JPS6123490B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a measuring device for measuring friction torque of a ball bearing.

For precision ball bearings for instruments, etc., it is necessary to measure friction torque, which is one of the factors that determines the important characteristics of the bearing. When measuring the friction torque of a ball bearing, it is desirable to apply a composite load consisting of a thrust load and a radial load to the bearing, and to achieve the same test conditions as the normal usage of the ball bearing. However, it is difficult to achieve the same test conditions as in normal use.
Although the structure of the measuring device is complicated and it is quite difficult, especially when applying a thrust load to a ball bearing, the friction between the thrust load loading device and the ball bearing will affect the measurement result of the friction torque of the ball bearing. is added,
There remains the problem that accurate measurement is difficult, and it is also difficult to stably apply such a thrust load to the ball bearing.

Moreover, when the inner ring 3 of the ball bearing 1 is mounted on the rotating shaft 2 and rotated, as shown in FIG. If there is a shape error, the outer ring 4 will show the arrows a and b.
A slight movement is caused in the direction of . However, in actual use of the ball bearing, the outer ring 4 is fixed by the bearing box, so these movements a and b are absorbed by the deformation of the contact area between the raceway surfaces 5 and 6 and the balls 7, and this deformation has a large influence on the characteristics of friction torque. Therefore, in order to know the friction torque in the actual usage state of the ball bearing, it is necessary to measure it while holding down the motions a and b of the outer ring.

This invention was made in view of the above circumstances, and it is possible to measure the friction torque of a ball bearing under the same conditions as the actual usage of the ball bearing. While constraining the degree of freedom, the influence of friction between the ball bearing and the thrust load loading device can be reduced, and the thrust load can be stably applied to the ball bearing, and the structure is simple and inexpensive. The object of the present invention is to provide a friction torque measuring device.

Corresponding to this purpose, the ball bearing friction torque measuring device of the present invention has an inner ring of a ball bearing fixedly mounted on a rotating shaft, an outer ring fixedly mounted inside a bearing box, and a static pressure applied to the bearing box. A thrust load system that applies a thrust load in the thrust direction of the ball bearing via an air bearing, and a friction torque detection unit that acts on the bearing box by a winding member wound around the bearing box. The box is characterized in that it includes a radial load system that applies a radial load to the box, and that the motion of the ball bearing is restricted to one degree of freedom of rotation around the rotation axis.

The details of this invention will be explained below with reference to the drawings showing one embodiment.

2, 3, and 4, reference numeral 11 denotes a friction torque measuring device of the present invention, and a ball bearing 1
It measures the friction torque of The friction torque measuring device 11 attaches the inner ring 3 of the ball bearing 1 to the rotating shaft 2 and rotates it at a constant speed. Further, the outer ring 4 is fixed and held within the bearing box 12. In this way, the motion of the outer ring 4 of the ball bearing 1 is constrained to one degree of freedom in which only rotational and oscillating motion about the center of rotation is permitted. The friction torque measuring device 11 also includes a ball bearing 1.
a thrust load system 13 for applying a thrust load to the bearing housing 1 through the bearing housing 1;
2 and a radial load system 15 for applying a radial load to the ball bearing 1 via the torque detection system 14.
It is equipped with

The thrust load system 13 has a static pressure air bearing 16 positioned close to the bearing box 12, and blows air from a nozzle 17 disposed opposite the bearing box 12 to create a minute gap 18 between the bearing box 12 and the bearing box 12. Further, a predetermined thrust load is applied to the ball bearing 1 by an air cylinder 19 disposed on the same line as the rotating shaft 2 and the static air bearing 16. Note that the air pressure supplied to the hydrostatic air bearing 16 is adjusted so that the gap 18 between the bearing box 12 and the hydrostatic air bearing 16 is maintained even when a thrust load is applied. As shown in FIG. 4, this static pressure air bearing 16 has groups of nozzles 17 with minute diameters arranged at equal intervals around its periphery, thereby increasing its rigidity against tilting of the outer ring 4 of the ball bearing 1. . Alternatively, instead of the nozzle group 17, a porous material 22 may be used as shown in FIG.
Mutual interference with the blowing pressure between the fine holes in No. 3 is reduced, and its rigidity is further increased.

The radial load system 15 is connected to the torque detection system 14 by a belt 24 and applies a radial load to the outer ring 4 of the ball bearing 1 via the torque detection system 14 and the bearing box 12, but this force is transferred to the air cylinder 25. given by.

The contents of the torque detection system 14 are basically based on the
This is the same technology as described in Publication No. 1920 (title of invention: "Radial load type friction measuring device for bearings"). That is, as shown in FIG. 3, strain gauges 28a, 28b, 29a, 29b are bonded to elastic bodies 27a, 27b attached to a movable frame 26, a belt 31 is connected to the ends of the elastic bodies, and this belt 31 is wound around the bearing box 12. When the rotating shaft 2 is rotated in this state, the outer ring 4 of the ball bearing 1
generates a minute rotational movement corresponding to the magnitude of the friction torque of the ball bearing, and this movement is transferred to the strain gauges 28a, 28b, 29a, 29b bonded to the elastic body.
The friction torque is measured.

In the ball bearing friction torque measurement device configured as described above, a radial load is applied to the ball bearing 1 by the radial load system 15, and a thrust load is applied to the ball bearing 1 by the thrust load system 13. Therefore, by applying a composite load and measuring the friction torque using the torque detection system 14 in this state, the friction torque of the ball bearing 1 can be measured under the same test conditions as the actual usage state of the bearing. I can do it. Moreover, in the thrust load system, the static pressure air bearing 16 is used, and the frictional resistance between the outer ring 4 of the ball bearing 1 and the jetted air is extremely small, so the friction torque measurement results
The influence of friction caused by the thrust load system is extremely low. Furthermore, by restricting the movement of the outer ring 4 of the ball bearing 1 to one degree of freedom by the static air bearing 16 of the thrust load system 13, the measurement conditions can be brought closer to the actual usage conditions of the ball bearing. I can do it.

As is clear from the above description, according to the present invention, it is possible to measure the friction torque of a ball bearing under the same conditions as in actual use. Therefore, it is possible to obtain a friction torque measuring device which is less affected by friction, which can stably apply the thrust load to the bearing, and which has a simple structure and is inexpensive.

[Brief explanation of the drawing]

Fig. 1 is an explanatory front view showing the movement of the outer ring when a ball bearing is attached to a rotating shaft and rotated, Fig. 2 is a front view showing a friction torque measuring device according to an embodiment of the present invention, and Fig. 3 Figure 4a is a side view showing the torque detection system, Figure 4a is a front view showing the hydrostatic air bearing, and Figure 4
Figure b is a bb arrow view in Figure 4a, Figure 5a
is a front view showing another hydrostatic air bearing, and FIG. 5b
is a view taken along the line bb in FIG. 5a. DESCRIPTION OF SYMBOLS 1... Ball bearing, 2... Rotating shaft, 11... Friction torque measuring device, 13... Thrust load system, 14...
...Torque detection system, 15...Radial load, 16...
...static air bearing.

Claims (1)

[Claims] 1 Thrust in which the inner ring of a ball bearing is fixedly attached to a rotating shaft, the outer ring is fixedly attached to a bearing box, and a thrust load is applied to the bearing box in the thrust direction of the ball bearing via a hydrostatic air bearing. a radial load system that applies a radial load to the bearing box through a friction torque detection section that acts on the bearing box by a winding member wound around the bearing box; A friction torque measuring device for a ball bearing, characterized in that the motion of the bearing is restricted to one degree of freedom of rotation around the rotating shaft.