The more comprehensively plants are automated, the more reliably malfunctions that could lead to defects, machine downtimes or even damage to the product must be excluded. In order to protect the transported products in packaging machines, safety elements in the form of switching or slipping clutches are used in the drive train. The advantages and disadvantages of the two different types of coupling must be taken into account, as they are ultimately decisive for effective protection of the equipment.
Slip clutches are the simplest overload systems. The disadvantage in many applications, however, is that the overload torque cannot be set precisely and permanently. In addition, the frictional resistance of the lining can be severely affected, especially by moisture and lubricants. The wear of the friction linings as well as the resulting heat development must also be taken into account. The advantage of the slipping clutch is its short design.
The advantages of ball detent clutches are, on the one hand, the relatively precisely adjustable cut-off torque, the high repeat accuracy and the low ratchet torque. In case of overload, a safe separation of the masses in the millisecond range is guaranteed.
For the emergency stop of the system, the switching movement can be scanned very easily by a proximity switch.
The safety clutch type ECH for chain drives from ENEMAC combines the advantages of ball detent clutches with the short design of slip clutches (slip hubs). The output element in the form of a chain wheel is integrated into the clutch as a functional part. Due to the positive locking of the clutch by means of balls which are pressed into a conical countersink by diaphragm springs, a high repeatability of the specified disengaging torque and the permanent function is guaranteed, unlike with a slip clutch. The clutch is set to a specific disengaging torque by means of a slotted nut. In case of overload, the clutch disengages and after one revolution engages again (synchronous disengagement).
The setting torques for the safety coupling type ECH range from 2 to 900 Nm for 11 sizes.
The coupling is preferably used in general mechanical engineering, wherever chain drives are used as drive elements.
