Drawing press with stable metal sheet holder

Abstract

The drawing press according to the invention includes a support structure for supporting a metal sheet holder which is part of a tool and supported on the press frame via the support structure. The metal sheet holder is assigned a plunger with a die tool, whereas the plunger is moved by means of a plunger drive which includes a blocking position. The blocking position is obtained, for example, by a drive which, in the locking position does not transmit any movement of the drive output to the driving servomotor. This can be achieved, for example, by an eccentric drive in the stretched position thereof. For performing the actual drawing stroke, the stamping tool is vertically movably supported. A carriage is raised or lowered by the press table by means of a table drive. As table drive, preferably a servomotor with a non-linear drive, such as an eccentric drive is used.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This is a continuation-in-part application of pending international application PCT / EP2011 / 064043 filed Aug. 15, 2011 and claiming the priority of German Application No. 10 2010 034 518.0 filed Aug. 15, 2010 and the priority of German Application No. 10 2010 037 950.6-14 filed Oct. 4, 2010.BACKGROUND OF THE INVENTION[0002]The invention resides in a drawing press which is suitable in particular for integration into press working lines, hybrid press set ups or transfer presses for the manufacture automobile body parts.[0003]In the manufacture of automobile body parts or other large area spatially formed metal sheets the first press stage is generally a drawing press which gives an initially planar plate a spatial shape. This is done in a drawing press in which the rim of the metal sheet is clamped in position or which permits the rim to slide toward the plate center in a controlled manner, while the part of metal sheet surrounded by the shee...

AI Technical Summary

Benefits of technology

[0011]This substantially reduces the power required for driving the plunger and for driving the table. The power required just for moving the plunger is small. In addition to the energy required for the dynamic acceleration and deceleration of the plunger and the die before the begin of a drawing stroke, when the die tool has come into contact with the metal sheet, only the build up of the holding force is necessary which is then maintained stable via the press frame. Alternatively, the metal sheet retaining force may also be provided by a short-stroke metal sheet holder drive. Also, the metal sheet holder drive may have a blocking position. It may, for example, be in the form of a short stroke eccentric drive or a cam drive which clamps the metal sheet holder into engagement with the die tool and which transmits the clamping forces directly into the press frame. In this case, a blocking position is reached when the eccentric drive is in the stretched position or, in connection with a cam drive; the cam is engaged at the maximum radius area thereof. The movement of the servomotor driving the die results in no or only a negligible metal sheet holder movement.

[0013]The press concept presented herewith minimizes the energy required for the plunger drive and for the table drive and also the power exchange between the two drives. The press, according to the invention, requires therefore in comparison with presses which have an intensive energy exchange between the plunger drive and the drawing cushion, small drives for the same capacity.

[0015]The press concept presented herewith permits the continued use of existing tool sets which had been provided for operation with a stationary die and a metal sheet holder that is moved downwardly during the drawing procedure. Also, the conventional transfer arrangements may be used without essential adaptation changes. With the drawing press according to the invention the linearly movable table may have a group of passages through which support elements extend. These support elements, for example, in the forms of straight bolts, extend through these passages and support the metal sheet holder at a support area. The support area is preferably arranged fixed with respect to the press frame. This means that the position of the metal sheet holder with respect to the press frame is firmly fixed or fixed by an adjustment arrangement. When the metal sheet disposed on the metal sheet holder is biased by the die against the metal sheet holder and plunger drive is in a blocking position (that is for example the drive has reached its stretched position), the metal sheet retaining force is determined by the elasticity of the press frame. This elasticity may be in the range of a few millimeters to a few 10 millimeters. The energy elastically stored in the press frame can be returned to the plunger drive during the return stroke of the plunger which further reduces the overall energy consumption of the drawing press.

Problems solved by technology

Since it has been recognized that with this concept at the drawing cushion a large amount of energy is used and generally lost which energy has to be provided by the plunger.

However, during the energy recuperation energy losses are unavoidable.

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