JP2011212766A - Method and device for press-fitting bushing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control a slant of a bushing with respect to a member to be press-fitted when the bushing is press-fitted into the member.SOLUTION: There is provided a method for press-fitting a bushing that press-fits an elastically deformable bushing 1 into holes 2b, 3b of eyes 2a, 3a of a shock absorber 10. The method includes: a preliminary press step of elastically deforming the bushing 1 in a radial direction by applying pressure to the bushing 1; and a press-fitting step of press-fitting the bushing 1 that is restored to an original form from elastic deformation caused in the preliminary press step into the holes 2b, 3b of the eyes 2a, 3a by elastically re-deforming the bushing in the radial direction.

Description

  The present invention relates to a bush press-fitting method and a bush press-fitting device.

  Conventionally, as a method of press-fitting a rubber bush into a circular hole formed in a press-fitted member, the bush is pressed in the axial direction while being elastically deformed in the radial direction by applying a high pressure to the bush. A method for eliminating the bias of the bush by pushing the bush back in the reverse direction is known.

  Patent Literature 1 discloses a vibration press-fitting machine that can reduce the pressure applied to elastically deform the bush by applying low-frequency vibration in the press-fitting direction to the bush and the press-fitting target component.

JP 2004-160612 A

  However, in the conventional press-fitting method described above, there is a risk that the bushing may change in posture when it is press-fitted into the press-fitting target part.

  The present invention has been made in view of the above-described problems, and an object thereof is to suppress the inclination of the bush with respect to the press-fit member when the bush is press-fit into the press-fit member.

  The present invention is a bush press-fitting method for press-fitting an elastically deformable bush into a circular hole of a press-fitted member, wherein a pre-compression step of applying pressure to the bush and elastically deforming the bush in a radial direction; A press-fitting step of press-fitting the bush restored from the elastic deformation in the pre-compression step into the hole while elastically deforming the bush again in the radial direction.

  In the present invention, the bush is elastically deformed in the radial direction in the pre-compression step, and then the bush restored from the elastic deformation is press-fitted into the hole of the press-fit member while being elastically deformed in the radial direction again in the press-fitting step. Therefore, since minute strains due to elastic deformation in the pre-compression process remain in the bush, the bush is easily elastically deformed uniformly in the press-fitting process and can uniformly absorb the force acting on the bush during press-fitting. Therefore, the change in the posture of the bush during press-fitting can be suppressed, and the inclination of the bush with respect to the press-fitted member can be suppressed.

(A) is a front view of the shock absorber into which a bush is press-fitted by the bush press-fitting method according to the embodiment of the present invention, and (b) is a side view in FIG. 1 (a). It is the figure which showed the side surface of the bush press-fit apparatus which concerns on embodiment of this invention in the cross section. (A) to (d) is a diagram showing a bush press-fitting method according to an embodiment of the present invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, a shock absorber 10 as a press-fit member into which the bush 1 is press-fitted will be described with reference to FIGS. In FIG. 1B, the eyes 2a and 3a and the press-fitted bush 1 are shown in cross section for easy understanding.

  The shock absorber 10 is interposed between a vehicle body and an axle of a vehicle such as an automobile, and has a function of suppressing a change in vehicle body posture. The shock absorber 10 can move forward and backward in the cylinder tube 2 and the cylinder tube 2. It is a cylinder apparatus provided with the rod 3 inserted in. The shock absorber 10 exerts a damping force due to the resistance generated when the working fluid in the cylinder tube 2 passes through the damping portion as the rod 3 advances and retreats in the cylinder tube 2. In addition to the shock absorber 10, an actuator such as a fluid pressure cylinder that moves a piston fixed to the rod by supplying and discharging a working fluid to and from the cylinder body and moves a load by moving the piston may be used. .

  At the end of the cylinder tube 2, a cylindrical eye 2a connected to a shaft (not shown) provided outside is formed. A circular hole 2b is formed on the inner periphery of the eye 2a.

  A cylindrical eye 3 a connected to a shaft (not shown) provided outside is also formed at the end of the rod 3. A circular hole 3b is formed on the inner periphery of the eye 3a.

  An elastically deformable bush 1 is press-fitted into the holes 2b and 3b of the cylinder tube 2 and the rod 3, respectively.

  The bush 1 includes a metal inner cylinder 1a and an annular rubber portion 1b bonded to the outer periphery of the inner cylinder 1a. A hole through which a shaft provided outside is inserted is formed on the inner periphery of the inner cylinder 1a. The bush 1 absorbs the force transmitted from the shaft provided outside by the elasticity of the rubber portion 1b bonded to the outer periphery of the highly rigid inner cylinder 1a. The bush 1 may be formed of only the rubber portion 1b without including the inner cylinder 1a. In that case, the shaft provided outside passes directly through the rubber portion 1b.

  In general, when the bush 1 is elastically deformed for the first time, the deformation of the rubber portion 1b at the time of press-fitting tends to be uneven and biased due to the solid difference. For this reason, there is a possibility that the center axis of the bush 1 may be inclined or displaced when it is press-fitted into the holes 2b and 3b.

  Next, the bush press-fitting device 100 for press-fitting the bush 1 into the eyes 2a and 3a of the shock absorber 10 will be described with reference to FIG.

  The bush press-fitting device 100 suppresses the inclination of the central axis of the bush 1 and the displacement of the bush 1 during press-fitting. Here, the case where the bush 1 is press-fitted into the eye 2a of the cylinder tube 2 will be described as an example, but the same applies to the case where the bush 1 is press-fitted into the eye 3a of the rod 3.

  The bush press-fitting device 100 includes a receiving jig 11 that supports the shock absorber 10, a pair of plungers 15 and 16 that move the shaft 1 in the axial direction while sandwiching the bush 1 from above and below in the axial direction, and pressure applied to the bush 1. And a second jig 22 for press-fitting into the eye 2a while elastically deforming the bush 1 that has passed through the first jig 21 again in the radial direction. Is provided.

  The plunger 15 is a push rod whose tip 15 a is inserted into the inner cylinder 1 a from the upper part of the bush 1. The outer diameter of the plunger 15 is formed smaller than the smallest part of the inner diameters of the first jig 21 and the second jig 22. The outer diameter of the tip 15a is formed substantially the same as the inner diameter of the inner cylinder 1a of the bush 1. The plunger 15 is urged in the axial direction toward the eye 2a by an electric actuator (not shown). Instead of the electric actuator, it may be energized by fluid pressure such as air pressure or hydraulic pressure.

  The plunger 16 is a push rod provided to face the plunger 15 in the axial direction. The plunger 16 has a tip 16 a inserted into the inner cylinder 1 a from the lower part of the bush 1, and sandwiches the bush 1 together with the plunger 15. The outer diameter of the plunger 16 is formed smaller than the smallest part of the inner diameters of the first jig 21 and the second jig 22. The outer diameter of the tip 16a is formed substantially the same as the inner diameter of the inner cylinder 1a of the bush 1.

  The plunger 16 is biased in the axial direction toward the eye 2a by air pressure. The biasing force of the plunger 16 is adjusted according to the magnitude of the air pressure. The plunger 16 is energized by air pressure, but may be energized by other fluid pressure such as oil pressure, or may be energized using an electric actuator or the like.

  The plungers 15 and 16 move in the axial direction while sandwiching the bush 1 from both axial ends. Since the distal ends 15 a and 16 a of the plungers 15 and 16 are inserted into the inner cylinder 1 a of the bush 1, the central axis of the bush 1 coincides with the central axis of the plungers 15 and 16. Therefore, when the bush 1 is sandwiched between the plungers 15 and 16, the inclination of the bush 1 is suppressed.

  The receiving jig 11 is formed in a substantially cylindrical shape, and a receiving surface 11a facing the eye 2a of the shock absorber 10 is formed. The eye 2a is placed on the receiving surface 11a so that the central axis of the hole 2b and the central axis of the receiving jig 11 coincide. A plunger 16 is inserted through the inner periphery of the receiving jig 11. A first jig 21 and a second jig 22 are provided above the receiving jig 11.

  The first jig 21 is formed in a substantially cylindrical shape into which plungers 15 and 16 that advance and retreat in the axial direction can be inserted through the inner periphery. The first jig 21 is provided integrally with the second jig 22 so as to be movable in the axial direction.

  An opening into which the bush 1 is inserted is formed on the inner periphery of the first jig 21, and is formed continuously with an equal diameter portion 21a having a constant inner diameter and an equal diameter portion 21a, and approaches the eye 2a. As a result, a tapered portion 21b having a smaller inner diameter is formed.

  The equal-diameter portion 21 a has an inner diameter slightly larger than the outer diameter of the bush 1 and has an axial length that is substantially the same as the axial length of the bush 1. The constant diameter portion 21a is formed with a lubricant supply hole 21c penetrating the outer periphery and the inner periphery, and a lubricant applicator 31 is provided there.

  The lubricant applicator 31 is a device that discharges and applies a lubricant to the outer periphery of the bush 1. The lubricant is soapy water or rubber processing oil that does not deteriorate the rubber part 1b.

  The tapered portion 21 b is formed such that the maximum inner diameter portion is larger than the outer diameter of the bush 1 and the minimum inner diameter portion is smaller than the outer diameter of the bush 1. When the bush 1 passes, the taper portion 21b applies elastic pressure to the rubber portion 1b to be elastically deformed. The bush 1 that has passed through the tapered portion 21b temporarily retains minute strain due to elastic deformation in the rubber portion 1b. Before the minute strain is completely restored, the bush 1 is transferred to the inner periphery of the second jig 22 by the plungers 15 and 16.

  The second jig 22 is formed in a substantially cylindrical shape into which plungers 15 and 16 that advance and retreat in the axial direction can be inserted through the inner periphery. The second jig 22 is disposed below the first jig 21 and is placed on the upper part of the eye 2 a of the shock absorber 10. That is, the second jig 22 is disposed between the first jig 21 and the eye 2a.

  At this time, the guide 25 formed at the end of the second jig 22 is inserted into the hole 2b of the eye 2a. Thus, the eye 2a is fixed in the axial direction and the radial direction by the second jig 22 and the receiving jig 11. The second jig 22 is provided so as to be movable in the axial direction together with the first jig 21.

  An opening into which the bush 1 is inserted is formed on the inner periphery of the second jig 22, and is formed continuously with an equal diameter portion 22a having a constant inner diameter and an equal diameter portion 22a, and approaches the eye 2a. As a result, a tapered portion 22b having a smaller inner diameter is formed.

  The equal-diameter portion 22 a has an inner diameter slightly larger than the outer diameter of the bush 1 and has an axial length that is substantially the same as the axial length of the bush 1. When the bush 1 that moves due to the pressing of the plungers 15 and 16 is positioned at the equal diameter portion 22 a, the rubber portion 1 b of the bush 1 is restored from the elastic deformation by the tapered portion 21 b of the first jig 21.

  The constant diameter portion 22a is formed with a lubricant supply hole 22c penetrating the outer periphery and the inner periphery, and a lubricant applicator 32 is provided there. The lubricant applicator 32 has the same configuration as the lubricant applicator 31.

  The taper portion 22b is formed so that the maximum inner diameter portion is larger than the outer diameter of the bush 1 and the minimum inner diameter portion is smaller than the outer diameter of the bush 1, similarly to the taper portion 21b. The tapered portion 22b is configured to elastically deform the rubber portion 1b by applying a pressure in the radial direction when the bush 1 moving by pressing of the plungers 15 and 16 passes. In the rubber part 1b of the bush 1, minute strains due to elastic deformation when passing through the tapered part 21b of the first jig 21 remain. Therefore, the rubber part 1b can be easily elastically deformed by passing the taper part 22b. Before the elastic deformation is fully recovered, the bush 1 is press-fitted into the hole 2b of the eye 2a by the plungers 15 and 16.

  A guide 25 that is an annular protrusion is formed at the lower end of the second jig 22. The guide 25 is formed so that its outer periphery is substantially the same as the inner periphery of the hole 2b, and the inner periphery is continuous with the same diameter as the minimum inner diameter portion of the tapered portion 22b.

  The lower end 25a of the guide 25 is inserted into the hole 2b when the second jig 22 is placed on the upper part of the eye 2a. The lower end 25a of the guide 25 is formed with a predetermined thickness of, for example, about 1 mm in order to contact and regulate the axial position when the bush 1 is pushed back by the plunger 16 after the bush 1 is press-fitted into the eye 2a. Is done. The axial length of the guide 25 is set according to the axial position of the bush 1 with respect to the eye 2a.

  The guide 25 is formed only on the second jig 22, but the guide 25 may be formed on the first jig 21 to have the same shape as the second jig 22. If the 1st jig | tool 21 and the 2nd jig | tool 22 are formed in the same shape, cost can be reduced rather than the case where it forms in a different shape. Moreover, although the 1st jig | tool 21 and the 2nd jig | tool 22 are formed in a different body, you may form these integrally.

  Hereinafter, a bush press-fitting method using the bush press-fitting device 100 will be described with reference to FIGS. Here, the case where the bush 1 is press-fitted into the eye 2a of the cylinder tube 2 will be described as an example, but the case where the bush 1 is press-fitted into the eye 3a of the rod 3 is the same as below.

  In FIG. 3, for ease of understanding, the process is illustrated separately for each process. However, in the processes of FIGS. 3A to 3C, the operations of the plungers 15 and 16 are not stopped halfway. , One continuous stroke.

  First, as shown in FIG. 2, the eye 2a of the shock absorber 10 is placed on the upper portion of the receiving jig 11, and the eye 2a is cured by moving the first jig 21 and the second jig 22 in the axial direction. It is clamped between the tool 11 and the second jig 22 and fixed. Further, the plunger 16 is moved in the axial direction by air pressure, and is positioned so that the tip 16 a faces the equal diameter portion 21 a of the first jig 21. In this state, the bush 1 is inserted into the equal diameter portion 21 a of the first jig 21. The bush 1 is placed on the end of the plunger 16, and the tip 16 a of the plunger 16 is inserted into the inner cylinder 1 a of the bush 1.

  Next, as shown in FIG. 3A, the plunger 15 is moved in the axial direction by the electric actuator, and the tip 15 a is inserted into the inner cylinder 1 a of the bush 1. In this state, the bush 1 is sandwiched between the plungers 15 and 16, and the central axis is prevented from being inclined. At this time, the lubricant is applied to the outer periphery of the rubber portion 1 b of the bush 1 by the lubricant applicator 31. This step corresponds to the first lubricant application step.

  Next, as shown in FIG. 3B, the plunger 15 is driven by an electric actuator to move the bush 1 in the axial direction and pass through the tapered portion 21 b of the first jig 21. As a result, the bush 1 is compressed in the radial direction under pressure. This process corresponds to the preliminary compression process. Since the lubricant is applied to the outer periphery of the bush 1 before the pre-compression step, the bush 1 can smoothly pass through the tapered portion 21b.

  At this time, the plunger 16 is also urged in the opposite direction to the plunger 15 by air pressure. However, since the urging force of the plunger 16 at this time is smaller than the urging force of the plunger 15, the plunger 16 is pushed back by the plunger 15.

  The rubber part 1b of the bush 1 is elastically deformed in the radial direction by passing through the tapered part 21b. When the bush 1 passes through the tapered portion 21b and faces the equal-diameter portion 22a of the second jig 22, the rubber portion 1b tries to return to its original state after being elastically deformed, but the rubber portion 1b is elastically deformed. As a result, a minute strain remains inside. At this time, the lubricant is applied to the outer periphery of the rubber portion 1 b of the bush 1 by the lubricant applicator 32. This step corresponds to the second lubricant application step.

  The lubricant is once applied to the outer periphery of the bush 1 by the lubricant applicator 31, but is scraped off by sliding contact with the tapered portion 21b when passing through the tapered portion 21b of the first jig 21. . Therefore, the lubricant is applied again by the lubricant applicator 32 before passing through the tapered portion 22 b of the second jig 22.

  Next, as shown in FIG. 3 (c), the plunger 15 is driven by an electric actuator to move the bush 1 in the axial direction and pass the tapered portion 22 b of the second jig 22. As a result, the rubber portion 1b of the bush 1 restored from the elastic deformation in the preliminary compression step is compressed again in the radial direction. At this time, the plunger 16 is also urged by air pressure, but the plunger 16 is pushed back because it is smaller than the urging force of the plunger 15.

  The plunger 15 is driven as it is, and the bush 1 in which the rubber portion 1b is elastically deformed in the radial direction is press-fitted into the hole 2b of the eye 2a. This process corresponds to the press-fitting process. Since the bush 1 is pushed into the hole 2b before the elastic deformation of the rubber portion 1b in the taper portion 22b is not completely restored, the bush 1 can be easily press-fitted. Further, since the lubricant is applied to the outer periphery of the rubber portion 1b of the bush 1 before the press-fitting step, the bush 1 is press-fitted through the tapered portion 22b smoothly.

  Here, a comparison is made with a case where the bush 1 is press-fitted into the eye 2a using only the second jig 22 without using the first jig 21.

  When the bush 1 is press-fitted into the eye 2a using only the second jig 22, the rubber portion 1b of the bush 1 is elastically deformed only at the tapered portion 22b. Therefore, the rubber portion 1b is not easily deformed by the force acting on the rubber portion 1b from the tapered portion 22b when the bush 1 passes through the tapered portion 22b, and there is a possibility that the deformation is biased. When the elastic deformation of the rubber portion 1b is biased, the central axis of the bush 1 may be inclined when the eye 2a is press-fitted. In this way, when the central axis of the bush 1 is inclined, a process for correcting it is necessary.

  On the other hand, when the first jig 21 and the second jig 22 are used, the rubber part 1b is elastically deformed in the radial direction when the bush 1 first passes through the tapered part 21b of the first jig 21. To do. Thereafter, the bush 1 restored from the elastic deformation in the taper portion 21b is press-fitted into the eye 2a while the rubber portion 1b is elastically deformed again in the radial direction by the taper portion 22b of the second jig 22.

  The rubber part 1b tries to restore the original shape after passing through the taper part 21b of the first jig 21, but a slight strain remains in the rubber part 1b due to elastic deformation once in the taper part 21b. Therefore, it is easily elastically deformed again. Therefore, the bush 1 passes through the taper portion 22b of the second jig 22 in a state where a minute strain due to elastic deformation in the first jig 21 remains inside the rubber portion 1b. The rubber part 1b is easily elastically deformed uniformly during press-fitting. Therefore, the force acting on the rubber portion 1b from the tapered portion 22b when the bush 1 is press-fitted is uniformly absorbed, the change in the posture of the bush 1 at the time of press-fitting is suppressed, and the inclination of the bush 1 with respect to the eye 2a is suppressed.

  Next, as shown in FIG. 3D, the plunger 16 is driven by air pressure to push back the bush 1 in the direction opposite to the press-fitting direction in the press-fitting process. The bush 1 is pushed back by the plunger 16 to adjust the position in the press-fitting direction (axial direction). At this time, the electric actuator that drives the plunger 15 is driven in a direction in which the plunger 15 is retracted from the eye 2a so as to match the movement of the plunger 16. This process corresponds to the pushing back process.

  The bush 1 is urged by the plunger 16 and pressed against the guide 25. When the rubber portion 1b is pressed against the guide 25, the bush 1 is accurately positioned in the press-fitting direction (axial direction) with respect to the hole 2b, and positional deviation with respect to the eye 2a is suppressed.

  After the bush 1 is press-fitted into the eye 3a of the shock absorber 10 as described above, the plunger 15 and the plunger 16 are retracted in a direction away from the eye 2a. Then, the first jig 21 and the second jig 22 are retracted upward, and the shock absorber 10 can be detached from the receiving jig 11.

  According to the above embodiment, the following effects are obtained.

  The rubber part 1b of the bush 1 is elastically deformed in the radial direction by passing through the taper part 21b of the first jig 21, and then the rubber part 1b is elastically elastic again in the radial direction by the taper part 22b of the second jig 22. The eye 2a is press-fitted while being deformed. Therefore, since minute strain due to elastic deformation in the first jig 21 remains inside the rubber part 1b, the rubber part 1b is easily elastically deformed uniformly during the subsequent press-fitting in the second jig 22, and the taper part at the time of press-fitting. The force acting on the bush 1 can be uniformly absorbed from 22b. Therefore, the posture change of the bush 1 at the time of press-fitting can be suppressed, and the inclination of the bush 1 with respect to the eye 2a can be suppressed.

  Further, after the bush 1 is press-fitted into the eye 2 a, the bush 1 is pushed back in the direction opposite to the press-fitting direction and pressed against the guide 25. As a result, the bush 1 is accurately positioned in the axial direction with respect to the hole 2b, and positional deviation with respect to the eye 2a is suppressed.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

  The present invention is not limited to a cylinder device such as a shock absorber or a fluid pressure cylinder, and can be applied to a method of press-fitting a bush into a hole.

DESCRIPTION OF SYMBOLS 100 Bush press-fit apparatus 1 Bush 1b Rubber part 2a Eye 3a Eye 10 Shock absorber 11 Receiving jig 15 Plunger 21 First jig 21b Taper part 22 Second jig 22b Taper part 25 Guide 31 Lubricant application machine 32 Lubricant application machine

Claims (7)

A bush press-in method for press-fitting an elastically deformable bush into a circular hole of a press-fit member,
A pre-compression step of applying pressure to the bush and elastically deforming the bush in a radial direction;
And a press-fitting step of press-fitting the bush restored from the elastic deformation in the preliminary compression step into the hole while elastically deforming the bush again in the radial direction.   The press-fitting step of pushing back the bush in a direction opposite to the press-fitting direction in the press-fitting step and positioning the bush at an axial position with respect to the hole after the press-fitting step. The bush press-in method described. The preliminary compression step compresses the bush in the radial direction by passing the bush through a tapered portion formed on the inner periphery of the first jig,
The said press-fitting process press-fits into the said hole, compressing the said bush to radial direction, when the said bush passes the taper part formed in the inner periphery of the 2nd jig | tool. The bush press-fitting method described in 1. A bush press-fitting device for press-fitting an elastically deformable bush into a circular hole of a press-fit member,
A moving mechanism for moving the bush in the axial direction;
A first jig that elastically deforms the bush moved by the moving mechanism in a radial direction by passing the bush;
A second jig for press-fitting into the hole by pressing of the moving mechanism, while the bush restored from the elastic deformation by the first jig is elastically deformed again in the radial direction by passing through the bush; A bush press-fitting device comprising:   The second jig contacts the bush when the bush is pushed back in the direction opposite to the press-fitting direction after the bush is press-fitted into the hole, and the bush is axially positioned with respect to the hole. The bush press-fitting device according to claim 4, further comprising a guide that performs the operation.   6. The bush press-fitting device according to claim 4, wherein each of the first jig and the second jig includes a tapered portion on an inner periphery thereof that compresses the bush in a radial direction by passing the bush. The bush comprises a hole formed along its central axis,
The bushing press-fit according to any one of claims 4 to 6, wherein the moving mechanism includes a pair of plungers whose distal ends are inserted into holes of the bush and are opposed to each other in the axial direction so as to sandwich the bush. apparatus.

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