Press-fit structure, press-fit member, and member to be press-fitted

Abstract

The present invention provides a press-fit structure, a press-fit member, and a press-fit member that offer excellent manufacturability and enable the acquisition of a larger pull-out load. [Solution] A press-fit structure in which a cylindrical, elastically deformable synthetic resin outer cylinder 2 is press-fitted into a press-fit hole 1A, wherein the press-fit hole 1A has a small-diameter portion 1B in which a portion with the same inner diameter D1 smaller than the outer diameter D2 of the resin outer cylinder 2 is continuous in the press-fit direction, and an enlarged-diameter portion 1C provided behind the small-diameter portion 1B in the press-fit direction and connected to the small-diameter portion 1B, and gradually expanding in diameter toward the back.

Description

Technical Field

[0001] The present invention relates to a press-fitting structure, a press-fitting member, and a press-fitted member.

Background Art

[0002] Generally, as a press-fitting structure for press-fitting a press-fitting member into a press-fitted member, the press-fitted member has a press-fitting hole in which a portion having the same inner diameter is continuous in the press-fitting direction, and a press-fitting member having an outer peripheral portion with an outer diameter slightly larger than the inner diameter of the press-fitting hole is press-fitted into the press-fitting hole. In such a press-fitting structure, a pull-out load is generated by the frictional force between the inner peripheral surface of the press-fitting hole and the outer peripheral surface of the press-fitting member.

[0003] Also, for example, Patent Document 1 discloses a press-fitting structure in which a rigid outer cylinder portion is press-fitted into a cylindrical holder in a bush-shaped vibration isolator rubber used as a body mount cushion. In this press-fitting structure, when the rigid outer cylinder portion is press-fitted into the cylindrical holder, the rigid outer cylinder portion protrudes to the front side from the cylindrical holder, and an engaging claw portion formed at the protruding tip portion of the rigid outer cylinder portion is engaged with an engaging receiving portion of the cylindrical holder to prevent the rigid outer cylinder portion from coming out of the cylindrical holder.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, as described above, when a pull-out load is generated by the frictional force between the inner surface of the press-fit hole and the outer surface of the press-fit member, increasing the compression allowance to generate a larger pull-out load results in increased press-fitting force and poor manufacturability, while decreasing the compression allowance makes the press-fit member more prone to coming loose. Furthermore, when the engaging claw portion is engaged with the engaging receiver portion of the cylindrical holder to prevent pull-out, a gap is created between the engaging claw portion and the engaging receiver portion, resulting in looseness and difficulty in obtaining stable performance.

[0006] Therefore, the object of the present invention is to provide a press-fit structure, a press-fit member, and a member to be press-fitted that are easy to manufacture and can obtain a larger pull-out load. [Means for solving the problem]

[0007] To achieve the above objective, the present invention is characterized in that a cylindrical, elastically deformable press-fit member made of synthetic resin is press-fitted into a press-fit hole, and the press-fit hole has a small-diameter portion in which a portion with the same inner diameter smaller than the outer diameter of the press-fit member is continuous in the press-fit direction, and an expanding-diameter portion which is provided connected to the back of the small-diameter portion in the press-fit direction and gradually expands in diameter toward the back. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a press-fit structure, a press-fit member, and a member to be press-fitted that offer excellent manufacturability and high pull-out load. Other problems, configurations, and effects will be clarified by the following description of embodiments. [Brief explanation of the drawing]

[0009] [Figure 1] This is a perspective view of a press-fit structure having a press-fit structure according to an embodiment of the present invention, as seen from the flange side. [Figure 2] This is a perspective view of a press-fit structure forming a press-fit structure according to an embodiment of the present invention, viewed from the side opposite the flange portion. [Figure 3]This is a cross-sectional view showing the holder and resin outer cylinder cut in the press-fit direction. [Figure 4] This is a cross-sectional view showing the press-fit structure cut in the press-fit direction. [Modes for carrying out the invention]

[0010] Hereinafter, one embodiment of the press-fit structure, press-fit member, and press-fit member according to the present invention will be described with reference to the drawings. The press-fit structure according to this embodiment is used, for example, as a body mount for fixing the vehicle body to a frame. As shown in Figures 1 and 2, it is a press-fit structure in which a resin outer cylinder 2 is press-fitted into a holder 1 which forms part of a member frame. In the following description, a press-fit structure 3 composed of a holder 1 as the member to be press-fitted and a resin outer cylinder 2 as the member to be press-fitted will be used as an example.

[0011] The holder 1 is made of aluminum or iron and, as shown in Figure 3, has a cylindrical shape that surrounds the press-fit hole 1A into which the resin outer cylinder 2 is press-fitted. The resin outer cylinder 2 is inserted into the holder 1 from the front side (upper side in Figure 2) to the back side (lower side in Figure 2) in the press-fitting direction of the press-fit hole 1A which penetrates through it, and then press-fitted.

[0012] The holder 1 is provided with a press-fit hole 1A having a small-diameter portion 1B that is continuous in the press-fit direction (predetermined direction) with the same inner diameter D1, and an enlarged diameter portion 1C that is connected to the small-diameter portion 1B on the far side (one side) of the small-diameter portion 1B in the press-fit direction, and whose inner diameter gradually expands toward the far side in the press-fit direction. The holder 1 also has a curved portion 1D on the near side of the small-diameter portion 1B in the press-fit direction, which curves so that its inner diameter expands toward the near side in the press-fit direction.

[0013] The resin outer cylinder 2 is made of an elastically deformable synthetic resin and has an outer cylinder portion 2A which is cylindrical in shape with a continuous and penetrating portion of the same outer diameter D2 in the press-fitting direction, and a flange portion 2B which is provided on the front edge of the outer cylinder portion 2A and protrudes in the expanding diameter direction to form an annular shape. The outer diameter D2 of the outer cylinder portion 2A is formed to be larger than the inner diameter D1 of the small diameter portion 1B of the holder 1, and further larger than the maximum inner diameter D3 of the expanded diameter portion 1C. In addition, the outer diameter D2 of the outer cylinder portion 2A is formed to be slightly smaller than the maximum inner diameter D4 of the curved portion 1D.

[0014] When press-fitting the resin outer cylinder 2 into the press-fit hole 1A of the holder 1, the tip side of the resin outer cylinder 2 that does not have a flange portion 2B is inserted from the front side in the press-fitting direction of the holder 1. At this time, the tip 2C of the resin outer cylinder 2 is guided by the curved portion 1D of the holder 1, and enters the small diameter portion 1B while elastically deforming so that the resin outer cylinder 2 is reduced in diameter.

[0015] Subsequently, as the resin outer cylinder 2 is further inserted into the press-fit hole 1A, the reduced diameter resin outer cylinder 2 slides along the press-fit hole 1A as its outer surface slides into the back of the small-diameter portion 1B.

[0016] Then, when the tip 2C of the resin outer cylinder 2 enters the enlarged diameter section 1C, the portion of the resin outer cylinder 2 that has entered the enlarged diameter section 1C slides along the inner circumferential surface of the enlarged diameter section 1C and moves further into the enlarged diameter section 1C. Subsequently, as shown in Figure 4, the flange portion 2B of the resin outer cylinder 2 comes into contact with the front end 1E of the holder 1, and the resin outer cylinder 2 is pressed into the holder 1.

[0017] At this time, the portion of the resin outer cylinder 2 that enters the enlarged diameter portion 1C gradually relaxes from its reduced diameter state, so the frictional force when the outer cylinder portion 2A slides in the enlarged diameter portion 1C becomes smaller than the frictional force when it slides in the small diameter portion 1B. For this reason, the pressing force when pressing the resin outer cylinder 2 into the holder 1 is smaller when the enlarged diameter portion 1C is provided than when the press-fit hole 1A is formed with the same inner diameter along its entire length.

[0018] When the resin outer cylinder 2 is press-fitted into the holder 1, the portion of the resin outer cylinder 2 that is reduced in diameter by the small-diameter portion 1B presses the inner peripheral surface of the small-diameter portion 1B toward the outer peripheral side, and the portion of the resin outer cylinder 2 that is reduced in diameter by the enlarged-diameter portion 1C presses the inner peripheral surface of the enlarged-diameter portion 1C toward the outer peripheral side. Therefore, when a force acts in the direction in which the resin outer cylinder 2 comes out of the holder 1, that is, toward the front side in the press-fitting direction, the frictional force generated between the outer peripheral surface of the resin outer cylinder 2 and the inner peripheral surface of the small-diameter portion 1B, and the force acting in the press-fitting direction among the frictional forces in the direction along the enlarged-diameter portion 1C generated between the outer peripheral surface of the resin outer cylinder 2 and the inner peripheral surface of the enlarged-diameter portion 1C presses the inner peripheral surface of the enlarged-diameter portion 1C, increasing the pulling-out force and making it difficult for the resin outer cylinder 2 to come out.

[0019] According to the press-fitting structure of this embodiment, the resin outer cylinder 2 made of synthetic resin that is elastically deformable and has a cylindrical shape with an outer diameter D2 larger than the small-diameter portion 1B is press-fitted into the press-fitting hole 1A formed in the holder 1, which has a small-diameter portion 1B where portions with the same inner diameter D1 are continuous in the press-fitting direction, and an enlarged-diameter portion 1C that is connected to the small-diameter portion 1B on the back side in the press-fitting direction and gradually increases in diameter toward the back side. Therefore, the press-fitting force during press-fitting can be made smaller than when press-fitting a press-fitting member into a press-fitting hole where only portions with the same inner diameter are continuous, and since the resin outer cylinder 2 presses both the small-diameter portion 1B and the enlarged-diameter portion 1C, it is possible to obtain a higher pulling-out load. As a result, excellent manufacturability and a high pulling-out load can be obtained.

[0020] Also, since the outer diameter D2 of the resin outer cylinder 2 is larger than the maximum inner diameter D3 of the enlarged-diameter portion 1C, it is possible to press the inner peripheral surface with the resin outer cylinder 2 even up to the end portion on the back side in the enlarged-diameter portion 1C. Therefore, since a pulling-out force can be generated over the entire area of the enlarged-diameter portion 1C, it is possible to obtain a larger pulling-out load.

[0021] The inventor of the present invention has conducted tests on the press-fitting force and the pulling-out force using an aluminum collar having an enlarged-diameter portion as the press-fitted member and a resin outer cylinder as the press-fitting member, and has confirmed the following results.

[0022] <Regarding the relationship between the shape of the enlarged-diameter portion and the press-fitting force> ·The smaller the tip drawing ratio of the diameter-expanded part (the larger the inclination angle), the lower the press-fitting force. ·The longer the length of the diameter-expanded part in the press-fitting direction, the lower the press-fitting force.

[0023] <Regarding the relationship between the length of the diameter-expanded part in the press-fitting direction and the normal-temperature pull-out force> ·In the case without a diameter-expanded part, "pull-out force (initial value) = pull-out force (maximum value)", and after the start of pull-out, the engagement length decreases as the displacement (= pull-out amount) increases, so the pull-out force decreases monotonically. ·In the case with a diameter-expanded part, in addition to the effect of pull-out force reduction similar to the case without a diameter-expanded part, there is an effect that the pull-out force increases due to the outer diameter of the outer cylinder being constricted in the diameter-expanded part as the pull-out amount increases. Therefore, the maximum value of the pull-out force is reached under the condition where the effect of pull-out force reduction and the effect of increasing pull-out force are balanced. ·The longer the diameter-expanded part in the press-fitting direction, the smaller the pull-out force (initial value).

[0024] <Regarding the relationship between the length of the diameter-expanded part in the press-fitting direction and the pull-out force after heat aging> ·In the case without a diameter-expanded part, the pull-out force decreases monotonically as in the normal-temperature case. ·In the case with a diameter-expanded part, the maximum value of the pull-out force is reached under the condition where the effect of pull-out force reduction and the effect of increasing pull-out force are balanced as in the normal-temperature case, but the length of the diameter-expanded part in the press-fitting direction is longer than that in the normal-temperature case. ·The longer the length of the diameter-expanded part in the press-fitting direction, the smaller the difference between the press-fitting force and the pull-out force. ·The longer the length of the diameter-expanded part in the press-fitting direction, the smaller the pull-out force (initial value).

[0025] <Regarding the relationship between the maximum inner diameter of the diameter-expanded part and the normal-temperature pull-out force> ·The larger the maximum inner diameter of the diameter-expanded part, the smaller the pull-out force (initial value). ·Regardless of the tip drawing diameter, the pull-out force (maximum value) is equivalent to the case without a diameter-expanded part. ·The larger the tip diameter, the smaller the press-fitting - pull-out force.

[0026] <Regarding the relationship between the maximum inner diameter of the diameter-expanded part and the pull-out force after heat aging> • Regardless of the maximum inner diameter of the enlarged section, the initial value of the release force will be the same. • The larger the maximum inner diameter of the enlarged section, the greater the maximum force that can be released.

[0027] One embodiment of the present invention has been described above. It should be noted that the present invention is not limited to the above-described embodiment and includes various other modifications. For example, the above-described embodiment is described in detail for the purpose of clearly illustrating the present invention and is not necessarily limited to having all the described configurations. Furthermore, it is possible to replace some of the configurations of this embodiment with those of other embodiments, and it is also possible to add configurations from other embodiments to the configuration of this embodiment. Moreover, it is possible to add, delete, or replace some of the configurations of this embodiment with those of other embodiments.

[0028] In the above embodiment, an example was described in which the press-fit structure of the present invention is used in a body mount for fixing the vehicle body to the frame. However, it is not limited to this, and may also be used in press-fit parts of engine mounts, motor mounts, bushings, strut mounts, cab mounts, subframe mounts, spring seats, air springs, and industrial vibration damping materials. [Explanation of Symbols]

[0029] 1: Holder 1A: Hole to be pressed in 1B: Small diameter section 1C: Expanded diameter part 1D: Curved section 1E: The front end of the holder 2: Resin outer cylinder 2A: Outer cylinder part 2B: Flange section 2C: Tip of the resin outer cylinder 3: Press-fit structure D1: Inner diameter of the small diameter section D2: Outer diameter of the outer cylinder D3: Maximum inner diameter of the enlarged section D4: Maximum inner diameter of the curved section

Claims

1. A press-fit structure in which a cylindrical, elastically deformable press-fit member made of synthetic resin is press-fitted into a press-fit hole, The aforementioned press-fit hole comprises a small-diameter portion having the same inner diameter smaller than the outer diameter of the press-fit member, which is continuous in the press-fit direction, In the press-fitting direction, an enlarged diameter portion is provided on the inner side of the small diameter portion, connected to the small diameter portion, and gradually widens toward the inner side. A press-fit structure characterized by having the following features.

2. In the press-fit structure described in claim 1, A press-fit structure characterized in that the outer diameter of the press-fit member is larger than the maximum inner diameter of the enlarged portion.

3. A small-diameter section in which parts with the same inner diameter are continuous in a predetermined direction, In the predetermined direction, an enlarged diameter portion is provided on one side of the small diameter portion, connected to the small diameter portion, and gradually widens toward the one side; A press-fitted hole having the above-mentioned side is pressed in toward one side, A press-fit member characterized by having a cylindrical shape with an outer diameter larger than the inner diameter of the hole to be press-fitted, and being made of an elastically deformable synthetic resin.

4. A press-fit member having a press-fit hole into which a cylindrical, elastically deformable synthetic resin press-fit member is pressed, The aforementioned press-fit hole has a small-diameter portion in which the portion with an inner diameter smaller than the outer diameter of the press-fit member is continuous in the press-fit direction, In the press-fitting direction, an enlarged diameter portion is provided on the inner side of the small diameter portion, connected to the small diameter portion, and gradually widens toward the inner side. A press-fit member characterized by having the following features.

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