CS200324B1 - Expansion punch particularly for the exact forming - Google Patents

Description

The invention relates to an expansive punch, in particular for precision forming, forming part of a forming tool for simplified production of precision molded parts while reducing the cost of producing molds.

The known butchers used in sheet drawing or bulk forming operations have certain radii at their forward free ends which are necessary in view of the desired shape of the workpiece.

The size of these radii must be chosen with regard to the extent of deformation of the formed parts, especially at their exposed locations, which are usually in the region of said radii. For these reasons, for example, punches for sheet metal drawing with graded radius are chosen; Naturally, it is then necessary to use more drawing operations than the final shape of the separation is achieved. This circumstance greatly affects the economics of these forming operations.

For the purpose of producing hollow molded parts, for example by extrusion or indentation methods, punches provided with a step at their front free end to improve the creep of the material of the molded part are suitable. However, this shoulder is worn when being removed from the cavity being formed and, in addition, damages the wall of the cavity.

For the production of said molded parts, it is advantageous to use an expansion butcher according to the invention, which largely eliminates the disadvantages mentioned, and whose background is based on:

20C 324

200 324 that consists of a core forming a support portion for a shroud that is closed at its free end by a flexible bottom having a center or edge of equal or different thickness in convex or concave and optionally non-parallel surface lines external to the core and internal to the shroud.

The advantages of the solution can be seen from the following description of the expansion punch according to the invention and the schematically depicted drawings, where Fig. 1 shows a longitudinal section of the expansion punch at the beginning and end of the drawing operation. 4 shows a longitudinal section of an expansion punch at the beginning and end of the bulk forming, FIG. 5 an embodiment of a resilient bottom concave, FIG.

During deep drawing in a not shown punch (Fig. 1), the support core 1 of the punch transfers the work force to the casing 2, closed at the free end by the resilient bottom 3. By the pressure of the core 1 applied by the work force an extract 7 (Fig. 3) with a slight rounding at the edge of the excess material of the bottom of the peeled upstock 6 (Fig. 2). The protrusion 6 is formed by pulling from the abutment o while the spring-shaped resilient bottom 2 of the housing 2 is sprung.

The expansion butcher works similarly in bulk forming (Fig. 4). At the beginning of the operation volume forming flexible bottom resting 2 ⁰ blank. Overcoming the resilience of the resilient bottom 2 of the casing 2 increases the dimension of the functional part 9 of the casing 2. On return travel of the punch, the suspension is reduced and thereby the functional part 9 of the casing 8 is reduced at 1C.

In order to improve the opening conditions of the expansion die shell 2, the outer outer surface lines of the core 6 and the inner surface lines of the shell 2 are not parallel.

The bottom of the expansion punch sheath 6 (FIG. 5,6) may be convex, concave or of varying thickness from edge to center.

The advantages of the expansive bumper are particularly prominent in the increased accuracy requirements of the molded product. Due to the reduction of the punching resistance, the tool life will be prolonged and the cost of forming operations will be reduced.

SUBJECT OF YOU & ALLEL

Claims (6)

SUBJECT OF YOU & ALLEL Expansion punch, in particular for precision forming, characterized in that it consists of a core 1 forming a support part for the casing (2), which is closed at its free end by a flexible bottom (3). 2. r-xponsive. A punch according to claim 1, characterized in that the flexible bottom (3) has a different thickness from the center to the center. · Expansion butcher according to items 1 and 2, characterized in that the resilient bottom (3) is concave. Expansion punch according to points 1 and 2, characterized in that the resilient bottom (3) is convex. Expansion punch according to Claims 1 to 4, characterized in that the outer surface lines of the core (1) and the inner surface lines of the shell (2) are not parallel to each other. 6 drawings