-specific data records in said computer.

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