JP2014124722A - Automatic thread fastening device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic thread fastening device improved in a support structure of a reaction torque associated with thread fastening.SOLUTION: A nut runner 6 for rotationally driving a screw is displaced by sliding in a direction perpendicular to a rotation axis of the nut runner 6 by a slide mechanism 5. The slide mechanism 5 includes a guide rail 25 and a slider 24 guided by the guide rail 25. A guide surface 24A of the slider 24 contacts a top surface 25A of the guide rail 25 so that a reaction torque associated with thread fastening by the nut runner 6 is supported by a wide area. Thus, displacement of the slider 24 caused by the reaction torque can be prevented by a stable supporting structure of the reaction torque.

Description

  The present invention relates to an automatic screw tightening device for tightening screws such as bolts and nuts at an arbitrary tightening position.

  As a method of fixing a vehicle-mounted device to a vehicle body, for example, a method of fixing a unitized device such as an internal combustion engine or a suspension at a predetermined position inside the vehicle body from below the vehicle body and then fixing the vehicle-mounted device to the vehicle body with bolts and nuts is known. It has been.

  The tightening operation of the nut to the bolt is performed using a device called a nut runner. The nut runner is configured to hold the nut at the tip of the rotating shaft of the electric motor and tighten the nut to the bolt by the rotation of the electric motor. Bolts are locked against the equipment in advance.

  The position of the bolt is not uniform depending on the vehicle type. Therefore, various movement mechanisms are used to move the nut runner to the tightening position of the nut.

  For example, it can be considered that the nutrunner is supported by an articulated robot so as to be movable in a three-dimensional direction. Further, as shown in Patent Document 1, it is conceivable that the nutrunner is supported by an arm type robot so as to be movable in a three-dimensional direction. Further, it is conceivable to support the nut runner movably in the three-dimensional direction using an actuator that drives the nut runner in the vertical direction and a biaxial slide mechanism that moves the actuator to an arbitrary position on a horizontal table.

JP 2009-113186 A

  These articulated robots and arm type robots have a problem of high manufacturing costs. The combination of the table type biaxial slide mechanism and the vertical actuator has an advantage that the cost is lower than these.

  By the way, tightening of a nut for fixing a device such as an internal combustion engine or a suspension to a vehicle body is performed with a high torque of 120 to 160 Newton meters (N · m). The counter-torque accompanying this tightening acts on the robot arm and slide mechanism.

  If the robot arm or the slide mechanism is displaced by receiving the counter torque, the positioning of the nut runner by the robot arm or the slide mechanism becomes invalid.

  In order to prevent such a problem from occurring, the robot arm and the slide mechanism are required to have high rigidity so that the nut runner can be held at a predetermined positioning position against the counter torque. In order to satisfy this requirement, it is necessary to increase the size of the entire moving mechanism, and as a result, the manufacturing cost of the moving mechanism increases. This problem also increases the manufacturing cost of the relatively inexpensive table-type two-axis slide mechanism.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an automatic screw tightening device having a slide mechanism that can easily support anti-torque.

  In order to achieve the above object, an automatic screw tightening device according to the present invention includes a nut runner having a rotating shaft that rotationally drives a screw including a nut and a bolt, and a slide mechanism that slides the nut runner in a direction perpendicular to the rotating shaft. It is equipped with.

  The slide mechanism includes a guide rail having a top surface and a slider guided to the guide runner by instructing the nut runner.

  The slider has a guide surface that overlaps the top surface of the guide rail.

  And the direction of a guide rail and a slider is set so that the counter torque accompanying screw tightening operation may be supported by the top surface of a guide rail.

  The guide surface of the slider that overlaps the top surface of the guide rail contacts the top surface of the guide rail over a wide area. The counter-torque accompanying the tightening of the screw is supported on the top surface of the guide rail through this wide contact surface. That is, the anti-torque is dispersed in a wide range and supported stably. Therefore, the position shift of the nut runner due to the counter torque is less likely to occur. Further, the load exerted by the counter torque on the engaging portion between the claw and the guide groove can be kept small.

1 is a perspective view of an automatic screw tightening device according to an embodiment of the present invention. FIG. It is a perspective view of the clamping unit with which the automatic clamping device of a screw is provided. It is a vertical sectional view of the tightening unit viewed from the Y-axis direction. It is a cross-sectional view of the X-axis slide mechanism with which the fastening unit is provided. It is a cross-sectional view of a Y-axis slide mechanism provided in the tightening unit. It is a principal part cross-sectional view of the fastening unit explaining the support structure of the anti-torque of nut fastening. It is a principal part cross-sectional view of the fastening unit which is not based on this invention explaining the support structure of the anti-torque of nut fastening.

  Referring to FIG. 1, an automatic screw tightening device for fixing unitized equipment such as an internal combustion engine and a suspension to a vehicle body includes a nut supply device 3 disposed at the center of a frame 1, and front and rear thereof. And three tightening units 2 arranged in the space.

  The vehicle body is disposed above the frame 1. The device is arranged at a predetermined position in the vehicle body from below the vehicle body. Then, the tightening unit 2 tightens the nut supplied from the nut supply device 3 to the fixing bolt of the device penetrating the fixing member on the vehicle body side. In the figure, the arrow UPR indicates the upper direction, the arrow Fr indicates the front of the vehicle, and the arrow LH indicates the left direction toward the front of the vehicle. As shown in the figure, in the automatic screw tightening device, two tightening units 2 in front of the nut supply device 3 are arranged on the left and right sides, and one tightening unit is also provided behind the nut supply device 3. Unit 2 is arranged.

  Referring to FIG. 2, each tightening unit 2 includes an X-axis slide mechanism 4, a Y-axis slide mechanism 5, an actuator 7, and a nut runner 6 configured on the frame 1.

  The nut runner 6 incorporates an electric motor. The nut runner 6 includes a rotating shaft 6A that is driven to rotate by an electric motor. A nut 9 supplied from the nut supply device 3 is held at the tip of the rotating shaft 6A. The nut runner 6 is driven by the actuator 7 in the Z-axis direction in the figure. The Y-axis slide mechanism 5 slides the actuator 7 in the Y-axis direction in the figure. The X-axis slide mechanism 4 drives the Y-axis slide mechanism 5 in the X-axis direction in the figure. 1 corresponds to the UPR direction in FIG. 1, the Y axis corresponds to the Fr direction in FIG. 1, and the Z axis corresponds to the UPR direction in FIG.

  Next, referring to FIG. 4, the X-axis slide mechanism 4 includes a base 16 fixed to the frame 1, a guide rail 15 extending on the base 16 in the X-axis direction, and a guide rail 15 guided to the X-axis. And a slider 14 that slides in the axial direction.

  The guide rail 15 is formed in a substantially rectangular cross section having a top surface 15A and a pair of side surfaces 15C. Guide grooves 15B are formed in the pair of side surfaces 15C in the X-axis direction.

  The slider 14 includes a guide surface 14A that overlaps the top surface 15A of the guide rail 15, a pair of claws 14B that engage with the guide groove 15B, and a pair of sub guide surfaces that connect the pair of claws 14B and the guide surface 14A. 14C. It is also preferable to engage the claw 14B and the guide groove 15B via a roller bearing.

  The X-axis slide mechanism 4 includes a stepping motor (not shown), and displaces the slider 14 on the guide rail 15 in the X-axis direction according to the operation of the stepping motor.

  Referring to FIG. 3, a bracket 8 that supports the Y-axis slide mechanism 5 on the slider 14 is fixed to the guide surface 14 </ b> A of the slider 14. The bracket 8 includes a horizontal portion 8A and a vertical portion 8B. The horizontal portion 8A is fixed to the guide surface 14A of the slider 14, and the vertical portion 8B supports the Y-axis slide mechanism 5. The Y-axis slide mechanism 5 has substantially the same configuration as the X-axis slide mechanism 4. Roughly, the Y-axis slide mechanism 5 corresponds to the X-axis slide mechanism 4 rotated 90 degrees in the yaw direction and further rotated 90 degrees in the roll direction. In this state, the Y-axis slide mechanism 5 is supported by the X-axis slide mechanism 4 via the bracket 8.

  Referring to FIG. 5, the Y-axis slide mechanism 5 includes a base 26, a guide rail 25, and a slider 24 configured in the same manner as the X-axis slide mechanism 4. The base 26 is fixed to the vertical portion 8B of the bracket 8. The guide rail 25 is fixed to the base 26. The base 26 and the guide rail 25 extend in the Y-axis direction orthogonal to the base 16 and the guide rail 15 of the X-axis slide mechanism 4.

  The guide rail 25 is formed in a substantially rectangular cross section having a top surface 25A and a pair of side surfaces 25C. Guide grooves 25B are respectively formed in the Y-axis direction on the pair of side surfaces 25C.

  The slider 24 includes a guide surface 24A that overlaps the top surface 25A of the guide rail 25, a pair of claws 24B that engage with the guide groove 25B, and a pair of sub-guide surfaces that connect the pair of claws 24B and the guide surface 24A. 24C. It is also preferable to engage the claw 24B and the guide groove 25B via a roller bearing.

  The Y-axis slide mechanism 5 includes a stepping motor (not shown), and displaces the slider 24 on the guide rail 25 in the Y-axis direction according to the operation of the stepping motor.

  With the above configuration, the guide surface 14A of the slider 14 and the top surface 15A of the guide rail 15 are both horizontal surfaces, whereas the guide surface 24A of the slider 24 and the top surface 25A of the guide rail 25 are both vertical surfaces. Become.

  The actuator 7 is fixed to the guide surface 24 </ b> A of the slider 24. The actuator 7 is an actuator that expands and contracts in the Z-axis direction, that is, the vertical direction. A nut runner 6 is supported on the actuator 7.

  One fastening unit 2 configured as described above is arranged on the left and right of the position corresponding to the front of the vehicle in front of the nut supply device 3 of the frame 1. A similar tightening unit 2 is also arranged at a position corresponding to the rear of the vehicle behind the nut supply device 3 of the frame 1.

  The vehicle body is transported above the frame 1 by the transport device. Further, an internal combustion engine, a suspension, and the like to be assembled to the vehicle body are arranged as a device unit at a predetermined position inside the vehicle body by another transport device. Bolts are fixed to the equipment unit in advance, and the tightening unit 2 fastens the nut 9 to the bolt that penetrates the mounting hole provided at a predetermined position of the body.

  A nut 9 is mounted in advance by the nut supply device 3 at the tip of the rotary shaft 6A of the nut runner 6 of the tightening unit 2. In this state, the tightening unit 2 operates the stepping motors of the slide mechanisms 4 and 5 to displace the nut runner 6 to the designated coordinate positions of the X axis and the Y axis.

  When the nut runner 6 reaches a predetermined position, the actuator 7 drives the nut runner 6 to extend, and the nut 9 held at the tip of the rotating shaft 6A is screwed into a downward projecting bolt. And the nut runner 6 fastens the nut 9 to the bolt by rotationally driving the rotating shaft 6A by the operation of the electric motor. The tightening torque at this time is as large as 120 to 160 N · m as described above, and accordingly, a large counter torque acts on the nut runner 6 as the nut 9 is tightened.

  The anti-torque support structure of the tightening unit 2 will be described with reference to FIG. 6A is a cross-sectional view of the Y-axis slide mechanism 5 viewed from the Y-axis direction, and FIG. 6B is a cross-sectional view of the X-axis slide mechanism 4 viewed from the X-axis direction.

  The counter torque associated with the tightening of the nut 9 is indicated by an arcuate arrow around the nut 9 in FIG. This counter torque acts on the slide mechanism 5 via the nut runner 6 and the actuator 7. At this time, it is the guide surface 24 A of the slider 24 that receives the counter torque from the actuator 7, and the counter torque exerts a pitching moment on the slider 24. On the other hand, the slider 24 supports the pitching moment by contacting the top surface 25A of the guide rail 25. At this time, since the guide surface 24A and the top surface 25A overlap with each other over a wide area, the pitching moment does not concentrate on a local area but is dispersed and supported stably over a wide area. Therefore, there is no possibility that the slider 24 is displaced in the Y-axis direction due to the counter torque.

  The counter torque further acts on the X axis slide mechanism 4 via the Y axis slite mechanism 5 and the bracket 8. This counter torque acts on the engaging portion between the claw 14B and the guide groove 15B in FIG. This counter-torque exerts a yaw moment indicated by the arc-shaped arrow in FIG. However, since the counter torque is dispersed in the process of being transmitted to the X-axis slide mechanism 4 via the Y-axis slide mechanism 5, the yaw moment acting on the slider 14 is small. Therefore, a large load does not act on the engaging portion between the claw 14B and the guide groove 15B in FIG.

  In addition, the device load indicated by the straight arrow in FIG. 6A acts vertically on the engaging portion between the upper claw 24B and the guide groove 25B of the Y-axis slide mechanism 5 shown in FIG. However, this vertical load is a small load whose main element is the weight of the nut runner 6 and the actuator 7, and the structural burden on the engaging portion between the claw 24B and the guide groove 25B in FIG. 5 is small.

  On the other hand, on the guide surface 14A of the slider 14 of the X-axis slide mechanism 4, as shown by the straight arrow in FIG. 6B, in addition to the equipment load in FIG. A large gauge load including the weight of the bracket 8 acts vertically. This equipment load is supported at the contact portion between the guide surface 14A of the slider 14 and the top surface 15A of the guide rail 15 shown in FIG. Since the slider 14 and the top surface 15A have a wide contact area as described above, the vertical load is not concentrated on the local portion but is dispersed and supported stably over a wide area.

  Referring to FIG. 7, contrary to the above embodiment of the present invention, the guide surface 14A of the slider 14 of the X-axis slide mechanism 4 and the top surface 15A of the guide rail 15 are vertical surfaces, and the slider of the Y-axis slide mechanism 5 is referred to. The action of the load in the fastening unit 2Z in which the guide surface 24A of 24 and the guide surface 25A of the guide rail 25 are horizontal surfaces will be described. The configuration and arrangement of the nut runner 6 and the actuator 7 are the same as those in the above embodiment.

  In this case, the counter torque of the nut 9 tightened by the nut runner 6 applies a moment load in the yaw direction to the slider 24 via the actuator 7 as shown by the arc-shaped arrow in FIG. This moment load acts intensively on the engaging portion between the claw 24B and the guide groove 25B. As a result, the slider 24 may be displaced, and the tightening unit 2Z may not be able to grasp the current position of the nut runner 6.

  Further, in the X-axis slide mechanism 4, a large device load obtained by adding the weights of the Y-axis slide mechanism 5 and the bracket 8 to the nut runner 6 and the actuator 7 acts on the slider 14 in the vertical direction. Since the guide surface 14A of the slider 14 is a vertical surface, this load is supported by the engaging portion of the upper claw 14B and the guide groove 15B. As a result, a large load acts on the engaging portion between the upper claw 14B and the guide groove 15B.

  In the support structure for the load of the tightening unit 2Z in FIG. 7, each member is required to have high rigidity in order to prevent displacement of the slider 24 due to the counter-torque of the nut 9 and to counter the load acting on each part. . In order to satisfy this requirement, an increase in size of the fastening unit 2Z and an accompanying increase in manufacturing cost are inevitable.

  On the other hand, the tightening unit 2 according to the embodiment of the present invention supports the counter torque associated with the tightening operation of the nut 9 with the top surface 25A of the guide rail 25 of the Y-axis slide mechanism 5, so that the nut 9 can be tightened. The support area of the accompanying anti-torque can be set large, and a stable anti-torque support structure can be realized. Accordingly, it is possible to reduce the size and weight of the tightening unit 2 and the automatic tightening device for the screw on which the tightening unit 2 is mounted and to reduce the cost.

  This feature is that the guide rail 25 of the Y-axis slide mechanism 5 is horizontally disposed so as to be perpendicular to the rotation shaft 6A of the nut runner 6, and the top surface 25A of the guide rail 25 and the guide surface 24A of the slider 24 are connected to the rotation shaft 6A. It can be easily realized by configuring with parallel planes, that is, vertical planes.

  In the tightening unit 2, the guide rail 25 of the Y-axis slide mechanism 5 has a substantially rectangular cross-sectional shape in which a pair of guide grooves 25 </ b> B extending in the direction of sliding displacement of the nut runner 6 is formed on the side surface 25 </ b> C, while the slider 24. Has a claw 24B engaged with the guide groove 25B. Since the top surface 25A supports the counter-torque, the load burden on these engaging portions is reduced, so that these engaging portions can also be made small and simple.

  The actuator 7 that displaces the nut runner 6 in the direction of the rotating shaft 6A is fixed to the guide surface 24A of the slider 24 of the Y-axis slide mechanism 5, so that the counter torque is converted to the guide surface 24A of the slider 24 serving as a support portion of the counter torque. Is transmitted to the contact portion of the guide rail 25 with the top surface 25A at the shortest distance. Therefore, a support structure that is stable against the counter torque can be obtained.

  The tightening unit 2 extends the guide rail 25 of the Y-axis slide mechanism 5 in the horizontal direction with respect to the rotary shaft 6A, which is a vertical axis, and the guide rail 25 is perpendicular to the same plane, that is, in the X-axis direction. The X-axis slide mechanism 4 is provided as another slide mechanism that slides on the X-axis. The above-described configuration of the Y-axis slide mechanism 5 brings about a preferable effect in reducing the load applied to the X-axis slide mechanism 4.

  Further, if a plurality of tightening units 2 are provided on a common frame 1, an inexpensive and structurally stable screw automatic tightening device for fixing a unit such as an internal combustion engine or a suspension to a vehicle body of a vehicle can be provided. Can be configured.

  As described above, the present invention has been described through some specific embodiments. However, the present invention is not limited to the above embodiments. Those skilled in the art can make various modifications or changes to these embodiments within the scope of the claims.

  For example, in the embodiment described above, the tightening unit for tightening the nut has been described. However, the present invention can also be applied to a tightening unit for tightening the bolt.

DESCRIPTION OF SYMBOLS 1 Frame 2 Tightening unit 2Z Tightening unit 3 Nut supply device 4 X axis slide mechanism 5 Y axis slite mechanism 6 Nut runner 6A Rotating shaft 7 Actuator 8 Bracket 8A Horizontal portion 8B Vertical portion 9 Nut 14 Slider 14A Guide surface 14B Claw 14C Sub Guide surface 15 Guide rail 15A Top surface 15B Guide groove 15C Side surface 16 Base 24 Slider 24A Guide surface 24B Claw 24C Sub guide surface 25 Guide rail 25A Top surface 25B Guide groove 25C Side surface 26 Base

Claims (6)

A nut runner having a rotating shaft that rotationally drives a screw including a nut and a bolt, and a slide mechanism that slides and displaces the nut runner in a direction perpendicular to the rotating shaft,
The slide mechanism includes a guide rail having a top surface, and a slider that supports the nut runner and is guided by the guide rail,
The slider has a guide surface overlapping a top surface of the guide rail;
An automatic screw tightening device, wherein directions of the guide rail and the slider are set so that a counter-torque accompanying the tightening operation of the screw is supported by a top surface of the guide rail.   The automatic tightening device for screws according to claim 1, wherein the guide rail is perpendicular to the rotation axis, and the top surface and the guide surface are configured by a plane parallel to the rotation axis.   3. The guide rail according to claim 1, wherein the guide rail has a substantially rectangular cross-sectional shape in which a pair of guide grooves extending in a direction of the slide displacement is formed on a side surface, and the slider has a claw that engages with the guide groove. Automatic screw tightening device.   The automatic tightening device for screws according to any one of claims 1 to 3, wherein the nut runner is supported by the slide mechanism via an actuator that displaces the nut runner in the rotation axis direction.   5. The rotation shaft according to claim 1, wherein the rotation shaft is a vertical shaft, the guide rail extends in a horizontal direction, and further includes another slide mechanism that slides the guide rail in a perpendicular direction on the same plane. Automatic tightening device for either screw.   The automatic screw tightening device according to claim 5, wherein a plurality of tightening units including a plurality of tightening units including the nut runner, the actuator, the slide mechanism, and another slide mechanism in a direction orthogonal to the slide direction are provided on a common frame. .

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