JP4478278B2 - Ball screw inspection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ball screw inspection apparatus. More specifically, the present invention relates to a ball screw inspection device that inspects the accuracy of a ball screw used for moving a movable portion relative to a fixed portion.
[0002]
[Background]
A ball screw has a structure including a screw shaft having a thread groove formed on an outer peripheral surface thereof, and a nut provided on the screw groove of the screw shaft so as to be movable on the outer periphery of the screw shaft via a ball. It is widely used as a mechanism for smoothly moving the movable part relative to the fixed part.
Regarding the accuracy inspection of the ball screw, various accuracy inspection items are defined by JIS and ISO. In JIS, for example, “actual travel” “variation” “perpendicular angle of nut reference end face or flange mounting surface with respect to screw axis of screw shaft” “radial circumferential runout of nut outer surface with respect to screw shaft axis of screw shaft” "And other inspection items are specified.
[0003]
Conventionally, the accuracy check of the “actual movement amount” is, for example, according to JIS, because the actual axial movement amount of the nut with respect to an arbitrary screw shaft rotation angle must be obtained by continuous measurement. It was attached to a measurement carriage slidable in parallel, and the movement amount of the measurement carriage relative to the screw shaft rotation angle was measured to obtain the actual movement amount.
For example, according to JIS, the accuracy check for “variation” is the maximum width of the actual travel curve sandwiched between two straight lines parallel to the representative travel distance line. Corresponding to the effective length of the screw portion of the shaft, (2) Corresponding to any 300 mm between the effective length of the screw portion of the screw shaft, (3) Between the effective length of the screw portion of the screw shaft Three items are defined: one corresponding to one arbitrary rotation (2πrad) taken.
[0004]
On the other hand, use a jig to check the accuracy of the "straight angle of the nut reference end face or flange mounting surface with respect to the screw shaft axis of the screw shaft" or "the radial runout of the nut outer peripheral surface with respect to the screw shaft axis of the screw shaft". It was done manually.
That is, the accuracy inspection of “the perpendicularity of the nut reference end face or flange mounting surface with respect to the screw shaft axis of the screw shaft” is performed with a V-block or the like at a position twice the screw shaft nominal diameter (2 do) from the nut end faces. Fix the nut reference end face or flange mounting surface, measure the maximum value of runout T when the nut is rotated once, and measure this value on the nut reference end face or flange mounting face with respect to the thread axis of the screw shaft. It was calculated as a squareness.
In addition, the accuracy test of “radial circumferential runout of the nut outer surface relative to the screw axis of the screw shaft” is performed by fixing the screw shaft from the both end surfaces of the nut at a position twice the nominal diameter of the screw shaft (2 do). The maximum value of the runout U when the nut is rotated once by placing a probe on the outer circumferential surface was measured and obtained as the circumferential runout in the radial direction of the nut outer circumferential surface with respect to the screw portion axis of the screw shaft.
[0005]
[Problems to be solved by the invention]
The conventional ball screw accuracy inspection method has the following problems.
In the accuracy inspection of "actual travel" and "variation", measurement of the bending (twisting) of the screw shaft, runout of the screw shaft axis, perpendicularity of the nut reference surface or flange surface, radial runout of the nut outer peripheral surface, etc. In addition to error factors, the movement of the nut has a tolerance in straightness, and also has a combined movement of pitching and yawing with respect to the screw shaft axis. For this reason, an error is caused by the principle of Appe, mechanical hysteresis, elastic deformation, etc., and an accurate measurement result cannot be obtained.
[0006]
In addition, a jig is used in the accuracy inspection of “the perpendicularity of the nut reference end surface or flange mounting surface with respect to the screw shaft axis of the screw shaft” and “the radial runout of the nut outer peripheral surface with respect to the screw shaft axis of the screw shaft”. Since it was performed manually, a dedicated worker was required, and there were problems such as variations in measurement positions, reading errors of measuring instruments, and individual errors depending on the worker, resulting in low inspection reliability.
[0007]
The object of the present invention is to eliminate the problems of the conventional inspection method, and in the “actual movement amount” and “variation” measurement, the screw shaft is bent (twisted), the screw shaft is shaken, the nut reference surface or the flange surface. To provide a ball screw inspection device that eliminates the effects of the perpendicularity of the nut and the circumferential runout of the nut outer peripheral surface, and provides accurate measurement results, which can greatly improve the reliability of measurement and inspection. It is in.
Another object of the present invention is to check the accuracy of “perpendicularity of nut reference surface or flange mounting surface with respect to screw axis of screw shaft” and “circumferential circumference of nut outer surface with respect to screw shaft axis of screw shaft”. Ball screw inspection that can greatly improve the reliability of inspection by eliminating the variation of measurement position, measuring instrument reading error, and personal error by enabling automatic inspection of the accuracy of “runout”. To provide an apparatus.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the ball screw inspection apparatus of the present invention employs the following configuration.
A ball screw inspection apparatus according to the present invention is a ball screw inspection apparatus for inspecting the accuracy of a ball screw having a screw shaft and a nut coupled to the screw shaft via a ball, the rotation rotating the screw shaft. A linear movement mechanism having a driving means and a measurement carriage, and holding the measurement carriage so as to be movable in a direction parallel to the screw shaft axis; one end connected to the nut via an alignment means; and the other end A connecting member connected to the measuring carriage; angle detecting means for detecting a rotation angle of the screw shaft; and length measuring means for measuring a moving distance of the measuring carriage; and the aligning means includes the nut And a second member provided so as to be rotatable about the first axis perpendicular to the screw shaft axis and movable in the first axis direction with respect to the first member. And this second The member is pivotable about a second axis perpendicular to the screw axis and the first axis, and is movable in the second axis direction, and is coupled to the measurement carriage via the connecting member. A third member; and a fourth member coupled to the third member and coupled to the measurement carriage via the coupling member. The first member is the screw shaft. A perpendicularity detector for detecting a perpendicularity of the end face with respect to the screw axis from the position of the end face of the first member in the screw axis direction; It is attached, It is characterized by the above-mentioned.
[0009]
According to this configuration, when the accuracy of the ball screw is checked, when the screw shaft is rotated by the rotation driving means, the nut is moved in the axial direction of the screw shaft. Then, since the measuring carriage of the linear movement mechanism is also moved through the connecting member, the moving distance of the measuring carriage is measured by the length measuring means, and the rotation angle of the screw shaft detected by the length measuring data and the angle detecting means. The “actual movement amount” is obtained from the data. Furthermore, each item of “variation” ((1) (2) and (3) described above) can be obtained from the “actual movement amount”.
At this time, the nut is orthogonal to the screw shaft axis and the first axis, respectively, the second member provided so as to be rotatable about the first axis perpendicular to the screw axis and movable in the first axis direction. Since it is connected to the measurement carriage via the aligning means having the third member provided so as to be rotatable about the second axis and movable in the second axis direction, and the connecting member, the screw shaft Accurate measurement results can be obtained without being affected by bending (twisting), runout of the screw shaft axis, perpendicularity of the nut reference surface or flange surface, radial runout of the nut outer peripheral surface, and the like. Therefore, the reliability of measurement and inspection can be greatly improved.
In addition, since a squareness detector that detects the squareness of the end face with respect to the screw axis axis from the position of the end face of the first member in the screw axis axis direction is provided, The accuracy inspection of the “perpendicularity of the end surface or the flange mounting surface” can be performed at the same time. Therefore, it is possible to eliminate variations in measurement positions by the operator, reading errors of measuring instruments, and individual errors, and the reliability of inspection can be greatly improved.
[0010]
In the ball screw inspection apparatus of the present invention, a displacement detector that detects a movement amount of the second member in the first axis direction and a movement amount of the third member in the second axis direction, respectively, and the second detector it is preferable that a rotation angle detector for detecting rotational angle about the second axis of rotation angle and the third member about the first axis of the member, respectively.
According to this configuration, it is possible to automatically inspect the accuracy of “circular runout of the nut outer peripheral surface relative to the screw shaft axis of the screw shaft”. Personal errors can be eliminated, and the reliability of inspection can be greatly improved.
[0012]
In the ball screw inspection apparatus of the present invention, a rotating means for rotating the third member about the screw axis is provided between the third member and the fourth member . It is preferable .
According to this configuration, since the rotation member that rotates the third member about the screw shaft axis is provided, “the perpendicularity of the nut reference surface or the flange mounting surface with respect to the screw portion axis of the screw shaft” Accuracy inspection can be performed automatically.
[0013]
In the ball screw inspection apparatus of the present invention , the linear movement mechanism includes a rail provided in parallel with the screw shaft axis, and a measurement carriage provided to be movable with respect to the rail via an air bearing. It is preferable to be configured.
According to this configuration, since the measurement carriage moves on the rail via the air bearing, the frictional resistance is small, and the resistance during movement of the nut is small. Therefore, more accurate measurement can be expected.
[0014]
In the ball screw inspection apparatus of the present invention , the length measuring means emits laser light to the reflector from the reflector provided on the measurement carriage and the screw shaft axis direction, and receives reflected light from the reflector. which is preferably configured to include a laser measurement device determining the distance to the reflector Te.
According to this configuration, since the position of the measurement carriage is detected by the laser length measuring device, the position of the measurement carriage can be measured with high accuracy.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
(overall structure)
FIG. 1 shows the overall configuration of the ball screw inspection apparatus of the present embodiment. The ball screw inspection apparatus is a ball screw inspection apparatus for inspecting the accuracy of a ball screw 3 having a screw shaft 1 and a nut 2 coupled to the screw shaft 1 via a ball (not shown). Rotation drive means 10 for rotating the screw shaft 1, a linear movement mechanism 20 having a measurement carriage 22 and holding the measurement carriage 22 so as to be movable in a direction parallel to the screw shaft axis (ZZ ′ axis), and one end Is connected to the nut 2 via a centering means 60 and the other end is connected to the measurement carriage 22, an angle detection means 30 for detecting the rotation angle of the screw shaft 1, and the measurement carriage 22 is provided with a length measuring means 40 for measuring the moving distance of 22 and a computer 50 as a calculating means.
[0016]
(Description of each component)
The rotation driving means 10 is connected to a head stock 11 and a tail stock 12 that rotatably support both ends of the screw shaft 1, and a power transmission band 13 such as a belt, and the screw shaft 1 is connected to the head stock 11. And a drive motor 14 to be rotated.
The linear movement mechanism 20 includes a rail 21 provided in parallel with the screw shaft axis (ZZ ′ axis), and a measurement provided to the rail 21 through an air bearing (not shown). And a carriage 22.
[0017]
The angle detection means 30 includes a rotary encoder 31 that is coaxially mounted with the head stock 11 and a counter 32 that counts pulses from the encoder 31.
The length measuring means 40 emits laser light to the reflector 41 from the reflector 41 provided on the measurement carriage 22 and the screw shaft axis (ZZ ′ axis) direction, and is reflected from the reflector 41. It includes a laser length measuring device 42 that receives light and determines the distance to the reflector 41, and a counter 43 that counts pulses from the laser length measuring device 42.
The computer 50 performs various accuracy inspection measurements based on the rotation angle data from the angle detection means 30 and the length measurement data from the length measurement means 40.
The aligning means 60 is configured as follows.
[0018]
(Detailed structure of alignment means)
2 to 5 show the detailed structure of the aligning means 60. 2 is an overall perspective view, FIG. 3 is a sectional view taken along line III-III in FIG. 2, FIG. 4 is a sectional view taken along line IV-IV in FIG. 2, and FIG.
The aligning means 60 includes a first member 71 to which the nut 2 is attached via a nut attachment plate 61, and is orthogonal to the screw shaft axis (ZZ ′ axis) with respect to the first member 71. A second member 81 provided so as to be rotatable about the first axis (XX ′ axis) and movable in the first axis direction, and the screw shaft axis (Z -Z 'axis) and can rotate around the second axis (YY' axis) orthogonal to the first axis (X-X 'axis) and move in the direction of the second axis (YY' axis) A third member 91 that can be provided, and a third member 91 that is coupled to the third member 91 via a bearing 98 and a stepping motor 99 as a rotating means, and coupled to the measurement carriage 22 via the coupling member 23. The fourth member 101 is included.
[0019]
The nut mounting plate 61 has a rectangular plate shape, a through hole 62 through which the main body 2A of the nut 2 is inserted at the center, four screw holes 63 at four positions on the outer periphery of the through hole 62, and an outer side thereof. Two screw insertion holes 65 through which the fixing screws 64 are inserted are formed in two places.
The first member 71 includes a flange portion 72 having an end surface 72A orthogonal to the screw shaft axis (ZZ ′ axis), a cylindrical portion 73 integrally formed at the center of the flange portion 72, and And a through hole 74 penetrating through the center. The flange portion 72 is formed with a screw hole 76 into which the tip of the fixing screw 64 inserted through the screw insertion hole 65 of the nut mounting plate 61 is screwed. Accordingly, the flange portion 2B of the nut 2 is fixed to the nut mounting plate 61 by the bolt 66, and the nut 2 is fixed to the first member 71 by the fixing screw 64, so that the nut 2 is the first member. 71 is fixed. The cylindrical portion 73 is formed with a through-hole 78 penetrating in a first axis (XX ′ axis) direction perpendicular to the screw axis (ZZ ′ axis), and these screw axis axes (Z A through hole 79 penetrating in the direction of the second axis (YY ′ axis) perpendicular to the −Z ′ axis and the first axis (XX ′ axis) is formed.
[0020]
The second member 81 is formed in a cylindrical shape that fits the cylindrical portion 73 of the first member 71 from the outside, and a pair of support shafts in a first axis (XX ′ axis) direction passing through the center thereof. 82A and 82B project and penetrate in the direction of the second axis (YY ′ axis) perpendicular to the screw axis (ZZ ′ axis) and the first axis (XX ′ axis). A through hole 83 is formed. The inner end portions of the respective support shafts 82A and 82B are inserted into the through holes 78 of the first member 71 via the linear ball guides 84. Accordingly, the second member 81 is provided so as to be rotatable about the first axis (XX ′ axis) and to be movable in the first axis (XX ′ axis) direction. Between one supporting shaft 82A and the first member 71, a displacement detector 85 that detects the movement of the second member 81 in the first axis (XX ′ axis) direction is provided. Between the other support shaft 82B and the first member 71, a rotation angle detector 86 that detects a rotation angle around the first axis (XX ′ axis) of the second member 81 is provided. Is provided.
[0021]
The third member 91 is formed in a cylindrical shape that covers the second member 81 from the outside, and a pair of support shafts 92A and 92B are provided in a second axis (YY ′ axis) direction passing through the center of the third member 91. Projected. The inner end portions of the respective support shafts 92A and 92B are inserted into the through holes 83 of the second member 81 through linear ball guides 94. Accordingly, the third member 91 is provided so as to be rotatable about the second axis (YY ′ axis) and movable in the second axis (YY ′ axis) direction. Between one support shaft 92A and the second member 81, there is provided a displacement detector 95 that detects the movement of the third member 91 in the second axis (YY ′ axis) direction. A rotation angle detector 96 that detects a rotation angle about the second axis (YY ′ axis) of the second member 81 is provided between the other support shaft 92B and the first member 71. Is provided. A spring 97 that biases the second member 81 upward is interposed between the second member 81 and the third member 91. The biasing force of the spring 97 is set so as to balance the weight of the second member 81, the first member 71, the nut mounting plate 61, and the nut 2.
[0022]
The fourth member 101 is formed in a cylindrical shape that covers the third member 91 from the outside, and the screw shaft axis (ZZ ′ axis) of the end surface 72A of the first member 71 is formed on the fourth member 101. A squareness detector 102 for detecting the position in the direction is attached. The perpendicularity detector 102 detects the angle of the end surface 72A with respect to the screw shaft axis (ZZ ′ axis) from the position of the end surface 72A of the first member 71 in the screw shaft axis (ZZ ′ axis) direction. . One end of the connecting member 23 is fixed to the back side of the fourth member 101 with a bolt or the like.
[0023]
(Function)
In measuring the “actual movement amount”, when the screw shaft 1 is rotated by the rotation driving means 10, the nut 2 is moved in the axial direction of the screw shaft 1. Then, since the measurement carriage 22 of the linear movement mechanism 20 is also moved through the connecting member 23, the movement distance of the measurement carriage 22 is measured by the length measuring means 40 and detected by the length measurement data and the angle detection means 30. The “actual movement amount” is obtained from the rotation angle data of the screw shaft 1.
For example, if the result shown in FIG. 6 is obtained by this “actual movement amount”, three items of “variation” from the actual movement amount curve, that is, (1) effective movement distance of the nut or screw portion of the screw shaft Corresponding to the effective length, (2) Corresponding to any 300mm taken between the effective length of the screw shaft, (3) Arbitrary taking between the effective length of the screw shaft One corresponding to one rotation (2π rad) can be obtained.
[0024]
The nut 2 is provided so as to be rotatable about a first axis (X-X 'axis) orthogonal to the screw axis (Z-Z' axis) and movable in the first axis (X-X 'axis) direction. The second member 81 can be rotated around the second axis (YY 'axis) orthogonal to the screw axis (ZZ' axis) and the first axis (XX 'axis). And since it is connected to the measuring carriage 22 via the alignment means 60 having the third member 91 provided so as to be movable in the second axis (YY ′ axis) direction, and the connecting member 23, Accurate measurement results can be obtained without being affected by bending (twisting) of the screw shaft 1, run-out of the screw shaft axis, perpendicularity of the nut reference surface or flange surface, radial run-out of the nut outer peripheral surface, etc. The reliability of measurement and inspection can be greatly improved.
[0025]
At this time, displacement detection is performed for the amount of movement of the second member 81 in the first axis (XX ′ axis) direction and the amount of movement of the third member 91 in the second axis (YY ′ axis) direction, respectively. By detecting with the devices 85 and 95, it is possible to automatically check the accuracy of “circular runout in the radial direction of the nut outer peripheral surface with respect to the screw axis of the screw shaft”.
Further, the first angle detector 102 provided on the fourth member 101 rotates the third member 91, the second member 81, and the first member 71 by driving the stepping motor 99, and thereby the first member 91 is rotated. If the position of the end surface 72A formed on the member 71 in the direction of the screw shaft axis (Z-Z 'axis) is detected, an accuracy check of "the perpendicularity of the nut reference surface or the flange mounting surface with respect to the screw shaft axis of the screw shaft" is performed. Can be done automatically.
Accordingly, it is possible to eliminate variations in measurement positions by the operator, reading errors of the measuring instrument, and individual errors, and the reliability of inspection can be greatly improved.
[0026]
(Effect of embodiment)
According to the above embodiment, the following effects can be expected in addition to the effects described in the “means for solving the problems” described above.
A spring 97 that biases the second member 81 upward is interposed between the second member 81 and the third member 91, and the biasing force of the spring 97 is applied to the second member 81 and the first member 81. Measurement is performed without being affected by the weights of the second member 81, the first member 71, the nut mounting plate 61, and the nut 2. Can be measured with higher accuracy.
[0027]
Further, since the inner end portions of the support shafts 82A and 82B are inserted into the through holes 78 of the first member 71 via the linear ball guide 84, the second member 81 is moved to the first axis (XX ′ axis). Can be smoothly rotated around the center, and can be moved with less resistance in the direction of the first axis (XX ′ axis). Similarly, since the inner end portions of the support shafts 92A and 92B are inserted into the through holes 83 of the second member 81 via the linear ball guide 94, the third member 91 is moved to the second axis (YY 'axis). ), And can be moved with less resistance in the direction of the second axis (YY ′ axis). This also assures highly accurate measurement.
[0028]
Note that the present invention is not limited to the configuration described in the above embodiment, and can be modified within the scope of the gist of the present invention.
For example, the length measuring means 40 is not limited to the laser length measuring device 42 but may be a capacitance length measuring device, a magnetic length measuring device, a photoelectric length measuring device, or the like.
Further, the aligning means 60 includes the first to fourth members 71, 81, 91, 101. However, the first to third members 71, 81, 91 may be used. Also about a shape, it is not restricted to the shape of the said embodiment, It can change suitably.
[0029]
【The invention's effect】
According to the ball screw inspection device of the present invention, in the “actual movement amount” and “variation” measurement, the screw shaft is bent (twisted), the shaft shaft is shaken, the perpendicularity of the nut reference surface or the flange surface, and the nut outer peripheral surface. It is possible to eliminate the influence of the circumferential runout in the radial direction, obtain an accurate measurement result, and greatly improve the reliability of measurement and inspection.
In addition, the accuracy inspection of the "perpendicular angle of the nut reference surface or flange mounting surface with respect to the screw shaft axis of the screw shaft" and the accuracy inspection of "radial circumferential runout of the nut outer surface with respect to the screw shaft axis of the screw shaft" are automatically performed. In this way, it is possible to eliminate variations in measurement positions by the operator, reading errors of the measuring instrument, and individual errors, and greatly improve the reliability of the inspection.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of a ball screw inspection apparatus of the present invention.
FIG. 2 is an exploded perspective view showing a detailed structure of the alignment means of the embodiment.
3 is a cross-sectional view taken along line III-III in FIG.
4 is a cross-sectional view taken along line IV-IV in FIG.
5 is a cross-sectional view taken along line VV in FIG.
FIG. 6 is a diagram showing an example of measurement results obtained by the apparatus of the present embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Screw shaft 2 Nut 3 Ball screw 10 Rotation drive means 20 Linear movement mechanism 21 Rail 22 Measuring carriage 23 Connecting member 30 Angle detector 40 Length measuring means 41 Reflector 42 Laser length measuring device 60 Centering means 71 First member 72A End surface 81 Second member 85 Displacement detector 86 Rotation angle detector 91 Third member 95 Displacement detector 96 Rotation angle detector 99 Stepping motor (rotation means)
102 detector

Claims (5)

A ball screw inspection device for inspecting the accuracy of a ball screw having a screw shaft and a nut coupled to the screw shaft via a ball,
Rotation drive means for rotating the screw shaft;
A linear movement mechanism having a measurement carriage and holding the measurement carriage movably in a direction parallel to the screw shaft axis;
A connecting member having one end connected to the nut via alignment means and the other end connected to the measurement carriage;
Angle detection means for detecting the rotation angle of the screw shaft;
A length measuring means for measuring the moving distance of the measurement carriage;
The aligning means is rotatable about a first member to which the nut is coupled and a first axis perpendicular to the screw shaft axis with respect to the first member, and is movable in the first axis direction. And a second member provided on the second member and rotatable relative to the second member about a second axis perpendicular to the screw axis and the first axis, and movable in the second axis direction. a third member, is configured to include a fourth member coupled to the measuring carriage via the coupling member while being connected to the third member,
The first member includes an end surface orthogonal to the screw shaft axis, and the fourth member includes a position of the end surface of the first member in a direction of the screw shaft axis from the position of the end surface directly to the screw shaft axis. A ball screw inspection device, wherein a squareness detector for detecting an angle is attached . The ball screw inspection apparatus according to claim 1,
A displacement detector for detecting the amount of movement of the second member in the first axis direction and the amount of movement of the third member in the second axis direction;
And a rotation angle detector for detecting a rotation angle around the first axis of the second member and a rotation angle around the second axis of the third member. Ball screw inspection device. In the ball screw inspection device according to claim 1 or 2 ,
A ball screw inspection device characterized in that a rotating means for rotating the third member about the screw shaft axis is provided between the third member and the fourth member. . In the ball screw inspection device according to any one of claims 1 to 3 ,
The linear movement mechanism includes a rail provided in parallel with the screw shaft axis, and a measurement carriage provided to be movable with respect to the rail via an air bearing. Ball screw inspection device. In the ball screw inspection apparatus according to any one of claims 1 to 4 ,
The length measuring means and a reflector provided on the measuring carriage and a laser measuring device for emitting a laser beam to the reflector from the axial direction of the screw shaft and receiving a reflected light from the reflector to obtain a distance to the reflector. A ball screw inspection apparatus comprising a length device.

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