JP2000240725A - Dynamic damper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress exposure of a mass metal fitting surface as small as possible to abolish rustproofing treatment. SOLUTION: This dynamic damper has a rubber covering layer 4 integrally formed with a rubber elastic body 3 by vulcanization molding together with a mass metal fitting 2, to cover a surface of the mass metal fitting 2 together with the rubber elastic body 3. The rubber covering layer 4 is molded with the mass metal fitting 2 positioned by positioning pins each at least partially having a crest-shaped positioning pin including a crest-shaped projecting tip section in line contact with the surface of the mass metal fitting 2. Thereby, the rubber covering layer 4 has positioning recessed parts 4a formed corresponding to the crest-shaped positioning pins. A central part of the positioning recessed part 4a is formed with a linear exposed part 2c wherein the surface of the mass metal fitting 2 is exposed in a thin line shape by the line contact of the tip of the crest-shaped positioning pin with the peripheral face of the mass metal fitting 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic damper which is attached to a vibration system such as a drive shaft or a differential of an automobile, an engine mount bracket, a motor housing, and suppresses harmful vibration generated in the vibration system.

[0002]

2. Description of the Related Art Conventionally, as a dynamic damper attached to a drive shaft of an automobile, FIGS.
0 is known. The dynamic damper includes a pair of mounting portions 11 and 11 which are formed in a ring shape of a rubber material, are disposed at an axial distance from each other, and are fixed and held on the outer periphery of the drive shaft. Mass metal fittings 12 arranged at a distance between the parts 11, 11;
It is composed of a pair of rubber elastic bodies 13, 13 interposed between them and 1 and 11 to integrally connect them, and a rubber coating layer 14 covering the surface of the mass metal fitting 12.

[0003] Attachment portions 11, 1 of this dynamic damper.
1. The rubber elastic bodies 13, 13 and the rubber coating layer 14 are integrally formed by vulcanization molding with the same rubber material. In this case, the mass metal fitting 12 is placed in a vulcanization mold, and vulcanization molding is performed together with the mass metal fitting 12, thereby forming a rubber coating layer 14 covering the surface of the mass metal fitting 12 together with the rubber elastic bodies 13, 13. Is done.

At this time, the mass metal fitting 12 arranged in the vulcanization mold is positioned in three axial directions by positioning pins projecting from the mold surface of the vulcanization mold, and in this state, the rubber coating layer 14 and the like are provided. Vulcanization molding is performed. Therefore, the rubber coating layer 14 is not formed in a portion where the positioning pin contacts the mass metal fitting 12, and an exposed portion 12a of the mass metal fitting 12 is formed corresponding to the shape of the contact portion.

In this case, since the positioning pins are formed so as to be in surface contact with the surface of the mass metal fitting 12 from the viewpoint of strength and the like, the exposed area of the exposed portion 12a is large, and the rust generation rate is low. Get higher. Therefore, conventionally, when performing vulcanization molding of the rubber coating layer 14, an adhesive for bonding the formed rubber coating layer 14 to the mass metal fitting 12 is applied to the entire surface of the mass metal fitting 12, Alternatively, after the rubber coating layer 14 is formed, the exposed portion 12
A was coated with a paint or the like to perform a rust prevention treatment.

[0006]

By the way, the above-mentioned conventional dynamic damper has a rubber coating layer 14 of the mass metal fitting 12.
The rust-prevention treatment is applied to the parts that are not coated, which increases the number of manufacturing steps and reduces productivity, and also requires special equipment for that, which inevitably increases costs. It is the current situation.

However, the positioning pin which causes the formation of the exposed portion 12a of the mass metal fitting 12 cannot be simply eliminated. That is, when the mass metal fittings 12 are arranged in the vulcanization mold, the positioning pins for regulating the lateral movement of the mass metal fittings 12 are necessary to prevent the center of the mass metal fittings 12 from being misaligned with the center of the product. If the misalignment occurs, the thickness dimension of the formed rubber coating layer 14 and the like becomes unbalanced, so that it is easy to cause an air defect or insufficient rubber at the time of vulcanization molding, so that it cannot be eliminated.

In addition, since the positioning pin which comes into contact with the surface of the mass metal fitting 12 in the direction of gravity and the direction of antigravity receives a large pressing pressure of the vulcanizing mold in addition to the weight of the mass metal fitting 12, the contact area is particularly small. It is formed so as to be in surface contact so as to increase, and reducing the contact area is
It is difficult because there are many strength problems (breakage and wear of the positioning part) and maintenance problems.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a problem to be solved is to provide a dynamic damper capable of minimizing the exposure of the surface of the mass metal fitting and eliminating the rust prevention treatment. Is what you do.

[0010]

According to the first aspect of the present invention, there is provided an attachment section fixedly held by a vibration system,
A mass metal fitting arranged at a distance from the mounting portion, a rubber elastic body interposed between the mass metal fitting and the mounting portion and integrally connecting the two, and vulcanized and molded together with the mass metal fitting. A rubber coating layer formed integrally with the rubber elastic body and covering the surface of the mass metal fitting, wherein the rubber coating layer has a mountain-like cross section at the tip end in line contact with the surface of the mass metal fitting. Means having a positioning recess formed corresponding to the mountain-shaped positioning pin by being formed in a state where the mass metal fitting is positioned by a plurality of positioning pins having at least a part of the mountain-shaped positioning pin projecting to Is adopted.

According to this means, when the rubber coating layer covering the surface of the mass metal fitting and the rubber elastic body are formed by vulcanization molding, the mass metal fitting is formed by the positioning pin having at least a part of the mountain-shaped positioning pin. The rubber coating layer and the like are formed in the positioned state. At this time, the rubber coating layer
A positioning recess is formed corresponding to the mountain-shaped positioning pin. An exposed portion is formed in the center of the positioning concave portion, where the tip of the mountain-shaped positioning pin makes line contact with the surface of the mass metal fitting, thereby exposing the surface of the mass metal fitting to a thin line.
In addition, when the injection pressure of the rubber material is extremely high, or when a slight gap (about 0.5 mm) is formed between the tip of the mountain-shaped positioning pin and the surface of the mass metal fitting due to dimensional variation of the mass metal fitting or the like. In this case, the rubber material enters the gap by the injection pressure of the rubber material to form a thin rubber coating layer, so that the surface of the mass metal fitting is not exposed. Therefore, the exposed portion of the mass metal fitting is hardly formed in the positioning concave portion of the rubber coating layer, and even if the exposed portion is formed, the exposed portion is formed so that the surface of the mass metal fitting is exposed in a thin line shape. Therefore, the exposed area of the surface of the mass metal fitting is significantly reduced.

Therefore, according to the present invention, when forming the rubber coating layer, the exposure of the surface of the mass metal fitting formed at the portion where the positioning pin comes into contact with the mass metal fitting can be suppressed as much as possible, and the exposed portion of the mass metal fitting can be suppressed. It is possible to abolish the rust prevention treatment applied to The rubber coating layer in the present invention covers the surface of the mass metal fitting to prevent rust and damage, and is formed integrally with the rubber elastic body by vulcanization molding together with the mass metal fitting. . The rubber coating layer has a positioning recess formed corresponding to the mountain-shaped positioning pin which is in line contact with the surface of the mass metal fitting. This mountain-shaped positioning pin is provided on at least a part of the positioning pin for positioning the mass metal fitting arranged in the vulcanization mold.
From the viewpoint of strength and maintenance, the mountain-shaped positioning pin may be provided at a position that restricts the lateral movement of the mass metal fitting arranged in the vulcanization mold as described in claim 2. it can. In this case, in order to restrict the lateral movement of the mass metal fitting, it is sufficient that at least three ridge-shaped positioning pins are provided around the lateral direction of the mass metal fitting.

Further, as described in claim 3,
It is preferable that the tip cross section of the mountain-shaped positioning pin is formed in an arc shape having a radius of curvature of 20 mm or less. According to this means, the exposed portion of the mass metal fitting formed by the line-shaped contact of the mountain-shaped positioning pin with the surface of the mass metal fitting can be formed into an extremely thin line, and the exposed area of the mass metal fitting can be further reduced. It becomes possible.

The mass metal fitting according to the present invention functions as a mass body that resonates by input vibration, and is formed of steel or the like to have a predetermined weight. Depending on the structure of the dynamic damper, the mass metal fittings may have various shapes such as a cylindrical shape or a block shape. As described in claim 4, as the mass metal fitting of the present invention, a metal fitting whose surface is not coated with an adhesive can be adopted.
According to this means, the number of manufacturing steps can be reduced, productivity can be improved, and cost can be reduced.

The mounting portion in the present invention is a portion for fixing the dynamic damper to the vibration system, and can be freely configured according to the shape of the fixed portion of the vibration system. This mounting portion may be formed of the same rubber material as the rubber elastic body or the rubber coating layer of the present invention, or may be formed of a rigid material such as metal or resin. The rubber elastic body according to the present invention is formed of a rubber material so as to be elastically deformable, and is disposed between the mass metal fitting and the mounting portion so as to integrally connect the two. This rubber elastic body is formed integrally with the rubber coating layer when the rubber coating layer covering the surface of the mass metal fitting is formed by vulcanization molding.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. [Embodiment 1] FIG. 1 is a plan view of a dynamic damper according to the present embodiment, FIG. 2 is a sectional view taken along the line II-II of FIG. 1, and FIG. It is a side view which expands and shows.

The dynamic damper of this embodiment has a cylindrical mounting portion 1 fixedly held on the outer periphery of a drive shaft.
A cylindrical mass fitting 2 coaxially arranged at a distance from the mounting portion 1, and a ring-shaped rubber elastic body interposed between the mass fitting 2 and the mounting portion 1 to integrally connect the two. 3, a rubber coating layer 4 formed by vulcanization molding together with the mass metal fitting 2, covering the surface of the mass metal fitting 2 in a non-adhered state, and having a positioning recess 4a formed corresponding to the mountain-shaped positioning pin; As a main element.

The mounting portion 1 is formed in a cylindrical shape by vulcanizing a rubber material. On one end side of the mounting portion 1, a concave portion 1 on which a mounting tool (not shown) such as a belt is mounted.
a is formed. The mounting portion 1 is integrally formed at the same time when a rubber elastic body 3 and a rubber coating layer 4 described later are formed by vulcanization molding. The mass metal fitting 2 is formed in a cylindrical shape with steel so as to have a predetermined mass. The mass metal fitting 2 is formed to have a shorter length than the mounting portion 1, and is coaxially arranged at a distance outside the mounting portion 1 so as not to overlap with the concave portion 1 a of the mounting portion 1. In the center of the mass metal fitting 2, eight through holes 2a penetrating in the radial direction are provided at equal angular intervals.

The rubber elastic body 3 is formed in a ring plate shape by vulcanizing a rubber material. The rubber elastic body 3 is integrally formed at the same time as the mounting portion 1 and the rubber coating layer 4 described later are formed by vulcanization molding. The rubber elastic body 3 has its inner peripheral side connected to the outer peripheral surface of the mounting portion 1 and its outer peripheral side connected to the inner peripheral surface of the mass metal fitting 2, thereby integrally connecting the two. In addition, three ribs 3a, 3b extending in the radial direction are provided at equal angular intervals on both front and back surfaces of the rubber elastic body 3, respectively. The ribs 3a on the front side and the ribs 3b on the back side are formed so as to be out of phase by 60 °.

The rubber coating layer 4 is formed by vulcanizing and molding a rubber material together with the mass metal fitting 2, thereby covering the surface of the mass metal fitting 2. This rubber coating layer 4
Are made of the same rubber material as the mounting portion 1 and the rubber elastic body 3 and are formed integrally therewith. When vulcanizing the rubber coating layer 4 or the like, the mass metal fitting 2 whose surface is not intentionally coated with an adhesive is arranged in a vulcanizing mold, and the mass metal fitting 2 is used as a vulcanization mold. It is performed in a state where it is positioned by a mountain-shaped positioning pin and a planar positioning pin projecting from a surface.

In this case, with respect to the mass metal fitting 2 arranged in the vulcanization mold so that both ends in the axial direction are in the vertical direction, a position opposing a corner where the upper end surface and the outer peripheral surface of the mass metal fitting 2 intersects. In addition, a planar positioning pin that makes surface contact with the upper end surface of the mass metal fitting 2 and a mountain-shaped positioning pin that makes line contact with the outer peripheral surface (side surface) of the mass metal fitting are integrally provided. In addition, mass metal fitting 2
At the position facing the corner where the lower end surface and the outer peripheral surface intersect,
A planar positioning pin that makes surface contact with the lower end surface of the mass metal fitting 2 and a mountain-shaped positioning pin that makes line contact with the outer peripheral surface (side surface) of the mass metal fitting 2 are provided integrally. These mountain-shaped positioning pins and planar positioning pins are provided at equal angular intervals at four locations in the circumferential direction with respect to the cylindrical mass metal fitting 2.

As shown in FIG. 4, the ridge-shaped positioning pin 5 which comes into contact with the outer peripheral surface of the mass metal fitting 2 has a tip section having a curvature radius of 6.
It is formed in an arc shape of mm and protrudes in a mountain shape, and its tip is formed so as to linearly contact the outer peripheral surface of the mass metal fitting 2 along the axial direction. The mountain-shaped positioning pins 5 restrict the movement of the mass metal fitting 2 arranged in the vulcanization mold in the lateral direction (vertical direction and horizontal direction in FIG. 1). In addition, the planar positioning pin that contacts the upper and lower end surfaces of the mass metal fitting 2 has a front end surface formed in a semicircular plane,
The tip surface is formed so as to make surface contact with the upper and lower end surfaces of the mass metal fitting 2. The planar positioning pin regulates the movement of the mass metal fitting 2 disposed in the vulcanization mold in the direction of gravity and the direction of antigravity (vertical direction in FIG. 2).

The ridge-shaped positioning pin 5 thus formed
In addition, vulcanization molding is performed in a state where the mass metal fitting 2 is positioned by the planar positioning pin, whereby the rubber coating layer 4 and the like are formed. At this time, the rubber coating layer 4
Are not formed, and the surface of the mass metal fitting 2 is formed in a semicircular shape to form a planar exposed portion 2b which is exposed (see FIGS. 1 to 3). In a portion of the rubber coating layer 4 corresponding to the mountain-shaped positioning pin 5, a positioning recess 4 a is formed corresponding to the shape of the mountain-shaped positioning pin 5. At the center of the positioning concave portion 4a, a linear exposed portion 2c is formed in which the tip of the mountain-shaped positioning pin 5 makes linear contact with the outer peripheral surface of the mass metal fitting 2, thereby exposing the surface of the mass metal fitting 2 to a thin linear shape. Is formed (see FIGS. 1 to 3).

When the injection pressure of the rubber material at the time of vulcanization molding is extremely high, or due to dimensional variation of the mass metal fitting 2, a slight gap is formed between the tip of the mountain-shaped positioning pin 5 and the surface of the mass metal fitting 2. Is formed, the rubber material enters the gap by the injection pressure of the rubber material to form the thin rubber coating layer 4, so that the linear exposed portion 2 c is not formed on the outer peripheral surface of the mass metal fitting 2. .

In the dynamic damper of this embodiment configured as described above, the mounting portion 1 is fitted at a predetermined position on the outer peripheral surface of the drive shaft, and a mounting tool such as a belt is wound around the concave portion 1a of the mounting portion 1 and fixed. Used for use. And
When harmful vibration is generated by the operation of the drive shaft, the mass metal fitting 2 resonates through elastic deformation (mainly compression deformation) of the rubber elastic body 3 to attenuate the harmful vibration.

As described above, according to the dynamic damper of the present embodiment, the rubber coating layer 4 that covers the surface of the mass metal fitting 2 corresponds to the mountain-shaped positioning pin 5 that is in line contact with the surface of the mass metal fitting 2. The positioning recess 4a is formed, and in the positioning recess 4a, a linear exposed portion 2c is formed in which the surface of the mass metal fitting 2 is exposed as a thin line by the linear contact of the mountain-shaped positioning pin 5. Therefore, the exposed area of the surface of the mass metal fitting 2 can be significantly reduced.

Therefore, when the rubber coating layer 4 is formed by vulcanization molding, an adhesive is applied to the surface of the mass metal fitting 2, or after the rubber coating layer 4 is formed, the planar exposed portions 2b and It is possible to eliminate the rust preventive treatment performed by applying a paint or the like to the linear exposed portion 2c. As a result, the number of manufacturing steps can be reduced, the productivity can be improved, and the cost can be reduced.

In the dynamic damper of the above embodiment, when the mass metal fitting 2 is placed in the vulcanization mold when the rubber coating layer 4 and the like are formed by vulcanization molding, the lateral movement of the mass metal fitting 2 The positioning pin 5 is provided only at the position where the positioning is restricted.
As long as there is no problem in strength in forming the shape, the mountain-shaped positioning pin 5 can be provided at a position where the movement of the mass metal fitting 2 in the direction of gravity or the direction of antigravity is regulated. By doing so, the exposed area of the mass metal fitting 2 can be further greatly reduced.

Further, in the above-described embodiment, the linear exposed portion 2c formed by the linear contact of the mountain-shaped positioning pin 5 with the outer peripheral surface of the mass metal fitting 2 is formed along the axial direction on the outer peripheral surface of the mass metal fitting 2. Although it is formed to extend linearly, the method of forming the linear exposed portion 2c into a thin linear shape is not limited to this. For example, as in the above embodiment,
When a mountain-shaped positioning pin that makes line contact with the outer peripheral surface of the mass metal fitting 2 and a planar positioning pin that makes surface contact with the end face of the mass metal fitting 2 are integrally provided, the mountain-shaped positioning pin makes line contact only with the edge of the outer peripheral surface of the mass metal fitting 2. What is necessary is just to provide.
Thereby, as shown in FIGS. 5 and 6, the linear exposed portion 2 d formed on the outer peripheral surface of the mass metal fitting 2 has a thin linear shape extending in the circumferential direction along the edge of the outer peripheral surface of the mass metal fitting 2. Formed.

The dynamic damper according to the above-described embodiment has a structure having the cylindrical metal fitting 2, but is not limited to the dynamic damper having this structure. For example, the dynamic metal damper formed in a square block shape. The present invention can also be applied to a dynamic damper configured by using a dynamic damper. Further, the mounting portion 1 of the above embodiment is formed of a rubber material, but is not limited to this, and various types such as those formed of metal or resin can be adopted. In this case, when the rubber coating layer and the like are formed by vulcanization molding, the mounting portion is arranged in a vulcanization mold together with the mass metal fitting and integrally molded, so that assembly and production of the dynamic damper can be easily performed. It can be carried out.

[Embodiment 2] FIG. 7 is a plan view of a dynamic damper according to the present embodiment, and FIG.
FIG. 8 is a sectional view taken along line VIII. The dynamic damper according to the present embodiment includes a pair of mounting portions 6, 6 fixedly held on the outer periphery of the drive shaft, a cylindrical mass metal fitting 7 coaxially arranged at a distance from the mounting portions 6, 6, A rubber elastic body 8 that is interposed between the mass metal fitting 7 and the two mounting portions 6 and 6 and integrally connects the two, and is formed by vulcanization molding together with the mass metal fitting 7 so that the surface of the mass metal fitting 7 is not adhered. Coated in a state,
Positioning recess 9 formed corresponding to mountain-shaped positioning pin
and a rubber coating layer 9 having a.

The dynamic damper of this embodiment is of a type in which the rubber elastic body 3 in the first embodiment is configured to be deformed by compression, whereas the dynamic damper is configured so that the rubber elastic body 8 is subjected to shear deformation. In that it is of the type given. Therefore, a detailed description of members and the like common to the first embodiment will be omitted, and different points will be mainly described below.

The mounting portions 6, 6 of this embodiment are formed of two cylindrical members made of a rubber material, and are coaxially arranged at a distance in the axial direction. One mounting part 6
Is formed to be longer in the axial direction than the other mounting portion 6, and a concave portion 6 a to which a mounting tool (not shown) such as a belt is mounted is formed on one end side of the one mounting portion 6. I have. The rubber elastic body 8 of the present embodiment is formed in a ring shape by vulcanizing a rubber material, and the outer peripheral portion thereof is connected to the axially central portion of the inner peripheral surface of the mass metal fitting 7. On the inner peripheral side of the rubber elastic body 8, a pair of legs 8a, 8a extending from the inner peripheral end at the same angle in both axial directions are provided, and the pair of legs 8a, 8a is provided. Each tip is connected to the inner shaft end of each of the mounting portions 6,6. Thereby, both legs 8a, 8 of the rubber elastic body 8 are formed.
A ring-shaped concave portion 8b which is depressed outward from the inner peripheral surfaces of the mounting portions 6, 6 is formed in a portion between the portions a.

The rubber coating layer 9 of this embodiment is formed by the same method as the method of forming the rubber coating layer 4 of the first embodiment. Therefore, the rubber coating layer 9
When vulcanization molding is performed, mass metal fittings 7
A positioning concave portion 9a corresponding to the shape of the mountain-shaped positioning pin used for the positioning is formed, and a linear exposed portion 7c in which the surface of the mass metal fitting 7 is exposed in a thin linear shape is formed at the center of the concave portion 9a. Are formed. The rubber coating layer 9
At the outer peripheral portions at both ends of the metal plate, a surface-shaped exposed portion 7b is formed in which the surface of the mass metal fitting 7 is exposed in a semicircular shape. This rubber coating layer 9 is also formed to cover the surface of the mass metal fitting 7 in a non-adhered state, which is the same as the rubber coating layer 4 of the first embodiment.

The dynamic damper of the present embodiment configured as described above is used in the same manner as in the first embodiment, and causes the harmful vibration generated by the operation of the drive shaft to elastically deform the rubber elastic body 8. (Mainly both legs 8a, 8a
The mass metal fitting 7 resonates through the shear deformation of the mass metal 7 to effectively attenuate. Then, the dynamic damper of the present embodiment has the same operation and effects as those of the first embodiment.

In particular, the dynamic damper according to the present embodiment is of a type in which the rubber elastic body 8 is configured to undergo a shearing deformation. The dynamic damper is configured such that the shearing and deforming legs 8a, 8a approach each other in the axial direction. The outer peripheral portion of the rubber elastic body 8 is connected to the axially central portion of the inner peripheral surface of the mass metal fitting 7. That is, the rubber elastic body 8 is provided at a position as far as possible from the planar exposure portion 7b and the linear exposure portion 7c of the mass metal fitting 7. Therefore, even if rust occurs on the planar exposed portion 7b or the linear exposed portion 7c of the mass metal member 7, the rubber elastic body 8 related to the resonance characteristics of the mass metal member 7 can be obtained.
It is possible to prevent rust from eroding up to the connecting portion of.

[Brief description of the drawings]

FIG. 1 is a plan view of a dynamic damper according to Embodiment 1 of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is an enlarged side view showing a portion indicated by an arrow A in FIG. 2;

FIG. 4 is an explanatory view showing a state in which a mountain-shaped positioning pin makes line contact with the outer peripheral surface of the mass metal fitting when the mass metal fitting is placed in a vulcanization mold in the first embodiment of the present invention.

FIG. 5 is an enlarged sectional view showing a main part of a dynamic damper according to another embodiment of the present invention.

FIG. 6 is a side view as seen from the direction of arrow B in FIG. 5;

FIG. 7 is a plan view of a dynamic damper according to Embodiment 2 of the present invention.

FIG. 8 is a sectional view taken along line VIII-VIII in FIG. 7;

FIG. 9 is a plan view of a conventional dynamic damper.

FIG. 10 is a sectional view taken along line XX of FIG. 9;

[Explanation of symbols]

1, 6, 11: mounting portion 1a, 6a: concave portion 2, 7, 12: mass metal fitting 2a: through hole 2b, 7b: planar exposed portion 2c, 2d, 7c: linear exposed portion 3, 8, 13: rubber Elastic body 3a, 3b ... rib 4, 9, 14 ... rubber coating layer 4a, 9a ... positioning concave part 5 ... mountain-shaped positioning pin 8a ... leg part 8b ... concave part 12a ... exposed part

Claims (4)

[Claims] A mounting portion fixed to and held by a vibration system, a mass metal fitting arranged at a distance from the mounting portion, and interposed between the mass metal fitting and the mounting portion to integrally connect the two. A dynamic rubber damper comprising: a rubber elastic body to be formed; and a rubber coating layer formed integrally with the rubber elastic body by vulcanization molding together with the mass metal fitting to cover the surface of the mass metal fitting. By forming the mass fitting in a state where the mass fitting is positioned by a plurality of positioning pins having at least a part of a mountain-shaped positioning pin whose tip cross section in line contact with the surface of the mass metal fitting projects in a mountain shape, A dynamic damper having a positioning recess formed corresponding to a mountain-shaped positioning pin. 2. The dynamic damper according to claim 1, wherein the mountain-shaped positioning pin is provided at a position for restricting a lateral movement of the mass metal fitting disposed on the vulcanization mold. 3. The dynamic damper according to claim 1, wherein a cross section at the tip of the mountain-shaped positioning pin is formed in an arc shape having a radius of curvature of 20 mm or less. 4. The dynamic damper according to claim 1, wherein no adhesive is applied to a surface of said mass fitting.