JP7085430B2 - Ball bearing assembly method - Google Patents

Description

The present invention relates to a method for assembling ball bearings to be incorporated in a wave speed reducer or the like.

As shown in FIG. 9, the wave speed reducer arranges an annular flex spline 2 having an external tooth 2a that meshes with the internal tooth 1a inside the annular circular spline 1 having the internal tooth 1a, and also flexes. When a wave generator 3 that bends the flex spline 2 in an elliptical shape is arranged inside the spline 2 in the radial direction, the circular spline 1 is fixed and the wave generator 3 is rotated, the flex spline is rotated with respect to one rotation of the wave generator 3. 2 is rotated by the difference in the number of teeth from the circular spline 1. The wave generator 3 is composed of a cam 4 having an elliptical cross section driven by rotation, and a ball bearing 10 incorporated between the outer circumference of the cam 4 and the inner circumference of the flex spline 2.

The ball bearing 10 used in this wave speed reducer is incorporated in a state in which the outer ring 11 and the inner ring 12 are respectively deformed into an elliptical shape with the plurality of balls 13 sandwiched between them, and as the cam 4 and the inner ring 12 rotate, the ball bearing 10 is incorporated into the ball 13. Since the pressed outer ring 11 deforms so as to change the posture of the elliptical shape, it is more than the one used for general purposes in order to stabilize the deformation behavior of the outer ring 11 in use and extend the bearing life. Is also required to incorporate many balls 13.

On the other hand, in the assembly method applied to a normal deep groove ball bearing, as shown in FIG. 5, the inner ring 22 is eccentric in the radial direction relative to the outer ring 21, and is formed between the outer ring 21 and the inner ring 22. After arranging the ball 23 inserted in the crescent-shaped gap along the raceway groove of the outer ring 21, a load is applied to the outer ring 21 from the outside in the radial direction in the direction of the white arrow in the figure, and the outer ring 21 is formed by the solid line in the figure. It is elastically deformed in the direction of the arrow to move the inner ring 22 until it is concentric with the outer ring 21 (this method is sometimes called "clicking").

However, in this normal assembly method, when the balls 23 incorporated between the outer ring 21 and the inner ring 22 are arranged without a gap as shown in FIG. 6, the rows of the balls 23 are arranged in the bearing circumferential direction (hereinafter, simply "". When the angle occupied in the "circumferential direction" is α, the filling rate of the ball 23 represented by α / 360 × 100 is only 50 to 60%, and if an attempt is made to incorporate more than this, the inner ring 22 is inserted. When the outer ring 21 is moved to a position concentric with the outer ring 21, the outer ring 21 is deformed excessively, and the outer ring 21 is plastically deformed or cracked.

On the other hand, Patent Document 1 proposes using a jig 51 as shown in FIGS. 7 and 8 as a method of incorporating more balls into a ball bearing for a wave reducer. The jig 51 engages with an external member 52 having protrusions 52a that engage with both axially both sides of the inner peripheral surface of the outer ring 11 of the ball bearing 10 and axially both sides of the outer peripheral surface of the inner ring 12 of the ball bearing 10. It is composed of an internal member 53 having a protruding portion 53a and a bolt 54 that penetrates the inner beam 53b of the internal member 53 and is screwed to the outer beam 52b of the external member 52. The external member 52 and the internal member 53 are formed with passages 52c and 53c for guiding the ball 13 between the outer ring 11 and the inner ring 12 of the ball bearing 10, respectively.

Then, by tightening the bolt 54 to bring the inner beam 53b and the outer beam 52b closer to each other, the protruding portions 52a and 53a of the outer member 52 and the inner member 53 are separated from each other in the radial direction, and the outer ring 11 of the ball bearing 10 is separated from each other. The radial gap of the inner ring 12 is expanded in a part in the circumferential direction, and the ball 13 is inserted from the passages 52c and 53c of the external member 52 and the internal member 53 into the expanded portion of the radial gap.

Japanese Unexamined Patent Publication No. 2017-36747

In the ball bearing assembly method proposed in Patent Document 1, more balls can be incorporated than in the normal deep groove ball bearing assembly method, but the balls are inserted from only one outer ring during the assembly work. There is a drawback that it cannot be inserted between the inner ring and the jig, and the jig tends to be large and difficult to handle.

Therefore, it is an object of the present invention to provide a method for assembling ball bearings, which can increase the filling rate of balls incorporated between the outer ring and the inner ring and can efficiently incorporate the balls. ..

In order to solve the above problems, the present invention comprises an outer ring having a raceway groove formed on the inner peripheral surface, an inner ring arranged radially inside the outer ring and having a raceway groove formed on the outer peripheral surface, and the outer ring. In a method of assembling a ball bearing including a plurality of balls freely arranged between the raceway groove of the inner ring and the raceway groove of the inner ring, the plurality of balls are provided between the raceway groove of the outer ring and the raceway groove of the inner ring. When incorporating in between, first, only two of the plurality of balls are arranged as fulcrum balls at a predetermined angular distance between the raceway groove of the outer ring and the raceway groove of the inner ring. A load in a direction that narrows the radial gap between the outer ring and the inner ring is applied to the outer ring and the inner ring near the center position of the angular distance between the two fulcrum balls to elastically deform the outer ring and the inner ring, and the outer ring and the inner ring are subjected to elastic deformation. From the region where the radial gap between the outer ring and the inner ring is widened by elastic deformation, among the plurality of balls, balls other than the fulcrum ball are inserted between the raceway groove of the outer ring and the raceway groove of the inner ring. It was adopted. Here, the angle interval means the angle formed by two straight lines connecting two points on a plane including the bearing center and the bearing center (the same applies hereinafter).

According to the above configuration, two fulcrum balls are arranged at predetermined positions between the outer ring and the inner ring, and a load is applied to the outer ring and the inner ring between the two fulcrum balls to position the fulcrum balls. On the other hand, on the side opposite to the side where the load is applied in the circumferential direction, a region where the radial gap between the outer ring and the inner ring widens is formed, and the remaining balls can be incorporated between the outer ring and the inner ring from the two regions. Therefore, the filling rate of the balls can be increased as compared with the usual method of assembling a deep groove ball bearing, and the ball assembling work can be performed more efficiently than the method using a conventional jig.

Here, the angle distance between the two fulcrum balls is 70 to 90 °, and the position where the balls other than the fulcrum balls are inserted between the outer ring and the inner ring is from the position where the fulcrum balls are arranged. It is preferable that the positions are separated by 30 to 50 ° at an angular interval on the side opposite to the side to which the load is applied in the circumferential direction.

Further, after inserting a jig between the outer ring and the inner ring and arranging the fulcrum balls at positions sandwiching the jig from both sides in the circumferential direction, the outer ring and the inner ring elastically deform to hold the jig in the radial direction. If the load is applied to the outer ring and the inner ring until it is sandwiched between the two, it is necessary to install the remaining balls by using a jig having a predetermined thickness without controlling the load applied to the outer ring and the inner ring. Since it becomes possible to form a radial gap between the outer ring and the inner ring, the work efficiency can be further improved.

As the jig, a plate-shaped member having a convex arc surface along the inner peripheral surface of the outer ring and a concave arc surface along the outer peripheral surface of the inner ring is adopted, and the thickness dimension T thereof is D1 for the inner diameter of the outer ring. When the groove bottom diameter of the raceway groove of the outer ring is D2, the outer diameter of the inner ring is d1, and the groove bottom diameter of the raceway groove of the inner ring is d2.
T ≦ 3/2 (D1-d1)-(D2-d2)
It is good to say.

The ball bearing assembly method of the present invention can be particularly effectively applied to the ball bearing incorporated on the inner peripheral side of the wave speed reducer.

In the ball bearing assembly method of the present invention, as described above, two fulcrum balls are arranged between the outer ring and the inner ring at a predetermined angular distance, and a load is applied to the outer ring and the inner ring between the two fulcrum balls. By adding, a region where the radial gap between the outer ring and the inner ring widens is formed in two places in the circumferential direction, and the remaining balls can be inserted between the outer ring and the inner ring from the two places. The filling rate of the balls can be increased as compared with the method of assembling the deep groove ball bearings, and the ball assembling work can be performed more efficiently than the method using the conventional jig.

Front view illustrating the first procedure of the ball bearing assembly method of the embodiment Front view illustrating the procedure of the assembly method following FIG. Graph showing the analysis result of the radial gap between the outer ring and the inner ring in the state of FIG. Front view showing the filling rate of the balls of the ball bearings assembled by the assembly method of the embodiment. Front view explaining how to assemble a normal deep groove ball bearing Front view showing the filling rate of the balls of the deep groove ball bearings assembled by the assembly method of FIG. Longitudinal side view explaining how to assemble ball bearings for conventional wave reducers Front view of FIG. Front view explaining the configuration of the wave reducer

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The ball bearing assembly method of this embodiment is applied to the ball bearing 10 incorporated in the inner peripheral side of the wave speed reducer shown in FIG. 9 described above. Like a normal deep groove ball bearing, the ball bearing 10 has a raceway groove formed on the inner peripheral surface of the outer ring 11 and a raceway groove formed on the outer peripheral surface of the inner ring 12 arranged radially inside the outer ring 11. A plurality of balls 13 are rotatably arranged between the two, but the outer ring 11 and the inner ring 12 are formed to be thinner than a normal deep groove ball bearing because they are used in a state of being deformed into an elliptical shape. Has been done.

1 and 2 show a procedure for assembling the ball bearing 10. When assembling the ball bearing 10, first, as shown in FIG. 1, the inner ring 12 is eccentric in the radial direction relative to the outer ring 11, and is formed between the outer ring 11 and the inner ring 12. A jig 20 made of a plate-shaped member having a convex arc surface along the inner peripheral surface of the outer ring 11 and a concave arc surface along the outer peripheral surface of the inner ring 12 is inserted into the crescent-shaped gap, and the jig 20 is inserted in the circumferential direction. Balls 13 serving as fulcrum balls are arranged one by one along the raceway groove 11a of the outer ring 11 at positions sandwiched from both sides of the outer ring 11.

After that, as shown in FIG. 2, by moving the inner ring 12 until it becomes concentric with the outer ring 11, two fulcrum balls 13 are designated between the raceway groove 11a of the outer ring 11 and the raceway groove 12a of the inner ring 12. It will be arranged with an angle interval θ of.

Here, the thickness dimension T of the jig 20 is such that the inner diameter of the outer ring 11 is D1, the groove bottom diameter of the raceway groove 11a of the outer ring 11 is D2, the outer diameter of the inner ring 12 is d1, and the groove bottom diameter of the raceway groove 12a of the inner ring 12. When is d2,
T ≦ 3/2 (D1-d1)-(D2-d2) ... (1)
A slight radial gap is formed between the jig 20 and the outer ring 11 and the inner ring 12. Further, the circumferential length dimension of the jig 20 is set so that the angular distance θ between the two fulcrum balls 13 sandwiching the jig 20 is 70 to 90 °.

Next, as shown in FIG. 2, the direction in which the radial gap between the outer ring 11 and the inner ring 12 is narrowed in the outer ring 11 and the inner ring 12 near the center position of the angular distance θ between the two fulcrum balls 13 (white in the figure). A load in the direction of the arrow) is applied to elastically deform the outer ring 11 and the inner ring 12.

The change in the radial gap due to the elastic deformation of the outer ring 11 and the inner ring 12 at this time was obtained by analysis. The results of the analysis are shown in FIG. 3 (since the analysis was performed under symmetrical conditions on the left and right sides of FIG. 2, only half of the circumferential direction is shown). In FIG. 3, in the circumferential position with respect to the position (load position) where the load is applied to the outer ring 11 and the inner ring 12, the side where the load is applied from the position (near 40 °) where the fulcrum ball 13 is arranged. The radial gap between the outer ring 11 and the inner ring 12 is widest at a position 30 to 50 ° apart (near 70 to 90 °, near region A in FIG. 2) on the opposite side at an angular interval.

Therefore, as shown in FIG. 2, an appropriate load is applied to the outer ring 11 and the inner ring 12, and the radial gap between the outer ring 11 and the inner ring 12 becomes larger than the diameter of the ball 13 in the vicinity of the two regions A in the circumferential direction. In this state, balls 13 other than the fulcrum balls 13 may be inserted between the raceway grooves 11a of the outer ring 11 and the raceway grooves 12a of the inner ring 12 from these two regions A.

Further, from FIG. 3, the amount of change in the gap in the circumferential position near 70 to 90 ° changes according to the magnitude of the load applied to the outer ring 11 and the inner ring 12, but the load position (0 ° position) does not depend on the load level. It can be seen that the magnitude of the change in the gap is about 1/2. Therefore, from this analysis result, the amount of change in the gap at the load position when the radial gap between the outer ring 11 and the inner ring 12 becomes larger than the diameter of the ball 13 near the region A in FIG. 2 is estimated, and the amount of change in the gap is estimated accordingly. When the thickness dimension T of the tool 20 is set within the range of the above equation (1) and the outer ring 11 and the inner ring 12 are elastically deformed, a load is applied until the jig 20 is sandwiched in the radial direction by the elastic deformation. By doing so, it is possible to easily realize a state in which the remaining balls 13 can be inserted without managing the load, and the work efficiency can be improved.

In the ball bearing 10 assembled by the above assembly method, as shown in FIG. 4, the filling rate (α / 360 × 100) of the ball 13 reaches about 80% and is incorporated in the inner peripheral side of the wave reducer. It is suitable for.

As described above, in the method of assembling the ball bearings, first, two fulcrum balls 13 are arranged between the outer ring 11 and the inner ring 12 at a predetermined angle interval θ, and then the two fulcrum balls 13 are assembled. By applying a load in the direction of narrowing the radial gap between the outer ring 11 and the inner ring 12 near the center position of the angular distance θ, a region A in which the radial gap between the outer ring 11 and the inner ring 12 widens is formed at two points in the circumferential direction. Then, the remaining balls 13 from the two regions A are inserted between the outer ring 11 and the inner ring 12, and the filling rate of the balls 13 is increased as compared with the usual method of assembling a deep groove ball bearing. Can be done.

Further, as compared with the method using the conventional jig 51 shown in FIGS. 7 and 8, there are many places where the ball 13 is inserted between the outer ring 11 and the inner ring 12, and the large jig 51 is difficult to handle. Since it is not necessary to operate the ball 13, the ball 13 can be efficiently incorporated.

Further, by appropriately setting the thickness dimension T of the jig 20 to be inserted between the outer ring 11 and the inner ring 12, when a load is applied until the outer ring 11 and the inner ring 12 sandwich the jig 20 in the radial direction. Since the radial gap between the outer ring 11 and the inner ring 12 required for incorporating the ball 13 other than the fulcrum ball 13 can be formed, it is not necessary to manage the load, and the work efficiency can be improved in this respect as well. ..

The jig of the present invention is not limited to the one of the above-described embodiment, and has a circumferential length corresponding to a predetermined angular distance between the two fulcrum balls, and is inserted into the radial gap between the outer ring and the inner ring. Anything can be used as long as it can regulate the reduction of the radial gap.

Further, the present invention can be applied particularly effectively to a ball bearing incorporated in the inner peripheral side of a wave speed reducer as in the embodiment, but as a method for assembling a ball bearing that is required to increase the filling rate of balls. Can be widely used.

1 Circular spline 2 Flex spline 3 Wave generator 4 Cam 10 Ball bearing 11 Outer ring 11a Track groove 12 Inner ring 12a Track groove 13 Ball 20 Jig

Claims (5)

An outer ring having a raceway groove formed on the inner peripheral surface, an inner ring arranged radially inside the outer ring and having a raceway groove formed on the outer peripheral surface, and rolling between the raceway groove of the outer ring and the raceway groove of the inner ring. In the method of assembling a ball bearing having a plurality of balls arranged freely.
When incorporating the plurality of balls between the raceway groove of the outer ring and the raceway groove of the inner ring,
First, only two of the plurality of balls are arranged as fulcrum balls at a predetermined angle between the raceway groove of the outer ring and the raceway groove of the inner ring, and then the outer ring and the inner ring are subjected to. Near the center position of the angular distance between the two fulcrum balls, a load in a direction that narrows the radial gap between the outer ring and the inner ring is applied to elastically deform the outer ring and the inner ring, and the outer ring and the inner ring are elastically deformed by the elastic deformation of the outer ring and the inner ring. Among the plurality of balls, balls other than the fulcrum balls are inserted between the raceway grooves of the outer ring and the raceway grooves of the inner ring from the region where the radial gap is widened. How to assemble ball bearings. The method for assembling a ball bearing according to claim 1, wherein the angle distance between the balls for both fulcrums is 70 to 90 °. The position where the balls other than the fulcrum balls are inserted between the outer ring and the inner ring is set at an angular distance from the position where the fulcrum balls are arranged to the side opposite to the side to which the load is applied in the circumferential direction. The method for assembling a ball bearing according to claim 1 or 2, wherein the ball bearings are located at a distance of 30 to 50 °. After inserting a jig between the outer ring and the inner ring and arranging the fulcrum ball at a position where the jig is sandwiched from both sides in the circumferential direction, the outer ring and the inner ring sandwich the jig in the radial direction due to elastic deformation. The method for assembling a ball bearing according to any one of claims 1 to 3, wherein a load is applied to the outer ring and the inner ring until the bearing is attached. The method for assembling a ball bearing according to any one of claims 1 to 4 , wherein the ball bearing is incorporated on the inner peripheral side of the wave speed reducer.

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