Shape measurement system and shape measurement method

Abstract

To measure a tooth profile, a tooth muscle and a diameter of a gear regardless of a diameter of the gear.SOLUTION: The present disclosure proposes a shape measurement system that measures a shape of a gear, as an example, the shape measurement system including a reference jig having a gear placement surface on which the gear to be measured is placed, at least one optical sensor that irradiates the reference jig and the gear with light to make measurement, a linear motion stage that linearly moves the reference jig and the gear in a direction along the gear placement surface, and a controller that outputs a measurement result of the shape of the gear on the basis of measurement data by at least one optical sensor. The linear motion stage and the at least one optical sensor are configured so that an area over the reference jig and the gear across the gear placement surface is irradiated with the light from the optical sensor when the reference jig and the gear are moved straight on the linear motion stage. The controller applies alignment data for known contour shape data of the measurement data of the reference jig to the measurement data of the gear to acquire the shape of the gear.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a shape measurement system and a shape measurement method.

Background Art

[0002] Power transmission devices are core components of various products such as automobiles, construction machinery, and aircraft. The machining accuracy of gears is an important item that determines the performance of power transmission devices. In order to ensure transmission performance, quality control of gear shapes is essential. In particular, tooth profile, tooth flanks, and diameter are directly related to the meshing of gears, so they need to be machined with high precision. For example, for a gear of accuracy class N9 defined in JIS B 1702-1, when the dimensions are a diameter of 500 mm and a tooth thickness of 20 mm, the tooth flank error is specified to be within 34 μm. Thus, gears require high machining accuracy, so precise measurement is necessary for quality control of gear shapes. On the other hand, in order to achieve 100% inspection on the production line, it is desirable that the measurement time is short.

[0003] As for gear measurement, the method using a contact probe is the mainstream. This method measures the gear shape by applying a probe to the tooth surface and moving the probe or rotating the gear. However, according to this method, although high-precision measurement can be performed, there is a problem that the measurement time is long.

[0004] Under such a background, in order to provide a measurement method with high precision and short time, in recent years, shape measurement systems using non-contact methods such as optical sensors have been proposed. For example, in Patent Document 1, a device is proposed in which a plurality of optical sensors are oriented with respect to a gear and the gear is rotated to measure the entire circumference shape.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] However, Patent Document 1 has a problem in that, because the measurement is taken while the gear is rotating, if an angular error occurs in the rotary encoder, the measurement accuracy deteriorates in proportion to the size of the gear. For example, if the gear diameter is 500 mm, an angular error of 10 seconds (10° / 3600) in the encoder results in a measurement error of 12 μm. In light of these circumstances, this disclosure provides a shape measurement technology that can measure the tooth profile, tooth trace, and diameter of a gear with high precision, regardless of the gear size. [Means for solving the problem]

[0007] To solve the above problems, this disclosure proposes a shape measurement system for measuring the shape of a gear, comprising: a reference fixture having a gear mounting surface on which the gear to be measured is placed; at least one optical sensor that performs measurement by irradiating the reference fixture and the gear with light; a linear motion stage that moves the reference fixture and the gear in a straight line in a direction along the gear mounting surface; and a controller that outputs the measurement result of the gear shape based on the measurement data from at least one optical sensor. The linear motion stage and at least one optical sensor are configured such that when the reference fixture and the gear are moving in a straight line on the linear motion stage, the light from the optical sensor is irradiated across the reference fixture and the gear, with the gear mounting surface in between. The controller acquires the shape of the gear by applying alignment data of the measurement data of the reference fixture to the measurement data of the gear.

[0008] Further features relating to this disclosure will become apparent from the description herein and the accompanying drawings. Furthermore, aspects of this disclosure are achieved and realized through elements and various combinations of elements and the modes of the claims described herein and the accompanying claims. Note that the description herein is merely a typical example and does not limit the claims or applications of this disclosure in any way. [Effects of the Invention]

[0009] According to the technology disclosed herein, a reference jig with a known shape is measured simultaneously with the gear, and the reference jig is used as a reference for alignment when synthesizing partial shape data. This eliminates the influence of the rotary encoder's angular error on the synthesis accuracy of the gear's entire circumference shape. Therefore, the gear's entire circumference shape can be measured and evaluated with high accuracy, regardless of the gear's size. [Brief explanation of the drawing]

[0010] [Figure 1] This figure shows a schematic example of the top view configuration of the shape measurement system 1 according to the first embodiment. [Figure 2] This figure shows a schematic front view of the shape measurement system 1 according to the first embodiment. [Figure 3] This is a flowchart illustrating the gear measurement process according to the first embodiment. [Figure 4] This figure shows the measurement results of arbitrary cross-sections of the gear 100 and the reference fixture 101, as measured by optical sensors 201 and 202 in step S102 of Figure 3. [Figure 5] This diagram illustrates the concept of combining partial shape data of the gear 100 and the reference jig 101 measured by the optical sensor 201. [Figure 6] This diagram illustrates the concept of synthesizing partial shape data of the gear 100 and the reference fixture 101 measured by the optical sensor 202. [Figure 7] This figure shows an example of the full circumference shape of gear 100 obtained by combining partial shape data of gear 100 and reference fixture 101 measured by optical sensors 201 and 202. [Figure 8] This figure (top view) shows a schematic configuration example of the shape measurement system 1A according to the second embodiment. [Figure 9] This is an enlarged view (top view) of the area around the gear 100 of the shape measurement system 1A according to the second embodiment. [Figure 10] This figure shows a schematic front view of the measurement system 1A according to the second embodiment. [Figure 11] This is a flowchart for explaining gear measurement processing according to the second embodiment. **Mode for Carrying Out the Invention**

[0011] In the present embodiment, a gear to be measured placed on a reference jig with known contour shape and dimensions is measured with an optical sensor together with the reference jig, coordinate conversion values (translation and rotation movements) are obtained based on the measurement data of the reference jig and the coordinate data of the reference jig in the virtual space, and the gear shape is drawn (shape synthesis) by applying the coordinate conversion values to the measurement data of the gear, and the shape and dimensions of the target gear are measured (calculated).

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In the accompanying drawings, functionally identical elements may sometimes be denoted by the same reference numerals. Note that the accompanying drawings show specific embodiments and implementation examples in accordance with the principles of the present disclosure, but these are for understanding the technology of the present disclosure and are not used to limit the interpretation of the technology of the present disclosure.

[0013] In the present embodiment, although the description is made in sufficient detail for those skilled in the art to implement the present disclosure, other implementations and forms are also possible, and it is necessary to understand that changes in configuration and structure and replacement of various elements are possible without departing from the scope and spirit of the technical idea of the present disclosure. Therefore, the following description should not be construed as being limited thereto.

[0014] Furthermore, embodiments of the present disclosure may be implemented by software running on a general-purpose computer as will be described later, or may be realized by dedicated hardware or a combination of software and hardware.

[0015] (1) First Embodiment The first embodiment will be described with reference to FIGS. 1 to 7. <Configuration Example of Shape Measurement System 1> FIG. 1 and FIG. 2 are a top view and a front view respectively showing a schematic configuration example of the shape measurement system 1 according to the present embodiment.

[0016] The shape measurement system 1 measures the gear 100, and includes a reference jig 101 with a known shape used for alignment during the synthesis of the entire circumference shape of the gear, a fixing mechanism (not shown) for the gear 100 and the reference jig 101, a rotary stage 102, a linear stage 103, a controller 104, a computer 105, and optical sensors 201 and 202 that measure the shapes of the gear 1 and the reference jig 101 using the optical cutting method. Here, the controller 104 and the computer 105 are separated, but the computer 105 may be configured to have the functions of the controller 104. Also, in the present embodiment, two optical sensors are provided, but three or more may be provided.

[0017] The material of the gear 100 can be, for example, steel. The gear specifications can be, for example, a module number of 15, a tooth number of 12, a height of 60 mm, and an accuracy of N9 class. In the case of the illustrated gear specifications, the tip circle diameter is 215.8 mm, the tooth thickness is 33.7 mm, the allowable error of the tooth profile is 60 μm, and the allowable error of the tooth flank is 36 μm. The accuracy of the diameter is about the general tolerance, and in the case of the gear 100, the tolerance is 200 μm.

[0018] Optical sensors 201 and 202 are arranged to measure the tooth surfaces of gear 100 in different orientations (sides). For example, in this embodiment, optical sensors 201 and 202 are optical devices including a light-emitting unit (light source) including a semiconductor laser, an optical system including a light-emitting lens and a light-receiving lens, and a light-receiving unit (light-receiving element) that receives light focused by the light-receiving lens. In this embodiment, optical sensors 201 and 202 are arranged symmetrically across a straight line 12 that passes through the center O of the reference jig 101 and is parallel to the y-axis (direction of movement of the linear stage 103). The distance between optical sensor 201 and the tooth root of gear 100, i.e., line segment S1-R1 in Figure 1, is 180 mm. Similarly, the line segment S2-R1' between optical sensor 202 and the tooth root of gear 100 is also 180 mm. To unify the measurement accuracy, it is desirable that optical sensors 201 and 202 be the same sensor. Furthermore, the linearity of optical sensors 201 and 202 is ±0.01%. When the tooth height of gear 100 is 33.7 mm, the measurement accuracy in the direction of the optical axis 21a is ±3.37 μm. Since the measurement accuracy is less than 1 / 10 of the tolerances of tooth profile, tooth trace, and diameter, it can be said that optical sensors 201 and 202 have sufficient measurement accuracy.

[0019] The gear 100 is placed on the gear mounting surface 108 of the reference jig 101 and fixed to the reference jig 101 (the fixing mechanism is not shown). The reference jig 101 is a regular polygonal prism of known shape with the same number of vertices as the number of teeth of the gear 100, and in this embodiment, it is a regular dodecagonal polygonal prism. The reference jig 101 also has its bottom surface (top surface) as the gear mounting surface 108. In order for optical sensors 201 and 202 to measure the gear 100 and the reference jig 101, the tooth traces T1-R1 of the gear 100 and the contour of the reference jig 101 must be within the measurement range MR1 in the direction of the optical axis 21a. Similarly, the tooth traces T1'-R1' of the gear 100 and the contour of the reference jig 101 must be within the measurement range MR2 in the direction of the optical axis 22a of optical sensor 202. In this embodiment, since the measurement ranges MR1 ​​and MR2 are 80 mm, the length of opposite sides of the reference jig 101 is set to 220 mm, and the gear 100 is placed on the reference jig 101 such that the tooth traces T1-R1 and T1'-R1' of the gear 100 and the contour of the reference jig 101 are contained within the measurement ranges MR1 ​​and MR2.

[0020] Furthermore, the height of the reference jig 101 is 30 mm, and the accuracy of its shape is approximately 1 / 10 of the gear diameter tolerance, i.e., 20 μm. Since the gear 100 and the reference jig 101 are measured with the same optical sensor, it is desirable that their surface reflection characteristics are identical.

[0021] The reference fixture 101 is mounted on the rotary stage 102. The rotation axis 11 of the rotary stage 102 and the center point O of the reference fixture 101 are aligned. The rotary stage 102 is mounted on the linear stage 103. The linear stage 103 is driven in the y-axis direction in Figure 1. Optical sensors 201 and 202 measure a portion of the gear 100 as the linear stage 103 moves in the y-axis direction.

[0022] The computer 105 reads a program (not shown) from memory to execute the process shown in the flowchart (see Figure 3) described later, and instructs the controller 104 to perform the necessary operational control based on the program. In response to the instructions given by the computer 105, the controller 104 controls the rotation of the rotary stage 102 (operation of the rotary encoder), the linear motion of the linear motion stage 103, the illumination of light by the optical sensors 201 and 202, and so on.

[0023] As shown in Figure 2, the optical sensors 201 and 202 are installed so that the longitudinal direction of the spread (radiation angle φ) of the line beams 21 and 22 emitted from the sensors is parallel to the z-axis. Here, the radiation angle φ of the line beams 21 and 22 is, for example, 26.7°, and the length (longitudinal length) of the line beams 21 and 22 on the tooth surface of the gear 100 is approximately 80 mm. In this embodiment, the irradiation range in the line direction of the line beams 21 and 22 is set so that they irradiate across the gear 100 and the side surface of the reference jig 101, with the gear mounting surface 108 of the reference jig 101 in between. This makes it possible to measure the shapes of the gear 100 and the reference jig 101 simultaneously.

[0024] <Gear measurement processing> Figure 3 is a flowchart illustrating the gear measurement process according to the first embodiment. In the following description, the main operator for each step is either the controller 104 or the computer 105. If the computer 105 has the functions of the controller 104, then the main operator is the computer 105.

[0025] (i) Step S101 After the user (operator) places and fixes the gear 100 to be measured on the reference jig 101, and then inputs a measurement start command using the input device of the computer 105, the controller 104 receives the measurement start command along with information on the distance traveled by the linear motion stage 103 during one measurement process (one movement step) in one measurement process from the computer 105, and initializes the operation of the optical sensors 201 and 202, the rotary stage 102, and the linear motion stage 103.

[0026] (ii) Step S102 The controller 104 controls the linear motion stage 103 and optical sensors 201 and 202 to move the gear 100 and reference fixture 101 in a straight line for a distance equivalent to one movement step in the y-axis direction of Figure 1, while measuring the tooth surface of the gear 100 and the partial shape of the reference fixture 101. The measurement range corresponds to the distance of one movement step and includes at least one tooth of the gear 100 and one vertex of the reference fixture 101. The controller 104 sends the data acquired in this single measurement process (measurement data of the reference fixture 101 and measurement data of the gear 100) to the computer 105. The computer 105 stores the received measurement data in memory (not shown) until all data has been acquired.

[0027] (iii) Step S103 Computer 105 checks if the measurement process has been completed for the entire circumference of gear 100. If measurement data for the entire circumference of gear 100 has been acquired (if the answer is Yes in step S103), the process proceeds to S105. If measurement data for the entire circumference of gear 100 has not yet been acquired (if the answer is No in step S103), the process proceeds to S104.

[0028] (iv) Step S104 The controller 104, in response to a command from the computer 105, controls the rotating stage 102 to rotate the gear 100 and the reference jig 101 by an arbitrary angle around the rotation axis 11. This rotation angle can be, for example, 360° / N based on the number of teeth N of the gear 100. If the number of teeth N=12, then 360° / 12=30°. By measuring each tooth individually with a rotation angle of 360° / N, the incidence conditions of the line beams 21 and 22 become the same for all teeth of the gear 100. As described above, any angle can be used for the rotation angle, but by setting the rotation angle to 360° / N, the positional relationship between each tooth of the gear 100 and the optical sensor 201 or optical sensor 202 can be made reproducible in each measurement, so that each tooth can be measured under the same optical conditions. In other words, the measurement conditions become the same for all teeth of the gear 100.

[0029] (v) Step S105 The computer 105 terminates the measurement process once it confirms that it has received measurement data for the entire circumference of the gear from the controller 104.

[0030] (vi) Step S106 The computer 105 synthesizes the measured partial shapes of the gear 100 to obtain the full circumference shape of the gear. At this time, the partial shape of the reference jig 101, which was measured simultaneously with the gear 100 in step S102, is used as a reference for alignment when synthesizing the full circumference shape of the gear.

[0031] <Composite processing of the entire circumference of the gear> The process of combining the full circumference shape of the gear will be explained with reference to Figures 4 to 7. Figure 4 shows the measurement results of arbitrary cross-sections of the gear 100 and reference fixture 101 measured by optical sensors 201 and 202 in step S102 of Figure 3. In Figure 4, the dotted lines show the actual shapes of the gear 100 and reference fixture 101, and the solid lines show the measurement range of the gear 100 and reference fixture 101. In step S102 of Figure 3, the linear motion stage 103 is moved in the y-axis direction, and optical sensors 201 and 202 irradiate line beams 21 and 22 in the x-axis direction. However, the linear motion stage 103, optical sensors 201 and 202, line beams 21 and 22 are omitted in Figure 4.

[0032] The range measured in step S102 is range A1 and range A1' in the y direction of approximately 40 mm in Figure 4 (equivalent to one movement step of the linear motion stage). The measured shape 301 of the reference fixture 101 measured by the optical sensor 201 is B1-V1-C1 including vertex V1, and the measured shape 401 of the gear 100 is Bg1-R1-T1-Cg1 including tooth traces R1-T1. In addition, the measured shape 301' of the reference fixture 101 measured by the optical sensor 202 is B1'-V6-C1' including vertex V6. The measured shape 401' of the gear 100 is Bg1'-R1'-T1'-Cg1' including tooth traces R1'-T1'.

[0033] Figure 5 shows a concept for synthesizing partial shape data of the gear 100 and the reference fixture 101 measured by the optical sensor 201. The known contour shape 101' of the reference fixture 101 is drawn in the virtual space (operation coordinates) for point cloud synthesis. In Figure 5, the contour shape 101' is shown as a dotted line. The measured shape 301 of the reference fixture 101 measured in step S102 of Figure 3 is transformed in coordinates so that it overlaps with the region containing vertex V1 of the contour shape 101' in the virtual space. That is, for example, first, a translation amount is calculated to superimpose the measured data (coordinates) of vertex V1 of the reference fixture 101 onto the point (coordinates) corresponding to vertex V1 on the contour shape 101'. Next, a rotational translation amount (rotation angle) is calculated to superimpose the line segment V1-C1 from the measured data onto the line segment corresponding to line segment V1-C1 in the contour shape 101'. This translational translation amount and rotational translation amount are calculated for each measurement data and become the coordinate transformation values ​​for each measurement data. Then, the same coordinate transformation as for the measurement shape 301 (partial measurement shape) of the reference jig is performed on the partial shape 401 of the gear 100. Similarly, the partial shape data of the gear 100 and the reference jig 101, which include vertices V2 to V12 of the reference jig 101 in their measurement range, are combined based on the contour shape 101'. Through the above processing, it becomes possible to combine the tooth surface shape of the gear 100 measured by the optical sensor 201.

[0034] Furthermore, the tooth surface measured by the optical sensor 202 is subjected to the same synthesis process as the tooth surface measured by the optical sensor 201. Figure 6 is a diagram illustrating the concept of synthesizing partial shape data of the gear 100 and the reference jig 101 measured by the optical sensor 202. As shown in Figure 6, the known contour shape 101' of the reference jig 101 is drawn as a dotted line in the virtual space for point cloud synthesis. The measured shape 301' (partial measured shape) of the reference jig 101 measured in step S102 of Figure 3 is transformed in coordinates so that it overlaps with the region containing vertex V6 of the contour shape 101' in the virtual space. At this time, the same coordinate transformation as the measured shape 301' of the reference jig 101 is also performed on the partial shape 401' of the gear 100. Similarly, the partial shapes of the gear 100 and the reference jig 101, including vertices V7~V12 and V1~V5 of the reference jig 101 in their measurement range, are synthesized based on the contour shape 101'. As a result, it becomes possible to synthesize the tooth surface shapes of the gear 100 measured by the optical sensor 202.

[0035] Figure 7 shows an example of the full circumference shape of gear 100 obtained by combining partial shape data of gear 100 and reference jig 101 measured by optical sensors 201 and 202. From Figure 7, it can be seen that the measured shape 100' of gear 100 is a shape obtained by combining the full circumference shapes of one side of the gear shown in Figures 5 and 6. In this way, by using a common reference jig 101 as a reference for alignment with the partial shape data measured by optical sensors 201 and 202, it becomes possible to combine the full circumference shapes of both tooth surfaces of the gear.

[0036] <Effects of the First Embodiment> According to the first embodiment, the following effects can be obtained. (i) By moving the gear 100 in a straight line and taking measurements, the measurement accuracy remains constant regardless of the gear size. (ii) When synthesizing partial data of the gear 100, the reference jig 101 is used as a reference for alignment, making it possible to accurately evaluate the entire circumference shape of the gear 100.

[0037] (2) Second embodiment Next, as a second embodiment, we will describe an example in which the sensor arrangement has been changed.

[0038] <Example configuration of shape measurement system 1A> (i) Example of overall structure Figure 8 is a diagram (top view) showing a schematic configuration example of the shape measurement system 1A according to the second embodiment.

[0039] The shape measurement system 1A measures a gear 100 as the measurement target and includes a reference jig 101a with a known shape used for alignment when synthesizing the full circumference shape of the gear, a fixing mechanism (not shown) for the gear 100 and the reference jig 101a, a rotating stage 102, a controller 104, a computer 105, optical sensors 201 and 202 for measuring the shapes of the gear 100 and the reference jig 101, and linear stages 106 and 107 for driving the optical sensors 201 and 202 in the z-axis direction. Although the controller 104 and computer 105 are separated here, the computer 105 may be configured to perform the functions of the controller 104. Also, although two optical sensors are provided in this embodiment, three or more may be provided.

[0040] The dimensions, shape, and material of the gear 100 are the same as those of the first embodiment. The reference jig 101a is a regular polygonal prism of known shape with the same number of vertices as the number of teeth of the gear 100, and in the second embodiment it is a regular dodecagonal polygonal prism.

[0041] Furthermore, the specifications of the optical sensors 201 and 202 are the same as those in the first embodiment. The optical sensors 201 and 202 are installed so that the longitudinal direction of the spread (radiation angle ψ) of the line beams 21 and 22 emitted from the sensors is parallel to the y-axis in Figure 8. The optical sensors 201 and 202 measure the tooth surfaces of the gear 100 in different orientations (sides). In this embodiment, the optical sensors 201 and 202 are arranged symmetrically across a straight line 12a that passes through the center Oa of the reference jig 101a and is parallel to the y-axis.

[0042] The gear 100 is placed on the reference fixture 101a and fixed to the reference fixture 101a (the fixing mechanism is not shown). The reference fixture 101a is mounted on the rotary stage 102 such that its center point Oa coincides with the rotation axis 11 of the rotary stage 102.

[0043] (ii) Arrangement and dimensions Figure 9 is an enlarged view (top view) of the area around gear 100 of the shape measurement system 1A. Using Figure 9, the arrangement relationship (example) between optical sensors 201 and 202, gear 100, and reference jig 101a, as well as the dimensions (example) of reference jig 101a, will be explained.

[0044] In the second embodiment, the optical sensor 201 is positioned such that its principal optical axis 21a passes through the apex T1 of the tooth tip of the gear 100, and S1-T1 is 90 mm. Similarly, the optical sensor 202 is positioned such that its principal optical axis 22a passes through the apex T1' of the tooth tip of the gear 100, and S2-T1' is 90 mm.

[0045] In order for the optical sensor 201 to measure the gear 100 and the reference fixture 101a, the tooth traces T1-R1 of the gear 100 and the contour of the reference fixture 101a must be within the measurement range MR1 of the optical sensor 201 in the direction of the optical axis 21a. Similarly, the tooth traces T1'-R1' of the gear 100 and the contour of the reference fixture 101a must be within the measurement range MR2 of the optical sensor 202 in the direction of the optical axis 22a. In this embodiment, since the measurement ranges MR1 ​​and MR2 are set to 80 mm, the diagonal length of the reference fixture 101a is set to 220 mm, so that the tooth traces T1-R1 and the contour of the reference fixture 101a are within the measurement range MR1, and the tooth traces T1'-R1' and the contour of the reference fixture 101a are within the measurement range MR2.

[0046] Furthermore, since the vertex of the reference jig 101a is used as the reference point for alignment, the vertex V1 of the reference jig 101a and the tooth traces T1-R1 of the gear 100 must be included in the y-axis irradiation range of the line beam 21. Similarly, the vertex V5 of the reference jig 101a and the tooth traces T1'-R1' of the gear 100 must be included in the y-axis irradiation range of the line beam 22.

[0047] The reference jig 101a and gear 100 are positioned to satisfy the above conditions. The height of the reference jig 101a is 30 mm, and the accuracy of its shape is approximately 1 / 10 of the gear diameter tolerance, i.e., 20 μm. Since the gear 100 and the reference jig 101a are measured with the same optical sensor, it is desirable that their surface reflection characteristics are identical.

[0048] (iii) Examples of front view configurations Figure 10 shows an example of a front view configuration of the measurement system 1A according to the second embodiment. Optical sensors 201 and 202 are fixed to linear stages 106 and 107, respectively, and move in the z-axis direction to measure the shape of the gear 100 and the reference fixture 101a. Optical sensor 201 is controlled to move in the z-axis direction so that its measurement range 31 includes the gear 100 and the reference fixture 101a. Similarly, optical sensor 202 is also controlled to move in the z-axis direction so that its measurement range 32 includes the gear 100 and the reference fixture 101a.

[0049] <Gear measurement processing> Figure 11 is a flowchart illustrating the gear measurement process according to the second embodiment. In the following description, the operating entity for each step is either the controller 104 or the computer 105. If the computer 105 has the functions of the controller 104, then the operating entity is the computer 105.

[0050] (i) Step S201 After the user (operator) places and fixes the gear 100 to be measured on the reference jig 101a, and then inputs a measurement start command using the input device of the computer 105, the controller 104 receives the measurement start command along with information on the distance traveled by the linear stages 106 and 107 during one measurement process (measurement range 31 and 32) from the computer 105, and initializes the operation of the optical sensors 201 and 202, the rotary stage 102, and the linear stages 106 and 107.

[0051] (ii) Step S202 The controller 104 controls the linear stages 106 and 107 and the optical sensors 201 and 202, and measures the tooth surface of the gear 100 and the partial shape of the reference jig 101a while the linear stages 106 and 107 move the optical sensors 201 and 202 in a straight line for a predetermined distance in the z-axis direction of Figure 10. The distance traveled by the linear stages 106 and 107 in the z-axis direction corresponds to the distances of the measurement ranges 31 and 32 (measurement ranges 31 and 32 are the same range). In other words, with a single measurement operation, the optical sensors 201 and 202 are moved using linear stages 106 and 107 so that data can be acquired for the height of the measurement ranges 31 and 32, for at least a portion of the tooth traces T1-R1 of the gear 100 and the vertex V1 of the reference fixture 101a and its adjacent edges using line beam 21, and for at least a portion of the tooth traces T1'-R1' of the gear 100 and the vertex V5 of the reference fixture 101a and its adjacent edges using line beam 22.

[0052] The controller 104 sends the data acquired in that single measurement process (measurement data of the reference jig 101a and measurement data of the gear 100) to the computer 105. The computer 105 stores the received measurement data in memory (not shown) until all data has been acquired.

[0053] (iii) Step S203 The computer 105 checks whether the measurement process has been completed for the entire circumference of the gear 100. If measurement data for the entire circumference of the gear 100 has been acquired (if the answer is Yes in step S203), the process proceeds to step S205. If measurement data for the entire circumference of the gear 100 has not yet been acquired (if the answer is No in step S203), the process proceeds to step S204.

[0054] (iv) Step S204 The controller 104, in response to a command from the computer 105, controls the rotating stage 102 to rotate the gear 100 and the reference jig 101a around the rotation axis 11 by an arbitrary angle. This rotation angle can be, for example, 360° / N based on the number of teeth N of the gear 100. If the number of teeth N=12, then 360° / 12=30°. By measuring each tooth with a rotation angle of 360° / N, the incidence conditions of the line beams 21 and 22 become the same for all teeth of the gear 100. In other words, the measurement conditions become the same for all teeth of the gear 100.

[0055] As mentioned above, the rotation angle can be any angle, but by setting the rotation angle to 360° / N, the positional relationship between each tooth of the gear 100 and the optical sensor 201 or optical sensor 202 can be made reproducible in each measurement run, so that the incidence conditions of the line beams 21 and 22 are the same for all teeth of the gear 100. In other words, the optical conditions (measurement conditions) can be made the same for all teeth of the gear 100.

[0056] (v) Step S205 The computer 105 terminates the measurement process once it confirms that it has received measurement data for the entire circumference of the gear from the controller 104.

[0057] (vi) Step S106 The computer 105 synthesizes the measured partial shapes of the gear 100 to obtain (draw) the full circumference shape of the gear. At this time, the partial shape of the reference jig 101a, which was measured simultaneously with the gear 100 in step S102, is used as a reference for alignment when synthesizing the full circumference shape of the gear. The method for synthesizing the full circumference shape of the gear 100 is the same as in the first embodiment, so the explanation is omitted.

[0058] <Effects of the second embodiment> According to the second embodiment, in addition to the above-mentioned effects (i) and (ii) of the first embodiment, the constraint on the measurement range in the height (tooth trace) direction of the gear 100 is relaxed. For example, even if the thickness (height) of the gear 100 increases, the gear 100 can be measured by adjusting (increasing) the movable range in the z direction of the optical sensors 201 and 202. This is because, in the first embodiment, the measurement range in the height direction of the gear 100 depended on the spread angle ψ of the line beams 21 and 22, but in the second embodiment, measurement is possible as long as it is within the operating range of the linear stages 106 and 107.

[0059] (3) Variant While the shape measurement process for external gears has been described in the first and second embodiments, the shape of internal gears can also be measured using the technology of this disclosure. More specifically, when measuring the shape of an internal gear, the above-described full-circumference shape synthesis process can be applied by adjusting the angles of the optical sensors 201 and 202 with respect to the xy plane to such an angle that light can be irradiated onto both the reference jig 101 or 101a and the internal gear.

[0060] (4) Summary (i) According to the technology of this disclosure, the gear 100 to be measured is placed on a reference jig 101 or 101a with a known contour shape, and measurement is performed by irradiating the reference jig 101 and the gear 100 with light using at least one optical sensor 201 or 202. The computer 105 then obtains the shape of the gear by applying the alignment data of the measurement data of the reference jig to the measurement data of the gear. Here, the gear mounting surface 108 of the reference jig is preferably larger than the circle defined by the outer diameter of the gear. The shape of the gear mounting surface 108 of the reference jig 101 or 101a can be a regular polygon with the same number of vertices as the number of teeth of the gear 100.

[0061] In this embodiment, the amount of deviation (amount of translation and rotation on the calculated coordinates: coordinate transformation value) from the known contour shape data of the reference jig 101 or 101a is calculated by aligning the measurement data of the reference jig 101 or 101a with the known contour shape data, and this is applied to the measurement data of the gear 100. Therefore, even if the mounting position of the gear 100 on the reference jig 101 or 101a is slightly off, it is possible to accurately synthesize the entire circumference shape of the gear 100.

[0062] (ii) In the shape measurement system 1 or 1A according to this embodiment, a rotating stage (including a rotary encoder) 102 can be used, similar to the prior art, on which a reference fixture 101 or 101a is placed and which rotates the gear 100 and the reference fixture 101 or 101a. In this case, the computer 105 rotates the rotating stage 102 by an arbitrary angle to operate the optical sensors 201 and 202, thereby acquiring one set of measurement data for the reference fixture 101 or 101a and the gear 100. The computer 105 then repeats the rotation by an arbitrary angle and the measurement operation by the optical sensors 201 and 202 to acquire measurement data for the entire circumference of the reference fixture 101 or 101a and the gear 100. The computer 105 then applies alignment data (amount of translation and rotation on the calculated coordinates: coordinate transformation values) of the measurement data for the entire circumference of the reference fixture 101 or 101a to the known contour shape data to acquire the full circumference shape of the gear 100. Since the measurement data from the reference jig 101 or 101a is used for alignment in this way, even when using the rotary stage 102 and rotary encoder, the adverse effect of the rotary encoder's angular error on the composite accuracy of the gear's overall shape can be eliminated. Therefore, the gear's overall shape can be evaluated with high accuracy, regardless of the size of the gear 100.

[0063] (iii) In the shape measurement system 1 or 1A according to this embodiment, a rotating stage 102 and linear stages 103, 106, and 107 can be used to move the reference fixture 101 or 101a on which the gear 100 is mounted and the optical sensors 201 and 202 in a linear direction perpendicular to the optical axis of the light from the optical sensors 201 and 202. In this case, the computer 105 operates the optical sensors 201 and 202 while moving the linear stages 103, 106, and 107 in a linear direction to acquire measurement data of a part of the gear 100 and a part of the reference fixture 101 or 101a, and then rotates the rotating stage 102 by an arbitrary angle to change the measurement location. The computer 105 then acquires measurement data of the entire circumference of the gear 100 and the reference fixture 101 or 101a by repeatedly acquiring local measurement data and changing the measurement location by rotation. Once measurement data for the entire circumference is acquired, the computer 105 applies alignment data (amount of parallel and rotational movement on the calculated coordinates: coordinate transformation values) from the measurement data for the entire circumference of the reference fixture 101 or 101a to the known contour shape data of the gear 100, thereby acquiring the full circumference shape of the gear 100. In this way, the gear 100 and optical sensors 201 and 202 are moved in a straight line to measure the three-dimensional shape, so the measurement accuracy depends on the accuracy of the optical sensors 201 and 202 and the linear motion stages 103 or 106 and 107, and does not depend on the diameter of the gear 100. In other words, it is possible to measure the tooth profile and tooth trace with high accuracy regardless of the gear size.

[0064] In the first embodiment, the linear motion stage 103 moves the reference jig 101 on which the gear 100 is mounted in a straight line in a direction parallel to the gear mounting surface 108 of the reference jig 101 (y-axis direction). The light emitted by the optical sensors 201 and 202 is configured to spread at a predetermined angle φ in the direction of movement of the linear motion stage 103 (y-axis direction).

[0065] In the second embodiment, the linear stages 106 and 107 move the optical sensors 201 and 202 linearly in the height direction (z-axis direction) of the reference jig 101a and the gear 100. The light emitted by the optical sensors 201 and 202 is configured to have a spread of a predetermined angle ψ in the direction of movement of the linear stages 106 and 107.

[0066] (iv) The functions of this embodiment can also be realized by software program code. In this case, a storage medium on which the program code is recorded is provided to a system or device, and the computer (or CPU or MPU) of that system or device reads the program code stored on the storage medium. In this case, the program code read from the storage medium itself realizes the functions of the embodiment described above, and the program code itself and the storage medium on which it is stored constitute the present disclosure. Examples of storage media for supplying such program code include flexible disks, CD-ROMs, DVD-ROMs, hard disks, optical disks, magneto-optical disks, CD-Rs, magnetic tapes, non-volatile memory cards, ROMs, etc.

[0067] Furthermore, based on the instructions in the program code, the operating system (OS) running on the computer may perform some or all of the actual processing, thereby realizing the functions of the embodiment described above. In addition, after the program code read from the storage medium is written to the computer's memory, the computer's CPU may perform some or all of the actual processing based on the instructions in the program code, thereby realizing the functions of the embodiment described above.

[0068] Furthermore, the program code for the software that realizes the functions of the embodiment may be distributed via a network and stored in a storage means such as a hard disk or memory of the system or device, or in a storage medium such as a CD-RW or CD-R, so that when in use the system or device's computer (or CPU or MPU) reads and executes the program code stored in the storage means or storage medium.

[0069] The processes and techniques described herein are not inherently related to any specific device and can be implemented by any suitable combination of components. Furthermore, a variety of general-purpose devices can be used. Dedicated devices may be constructed to perform the steps of the methods described herein. Also, various inventions can be formed by appropriate combinations of the multiple components disclosed in the embodiments. For example, some components may be removed from all the components shown in the embodiments. Furthermore, components from different embodiments may be combined as appropriate. This disclosure has been written in relation to specific examples, but these are for illustrative purposes only, not limitation, in all respects. Those skilled in the art will find that there are many suitable combinations of hardware, software, and firmware to implement this disclosure. For example, the software described can be implemented in a wide range of programming or scripting languages ​​such as assembler, C / C++, Perl, Shell, PHP, Java®, etc.

[0070] Furthermore, in the embodiments described above, the control lines and information lines shown are those deemed necessary for illustrative purposes, and not all control lines and information lines are necessarily shown in the actual product. All components may be interconnected.

[0071] In addition, other implementations of this disclosure will become apparent to those ordinary skill in the art from the description and embodiments of this disclosure. The description and examples are typical, and the scope and spirit of this disclosure are shown in the subsequent claims. [Explanation of symbols]

[0072] 1. 1A Shape Measurement System 11 Rotation axis 100 gears 101, 101a Reference fixture 102 Rotating Stage 103, 106, 107 Linear motion stage 104 Controller 105 Computers 108 Gear mounting surface 201, 202 Optical Sensors 21, 22 Line beam 21a, 22a Line beam optical axis 301, 301' Partial measurement shape of the reference jig 401, 401' Gear part measurement shape

Claims

1. A shape measuring system for measuring the shape of a gear, A reference jig having a gear mounting surface on which the gear to be measured is placed, At least one optical sensor that irradiates light onto the reference jig and the gear to perform measurements, A linear motion stage that moves the reference jig and the gear in a straight line in a direction along the gear mounting surface, The system includes a controller that outputs a measurement result of the gear shape based on measurement data from at least one optical sensor, The linear motion stage and the at least one optical sensor are configured such that, when the reference fixture and the gear are moving linearly on the linear motion stage, light from the optical sensor shines across the reference fixture and the gear, with the gear mounting surface in between. The controller acquires the shape of the gear by applying alignment data of the measurement data of the reference jig to the measurement data of the gear, Furthermore, the system includes a rotary stage that rotates the gear and the reference jig having the gear mounting surface using a rotary encoder. The aforementioned controller, The process involves rotating the rotating stage by an arbitrary angle to activate the optical sensor, thereby acquiring one measurement of the reference jig and the gear. A process to acquire measurement data of the entire circumference of the reference jig and the gear by repeatedly performing the rotation at the arbitrary angle and the measurement operation by the optical sensor, The process of obtaining the full circumference shape of the gear by applying the alignment data of the measurement data of the entire circumference of the reference jig to the known contour shape data, Execute Shape measurement system.

2. In claim 1, The diameter of the circle defined by the outer diameter of the gear mounting surface of the reference jig, The difference in diameter of the circle defined by the outer diameter of the gear is A shape measurement system whose measurement range is below that of the optical sensor.

3. In claim 1, The linear motion stage is configured to move the reference jig on which the gear is mounted and the optical sensor in a linear motion relative to each other in a direction perpendicular to the optical axis of the light from the optical sensor. The aforementioned controller, The process involves operating the optical sensor while moving the linear motion stage in a straight line to acquire measurement data of a part of the gear and a part of the reference jig, The process involves rotating the aforementioned rotating stage by an arbitrary angle to change the measurement location, A process to acquire measurement data for the entire circumference of the gear and the reference jig by repeatedly performing the process of acquiring the measurement data and the process of changing the measurement location, The process of obtaining the full circumference shape of the gear by applying the alignment data of the measurement data of the entire circumference of the reference jig to the known contour shape data, A shape measurement system that performs this operation.

4. In claim 3, The linear motion stage moves the reference jig on which the gear is mounted in a straight line in a direction parallel to the gear mounting surface of the reference jig. A shape measurement system in which the light emitted by the optical sensor has a predetermined angle spread in the direction of movement of the linear stage.

5. In claim 3, The linear motion stage moves the optical sensor linearly in the height direction of the reference jig and the gear, A shape measurement system in which the light emitted by the optical sensor has a predetermined angle spread in the direction of movement of the linear stage.

6. In claim 2, A shape measurement system in which the shape of the gear mounting surface of the reference jig is a regular polygon having the same number of vertices as the number of teeth of the gear.

7. A shape measurement method for measuring the shape of a gear, The steps include: placing the gear to be measured on a reference jig whose contour shape is known; The steps include: using at least one optical sensor to irradiate the reference jig and the gear with light and perform measurements; The process includes the step of using a controller to generate a measurement result of the gear shape based on measurement data from at least one optical sensor, When the reference jig and the gear are moving in a straight line on a linear motion stage that moves the gear in a straight line, light from the optical sensor is shone across the reference jig and the gear, with the gear mounting surface on which the gear is placed in between. In the step of generating the measurement results of the gear shape, the controller obtains the gear shape by applying alignment data of the measurement data of the reference fixture to the known contour shape data of the gear measurement data, Furthermore, the controller allows, A step of acquiring one measurement of the reference jig and the gear by rotating a rotary stage that rotates the gear and the reference jig having the gear mounting surface by a rotary encoder by an arbitrary angle and operating the optical sensor, A step of acquiring measurement data of the entire circumference of the reference jig and the gear by repeatedly performing the rotation at the arbitrary angle and the measurement operation by the optical sensor. The step of obtaining the full circumference shape of the gear by applying the alignment data of the measurement data of the entire circumference of the reference jig to the known contour shape data, Having, Method for measuring shape.

8. Claim 7 further, The steps include: operating the optical sensor while moving a linear motion stage that moves the reference jig on which the gear is mounted and the optical sensor in a linear motion relative to each other in a direction perpendicular to the optical axis of the light from the optical sensor, thereby acquiring measurement data of a part of the gear and a part of the reference jig; The steps include: placing the aforementioned reference jig on it and rotating the rotating stage that rotates the gear and the aforementioned reference jig by an arbitrary angle to change the measurement location; The step includes repeatedly acquiring the aforementioned measurement data and changing the measurement location to acquire measurement data for the entire circumference of the gear and the reference jig, The controller is a shape measurement method that obtains the full circumference shape of a gear by applying alignment data of the measurement data of the entire circumference of the reference jig to the known contour shape data of the gear, thereby obtaining the full circumference shape of the gear.

9. In claim 8, In the step of acquiring measurement data of a part of the gear and a part of the reference fixture, the controller controls the linear motion stage to move the reference fixture on which the gear is mounted in a straight line in a direction parallel to the gear mounting surface of the reference fixture. A shape measurement method wherein the light emitted by the optical sensor has a predetermined angle of spread in the direction of movement of the linear stage.

10. In claim 8, In the step of acquiring measurement data of a part of the gear and a part of the reference fixture, the controller controls the linear motion stage to move the optical sensor linearly in the height direction of the reference fixture and the gear, A shape measurement method wherein the light emitted by the optical sensor has a predetermined angle of spread in the direction of movement of the linear stage.

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