JP3202148B2 - Bossed shaft and boss mounting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a bossed shaft,
The present invention relates to a boss mounting method for mounting a shaft on a boss by press fitting.

[0002]

2. Description of the Related Art Conventionally, when manufacturing a rotor for a rotating electric machine such as a servomotor or a stepping motor, a boss of a cylindrical metal body to which a rotor magnetic pole is fixed is attached to a rotating shaft as shown in FIG. This will be described below. In FIG. 2, 1 'is a shaft, 2' is a boss, 3'a and 3 '
b is a magnetic pole made of a permanent magnet fixed to the boss 2 '.
The illustrated arrows indicate the direction of press-fitting of the shaft 1 ', and for convenience of explanation, the right side of the axis X of the shaft indicates the state at the time of starting press-fitting of the boss 2' and the magnetic pole 3 'into the shaft 1'. The boss 2 ′ and the magnetic pole 3 ′ are on the left side of the axis X.
Shows a state when the shaft 1 'is press-fitted (press-fitting is completed). 1'a of the shaft 1 'is a first press-fit portion, 1'b is a second press-fit portion, and 1'c and 1'd are relief portions each having a diameter slightly smaller than each press-fit portion, that is, a small-diameter relief portion. 1′e has a slightly larger diameter, that is, a slightly larger diameter body portion than the press-fit portion 1b, 1′f and 1′g are bearing fitting portions, 1′h and 1′i are oil seal portions, 1'j
Denotes a sensor mounting portion such as a rotating disk. The shaft 1 'is made of a single bar, and the above-mentioned portions having different diameters are formed by machining using a machine tool such as an NC lathe. The first and second press-fitting portions 1'a, 1'b
Has been ground to reduce the press-in resistance.

The inner diameter of the boss 2 'is the first diameter of the shaft 1'.
And the outer diameter of the second press-fitting portions 1'a and 1'b is slightly smaller. In the boss 2 ′, the inner corner 2 ′ a1 of the end face of the press-fitted portion 2 ′ a with which the tip of the first press-fit portion 1 ′ abuts at the start of press-fitting of the shaft 1 ′ is obliquely chamfered ( That is, it is tapered) to facilitate the press-fitting of the first and second press-fitting portions 1'a into the press-fitted portions 2'a. In the press-fitting operation of the shaft 1 'into the boss 2', the shaft 1 'is normally pressed into the boss 2' by applying a strong pressing force in the direction of the arrow while the boss 2 'is held by the holder. In the process of this press-fitting, the first press-fitting portion 1'a becomes the boss 2 '
Is pressed in the length direction of the boss 2 'while scraping the inner peripheral wall surface of the boss 2'. D 'shown is a press-fit distance, and in this example, D'
Has a length of 41 mm corresponding to the entire length of the inner wall surface of the boss 2 '.

[0004]

As in the prior art, when the press-fitting distance becomes long, the first press-fitting portion 1'a of the shaft 1 'enters the process of shaving the inner wall surface of the boss 2' by a strong pressing force. In some cases, the inner wall surface of the boss 2 ′ may be cut off or deformed, and the shaft 1 ′ may not move, making it impossible to press-fit. Further, if the shaving method is different, even if the press-fitting is completed, the axis X of the shaft 1 'and the center line of the boss 2' do not match, that is, an axis shift occurs. When such an axis shift occurs, the balance of the rotor is lost and it becomes impossible to obtain a good balanced rotation.

[0005] The problems of the conventional boss mounting method described above can be summarized as follows: it is difficult to press-fit, and even if press-fitted, the shaft and the boss tend to be misaligned.

SUMMARY OF THE INVENTION An object of the present invention is to provide a boss-mounted shaft and a method of mounting a boss, which can be easily press-fitted and do not cause axial misalignment between the press-fit shaft and the boss.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to improve a bossed shaft in which the shaft is mounted on a cylindrical boss by press fitting. And in this invention, a 1st and 2nd press-fitting part is formed in a press-fitting direction (one direction of the axial direction of a shaft) in a shaft at intervals. Further, first and second press-fitted portions into which the first and second press-fitted portions are press-fitted are formed on the inner surface of the boss at intervals in the press-fitting direction. Then, the second press-fitted portion is formed so as to allow passage of the first press-fitted portion. Further, the first and second press-fitting portions and the first and second press-fitting portions are formed such that the first and second press-fitting portions are simultaneously pressed into the first and second press-fitting portions. The shapes of the press-fitted portion and the press-fitted portion are arbitrary, and ridges (caulking portions) may be formed on both press-fitted surfaces.

More specifically, the outer diameter of the first press-fit portion and the inner diameter of the first press-fit portion located on the front side in the press-fit direction are respectively located on the rear side in the press-fit direction. The outer diameter of the second press-fit portion and the inner diameter of the second press-fit portion are set smaller. The distance between the front end of the first press-fit portion in the press-fit direction and the front end of the second press-fit portion in the press-fit direction and the rear end of the first press-fit portion in the press-fit direction. And the distance between the second press-fitted portion and the rear end in the press-fitting direction is made equal.

In the above-mentioned bossed shaft, if the dimensions of the first and second press-fitting portions in the press-fitting direction are made equal, the start and end of press-fitting of both press-fitting portions become simultaneous, thereby facilitating the press-fitting operation.

Also, until the first press-fitted portion is press-fitted into the first press-fitted portion, the outer diameter of the first press-fitted portion is adjusted so that the first press-fitted portion does not scrape the inner surface of the boss. If the difference between the inner diameter of the second press-fitted portion and the inner diameter of the second press-fitted portion is determined, the press-fitting becomes easier.

In the method of mounting a boss according to the present invention, first and second press-fit portions are formed on the shaft at intervals in the press-fit direction, and the first and second press-fit portions are formed on the inner surface of the boss at intervals in the press-fit direction. First and second press-fitted portions into which the second press-fitted portions are press-fitted are formed. Then, the outer diameter of the first press-fit portion located on the front side in the press-fit direction and the inner diameter of the first press-fitted portion are respectively changed to the outer diameter of the second press-fit portion located on the rear side in the press-fit direction and It is smaller than the inner diameter of the second press-fitted portion. The distance between the front end of the first press-fit portion in the press-fit direction and the front end of the second press-fit portion in the press-fit direction, and the rear end of the first press-fit portion in the press-fit direction. The distance between the portion and the rear end of the second press-fitted portion in the press-fitting direction is made equal.
Then, the first and second shafts are fixed with the boss fixed.
Are simultaneously press-fitted into the first and second press-fitted portions.
As in the present invention, when the first and second press-fitted portions of the shaft are simultaneously pressed into the first and second press-fitted portions of the boss, the press-fitted portion and the press-fitted portion are separated at two places in the press-fitting direction or the axial direction. The press-fitting operation is started from a state where the press-fitting operation is started from the state where the shaft is engaged or contacted with the shaft. There is no risk of displacement.

In the above invention, the press-fitted portion and the press-fitted portion are engaged or brought into contact with each other at two places separated in the press-fitting direction or the axial direction, but the press-fitted portion and the press-fitted portion are press-fitted at one place. You may. In that case, a press-fit portion and a fitting portion are formed on the shaft at intervals in the press-fit direction. A press-fitted portion into which the press-fit portion is press-fitted and a fitted portion into which the fitting portion is fitted are formed on the inner surface of the boss at intervals in the press-fitting direction. Then, the press-fitted portion and the fitted portion, which are located on the rear side in the press-fitting direction, are formed so as to allow passage of the press-fitted portion and the fitting portion, which are located on the front side in the press-fitting direction. . Further, the press-fit portion and the fitting portion, and the press-fit portion and the fitted portion are formed such that at least a part of the fitting portion is fitted into the fitted portion when the press-fit portion is press-fitted into the press-fit portion. .

In this way, the press-fit portion and the press-fit portion are
Since the fitting portion and the fitted portion are fitted at the time of press-fitting, there is almost no axial deviation between the shaft and the boss. Further, there is an advantage that the press-fitting operation is facilitated because the number of press-fit locations is reduced. In order to restrict the movement of the shaft at the fitting portion, the fitting portion and the fitted portion may be joined with an adhesive.

[0014]

In the boss-mounted shaft and the boss mounting method according to the present invention, the first press-fitting portion of the shaft is kept until the leading end of the first press-fitting portion reaches the inlet of the first press-fitted portion of the boss.
The inner wall of the boss is not scraped off by the press-fitting portion, and the shaft can be smoothly inserted to a certain depth. When the front end (tip) of the first press-fit portion of the shaft reaches (engages or contacts) the rear end (entrance) of the first press-fitted portion of the boss, the second end of the shaft is formed at the same time. The front end (tip) of the press-fit portion reaches (engages or contacts) the rear end (entrance) of the second press-fit portion of the boss. That is,
In a state where the positional relationship between the shaft and the boss is concentrically positioned on both end sides in the press-fitting direction of the boss, the press-fitting of the first and second press-fitting portions into the first and second press-fitted portions simultaneously is performed. Will be
Since this press-fit distance is short, the press-fit portion of the shaft has a small amount of shaving the inner wall surface of the press-fit portion of the boss, and press-fitting is easy.
In addition, it is possible to effectively prevent the axial displacement between the press-fitted shaft and the boss.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a rotor for a rotating electric machine will be described with reference to FIG. In FIG. 1, reference numeral 1 denotes a rotor shaft, and reference numeral 2 denotes a cylindrical boss to which the rotor magnetic poles 3a and 3b are fixed. In the present embodiment, the shaft 1 is press-fitted into the boss 2 held by the jig in the press-fit direction indicated by the arrow. The boss 2 is formed of a metal that is the same or slightly softer than the shaft 1. Two press-fit portions are formed in the shaft 1 at intervals in the axial direction (press-fit direction), and a portion 1A on the front side in the press-fit direction is the first press-fit portion, and a portion 1B on the rear side in the press-fit direction is the first press-fit portion. 2 is a press-fitting portion. Reference numeral 1C denotes a relief portion having a slightly smaller outer diameter than the press-fit portions 1A and 1B. In the other parts of the shaft 1, the same parts as those in FIG. 2 are denoted by the same reference numerals except for the dashes.

In this embodiment, the outer diameter of the first press-fit portion 1A is smaller than the outer diameter of the second press-fit portion 1B (0.1 mm or more). In addition, both press-fitting parts 1A, 1B
Are made equal in length L1 and L2. On the other hand, on the inner surface of the boss 2, first and second press-fitted portions 2A, 2B into which the first and second press-fitted portions 1A, 1B are press-fitted are provided at intervals in the center line direction (press-fitting direction). Is formed. The rear end portions (press-fit start ports) 2A1 and 2B1 in the press-fit direction of the two press-fit portions 2A and 2B are tapered so that the insides of the end surfaces are chamfered. The inner diameter of the first press-fitted portion 2A is smaller than the inner diameter of the second press-fitted portion 2B (0.1 mm or more). Drawing d shows this diameter difference.

In this embodiment, the distance L3 between the front end of the first press-fitting portion 1A in the press-fitting direction and the front end of the second press-fitting portion 1B in the press-fitting direction, Press-fit part 2A
The distance L4 between the rear end of the second press-fitted portion 2B in the press-fit direction and the rear end of the second press-fitted portion 2B is equalized.

When the dimensional relationship of the main parts is set as described above, when the shaft 1 is press-fitted into the boss 2, the first press-fitting portion 1A of the shaft 1 firstly has a front end 1A1 in the press-fitting direction.
Until the first press-fit portion 2A of the boss 2 reaches the rear end 2A1 in the press-fit direction of the first press-fit portion 2A, the shaft presses the boss 2 smoothly without the first press-fit portion 1A shaving the inner peripheral surface of the boss 2. Penetrate. Then, the front end 1A1 of the first press-fitting portion 1A.
Reaches the rear end 2A1 of the first press-fitted portion 2A, and at the same time, the front end 1B1 in the press-fit direction of the second press-fitted portion 1B.
Reaches the rear end 2B1 in the press-fitting direction of the second press-fitted portion 2B.

Here, the tip 1A1 of each press-fitting portion 1A, 1B.
, 1B1 are the rear ends 2A1,.
By contact (engagement or contact) with 2B1, the press-fitting operation is started in a posture in which the center line of the boss 2 and the axis of the shaft 1 match. By this press-fitting operation, the first press-fit portion 1A is press-fitted into the first press-fitted portion 2A, and the second press-fit portion 1B is press-fitted into the second press-fitted portion 2B at the same time. D in the drawing is a press-fit distance. In this case, the press-fit distance D is equal to each press-fit portion 1A,
1B may be equal to the length dimensions L1 and L2, and in this embodiment, D = L1 = L2 = 6.5 mm.

As described above, in this embodiment, the fitting portion between the shaft 1 and the boss 2 by the press-fit portions 1A and 1B of the shaft 1 and the press-fit portions 2A and 2B of the boss 2 is formed in two steps. The good parallelism between the shaft and the boss at the time is ensured. That is, there is no axial displacement between the shaft and the boss. Further, since the press-fitting distance (D = L1 = L2 = 6.5 mm) is short, the press-fitting operation is easy. In the present embodiment, the press-fitting portions 1A,
Since the diameters of 1B are different, the directionality when the shaft is pressed into the boss is determined. Therefore, it is possible to prevent the shaft from being pressed in with the direction of the shaft reversed.

In this embodiment, the press-fitting is performed by fixing the boss to the jig and moving the shaft toward the boss. However, the press-fitting is performed by fixing the shaft to the jig and moving the boss. You may.

In the above embodiment, the press-fitting portion and the press-fitting portion have two press-fitting portions, but the press-fitting portion may have only one press-fitting portion. In this case, one of the press-fitting portions 1A and 1B in FIG. 1 is a fitting portion, and one of the first and second press-fitting portions 2A and 2B corresponding to the fitting portion is a fitting portion. Good. Also in this case, when the press-fitted portion is press-fitted into the press-fitted portion as in the above-described two-stage press-fitting, the fitting portion is fitted into the fitted portion at the same time, or when the press-fitting starts, the fitting portion is covered. What is necessary is just to make it fit in the fitting part partially. Even in this case, the press-fitting is completed substantially without any axial deviation between the shaft 1 and the boss 2.

[0023]

As described above, according to the bossed shaft of the present invention, the press-fitting operation is easy, and furthermore, it is possible to effectively prevent the occurrence of axial misalignment between the shaft and the boss.

Particularly, first and second press-fit portions are formed on the shaft at intervals in the press-fit direction, and the first and second press-fit portions are formed on the inner surface of the boss at an interval in the press-fit direction, respectively. The first and second press-fitted portions are formed, and the outer diameter of the first press-fitted portion and the inner diameter of the first press-fitted portion located on the front side in the press-fitting direction are respectively set on the rear side in the press-fitting direction. If the outer diameter of the second press-fitted portion and the inner diameter of the second press-fitted portion are set to be smaller than each other, the press-fit distance can be set to a short distance equal to the length of each press-fit portion in the press-fit direction. Thus, press-fitting can be easily performed.

The distance between the front end of the first press-fit portion in the press-fit direction and the front end of the second press-fit portion in the press-fit direction is determined by the press-fit direction of the first press-fit portion. The rear end of the
If the distance between the second press-fitted portion and the rear end in the press-fitting direction is equal to that of the second press-fitted portion, the press-fitting of the first press-fitted portion to the first press-fitted portion and the second press-fitted portion of the second press-fitted portion. Press-fitting into the press-fitting portion can be started and performed simultaneously with the center line of the shaft and the boss aligned. Thus, it is possible to effectively prevent the occurrence of axial misalignment between the shaft and the boss.

According to the boss mounting method of the present invention,
The boss can be press-fitted to the shaft with a short press-fitting distance (a distance during which the press-fitting is actually performed), and the axial displacement between the shaft and the boss can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is an explanatory view used to explain a structure and a manufacturing method of an embodiment of a bossed shaft of the present invention.

FIG. 2 is an explanatory view used to explain the structure and manufacturing method of an example of a conventional bossed shaft.

[Explanation of symbols]

 1, 1 'Shaft 1A First press-fit portion 1B Second press-fit portion 2, 2' Boss 2A First press-fit portion 2B Second press-fit portion 3a, 3b Magnetic pole D Press-fit distance

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02K 1/00-1/34 H02K 15/00-15/16

Claims (2)

(57) [Claims] 1. A bossed shaft comprising a cylindrical boss and a shaft press-fitted into the boss, wherein the shaft is formed with a press-fit portion and a fitting portion at intervals in a press-fit direction. A press-fitted portion into which the press-fit portion is press-fitted at an interval in the press-fitting direction and a fitted portion into which the fitting portion is fitted at an inner surface of the boss; parts and those located on the rear side of the press-fitting direction of the fitted portion has an inner diameter dimensioned to permit passage of those located on the front side of the press-fitting direction of the press-fitting portion and said fitting portion and, when the press-fit portion is press-fitted into the press-fit portion, at the same time
The fitting portion is fitted to the fitted portion or the fitting
As the mating part is partially fitted to the fitted part,
The press-fit portion and the fitting portion are spaced from each other in the press-fit direction.
And the press-fitted portion and the fitted portion are
A bossed shaft characterized in that it is formed at intervals in the entry direction . 2. A boss with shaft according to claim 1, wherein said fitting portion and fitted portion are joined by an adhesive.