Dimension measurement device for cylindrical workpiece and positioning method for the same

Abstract

To provide a dimension measurement device having a simple structure.SOLUTION: A dimension measurement device that measures a diameter of a cylindrical workpiece (70), comprises: a pair of first contact elements (13A) that is arranged outside the cylindrical workpiece (70) and pressed against the cylindrical workpiece (70); and a pair of second contact elements (13B) that is arranged outside the cylindrical workpiece (70) separately from the first contact elements (13A) and pressed against the cylindrical workpiece (70) to measure a diameter different from that measured by the first contact elements (13A). When an axis orthogonal to a longitudinal center axis (70a) of the cylindrical workpiece (70) is defined as an orthogonal center axis (70b), a first center axis (11A) linking the pair of first contact elements (13A) and a second center axis (11B) linking the pair of second contact elements (13B) are arranged at positions line-symmetric with respect to the orthogonal center axis (70b). By pressing the cylindrical workpiece 70 by the pair of contact elements (13A, 13A) and the different pair of contact elements (13B, 13B), positioning of the cylindrical workpiece (70) becomes possible.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a dimension measuring device for measuring the diameter of a cylindrical workpiece and a positioning method for the device. [Background technology]

[0002] [Terminology] Over-ball diameter: Abbreviated as OBD. This is the diameter used to measure gear tooth thickness. Diameter of cylindrical workpiece: A general term for OBD, large diameter larger than OBD, and small diameter smaller than OBD.

[0003] [Conventional overball diameter measuring device] Various dimension measuring devices for measuring the diameter of cylindrical workpieces have been put into practical use, one of which is an over-ball diameter measuring device (see, for example, Patent Document 1 (FIG. 1)).

[0004] When a gear is manufactured, the tooth thickness may be larger or smaller than the specified value. If the tooth thickness is larger or smaller than the specified value by more than the allowable value, the gear will be rejected. In addition to directly measuring the gear tooth thickness with a caliper, a measurement method using the overball diameter is also known.

[0005] [Over-ball diameter measurement method] Prepare two balls of a specified diameter. Insert the two balls into the gear tooth gap at a 180° pitch. If the tooth thickness is large, the tooth gap will be small and the balls will fit shallowly. If the tooth thickness is small, the tooth gap will be large and the balls will fit deep. Measure the outsides of the two balls together (or the insides together). Based on this measurement, it can be determined whether the tooth thickness is within the specified value.

[0006] [Summary of the prior art] In the over-ball diameter measuring device disclosed in Patent Document 1, a gear is attached to the main shaft (θ axis). The gear rotates around the θ axis. A pair of contacts (balls) advances and retreats along axes (XU axis, XL axis, hereinafter referred to as X axis for convenience) that are perpendicular to the θ axis. The pair of balls is movable along an orthogonal axis (Y axis) that is perpendicular to the θ axis and also perpendicular to the XU axis.

[0007] [Advantages of conventional technology] If the pair of balls were immobile along the Y axis, the balls might not smoothly fit into the gear tooth grooves because the gear is positioned by the main shaft (θ axis). In this case, the technique of Patent Document 1 has the advantage that the ball moves along the Y axis, resulting in the ball smoothly entering the gear tooth grooves.

[0008] For convenience, the mechanism that moves the ball along the X axis will be called the X-axis movement mechanism, and the mechanism that moves the ball along the Y axis will be called the Y-axis movement mechanism.

[0009] The X-axis translation mechanism is mounted on the Y-axis translation mechanism, so if the Y-axis translation mechanism shakes (or deforms), the X-axis translation mechanism will shake (or deform) along with it. Since the X-axis movement mechanism is a mechanism for moving the ball, it is undesirable for its position to change. Increasing the rigidity of the Y-axis movement mechanism is an effective countermeasure.

[0010] [Disadvantages of the prior art] That is, in the technology of Patent Document 1, an X-axis movement mechanism is added to a Y-axis movement mechanism, so the over-ball diameter measurement device has a complex structure and is expensive. Furthermore, increasing the rigidity of the Y-axis movement mechanism further increases the cost and size of the over-ball diameter measurement device.

[0011] In this type of dimension measuring device, the more complex the structure, the more likely it is to malfunction, and the higher the repair costs become. Such rising costs are a factor that hinders the widespread use of dimension measuring devices. In order to promote the widespread use of dimension measuring devices, a dimension measuring device that is simple in structure and inexpensive is desired. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Patent No. 5860553 Summary of the Invention [Problem to be solved by the invention]

[0013] An object of the present invention is to provide a dimension measuring device that is simple in structure and inexpensive. [Means for solving the problem]

[0014] The inventors of the present invention have come up with the idea of ​​using two sets (two pairs) of contacts in the course of various investigations to solve the problem. This idea will be explained based on Figures 1(a) and 1(b).

[0015] FIG. 1(a) is a diagram illustrating a comparative example. When the outer periphery of the cylindrical workpiece 101 is pressed by a pair of contacts 102, 102, there is a possibility that the cylindrical workpiece 101 will move in a direction perpendicular to the central axis 104 (to the right or left in the figure) from the central axis 104 which passes through the center of the contacts 102, 102. The technology that allows this movement can be said to be the technology disclosed in Patent Document 1.

[0016] A technique that replaces the technique disclosed in Patent Document 1 will be described with reference to FIG. 1(b). In Fig. 1(b), the central axis is given the reference symbol 11, and when the central axis 11 is to be distinguished as a first central axis and a second central axis, the first axis is prefixed with A and the second axis is prefixed with B, and they are referred to as the first central axis 11A and the second central axis 11B. The same applies to the other components below.

[0017] 1(b), an axis rotated clockwise from the Y axis by an angle θ is defined as a first central axis 11A, and a pair of first contactors 13A, 13A are arranged on this first central axis 11A. When the outer periphery of the cylindrical workpiece 70 is pressed by the pair of first contactors 13A, 13A, there is a possibility that the cylindrical workpiece 70 will move from the first central axis 11A in a direction perpendicular to the first central axis 11A.

[0018] An axis rotated counterclockwise from the Y axis by an angle θ is set as the second central axis 11B, and a pair of second contactors 13B, 13B is arranged on this second central axis 11B. When the outer periphery of the cylindrical workpiece 70 is pressed by the pair of second contactors 13B, 13B, there is a possibility that the cylindrical workpiece 70 will move from the second central axis 11B in a direction perpendicular to the second central axis 11B. The pair of second contacts 13B, 13B presses different peripheral surfaces (surfaces with different diameters) from those of the first contacts 13A, 13A.

[0019] The movement in the direction perpendicular to the first central axis 11A and the movement in the direction perpendicular to the second central axis 11B cancel each other out, and the cylindrical workpiece 70 comes to rest when the balance is achieved. The longitudinal central axis 70a of the cylindrical workpiece 70 (the central axis extending from the front to the back of the drawing) comes to rest at a position displaced by δ from the origin 17 of the X-axis and Y-axis. That is, the cylindrical workpiece 70 is positioned by the pair of first contacts 13A, 13A and the pair of second contacts 13B, 13B. In this state, the dimension measurement is carried out.

[0020] The invention completed based on the above findings is as follows. The invention according to claim 1 is a dimension measuring device for a cylindrical workpiece that measures the diameter of the cylindrical workpiece, a pair of first contactors that are arranged outside the cylindrical workpiece and pressed against the cylindrical workpiece; a pair of second contactors that are arranged outside the cylindrical workpiece separately from the first contactors and pressed against the cylindrical workpiece to measure a diameter different from that of the first contactors; and a control unit that calculates a distance between the pair of first contactors based on position information of the first contactors and calculates a distance between the pair of second contactors based on position information of the second contactors, When an axis perpendicular to the longitudinal central axis of the cylindrical workpiece is defined as an orthogonal central axis, The first central axis connecting the first contactors and the second central axis connecting the second contactors are arranged in line-symmetrical positions with respect to the orthogonal central axis.

[0021] That is, in Figure 1(b), it is characterized in that it comprises a pair of first contactors 13A, 13A that are arranged outside the cylindrical workpiece 70 and pressed against the cylindrical workpiece 70, and a pair of second contactors 13B, 13B that are arranged outside the cylindrical workpiece 70 separately from the first contactors 13A, 13A and pressed against the cylindrical workpiece 70, measuring a diameter different from that of the first contactors 13A, 13A, and when an axis perpendicular to the longitudinal center axis 70a of the cylindrical workpiece 70 is defined as the orthogonal center axis 70b, the first center axis 11A connecting the first contactors 13A, 13A and the second center axis 11B connecting the second contactors 13B, 13B are arranged in positions that are linearly symmetrical with respect to the orthogonal center axis 70b.

[0022] The invention according to claim 2 is the cylindrical workpiece dimension measuring device according to claim 1, the first contact and the second contact are each provided on a cylinder unit, This cylinder unit is characterized by comprising: a long, thin cylinder that houses a piston; a piston rod that extends from the piston to the outside of the cylinder and has the first contactor or the second contactor at its tip; an air port that is provided in the cylinder and supplies compressed air that presses the surface of the piston away from the piston rod; a return spring that is provided in the cylinder and presses the surface of the piston facing the piston rod; and a position measurement mechanism that is housed in the cylinder and measures the position of the piston.

[0023] The invention according to claim 3 is the cylindrical workpiece dimension measuring device according to claim 1, The cylindrical workpiece has external teeth, and of the three types of contactors, namely, a contactor that comes into contact with the tips of the external teeth to measure the large diameter, a contactor that is inserted into the tooth grooves of the external teeth to measure the overball diameter, and a contactor that comes into contact with the bottoms of the external teeth to measure the small diameter, one is the first contactor and the remaining one is the second contactor.

[0024] The invention according to claim 4 is the cylindrical workpiece dimension measuring device according to claim 1, This device for measuring the dimensions of a cylindrical workpiece is characterized by having a turntable on which the cylindrical workpiece is placed and rotated, and also having a reference detection sensor located outside the turntable that detects the rotation reference of the cylindrical workpiece.

[0025] The invention according to claim 5 is the cylindrical workpiece dimension measuring device according to claim 4, The turntable is characterized in that it is supported by an elevating mechanism.

[0026] The invention according to claim 6 is the cylindrical workpiece dimension measuring device according to claim 5, When a first height from the top surface of the turntable and a second height higher than the first height are set within the height dimension of the cylindrical workpiece, The control unit is characterized by performing a series of controls, including controlling the lifting mechanism so that the first height matches the first central axis, performing measurements at multiple locations while rotating the turntable at the first height, then raising the cylindrical workpiece so that the second height matches the first central axis, performing measurements at multiple locations while rotating the turntable at the second height, and then lowering the cylindrical workpiece so that the first height matches the first central axis.

[0027] The invention according to claim 7 is the cylindrical workpiece dimension measuring device according to claim 6, When a master gauge is placed on the turntable and measurement values ​​at multiple locations are obtained, the control unit corrects the measurement values ​​of the cylindrical workpiece based on the obtained measurement values.

[0028] The invention according to claim 8 is the cylindrical workpiece dimension measuring device according to claim 3, the first contactor is a contactor for measuring the overball diameter, The control unit controls the insertion of the contact for measuring the overball diameter into the tooth groove at least once before measurement.

[0029] The invention according to claim 9 is the cylindrical workpiece dimension measuring device according to claim 7, The control unit is characterized in that it displays a failure when the measured value deviates from the pass standard.

[0030] The invention according to claim 10 is the cylindrical workpiece dimension measuring device according to claim 7, The control unit analyzes the acquired measurement value and displays a warning or an abnormality even if the measurement value is within the acceptable standard.

[0031] The invention according to claim 11 is the cylindrical workpiece dimension measuring device according to claim 6, The control unit is characterized in that it controls to increase the number of measurement points when a command for precision measurement is received or periodically.

[0032] The invention according to claim 12 is the cylindrical workpiece dimension measuring device according to claim 4, The turntable is driven by a rotation control motor, The control unit controls the rotation angle and speed of the rotation control motor.

[0033] The invention according to claim 13 is the cylindrical workpiece dimension measuring device according to claim 5, The lifting mechanism includes a nut fixed to a turntable, a screw shaft extending vertically and screwed into the nut, a support member for rotatably supporting the screw shaft, a large-diameter pulley fixed to the lower end of the screw shaft, a lifting control motor having a small-diameter pulley on its motor shaft, and a belt stretched between the large-diameter pulley and the small-diameter pulley, The control unit controls the lifting control motor so that the cylindrical workpiece reaches a predetermined height.

[0034] The invention according to claim 14 is a positioning method for the cylindrical workpiece dimension measuring device according to claim 1, the cylindrical workpiece dimension measuring device includes a center shaft that fits into a center hole of the cylindrical workpiece, a clamp and an L-shaped bracket that support the first contactor and the second contactor, respectively, a column that supports the L-shaped bracket, and a fixing bolt that fixes the L-shaped bracket to the column; a step of preparing a boss that is detachably fitted onto the center shaft, a bar that passes through the boss and extends to the L-shaped bracket, and jig clamps that are the same shape as the clamps and that are detachably attached to both ends of the bar; removing the clamp and the first and second contacts from the L-shaped bracket and removing the cylindrical workpiece from the center shaft; loosening the fixing bolt to make the L-shaped bracket movable; fitting the boss onto the center shaft; Fixing a pair of L-shaped brackets to both ends of the bar via the jig clamp; a step of tightening the fixing bolts in this fixed state to make the pair of L-shaped brackets immovable; removing the jig clamp, the bar, and the boss; a step of fixing the first contact to a pair of positioned L-shaped brackets via the clamp, and fixing the second contact to a pair of positioned L-shaped brackets via the clamp; The present invention provides a positioning method for a cylindrical workpiece dimension measuring device, which positions the first contactor and the second contactor using an adjustment jig consisting of the boss, the bar, and the jig clamp. [Effects of the Invention]

[0035] In the invention according to claim 1, two or more sets (two pairs) of contacts can be used to measure a variety of dimensions, such as different diameters (for example, over-ball diameter, large diameter, small diameter), with a single dimension measuring device. Moreover, by arranging the two sets (two pairs) of contacts in line symmetry with respect to the orthogonal central axis and pressing the cylindrical workpiece, it becomes possible to position the cylindrical workpiece.

[0036] If a workpiece positioning device and a dimension measuring device were to be prepared separately, the equipment costs would be high. In contrast, in the present invention, the dimension measuring device also positions the workpiece, so the equipment costs can be reduced. Furthermore, since the dimension measuring device only has multiple pairs of contacts, the structure is simple and inexpensive. That is, the present invention provides a dimension measuring device that is simple in structure and inexpensive.

[0037] In the invention according to claim 2, the contacts are supported by a long and thin cylinder unit. Because they are long and thin, the contacts can be placed in a narrow space. As a result, many contacts can be easily placed along the outer periphery of a cylindrical workpiece in the dimension measuring device, and many different outer diameters can be measured at once.

[0038] In the invention according to claim 3, the cylindrical workpiece has external teeth, and the over-ball diameter and the large diameter, or the over-ball diameter and the small diameter, can be measured by the dimension measuring device. Since the over-ball diameter is measured, the quality of cylindrical workpieces having tooth grooves can be improved.

[0039] In the invention according to claim 4, the dimensions of the cylindrical workpiece are measured while it is being rotated on the turntable, so that the dimensions of multiple locations on the outer periphery of the cylindrical workpiece can be measured automatically.

[0040] In the invention according to claim 5, the turntable is supported by a lifting mechanism, so it is possible to measure dimensions at multiple points at different heights. Therefore, for a cylindrical workpiece such as a clutch pulley, which has a long tooth groove formed on its side wall by bending the periphery of a disk, it is possible to evaluate the bending along the tooth groove based on the measurements at multiple points at different heights, and to detect defective products.

[0041] In the invention according to claim 6, dimension measurements are performed at a plurality of locations at a first height, and dimension measurements are performed at a plurality of locations at a second height higher than the first height, and after the series of measurements is completed, the cylindrical workpiece is returned to its initial height. Dimensional measurements can be performed efficiently and quickly. Because measurements are completed in a short time, the dimension measuring device according to the present invention can be applied to an automatic processing line.

[0042] In the invention according to claim 7, the correction value is determined using a master gauge, and the measurement value is corrected with this correction value, thereby further increasing the reliability of the measurement value.

[0043] In the invention according to claim 8, the position of the cylindrical workpiece is corrected by the first contactor before measurement. This correction allows the ball of the first contactor to be inserted more reliably into the tooth groove. As a result, the reliability (measurement accuracy) of the measured value of the over-ball diameter is further improved.

[0044] In the invention according to claim 9, when the measured value falls outside the pass criteria, a rejection is displayed. When applied to mass production, by displaying the rejection during mass production, it is possible to prevent the outflow of defective products at an early stage.

[0045] In the invention according to claim 10, even if the measured value is within the acceptable standard, a warning or abnormality is displayed, so that the outflow of defective products can be prevented at an earlier stage.

[0046] In the invention according to claim 11, the measurement accuracy can be confirmed by carrying out precise measurements as appropriate.

[0047] In the invention according to claim 12, the turntable is driven by a rotation control motor, and the position of the cylindrical workpiece in the rotation direction is determined with high precision.

[0048] In the invention according to claim 13, the turntable is raised and lowered by a lifting control motor and a screw shaft, and the position of the cylindrical workpiece in the height direction is determined with high precision.

[0049] In the invention according to claim 14, the positioning (particularly, axial alignment) of the contacts can be easily performed using an adjustment jig. The adjustment jig used for this purpose is a simple jig consisting of a boss, a bar, and a jig clamp, and the jig is inexpensive and easy to procure. [Brief explanation of the drawings]

[0050] [Figure 1] 1A and 1B are diagrams illustrating the basic principle of the present invention, where FIG. 1A is a diagram illustrating a comparative example, and FIG. 1B is a diagram illustrating an embodiment. [Figure 2] 1A and 1B are diagrams illustrating the basic structure of the contactor used in the present invention, where (a) is a cross-sectional view illustrating the structure of a cylinder unit having a contactor, (b) is an operational diagram of the first contactor, (c) is an operational diagram of the second and third contactors, and (d) is an operational diagram of the position measuring mechanism. [Figure 3] 1 is a front view of a cylindrical workpiece dimension measuring device according to the present invention; [Figure 4] FIG. 2 is a perspective view of an L-shaped bracket, a clamp, and a cylinder unit. [Figure 5] 1 is a plan view of a cylindrical workpiece dimension measuring device according to the present invention; [Figure 6] (a) is a perspective view of a cylindrical workpiece, (b) is an enlarged view of part b in (a), (c) is a diagram illustrating the principle of the reference detection sensor, and (d) is a diagram illustrating the operation of the reference detection sensor. [Figure 7] FIG. 2 is a block diagram of a control system. [Figure 8] FIG. 10 is a flow chart illustrating a normal measurement mode performed by the control unit. [Figure 9] FIG. 10 is a flow chart illustrating a normal measurement mode performed by the control unit. [Figure 10] FIG. 10 is a flow chart illustrating a normal measurement mode performed by the control unit. [Figure 11] 10(a) and 10(b) are diagrams illustrating the trends of the measured values. [Figure 12] FIG. 10 is a flow chart illustrating a precision measurement mode performed by the control unit. [Figure 13]10(a) to 10(d) are diagrams illustrating the configuration and action of an adjustment jig. [Figure 14] FIG. 10 is a flowchart illustrating a correction value determination mode performed by the control unit. DETAILED DESCRIPTION OF THE INVENTION

[0051] An embodiment of the present invention will be described below with reference to the accompanying drawings. [Example]

[0052] [Contact] As shown in Fig. 2(a), the contact 13 is provided on the cylinder unit 20. When the contacts 13 are further classified into first to third contacts, as explained above, the first is designated with A, the second with B, and the third with C, and they are called the first contact 13A, the second contact 13B, and the third contact 13C.

[0053] 2(b), the first contactor 13A is a contactor that measures the overball diameter by being inserted into the tooth groove of the external teeth 73. For this purpose, the first contactor 13A has a ball 14 with a predetermined outer diameter at its tip.

[0054] 2(c), the second contactor 13B is a contactor that measures the large diameter by coming into contact with the tooth tips 74 of the external teeth 73. For this reason, the tip of the second contactor 13B is sharp. The third contactor 13C is a contactor that measures the minor diameter by coming into contact with the tooth bottom 75 of the external tooth 73. For this reason, the third contactor 13C also has a pointed tip. The pointed tip may be a truncated cone.

[0055] [Cylinder unit] As shown in Figure 2(a), the cylinder unit 20 consists of a long, thin cylinder 22 that houses the piston 21, a piston rod 23 that extends from the piston 21 to the outside of the cylinder 22 and has one of the first contact 13A, the second contact 13B, and the third contact 13C at its tip, an air port 24 that is provided in the cylinder 22 and supplies compressed air that presses the surface of the piston 21 away from the piston rod 23, a return spring 25 that is provided in the cylinder 22 and presses the surface of the piston 21 facing the piston rod 23, and a position measuring mechanism 30 that is housed in the cylinder 22 and measures the position of the piston 21 (i.e., the position of the contact 13).

[0056] Preferably, the air port 24 is provided in a lid 26 that closes the opening of the cylinder 22. In order to define the retraction limit of the piston 21, the lid 26 is opened and a cylindrical stopper 27 of a predetermined length is inserted.

[0057] For example, when a three-way air valve 28 is switched to supply compressed air from a compressed air source 29 to the air port 24, the piston 21 moves forward to compress the return spring 25, and the contact 13 moves forward together with the piston rod 23. When the air valve 28 is switched to cut off the supply from the compressed air source 29 and open the air port 24 to the atmosphere, the return spring 25 causes the contact 13 to move backward together with the piston rod 23 and return to the original position (standby position).

[0058] Since the cylinder units 20 are long and narrow, a large number of the cylinder units 20 can be efficiently arranged in a limited space.

[0059] [Position measurement mechanism] The position measuring mechanism 30 housed in the cylinder unit 20 comprises, for example, a scale plate 31 extending from the piston 21 on the opposite side of the piston rod 23, and a light emitter 32 and a light receiver 33 arranged on either side of the scale plate 31.

[0060] As shown in Figure 2(d), the scale plate 31 is provided with a plurality of slits 34, which are narrow, strip-shaped through-holes. When laser light is emitted from the projector 32, part of the light passes through the slits 34 and reaches the receiver 33. The receiver 33 has minute light-receiving elements densely arranged, and the light-receiving elements are distinguished from the light-receiving elements, thereby recognizing the light-receiving lengths L1 and L2.

[0061] When the scale plate 31 moves forward or backward, the ratio of (slit 34 width / light receiving length L1) to (slit 34 width / light receiving length L2) changes. This change is monitored and the position of the scale plate 31 is calculated. As a result, the position of the contact 13 is measured by the position measuring mechanism 30.

[0062] [Cylindrical workpiece dimension measuring device] As shown in Figure 3, the dimensional measuring device 40 for cylindrical workpieces (hereinafter referred to as the dimensional measuring device 40) includes a turntable 41 on which the cylindrical workpiece 70 is placed and rotated, a lifting mechanism 45 that supports the turntable 41, a clamp 42 and a stand 43 that support the contactor 13, and a base 44 that supports all of these together.

[0063] [Lifting mechanism] The lifting mechanism 45 comprises, for example, a support 46 that stands on the base 44, a screw shaft 48 that is attached vertically to the support 46 via a bearing 47, a nut 49 that is screwed onto the screw shaft 48 and is guided by the support 46 so that it can be raised and lowered, a shaft 51 that extends upward from the nut 49, a large-diameter pulley 52 that is fixed to the lower end of the screw shaft 48, a lifting control motor 53 that is fixed to the support 46, a small-diameter pulley 54 that is attached to the motor shaft of the lifting control motor 53, and a belt 55 that is stretched between the small-diameter pulley 54 and the large-diameter pulley 52.

[0064] The lift control motor 53 is preferably a stepping motor, but any type of control motor can be used as long as it is capable of fine control of the rotation angle and precise position control.

[0065] A longitudinal groove 56 is provided in the support member 46, and a key 57 is provided in the nut 49, and this key 57 fits into the longitudinal groove 56. The key 57 and the longitudinal groove 56 may be splines. The lifting control motor 53 rotates the screw shaft 48 via the small diameter pulley 54, belt 55, and large diameter pulley 52. ​​The presence of the key 57 prevents the nut 49 from rotating. Therefore, the nut 49 rises or falls. As a result, the turntable 41 rises or falls. In other words, the height of the turntable 41 is precisely controlled by the lifting control motor 53.

[0066] [Turntable] The turntable 41 is rotatably supported on the shaft 51 via a bearing 58. A rotation control motor 61 is attached to the nut 49, and a small diameter gear 62 is attached to the motor shaft of the rotation control motor 61. The small diameter gear 62 meshes with a large diameter gear 63 that is integrally formed (or attached) to the bottom of the turntable 41. The turntable 41 is rotated by a rotation control motor 61 via a small diameter gear 62 and a large diameter gear 63. The rotation control motor 61 precisely controls the rotation angle of the turntable 41.

[0067] The rotation control motor 61 is preferably a stepping motor, but any type of control motor can be used as long as it is capable of fine control of the rotation angle and precise position control.

[0068] [stand] The stand 43 that supports the contact 13 is made up of, for example, a column 64 that extends upward from the base 44, an L-shaped bracket 65 placed on this column 64, and a fixing bolt 66 that fixes this L-shaped bracket 65 to the column 64. It is possible to omit the column 64 by making the vertical dimension of the L-shaped bracket 65 sufficiently large. However, this would lower the height position of the fixing bolt 66, making it difficult to work with, so it is desirable to raise the height with the column 64 and position the fixing bolt 66 at a higher position.

[0069] [L-bracket and clamp] 4, the L-shaped bracket 65 is an L-shaped member consisting of a horizontal portion 65a and a vertical portion 65b extending upward from the horizontal portion 65a. The horizontal portion 65a has a horizontally extending elongated hole 65c. The vertical portion 65b has a female thread portion 65d.

[0070] The clamp 42 is made up of a clamp body 42a, a holding member 42b, a first bolt 42c, and a second bolt 42d. A groove 42e corresponding to the cylinder unit 20 is formed in each of the clamp body 42a and the holding member 42b.

[0071] The clamp body 42a is placed against the cylinder unit 20. Next, the retaining member 42b is placed over the cylinder unit 20. The retaining member 42b is fixed to the clamp body 42a with the first bolt 42c. The clamp 42 is now set on the cylinder unit 20.

[0072] Next, the clamp body 42a is attached to the L-shaped bracket 65 by screwing the second bolt 42d into the female thread portion 65d. Next, the L-shaped bracket 65 is fixed to the column 64 shown in FIG.

[0073] As a result of the above, the contact 13 is fixed to the base 44 via the clamp 42 and the stand 43, as shown in FIG. The configuration of the clamp 42 may be changed.

[0074] FIG. 5 is a plan view of the dimension measuring device. As shown in FIG. 5, the first contactor 13A is fixed to a stand 43 by a clamp 42, and similarly, the second contactor 13B and the third contactor 13C are fixed. First contactors 13A, 13A are arranged on a first central axis 11A rotated clockwise by an angle θ from the Y axis, second contactors 13B, 13B are arranged on a second central axis 11B rotated counterclockwise by an angle θ from the Y axis, and third contactors 13C, 13C are arranged on a third central axis 11C on the X axis. In this example, the angle θ is 30°.

[0075] [Reference detection sensor] In addition, a reference detection sensor 68 for detecting the rotation reference of the cylindrical workpiece is disposed outside the turntable 41 .

[0076] [Cylindrical workpiece] 6(a), a cylindrical workpiece 70 is made up of, for example, a peripheral wall 71, a bottom portion 72 that closes one end of the peripheral wall 71, and external teeth 73 formed on the outer surface of the peripheral wall 71. A central hole 72a is provided in the center of the bottom portion 72. 3, this center hole 72a is a hole with a gap added to the center shaft 41a extending upward from the turntable 41. Therefore, the cylindrical workpiece 70 can move horizontally by the amount of the gap.

[0077] As shown in FIG. 6(b), the external teeth 73 have tooth tips 74 and tooth bottoms 75, and are provided in a form in which a small-diameter reference hole 76 passes through the tooth bottoms 75. As shown in FIG. 6(a), the reference holes 76 are at different heights and comprise a first reference hole 76A, a second reference hole 76B, and a third reference hole 76C.

[0078] The first reference hole 76A is a hole corresponding to the "first height" described below, the second reference hole 76B set higher is a hole corresponding to the "second height", and the third reference hole 76C set higher is a hole corresponding to the "third height".

[0079] Although one first reference hole 76A is sufficient, considering that this first reference hole 76A will be detected by the reference detection sensor 68, it is desirable to provide multiple holes, such as holes at all tooth roots 75. The same applies to the second and third reference holes 76B, 76C. This is because the more holes there are, the smaller the rotation angle required to complete reference detection, thereby shortening the measurement time.

[0080] [Reference detection sensor] As shown in FIG. 6(c), the reference detection sensor 68 has, for example, a light emitting element 68b and a light receiving element 68c in a case 68a. When laser light 68d emitted from light-emitting element 68b is reflected by tooth tip 74 or tooth bottom 75, the reflected light reaches light-receiving element 68c, which electrically recognizes the reflected light.

[0081] 6(d), when the center of the reference detection sensor 68 coincides with the reference hole 76, the laser beam 68d enters the reference hole 76, and no reflected light is obtained. Even if a reflected light is obtained, it is weak. At this time, the light receiving element 68c detects the reference hole 76. Therefore, in FIG. 5, when the cylindrical workpiece 70 is rotated by the turntable 41, the reference detection sensor 68 detects the reference hole 76.

[0082] [Control Unit] As shown in FIG. 7, the control unit 80 obtains reference detection information from the reference detection sensor 68. The control unit 80 controls the rotation angle and speed of the rotation control motor 61 . The control unit 80 controls the rotation angle of the lift control motor 53. By controlling the rotation angle of the lift control motor 53, the height position of the turntable is accurately controlled.

[0083] The control unit 80 controls the opening and closing of the air valve 28 to move the pair of first contactors 13A forward / backward to obtain the overball diameter measurement value, move the pair of second contactors 13B forward / backward to obtain the large diameter measurement value, and move the pair of third contactors 13C forward / backward to obtain the small diameter measurement value. The control unit 80 compares the obtained measurement value with a reference value and makes a pass / fail decision.

[0084] Furthermore, the control unit 80 executes a normal measurement mode, a correction value determination mode, a precise measurement mode, etc. based on the flow described later.

[0085] [Normal measurement mode] As shown in FIG. 8, at step number (hereinafter abbreviated as ST) 01, the cylindrical workpiece is placed on the turntable by a robot (or manually). The lifting mechanism is controlled to set the cylindrical workpiece to the "first height" (ST02), and the turntable is rotated at a predetermined speed (ST03). When the reference detection sensor detects the first reference hole (ST04), the turntable is stopped (ST05).

[0086] In ST06, the first pair of contacts (OBD measurement contacts) is moved forward and backward. This operation is generally performed once, but it is acceptable to repeat it multiple times. As shown in Fig. 2(b), the balls 14 enter the tooth grooves. If the cylindrical workpiece is out of phase, this entry corrects the misalignment.

[0087] In ST07, the first contactor measures the OBD (see Figure 2(b)), the second contactor measures the large diameter (see Figure 2(c)), and the third contactor measures the small diameter (see Figure 2(c)). The obtained measurement value is compared with the reference value and evaluated (ST08), and pass / fail is determined (ST09). If the test is unsuccessful, a message indicating this is displayed (ST10). If the test is unsuccessful, the flow ends.

[0088] If the test passes, the turntable is rotated by a predetermined angle (for example, 120°) in ST11 and then stopped (ST12). In ST13, the pair of first contacts (for OBD measurement) is moved forward and backward. Then, measurements are carried out on the new location (ST14), the measured values ​​are evaluated (ST15), a pass / fail decision is made (ST16), and if the result is unsuccessful, a failure is displayed (ST17).

[0089] In ST18, if measurement at the first height is to be continued, the process returns to ST11 and ST12 to ST17 are repeated. This repetition provides multiple measurements at the first height. In ST18, if the measurement at the first height is to be ended, the process proceeds to FIG.

[0090] In ST21 of Fig. 9, the lifting mechanism is controlled to set the cylindrical workpiece to the "second height." ST22 to ST36 in FIG. 9 are the same as ST03 to ST17 in FIG. 8, and therefore detailed description thereof will be omitted. That is, in FIG. 9, measurements are carried out at the second height. In ST37, if measurement at the second height is to be continued, the process returns to ST30 and ST31 to ST36 are repeated. This repetition provides multiple measurements at the second height. In ST37, if the measurement at the second height is to be ended, the process proceeds to FIG.

[0091] In ST41 of FIG. 10, the lifting mechanism is controlled to set the cylindrical workpiece to the "third height." ST42 to ST56 in FIG. 10 are the same as ST22 to ST36 in FIG. 9, and therefore detailed description thereof will be omitted. That is, in FIG. 10, measurements are carried out at the third height. In ST57, if measurement at the third height is to be continued, the process returns to ST50 and ST51 to ST56 are repeated. This repetition provides multiple measurements at the third height. If the measurement at the third height is completed in ST57, the cylindrical workpiece is removed from the turntable in ST58. This completes the normal measurement mode.

[0092] Thus, three OBD measurements are obtained at the first elevation, three OBD measurements are obtained at the second elevation, and three OBD measurements are obtained at the third elevation, for a total of nine OBD measurements. The first OBD measurement at the first height, the first OBD measurement at the second height, and the first OBD measurement at the third height are measurements at a common tooth space.

[0093] If the three OBD measurements in a common tooth space are the same (or nearly the same), the tooth space is straight along the vertical axis. On the other hand, if there is a difference between the three OBD measurements for a common tooth gap, an abnormality in the tooth gap is suspected. Abnormalities include inclined, curved, or meandering tooth gaps. If an abnormality is found, the cylindrical workpiece is rejected as a defective product.

[0094] In a strict sense, OBD is the dimension between the outer surfaces of the balls, but by measuring the OBD height difference, it is possible to detect abnormalities in the shape of the tooth grooves. This increases the added value of the dimension measuring device 40 according to the present invention.

[0095] The pass / fail judgment described in ST08 and ST09 in FIG. 8 may be made by comparing the measured value with a reference value, or by examining the tendency of changes in the measured value. As shown in Figure 11(a), if a measurement value exceeds the reference value but is below the upper tolerance, the shaded area is the "difference" calculated as (measurement value - reference value). Figure 11(b) shows the "differences" arranged in chronological order.

[0096] As shown in Figure 11(b), when the "difference" is on the rise and is expected to exceed the allowable value in the near future, it is recommended to issue a caution or warning. That is, the control unit checks the tendency of the acquired measurement values ​​and displays a warning or an abnormality even if the measurement values ​​are within the acceptable standards.

[0097] By taking measures based on the warning or abnormality indication before a rejected product is produced, it is possible to prevent or suppress the production of rejected products.

[0098] [Precision measurement mode] As is well known, there are two types of inspection methods: 100% inspection and sampling inspection. 100% inspection is ideal, but it increases the inspection cost. Sampling inspection has the advantage of reducing the inspection cost. The normal measurement mode described above corresponds to a sampling inspection. The cylindrical workpiece 70 shown in FIG. 6(a) is a so-called press-formed product. That is, a die is set in a press machine, and a blank is subjected to plastic working with this die to obtain a press-formed product. During this process, the die gradually wears out. Therefore, the die is replaced periodically (for example, when a predetermined number of shots is reached).

[0099] When a die is replaced, it is important to verify the accuracy of the die. Therefore, it is desirable to perform precision measurements equivalent to a 100% inspection on the cylindrical workpiece 70 manufactured with the replaced die.

[0100] In ST61 of FIG. 12, it is checked whether or not the precision measurement mode has been selected. If the result is No and the normal measurement mode is selected in ST62, the steps in FIGS. 8 to 10 are carried out (ST63). When precision measurement mode is selected in ST61, it is set in ST64 whether to measure N% of the number of external teeth. If N is 100%, it is a full inspection, and if N is 50%, it is a half inspection. In ST65, N% is measured based on FIGS.

[0101] 5, it is important to position (align) the first contactors 13A, 13A so that the first central axis 11A connecting the pair of first contactors 13A, 13A passes through the center (including almost the center) of the center shaft 41a. The same applies to the second contactor 13B and the third contactor 13C. This positioning (axis alignment) work is performed very carefully and takes a long time, so it is desirable to shorten this work time. An adjustment jig 85 capable of shortening the working time is provided, and a method for positioning a dimension measuring device using this adjustment jig 85 will be described below.

[0102] [Adjustment jig] FIG. 13(a) is a partial view of FIG. In Fig. 13(a), the contact 13, the cylinder unit 20 and the clamp 42 are removed from the L-shaped bracket 65. The removed state is shown in Fig. 13(b). As shown in Figure 13(c), the adjustment jig 85 consists of a boss 86 that can be detachably fitted onto the center shaft 41a, a bar 87 that passes through this boss 86 and extends to the L-shaped bracket 65, and jig clamps 88 that are fitted onto both ends of this bar 87.

[0103] The jig clamp 88 has the same structure as the clamp (FIG. 3, reference numeral 42), but the dimensions are different because the outer diameter of the cylinder unit 20 and the outer diameter of the bar 87 are different. However, the center height ha of the jig clamp 88 shown in Fig. 13(d) is set to be the same as the center height ha of the clamp 42 shown in Fig. 13(a). This makes it possible to align the axis of the cylinder unit 20 (i.e., the contact 13) even when the jig clamp 88 is used instead of the clamp 42.

[0104] [Positioning method] The first step in the positioning method is to prepare the dimension measuring device 40 shown in FIGS. 3 to 5 and the adjusting jig 85 shown in FIG. 13(c). 13(a) and 13(b), the clamp 42 and the first contact 13A are removed from the L-shaped bracket 65. The second and third contacts 13B and 13C are also removed in the same manner.

[0105] As shown in FIG. 3, when the cylindrical workpiece 70 is fitted on the center shaft 41a, the cylindrical workpiece 70 is removed from the center shaft 41a.

[0106] Next, in FIG. 13(b), the fixing bolt 66 is loosened to make the L-shaped bracket 65 movable. 13(d), a pair of L-shaped brackets 65 are fixed to both ends of the bar 87 via jig clamps 88. In this fixed state, the fixing bolts 66 are tightened to make the L-shaped brackets 65 immovable.

[0107] Next, in FIG. 13(d), the jig clamp 88, the bar 87 and the boss 86 are removed. The shape after removal will be the same as that shown in Figure 13(b). 13(b), the first contactor 13A is fixed to the positioned L-shaped bracket 65 via the clamp 42. As a result, the state returns to that of FIG. 13(a), and the pair of first contactors 13A are accurately positioned. The second and third contactors 13B and 13C are similarly positioned.

[0108] As described above, by using the adjustment jig 85 consisting of the boss 86, the bar 87, and the jig clamp 88 to position the first to third contactors 13A to 13C, the cylindrical workpiece dimension measuring device 40 can be positioned quickly and easily.

[0109] [Master Model] The master model has the same appearance as the cylindrical workpiece 70 shown in Figure 6(a). However, the master model is a machined product manufactured by cutting it out of steel material. Machined products have significantly better dimensional accuracy than press-formed products. Using such a master model, correction values ​​can be determined.

[0110] [Correction value determination mode] In ST71 of FIG. 14, the master model is placed on the turntable. The lifting mechanism is controlled to set the cylindrical workpiece to a predetermined height (ST72), and the turntable is rotated at a predetermined speed (ST73). When the reference detection sensor detects the reference hole (ST74), the turntable is stopped (ST75).

[0111] In ST76, the pair of first contacts (for OBD measurement) is moved forward and backward. In ST77, the OBD is measured using the first contact. The OBD correction value is determined (ST78) using the formula (OBD reference value - OBD measurement value = OBD correction value). In ST79, the large diameter is measured with the second contact. The large diameter correction value is determined (ST80) using the formula (large diameter reference value - large diameter measurement value = large diameter correction value). In ST81, the small diameter is measured with the third contact. The small diameter correction value is determined (ST82) using the formula (small diameter reference value - small diameter measurement value = small diameter correction value).

[0112] The control unit measures the OBD and corrects the obtained measurement value with the OBD correction value. Similarly, the control unit measures the large diameter and corrects the obtained measurement value with the large diameter correction value, and measures the small diameter and corrects the obtained measurement value with the small diameter correction value (ST83). As a result, the reliability of the measurement value can be further improved.

[0113] The dimension measuring device 40 of the present invention is suitable for cylindrical workpieces having external teeth, but may also be applied to cylindrical workpieces that do not have external teeth.

[0114] Furthermore, the structure of the cylindrical workpiece dimension measuring device 40 shown in FIG. 3 may be modified as appropriate. Furthermore, although three pairs of contacts are arranged in FIG. 5, it is also acceptable to arrange two pairs of contacts or four or more pairs of contacts. In addition, the turntable may be configured to have an intermediate angle of 60° in addition to 120° to increase the number of measurement points. [Industrial Applicability]

[0115] The present invention is suitable for a dimension measuring device that measures the major and minor diameters on the outer periphery of a cylindrical workpiece. [Explanation of symbols]

[0116] 11A...first center shaft, 11B...second center shaft, 13...contactor, 13A...first contactor, 13B...second contactor, 14...ball, 20...cylinder unit, 21...piston, 22...cylinder, 23...piston rod, 24...air port, 25...return spring, 30...position measuring mechanism, 40...cylindrical workpiece dimension measuring device (dimension measuring device), 41...turntable, 41a...center shaft, 42...clamp, 45...lifting mechanism, 46...support material, 48 ...Screw shaft, 49...Nut, 52...Large diameter pulley, 53...Lifting control motor, 54...Small diameter pulley, 55...Belt, 61...Rotation control motor, 64...Column, 65...L-shaped bracket, 66...Fixing bolt, 68...Reference detection sensor, 70...Cylindrical workpiece, 70a...Longitudinal center axis, 70b...Orthogonal center axis, 72a...Center hole, 73...External teeth, 74...Tooth tip, 75...Tooth bottom, 80...Control unit, 85...Adjustment jig, 86...Boss, 87...Bar, 88...Jig clamp.

Claims

1. A cylindrical workpiece dimension measuring device for measuring the diameter of a cylindrical workpiece, a pair of first contactors arranged outside the cylindrical workpiece and pressed against the cylindrical workpiece; a pair of second contactors arranged outside the cylindrical workpiece separately from the first contactors and pressed against the cylindrical workpiece to measure a diameter different from that of the first contactors; and a control unit that calculates a distance between the pair of first contactors based on position information of the first contactors and calculates a distance between the pair of second contactors based on position information of the second contactors, When an axis perpendicular to the longitudinal central axis of the cylindrical workpiece is defined as an orthogonal central axis, A dimensional measuring device for a cylindrical workpiece, characterized in that a first central axis connecting the first contactors and a second central axis connecting the second contactors are arranged in a position symmetrical with respect to the orthogonal central axis.

2. The cylindrical workpiece dimension measuring device according to claim 1, the first contact and the second contact are each provided on a cylinder unit, This cylinder unit is an apparatus for measuring the dimensions of a cylindrical workpiece, characterized in that it comprises a long, thin cylinder that houses a piston, a piston rod that extends from the piston to the outside of the cylinder and has the first contactor or the second contactor at its tip, an air port provided in the cylinder that supplies compressed air that presses the surface of the piston away from the piston rod, a return spring provided in the cylinder that presses the surface of the piston facing the piston rod, and a position measuring mechanism that is housed in the cylinder and measures the position of the piston.

3. The cylindrical workpiece dimension measuring device according to claim 1, The cylindrical workpiece has external teeth, and of the three types of contactors, namely a contactor that contacts the tips of the external teeth to measure the large diameter, a contactor that is inserted into the tooth grooves of the external teeth to measure the overball diameter, and a contactor that contacts the bottoms of the external teeth to measure the small diameter, one is the first contactor and the remaining one is the second contactor.

4. The cylindrical workpiece dimension measuring device according to claim 1, This device for measuring the dimensions of a cylindrical workpiece is characterized in that it comprises a turntable on which the cylindrical workpiece is placed and rotated, and also comprises a reference detection sensor that is arranged outside the turntable and detects the rotation reference of the cylindrical workpiece.

5. The cylindrical workpiece dimension measuring device according to claim 4, The device for measuring dimensions of a cylindrical workpiece is characterized in that the turntable is supported by a lifting mechanism.

6. The cylindrical workpiece dimension measuring device according to claim 5, When a first height from the top surface of the turntable and a second height higher than the first height are set within the height dimension of the cylindrical workpiece, The control unit controls the lifting mechanism so that the first height matches the first center axis, performs measurements at multiple locations while rotating the turntable at the first height, then raises the cylindrical workpiece so that the second height matches the first center axis, performs measurements at multiple locations while rotating the turntable at the second height, and then lowers the cylindrical workpiece so that the first height matches the first center axis.This is an apparatus for measuring the dimensions of a cylindrical workpiece, characterized by performing a series of controls.

7. The cylindrical workpiece dimension measuring device according to claim 6, A dimensional measuring device for cylindrical workpieces, characterized in that when a master gauge is placed on the turntable and measurement values ​​at multiple locations are obtained, the control unit corrects the measurement values ​​of the cylindrical workpiece based on the obtained measurement values.

8. The cylindrical workpiece dimension measuring device according to claim 3, the first contactor is a contactor for measuring the overball diameter, The device for measuring dimensions of a cylindrical workpiece is characterized in that the control unit controls the insertion of a contact for measuring the overball diameter into the tooth groove at least once before measurement.

9. The cylindrical workpiece dimension measuring device according to claim 7, The device for measuring dimensions of a cylindrical workpiece is characterized in that the control unit displays a failure when the measured value deviates from the pass standard.

10. The cylindrical workpiece dimension measuring device according to claim 7, The control unit analyzes the acquired measurement values ​​and displays a warning or abnormality even if the measurement values ​​are within the acceptable standards.

11. The cylindrical workpiece dimension measuring device according to claim 6, The device for measuring dimensions of a cylindrical workpiece is characterized in that the control unit controls the number of measurement points to be increased when a precision measurement command is received or periodically.

12. The cylindrical workpiece dimension measuring device according to claim 4, The turntable is driven by a rotation control motor, The control unit controls the rotation angle and speed of the rotation control motor.

13. The cylindrical workpiece dimension measuring device according to claim 5, The lifting mechanism includes a nut fixed to a turntable, a screw shaft extending vertically and screwed into the nut, a support member for rotatably supporting the screw shaft, a large-diameter pulley fixed to the lower end of the screw shaft, a lifting control motor having a small-diameter pulley on its motor shaft, and a belt stretched between the large-diameter pulley and the small-diameter pulley, The control unit controls the lifting control motor so that the cylindrical workpiece reaches a predetermined height.

14. 2. A method for positioning a cylindrical workpiece dimension measuring device according to claim 1, comprising: the cylindrical workpiece dimension measuring device includes a center shaft that fits into a center hole of the cylindrical workpiece, a clamp and an L-shaped bracket that support the first contactor and the second contactor, respectively, a column that supports the L-shaped bracket, and a fixing bolt that fixes the L-shaped bracket to the column; a step of preparing a boss that is detachably fitted onto the center shaft, a bar that passes through the boss and extends to the L-shaped bracket, and jig clamps that are the same shape as the clamps and that are detachably attached to both ends of the bar; removing the clamp and the first and second contacts from the L-shaped bracket and removing the cylindrical workpiece from the center shaft; loosening the fixing bolt to make the L-shaped bracket movable; fitting the boss onto the center shaft; Fixing a pair of L-shaped brackets to both ends of the bar via the jig clamp; a step of tightening the fixing bolts in this fixed state to make the pair of L-shaped brackets immovable; removing the jig clamp, the bar, and the boss; a step of fixing the first contact to a pair of positioned L-shaped brackets via the clamp, and fixing the second contact to a pair of positioned L-shaped brackets via the clamp, A positioning method for a cylindrical workpiece dimension measuring device, which positions the first contactor and the second contactor using an adjustment jig consisting of the boss, the bar, and the jig clamp.

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