Device for screwing on caps
The device for screwing on a cap comprises a gripping head fixed to a rotary spindle, and a drive shaft connected to a drive member carried by a frame, the rotary spindle and the drive shaft are connected to each other on the same axis by a resilient coupling member, connected both to the rotary spindle and to the drive shaft, and the device further comprises a detector member for detecting relative rotation between the rotary spindle and the drive shaft, and a control member for interrupting tightening of the cap when the relative rotation reaches a predetermined threshold.
1. A device for screwing on a cap, which screwing-on device comprises a gripping head fixed to a rotary spindle, and a drive shaft connected to a drive member carried by a frame, wherein the rotary spindle and the drive shaft are connected to each other on the same axis by a resilient coupling member, connected both to the rotary spindle and to the drive shaft, and wherein the device further comprises a detector member for detecting relative rotation between the rotary spindle and the drive shaft, and a control member for interrupting tightening of the cap when the relative rotation reaches a predetermined threshold.
2. A screwing-on device according to claim 1 , wherein the resilient coupling member is a spring disposed between two abutments.
3. A screwing-on device according to claim 2 , wherein at least one of the abutments is adjustable.
4. A screwing-on device according to claim 1 , wherein the detector member comprises at least one disk having a position which is a function of a relative angular position between the drive shaft and the rotary spindle, and a position sensor for detecting the position of the disk.
5. A screwing-on device according to claim 4 , wherein the disk is constrained to rotate with the drive shaft, while being mounted to move axially relative thereto, and is provided with positioning studs coming into abutment against ramps that are constrained to rotate with the rotary spindle.
6. A screwing-on device according to claim 5 , wherein the ramp is formed by a frustoconical notch.
7. A screwing-on device according to claim 1 , wherein the gripping head comprises a housing fixed to the rotary spindle, a bell-shaped actuating member constrained to rotate with the housing and mounted to be movable axially relatively thereto, and gripping jaws mounted to move radially inside the actuating member, the actuating member and the jaws having ramps disposed facing one another to transform axial movement of the actuating member into radial movement of the gripping jaws.
8. A screwing-on device according to claim 7 , wherein the ramps are provided with grooves in which coupling balls are disposed.
9. A screwing-on device according to claim 7 , wherein the rotary spindle is hollow, and wherein the actuating member is connected by an actuating rod extending inside the rotary spindle to an actuator carried by the frame of the device.
10. A screwing-on device according to claim 9 , wherein the actuating rod is hollow and a cap presence detector rod extends inside the actuating rod to a detector carried by the frame.
11. A screwing-on device according to claim 1 , wherein the control member for interrupting tightening of the cap is disposed to interrupt rotation of the drive shaft.
12. A screwing-on device according to claim 1 , wherein the control member for interrupting tightening of the cap is disposed to cause the gripping head to open.