Center punch (tool)
A grain is a hallmark that the graining is used. It consists of tempered tool steel , has a hardened tip and a shaft. Usually the tip has an angle of 60 ° or 90 °.
application
With pre-punching or center punching , the tip of the punch is driven into the workpiece with a light hammer blow . This creates a small depression in the form of a crater, which is known as the grain . If a deeper grain is required, a grain with a tip of 60 ° can be used afterwards. The accuracy of punching depends on the accuracy of scribing .
In constructions with wood, the center punch is an aid to be able to screw in screws precisely and easily.
The centering bell is a special form of the center punch. The grain is guided here in the axis extension of a hollow cone with a drilled hole, into the interior of which it protrudes. This enables the smooth end faces of cylindrical workpieces to be center-punched without prior marking, as the bell centers itself through its conical shape.
Hole preparation
Most of the time, the grit is used to give a drill its first guide at a specified position. Without grain size of the drill tends to the workpiece when drilling bleeding , uncontrolled sliding over the surface, no dimensionally stable drilling position is so possible. When drilling purely by machine, e.g. B. with NC-controlled machine tools , a center drill or an NC tapping drill is used for this task instead of a center punch .
Contour marking
In addition to preparing holes, grain sizes are also used as accuracy points, for example on sheet metal , in order to provide a robust and precise orientation aid for the following work steps. A double-point center punch can also be used here to make the work more effective with long contours. The distance between the two tips on a shaft depends on the fineness / coarseness of the marking work. This application has become rare today because NC-controlled machine tools are more suitable for creating contours.
See also
Individual evidence
- ↑ Walter Bartsch: At the lathe. Expertise for lathe operators , Georg Westermann Verlag, Braunschweig 1987, ISBN 3-14-201498-5
