JP2011125957A - Screw part fastening/loosing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a screw part fastening/loosing device capable of achieving work of both fastening and loosing a screw part at high speed with high torque accuracy by one rotation driving source. <P>SOLUTION: A first input shaft 5 driven by an AC servo motor 3 to rotate is provided. A second input shaft 9 is coupled to the first input shaft 5 through an electromagnetic clutch 8. An output shaft 11 to which a screw fastening tool is coupled is provided. The second input shaft is coupled to the output shaft 11, and the first input shaft 5 is through a speed reducer 12 and a tooth clutch 14. Each clutch 8, 14 is controlled according to each step of fastening or loosing of the screw part, thereby switching a state wherein rotations of high speed and low torque are transmitted from the second input shaft 9 to the output shaft 11, and a state wherein rotations of low speed and high torque are transmitted from the first input shaft 5 through the speed reducer 12. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a screw part tightening device for fastening or loosening screw parts.

  Shortening the screw tightening cycle time, that is, speeding up the screw tightening work, is an important issue in tightening the screw parts to the workpiece, and various screw parts fastening machines shown in Patent Documents 1 to 5 are proposed to solve the problem. Has been.

  The screw part fastening machine disclosed in Patent Documents 1 to 4 includes a first drive means for rotationally driving a screw fastening tool at high speed and low torque, and a second drive means for rotationally driving at a low speed and high torque. It has two rotational drive sources. The screw component fastening machine disclosed in Patent Document 1 is configured not to receive the deceleration resistance of the second drive means by utilizing the idling action of the one-way clutch when the first drive means is driven. In addition, in the screw component fastening machine disclosed in Patent Documents 2 to 4, the drive of the first drive means is transmitted to the output shaft or the screw tightening tool by a belt, and the drive of the second drive means is decelerated and increased by the reducer. Only when the electromagnetic clutch is engaged, it can be transmitted to the output shaft or the screw tightening tool. According to these screw parts fastening machines of Patent Documents 1 to 4, it is possible to temporarily fasten at high speed and low torque until the screw parts are seated, and then fasten to the final target tightening torque at low speed and high torque. However, since two rotational drive sources are required, there are problems such as an increase in the size and weight of the apparatus and an increase in power consumption.

  Therefore, a screw component fastening machine has been proposed that can switch between the above-described high-speed / low-torque tightening and low-speed / high-torque tightening with a single rotational drive source, such as Patent Document 5. The screw part fastening machine disclosed in Patent Document 5 is configured to output an input from a drive motor to two systems of an output via a speed reducer and an output not via a speed reducer, and a plurality of one-way clutches on a rotation transmission path. In combination, the high-speed and low-torque output that does not pass through the speed reducer is transmitted to the drive shaft during forward rotation of the motor, and the low-speed and high-torque output that passes through the speed reducer is transmitted to the drive shaft during reverse rotation of the motor. Is.

JP 2004-283948 A JP 2008-6560 A JP 2009-160709 A JP 2009-178823 A JP 2008-114303 A

  According to the screw part fastening machine of Patent Document 5, it is possible to realize the work of screwing at high speed and low torque until the screw part is seated and then tightening to the target tightening torque at low speed and high torque with one rotational drive source. became. However, in this screw component fastening machine, the drive shaft cannot be reversed because the forward / reverse drive of the rotational drive source is used for tightening the screw component. For this reason, there is a problem that the screw tightening tool cannot be reversed, for example, when the screw component head and the screw tightening tool that are generated when the screw component is tightened to the target tightening torque is released. It was. In addition, in order to cope with the loosening work of screw parts, it is necessary to rearrange the fastening machine, such as a one-way clutch reversed configuration, etc. On the site where tightening work and loosening work of screw parts are mixed. There were also problems such as being unable to adapt.

  The present invention has been made in view of the above problems, and provides a screw component tightening device capable of realizing both high-speed and high-precision torque screw component tightening and loosening operations with a single rotational drive source. It is the purpose. In order to achieve this object, the present invention relates to a first input shaft that rotates in response to the drive of a rotary drive source, a second input shaft that is rotatably provided, and the drive of the rotary drive source to the first input shaft. And a first clutch means that switches between a state that can be transmitted to both the second input shaft and a state that cannot be transmitted to the second input shaft, and a predetermined deceleration of the rotation of the first input shaft that is connected to the first input shaft. A reduction gear capable of outputting at a reduced speed, and an output shaft configured to be coupled to a screw tightening tool capable of being engaged with a head of a screw component and configured to be rotatable in response to the rotation of the second input shaft; The second clutch means for switching the output rotation of the speed reducer to the output shaft and the non-transmittable state, and the rotation transmission state by the first clutch means and the second clutch means is during tightening of the screw parts. Or, it becomes a predetermined rotation transmission state for each loosening process Characterized by comprising Yo by a control unit provided for controlling the first clutch means and the second clutch means.

  The control unit controls the first clutch so that the drive of the rotary drive source can be transmitted to the second input shaft in the step of tightening the screw component at a high speed or the step of loosening at a high speed. It is desirable to control the second clutch so that the output rotation of the second clutch cannot be transmitted to the output shaft. Further, the control unit controls the first clutch so that the drive of the rotational drive source cannot be transmitted to the second input shaft in the process of tightening the screw component with high torque or the process of loosening with high torque. It is desirable to control the second clutch means so that the output rotation of the reduction gear can be transmitted to the output shaft. Further, it is preferable that the reduction gear employs a harmonic drive (registered trademark), the first input shaft is connected to a wave generator, and the second clutch means is provided so that an output from the flex spline is transmitted. The first clutch means and the second clutch means are preferably electromagnetic clutches each having an input part and an output part that can be coupled and separated by electromagnetic force.

  With a single rotational drive source, screw parts can be rotated at high speed and low torque until they are seated and screwed at high speed, and after seating, they can be rotated at low speed and high torque to be tightened to the specified tightening torque.・ High precision tightening is possible. Also, after tightening the screw parts that have already been tightened securely while monitoring the torque at low speed and high torque, and after the loosening torque has been reduced, the screw parts can be loosened and removed at high speed with low speed and high torque. Accurate loosening is possible. In this way, the output shaft can be freely rotated at a desired angle, low speed / high torque, high speed / low torque in both the direction of tightening the screw and the direction of loosening the screw. The operation of releasing the fixation by slightly reversing the screw tightening tool fixed to the head of the screw component by tightening the component is also possible. Furthermore, since the above-mentioned effect can be obtained with a motor with a small rated output that can generate a temporary tightening torque with the impact torque when the screw component is seated, a screw component tightening device with low power consumption is realized, There are also advantages such as being able to contribute to energy saving.

It is sectional drawing of the screw component fastening apparatus which concerns on this invention. It is operation | movement explanatory drawing which showed schematic structure of the screw component fastening apparatus which concerns on this invention. It is operation | movement explanatory drawing which showed schematic structure of the screw component fastening apparatus which concerns on this invention.

  In FIG. 1, reference numeral 1 denotes a screw part tightening device for fastening or loosening screw parts such as small screws, bolts, and nuts, and an AC servo motor 3 (hereinafter referred to as an example of a rotational drive source) attached to the case 2. It is simply referred to as a motor 3). A pulley 4 with main driving teeth (hereinafter simply referred to as 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 parallel with the drive shaft 3a and rotatably supported is provided at a lateral position of the motor 3, and the first input shaft 5 includes an upper portion thereof. A pulley 6 with driven teeth (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 first clutch means on the driven pulley 6. The first input shaft 5 is inserted into the electromagnetic clutch 8 and is connected to the first input shaft 5. A solid second input shaft 9 that is rotatably provided is connected.

  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. Become. The coil portion 83 becomes an electromagnet when energized, and is thereby configured to magnetically couple the input portion 81 to the output portion 82. Normally, the coil unit 83 is not energized, and the input unit 81 and the output unit 82 are separated, and the drive of the motor 3 cannot be transmitted to the second input shaft 9, but the coil unit 83 is energized. When the input unit 81 and the output unit 82 are coupled, the drive of the motor 3 can be transmitted to the second input shaft 9.

  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 or a socket for engaging with a screw head and transmitting rotation to the head of the main shaft 112 of the output shaft 11 is directly or variously connected. 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 the wave generator 121 thereof. The speed reducer 12 fixes a circular spline 122 to the case 2 of the main screw component tightening / loosing device 1 and outputs a rotation input by the wave generator 121 by decelerating and reversing the rotation by the flex spline 123 (registered). Trademark) A general structure of use as a reduction gear is adopted. The reduction ratio is 1/30.

  The flexspline 123 of the speed reducer 12 is connected to a hollow cylindrical coupling 13 that is rotatably disposed in the case 2. The coupling 13 is connected to a tooth clutch 14 which is an example of a second clutch means. The tooth 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 portion 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 tooth 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.

  A hollow cylindrical strain generating body 15 is integrally connected to the lower part of the case 2. A strain gauge 16 is affixed to the strain body 15 and is configured to output an electrical signal corresponding to the strain amount of the strain body 15. 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, which controls forward drive and reverse drive by energization control to the motor 3, and controls energization to the coil portions 83 and 143 of the electromagnetic clutch 8 and the tooth clutch 14 to transmit these rotations. It is configured to switch the state, that is, the ON / OFF state of each clutch described later.

  Next, the operation of the present screw component fastening apparatus 1 will be described with reference to FIGS. 2 and 3, the parts painted with light ink indicate the parts that rotate in response to the rotation transmission in each state, and among these, the parts with dark light ink represent the output of the speed reducer 12 (deceleration / boosting force). The rotation part is shown. Moreover, each arrow in a figure shows the rotation direction of each part.

This screw parts tightening / loosening device 1 performs “high-speed tightening” for tightening screw parts at high speed and low torque from the start of screwing to temporary tightening torque, and low and high speeds from temporary tightening torque to final target tightening torque. "High torque tightening" for tightening with torque, "High torque loosening" to loosen the already tightened screw parts at low speed and high torque to the specified loosening torque, and after loosening the high torque, loosen the screw parts at high speed and low torque Each process of “fast loosening” can be performed. Table 1 shows the driving state of the motor 3 and the rotation transmission state of the electromagnetic clutch 8 and the tooth clutch 14 in each step. The term “ON” in Table 1 refers to the state where the coil portion of each clutch is energized and the input portion and the output portion are coupled, and the word “OFF” indicates that the coil portion of each clutch is energized. It refers to the state where the input unit and output unit are separated.

  In the “high-speed tightening” process of the threaded part, as shown in Table 1, the motor 3 is driven in the forward direction, the electromagnetic clutch 8 is turned on, and the tooth clutch 14 is turned off. As shown in FIG. 2A, when the motor 3 is driven to rotate forward, this drive is transmitted to the driven pulley 6 by the main driving pulley 4 and the toothed belt 7, thereby rotating to the first input shaft 5 and the electromagnetic clutch 8. Is transmitted. At this time, since the electromagnetic clutch 8 is ON, the input portion 81 and the output portion 82 can be rotated together. Thereby, the rotation is transmitted to the second input shaft 9 and the first input shaft 5 and the first input shaft 5 are rotated. The two input shaft 9 also rotates forward.

  The wave generator 121 is also rotated forward by the rotation of the first input shaft 5, and the flexspline 123 is decelerated and increased in the opposite direction. At this time, since the tooth clutch 14 is OFF, the deceleration / power increase / reverse rotation output by the speed reducer 12 is not transmitted any further. The rotation of the second input shaft 9 is transmitted to the output shaft 11 or the screw tightening tool. Thus, the rotation transmission system path from the motor 3 to the output shaft 11 in the high-speed tightening process is as follows: motor 3 → primary pulley 4 → driven pulley 6 → electromagnetic clutch 8 → second input shaft 9 → output shaft 11. Since the forward rotation transmitted to the screw tightening tool is a high-speed and low-torque rotation that does not involve the speed reducer 12, the screw component can be screwed into the workpiece at a high speed. Incidentally, the reduction ratio in the rotation transmission path is 1 / 2.4 defined by the diameter difference (tooth difference) between the main pulley 5 and the driven pulley 6.

  The tightening torque while the screw component is tightened is calculated and monitored by the control unit 18 based on the strain amount of the strain generating body 15. That is, the reaction force of the tightening torque of the screw component is transmitted from the output shaft 11 to the case 2 via the first input shaft 5 or the second input shaft 9 and the motor 3. At this time, since the mounting flange 17 is fixed to the arm of the robot or the like, the strain generating body 15 is distorted by the action of the reaction force, and an electric signal corresponding thereto is sent from the strain gauge 16 to the control unit 18. The control unit 18 calculates and monitors the tightening torque from the electrical signal of the strain gauge 16.

  When the screw component is seated on the workpiece, an excessive tightening torque (hereinafter referred to as impact torque) exceeding the target tightening torque due to inertia may momentarily act on the screw component. In such a case, by setting the transmittable torque of the electromagnetic clutch 8 to a torque in a range larger than the temporary tightening torque and smaller than the final tightening torque, the input portion 81 and the output portion 82 are affected by the impact torque. Slip can occur between them. Further, the motor 3 having a small output torque may be selected in advance so that the impact torque generated in the high-speed tightening process is smaller than the target tightening torque. Thus, it is possible to absorb the impact torque and prevent the screw parts from being excessively tightened.

  After the seating, the tightening torque increases, and when this reaches the temporary tightening torque, the process proceeds to the “high torque tightening” process. In the high torque tightening process, as shown in Table 1, the motor 3 is driven in reverse rotation, the electromagnetic clutch 8 is OFF, and the tooth clutch 14 is ON. That is, when the control unit 18 detects that the temporary fastening torque has been reached, the drive of the motor 3 is switched to the reverse drive, the electromagnetic clutch is turned off, and the tooth clutch 14 is turned on.

  Due to the reverse rotation of the motor 3, as shown in FIG. 2B, the rotation output from the speed reducer 12 becomes a positive rotation, and this rotation is transmitted to the output shaft 11 or the screw tightening tool via the tooth clutch 14. . At this time, since the electromagnetic clutch 8 is OFF, the drive of the motor 3 is not transmitted to the second input shaft 9 through this. Therefore, the rotation transmission path to the output shaft 11 is as follows: motor 3 → primary pulley 4 → driven pulley 6 → first input shaft 5 → reduction gear 12 → tooth clutch 14 → output shaft 11. As a result, the output shaft 11 or the screw tightening tool rotates forward at a low speed and a high torque output from the speed reducer 12. For this reason, the screw parts can be securely tightened to the target tightening torque, and overrunning (over-tightening) from when the target tightening torque is detected by the control unit 18 until the drive of the motor 3 stops is also prevented. it can.

  When the control unit 18 detects that the tightening torque has reached the target tightening torque, an operation for separating the screw tightening tool fixed by screw tightening from the head of the screw component is subsequently performed. In this case, the "high torque loosening" process is performed for a short time. In this case, as shown in Table 1, the drive of the motor 3 is switched to the forward rotation drive, but the electromagnetic clutch 8 is OFF and the tooth clutch 14 is Work is performed with the switch ON.

  Since the motor 3 is driven forward and the tooth clutch 14 is ON, the low-speed and high-torque rotation converted to the reverse rotation by the speed reducer 12 causes the output shaft 11 to be screwed as shown in FIG. Is transmitted to the tool. At this time, since the electromagnetic clutch 8 is OFF, the drive of the motor 3 is not transmitted to the second input shaft 9 through this. Therefore, the screw tightening tool rotates in the reverse direction at a low speed and with a high torque and is surely separated from the head of the screw component fixed by the screw tightening. The forward rotation drive time of the motor 3 at this time is set to such an extent that the screw tightening tool can be reversely rotated by a slight angle necessary for releasing the fixation, and the screw parts are not loosened.

  On the other hand, when loosening a screw component that has already been tightened to a workpiece, first, a “high torque loosening” step is performed with the screw tightening tool engaged with the head of the screw component. The state of the motor 3, the electromagnetic clutch 8, and the tooth clutch 14 is the same as that at the time of releasing the fixation of the screw component and the screw tightening tool described above. Can be loosened (see FIG. 3A). At this time, the loosening torque is calculated from the signal of the strain gauge 16 and monitored in the control unit 18 like the tightening torque.

  When the loosening torque is reduced to a predetermined torque, for example, a torque that does not cause slippage between the input portion 81 and the output portion 82 of the electromagnetic clutch 8, a "high-speed loosening" step is subsequently performed. In this high-speed loosening process, as shown in Table 1, the motor 3 is driven in reverse rotation, the electromagnetic clutch 8 is turned on, and the tooth clutch 14 is turned off. As a result, as shown in FIG. 3 (b), the screw tightening tool can be rotated reversely at high speed and low torque, contrary to the high-speed tightening step, and can be loosened to a predetermined loosening torque by the above-described high torque loosening step. Can loosen and unscrew the tapped parts at high speed.

  As described above, when tightening a screw component to a workpiece, the present screw component tightening / loosening device 1 screws the screw component at a high speed and a low torque until the temporary tightening torque is reached, and then reaches the target tightening torque. Can be tightened at low speed and high torque. Further, when loosening a screw component, the screw component can be loosened at a low speed and a high torque until a predetermined loosening torque, and then the screw component can be loosened and unfastened at a high speed and a low torque. For this reason, it becomes possible to achieve both shortening of the cycle time required for tightening or loosening the threaded parts and high-precision tightening torque / loosening torque management. Furthermore, in the present screw component tightening / loosening device 1, even if the rated output of the motor 3 is small, it is possible to generate a temporary tightening torque at the time of tightening by using the impact torque, and the speed reducer 12 is used. Thus, it is possible to generate the target tightening torque and the torque necessary to loosen the screw parts. Therefore, it is possible to reduce power consumption of the motor 3 and contribute to energy saving.

The speed reducer 12 may employ another speed reducing mechanism such as a planetary gear mechanism, or may be a speed reducer in which the rotation output with respect to the input rotation is the rotation in the same direction. . For example, let us assume a case where a speed reducer that outputs a rotation in the same direction as the rotation transmitted from the first input shaft 5 in the above configuration is used. Table 2 shows the driving state of the motor 3 and the rotation transmission state of the electromagnetic clutch 8 and the tooth clutch 14 for each process.
As shown in Table 2, operations similar to those described above are performed in both the high-speed tightening and high-speed loosening processes of the screw parts. Further, in high torque tightening and high torque loosening of screw parts, it is only necessary to drive the motor 3 in the opposite direction to that described above. That is, the motor 3 may be normally driven in the high torque tightening step, and the motor 3 may be reversely driven in the high torque loosening step. Even when such a reduction gear is used, the obtained effect is the same.

DESCRIPTION OF SYMBOLS 1 Thread part locking / unlocking device 2 Case 3 AC servo motor 4 Pulley with driven teeth 5 First input shaft 6 Pulley with driven teeth 7 Belt with teeth 8 Electromagnetic clutch 9 Second input shaft 11 Output shaft 12 Reducer 13 Coupling 14 Two Scratch 15 strain generating body 16 strain gauge 17 mounting flange 18 control unit

Claims (5)

A first input shaft that rotates in response to the drive of a rotational drive source;
A second input shaft rotatably provided;
First clutch means for switching between a state in which the drive of the rotational drive source can be transmitted to both the first input shaft and the second input shaft and a state in which the drive to the second input shaft cannot be transmitted;
A speed reducer coupled to the first input shaft and capable of outputting by reducing the rotation of the first input shaft at a predetermined reduction ratio;
A screw tightening tool that can be engaged with the head of the screw component, and an output shaft configured to be rotatable in response to the rotation of the second input shaft;
Second clutch means for switching the output rotation of the speed reducer to a state in which the output rotation can be transmitted to the output shaft and a state in which the output rotation cannot be performed;
A control unit for controlling the first clutch means and the second clutch means so that the rotation transmission state by the first clutch means and the second clutch means becomes a predetermined rotation transmission state every time the screw part is being tightened or loosened; And a screw part tightening device.   The control unit controls the first clutch so that the drive of the rotational drive source can be transmitted to the second input shaft in the process of tightening the screw parts at a high speed or the process of loosening at a high speed. The screw part tightening device according to claim 1, wherein the second clutch is controlled in a state in which the second clutch cannot be transmitted to the output shaft.   The control unit controls the first clutch so that the drive of the rotational drive source cannot be transmitted to the second input shaft in the process of tightening the screw component with high torque or the process of loosening with high torque. The screw part tightening device according to claim 1 or 2, wherein the second clutch means is controlled so that the output rotation of the second clutch means can be transmitted to the output shaft.   2. The reduction gear according to claim 1, wherein the reduction gear is a harmonic drive (registered trademark), the first input shaft is connected to a wave generator, and the second clutch means is provided to transmit an output from the flexspline. The screw component tightening / loosing device according to claim 3.   The first clutch means and the second clutch means are electromagnetic clutches each having an input part and an output part that can be coupled / separated by electromagnetic force. Screw parts tightening device.