Rotatable chuck for glass tubes

2.1 Chucks for glass tubes must be constructed in such a way that, on the one hand, they grasp the glass tube gently in order to ensure that it is not destroyed and, on the other hand, hold it firmly enough to ensure that the glass tube can be worked safely. This requires a technical complexity which increases the dimensions of the chuck, and leads to a narrow diameter range of glass tubes which can be clamped. For a different diameter range, the chucks must be modified. The new chuck is intended to have a wide diameter range while having small external dimensions. 2.2 The chuck (1) has clamping jaws (18) which are displaceable radially relative to its longitudinal axis (LA) and the distance of which from the longitudinal axis is determined via a pressure sleeve (8) which is connected via a positive guide (16, 17) to the clamping jaws. The positive guide forms an angle of 30 DEG to 60 DEG , preferably 45 DEG , to the longitudinal axis. 2.3 The chuck serves to hold a glass tube in a bottle making machine.