JP2009236571A - Apparatus and method for measuring rotational accuracy for bearings - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing rotational accuracy measuring apparatus and method, effectively measuring the plane-deflection accuracy of a bearing required for a turntable of a machine tool, in addition to deflection in radial directions of the bearings. <P>SOLUTION: The rotational bearing accuracy measuring apparatus 10 for measuring the rotational accuracy of a bearing 1 supporting the turntable is provided with: a reference sphere 21 arranged on the center axis of a rotator 15 supported by the bearing 1; and displacement meters 41 and 42 for measuring deflection in radial directions of the reference sphere 21. The displacement meters 41 and 42 measure a deflection in radial directions in at least two or more positions L1, L2, L3 having different distances in axial directions between the bearing 1 and the reference sphere 21. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a bearing rotation accuracy measuring apparatus and measurement method, and more specifically, to a bearing rotation accuracy measuring apparatus for measuring the rotation accuracy of a bearing used for a turning shaft such as a rotary table of a machine tool or a spindle turning unit. And a measuring method.

  Conventionally, rolling bearings such as ball bearings, roller bearings, taper roller bearings, etc. rotate due to shape errors and dimensional differences of rolling elements such as balls, rollers, taper rollers, etc., and shape errors of the inner and outer ring raceway surfaces. It is known that a minute displacement in the radial direction and the axial direction, which is called non-synchronous run-out (Non Repeatable Run-out = NRRO), which is not repeated every rotation occurs. In the case of a bearing incorporated in an indexing shaft or indexing table of a machine tool, such a small displacement greatly affects the performance. Therefore, it is important to improve the performance of various devices by measuring the rotational accuracy of the rolling bearing and dealing with the occurrence of the above-mentioned rotational asynchronous vibration in order to eliminate it.

For this purpose, various devices for measuring the rotational accuracy of the bearing have been devised (for example, see Patent Document 1). As shown in FIG. 11, the measuring apparatus 100 described in Patent Document 1 includes a jig main body 101 having a spherical seat 103 formed on the surface, and a spherical portion 114 that matches the spherical seat 103 on the back and a reference sphere 115 on the surface. And a spherical mounting base 102 provided with each of them. The spherical base 102 is mounted on the jig body 101 so that the spherical portion 114 can be displaced by being guided by the spherical seat 103 and can be fixed. The center point C2 of the true sphere is slightly displaced with respect to the center point C1 of the spherical surface portion / spherical seat, and the jig body 101 allows the true spherical mounting base 102 to be adjusted and displaced along the spherical seat 103. . Thus, the rotational accuracy is measured by measuring the radial displacement of the reference sphere 115 with a non-contact displacement sensor in a state where the measurement object is rotated.
Japanese Utility Model Publication No. 6-5075 (Fig. 1)

  By the way, the bearings used for turning shafts such as rotary tables and spindle turning units of machine tools have limitations in the length direction due to the structure of the machine tools used, and even when a plurality of bearings are used in combination. It is necessary to support the rotary table with a short span.

  On the other hand, the workpiece set on the rotary table is often processed at a position away from the bearing rather than near the bearing. Also in a turning shaft such as a spindle turning unit, the distance from the turning shaft bearing to the tool tip position is generally longer. For this reason, in bearings used for turning shafts such as rotary tables and spindle turning units of machine tools, not only radial runout but also runout that appears as surface runout on the table top surface (hereinafter referred to as “surface The “runout” is important for machining accuracy.

  However, since the measuring apparatus 100 described in Patent Document 1 measures only the radial runout, it is effective when measuring the spindle device of a machine tool and the bearing of the spindle device. When measuring a bearing used for a turning shaft such as a table or a spindle turning unit, there is a problem that the above-described surface runout cannot be captured. For this reason, even if the radial shake is measured in the vicinity of the bearing and the shake amount is small, the shake at a position away from the table upper surface is not always small when it is incorporated in the rotary table. Similarly, when incorporated in the spindle turning unit, the tool tip position does not always have a small deflection.

  Further, JIS B6336-3 defines an inspection method for measuring the surface runout of the upper surface of the table. As shown in FIG. 12, at least every 90 ° apart from the center of the rotating table T by a predetermined distance R. At four places, block gauges and dial gauges G are used to check table runout.

  In order to measure surface runout using this inspection method, a reference plate with a flatness near zero is manufactured, the reference plate is rotated with the target bearing, and the runout of the upper surface of the reference plate is measured. However, it is difficult and practically impossible to manufacture a reference plate having a flatness close to zero.

  The present invention has been made in view of the above circumstances, and its purpose is to provide bearing runout accuracy required for a turning shaft such as a rotary table of a machine tool or a spindle turning unit in addition to the radial runout of the bearing. It is an object of the present invention to provide a bearing rotation accuracy measuring device and a measuring method capable of effectively measuring the above.

The above object of the present invention is achieved by the following configurations.
(1) A bearing rotational accuracy measuring device for measuring rotational accuracy of a bearing,
A measurement reference body disposed on a central axis of a rotating body supported by the bearing;
Displacement measuring means for measuring a radial deflection of the measurement reference body;
With
The bearing measurement accuracy measuring apparatus according to claim 1, wherein the displacement measuring unit measures the radial runout at at least two positions where the axial distance between the bearing and the measurement reference body is different.
(2) The bearing rotation accuracy measuring device according to (1), wherein the measurement reference body is a reference sphere.
(3) The displacement measuring means is 90 degrees around the measurement reference body and in the circumferential direction of the rotating body at each of at least two positions where the axial distance between the bearing and the measurement reference body is different. The bearing rotation accuracy measuring device according to (1) or (2), comprising two displacement meters arranged in a state of being shifted in phase.
(4) The displacement measuring means is arranged around the measurement reference body at each of at least two positions where the axial distance between the bearing and the measurement reference body is different, and the measurement reference body is rotated. An angle information meter for detecting an angle is further provided. The bearing rotation accuracy measuring device according to (1) or (2).
(5) A bearing rotational accuracy measuring method for measuring rotational accuracy of a bearing,
Disposing a measurement reference body on a central axis of a rotating body supported by the bearing;
Measuring at least two or more positions where the axial distance between the bearing and the measurement reference body is different, by measuring a deflection in the radial direction of the measurement reference body by a displacement measuring means;
A rotational accuracy measuring method for bearings, comprising:
(6) The bearing rotation accuracy method according to (5), wherein the measurement reference body is a reference sphere.
(7) The displacement measuring means is 90 degrees around the measurement reference body in the circumferential direction of the rotating body at at least two positions where the axial distance between the bearing and the measurement reference body is different. (2) The rotational accuracy measuring method for bearings according to (5) or (6), further comprising two displacement meters arranged in a phase shifted state.
(8) The displacement measuring means is arranged around the measurement reference body at each of at least two positions where the axial distance between the bearing and the measurement reference body is different, and the measurement reference body is rotated. An angle information meter for detecting an angle is further provided. The bearing rotation accuracy measuring method according to (5) or (6), characterized in that:

  According to the bearing rotational accuracy measuring device and the measuring method of the present invention, the displacement measuring means for measuring the radial deflection of the measurement reference body has at least two positions where the axial distance between the bearing and the measurement reference body is different. Therefore, in addition to the radial runout of the bearing, it is necessary to effectively measure the bearing runout accuracy required for the swivel shaft of the rotary table of the machine tool, main spindle swivel unit, etc. in addition to the radial runout of the bearing. Can do.

  Hereinafter, a bearing rotation accuracy measuring device and a measuring method according to an embodiment of the present invention will be described in detail with reference to FIGS.

  The bearing rotation accuracy measuring device 10 according to the present embodiment measures the surface runout accuracy of the rotating body 15 supported by the measurement bearing 1 in addition to the radial runout of the measurement bearing 1 incorporated in the device 10. . In this embodiment, a combination angular contact ball bearing applicable to support a rotary table of a machine tool is used as the measurement bearing 1, and an inner ring 2, an outer ring 3, a ball 4, a cage 5, and Each ball bearing provided with the seal member 6 is arranged in a backside combination.

  As shown in FIG. 1, the bearing rotational accuracy measuring device 10 is fastened and fixed to a measuring table 11, and is fitted around the inner ring 2 of the measurement bearing 1, and an outer peripheral surface as a driving means. A flat rotating belt 14 is wound and fitted in a state where the outer ring 3 of the measurement bearing 1 is sandwiched, and a cylindrical rotating part 14 is disposed on the rotating part 14. Including a shake adjusting mechanism 20 for disposing on the central axis of the rotating body 15 and a displacement measuring means 40 for measuring the shake of the reference sphere 21 in the radial direction.

  The rotating unit 14 fastens the two outer rings 3 in the axial direction by fastening rotating parts 14a and 14b each having an axial end surface. In addition, the fixing portion 12 fastens the two inner rings 2 in the axial direction by fastening two fixing parts 12a and 12b each having an axial end face, and applies the preload of the bearing 1 and also fixes the two inner rings 2 to each other. It is fixed in the axial direction.

  The shake adjustment mechanism 20 includes a reference plate 22 on a substantially disk that is fastened and fixed to the upper side surface of the cylindrical rotating portion 14, a shake adjustment component 23 to which the reference sphere 21 is fixed, and a center portion on the upper surface of the reference plate 22. And a conical hole 22a formed in the center of the lower surface of the shake adjusting component 23, and a shake adjusting ball 24 constituting a ball joint together with the conical holes 22a and 23a, Is provided. Further, in the shake adjusting mechanism 20, the tension bolts 25 that are in contact with the upper surface of the reference plate 22 and the tension bolts 26 that are screwed into the screw holes 22 b of the reference plate 22 are arranged in the circumferential direction. Are alternately provided at equal intervals. The rotating body 15 according to the present embodiment includes the rotating unit 14 and the reference plate 22. Further, the deflection adjusting mechanism 20 may be configured by only the tension bolt 26 without the tension bolt 25.

  Further, as shown in FIGS. 3 (a) and 3 (b), the shake adjusting mechanism 20 is provided with a substantially flat disk-shaped reference plate 22 shown in FIG. The other two shake adjustment mechanisms 30 and 31 including two reference plates 27 and 28 having cylindrical portions 27b and 28b having different heights, the upper surfaces of which are opposed to the lower surface of the shake adjustment component 23 projecting upward, are provided. Is provided. As shown in FIG. 4, the other two shake adjusting mechanisms 30 and 31 are connected to the reference plate 22 of the shake adjusting mechanism 20 and the spacer s, so that the cylindrical portions 27b and 28b and the substantially flat disc portion. 27a and 28a may be formed.

  In the shake adjustment mechanisms 20, 30, and 31 configured in this manner, the tension adjustment bolts 25 and the tension bolts 26 at appropriate circumferential positions are adjusted and rotated, and the shake adjustment component 23 is oscillated and displaced with the ball joint as a fulcrum. Thus, the center point O of the reference sphere 21 is adjusted to a position slightly displaced (about several μm) from the center axis L of the rotating body 15. The shake adjustment mechanisms 20, 30, and 31 may have other configurations as long as the center point of the reference sphere 21 is positioned in the vicinity of the center axis L of the rotating body 15. It may be configured as follows.

  As shown in FIG. 2, the displacement measuring means 40 has at least two or more (three in this embodiment) height positions L1, L2, L3 in which the axial distance between the measuring bearing 1 and the reference sphere 21 is different. Thus, around the reference sphere 21, there are provided two displacement meters 41 and 42 arranged with a phase shifted by 90 degrees in the circumferential direction of the rotating body 15. The displacement meters 41 and 42 may be arranged for each of the height positions L1, L2, and L3, respectively, or may be arranged so as to be movable and adjustable to the height positions L1, L2, and L3. If the displacement meter is expensive, the movement adjustment type is less expensive.

  The displacement gauges 41 and 42 are non-contact type sensors such as a laser Doppler vibrometer and a capacitance type displacement sensor that can measure the minute displacement of the outer peripheral surface without contacting the reference sphere 21 as the object to be measured. Things are used. However, a contact type such as an electric micrometer can be used as long as the measurement pressure is very small and does not affect the rotational asynchronous vibration. Further, as in the present embodiment, by providing two displacement meters 41 and 42 whose phases are shifted by 90 degrees at each height position, a Lissajous waveform can be obtained, and the radial deflection (displacement) of the reference sphere 21 can be obtained. ) Is obtained, and the maximum value of the rotational asynchronous vibration can be reliably detected.

  In the rotational accuracy measuring device 10 configured as described above, first, the measurement bearing 1 is fixedly disposed between the fixed portion 12 and the rotating portion 14, and further, the distance from the reference ball 21 to the intermediate position of the measurement bearing 1. The reference ball 21 is arranged in the vicinity of the central axis L of the rotating body 15 by fixing the shake adjusting mechanism 20 with L1 to the rotating unit 14 and adjusting the mechanism 20. Then, the rotating unit 14 is rotationally driven by the flat belt 13, and the radial deflection of the reference sphere 21 that rotates integrally is detected by the two displacement meters 41 and 42.

  Further, the radial direction of the reference sphere 21 is changed in the same manner as described above while exchanging the shake adjusting mechanisms 30 and 31 having the distances from the reference sphere 21 to the intermediate position of the measurement bearing 1 to L2 and L3, respectively. Detects runout. Thereby, the surface runout accuracy of the measurement bearing 1 can be measured.

  For example, as shown in FIG. 5A, when the bearing 1a is swung only in the radial direction, it can be expected that the surface runout is reduced when the bearing 1a is incorporated in the rotary table of the machine tool. On the other hand, as shown in FIG. 6A, in the case of the bearing 1b having runout that rotates obliquely, the runout becomes large after being incorporated in the machine tool.

  However, in order to evaluate this in advance with a single bearing, just measuring the deflection of the reference ball 21 at one location in the vicinity of the bearing as in the prior art makes no significant difference between the two, making it difficult to evaluate. On the other hand, as shown in FIGS. 5B and 6B, the surface runout accuracy of the bearing alone can be measured by measuring the runout of the reference sphere 21 at at least two positions.

  As described above, according to the bearing rotation accuracy measuring device 10 and the measuring method of the present embodiment, the displacement measuring means 40 that measures the radial deflection of the reference sphere 21 is provided between the bearing 1 and the reference sphere 21. Since the radial runout is measured at at least two positions L1, L2, and L3 having different axial distances, in addition to the radial runout of the bearing 1, the bearing 1 required for the rotary table of the machine tool is required. Surface runout accuracy can be measured effectively.

In addition, this invention is not limited to embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably.
For example, in the present embodiment, two displacement meters 41 and 42 are used as the displacement measuring means 40 at each of at least two positions where the axial distance between the measurement bearing 1 and the reference sphere 21 is different. As shown in FIG. 7, one displacement meter 41 is arranged around the reference sphere 21, and an angle information meter 50 including a gear 51 and a detection head 52 that detects the rotation angle of the reference sphere 21 is further provided. The displacement in the radial direction may be detected using the displacement meter 41 and the angle information meter 50. In this case, the measurement result is given as an error from a sine wave that includes a radial shake component. The angle information meter 50 may be a magnetic encoder in addition to the gear type as shown in FIG. If the measured rotation speed is constant, only one rotation signal may be extracted and used as angle information.

  Further, in the present embodiment, the reference sphere 21 in which sphericity is easily obtained is used as the measurement reference body. However, if the surface shake component (radial shake component) can be accurately extracted, Any configuration may be used.

  Furthermore, in this embodiment, a combination angular contact ball bearing is used as the measurement bearing, but it can be applied as a bearing for supporting a rotary table of a machine tool, such as a cross roller bearing, a double row angular contact ball bearing, or a composite roller bearing. Any bearing can be used.

  In the measuring apparatus of the present embodiment, the member that externally fits the inner ring of the measurement bearing is a fixed part, and the member that internally fits the outer ring is a rotating part. However, the member that externally fits the inner ring is rotationally driven by a belt. Thus, the rotating part and the member that internally fits the outer ring may be used as a fixed part, and the shake adjusting mechanism may be attached to the rotating part.

  In addition, the measurement object of the rotational accuracy measuring device and measuring method for bearings of the present invention is not limited to the bearing that supports the rotary table as in the above embodiment, but for the swivel shaft as shown in FIG. The bearing 1c may be the target.

  That is, this bearing 1c supports the turning shaft 61 driven by the direct drive motor 60 so as to be turnable with respect to the pair of support arms 62, and a combined angular ball bearing is used. Then, as the turning shaft 61 is driven to turn, the main shaft portion 63 to which the tool T is attached is also turned as shown by the arrow A. The spindle head 64 having the pair of support arms 62 is provided so as to be capable of rotational indexing as indicated by an arrow B.

  Even in such a bearing 1c for the turning shaft and a bearing that supports the movement of the arrow B, since the rotational runout accuracy of the bearing 1c affects the processing accuracy by the tool T, it is effective to apply the measuring device and the measuring method. It is.

  Here, using two measurement bearings a and b, the run-out measurement was performed by the rotation accuracy measuring apparatus of the above-described embodiment shown in FIG. 9 and 10 are Lissajous waveforms in which the values obtained from the non-contact displacement meters 41 and 42 are plotted as the X axis and the Y axis at the respective height positions L1, L2, and L3.

  From the measurement results of FIGS. 9 and 10, it can be seen that the rotational accuracy of the measurement bearing b is greatly deteriorated with increasing distance from the bearing than the measurement bearing a. As a result, it can be seen that the measurement bearing a is a highly accurate bearing as a rotary table bearing, and that the accuracy of the bearing can be effectively measured by performing the measurement method of the present invention.

It is sectional drawing of the rotational accuracy measuring apparatus for bearings which concerns on one Embodiment of this invention. It is a top view of the rotational accuracy measuring apparatus for bearings shown in FIG. (A) is sectional drawing of the shake adjustment mechanism used for a 2nd position, (b) is sectional drawing of the shake adjustment mechanism used for a 3rd position. (A) is sectional drawing of the modification of the shake adjustment mechanism used for a 2nd position, (b) is sectional drawing of the modification of the shake adjustment mechanism used for a 3rd position. (A) is a schematic diagram which shows a table and a bearing when a surface runout is small, (b) is a schematic diagram which shows the measuring method when the surface runout of this invention is small. (A) is a schematic diagram which shows a table and a bearing when a surface runout is large, (b) is a schematic diagram which shows the measuring method when the surface runout of this invention is large. It is a top view which shows the modification of the rotational accuracy measuring apparatus for bearings. (A) is a perspective view which shows the spindle head to which the bearing for rotation axes is applied as a measuring object, (b) is the sectional drawing. It is a figure which shows the measurement result of the two displacement meters in each axial direction position at the time of using the test bearing a. It is a figure which shows the measurement result of the two displacement meters in each axial direction position at the time of using the test bearing b. It is sectional drawing which shows the conventional rotational accuracy measuring apparatus. It is a figure for demonstrating the measuring method of JISB6336-3.

Explanation of symbols

1,1a Measuring bearing 10 Bearing rotational accuracy measuring device 15 Rotating body 20 Runout adjustment mechanism 21 Reference ball (measurement reference body)
22 Reference plate 23 Runout adjustment component 24 Runout adjustment ball 40 Displacement measuring means 41, 42 Displacement meter

Claims (8)

A bearing rotation accuracy measuring device for measuring the rotation accuracy of a bearing,
A measurement reference body disposed on a central axis of a rotating body supported by the bearing;
Displacement measuring means for measuring a radial deflection of the measurement reference body;
With
The bearing measurement accuracy measuring apparatus according to claim 1, wherein the displacement measuring unit measures the radial runout at at least two positions where the axial distance between the bearing and the measurement reference body is different.   The bearing measurement accuracy measuring apparatus according to claim 1, wherein the measurement reference body is a reference sphere.   The displacement measuring means shifts the phase by 90 degrees around the measurement reference body in the circumferential direction of the rotating body at at least two positions where the axial distance between the bearing and the measurement reference body is different. The bearing rotational accuracy measuring device according to claim 1, further comprising two displacement meters arranged in a state where the bearing is rotated.   The displacement measuring means is arranged around the measurement reference body at each of at least two positions where the axial distance between the bearing and the measurement reference body is different, and the rotation angle of the measurement reference body is detected. The bearing rotation accuracy measuring device according to claim 1, further comprising an angle information meter for performing the rotation. A bearing rotational accuracy measurement method for measuring the rotational accuracy of a bearing,
Disposing a measurement reference body on a central axis of a rotating body supported by the bearing;
Measuring at least two or more positions where the axial distance between the bearing and the measurement reference body is different, by measuring a deflection in the radial direction of the measurement reference body by a displacement measuring means;
A rotational accuracy measuring method for bearings, comprising:   The bearing measurement accuracy method according to claim 5, wherein the measurement reference body is a reference sphere.   The displacement measuring means shifts the phase by 90 degrees around the measurement reference body in the circumferential direction of the rotating body at at least two positions where the axial distance between the bearing and the measurement reference body is different. The rotational accuracy measuring method for a bearing according to claim 5 or 6, further comprising two displacement meters arranged in a closed state.   The displacement measuring means is arranged around the measurement reference body at each of at least two positions where the axial distance between the bearing and the measurement reference body is different, and the rotation angle of the measurement reference body is detected. The method according to claim 5 or 6, further comprising an angle information meter for performing the bearing rotation accuracy measurement.

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