DE102021118550A1 - Device for machining a workpiece - Google Patents

Abstract

In a device for machining a workpiece using an upper tool part (1) and a lower tool part (2) or a table (5, 6), which together form a machining plane in a gap (3), the width of which is controlled by a drive (9.1, 9.2 ) of the upper tool part (1) and/or the lower tool part (2) can be changed, the drive (9.3, 9.4) should be arranged below the machining level.

Description

The invention relates to a device for machining a workpiece using an upper tool part and a lower tool part or a table, which together form a machining plane in a gap whose width can be changed by driving the upper tool part and/or the lower tool part.

State of the art

A large number of machine tools which deal with the forming of workpieces are known from the prior art. These include, above all, presses of all kinds, with which a workpiece is cut out or trimmed, or with which the workpiece can also be deformed.

The main difference between presses is the type of drive. For example, there are hydraulic or pneumatic presses, as in the EP 1 252 010 are shown. Above all, however, mechanical presses are also used, such as toggle presses or eccentric presses. Such an eccentric press with connecting rod is, for example, in EP 0 941 831 shown. Such presses usually consist of several parts, such as in particular the head piece, ram, stand and table, or of a ring frame which depicts the head piece, stand and table. The movement of the ram is guided by guides on the stand, and the force is transmitted to the ram via a gear train with levers and eccentrics via connecting rods. The frame, which is made up of a head piece, stand and table, is usually clamped together using anchors.

In the classic application of a multi-stage tool, the available table length is defined by the number of stages and is usually also used. In order to form components accurately, an attempt is made to allow the table and the ram to deflect as little as possible. The deflection line is largely determined by the support spacing, since the deflection depends on the third power of the length of the support spacing.

Especially when forming microstructure plates, such as bipolar plates, very high forces are required in a very small space. The power flow of classic mechanical forming presses in the frame poses a problem.

task

It is the object of the present invention to develop a press which can be used above all in the forming of microstructured plates and here in particular in the forming of bipolar plates.

solution of the task

The task is solved by the fact that the drive is arranged below the processing level.

In a mechanical press and here in particular in an eccentric press, the eccentric drives or their gear train are no longer arranged in the head piece, but in or on the table. The connecting rods then point upwards and are attached to the tappet. Thus, no pressure acts on the ram, but rather a train. This makes it possible for the force introductions on the ram and on the table to have the same support spacing. A deflection/bending is thus symmetrical, at the same time the support distances are minimized.

The distance between the connecting rods is preferably dimensioned as small as possible, so that on the one hand a circuit board conveyor system for the microstructure plates fits through between them and on the other hand the drive mechanism is dimensioned sufficiently. However, many machine elements of the usual presses are omitted, such as in particular the head piece or the necessary anchors in the stand. The flow of forces takes place in the smallest possible space, in which very high forces can now be realized.

Furthermore, for the processing of particularly sensitive microstructure plates, there is a significant advantage in that there is now no longer a drive mechanism in the head piece above the microstructure plates, which is lubricated there with oil, which runs into the ram via partly free openings and from there onto the workpieces to be machined strikes. In the case of bipolar plates to be manufactured, for example, there must be no particles or dirt on the circuit boards. According to the present invention, however, the drive is below the processing level, so that contamination of the workpieces can be ruled out. The connecting rods themselves or their lubricated joints above the processing level can be covered using simple design measures.

character list

• 1 eine schematisch dargestellte Frontansicht einer mechanischen Presse nach dem Stand der Technik;
• 2 eine schematische Darstellung der Druck- und Kraftverhältnisse bei einer mechanischen Presse gemäss 1;
• 3 eine schematisch dargestellte Frontansicht einer erfindungsgemässen Presse mit einem Unterflurantrieb;
• 4 eine schematisch und blockschaltbildlich dargestellte Anordnung der Dimensions- und Kraftverhältnisse bei der erfindungsgemässen Presse gemäss 3.

Further advantages, features and details of the invention result from the following description of preferred exemplary embodiments and from the drawing; this shows in

• 1 a schematically illustrated front view of a mechanical press according to the prior art;
• 2 according to a schematic representation of the pressure and force conditions in a mechanical press 1 ;
• 3 a schematically illustrated front view of a press according to the invention with an underfloor drive;
• 4 a schematic and block diagram of the arrangement of the dimension and force ratios in the press according to the invention 3 .

In 1 a press P for machining a workpiece not shown in detail is shown according to the prior art. The workpiece is machined between an upper tool part 1 and a lower tool part 2 in a gap 3, the width of which changes when upper tool parts 1 and lower tool part 2 are moved together and the workpiece is thus machined. An imaginary plane through this gap 3 is referred to below as the processing plane.

The upper tool part 1 is located on a ram 4, while the lower tool part 2 is seated on a table top 5. Under the table top 5, a machine table 6 is also indicated.

The ram 4 is arranged so that it can move vertically in a machine frame 7, being connected in an articulated manner to two connecting rods 8.1 and 8.2 for the purpose of its vertical movement. Each connecting rod 8.1 and 8.2 is part of an eccentric drive 9.1 and 9.2 as an example of an underfloor drive according to the invention, with only parts of the gear trains 10.1 and 10.2 being indicated in the drawing. Eccentric drive 9.1 and 9.2 and wheel trains 10.1 and 10.2 sit in a head piece 11.

The head piece 11, the machine frame 7 and the machine table 6 are penetrated by tie rods 12.1 and 12.2 and clamped together by anchor nuts 13 acting above the head piece 11 and below the machine table 6.

With the bold solid line is in 1 shows the power flow that takes place in such a press according to the prior art. In synopsis with 2 this flow of forces is explained, with A denoting the distance between the gear trains 10.1 and 10.2 and B denoting the support distance, ie the distance between the tie rods 12.1 and 12.2. F _PN designates the power flow through the connecting rods 8.1 and 8.2, F _P the power flow of the tool upper part 1. The power flow runs via the connecting rods 8.1 and 8.2 combined to the tool upper part 1 and is transferred from this during pressing to the tool lower part 2 and from there laterally derived to the tie rods 12.1 and 12.2, which in turn are operatively connected to the gear trains 10.1 and 10.2 in relation to the flow of force.

In the classic application of a multi-stage tool, the available table length is defined by the number of stages and is usually also used. In order to form workpieces true to size, an attempt is made to allow the table top 5 and the ram 1 to deflect as little as possible. However, the deflection line is largely determined by the support distance B, since the deflection depends on the third power of the length of the support distance B.

The forming of workpieces, such as bipolar plates, requires very high forces in a very small space. In such a case, a point load should actually be assumed. In the classic mechanical forming press according to the prior art, the distance A between the two connecting rods 8.1 and 8.2 is determined by the necessary distance between the gear trains based on the torque. The support distance B then also results largely from the construction of distance A, with the support distance B always being greater than the distance A of the gear trains 10.1 and 10.2. Due to the greater support spacing B, the table 5 must be designed to be significantly stronger for the same resulting deflection. In addition, symmetrical bending is not possible due to the different support distances in the case of distributed loads.

According to the present invention according to a press P1 3 the eccentric drives 9.3 and 9.4 are now arranged in the machine table 6 with an underfloor drive, so that the connecting rods 8.3 and 8.4 point upwards and are suspended there on the ram 4. However, this means that the force application on the ram and on the table has the same support distance A. Springing/bending is therefore symmetrical, and the support distances A are minimized at the same time. The distance between the connecting rods 8.3 and 8.4 can only be dimensioned as small as possible, so that a blank conveyor system 14 fits through between the ram 4 and the machine table 6 and the drive mechanism is sufficiently dimensioned. It is also eliminated, the separate head piece 11 and the previously required tie rods 12.1 and 12.2. The flow of forces, which is also illustrated here by the thick solid line, takes place in the smallest possible space, in which very high forces can now be realized.

Reference List

1

tool top

2

tool base

3

gap

4

pestle

5

tabletop

6

machine table

7

machine frame

8th

connecting rod

9

eccentric drive

10

gear train

11

headpiece

12

tie rod

13

anchor nut

14

conveyor system

A

Distance from 10.1, 10.2

B

Distance from 12.1, 12.2

f

power flow

P

Press

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 1252010 [0003]
• EP 0941831 [0003]

Claims (6)

Device for machining a workpiece by means of an upper tool part (1) and a lower tool part (2) or a table (5, 6), which together form a machining plane in a gap (3), the width of which is determined by a drive (9.1, 9.2) of the The upper tool part (1) and/or the lower tool part (2) can be changed, characterized in that the drive (9.3, 9.4) is arranged below the working plane. device after claim 1 , characterized in that the drive is an eccentric drive (9.3, 9.4). device after claim 2 , characterized in that the eccentric drive (9.3, 9.4) has at least two gear trains (10.3, 10.4) which are connected via connecting rods (8.3, 8.4) to a ram (4) on which the tool upper part (1) is arranged. device after claim 3 , characterized in that the two connecting rods (8.3, 8.4) are arranged parallel to one another at a distance (A). Device according to at least one of the preceding claims, characterized in that the drive (9.3, 9.4) exerts a pull on the tool upper part (1). Device according to at least one of the preceding claims, characterized in that the workpiece to be machined is a microstructure plate.

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