JP2020190272A - Stopper, stopper unit, and manufacturing method of stopper - Google Patents

Abstract

To provide a stopper capable of hardly generating abnormal noise at elongation/contraction.SOLUTION: A stopper which is attached to a bracket and formed from a cylindrical elastic body absorbing an impact due to being pressed to the contact face of the bracket and compressed in the axial direction includes: a cylindrical buffer part having an edge face in the axial direction, capable of coming in contact with the contact face; and a cylindrical fitting part projecting in the axial direction from the edge face and capable of being fitted to the bracket. The fitting part is provided with an air hole penetrating in the radial direction, the air hole is separated from a tip in the axial direction in the fitting part, at an opposite side to the buffer part, a first groove is disposed on the edge face, and the first groove extends from a position of the air hole toward the radial direction when viewed from the axial direction.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for manufacturing a stopper, a stopper unit and a stopper, and particularly to a method for manufacturing a stopper, a stopper unit and a stopper capable of making it difficult to generate an abnormal noise during expansion and contraction.

For example, a stopper formed of a tubular elastic body is placed between the cylinder of the shock absorber and the bracket fixed to the piston rod protruding from the cylinder to prevent the impact at the time of large contraction of the shock absorber. It is known to be absorbed by. The stopper includes a mounting portion that fits on the inner peripheral side of the tubular bracket, and a tubular cushioning portion that has an axial end face that is connected to the mounting portion so as to project radially outward from the mounting portion. There is something to be provided (Patent Document 1).

In Patent Document 1, a plurality of grooves are provided on the outer peripheral surface and the end surface of the mounting portion, and an air passage connecting the inside and outside of the stopper is formed between the bracket and the stopper. As a result, when the stopper is compressed in the axial direction between the cylinder and the bracket, the air inside the stopper can be discharged from the air passage to the outside of the stopper, and the generation of abnormal noise due to the compression of the air inside the stopper is suppressed. it can. Further, when the stopper is compressed in the axial direction and then expanded, the inside of the stopper becomes negative pressure and abnormal noise can be suppressed by the air passage.

European Patent Application Publication No. 269544

However, in the technique of Patent Document 1, since a long air passage that bypasses the tip of the mounting portion is formed, it is not possible to sufficiently secure the instantaneous intake / exhaust amount through the air passage when the stopper expands and contracts. However, there is a problem that the generation of abnormal noise during expansion and contraction cannot be sufficiently suppressed.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a stopper, a stopper unit, and a method for manufacturing a stopper capable of making it difficult to generate an abnormal noise during expansion and contraction.

In order to achieve this object, the stopper of the present invention is formed of a tubular elastic body that is attached to a bracket and is pressed against the contact surface of the bracket and compressed in the axial direction to absorb impact. The present invention includes a tubular cushioning portion having an axial end surface that can come into contact with the contact surface, and a tubular mounting portion that projects axially from the end surface and can be fitted to the bracket. The mounting portion is provided with an air hole penetrating in the radial direction, the air hole is separated from the axial tip of the mounting portion opposite to the buffer portion, and a first groove is provided on the end surface. The first groove extends in the radial direction from the position of the air hole when viewed from the axial direction.

The stopper unit of the present invention includes a bracket having a contact surface and a stopper formed of a tubular elastic body attached to the bracket and pressed against the contact surface to be compressed in the axial direction to absorb impact. The stopper includes a tubular cushioning portion having an axial end surface that can contact the contact surface, and a tubular mounting portion that projects axially from the end surface and fits into the bracket. The mounting portion is provided with an air hole penetrating in the radial direction, and the air hole is separated from the axial tip of the mounting portion opposite to the cushioning portion, and at least the end surface and the contact surface. A first groove is provided on one side, and the first groove extends in the radial direction from the position of the air hole when viewed from the axial direction.

The method for manufacturing a stopper of the present invention is a method for manufacturing a tubular stopper that is attached to a bracket, pressed against the contact surface of the bracket and compressed in the axial direction to absorb an impact, and is attached to the bracket. A tubular mounting portion that can be fitted, a tubular cushioning portion that has a bellows-shaped outer peripheral surface and an inner peripheral surface and is connected to the mounting portion, and a tubular mounting portion that protrudes radially outward from the outer peripheral surface of the mounting portion. A molding step of blow molding a molded body made of a thermoplastic elastoma having a protruding portion and having a concave portion from the inner peripheral surface of the mounting portion to the outside in the radial direction so that the bottom is located in the protruding portion. A cutting step of cutting the protruding portion of the molded body formed by the blow molding along the outer peripheral surface of the mounting portion and forming an air hole penetrating the mounting portion in the radial direction by the recess. To be equipped.

According to the stopper according to claim 1, even if the mounting portion is fitted to the bracket and the end surface of the cushioning portion is pressed against the contact surface of the bracket, an air hole penetrating the mounting portion in the radial direction and an air hole when viewed from the axial direction. An air passage that communicates with the inside and outside of the stopper can be provided between the stopper and the bracket by the first groove provided on the end surface of the cushioning portion in the radial direction from the position of. Further, since the air holes penetrate the mounting portion in the radial direction, the air passage can be shortened as compared with the case where the air passage bypasses the tip of the mounting portion. As a result, it is possible to increase the instantaneous intake / exhaust amount through the air passage when the stopper expands and contracts, so that it is possible to reduce the occurrence of abnormal noise when the stopper expands and contracts.

Here, if an air hole is provided up to the tip of the mounting portion and the tip of the mounting portion is divided in the circumferential direction, a part of the mounting portion that hits the contact surface bends when the mounting portion is fitted to the bracket. As a result, workability when fitting the mounting portion to the bracket deteriorates. However, since the air hole penetrates a position of the mounting portion away from the tip, workability when fitting the mounting portion to the bracket can be ensured.

According to the stopper according to claim 2, since a plurality of air holes and the first groove are provided at intervals in the circumferential direction, the amount of intake and exhaust through the air passage by the air holes and the first groove can be increased, and the stopper. It is possible to make it more difficult to generate abnormal noise when expanding and contracting. A plurality of second grooves extending in the radial direction from the mounting portion are provided between the first grooves on the end surface of the cushioning portion. As a result, when the end face of the cushioning portion is pressed against the bracket, the difference in stress applied to the end face between the portion having the first groove for forming the air passage and the portion without the first groove can be reduced. As a result, in addition to the effect of claim 1, the durability of the stopper can be improved.

According to the stopper according to claim 3, the mounting portion includes a separating portion that axially separates the air hole and the first groove. When the stopper expands and contracts, the mounting portion fitted to the bracket hardly expands and contracts, and the cushioning portion expands and contracts mainly in the axial direction, so that stress tends to concentrate on the corners between the end face of the cushioning portion and the mounting portion. Since it is possible to prevent the air holes from being provided up to this corner by the separation portion, it is possible to suppress the occurrence of cracks or the like in the stopper starting from the air holes. As a result, in addition to the effect of claim 1 or 2, the durability of the stopper can be further improved.

According to the stopper unit according to claim 4, even if the mounting portion is fitted to the bracket and the end surface of the cushioning portion is pressed against the contact surface of the bracket, the air hole penetrating the mounting portion in the radial direction and the air when viewed from the axial direction. An air passage communicating inside and outside the stopper can be provided between the stopper and the bracket by a first groove provided on at least one of the end surface and the contact surface in the radial direction from the position of the hole. Further, since the air holes penetrate the mounting portion in the radial direction, the air passage can be shortened as compared with the case where the air passage bypasses the tip of the mounting portion. As a result, it is possible to increase the instantaneous intake / exhaust amount through the air passage when the stopper expands and contracts, so that it is possible to reduce the occurrence of abnormal noise when the stopper expands and contracts. Further, since the air hole penetrates a position of the mounting portion away from the tip, workability when fitting the mounting portion to the bracket is improved as compared with the case where the tip of the mounting portion is divided in the circumferential direction. Can be secured.

According to the stopper unit according to claim 5, the first groove is provided only on the contact surface. As a result, as compared with the case where the first groove is provided on the end face of the cushioning portion, it is possible to suppress the deformation of the end face from changing in the circumferential direction due to the first groove. As a result, in addition to the effect of claim 4, the durability of the stopper can be improved.

According to the stopper unit according to claim 6, the first groove is provided at least up to both radial edges of the portion where the contact surface and the end surface of the cushioning portion face each other in the axial direction. As a result, even if the contact surface and the end surface are in close contact with each other to the maximum, an air passage that communicates inside and outside the stopper can be secured by the first groove and the air hole. As a result, in addition to the effect of claim 4 or 5, it is possible to make it more difficult to generate an abnormal noise when the stopper expands and contracts.

According to the method for manufacturing a stopper according to claim 7, in the molding step, a molded body made of a thermoplastic elastomer having a tubular cushioning portion having a bellows-shaped outer peripheral surface and an inner peripheral surface is easily formed, and thus blown. A molded body is formed by molding. Further, in the molded body formed by the molding step, the protruding portion protrudes radially outward from the outer peripheral surface of the tubular mounting portion, and the bottom is positioned in the protruding portion from the inner peripheral surface of the mounting portion to the radial outer side. A recess is provided toward the end. By cutting the protruding portion of the molded body along the outer peripheral surface of the mounting portion by the cutting step, an air hole penetrating the mounting portion in the radial direction is formed by the recess. As a result, air holes can be easily formed in the molded body formed by blow molding.

It is sectional drawing of the stopper unit in 1st Embodiment. It is a perspective view of a stopper. It is a perspective view of the molded body formed by blow molding. It is sectional drawing of the molded article in line IV-IV of FIG. It is sectional drawing of the stopper unit in 2nd Embodiment. It is sectional drawing of the stopper unit in the VI-VI line of FIG.

Hereinafter, preferred embodiments will be described with reference to the accompanying drawings. First, the stopper unit 10 and the shock absorber 1 in the first embodiment will be described with reference to FIG. FIG. 1 is a cross-sectional view of the stopper unit 10. Specifically, FIG. 1 is a cross-sectional view of a stopper unit 10 attached to the shock absorber 1, including the central axis C of the piston rod 4 of the shock absorber 1. The right side of the paper surface with respect to the central axis C of FIG. 1 shows a cross section passing through the first groove 37, and the left side of the paper surface with respect to the central axis C shows a cross section not passing through the first groove 37 and the second groove 38.

As shown in FIG. 1, the shock absorber 1 is a part of a suspension that mainly connects a wheel (not shown) and a vehicle body (not shown) and buffers vibration from the wheel to the vehicle body. The shock absorber 1 damps the vibration of a coil spring (not shown) that absorbs the shock from the wheels while supporting the vehicle body. The shock absorber 1 mainly includes a cylinder 2 attached to the wheel side and a piston rod 4 protruding from the axial end surface 3 of the cylinder 2. The shock absorber 1 expands and contracts by changing the amount of protrusion of the piston rod 4 from the cylinder 2 in accordance with the load input from the wheels, and damps the vibration.

The stopper unit 10 includes a tubular bracket 11 to which the piston rod 4 is attached, and a tubular stopper 20 attached to the cylinder 2 side of the bracket 11. The bracket 11 is formed of a cylindrical portion 12 to which the tip of the piston rod 4 is fixed, a disc portion 13 protruding radially outward from the cylindrical portion 12, and an elastic body such as rubber or a thermoplastic elastomer. An elastic portion 14 that surrounds the periphery of the 13 and a first fixture 15 and a second fixture 16 that sandwich the elastic portion 14 from the axial direction are provided.

The first fixture 15 and the second fixture 16 are metal members fixed to the vehicle body side. The first fixture 15 is a plate material located on the side opposite to the cylinder 2 with respect to the elastic portion 14. The second fixture 16 is a cylinder that surrounds and supports the cylinder 2 side and the radial outer side of the elastic portion 14.

The second fixture 16 includes an annular contact surface 17 which is an axial end surface on the cylinder 2 side, and a press-fitting surface 18 which is an inner peripheral surface from the inner peripheral edge of the contact surface 17 toward the elastic portion 14. The contact surface 17 is formed substantially perpendicular to the central axis C and faces the axial end surface 3 of the cylinder 2. The stopper 20 is axially compressed between the contact surface 17 and the axial end surface 3.

The press-fitted surface 18 is formed substantially entirely parallel to the central axis C in the cross section including the central axis C, that is, substantially perpendicular to the contact surface 17. The press-fitting surface 18 is arranged concentrically with the piston rod 4 and the cylindrical portion 12 so as to be separated from each other by a predetermined space.

A mounting portion 21 of a stopper 20, which will be described later, is press-fitted into the press-fitting surface 18. The press-fitting surface 18 is provided with a chamfering portion 18a at a corner with the contact surface 17, and a fitting recess 18b into which the claw portion 24 of the mounting portion 21 is fitted is provided substantially in the center in the axial direction. The chamfered portion 18a makes it easy to fit the stopper 20 onto the press-fitted surface 18.

The stopper 20 is a tubular member arranged between the cylinder 2 and the bracket 11 so as to surround the outer circumference of the piston rod 4. The stopper 20 has a cross section perpendicular to the central axis C formed in an annular shape centered on the central axis C. That is, the central axis C of the piston rod 4 is also the central axis of the stopper 20.

Each part of the stopper 20 is integrally formed of an elastic body such as rubber, a foamed synthetic resin, or a thermoplastic elastomer. In this embodiment, the stopper 20 is formed by a thermoplastic elastomer. When the shock absorber 1 is greatly contracted, the stopper 20 is sandwiched between the axial end surface 3 of the cylinder 2 and the contact surface 17 of the bracket 11 and is compressed in the axial direction, so that the elastic force of the stopper 20 causes compression during compression. Absorbs shock.

The stopper 20 has a substantially cylindrical mounting portion 21 configured to be press-fitted into the press-fitting surface 18 of the second fixture 16 and a cylinder connected to the axial end of the mounting portion 21 on the cylinder 2 side. It is provided with a cylindrical shock absorber 30. The mounting portion 21 includes a tip portion 23 in the axial direction opposite to the cushioning portion 30, and a claw portion 24 protruding radially outward from the outer peripheral surface on the tip end 23 side.

The claw portion 24 is a portion intermittently provided in the circumferential direction of the mounting portion 21. By fitting the claw portion 24 into the fitting recess 18b of the press-fitting surface 18, the mounting portion 21 can be made difficult to come off from the bracket 11.

The cushioning portion 30 is a portion that is compressed in the axial direction between the axial end surface 3 of the cylinder 2 and the contact surface 17 of the bracket 11 to absorb the impact. The outer peripheral surface 31 and the inner peripheral surface 32 of the buffer portion 30 are formed in a bellows shape in which a plurality of peaks and valleys are continuous in the axial direction. The peak of the outer peripheral surface 31 and the valley bottom of the inner peripheral surface 32 are at the same axial position, and the valley bottom of the outer peripheral surface 31 and the peak of the inner peripheral surface 32 are at the same axial position.

The outer peripheral surface 31 includes an axial end surface 33 connected to the outer peripheral surface of the mounting portion 21 so as to project radially outward from the mounting portion 21, and a pressure receiving surface 34 capable of contacting the axial end surface 3 of the cylinder 2. .. The end surface 33 is a surface that comes into contact with the contact surface 17 of the bracket 11 at the maximum load that is expected to be applied to the cushioning portion 30. In the present embodiment, even when the cushioning portion 30 is not compressed in the axial direction, substantially the entire end surface 33 is in surface contact with the contact surface 17 with the claw portion 24 fitted in the fitting recess 18b. The mounting portion 21 projects axially from the end surface 33. The pressure receiving surface 34 comes into close contact with the axial end surface 3 of the cylinder 2 when the shock absorber 1 is greatly contracted.

Next, the stopper 20 will be further described with reference to FIG. FIG. 2 is a perspective view of the stopper 20. As shown in FIG. 2, the mounting portion 21 is provided with four air holes 26 penetrating in the radial direction at equal intervals in the circumferential direction. Four claws 24 are provided at positions deviated from the air holes 26 in the circumferential direction. The mounting portion 21 includes a separating portion 27 that axially separates the air hole 26 and the end surface 33 of the cushioning portion 30.

The length of the air hole 26 in the circumferential direction is larger than the length in the axial direction. As a result, a large air hole 26 can be provided in the mounting portion 21 having a small axial dimension. Further, the distance between the air holes 26 in the circumferential direction is larger than the length in the circumferential direction of the air holes 26. As a result, the mechanical strength of the mounting portion 21 can be ensured.

The air hole 26 is formed at a position away from the tip 23 and penetrates the buffer portion 30 side of the claw portion 24. Here, if the air hole 26 is provided up to the tip 23 of the mounting portion 21 and the tip 23 of the mounting portion 21 is divided in the circumferential direction, the air hole 26 hits the contact surface 17 when the mounting portion 21 is fitted to the bracket 11. The mounting portion 21 may be damaged due to a part of the mounting portion 21 being bent or the like. Further, since it is necessary to work while being careful not to bend the mounting portion 21, the workability when fitting the mounting portion 21 to the bracket 11 is deteriorated. However, in the present embodiment, since the air hole 26 is provided through the position of the mounting portion 21 away from the tip 23, workability when fitting the mounting portion 21 to the bracket 11 can be ensured.

On the end surface 33 of the shock absorber 30, four linear first grooves 37 and four linear second grooves 38 are provided in a radial pattern centered on the central axis C (see FIG. 1). There is. The plurality of first grooves 37 and the second grooves 38 are arranged at equal intervals in the circumferential direction so as to be positioned alternately. The first groove 37 extends in the radial direction from the position where the position of the air hole 26 is extended in the axial direction. That is, the first groove 37 extends in the radial direction from the position of the air hole 26 when viewed from the axial direction. The second groove 38 extends in the radial direction from the mounting portion 21 at a position where there is no air hole 26.

Each of the first groove 37 and the second groove 38 has an axis from the radial inner edge of the end face 33 to the radial outer edge, that is, the contact surface 17 (see FIG. 1) between the end face 33 and the bracket 11. It is formed up to both radial edges of the portions facing in the direction. All the first groove 37 and the second groove 38 have the same shape and dimensions.

The area of the first groove 37 and the second groove 38 is smaller than the area of the end face 33 without the first groove 37 and the second groove 38. As a result, the contact area between the portion of the end surface 33 that does not have the first groove 37 and the second groove 38 and the contact surface 17 of the bracket 11 can be secured, so that the load when the end surface 33 is pressed against the contact surface 17 is dispersed. It can be made easy.

It will be described back to FIG. In a state where the mounting portion 21 of the stopper 20 is press-fitted into the press-fitting surface 18 of the bracket 11, the space on the side away from the pressure receiving surface 34 from the tip 23 of the stopper 20 is formed by the disk portion 13 and the elastic portion 14. It is closed. Therefore, when the stopper 20 contracts due to the contraction of the shock absorber 1, the air in the stopper 20 can hardly escape from the tip 23, and the pressure receiving surface 34 comes into close contact with the axial end surface 3 of the cylinder 2 and inside the stopper 20. The air is compressed with.

An abnormal noise may be generated when the compressed air tries to escape from between the pressure receiving surface 34 and the axial end surface 3. Further, after the stopper 20 is compressed, the stopper 20 expands at once, so that the inside of the stopper 20 becomes a negative pressure at the time of this expansion. Then, air tries to enter between the pressure receiving surface 34 and the axial end surface 3, or it becomes difficult for air to enter between the bellows-shaped inner peripheral surface 32 which is in close contact with the axial direction, and an abnormal noise is generated. There is.

In the present embodiment, the inside and outside of the stopper 20 are formed by an air hole 26 provided in the mounting portion 21 and a first groove 37 provided in the end surface 33 of the buffer portion 30 so as to extend radially outward from the air hole 26. An air passage for communicating with the stopper 20 can be provided between the stopper 20 and the bracket 11. As a result, it is possible to suppress abnormal noise when the stopper 20 expands and contracts.

Further, since the air hole 26 penetrates the mounting portion 21 in the radial direction, a groove is provided on the outer peripheral surface of the mounting portion 21 in the axial direction so that the air passage bypasses the tip 23 of the mounting portion 21. And the air passage can be shortened. As a result, it is possible to increase the instantaneous intake / exhaust amount through the air passage when the stopper 20 expands and contracts, so that it is possible to make it difficult to generate an abnormal noise when the stopper 20 expands and contracts.

The air hole 26 and the first groove 37 are axially separated by a separation portion 27 and are not directly connected to each other. Here, when the stopper 20 expands and contracts, the mounting portion 21 fitted to the bracket 11 hardly expands and contracts, and the cushioning portion 30 expands and contracts mainly in the axial direction. Therefore, the end surface 33 of the cushioning portion 30 and the outer peripheral surface of the mounting portion 21 Stress tends to concentrate in the corners of. Since it is possible to prevent the air holes 26 from being provided up to this corner by the separation portion 27, it is possible to suppress the occurrence of cracks or the like in the stopper 20 starting from the air holes 26. As a result, the durability of the stopper 20 can be further improved.

At the corner between the outer peripheral surface of the mounting portion 21 and the end surface 33 of the cushioning portion 30, an air passage through the air hole 26 and an air passage through the first groove 37 are provided between the chamfered portion 18a of the press-fitting surface 18. A part of the air passage connecting the two is formed. Since the upper end of the chamfered portion 18a away from the contact surface 17 is located above the lower end of the air hole 26 on the end surface 33 side, the first groove 37 between the contact surface 17 and the end surface 33 is formed. The air passage and the air passage provided by the air hole 26 can be easily communicated with each other.

As a result, the amount of intake and exhaust when the stopper 20 is expanded and contracted can be increased, so that abnormal noise when the stopper 20 is expanded and contracted can be made less likely to occur. Even if there is no chamfered portion 18a and the corners of the outer peripheral surface and the end surface 33 of the mounting portion 21 are in close contact with the corners of the press-fitted surface 18 and the contact surface 17, the air holes 26 and the first groove 37 are used. The pressure of the air passing through the air passage allows the air passage through the first groove 37 and the air passage through the air hole 26 to communicate with each other.

Since the chamfered portion 18a is provided on the entire circumference of the press-fitted surface 18, the air passage formed by the chamfered portion 18a can be communicated with the space provided by the contact surface 17 and the second groove 38. As a result, the space formed by the contact surface 17 and the second groove 38 can be made a part of the air passage that communicates inside and outside the stopper 20, so that the amount of intake and exhaust through the air passage can be increased, and the stopper 20 can be expanded and contracted. It is possible to make it less likely to generate abnormal noise. Further, since the flow path cross-sectional area of the air passage by the air hole 26 is larger than the flow path cross-sectional area of the air passage by the first groove 37, when the second groove 38 is used as an air passage, intake and exhaust through the air passage The amount can be further increased, and abnormal noise when the stopper 20 is expanded and contracted can be further reduced.

Since the first groove 37 and the second groove 38 are formed up to both ends in the radial direction of the portion where the contact surface 17 of the bracket 11 and the end surface 33 of the cushioning portion 30 face each other in the axial direction, the contact surface 17 and the end surface are formed. Even if the 33 is in close contact with the maximum, an air passage that communicates with the inside and outside of the stopper 20 can be secured by the first groove 37 and the air hole 26. As a result, it is possible to make it more difficult to generate an abnormal noise when the stopper 20 expands and contracts.

Since a plurality of air holes 26 and the first groove 37 are provided in the circumferential direction, the amount of intake and exhaust through the air passages of the air holes 26 and the first groove 37 can be increased, and abnormal noise is generated when the stopper 20 expands and contracts. It can be difficult. Further, since the plurality of air holes 26 and the first groove 37 are arranged at equal intervals in the circumferential direction, the stress received by the end face 33 from the air passing through the air passage by the air holes 26 and the first groove 37 is uniformly applied in the circumferential direction. You can get closer. As a result, the durability of the stopper 20 can be improved.

Since a plurality of second grooves 38 are provided between the first grooves 37, when the end surface 33 is pressed against the contact surface 17, a portion mainly having the first groove 37 for forming an air passage and a portion without the first groove 37 are provided. The difference in stress received by the end face 33 at and is small. Thereby, the durability of the stopper 20 can be further improved. Further, since the first groove 37 and the second groove 38 are alternately arranged at equal intervals, the stress received by the end face 33 can be made uniform in the circumferential direction, and the durability of the stopper 20 can be further improved.

Since the first groove 37 forming an air passage between the contact surface 17 of the bracket 11 and the end surface 33 of the cushioning portion 30 is formed on the end surface 33, the case where the first groove 37 is provided on the contact surface 17 Therefore, it is possible to eliminate the need for the alignment of the air hole 26 and the first groove 37 in the circumferential direction. Further, even if the stopper 20 rotates with respect to the bracket 11 after the stopper 20 is assembled to the bracket 11, it is possible to prevent the air hole 26 and the first groove 37 from being displaced in the circumferential direction.

Next, a method of manufacturing the stopper 20 will be described with reference to FIGS. 3 and 4. FIG. 3 is a perspective view of a molded body 40 formed by blow molding. FIG. 4 is a cross-sectional view of the molded product 40 taken along the line IV-IV of FIG. As shown in FIGS. 3 and 4, first, a molded body 40 made of a thermoplastic elastomer is formed by known blow molding (molding step). Specifically, a tubular elastomer made of thermoplastic elastomer is extruded, the outer circumference of the parison is covered with a mold, and then air is blown into the parison to press the outer peripheral surface of the parison against the mold. The molded body 40 is formed by press blow molding.

The molded body 40 is provided with a protrusion 41 protruding radially outward from the outer peripheral surface of the mounting portion 21 with respect to the stopper 20 shown in FIG. 2, and a recess 42 is provided instead of the air hole 26. Further, although burrs are attached to the tip 23 of the molded body 40 immediately after molding and the axial end portion on the pressure receiving surface 34 side, these burrs are omitted in FIG.

The protruding portion 41 is formed at a position axially separated from the claw portion 24 and the end surface 33 of the cushioning portion 30. The recess 42 is formed from the inner peripheral surface of the mounting portion 21 toward the outer side in the radial direction so that the bottom 42a is located in the protruding portion 41. The recess 42 is also formed by blow molding.

After blow molding, burrs are cut at the tip 23 of the molded body 40 and the axial end on the pressure receiving surface 34 side, and the protruding portion 41 is cut along the outer peripheral surface of the mounting portion 21 along the cutting line 44 (cutting step). .. Specifically, in the cutting step, first, the molded body 40 is set on a rotatable turntable (not shown) about the central axis C (see FIG. 1). Next, the molded body 40 is rotated while the blade (not shown) is vertically applied to the outer peripheral surface of the molded body 40 to cut burrs at the tip 23 and the axial end portion on the pressure receiving surface 34 side.

Next, the blade 43, which is smaller than the axial distance between the claw portion 24 and the end surface 33 and larger than the axial dimension of the protruding portion 41, is positioned on the tangent line of the outer peripheral surface of the mounting portion 21. It hits the mounting portion 21 between the portion 24 and the end surface 33. Then, by rotating the molded body 40 with the blade 43 fixed, the protruding portion 41 is cut along the outer peripheral surface of the mounting portion 21 by the cutting line 44.

Since the bottom 42a of the recess 42 that opens to the inner peripheral surface of the mounting portion 21 is inside the protruding portion 41, by cutting the protruding portion 41, an air hole 26 that penetrates the mounting portion 21 in the radial direction is formed by the recess 42. Will be done. Further, since the recess 42 is provided in the protruding portion 41 axially away from the end surface 33, the mounting portion 21 is sure to have a separated portion 27 that axially separates the air hole 26 and the first groove 37.

In blow molding in which air is blown into the parison to form the molded body 40, it is difficult to provide the air holes 26 in the molded body 40. For example, injection blow molding is conceivable in which a parison having an attachment portion 21 provided with an air hole 26 is formed by injection molding, and then a buffer portion 30 is formed by blow molding while closing the air hole 26. It takes time and effort, and it takes time and effort to close the air hole 26. Further, a method is conceivable in which a plurality of air holes 26 are hollowed out by a cutter or the like after blow molding the molded body 40 having no protrusion 41 or recess 42, but it takes time and effort.

On the other hand, in the present embodiment, the tubular cushioning portion 30 having the bellows-shaped outer peripheral surface 31 and the inner peripheral surface 32 can be easily formed by blow molding, and the protruding portion 41 formed by blow molding is cut. As a result, the stopper 20 having the air holes 26 can be easily formed. In particular, even if the molded body 40 is formed by press blow molding using a parison having no air holes 26, the protruding portion 41 can be cut to form the air holes 26 in the same manner as the burr cutting, so that the burr can be cut in the same manner. The formation of the air hole 26 can be facilitated as compared with the case where the stopper 20 is formed by the required injection blow molding.

Further, the end surface 33 of the buffer portion 30 is slightly ascended toward the tip 23 side toward the inside in the radial direction. This makes it easier to bring the thermoplastic elastoma into close contact with the mold during blow molding, and makes it easier to form the end face 33 on which the first groove 37 and the second groove 38 are provided. In addition, the stopper 20 can be easily removed from the mold after blow molding. In the state where the claw portion 24 is fitted into the fitting recess 18b of the bracket 11, the end surface 33 is pressed against the contact surface 17 substantially perpendicular to the central axis C, and the end surface 33 is also substantially perpendicular to the central axis C.

The groove bottoms of the first groove 37 and the second groove 38 are slightly upwardly inclined toward the tip 23 side toward the inside in the radial direction. Further, the first groove 37 and the second groove 38 are inclined upward from the bottom of the groove toward both sides in the circumferential direction. This makes it easier to remove the first groove 37 and the second groove 38 from the mold after blow molding.

Next, the second embodiment will be described with reference to FIGS. 5 and 6. In the first embodiment, the case where the first groove 37 and the second groove 38 are provided on the end surface 33 of the cushioning portion 30 has been described. On the other hand, in the second embodiment, the case where the first groove 54 and the second groove 55 are provided on the contact surface 17 of the bracket 51 will be described. The same parts as those in the first embodiment are designated by the same reference numerals, and the following description will be omitted.

FIG. 5 is a cross-sectional view of a stopper unit 50 attached to the shock absorber 1, including the central axis C of the piston rod 4 of the shock absorber 1. FIG. 6 is a cross-sectional view of the stopper unit 50 in the VI-VI line of FIG. The right side of the paper surface with respect to the central axis C of FIG. 5 shows a cross section passing through the first groove 54, and the left side of the paper surface with respect to the central axis C shows a cross section not passing through the first groove 54 and the second groove 55. Further, FIG. 6 schematically shows a cross section of the attachment portion 21 and the second fixture 53 of the stopper unit 50, and a part visible on the back side of the paper surface with respect to the cross section is omitted.

As shown in FIG. 5, the stopper unit 50 includes a tubular bracket 51 to which the piston rod 4 is attached and a tubular stopper 52 attached to the cylinder 2 side of the bracket 51. The stopper 52 is formed in the same manner as the stopper 20 of the first embodiment except that the first groove 37 and the second groove 38 are not provided on the end surface 33 of the cushioning portion 30.

The bracket 51 includes a cylindrical portion 12, a disk portion 13, an elastic portion 14, and a first fixture 15 and a second fixture 53 that sandwich the elastic portion 14 in the axial direction, respectively. The second fixture 53 is the same as the second fixture 16 except that the contact surface 17 is provided with the first groove 54 and the second groove 55 with respect to the second fixture 16 of the first embodiment. Is formed in.

As shown in FIGS. 5 and 6, four first grooves 54 and four second grooves 55 are provided on the contact surface 17 of the second fixture 53 in a radial pattern centered on the central axis C. Has been done. The plurality of first grooves 54 and the second grooves 55 are arranged at equal intervals in the circumferential direction so as to be positioned alternately. Each of the first groove 54 and the second groove 55 is formed linearly from the radial inner edge of the contact surface 17 to the radial outer edge. All the first groove 54 and the second groove 55 have the same shape and dimensions.

The mounting portion 21 is press-fitted into the press-fitting surface 18 of the bracket 51 so that the first groove 54 is located on the radial outer side of the air hole 26. Therefore, the first groove 54 extends in the radial direction from the position of the air hole 26 when viewed from the axial direction. On the other hand, the second groove 55 extends in the radial direction from the mounting portion 21 at a position where there is no air hole 26.

The stopper 52 and the bracket 51 provide an air passage that communicates the inside and outside of the stopper 52 by the air hole 26 provided in the mounting portion 21 and the first groove 54 provided in the contact surface 17 radially outward from the air hole 26. It can be provided between and. As a result, abnormal noise when the stopper 52 expands and contracts can be suppressed.

A first groove 54 is formed from the radially inner end edge of the portion where the contact surface 17 of the bracket 51 and the end surface 33 of the cushioning portion 30 face each other in the axial direction to the outer side of the radial outer edge. Therefore, even if the contact surface 17 and the end surface 33 are in close contact with each other to the maximum extent, the radial outer end of the air passage communicating with the inside and outside of the stopper 52 can be reliably opened. As a result, it is possible to make it more difficult to generate an abnormal noise when the stopper 52 expands and contracts.

Since the first groove 54 is provided on the contact surface 17, the air passage formed by the first groove 54 can be directly communicated with the air hole 26. As a result, it is possible to increase the instantaneous intake / exhaust amount through the air passage when the stopper 52 expands and contracts, so that it is difficult to generate an abnormal noise when the stopper 52 expands and contracts. In particular, when the bottom of the first groove 54 is located at the same axial position as the edge of the air hole 26 on the tip 23 side, or is located on the axial tip 23 side of the edge of the air hole on the tip 23 side. The instantaneous intake / exhaust amount through the air passage when the stopper 52 is expanded / contracted can be increased, and abnormal noise can be made less likely to occur.

Further, since the first groove 54 is provided on the contact surface 17 of the bracket 51, the thickness of the cushioning portion 30 that affects the cushioning characteristics is different from that of the first embodiment in which the first groove 37 is provided on the end surface 33 of the cushioning portion 30. The first groove 54 can be formed deeply regardless of. As a result, the amount of instantaneous intake and exhaust through the air passage can be increased, so that abnormal noise can be less likely to be generated.

Further, since the first groove 54 is provided only on the contact surface 17, the way of deforming the end surface 33 due to the first groove 54 is different from that of the first embodiment in which the first groove 37 is provided on the end surface 33. It is possible to suppress the change in the direction. As a result, the durability of the stopper 52 can be improved.

Since a plurality of second grooves 55 are provided between the first grooves 54, when the end surface 33 is pressed against the contact surface 17, the portion with and without the first groove 54 for forming an air passage The difference in stress received by the end face 33 can be reduced. As a result, the durability of the stopper 52 can be further improved. Further, since the first groove 54 and the second groove 55 are alternately arranged at equal intervals, the stress received by the end face 33 can be uniformly approached in the circumferential direction. As a result, the durability of the stopper 52 can be further improved.

The circumferential dimension of the air hole 26 is larger than the circumferential dimension of the first groove 54. As a result, even if the mounting portion 21 rotates slightly in the circumferential direction with respect to the bracket 51, the first groove 54 can be positioned on the radial outer side of the air hole 26. As a result, it is possible to secure an air passage through the air hole 26 and the first groove 54, and it is possible to prevent abnormal noise from being generated.

Further, when the mounting portion 21 rotates in the circumferential direction with respect to the bracket 51, if the portion that was the second groove 55 before the rotation is located on the radial outside of the air hole 26, the second groove 55 is before the rotation. The portion that was the first groove becomes the first groove, and the portion that was the first groove 54 before the rotation becomes the second groove. It is preferable that the circumferential dimension of the air hole 26 is larger than the circumferential distance from the first groove 54 to the second groove 55 on the press-fitting surface 18. As a result, no matter how much the mounting portion 21 rotates in the circumferential direction with respect to the bracket 51, an air passage communicating with the inside and outside of the bracket 51 can be secured, and abnormal noise can be less likely to occur.

Although the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments, and it is easy to make various improvements and modifications without departing from the spirit of the present invention. It can be inferred. For example, the shapes and dimensions of the brackets 11, 51 and the stoppers 20, 52 may be appropriately changed. At least one of the outer peripheral surface 31 and the inner peripheral surface 32 of the cushioning portions 30 of the stoppers 20 and 52 may be formed in a shape other than the bellows shape. Further, the stopper 20 of the first embodiment may be attached to the bracket 51 of the second embodiment, and the first grooves 37 and 54 may be provided on the contact surface 17 and the end surface 33, respectively.

In the above embodiment, the case where the stopper units 10 and 50 are attached to the piston rod 4 of the shock absorber 1 has been described, but the present invention is not necessarily limited to this. The stopper units 10 and 50 may be attached to the cylinder 2 side, and the stoppers 20 and 52 may be compressed in the axial direction between the frame attached to the piston rod 4 side and the brackets 11 and 51. Further, the stoppers 20 and 52 may be arranged between the two members other than the shock absorber 1, and the impact between the two members may be absorbed by the stoppers 20 and 52.

In the above embodiment, four air holes 26 are provided in the mounting portion 21, and four linear first grooves 37, 54 and four linear second grooves 38, 55 are provided in the end surface 33 or the contact surface 17. Although the case where it is provided has been described, it is not necessarily limited to this. The number and shape of the air holes 26, the first grooves 37, 54, and the second grooves 38, 55, the distance between them, and the like may be appropriately changed. Further, the second grooves 38 and 55 may be omitted.

In the above embodiment, the case where the mounting portion 21 is press-fitted into the press-fitting surface 18 which is the inner peripheral surface of the second fixture 16 of the brackets 11 and 51 has been described, but the present invention is not necessarily limited to this. A part of the contact surface 17 of the brackets 11 and 51 may be recessed in the axial direction, and the mounting portion 21 may be fitted in the recess. Further, the mounting portion 21 may be fitted to the brackets 11 and 51 so that the outer peripheral surfaces of the brackets 11 and 51 are covered with the inner peripheral surface of the mounting portion 21. In these cases, the end surface 33 may be provided from the inner peripheral surface of the mounting portion 21 toward the inside in the radial direction.

In the above embodiment, the case where the stoppers 20 and 52 are formed by press blow molding has been described, but the present invention is not necessarily limited to this. The stoppers 20 and 52 may be formed by blow molding other than press blow molding, such as the above-mentioned injection blow molding, direct blow molding, and biaxial stretching blow molding. Further, the stoppers 20 and 52 may be formed by using a mold having a core forming the inner peripheral surfaces 32 of the stoppers 20 and 52. In this case, the stoppers 20 and 52 may be formed of rubber, a foamed synthetic resin, or the like, which is an elastic body other than the thermoplastic elastomer. If it is difficult to forcibly remove the stoppers 20 and 52 from the core, a collapsible core may be used.

In the first embodiment, the case where the air hole 26 and the first groove 37 are not directly connected has been described, but the present invention is not necessarily limited to this. Depending on the molding method of the stopper 20, the air hole 26 can be provided up to the end surface 33, the separation portion 27 can be omitted, and the first groove 37 and the air hole 26 can be directly connected. As a result, the amount of intake and exhaust when the stopper 20 is expanded and contracted can be increased, so that abnormal noise when the stopper 20 is expanded and contracted can be made less likely to occur.

In the first embodiment, the blade 43 located on the tangent line of the outer peripheral surface of the mounting portion 21 is applied to the mounting portion 21 between the claw portion 24 and the end surface 33, and the molded body 40 is fixed with the blade 43 fixed. The case where the protruding portion 41 is cut along the outer peripheral surface of the mounting portion 21 by the cutting line 44 has been described, but the present invention is not necessarily limited to this. Since the claw portion 24 is provided at a position deviated from the protruding portion 41 (air hole 26) in the circumferential direction, the blade is applied to the protruding portion 41 from the axial direction without interfering with the claw portion 24, and the protruding portion is formed. 41 can be cut.

10,50 Stopper unit 11,51 Bracket 17 Contact surface 20,52 Stopper 21 Mounting part 23 Tip 26 Air hole 27 Separation part 30 Cushioning part 31 Outer peripheral surface 32 Inner peripheral surface 33 End surface 37,54 First groove 38,55 Second Groove 40 Molded body 41 Protruding part 42 Recessing part 42a Bottom C Central axis

Claims (7)

A stopper formed by a tubular elastic body that is attached to a bracket and is pressed against the contact surface of the bracket and compressed in the axial direction to absorb an impact.
A tubular cushioning portion having an axial end surface that can contact the contact surface,
A tubular mounting portion that projects axially from the end face and can be fitted to the bracket is provided.
The mounting portion is provided with an air hole penetrating in the radial direction.
The air hole is separated from the axial tip of the mounting portion opposite to the cushioning portion.
A first groove is provided on the end face.
The first groove is a stopper characterized in that it extends in the radial direction from the position of the air hole when viewed from the axial direction. A plurality of the air holes and the first groove are provided at intervals in the circumferential direction.
A plurality of second grooves are provided between the first grooves on the end face.
The stopper according to claim 1, wherein the second groove extends in the radial direction from the mounting portion. The stopper according to claim 1 or 2, wherein the mounting portion includes a separating portion that axially separates the air hole and the first groove. Brackets with contact surfaces and
A stopper formed of a tubular elastic body attached to the bracket and pressed against the contact surface and compressed in the axial direction to absorb an impact.
The stopper includes a tubular cushioning portion having an axial end surface that can contact the contact surface.
A tubular mounting portion that projects axially from the end face and fits into the bracket is provided.
The mounting portion is provided with an air hole penetrating in the radial direction.
The air hole is separated from the axial tip of the mounting portion opposite to the cushioning portion.
A first groove is provided on at least one of the end face and the contact surface.
The first groove is a stopper unit characterized in that it extends in the radial direction from the position of the air hole when viewed from the axial direction. The stopper unit according to claim 4, wherein the first groove is provided only on the contact surface. The stopper according to claim 4 or 5, wherein the first groove is provided at least up to both radial edges of a portion where the contact surface and the end surface face each other in the axial direction. A method for manufacturing a tubular stopper that is attached to a bracket, pressed against the contact surface of the bracket, and compressed in the axial direction to absorb an impact.
A tubular mounting portion that can be fitted to the bracket, a tubular cushioning portion that has a bellows-shaped outer peripheral surface and an inner peripheral surface and is connected to the mounting portion, and a radial outer side from the outer peripheral surface of the mounting portion. A molded body made of a thermoplastic elastomer having a protruding portion protruding toward the surface and having a concave portion radially outward from the inner peripheral surface of the mounting portion so that the bottom is located in the protruding portion is blow-molded. Molding process and
A cutting step of cutting the protruding portion of the molded body formed by the blow molding along the outer peripheral surface of the mounting portion and forming an air hole penetrating the mounting portion in the radial direction by the recess. A method for manufacturing a stopper, which is characterized by being provided.

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