JPH0331741A - Bearing rigidity measuring instrument for static pressure bearing - Google Patents

Abstract

PURPOSE:To omit labor such as the replacement of a weight to safely and continuously measure the bearing rigidity of a static pressure bearing against a load by providing a fixing member for fixing and supporting a static pressure bearing with a means for adding a continuously variable load to a shaft supported by the static pressure bearing and detecting the load. CONSTITUTION:The static pressure bearing 1 provided with porous materials 1a, 1b for projecting pressurized gas supplied from the external supports the shaft 1c with static pressure and is fixed and supported by a fixing block 2. At the time of measuring the rigidity of the bearing 1, a switching valve 20 is set up to the returning side and load to be applied to the shaft 1c is turned to zero by air cylinders 3, 13 to determine the origin of load displacement. Then the switch valve 20 is turned to the going side, the air cylinders 3, 13 are driven by compressed air fed from a switching pipe 24 and load to be applied to the shaft 1c is detected by load cells 4, 14. Thus, the load to be applied to the shaft 1c can be continuously variably measured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for measuring bearing stiffness of a hydrostatic bearing.

[Prior Art] Hydrostatic bearings require a certain level of bearing rigidity in order to rotate smoothly without seizing even when overloaded. Therefore, after assembly, bearing rigidity is measured to determine whether the quality is good or bad.

The conventional method for measuring bearing stiffness is shown in Figs. 5(a) and (b).
), the radial and axial hydrostatic bearings 1a and 1b are installed in blocks 2a and 2b aligned with the measurement direction, respectively, so that the measurement direction of the radial and axial bearing stiffness coincides with the direction of gravity. 3a and 3b are gradually increased, the amount of shaft displacement at each time is detected by the displacement meter 4, and the ratio of the shaft displacement to the load applied to the shaft is determined from the relation diagram between load and displacement as shown in figure 's4. The stiffness value is obtained.

[Problems to be Solved by the Invention] However, in such conventional examples, since weights are used in the loading method, there are the following problems.

(1) As shown in Figure 2, measurements can only be made with a fixed load, and a continuous relationship between load and displacement cannot be obtained.

(2) Since it is necessary to frequently replace the weight, which is time-consuming, it cannot be put into mass production.

(3) Since the rigidity differs depending on the size of the hydrostatic bearing, it is necessary to prepare a large number of weights for each size.

(4) If the weight exceeds 50 kgf, manual work is inefficient and dangerous.

(5)! Depending on where one is placed, the load will be uneven, and the relationship between load and displacement will vary.

(6) In detecting the amount of shaft displacement, the amount of compressive deformation of the hydrostatic bearing housing is included, so the apparent rigidity is detected to be low.

In view of the problems of the prior art, an object of the present invention is to
In a bearing stiffness measurement device for hydrostatic bearings, it is possible to safely measure the stiffness against continuous loads without having to change weights, etc., and it also eliminates errors due to deformation of the housing and variations due to uneven loads. The purpose is to make it possible to perform accurate measurements.

[Means for Solving the Problems] In order to achieve the above object, a bearing stiffness measuring device for a hydrostatic bearing according to the present invention includes a fixing member that fixedly supports a hydrostatic bearing, and a fixing member that is attached to the fixing member, and a device for measuring the bearing stiffness of a hydrostatic bearing. The apparatus includes means for continuously applying a variable load to the supported shaft and detecting the load, and means attached to the fixed member for detecting the amount of displacement of the shaft due to the load.

[Function] In this configuration, a load is applied to the shaft when measuring bearing rigidity, but this load can be changed continuously, and the load value and the amount of shaft displacement due to it are also continuously detected. Ru. Therefore, there is no need to replace various weights as in the prior art, and continuous load changes can be measured easily and safely. Furthermore, since the means for applying and detecting the load and the means for detecting the amount of shaft displacement are both attached to the fixed member, the obtained measured values do not include errors due to deformation of the housing or the like.

[Example] Below, an example of the present invention will be described based on FIGS. 1 and 2.

1 and 2 are a sectional view and an external view of a bearing stiffness measuring device according to an embodiment of the present invention. In these figures, reference numeral 1 denotes a static pressure bearing, which includes a cylindrical porous material 1a that blows out pressurized gas supplied from the outside, and an annular porous material 1b, which supports the shaft IC under static pressure. .

Fixed blocks 2 position and support the hydrostatic bearing 1 from both sides, each of which is fixed at three locations with bolts.

3 is an air cylinder for loading in the axial direction; 4 is a small load cell concentrically connected to the rod end of the air cylinder 3 to detect this load; 5 is a load cell 4
6 is a sliding bearing for smoothly and accurately sliding the piston 5, and 7 is positioned on the fixed block 2 to concentrically support the air cylinder 3 and the sliding bearing 6. A fixed housing, 8 a linear displacement meter for detecting displacement of the axial axis, 13 a radial load air cylinder,
14 is a small load cell, 15 is a piston, 16 is a sliding bearing, 17 is a housing that is positioned and fixed to the fixed block 2 to support the air cylinder 13 and the sliding bearing 16 concentrically, and 18 is a housing opposite to the load part (piston 15). A linear displacement meter for detecting radial displacement is fixed at the position, 10 is a digital amplifier for displacement, 11 is a cord connecting the displacement meter 8.18 and the amplifier 10, and 12 is a strain current detected by the load cell. A digital strain amplifier for converting and displaying the load; 9 is a cord connecting the load cells 4, 14 and the amplifier 12; 19 is positioned and fixed to the fixed block 2 opposite to the load side in order to position and support the displacement meter 8. It is a housing. The housing 19 has the same positioning and supporting method as the housing 7, and the load section and the displacement detection section can be changed between the left and right sides.

20 is a reciprocating switching valve for the air cylinder 3.13, 21 is a pressure gauge that indicates the pressure supplied to the air cylinder 3.13, and 22 is a precision gauge for precisely controlling the pressure supplied to the air cylinder 3.13. It is a pressure reducing valve. 23.24 are air pipes, which connect the outlet 25.2 of the switching valve 20.
6 are connected to the backward and forward sides of the air cylinder 3.13, respectively.

Next, the operation of this device will be explained.

First, the switching valve 20 is set to the backward movement side, appropriate pressure is supplied to the air cylinder 3 or 13, the load applied to the shaft IC is made zero, and the origin of the load displacement is determined. Next, the pressure reducing valve 22 is returned to zero, and the switching valve 20 is switched to the forward side. Then, the pressure is gradually increased by turning the pressure reducing valve 22. As a result, the compressed air supplied from the pipe 24 pushes up the piston rod of the air cylinder 3 or 13, and the load cell 4 or 14 attached to the tip of this piston rod pushes up the piston 5 or 15 from the rear. The piston 5 or 15 is guided by a plain bearing 6 or 16 and transmits the load to the shaft 1c. axis 1
The load applied to c is detected by the load cell 4 or 14, and the amount of minute displacement of the axis IC due to this load is detected by the displacement meter 8 or 18 attached to each measurement axis. However, the axial and radial measurements may be performed simultaneously or separately. The detected load value and displacement amount are determined by each amplifier 1.
2 and 10 and are read.

In addition, the relationship between load and displacement can be continuously recorded using the X-Y recorder 30, and the pressure can also be dividedly controlled using the pressure reducing valve 22 to plot the relationship between load and displacement at any given time. You can.

The apparatus of this embodiment has the following advantages.

■ Eliminates the need to frequently replace weights and improves safety.

■ Good position repeatability of load position and displacement detection position,
Improves reproducibility of measurements due to setup changes.

■Load can be applied either continuously or dividedly,
Also, the load range is wide, so it has great versatility.

■Can accommodate different sizes of hydrostatic bearings.

(2) As shown in FIG. 3, the amount of compressive deformation of the bearing housing, which was included in the conventional example, is canceled out with respect to the amount of shaft displacement, and the rigidity of the bearing portion can be accurately detected.

[Effects of the Invention] As explained above, according to the present invention, the load applied to the shaft is made to be a continuously variable load, which eliminates the hassle of replacing weights, etc., and allows for safe measurement of rigidity against continuous loads. can be done. Also, load loading and detection means,
In addition, since both the shaft displacement detection means are attached to the fixed member, accurate measurement can be performed without errors due to deformation of the housing or variations due to unbalanced loads.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a bearing stiffness measuring device according to an embodiment of the present invention, FIG. 2 is an external view of the device shown in FIG. 1, and FIG. 3 is a diagram showing load and shaft displacement in the device shown in FIG. 1. FIG. 4 is a graph showing the relationship between the conventional load and shaft displacement, and FIGS. 5 (a) and (b) show a bearing stiffness measuring device according to the conventional example. It is an external view. 1: Hydrostatic bearing, IC: Shaft, 2; Fixed block, 3.13
: Air cylinder, 4, 14: Load cell, 5, 15: Piston, 8.18: Straight displacement meter.

Claims (1)

[Claims] (1) a fixing member that fixedly supports the hydrostatic bearing; a means attached to the fixing member for continuously applying a variable load to the shaft supported by the hydrostatic bearing and detecting the load; 1. A bearing rigidity measuring device for a hydrostatic bearing, characterized in that the device is attached to a fixed member and includes means for detecting the amount of displacement of a shaft due to a load.