JPH08126971A - Fastening device of fastening member - Google Patents

Abstract

PURPOSE: To obtain a stable fastening condition, and to simplify the structure and to realize a secure operation. CONSTITUTION: After the head 26A of a fastener 26 is fitted in the recess of an impact 38, the impact 38 is rotated. As a result, the fastener 26 is screwed in to a piston rod 12, and made in the condition (A). By rotating it further, a small diameter part 12A is extended in an elastic zone, and made in the condition (B). And by rotating it furthermore, the head 26A of the fastener 26 is removed from the recess 46 at the time when the extending amount of the small diameter part 12A is made coincident to the depth of the recess 46. Consequently, the fastening work is completed in a plastic area. As a result, a stable fastening condition is obtained, and since the structure is simple as in the above condition, the operation is also made secure.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a first fastening member and a second fastening member.
And a fastening member fastening device for fastening a fastened member to the fastening member.

[0002]

2. Description of the Related Art A second fastening member such as a nut or a nut-like member is screwed into a first fastening member such as a bolt or a bolt-like member to fasten a member to be fastened therebetween. The configuration of fastening is extremely common. For example, in a shock absorber of an automobile, this type of fastening method is adopted when a piston, a leaf valve, etc. are attached to the tip of a piston rod arranged in a cylinder. More specifically, a small diameter portion is formed at the tip of the piston rod, and a male screw is formed on the peripheral surface of the small diameter portion. Parts such as stopper, leaf seat (retainer), leaf valve, piston, another leaf valve, leaf seat, and stopper are inserted and arranged in this order in this small diameter part, and finally these nuts are tightened to fix these parts. are doing.

In this type of structure, the damping force characteristic of the leaf valve depends on the axial force acting on the piston rod when the nut is screwed into the piston rod. A nut is tightened precisely using a fastening device called an attachment device.

A conventional fastening device of this type has the following structure. A rotatable tool is arranged in the main body of the fastening device, and a nut is first attached to the tip of the tool. Then, the nut in this state is positioned with respect to the tip portion of the piston rod. Then, the tool is rotated to screw the nut into the tip of the piston rod.

At this time, in the conventional fastening device, the tightening torque of the nut is preset to the predetermined torque so that the predetermined damping force characteristic is obtained as described above. That is, the tool is rotated until the tightening torque of the nut reaches the predetermined torque, and the rotation of the tool is stopped when the tightening torque reaches the predetermined torque. From this,
It can be said that the conventional fastening device maintains the fastening accuracy by managing the fastening torque of the nut.

However, in the case of a fastening device of the type that maintains fastening accuracy by controlling the fastening torque, the following problems occur. That is, in the case of torque management, the tightening torque is generally set so that the tightening is completed within the elastic deformation range of the rod, and if the actual tightening torque deviates from the set torque for some reason, the piston rod is The acting axial force also changes. If foreign matter adheres to the male thread part of the small diameter part of the piston rod or the female thread part of the nut, the friction coefficient changes due to the presence of foreign matter, although the set torque is applied. The axial force acting on changes. For the above reason, in the case of torque management, the axial force acting on the piston rod is not stable, which may cause quality variations among products. Although the variation itself is actually slight, there is a demand to obtain a predetermined damping force characteristic uniformly among products.

As a structure taking this point into consideration, Japanese Patent Laid-Open No.
The structure disclosed in JP-A-111100 can be mentioned. According to the configuration disclosed in this publication, the yield start point of the bolt is detected, and the operation of the tool is controlled to stop at a predetermined point in the plastic deformation region of the bolt.
Therefore, the structure disclosed in this publication can be said to be a fastening device by torque management, but since the rotation of the tool is controlled to stop in the plastic deformation area of the bolt, compared to the case where the tool is stopped in the elastic deformation area. A stable fastening state can be obtained.

However, in the case of the structure disclosed in this publication, it is not easy to secure reliability because the circuit structure is complicated. Further, since the bolt yielding start point is detected and the rotation of the tool is stopped based on this point, high detection accuracy is required, and there are disadvantages such as variation between products due to error in detection torque. is there.

In view of the above facts, it is an object of the present invention to provide a fastening device for fastening members which can obtain a stable fastening state, and can simplify the construction and ensure the operation.

[0010]

According to the present invention, a first fastening member such as a nut or a nut-shaped member is fitted into a recess provided at the end of a rotatable tool, and the tool is rotated in this state. A fastening member fastening device that fastens a fastened member between the first fastening member and the second fastening member by screwing the first fastening member onto a second fastening member such as a bolt or a bolt-shaped member. When the screwing amount of the first fastening member into the second fastening member reaches a predetermined amount corresponding to the plastic deformation region of the second fastening member, the rotational force is transmitted to the first fastening member. It is characterized in that a transmission path blocking means for mechanically blocking the path is provided.

[0011]

According to the above construction, until the screwing amount of the first fastening member with respect to the second fastening member reaches the predetermined amount corresponding to the plastic deformation region of the second fastening member, the first fastening member is applied to the first fastening member. Since the rotational force transmission path of is not cut off, the rotational movement of the tool is maintained. Then, when the screw-in amount reaches the predetermined amount, the rotational force transmission path to the first fastening member is mechanically cut off by the transmission path cutoff means. Therefore, the first fastening member cannot rotate any further. By the above operation, the member to be fastened is fastened between the first fastening member and the second fastening member.

That is, according to the present invention, the screwing amount of the first fastening member with respect to the second fastening member (in other words, the relative position of the first fastening member with respect to the second fastening member) is the first The fastening state by the fastening member and the second fastening member is managed. Therefore, even if foreign matter or the like adheres to the screw portion of the first fastening member or the second fastening member, a uniform fastening state can be obtained without being affected by this.
Moreover, since the screwing of the first fastening member is stopped in the plastic deformation region of the second fastening member, the axial force acting on the second fastening member is also stable.

Further, according to the present invention, since the rotational force transmission path to the first fastening member is mechanically cut off by the transmission path cutoff means, the structure is simplified as compared with the case of a complicated circuit structure. As a result, reliable operation can be obtained.

[0014]

【Example】

[First Embodiment] The first embodiment will be described below with reference to FIGS.

FIG. 3 shows a main portion of the shock absorber, which is a constituent element of an automobile suspension, except for a cylinder. As shown in this figure, a small diameter portion 12A having a male screw formed on its peripheral surface is formed at the tip of the piston rod 12 inserted and arranged inside the cylinder. In the small diameter portion 12A of the piston rod 12,
Stopper 14, leaf seat 16, leaf valve 18,
Piston 20, leaf valve 21, leaf seat 22,
Parts such as the spring seat 23 and the coil spring 24 (these parts correspond to the "fastened member" in the present invention according to claim 1) are mounted in this order, and the fixing tool 26 is screwed in after mounting these parts. Has been done.

The structure of each component will be briefly described below. Annular grooves 28 and 30 are formed in the upper end surface and the lower end surface of the piston 20, respectively. In addition, the piston 20 has a port 32 that communicates the upper and lower concave grooves 28 and 30.
And port 3 that connects the piston upper chamber and the piston lower chamber
4 are formed. Further, a recess 36 is formed in the lower portion of the piston 20, and a leaf valve 21, a leaf seat 22, a spring seat 23 having a hat-shaped cross section, and a closing direction of the leaf valve 21 via the spring seat 23 are formed in the recess 36. A coil spring 24 for urging and pressing is provided. As a result, the leaf valve 18 elastically deforms to open the port 34 during the contracting stroke, and the leaf valve 21 opens the port 32 against the biasing force of the coil spring 24 during the expanding stroke. The fixture 26 that fastens the above-described components includes a head 26A having a diameter larger than the diameter of the coil spring 24,
The head portion 26A includes a shaft portion 26B that bulges from the shaft core portion and has a diameter reduced in the middle. A female screw is formed on the inner peripheral surface of the shaft portion 26B.

The fixture 26 described above is attached to the piston rod 12
The device for fastening to the small diameter portion 12A is the fastening device for the fastening member, which will be described below.

FIG. 2 shows an impact 38 as a tool which is a main part of a fastening device for fastening members. In addition,
2A is a plan view of the impact 38, and FIG. 2B is a vertical cross-sectional view of the impact 38.

As shown in this figure, the impact 38
Has a rod-shaped support shaft 40. A base portion 42 for receiving a driving force from a motor is formed at a lower end portion of the support shaft 40, and a swivel portion 44 having a larger diameter than the head portion 26A of the fixture 26 is formed at an upper end portion of the support shaft 40. Has been formed. A concave portion 46 is formed on the upper end surface of the turning portion 44. Figure 2
As shown in (A), the planar shape of the recess 46 is a substantially regular hexagon, which matches the planar shape of the head 26A of the fixture 26. Further, the depth h of the recess 46 is set to be larger than the wall thickness dimension h ′ (see FIG. 3) of the head 26A of the fixture 26 by a predetermined amount.

Below, the piston rod 12 of the fixture 26
The operation of the present embodiment will be described while explaining the procedure of screwing into.

First, the small diameter portion 12A of the piston rod 12
Stopper 14, leaf seat 16, leaf valve 1
8, piston 20, leaf valve 21, leaf seat 2
Install parts such as 2. Next, impact 38
The head 26A of the fixture 26 is fitted into the recess 46 of the.
Next, the coil spring 24 is wound around the outer peripheral portion of the shaft portion 26B of the fixture 26, and the spring seat 23
Is loosely fitted. Next, the small diameter portion 1 of the piston rod 12
2A and the shaft portion 26B of the fixture 26 are positioned coaxially.
Then, an operation switch (not shown) is turned on to drive the motor. As a result, the impact 38 rotates around the axis to screw the fixture 26 into the small diameter portion 12A of the piston rod 12.

Here, the piston rod 12 of the fixture 26
The state of screwing into the small diameter portion 12A will be described in detail. First,
As shown in FIG. 1 (A), when the impact 38 is rotated, the screwing amount of the fixture 26 is the first predetermined amount (that is,
The screwing amount when the end surface of the small diameter portion 12A reaches the end surface of the head portion 26A of the fixture 26 is reached. In this state, both of the end surface of the small diameter portion 12A of the piston rod 12 and the end surface of the head portion 26A of the fixture 26 have the recesses 4 of the impact 38.
It is in contact with the bottom surface of 6. Further, the head 2 of the fixture 26
The outer peripheral surface of 6A is also in contact with the inner peripheral surface of the recess 46 of the impact 38. Therefore, in this state, when the impact 38 is rotated, the rotational force of the impact 38 is transmitted to the fixture 26. When the state shown in FIG. 1 (A) is viewed in the graph shown in FIG. 4, the state is located at the origin, and the small diameter portion 12A is not deformed. In addition, this graph is
The vertical axis represents the axial force acting on the piston rod 12 when the horizontal axis represents the amount of extension of the small diameter portion 12A of the piston rod 12.

Next, as shown in FIG. 1B, the impact 38 is further rotated. As a result, the fixture 2
Since 6 is further screwed, the small diameter portion 12A of the piston rod 12 elastically deforms and extends. Therefore, the end surface of the small diameter portion 12A of the piston rod 12 is attached to the head 2 of the fixture 26.
It is located below the end face of 6A. Therefore, the fixture 2
The end surface of the head portion 26A of 6 is separated from the bottom surface of the recess 46 of the impact 38, and only the end surface of the small diameter portion 12A is in contact with the bottom surface of the recess 46. At this point, the outer peripheral surface of the head portion 26A of the fixture 26 is still in contact with the inner peripheral surface of the recess 46, and the fitting state is maintained. This Figure 1
When the state shown in FIG. 4B is viewed in the graph shown in FIG. 4, the small diameter portion 12A of the piston rod 12 extends in the elastic deformation region.

Next, as shown in FIG. 1C, the impact 38 is further rotated. As a result, the fixture 2
6 is the second predetermined amount (that is, the piston rod 12
Of the small diameter portion 12A reaches the depth h of the recess 46). The second predetermined amount is
This corresponds to the "predetermined amount" in the present invention according to claim 1.
In this case, the outer peripheral surface of the head 26A of the fixture 26 is no longer
The inner peripheral surface of the recess 46 is disengaged. Therefore, even if the impact 38 is rotated in this state, the rotational force applied to the impact 38 is not transmitted to the fixture 26. That is, the rotational force transmission path from the impact 38 to the fixture 26 is mechanically cut off, and the impact 38 idles. As you can see from this,
In the present embodiment, the recess 46 functions as the "transmission path blocking means" in the present invention according to claim 1. In this state, the operation switch is turned off and the impact 3
The rotation of 8 is stopped. When the state shown in FIG. 1C is viewed in the graph shown in FIG. 4, the piston rod 12
The amount of extension of the small diameter portion 12A has reached the plastic deformation region, and in this embodiment, it is set so as to fall within the range of the section A in which the axial force acting on the piston rod 12 is stable.

As a result of the above, the stopper 1 is provided between the small diameter portion 12A of the piston rod 12 and the head portion 26A of the fixture 26.
4, leaf seat 16, leaf valve 18, piston 2
Components such as 0, leaf valve 21, leaf seat 22, spring seat 23, and coil spring 24 are fastened.

Thus, in this embodiment, the impact 38
By setting the depth h of the concave portion 46 formed in the swivel portion 44 to a predetermined depth, the extension amount of the small diameter portion 12A of the piston rod 12 reaches the plastic deformation region and the axial force acting on the piston rod 12 is reached. Since the screwing amount of the fixing tool 26 is set to the second predetermined amount within which the section A is stable, in other words, the fastening state is managed by the screwing amount of the fixing tool 26. Even if foreign matter or the like adheres to the shaft portion 26B of the fixture 26, it is possible to obtain a uniform fastening state without being affected by this and to stabilize the axial force acting on the piston rod 12. You can As a result,
It is possible to prevent the damping force characteristics of the shock absorber from varying among products.

Further, in this embodiment, the piston rod 1
The amount of extension of the small diameter portion 12A of 2 is the concave portion 46 of the impact 38.
At a time point corresponding to the depth h of the above, the engagement state between the recess 46 and the head 26A of the fixture 26 is mechanically and forcibly released, and the rotational force transmission path from the impact 38 is cut off. Therefore, the structure can be simplified and the operation can be ensured as compared with the case where the circuit configuration is complicated. [Second Embodiment] A second embodiment will be described below with reference to FIGS. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

FIG. 9 schematically shows the overall structure of the fastening device for fastening members according to this embodiment. As shown in this figure, the fastening device for fastening members includes a substantially L-shaped housing 50, and the lower portion of the impact 52 is accommodated in the housing 50. In addition, impact 52
The upper part of the is projected to the outside of the housing 50.

The impact 52 according to the present embodiment has a different structure from the impact 38 of the first embodiment described above, and the impact main body 54 and the push rod 56 constitute the main part. The impact body 54 is the above-mentioned first
As in the embodiment, the turning portion 44 having the recess 46 is provided. Further, the intermediate portion and the lower end portion of the impact body 54 are axially supported by ball bearings 58, respectively.
Further, a brush 60 is provided in the middle of the impact body 54, and a coil 62 is provided on the lower peripheral surface. Corresponding to this, the iron core 64 and the coil 66 are also provided inside the housing 50 (see FIGS. 7 and 8). Further, a normally closed first switch 68 is provided on the conductor of the coil 66 corresponding to the stator, and the first switch 68 is a push rod 5 described later.
It is arranged below 6. In addition, one brush 60
A second switch 70 for power supply is arranged on the lead wire connected to. 6 is a schematic circuit diagram of the above configuration, and FIG. 7 is a schematic connection diagram. Note that, in FIG. 6, the symbol M meaning a motor corresponds to the impact 52 here.

On the other hand, a through hole 72 is formed in the shaft core of the impact body 54, and the push rod 56 is accommodated in the through hole 72 so as to be relatively movable. In the initial state, the tip surface of the push rod 56 is located slightly below the bottom surface of the recess 46 of the impact body 54 (see FIG. 5A). The above-described first switch 68 is disposed at the lower end of the push rod 56, and the first switch 68 is turned off when the push rod 56 moves downward relative to the push rod 56.

According to the above structure, as shown in FIG. 5 (A), after the head 26A of the fixture 26 is fitted into the recess 46 of the impact body 54, the second switch 70 is turned on to rotate. The child impact body 54 rotates. As a result, the fixture 26 causes the small diameter portion 12 of the piston rod 12 to
It is screwed into A. As shown in FIG. 5B, when the screwing amount of the fixture 26 reaches the second predetermined amount, the small diameter portion 12A of the piston rod 12 extends and the tip end portion of the push rod 56 is pressed downward. As a result, the push rod 56 relatively moves downward to turn off the first switch 68. That is, the rotational force transmission path from the impact body 54 to the fixture 26 is mechanically and forcibly blocked by the push rod 56, and the rotation of the impact body 54 is stopped.

Therefore, also in this embodiment, the fixture 26
Since the fastening state is controlled by the screwing amount of
Even if foreign matter or the like adheres to the shaft portion 26B of the fixing tool 26, it is possible to obtain a uniform fastening state without being affected by the foreign matter and to stabilize the axial force acting on the piston rod 12. be able to.

Also in this embodiment, when the amount of extension of the small diameter portion 12A of the piston rod 12 reaches a predetermined amount, the push rod 56 mechanically and forcibly turns off the first switch 68 for rotation. Since the force transmission path is cut off, the structure can be simplified and the operation can be ensured as compared with the case where the circuit configuration is complicated.

In the embodiment described above, the first fastening member is the fixing member 26 which is a nut-shaped member, and the second fastening member is the piston rod 1 which is a bolt-shaped member.
However, the present invention is not limited to this, and the present invention can be applied to the case where a normal nut is fastened to a normal bolt.

Further, in the second embodiment, the push rod 5
When 6 is pressed by the small diameter portion 12A of the piston rod 12 and moves relatively, the first switch 68 is turned off and the rotation of the impact body 54 is stopped. However, the configuration is not limited to this, and the push rod 56 has a small diameter. When it is pressed by the portion 12A, the air is released and the torque drops, and the impact body 5
The rotation of 4 may be stopped.

According to the present invention as set forth in claim 1, "when the screwing amount of the first fastening member with respect to the second fastening member reaches a predetermined amount corresponding to the plastic deformation region of the second fastening member. And a release means for mechanically releasing the fitting state of the first fastening member into the concave portion of the tool (the concave portion 46 corresponds to this), "corresponds to the first embodiment. It becomes an invention. In this case, the same operation and effect as the present invention according to claim 1 can be obtained. In addition, since the number of parts is not increased, it is possible to further simplify the structure and ensure the operation.

Further, the present invention according to claim 1 is the "first".
When the screwing amount of the fastening member of the second fastening member with respect to the second fastening member reaches a predetermined amount corresponding to the plastic deformation region of the second fastening member,
The tool stop means (the push rod 56 and the first switch 68 correspond to this) which presses the end of the second fastening member to mechanically stop the rotation of the tool is provided. ” The invention corresponds to the second embodiment. in this case,
The same operation and effect as the present invention according to claim 1 can be obtained.

[0038]

As described above, in the fastening device of the fastening member according to the present invention, the screwing amount of the first fastening member with respect to the second fastening member corresponds to the plastic deformation region of the second fastening member. Since the transmission path blocking means for mechanically blocking the rotational force transmission path to the first fastening member is provided when the fixed amount is reached,
It has an excellent effect that a stable fastening state can be obtained, and further, the configuration can be simplified and the operation can be ensured.

[Brief description of drawings]

FIG. 1 is an operation explanatory view for explaining a screwed state of a fixture by a fastening device for a fastening member according to a first embodiment.

FIG. 2A is a plan view of the impact, and FIG. 2B is a front view of the impact.

FIG. 3 is a vertical cross-sectional view showing a piston peripheral portion of the shock absorber.

FIG. 4 is a graph showing the axial force with respect to the extension of the piston rod.

FIG. 5 is an operation explanatory view for explaining a screwed state of the fixture of the fastening device for the fastening member according to the second embodiment.

FIG. 6 is a schematic circuit diagram of a fastening device for fastening members according to a second embodiment.

FIG. 7 is a schematic connection diagram of impact.

8 is a cross-sectional view taken along line 8-8 of FIG. 9 showing the structure of impact.

FIG. 9 is a schematic configuration diagram of a fastening device for fastening members according to a second embodiment.

[Explanation of reference numerals] 12 piston rod (second fastening member) 14 stopper (fastening member) 16 leaf seat (fastening member) 18 leaf valve (fastening member) 20 piston (fastening member) 21 leaf valve (fastening member) Fastening member 22 Leaf sheet (fastened member) 23 Spring sheet (fastened member) 24 Coil spring (fastened member) 26 Fixing tool (first fastening member) 38 Impact (tool) 46 Recessed portion (transmission path blocking means) 52 Impact (Tool) 56 Push Rod (Transmission Path Interrupting Means) 68 First Switch (Transmission Path Interrupting Means)

Claims (1)

[Claims] 1. A first fastening member such as a nut or a nut-shaped member is fitted into a recess provided in an end portion of a rotatable tool, and the tool is rotated in this state to bolt the first fastening member or A fastening member fastening device for fastening a fastened member between a first fastening member and a second fastening member by being screwed into a second fastening member such as a bolt-shaped member. The screwing amount of the member with respect to the second fastening member is the second
The fastening member is characterized in that transmission path blocking means is provided for mechanically blocking the rotational force transmission path to the first fastening member when a predetermined amount corresponding to the plastic deformation region of the fastening member is reached. Fastening device.