JP2935211B2 - Spiral groove measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spiral groove measuring device for measuring a spiral groove such as a screw shaft.

[0002]

2. Description of the Related Art Conventionally, a measuring device for measuring the pitch of a spiral groove such as a feed screw shaft is supported by a compressed air blown out in a non-contact manner, and a measuring element is attached to a smooth sliding air slider. The probe is brought into contact with the spiral groove provided on the DUT with a certain load, and the amount of movement of the DUT in the axial direction of the DUT is optically read from the scale of a glass scale attached to an air slider, etc. Has become.
That is, when measuring the pitch of the spiral groove, the object to be measured is rotated by a fixed angle by a drive motor, and the measuring element is moved along the spiral groove to move the air slider in the axial direction of the object to be measured. The amount is read by a glass scale attached to the air steider, and the pitch of the spiral groove is determined from the amount of rotation of the measured object and the amount of movement of the air slider.

[0003]

However, in the above-described conventional measuring apparatus, the amount of movement of the tracing stylus is read by a glass scale provided on the air slider.
Since the place where the actual movement amount is read is separated from the tracing stylus, it is easily affected by errors due to rigidity problems such as bending of the tracing stylus. Moreover, in the conventional apparatus, it is difficult to make the object to be measured and the glass scale completely parallel to each other, and the two are separated from each other. Abbe's principle states that this can be ignored if the relative inclination between the object and the measured object is small, but cannot be ignored unless both are on a straight line.
Large measurement errors occur.

In the conventional measurement of a spiral groove, a master gauge is measured once prior to the measurement, and after confirming that a measuring device has a specified accuracy, an object to be measured is measured. Is a kind of comparative measurement. Moreover,
At present, the master gauge is not absolute but refers to a screw or the like made with extremely high accuracy as a master, and it is very difficult to obtain the absolute value of the pitch of the spiral groove. Further, in the conventional measurement, when measuring the fluctuation (so-called random walk) in the direction perpendicular to the axis of the object to be measured, it is not only necessary to use a completely different measuring device, but also to measure in the axial direction of the object to be measured. The relationship between the position of the object and the displacement in the direction perpendicular to the axis (shake of the object to be measured) cannot be obtained, and the judgment of what caused the pitch error or the shake depends on the experience of the operator. There were many.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks of the prior art, and has as its object to provide a spiral groove measuring apparatus capable of obtaining the relationship between the position of an object to be measured in the axial direction and the runout. And Another object of the present invention is to make it possible to accurately measure the pitch of the spiral groove.

[0006]

In order to achieve the above object, a spiral groove measuring device according to the present invention comprises a measuring element that contacts a spiral groove of a rotating object to be measured, and a light provided on the measuring element. A reflecting unit, a length measuring unit that irradiates light to the light reflecting unit, receives the reflected light, and detects an amount of movement of the measuring element in the axial direction of the measuring object, and a scale attached to the measuring element. A displacement detecting means for detecting an amount of displacement of the measuring element in a direction perpendicular to the axis direction of the measured object; and the measured object based on output signals from the displacement detecting means and the length measuring means. Computing means for calculating the amount of displacement of the tracing stylus at an arbitrary position in the axial direction in a direction orthogonal to the axial direction.

[0007] A rotation angle detection means for the object to be measured is provided on the support portion of the object to be measured, and a detection signal from the rotation angle detection means is input to the operation means. The pitch of the spiral groove can be obtained from the detection signal. The length measuring means may be a laser length measuring device,
The reflecting mirror of the laser length measuring instrument can be fixed to the measuring element. As the laser length measuring device, a Michelson interferometer type or another length measuring device can be used. In particular, a type that can obtain two interference fringes and can determine the forward or backward movement of the tracing stylus is desirable. Note that the displacement detecting means may be an optical linear encoder that optically reads the scale of a glass scale attached to the tracing stylus using a vernier.

[0008]

The helical groove measuring apparatus of the present invention constructed as described above determines the amount of movement of the measuring element in the axial direction of the measuring element by the length measuring means, and calculates the amount of movement of the measuring element in the axial direction of the measuring element by the displacement detecting means. The amount of displacement in the direction orthogonal to is calculated. And
From the values obtained by the calculating means by the length measuring means and the displacement detecting means,
An amount of displacement in a direction perpendicular to the axis of the object at an arbitrary position in the axial direction of the object, that is, a change in the depth of the spiral groove or a deflection of the object is obtained. Thus, the accuracy of the device under test can be grasped in detail, which can be useful for estimating the cause of the accuracy error.

Since the length measuring means can detect the moving amount of the measuring element by receiving the reflected light from the measuring element, no external force acts on the measuring element,
Measurement accuracy can be improved. Further, by attaching the scale of the displacement detecting means to the tracing stylus, not only can it be used for centering when the object to be measured is set, but also the device can be simplified. If a reflecting mirror is used as the light reflecting portion provided on the tracing stylus, the working of the tracing stylus becomes easy.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the spiral groove measuring device according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is an explanatory diagram of a spiral groove measuring device according to an embodiment of the present invention.

Referring to FIG. 1, a spiral groove measuring apparatus 10 has a base 12 on which a front bracket 16 and a rear bracket 18 for supporting a screw shaft 14 as an object to be measured stand upright. The front end bracket 16 is provided with a front end receiving center 20 having a conical front end. The rear end bracket 18 has a chuck 22 for inserting and fixing the shank portion of the screw shaft 14, a motor 26 for rotating the screw shaft 14 in the forward and reverse directions as indicated by an arrow 24 via the chuck 22, and a chuck 22. A rotation angle detector (rotation angle detection means) 28, which is constituted by a rotary encoder or the like, for detecting the rotation amount of the motor is mounted. The screw shaft 14 attached to the chuck 22 via the shank has a bearing hole (not shown) formed at the tip, and the tip of the tip receiving center 20 is inserted into the bearing hole. It is rotatably supported by brackets 16 and 18 via a chuck 20 and a chuck 22.

On the other hand, above the base 12, a guide 32 of the air slider 30 is provided in parallel with the screw shaft 14. The air slider 30 is provided with an optical linear encoder 34 constituting a displacement detecting means. The linear encoder 34 has a tracing stylus 36 directed downward. The measuring element 36 includes a detecting shaft 37 and a measuring ball 38 fixed to the lower end thereof.
8 comes into contact with the spiral groove 40 of the screw shaft 14.

As shown in FIG. 2A, the detection shaft 37 is mounted on a slider 44 of a linear motion roller bearing 42. When the detection shaft 37 moves up and down, the slider 44 is moved to the roller guides 46, 46. It goes up and down. The slider 44 has a linear encoder 3
The fourth glass scale 48 is fixed. In the main body case 50 of the linear encoder 34, on both sides of the glass scale 48, a vernier 52 facing the glass scale 48 and a detection unit 54 serving as a light receiving unit are disposed (see FIG. 2 (2)). ). The detection unit 54 is configured by a four-divided sensor corresponding to a scale portion of the vernier 52 described in detail later, and receives light transmitted through the vernier 52 and the glass scale 48. That is, a light emitting diode 56 serving as a light source is disposed behind the vernier 52, and the light emitted by the light emitting diode 56 is collimated by the collimating lens 58 so as to be incident on the vernier 52 from behind the vernier 52. Has become.

As shown in FIG. 2C, the glass scale 48 has, for example, graduations 60 having a width of 4 μm at a pitch of 8 μm. On the other hand, the vernier 52 has four scale portions 6.
1 to 64 are arranged in a matrix. Each scale 61
To 64, the scale 60 of the glass scale 48
And a pair of scales parallel to. The scales that make up each pair are
Each has a width of 4 μm, and the interval between the two is 4 μm, similar to the scale 60 of the glass scale 48. However, the scales 61 to 64 are arranged with a phase shift of π / 4 from the scale 60 of the glass scale 48. Therefore, when the glass scale 48 moves by 8 μm, the output of the sensor of the detecting unit 54 arranged corresponding to the scales 61 to 64 becomes as shown in FIGS. 3A and 3B. These outputs are output to a scale 61 (0 °) and a scale 63.
The output of the sensor corresponding to (180 °) is differentially amplified to a 0 ° signal as shown in FIG.
The output of the sensor corresponding to (90 °) and the scale portion 64 (270 °) is differentially amplified to a signal of 90 ° as shown in FIG. These signals are supplied to the converter 6 shown in FIG.
6 and converted into A-phase and B-phase rectangular wave signals, as will be described in detail later, and input to the arithmetic unit 70.

On the side of the detection shaft 37, there is formed a light reflector 74 for reflecting the light emitted by the laser length measuring device 72 as the length measuring means toward the laser length measuring device 72. As shown in FIG. 2 (4), the light reflecting portion 74 has a part of the detection shaft 37 cut flat by grinding or the like, and is mirror-finished.
The laser length measuring device 72 is a so-called Michelson interferometer-type length measuring device. As shown in FIG. 4, a laser light source 76 that emits laser light and a laser light source 76 are arranged in front of the laser light source 76. And a beam splitter 80.
The beam splitter 80 splits the laser beam 78 emitted from the light source 76 into a first split beam 79 and a second split beam 81 in two directions orthogonal to each other with the light reflecting unit 74 and the fixed mirror 82, The light reflection section 74 and the fixed mirror 82 serve as an interference fringe generation section that generates interference fringes from the light reflected. Then, at the position where the interference fringe of the beam splitter 80 is generated,
An optical sensor 84 for detecting interference fringes is provided. The output signal of the optical sensor 84 is input to the converter 86 of FIG.
A rectangular waveform is input to the arithmetic unit 70. Note that the laser length measuring device preferably generates two interference fringes and detects the moving direction of the measuring ball 38.

The arithmetic unit 70 calculates a light reflecting unit 74, that is, a distance calculating unit 88 for obtaining the amount of movement of the measuring ball 38 in the axial direction of the screw shaft 14 based on the output signal of the converter 86.
Measuring ball 38 based on the output signal of converter 66
And a displacement calculator 90 for calculating a displacement in a direction (radial direction) orthogonal to the axis of the screw shaft 14. The arithmetic unit 70 has a rotation angle calculation unit 94 that calculates the rotation amount of the screw shaft 14 based on the output signal of the rotation angle detector 28 obtained via the converter 92. Further, the arithmetic unit 70 includes a pitch calculation unit 96 for obtaining the pitch of the spiral groove 40 formed on the screw shaft 14 from the outputs of the distance calculation unit 88 and the rotation angle calculation unit 94, a distance calculation unit 88 and a displacement calculation unit 90.
Of the measurement ball 38 in the radial direction at any position along the axis of the screw shaft 14 (the amount of deflection)
Is provided, and the outputs of the shake calculation section 98 and the pitch calculation section 96 can be output to an output device 100 such as a printer or a display, or to an external storage (not shown).

The operation of the embodiment constructed as described above is as follows. The measurement ball 38 is brought into contact with a predetermined position (for example, the left end in FIG. 1) of the spiral groove 40 of the screw shaft 14 supported by the chuck 22 and the tip receiving center 20. When the motor 26 is driven to rotate the screw shaft 14, the measuring ball 38 is guided by the spiral groove 40 and moves in the axial direction of the screw shaft 14.

The rotation angle detector 28 outputs a detection signal to the converter 92 at each predetermined rotation angle of the screw shaft 14, and
2 is input to the rotation angle calculation unit 94 as a rectangular wave. Also,
The optical sensor 84 of the laser length measuring device 72 detects a change in the brightness of interference fringes generated based on the reflected light from the light reflecting portion 74 and the fixed mirror 82 that move together with the measuring ball 38, and sends the change to the converter 86. input. On the other hand, as described above, the linear encoder 34 outputs a signal of 0 ° based on the scale 60 of the glass scale 48 detected by the scale of the vernier 52 and the signal 9.
The signal of 0 ° is input to the converter 66. The converter 66
Based on the incoming 0 ° and 90 ° signals,
The signals as shown in FIG. 5 are created, and the A-phase and B-phase line drive signals are output from the rectangular waves corresponding to these signals as shown in FIG.

That is, the converter 66 outputs the signal of 0 ° and 9
A signal of 0 °, a signal of 45 ° obtained by halving a difference between them by a dividing resistor, and a difference between a signal of 180 ° and a signal of 90 ° produced by inverting the signal of 0 ° were halved by a dividing resistor. Create 135 ° signals, and from these, 0 °,
Generate a 45 °, 90 °, 135 ° signal square wave,
An A-phase line drive signal and a B-phase line drive signal based on the (0 ° -90 °) A-phase signal and the (45 ° -135 °) B-phase signal are output. These line drive signals are input to a displacement calculation unit 90 of the calculation device 70. The displacement calculation unit 90 calculates the amount of displacement of the screw shaft 14 of the measurement ball 38 in the radial direction, and inputs the calculated amount to the shake calculation unit 98.

That is, the signals of the A phase and the B phase are shown in FIG.
From the relationship between (3) and FIG. 3, as shown in FIG. 6, for example, if the rising a of the A phase is 1 μm, the rising b of the B phase is 2 μm, the falling c of the A phase is 3 μm, and the B phase is 3 μm. Is 4 μm, and the next rising e of phase A is 5 μm.
m, the rising f of the next B phase represents 6 μm, the falling g of the A phase is 7 μm, and the falling h of the B phase is 8 μm. Therefore, the displacement calculation unit 90 counts up or down the count value of an up / down counter (not shown) from the phase relationship between the A phase and the B phase, and calculates the displacement amount of the measurement ball 38 based on the count value. Output to Further, the distance calculation unit 88 counts the output pulses of the converter 86, determines the amount of movement of the measurement ball 38 in the axial direction of the screw shaft 14, and outputs it to the pitch calculation unit 96 and the shake calculation unit 98. The pitch calculation unit 96 calculates the rotation angle of the screw shaft 14 obtained by the rotation angle calculation unit 94 and the distance calculation unit 88.
From the moving distance of the measuring ball 38 calculated by
A pitch of 0 is obtained and output to the output device 100. Further, the shake calculating section 98 includes a distance calculating section 88 and a displacement calculating section 9.
Based on the output of “0”, the radial displacement (runout) of the measurement ball 38 at an arbitrary position in the axial direction of the screw shaft 14 is calculated and sent to the output device 100. The shake amount and the pitch are displayed on a display device, printed by a printer, and stored in a storage device as needed.

Thus, in the embodiment, the screw shaft 1
Since the amount of runout (or variation in the depth of the spiral groove 40) at any position in the axial direction of 4 can be easily obtained, it is easy to analyze the factor of the manufacturing error of the screw shaft 14,
It is possible to manufacture the screw shaft 14 with high precision. In the embodiment, the light reflecting portion 74 is connected to the measuring ball 3 of the detection axis 37.
8, the measurement accuracy of the spiral groove 40 can be improved without being substantially affected by bending of the detection shaft 37 or the like. Moreover, in the embodiment, since the glass scale 48 of the linear encoder 34 is fixed to the measuring ball 38, not only the structure can be simplified, but also the centering when the screw shaft 14 is set can be performed. Further, in the embodiment, since the detection shaft 37 is attached to the slider 44 of the linear motion roller bearing 42, it has a radial rigidity and a structure that is strong against rotational torque. An error can be prevented, and the measurement of the spiral groove 40 can be performed with high accuracy. In the embodiment, the amount of movement of the measuring ball 38 is obtained by the laser length measuring device 72, and the amount of rotation of the screw shaft 14 is obtained by the rotation angle detector 28. , The absolute value of the pitch can be obtained.

In the above embodiment, the detection shaft 37
The case where the mirror-finished light reflecting portion 74 is formed is described above. However, as shown in FIG. 7, the reflecting mirror 102 is fixed to the side of the detection shaft 37 via a mounting ring 101 and the like, and the reflecting mirror 102 is It may be a reflection section. When the light reflecting portion is constituted by the reflecting mirror 102 in this manner, the processing of the detection shaft 37 is facilitated, and a decrease in the rigidity of the detection shaft 37 can be prevented.

In the above embodiment, the screw shaft 1
The case where the spiral groove 40 of No. 4 is measured has been described, but the present invention can also be applied to the measurement of a spiral groove such as a bolt or a drill. Further, in the above embodiment, the case where the length measuring means is the Michelson interferometer type laser length measuring device 72 has been described, but it is a matter of course that the present invention is not limited to this. Further, the linear encoder 3 detects the runout of the screw shaft 14.
4 describes the case where the vernier 52 is constituted by four scale portions. However, another linear encoder may be used, or another displacement detecting means other than the linear encoder may be used. Further, in the above-described embodiment, the case where the pitch calculation unit 96 obtains only the pitch of the screw shaft 14 has been described, but the pitch angle may also be obtained.

[0024]

As described above, according to the present invention, according to the present invention, the moving amount of the measuring element in the axial direction of the measuring object determined by the length measuring means and the measuring element determined by the displacement detecting means are calculated by the calculating means. From the displacement amount in the direction perpendicular to the axis direction of the DUT, to determine the displacement amount of the measuring element in the direction perpendicular to the axis at any position in the axial direction of the DUT, that is, to determine the deflection of the DUT, The accuracy of the object to be measured can be grasped in detail, which can be useful for estimating the cause of the accuracy error.

[Brief description of the drawings]

FIG. 1 is a block diagram of a spiral groove measuring device according to an embodiment of the present invention.

FIG. 2 is a detailed explanatory diagram of an optical linear encoder showing an example of a displacement detecting unit according to the embodiment.

FIG. 3 is an explanatory diagram of an output signal of the optical linear encoder according to the embodiment.

FIG. 4 is an explanatory diagram of a Michelson interferometer type laser length measuring device showing an example of a length measuring device according to the embodiment.

FIG. 5 shows A phase, B phase from the output signal of the linear encoder.
FIG. 4 is an explanatory diagram of a method for obtaining a phase signal.

FIG. 6 is an explanatory diagram of a rectangular wave corresponding to the signal shown in FIG. 5 generated by the converter according to the embodiment.

FIG. 7 is an explanatory view of another embodiment of the light reflecting section.

[Explanation of symbols]

 Reference Signs List 10 spiral groove measuring device 14 DUT (screw shaft) 28 rotation angle detecting means (rotary encoder) 30 air slider 34 displacement detecting means (rotation angle detector) 36 measuring element 38 measuring ball 40 spiral groove 48 glass scale 52 vernier 54 Detecting section 70 Computing means (computing device) 72 Length measuring means (laser length measuring instrument) 74 Light reflecting section 102 Reflecting mirror

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01B 11/00-11/30 G01B 21/20

Claims (4)

(57) [Claims] 1. A measuring element that comes into contact with a spiral groove of a rotating DUT, a light reflecting portion provided on the measuring element, and a light reflecting section that is irradiated with light, receives the reflected light, and receives the reflected light. Measuring means for detecting the amount of movement of the object to be measured in the axial direction, and a scale attached to the measuring element, and detecting the amount of displacement of the measuring element in a direction perpendicular to the axis direction of the object to be measured. Based on the output signals of the displacement detecting means and the length measuring means, the displacement amount of the measuring element at an arbitrary position in the axial direction of the object to be measured in a direction perpendicular to the axial direction of the measuring element. A spiral groove measuring device, comprising: a calculating means for determining the spiral groove. 2. The apparatus according to claim 1, wherein the supporting portion of the object to be measured includes a rotation angle detecting means for detecting a rotation angle of the object to be measured, and the calculating means includes a function of the rotation angle detecting means and the length measuring means. The spiral groove measuring device according to claim 1, further comprising a pitch calculating unit that calculates a pitch of the spiral groove based on an output signal. 3. The spiral groove measuring device according to claim 1, wherein the light reflecting section is a mirror fixed to the tracing stylus. 4. A tracing stylus that comes into contact with a spiral groove of a rotating DUT, a light reflecting portion provided on the measuring stylus, a rotation angle detecting unit that detects a rotation angle of the DUT, and a light source that emits light. Splitting the split light into a first split light incident on the light reflecting portion and a second split light in a direction orthogonal to the first split light, the first split light reflected by the light reflecting portion, and the second split light. An interference fringe generator for generating interference fringes with light, and an interference fringe detector for detecting the interference fringes generated by the interference fringe generator, the amount of movement of the tracing stylus in the axial direction of the object to be measured Length measuring means for detecting the measurement element, a scale provided on the measurement element, a vernier disposed to face the scale, and a light receiving section for detecting light transmitted through the vernier and the scale, and the measurement element A displacement for detecting a displacement of the object to be measured in a direction orthogonal to the axial direction Output means, based on output signals of the displacement detection means, the length measurement means, and the rotation angle detection means, a direction orthogonal to the axis direction of the tracing stylus at an arbitrary position in the axis direction of the workpiece. And a calculating means for calculating a displacement amount of the spiral groove and a pitch of the spiral groove.