Torque-applying tool and control therefor
First Claim
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1. A method of controlling a torque applying tool to apply a selected torque by controlling a speed of the torque applying tool, the method comprising:
- calculating a first torque at an end of a deceleration ramp that is a percentage of the selected torque;
calculating a second torque at a start of the deceleration ramp that is a percentage of the selected torque;
calculating a first speed at the end of the deceleration ramp that is a percentage of a selected speed;
periodically determining a peak torque applied by the tool;
determining if the peak torque is greater than or equal to the first torque;
stopping the tool, if the peak torque is greater than or equal to the first torque and the selected torque;
determining if the peak torque is greater than or equal to the second torque, if the peak torque is not greater than the first torque; and
calculating parameters descriptive of the deceleration ramp and controlling the speed in accordance with the parameters, if the peak torque is greater than or equal to the second torque.
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Abstract
A method of controlling electric- and fluid-powered torque-applying tools to avoid torque overshoot and unwanted joint stresses. During a fastening operation, a controller monitors the peak torque applied to a joint at specified intervals in time and adjusts the speed of the tool appropriately to reach a programmed torque value without overshooting. The method may be applied to arbitrary types of joints and allows the tool to adapt to the characteristics of a joint while a fastening operation is underway, without a separate “learning” or “adaptation” phase.
121 Citations
31 Claims
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1. A method of controlling a torque applying tool to apply a selected torque by controlling a speed of the torque applying tool, the method comprising:
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calculating a first torque at an end of a deceleration ramp that is a percentage of the selected torque;
calculating a second torque at a start of the deceleration ramp that is a percentage of the selected torque;
calculating a first speed at the end of the deceleration ramp that is a percentage of a selected speed;
periodically determining a peak torque applied by the tool;
determining if the peak torque is greater than or equal to the first torque;
stopping the tool, if the peak torque is greater than or equal to the first torque and the selected torque;
determining if the peak torque is greater than or equal to the second torque, if the peak torque is not greater than the first torque; and
calculating parameters descriptive of the deceleration ramp and controlling the speed in accordance with the parameters, if the peak torque is greater than or equal to the second torque. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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6. The method of claim 5, wherein the coefficient C1 is −
- 0.04, the offset value C2 is 100, the first programmed speed is 501 rpm, the second programmed speed is 2001 rpm and the variable percentage TER % is 20% if the programmed speed SP is greater than 2001 rpm, and the variable percentage TER % is 100% if the programmed speed is less than 501 revolutions per minute.
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7. The method of claim 1, wherein the first speed is a variable percentage of the selected speed.
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8. The method of claim 7, wherein the variable percentage is defined as
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9. The method of claim 8, wherein the R is 0.25 and Z is 7.5.
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10. The method of claim 1, wherein calculating the parameters descriptive of the deceleration ramp includes calculating a slope of the deceleration ramp as
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11. The method of claim 10, wherein the second speed is a current speed of the torque applying tool at the start of the deceleration ramp.
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12. The method of claim 1, wherein controlling the speed in accordance with the parameters includes issuing a speed command to the torque applying tool, the speed command defined as
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13. The method of claim 1 wherein the peak torque is determined every millisecond.
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14. A method of controlling a torque applying tool to apply a selected torque by controlling a speed of the torque applying tool, the method comprising:
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determining a final torque value;
determining a final speed value;
decreasing speed levels until the torque applying tool reaches the final torque value and the final speed value;
periodically measuring the torque level until the final torque value is measured; and
stopping the torque applying tool when the selected torque value is reached.
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15. A torque applying tool that:
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calculates a first torque at an end of a deceleration ramp that is a percentage of a selected torque;
calculates a second torque at a start of the deceleration ramp that is a percentage of the selected torque;
calculates a first speed at the end of the deceleration ramp that is a percentage of a selected speed;
periodically determines a peak torque applied by the tool;
determines if the peak torque is greater than the first torque;
stops the tool, if the peak torque is greater than or equal to the first torque and the selected torque;
determines if the peak torque is greater than or equal to the second torque, if the peak torque is not greater than the first torque; and
calculates parameters descriptive of the deceleration ramp and controls the speed in accordance with the parameters, if the peak torque is greater than or equal to the second torque. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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20. The torque applying tool of claim 19, wherein the coefficient C1 is −
- 0.04, the offset value C2 is 100, the first programmed speed is 501 rpm, the second programmed speed is 2001 rpm and the variable percentage TER % is 20% if the programmed speed SP is greater than 2001 rpm, and the variable percentage TER % is 100% if the programmed speed is less than 501 revolutions per minute.
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21. The torque applying tool of claim 15, wherein the first speed is a variable percentage of the selected speed.
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22. The torque applying tool of claim 21, wherein the variable percentage is defined as
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23. The torque applying tool of claim 22, wherein the R is 0.25 and Z is 7.5.
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24. The torque applying tool of claim 15, wherein calculation of the parameters descriptive of the deceleration ramp includes calculation of a slope of the deceleration ramp as
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25. The torque applying tool of claim 24, wherein the second speed is a current speed of the torque applying tool at the start of the deceleration ramp.
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26. The torque applying tool of claim 15, wherein control of the speed in accordance with the parameters includes issuance of a speed command to the torque applying tool, the speed command defined as
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27. The torque-applying tool of claim 15, wherein the peak torque is determined every millisecond.
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28. The torque applying tool of claim 15, wherein the torque applying tool is an electric torque applying tool.
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29. The torque applying tool of claim 15, wherein the torque applying tool is a hydraulic torque applying tool.
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30. The torque applying tool of claim 15, wherein the torque applying tool is a pneumatic torque applying tool.
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31. A controller for a torque applying tool that:
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calculates a first torque at an end of a deceleration ramp that is a percentage of a selected torque;
calculates a second torque at a start of the deceleration ramp that is a percentage of the selected torque;
calculates a first speed at the end of the deceleration ramp that is a percentage of a selected speed;
periodically determines a peak torque applied by the tool;
determines if the peak torque is greater than the first torque;
stops the tool, if the peak torque is greater than or equal to the first torque and the selected torque;
determines if the peak torque is greater than or equal to the second torque, if the peak torque is not greater than the first torque; and
calculates parameters descriptive of the deceleration ramp and controls the speed in accordance with the parameters, if the peak torque is greater than or equal to the second torque.
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Specification