CS199833B1 - Method of fine punched thin-walled grate manufacture - Google Patents

Description

The invention provides a method of manufacturing a fine-perforated thin-walled grid with a one-sided rounding of openings, forming, for example, a fixed knife of an electric shaver.

The fine-perforated thin-walled grid, on whose inner surface the movable electric knife of the electric razor oscillates, is still produced by etching or electroplating, so-called galvanoplasty.

At present, fine holes in the thin-walled grid are also produced by punching, stretching and grinding, and it is known to use an elastic environment for forming operations.

The production of etching grids for electric shavers is very lengthy and laborious and does not guarantee quality products, as burrs are produced on both sides of the etched products.

Thin-walled fine-mesh grills with galvanoplastic are superior, but expensive to manufacture and have a low lifetime in service.

The punching and stretching holes created in thin-walled grids are geometrically more accurate and the products are of better quality and less laborious. However, punch waste is very difficult to remove due to its small size. If it sticks to some parts of the tool, it will cause problems with stretching or cause scrap.

The described drawbacks of the known technologies are substantially eliminated by the method of producing a fine-perforated thin-walled grid with finishing operations of the edges of the openings according to the invention, which is based on the fact that openings with one-sided rounding are formed by tearing

199 833

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AND

199 833 semi-finished product. The holes are formed by tearing while rolling, or by tearing on the coiled blank by compressing the elastic environment.

In this way, higher product quality is achieved at reduced costs.

An exemplary embodiment of a method of manufacturing a fine-perforated thin-walled grille with a one-sided rounding is apparent from the attached drawing, wherein FIG. 4 and 5 show cross-sectional views of steel tools for tearing, FIG. 6 is a tool in which one part is formed by an elastic environment, FIG. 7 shows a tool for tearing openings by compressing the elastic environment.

In the known formation of fine openings 1 into the thin-walled grid 2 by etching, the active surface 4 is irregular and has burrs 4 on both sides of the thin-walled grid 2.

The thin-walled grid 2 used as a fixed knife for electric shavers must have rounded openings on the outside. According to the invention, the rounding 6 on the one hand is achieved by tearing. Since the edge of the hole flange 6 thus obtained is not straight, it has to be treated by machining, e.g. by abrasion.

The steel punching tool 8 comprises a punch 8 provided with protrusions 8e with cutting edges 10.

The active surfaces of the protrusions 11 merge into the flashing surfaces 12.

The die 13 corresponding to the punch 8 with the appropriate clearance for the thickness of the workpiece 14 to be processed may be in one piece, but it may be composed of individual inserts 16, which allows a simple opening of the sink holes 17.

The functional element 18 for breaking into the elastic environment 19 has the same shape as the punch 8. The use of the functional element 18 and the elastic environment 19 simplifies the tool. However, the elastic environment 19 needs to be enclosed in the sleeve 20.

By compressing the elastic insert 21 in the swiveling tool 22, the precursor blank 15 extends across the active surfaces in shape identical for both the forming punch 8 and the functional element 18 but adapted to a segment shape.

The edge height of the rim 6 is adjusted by machining in a flat or coiled state. The fine coating produced during machining is removed by electrolytic, electroerosive or other suitable means.

The shape of the fine holes is arbitrary. Accordingly, the punch 8, or the functional element 18 and the matrix 13 or the insert 16 are adapted accordingly. The most preferred in terms of production are square and rhombic shapes with corresponding corner roundings and elongated oval shapes.

The method of producing a fine-perforated thin-walled grid, for example for the electric shavers of the invention, can also be advantageously used in the manufacture of other components, such as fine-perforated thin-walled nets, both on presses and on special roll stands.

Claims (3)

A method of manufacturing a fine-perforated thin-walled grid with finishing operations on the edges of holes, characterized in that holes are formed by one-sided rounding by rupture of the starting stock. 2. Method according to claim 1, characterized in that the openings are produced by rupture during simultaneous rolling. Method according to claim 1, characterized in that the openings on the coiled blank are torn by compressing the elastic environment.