JP3926133B2 - Ball spline and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ball spline that linearly moves or transmits torque with respect to a spline shaft, and more particularly to a ball spline with improved manufacturing efficiency.
[0002]
[Prior art]
Ball splines are widely used in various machine tools, industrial machines, and robots to linearly guide members and transmit torque. The ball spline has an outer cylinder, a ball holder (retainer) inserted in the outer cylinder, and a plurality of balls that are circulated between the outer cylinder and a ball exposure hole of the ball holder. A load ball rolling groove is provided between the exposed ball and the ball rolling groove of the spline shaft, and a return groove connected to the load ball rolling groove is connected to the outer periphery of the ball cage. The outer cylinder and the ball cage inserted into the outer cylinder are indispensable as main components.
[0003]
[Problems to be solved by the invention]
By the way, the overall length of the ball spline is generally selected according to the size of the member to be guided. Therefore, as a manufacturer, in order to meet the demand, a plurality of types of ball splines are manufactured in advance. I had to prepare. In this case, since the outer cylinder is usually made of metal, there was no particular difficulty in manufacturing a plurality of types of outer cylinders. However, since the ball cage is usually manufactured by injection molding of plastic, a separate mold must be prepared for each different total length, and there is a problem that requires a great manufacturing cost.
[0004]
On the other hand, when an order for a non-standard full length ball spline is received from a consumer, the metal outer cylinder can be immediately manufactured as described above. However, with regard to the ball cage, it is necessary to manufacture a mold first, and further, it is necessary to test a product molded by the manufactured mold and finely adjust the mold based on the test. There was a problem that required delivery.
[0005]
From the above situation, we have manufactured an outer cylinder with a length according to demand for the time being, and the ball cage is selected from the ready-made products and combined with the closest one. When the outer cylinder is too long for the cage, there is a possibility that the moment load and the rated load are insufficient.
[0006]
[Means for Solving the Problems]
The present invention was created in view of the above problems of the prior art, and an object of the present invention is to provide a ball spline and a method for manufacturing the same that can efficiently manufacture ball splines having different full lengths. .
[0007]
That is, the ball spline of the present invention has an outer cylinder, a ball holder inserted in the outer cylinder, and a plurality of balls that are circulated between them. Provided is a load ball rolling groove that the ball exposed from the ball rolls between the spline shaft and a return groove connected to the load ball rolling groove on the outer periphery of the ball cage and connected to this. In a ball spline having a structure provided with a no-load ball rolling groove, a plastic ball cage divided into two in the axial direction is inserted into a metal outer cylinder.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The details of the ball spline and the manufacturing method thereof according to the present invention will be described below with reference to the accompanying drawings. 1 to 4 are views showing an example of the ball spline of the present invention. The basic structure of the ball spline on which the present invention is predicated is a conventionally known one in which a plastic ball cage 10 that accommodates a ball B is inserted into a metal outer cylinder 1. That is, the cylindrical ball cage 10 having a plurality of endless circuit-like ball circulation paths R including the pole exposure holes 11 opened in the shape of a long hole in the axial direction is accommodated, and a plurality of balls B are accommodated in the ball circulation path. A structure is adopted in which the ball moves infinitely in the ball circulation path covered by the inner peripheral wall surface of the outer cylinder by being inserted and fixed in the outer cylinder 1 in the state.
[0009]
In this case, a plurality of raised portions 3 protruding in the shape of a bank in the axial direction are provided on the inner periphery of the outer cylinder 1 at intervals in the circumferential direction, and the ball rolling groove of the spline shaft S is provided at the tip thereof. A load ball rolling groove 2 to which the ball B should roll is provided between S1 and S1. On the other hand, the ball cage 10 is provided with a pole exposure hole 11 opened in the shape of a long hole in the axial direction at a position corresponding to the load ball rolling groove 2 when inserted into the outer cylinder 1. The ball B rolling between the dynamic groove S1 and the loaded ball rolling groove 2 of the outer cylinder is exposed from here in a state in which it is prevented from falling off. In addition, an unloaded ball rolling groove 13 is provided on the outer periphery of the ball cage 10 in parallel with the pole exposing hole 11, and both ends of the unloaded ball rolling groove and both ends of the ball exposing hole are connected in an arc shape. By connecting with the grooves 12 and 12, an endless circuit-like ball circulation path R is formed. A plurality of pairs of raised portions 15, 15 projecting like a bank in the axial direction are provided on the outer periphery of the ball cage 10 at intervals in the circumferential direction, and the ball cage is inserted into the outer cylinder 1. At this time, the both sides of the above-described raised portion 3 of the outer cylinder are clamped by the raised portions 15 and 15 on the ball cage side, thereby positioning and rotating the both.
[0010]
The ball cage 10 described above is inserted and fixed in the outer cylinder 1 in a state of being divided into two in the axial direction, thereby constituting the ball spline of the present invention, which is a characteristic part of the present invention. Reference numerals 21 and 21 in the figure are ring-shaped end members that seal the ball cage 10 inserted in this case in the axial direction and are engraved on the inner periphery of both ends of the outer cylinder 1. It is contact | abutted toward the both ends of a ball holder with the stop rings 20 and 20 inserted by the annular groove 4. FIG.
[0011]
Next, an embodiment of a method for combining the outer cylinder 1 and the ball cage 10 that is inserted by being divided into two will be described.
[0012]
(Example 1)
The right and left portions of the ball cage 10 are appropriately cut out and combined to correspond to the entire length of the outer cylinder 1.
[0013]
Although this method can cope with the case where the overall length of the outer cylinder 1 is out of specification, a material loss occurs when the left and right portions of the ball cage 10 are cut out at the intermediate portion.
[0014]
(Example 2)
The ball holder 10 is divided into two parts in the left and right direction in the axial direction and cut, and a ball holder having a required length is obtained by combining the divided pieces.
[0015]
This method is an efficient method because no material loss occurs. For example, as shown in FIGS. 7 and 8, one ball holder 10 is divided into two by setting the left divided piece 10A longer than the right divided piece 10B (see FIG. 7), and the other ball holder 10 Divides the left divided piece 10C into two by setting the left divided piece 10C short (see FIG. 8). By doing so, in addition to the ball cage 10 shown in FIG. 7 or FIG. 8 by the combination of the short divided pieces 10B and the long divided pieces 10A (or 10C and 10D), the long divided pieces 10A and It is possible to obtain the ball cage 10 shown in FIGS. 1 to 3 by combining the long divided pieces 10D and the ball holder 10 shown in FIG. 6 by combining the short divided pieces 10C and the short divided pieces 10B. Therefore, by adjusting the length of each divided piece to be cut, it is possible to obtain a ball holder having a stepless length up to a ball holder having a full length nearly twice that of the ball holder before cutting. . The manufacturing method according to claim 2 is based on this method.
[0016]
Example 3
Prepare a plurality of ball holders that have been cut in advance by dividing them into two parts that are uneven in length on the left and right sides, and multiple types of metal outer cylinders corresponding to the total length of the ball holders when the divided pieces are combined. A plurality of types of ball splines having a full length are obtained by combining these.
[0017]
In this method, the division dimension of the ball cage 10 in the method of the second embodiment is standardized, and the dimension of the outer cylinder 1 corresponding thereto is standardized. A plurality of types of full-length ball splines can be rapidly manufactured. The manufacturing method according to claim 3 is based on this method.
[0018]
【The invention's effect】
According to the present invention having the above-described configuration, if a ball cage having one type of length is prepared, a ball cage having a stepless length up to a ball cage having a full length nearly twice that of the ball cage can be obtained. Therefore, ball splines of various lengths can be manufactured at low cost, and the delivery time can be shortened.
[0019]
In addition, the ball that rolls under load rolls between the ball rolling groove of the spline shaft and the load ball rolling groove of the outer cylinder. Since no load is applied to the ball cage, the ball cage is divided. The adverse effects of the combination will not occur.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a ball spline according to the present invention.
FIG. 2 is a perspective view showing the outer cylinder with imaginary lines.
FIG. 3 is a partially cutaway side view.
FIG. 4 is a front view of the above.
FIG. 5 is a partially cutaway side view with the ball removed.
FIG. 6 is a partially cutaway side view of a different embodiment.
FIG. 7 is a side view of the ball cage.
FIG. 8 is a side view of the ball cage.
[Explanation of symbols]
1 Outer cylinder 2 Loaded ball rolling groove 10 Ball cage 11 Ball exposure hole 12 Return groove 13 Unloaded ball rolling groove B Ball S Spline shaft S1 Ball rolling groove

Claims (2)

  The outer cylinder, a ball holder inserted in the outer cylinder, and a plurality of balls circulated between the outer cylinder and the ball are exposed from the ball exposure holes of the ball holder on the inner circumference of the outer cylinder. A load ball rolling groove to be rolled with the ball rolling groove is provided, a return groove connected to the loaded ball rolling groove on the outer periphery of the ball cage, and a no-load ball rolling groove connected to the return groove In manufacturing a ball spline having a structure provided with a plastic ball cage, the plastic ball cage is divided into two parts in the axial direction in the left and right direction and cut in the axial direction. A method of manufacturing a ball spline, comprising: obtaining a ball cage and inserting the ball cage into a metal outer cylinder.   Prepare a plurality of plastic ball cages that have been cut in advance by dividing them into left and right unequal lengths, and multiple types of full length metal products corresponding to the total length of the ball cages when the divided pieces are combined. The ball spline manufacturing method according to claim 1, wherein a plurality of types of ball splines are obtained by combining these outer cylinders.

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