JP6792373B2 - How to fasten the hollow shaft and the ring-shaped part - Google Patents

Description

The present invention relates to a method of fastening a hollow shaft and a ring-shaped component.

Patent Document 1 describes a technique for fastening a gear and a shaft. Patent Document 2 describes a fitting structure of a flange hole for mounting a wheel and a bolt.

Japanese Unexamined Patent Publication No. 64-15511 Japanese Unexamined Patent Publication No. 8-226426

When the hollow shaft is press-fitted into the hole of the ring-shaped part having serrations on the inner peripheral wall, the hollow shaft may contract inward in the radial direction, and the hollow shaft and the ring-shaped part may not be firmly fastened.

An object of the present invention is to eliminate such inconvenience and to firmly fasten the hollow shaft and the ring-shaped component.

In order to achieve the above object, the method of fastening the hollow shaft and the ring-shaped component according to the present invention is described by inserting a jig having a cylindrical collet capable of expanding the diameter into the hollow portion of the hollow shaft. The diameter-expanding step of expanding the diameter of the collet to bring the outer peripheral wall of the collet into contact with the inner peripheral wall of the hollow shaft, and the ring-shaped component having a hardness larger than that of the hollow shaft and having serrations formed on the inner peripheral wall are described above. It includes a press-fitting step of press-fitting the hollow shaft into a hole of the ring-shaped component so as to be located radially outside the hollow shaft and radially outside the collet.

According to the present invention, the hollow shaft and the ring-shaped component can be firmly fastened.

It is explanatory drawing which shows the hollow shaft and the ring-shaped part. It is another explanatory view which shows the hollow shaft and the ring-shaped part. It is explanatory drawing which shows the contact part between the outer peripheral wall of a hollow shaft, and the inner peripheral wall of a ring-shaped component. It is explanatory drawing which shows a hollow shaft, a ring-shaped part, and a jig. It is explanatory drawing of the jig.

An embodiment of the present invention will be described below. However, the present invention is not limited to the following embodiments.

FIG. 1A shows the hollow shaft 1. A specific example of the hollow shaft 1 is an output shaft of a speed reducer unit. By using a hollow shaft, there are merits such as connecting to the driven shaft in the hollow portion, passing wiring through the hollow portion, and reducing the rotational inertia. The hollow shaft 1 has a hollow portion 11, an inner peripheral wall 12, and an outer peripheral wall 13.

FIG. 1B shows a ring-shaped component 2 provided with a hole 21. Specific examples of the ring-shaped component 2 include gear components such as spur gears, hypoid gears, face gears, bevel gears, and worm gears, and carriers of planetary gears. The inner peripheral wall 22 of the ring-shaped component 2 is formed with serrations, that is, serrations. This serration is also called a hole side serration. Then, FIG. 1C shows a state in which the hollow shaft 1 is press-fitted into the hole 21 of the ring-shaped component 2.

In order to firmly fasten the hollow shaft 1 and the ring-shaped component 2, the outer peripheral wall 13 of the hollow shaft 1 yields due to press fitting, and a part of the outer peripheral wall 13 is a serration groove portion of the inner peripheral wall 22 of the ring-shaped component 2. It needs to be plastically deformed so that it can enter. In order to undergo plastic deformation, the hardness of the material of the hollow shaft 1 is smaller than the hardness of the material of the ring-shaped part 2, and the contact portion between the outer peripheral wall 13 of the hollow shaft 1 and the inner peripheral wall 22 of the ring-shaped part 2 is formed. It is required that the generated compressive stress is larger than the yield stress of the hollow shaft 1.

The compressive stress can be expressed by the following equation.

However, as shown in FIG. 2, R is the outer radius (unit: mm) of the ring-shaped component 2.
r _a is the hollow shaft 1 inside radius (unit: mm) is.
r _b is the outer radius (unit: mm) of the hollow shaft 1.
E ₁ is the Young's modulus (unit: kgf / mm ² ) of the material constituting the hollow shaft 1.
E ₂ is the Young's modulus (unit: kgf / mm ² ) of the material constituting the ring-shaped component 2.
ν ₁ is the Poisson's ratio of the materials constituting the hollow shaft 1.
ν ₂ is the Poisson's ratio of the material constituting the ring-shaped component 2.
δ is the radius tightening allowance (unit: mm). That is, δ is a value obtained by subtracting the inner radius of the ring-shaped component 2 with respect to the tooth tip portion of the serration tooth from the outer radius r _b of the hollow shaft 1.
P is a compressive stress (unit: kgf / mm ² ) generated at the contact portion between the outer peripheral wall 13 of the hollow shaft 1 and the inner peripheral wall 22 of the ring-shaped component 2.

As shown in FIG. 3A, the hollow shaft 1 may contract inward in the radial direction during press fitting. In the figure, the arrow Y indicates the radial inward direction, and the reference numeral 12a indicates the inner peripheral wall after contraction. Reference numerals 22a and 22b indicate serration grooves and serration teeth on the inner peripheral wall 22, respectively. When the generated compressive stress P is less than the yield stress of the hollow shaft 1 due to the contraction of the hollow shaft 1, the material of the hollow shaft 1 does not plastically flow into the serration groove portion 22a. That is, serrations (also referred to as "shaft-side serrations") are not formed on the outer peripheral wall 13 of the hollow shaft 1. Incidentally, as the thickness of the difference or the hollow shaft 1 and outer radius r _b and an inner radius r _a of the hollow shaft 1 is small, compressive stress P becomes smaller.

Hereinafter, a case where the shaft-side serrations are not formed well and a case where the shaft-side serrations are formed well will be described. However, for metals that do not exhibit a yield phenomenon, such as stainless steel and aluminum alloys, the stress corresponding to the yield stress is defined as the proof stress, and the 0.2% proof stress is used instead of the yield stress. In the case of the embodiment of the present invention, since the hollow shaft 1 is made of stainless steel, 0.2% proof stress will be used instead of the yield stress.

[When axial serrations are not formed well]
Material: Hollow shaft 1 (SUS303 austenitic stainless steel)
-0.2% proof stress 250 MPa (25 kgf / mm ² )
-Young's modulus E ₁ = 190 GPa (19,000 kgf / mm ² )
・ Poisson's ratio ν ₁ = 0.3
Ring-shaped part 2 (SCM415 chrome molybdenum steel carburizing, quenching and tempering)
・ Yield stress 500MPa (50kgf / mm ² )
Young's modulus E ₂ = 210 GPa (21,000 kgf / mm ² )
・ Poisson's ratio ν ₂ = 0.3
Shape: Hollow shaft 1
· Outer diameter φ22 _(r b = 11mm)
- inside diameter φ17.6 _(r a = 8.8mm)
Ring-shaped part 2
・ Ring outer diameter φ30 (R = 15mm)
・ Radius tightening allowance: δ = 0.1 mm

The material of the ring-shaped component 2 has a higher hardness than the material of the hollow shaft 1.

In this case, according to the formula (1), P≈229 MPa. This compressive stress P is smaller than the 0.2% proof stress corresponding to the yield stress of the hollow shaft 1. Therefore, as shown in FIG. 3A, the axial serrations are not well formed.

[When axial serrations are formed well]
Material: Hollow shaft 1 (SUS303 austenitic stainless steel)
-0.2% proof stress 250 MPa (25 kgf / mm ² )
-Young's modulus E ₁ = 190 GPa (19,000 kgf / mm ² )
・ Poisson's ratio ν ₁ = 0.3
Ring-shaped part 2 (SCM415 chrome molybdenum steel carburizing, quenching and tempering)
・ Yield stress 500MPa (50kgf / mm ² )
Young's modulus E ₂ = 210 GPa (21,000 kgf / mm ² )
・ Poisson's ratio ν ₂ = 0.3
Shape: Hollow shaft 1
· Outer diameter φ22 _(r b = 11mm)
- an inner diameter of φ8 _(r a = 4mm)
Ring-shaped part 2
・ Ring outer diameter φ30 (R = 15mm)
・ Radius tightening allowance: δ = 0.1 mm

Compared to previously described "if serrations are not sufficiently formed", the inner diameter r _a of the hollow shaft 1 is small. That is, the wall thickness of the hollow shaft 1 is increased. In this case, when the compressive stress P is calculated from the equation (1), P≈403 MPa. This compressive stress P is larger than the 0.2% proof stress corresponding to the yield stress of the hollow shaft 1. Therefore, as shown in FIG. 3B, axial serrations are satisfactorily formed. That is, a part of the material of the hollow shaft 1 enters the serration groove portion 22a to form the shaft side serration tooth portion 13a.

Based on the formula (1) and FIG. 3, the inventor came up with the jig 3 for suppressing the inward contraction of the hollow shaft 1 in the radial direction at the time of press fitting as shown in FIGS. 4 and 5. ..

The jig 3 includes a jig main body 4, a collet 5 and a sleeve 6 which are cylindrical parts formed of a thin metal plate, and a nut 7.

The jig main body 4 includes a head 41 and a shaft 42. A male thread is cut on the tip portion 42a of the shaft portion 42. The jig main body 4 is further provided adjacent to the head 41 and the base end 42b of the shaft portion 42, and gradually has a diameter along the first axial direction D1 from the base end portion 42b toward the tip end portion 42a. It is provided with a tapered portion (first tapered portion) 43 that is smaller in size. The tapered portion 43 is provided with a protruding portion 44 formed so as to protrude outward in the radial direction.

The shaft portion 42 is inserted into the hollow portion of the collet 5. The collet 5 has an axial first end 51 on the head 41 side and an axial second end 52 on the tip 42a side.

The collet 5 has a first slit 53 formed so as to extend from the first axial end portion 51 in the first axial direction D1. The collet 5 further has a second slit 54 formed so as to extend from the second axial end 52 in the second axial D2 opposite to the first axial D1. The first slit 53 and the second slit 54 are alternately provided in the circumferential direction of the collet 5.

The shaft portion 42 is inserted into the cavity portion of the collet 5 so that one of the plurality of first slits 53 engages with the protrusion portion 44. Further, the normal inner diameter of the collet 5 is smaller than the maximum diameter of the tapered portion 43 and larger than the minimum diameter.

The shaft portion 42 is further inserted into the hollow portion of the sleeve 6. The sleeve 6 is located closer to the tip portion 42a than the collet 5. The sleeve 6 includes a tapered portion (second tapered portion) 61 formed at an axial end portion on the head 41 side. The tapered portion 61 is formed so that the outer diameter gradually decreases along the second axial direction D2. The normal inner diameter of the collet 5 is smaller than the maximum outer diameter of the tapered portion 61 and larger than the minimum outer diameter.

A nut 7 is screwed into the tip portion 42a. When the nut 7 is tightened with respect to the tip portion 42a, the sleeve 6 is pushed by the nut 7 and moves in the second axial direction D2. Then, the axial distance L between the tapered portion 43 of the jig main body portion 4 and the tapered portion 61 of the sleeve 6 is reduced. As a result, the tapered portion 43 is pushed into the hollow portion of the collet 5, and the size of the first slit 53 in the circumferential direction is increased. At the same time, the tapered portion 61 is pushed into the hollow portion of the collet 5 to increase the size of the second slit 54 in the circumferential direction. In this way, the diameter of the collet 5 is increased (that is, the diameter is increased).

The flow of fastening the hollow shaft 1 and the ring-shaped component 2 using the jig 3 as described above will be described below.
First, the jig 3 in which the collet 5 is not expanded in diameter is inserted into the hollow portion 11 of the hollow shaft 1.
Next, the diameter of the collet 5 is expanded by tightening the nut 7 with respect to the tip portion 42a, and the outer peripheral wall of the collet 5 is brought into contact with the inner peripheral wall 12 of the hollow shaft 1.
Subsequently, the hollow shaft 1 is press-fitted into the hole 21 of the ring-shaped component 2 so that the ring-shaped component 2 is located radially outside the hollow shaft 1 and radially outside the collet 5 (FIG. 4). ..

After that, the tightening of the nut 7 with respect to the tip portion 42a is loosened, and the expanded collet 5 is returned to the original size diameter. Then, the jig 3 is taken out from the hollow portion 11 of the hollow shaft 1.

As described above, the jig 3 is a shrinkage suppressor that suppresses the shrinkage of the hollow shaft 1 in the radial direction at the time of press fitting.

According to the above embodiment, the enlarged collet in contact with the inner peripheral wall of the hollow shaft suppresses the shrinkage of the hollow shaft inward in the radial direction at the time of press fitting. As a result, a large compressive stress can be generated at the contact portion between the outer peripheral wall of the hollow shaft and the inner peripheral wall of the ring-shaped component. As a result, the material of the hollow shaft yields, and the outer peripheral wall of the hollow shaft can be formed with shaft-side serrations that mesh with the serrations of the inner peripheral wall of the ring-shaped component. Therefore, the hollow shaft and the ring-shaped component can be firmly fastened.

Further, by engaging one of the plurality of first slits 53 with the protrusion 44, the collet 5 can be easily positioned with respect to the jig main body 4.

The nut 7 can be omitted by cutting a female thread on the inner peripheral wall of the sleeve 6. In this case, the sleeve 6 is screwed into the tip portion 42a. Then, when the sleeve 6 is tightened to the tip portion 42a, the tapered portion 43 and the tapered portion 61 are pushed into the hollow portion of the collet 5, and the diameter of the collet 5 is expanded. In this way, the same effect as when the nut 7 is provided can be obtained, and the number of parts of the jig 3 can be reduced.

Although the specific embodiments of the present invention have been described, the present invention is not limited to such embodiments, and various modifications based on the technical idea of the present invention are included in the concept of the present invention.

1 Hollow shaft 11 Hollow part 12 Inner peripheral wall 13 Outer wall

2 Ring-shaped part 21 Hole 22 Inner peripheral wall 22a Serration groove 22b Serration tooth

3 Jig

4 Jig body 41 Head 42 Shaft 42a Tip 43 Tapered 44 Projection


5 collet (cylindrical part)
51 Axial first end 52 Axial second end 53 First slit 54 Second slit


6 Sleeve (cylindrical part)
61 Tapered part

7 nut

Claims (7)

A diameter-expanding step of inserting a jig having a cylindrical collet capable of expanding the diameter into the hollow portion of the hollow shaft, expanding the diameter of the collet, and bringing the outer peripheral wall of the collet into contact with the inner peripheral wall of the hollow shaft. ,
The hollow shaft is ring-shaped so that the ring-shaped part having a hardness higher than that of the hollow shaft and having serrations formed on the inner peripheral wall is located on the radial outside of the hollow shaft and the radial outside of the collet. A method of fastening a hollow shaft to a ring-shaped part, including a press-fitting process of press-fitting into a hole of the part. The jig further includes a jig body portion having a shaft portion with a threaded shaft portion at the tip portion, a cylindrical sleeve, and a nut.
The shaft portion is inserted into the cavity portion of the collet and the cavity portion of the sleeve, and the nut is screwed into the tip portion.
When the nut is tightened to the tip portion, the first tapered portion provided on the jig main body portion and the second tapered portion provided on the sleeve are pushed into the collet to expand the diameter of the collet. The method for fastening a hollow shaft and a ring-shaped component according to claim 1. The first tapered portion is provided adjacent to the base end portion of the shaft portion, and is formed so that the diameter gradually decreases along the first axial direction from the base end portion to the tip end portion. Ori
The collet has a first slit formed so as to extend along the first axial direction and a second slit formed so as to extend along a second axial direction opposite to the first axial direction. It is provided with two slits, and the first slit and the second slit are alternately provided in the circumferential direction.
The second tapered portion is formed so that the outer diameter gradually decreases along the second axial direction.
When the nut is tightened with respect to the tip portion, the axial distance between the first tapered portion and the second tapered portion decreases, and the first tapered portion and the second tapered portion are pushed into the collet. The method for fastening a hollow shaft and a ring-shaped component according to claim 2, wherein the size of the first slit and the second slit in the circumferential direction is increased, and the diameter of the collet is increased. The method for fastening a hollow shaft and a ring-shaped component according to claim 3, wherein the first tapered portion is provided with a protrusion with which one of the first slits engages. The method for fastening a ring-shaped component to a hollow shaft according to any one of claims 1 to 4, wherein the hollow shaft is an output shaft of the speed reducer unit. The hollow shaft and ring-shaped component according to any one of claims 1 to 5, wherein the ring-shaped component is one of a spur gear, a hypoid gear, a face gear, a bevel gear, a worm gear, and a carrier of a planetary gear device. How to fasten. The jig further includes a jig main body portion having a shaft portion threaded at the tip portion, and a sleeve having a cylindrical shape and threaded on the inner peripheral wall.
The shaft portion is inserted into the cavity portion of the collet, and the sleeve is further screwed into the tip portion.
When the sleeve is tightened to the tip portion, the first tapered portion provided on the jig main body portion and the second tapered portion provided on the sleeve are pushed into the collet to expand the diameter of the collet. The method for fastening a hollow shaft and a ring-shaped component according to claim 1 .

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