Control method and control unit for impact type screw fastening device
First Claim
Patent Images
1. A control method for an impact type screw fastening device using an electric motor as a rotation driving source, the control method comprising the steps of:
- driving the motor to rotate by supplying thereto pulse current having a rectangular waveform with a flat peak and a predetermined period so that a speed of the motor becomes an intermittent waveform corresponding to the pulse current in a time axis and, at the same time, torque exerted on a load by rotation of the motor becomes pulse torque corresponding to the pulse current and increases pulse by pulse in succession in the time axis;
in a first stage until the pulse torque reaches a first set value, controlling the pulse current so that the pulse torque increases pulse by pulse in succession in increments of a first torque value; and
in a second stage starting from when the pulse torque reaches the first set value and until the pulse torque reaches a second set value, controlling the pulse current so that the pulse torque increases pulse by pulse in succession in increments of a second torque value that is smaller than the first torque value.
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Abstract
An object is to improve accuracy of tightening torque and to shorten time necessary for fastening a screw in an impact type screw fastening device that uses an electric motor as a rotation driving source. A control method for the impact type screw fastening device that uses an electric motor as a rotation driving source includes the steps of driving the motor to rotate by supplying current to the motor intermittently so that torque exerted on a load by rotation of the motor becomes like pulses on the time axis, and controlling the current of every time of each pulse so that an increment of every time of each pulse of the torque after the torque reaches a target approach torque TQN that is a first set value becomes smaller than that before it reaches the target approach torque TQN.
863 Citations
17 Claims
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1. A control method for an impact type screw fastening device using an electric motor as a rotation driving source, the control method comprising the steps of:
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driving the motor to rotate by supplying thereto pulse current having a rectangular waveform with a flat peak and a predetermined period so that a speed of the motor becomes an intermittent waveform corresponding to the pulse current in a time axis and, at the same time, torque exerted on a load by rotation of the motor becomes pulse torque corresponding to the pulse current and increases pulse by pulse in succession in the time axis; in a first stage until the pulse torque reaches a first set value, controlling the pulse current so that the pulse torque increases pulse by pulse in succession in increments of a first torque value; and in a second stage starting from when the pulse torque reaches the first set value and until the pulse torque reaches a second set value, controlling the pulse current so that the pulse torque increases pulse by pulse in succession in increments of a second torque value that is smaller than the first torque value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A control unit for an impact type screw fastening device using an electric motor as a rotation driving source, the control unit comprising:
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a pulse driving portion that drives the motor to rotate by supplying thereto pulse current having a rectangular waveform with a flat peak and a predetermined period so that a speed of the motor becomes an intermittent waveform corresponding to the pulse current in a time axis and, at the same time, torque exerted on a load by rotation of the motor becomes pulse torque corresponding to the pulse current and increases pulse by pulse in succession in the time axis; and a pulse control portion that controls the pulse current, in a first stage until the pulse torque reaches a first set value, so that the pulse torque increases pulse by pulse in succession in increments of a first torque value, and controls the pulse current, in a second stage starting from when the pulse torque reaches the first set value and until the pulse torque reaches a second set value, so that the pulse torque increases pulse by pulse in succession in increments of a second torque value that is smaller than the first torque value. - View Dependent Claims (14, 15)
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16. A control unit for an impact type screw fastening device using an electric motor as a rotation driving source, the control unit comprising:
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a torque detecting portion that detects tightening torque of a screw by the motor; a setting portion that sets a first set value and a second set value with respect to the tightening torque; a pulse driving portion that drives the motor to rotate by supplying thereto pulse current having a rectangular waveform with a flat peak and a predetermined period so that a speed of the motor becomes an intermittent waveform corresponding to the pulse current in a time axis and, at the same time, torque exerted on a load by rotation of the motor becomes pulse torque corresponding to the pulse current and increases pulse by pulse in succession in the time axis; a pulse control portion that controls the pulse current, in a first stage until the pulse torque reaches a first set value so that the pulse torque increases pulse by pulse in succession in increments of a first torque value, and controls the pulse current, in a second stage starting from when the pulse torque reaches the first set value and until the pulse torque reaches a second set value, so that the pulse torque increases pulse by pulse in succession in increments of a second torque value that is smaller than the first torque value; and a stop control portion that stops supply of the pulse current to the motor when the tightening torque reaches the second set value.
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17. A screw fastening device comprising:
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a screw fastening device main body that uses an electric motor as a rotation driving source; a torque detecting portion that detects tightening torque of a screw by the motor; a setting portion that sets a first set value and a second set value with respect to the tightening torque; a pulse driving portion that drives the motor to rotate by supplying thereto pulse current having a rectangular waveform with a flat peak and a predetermined period so that a speed of the motor becomes an intermittent waveform corresponding to the pulse current in a time axis and, at the same time, torque exerted on a load by rotation of the motor becomes pulse torque corresponding to the pulse current and increases pulse by pulse in succession in the time axis; a pulse control portion that controls the pulse current, in a first stage until the pulse torque reaches a first set value, so that the pulse torque increases pulse by pulse in succession in increments of a first torque value, and controls the pulse current, in a second stage starting from when the pulse torque reaches the first set value and until the pulse torque reaches a second set value, so that the pulse torque increases pulse by pulse in succession in increments of a second torque value that is smaller than the first torque value; and a stop control portion that stops supply of the pulse current to the motor when the tightening torque reaches the second set value.
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Specification
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Current AssigneeEstic Corporation
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Original AssigneeEstic Corporation, Honda Motor Co., Ltd. (Honda Motor Company)
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InventorsTakamura, Hitoshi, Shibata, Yoshitsugu, Ito, Takaya
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Primary Examiner(s)Smith; Scott A.
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Application NumberUS11/920,162Publication NumberTime in Patent Office1,553 DaysField of Search173/1, 173/2, 173/176, 173/179, 173/180, 173/181, 173/183, 738/622.3, 738/623.38, 318/432, 318/434, 318/811US Class Current173/1CPC Class CodesB23P 19/066 by electrical meansB25B 23/1405 for impact wrenches or scre...B25B 23/1475 for impact wrenches or scre...
