JP2010284739A - Power transmission device for automatic fastening machine for screw parts - Google Patents

Abstract

A power transmission device in a screw part automatic fastening machine that enables forced reversal of a driver bit after completion of screw part fastening.
A pin member 8 with one end projecting is fixed to one of a rotary coupling body 22 and a fixing member 7 arranged around a drive shaft 2, and the other fixing member 7 or the other fixing member 7 is not fixed. A circular long groove-shaped drive transmission groove 23 extending in the circumferential direction is formed in the rotary coupling body 22, and the pin member 8 is fitted in the drive transmission groove 23, so that the drive shaft 2 and the transmission shaft 6 are blocked from rotating within a predetermined angle range. On the other hand, an electromagnetic clutch 33 that forcibly connects or disconnects low-speed and high-torque rotation is interposed between the rotary connecting member 31 and the transmission shaft 6, and the electromagnetic clutch 33 is in a rotation-blocking state during high-speed and low-torque driving. Therefore, immediately after the final screw tightening is completed, the driver bit is slightly reversed by a predetermined angle, and the bite between the screw and the driver bit is eliminated.
[Selection] Figure 1

Description

  The present invention is an automatic screw part fastening machine that first screws a screw part such as a screw, a bolt or a nut with high speed and low torque rotation, and then fastens the screw part to a workpiece with low speed and high torque up to a preset final fastening torque. In particular, the present invention relates to a power transmission device that eliminates the biting of a driver bit into a drive portion of a screw component that occurs when screw component fastening is completed.

  2. Description of the Related Art Conventionally, well-known screw component fastening machines such as bolts, nuts, and screws are well known in the art in which these screw components are automatically supplied every work cycle and screwed into a workpiece. An example of the screw tightening machine uses a driver bit that can be engaged with a rectangular shaped drive hole such as a cross or a hexagon hole formed on the head of the screw, and this driver bit is connected to an electric driver via a drive shaft. It is the structure connected to. When a screw is screwed into a workpiece with this screw tightener, the electric driver is driven in a state where a driver bit is engaged with a screw driving hole. Thereby, a rotational force is transmitted from the driver bit to the screw, and the screw is fastened to the workpiece.

  Such a screw tightening machine is not often used for screw tightening work where high screw tightening accuracy (fastening torque with little variation) is required. Therefore, as a screw part fastening machine that has been recently used as a part fastening machine having a stable fastening torque, there is a fastening machine as shown in FIG. As shown in Patent Document 1, this is a screw tightening machine in which two of a low-speed high-torque driver 102 and a high-speed low-torque driver 103 are arranged, and after a screw is held in a chuck unit (not shown). The low speed high torque driver 102 and the high speed low torque driver 103 are driven simultaneously. At this time, since the outer ring 121 slips with respect to the inner ring 122 by the one-way clutch 120, the driver bit (not shown) is rotated by the rotation of only the high-speed and low-torque driver 103 via the drive shaft 104, and the screw is turned. Screwed at high speed. In this operation, when the rotational speed of the high speed / low torque driver 103 decreases as the screw is screwed in and decreases below the rotational speed of the low speed / high torque driver 102, the rotation of the low speed / high torque driver 102 is controlled by the action of the one-way clutch 120. It is transmitted to the connected drive shaft 104 and screwed until it reaches the final fastening torque at a low speed.

  Recently, a screw tightening machine as shown in FIG. 7 has also been developed. This is because the drive motor 204 disposed at the rear transmits the rotation from the first rotation transmission path 220 directly connected to the drive shaft 205 located on the extended center line of the motor shaft to transmit the drive shaft 205 at a high speed in the initial stage of screw tightening. Rotate with low torque, temporarily tighten the screw part, and the seating surface of the screw part is seated on the workpiece (not shown). At the same time, the rotation direction of the motor shaft is switched, and the transmission path of the rotational power is changed to change the rotation of the motor shaft. This is a screw tightening machine configured to transmit low-speed and high-torque rotation from a second rotation transmission path 230 disposed around an extended center line (see Patent Document 2). In this screw tightening machine, three-way clutches 211, 221, 231 for interrupting transmission of rotation when the rotation direction of the drive motor 204 for screw tightening is changed are provided at three locations, Thereby, the rotation transmission path is smoothly changed.

JP-A-60-52268 JP 2008-114303 A

  However, all of these component fastening machines can properly obtain a predetermined fastening torque. However, when the final screw tightening is completed, the driver bit remains in the screw drive hole. If the machine tries to rise after the tightening is completed, the workpiece may rise together, leading to product defects. In addition, since a one-way clutch is used in any of these machines, when the drive shaft is reversed by a reaction force caused by twisting of the driver bit at the completion of screw tightening, the reverse rotation is prevented by these clutches. It is difficult to release the screwed state. In addition, when the workpiece is relatively thin as in recent years due to such problems, the workpiece is often damaged when mounting parts automatically, and automation is difficult to progress. Has produced.

  The object of the present invention is to eliminate such problems and fasten the screw parts at high speed and low torque at the beginning of screwing of the screw parts, and fasten the screw parts at low speed and high torque when the screwing is completed, and counteracts by twisting of the driver bit after the fastening is completed. It is to obtain a power transmission device in a screw part automatic fastening machine that enables a slight reverse rotation by force and a forced reverse rotation of a driver bit at the same time.

  An object of the present invention is to connect a rotary connecting body 22 arranged around a drive shaft 2 rotated by a single drive motor 4 capable of rotating in the forward and reverse directions so as to be integrally rotatable at the time of forward rotation and to rotate at the time of reverse rotation. A one-way clutch 21 that cuts off is provided, and the drive shaft 5 is connected to the transmission shaft 6 to which the rotation of the rotary coupling body 22 is transmitted to drive at high speed and low torque. An output speed reduction means that decelerates and rotates in the direction opposite to the rotation direction of the drive shaft 2 is arranged, and the drive shaft 5 is driven at a low speed and a high torque via a rotation connecting member 31 to which the rotation from the output speed reduction means is transmitted. In the screw component automatic fastening machine that is driven, a pin member 8 with one end protruding is fixed to one of the rotary coupling body 22 and the fixing member 7 fixed to the transmission shaft 6. Fixed The other fixed member 7 or the rotary connecting body 22 is formed with a drive transmission groove 23 in the shape of a circular long groove having the same center as that of the rotary connecting body 22 along the circumferential direction. 8, the drive shaft 2 and the transmission shaft 6 are configured to block transmission of rotation within a predetermined angle range, while forcibly connecting or blocking low-speed high-torque rotation from the rotary connecting member 31. The electromagnetic clutch 33 is interposed between the rotary connecting member 31 and the transmission shaft 6, and this is achieved by providing a power transmission device having a configuration in which the electromagnetic clutch 33 is in a rotation cut-off state during high-speed and low-torque driving.

  In order to achieve this object, in the power transmission device, the drive transmission groove is on the turning locus of the pin member 8, and the pin member 8 is capable of turning back and forth while standing on the turning locus. Therefore, the reaction force generated in the drive shaft and the driver bit at the time of screw tightening can be removed immediately after the completion of fastening, and forced reverse rotation is also possible. Furthermore, the electromagnetic clutch in these power transmission devices is connected at low speed and high torque drive and when the driver bit reverses after completion of screw tightening, and is disconnected when high speed and low torque drive is completed. Since the bit is forcibly reversed by a slight angle, the biting between the drive unit and the driver bit is reliably eliminated.

  According to the present invention, one of these members is pinned between the rotary coupling body fixed to the one-way clutch to which the drive shaft is coupled only during forward rotation and the fixed member of the transmission shaft to which the rotation is transmitted. The other member is provided with a drive transmission groove in which the pin member is fitted, and these are fitted together to transmit the rotation, and the screwdriver bit is forcibly reversed by a small angle immediately after the screw tightening is completed. Therefore, when the drive motor is reversed when the final screw tightening is completed, the driver bit is immediately slightly reversed by a predetermined angle, so that the bite between the screw drive part and the driver bit is eliminated, and then the machine rises. However, the work does not reach the driver bit. This eliminates the occurrence of product defects. Further, in a screw tightening machine provided with a one-way clutch in the rotation transmission system, the reverse rotation of the drive shaft after the completion of screw tightening always occurs, so that the screw tightened state can be reliably released. Further, since the drive shaft can be forcibly reversed in a predetermined range as described above, the reliability is improved as compared with the case where the engagement is released only by the reaction force of the driver bit. In addition, when the workpiece is relatively thin as in recent years, the occurrence of damage to the workpiece when the mounting of the parts is automated is eliminated, and a specific effect such as the progress of automation can be obtained.

It is an expanded sectional view showing the important section of the present invention. It is a partial cross section front view showing the whole composition concerning the present invention. It is a principal part expanded sectional view which shows the operation state of the electromagnetic clutch used for this invention, (a) has shown the interruption | blocking state of the electromagnetic clutch, (b) has shown the connection state of the electromagnetic clutch. It is an expansion schematic perspective view which shows the decomposition | disassembly structure of the principal part of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic perspective view which decomposed | disassembled and showed the rotation transmission state of the principal part of this invention to the state just before a combination, (a) shows a high speed low torque rotation transmission state, (b), (c) is low speed high torque rotation. The transmission state is shown, and (d) shows the forced reverse state after completion of the fastening. It is an operation | movement flowchart which shows the operation state of the rotation transmission system which concerns on this invention, (a) shows the high speed low torque rotation transmission state, (b) has shown the low speed high torque rotation transmission state. It is principal part sectional drawing which shows the structure of the prior art example of this invention. It is a block diagram including the principal part cross section which shows another prior art example of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. In FIG. 2, reference numeral 1 denotes a screw component automatic fastening machine that is placed on a lifting platform (not shown) and moves up or down. The screw component automatic fastening machine 1 belt-drives a drive pulley 3 fixed to a drive shaft 2 and can rotate forward and reverse, and a rotation transmission system that transmits rotation from the drive motor 4 to the inside. And a drive shaft 5 that receives rotation from a rotation transmission system. A drive shaft 5 for fixing a driver bit (not shown) is disposed on a central extension line of the drive shaft 2 to which the drive pulley 3 is fixed. Between the drive shaft 2 and the drive shaft 5, a drive shaft 5 is disposed. Two rotation transmission systems are configured. One of the rotation transmission systems is a first rotation transmission system 20 that rotates the drive shaft 5 at high speed and low torque, and the other is a second rotation transmission system 30 that rotates the drive shaft 5 at low speed and high torque. is there.

  As shown in FIG. 1, the first and second rotation transmission systems 20 and 30 have a structure that acts when the drive motor 4 rotates in the forward and reverse directions. The first rotation transmission system 20 includes a drive shaft. When the drive shaft 2 is connected to the tip of the drive shaft 2 to rotate it in the forward direction (clockwise) to transmit the rotation and to rotate in the reverse direction (counterclockwise direction) Is fixed to one of the one-way clutches 21 that disconnects the rotation and cuts off the rotation transmission, and the other one-way clutch 21 is fixed to a cylindrical rotary connecting member 22 having the same center as that of the drive shaft 2. . The rotary connection body 22 is rotatably supported by a hollow rotary connection member 31 constituting a second rotation transmission system 30 supported by the casing 10 so as to be rotatable around the rotation connection body. 22 is concentric with the fixing member 7 fixed so as to be integrated with the transmission shaft 6 disposed on the central extension line of the drive shaft 2.

  A pin member 8, one end of which protrudes on the side facing the rotary connecting body 22, is fixed to the fixing member 7 so as to turn around the center of the fixing member 7, while the fixing member 7 of the rotary connecting body 22 is fixed. A drive transmission groove 23 into which the protruding end of the pin member 8 is fitted is formed on the side opposite to the side. The drive transmission groove 23 has the same center as the rotary coupling body 22 and is formed in a circular long groove shape along the circumferential direction. The rotary coupling body 22 that rotates by receiving the rotation from the drive shaft 2 is the pin member. The rotation is transmitted to the transmission shaft 6 that transmits the rotation to the drive shaft 5 via 8. As shown in FIG. 4, the circumferential length of the drive transmission groove 23 is such that the transmission shaft 6 that integrally fixes the pin member 8 can freely turn by a predetermined rotation angle with respect to the rotary coupling body 22. In this embodiment, when the drive shaft 5 is reversed by a slight angle, the drive shaft 2 is rotated by a large angle by the output reduction means described later, so that the angle range is relatively large around the center of the rotary coupling body 22. Is set to Therefore, the rotation transmission between the drive shaft 2 and the transmission shaft 6 is cut off within the range of this angle, and the rotation is transmitted to the transmission shaft 6 by rotating more than this angle. Further, this angle can be arbitrarily set within the range depending on the reduction ratio of the output reduction means.

  In other words, the drive transmission groove 23 is on the turning locus of the pin member 8 as shown in FIG. 4, and the pin member 8 can move forward and backward along the turning locus in a state where the pin member 8 stands upright on the turning locus. It is formed. In this embodiment, the pin member 8 is fixed to the fixing member 7, and the drive transmission groove 23 into which the pin member 8 is fitted is formed in the rotary coupling body 22. However, these configurations are reversed, that is, the pin member 8 is rotationally coupled. Even if it is fixed to the body 22 and the drive transmission groove 23 is formed on the fixing member 7, the same effect can be obtained.

  The drive shaft 2, the one-way clutch 21, the rotary coupling body 22, and the transmission shaft 6 constitute the first rotation transmission system 20, and the rotation from the first rotation transmission system 20 is the transmission shaft. The drive shaft 5 connected to the motor 6 so as to rotate integrally is transmitted at high speed and low torque.

  On the other hand, in FIG. 2, there is output deceleration means around the intermediate position of the drive shaft 2 as an output reduction means for reducing the rotation of the drive shaft 2 at high speed and low torque with a large reduction ratio and converting the rotation to low speed and high torque. A reduction gear 40 is arranged. The speed reducer 40 has a structure called a Harmonic Drive (registered trademark) speed reduction mechanism, and this means that the rotation of the drive shaft 2 transmitted from the drive motor 4 via the drive pulley 3 is the rotational direction of the drive shaft 2. Is a configuration in which it is converted into a low-speed high-torque rotation in the reverse direction and output. This configuration is disclosed in, for example, Japanese Patent Application Laid-Open No. 58-196349 or Japanese Patent Application Laid-Open No. 59-113342, and is already known prior to the filing of the present invention.

  A generator 41 on the input side of the speed reducer 40 is operated on the drive shaft 2, and the operation of the generator 41 outputs reduced rotation to the flexible gear 42 on the output side of the speed reducer 40. It has become. The output side of the speed reducer 40 is connected to a cylindrical rotary connecting member 31 that is rotatably supported by the casing 10, and the rotary connecting member 31 is connected to or cut off from the low speed high torque rotation. An annular body 32 for transmitting rotation is fixed to the input side of the electromagnetic clutch 33 whose output side is fixed to the transmission shaft 6. As shown in FIG. 1, serrated external teeth 32 a are formed on the outer periphery of the annular body 32. On the other hand, the electromagnetic clutch 33 that forcibly connects or disconnects the low-speed and high-torque rotation from the rotary connection member 31 is interposed between the rotary connection member 31 and the transmission shaft 6, and is shown in FIG. As shown to (a), it is comprised so that rotation of the electromagnetic clutch 33 may be in the interruption | blocking state. That is, an annular inner tooth 32b that engages with the outer teeth 32a and is slidable in the axial direction is formed around the annular body 32, and the transmission shaft is disposed on the outer peripheral side opposite to the annular body 32. A movable clutch member 33c having clutch teeth 33b that can mesh with the clutch teeth 33b of the clutch body 33a fixed to 6 is disposed. The movable clutch member 33c is normally in a state where the clutch teeth 33b are separated from each other by a spring member (not shown) disposed between the movable clutch member 33a and the movable clutch member 33c when an electric signal is input. 33c moves to the clutch body side against the spring member, comes into contact with the clutch body 33a, and the clutch teeth 33b engage with each other.

  Specifically, the engagement of the clutch teeth 33b is connected as shown in FIG. 3B during low-speed and high-torque driving and when the driver bit reverses after completion of screw tightening, and during high-speed and low-torque driving, the rotation is cut off ( This operation control is performed at the time of screw tightening at high speed and low torque, screw tightening at low speed and high torque, and starting the reverse operation of the driver bit when screw tightening is completed. An electric signal is output from the control unit 60 to operate. The drive shaft 2, the speed reducer 40, the rotation connecting member 31, the electromagnetic clutch 33, and the transmission shaft 6 constitute the second rotation transmission system 30, and the rotation from the second rotation transmission system 30 is The drive shaft 5 is transmitted at a low speed and a high torque.

  In the state where the rotation is transmitted from the first rotation transmission system 20 at the time of high-speed low-torque rotation, that is, in the state where the drive shaft 2 is rotating forward, the second rotation transmission system 30 is also transmitted. Although the low speed rotation in the reverse direction is transmitted from the speed reducer 40 as the output speed reduction means, the transmission of the rotation is blocked by the electromagnetic clutch 33, so the low speed rotation to the transmission shaft 6 is blocked. Yes. On the other hand, in a state where the rotation is transmitted from the second rotation transmission system 30, that is, in a state where the drive shaft 2 is reversely rotated, the output from the speed reducer 40 of the second rotation transmission system 30 is forward rotation. The rotation is at a low speed, and this rotation is transmitted to the electromagnetic clutch 33 via the rotation connecting member 31. At this time, the one-way clutch 21 of the first rotation transmission system 20 is in a state in which the reverse rotation from the drive shaft 2 is cut off, so that the low speed and high torque rotation from the second rotation transmission system 30 is applied to the transmission shaft 6. Therefore, the high-speed low-torque rotation is converted into the low-speed high-torque rotation by switching the forward / reverse rotation of the drive shaft 2. Moreover, the first and second rotation transmission systems 20 and 30 are built in the casing 10, and the rotary connection member 31 is rotatably supported by the casing 10. Each of the 22 is rotatably supported.

  Furthermore, a driver bit (not shown) such as a box bit or a cross bit that engages with the head of a screw component (not shown) is connected to the tip of the drive shaft 5, and this driver bit is In response to the rotation transmitted from the first and second rotation transmission systems 20 and 30, the screw component is rotated at a high speed and a low torque at the initial stage of screwing, and at a low speed and a high torque when the screwing is completed.

  In addition, as shown in FIG. 2, a cylindrical strain generating tube 50 covering the drive shaft 5 is fixedly disposed on a spacer 11 fixed to the lower end of the casing 10. The pipe 50 receives a reaction force of the drive shaft 5 generated when a threaded part is seated on a work (not shown) and is fastened with a high torque. The strain pipe 50 is twisted. A strain gauge 51 for detecting a strain corresponding to the twist as an electric signal is attached. A torque sensor is constituted by the strain tube 50 and the strain gauge 51, and the fastening torque is determined by the control unit 60 from the signal of the strain gauge 51, and a predetermined fastening torque is obtained, and from high speed low torque driving to low speed high torque driving. When switching, an operation signal of the electromagnetic clutch 33 is output.

  The drive motor 4 outputs a signal indicating its rotation state, and this signal enters the control unit 60 and is processed together with a signal from the sensor. In addition, the control unit 60 outputs a signal for rotating the drive motor 4 forward and backward, which is a stall state of the drive motor 4 (stall means that the motor shaft of the drive motor 4 is rotated). In this stalled state, a high-speed low-torque drive by forward rotation of the drive motor 4 is switched in response to the signal, and the drive shaft 2 is switched. The rotation is reversed and the drive shaft 5 is transmitted with low speed and high torque drive. In addition, the control unit 60 causes the screw component to be screwed at a high speed by the forward rotation of the drive motor 4 with respect to the final fastening torque set according to the type of the screw component, and the screw component is seated on the workpiece. In this case, the maximum rotational speed of the drive motor 4 is determined so that the generated impact torque does not exceed the final fastening torque.

  Next, the operation of the present invention will be described. In a screw component automatic fastening machine having a screwdriver bit in a state where the screw component is engaged and held, when a start signal is input with the screw component positioned at the work fastening position. As shown in FIG. 6A, the drive motor 4 causes the drive shaft 2 to rotate at high speed in the forward direction, that is, in the clockwise direction that is the screwing direction (the direction of arrow (A) in FIG. 5A). At this time, the one-way clutch 21 is connected to the drive shaft 5 so that the drive shaft 2, the rotary connecting body 22, the transmission shaft 6 and the drive shaft 5 rotate together. In this rotation, the pin member 8 fitted in the drive transmission groove 23 of the rotary coupling body 22 is engaged with the drive transmission groove 23 to transmit the rotation to the transmission shaft 6 as shown in FIG. . On the other hand, as shown on the right side of FIG. 6 (a), the speed reducer 40 is also rotated by this rotation, and the reverse rotation direction, that is, the low-speed rotation in the counterclockwise direction (the arrow (b) direction in FIG. 5 (a)). The output is decelerated at 40, but since the meshing of the electromagnetic clutch 33 is disengaged, transmission of low-speed rotation to the transmission shaft 6 is interrupted. As a result, the drive shaft 5 rotates at high speed and low torque without receiving any resistance, the rotation is transmitted to the driver bit, and the screw part is screwed into the work (not shown) at high speed and low torque.

  In this way, when the screw component is screwed in at a high speed and the screw component is seated on the work, the drive motor 4 is in a stalled state, and a signal for starting reverse rotation is input to the drive motor 4 from the control unit 60, and FIG. As shown in b), the drive shaft 2 rotates at high speed in the reverse direction, that is, in the counterclockwise direction due to the reverse rotation of the motor shaft of the drive motor 4. For this reason, the one-way clutch 21 is idled and the rotation is cut off, and the transmission shaft 6 is cut off from the high-speed reverse rotation. On the other hand, since the speed reducer 40 is connected to the drive shaft 2, the reverse rotation of the drive shaft 2 is output as a forward rotation that is decelerated from the output side of the speed reducer 40, that is, a clockwise low-speed rotation. The rotation connecting member 31 is transmitted to the movable clutch member 33c of the electromagnetic clutch 33. Further, the electromagnetic clutch 33 is engaged with each other by the signal from the control unit 60, so that the rotation from the rotary connecting member 31 is transmitted from the transmission shaft 6 to the drive shaft 5 as a low-speed high-torque forward rotation. Is done. In this rotation, as shown in FIGS. 5B and 5C, the rotation of the pin member 8 engaged with the drive transmission groove 23 is not transmitted from the rotation coupling body 22, and the rotation connection member 31 Is transmitted to the transmission shaft 6 via the electromagnetic clutch 33.

  When the fastening torque reaches the final fastening torque set to a predetermined value by the torque sensor during the rotation of the low speed and high torque, as shown in FIG. The drive shaft 2 that receives the rotation of the rotation rotates in the direction of the arrow (A) (clockwise rotation). At the same time, the driver bit slightly reverses (counterclockwise rotation) due to the twist generated in the driver bit and the drive shaft 5. The rotation of the driver bit generated by combining the clockwise rotation and the twisting reaction force of the drive motor 4 is possible because the drive shaft 5 is inserted into the drive transmission groove 23 in which the pin member 8 is fitted. This is because there is no wall of the groove 23 in the reverse rotation direction, that is, there is play, and the drive shaft 5 reverses by this play, so that the reduction ratio of the speed reducer 40 is 1:50, for example. Then, the rotation is reversed by 1/50 of the formation angle range of the drive transmission groove 23 formed in the circumferential direction, and the biting of the driver bit into the drive hole of the screw part is reliably eliminated. Thus, the reverse rotation range can be set according to the magnitude of the reduction ratio.

  In the fastening operation of the screw parts, since the stall state by the drive motor 4 is driven and controlled by the control unit 60 so as to be generated with an impact torque lower than the final fastening torque, the inertia in the drive motor 4 is small. The final fastening torque can be accurately obtained by the reverse drive of the drive motor 4. Therefore, the fastening operation from the start of screwing in the forward rotation of the drive motor 4 to the seating on the work can be performed at a high speed.

  On the other hand, when the screw part is seated on the workpiece by the high-speed and low-torque screwing operation with the drive motor 4, the control unit 60 reverses the drive motor 4 until the final fastening torque is reached. The stalling state is detected and the drive motor 4 is controlled, and it is determined whether or not the screw component is seated and the final fastening torque is reached. Thus, the fastening operation can be comprehensively controlled by transmitting and receiving signals from the drive motor 4 and the torque sensor to and from the control unit 60, and the screw parts can be fastened efficiently. After this, when the fastening work cycle of the screw parts is completed, the process enters a standby state until the next work cycle. When the next start signal is input again, the above fastening operation is repeated.

  In this embodiment, the forward direction is shown as a clockwise direction, and the reverse direction is shown as a counterclockwise direction. However, the forward direction may be taken as a counterclockwise direction, and the reverse direction may be taken as a clockwise direction. The screw is a right-handed screw, which is shown from the fact that the screwing direction seen from above is regarded as the positive direction, and it is easy to understand that the left-handed screw is the opposite. .

  According to the present invention, when screw parts are fastened, a screwing operation with a preset fastening torque can be accurately obtained without causing screw floating, and the biting of the driver bit into the drive part of the screw parts is released. It is suitable for.

DESCRIPTION OF SYMBOLS 1 Screw component automatic fastening machine 2 Drive shaft 3 Drive pulley 4 Drive motor 5 Drive shaft 6 Transmission shaft 7 Fixed member 8 Pin member 10 Casing 11 Spacer 20 First rotation transmission system 21 One-way clutch 22 Rotation coupling body 23 Drive transmission groove DESCRIPTION OF SYMBOLS 30 2nd rotation transmission system 31 Rotation connection member 32 Annular body 32a External tooth 32b Internal tooth 33 Electromagnetic clutch 33a Clutch main body 33b Clutch tooth 33c Movable clutch member 40 Reducer 41 Generator 42 Flexible gear 50 Strain tube 51 Strain gauge 60 Control Part

Claims (3)

A one-way clutch 21 is connected to a drive shaft 2 that is rotated by a single drive motor 4 capable of rotating in the forward and reverse directions so that a rotary connecting body 22 disposed around the drive shaft 2 can rotate integrally during forward rotation and is blocked during reverse rotation. The drive shaft 5 is connected to the transmission shaft 6 to which the rotation of the rotary coupling body 22 is transmitted, and the drive shaft 2 is driven at high speed and low torque, and the rotation direction is reduced around the drive shaft 2. A screw component in which an output speed reduction means that rotates in the direction opposite to the rotation direction of the drive shaft 2 is arranged, and the drive shaft is driven at a low speed and a high torque via a rotary connection member 31 to which the rotation from the output speed reduction means is transmitted. In automatic fastening machine,
A pin member 8 with one end protruding is fixed to one of the rotation coupling body and the fixing member 7 fixed to the transmission shaft, and the other rotation fixing body or rotation coupling body to which the pin member is not fixed is rotated. A drive transmission groove 23 having a circular long groove shape having the same center as that of the coupling body and extending in the circumferential direction is formed. The pin member is fitted into the drive transmission groove, and the drive shaft and the transmission shaft are within a predetermined angle range. On the other hand, an electromagnetic clutch 33 for forcibly connecting or blocking low-speed high-torque rotation from the rotary connecting member is interposed between the rotary connecting member and the transmission shaft so as to cut off the transmission of rotation. A power transmission device characterized in that the electromagnetic clutch is in a rotation cut-off state during driving.   2. The drive transmission groove is on a turning locus of the pin member, and the pin member is formed to have a length capable of turning in the front-rear direction while standing on the turning locus. The power transmission device described.   3. The power transmission device according to claim 1, wherein the electromagnetic clutch is connected when driving at low speed and high torque and when the driver bit reverses after completion of screw tightening, and is disconnected when driving at high speed and low torque.

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