JP5015504B2 - Plastic joint structure of rotating member - Google Patents

Description

  The present invention relates to a plastic coupling structure of a rotating member for coupling members that transmit rotational force such as a hub and a shaft to each other by plastic coupling.

  For example, a plastic coupling structure is known as a structure for coupling a shaft and a hub used for an automatic transmission for an automobile to transmit rotational force. The plastic coupling structure forms serrations on the outer peripheral surface of the shaft-side coupling portion, and press-fits the outer peripheral surface of the shaft-side coupling portion into the inner peripheral surface of the hub-side coupling portion formed of a member having a lower hardness than the shaft. Then, the serration tooth profile is caused to bite into the inner peripheral surface of the hub-side coupling portion, and the hub-side material is plastically flowed between the tooth profiles to bond them together. As a result, a meshing connection between the serration-side tooth profile and the hub-side tooth profile formed by plastic flow occurs, and a large rotational force can be transmitted.

Further, in Patent Document 1, in the above-described plastic coupling structure, as shown in FIG. 7, the inclination angle α of one tooth surface 2 </ b> A with respect to the circumferential direction of the shaft 1 in the tooth profile of the serration 2 formed on the shaft 1 side. A structure with an obtuse angle is described. Thereby, when a positive rotational force T acts between the shaft 1 and the hub 3, the force F acting on the tooth profile of the serration 2 is applied to the component force F1 and the tooth surface 2A in the direction along the tooth surface 2A. The component force F2 in the vertical direction can be disassembled, and among these, the component force F1 in the direction along the tooth surface 2A acts in the direction of reducing the diameter of the hub 3, so that there is a gap between the shaft 1 and the hub 2. The torsional strength can be improved.
JP 2004-195475 A

  However, the plastic coupling structure shown in FIG. 7 has the following problems. By making the inclination angle α of one tooth surface 2A in the tooth profile of the serration 2 an obtuse angle, the width W of the base portion of the tooth profile of the serration 2 is reduced, and the root side of the base portion of the tooth surface 2A is an acute angle and stress. Since it becomes easy to concentrate, the intensity | strength of the serration 2 will fall.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a plastic coupling structure of a rotating member capable of increasing the strength against a rotational force acting between members coupled to each other.

In order to solve the above-mentioned problem, the invention according to claim 1 is characterized in that serrations are formed on the outer peripheral surface of the coupling portion of the first rotating member, and the hardness of the second rotating member is lower than that of the first member. The outer peripheral surface of the coupling portion of the first rotating member is press-fitted into the inner peripheral surface so that the serration tooth profile is bitten into the inner peripheral surface and the material on the second member side is plastically flowed between the tooth profiles. Accordingly, in the plastic coupling structure of the rotating member that couples the first rotating member and the second rotating member, one tooth surface of the tooth profile has an acute angle with respect to the circumferential direction of the first rotating member. The other tooth surface of the tooth profile has an obtuse angle with respect to the circumferential direction of the first rotating member of the surface of the end of the tooth, and the surface of the tooth base is the circumference of the first rotating member. It is formed so as to be substantially perpendicular to the direction Plastic coupling structure of the rotary member according to the invention of claim 2 is, in the configuration of the first aspect, wherein the angle of inclination, characterized in that it is in the range of 120 ° to 160 °.
According to a third aspect of the present invention, in the plastic coupling structure of the rotating member according to the first or second aspect, the first rotating member is a shaft and the second rotating member is a hub.

  According to the plastic coupling structure of the rotating member according to the present invention, when the rotational force is applied, the second rotating member is contracted when the inclination angle of the surface of the tooth end side of the serration with respect to the circumferential direction is an obtuse angle. It is possible to generate a component force in the direction of diameter, and by making the root side of the serration tooth profile substantially perpendicular to the circumferential direction, the width of the tooth profile base is increased and the tooth profile strength is increased. Therefore, the strength against rotational force can be increased.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
The shaft-hub assembly assembled by the plastic coupling structure according to the present invention is shown in FIGS. As shown in FIGS. 4 and 5, the shaft-hub assembly 4 is a component that is used for an automatic transmission for an automobile and transmits a rotational force, and is one end of a substantially cylindrical shaft 5 (first rotating member). The bottom part of the substantially bottomed cylindrical hub 6 (second rotating member) is joined to the part by the plastic joint structure according to the present invention.

  One end of the shaft 5 is expanded in diameter to form a large-diameter portion 7, and the end of the large-diameter portion 7 is expanded in diameter to form a flange-shaped coupling portion 8. A serration 9 is formed on the outer peripheral surface of the coupling portion 8. The shaft 5 is made of, for example, SMC420H (carburized chromium molybdenum steel) and has a Vickers hardness of about Hv800.

  A cylindrical coupling portion 10 into which the coupling portion 8 of the shaft 5 is fitted is formed at the center of the bottom portion of the hub 6. Flange-shaped crimping portions 11 and 12 that are in contact with both end portions of the coupling portion 8 of the shaft 5 fitted in the coupling portion 10 are formed on inner peripheral portions at both ends of the coupling portion 10. The hub 6 is made of, for example, SPHD (hot rolled steel plate), has a Vickers hardness of about Hv100, and is lower in hardness than the shaft 5.

Next, a coupling structure between the shaft 5 and the hub 6 will be described with reference to FIGS.
As shown in FIGS. 1 and 2, serrations 9 are formed on the outer peripheral surface of the coupling portion 8 of the shaft 5. The tooth profile of the serration 9 is an acute angle having an inclination angle β of about 35 ° with respect to the circumferential direction of the coupling portion 8 of the shaft 5 on the right tooth surface 13 in the drawing. In addition, the tooth surface 14 on the left side in the drawing has an obtuse angle of about 150 ° with respect to the circumferential direction of the coupling portion 8 of the end surface 14A, and the tooth base surface 14B is the coupling portion 8. Is substantially perpendicular to the circumferential direction. The inclination angle γ of the end surface 14A is an obtuse angle, preferably 120 ° to 160 °. The tooth tip portion 15 of the tooth shape of the serration 9 is formed with a roundness having a radius R1 of about 0.3 mm. Further, the base of the tooth surface 14 is rounded with a radius R2, and this radius R2 is preferably as large as possible.

  Then, the coupling portion 8 of the shaft 5 is press-fitted into the coupling portion 10 of the hub 6, the tooth profile of the serration 9 bites into the inner peripheral surface of the coupling portion 10 of the hub 6, and the material on the hub 6 side is plastic between the tooth profiles of the serration 9. The tooth profile formed in the coupling portion 10 on the hub 6 side and the tooth profile of the serration 9 mesh with each other. Further, the coupling portion 8 of the shaft 5 is clamped by the caulking portions 11 and 12 formed at both ends of the coupling portion 10 of the hub 6 and fixed in the axial direction.

  Next, an assembly process by plastic coupling between the shaft 5 and the hub 6 will be described with reference to FIG. As shown in FIG. 6 (A), the shaft 5 is inserted into a die 17 having a gear cutting portion 16 for forming a serration 9, and the connecting portion 8 of the shaft 5 is pushed into the gear cutting portion 16 by a punch 18. Serrations 9 are formed on the outer peripheral surface of the joint 8.

  As shown in FIG. 6B, the hub 6 is set on the dies 18 and 19, the shaft 5 is inserted into the dies 18 and 19, and the coupling portion 8 of the shaft 5 on which the serration 9 is formed by the punch 20. 6 into the joint 10. Thereby, the tooth profile of the serration 9 bites into the joint 10 of the hub 6, and the material on the hub 6 side plastically flows between the tooth profiles of the serration 9, and the tooth profile formed on the joint 10 of the hub 6 and the tooth profile of the serration 9. Mesh with each other. Further, a caulking portion 11 is formed at the lower end portion of the coupling portion 10 of the hub 6.

  As shown in FIG. 6C, the upper end portion of the coupling portion 10 of the hub 6 is pressed by the punch 21 to form the crimping portion 12, and the crimping portions 11 formed at both ends of the coupling portion 10 of the hub 6, 12 fixes the joint 8 of the shaft 5 in the axial direction. In this way, the shaft 5 and the hub 6 can be coupled to each other by plastic coupling.

The operation of the present embodiment configured as described above will be described next.
The shaft 5 and the hub 6 are coupled by meshing the tooth profile of the serration 9 formed on the coupling portion 8 on the shaft 5 side with the tooth profile formed by plastic flow on the coupling portion 10 on the hub 6 side. Rotational force can be transmitted between them.

  As shown in FIG. 3, when a positive rotational force T acts between the shaft 5 and the hub 6, the force f acting on the tooth top portion 15 of the tooth profile of the serration 9 follows the inclined surface. Can be broken down into a component force f1 in the direction perpendicular to the inclined surface and a component force f2 in the direction perpendicular to the inclined surface, and the component force f1 in the direction along the inclined surface expands the diameter of the connecting portion 10 of the hub 5. Act on. Here, since the tip 15 is rounded at least about R1 = 0.3 mm due to its manufacturing method, and it is very difficult to make it completely pointed. The component force f1 acting in the direction of expanding the diameter of 10 cannot be eliminated.

  Further, when a positive rotational force T acts between the shaft 5 and the hub 6, the force F acting on the end surface 14A of the tooth profile of the serration 9 is a direction along the end surface 14A. The component force F1 and the component force F2 in the direction perpendicular to the end surface 14A can be decomposed, and the component force F1 in the direction along the end surface 14A is the end force side. Since the inclination angle γ of the surface 14A is an obtuse angle, it acts in the direction of reducing the diameter of the coupling portion 10 of the hub 6.

  As a result, the component force f1 acting in the direction of expanding the diameter of the connecting portion 10 of the hub 5 generated at the tooth tip portion 15 of the tooth profile of the serration 9 and the diameter of the connecting portion 10 of the hub 6 generated at the end surface 14A are reduced. Since the component force F1 acting in the direction to be canceled out, the diameter of the coupling portion 10 of the hub 6 can be prevented from expanding. Thereby, the intensity | strength with respect to the rotational force T which acts between the shaft 5 and the hub 6 can be raised.

  Further, since the tooth base surface 14B of the tooth profile of the serration 9 is substantially perpendicular to the circumferential direction of the coupling portion 8 of the shaft 5, the width W of the base portion of the tooth profile can be sufficiently increased. Strength can be increased. In addition, since the tooth-side surface 14B is substantially perpendicular to the circumferential direction of the coupling portion 8 of the shaft 5, when the rotational force T acts, the surface 14B acts in the direction of reducing the diameter of the coupling portion 10 of the hub 6. However, since the plastic-flowed material on the hub 6 side hardly comes into contact with the tooth-side surface 14B, the strength of the meshing of the serration 9 is not affected. Further, by sufficiently increasing the radius R2 of the base portion of the surface 14B on the tooth base side, stress concentration can be prevented and the strength of the serration 9 can be increased.

  In the above embodiment, the case where the present invention is applied to the coupling between the shaft 5 and the hub 6 of the automatic transmission for automobiles is described. However, the present invention is not limited to this, and other rotational force is transmitted. The present invention can be similarly applied to coupling between rotating members.

It is the schematic which expands and shows the coupling | bond part of the shaft side and hub side by the plastic coupling structure of the rotating member which concerns on one Embodiment of this invention. It is the schematic which expands and further shows the coupling | bond part shown in FIG. It is explanatory drawing which shows the direction and magnitude | size of the force which acts on the coupling part shown in FIG. It is a longitudinal cross-sectional view of the shaft-hub assembly assembled using the plastic coupling structure shown in FIG. It is a longitudinal cross-sectional view which expands and shows the coupling | bond part of the shaft-hub assembly shown in FIG. It is a figure which shows the assembly process by the plastic coupling of the shaft and hub of the shaft-hub assembly shown in FIG. It is the schematic which expands and shows the coupling | bond part by the conventional plastic coupling.

Explanation of symbols

  5 Shaft (first rotating member), 6 Hub (second rotating member), 8 coupling portion, 9 serration, 10 coupling portion, 13 tooth surface, 14 tooth surface, 14A tooth end side surface, 14B tooth base side surface , Β tilt angle, γ tilt angle

Claims (3)

Serrations are formed on the outer circumferential surface of the coupling portion of the first rotating member, and the outer circumferential surface of the coupling portion of the first rotating member is formed on the inner circumferential surface of the coupling portion of the second rotating member having a hardness lower than that of the first member. The first rotating member and the second rotating member are joined by press-fitting and causing the serration tooth profile to bite into the inner peripheral surface and causing the material on the second member side to plastically flow between the tooth profiles. In the plastic coupling structure of the rotating member, one tooth surface of the tooth profile is formed such that an inclination angle with respect to a circumferential direction of the first rotating member is an acute angle, and the other tooth surface of the tooth profile is the end tooth side The inclination angle of the surface with respect to the circumferential direction of the first rotating member is an obtuse angle, and the surface on the tooth base side is formed substantially perpendicular to the circumferential direction of the first rotating member. The plastic coupling structure of the rotating member. The plastic coupling structure for a rotating member according to claim 1, wherein the inclination angle is in a range of 120 ° to 160 °. 3. The plastic coupling structure of a rotating member according to claim 1, wherein the first rotating member is a shaft, and the second rotating member is a hub. 4.

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