EP2114587B1 - Forming press with a drawing cushion function integrated into the sliding table - Google Patents

Abstract

The invention relates to a forming press in which the drawing cushion functions (3) or parts thereof, such as, for example, the drives (5) and the displacement and force transmission means, are integrated into one or more sliding tables (1)

Description

The invention relates to a forming press according to the preamble of claims 1 and 2, wherein the die cushion functionalities or parts thereof are integrated into one or more sliding tables.

State of the art

Cushions are used to hold down during deep drawing in presses. This prevents wrinkling or cracking and, thanks to the simultaneous ejector function, raises the parts to the transport level at the ram return. The workpiece is clamped between a special plate holder and the descending upper tool. In this case, the force applied by the plunger during the decline force must counteract a counter force on a controlled reproducing device. In conventional die cushion, the counterforce is applied to the blank holder by an underlying pressure cheek. The structure of such a die cushion is in the " Handbuch der Umformtechnik page 46, Schuler 1996 In the generic EP 0 417 754 B1 a die cushion device is disclosed in which upon impact of the upper tool on the blank holder of the impact and the resulting impact noise by pre-acceleration of the Drawing cushion masses can be reduced and subsequently a hydraulic clamping of the sheet metal holder can take place.

Characteristic of all hydraulically and pneumatically actuated die cushion is the very high control and regulatory effort to achieve the desired displacement and force functions.

Recently, die cushions have become known in which these travel and force functions are generated by NC-controlled electric drives. The also generic EP 1 082 185 B1 discloses a deep drawing press with driven by threaded spindle and spindle nut press ram and die cushion. The movement of the die cushion is achieved in this embodiment exclusively by electronic drives, which are connected via spindle nut and threaded spindle with the pressure cheek.

Both the hydraulic and pneumatic, as well as the NC-controlled electrically driven die cushion as described in the prior art, are arranged in the region of the press table. That means for the regulation of the blank holder force, that this must be readjusted for each new tool. Due to the arrangement of the die cushion in the table, it is usually not possible to retrofit existing presses without die cushion with such. As a rule, the installation spaces in an existing press table are unsuitable for the installation of a die cushion.

Recent developments aim to shift the die cushion functionality into the tool. These tools could be used in conjunction with a so-called segment elastic blank holder which is constructed in a truncated pyramid-like ribbing. In Each truncated pyramid can be introduced via respectively assigned hydraulic cylinders and proportional or servo valves predetermined holding down forces. This results in an integrated into the drawing tool multi-point pulling device. Thus, the surface pressure between the sheet metal and sheet holder can be adjusted in a particular sheet holder surface element, without the neighboring segments are thereby significantly affected. ( Prof. Siegert, "Recent Developments in Sheet Metal Forming", 2004 ). A disadvantage of this embodiment, in addition to the limited space above all, the high tooling costs.

Task and advantage of the invention

The invention has for its object to develop a die cushion for a forming press, which is compact and inexpensive in construction and which can be retrofitted for existing presses.

This object is achieved on the basis of a forming press according to the preambles of claims 1 and 2 by the characterizing features of claims 1 and 2. In the dependent claims advantageous and expedient developments of the transport device according to the invention are given.

The invention is based on the idea to develop a forming press, in which the die cushion functionalities are fully or partially integrated into a sliding table. The integration of the die cushion in the sliding table has the advantage that existing forming presses, which hitherto have no die cushion, can be retrofitted. At the same time, this sliding table cushion has a cushioning functionality with respect to tools described in the prior art significant cost advantage. This cost advantage is due to the fact that not for each tool the corresponding die cushion components must be provided, but only for one or two sliding tables. In an advantageous embodiment, two sliding tables are equipped with the drawing devices according to the invention in a forming system. This embodiment variant has the advantage that preparatory measures and adjustments can already be carried out before a tool change on the sliding table remaining outside the press with the die cushion according to the invention. As a result, the tool change can be performed very quickly and the production can be resumed quickly with the new tools.

In principle, all known drive types, such as, for example, hydraulically or pneumatically actuated cylinders, NC electric drives or linear motors, come into question as drives for the die cushion according to the invention.

A further embodiment of the die cushion device according to the invention is that partial functions of the die cushion are arranged both in the sliding table and in the press table. So it is conceivable, for example, that the force functions that are effective during the drawing process in the sliding table, and the path functions that are effective outside of the drawing process are housed in the press table.

A further advantageous embodiment of the die cushion according to the invention is that the pressure bolts, which are moved by the above-mentioned die cushion drives, directly act on a segment elastic sheet metal holder. The use of a conventional plate holder is also possible. Further details and advantages of the invention will become apparent from the following descriptions of the illustrated embodiments.

Figur 1

Schiebetisch einer Umformpresse mit integriertem Ziehkissen

Figur 2

Schiebetisch und Tisch einer Umformpresse mit Ziehkissen

Show it:

FIG. 1

Sliding table of a forming press with integrated die cushion

FIG. 2

Sliding table and table of a forming press with die cushion

Description of a first embodiment

FIG. 1 shows a mobile sliding table 1 and a press table 2 of a forming press not shown here. In the illustrated position, the sliding table 1 is moved into the forming press and lowered onto the press table 2. In the interior of the sliding table 1 is a die cushion 3. This die cushion 3 is fully integrated into the sliding table 1 and is also in a tool change together with the sliding table 1 out of the forming press, or driven into the forming press.

In this embodiment, an embodiment is shown in which hydraulic components in the die cushion be used. As already described above, however, all types of drive known in the prior art are possible. During the forming process, the sheet holding force is applied by the cylinders 5 with the piston 6, which are located within the sliding table 4. The Kolbestangen 7 protrude on the bottom of the sliding table 4 out. At their free ends, the path of the piston rods 7 is limited by a connecting plate 8. The piston rods 7 and the connecting plate 8 are not fixed to each other, there is only one contact. The connecting plate 8 forms, as it were, a stop for the piston rods 7. The force and motion transmission of the piston 6 on the sheet holder, not shown here via the pressure pin. 9

The connecting plate 8 is connected at its outer ends in each case with a piston rod 10 and a piston 11 of a cylinder 12.

In the illustrated position, the pressure pins 9 are retracted into the sliding table plate 4. The pressure pins 9 were displaced during the forming process by the movement of the plunger and the sheet holder down and are now in their lowest position. The force which is applied by the die cushion 3 during the forming process can be regulated via the cylinders 5, which in this case are designed as double-acting cylinders. In this case, each cylinder individually, as well as several cylinders can be controlled in combination. If several cylinders are controlled together, the cylinder chambers can be interconnected. The oil is supplied via horizontal holes 13.

After the forming process, the die cushion 3 must be moved upwards again. For this purpose, piston 11 of the cylinder 12 is pressurized, so that the piston rods 10 are moved together with the connecting plate 8 upwards. The piston rods 7 of the cylinder 5 are taken from the connecting plate 8 in its upward movement. This ensures a synchronization of the piston rods 7 and causes the pressure pin 9 extend upward from the sliding table plate 4 and move the blank holder in its upper position. During the forming process, the connecting plate 8 leads in its downward movement ahead of the lower ends of the piston rods 7, so that no contact between the piston rods 7 and the connecting plate 8 is formed and a regulation of the blank holder forces by the cylinder 5 is possible.

The arrangement of the cylinders 12 and 5 is variable and adaptable to the given requirements.

As a variant of this embodiment, it is conceivable that the cylinders 5 are designed as single-acting cylinders. The connecting plate 8 would then penetrated in the downward movement of the piston 6 of the piston rods 7 and taken in the upward movement by a stop at the end of the piston rods 7 upwards. The cylinders 12 would then build up a back pressure in the upward movement of the cylinder 5 to ensure synchronization.

This embodiment has the advantage that not all pressure pin 9 must be plugged because the cylinder 5 are designed to be single acting.

In forming presses, which are equipped with a sliding table with a low height and thus not enough space for an integrated die cushion is available, it is possible to make the sliding table with a higher height and then make this in the press table to the appropriate height automatically retractable.

Description of a second embodiment

In FIG. 2 is another way to integrate die cushion functions into the sliding table. In this embodiment, not all die cushion functionalities, but only subfunctions are integrated into the sliding table 1.

The cylinder 5 with the piston 6 and the piston rods 7 are constructed in their structure and in their function the same as described in the first embodiment. They serve the controlled introduction of force into the blank holder during the forming process.

However, the connecting plate 8 is connected to a cylinder 8, which is located in the press table 2. The connecting plate 8 is thus no longer part of the sliding table 1, but of the press table 2 and thus remains even with a tool change and extending sliding table 1 in the forming press. The cylinder 14 performs substantially the same tasks as the cylinder 12 in the first embodiment. Instead of a central cylinder 14, a plurality of cylinders can also be used to move the connecting plate 8 and thus the die cushion 3.

The invention is not limited to the described and illustrated embodiments. It also includes all expert embodiments within the scope of the inventive idea.

For example, instead of the hydraulic cylinder described in the embodiments, other from the prior Technically known drive types are used, such as electric spindle drives, linear motors or drives via pivoting lever mechanisms. Likewise, combinations of different drives are possible.

In a further advantageous embodiment, the cylinder 5 can be designed so that the pressure pin 9 can not only be inserted centrally into the cylinder 5, but at different slots on the cylinder surface.

LIST OF REFERENCE NUMBERS

1

sliding table

2

press table

3

cushion

4

Sliding table

5

cylinder

6

piston

7

piston rod

8th

connecting plate

9

pushpin

10

piston rod

11

piston

12

cylinder

13

drilling

14

cylinder

Claims (15)

1. Press, press working line, multi-ram press or the like with at least one drawing cushion device to control the plate holding force between the tool lower part and the tool upper part, and with at least one moveable sliding table, which, during a tool change, can be moved out of the press or moved into the press, characterised in that the drawing cushion device (3) with its drives (5, 12) and its movement and force transmission means is integrated in the moveable sliding table (1) and, together with the sliding table (1), can be moved out of the press and moved into the press.
2. Press, press working line, multi-ram press or the like with at least one drawing cushion device to control the plate holding force between the tool lower part and the tool upper part, and with at least one moveable sliding table, which, during a tool change, can be moved out of the press or moved into the press, characterised in that the drives (5) and the movement and force transmission means, which produce a plate holding force during the forming process, are integrated in the moveable sliding table (1) and, together with the sliding table (1), can be moved out of the press and moved into the press.
3. Press according to claim 1 and/or 2, characterised in that the drives (5) are integrated in the sliding table plate (4) and wherein in particular the drives (5) are configured as double-acting or single-acting hydraulic cylinders or wherein in particular the drives (5) are configured as electric spindle drives.
4. Press according to any one or more of claims 1 to 3, characterised in that the drives (5) are configured from a combination of hydraulic drives or electric drives and a lever mechanism.
5. Press according to any one or more of claims 1 to 4, characterised in that the plate holding force, which acts from the drawing cushion device (3) on the plate holder, is transmitted by insertable pressure bolts (9).
6. Press according to any one or more of claims 1 to 5, characterised in that a driven connecting plate (8) is provided as a stop or entrainment device for the piston rod (7) to produce a synchronisation of all the drives (5) during the upward movement of the drawing cushion device (3).
7. Press according to any one of claims 1 to 6, characterised in that one or more drives (12) are integrated in the sliding table plate (4) to move the connecting plate (8) or in that one or more drives (14) are preferably integrated in the press table (2) to move the connecting plate (8).
8. Press according to any one or more of claims 1 to 7, characterised in that the drives (14) are configured as double-acting or single-acting hydraulic cylinders.
9. Press according to any one or more of claims 1 to 8, characterised in that the drives (14) are configured as electric spindle drives.
10. Press according to any one or more of claims 1 to 9, characterised in that the drives (14) are configured from a combination of hydraulic drives or electric drives and a lever mechanism.
11. Press according to any one or more of claims 1 to 10, characterised in that the cylinders (5) are supplied with hydraulic fluid via bores (13) in the sliding table plate (4).
12. Press according to any one or more of claims 1 to 11, characterised in that the drives (5) are controlled individually, independently of the other drives.
13. Press according to any one or more of claims 1 to 12, characterised in that a plurality of the drives (5) are combined to form a control unit.
14. Press according to any one or more of claims 1 to 13, characterised in that the pressure bolts (9) can be inserted at a plurality of insertion places on the upper side of the cylinder to transmit the plate holding force.
15. Press according to any one or more of claims 1 to 14, characterised in that the sliding table (1) can be automatically lowered into the press table (2) after it has been moved into the tool space.

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