JP2012159499A - Measuring apparatus and measuring method for ball screw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily inspect a groove shape on an inner peripheral surface of a ball screw nut in a short time.SOLUTION: The ball screw nut is supported rotatably by a rotary table 22, and its angle of rotation is measured by a rotary encoder 23. A gage head 3 is supported by an XYZ table 12 freely movably in XYZ directions, displacement in an X-axial direction in which the gage head 3 moves in a direction of the ball screw nut is measured by a linear gage 13, and displacement in a Z-axial direction in which the gage head 3 moves up and down is measured by a dial gage 14. Based upon detection signals of those sensors, position coordinates of the gage head 3 on the ball screw nut are computed so as to measure respective parts of the ball screw nut based upon the position coordinates.

Description

  The present invention relates to a ball screw measuring apparatus and measuring method for performing various measurements such as the shape and position of each part of a ball screw.

The ball screw is arranged between a nut having a spiral groove formed on the inner peripheral surface, a screw shaft having a spiral groove formed on the outer peripheral surface, and a track formed by the spiral groove of the nut and the spiral groove of the screw shaft. And a ball return path for returning the ball from the end point of the track to the viewpoint, and the nut moves relative to the screw shaft as the ball rolls in the track.
Such a ball screw is used not only for a general industrial machine positioning device but also for an electric actuator mounted on a vehicle such as an automobile, a two-wheeled vehicle or a ship.

The ball return path of the ball screw includes a circulation tube system, a top system, and the like. In the case of the top system, a top formed with a recess that forms the ball return path is fitted in the through hole of the nut. On the other hand, a method has also been proposed in which a recess (circulation groove) forming a ball return path is directly formed on the inner peripheral surface of the nut material by plastic working.
By the way, as described above, as a method for measuring and inspecting irregularities such as the inner surface of the spiral groove on which the ball rolls, for example, Patent Document 1 listed below has the same diameter as the ball arranged between the tracks. A method of inspecting the shape of the spiral groove by measuring the displacement of the probe while positioning the probe on the spiral groove and moving the probe along the spiral groove is proposed. (For example, refer to Patent Document 1).

Japanese Patent No. 3572951

  As described above, when the shape of the spiral groove is measured using a spherical measuring element having the same diameter as the ball arranged between the tracks, and the ball screw is inspected based on this, the measurement is performed along the spiral groove. Since the spiral groove is inspected by moving the element, for example, there is no problem in measuring the axial position of the measuring element on the spiral groove of the nut material, but the circulation groove is forged on the inner peripheral surface of the nut material It is difficult to measure the pitch of the circulation groove in a nut integrated with the circulation groove that is directly formed by, for example.

That is, in many cases, the circulation grooves are provided, for example, at a predetermined pitch and with different phases on the inner peripheral surface of the nut material. Therefore, in order to measure the pitch of the circulation groove, it is necessary to relatively rotate the nut material and the measuring element and measure the amount of movement. In the above conventional inspection method, the amount of movement in the relative rotation is required. Therefore, there is a demand for a measuring device and a measuring method that can easily measure each part of the ball screw, such as the measurement of the pitch of the circulation groove, and that can measure with high accuracy. It was.
Accordingly, an object of the present invention is to provide a ball screw measuring device and a measuring method capable of easily and accurately measuring the shape and position of each part of the ball screw.

  In order to achieve the above object, a ball screw measuring apparatus according to claim 1 of the present invention is configured to move the measuring element along a groove formed in a ball screw shaft or a ball screw nut constituting the ball screw. A ball screw measuring device for measuring a ball screw, comprising: a first support means for supporting the ball screw shaft or the ball screw nut as a measurement object; and a second support means for supporting the measuring element. The first support means and the second support means support the measurement object and the measuring element so as to be relatively movable along an axis of the measurement object, and the radial direction of the measurement object And relative to the measuring object and the measuring element in the direction along the axis of the measuring object. Displacement And axial displacement detecting means for output, and characterized by comprising a radial displacement detection means for detecting a relative displacement in the radial direction, and the circumferential direction displacement detecting means for detecting the circumferential direction of the relative displacement, a.

The ball screw measuring apparatus according to claim 2 is characterized in that the measuring element is a single sphere having the same diameter as a rolling sphere that rolls in the groove.
The ball screw measuring device according to claim 3, wherein the groove is a circulation groove formed integrally with the ball screw shaft or a ball screw nut and having a concave portion forming a ball return path. It is a fitting member that is fitted in the recess of the circulation groove and positioned in the circulation groove.

The ball screw measuring apparatus according to a fourth aspect is characterized in that the measuring element has the same shape as the concave portion of the circulation groove and has a convex shape of the circulation groove that fits into the circulation groove.
The ball screw measuring device according to claim 5 is characterized in that the measuring element is two spheres, and the two spheres are fitted to the circulation groove in a state of being opposed to both longitudinal ends of the circulation groove. It is said.

The ball screw measuring apparatus according to claim 6, wherein the measuring element has an arc part having a diameter larger than a diameter of a rolling sphere rolling the groove, and the arc part and the groove of the measuring element Is characterized by the fact that they come into contact with each other.
The ball screw measuring device according to claim 7 is characterized in that the measuring element is a sphere having a diameter larger than the diameter of the rolling sphere.

The ball screw measuring apparatus according to claim 8 is characterized in that the diameter of the measuring element is smaller than the opening width of the groove.
The ball screw measuring apparatus according to claim 9, wherein the measuring element is a columnar or columnar member having a diameter larger than the diameter of the rolling sphere, and the cross-section of the columnar member has two adjacent corners in an arc. It is characterized by a rectangular shape consisting of
The ball screw measuring device according to claim 10, wherein the first support means rotatably supports the measurement object in the circumferential direction, and the second support means uses the measuring element as an axis of the measurement object. It is characterized by being supported so as to be movable in the direction along and in the radial direction.

  According to a eleventh aspect of the present invention, there is provided a ball screw measurement method, wherein the ball screw is measured by moving a measuring element along a groove formed in a ball screw shaft or a ball screw nut constituting the ball screw. A measuring method, wherein the measuring element is moved along a groove of the measuring object with the ball screw shaft or the ball screw nut as a measuring object, and the measurement between the measuring object and the measuring element at this time is performed. The relative displacement in the direction along the axis of the object, the relative displacement in the radial direction of the measurement object, and the relative displacement in the circumferential direction around the measurement object axis are measured, and based on these measurement values, the measurement It is characterized by measuring the object.

  The ball screw measurement method according to claim 12 is characterized in that the groove is a circulation groove formed integrally with the ball screw shaft or a ball screw nut and formed by a concave portion forming a ball return path. It is composed of two spheres, measures the position coordinates of both ends in the longitudinal direction of the circulation groove using the probe, calculates the position coordinates of the center of the circulation part from the position coordinates of the ends, and calculates the center The position coordinate of the part is the position coordinate of the circulation groove.

  The ball screw measuring method according to claim 13 is characterized in that the groove is a circulation groove formed integrally with the ball screw shaft or a ball screw nut and having a concave portion forming a ball return path, It is composed of a fitting member that is fitted to the concave portion of the circulation groove and positioned in the circulation groove, and the position coordinate of the measurement element when the measurement piece is fitted to the circulation groove is the position coordinate of the circulation groove. It is characterized by that.

The ball screw measuring method according to claim 14 detects the position coordinates of the circulation groove, and based on the position coordinates of the circulation groove and the position reference of the circulation groove set in advance, the position reference of the circulation groove and the The phase of the circulation groove is measured from the phase difference from the position of the circulation groove.
The ball screw measuring method according to claim 15 is characterized in that the position coordinate of the circulation groove is detected, and the depth of the circulation groove at the position coordinate of the circulation groove is measured as the depth of the circulation groove. Yes.

  In the ball screw measuring method according to claim 16, the measuring element is formed of a single sphere, and the measuring object is maintained in a state in which the measuring element is in contact with the groove of the measuring object. Rotate in the circumferential direction around the axis, measure each relative displacement of the probe moving along the groove of the measurement object as the measurement object rotates, and based on these measurement values, It is characterized by measuring the locus of the groove center of the groove.

  The ball screw measuring method according to claim 17, wherein the groove is a substantially S-shaped circulation groove formed of a concave portion forming a ball return path, which is formed integrally with the ball screw shaft or the ball screw nut. The relative displacement of the probe moving from one end to the other end of the circulation groove along the circulation groove with the rotation of the measurement object is measured, and the locus of the groove center of the circulation groove is determined based on these measured values. It is characterized by measuring.

  The ball screw measuring method according to claim 18, wherein the groove is a spiral groove formed in a spiral shape and the circulation groove, and a center in the width direction of the spiral groove at a connection portion between the spiral groove and the circulation groove. A position coordinate of the position and a position coordinate of the center position in the width direction of the circulation groove in the connecting portion are measured, and based on the measured position coordinates, the width direction center position of the spiral groove and the width direction center position of the circulation groove are determined. A straight line to be connected is detected as a lead angle equivalent value, and a connection deviation state between the spiral groove and the circulation groove is measured based on the lead angle equivalent value.

  The ball screw measuring method according to claim 19 is characterized in that the spiral groove is a groove whose groove bottom is a non-single arc in its cross section, and the circulation groove is a groove whose groove bottom is a single arc in its cross section. Thus, when measuring the position coordinates of the center position in the width direction of the spiral groove, a first measuring element made of a sphere having the same diameter as the rolling sphere rolling the groove is used as the measuring element, When measuring the position coordinates of the center position in the width direction, a second measuring element made of a sphere having a diameter larger than the diameter of the rolling sphere is used as the measuring element.

  A measuring method of a ball screw according to claim 20 uses a third measuring element and a fourth measuring element which are spheres having a diameter larger than the diameter of the rolling sphere rolling in the groove and having different diameters. A position coordinate of an arbitrary measurement position of the groove is measured, and based on the measured position coordinate, a center position of the sphere constituting the third probe and a center position of the sphere constituting the fourth probe Is detected, an angle formed by the straight line and a straight line along the radial direction of the measurement target is detected, and based on the angle, whether the groove shape of the groove is bilaterally symmetric is measured. It is said.

The ball screw measuring method according to claim 21, wherein the groove is a circulation groove formed of a recess that forms a ball return path, and the pitch, position, phase, depth of the circulation groove, and the groove of the circulation groove. One of the features is that the shape is symmetric or not.
23. The ball screw measuring method according to claim 22, wherein the groove is a spiral groove formed in a spiral shape, and the pitch, position, roundness, and groove shape of the spiral groove are left and right. It is characterized by measuring either symmetric or not.
24. The ball screw measuring method according to claim 23, wherein the groove is a circulation groove formed of a concave portion forming a ball return path and a spiral groove formed in a spiral shape, and a connection portion between the circulation groove and the spiral groove. One of the steps is to measure either a step or a positional deviation.

  According to the present invention, the measuring object and the measuring element can be obtained by the first supporting means for supporting the ball screw shaft or the ball screw nut as the measuring object and the second supporting means for supporting the measuring element. Supporting relative movement along the axis of the measurement object, supporting relative movement in the radial direction of the measurement object, and supporting relative movement in the circumferential direction around the measurement object axis, Since the relative displacement in the direction along the axis of the measurement object, the relative displacement in the radial direction, and the relative displacement in the circumferential direction between the measurement object and the measuring element are detected, a ball screw shaft or By moving the measuring element along the groove formed in the ball screw nut, the relative displacement in the direction along the axis of the measuring object, the relative displacement in the radial direction of the measuring object and the measuring element, Circumferential relative The position can be easily detected, by using these relative displacement, the shape and position of each part of the measurement object can be easily detected.

It is a lineblock diagram showing an example of a measuring device in a 1st embodiment. It is a figure which shows the state which mounted | wore the nut support mechanism with the ball screw nut. It is a block diagram which shows the other example of a measuring jig. It is explanatory drawing of the detection method of the center of a Y direction. It is a figure for demonstrating the intermediate position of a circulation groove. It is a schematic block diagram of the measuring element in 2nd Embodiment. It is a schematic block diagram which shows the other example of a measuring element. It is a figure for demonstrating the shape of the measuring element in 3rd Embodiment. It is a figure for demonstrating the measuring method in 4th Embodiment. It is a figure for demonstrating the shape of the measuring element in 5th Embodiment. It is a figure for demonstrating the shape of the measuring element in 6th Embodiment. It is a figure for demonstrating the shape of the measuring element in 7th Embodiment.

Embodiments of the present invention will be described below.
First, a first embodiment will be described.
FIG. 1 is a perspective view showing an embodiment of a ball screw measuring apparatus to which the present invention is applied.
The measuring device 1 includes a measuring device support mechanism 5 that supports a measuring device 4 having a measuring element 3 and a nut support mechanism 7 that supports a ball screw nut that is a measurement target on a base 2.
The measuring element 3 is formed of one steel ball having the same diameter as a ball that rolls in a spiral groove (not shown). Note that the probe 3 need not be made of steel.

  The measuring instrument support mechanism 5 includes a measuring instrument holding member 11 that holds the measuring instrument 4 and an XYZ table that supports the measuring instrument holding member 11 so as to be movable in the X axis direction, the Y axis direction, and the Z axis direction orthogonal to each other. 12. In FIG. 1, the direction in which the probe 3 is moved horizontally toward the nut support mechanism 7 is the X axis direction, the direction in which the probe 3 is moved in the horizontal direction perpendicular to the X axis is the Y axis direction, and the probe 3 is moved up and down. The direction of movement in the (vertical direction) is the Z-axis direction.

  The XYZ table 12 is configured such that the movable member 12b moves along a guide rail 12a arranged on the base 2, for example, and the position of the movable member 12b in the X-axis direction is parallel to the guide rail 12a. A linear gauge 13 for detection is provided. Further, a dial gauge 14 for detecting a displacement of the XYZ table 12 in the Z-axis direction is provided at an appropriate position of the XYZ table 12.

On the other hand, the nut support mechanism 7 includes a holding member 21 that holds a ball screw nut to be measured, a rotary table 22 that rotatably supports the holding member 21, and a rotary encoder 23 that detects a rotation angle of the rotary table 22. The rotary encoder 23 is connected to a signal processing device 23a that detects a rotation angle based on the encoder output.
FIG. 2 shows a state in which the ball screw nut 6 is mounted on the holding member 21 in the nut support mechanism 7. In FIG. 2, the measurement jig 31 holds the ball screw nut 6, and the holding member 21 is formed with a chuck mechanism 21 a that detachably holds and holds the measurement jig 31. 6 is fixed to the measurement jig 31, and the measurement jig 31 is held by the chuck mechanism 21a, so that the axis (center axis) of the ball screw nut 6 and the rotation axis of the rotary table 22 are aligned with each other. The ball screw nut 6 is fixed to the holding member 21.

  As shown in FIG. 2, the measuring jig 31 has a thick cylindrical shape that can accommodate the ball screw nut 6 and has an inner diameter equivalent to the outer diameter of the ball screw nut 6. The length of the measuring jig 31 in the axial direction is the length that can be accommodated up to the flange portion 6 a of the ball screw nut 6, and the non-opening side surface of the cylindrical measuring jig 31 has the ball screw nut 6. A circular opening 31a having the same inner diameter d2 (= d1) as the inner diameter d1 is formed. At an appropriate position on the inner periphery of the edge on the opening side of the measuring jig 31, a step 31 b is formed which is approximately equal to the thickness of the flange portion 6 a of the ball screw nut 6. Then, the ball screw nut 6 is housed in the measuring jig 31 and the flange portion 6a is brought into contact with the step 31b, whereby the flange portion 6a is fitted into the edge of the measuring jig 31, and in this state, the step 31b portion A clamp 31c is provided so as to suppress the flange portion 6a of the screw, and a bolt 31e is fixed to a screw hole 31d formed in the measurement jig 31 via the clamp 31c, whereby the shaft of the ball screw nut 6 and the measurement jig are fixed. The ball screw nut 6 is fixed to the measuring jig 31 with the axis of the tool 31 aligned.

  When a mounting hole is formed in the flange portion 6a of the ball screw nut 6, the measuring jig 31 is connected to the flange portion of the ball screw nut 6 as shown in a simplified manner in FIG. The cylindrical part 6b excluding 6a is formed so as to be housed. That is, by forming the inner diameter of the measuring jig 31 to be approximately equal to the outer diameter of the cylindrical portion 6b of the ball screw nut 6, the movement of the cylindrical portion 6b of the ball screw nut 6 in the measuring jig 31 is restricted, and the ball The flange portion 6a of the screw nut 6 and the opening side edge top surface 31f of the measuring jig 31 are in contact with each other, thereby restricting the movement of the ball screw nut 6 in the measuring jig 31 in the axial direction, and is formed in the flange portion 6a. By fixing the flange portion 6a to the edge of the measuring jig 31 with a bolt 31e through the mounting hole 6c, the axis of the ball screw nut 6 (center axis) and the axis of the measuring jig 31 (center axis) And the ball screw nut 6 may be fixed to the measuring jig 31.

  Further, in the case of the ball screw nut 6 having no flange portion, as shown in a simplified manner in FIG. 3B, in the measuring jig 31 of FIG. The length of the ball screw nut 6 is slightly shorter than the axial length of the ball screw nut 6, the ball screw nut 6 is accommodated in the measuring jig 31, and the end surface of one edge of the ball screw nut 6 is held by the clamp 31c. In this state, the ball screw nut 6 and the measurement jig 31 may be fixed by fixing the bolt 31e to the screw hole 31d of the measurement jig 31 via the clamp 31c.

Here, the case where the ball screw nut 6 is attached to the chuck mechanism 21a via the measurement jig 31 has been described, but the ball screw nut 6 is directly fixed to the chuck mechanism 21a without using the measurement jig 31. It is also possible. However, in order to perform more accurate measurement, it is preferable to fix via the measurement jig 31.
As described above, the ball screw nut 6 is attached to the chuck mechanism 21a via the measuring jig 31, and the ball screw nut is exchanged according to the shape of the ball screw nut 6. Regardless of the shape of 6, the ball screw nut 6 can be attached to the chuck mechanism 21a.

  The measuring instrument support mechanism 5 and the nut support mechanism 7 are arranged so that the ball screw nut 6 attached to the chuck mechanism 21a via the measuring jig 31 and the measuring element 3 face each other, and the chuck mechanism 21a With the ball screw nut 6 attached, the XYZ table 12 is operated to move the probe 3 in the X axis, Y axis, and Z axis directions, and the rotary table 22 is operated to rotate the ball screw nut 6. Thus, the probe 3 can be scanned over the entire inner region of the ball screw nut 6.

Next, a measurement procedure using the measurement apparatus of FIG. 1 will be described.
First, the ball screw nut 6 to be measured is mounted on the chuck mechanism 21a via the measuring jig 31 as shown in FIG. The ball screw nut 6 to be measured has a recess (hereinafter referred to as a circulation groove) 6A that forms a ball return path on the inner peripheral surface, and is directly formed on the inner peripheral surface by plastic processing such as forging or removal processing such as cutting. In addition, a spiral groove (not shown) is formed. The spiral groove is a groove on which the ball rolls, and the circulation groove 6A is a groove for connecting the start point and the end point of the spiral groove and circulating the ball. Here, a case will be described in which measurement is performed on a ball screw nut that forms a 360 ° closed circuit with the spiral groove and the circulation groove 6A.
The ball screw nut 6 may be a ball screw nut 6 in a state in which a spiral groove and a circulation groove are formed, or the ball screw nut 6 in the middle of manufacture in which only the circulation groove is formed. Even a ball screw nut 6 in which a spiral groove having no circulation groove is formed can be applied.

  When the ball screw nut 6 is attached to the chuck mechanism 21a, measurement standards are set in advance for the rotary table 22 and the ball screw nut 6, and the measurement standard of the rotary table 22 and the measurement standard of the ball screw nut 6 are determined. The ball screw nut 6 is mounted on the chuck mechanism 21a so as to match. For example, a notch is provided in the measurement jig 31 and the ball screw nut 6 so that the notches are aligned with each other, or a key is placed on the measurement jig 31 according to the notch of the ball screw nut 6. The ball screw nut 6 is attached to the measuring jig 31 so that the notch of the ball screw nut 6 and the key of the measuring jig 31 are engaged. Then, a relative relationship between the measurement jig 31 and the chuck mechanism 21a in which the measurement standard of the rotary table 22 and the measurement standard of the ball screw nut 6 coincide with each other is set in advance, and the measurement process is performed so that this relative relationship is obtained. The tool 31 is mounted on the chuck mechanism 21a.

  Next, by operating the XYZ table 12, first, the probe 3 is moved to a position in contact with the inner periphery of the ball screw nut 6, and the probe 3 is moved to the lowest point of the ball screw nut 6, as shown in FIG. Adjust so that That is, when the ball screw nut 6 is viewed from the axial direction, the lowest point at which the position of the probe 3 in contact with the ball screw nut 6 is lowest is searched. And the lowest point of this ball screw nut 6 is made into the center of a Y direction. Then, the Y-axis direction is fixed in the XYZ table 12.

  Next, the probe 3 is moved in the X-axis direction, and the probe 3 is moved to a position facing the inner periphery of the opening 31 a of the measurement jig 31 as shown in FIG. Then, the Z-axis direction is adjusted so that the probe 3 contacts the inner periphery of the opening 31a, and the position in the Z-axis direction at this time is set as the initial position in the Z-axis direction. Then, the dial gauge 14 is zeroed in a state where the probe 3 is at the initial value in the Z-axis direction. As a result, as shown in FIG. 2, the dial gauge output of the dial gauge 14 when the probe 3 is in contact with the groove bottom of the circulation groove 6 </ b> A is based on the inner periphery of the opening 31 a of the measuring jig 31. It represents the depth e of the groove bottom. Here, the ball screw nut 6 has a circulation groove 6A and a spiral groove (not shown) formed by forging or the like, and the ball screw nut 6 may be deformed at that time. Therefore, the dial gauge 14 is zeroed using the measurement jig 31 instead of the ball screw nut 6. Note that the above-described setting of the center in the Y direction may also be performed using a measurement jig.

Next, the measuring element 3 is moved in the X-axis direction, and the tip of the measuring instrument 4 is moved to a position where it abuts against the end face of the ball screw nut 6 on the measuring instrument support mechanism 5 side. The position in the X-axis direction at this time is set as the initial position in the X-axis direction.
As described above, measurement is possible.
In the measurement apparatus, the pitch, position, phase, depth, and the like of the circulation groove 6A can be measured. Moreover, about a spiral groove, the pitch, a position, roundness, depth, etc. can be measured. Further, the step and displacement between the circulation groove and the spiral groove can be measured.

First, a method for measuring the circulation groove 6A will be described.
The circulation groove 6A is formed in a substantially Roman S-shape as shown in FIG.
First, the XYZ table 12 is operated to adjust the X-axis direction, and the rotary table 22 is operated so that the measuring element 3 is moved to one of the end portions A and B of the S-shaped circulation groove 6A, for example, the end. It moves to the position vicinity which opposes the part A, and adjusts so that the measuring element 3 may contact the groove bottom of 6 A of circulation grooves. When the ball screw nut 6 is rotated in this state, the probe 3 hits the step of the circulation groove 6A at the position of the end A of the circulation groove 6A, and the movement is restricted. The position at which this movement is restricted is the position of the end A of the circulation groove 6A, and the rotary signal output of the rotary encoder 23, the linear signal output of the linear gauge 13 and the dial gauge signal output of the dial gauge 14 at this time are Acquired as position information of the end A.

In the same procedure, the rotary signal output from the rotary encoder 23, the linear signal output from the linear gauge 13, and the Z-axis displacement signal output from the dial gauge 14 are also acquired as position information for the end B. Then, an intermediate position C of the circulation groove 6A is obtained from the position information of the end portions A and B. As shown in FIG. 5, the circulation groove 6 </ b> A has a shape that is point-symmetric with respect to the intermediate position C, so that the position information of the intermediate position C is calculated from the position information of the end portions A and B. Can do. For example, from the position information of the end portions A and B, the position coordinates in the XYZ coordinates of the end portions A and B with reference to the measurement standard set for the ball screw nut 6 are obtained, and based on this, the position coordinates of the intermediate position C are obtained. Calculate.
In the same procedure, the position coordinates of the end portions A and B are obtained for the other circulation grooves 6A, and the position coordinates of the intermediate position C are obtained for each.

  Further, the pitch of the circulation grooves 6A can be obtained by taking the difference in the position coordinates of the intermediate positions C of the adjacent circulation grooves 6A in the position coordinates of the intermediate positions C of the circulation grooves 6A. Thus, by calculating the position coordinate of the intermediate position C of the circulation groove 6A and using this as the position coordinate of the circulation groove 6A, the circulation is performed without being affected by the shape, type, and size of the probe 3. The position coordinates of the groove 6A can be easily detected.

Further, the phase of the circulation groove 6A can be detected by obtaining the phase difference between the position coordinates of the intermediate position C of each circulation groove 6A and the measurement reference of the ball screw nut 6.
Further, the measuring element 3 is moved to the position of the position coordinate of the intermediate position C of each circulation groove 6A calculated in this way, and the measuring element 3 is brought into contact with the groove bottom in this state, and the dial of the dial gauge 14 at this time By obtaining the gauge signal output, the depth of the groove at the intermediate position C of the circulation groove 6A can be detected.

On the other hand, when measuring the position of a spiral groove (not shown) with respect to the circulation groove 6A (positional deviation between the spiral groove and the circulation groove 6A), first, the measuring element 3 is placed at the position of the intermediate position C of the circulation groove 6A. Move. In this state, the turntable 22 is rotated 180 degrees, and the measuring element 3 is brought into contact with the inner periphery of the ball screw nut 6 at this position.
Here, it is ideal that the position of the intermediate position C of the circulation groove 6A and the spiral groove have a point-symmetric positional relationship. Therefore, the position where the rotary table 22 is rotated 180 degrees should be the groove bottom of the spiral groove. Therefore, the rotary table 22 is rotated 180 degrees, and the probe 3 is finely moved in the X-axis direction at this position to search for the deepest portion of the spiral groove. Then, the amount of displacement between the position where the spiral groove is the deepest part and the position when the rotary table 22 is rotated 180 degrees from the intermediate position C is measured as the amount of displacement between the spiral groove and the circulation groove 6A.

Further, the depth of the spiral groove can be measured by bringing the probe 3 into contact with the groove bottom of the spiral groove. Further, in this state, every time the rotary table 22 is rotated 360 degrees along the spiral groove, the dial gauge signal output of the dial gauge 14, the linear signal output of the linear gauge 13, and the rotary signal output of the rotary encoder 23 are converted into position information. To win as. Based on this position information, the pitch between the spiral grooves can be calculated by taking the difference in the X-axis direction between the adjacent spiral grooves from the position coordinates every time the ball screw nut 6 is rotated 360 degrees.
Further, the probe 3 is moved along the spiral groove while being in contact with the bottom of the spiral groove, and the dial gauge signal output of the dial gauge 14 at this time is detected. Then, by obtaining the maximum outer diameter and the minimum inner diameter based on the dial gauge signal output, the roundness can be calculated therefrom.

  Further, when measuring the step between the circulation groove 6A and the spiral groove, based on the position coordinates of the end of the circulation groove 6A obtained by the above procedure, for example, the end A of FIG. The measuring element 3 is moved, and the measuring element 3 is brought into contact with the bottom of the circulation groove 6A. In this state, the probe 3 is moved along the circulation groove 6A to move toward the spiral groove. Then, the dial gauge signal output of the dial gauge 14 is detected when the probe 3 moves from the circulation groove 6A to the spiral groove, and based on this, the displacement when the probe 3 moves from the circulation groove 6A to the spiral groove is detected. This is detected as the amount of deviation in the groove depth direction of the step between the circulation groove 6A and the spiral groove.

  Further, the rotary table 22 is operated to rotate the ball screw nut 6 to obtain the linear signal output of the linear gauge 13 when the probe 3 is moved from the circulation groove 6A to the spiral groove. By detecting the displacement of the linear signal output of the linear gauge 13 when moving from the circulation groove 6A to the spiral groove, a shift amount in the groove width direction of the step between the circulation groove 6A and the spiral groove can be obtained.

  As described above, the rotary table 22 for rotating and supporting the ball screw nut 6 and the rotary encoder 23 for detecting the rotation angle of the rotary table 22 are provided, and the displacement amounts of the XYZ table 12 and the XYZ table 12 in the X-axis and Z-axis directions are determined. A linear gauge 13 and a dial gauge 14 are provided to detect the position in the X-axis direction, the amount of displacement in the Z-axis direction, and the rotation angle of the ball screw nut 6 when the inner circumference of the ball screw nut 6 is scanned by the measuring element 3. Thus, the shape of each part of the ball screw nut 6 can be easily measured based on these detection signals.

  In the first embodiment, drive control means for moving the XYZ table 12 and the rotary table 22 by a movement amount corresponding to the input command signal is further provided, and the target of the measuring element 3 and the ball screw nut 6 is provided. The XYZ table 12 is automatically moved in the XYZ axial directions and the rotary table 22 is driven to rotate so that the probe 3 is moved to the ball screw nut 6 by inputting a command signal corresponding to the movement amount. It can also be configured to automatically move to the position to be measured.

  Further, pressure detecting means for detecting the pressure applied to the measuring element 3 may be provided, and the contact between the ball screw nut 6 and the measuring element 3 may be detected based on an output signal of the pressure detecting means. . Furthermore, data storage means for storing the detection signals of various sensors such as the linear gauge 13, dial gauge 14, rotary encoder 23 in the storage means in accordance with the input command signal is provided. By storing the output signals of the various sensors when moving to the storage means, the output signals of the sensors at each measurement position are stored. For example, after all measurements are completed, the output signals are stored in the storage means. It is also possible to perform various calculations based on the output signal.

Furthermore, an arithmetic means for performing predetermined arithmetic processing is provided, and when the probe 3 moves to a target position, the output signals of various sensors are taken in, and based on the output signals of the sensors, for example, the center position of the circulation groove 6A It is also possible to configure to automatically perform various calculation processes such as coordinate calculation or pitch calculation.
In the above embodiment, the case where the ball screw nut 6 is rotatably supported by the nut support mechanism 7 has been described. However, the present invention is not limited to this. For example, the nut support mechanism 7 is configured to be non-rotatable. On the measuring instrument support mechanism 5 side, the measuring element 3 can be further rotatably supported.

  In the above embodiment, the case where the Y-axis direction is fixed and the displacement in the X-axis direction and the Z-axis direction is detected has been described. However, the present invention is not limited to this. For example, the Z-axis direction is fixed and the X-axis direction is fixed. It is also possible to detect the displacement in the direction and the Y-axis direction. In this case, the position of the end of the ball screw nut 6 in the Y-axis direction is searched as the Z-axis center, the Z-axis direction is fixed to the Z-axis center position, and the Y-axis direction position is adjusted. A configuration in which the depth of the groove is measured is also possible.

Next, a second embodiment of the present invention will be described.
Since the second embodiment is the same as the first embodiment except that the shape of the probe 3 is different, the same reference numerals are given to the same parts, and detailed description thereof is omitted.
As shown in FIG. 6, the measuring element 3a according to the second embodiment has a circulation groove convex shape that fits with a circulation groove 6A formed as a recess that forms a ball return path on the inner periphery of the ball screw nut 6. have. 6A is a top view of the measuring instrument 4 provided with the measuring element 3a, and FIG. 6B is a perspective view thereof.

Next, a measurement procedure using the measuring apparatus 1 provided with the measuring element 3a of FIGS. 6 (a) and 6 (b) will be described.
First, the ball screw nut 6 to be measured is mounted on the chuck mechanism 21a via the measuring jig 31 in the same procedure as in the first embodiment, and the center in the Y direction is set in the same procedure as in the first embodiment. And the Y-axis direction is fixed in the XYZ table 12.
Next, the probe 3a is moved in the X-axis direction, and the probe 3a is brought into contact with the inner periphery of the opening 31a of the measurement jig 31, as shown in FIG. The initial position in the Z-axis direction. Then, the dial gauge 14 is zeroed in a state where the probe 3a is at the initial value in the Z-axis direction.

Next, the probe 3a is moved in the X-axis direction, and the tip of the measuring instrument 4 is moved to a position where the tip of the ball screw nut 6 abuts against the end face of the measuring instrument support mechanism 5 side. The position in the X-axis direction at this time is set as the initial position in the X-axis direction.
As described above, measurement is possible.
Here, in the measuring apparatus 1 according to the second embodiment provided with the measuring element 3a having the convex shape of the circulation groove, the pitch, position, phase, and depth of the circulation groove 6A can be measured.

  First, by operating the XYZ table 12 and the rotary table 22, the measuring element 3a is moved to a position facing the S-shaped circulation groove 6A, and the measuring element 3a and the circulation groove 6A are aligned and measured. The child 3a is moved to a position that fits in the circulation groove 6A. The position at which the probe 3a fits in the circulation groove 6A is the position of the circulation groove 6A. At this time, the rotary signal output of the rotary encoder 23, the linear signal output of the linear gauge 13, and the dial gauge output of the dial gauge 14 Are obtained as position information of the circulation groove 6A. And the position coordinate of the circulation groove 6A on the basis of the measurement standard set to the ball screw nut 6 is acquired from this position information.

  In the same procedure, the position where the measuring element 3a fits with the circulation groove 6A is searched for the other circulation groove 6A. At this time, the rotary signal output of the rotary encoder 23, the linear signal output of the linear gauge 13, and the dial gauge 14 The dial gauge output is acquired as position information of the circulation groove 6A, and based on this, position coordinates based on the measurement standard set for the ball screw nut 6 are acquired.

Further, the pitch of the circulation grooves 6A can be obtained by taking the difference in the position coordinates of the adjacent circulation grooves 6A. Further, the phase of the circulation groove 6A can be detected by obtaining the phase difference between the position coordinates of each circulation groove 6A and the measurement standard of the ball screw nut 6.
Further, the depth of the circulation groove 6A can be detected by obtaining the dial gauge output of the dial gauge 14 when the measuring element 3a is fitted in the circulation groove 6A.
Here, as shown in FIGS. 6A and 6B, the measuring element 3a has a convex shape of the circulation groove that fits with the circulation groove 6A. For this reason, in the ball screw nut 6, the position coordinates of the circulation groove 6 </ b> A can be obtained by searching for the recess in which the measuring element 3 a is fitted and acquiring the position coordinates of the measuring element 3 a when fitting.

As described above, when the measuring element 3 is formed of one sphere as in the first embodiment, it is necessary to calculate the position coordinate of the intermediate position C from the position coordinates of both ends of the circulation groove 6A. . On the other hand, by making the measuring element 3a into the convex shape of the circulation groove, the position coordinates of the circulation groove 6A can be easily obtained by one measurement.
Therefore, it is possible to shorten the time required for measuring the circulation groove 6A.

  In the second embodiment, as shown in FIGS. 6 (a) and 6 (b), a case has been described in which the measuring element 3a has a convex shape of the circulation groove that fits with the circulation groove 6A. 7A and 7B, for example, a position corresponding to the longitudinal end of the circulation groove 6A formed as a recess that forms a ball return path on the inner periphery of the ball screw nut 6. Each may be provided with a sphere such as a steel ball, and the measuring element 3b made of these two spheres may be formed. Also in this case, since the measuring element 3b can be uniquely positioned with respect to the circulation groove 6A by fitting the two spheres into the circulation groove 6A, the same effect as described above can be obtained. 7A is a top view of the measuring instrument 4 having the measuring element 3b, and FIG. 7B is a perspective view thereof.

Next, a third embodiment of the present invention will be described.
In the third embodiment, the measuring element 3c is formed of a single body such as a steel ball having a larger diameter than a ball rolling in a spiral groove (not shown). The measuring element 3c may not be made of steel.
Here, when a single sphere having the same diameter as the rolling element is used as a measuring element as in the first embodiment, the groove shape of the circulation groove 6A has, for example, a single arc U-shaped cross section. In some cases, positioning is difficult. That is, in the case of a U-shaped cross section, the measuring element and the circulation groove come into contact with each other at one point. Therefore, it is necessary to search for the position where the deepest groove through which the rolling element actually passes and the measuring element come into contact. That is, it is necessary not only to insert the probe into the groove but also to search for a point where the probe is at the deepest position.

Therefore, in the third embodiment, the measuring element 3c made of one sphere is a sphere having a diameter larger than that of the rolling element, and the measuring element 3c is configured to contact at two points in the circulation groove 6A. The positioning can be performed only by inserting the probe 3c into the circulation groove 6A.
That is, as shown in FIG. 8A, the measuring element 3c in the third embodiment is formed of one sphere, and when the radius of the sphere is R1, the radius R1 is set to the circulation groove 6A. It is larger than the curvature radius R2 of the groove bottom (R1> R2).

Further, as shown in FIG. 8A, the diameter “2 × R1” of the measuring element 3c is larger than the distance d between the intersections of the extension line of the circulation groove side surface part 61 and the extension line of the circulation groove land part 62. In the case (R1> d / 2), as shown in FIG. 8 (b), when the sag of the groove shoulder 63 of the circulation groove 6A is asymmetrical, the probe 3c contacts the sag. In addition, there is a possibility that the center of the measuring element 3c and the center of the circulation groove do not match.
For this reason, it is preferable that R1 <d / 2.

  By using the measuring element 3c having such a configuration, the measuring element 3c comes into contact with the circulation groove 6A at a point. Therefore, positioning of the measuring element 3c in the circulation groove 6A becomes easy. Accordingly, it is possible to reduce the time required for the measurement and to reduce the measurement accuracy due to positioning error because there is no need to perform positioning in the circulation groove. Can be improved.

In the case of the third embodiment, the pitch, position, and phase of the circulation groove 6A can be measured in the same procedure as in the first embodiment. Similarly, the pitch and position of a spiral groove (not shown) can be measured.
In addition, here, the case of applying to the measuring element 3 composed of one sphere in the first embodiment has been described. However, as shown in FIG. 7, the measuring element 3b is composed of two spheres. Can also be applied.

Next, a fourth embodiment of the present invention will be described.
In the fourth embodiment, the connection accuracy of the connection portion between the circulation groove 6A and the spiral groove is measured. The circulation groove 6A is a U-shaped groove such as a U-shaped groove whose groove bottom is a single arc, and the spiral groove is a Gothic arch-shaped groove whose groove bottom is a non-single arc in the cross section.
The measuring apparatus 1 in the fourth embodiment includes a measuring instrument 4 having a measuring element 3 made of a sphere having the same diameter as the rolling element in the first embodiment, and a third embodiment shown in FIG. The measuring instrument 4 having the measuring element 3c made of a sphere having a diameter larger than that of the rolling element in the form is configured to be replaceable.

  When performing measurement, first, the probe 3 is moved to the vicinity of the connection portion M between the circulation groove 6A and the spiral groove using the probe 3. Then, the probe 3 is brought into contact with the bottom of the spiral groove to obtain the position coordinates of the probe 3. At this time, the spiral groove is a Gothic arch-like groove whose groove bottom is a non-single arc in the cross section, and the measuring element 3 contacts at two points in the spiral groove. Therefore, the measuring element 3 can be easily positioned. The position coordinates acquired in this way are set as the center position coordinates of the spiral groove in the connection portion M.

  Next, the measuring instrument 4 is replaced, and the measuring element 3c is moved to the vicinity of the connection portion M between the circulation groove 6A and the spiral groove, which is the same as described above, using the measuring element 3c. Then, the measuring element 3c is inserted into the groove of the circulation groove 6A, and the position coordinates at this point are obtained. This is the center position coordinate of the circulation groove 6A in the connection portion M. Here, since the circulation groove 6A is a U-shaped groove or the like having a single circular arc at the bottom in the cross section, the circulation groove 6A and the measurement element are used when the measurement element 3 made of a sphere having the same diameter as the rolling element is used. 3 will contact at one point, and it takes time to position. However, since the measurement of the circulating groove 6A is performed using the measuring element 3c, the circulating groove 6A and the measuring element 3c are in contact at two points. Therefore, the measuring element 3c can be easily positioned.

Next, an angle formed by a straight line passing through these two points and a plane perpendicular to the axis of the ball screw nut 6 from the center position coordinates of the spiral groove and the center position coordinates of the circulation groove 6A in the connecting portion M corresponds to the lead angle. Calculate as a value.
That is, as shown in FIG. 9, it is desirable that the spiral groove center line and the circulation path center line are connected to each other without being shifted as shown in FIG. The angle formed by the straight line passing through the spiral groove and the circulation groove 6A and the surface perpendicular to the axis of the ball screw nut 6 should be approximately equal to the lead angle.

  Therefore, the angle formed by the straight line passing through these two points and the plane perpendicular to the axis of the ball screw nut 6 is calculated from the center position coordinate of the spiral groove and the center position coordinate of the circulation groove 6A, and this is equivalent to the lead angle. By comparing this lead angle equivalent value with the design value of the lead angle, it is possible to detect the presence or absence of connection displacement between the circulation groove 6A and the spiral groove in the connection portion M, and take these differences. Thus, the degree of deviation can be measured.

By performing this operation for all the circulation grooves 6A, it is possible to measure the shift of the connection portion between the circulation groove 6A and the spiral groove at the connection portion of each circulation groove 6A.
Here, the case where the center position coordinate of the circulation groove 6A is measured after measuring the center position coordinate of the spiral groove has been described here. However, after the center position coordinate of the circulation groove 6A is measured, the center position coordinate of the spiral groove is measured. Can be measured, and the measurement order can be arbitrarily set.

  In the above embodiment, the spiral groove is measured using the probe 3 and the circulation groove 6A is measured using the probe 3c. However, the spiral groove has a single circular arc in the cross section. In the case of a U-shaped groove or the like, if the spiral groove is measured using the probe 3c, the time required for positioning the probe can be shortened in the same manner. Moreover, it is also possible to measure the displacement of the connecting portion between the spiral groove and the circulation groove 6A using only the measuring element 3c regardless of the groove shape of the spiral groove.

Next, a fifth embodiment of the present invention will be described.
In the fifth embodiment, the deformation of the shape of the circulation groove 6A is measured.
The measuring apparatus 1 according to the fifth embodiment replaces a measuring instrument 4 having one spherical measuring element 3d and a measuring instrument 4 having a spherical measuring element 3e having a diameter different from that of the measuring element 3d. To measure.

The measuring elements 3d and 3e are formed to have the same characteristics as those of the third embodiment. That is, the radii of the measuring elements 3d and 3e are larger than the curvature radii of the circulation groove bottoms, respectively, and the radii of the measuring elements 3d and 3e are between the intersections of the circulation groove side surface extension line and the circulation groove land part extension line. It is set to be smaller than a half value of the distance.
When measuring the collapse of the shape of the circulating groove 6A using the thus formed measuring elements 3d and 3e, first, one measuring element, for example, 3d, is used to move to an arbitrarily set measurement position of the circulating groove 6A. The measuring element 3d is inserted into the circulation groove 6A and positioned. Then, the linear signal output of the linear gauge 13, the rotary signal output of the rotary encoder 23, and the dial gauge output of the dial gauge 14 at this position are acquired as the position coordinates of the measuring element 3d.

  Next, switching to the measuring element 3e, the measuring element 3e is moved to the same position as the measurement position, and the measuring element 3e is inserted into the circulation groove 6A and positioned at this position. Then, the linear signal output of the linear gauge 13, the rotary signal output of the rotary encoder 23, and the dial gauge output of the dial gauge 14 at this position are acquired as the position coordinates of the probe 3 e.

Here, although the measuring elements 3d and 3e are spheres having different diameters, the position coordinates are measured at the same position of the circulation groove 6A. If the circulation groove 6A is left-right symmetric, as shown in FIG. 10, when measurement is performed with the measuring element moved to the same position, the straight line connecting the center positions of the spherical measuring elements 3d and 3e is L1 And the direction along the diameter of the shaft of the ball screw nut 6. On the other hand, when the circulation groove 6A is asymmetrical, even if the measurement is performed by moving the measurement probe to the same position, the measurement probe is positioned with respect to the circulation groove 6A as shown in FIG. As described above, since the positioning is performed with an inclination, the straight line L2 connecting the center positions of the spherical measuring elements 3d and 3e is not in the direction along the diameter of the ball screw nut 6 but is inclined.
Therefore, by detecting a straight line connecting the center positions of the measuring elements 3d and 3e at the same position of the circulation groove 6A, it is possible to measure whether the circulation groove 6A is symmetric.

The slope of the straight line connecting the center positions of the measuring elements 3d and 3e can be obtained from the position coordinates of the measuring element 3d and the position coordinates of the measuring element 3e measured at the same position of the circulation groove 6A. Then, based on the coordinates of the center positions of the measuring elements 3d and 3e, a straight line passing through these center positions is calculated, and whether or not this straight line is a direction along the diameter of the ball screw nut 6 in the design, That is, by calculating the angle formed by the straight line perpendicular to the axis of the ball screw nut 6, it is possible to easily measure whether or not the circulation groove 6 </ b> A is bilaterally symmetric, that is, whether or not the shape is broken. Can do.
Further, at this time, the common of these measuring elements is determined from the angle formed by the straight line passing through the center position of each measuring element and the straight line orthogonal to the axis of the ball screw nut 6 and the position coordinates and diameter of the center position of each measuring element. By calculating the tangent, the inclination of the common tangent to the axis of the ball screw nut 6 can also be measured as the inclination of the circulation groove side surface.

Next, a sixth embodiment of the present invention will be described.
Since the sixth embodiment is the same as the first embodiment except that the shape of the probe 3 is different, the same reference numerals are given to the same parts, and detailed description thereof is omitted.
The measuring element 3f in the sixth embodiment has a cylindrical shape or a cylindrical shape having a rectangular parallelepiped shape and a curved surface having two adjacent corners as arcs as shown in FIG. Hereinafter, the term “substantially cylindrical” includes a cylinder and a rectangular parallelepiped shape in which a part thereof has a curved surface.

  The measuring element 3 is scanned so that the axial direction of the substantially cylindrical shape coincides with the longitudinal direction of the spiral groove and the circulation groove 6A. The length of the substantially cylindrical shape in the axial direction is set to a length that allows scanning with the measuring element 3f in contact with the bottom of the S-shaped circulation groove 6A. Further, the measuring element 3f is positioned at a position where the rolling element contacts in the spiral groove, that is, an angle of a position where the rolling element contacts based on the lowermost part of the ball screw nut 6 as shown in FIG. It is also in contact with the spiral groove in the vicinity. That is, as shown in FIG. 11, when the radius of curvature of the spiral groove is r1 and the radius of curvature of the curved surface of the substantially cylindrical measuring element 3f is r2, r2 <r1 is satisfied. Further, as shown in FIG. 11, when the width of the substantially cylindrical measuring element 3f is D, it is set so as to satisfy D <2 × r1.

Further, as described above, the rolling element moves in the spiral groove while contacting the spiral groove with a certain contact angle. Further, as described in the fourth embodiment, it is desirable that the spiral groove and the circulation groove 6A be connected without deviation between the spiral groove center line and the circulation groove center line. Therefore, it is desirable that the measuring element 3f is in contact with the spiral groove at a position corresponding to the contact position with the spiral groove 6A. Therefore, the contact angle of the measuring element 3f is set so as to satisfy the above-described conditions.
Thus, by making the measuring element 3f into a substantially cylindrical shape, the measuring element 3f comes into contact at two points in the spiral groove or the circulation groove. For this reason, the measuring element 3f can be uniquely positioned in the spiral groove or the circulation groove. Therefore, measurement accuracy can be improved.

Note that the measuring device 1 in the sixth embodiment can measure the pitch, position, phase, and depth of the circulation groove 6A in the same manner as the measuring device 1 in the above embodiment. Moreover, about a spiral groove, the pitch, a position, and roundness can be measured. Further, the step and displacement between the circulation groove and the spiral groove can be measured. The measurement method is the same as the measurement method in the first embodiment.
In the sixth embodiment, the contact position of the measuring element is the same in the circulation groove and the spiral groove. However, the first embodiment, the third embodiment, and the fifth embodiment are implemented. Also in this form, it is desirable to determine the shape of the measuring element so that the contact position of the measuring element of the circulation groove and the spiral groove becomes an equivalent position.

Next, a seventh embodiment of the present invention will be described.
In the seventh embodiment, the locus of the groove center of the substantially S-shaped circulation groove 6A is measured.
The measuring device 1 in the seventh embodiment is the same as the measuring device 1 in the first embodiment. In the first embodiment, the measuring element 3 is formed of one steel ball having the same diameter as a rolling element that rolls in a spiral groove (not shown). However, in the measuring apparatus 1 in the seventh embodiment, As shown in the third embodiment, even a probe 3c formed of one steel ball having a diameter larger than that of the rolling element can be applied, and the sphere having a diameter larger than that of the rolling element. Is preferably used.
Note that the probe 3, 3c is preferably a cemented carbide in order to prevent a decrease in measurement accuracy due to wear of the probe.

Next, a method for measuring the trajectory of the groove center of the circulation groove 6A shown in FIG.
First, the ball screw nut 6 to be measured is mounted on the chuck mechanism 21a via the measuring jig 31 in the same procedure as in the first embodiment, adjusted to the initial position, and then the Y axis on the XYZ table 12 is adjusted. Fix the direction so that measurement is possible.
From this state, the XYZ table 12 is operated to adjust the X-axis direction, and the rotary table 22 is operated, so that the probe 3 is moved to one of the end portions A and B of the S-shaped circulation groove 6A. On the other hand, for example, it is moved to the vicinity of the position facing the end A, and the measuring element 3 is adjusted so as to contact the groove bottom of the circulation groove 6A. Then, the position of the end portion A of the circulation groove 6A is searched in the same procedure as in the first embodiment. That is, the ball screw nut 6 is rotated, the position when the movement of the probe 3 is restricted is searched, and this position is acquired as position information of the end A of the circulation groove 6A.

In this manner, the probe 3 is moved to the end A, and the probe 3 is kept in contact with the groove bottom of the circulation groove 6A while the probe 3 is in contact with the groove bottom of the circulation groove 6A. When the rotary table 22 is rotated, the probe 3 is guided and moved by the circulation groove 6A as the ball screw nut 6 rotates.
A rotary signal output of the rotary encoder 23, a linear signal output of the linear gauge 13, and a dial gauge signal output of the dial gauge 14 are obtained at each point of the tracing stylus 3 guided and moved by the circulation groove 6A.

When the probe 3 reaches the end B of the circulation groove 6A, that is, when the movement of the probe 3 is restricted, the end B is reached. At this time, the rotation of the ball screw nut 6 is stopped. To complete the measurement.
Then, from the position information at each point of the measuring element 3 when the measuring element 3 moves from the end A to the end B of the circulation groove 6A, for example, the measuring element based on the measurement standard set in the ball screw nut 6 The position coordinates at each point in the XYZ coordinates of 3 are obtained, and the locus of the groove center of the circulation groove 6A is calculated based on this. That is, when the rotation angle of the rotary table 22 is θ, the rotation angle θ of the rotary table obtained from the rotary signal output of the rotary encoder 23, the linear signal output of the linear gauge 13, and the dial gauge signal output of the dial gauge 14, 3 can obtain position coordinates (θ, X, Z) from displacements in the X-axis and Z-axis directions, and the movement trajectory of the probe 3 can be calculated from the position coordinates. The locus of the groove center can be calculated.

In this way, the detection signals of the rotary encoder 23, the linear gauge 13 and the dial gauge 14 when the rotary table 22 is operated to rotate the ball screw nut 6 to move the probe 3 along the circulation groove 6A. By acquiring, the locus of the groove center of the circulation groove 6A can be easily measured based on these detection signals.
When measuring the locus of the groove center of the circulation groove 6A, for example, a weight (weight), an air pressure, etc., for example, should be biased by a method in which the biasing force (measurement pressure) is constant in order to maintain measurement accuracy. For example, an urging force is applied to the measuring element 3 to press the measuring element 3 against the groove bottom of the circulating groove 6A so that the measuring element 3 moves while the measuring element 3 is in contact with the groove bottom of the circulating groove 6A. It may be.

Further, when the measuring element 3c having a diameter larger than that of the rolling element is used as the measuring element, the measuring element 3c may be moved while being in contact at two points in the circulation groove 6A.
When the measuring element 3c having a diameter larger than that of the rolling element is used as the measuring element, the measuring element 3c moves while being in contact at two points in the circulating groove 6A. Therefore, the circulating groove 6A and the measuring element 3c are different from each other. Touch at a point. Therefore, positioning of the measuring element 3c in the circulation groove 6A becomes easy. As a result, it is possible to shorten the time required for measurement and to suppress a decrease in measurement accuracy due to positioning errors.

Further, since the measuring element 3c is in contact with the circulation groove 6A at two points, even if the cross-sectional shape of the circulation groove 6A is not subject to right and left in the cross section perpendicular to the traveling direction of the rolling element, the rolling element It is possible to detect the position at which the passage of the groove is predicted, that is, the groove center.
In the seventh embodiment, the case where the groove center of the circulation groove 6A is measured has been described. However, the present invention is not limited to this. For example, the groove center of a spiral groove (not shown) is measured in the same procedure. It is also possible.

  In each of the above embodiments, the case of measuring the ball screw nut 6 has been described. However, the present invention is applicable even when only one of the circulation groove and the spiral groove is provided. be able to. Moreover, it is possible to measure not only a ball screw nut but also a ball screw shaft, and the present invention can be applied even when a circulation groove and a spiral groove are formed on the ball screw shaft. When measuring the ball screw shaft, it is configured to scan the probe along the outer periphery of the ball screw shaft, and in the nut support mechanism, the ball screw shaft is replaced with the ball screw nut. What is necessary is just to comprise so that it may rotatably support. Each of the above embodiments is suitable for measurement of a ball screw nut, particularly when the circulation groove is formed on the ball screw nut, and when the circulation groove is formed on the ball screw shaft, Suitable for axis measurement.

  In the second to seventh embodiments, drive control means for moving the XYZ table 12 and the rotary table 22 by the amount of movement corresponding to the input command signal is provided, and various measuring elements and ball screw nuts 6 are provided. By inputting a command signal corresponding to a target movement amount, the XYZ table 12 is automatically moved in the respective XYZ axes, and the rotary table 22 is driven to rotate. It can also be configured to automatically move to the position to be measured. That is, in each of the above-described embodiments, except when the ball screw nut 6 to be measured is mounted on the chuck mechanism 21a and when the probe is positioned so as to contact the inner periphery of the ball screw nut 6 to be measured. It is also possible to configure so that the measurement of the shape of each part of the ball screw nut can be performed automatically.

At that time, it is also possible to perform fine adjustment manually in each step. When fine adjustment is performed in the middle of each process, the reference point of the position coordinates and the like are shifted. Therefore, the position information acquired by automatic measurement may be configured to adjust the displacement associated with manual fine adjustment.
In each of the above embodiments, the circulation groove may be formed by forging, for example, and the spiral groove of the ball screw nut is, for example, a spiral groove as described in JP-A-2008-281063. What is necessary is just to revolve and cut the tool which has the cutter of the shape corresponding to to, revolving. The ball material of the ball screw nut 6 is a steel material SCM420H defined in Japanese Industrial Standard JIS G4052 when the heat treatment after the formation of the spiral groove and the circulation groove is carburizing. Carbon steel (S53C or the like) or SAE4150 or the like is preferable.

  Moreover, the present invention can be combined with the above-described embodiments. That is, it is possible to combine one or more according to the measurement purpose. As described above, since the measuring device in each embodiment differs only in the measuring element, the measuring device 4 that holds the measuring element has a common shape, and the measuring element suitable for this is held according to the measurement purpose. It can be easily realized by changing to the measuring device 4.

  In the above embodiment, the nut support mechanism 7 corresponds to the first support means, the measuring instrument support mechanism 5 corresponds to the second support means, the linear gauge 13 corresponds to the axial displacement detection means, The dial gauge 14 corresponds to the radial direction displacement detection means, and the rotary encoder 23 corresponds to the circumferential direction displacement detection means. The measuring element 3 corresponds to the first measuring element, the measuring element 3c corresponds to the second measuring element, and the measuring elements 3d and 3e correspond to the third measuring element and the fourth measuring element. Yes.

DESCRIPTION OF SYMBOLS 1 Measuring apparatus 3 Measuring element 4 Measuring instrument 5 Measuring instrument support mechanism 7 Nut support mechanism 12 XYZ table 13 Linear gauge 14 Dial gauge 21a Chuck mechanism 22 Rotary table 23 Rotary encoder

Claims (23)

A ball screw measuring device for measuring the ball screw by moving a probe along a groove formed in a ball screw shaft or a ball screw nut constituting the ball screw,
First support means for supporting the ball screw shaft or the ball screw nut as a measurement object;
Second support means for supporting the measuring element,
The first support means and the second support means support the measurement object and the measuring element so as to be relatively movable along an axis of the measurement object, and relatively move in a radial direction of the measurement object. Supported in such a manner that it can be relatively moved in the circumferential direction around the measurement target axis
Furthermore, an axial displacement detection means for detecting a relative displacement in a direction along the axis of the measurement object between the measurement object and the measuring element,
Radial displacement detecting means for detecting the relative displacement in the radial direction;
A ball screw measuring device comprising: a circumferential displacement detecting means for detecting a relative displacement in the circumferential direction.   2. The ball screw measuring device according to claim 1, wherein the measuring element is a single sphere having the same diameter as a rolling sphere that rolls in the groove. The groove is a circulation groove that is formed integrally with the ball screw shaft or the ball screw nut and includes a recess that forms a ball return path,
The ball screw measuring device according to claim 1, wherein the measuring element is a fitting member that is fitted into the concave portion of the circulation groove and is positioned in the circulation groove.   4. The ball screw measuring device according to claim 3, wherein the measuring element has the same shape as the concave portion of the circulation groove and has a convex shape of the circulation groove fitted to the circulation groove.   4. The ball screw measuring device according to claim 3, wherein the measuring element is two spheres, and the two spheres are fitted to the circulation groove in a state of being opposed to both longitudinal ends of the circulation groove. . The measuring element has an arc portion having a diameter larger than the diameter of a rolling sphere that rolls in the groove,
The ball screw measuring device according to claim 1, wherein the arc portion of the measuring element and the groove are in contact with each other.   The ball screw measuring device according to claim 6, wherein the measuring element is a sphere having a diameter larger than a diameter of the rolling sphere.   The ball screw measuring device according to claim 7, wherein a diameter of the measuring element is smaller than an opening width of the groove.   The measuring element is a cylinder or a columnar member having a diameter larger than the diameter of the rolling sphere, and the cross-section of the columnar member is a rectangular shape in which two adjacent corners are arcs. The ball screw measuring device according to claim 6 or 7. The first support means supports the measurement object rotatably in the circumferential direction,
The said 2nd support means supports the said measuring element so that a movement along the said measurement object's axis | shaft and the said radial direction are possible, The any one of Claims 1-9 characterized by the above-mentioned. Ball screw measuring device. A measurement method for measuring the ball screw by moving a probe along a groove formed in a ball screw shaft or a ball screw nut constituting the ball screw,
Using the ball screw shaft or the ball screw nut as a measuring object, the measuring element is moved along the groove of the measuring object, and along the measuring object axis between the measuring object and the measuring element at this time Measuring the relative displacement in the direction, the relative displacement in the radial direction of the measurement object, and the relative displacement in the circumferential direction around the axis of the measurement object;
A ball screw measuring method, wherein the measurement object is measured based on these measured values. The groove is a circulation groove formed of a concave portion forming a ball return path, which is formed integrally with the ball screw shaft or the ball screw nut, and the measuring element is constituted by one sphere,
The position coordinates of both ends in the longitudinal direction of the circulation groove are measured using the probe, the position coordinates of the center of the circulation part are calculated from the position coordinates of the both ends, and the calculated position coordinates of the center are 12. The ball screw measuring method according to claim 11, wherein the position coordinates of the circulation groove are used. The groove is a circulation groove formed integrally with the ball screw shaft or the ball screw nut and including a recess that forms a ball return path, and the measuring element is fitted to the recess of the circulation groove and the circulation groove Composed of a fitting member positioned on
12. The ball screw measuring method according to claim 11, wherein a position coordinate of the measuring element when the measuring element is fitted to the circulating groove is a position coordinate of the circulating groove. Detecting the position coordinates of the circulation groove,
The phase of the circulation groove is measured from the phase difference between the position reference of the circulation groove and the position of the circulation groove based on the position coordinates of the circulation groove and a preset position reference of the circulation groove. The method for measuring a ball screw according to any one of claims 11 to 13. Detecting the position coordinates of the circulation groove,
15. The ball screw measuring method according to claim 11, wherein the depth of the circulation groove is measured by measuring the depth of the circulation groove at a position coordinate of the circulation groove. The probe is composed of one sphere,
While maintaining the state in which the probe is in contact with the groove of the measurement object, the measurement object is rotated in the circumferential direction around the axis of the measurement object,
Measuring each relative displacement of the probe moving along the groove of the measurement object as the measurement object rotates,
The ball screw measuring method according to claim 11, wherein a trajectory of the groove center of the groove to be measured is measured based on these measured values. The groove is a substantially S-shaped circulation groove that is formed integrally with the ball screw shaft or the ball screw nut and includes a recess that forms a ball return path,
Measuring each relative displacement of the probe moving from one end of the circulation groove to the other end along the circulation groove with the rotation of the measurement object;
The ball screw measuring method according to claim 16, wherein a trajectory of the groove center of the circulation groove is measured based on these measured values.   The groove is a spiral groove formed in a spiral shape and the circulation groove, the position coordinates of the center position in the width direction of the spiral groove in the connection portion between the spiral groove and the circulation groove, and the circulation groove in the connection portion. Measuring a position coordinate of the center position in the width direction, and detecting a straight line connecting the center position in the width direction of the spiral groove and the center position in the width direction of the circulation groove as a lead angle equivalent value based on the measured position coordinates, The ball screw measuring method according to claim 11, wherein a connection shift state between the spiral groove and the circulation groove is measured based on a lead angle equivalent value. The spiral groove is a groove whose groove bottom is a non-single arc in its cross section, and the circulation groove is a groove whose groove bottom is a single arc in its cross section,
When measuring the position coordinates of the center position in the width direction of the spiral groove, a first measuring element made of a sphere having the same diameter as a rolling sphere rolling the groove is used as the measuring element, and the width direction of the circulation groove 19. The ball screw measuring method according to claim 18, wherein when measuring the position coordinates of the center position, a second measuring element made of a sphere having a diameter larger than the diameter of the rolling sphere is used as the measuring element. . The position coordinates of an arbitrary measurement position of the groove are measured by using a third measuring element and a fourth measuring element having a diameter larger than the diameter of the rolling sphere rolling on the groove and having different diameters. And
Based on the measured position coordinates, a straight line connecting the center position of the sphere constituting the third measuring element and the center position of the sphere constituting the fourth measuring element is detected, and the straight line and the measurement object are detected. The angle formed by a straight line along the radial direction is detected, and based on the angle, it is measured whether the groove shape of the groove is bilaterally symmetric. The ball screw measuring method described in 1. The groove is a circulation groove composed of a recess that forms a ball return path,
The ball screw measurement according to claim 11, wherein the pitch, position, phase, depth, and groove shape of the circulation groove of the circulation groove are symmetrical to each other. Method. The groove is a spiral groove formed in a spiral shape,
The ball according to claim 11 or 21, wherein the pitch, the position, the roundness, and the groove shape of the spiral groove of the spiral groove are measured symmetrically. Thread measurement method. The groove is a circulation groove composed of a concave portion forming a ball return path and a spiral groove formed in a spiral shape,
The measurement of the ball screw according to any one of claims 11, 21, and 22, wherein any one of a step and a positional deviation of a connection portion between the circulation groove and the spiral groove is measured. Method.

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