The braking angle on mechanical forging presses
The standstill of the ram and all moving masses after disconnecting the clutch and engaging the brake plays a decisive role in the safety concept of presses.
The size of the brake angle should not be greater than max. 20 ° to TDC / OU. In the case of large mechanical presses, the braking angle is determined by the size of the masses to be braked, the air pressure, the pressure, the pressure drop times, the spring pressure and the processing of the signals in the case of large mechanical presses with friction linings and electro-pneumatically controlled PSV valves. Of course, the flooring and the temperature play a further decisive role, but more about this later.
Various systems are used to prevent the clutch and the brake from interacting with each other. The clutch is pneumatically engaged and the brake actuated by a push rod purely mechanically controlled. Other manufacturers program times between the circuits of the valves or program angles in which the clutch or brake is disengaged. Faulty cam switching and programming lead to increased wear on the linings and the system.
Important are pressure springs tested and functioning properly in friction linings which control the engagement of the brake or disengagement of the clutch. Defective compression springs lead to increased wear on the friction linings. Friction linings must be measured when changing, uneven wear is often attributable to faulty compression springs. Not infrequently, the cooling of the friction linings is underestimated and neglected. Hot brake discs provide for the glazing of the friction linings and increase the braking angle. And this again leads to an increased wear on the linings and unnecessary costs.
With further wear on the friction linings of the brake and clutch, the strokes and the air consumption are also increased and the pressure drop times are extended, resulting in an increase in the braking angle. The braking angle can be corrected and adjusted by means of adjustment possibilities. Mechanically, the play of the pads can be adjusted / reduced, the switching / monitoring times of the valves and cams can be readjusted electrically / electronically.
The lining of friction linings must maintain a high coefficient of friction, high abrasion resistance, stable and flexible, environmentally friendly and health-neutral and generate a low noise level. The symbiosis of the various properties makes this system so stable and economical.
Monitoring of all factors is easily possible in modern control systems. Temperatures, switching times and angles are indicated on the display and can immediately provide information on the condition of the components. Operators and maintenance receive relevant information for their daily work.
Maintenance maintains and inspects the system in routine intervals and can react specifically to faults and machine failures. The monitoring of the conditions of components and machines helps maintenance in the performance of their tasks. The spare parts strategy and the maintenance organization help to reduce downtime and downtime and to use side-by-side repairs.
All planned work of the maintenance is planned over the entire range in order to ensure the most effective maintenance possible. This means that the machine running time can be positively influenced by maintenance.