Plate bending machine equipped with a plate clamping manipulator and a plate position detecting device

• US 5,058,406 A
• Filed: 03/06/1990
• Issued: 10/22/1991
• Est. Priority Date: 01/29/1988
• Status: Expired due to Term

• Current Assignee: Amada Company Limited
• Original Assignee: Amada Company Limited
• Inventors: Arghiracopulos, Salvatore, Sartorio, Franco, Prunotto, Gianpaolo, Sgandurra, Francesco
• Primary Examiner(s): Spruill, Robert L.
• Application Number:
  US07/489,875
• Time in Patent Office: 595 Days
• Field of Search: 72/9, 72/420, 72/461, 72/422, 83/419, 83/269, 83/367, 83/704, 83/708, 901/24, 414/590
• US Class Current: 72/16.2
• CPC Class Codes: B21D 43/003 Positioning devices B21D28/04 and B21D28/265 take precedence; stops B21D43/26; centering moving strips B21D43/023
• CPC Class Codes: B21D 43/105 Manipulators, i.e. mechanical arms carrying a gripper element having several degrees of freedom
• CPC Class Codes: B21D 5/0281 Workpiece supporting devices

Abstract

A press brake for bending plates. A press brake is provided for bending plates, including a pair of dies which act in mutual cooperation to bend a plate, a plate clamping manipulator which grasps and moves a plate which is to be placed in a scheduled location with respect to the dies, and a plate position detector mounted on the press brake in a specified positional relationship with respect to the dies, for detecting a position of the plate grasped by the manipulaator, and controlling the manipulator in response to a signal from the plate position detector.

Claims

1. A press brake comprising:

a pair of dies which can act in mutual cooperation to bend a workpiece having edges;

a manipulator for grasping and moving the workpiece which is to be placed in an object position with respect to the dies; and

detector means, mounted in a frame of the press brake in a specified positional relationship with respect to the dies, for detecting a plurality of points along the edges of the workpiece provided by the manipulator, thereby detecting a current position; and

means for controlling the manipulator in response to a signal from the workpiece position detector means by adjusting the workpiece edges relative to the detector means so that the workpiece is positioned in the object position with respect to the dies;

said means for controlling including means for calculating a spacing between the current position of the workpiece and the object position of the workpiece for at least two of said plurality of points along the edges of the workpiece and means for moving the workpiece so that each of said plurality of points moves toward each object position by a predetermined distance, the predetermined distance being determined by multiplying each of the calculated spacings by a factor which is smaller than one.

2. The press brake of claim 1 wherein the dies have a longitudinal axis and wherein further the workpiece detector means is a device provided at the rear of the dies for detecting the workpiece position in a direction at right angles to the longitudinal axis of the dies.

3. The press brake of claim 2 wherein the workpiece position detector means is so constructed as to measure current workpiece position within a specified range and the manipulator controlling means is so constructed as to carry out a final positioning at a mid position in the specified detection range of the detector means.

4. The press brake of claim 1 wherein the dies have a longitudinal axis and a side edge section and wherein further the workpiece position detector means includes a device provided close to the side edge section of the dies for detecting the workpiece position along the longitudinal axis of the dies.

5. The press brake of claim 4 wherein the workpiece detector means is so constructed as to measure current workpiece position within a specified range and the manipulator controlling means is so constructed as to carry out a final positioning at a mid position in the specified detection range of the detector means.

6. The press brake of claim 1, wherein the manipulator includes jaws for gripping the workpiece, and support means for supporting the jaws free to move along an axis perpendicular to the longitudinal axis of the dies and free to rotate within a plane parallel to and passing through the longitudinal axis of the dies.

7. The press brake of claim 6, wherein the manipulator further includes another supporting means for supporting the jaws free to move along the longitudinal axis of the dies.

8. The press brake of claim 1, wherein the detector means detect at least three points along the edges of the workpiece.

9. A method of positioning a workpiece with respect to a press brake, the positioning occurring between current and object positions comprising the steps of:

inserting the workpiece between dies of the press brake;

positioning the workpiece in a current position with respect to the dies;

detecting the current positions of a plurality of sections of the workpiece with respect to object positions thereof;

calculating a first spacing between the current position of the first section of the workpiece and the object positions of the same, and calculating a second spacing between the current position of the second section of the workpiece and the object position of the same;

moving the workpiece so that each of the sections thereof moves toward each of the object positions thereof by a predetermined distance, the predetermined distance being determined by multiplying each of the spacings calculated above by a factor which is smaller than one.

10. The method of claim 9, further comprising the step of stopping the workpiece movement when the spacings between the current positions and the object positions becomes less than respective allowable values.

11. The method for positioning a workpiece of claim 9 wherein the positioning has associated therewith position coordinate which comprise:

linear coordinates for a point on the workpiece at right angles to the longitudinal axis of the dies; and

angular coordinates of a specified edge of the workpiece with respect to the longitudinal axis of the dies.

12. The method of claim 9, wherein one of the current positions of the workpiece is an average of positions of rear edges of the workpiece at both sides thereof in the lateral directions of the press brake, and another one of the current positions of the workpiece is an inclination angle of the rear edge of the workpiece with respect to the longitudinal axis of the dies.

13. A press brake comprising:

a pair of dies which can act in mutual cooperation to bend a workpiece having edges and lying substantially in a workpiece plane, the dies having a longitudinal axis;

a manipulator for grasping and moving the workpiece which is to be placed in an object position with respect to the dies, the manipulator including a single motor for rotating the workpiece about an axis perpendicular to the surface of the workpiece positioned in the workpiece plane;

detector means, mounted on a frame of the press brake in a specified positioning relationship with respect to the dies, for detecting a plurality of points along the edges of the workpiece provided by the manipulator, thereby detecting a current position of the workpiece edges with respect to the detector means;

means for controlling the manipulator in response to a signal from the workpiece position detector means by adjusting the workpiece edges relative to the detector means so that the workpiece is positioned in the object position with respect to the dies; and

the control means calculating spacings DEX and SX between current positions of the workpiece and the object positions of the workpiece for two of the plurality of points along the edges of the workpiece;

calculating from the spacings DEX and SX a first parameter YM substantially representing the mean of the spacings DEX and SX, and a second parameter ALFA substantially representing the rotation of the edge of the workpiece about the axis perpendicular to the surface thereof with respect to the longitudinal axis of the dies, rotationally moving the workpiece by said motor so that each of the first and the second parameters decreases; and

stopping the rotational movement of the workpiece when at least the first parameter YM gets small than a predetermined value YS.

14. The press brake of claim 13, wherein the control means stopping the rotational movement of the workpiece when the difference between the first and the second parameters gets smaller than a predetermined value and the first parameter YM gets smaller than a predetermined value.