JP2002206560A - Connection structure of shaft hole member onto shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure capable of preventing the fretting of a shaft hole and a shaft for long period with a simple and low cost structure. SOLUTION: An iron/steel input shaft 8 (shaft hole member) having a shaft hole 8A and an iron/steel motor shaft 10 fitted into the shaft hole 8A of the input shaft 8 are connected to each other through a power transmission part T formed of a keyways 8K and 10K and a key 30. A resin (non-ferrous) bush 40 is provided in the areas between the inner peripheral surface of the shaft hole 8A and the outer peripheral surface of the motor shaft 10 excluding the areas of the keyways 8K and 10K.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an iron-based shaft hole member having a shaft hole, such as a hollow shaft or a coupling of a speed reducer, which is fitted to the inner periphery of the shaft hole via a minute gap. The present invention relates to a structure in which an iron-based shaft is connected so as to be able to transmit power via a power transmission portion formed in a part in the circumferential direction.

[0002]

2. Description of the Related Art When a shaft is connected to a member having a shaft hole (shaft hole member) such as a hollow shaft or a coupling of a reduction gear so that power can be transmitted, an outer diameter slightly smaller than the inner diameter of the shaft hole is required. A method of inserting a shaft having the shaft into the shaft hole and engaging a key with a key groove formed on the inner periphery of the shaft hole and the outer periphery of the shaft has been widely adopted.

In addition, a projection is provided on the inner periphery of the shaft hole,
There is also widely known a structure in which a part of the outer periphery of a shaft is cut into a shape corresponding to the projecting portion, and power is transmitted by engagement of the projecting portion with the cut portion.

[0004] A so-called D in which a part of the shaft is cut so that its cross section becomes a letter D and the inner periphery of the shaft hole is protruded by that amount.
Cut connection and the like also correspond to this.

In this case, the projecting portion or the cut portion is generally formed in a shape continuous in the axial direction so as to be assembled and disassembled in the axial direction. For example, a threaded hole is formed in the shaft hole member in the radial direction. In some cases, a bolt is screwed into the screw hole and engaged with a screw portion on the outer periphery of the shaft.

A common feature of these coupling structures is that the shaft hole member and the shaft are fitted in a state where a minute gap is left on the inner periphery of the shaft hole, that is, "gap fitting". It is. The coupling structure using the “gap fit” has an advantage that the assembling and disassembling can be easily performed at room temperature without using a special tool, and power transmission is reliable.

[0007] However, while having such advantages, the coupling structure utilizing this clearance fitting generally uses an iron-based material (steel material) (in terms of strength) as a material for the shaft hole member and the shaft. There is a problem that fine movement wear called "fretting" due to a minute gap between the inner circumference and the outer circumference of the shaft easily occurs.

[0008] When fretting occurs, problems such as excessive wear of the shaft hole and the shaft, or the fact that the shaft is fixed to the shaft hole and cannot be disassembled occur.

Conventional techniques for avoiding such problems include, for example: 1) Inserting a shaft having an outer diameter slightly larger than the inner diameter of the shaft hole by press-fitting, shrink fitting, etc. 2) Coupling by a friction joint utilizing the wedge effect; 3) Coupling by applying a lubricant such as molybdenum disulfide to the contact surface; 4) Special bonding of Fe-Al type, phosphoric acid type, etc. Coating with coating or thermal spraying on the contact surface (JP-A-11-210)
756, etc.);

[0010]

However, the connection structure of eliminating the gap between the shaft hole and the shaft by the press-fitting, shrink-fitting, etc. of the above 1) is certainly an appropriate effect for preventing fretting. However, assembly and disassembly require a large number of man-hours, and it is often impossible to heat or press-fit with a large load due to its structure.

The coupling structure using the friction joint utilizing the wedge effect described in the above 2) requires accurate centering between the shaft hole member and the shaft, which inevitably results in high cost and requires a large space. I do.

In the connection structure of 3), in which the lubricant is applied to the contact surface, the effect of preventing the occurrence of fretting can be expected in the early stage of operation, but the effect cannot be maintained for a long time. It must be said that the structure is insufficient as a countermeasure. Further, a special structure may be required to prevent the leakage of the lubricating oil.

[0013] A number of proposals have been made for the bonding structure of 4) for coating a special coating or spraying the contact surface on the contact surface. Therefore, there is a problem that the effect cannot be maintained for a long time. Also, because it is a special processing,
The cost must be high.

[0014] As described above, although various techniques have been proposed as connection structures for preventing fretting in the related art, each of them has a problem or a problem.

The present invention has been made in view of such a conventional problem, and has a simple structure, low cost, easy assembly and disassembly including a power transmission unit, and It is an object of the present invention to provide a coupling structure between a shaft hole member and a shaft that can maintain the fretting prevention effect for a long time.

[0016]

According to the present invention, there is provided an iron-based shaft hole member having a shaft hole, and an iron-based shaft fitted into the shaft hole of the shaft hole member through a minute gap. In a coupling structure between a shaft hole member and a shaft that are coupled to each other via a power transmission portion formed in a part in a circumferential direction so as to be able to transmit power, the power is transmitted between an inner periphery of the shaft hole and an outer periphery of the shaft. The above problem has been solved by interposing a bush made of a non-ferrous material at least in a portion excluding a transmission portion and between an inner periphery of the shaft hole and an outer periphery of the shaft. is there.

The term "bush" is generally
"Cylindrical part to be fitted into the inner peripheral surface of shaft hole or outer peripheral surface of shaft"
It is used as a term to the effect. However, the "bush" in the present invention is "a component that can be interposed between the inner periphery of the shaft hole and the outer periphery of the shaft, and can exist and distribute as a single component by itself". Define.

Accordingly, as will be described later, a non-ferrous material such as a resin, a copper alloy, or an aluminum alloy is formed into a shape to be interposed in the inner periphery of the shaft hole or the outer periphery of the shaft from the beginning. In addition to the above, there is also included a sheet-shaped member that is wound around the inner periphery of the shaft hole or the outer periphery of the shaft. However, those that cannot exist and cannot be distributed as a single component, such as film formation, coating, thermal spraying, and vapor deposition, are not included.

As a specific material of the bush, a material whose elastic modulus is smaller than that of the shaft hole member and the shaft is preferable. Resins, copper-based alloys (including brass), aluminum-based alloys and the like are conceivable. In particular, it has been confirmed that the resin can be easily arranged at low cost and has a long life. Further, a sheet material used for a sliding bearing is commercially available, but it has been confirmed that the sheet material may be cut into an appropriate size and wound.

The interposed bush may be fixed to either the inner periphery of the shaft hole or the outer periphery of the shaft. If there is a suitable axial movement restricting means such as a step, the bush is particularly fixed. You don't have to.

[0021]

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

In this embodiment, the present invention is applied to a coupling portion for connecting a motor shaft of a motor (not shown) to an input shaft of a speed reducer.

In FIGS. 1 and 2, reference numeral 2 denotes a joint casing to which a motor (not shown) is connected, and reference numeral 4 denotes an input side casing of the speed reducer R. The joint casing 2 and the input side casing 4 are connected by bolts 6, and the input shaft (shaft hole member) 8 of the reduction gear extends to the inside of the annular portions 2A, 4A of the respective casings 2, 4. ing. A coupling portion C between the input shaft 8 and the motor shaft 10 (see FIG. 2, not shown in FIG. 1) is formed at the extended portion, that is, at the base end portion of the input shaft 8 of the speed reducer R. (Described later).

The reduction gear R itself is known and has no direct relation to the present invention, so that the description will be briefly omitted.

The speed reducer R is mounted on the outer periphery of the input shaft 8 so as to rotate integrally with the input shaft 8, and is mounted on the outer periphery of the eccentric body 12 via a bearing 14. External gear 16 rotatable eccentrically with respect to 10
And an internal gear 18 also serving as a casing in which the external gear 16 meshes internally. External teeth such as a trochoidal tooth shape and an arc tooth shape are provided on the outer periphery of the external gear 16, and internal teeth made of an external pin 18 </ b> A are provided on the internal periphery of the internal gear 18. The external gear 16 is provided with a plurality of inner pin holes 16 </ b> A, in which the inner pins 24 protruding from the flange portion 22 </ b> A of the output shaft 22 are loosely fitted. As a result, only the rotation component of the external gear 16 is transmitted to the output shaft 22 via the internal pin 24, and a predetermined reduction according to the number of teeth of the external gear 16 and the internal gear 18 is performed. Is realized.

The viewpoint is returned to the vicinity of the coupling portion C of the input shaft 8 again. The configuration of this portion will be described in detail with reference to FIGS.

The input shaft (shaft hole member) 8 is formed of an iron-based material, and its base end (motor side) is enlarged in diameter, and has an inner diameter slightly larger than the outer diameter of the motor shaft 10. Hole 8A
Are formed from the motor side. Keyway 8 in shaft hole 8A
K is formed in the axial direction.

On the other hand, the motor shaft 10 is also formed of an iron-based material, and the motor shaft 10 also has a keyway 10K formed in the axial direction. The key 30 is inserted into both key grooves 8K and 10K, and the power of the motor shaft 10 is transmitted to the input shaft 8 through the path of the key groove 10K of the motor shaft 10, the key 30, and the key groove 8K of the input shaft 8. . That is, in this embodiment, the motor shaft 1
The zero keyway 10K, the key 30, and the keyway 8K of the input shaft 8 constitute the power transmission unit T.

The power transmission portion T is formed only in a part in the circumferential direction. In most of the remaining portion, the outer periphery of the iron-based motor shaft 10 and the inner periphery of the shaft hole 8A of the iron-based input shaft 8 are formed. It is in such a form that it comes into contact with "gap fit". Therefore, fretting may occur in this state,
In this embodiment, a resin (non-ferrous) bush 40 as shown in FIGS. 2 and 3 is interposed between the inner periphery of the shaft hole 8A of the input shaft 8 and the outer periphery of the motor shaft 10. .

The entire bush 40 is formed in a substantially cylindrical shape, and portions corresponding to the key grooves 8K and 10K are cut in the axial direction. The outer diameter Db of the bush 40 is set slightly larger than the inner diameter dh of the shaft hole 8A (Db> dh). However, the key groove 8K of the shaft hole 8A and the bush 40 can be inserted into the shaft hole 8A with the outer diameter Db slightly reduced by utilizing the elasticity of the resin.
By releasing the contraction in a state where the phases of the cut portions 40A are matched with each other, the cut portions 40A can be easily inserted and fixed to the inner periphery of the shaft hole 8A.

The radial thickness W of the bush 40 is suppressed to 10% or less of the outer diameter Dm of the motor shaft 10 in order to avoid a decrease in the strength of the key 30 due to the intervention of the bush 40.

The inner diameter db of the bush 40 is slightly larger than the outer diameter Dm of the motor shaft (db> Dm).
It can be easily assembled and disassembled (gap fit).

In this embodiment, the axial length L of the bush 40 matches the axial length (full length) Lo of the outer peripheral surface of the shaft hole 8A (see FIG. 1).

Reference numerals 50 and 52 in the figure denote bolt holes, from which the embedded type bolts (not shown) are screwed in to move the key 30 in the axial direction and the bush 40.
Is used to regulate the axial movement of the

Since this embodiment has such a configuration, the transmission of power from the motor shaft 10 to the input shaft 8 is performed by the keyway 10K of the motor shaft 10, the key 3
0, in the path of the keyway 8K of the input shaft 8, all the operations are performed between iron-based materials. Therefore, there is no particular problem in strength.

On the other hand, since the bush 40 made of resin is interposed in a portion where fretting is likely to occur, the contact between the iron-based materials is cut off, and fretting is effectively prevented. This is understood to be related to the fact that the elastic modulus of the resin is much larger than the elastic modulus of the iron-based material.
Since fretting is prevented, excessive fine wear does not occur, and the bush 40 and the motor shaft 10 do not adhere to each other to make disassembly difficult.

The material of the bush 40 is a resin (in this embodiment), but is a "single member", and therefore, there is no occurrence of a state such as peeling. The effect of anti-ting is not reduced.

Further, the mounting of the bush 40 can be extremely easily performed by utilizing the elasticity of the resin, and the insertion of the motor shaft after the mounting of the bush can be easily performed (by fitting a gap).

Above all, the resin bush 40 can be manufactured or obtained at extremely low cost, and the conventional structure can be modified only slightly, so that it can be implemented with almost no increase in cost.

In the above embodiment, the material of the bush 40 is used as a material (mainly for cost and ease of procurement).
Although the resin is used, the material of the bush in the present invention does not necessarily need to be a resin, and it is essential that the material is not an iron-based material. That is, for example, a copper alloy such as brass or an aluminum alloy may be used.

Further, according to the test of the inventor, as shown by the imaginary line in FIG. 3, a sheet-shaped material Sh which is commercially available for use as a sliding bearing is cut into an appropriate size. It has been confirmed that a similar effect can be obtained by using the wrapping around the shaft side. Of course, the shaft hole and the shaft according to the present invention do not slide (relatively move) between the two.
Rather, fretting is likely to occur because of no sliding. However, the sheet material Sh for the sliding shaft has an extremely effective effect for preventing the fretting. Since the sheet material Sh for the sliding shaft can be obtained at any time (because it is commercially available), and can flexibly cope with various shaft diameters and shaft lengths, the present invention can be carried out extremely easily. It is a useful material in that it can be used.

In the above embodiment, the bush 4
Although the axial length Lb of 0 is made equal to the axial length (total length) Lo of the outer peripheral surface of the axial hole 8A, the axial length Lb does not necessarily extend over the entire axial direction between the inner periphery of the axial hole and the outer periphery of the shaft. No need to let
You may make it intervene in only one part. In addition, when it arrange | positions only in one part of an axial direction, it installs in the site | part (for example, vicinity of the edge part C1) to which micro vibration in a radial direction is easy to apply.

In the above-described embodiment, the bush 40 is provided on the entire surface except for the power transmitting portion T in the circumferential direction. However, the bush 40 may be provided on only a part of the circumferential direction.

Further, in the above embodiment, the input shaft 8
Transmission between the shaft and the motor shaft 10 is realized by engagement of the key grooves 8K and 10K with the key 30, but the power transmission structure between the shaft hole member and the shaft in the present invention is not limited to this configuration. Instead, for example, a D-cut connection structure or a structure in which pins or bolts are embedded from the radial direction as mentioned in the section of the prior art may be used. Each of these structures has a structure in which power is transmitted through a power transmission portion formed in a part in the circumferential direction, and fretting easily occurs in these structures as well. However, the fretting is generated by applying the present invention. Can be prevented.

In the above embodiment, the bush 40 is crimped to the inner peripheral surface of the shaft hole 8A by utilizing the elasticity of the bush 40.
Although the fixing is performed, the method of fixing the bush is not necessarily limited to this method. For example, the above-described configuration may be combined with an adhesive so as not to easily fall off,
When the movement of the bush in the axial direction can be restricted by the step portion or the stopper, it is not necessary to fix the bush. Further, the motor shaft may be fixed to the side of the motor shaft, and the motor shaft with the bush attached may be inserted into the shaft hole.

[0046]

According to the present invention, fretting generated between the inner periphery of the shaft hole and the outer periphery of the shaft can be prevented with a simple and low-cost structure. Can be maintained for a long time.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a reduction gear to which a coupling structure between a shaft hole member and a shaft according to the present invention is applied.

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

FIG. 3 is a perspective view showing a shape of a bush.

[Explanation of symbols]

 Reference numeral 8: Input shaft (shaft hole member) 8A: Shaft hole 8K: Key groove 10: Motor shaft 10A: Key groove 30: Key 40: Bush C: Coupling part T: Power transmission part

Claims (5)

[Claims] An iron-based shaft hole member having a shaft hole and an iron-based shaft fitted into the shaft hole of the shaft hole member with a small gap formed in a part in a circumferential direction. In the coupling structure of the shaft hole member and the shaft, which are coupled to each other so as to be able to transmit power via the power transmission unit, a portion excluding the power transmission unit between the inner periphery of the shaft hole and the outer periphery of the shaft. A bush made of a non-ferrous material is interposed at least in a part between the inner periphery of the shaft hole and the outer periphery of the shaft. 2. The shaft hole member and shaft according to claim 1, wherein the bush is interposed only in a part of the shaft direction between the inner periphery of the shaft hole and the outer periphery of the shaft. And connection structure. 3. The shaft hole member and the shaft according to claim 1, wherein the bush is made of a material whose elastic modulus is smaller than that of the shaft hole member and the shaft. Coupling structure. 4. The coupling structure between a shaft hole member and a shaft according to claim 1, wherein any one of a resin, a copper-based alloy, and an aluminum-based alloy is adopted as the bush. . 5. The coupling structure between a shaft hole member and a shaft according to claim 1, wherein a sheet material used for a sliding bearing is selected as the bush.