Pointeau a dispositif de frappe incorpore /Granetes automatico /Automatischer Körner
An automatic centre punch unlike its conventional counterpart (the ordinary centre punch) doesn't require a hammer to strike. It can be pushed single-handedly against the surface that needs to be marked. The springs amplify and transfer the force thus creating the desired indent. The mechanism consists of:
At the equilibrium position both the springs neither undergo compression or tension and are thus at a stable state. The intermediate pin tends to incline away from the pocket inside the weight.
Once a force is applied onto the punch against a rigid surface, the surface tends to push the punch's pin back into its housing. The pin further pushes onto the intermediate pin upwards which in turn pushes the weight against the heavy spring. The spring now compressed is removed from its stable state.
As the intermediate pin is further pushed upwards it gets aligned straight as the slope on the pin meshes against the inner groove of the body. The intermediate pin gets pushed inside the pocket in the hung weight eliminating the contact between the pin and the weight. This removes any compression force acting on the heavy spring. The spring tends to achieve its equilibrium state by pushing the weight against the pin. The force is eventually transferred to the punch pin which pushes into the surface thus creating a recess in it.
As the cap of the punch is loosened, more space is created at the back of the punch. This allows the intermediate pin to retract a larger distance before it starts to compress the spring leading to a comparitively lower build up of force inside the spring. Once the pin enters the weight's pocket the spring exerts back this decreased force which is eventually transferred to the punch pin and then to the surface. This reduces the intensity of the strike of the punch and the depth of the recess. Similarly tightening the cap allows higher intensity strikes and deeper indents.
Centre punches are used for marking an indentation on a surface in order to guide the drill bit for a clean and smooth operation.