JP2012240172A - Nut runner and pressing force control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and surely achieve the pressing force control of a nut runner, which can prevent troubles such as galling or socket removal during fastening work.SOLUTION: Movement of a socket 12 in an axial direction with respect to a rotary part 16 is generated by expansion and contraction of a magnetic spring M, and the pressing force F of a nut runner 24 is appropriately controlled with respect to the progress of fastening work. The socket 14 and the rotary part 16 are held by a holding part 18 in such a manner that the relative movement range of the socket 14 and the rotary part 16 falls within a range where the pressing force of the expansion and contraction stroke of the magnetic spring M is constant, the pressing force F of the nut runner 24 is controlled constant irrespective of the elapsed time of the fastening work. At the initial stage of the fastening work, the pressing force F is set to a level preventing galling caused by the excessive pressing force of the nut runner, and thus a galling trouble is prevented.

Description

  The present invention relates to a nut runner and a method for controlling the pressing force of the nut runner.

  Conventionally, various techniques have been proposed for the purpose of controlling a pressing force of a nut runner used in a bolt tightening process to be constant or arbitrary. For example, there is a method of controlling the pressing force by feeding back the screw amount of the nut runner, the applied pressure, or the like (for example, see Patent Documents 1 to 3).

Japanese Patent Laid-Open No. 02-284833 Japanese Patent Laid-Open No. 06-008074 Japanese Patent Laid-Open No. 06-328329

  However, as described above, the method of feeding back the measured value obtained in the bolt tightening process to the pressing force of the nut runner has a complicated apparatus configuration, and it is desired to realize a simpler and more reliable control of the pressing force of the nut runner. . FIG. 7 shows a conventional nutrunner having a simple device configuration. The nut runner 10 includes a socket 14 that engages with the head of the bolt 12 and a rotating portion 16 that engages the socket 14 so as to be relatively movable in the axial direction. Furthermore, the holding part 18 which consists of a cylindrical member for hold | maintaining the socket 14 and the rotation part 16 so that rotation is possible and the socket 14 is slidable is provided.

  In the nut runner 10 of FIG. 7, the socket 14 has a recess 14 that engages with the bolt 12 at the tip 14 a. The rotating portion 16 is directly connected to the rotating shaft of the motor and rotationally drives the socket 14. In the illustrated example, the engaging portion 16a that is slidably engaged with the socket 14 has a rectangular cross section. ing. Further, the engagement concave portion 14b of the socket 14 with the engagement portion 16a also has a rectangular cross-sectional shape following the engagement portion 16a. The socket 14 and the rotating portion 16 are prevented from rotating together, so that they can move relative to each other in the axial direction, and the socket 14 is rotationally driven by the rotating portion 16. Further, a coil spring 20 is disposed between the annular flange formed at the proximal end portion 14 c of the socket 14 and the annular flange formed at the intermediate portion 16 b of the rotating portion 16. Further, the inner cylinder portion of the holding portion 18 is rotatable and slid in the axial direction with a small-diameter portion 18a that rotatably holds the outer peripheral surface of the socket 14 and an annular flange formed on the base end portion 14c of the socket 14. And a large diameter portion 18b for guiding. 7 is a housing of a motor that drives the rotating unit 16, and the holding unit 18 is fixed to the housing 22.

  In this nut runner 10, the coil spring 20 is in a contracted state at the initial stage of the tightening operation of the bolt 12 shown in FIG. 7A, and the pressing force F of the nut runner 10 is shown in FIG. 8A. Will grow. Further, as the tightening operation time T elapses, the tightening of the bolt 12 proceeds and proceeds in the axial direction, so that the coil spring 20 extends as shown in FIG. 7B. As the coil spring 20 extends, the pressing force F of the nut runner 10 decreases as shown in FIG. Therefore, the pressing force F of the nut runner 10 ideally decreases linearly as shown by the solid line in FIG. 8A with the passage of time T of the tightening and attaching operation, and actually shown by the dotted line. It decreases with a slight fluctuation.

By the way, as shown in FIG. 8B, the occurrence frequency Of of the bolts 12 in the tightening operation is high in the occurrence of galling A at the beginning of tightening. The frequency of occurrence tends to increase. Here, the cause of the occurrence of galling is that the pressing force F of the nut runner 10 is excessive in the initial stage of the tightening operation. Also, the removal of the socket is caused by the fact that the pressing force F of the nut runner 10 is insufficient as the tightening operation proceeds. However, the pressing force F of the conventional nutrunner 10 shown in FIG. 7 is large at the initial stage of tightening as shown in FIG. 8 (a), and becomes smaller as the tightening operation time T elapses. It becomes easy to induce both of the sockets coming off.
The present invention has been made in view of the above problems, and the object of the present invention is to provide a simple and reliable control of the pressing force of the nutrunner that can prevent the occurrence of defects during tightening work such as galling or socket disconnection. To be realized.

(Aspect of the Invention)
The following aspects of the present invention exemplify the configuration of the present invention, and will be described separately for easy understanding of various configurations of the present invention. Each section does not limit the technical scope of the present invention, and some of the components of each section are replaced, deleted, or further while referring to the best mode for carrying out the invention. Those to which the above components are added can also be included in the technical scope of the present invention.

(1) a socket, a rotating part that engages with the socket so as to be relatively movable in the axial direction and rotationally drives the socket, and a holding part that holds the socket so as to be movable and rotatable in the axial direction; A nut runner including a magnetic spring for moving the socket in the axial direction with respect to the rotating portion (Claim 1).
In the nut runner described in this section, when the socket is rotated by the rotating portion and the bolt and nut are tightened, the axial movement of the socket relative to the rotating portion is caused by the expansion and contraction of the magnetic spring, and the pressing force of the nut runner is reduced. It is appropriately controlled with respect to the progress of the tightening operation.

(2) In the above item (1), the holding portion allows the relative movement range in the axial direction of the socket and the rotating portion to fall within a range where the pressing force of the expansion / contraction stroke of the magnetic spring is constant. A nut runner in which a socket and the rotating portion are held (Claim 2).
The nutrunner described in this section has a holding portion so that the relative movement range of the socket and the rotating portion is within a certain range of the pressing force of the expansion / contraction stroke of the magnetic spring that causes the axial movement of the socket with respect to the rotating portion. Thus, the socket and the rotating part are held. For this reason, when the socket is rotated by the rotating part and the bolt and nut are tightened, the pressing force of the nut runner is constant regardless of the passage of time of the tightening work, that is, the axial movement of the socket relative to the rotating part. Controlled. The pressing force at this time is set to a strength that avoids the occurrence of galling due to the excessive pressing force of the nut runner in the initial stage of the tightening operation. In this case, as the tightening operation progresses, the occurrence of socket detachment due to insufficient pressing force of the nut runner is taken into consideration, and the pressing force is set to an appropriate constant pressing force that can also be avoided. It is desirable.

(3) In the above item (1), the holding portion causes the socket and the socket to be within a range in which the pressing force of the expansion / contraction stroke of the magnetic spring is increased. A nut runner in which the rotating part is held (Claim 3).
The nutrunner described in this section has a holding part so that the relative movement range of the socket and the rotating part is within the range in which the pressing force of the expansion / contraction stroke of the magnetic spring that causes the axial movement of the socket with respect to the rotating part is increased. Thus, the socket and the rotating part are held. Therefore, the pressing force of the nut runner when the socket is rotated by the rotating portion and the bolt nut is tightened is increased with the passage of time of the tightening operation, that is, the axial movement of the socket with respect to the rotating portion. Controlled. The pressing force at this time is set to a strength that prevents the occurrence of galling due to the excessive pressing force of the nut runner in the initial stage of the tightening operation. Further, the pressing force is set so as to increase to a strength that avoids the occurrence of the socket detachment due to the shortage of the pressing force of the nut runner as the tightening operation progresses.

(4) In the above items (1) to (3), the holding part is constituted by a cylindrical member, the socket, the rotating part, and the holding part are arranged concentrically, and the socket A nut runner in which the magnetic spring is configured in a range where the rotating portion is in sliding contact with each other.
In the nut runner described in this section, the socket, the rotating portion, and the holding portion configured by the cylindrical member are arranged concentrically, and the movement of the socket in the axial direction with respect to the rotating portion can be performed. It is caused by the magnetic springs configured in the range where they are in sliding contact with each other. Then, while controlling the pressing force of the nutrunner by the magnetic spring, the rotating portion held rotatably by the holding portion which is a cylindrical member was also held by the holding portion so as to be rotatable and slidable in the axial direction. The socket is driven to rotate, and the bolts and nuts are tightened.

(5) In the above items (1) to (3), the holding portion includes a linear guide that holds the socket movably in the axial direction with respect to the rotating portion, and the magnetic spring includes a stator and the stator. A nut runner which is arranged in parallel with the linear guide, and one of the stator and the slider is fixed to the rotating portion and the other is fixed to the socket. (Claim 5).
In the nut runner described in this section, the magnetic spring includes a stator and a slider that slides relative to the stator, and one of the stator and the slider is fixed to the rotating portion, and the other is fixed to the socket. . For this reason, the movement of the socket in the axial direction with respect to the rotating part is caused by the magnetic spring arranged parallel to the axial direction of the rotating part. Then, while controlling the pressing force of the nut runner by the magnetic spring, the linear guide guides the socket in the axial direction with respect to the rotating portion, and the socket is rotated by the rotating portion held rotatably by the holding portion, Tighten bolts and nuts.

(6) In the above items (1) to (5), a nutrunner in which sliding portions of the socket and the rotating part have a polygonal cross section.
In the nutrunner described in this section, the sliding contact portions of the socket and the rotating portion have a polygonal cross section, so that the socket and the rotating portion are prevented from rotating together and are relatively movable in the axial direction, and The socket is rotationally driven by the rotating part.

(7) The nut runner according to the above items (1) to (5), wherein the sliding contact portions of the socket and the rotating part have a circular cross section and are provided with a detent.
In the nutrunner described in this section, the sliding contact portions of the socket and the rotating part have a circular cross section, and the rotation preventing part is formed between the socket and the rotating part. The socket is movable and is driven to rotate by the rotating part.

(8) In the above item (7), the socket has a base end portion that engages with the rotating portion and a tip end portion that engages with the bolt nut on the same axis, and the base end portion and the tip end portion The power transmission mechanism which connects is provided.
In the nut runner described in this section, the base end portion of the socket that engages with the rotating portion and the tip end portion that engages with the bolt nut are not coaxial, and the bolt nut is tightened at a position offset from the rotating portion. Is to do.

(9) The nut runner according to the above items (1) to (8), wherein the magnet constituting the magnetic spring includes an electromagnet.
In the nutrunner described in this section, the magnet constituting the magnetic spring includes an electromagnet, and the pressing force of the magnetic spring that causes the movement of the socket relative to the rotating part by changing the current value flowing through the coil of the electromagnet It is controlled to increase with the passage of time. Then, when the socket is driven to rotate by the rotating part and the bolt and nut are tightened, the pressing force of the nut runner increases with the passage of time of the tightening work, that is, the axial movement of the socket with respect to the rotating part. It is to be controlled. The pressing force at this time is set to a strength that prevents the occurrence of galling due to the excessive pressing force of the nut runner in the initial stage of the tightening operation. Further, as the tightening operation progresses, it is set so as to increase to such a strength that the occurrence of the socket detachment due to insufficient pressing force of the nut runner is avoided. It is also possible to control the pressing force of the nutrunner to be constant, and in this case, the pressing force is appropriately adjusted to an appropriate strength that can avoid both galling and socket detachment. is there.

(10) A socket, a rotating portion that engages the socket so as to be relatively movable in the axial direction and rotationally drives the socket, and the socket and the rotating portion are relatively movable and rotatable in the axial direction. A nutrunner having a holding part for holding and a spring for moving the socket in the axial direction with respect to the rotating part, and using a magnetic spring for the spring, and a force for moving the socket in the axial direction with respect to the rotating part A method for controlling the pressing force of the nut runner that controls the magnetic spring by means of the magnetic spring (Claim 6).
The nut runner described in this section uses a magnetic spring as a spring, and causes the axial movement of the socket in the axial direction with respect to the rotating portion to be caused by the magnetic spring. When the bolt and nut are tightened, the magnetic spring controls the force for moving the socket relative to the rotating part, and the nut runner pressing force is appropriately controlled appropriately for the progress of the tightening operation. Is.

(11) In the above item (10), the range of relative movement in the axial direction of the socket and the rotating part is accommodated in a range in which the pressing force of the expansion / contraction stroke of the magnetic spring is constant, and the socket is connected to the rotating part. A method for controlling the pressing force of a nut runner that controls the moving force to be constant (claim 7).
The nutrunner described in this section accommodates the relative movement range of the socket and the rotating part in the axial direction of the expansion and contraction stroke of the magnetic spring, and moves the socket in the axial direction with respect to the rotating part. Control the force to be constant. Then, when the socket is rotated by the rotating part and the bolt and nut are tightened, the pressing force of the nut runner is kept constant regardless of the passage of time of the tightening work, that is, the axial movement of the socket relative to the rotating part. It is something to control. The pressing force at this time is set to a strength that prevents the occurrence of galling due to the excessive pressing force of the nut runner in the initial stage of the tightening operation. In this case, as the tightening operation progresses, considering the occurrence of socket detachment due to insufficient nutrunner pressing force, set an appropriate constant pressing force that can also be avoided. Is desirable.

(12) In the above item (10), an axial relative movement range of the socket and the rotating part is accommodated in a range in which the pressing force of the expansion / contraction stroke of the magnetic spring is increased, and the socket is connected to the rotating part. A method of controlling a pressing force of a nut runner that increases the force to be moved according to the amount of movement of the socket relative to the rotating part (claim 8).
The nut runner described in this section stores the relative movement range of the socket and the rotating part in the axial direction of the expansion and contraction stroke of the magnetic spring, and moves the socket with respect to the rotating part. Control is performed so as to increase in accordance with the amount of movement of the socket relative to the rotating part. Then, when the socket is rotated by the rotating portion and the bolt nut is tightened, the pressing force of the nut runner is increased with the passage of time of the tightening operation, that is, the axial movement of the socket with respect to the rotating portion. It is something to control. The pressing force at this time is set to a strength that prevents the occurrence of galling due to the excessive pressing force of the nut runner in the initial stage of the tightening operation. Further, as the tightening operation proceeds, the setting is made so as to increase the strength to avoid the occurrence of the socket detachment due to the shortage of the pressing force of the nut runner.

  Since the present invention is configured as described above, it is possible to easily and reliably realize the pressing force control of the nut runner that can prevent the occurrence of defects during tightening work such as galling or socket disconnection.

It is sectional drawing of the nutrunner which concerns on embodiment of this invention, (a) is a state of the initial stage of bolt fastening operation | work, (b) The state of the final stage of bolt fastening operation | work, (c) is (a ) Is a cross section taken along the line AA. It is a graph which shows the relationship between the pressing force of the nut runner shown by FIG. 1, and the time of fastening operation | work. It is a graph which shows the characteristic of the magnetic spring of the nutrunner shown in FIG. It is sectional drawing which concerns on the other example of the nut runner which concerns on embodiment of this invention, (a) is a state of the initial stage of bolt fastening operation | work, (b) The state of the final stage of bolt fastening operation | work is (c) ) To (f) exemplify the BB cross section of (b). The application example of the nut runner which concerns on embodiment of this invention is shown, (a) is a principal part longitudinal view, (b) is a bottom view. (A) is a front view (partial sectional view) of the nut runner shown in FIG. 5, and (b) is a side view (partial sectional view) of a magnetic spring portion of the nut runner. It is sectional drawing of the conventional nutrunner, (a) shows the mode of the initial stage of bolt fastening operation | work, (b) The mode of the final stage of bolt fastening operation | work. (A) is a graph showing the relationship between the pressing force of the nut runner shown in FIG. 7 and the time of the tightening operation, and (b) is a graph showing a defect in the bolt tightening operation using the nut runner shown in FIG. It is a graph which shows the relationship between generation frequency and time of a fastening operation | work.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected and demonstrated about the part same as a prior art, or a corresponding part.
As shown in FIG. 1, the nut runner 24 according to the embodiment of the present invention is engaged with a socket 14 and a rotary unit 16 that rotationally drives the socket 14 by engaging with the socket 14 so as to be relatively movable in the axial direction. And a holding portion 18 that holds the socket 14 so as to be movable relative to the rotating portion 16 in the axial direction and rotatably. Further, a magnetic spring M is included as a spring that causes the axial movement of the socket 14 with respect to the rotating portion 16.

  In the example of FIG. 1, the holding portion 18 is configured by a cylindrical member that holds the socket 14 and the rotating portion 16 so that the socket 14 can rotate and the socket 14 can slide in the axial direction. Moreover, the magnetic spring M is comprised in the range which the socket 14 and the rotation part 16 mutually slidably contact, as FIG.1 (c) shows. That is, the socket 14 and the rotating part 16 constitute a stator of the magnetic spring M and a slider that slides relative to the stator. Further, in the range in which the magnetic spring M of the socket 14 and the rotating portion 16 is configured, the sliding portions of each other have a rectangular cross section. In FIG. 1C, the magnetic spring M is provided on two opposite faces of the rectangular cross section of the socket 14 and the rotating portion 16, but may be provided on one, three, or four faces as appropriate. Further, a permanent magnet may be arranged in one of the socket 14 and the rotating unit 16, and a ferromagnetic material such as iron may be used in the other. Furthermore, the range in which the magnetic spring M of the socket 14 and the rotating part 16 is configured may be such that the mutual sliding contact portions have a polygonal cross section other than a square.

  The nut runner 24 has the pressing force F1 in the initial stage of the bolt 12 tightening operation shown in FIG. 1A and the time of the tightening operation, and the final tightening operation of the bolt 12 shown in FIG. The pressing force F2 at the time of the stage can be constant as shown by the solid line in FIG. Further, as indicated by a dotted line in FIG. 2, the pressing force F can be increased with the passage of time T of the tightening operation so that F2 is larger than F1.

Such a control of the pressing force F of the nut runner 24 can be achieved by appropriately utilizing the characteristics of the magnetic spring shown in FIG. That is, the pressing force F of the magnetic spring M becomes a certain range (Fc) from the state where the pressing force F = 0 at both ends of the expansion / contraction stroke passes through a range (Fv) in which the pressing force F increases. Is. Accordingly, the socket 14 and the rotating portion 16 are held by the holding portion 18 so that the relative movement range of the socket 14 and the rotating portion 16 is within a certain range (Fc) of the pressing force F of the magnetic spring M. Thus, the pressing force F of the nut runner 24 can be controlled so that the pressing force F of the nut runner 24 becomes constant.
On the other hand, the holding part 18 is arranged to hold the socket 14 and the rotating part 16 so that the relative movement range of the socket 14 and the rotating part 16 is within the range (Fv) in which the pressing force of the magnetic spring M increases. Thus, the pressing force F of the nut runner 24 can be controlled to increase with the passage of time T of the tightening operation.

Now, the nut runner 26 of FIG. 4 is another example of the nut runner 24 of FIG. The difference between the two is that the mutual sliding contact portion in which the magnetic spring M of the socket 14 and the rotating portion 16 is formed has a circular cross section as shown in FIGS. By the way. In addition, the portion other than the range (engagement portion) 16a in which the magnetic spring M of the rotating portion 16 is configured, specifically, the base end portion 16c has a square cross section. Further, the inner cylinder portion of the socket 14 is provided with a small-diameter portion 14d in which an engaging recess 14b with the engaging portion 16a of the rotating portion 16 is formed. Further, the inner cylinder portion of the socket 14 is provided with a large-diameter portion 14f formed with a guide portion 14e with which an annular flange formed on the intermediate portion 16b of the rotating portion 16 is slidably contacted. A through hole 14g having a quadrangular cross-sectional shape is formed in the proximal end portion of the large diameter portion 14f, following the proximal end portion 16c of the rotating portion 16. Therefore, the socket 14 and the rotating portion 16 are prevented from rotating together by the base end portion 16c of the rotating portion 16 and the through hole 14g. The socket 14 and the rotating part 16 are relatively movable in the axial direction, and the socket 14 is rotationally driven by the rotating part 16.
As shown in FIGS. 4C to 4F, the facing portions of the socket 14 and the rotating portion 16 may be the same polarity or different polarities. The permanent magnet may be partially disposed, or the permanent magnet may be disposed throughout. Further, a permanent magnet may be arranged in one of the socket 14 and the rotating unit 16, and a ferromagnetic material such as iron may be used in the other. These points also apply to the nutrunner 24 of FIG.

  5 and 6 show still another nutrunner 28 according to the embodiment of the present invention. 1 and 4 is different from the conventional nut runners 24 and 26 in that the magnetic spring M is constituted by the socket 14 and the rotating portion 16 itself, whereas the nut runners 24 and 26 in FIGS. In the nut runner 28, the magnetic spring M forms a separate body with respect to the socket 14 and the rotating portion 16, and is disposed in parallel with the axial direction of the rotating portion 16.

  More specifically, the holding unit 18 includes a guide unit 30 that holds the socket 14 so as to be relatively movable with respect to the rotating unit 16. In addition, the guide means 30 includes a base plate 301 fixed to the housing 22 of the motor 32 that drives the rotating unit 16. The base plate 301 is formed with an insertion hole 301 a for inserting the rotation shaft 32 a of the motor 32. A slide plate 304 is supported on a bracket 302 fixed to the base plate 301 via a linear guide 303 that slides parallel to the axial direction of the rotating portion 16. A socket 14 and two flanges 305 that hold the magnetic spring M are fixed to the slide plate 304. Furthermore, a stay 306 shown only in FIG. 6A is fixed to the slide plate 304. The slide pin 307 is slidably held by the stay 306. The slide pin 307 is fixed to the base plate 301 in parallel with the axial direction of the rotating unit 16. The stay 306 and the slide pin 307 also function as a guide when the slide plate 304 is slid in parallel with the axial direction of the rotating portion 16, and assist the linear guide 303.

The magnetic spring M in FIGS. 5 and 6 includes a cylindrical stator Ma and a columnar slider Mb that slides relative to the stator Ma. The stator Ma is fixed to the slide plate 304 by a flange 305. . On the other hand, the upper end of the slider Mb is fixed to the base plate 301. That is, in the example of FIGS. 5 and 6, the stator Ma is fixed to the socket 14 and the slider Mb is fixed to the rotating portion 16, but the relationship may be reversed.
In addition, by moving the position of the flange 305 with respect to the slide plate 304, it is also possible to move the relative position in the axial direction of the stator Ma with respect to the slider Mb. Then, if necessary, the holding portion 18 moves the socket 14 and the rotating portion 16 so that the relative movement range between the socket 14 and the rotating portion 16 is within a certain range (Fc) of the pressing force F of the magnetic spring M. It can be adjusted to hold. On the other hand, the holding part 18 is arranged to hold the socket 14 and the rotating part 16 so that the relative movement range of the socket 14 and the rotating part 16 is within the range (Fv) in which the pressing force of the magnetic spring M increases. It is also possible. Such post-adjustment means for the pressing force F can be appropriately provided in the nut runners 24 and 26 shown in FIGS.

The magnetic spring M applies a force that moves the socket 14 in the axial direction relative to the rotating portion 16 to the slide plate 304 of the guide means 30 by sliding the stator Ma in the axial direction relative to the slider Mb. Is. As the magnetic spring M used here, as a stroke S (FIG. 5A) necessary for the tightening operation of the bolt 12, for example, S = 30 mm is secured and the pressing force is constant. = 10 to 60 N are used, but these specific numerical values are appropriately set according to the bolt 12 to be tightened (these values are the same in the examples of FIGS. 1 and 4). is there).
5 and 6, two magnetic springs M are used. However, only one magnetic spring M or three or more magnetic springs M may be used as appropriate. Further, instead of the linear guide 303, the stay 306 and the slide pin 307, another type of guide may be used as a guide for sliding the slide plate 304 in parallel with the axial direction of the rotating portion 16.

In the example of FIGS. 5 and 6, similarly to the engaging portion 16 a of the rotating portion 16 having a square cross-sectional shape, the base end portion 141 of the socket 14 has an engaging portion 16 a having a square cross-sectional shape. The engaging recess 14b is formed. Therefore, the base end portion 141 of the socket 14 is slidable in the axial direction with respect to the rotating portion 16 and is rotated by the rotating portion 16.
The socket 14 includes an arm 143 including a power transmission mechanism 142 including a plurality of gears 142a to 142e. The arm 143 is fixed to the slide plate 304 so as to project in a direction orthogonal to the rotating portion 16. In the illustrated example, the gear 142a of the arm 143 has an engagement portion having a quadrangular cross-sectional shape that is detachably engaged with the base end portion 141. The gear 142e is formed with a tip end portion 14a that engages with the head of the bolt and nut. Therefore, in the example of FIGS. 5 and 6, the base end portion 141 and the tip end portion 14 a of the socket 14 are not coaxial and have an L shape as a whole. Note that the power transmission mechanism 142 is not limited to the plurality of gears 142a to 142e, and a mechanism capable of transmitting power as appropriate, such as a chain, a belt, and a pulley.

Further, as shown in FIG. 5A, the rotating portion 16 includes an engaging portion 16a for the socket 14 and an engaging portion 16d for the rotating shaft 32a of the motor 32. The engaging portion 16 d of the motor 32 with the rotating shaft 32 a has a hat-like vertical cross section, and a cross-sectional shape of the engaging portion 16 d is a quadrangle following the rotating shaft 32 a of the motor 32. A coil spring 34 is provided between the annular flange 16e provided at the outermost end of the engaging portion 16d and the annular flange 141a provided at the proximal end portion 141 of the socket 14. By this coil spring 34, the base end portion 141 of the socket 14 is always urged downward in FIGS. 5 (a) and 6 (a).
Then, the arm 143 of the socket 14 moves in the axial direction of the rotating unit 16 as indicated by a solid line and a dotted line in FIG. 5A, while the rotating shaft 32 a of the motor 32, the rotating unit 16, and the socket 14. The distal end portion 14 a is rotationally driven via the power transmission mechanism 142 of the base end portion 141 and the arm 143, and the bolt 12 is tightened at a position offset from the axis of the rotating portion 16.

Now, according to the embodiment of the present invention configured as described above, the following operational effects can be obtained.
First, the nut runners 24, 26, and 28 according to the embodiment of the present invention rotate the socket 14 by the rotating portion 16 to move the socket 12 in the axial direction relative to the rotating portion 16 when the bolt 12 is tightened. Is caused by the expansion and contraction of the magnetic spring M, and the pressing force F of the nut runners 24, 26 and 28 is appropriately controlled with respect to the progress of the tightening operation.

  In particular, the range of relative movement between the socket 14 and the rotating portion 16 is within a range where the pressing force of the expansion / contraction stroke of the magnetic spring M causing the axial movement of the socket 14 relative to the rotating portion 16 is constant (see Fc in FIG. 3). Assuming that the socket 14 and the rotating portion 16 are held by the holding portion 18 so as to be accommodated, the pressing force F of the nut runners 24, 26, and 28 is controlled to be constant regardless of the time of tightening work. (Aspect indicated by a solid line in FIG. 2). Moreover, the pressing force F at this time is set to a strength that avoids the occurrence of galling due to the excessive pressing force of the nut runner in the initial stage of the tightening operation, so that the galling problem is reduced. No longer occurs. In this case, as the tightening operation progresses, it is possible to consider occurrence of socket detachment due to insufficient pressing force F of the nut runners 24, 26, 28, and to prevent this from occurring. It is desirable to set the pressing force F.

  Further, the relative movement range of the socket 14 and the rotating part 16 is within a range where the pressing force of the expansion / contraction stroke of the magnetic spring M causing the axial movement of the socket 14 with respect to the rotating part 16 is increased (see Fv in FIG. 3). If the socket 14 and the rotating part 16 are held by the holding part 18 so as to be accommodated, the pressing force F of the nut runners 24, 26, 28 is controlled so as to increase with the lapse of time T of the tightening operation. (A mode indicated by a dotted line in FIG. 2). The pressing force F at this time is set to a strength at which the occurrence of galling due to the excessive pressing force F of the nut runners 24, 26, 28 is avoided in the initial stage of the tightening operation. Further, as the tightening operation progresses, the setting is made so that it increases to a strength that prevents the occurrence of socket detachment due to insufficient pressing force F of the nut runners 24, 26, 28. Further, the occurrence of the socket detachment is avoided.

In the embodiment of the present invention, as shown in FIG. 1 and FIG. 4, the socket 14, the rotating part 16, and the holding part 18 constituted by the cylindrical member are arranged concentrically, and the rotating part 16. It is possible to adopt a configuration in which the movement of the socket 14 in the axial direction is caused by the magnetic spring M configured in a range where the socket 14 and the rotating portion 16 are in sliding contact with each other.
As shown in FIGS. 5 and 6, the magnetic spring M includes a stator Ma and a slider Mb that slides relative to the stator Ma, and is disposed in parallel with the linear guide 303 of the holding portion 18. It is also possible to adopt a configuration in which one of the stator Ma and the slider Mb is fixed to the rotating portion 16 and the other is fixed to the socket 14. Furthermore, in the example shown in FIGS. 5 and 6, since the base end portion 141 of the socket 14 that engages the rotating portion 16 and the tip end portion 14 a that engages the bolt M are not coaxial, the rotating portion The bolt 12 can be tightened at a position offset from 16.

  Further, as a magnet constituting the magnetic spring M, an electromagnet is used in place of the permanent magnet, and the current value flowing through the coil of the electromagnet is changed, and the pressing force of the magnetic spring M causing the movement of the socket 14 with respect to the rotating portion 16 is tightened. It is also possible to control to increase with the lapse of time of work. Also in this case, the pressing force F of the nut runners 24, 26, and 28 is prevented from causing galling due to the excessive pressing force F of the nut runners 24, 26, and 28 in the initial stage of the tightening operation. Set to strength. Further, as the tightening operation progresses, the setting is made such that the strength increases so that the occurrence of the socket detachment caused by the insufficient pressing force F of the nut runners 24, 26, 28 is avoided. Further, even when the pressing force F of the nut runners 24, 26 and 28 is controlled to be constant, the pressing force F is appropriately set to an appropriate strength capable of avoiding both galling and socket detachment. It becomes possible to adjust.

  12: bolt, 14: socket, 14a: tip portion, 14b: engagement recess, 14g: through hole, 141: base end portion, 142: power transmission mechanism, 143: arm, 16: rotating portion, 16a: engagement portion , 18: holding portion, 22: housing, 24, 26, 28: nutrunner, 30: guide means, 303: linear guide, 32: motor, M: magnetic spring, Ma: stator, Mb: slider

Claims (8)

A socket, a rotating portion that engages with the socket in an axially movable manner and rotationally drives the socket, a holding portion that holds the socket in an axially movable and rotatable manner, and the rotating portion And a magnetic spring for moving the socket in the axial direction. The socket and the rotating part are held by the holding part so that the axial relative movement range of the socket and the rotating part is within a certain range of the pressing force of the expansion / contraction stroke of the magnetic spring. The nutrunner according to claim 1, wherein The socket and the rotating part are held by the holding part so that the range of relative movement in the axial direction of the socket and the rotating part is within the range in which the pressing force of the expansion / contraction stroke of the magnetic spring increases. The nutrunner according to claim 1, wherein The holding portion is formed of a cylindrical member, and the socket, the rotating portion, and the holding portion are arranged concentrically, and the magnetic field is within a range where the socket and the rotating portion are in sliding contact with each other. The nut runner according to any one of claims 1 to 3, wherein a spring is formed. The holding portion includes a linear guide that holds the socket movably in the axial direction with respect to the rotating portion, the magnetic spring includes a stator and a slider that slides relative to the stator, and the linear spring 4. The device according to claim 1, wherein the stator and the slider are fixed to the rotating portion, and the other is fixed to the socket. The nutrunner described. A socket, a rotating portion that engages the socket so as to be relatively movable in the axial direction and rotationally drives the socket, and a holder that holds the socket and the rotating portion so as to be relatively movable and rotatable in the axial direction And a nutrunner that provides a spring for moving the socket in the axial direction relative to the rotating portion, using a magnetic spring as the spring, and a force for moving the socket in the axial direction relative to the rotating portion, A method for controlling the pressing force of a nut runner, wherein the pressing force is controlled by a magnetic spring. A range in which the pressing force of the expansion and contraction stroke of the magnetic spring is within a certain range includes a relative movement range in the axial direction of the socket and the rotating part, and the force for moving the socket with respect to the rotating part is controlled to be constant. The method of controlling a pressing force of a nut runner according to claim 6. The range of the expansion and contraction stroke of the magnetic spring is within a range in which the pressing force increases, and the axial relative movement range of the socket and the rotating part is accommodated, and the force for moving the socket with respect to the rotating part is set to the rotating part. 7. The method of controlling a pressing force of a nut runner according to claim 6, wherein the pressing force is increased in accordance with a movement amount of the socket.

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