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A device is provided for determining and optimizing a pre-draft value on a draw unit for slivers. The draw unit has a feed roll pair, a center roll pair and a delivery roll pair, a pre-draft zone between the feed roll pair and the center roll pair, and a main draft zone between the center roll pair

A device is provided for determining and optimizing a pre-draft value on a draw unit for slivers. The draw unit has a feed roll pair, a center roll pair and a delivery roll pair, a pre-draft zone between the feed roll pair and the center roll pair, and a main draft zone between the center roll pair and the delivery roll pair. The device has a center roll drive motor for driving a lower roll of the center roll pair, a sensor for measuring values of a variable indicative of draft forces at the center roll drive motor, and means for controlling the drive motor in accordance with a function defining a relationship between the measured value and the pre-draft value. The function indicates an optimum region having at least one of an increase end point and an increase end region, the optimum region providing a parameter that is usable for optimizing the pre-draft value for the draw unit. A speed of the center roll drive motor is controlled to adjust a ratio of circumferential speeds of the center roll pair to the feed roll pair in order to change the pre-draft value.

대표청구항 ▼

1. A device for determining and optimizing a pre-draft value on a draw unit for slivers, the draw unit having a feed roll pair, a center roll pair and a delivery roll pair, a pre-draft zone between the feed roll pair and the center roll pair, and a main draft zone between the center roll pair and th

1. A device for determining and optimizing a pre-draft value on a draw unit for slivers, the draw unit having a feed roll pair, a center roll pair and a delivery roll pair, a pre-draft zone between the feed roll pair and the center roll pair, and a main draft zone between the center roll pair and the delivery roll pair, the device comprising: a center roll drive motor for driving a lower roll of the center roll pair; a sensor for measuring values of a variable indicative of draft forces at the center roll drive motor; and means for controlling the drive motor in accordance with a function defining a relationship between the measured value and the pre-draft value, the function indicating an optimum region having at least one of an increase end point and an increase end region, the optimum region providing a parameter that is usable for optimizing the pre-draft value for the draw unit, wherein a speed of the center roll drive motor is controlled to adjust a ratio of circumferential speeds of the center roll pair to the feed roll pair in order to change the pre-draft value. 2. The device according to claim 1, wherein a driving force for the center roll drive motor is measured by the sensor. 3. The device according to claim 2, wherein the driving force is measured by measuring the torque at one roll of the center roll pair. 4. The device according to claim 2, wherein the driving force is measured by measuring the actual current consumption of the drive motor. 5. The device according to claim 2, wherein the driving force is measured by measuring the phase displacement. 6. The device according to claim 2, wherein the driving force is measured by measuring a change in speed of the center roll pair. 7. The device according to claim 1, further comprising separate drive motors for each roll pair of the feed roll pair, the center roll pair and the delivery roll pair. 8. The device according to claim 1, wherein the center roll drive motor drives only the lower roll of the center roll pair, and the center roll drive motor is controllable. 9. The device according to claim 1, wherein the draft force increases until the optimum region is reached. 10. The device according to claim 1, wherein the measured values are converted to electronic signals. 11. The device according to claim 1, wherein the measured values are assigned to specific pre-drafts. 12. The device according to claim 11, wherein the controlling means comprises a processor, and the measured values are mathematically assigned to specific pre-drafts by the processor. 13. The device according to claim 1, further comprising a data table containing an assignment of the measured values to specific pre-draft values. 14. The device according to claim 1, wherein an optimum pre-draft value is determined automatically. 15. The device according to claim 1, wherein an optimum pre-draft value is adjusted automatically. 16. The device according to claim 1, wherein the controlling means comprises a processor, and the sensor is connected to the processor. 17. The device according to claim 16, wherein the center roll drive motor is connected to the processor. 18. The device according to claim 17, wherein an optimum adjustment of the draw unit is provided to the center roll drive motor. 19. The device according to claim 1, wherein the variable indicative of the draft forces is measured at the delivery roll pair in the pre-draft zone. 20. The device according to claim 1, wherein the variable indicative of the draft forces is measured at the feed roll pair in the main draft zone.