JP2012121125A - Screw part fastener - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screw part fastener smoothly switching a transmission system by a toothed clutch.SOLUTION: The screw part fastener 1 includes: an output shaft 11 having a driver bit at an end; a high-speed low-torque transmission system connected to a motor 3 and transmitting the high-speed low-torque drive to the output shaft 11; a low-speed high-torque transmission system connected to the motor 3 via a reducer 12 and transmitting the low-speed high torque drive to the output shaft 11; the toothed clutch 14 having an input part 141 and an output part 142 formed of tooth parts 141a, 142a and configured to be switchable of the transmission systems by meshing of the tooth parts 141a, 142a by connecting the transmission systems to the input part 141 and output part 142 respectively; and cross roller bearings 10a, 10b rotatably supporting the toothed clutch 14.

Description

  The present invention relates to a screw component fastening machine that temporarily tightens a screw component at high speed and low torque and then performs final tightening at a low speed and high torque.

  Conventionally, as a screw tightening machine belonging to the above technical field, there is one shown in Patent Document 1. This screw tightening machine has a high speed and low torque transmission system by a high speed and low torque drive motor and a low speed and high torque transmission system by a low speed and high torque drive motor. The screw part is configured to be tightened.

JP 2008-006560 A

  However, in the screw tightening machine, since a radial load is applied to each transmission system during the screw tightening process, the meshing of the toothed clutch is hindered, causing a problem in switching the transmission system.

  In view of the above problems, the screw component fastening machine of the present invention transmits an output shaft having a driver bit that engages the head of the screw component at the tip and a rotational drive source to transmit high-speed and low-torque drive to the output shaft. A high-speed low-torque transmission system, a low-speed high-torque transmission system that is connected to a rotational drive source via a speed reduction unit and transmits low-speed high-torque drive to an output shaft, and an input portion and an output portion in which teeth are formed A toothed clutch configured to connect the transmission system to the input part and the output part and to switch the transmission system by meshing the tooth part, and to freely rotate the input part and the output part of the toothed clutch And a cross roller bearing to be supported.

  According to the screw component fastening machine of the present invention, since the toothed clutch is supported by the high-rigidity cross roller bearing, when the transmission system is switched, the engagement of the clutch means acts on the output shaft or the transmission system. Not disturbed by radial load. For this reason, the transmission system can be switched reliably, and the fastening failure of the screw parts due to the transmission system switching failure does not occur. In addition, since one cross roller bearing can obtain the same rigidity as that provided with two cylindrical roller bearings, the number of parts is reduced, and a small screw part fastening machine can be provided.

It is sectional drawing which shows the screw component fastening machine of this invention. It is the figure which gave thin coating to the high-speed low torque transmission system. It is the figure which gave thin coating to the low-speed high torque transmission system. It is a graph which shows drive control of the screw component fastening machine of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes a screw part fastening machine for fastening or loosening screw parts such as screws, bolts, and nuts, and an AC servo motor 3 (hereinafter simply referred to as a motor) that is an example of a rotational drive source attached to the case 2. 3). A resolver 3b is assembled to the motor 3 so that the rotation angle of the drive shaft 3a of the motor 3 can be detected.

  A pulley 4 with a main driving tooth (hereinafter simply referred to as a main driving pulley 4) is connected to the drive shaft 3a of the motor 3 so as to be integrally rotatable. A horizontal cylindrical first input shaft 5 extending in a direction parallel to the drive shaft 3a and rotatably supported by the hollow shaft is provided at a lateral position of the motor 3, and the first input shaft 5 includes An upper driven toothed pulley 6 (hereinafter referred to as a single driven pulley 6) is integrally connected. An endless toothed belt 7 is wound and meshed with the driven pulley 6 and the main driving pulley 4 so that the drive of the motor 3 can be transmitted to the first input shaft 5. Further, an electromagnetic clutch 8 is provided as an example of clutch means on the driven pulley 6. The electromagnetic clutch 8 is inserted into the first input shaft 5 and is rotated with respect to the first input shaft 5. The solid 2nd input shaft 9 provided so that it was possible was connected. The number of teeth of the main pulley 4 and the driven pulley 6 is different, and the reduction ratio is 1 / 2.4. This is preliminarily set to obtain a sufficient torque even for a motor with a low output torque, and there is no problem even if the number of teeth is the same and the speed is not increased or decreased.

  The electromagnetic clutch 8 includes an input unit 81 that is rotatably connected to the driven pulley 6, an output unit 82 that is rotatably connected to the second input shaft 9, and a coil unit 83. Yes. The coil portion 83 becomes an electromagnet when energized, and is configured so that the input portion 81 can be magnetically coupled to the output shaft 82. Normally, the coil unit 83 is not energized, and the input unit 81 and the output unit 82 are separated so that the drive of the motor cannot be transmitted to the second input shaft 9. If 81 and the output part 82 couple | bond together, it will be in the state which can transmit the drive of the motor 3 to the 2nd input shaft 9. FIG.

  The second input shaft 9 extends through the first input shaft 5, and an output shaft 11 is connected to the tip of the second input shaft 9. The output shaft 11 is integrated with the transmission shaft portion 111 by inserting and engaging the transmission shaft portion 111 connected to the second input shaft 9 and the spline shaft portion 112a in the spline hole portion 111a at the tip of the transmission shaft portion 111. The main body shaft portion 112 is rotatably connected to the main body shaft portion 112. A screw tightening tool (not shown) such as a driver bit and a socket for engaging with the head of a screw component and transmitting rotation to the head is directly or variously connected to the tip of the main body shaft portion 112 of the output shaft 11. It is connected through.

  The tip of the first input shaft 5 is connected to the speed reducer 12. The speed reducer 12 is generally known as a harmonic drive (registered trademark), and the first input shaft 5 is connected to these wave generators 121. The speed reducer 12 fixes a circular spline 122 to the case 2 of the main screw component fastening machine 1 and outputs a rotation input by the wave generator 121 by decelerating and reversing the rotation by the flex spline 123 (registered trademark). ) The general structure of use as a reducer is adopted. The reduction ratio is 1/30.

  The flexspline 123 of the speed reducer 12 is connected to a coupling 13 that is rotatably disposed in the case 2. This coupling 13 is connected to a toothed clutch 14.

  The toothed clutch 14 includes an input portion 141 that is rotatably connected to the coupling 13, an output portion 142 that is rotatably connected to the transmission shaft 111 of the output shaft 11, and the output portion. 142 is an electromagnetic clutch having an urging means (not shown) for urging so that 142 and the input part 141 are always separated from each other, and a coil part 143 fixed to the case 2. The input part 141 and the output part 142 have a configuration in which opposing surfaces are formed into an annular disk surface, and tooth parts 141a and 142a are formed at the peripheral edge thereof, and are generated by energization of the coil part 143. The teeth 141a and 142a are engaged with each other by electromagnetic force so as to be coupled. In the toothed clutch 14, the coil portion 143 is not energized at all times, and the input portion 141 and the output portion 142 are separated, and the output rotation of the speed reducer 12 cannot be transmitted to the output shaft 11. However, when the coil unit 143 is energized and the input unit 141 and the output unit 142 are coupled, the output rotation of the speed reducer 12 can be transmitted to the output shaft 11.

  The coupling 13 and the transmission shaft 11 are rotatably supported by cross roller bearings 10a and 10b, respectively. That is, the input portion 141 and the output portion 142 of the toothed clutch 14 that are rotatably connected integrally therewith are rotatably supported by known cross roller bearings 10A and 10B.

  Since the cross roller bearings 10a and 10b are excellent in rigidity, the meshing of the toothed clutch 14 is not hindered by the radial load acting on the output shaft 11 or each transmission system when the transmission system is switched. For this reason, the transmission system can be switched reliably, and the fastening failure of the screw parts due to the transmission system switching failure does not occur. In addition, since the cross roller bearings 10a and 10b can obtain the same rigidity as that provided with two cylindrical roller bearings, the number of parts is reduced, and the small screw part fastening machine 1 can be provided.

  A hollow cylindrical strain body 15 is integrally connected to the lower portion of the case 2. A strain gauge 16 connected in a bridge is attached to the strain generating body 15, and an electric signal corresponding to the strain amount of the strain generating body 15 that is distorted according to the rotational load acting on the output shaft 11 is detected as an analog signal. It is configured to The strain-inducing tube 15 and the strain gauge 16 constitute torque detecting means. The lead wire 16a of the strain gauge 16 is connected to the circuit board 16b, and an analog signal is digitally converted on the circuit board 16b and output to the torque detector 18f. The torque detection unit 18f is configured to electrically calculate the rotational load torque acting on the output shaft 11 by receiving and calculating the digital signal with a built-in CPU.

  A mounting flange 17 that can be fixed to an arm (not shown) of a screw tightening robot, a machine base (not shown), or the like is integrally fixed to a lower portion of the strain body 15.

  Reference numeral 18 denotes a control unit that applies an excitation voltage to the control unit 18a, a motor drive unit 18c that drives and controls the motor 3 in response to a command from the control unit 18a, and an output voltage of the resolver 3b. The resolver drive unit 18d for determining the rotation angle from the control unit 18a, the clutch control unit 18b for energizing and controlling the electromagnetic clutch 8 in response to a command from the control unit 18a, and the toothed clutch 14 in response to the command from the control unit 18a. A clutch control unit 18e that controls energization, a storage unit 18i that stores various programs and parameters necessary for driving control of the motor 3, an operation unit 18g that inputs various types of information, and a display unit 18h that displays various types of information Comprising.

  The main screw component fastening machine 1 performs a temporary tightening step of tightening the screw component with high speed and low torque from the start of screwing to seating, and a final tightening step of tightening the seated screw component with low speed and high torque until the tightening is completed.

  In the temporary fastening process, the control unit 18 controls the energization of the clutch control units 18b and 18e to set the electromagnetic clutch 8 to ON and the tooth clutch 14 to OFF. As a result, the drive system is switched to the high speed low torque drive transmission system. This high-speed, low-torque drive transmission system is a portion that is thinly coated in FIG. 2, and includes a main pulley 4, a driven pulley 6, an electromagnetic clutch 8, a second input shaft 9, and an output shaft 11. In this order, the rotational drive of the motor 3 is transmitted to the output shaft 11 without passing through the speed reducer 12. In the temporary tightening process, the first input shaft 5 and the speed reducer 12 connected thereto rotate as the driven pulley 6 rotates. However, when the tooth clutch 14 is OFF, the rotational drive is performed on the output shaft 11. It is configured not to be transmitted to.

  On the other hand, in the final fastening step, the control unit 18 controls energization so that the electromagnetic clutch 8 is turned off and the toothed clutch 14 is turned on. As a result, the drive system is switched from the high speed low torque transmission system to the low speed high torque drive transmission system. This low-speed, high-torque transmission system is a part that is thinly coated in FIG. 3, and includes a main pulley 4, a driven pulley 6, a first input shaft 5, a speed reducer 12, a coupling 13, and a toothed clutch. 14 and the output shaft 11, and the rotational drive of the motor 3 is transmitted to the output shaft 11 via the speed reducer 12 in this order.

  By the way, the harmonic drive which is an example of the speed reducer 12 has the input / output reversely rotated as described above. Therefore, in the final tightening step using the low speed and high torque transmission system, the control unit 18 is configured to rotate the motor 3 in the reverse direction so that the output shaft 11 rotates in the forward direction.

  FIG. 4 shows drive control by the control unit 18 of the main screw component fastening device 1, and is a graph showing the rotational speed and torque of the output shaft 11 in the temporary fastening step and the final fastening step. It should be noted that from the start of screwing to seating, a temporary fastening process is shown, and from the seating to completion of fastening, a final fastening process is shown.

  In the temporary tightening process, at the start of screwing, the control unit 18 drives and controls the motor 3 so that the output shaft 11 rotates at the maximum rotation speed of 2000 rpm. When the screw component is screwed to a predetermined number of turns, the rotational drive source is controlled so as to reduce the rotational speed of the output shaft 11 to a predetermined rotational speed.

  Specifically, the number of turns of the screw component is preset in the storage unit 18 i of the control unit 18. Then, the rotational angle of the rotary shaft 11 is monitored by the resolver driving unit 18d, and when the screw component is screwed in until the position obtained by subtracting two turns from the number of turns required from the start of screwing to the seating, that is, immediately before the seating, the output shaft 11 rotates. The motor 3 is driven and controlled to reduce the number. The rotation speed of the output shaft 11 during deceleration is set to 400 rpm.

  Subsequently, after the speed is reduced to 400 rpm in the temporary tightening process, when the remaining two-turn screw parts are screwed and seated, an impact torque is generated. When the torque detection means detects this impact torque, the control unit 18 controls the energization of the clutch control units 18b and 18e to set the electromagnetic clutch 8 to OFF and the toothed clutch 14 to ON, and also to the characteristics of the harmonic drive. The motor 3 is driven in reverse. As a result, the drive system is switched to the low speed and high torque transmission system, and the process proceeds to the final tightening step.

  In the final tightening step, a threshold corresponding to the rotational load torque acting on the output shaft 11 is set in the storage unit 18 i of the control unit 18. Two threshold values are set. The first threshold value with a low rotational load torque value is set to about 25% of the target tightening torque, while the second threshold value with a high rotational load torque value is the target tightening torque value. Set to about 75%. Each time the rotational load torque reaches these threshold values, the control unit 18 drives and controls the motor 3 so as to reduce the rotational speed of the output shaft 11. When the value detected by the torque detection means reaches the tightening completion torque, the driving of the motor 3 is stopped and the tightening is completed.

  In the screw component fastening machine 1 of the present invention, a harmonic drive which is an example of the speed reducer 12 is incorporated in a low speed and high torque transmission system. The flex drive line 123 of this harmonic drive has a thin cup shape and is configured to be deformed. As a result, misalignment occurs. Moreover, since the first input shaft 5 supported by the wave generator 121 of the speed reducer 12 supports the toothed belt 7 via the driven pulley 6, the first input shaft 5 is pulled by the toothed belt 7. This also causes misalignment. As a result, the meshing of the toothed clutch 14 connected to the flexspline 123 is hindered, and the transmission system cannot be switched at a desired timing.

  The output shaft 11 is connected to the output portion 142 of the toothed clutch. Since an external force acts on the output shaft 11 in the tilting direction during the screwing process of the screw component, misalignment occurs.

Therefore, according to the screw component fastening machine 1 of the present invention, the input portion 141 and the output portion 142 of the toothed clutch 14 are rotatably supported by the cross roller bearings 10a and 10b, so that misalignment does not occur. Therefore, since the meshing of the toothed clutch 14 is not hindered, a transmission system switching problem can be prevented. Therefore, it is possible to switch the transmission system at a desired timing, and there is no occurrence of poor tightening of screw parts.

DESCRIPTION OF SYMBOLS 1 Screw component fastening machine 2 Case 3 Motor 3a Drive shaft 4 Main drive pulley 5 First input shaft 6 Driven pulley 7 Toothed belt 8 Electromagnetic clutch 9 Second input shaft 10a, 10b Cross roller bearing 11 Output shaft 12 Reducer 13 Coupling 14 Toothed clutch 15 Straining body 16 Strain gauge 17 Mounting flange 18 Control unit 18a Control unit 18b Clutch control unit 18c Motor drive unit 18d Resolver drive unit 18e Clutch control unit 18f Torque detection unit 18g Operation unit 18h Display unit 18i Storage unit

Claims (1)

An output shaft having a screwdriver bit at the tip that engages the head of the screw component;
A high-speed low-torque transmission system that connects to a rotary drive source and transmits high-speed low-torque drive to the output shaft;
A low-speed high-torque transmission system that is coupled to a rotational drive source via a speed reduction unit and transmits low-speed high-torque drive to the output shaft;
A toothed clutch having an input part and an output part in which tooth parts are formed, the transmission system being connected to the input part and the output part, respectively, and the transmission system being switchable by meshing of the tooth parts; ,
A cross roller bearing that rotatably supports the input portion and the output portion of the toothed clutch;
A screw component fastening machine comprising: