JP2008073797A - Screw member tightening device, and manufacturing method of assembly - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a screw member tightening device which causes a nut core to automatically copy a core of a screw spindle without applying a large load to any of screw members for smooth centering of the respective cores, and also performs automatic tightening, and also to provide a manufacturing method of an assembly. <P>SOLUTION: The screw member tightening device T includes a fixed driving motor 4 including a driving shaft 4a, a displaceable tightening part 2 having a driven shaft 24, a guide mechanism R for coupling the driving shaft with the tightening part, and a floating mechanism F for coupling the driven shaft with a nut holding part. The guide mechanism includes: a driving gear 9 provided on the driving shaft; a driven gear 25 provided on the driven shaft; an idler shaft 45a interposed between the driven shaft and the driving shaft with a center distance from the driven shaft and a center distance from the driving shaft specified to be the same; an idler gear 45 provided on the idler shaft and engaging both with the driving gear and the driven gear; a first link arm 11 for rotatably connecting the driving shaft with the idler shaft; and a second link arm 20 for rotatably connecting the idler shaft with the driven shaft. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a screw member fastening device that automatically fits a nut shaft core to a screw shaft (bolt) shaft shaft and automatically rotates the nut to fasten, and an assembly using the screw member fastening device. It relates to the manufacturing method.

For example, when manufacturing an assembly which is a notebook personal computer (hereinafter referred to as “notebook personal computer”), a screw shaft is used to assemble (assemble) each component and fasten (attach) the assembled component to a housing. Many screw members consisting of bolts and nuts are required. Moreover, since the target assembly is small, the screw diameter of the screw member is small, and man-hours are required for man-hours for screw fastening.
Therefore, a screw member fastening device, a so-called nut runner, is often used to automatically fasten the two members with a screw member made up of a nut and a screw shaft, thereby reducing costs by improving productivity and saving labor. Is planned.

In this type of nut runner, there is no problem if the axis of the fastener with the hexagonal hole that holds the nut matches the axis of the screw shaft, and the alignment of each other is accurate, In many cases, accurate alignment is difficult and misalignment occurs. At this time, the nut is fitted to the screw shaft from an oblique direction, and a tightening failure occurs.
Therefore, as shown in FIG. 7, if the tightening tool K is rotated by forming the hexagonal hole r shape of the tightening tool K to be larger than the outer shape of the nut N, the apex angle q of the nut N is inevitable. In particular, it abuts against the side of the hexagonal hole r. Although the hexagonal hole r and the nut N of the fastener K are misaligned with each other, the centers of both coincide with each other, so that the nut N rotates smoothly and is screwed onto the screw shaft.

In such a configuration, the nut N cannot be held in the hexagonal hole r of the fastener K in advance from the above dimension setting. First, the operator properly aligns the nut N with the screw shaft and holds the nut N, and then engages the hexagonal hole r of the fastening tool K so that the nut N is not displaced or tilted, and remains as it is. The nut N must be rotated.
In particular, when the hexagonal hole r of the fastener K is engaged with the nut N, the nut N cannot be held. When the fastening tool K is rotated, any one side of the hexagonal hole r first hits the apex angle q of the nut N, and the posture of the nut N is easy to tilt. That is, the axis of the nut N is easily displaced from the axis of the screw shaft, and correct screw tightening is difficult.

[Patent Document 1] discloses a nut runner for automatically fastening a screw member. Although there is no particular description in this specification, there is an allowance (backlash) that the entire apparatus can move to some extent in the horizontal direction. For this reason, even if the fastening member held by the fastener and the axial center of the other fastening member to be screwed with each other are misaligned, the misalignment of the entire apparatus can be absorbed.
However, since the entire apparatus including the heavy drive source has to move, smooth movement cannot be guaranteed. When the alignment is completed, the entire weight of the device is applied to the threaded portion of the screw member, and the threaded portion that has received the impact is likely to be damaged.
[Patent Document 2] discloses a nut runner having a flexible shaft coupling between a drive shaft and a driven shaft rotated by the drive shaft. By providing the flexible shaft coupling, even if there is a misalignment between the fastening members, the misalignment is surely absorbed and proper fastening can be smoothly performed.
Japanese Patent Laid-Open No. 9-108963 JP-A-6-55383

However, the nut runner of [Patent Document 2] is provided with a recess having a regular polygonal cross section perpendicular to the axis and a flat surface on each inner wall at the ends of the drive shaft and the driven shaft. A flexible shaft joint has a curved surface with outwardly convex curved surfaces, a regular polygonal cross section perpendicular to the shaft core, and a conductor having a bulging portion along the inside of the recess at both ends at the maximum. The bulging portions at both ends of the transmission body are fitted into the respective recesses.
Thus, the transmission body which comprises a flexible shaft coupling is a very complicated shape, and requires time and effort for manufacture. In order to accurately fit the transmission body into the recesses of the drive shaft and the driven shaft, high-precision machining is required. Furthermore, it is necessary to attach a plurality of elastic body supports that elastically support the driven shaft to the drive shaft at equal intervals, and it is difficult to adjust the balance between the elastic forces.

  The present invention has been made based on the above circumstances, and the object of the present invention is to automatically turn the nut shaft core into the screw shaft shaft without applying a large load to any of the screw members. A screw member fastening device that can smoothly align each other and allow automatic fastening, and an assembly manufacturing method that uses the screw member fastening device to manufacture an assembly. It is.

In order to satisfy the above object, a screw member fastening device according to the present invention includes a drive source having a drive shaft and a tightening portion that has a driven shaft that is rotationally driven by the drive shaft and that screwes a nut that holds the driven shaft into the screw shaft. A guide mechanism that connects the drive shaft and the tightening portion so that the tightening portion can be displaced in the horizontal direction while fixing the position of the drive shaft, and the nut holding portion in the tightening portion is perpendicular to the screw shaft. A floating mechanism that connects the driven shaft and the nut holding portion so as to elastically abut,
The guide mechanism includes a driving gear provided on a driving shaft whose position is fixed, a driven gear provided on a driven shaft whose position is displaceable, and a position which is displaceable and interposed between the driven shaft and the driving shaft. The idler shaft having the same distance between the driven shaft and the drive shaft, the idler gear provided on the idler shaft meshing with both the drive gear and the driven gear, the drive shaft and the idler shaft. A first link arm that rotatably connects the shaft and a second link arm that rotatably connects the idler shaft and the driven shaft are provided.

  Furthermore, in order to satisfy the above object, the method for manufacturing an assembly of the present invention includes a step of fastening a nut and a screw shaft using the screw member fastening device.

  According to the present invention, without causing a large load to be applied to any of the screw members, the nut shaft core is automatically made to follow the shaft shaft of the screw shaft, and the respective shaft centers are smoothly aligned. In addition, there is an effect that enables automatic fastening.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a longitudinal front view of a screw member fastening device T according to the first embodiment, FIG. 2 is a plan view of a guide mechanism R in the same embodiment, and FIG. 3 is a basic configuration diagram of the guide mechanism R.
A screw member fastening device T shown in FIG. 1 includes a drive unit 1, a tightening unit 2 including a floating mechanism F, and an intermediate drive unit 3 interposed between the drive unit 1 and the tightening unit 2. .
First, the drive unit 1 will be described. The drive motor 4 as a drive source is supported by the base plate 6 via the support member 5 with the drive shaft 4a facing downward. The base plate 6 extends in the horizontal direction from the driving unit 1 to the tightening unit 2 via the intermediate driving unit 3.

An extension shaft 7 extending in the same direction as the drive shaft 4 a is fitted and fixed to the drive shaft 4 a of the drive motor 4. The extension shaft 7 is inserted through a hole a provided in the base plate 6 and protrudes further downward. The outer ring portion of the bearing member 8 is fitted into the hole a of the base plate 6, and the extension shaft 7 is fitted and fixed to the inner ring portion of the bearing member 8.
A drive gear 9 is fitted and fixed to a portion of the extension shaft 7 that protrudes downward from the base plate 6, and the extension shaft 7 portion between the base plate 6 and the motor support 5 is connected to the first through a bearing 10. One end of the link arm 11 is attached. The drive gear 9 is covered with a cover 12 attached to the lower surface of the base plate 6. The cover 12 is extended to the tightening portion 2 via the intermediate drive portion 3.

The tightening portion 2 includes a driver shaft portion 13 which is inserted into an opening b provided in the base plate 6 and protrudes upward from the base plate 6 and supported as described later. The driver shaft portion 13 is a cylindrical body whose axis is oriented in the vertical direction, and a copying plate 14 is attached to the upper end portion in the horizontal direction.
Rail portions 15a of a pair of X linear guides (only one shown) 15 oriented on the upper surface of the base plate 6 and to the left and right with the driver shaft portion 13 in between are mounted. Established. An intermediate plate 16 is mounted on a guide portion 15 b that is movable with respect to the rail portion 15 a of the X linear guide 15.

On the upper surface of the intermediate plate 16, a rail portion 17a of a pair of Y linear guides (only one shown) 17 oriented in the Y direction (left and right direction in the figure) is mounted. The copying plate 14 provided at the upper end portion of the driver shaft portion 13 is mounted on a guide portion 17b that is movable with respect to the rail portion 17a of the Y linear guide 17.
Therefore, the copying plate 14 is supported by the base plate 6 via the X linear guide 15 and the Y linear guide 17, and the driver shaft portion 13 integrated with the copying plate 14 is free in the X direction and the Y direction. It is freely displaceable.

An inner ring portion of the bearing member 18 is fitted into the outer peripheral surface of the lower end portion of the driver shaft portion 13, and one end portion of the second link arm 20 is fitted and fixed to the outer ring portion of the bearing member 18. Therefore, the second link arm 20 and the driver shaft portion 13 are rotatable with respect to each other.
Outer ring portions of the bearing members 22 and 23 are fitted on the inner peripheral surface of the driver shaft portion 13 with a space in the vertical direction, and a cylindrical driven shaft 24 is fitted to the inner ring portions of the bearing tools 22 and 23. It is. That is, the driven shaft 24 is supported by the driver shaft portion 13 via the bearings 22 and 23 and is rotatable with respect to the driver shaft portion 13.

A driven gear 25 is fitted and fixed to the outer peripheral surface of the driven shaft 24 protruding downward from the lower bearing 23, and a rotating arm 26 is fitted to the outer peripheral surface of the driven shaft 24 on the lower side of the driven gear 25. ing. Therefore, the driven gear 25 and the rotating arm 26 are rotatable together with the driven shaft 24.
The rotary arm 26 is formed to extend further downward from the lower end surface of the driven shaft 24, and a bit shaft portion 28 is suspended from the lower end portion via a cam follower 27. That is, the bit shaft portion 28 and the cam follower 27 are movable in the vertical direction within the range of the cam follower support portion c provided on the rotating arm 26.

The bit shaft portion 28 is a substantially cylindrical body that protrudes downward from the lower end of the rotary arm 26. The inner and outer diameters on the lower side are slightly larger than the upper side, and stepped portions d and e are projected on the inner diameter side at the boundary. On the inner diameter side of the lower end of the bit shaft portion 28, a hexagonal hole 28a that matches the outer shape and outer diameter of the nut N constituting the screw member is provided.
A sensor dog 30 made of a thin plate is fitted and fixed in the horizontal direction on the outer diameter side stepped portion e of the bit shaft portion 28. Opposing the sensor dog 30, a height sensor 31 supported by a support tool (not shown) is disposed. The detection signal of the height sensor 31 is sent to a control unit (not shown) so that the distance between the height sensor 31 and the sensor dog 30 can be measured.

A fixed shaft 32 made of a pipe body is inserted from the inner diameter portion of the driven shaft 24 to the inner diameter portion of the bit shaft portion 28. The outer diameter of the fixed shaft 32 is the same as or slightly smaller than the inner diameter of the nut N to be held. The lower end edge of the fixed shaft 32 is aligned at substantially the same position as the lower end edge of the bit shaft portion 28, and the upper end portion of the fixed shaft 32 protrudes upward from the upper end edge of the driven shaft 24.
On the copying plate 14, a holding plate 33 having an approximately L-shaped cross section is provided, and an insertion hole f is provided in a horizontal portion of the holding plate 33. The upper end portion of the fixed shaft 32 is inserted into the insertion hole f of the presser plate 33 and further protrudes upward. A stop plate 34 is fitted and fixed to the outer peripheral surface of the upper end portion of the fixed shaft 32, and the stop plate 34 is supported on the presser plate 33. The upper end portion of the fixed shaft 32 is suspended from the presser plate 33 via a stop plate 34.

Rotary bushes 35 are respectively interposed between the inner peripheral surface of the driven shaft 24 and the outer peripheral surface of the fixed shaft 32 and between the inner peripheral surface of the bit shaft portion 28 and the outer peripheral surface of the fixed shaft 32. Due to the presence of the rotary bush 35, the fixed shaft 32 is not affected even if the driven shaft 24 and the bit shaft portion 28 are driven to rotate, and so-called accompanying phenomenon does not occur.
Further, due to the presence of the rotary bush 35, the fixed shaft 32 can freely move in the vertical direction with respect to the driven shaft 24 and the bit shaft portion 28, and is not affected by the movement of each other.

A receiving plate 37 is fitted and fixed to the outer peripheral surface of the fixed shaft 32 protruding from the upper end surface of the driven shaft 24. Between the receiving plate 37 and the horizontal portion of the pressing plate 33, a shaft pressing spring 38 made of a compression spring is interposed. Due to the presence of the wheel pressurizing spring 38, when the fixed shaft 32 receives upward urging force and tries to move upward, the shaft pressurizing spring 38 is compressed and deformed to generate a repulsive force, thereby pushing down the fixed shaft 32. Eggplant.
A bit pressure spring 39 made of a compression spring is interposed between the lower end surface of the driven shaft 24 and the upper end surface of the bit shaft portion 28. As described above, the bit shaft portion 28 is movable in the vertical direction via the cam follower 27. When the bit shaft portion 28 attempts to move upward due to the pushing biasing force, the bit pressurizing spring 39 is compressed and deformed. A repulsive force is generated, and the bit shaft portion 28 is pushed down.

In this way, from the combination of the assembly of the fixed shaft 32, the rotary arm 26 and the bit shaft portion 28 with respect to the driven shaft 24 in the tightening portion 2, and the arrangement of the shaft pressure spring 38, the bit pressure spring 39 and the rotary bush 35. The following mechanism F is configured.
A hose joint is provided at an end portion of the fixed shaft 32 that protrudes upward from the stopper plate 34, and a hose that communicates with a vacuum suction source such as a vacuum pump is connected to the end (not shown). Therefore, the inner diameter hole of the fixed shaft 32 is a vacuum hole 32a communicating with the vacuum suction source via the hose.

  The distal end shaft portion 40 is closely fitted to the lower end of the vacuum hole 32a, and the lower end of the vacuum hole 32a is closed. The tip shaft portion 40 includes a conical tip g that protrudes downward from the lower end surface of the fixed shaft 32. As will be described later, the shaft end taper portion h provided at the end of the screw shaft (bolt) G constituting the screw member and the conical tip g of the tip shaft portion 40 have exactly the same shape.

Between the lower end portion of the fixed shaft 32 in which the distal end shaft portion 40 is fitted and the portion facing the inner diameter step portion d of the bit shaft portion 28, a plurality of gaps exist along the peripheral surface of the fixed shaft 32. A communication hole 32b is provided. Due to the presence of these communication holes 32b, the vacuum hole 32a of the fixed shaft 32 and the lower end inner diameter portion of the bit shaft portion 28 are communicated with each other.
That is, the vacuum hole 32a of the fixed shaft 32 is connected to the nut N, whose outer shape is engaged with the hexagonal hole 28a of the bit shaft portion 28 and whose inner diameter portion is fitted to the outer peripheral surface of the fixed shaft 32, from the vacuum pump via the connection hose. The vacuum pressure led to Accordingly, the nut holding portion W is configured to hold the nut N by vacuum suction on the bit shaft portion 28.

The intermediate drive unit 3 includes a bearing member 42 in which an outer ring portion is fitted to the other end portion of the first link arm 11, a bearing member 43 in which an outer ring portion is fitted to the other end portion of the second link arm 20, and The idler shaft 45a is inserted into the inner ring portion of the bearings 42 and 43 and is fitted and fixed, and an idler gear 45 provided on the idler shaft 45a.
The idler gear 45 is engaged with both the drive gear 9 provided in the drive unit 1 and the driven gear 25 provided in the tightening unit 2. Since the idler shaft 45 a is supported by both the first link arm 11 and the second link arm 20, the idler shaft 45 a is affected by the displacement of the link arms 11 and 20.

Specifically, it is configured as shown in FIG.
The inter-axis distance dimension L between the drive shaft 4a constituting the axis of one end of the first link arm 11 and the idler shaft 45a constituting the axis of the other end, and the axis of one end of the second link arm 20 The inter-axis distance dimension L between the idler shaft 45a constituting the core and the driven shaft 24 constituting the other end portion axial core is set to be the same.
The position of the drive shaft 4a is fixed, and the first link arm 11 has the other end portion of the first link arm 11 pivotally supported by the idler shaft 45a and the second link arm 20 with this end portion as a fulcrum. The position of one end of is freely displaceable.
Further, the second link arm 20 pivotally supported by the driven shaft 24 with the other end portion of the first link arm 11 pivotally supported by the idler shaft 45a and the position of one end portion of the second link arm 20 pivoted. The end position is freely rotatable.

In this manner, the first link arm 11 and the second link arm 20 are provided from the drive unit 1 to the tightening unit 2 via the intermediate drive unit 3, and the drive gear 9, idler gear 45 and driven gear 25 are provided. A guide mechanism R is formed.
The drive gear 9, the driven gear 25, and the idler gear 45 all have the same number of teeth and the same gear diameter. In FIG. 2, since the second link arm 20 intersects the first link arm 11 by 90 °, the drive gear 9 and the driven gear 25 have an angle of 90 ° with respect to the idler gear 45. positioned.
As described above, the end portion to which the idler shaft 45a is attached is freely displaceable within the radius L with the end portion on the drive shaft 4a side of the first link arm 11 as a fulcrum. Then, a guide mechanism R in a right-angled two-degree-of-freedom direction in which an end portion where the driven shaft 24 of the second link arm 20 is provided is freely displaceable within a radius L with an end portion to which the idler shaft 45a is attached as a fulcrum is configured. The

Since the guide mechanism R is described above, the meshing state of the idler gear 45 with respect to the drive gear 9 does not change regardless of the position at which the first link arm 11 and the second link arm 20 are rotationally displaced, and the idler gear. There is no change in the meshing state of the driven gear 25 with respect to 45.
Basically, the guide mechanism R as shown in FIG. 3 is embodied.
In the figure, the center axis position of the C gear is fixed, and the B gear meshing with the C gear is movable in the X direction shown in the figure. The A gear that meshes with the B gear can move in the X direction together with the B gear, and can move in the Y direction orthogonal to the X direction. Eventually, the A gear can freely move in the XY directions with respect to the C gear whose position does not change.

The C gear corresponds to the drive gear 9 of the drive unit 1, and the position of the drive shaft 4a that is the central axis of the drive gear 9 is fixed. The B gear corresponds to the idler gear 45 of the intermediate drive unit 3, and the idler gear 45 meshes with the drive gear 9. An idler shaft 45a, which is the central axis of the idler gear 45, is movable in the X direction.
The A gear corresponds to the driven gear 25 of the tightening portion 2, and the driven gear 25 meshes with the idler gear 45. An idler shaft 45a, which is the central axis of the idler gear 45, can move in the X direction together with the idler gear 45, and can move in the Y direction orthogonal to the X direction. Eventually, the A gear (driven gear 25) is movable in the XY directions with respect to the C gear (drive gear 9) whose center position does not change.

Next, a method of attaching and manufacturing a member to be fastened, which is a component, to a housing of an assembly that is a notebook computer, for example, using the screw member fastening device T will be described.
First, the nut N is sucked and held on the nut holding portion W formed at the tip of the bit shaft portion 28 in the tightening portion 2 of the screw member fastening device T. At this time, the vacuum pump is driven, and a vacuum pressure is applied to the tip inner diameter portion of the bit shaft portion 28 through the vacuum hole 32a and the communication hole 32b of the fixed shaft 32.
The nut N has its outer shape engaged with the hexagonal hole 28a provided in the bit shaft portion 28, and receives the vacuum pressure in a state where the inner diameter portion is engaged with the outer peripheral surface of the end portion of the fixed shaft 32, and is securely held. In this state, for example, the casing of the notebook computer is moved directly below the screw member fastening device T and driven upward. Conversely, the screw member fastening device T may be supported by the lifting mechanism and lowered with respect to the housing.

A member to be fastened such as a component is placed in advance in the casing, and a screw shaft (bolt) is inserted into the member to be fastened. The screw shaft is a counterpart to be screwed with the nut N held by the nut holding portion W, and the screw portion of the screw shaft is set upward. Then, the tip shaft portion 40 of the bit shaft portion 28 approaches the screw shaft and finally comes into contact.
FIG. 4 shows a positional deviation state of the axial center La of the distal end shaft portion 40 (that is, the nut N) with respect to the axial center Lb of the screw shaft G in a state where the distal end shaft portion 40 is in contact with the screw shaft G, and a correction amount ( = Eccentricity) δ is shown, and FIG. 5 is a diagram showing the state of the reaction force generated at this time.
In a state where the tip shaft portion 40 is in contact with the screw shaft G, the shaft center La of the tip shaft portion 40 does not always coincide with the shaft core Lb of the screw shaft G. In most cases, as shown in FIG. Misalignment. The amount of misalignment at this time is the amount of eccentricity of the axis La of the tip shaft portion 40 with respect to the axis Lb of the screw shaft G, and is a correction amount δ for the screw shaft G of the tightening portion 2 as will be described later.

As shown in FIG. 5, when the axial center La of the tip shaft portion 40 abuts at a position eccentric with the shaft core Lb of the screw shaft G, a contact reaction force FW is generated from the contact position to the tip shaft portion 40. . Since the contact reaction force FW acts in an oblique direction, a horizontal component force Fh and a vertical component force Ft are generated in each of the horizontal direction and the vertical direction.
The horizontal component force Fh is absorbed by the guide mechanism R provided from the driving unit 1 to the tightening unit 2 via the intermediate driving unit 3. The vertical component force Ft is absorbed by the floating mechanism F configured in the tightening portion 2. Then, in a state where both the horizontal component force Fh and the vertical component force Ft are completely absorbed, the shaft core Lb of the screw shaft G and the shaft core La of the tip shaft portion 40 coincide, that is, the shaft core Lb of the screw shaft G. The axial center La of the nut N will coincide.

Specifically, the conical tip 40a of the tip shaft portion 40 abuts the screw shaft G at a position where the shaft core is eccentric, and the tip shaft portion 40 and the fixed shaft 32 receive the vertical component force Ft once. To rise. At this time, since the shaft pressing spring 38 absorbs the contact reaction force FW with respect to the fixed shaft 32, the screw shaft G and the fixed shaft 32 do not generate an impact during contact.
The conical tip g of the tip shaft portion 40 is pressed in the vertical direction against the shaft end taper portion h of the screw shaft G by the elastic repulsive force of the shaft pressurizing spring 38, and the first link arm in the guide mechanism R described above. 11 and the second link arm 20 cause the distal end shaft portion 40 to move in the XY direction together with the tightening portion 2.

That is, while the conical tip g of the tip shaft portion 40 contacts the shaft end taper portion h of the screw shaft G, the conical tip g moves following the shape of the shaft end taper portion h. Finally, the conical tip g is completely fitted into the shaft end taper portion h, and the shaft centers La and Lb coincide with each other. At the same time, the screw portion Na of the nut N and the screw portion Ga of the screw shaft G are correctly aligned.
At this time as well, no impact is generated on both the nut N and the screw part G, but the pushing-up action of the screw shaft G continues or the pushing-down action of the tightening part 2 continues. The screw portion Na of the nut N and the screw portion Ga of the screw shaft G come into contact with each other, and the bit shaft portion 28 that holds the nut N is pushed up. The sensor dog 30 provided integrally with the bit shaft portion 28 rises and approaches the height sensor 31.

A bit pressure spring 39 provided between the bit shaft portion 28 and the driven shaft 24 is compressed and deformed, and an elastic repulsive force is applied. Therefore, a large load is not applied to the threaded portion Na of the nut N and the threaded portion Ga of the screw shaft G, and damage to the threaded portions Na and Ga is reliably prevented.
By continuing the push-up action of the screw shaft G or the push-down action of the tightening portion 2, the sensor dog 30 continues to approach the height sensor 31 regardless of the elastic repulsion force of the bit pressurizing spring 39. Since the detection signal of the height sensor 31 is sent to the control unit, the control unit determines that the dimension between the height sensor 31 and the sensor dog 30 is different from the reference dimension stored in advance.

Then, the control unit sends a control signal for stopping the pushing-up action of the screw shaft G or the pushing-down action of the tightening unit 2. After that, the screw shaft G position or the tightening portion 2 is controlled to return to a position where the distance between the height sensor 31 and the sensor dog 30 becomes the reference dimension.
Next, the control unit sends a control signal to the drive motor 4 to start driving the drive shaft 4a. The drive gear 9 attached to the drive shaft 4a via the extension shaft 7 is rotationally driven, and the idler gear 45 and the driven gear 25 that mesh with the drive gear 9 rotate. Therefore, the driven gear 25 is rotationally driven in the same direction as the drive gear 9.

The driven gear 25 simultaneously rotates the bit shaft portion 28 via the driven shaft 24 and the rotating arm 26, and the nut N held by the nut holding portion W is rotationally driven. As described above, since the nut N is rotationally driven in a state where the shaft core Na of the nut N is correctly aligned with the shaft core Ga of the screw shaft G, the nut N is not inclined with respect to the screw shaft G, and smooth. Then, the screw is fastened and the fastened member is fastened to the housing.
While the nut N is screwed into the screw shaft G, the bit shaft portion 28 moves down together with the cam follower 27. At the same time, the bit pressurizing spring 39 urges a constant pressure (that is, elastic repulsive force) to the bit shaft portion 28, so that the rotation of the bit shaft portion 28 that holds the nut N is made smoother.

  When the bit shaft portion 28 is lowered by a predetermined amount, the nut N is securely screwed into the screw shaft G, and the fastened member is fastened to the housing. The height sensor 31 detects a predetermined amount of movement of the bit shaft portion 28, and the control unit that receives the detection signal stops driving the drive motor 4. Then, the screw member fastening device T receives the next nut N and repeats the above-described operation for the screw shaft G inserted through the fastened member.

In this way, the screw member fastening device T according to the present invention is a combination of the floating mechanism F provided in the tightening portion 2 and the guide mechanism R extending from the drive portion 1 to the tightening portion 2 via the intermediate drive portion 3. The axis Na of the nut N can be made to follow the axis Ga of the axis G, and can be quickly matched.
In addition, there is no impact on the screw shaft G and the nut N during the alignment of each other, and therefore the posture of the screw shaft G and the nut N is kept constant and there is no inclination, so that a smooth screwing operation can be performed. it can.
FIG. 6 is a diagram for explaining a guide mechanism Ra as a second embodiment, which substitutes the guide mechanism R described above, and schematically shows the guide mechanism Ra.

A line Ld connecting the axis of the idler gear 45 and the axis of the driven gear 25 intersects with the line Lc connecting the axis of the drive gear 9 and the axis of the idler gear 45 at 90 °. Here, the drive gear 9, the idler gear 45, and the driven gear 25 are supported so as to be rotatable on the spot without moving the axial center position.
Substrates are provided at the end portions of the rotation shafts of the gears 9, 45, 25 via bearings, and the positions of the respective substrates are fixed regardless of the rotation of the rotation shafts. A first guide plate 51 is mounted on a substrate attached to the rotation shaft of the idler gear 45 via a bearing, via a pair of X linear guides 50 that guide in the X direction.

A second guide plate 61 is mounted on a substrate attached to the rotating shaft of the driven gear 25 via a bearing member via a Y linear guide 60 that guides in the Y direction. Although the second guide plate 61 moves simultaneously with the first guide plate 51 in the X direction, only the second guide plate 61 itself (the second guide plate 61) moves in the Y direction. It is in an engaged state so as not to move in the same direction.
The above-described floating mechanism F is configured and attached to the second guide plate 61. Accordingly, the nut N is held by the nut holding portion W which is the tip of the bit shaft portion 28 via the floating mechanism F on the second guide plate 61.

By the combination of the floating mechanism F and the guide mechanism Ra, the axial center Na of the nut N can be quickly aligned with the axial center Ga of the screw shaft G in the XY direction. During the alignment, there is no impact on the screw shaft G and the nut N, the postures of the screw shaft G and the nut N are kept constant and there is no inclination, and the fastening operation is performed smoothly.
Note that the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above-described embodiments.

1 is a schematic cross-sectional view of a screw member fastening device according to a first embodiment of the present invention. The top view of the guide mechanism based on the embodiment. The basic block diagram of the guide mechanism based on the embodiment. The figure explaining the center shift | offset | difference state based on the embodiment. The figure explaining the reaction force at the time of the core shift based on the embodiment. The typical explanatory view of the guide mechanism concerning the 2nd embodiment in the present invention. The figure explaining the conventional nut fastening operation | work.

Explanation of symbols

  4a ... drive shaft, 4 ... drive motor (drive source), 24 ... driven shaft, N ... nut, G ... screw shaft, 2 ... tightening portion, R ... guide mechanism, W ... nut holding portion, F ... floating mechanism, 9 DESCRIPTION OF SYMBOLS ... Drive gear, 25 ... Drive gear, 45a ... Idler shaft, 45 ... Idler gear, 11 ... 1st link arm, 20 ... 2nd link arm, 51 ... 1st guide plate, 61 ... 2nd guide plate.

Claims (3)

In a screw member fastening device comprising: a drive source having a drive shaft; and a tightening portion having a driven shaft that is rotationally driven by the drive shaft and screwing a holding nut to the screw shaft.
A guide mechanism for connecting the drive shaft and the tightening portion so that the position of the drive shaft is fixed while the tightening portion can be displaced in the horizontal direction;
A floating mechanism that connects the driven shaft and the nut holding portion so that the nut holding portion in the tightening portion elastically contacts the screw shaft in the vertical direction;
The guide mechanism is
A drive gear provided on the drive shaft whose position is fixed;
A driven gear provided on the driven shaft whose position is freely displaceable;
An idler shaft having a freely displaceable position, interposed between the driven shaft and the drive shaft, and having the same distance between the drive shaft and the drive shaft.
An idler gear provided on the idler shaft and meshing with both the drive gear and the driven gear;
A first link arm that rotatably connects the drive shaft and the idler shaft;
A screw member fastening device comprising: a second link arm that rotatably connects the idler shaft and the driven shaft. In a screw member fastening device comprising: a drive source having a drive shaft; and a tightening portion having a driven shaft that is rotationally driven by the drive shaft and screwing a holding nut to the screw shaft.
A guide mechanism for connecting the drive shaft and the tightening portion so that the position of the drive shaft is fixed while the tightening portion can be displaced in the horizontal direction;
A floating mechanism that connects the driven shaft and the nut holding portion so that the nut holding portion in the tightening portion elastically contacts the screw shaft in the vertical direction;
The guide mechanism is
A drive gear provided on the drive shaft whose position is fixed;
A driven gear provided on the driven shaft whose position is fixed;
The position is fixed, and an idler shaft interposed between the driven shaft and the drive shaft;
An idler gear provided on the idler shaft and meshing with both the drive gear and the driven gear;
A first guide plate provided on the idler shaft and displaceable only in a predetermined direction;
The second guide is provided on the driven shaft, and the first guide plate moves in the direction along with the first guide plate and is movable only in the direction perpendicular to the direction of movement of the first guide plate. A screw member fastening device comprising: a guide plate.   A method for manufacturing an assembly comprising the step of fastening a nut and a screw shaft using the screw member fastening device according to any one of claims 1 and 2.

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