JP5968043B2 - Vibration isolator and manufacturing method thereof - Google Patents

Description

  The present invention relates to a vibration isolator suitably applied to, for example, automobile suspension bushes, torque rods, engine mounts, and the like, and a method for manufacturing the same.

  2. Description of the Related Art Conventionally, there has been known an anti-vibration device that is interposed between members constituting a vibration transmission system and that anti-vibrates and supports the members mutually. This vibration isolator has a structure in which an inner member is inserted and arranged in a cylindrical portion of an outer member, and the inner member and the outer member are elastically connected to each other by an elastic body. For example, it is shown in Unexamined-Japanese-Patent No. 2005-220956 (patent document 1).

  Conventionally, the vibration isolator has been formed by vulcanizing and bonding a rubber elastic body to a metal inner member and an outer member. However, Patent Document 1 aims to reduce the weight and omit the bonding process. A structure in which an outer member made of synthetic resin is formed on the outer peripheral surface of a rubber elastic body by injection molding has been proposed.

  However, since the outer member formed by injection molding is not fixed to the rubber elastic body, even if a recess is provided on the outer peripheral surface of the rubber elastic body, the outer member may come out of the rubber elastic body when a heavy load is input. It was. Further, there is a demand for further improvement in mass productivity, and for this reason, it may be required to shorten the time required for vulcanization molding of a rubber elastic body.

Japanese Patent Laid-Open No. 2005-220956

  The present invention has been made in the background of the above-mentioned circumstances, and its solution is to prevent the outer member from coming off without providing an adhesion step, and to efficiently manufacture with excellent mass productivity. An object of the present invention is to provide an anti-vibration device having a novel structure that can be achieved.

  It is another object of the present invention to provide a novel method for manufacturing a vibration isolator capable of pre-compressing an elastic body without requiring an increase in the number of steps and realizing improved durability. And

That is, the first aspect of the present invention is the vibration isolator in which the inner member is inserted into the cylindrical portion of the outer member, and the inner member and the cylindrical portion of the outer member are elastically connected by the elastic body. The cylindrical portion formed on the outer peripheral surface of the elastic body, wherein the elastic body is made of a thermoplastic elastomer and is fixed to the inner member, and the cylindrical portion of the outer member is made of a synthetic resin . and the elastic body are the fused fixed state, and, Ri Contact is exerted the cylindrical portion pressing force against the cylindrical outer peripheral surface of the elastic body having a concave axial end surfaces, with the axial end surface of the elastic body is in a state that bulges deformed axially outwardly, axially outer peripheral surface of the elastic body that is fused to the inner peripheral surface of the cylindrical portion in longitudinal section It is characterized by gradually inclining toward the inner periphery as it goes to.

  According to the vibration isolator having the structure according to the first aspect as described above, since the elastic body is made of a thermoplastic elastomer, the elastic body can be formed in a short time, thereby improving mass productivity. It is done. Furthermore, it may be possible to reuse the discarded elastic body of the vibration isolator.

  Moreover, since the outer member is made of synthetic resin, the weight can be reduced and the outer member can be formed into an arbitrary shape in a short time. In addition, since the outer member is molded on the outer peripheral surface of the elastic body, the outer peripheral surface of the elastic body formed of the thermoplastic elastomer is melted by the heat of the outer member, and the outer member and the elastic body are mutually melted. Worn. Accordingly, the outer member can be prevented from coming off from the elastic body without requiring adhesion using an adhesive, and sufficient axial load resistance is ensured.

Incidentally, the vibration damping device according to the first aspect of the present invention, by the tubular portion pressing force of the cylindrical outer peripheral surface of the elastic body having a concave axial end face is exerted, the elastic The axial end surface of the body is bulged and deformed outward in the axial direction, and the outer peripheral surface of the elastic body fused to the inner peripheral surface of the cylindrical portion gradually becomes inner in the longitudinal section as it goes outward in the axial direction. The aspect which inclines to the circumference side is employ | adopted .

According to the first aspect, the outer member is prevented from coming off from the elastic body in the axial direction by the engagement between the inner peripheral surface of the cylindrical portion of the outer member and the outer peripheral surface of the elastic body. Moreover, since the inner peripheral surface of the cylindrical portion of the outer member and the outer peripheral surface of the elastic body are curved cylindrical shapes corresponding to each other in the longitudinal section, the inner peripheral surface of these cylindrical portions and the outer peripheral surface of the elastic body As a result, a large resistance area can be obtained and the load resistance in the axial direction can be improved. Further, the end surface in the axial direction of the elastic body before the cylindrical portion is fused is formed in a concave shape, a large free surface is secured on the end surface in the axial direction, and the rubber volume at the end portion in the axial direction of the elastic body is secured. Is suppressed. As a result, when the elastic body is pressed to the inner peripheral side by the cylindrical portion, the elastic body can be efficiently swelled outward in the axial direction, and the internal distortion is effectively reduced or eliminated. In addition, deformation of the inner peripheral surface of the cylindrical portion and the outer peripheral surface of the elastic body into an inclined shape is effectively realized.

A second aspect of the present invention, the vibration damping device according to the first aspect, Ri Contact the pressing force of the cylindrical portion is exerted on the cylindrical outer peripheral surface of the elastic body, the axis of the elastic member together in the state in which end face has bulging deformation axially outward, in which has a convex shape in longitudinal section.

According to the second aspect, the internal strain is sufficiently reduced or eliminated by applying large pre-compression in the radial direction until the axial end surface of the elastic body formed into a concave shape in the longitudinal section becomes convex. In addition, since the outer peripheral surface of the elastic body is sufficiently deformed, the locking action in the axial direction and the securing of the fusion area are effectively realized.

A third aspect of the present invention is a method of manufacturing a vibration isolator in which an inner member is inserted into a cylindrical portion of an outer member, and the inner member and the cylindrical portion of the outer member are elastically connected by an elastic body. The inner member is prepared and set in an elastic body molding die, and then the elastic body is molded by filling the cavity of the elastic body molding die with a molten thermoplastic elastomer, An elastic body molding step for fixing the elastic body to the inner member, and after the elastic body molded in the elastic body molding step is set in an outer molding die, it is heated and melted in a cavity of the outer molding die. An outer molding step of filling the synthetic resin and molding the cylindrical portion of the outer member on the outer peripheral surface of the elastic body, and fusing the cylindrical portion and the elastic body to each other. Is a feature.

According to the method for manufacturing a vibration isolator according to the third aspect, the time required for the elastic body forming step is higher than that when the elastic body is formed of rubber by forming the elastic body of thermoplastic elastomer. Can be shortened.

  In addition, since the outer member is formed after the elastic body is molded, the outer peripheral surface of the elastic body formed of the thermoplastic elastomer is melted by the heat of the outer member, and these elastic members are not required without requiring a special bonding step. The body and the outer member are fixed to each other by fusion.

  Further, the elastic body is compressed to the inner peripheral side by the filling pressure of the synthetic resin which is the material for forming the outer member. Therefore, even when the outer member made of synthetic resin is employed and post-processing such as diameter reduction processing is not performed, the internal distortion of the elastic body is reduced or eliminated by the molding of the outer member, and the elastic body Durability is improved.

According to a fourth aspect of the present invention, there is provided the vibration isolator manufacturing method according to the third aspect, wherein the elastic body shaft is set in the outer molding die before the cylindrical portion is molded. A gap is provided between at least a part of both end surfaces in the direction and the wall inner surface of the cavity of the outer mold, and the cylindrical shape is formed on the cylindrical outer peripheral surface of the elastic body having a concave axial end surface. The outer circumferential surface of the elastic body fused to the inner circumferential surface of the cylindrical portion while causing the axial end surface of the elastic body to bulge and deform outward in the axial direction by exerting a pressing force during molding of the portion Is gradually inclined toward the inner peripheral side as it goes outward in the axial direction in the longitudinal section.

According to the fourth aspect, when the compressive force toward the inner peripheral side is exerted on the elastic body when the outer member is molded, the elastic body is compressed in the direction perpendicular to the axis and bulges into the gap in the axial direction. Thereby, the internal distortion of the elastic body is effectively reduced or eliminated, and the durability is improved.

  Further, at least a part of the axial end surface of the elastic body is a free surface that is not constrained by the inner wall surface of the outer mold, and the rigidity of the elastic body in the direction perpendicular to the axial direction is the axial central portion at both axial end portions. Has been smaller than. Therefore, the curved cylindrical shape of the fusion surface of the outer member and the elastic body can be easily obtained by the filling pressure of the forming material of the outer member, and without requiring a special process such as adhesion, the axial direction can be obtained. The slip-off resistance can be improved.

  Moreover, in the elastic body forming step, the axial end surface of the elastic body is formed into a concave shape, the rubber volume at the axial end portion of the elastic body is reduced, and the area of the free surface on the axial end surface of the elastic body Is greatly secured. As a result, in the outer molding process, the elastic body is sufficiently allowed to bulge outward in the axial direction, and the internal distortion is reduced or eliminated by pre-compression to the inner peripheral side, and the axial drag resistance is improved. Is realized more effectively.

According to a fifth aspect of the present invention, there is provided a method for manufacturing a vibration isolator as described in the fourth aspect, wherein a pressing force at the time of molding the cylindrical portion is applied to the cylindrical outer peripheral surface of the elastic body. The axial end face of the elastic body bulges outward in the axial direction and is deformed into a convex shape in the longitudinal section.

According to the fifth aspect, the internal distortion is sufficiently reduced or reduced by applying a large pre-compression to the elastic body in the radial direction and sufficiently deforming the elastic body until the axial end surface has a convex shape. As a result, the durability is improved, and the axial drag is effectively improved.

  According to the present invention, since the elastic body is formed of a thermoplastic elastomer, the mass productivity can be improved. Furthermore, since the cylindrical part of the outer member is made of synthetic resin, both weight reduction and improvement in mass productivity are realized. In addition, since the cylindrical portion of the outer member is fused to the elastic body, the removal effect in the axial direction is sufficiently ensured without requiring a special bonding operation, and the outer member is prevented from being detached from the elastic body. be able to.

The longitudinal cross-sectional view which shows the suspension bush as the 1st Embodiment of this invention. The longitudinal cross-sectional view explaining the elastic body shaping | molding process which is a manufacturing process of the suspension bush shown by FIG. The longitudinal cross-sectional view explaining the outer shaping | molding process which is a manufacturing process of the suspension bush shown by FIG. The longitudinal cross-sectional view which shows the principal part of the torque rod as the 2nd Embodiment of this invention.

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

  FIG. 1 shows a suspension bush 10 for an automobile as a first embodiment of a vibration isolator having a structure according to the present invention. The suspension bush 10 has a structure in which an inner member 12 is inserted into an outer member 14 and the inner member 12 and the outer member 14 are elastically connected by an elastic body 16.

  More specifically, the inner member 12 has a small-diameter, generally cylindrical shape, and is a highly rigid member formed of a metal such as iron or an aluminum alloy. In the present embodiment, the linear shape has a substantially constant inner and outer diameter dimension over the entire axial length. For example, a large-diameter bulging portion is partially provided in the central portion in the axial direction. Thus, the fixing strength of the elastic body 16 described later can be increased.

  The elastic member 16 is fixed to the inner member 12. The elastic body 16 is formed of a thermoplastic elastomer and has a substantially cylindrical shape, and the inner peripheral surface thereof is fixed to the outer peripheral surface of the axially central portion of the inner member 12 by means such as adhesion. Further, the end face in the axial direction of the elastic body 16 is a convex end face 17 that is convex outward in the axial direction.

  Furthermore, the elastic body 16 is integrally formed with a pair of lip portions 18, 18. The lip portions 18 are provided at both end portions in the axial direction of the elastic body 16, protrude toward the outer peripheral side, and have an annular shape continuous over the entire periphery. Further, the lip portion 18 has a cross-sectional shape that gradually becomes narrower in the axial direction toward the projecting tip side in the vertical cross section, and the outer surface in the axial direction expands in a substantially perpendicular direction to the axial direction. It is set as the inclined surface which inclines to an axial direction outer side as an inner surface goes to an outer peripheral side.

  Furthermore, a concave groove 20 that opens to the outer peripheral surface and extends in the circumferential direction is formed between the pair of lip portions 18 and 18 in the axial direction. The bottom surface of the groove 20 constitutes a curved cylindrical outer peripheral surface 21 of the elastic body 16, and the curved cylindrical outer peripheral surface 21 has a curved cylindrical shape that inclines toward the inner peripheral side as it goes outward in the axial direction in the longitudinal section. As a result, the depth of the groove 20 is greater at the axially outer portion than at the axially central portion. Further, the inner surface of the side wall of the concave groove 20 formed by the axially inner surfaces of the lip portions 18 and 18 is an inclined surface, and the concave groove 20 has a longitudinal sectional shape that gradually expands toward the outer peripheral side. ing.

  The material for forming the elastic body 16 is not particularly limited as long as it is a thermoplastic elastomer exhibiting rubbery elasticity, and examples thereof include urethane-based, styrene-based, olefin-based, ester-based, fluorine-based, and diene-based materials. Both are preferably employed. Specifically, for example, styrene-butadiene block copolymer, polyester-polyether block copolymer, segmented polyurethane, partially crosslinked blend of polypropylene and ethylene-propylene rubber, chlorinated polyethylene, syndiotactic-1, 2 Polybutadiene or the like can be employed as the material for forming the elastic body 16. In addition, as a forming material of the elastic body 16, the above thermoplastic elastomers may be used alone or in combination of two or more. Furthermore, it is also possible to adjust the characteristics by adding carbon black or the like to the thermoplastic elastomer as described above.

  In the present embodiment, the axial end surface of the elastic body 16 is inclined outward in the axial direction as it goes to the inner peripheral side in the axial direction before the outer member 14 to be described later is formed, and the inclination angle with respect to the central axis is internal. The concave end surface 22 has a curved concave shape that decreases toward the circumferential side. In addition, the outer peripheral surface of the elastic body 16 is a cylindrical cylindrical outer peripheral surface 23 that extends linearly in the axial direction before the outer member 14 described later is formed (see FIG. 3).

  An outer member 14 is formed on the outer peripheral side of the elastic body 16. The outer member 14 has a large-diameter, generally cylindrical shape, and is formed of a hard synthetic resin. The outer member 14 is formed with a substantially constant outer diameter over the entire axial length, and the inner diameter of both axial ends is larger than the axial middle portion. Furthermore, the inner peripheral surface of the axially intermediate portion of the outer member 14 has a curved shape that gradually inclines toward the inner peripheral side in the longitudinal section as it goes outward in the axial direction. Protrusions 24 projecting to the inner peripheral side are formed. In the present embodiment, the entire outer member 14 has a substantially cylindrical shape, and the tubular portion is configured by the entire outer member 14.

  The material for forming the outer member 14 is not particularly limited as long as it is a hard synthetic resin. For example, polyamide (hereinafter referred to as PA) 46, PA6, PA66, PA92, PA99, PA610, PA612, PA11, PA912. PA12, a copolymer of PA6 and PA66, a copolymer of PA6 and PA12, PA4T, PA6T, PAMXD6, PA9T, PA10T, PA11T, PA12T, PA13T and the like can be suitably employed. In particular, as a material for forming the outer member 14, PA 66 having excellent hydrolysis resistance is desirable. In addition, said forming material can be employ | adopted individually or in combination of 2 or more types. Further, the strength can be increased by adding glass fiber or the like to the above synthetic resin material. Further, the material for forming the outer member 14 is not limited to the thermoplastic synthetic resin, and a thermosetting synthetic resin can also be adopted.

  The outer member 14 is formed by injection molding on the outer peripheral surface of the elastic body 16, and the synthetic resin material forming the outer member 14 is injected while being heated and melted. The outer peripheral surface and the inner peripheral surface of the outer member 14 are fused to each other. Note that the inner peripheral end portion of the outer member 14 is sandwiched between the pair of lip portions 18 and 18 in the axial direction intermediate portion. Further, no adhesive is applied to the inner peripheral surface of the outer member 14 and the outer peripheral surface of the elastic body 16, and the melted outer member 14 and the elastic body 16 are fixed to each other by cooling and solidifying.

  Further, a pressing force to the inner peripheral side is applied to the outer peripheral surface of the elastic body 16 by the injection pressure of the outer member 14, and the elastic body 16 is pre-compressed in the radial direction. Furthermore, in the present embodiment, the concave end surface 22 of the elastic body 16 formed into a curved concave shape is formed in the axial direction by the injection pressure of the outer member 14 acting as a radial compressive force on the elastic body 16. It is deformed to bulge outward. In particular, in this embodiment, the amount of deformation of the elastic body 16 toward the inner peripheral side is sufficiently large, and after the outer member 14 is molded, the axial end surface of the elastic body 16 has a convex end surface 17 that is convex in the longitudinal section. Has been. Furthermore, since the rigidity in the radial direction of the elastic body 16 gradually decreases toward the outer side in the axial direction, the cylindrical outer peripheral surface 23 of the elastic body 16 formed into a cylindrical shape has an injection pressure of the outer member 14. As a result, the outer side in the axial direction is compressed to be larger than the inner side, and the curved cylindrical outer peripheral surface 21 is deformed into a convex curved shape on the outer peripheral side.

  In the suspension bush 10 having such a structure, the inner member 12 is attached to the suspension side (not shown) and the outer member 14 is attached to the vehicle body side, so that the suspension is connected to the vehicle body in a vibration-proof manner. doing.

  According to the suspension bush 10 having such a structure, the elastic body 16 is formed of a thermoplastic elastomer and can be formed in a short time by injection molding or the like. As compared with the case of obtaining the above, the mass productivity can be improved. Moreover, by disposing the elastic body 16 made of a thermoplastic elastomer, the discarded elastic body 16 can be reused.

  Further, the outer member 14 made of synthetic resin and the elastic body 16 made of thermoplastic elastomer are fused to each other by heat during molding, so that the outer member 14 is prevented from coming off from the elastic body 16. Moreover, since the lip portions 18, 18 projecting toward the outer peripheral side are provided at both axial end portions of the elastic body 16, the outer member 14 is locked to the lip portion 18, whereby the elastic body of the outer member 14. 16 is prevented from coming off in the axial direction. Furthermore, since the outer peripheral surface of the outer member 14 and the outer peripheral surface (curved cylindrical outer peripheral surface 21) of the elastic body 16 have a curved shape that inclines toward the inner peripheral side as it goes outward in the axial direction in the longitudinal section, The inner peripheral surface of the outer member 14 and the outer peripheral surface of the elastic body 16 are locked in the axial direction, and the outer member 14 is prevented from coming off in the axial direction. In addition, the formation of the lip portion 18 and the curved shape of the inner peripheral surface of the outer member 14 and the outer peripheral surface of the elastic body 16 ensure a large fusion area between the outer member 14 and the elastic body 16. The improvement of the fixing strength by this is realized.

  The suspension bush 10 having the structure according to the present embodiment is manufactured as follows, for example.

  That is, first, as shown in FIG. 2, the prepared inner member 12 is set in the cavity 26 of the elastic body molding die 25, and the thermoplastic elastomer is injected from the injection port 28 communicated with the cavity 26. Is injected into the cavity 26, whereby the elastic body 16 is injection-molded and fixed to the inner member 12. After the elastic body 16 is cooled and the shape is stabilized, the elastic body 16 is taken out from the elastic body forming mold 25 to obtain an integrally molded product of the elastic body 16 including the inner member 12. The elastic body forming process is thus completed. 2 and 3, the elastic body 16 formed in the elastic body forming step has a cylindrical outer peripheral surface 23 in which the outer peripheral surface (the bottom surface of the groove 20) is linear in the longitudinal section. It is said that. Further, the elastic body 16 formed in the elastic body forming step has a concave end face 22 whose axial end face has a curved inclined shape in the longitudinal section.

  The suspension bush 10 can be obtained by two-color molding of the elastic body 16 and the outer member 14 by continuously executing the elastic body molding step and an outer molding step described later. That is, the elastic body 16 is cooled and the shape is stabilized in the elastic body forming step means that the elastic body 16 is solidified from a molten state to at least a mold that can be demolded. It does not mean just cooling to (for example, temperature). Accordingly, the outer member 14 can be quickly formed by replacing the elastic body forming mold 25 with the outer forming mold 30 (described later) without providing a special cooling time after the elastic body 16 is formed. There is a case. According to this, since the cooling time is not required in the molding process of the elastic body 16 and the outer member 14, it is possible to manufacture in a short time and to improve productivity. In short, the elastic member 16 and the outer member 14 are fused by molding the outer member 14 by two-color molding or the like before the elastic member 16 is cooled to room temperature or until it is completely solidified. It is also possible to perform the process more promptly and more stably.

  Next, as shown in FIG. 3, the integrally molded product of the elastic body 16 obtained by the above process is set in the cavity 32 of the outer molding die 30 and is integrally formed with the elastic body 16. The surfaces on the outer side in the axial direction of the lip portions 18 and 18 are pressed against and closely adhered to the inner wall surface of the cavity 32 of the outer molding die 30, so that the outer peripheral surface of the elastic body 16 and the inner wall surface of the cavity 32 are interposed. Create a space. Then, the outer member 14 is injection-molded on the outer peripheral side of the elastic body 16 by injecting synthetic resin heated and melted into the space (a part of the cavity 32) through the injection port 34.

  Further, when the outer member 14 is injection-molded, the outer peripheral surface of the elastic body 16 is heated and melted when the synthetic resin heated and melted contacts the outer peripheral surface of the elastic body 16. The inner peripheral surface of the outer member 14 is fused.

  Further, when the injection pressure when forming the outer member 14 acts on the outer peripheral surface of the elastic body 16, a compressive force is applied to the elastic body 16 inward in the radial direction. The internal strain of the elastic body 16 is reduced or eliminated by the action. Note that, when the elastic body 16 is completely solidified after the outer member 14 is molded, the internal distortion due to the heat shrinkage occurs more in the elastic body 16, but also in this case, due to the injection pressure of the outer member 14. Internal distortion can be reduced or eliminated by applying sufficient pre-compression.

  Further, at least before the outer member 14 is molded, a gap 36 is formed between the axial end surface of the elastic body 16 and the outer molding die 30, and the concave end surface 22 of the elastic body 16 is formed on the outer side in the axial direction. Deformation to is allowed. Therefore, the compression deformation inward in the radial direction of the elastic body 16 accompanied by the bulging outward in the axial direction is efficiently generated by using the injection pressure of the outer member 14, and the internal strain is effectively eliminated. To be realized. Although not necessarily clear in the figure, the gap 36 is communicated to the outside through a communication hole formed in the outer molding die 30, and by avoiding the action of the air spring, the axial direction of the elastic body 16 can be avoided. Outward bulging deformation is allowed. In the present embodiment, as is apparent from FIGS. 1 and 3, the gap 36 is formed not only before the outer member 14 but also after the injection molding, so that the elastic body 16 and the outer molding die are formed. Air remains between 30 and 30. However, it is sufficient that the gap 36 is provided at least before the outer member 14 is molded. After the outer member 14 is molded, the axial end surface of the elastic body 16 contacts the outer molding die 30 and the gap 36 disappears. It may be like this.

  Further, the formation of the gap 36 makes the concave end surface 22 of the elastic body 16 a free surface that is allowed to be elastically deformed (bulging deformation toward the gap 36), and the rigidity of the elastic body 16 in the radial direction is increased. The outer end portion in the axial direction is smaller than the central portion in the axial direction. Therefore, the cylindrical outer peripheral surface 23 of the elastic body 16 is pushed to the inner peripheral side by the injection pressure of the outer member 14 so that the axial outer end portion is larger than the axial central portion. As a result, as shown in FIG. 1, after the outer member 14 is molded, the outer peripheral surface of the elastic body 16 is gradually curved toward the inner peripheral side as it goes outward in the axial direction in the longitudinal section. 21 is deformed.

  In addition, the end face in the axial direction of the elastic body 16 is a concave end face 22, the rubber volume at the end in the axial direction of the elastic body 16 is reduced, and a large free surface is secured. As a result, the axial end surface is efficiently allowed to bulge outward in the axial direction, and the axial outer end portion is more easily pushed into the inner peripheral side than the axial central portion. The cylindrical outer peripheral surface 23 of the elastic body 16 is easily deformed into a curved cylindrical outer peripheral surface 21 having a predetermined shape. In addition, the concave end surface 22 of the elastic body 16 is deformed into a convex end surface 17 that has a convex curved shape in the longitudinal section by bulging outward in the axial direction by the injection molding pressure of the outer member 14.

  Note that the lip portions 18 provided at both end portions in the axial direction of the elastic body 16 are strongly pressed against the wall inner surface of the cavity 32 by the injection pressure of the forming material of the outer member 14. It is possible to prevent the forming material from entering the gap 36. In particular, in the present embodiment, the axially inner surfaces of the lip portions 18 and 18 are inclined surfaces, and the lip portion 18 gradually becomes thinner toward the outer peripheral side, so that the material for forming the outer member 14 is injected. The lip portions 18 and 18 are stably pressed against the wall inner surface of the cavity 32 by the pressure. Therefore, the synthetic resin can be more effectively prevented from entering the gap 36 when the outer member 14 is molded. By providing such a lip portion 18, the injection pressure of the outer member 14 can be set relatively large, and sufficient precompression can be applied to the elastic body 16. Therefore, even when the two-color molding in which the outer member 14 is molded before the elastic body 16 is cooled, the internal strain of the elastic body 16 can be sufficiently reduced.

  Then, after the outer member 14 is cooled and solidified, the suspension bush 10 is obtained by taking out the outer member 14 from the outer molding die 30. Thus, the outer molding process is completed, and the manufacturing process of the suspension bush 10 is completed.

  According to the method for manufacturing the suspension bush 10 according to this embodiment, the elastic body 16 can be formed in a very short time by injection molding of a thermoplastic elastomer. Therefore, the suspension bush 10 can be manufactured with excellent mass productivity.

  Further, the outer member 14 can also be formed in a short time by injection molding of a synthetic resin, and the outer member 14 is formed on the outer peripheral surface of the elastic body 16 after the elastic body 16 is molded, so that the molten outer member 14 is formed. Since the outer member 14 and the elastic body 16 are fused by the heat of the member 14, the outer member 14 and the elastic body 16 can be fixed to each other without adding a process such as applying an adhesive.

  Further, in the outer molding step, the compression pressure of the elastic body 16 in the radial direction is applied by applying the injection pressure of the material forming the outer member 14 to the cylindrical outer peripheral surface 23 of the elastic body 16. Therefore, the internal strain of the elastic body 16 can be eliminated with a small number of steps while employing the outer member 14 made of a synthetic resin, which is difficult to pre-compress by the diameter reduction processing after molding.

  FIG. 4 shows an automotive torque rod 40 as a second embodiment of the present invention. The torque rod 40 has a structure in which a pair of bush portions 42, 42 as a vibration isolator are connected by a rod body 44. In FIG. 4, one bush portion 42 and the end portion of the rod body 44 on the bush portion 42 side are illustrated, and the other bush portion 42 and the other end portion of the rod body 44 are connected to one of the bush portions 42. Since the structure is substantially the same as that of the side, the illustration is omitted here.

  More specifically, the bush portion 42 has a structure in which the inner member 12 is inserted into the cylindrical portion 48 of the outer member 46, and the inner member 12 and the cylindrical portion 48 are elastically connected by the elastic body 16. Yes. The cylindrical portion 48 is formed of a hard synthetic resin and has a substantially cylindrical shape. Furthermore, a rod main body 44 is integrally formed on a part of the circumference of the cylindrical portion 48 so as to protrude radially outward, and the pair of cylindrical portions 48, 48 are connected to each other by the rod main body 44. Yes. The outer member 46 includes a pair of cylindrical portions 48, 48 and a rod body 44. Further, since the structure of the cylindrical portion 48 of the present embodiment is substantially the same as the structure of the outer member 46 in the first embodiment, description thereof is omitted here.

  In such a torque rod 40, the same effect as the suspension bush 10 shown in the first embodiment can be obtained in the bush portion 42. Further, as is apparent from the structure of the present embodiment, the outer member 46 is not necessarily limited to the entire cylindrical member, and may be provided with a cylindrical portion 48, and a plurality of cylindrical portions 48 may be provided. May be provided. In particular, since the outer member 46 is formed of a synthetic resin, the outer member 46 can be reduced in weight as compared with a metal product and can be easily formed into an arbitrary shape.

  As mentioned above, although embodiment of this invention was explained in full detail, this invention is not limited by the specific description. For example, the outer peripheral surface of the elastic body and the inner peripheral surface of the cylindrical portion of the outer member may be, for example, a cylindrical shape having a constant diameter over the entire length in the axial direction. It may be inclined to the side. Such a shape is realized, for example, by making the outer peripheral surface of the elastic body gradually incline toward the inner peripheral side as it goes outward in the axial direction in the elastic body forming step.

  Moreover, in the said embodiment, although the lip | rip part 18 was integrally formed in the elastic body 16, the lip | rip part 18 is not essential and may be abbreviate | omitted.

  In the above-described embodiment, the gap 36 is formed by separating the entire axial end surface of the elastic body 16 (except for the lip portion 18) from the wall inner surface of the cavity 32. The gap 36 may be formed by the axial end face being partially separated from the wall inner surface of the cavity 32. In short, in the state where the elastic body 16 is set in the outer mold 30, the entire axial end surface of the elastic body 16 does not necessarily have to be a free surface.

  Further, the outer member may be entirely formed of a synthetic resin, but for example, a structure in which only a cylindrical portion is formed of a synthetic resin may be employed. Specifically, for example, in the torque rod 40 of the second embodiment, the rod body 44 constituting the outer member 46 is formed of a metal such as iron or aluminum alloy, and synthetic resin is formed at both ends of the rod body 44. It is also possible to employ a structure in which a cylindrical portion 48 made of metal is fixed.

  In addition, the method of molding the outer member (cylindrical portion) formed of an elastic body made of thermoplastic elastomer or hard synthetic resin is preferably the injection molding exemplified in the above embodiment, but is not necessarily limited. Absent.

  Further, the application range of the present invention is not limited to the suspension bush and the bush portion of the torque rod, but can also be applied to an engine mount, a body mount, and the like. Furthermore, the present invention can be suitably applied not only to a vibration isolator used for automobiles but also to a vibration isolator used for motorcycles, railway vehicles, industrial vehicles, and the like.

10: Suspension bush (vibration isolation device), 12: Inner member, 14: Outer member (cylindrical portion), 16: Elastic body, 17: Convex end surface, 18: Lip portion, 21: Curved cylindrical outer peripheral surface, 22 : Concave end surface, 23: cylindrical outer peripheral surface, 25: mold for elastic body molding, 26: cavity, 30: mold for outer molding, 32: cavity, 36: gap, 40: torque rod, 42: bush part (Vibration isolator), 46: outer member, 48: cylindrical portion

Claims (5)

In the vibration isolator in which the inner member is inserted into the cylindrical portion of the outer member, and the inner member and the cylindrical portion of the outer member are elastically connected by an elastic body,
The elastic body is made of a thermoplastic elastomer and is fixed to the inner member, and the cylindrical portion of the outer member is made of synthetic resin and formed on the outer peripheral surface of the elastic body. The portion and the elastic body are in a fusion- fixed state , and
Concave pressing force of the cylindrical portion against the cylindrical outer peripheral surface of the elastic body having an axial end face is exerted of your is, the axial end surface of the elastic body is bulged deformed axially outward And the outer peripheral surface of the elastic body fused to the inner peripheral surface of the cylindrical portion is gradually inclined toward the inner peripheral side as it goes outward in the axial direction in the longitudinal section. Anti-vibration device. Ri Contact the cylindrical portion press force is exerted of the cylindrical outer peripheral surface of the elastic body, with an axial end surface of the elastic body is in a state that bulges deformed axially outward, in longitudinal section The vibration isolator according to claim 1, which has a convex shape. The inner member is inserted into the cylindrical portion of the outer member, and the inner member and the cylindrical portion of the outer member are elastically connected by an elastic body, and the manufacturing method of the vibration isolator,
After the inner member is prepared and set in an elastic body molding die, the elastic body is molded by filling the cavity of the elastic body molding mold with a molten thermoplastic elastomer, and the elastic body An elastic body forming step of fixing the inner member to the inner member;
After the elastic body molded in the elastic body molding step is set in an outer molding die, the outer molding die is filled with a synthetic resin heated and melted on the outer peripheral surface of the elastic body. An anti-vibration device manufacturing method comprising: forming the tubular portion of the outer member, and an outer forming step of fusing the tubular portion and the elastic body to each other. A gap is provided between at least a part of both axial end surfaces of the elastic body set in the outer molding die before molding the cylindrical portion and the inner wall surface of the cavity of the outer molding die. The cylindrical end surface of the elastic body having a concave axial end face is swelled outward in the axial direction by exerting a pressing force during molding of the cylindrical portion on the cylindrical outer peripheral surface of the elastic body. The vibration isolator according to claim 3 , wherein the vibration isolator is deformed and gradually inclined toward the inner peripheral side as it goes outward in the axial direction in the longitudinal section of the elastic body fused to the inner peripheral surface of the cylindrical portion. Production method. The axial end surface of the elastic body is bulged outwardly in the axial direction and deformed into a convex shape in the longitudinal section by exerting a pressing force at the time of molding the cylindrical portion on the cylindrical outer peripheral surface of the elastic body. Item 5. A method for manufacturing a vibration isolator according to Item 4 .

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