JP3207458U - Pitch measurement structure - Google Patents

Abstract

A pitch measuring structure with improved accuracy in a non-contact type pitch measuring apparatus is provided. A pitch measurement structure (10) includes a shaft portion (11) that rotatably supports a rotating body (S), a drive portion (12) that rotationally drives the shaft portion, and a rotating body that rotates together with the shaft portion. A laser beam that irradiates a laser beam with a predetermined linear trajectory over a continuous time, and measures and outputs the distance to the protrusion (Q) that crosses the laser beam several times based on the reflected light from the rotating body. The angle data of the shaft part is accumulated from the distance measurement unit (13) and the rotation condition of the shaft part, the distance data corresponding to the angle data is accumulated from the distance output from the laser distance measurement part, and from the angle data and the distance data A pitch calculator (14) that calculates the pitch between the plurality of protrusions. [Selection] Figure 1

Description

  The present invention is a pitch measuring device for measuring a circumferential pitch of a protrusion such as a tooth of a gear or a blade of an impeller in a non-contact manner, such as a gear or an impeller. About. The present invention also relates to a pitch measuring device that measures a longitudinal length of teeth or protrusions in a non-contact manner, using a long object having teeth such as a rack or a long object having a plurality of protrusions as a measurement object.

  In the production process of products such as gears and screws, it is important to measure the product finish. In order to ship a product that has passed a predetermined standard at a low cost, it is desirable to be able to measure accurately in a short time without increasing the number of production steps. In order to realize such a demand, a non-contact measurement method can be considered.

  As a non-contact measurement method for gear teeth and screw pitch, for example, the one described in Japanese Patent No. 3960618 (Patent Document 1) is known. In the pitch measurement method described in Patent Document 1, the target shape portion is rotated so that the plurality of target shape portions move on the same route. Further, for a target shape portion that passes through a predetermined position on the route from a fixed position, the target shape portion is focused on the predetermined position and continuously captured and stored by the camera. Next, R, G, and B luminance levels of the stored image data are respectively obtained, multiplied by an appropriate coefficient, and added, and the sharpness of the image is digitized as a focus evaluation value. Next, let the focus evaluation value be the vertical axis, the rotation angle (movement distance) of the target shape part be the horizontal axis, and based on the correspondence between the focus evaluation value and the rotation angle, a number of points that are continuous in a wavy shape on the graph obtain. Then, a wavy reference curve is calculated from the point group, and peak values Q 0, Q 1, Q 2,... Of the focus evaluation values are obtained from the reference curve, and the rotation angle difference between adjacent peak positions is determined as pitches θ 1, θ 2, It is calculated as θ3,.

Japanese Patent No. 3960618

  However, the conventional pitch measuring method has the following problems. That is, there are differences in tint due to skin burn, burning unevenness, cleaning stains, etc. during manufacture on the surface of the gear teeth and screw pitch, resulting in differences in brightness and variations in reflected light. In addition, when the reflectance of the product surface is high, measurement becomes impossible due to halation. For this reason, even if the teeth of the gear and the thread of the screw have the same shape, different image data can be obtained due to misjudgment if the color of the tooth or thread is different. If it does so, the measurement result of a pitch will be influenced by the surface state of an attention shape part, and the pitch of a tooth and a screw thread cannot be measured correctly. When the installation environment (illuminance) changes, different image data is obtained even for the same target shape portion, and the pitch cannot be measured accurately.

  Therefore, in order not to be affected by the surface state of the target shape portion, a well-known contact-type pitch measuring device is used. However, when measuring the gear pitch with the contact-type pitch measuring device, there are many measuring elements. It is necessary to turn the gear while inserting and removing between the teeth. For this reason, the measurement work requires a long time and a large amount of labor.

  Also, since the probe wears out, the measurement quality gradually changes and must be periodically replaced. The maintenance cost of the measuring device increases the capital investment cost, which in turn increases the production cost of the product.

  An object of the present invention is to provide a non-contact type pitch measurement structure which improves the accuracy by eliminating the influence of the color of teeth and screws in view of the above situation. It is another object of the present invention to provide a pitch measurement structure that can measure a pitch error in a short time without increasing the number of processes and contribute to a reduction in product production costs.

  For this purpose, the pitch measuring structure according to the present invention measures a rotating body having a circular base and a plurality of protrusions arranged on the outer periphery of the base at equal intervals in the circumferential direction, and rotatably supports the rotating body. A shaft spot, a drive section that rotates the shaft section, and a rotating body that rotates together with the shaft section are irradiated with a laser spot beam that draws a predetermined linear trajectory, and the laser spot beam is emitted based on the reflected light from the rotating body. Laser distance measurement unit that measures and outputs the distance to the protrusion that crosses multiple times, accumulates the distance data output from the laser distance measurement unit, accumulates angle data corresponding to the distance data from the rotation condition of the shaft, A pitch calculator that calculates the pitch between the plurality of protrusions from the angle data and the distance data.

  According to the present invention, since the distance is measured by the laser spot beam, the influence of the color difference that occurs in the prior art is eliminated. Therefore, the pitch of the protrusions on the outer periphery of the rotating body can be accurately measured. Compared with a contact-type pitch measuring device, the pitch can be measured in a short time, and the durability is excellent and the measurement quality does not change. The rotating body having a circular base and a plurality of protrusions arranged on the outer periphery of the base at equal intervals in the circumferential direction is generally used for gears such as bevel gears, spur gears, parallel shaft gears, hypoid gears, turbines, and turbochargers. An impeller such as an impeller, or an object having a shape similar to these. The direction of rotation of the shaft is not particularly limited, and can be forward or reverse. The present invention can be applied to all equipment provided with a rotation mechanism. Thereby, the capital investment cost can be suppressed. For example, the present invention can be attached to a gear cutter or a rotary machine. Further, according to the present invention, when measuring the gear tooth pitch error, it is possible to measure at any position in both the tooth profile direction and the tooth trace direction by changing the mounting position of the laser distance measuring unit.

  The pitch may be calculated as a pitch angle [°] or may be calculated as a pitch length [μm]. The structure for outputting the angle data from the rotation condition of the shaft is not particularly limited. As an embodiment of the present invention, an encoder is further provided that measures the angle of the shaft portion a plurality of times and outputs the same to the pitch calculation portion. According to this embodiment, since the rotation angle is also measured, the pitch measurement accuracy is improved.

  The smaller the resolution, the finer the measurement result. In a preferred embodiment, the resolution of the angle that the encoder measures is finer than 1/10 of the maximum allowable pitch error. Specifically, for example, in the case of a gear having a pitch circle of φ30 [mm] and a pitch error standard of 1 [μm], the number of signals output by the encoder per one rotation of the shaft portion is 1 million pulses or more.

  Or as another embodiment, the motor control part which rotates a drive part at a fixed speed is further provided. According to such an embodiment, the motor can be rotated at a constant speed, rotation angle data can be obtained from the time axis based on the constant speed, and the structure for outputting the angle data can be simplified.

  When measuring the pitch, it is conceivable that the measurement result changes depending on whether it is measured at the base of the protrusion or at the tip of the protrusion. When the object to be measured is a rotating body, the predetermined linear trajectory drawn by the laser spot beam extending toward the protrusion has an acute angle, for example, with respect to a reference line passing through the irradiation port of the laser distance measuring unit and the rotation center of the shaft unit. Eggplant. As a result, the laser distance measuring unit can irradiate the laser spot beam from the side of the protrusion to measure the intermediate portion between the tip and the base of the protrusion, and obtain a good measurement result. Alternatively, the angle of the reference line and the linear trajectory may be set to 0 [°], and the laser distance measuring unit may measure the tip of the protrusion.

  As a further preferred embodiment of the present invention, the plurality of protrusions include a first protrusion and a second protrusion that are arranged adjacent to each other, and the laser spot beam includes a tip of the first protrusion that rotates about the shaft portion, It collides with the intermediate part which connects the front-end | tip part and root part of a 2nd protrusion in this order or the reverse order. According to such an embodiment, it is possible to obtain a good measurement result by measuring the distance from the middle part of the protrusion to the tip.

  The smaller the resolution, the finer the measurement result. As a preferred embodiment of the present invention, the resolution of the distance measured by the laser distance measuring unit is finer than 1/10 of the maximum allowable error of the pitch. Specifically, for example, when measuring the pitch of the hypoid gear teeth, the minimum required resolution is 0.1 [μm]. Thereby, measurement accuracy can be raised to 0.1 [μm] or less.

  The present invention can measure the pitch angle of rotating bodies such as gears and impellers, and can measure the pitch of long objects such as screw threads and rack teeth. For this reason, the pitch measurement structure according to the present invention has a base that extends in the longitudinal direction and an object having a plurality of protrusions arranged at equal intervals in the longitudinal direction on the base, and a drive unit that displaces the object in the longitudinal direction. A predetermined linear trajectory that defines an acute angle with respect to the longitudinal direction is defined, and a laser spot beam that draws the linear trajectory is applied to an object that is displaced in the longitudinal direction, and the laser spot beam is traversed based on the reflected light from the object. Laser distance measurement unit that measures and outputs the distance to the projection multiple times, and distance data output from the laser distance measurement unit, and displacement data corresponding to the object distance data from the displacement conditions of the drive unit And a pitch calculator for calculating the pitch between the plurality of protrusions from the displacement data and the distance data.

  As described above, according to the present invention, the gear tooth pitch and the impeller blade pitch can be accurately measured in a short time. Therefore, it is possible to contribute to efficiently producing a gear with little meshing transmission error.

It is a schematic diagram which shows the system configuration | structure of the pitch measurement structure which becomes one Embodiment of this invention. It is a work flow which shows the pitch measurement procedure in this invention. It is a schematic diagram which shows the laser spot light beam which this invention irradiates to a rotary body. It is a graph which shows the relationship between the rotation angle data per tooth, and distance data. It is a schematic diagram which contrasts and shows the position of an ideal tooth and the measured tooth position. It is a work flow which a contact-type pitch measurement structure performs. It is a schematic diagram which shows the system configuration | structure of the pitch measurement structure which becomes other embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing an overall system configuration of a pitch measurement structure according to an embodiment of the present invention. The pitch measurement structure 10 includes a shaft part 11, a motor 12, a laser distance measurement part 13, a computer 14, and a motor control part 15.

  A workpiece (hereinafter referred to as a rotating body S) is attached to the shaft portion 11. The shaft portion 11 has one end 11a and the other end 11b, is rotatably supported by a bearing (not shown), and is rotatable. The other end 11b can be displaced in the direction of the rotation axis O, and the rotating body S to be measured is clamped between the one end 11a and the other end 11b. Thus, the shaft portion 11 holds the rotating body S coaxially with the rotating shaft O. The rotating body S has a plurality of protrusions Q arranged at equal intervals in the circumferential direction.

  The motor 12 is a drive source that rotationally drives the shaft portion 11. The motor 12 is electrically connected to the motor control unit 15 and is controlled by the motor control unit 15 to rotate under a predetermined rotation condition. Further, the motor control unit 15 outputs the rotation conditions of the motor 12 to the computer 14. For example, the motor control unit 15 outputs pulse (phase) information indicating the angle of the motor 12 every predetermined unit time. Alternatively, the encoder 16 may be attached to the shaft portion 11. The encoder 16 detects the rotation angle of the shaft 11 every predetermined unit time and outputs it to the computer 14. As the rotating body S rotates about the rotation axis O, the plurality of protrusions Q perform a rotation movement that revolves around the rotation axis O.

  The laser distance measuring unit 13 generates an irradiation portion for generating and irradiating a laser spot beam, a light receiving portion for receiving a reflected laser beam reflected by the laser spot beam colliding with a measurement object, and an irradiation portion based on the reflected laser beam. And an output portion for outputting a distance signal to the measurement object. The laser distance measuring unit 13 is selected to have a small resolution because the measurement object is a tooth or a blade. Further, the laser distance measuring unit 13 is installed and fixed to the shaft unit 11 so as to be separated from the measurement target within a range of 10 to 50 [mm].

  The laser ranging unit 13 is installed in the vicinity of the shaft unit 11, irradiates the projection Q of the rotator S with a laser spot beam, measures the distance from the laser ranging unit 13 to the projection Q of the rotator S, and the computer 14. Output to. That is, the pitch measurement structure 10 of the present embodiment does not have a probe that contacts the rotating body S, and is a non-contact type that measures the pitch of the rotating body S with a laser beam. The laser distance measuring unit 13 is fixed in position and laser irradiation direction with respect to the rotation axis O, and the rotating body S rotates by the rotation of the shaft unit 11. Accordingly, the laser distance measuring unit 13 irradiates all the protrusions Q that perform rotational movement with a laser spot beam, and measures the distances of all the protrusions Q.

  The computer 14 receives the rotation condition of the motor 12, and creates angle data (unit [°] or [rad]) regarding the rotation position of the rotating body S from the rotation condition. And the distance value corresponding to each angle value is accumulated from the received distance data. The pitch between adjacent projections Q, Q is calculated from the relationship between the angle data and the distance data, and is output to the interface of the computer 14. The computer 14 may be a commercially available personal computer. By rotating the rotating body S beyond one rotation, the pitches of all the protrusions Q and Q can be calculated.

  In the present embodiment, as an example, the rotating body S is rotated in the positive direction, and the pitch between the adjacent protrusions Q and Q is calculated. Preferably, the rotating body S is rotated more than one rotation, and the measurement error is reduced by removing the data attributed to the acceleration / deceleration of the motor 12 at the first rotation and the last rotation and the rotation less than one pitch. Remove.

  FIG. 2 is a work flow showing a pitch measurement procedure in the pitch measurement structure 10. When measuring the pitch of the protrusions Q, first, a workpiece (rotating body S) to be measured is clamped to the shaft portion 11 in step S21. When the motor 12 is energized and the shaft 11 is rotated in the next step S22, the work (rotating body S) rotates. In the next step S23, the laser distance measuring unit 13 outputs the distance data and outputs the rotation condition of the motor control unit 15. The rotation condition is the rotation speed of the motor 12 or the angle of the shaft portion 11. In the next step S24, the computer 14 collates the distance data and rotation conditions of each protrusion Q, accumulates these data, and outputs the pitch between adjacent protrusions Q. This completes the work flow.

  The rotating body S is a bevel gear having a shaft U as shown in FIG. Alternatively, the rotating body S may be a spur gear or an impeller. FIG. 3 is a schematic diagram showing a gear as a rotating body. The rotating body (gear) S includes a base P centered on the rotation axis O and a plurality of protrusions provided on the outer periphery of the base P at equal intervals in the circumferential direction, that is, teeth Q1, Q2,. In the following description, when teeth are not distinguished, they are simply referred to as Q. In this example, the rotating body (gear) S to be measured has eight teeth Q.

  As shown in FIG. 3, the laser distance measuring unit 13 irradiates the tooth surface of the tooth Q with the laser spot beam L. The laser distance measuring unit 13 measures the distance every predetermined unit time of, for example, 0.5 [msec] over a predetermined continuous time, and continuously outputs the measurement result to the computer 14 each time. The laser distance measuring unit 13 does not change its position and direction for a predetermined continuous time.

  The laser spot beam L collides with the tooth surface of the tooth Q in a predetermined linear trajectory T. The distance from the linear track T to the rotation axis O is maintained at a predetermined value in a range that is larger than the radius of the root of the rotating body (gear) S and smaller than the radius of the tooth tip of the rotating body (gear) S. The distance D from the laser ranging unit 13 to the tooth Q is set to an appropriate range according to the specifications of the laser ranging unit 13. An angle N formed by the linear trajectory T from the laser distance measuring unit 13 to the tooth Q and the reference line M from the laser distance measuring unit 13 to the rotation axis O is an acute angle.

  Since the rotating body S rotates at a constant speed as indicated by an arrow in FIG. 3, the distance D from the laser distance measuring unit 13 to the tooth Q changes. Specifically, since the tooth Q1 moves away from the laser distance measuring unit 13 and the adjacent tooth Q2 approaches the laser distance measuring unit 13, first the distance to the tooth surface of the tooth Q1 is measured, and then the tooth of the tooth Q2 Measure the distance to the surface. The laser distance measuring unit 13 thus measures the tooth surfaces of each tooth one after another, and ends the measurement when measuring the tooth surfaces of all the teeth.

  More specifically, the laser spot beam L collides with the tooth tip surface of the tooth Q1 to measure the distance, and after a predetermined unit time, slightly collides with the tooth surface on the tooth base side from the previously measured distance. Then, the distance is measured, and thereafter, the distance is measured by colliding with the tooth surface of the tooth base side one after another. Next, the laser spot light L slightly collides with the tooth surface on the tooth tip side from the previously measured distance, and measures the distance, and subsequently collides with the tooth surface on the tooth tip side one after another. Measure the location. From the time when the tooth tip of the tooth Q1 revolving around the rotation axis O first crosses the trajectory T until the end of the tooth Q1 finally traverses the trajectory T, the laser distance measuring unit 13 has a plurality of teeth on the tooth root surface and the tooth tip surface of the tooth Q1. When the distance of the part is measured, the distance measurement of the tooth Q1 is completed.

  As the tooth Q1 moves away and the tooth Q2 approaches, the laser spot beam L collides with the tooth Q2 instead of the tooth Q1. Similarly, when the distance to a plurality of positions on the tooth surface of the tooth Q2 is measured, the distance measurement of the tooth Q2 is completed. In this manner, the distances to a plurality of locations on the tooth surface of each tooth are sequentially measured. For this reason, the distance data repeatedly increases and decreases each time one tooth crosses the laser spot beam L.

  In the present embodiment, a shaft runout measuring device (not shown) may be provided to measure the shaft runout of the shaft U. And it is good to measure the above-mentioned pitch measurement by measuring the angle and distance of the shaft runout.

  As an example, pitch measurement was performed on the rotating body S and the bevel gear having 8 teeth shown in FIG. The conditions are: the rotational speed of the motor 12 is 15.00 [rpm], the sampling frequency (measurement unit time) is 0.20 [msec], the measurement unit of the encoder 16 is 0.001 [°], and the measurement unit of the laser distance measuring unit 13 is 0.01 [μm], data accumulation number 25000 points, data accumulation time 5.00 [sec], and data measurement range 450 [°]. This is for measuring data of 10 teeth with respect to the rotating body S having 8 teeth at 360 °. When the motor 12 is driven and the rotational speed of the rotating body S is stabilized, distance measurement by the laser distance measuring unit is started. The output distance is repeatedly increased and decreased within a predetermined range. Data storage starts when the set value (28.27961 [mm]) is exceeded. Table 1 shows data indicating the shaft portion 11 at a certain angle and the distance measured at that time. Since the amount of data is very large, a part of it is omitted. The left column is the number of accumulated data, and numbers 1 to 25000 are present. The middle row is the measurement angle of the shaft portion 11 at each number. The right column is the measurement distance at the corner number.

  Numbers 1 to 150 are extracted from numbers 1 to 25000 shown in Table 1 as the first tooth. Table 2 shows segment extraction data for the first tooth. The left column is a number corresponding to Table 1, this adjacent column is a measurement angle corresponding to each number, and this adjacent column is a measurement distance corresponding to each number. The right column is a value obtained by squaring the measurement distance corresponding to each number. Using such a square value, an approximate expression of a quadratic function can be obtained by the least square method. Alternatively, an approximate expression of a linear function may be used. Since the amount of data is very large, a part of it is omitted. FIG. 4 is a graph showing Table 2 and the approximate expression, in which the horizontal axis represents the measurement distance, the vertical axis represents the angle, the point represents data, and the solid line represents the approximate expression.

  Referring to FIG. 4, when the reading angle on the vertical axis when the horizontal axis distance is 28.50 [mm] is obtained based on the approximate expression, the first tooth is 1574627 (rounded off after the decimal point). The obtained reading angle is shown in Table 4.

  Similarly, numbers 2501 to 2650 are extracted from numbers 1 to 25000 shown in Table 1 as second teeth. Table 3 shows segment extraction data for the second tooth. Similarly, when the approximate expression was calculated and the reading angle on the vertical axis when the distance on the horizontal axis was 28.50 [mm] was obtained based on the approximate expression, the second tooth was 1619653 (rounded off after the decimal point). The obtained reading angle is shown in Table 4.

  Similarly, numbers 5001 to 5150 are extracted from numbers 1 to 25000 shown in Table 1 to form the third tooth. Similarly, when the approximate expression is calculated and the reading angle on the vertical axis when the distance on the horizontal axis is 28.50 [mm] is obtained based on the approximate expression, the third tooth is 1664705 (rounded off after the decimal point). The obtained reading angle is shown in Table 4.

  Similarly, numbers 7501 to 7650 are extracted from numbers 1 to 25000 shown in Table 1 to be the fourth tooth. Similarly, when the approximate expression is calculated and the reading angle of the vertical axis of the fourth tooth when the horizontal axis distance is 28.50 [mm] is calculated based on the approximate expression, the fourth tooth is 1709729 (rounded off after the decimal point). It was. The obtained reading angle is shown in Table 4.

  Similarly, numbers 10001 to 10150 are extracted from numbers 1 to 25000 shown in Table 1 to be the fifth tooth. Similarly, when the approximate expression is calculated and the reading angle of the vertical axis of the fifth tooth when the horizontal axis distance is 28.50 [mm] is obtained based on the approximate expression, the fifth tooth is 1754730 (rounded off after the decimal point). It was. The obtained reading angle is shown in Table 4.

  Similarly, numbers 12501 to 12650 are extracted from numbers 1 to 25000 shown in Table 1 to be the sixth tooth. Similarly, when the approximate expression is calculated and the reading angle of the vertical axis of the sixth tooth when the distance on the horizontal axis is 28.50 [mm] is obtained based on the approximate expression, the sixth tooth is 1799678 (rounded off after the decimal point). It was. The obtained reading angle is shown in Table 4.

  Similarly, numbers 15001 to 15150 are extracted from numbers 1 to 25000 shown in Table 1 to form seventh teeth. Similarly, when the approximate expression is calculated and the reading angle of the vertical axis of the seventh tooth when the distance on the horizontal axis is 28.50 [mm] is calculated based on the approximate expression, the seventh tooth is 1844633 (rounded off after the decimal point). It was. The obtained reading angle is shown in Table 4.

  Similarly, numbers 17501 to 17650 are extracted from numbers 1 to 25000 shown in Table 1 and are set as the eighth tooth. Similarly, when the approximate expression is calculated and the reading angle of the vertical axis of the eighth tooth when the horizontal axis distance is 28.50 [mm] is obtained based on the approximate expression, the eighth tooth is 1889613 (rounded off after the decimal point). It was. The obtained reading angle is shown in Table 4.

  Similarly, numbers 20001 to 20150 are extracted from numbers 1 to 25000 shown in Table 1 to be 9th tooth. Similarly, when the approximate expression is calculated and the reading angle of the vertical axis of the ninth tooth when the distance of the horizontal axis is 28.50 [mm] is calculated based on the approximate expression, the ninth tooth is 1934627 (rounded off after the decimal point). It was. The obtained reading angle is shown in Table 4. The ninth tooth is the same as the first tooth. The 10th tooth data is not used because the motor deceleration and the motor stop are mixed and the motor rotation speed is not 15 [rpm].

  Table 4 shows the reading angles of the 1st to 9th teeth thus obtained. The left column shows the number of teeth. This adjacent row indicates the reading angle. This adjacent row represents the angular difference between adjacent teeth. This adjacent row represents the phase difference between the ideal value of each tooth and the reading angle. As indicated by a two-dot chain line in FIG. 5, each tooth Q is ideally arranged at equal intervals of 45 [°]. In practice, however, the teeth are arranged with a pitch error F. In two adjacent teeth, the difference between the actual pitch and the theoretical pitch of the tooth surfaces on the same side that are separated along the pitch circle is referred to as a single pitch error.

  Returning to Table 4, the column next to the phase difference shows the phase difference converted from degrees [°] to radians [rad]. Multiplying each radian by a predetermined radius of the rotating body S, 19.279 [mm] in this embodiment, a single pitch error is calculated. Single pitch errors are shown in radians next row. The predetermined radius is a radial dimension of a tooth surface separated from the laser distance measuring unit 13 by the above-described distance of 28.50 [mm] in the ideally shaped rotator S without error.

  The accumulated pitch is calculated by accumulating and adding adjacent single pitch errors. Shown in this adjacent column. The accumulated pitch error is 39.3 [μm], which is the difference between the maximum value 34.7 [μm] and the minimum value −4.6 [μm].

  According to the pitch measurement structure 10 of the present embodiment, with respect to the protrusions such as gear teeth and impeller blades that are provided at equal intervals in the circumferential direction, the pitch of each protrusion, the single pitch error, and the cumulative pitch error Can be requested.

  As a reference example, FIG. 6 shows a flow of work procedures for a contact-type pitch measuring device. When measuring the gear tooth pitch, first, in step S101, a workpiece (gear) to be measured is clamped to the shaft portion of the pitch measuring device. In the next step S102, the probe of the pitch measuring device is inserted into the tooth surface groove.

  In the next step S103, the work (gear) is rotated. In the next step S104, the angle at which the probe contacts the workpiece is read. In the next step S105, the measuring element is extracted from the groove on the tooth surface. In the next step S106, indexing is performed to rotate the workpiece by one tooth according to the number of teeth of the workpiece. In the next step S107, it is determined whether or not all teeth have been measured. If the measurement of all teeth has not been completed (NO), the process returns to step S102, and the phase of the next tooth is read. On the other hand, if the measurement of all teeth has been completed (YES), the measurement result is output and this work flow is terminated.

  By the way, according to this embodiment shown in FIG. 2, compared with the reference example shown in FIG. 6, step S102, step S105, and step S106 can be omitted. Further, it is not necessary to repeat step S102 to step S106. Therefore, the time required for the pitch measurement is shortened and the working efficiency is improved.

  Moreover, according to this embodiment, since it is a non-contact type, the problem that a measuring element wears out does not arise. This is advantageous from the viewpoint of maintenance and durability.

  Next, a pitch measurement structure according to another embodiment of the present invention will be described with reference to the schematic diagram of FIG.

  The pitch measurement structure 20 includes a drive unit 32, a laser distance measurement unit 33, and a pitch calculation unit 34, and measures the pitch of the protrusions B arranged in the longitudinal direction of the object C.

  The object C has a base portion A extending in the longitudinal direction and a plurality of protrusions B arranged on the base portion A at equal intervals in the longitudinal direction. The object C is, for example, a rack or a screw, and the protrusion B is, for example, a rack tooth or a screw thread. The drive unit 32 displaces the object C in the longitudinal direction M as indicated by a thick arrow in FIG.

  The laser distance measuring unit 33 irradiates the object C with the laser spot beam L over a continuous time, and measures the distance to the object C based on the reflected light from the object C. The laser spot beam L draws a predetermined linear trajectory T and collides with the protrusion B. The linear trajectory T extending from the laser distance measuring unit 33 toward the protrusion B forms an acute angle N with respect to the longitudinal direction M. Since the protrusion B is displaced in the longitudinal direction M, the distance from the laser distance measuring unit 33 to the protrusion B repeatedly increases and decreases. Therefore, the laser distance measuring unit 33 measures and outputs the increase / decrease in the distance to the protrusion B crossing the laser spot beam based on the reflected light from the protrusion B.

  The pitch calculation unit 34 accumulates the displacement data of the object C from the displacement condition of the drive unit 32, accumulates the distance data corresponding to the displacement data from the increase / decrease of the distance output from the laser ranging unit 33, and the displacement data and distance The pitch between the plurality of protrusions B is calculated from the data.

  Although the embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to the illustrated embodiments. Various modifications and variations can be made to the illustrated embodiment within the same range as the present invention or within an equivalent range.

  The pitch measurement structure according to the present invention is advantageously used in automobiles, machines, and other production processes.

10 pitch measurement structure, 11 shaft, 12 motor,
13, 33 Laser ranging unit, 14 computer,
15 motor controller, 16 encoder, 20 pitch measurement structure,
32 drive unit, 33 laser ranging unit, 34 pitch calculation unit.

Claims (8)

A rotating body having a circular base and a plurality of protrusions arranged at equal intervals in the circumferential direction on the outer periphery of the base is a measurement object,
A shaft portion that rotatably supports the rotating body;
A drive unit that rotationally drives the shaft part;
The rotating body that rotates together with the shaft portion is irradiated with a laser spot beam that draws a predetermined linear trajectory, and the distance to the protrusion that crosses the laser spot beam is measured a plurality of times based on the reflected light from the rotating body. A laser distance measuring unit for output,
The distance data output from the laser distance measuring unit is accumulated, the angle data corresponding to the distance data is accumulated from the rotation condition of the shaft portion, and the pitch between the plurality of protrusions is calculated from the angle data and the distance data. A pitch measurement structure comprising a pitch calculation unit for calculating.   The pitch measurement structure according to claim 1, further comprising an encoder that measures an angle of the shaft portion and outputs the angle to the pitch calculation unit.   The pitch measurement structure according to claim 2, wherein the resolution of the angle measured by the encoder is finer than 1/10 of the maximum allowable error of the pitch.   The pitch measurement structure according to claim 1, further comprising a motor control unit that rotates the driving unit at a constant speed.   The pitch measurement structure according to any one of claims 1 to 4, wherein the predetermined linear trajectory forms an acute angle with respect to a reference line passing through an irradiation port of the laser distance measuring unit and a rotation center of the shaft unit. The plurality of protrusions include a first protrusion and a second protrusion arranged adjacent to each other,
The laser spot beam is applied to the tip of the first projection rotating around the shaft portion and the intermediate portion connecting the tip and the root of the second projection in this order or in the reverse order. The pitch measurement structure according to claim 5, which collides.   The pitch measurement structure according to any one of claims 1 to 6, wherein a resolution of a distance measured by the laser ranging unit is finer than 1/10 of a maximum allowable error of pitch. An object having a base portion extending in the longitudinal direction and a plurality of protrusions arranged at equal intervals over the longitudinal direction on the base portion is a measurement object.
A drive unit for displacing the object in the longitudinal direction;
A predetermined linear trajectory that forms an acute angle with respect to the longitudinal direction is defined, and a laser spot beam that draws the linear trajectory is applied to the object that is displaced in the longitudinal direction, and based on reflected light from the object, A laser distance measuring section for measuring and outputting the distance to the protrusion traversing the laser spot beam a plurality of times;
The distance data output from the laser distance measuring unit is accumulated, the displacement data corresponding to the distance data of the object is accumulated from the displacement condition of the driving unit, and between the plurality of protrusions from the displacement data and the distance data A pitch measurement structure comprising a pitch calculation unit that calculates the pitch of the pitch.

Images