Method of and apparatus for the fine cutting (punching) of articles

• US 4,586,360 A
• Filed: 07/06/1984
• Issued: 05/06/1986
• Est. Priority Date: 07/08/1983
• Status: Expired due to Term

• Current Assignee: Dako-Werkzeugfabriken David Kotthaus GmbH & Company KG
• Original Assignee: Dako-Werkzeugfabriken David Kotthaus GmbH & Company KG
• Inventors: Honsberg, Friedrich-Wilhelm, Halbach, Kurt, Jurgensmeyer, Willi
• Primary Examiner(s): Crane, Daniel C.
• Application Number:
  US06/628,183
• Time in Patent Office: 669 Days
• Field of Search: 72/327-330, 72/333, 72/335, 72/339, 72/344, 72/354, 72/358, 72/338, 72/352, 29/159.2
• US Class Current: 72/328
• CPC Class Codes: B21D 28/16 Shoulder or burr prevention , e.g. fine-blanking
• CPC Class Codes: Y10T 29/49472 Punching or stamping

Abstract

Fine die stamping of workpieces from sheet metal is effected by clamping the workpiece between a die plate and guide plate, supporting the portion of the material to form the article by an ejector which is displaced along with the punch, and driving the supported portion of the material into a hole in the die plate having flanks tapered away from the guide plate and punch so that swaging occurs on the separated portion with or upon its separation from the balance of the workpiece material.

Claims

1. A method of fine cutting an article from a flat workpiece, comprising the steps of:

clamping said workpiece between a die plate and a guide plate, said die plate having a hole having the configuration of said article with the wall of the hole defined by at least some flanks tapered away from said guide plates so that the hole decreases in cross-section away from the guide plate, said workpiece being clamped so that a portion of said workpiece lies across said hole and a remainder of said workpiece is clamped between the die plate and guide plate;

supporting said portion of said workpiece lying across said hole with an ejector; and

punching said portion of said workpiece from the remainder of said workpiece into said hole with a punch having a cross section complementary to the cross section of said hole at a side thereof turned toward said guide plate by displacing said punch in said guide plate toward said die plate while continuing to support said portion with said ejector, thereby separating said portion from the remainder of the workpiece and simultaneously with the separation of said portion, swaging it to have tapered flanks in said hole and to form said article.

2. The method defined in claim 1 wherein said portion is pressed from said workpiece into said hole and is swaged therein in a single continuous operation of said punch.

3. The method defined in claim 1 wherein said portion is first pressed partially from said remainder of said workpiece in a first step by a punch in a hole without tapered flanks and is then swaged in a second step in said hole with tapered flanks.

4. A tool for the fine punching of workpieces having tapered flanks, comprising:

a guide plate having a workpiece clamping surface;

a die plate juxtaposed with said guide plate and having a workpiece clamping surface defining a plane and positioned relative to said guide plate clamping surface to clamp a flat workpiece thereagainst, said die plate being formed with a hole having a contour provided with at least some flanks tapering away from said plane of contact of said die plate with said workpiece and extending to said plane, said taper being such that the cross-section of said hole decreases from said plane to a position spaced away from said plane;

an ejector displaceable in said hole for supporting a portion of a workpiece adapted to be punched into said hole; and

a punch aligned with said ejector and having a cross section complementary to that of said hole at said plane, means for movably mounting both said punch and ejector so that said punch severs said portion from the remainder of said workpiece and drives it into said hole while said portion is supported by said ejector for swaging said portion immediately during the severing of said portion to impart a taper thereto and form said article.

5. The apparatus defined in claim 4 wherein said tapered flanks have a length slightly greater than the spacing between said plates upon clamping of the workpiece between them prior to the swaging of said portion.

6. The apparatus defined in claim 4, further comprising another die plate for initially deforming said portion from said remainder of said workpiece prior to the swaging of said portion.

7. The apparatus defined in claim 4 wherein said guide plate is formed with an annular barb of triangular cross section tapering in the direction of the said die plate and impressing a groove in said workpiece when said workpiece is claimed between said plates, said die plate being flat opposite said guide plate.

8. A method of fine cutting an article from a flat workpiece, comprising the steps of:

clamping said workpiece between a die plate and a guide plate, said die plate having a hole having the configuration of said article with the wall of the hole defined by at least some flanks tapered away from said guide plate so that the hole decreases in cross-section away from the guide plate, said workpiece being clamped so that a portion of said workpiece lies across said hole and a remainder of said workpiece is clamped between the die plate and guide plate, said guide plate having an annular barb which is pressed into and embosses said workpiece outwardly of and coaxial with said hole upon the clamping of said workpiece between said die plate and said guide plate, said guide plate being flat opposite said barb;

supporting said portion of said workpiece lying across said hole with an ejector; and

punching said portion of said workpiece from the remainder of said workpiece into said hole with a punch having a cross section complementary to the cross section of said hole at a side thereof turned toward said guide plate by displacing said punch in said guide plate toward said die plate while continuing to support said portion with said ejector, thereby separating said portion from the remainder of the workpiece and simultaneously with the separation of said portion, swaging it to have tapered flanks in said hole and to form said article.