Drawing press with dynamically optimized blank holding

Patent metadata

Field	Value
Publication number	US-9713832-B2
Application number	US-201113866107-A
Country	US
Kind code	B2
Filing date	Oct 14, 2011
Priority date	Oct 21, 2010
Publication date	Jul 25, 2017
Grant date	Jul 25, 2017

Abstract

The drawing press ( 10 ) according to the invention has for driving its ram ( 15 ) a directionally reversing gear mechanism ( 22, 54 ), for example a coupling gear mechanism, and at least one servomotor ( 23 ). The servomotor ( 23 ) passes through the reversal point (Ut) of the ram movement, which is predetermined by the kinematics of the coupling gear mechanism, for example the extended position of an eccentric drive. During the closing of the die ( 18 ), that is to say during a press stroke, the servomotor ( 23 ) is activated in such a way that it first passes through this reversal point (Ut), then stops, reverses and then passes through it once again, in order to open the die ( 18 ) again. Consequently, the braking to a standstill and re-acceleration of the servomotor for the upper ram ( 15 ) takes place while the actual drawing operation is still or already being performed, i.e. during the forming of the metal blank, which significantly reduces the cycle time.

First claim

I claim:

1. Drawing press ( 10 ) comprising:
a press frame,
a ram ( 15 ) provided for accommodating a matrix tool ( 18 ) for deforming a blank ( 20 ), said ram ( 15 ) being supported in a manner so as to be adjustable in an adjustment direction ( 16 ), the matrix tool ( 18 ) comprising a rim ( 19 ) for contacting a rim of the blank ( 20 ) and a lower contour into which the blank ( 20 ) is to be deformed,
a blank holder ( 35 ) opposite the ram ( 15 ), said bank holder abutting against an abutment ( 47 ) and configured to cooperate with the rim ( 19 ) of the matrix tool ( 18 ) to clamp the rim of the blank;
a ram drive ( 22 ) comprising at least one servomotor ( 23 ) connected to the ram via a coupling gear mechanism ( 25 ) or a cam mechanism ( 54 ), said coupling gear mechanism or cam mechanism having a reversal point (U t ) corresponding to a lower dead center position of said ram ( 15 ) resulting in the rim ( 19 ) of the matrix tool ( 18 ) clamping the rim of the blank against the blank holder,
a table ( 31 ) for accommodating a punch tool ( 34 ) with an upper contour for cooperating with the lower contour of the matrix tool ( 18 ) for deforming the blank ( 20 ), said table being associated with a table drive ( 36 ) in order to move said table back and forth in the adjustment direction ( 16 ),
wherein the ram ( 15 ) in accordance with the ram drive ( 22 ) is configured to:
(1) in a single press stroke with the at least one servomotor ( 23 ) running and the matrix tool ( 18 ) closed to clamp the rim of the blank ( 20 ) against the blank holder ( 35 ), passes the reversal point (U t ) at least in two chronologically spaced apart points in time TA and TB;
(2) in a single press stroke a directional reversal of the ram ( 15 ) is performed between the points in time TA and TB via the at least one servomotor ( 23 ); and,
(3) in a single press stroke the ram ( 15 ) is lifted from the reversal point (U t ) by a small amount with the matrix tool ( 18 ) still closed until the at least one servomotor ( 23 ) is reversed at a point of time TC located between the points in time TA and TB and then moves downward again in order to pass the reversal point (U t ) of the second point of time TB;

wherein the ram drive ( 22 ) is configured to in a single press stroke to not stop the at least one servomotor ( 23 ) at the points of time TA and TB, but the at least one servomotor ( 23 ) continues to rotate and decelerates after the ram ( 15 ) has passed through the reversal point (U t ) at time TA and accelerates at the point of time TC before the ram ( 15 ) passes the reversal point (U t ) at time TB; and
wherein the table drive ( 36 ) assigned to the punch tool ( 34 ) is configured to start when the reversal point (U t ) of the ram ( 15 ) and the matrix tool ( 18 ) is reached for the first time, the punch tool ( 34 ) in accordance with the table drive ( 36 ) is configured in a single press stroke to perform a drawing operation of the blank ( 20 ) between the points in time TC and TB and not between the points of time TA and TB.

2. Drawing press as in claim 1 , characterized in that the coupling gear mechanism is an eccentric gear mechanism.

3. Drawing press as in claim 1 , characterized in that the abutment ( 47 ) is stationarily arranged on the press frame.

4. Drawing press as in claim 1 , characterized in that the abutment ( 47 ) and the rain ( 15 ) are arranged so as to be resilient relative to each other.

5. Drawing press as in claim 1 , characterized in that the abutment ( 47 ) is associated with an adjustment drive ( 48 ) in order to regulate the blanking holding force.

6. Drawing press as in claim 1 , characterized in that the table drive ( 36 ) comprises a gear mechanism ( 25 , 38 ) with at least one rest position in which the gear mechanism does not transfer movement to the table.

7. Drawing press as in claim 6 , characterized in that the gear mechanism ( 25 , 38 ) for the table drive ( 36 ) is a coupling gear mechanism.

8. Drawing press as in claim 7 , characterized in that the coupling gear mechanism is an eccentric gear mechanism.

9. Drawing press as in claim 8 , characterized in that the table drive ( 36 ) comprises at least one servomotor ( 40 , 41 ) that is configured to go in reverse.

10. Drawing press as in claim 9 , characterized in that the table drive ( 36 ) comprises an eccentric gear mechanism whose eccentric ( 42 ) is configured to move through an angle of rotation smaller than 90 degrees during one press stroke.

11. Drawing press as in claim 1 , characterized in that the press frame comprises a head ( 13 ), a table ( 31 ) and interposed stands ( 11 , 12 ).

12. A method for deep-drawing a sheet metal part, in particular a vehicle body part, with the use of a drawing press ( 10 ) comprising a ram ( 15 ) for the accommodation of a matrix tool ( 18 ), said matrix tool ( 18 ) comprising a rim ( 19 ) for contacting a rim of the sheet metal part ( 20 ) and a lower contour into which the sheet metal part ( 20 ) is to be deformed, a blank holder ( 35 ) opposite the ram ( 15 ), said bank holder abutting against an abutment ( 47 ) and configured to cooperate with the rim ( 19 ) of the matrix tool ( 18 ) to clamp the rim of the sheet metal part ( 20 ); said ram being movable between an open position and a closed position using a ram drive ( 22 ) comprising at least one servomotor ( 23 ) connected to the ram via a coupling gear mechanism ( 25 ) or a cam mechanism ( 54 ), said coupling gear mechanism or cam mechanism having a reversal point U t corresponding to a lower dead center position of the ram ( 15 ) resulting in the rim ( 19 ) of the matrix tool ( 18 ) clamping the rim of the sheet metal part ( 20 ) against the blank holder ( 35 ), wherein the ram ( 15 ) reaches and passes through its lower dead center position defining the closed position, wherein a servomotor driving said ram is decelerated and reversed after passing through the reversal point U t in order to move the ram ( 15 ) after its renewed passage through the dead center position, again into its open position through the reversal point U t ;
wherein the servomotor ( 23 ) performs a directional reversal of the ram ( 15 ) between points in time TA and TB defining two chronologically spaced apart points in time when the ram ( 15 ) passes through the reversal point U t during a single press stroke of the ram ( 15 ) with the servomotor ( 23 ) running and the matrix tool ( 18 ) closed to clamp the rim of the sheet metal part ( 20 ) against the blank holder ( 35 ), wherein the ram ( 15 ) is lifted from the reversal point U t by a small amount with the matrix tool ( 18 ) still closed until the servomotor is reversed at a point in time TC located between the points in time TA and TB and then moves downward again in order to pass the reversal point of time TB;
wherein the servomotor then accelerates the ram through the reversal point Ut of time TB; and
wherein the servomotor ( 23 ) is not stopped at the points of time TA and TB, but continues to rotate and decelerates after the ram ( 15 ) has passed through the reversal point at TA and accelerates at the point of time TC before the ram has passed the reversal point at TB; and
wherein a table drive assigned to a punch tool is started when the reversal point Ut of the ram and the matrix tool is reached for the first time, the punch tool in a single press stroke performing a drawing operation of the sheet metal part between the points in time TC and TB and not between the points in time TA and TB.

Assignees

• Schollhammer Dietmar
• Schuler Pressen Gmbh

Inventors

• Schollhammer Dietmar

Classifications

• B30B15/148

  Electrical control arrangements · CPC title

• B21D22/20 Primary

  Deep-drawing (special deep-drawing arrangements in, or in connection with, presses B21D24/00) · CPC title

• B30B1/266

  Drive systems for the cam, eccentric or crank axis · CPC title

• B30B15/20

  controlling the speed of the ram, e.g. the speed of the approach, pressing or return strokes · CPC title

• B21D22/22 Primary

  with devices for holding the edge of the blanks (B21D22/24 - B21D22/30 take precedence; shaping over a die without external former B21D11/02) · CPC title