Method for controlling the rotary drive of a hot forming machine
A method for controlling a rotary drive of a hot forming machine having a plurality of processing stations arranged in a circular manner and a rotary table arranged thereabove, in which glass tubes to be processed are held and moved from one processing station to the next by a stepwise rotary movement, is provided. The rotary table is driven by a step gear by which a movement of a drive shaft is translated into a cyclic step movement, a step cycle of which comprises a movement phase and a subsequent standstill phase. A first value for the angular velocity of the drive shaft is assumed at a first time in the movement phase of the step cycle and a second value different from the first value is assumed at a second time in the standstill phase of the same step cycle.
1. A hot forming machine, comprising:
a plurality of processing stations arranged in a circular manner and a rotary table arranged thereabove, in which glass tubes to be processed are held and movable from one processing station to the next by a stepwise rotary movement, the rotary table being connected on a drive side to a step gear which translates a movement of a drive shaft into a cyclic step movement, a step cycle of which comprises a movement phase and a subsequent standstill phase; and
a drive unit comprising:
a drive motor adapted to drive the drive shaft at a variable, predeterminable angular velocity; and
a control unit adapted to drive the drive shaft in such a manner that the angular velocity of the drive shaft assumes a first value at a first time in the movement phase of the step cycle and assumes a second value different from the first value at a second time in the standstill phase of the same step cycle.
2. The hot forming machine according to claim 1 , wherein the first value is higher than the second value.
3. The hot forming machine according to claim 1 , wherein the angular velocity is constant during the movement phase.
4. The hot forming machine according to claim 1 , wherein the angular velocity is constant during a time span within the standstill phase.
5. The hot forming machine according to claim 4 , wherein the time span comprises more than 60% of the standstill phase.
6. The hot forming machine according to claim 1 , wherein a plurality of step cycles immediately follow one another, an angular velocity curve of each step cycle being identical.
7. A drive unit for a hot forming machine having a plurality of processing stations arranged in a circular manner and a rotary table arranged thereabove, in which glass tubes to be processed are held and movable from one processing station to the next by a stepwise rotary movement, the rotary table being connected on a drive side to a step gear which translates a movement of a drive shaft into a cyclic step movement, a step cycle of which comprises a movement phase and a subsequent standstill phase, the drive unit comprising:
a drive motor adapted to drive the drive shaft at a variable, predeterminable angular velocity; and
a control unit adapted to drive the drive shaft in such a manner that the angular velocity of the drive shaft assumes a first value at a first time in the movement phase of the step cycle and assumes a second value different from the first value at a second time in the standstill phase of the same step cycle.
8. The drive unit according to claim 7 , wherein the drive motor is designed as a synchronous motor.
9. The drive unit according to claim 7 , wherein the step gear is designed as a cylinder cam gear.
10. A control unit for a rotary drive of a hot forming machine having a plurality of processing stations arranged in a circular manner and a rotary table arranged thereabove, in which glass tubes to be processed are held and movable from one processing station to the next by a stepwise rotary movement, the rotary table being connected on a drive side to a step gear which translates a movement of a drive shaft into a cyclic step movement, a step cycle of which comprises a movement phase and a subsequent standstill phase, the control unit being adapted to drive the drive shaft of the step gear with a variable angular velocity in such a manner that the angular velocity of the drive shaft assumes a first value at a first time in the movement phase of the step cycle and assumes a second value different from the first value at a second time in the standstill phase of the same step cycle.
11. A method for retrofitting a hot-forming machine with a plurality of processing stations arranged in a circular manner and a rotary table arranged thereabove, in which glass tubes to be processed are held and movable from one processing station to the next by a stepwise rotary movement, the rotary table being connected on a drive side to a step gear which translates a movement of a drive shaft into a cyclic step movement, a step cycle of which comprises a movement phase and a subsequent standstill phase, the method comprising:
retrofitting a control unit in the hot forming machine, the control unit being adapted to drive the drive shaft in such a manner that the angular velocity of the drive shaft assumes a first value at a first time in the movement phase of the step cycle and assumes a second value different from the first value at a second time in the standstill phase of the same step cycle.
12. The method according to claim 11 , further comprising retrofitting a drive motor for driving the drive shaft with a variable, predeterminable angular speed in the hot forming machine.
13. The method according to claim 12 , wherein the drive motor is designed as a synchronous motor.