Measurement device, drive unit, measurement system, and measurement method

Abstract

The present invention provides a measurement device, a drive unit, a measurement system, and a measurement method with which it is possible to stabilize measurement performance and improve operability, and with which cost reductions due to the repurposing of an existing element can be realized .　A caliper (10) has a main scale (11), a slider (12), a detector (13), and a drive unit (40) that moves the slider (12). The main scale (11) has a rolling surface (112) and a pressing surface (113). The drive unit (40) has a connection pin (42) that is connected to the slider (12) and can transmit driving force in a measurement direction (D), a driving roller (44) that is driven by a motor (43) and can roll on the rolling surface (112), and a pressing mechanism (50) that is pressed against the pressing surface (113). The pressing mechanism (50) has: a pair of pressing rollers (51) that are pressed against the pressing surface (113) at a plurality of positions in the measurement direction (D) on both sides of the driving roller (44); and a coil spring (52) that biases the pressing rollers (51) toward the pressing surface (113).

Description

MEASUREMENT DEVICE, DRIVE UNIT, MEASUREMENT SYSTEM, AND MEASUREMENT METHOD

[0001] The present invention relates to a measuring device, a drive unit, a measuring system and a measuring method.

[0002] Various measuring devices are used to measure workpiece dimensions. For example, relatively large-scale measuring devices such as coordinate measuring machines (CMMs) are used to meet high-precision requirements. On the other hand, small measuring devices are used for routine inspections in manufacturing processes. Routine inspections in manufacturing processes include, for example, in-line inspections during the process and 100% inspections before shipping. In these routine inspections, the same measurement operations are repeatedly performed on multiple workpieces. Although the tasks themselves are simple, there is a need for more efficient and labor-saving measurement operations. In contrast, among small measuring devices, calipers, height gauges, depth gauges, and other measuring devices that measure workpiece dimensions by moving a slider relative to a main scale are simple in structure, inexpensive to manufacture, easy to operate, and have stable measurement performance. These make them ideal for the routine inspections mentioned above, and are easily introduced even in relatively small manufacturing plants.

[0003] In the above-mentioned small measuring instruments, efforts have been made to stabilize measurement performance and improve operability, such as by improving the rollers that move the slider relative to the main scale (see Patent Documents 1 and 2) and by motorizing the slider relative to the main scale (see Patent Documents 2 and 3). In addition, the relative displacement of the slider relative to the main scale is read by a sensor and the measurement value is output externally, and simple measurement systems that include the above-mentioned small measuring instruments have also been constructed (see Patent Document 4).

[0004] JP 2015-165233 A JP 2019-144049 A JP 2003-185401 A JP 2009-33422 A

[0005] The measuring instruments disclosed in the above-mentioned Patent Documents 1 to 3 each have a new mechanism installed in part of the measuring instrument, and existing main scales and sliders cannot be reused, so the dedicated design increases manufacturing costs, which creates a barrier to adoption for relatively small manufacturing companies. In particular, at manufacturing sites where a large number of conventional measuring instruments are already in use, replacing these with new measuring instruments poses a significant cost problem.

[0006] An object of the present invention is to provide a measuring device, a drive unit, a measuring system, and a measuring method that can stabilize measuring performance and improve operability, and that can reduce costs by repurposing existing elements.

[0007] The measuring device of the present invention is a measuring device for measuring the dimensions of a workpiece, and comprises: a reference member and a measuring member that are movable relative to each other in a measurement direction and can each come into contact with the workpiece; a detector that can detect the relative position of the measuring member with respect to the reference member; and a drive unit that moves the measuring member in the measurement direction relative to the reference member, wherein the reference member has a rolling surface that extends in the measurement direction and a pressing surface on the opposite side to the rolling surface that is parallel to the rolling surface and extends in the measurement direction, the drive unit has a connection part that is connected to the measuring member and can transmit a driving force in the measurement direction, a drive roller that is driven by a motor and can roll on the rolling surface, and a pressing mechanism that presses the pressing surface, and the pressing mechanism has a pair of pressing members that are pressed against the pressing surface at multiple positions in the measurement direction on both sides of the drive roller, and a biasing member that biases the pressing member toward the pressing surface.

[0008] The drive unit of the present invention comprises a reference member and a measuring member that are movable relative to each other in a measurement direction and can each come into contact with a workpiece, and a detector that can detect the relative position of the measuring member with respect to the reference member, wherein the reference member is attached to a measuring device main body that has a rolling surface that extends in the measurement direction and a pressing surface on the opposite side of the rolling surface that is parallel to the rolling surface and extends in the measurement direction, and the drive unit moves the measuring member in the measurement direction relative to the reference member, and comprises a connection part that is connected to the measuring member and can transmit a driving force in the measurement direction, a drive roller that is driven by a motor and can roll on the rolling surface, and a pressing mechanism that presses the pressing surface, and the pressing mechanism comprises a pair of pressing members that are pressed against the pressing surface at multiple positions on both sides of the drive roller in the measurement direction, and a biasing member that biases the pressing member toward the pressing surface.

[0009] The measuring system of the present invention is a measuring system having the measuring device of the present invention described above and a control device that controls the detector and the drive unit, and the control device has a movement control unit that uses the drive unit to move the measuring member relative to the reference member and bring it into contact with the workpiece, and a stop control unit that detects contact between the measuring member and the workpiece and stops the drive unit.

[0010] The measuring method of the present invention is a measuring method for measuring the dimensions of the workpiece using the measuring device of the present invention described above, in which the measuring member is moved relative to the reference member by the drive unit, the measuring member is brought into contact with the workpiece, the detector detects contact between the measuring member and the workpiece, the drive unit is stopped, and then the dimensions of the workpiece are measured from the detector.

[0011] 1 is a front view showing a measurement system according to a first embodiment of the present invention; a plan view showing the measurement system according to the first embodiment; a front view showing a measurement device of the measurement system according to the first embodiment; a sectional view showing a drive unit of the measurement device according to the first embodiment; a sectional view showing a pressing mechanism of the drive unit according to the first embodiment; a plan view showing a control device of the measurement system according to the first embodiment; an enlarged view showing a display unit of the control device according to the first embodiment; a block diagram showing functional elements of the control device according to the first embodiment; a flowchart showing the operation of the control device according to the first embodiment; a sectional view showing a pressing mechanism according to a second embodiment of the present invention; a sectional view showing a pressing mechanism according to a third embodiment of the present invention; a sectional view showing a pressing mechanism according to a fourth embodiment of the present invention; a sectional view showing a pressing mechanism according to a fifth embodiment of the present invention; a plan view showing the underside of the pressing mechanism according to the fifth embodiment.

[0012] 1 and 2 show a measurement system 1 according to a first embodiment of the present invention. The measurement system 1 includes a caliper 10, which is a measurement device according to the present invention, a stand 20 that supports the caliper 10, and a control device 30 that controls the caliper 10. The caliper 10 includes a drive unit 40 based on the present invention. FIG. 3 shows the caliper 10, and FIG. 4 shows an enlarged view of the drive unit 40. FIG. 5 shows an enlarged view of a pressing mechanism 50 included in the drive unit 40.

[0013] [Measuring Device] In Figure 3, a vernier caliper 10, which is a measuring device, has a main scale 11 extending in a measurement direction D and a slider 12 that moves along the main scale 11. A detector 13 is installed inside the slider 12, and a display unit 14 is installed on the surface of the slider 12. The detector 13 can detect the relative position of the slider 12 in the measurement direction D with respect to the main scale 11, and the display unit 14 can display the value detected by the detector 13. Jaws 111 and 114 are formed on the main scale 11, and jaws 121 and 124 are formed opposite to the main scale 11 on the slider 12. By clamping a workpiece 9 between the pair of jaws 111 and 121, the main scale 11 and the slider 12 stop at a relative position corresponding to the outer dimensions of the workpiece 9. Furthermore, by expanding the pair of jaws 114 and 124 in a gap portion such as a recess in the workpiece 9, the main scale 11 and the slider 12 stop at a relative position corresponding to the inner dimensions of the workpiece 9. In this state, the detection position of the detector 13 is read and displayed on the display unit 14, thereby making it possible to measure the dimension of the workpiece 9 in the measurement direction D.

[0014] The above are existing functions of so-called digital calipers, and the caliper 10, which is the measuring device of the present invention, can be constructed using the elements of existing digital calipers as is. Here, the main scale 11 and slider 12 are the reference member and measuring member of the present invention. The main scale 11, which is the reference member, has a pair of rolling surfaces 112 and a pressing surface 113 extending in the measurement direction D. In this embodiment, the rolling surface 112 is the side of the main scale 11 on which the jaw 111 is formed (the bottom side in FIG. 3 ), and the pressing surface 113 is the side of the main scale 11 opposite the rolling surface 112 (the top side in FIG. 3 ). A drive unit 40 is connected to the slider 12, which is the measuring member, and moves the slider 12 (measuring member) in the measurement direction D relative to the main scale 11 (reference member).

[0015] 4, the drive unit 40 has a frame 41 that surrounds the main beam 11. On the rolling surface 112 side of the frame 41, a connection pin 42 that serves as a connection portion, and a drive roller 44 that is driven by a motor 43 are provided.

[0016] The connection pin 42 (connection portion) is a shaft member that extends in a direction intersecting the plane of the drawing and has both ends supported by the frame 41, and is engageable with a recess in a thumb roller support portion 122 formed on the slider 12. The engagement between the connection pin 42 and the thumb roller support portion 122 connects the drive unit 40 and the slider 12, and when the drive unit 40 generates a driving force in the measurement direction D, this driving force can be transmitted to the slider 12. The drive unit 40 is rotatable about the connection pin 42 relative to the slider 12, and is displaceable in directions intersecting the measurement direction D (up-down direction in the plane of the drawing and directions perpendicular to the plane of the drawing).

[0017] The connecting pin 42, which is the connecting portion, is not limited to being engaged with the recess of the thumb roller support portion 122 of the slider 12, but may be engaged with another portion of the slider 12. The connecting portion may be any other joint mechanism as long as it has the function of transmitting the driving force in the measurement direction D from the drive unit 40 to the slider 12 (measuring member) while mitigating displacement or bending in directions other than the measurement direction D.

[0018] The drive roller 44 is a cylindrical roller made of metal such as stainless steel and rotatably supported by a shaft extending in the direction perpendicular to the drawing. The drive roller 44 is preferably a tapered roller with flanges on both sides. The drive roller 44 may also be made of an elastomer material such as synthetic rubber. The drive roller 44 has the same shape as the thumb roller or thumbwheel of a typical vernier caliper. One side of the shaft supporting the drive roller 44 is supported by the frame 41, and the drive roller 44 is pressed against the rolling surface 112 of the main scale 11 to roll. The drive roller 44 is connected to the motor 43 via a transmission mechanism 45 such as a gear train and is rotated by the driving force from the motor 43. The transmission mechanism 45 and the motor 43 are fixed to a gearbox 46 fixed to the outside of the frame 41. The transmission mechanism 45 is not limited to a gear mechanism; other transmission mechanisms, such as an existing belt pulley, may be used as long as they are capable of transmitting driving force from the motor 43 to the drive roller 44.

[0019] When the drive roller 44 is driven to rotate by the motor 43, a driving force in the measurement direction D is applied to the rolling surface 112 of the main scale 11 by frictional force. In order to ensure the frictional force between the drive roller 44 and the rolling surface 112, a pressing mechanism 50 is installed on the pressing surface 113 side of the frame 41 to press the pressing surface 113.

[0020] The pressing mechanism 50 includes a pair of pressing rollers 51 (pressing members) that are pressed against the pressing surface 113 at two positions in the measurement direction D on either side of the drive roller 44, and a coil spring 52 (urging member) that urges the pressing rollers 51 toward the pressing surface 113. The pressing rollers 51 are rotatably supported by the pressing mechanism 50 and can roll on the pressing surface 113. The pressing rollers 51 are cylindrical rollers made of metal such as stainless steel, and a ball bearing or the like is installed on the shaft to reduce rolling resistance. The pressing rollers 51 may also be tapered rollers with flanges on both sides. The pressing rollers 51 may also be made of an elastomer material such as synthetic rubber.

[0021] In the pressing mechanism 50, the two positions in the measurement direction D on either side of the drive roller 44 refer to two positions on either side of the position of the drive roller 44 in terms of coordinates on an axis extending in the measurement direction D. For example, these positions may be two positions on either side of position C, where a normal to the pressing surface 113 extending in the measurement direction D passes through the center of the drive roller 44. The number of pressing positions by the pressing roller 51 (pressing member) is not limited to two positions, and multiple positions may be used. It is preferable that such multiple positions are arranged symmetrically on both sides of position C passing through the center of the drive roller 44. In the pressing mechanism 50, each component, including the pressing roller 51, is configured symmetrically on both sides of position C in the measurement direction D of the drive roller 44.

[0022] 5 , the pressing mechanism 50 has a pantograph mechanism 59 including a pair of crossed swing arms 53, a connecting shaft 54 ​​that rotatably connects the middle portions of the pair of swing arms 53, and a pair of coil springs 52 (biasing members) installed between the pair of swing arms 53. A plate-shaped holding portion 411 is installed in a portion of the frame 41 of the drive unit 40 that faces the pressing surface 113, and the pantograph mechanism 59 is sandwiched between the holding portion 411 and the pressing surface 113.

[0023] In the pantograph mechanism 59, a pair of swing arms 53 each hold a pressure roller 51 (pressing member) at a tip end 531, and an end 532 opposite the tip end 531 abuts against the holding portion 411. A coil spring 52 (biasing member) is sandwiched in a compressed state between the tip end 531 of one of the pair of swing arms 53 and the vicinity of the end 532 of the other swing arm 53. In addition to a coil spring, other elastic members such as resin foam may also be used as the biasing member. The coil spring 52, which is the biasing member, biases each of the swing arms 53 in a direction in which one tip end 531 moves away from the other end 532. In other words, the coil spring 52 biases the pressure roller 51 (pressing member) supported by one of the pair of swing arms 53 in a direction in which it moves away from the holding portion 411 against which the other swing arm 53 abuts.

[0024] In the drive unit 40 described above, the pressing mechanism 50 presses the drive roller 44 against the rolling surface 112, thereby ensuring a desired frictional force between the drive roller 44 and the rolling surface 112, and the motor 43 drives the drive roller 44 to rotate, thereby applying a driving force from the drive roller 44 to the rolling surface 112 in the measurement direction D. The reaction force of the driving force from the drive roller 44 is transmitted to the slider 12 (measuring member) via the connecting pin 42, which serves as the connecting part, and the slider 12 is driven in the measurement direction D relative to the main scale 11 (reference member). Therefore, by controlling the operation of the motor 43, the slider 12 can be moved to any position on the main scale 11 (reference member) without manual operation by the user, and the operation of clamping the workpiece 9 (see FIG. 3) for measurement can be performed. In the drive unit 40, a clamping type pantograph mechanism 59 is used as the pressing mechanism 50, and in this pantograph mechanism 59, a pressure roller 51 (pressing member) is pressed against a pressing surface 113 by a coil spring 52 (urging member) at two positions on both sides of the drive roller 44. Therefore, the driving force of the drive roller 44 is appropriately transmitted to the rolling surface 112, and the pressure roller 51 presses the pressing surface 113 at two positions on both sides of the drive roller 44, so that the driving force by the drive roller 44 is the same in either direction of the measurement direction D.

[0025] 3 and 4 , the drive unit 40 is provided with a proximity sensor 47 that detects the approach of the workpiece 9. The proximity sensor 47 is a non-contact sensor element that uses electromagnetic radiation, such as infrared radiation, or acoustic radiation, such as ultrasonic radiation. The proximity sensor 47 may also be a non-contact distance sensor element that uses triangulation. A distance sensor can detect the relative distance from the proximity sensor 47 to the workpiece 9. Therefore, when this distance falls below a predetermined value, it is possible to control the measurement speed of the slider 12 to reduce the impact caused by contact between the workpiece 9 and the jaws 111 and 121. The proximity sensor 47 can detect the approach of the workpiece 9 to a predetermined area near the caliper 10. That is, the proximity sensor 47 emits a detection beam 471, such as infrared radiation, toward the vicinity of the jaws 111 and 121. When a user grips the workpiece 9 and attempts to introduce it between the jaws 111 and 121 during measurement, the workpiece 9 or the user's hand intersects with the detection beam 471, thereby enabling the proximity sensor 47 to detect the approach of the workpiece 9.

[0026] 1 and 2 , the caliper 10, which is the measuring device described above, is supported on a desk or the like by a stand 20, which is a support device. The stand 20 has a base 21, a support column 22 standing upright from the base 21, a clamp 23 attached midway along the support column 22, and a holder 24 supported by the clamp 23. The base 21 is formed, for example, from a metal block or a magnetic base, and has sufficient weight to ensure stability even when supporting the caliper 10. The support column 22 is formed, for example, from a metal round bar. The clamp 23 is annular, with the support column 22 inserted into it, and can be fixed at any height relative to the support column 22 using a releasable tightening mechanism or the like. The holder 24 has an elongated main body 241 supported at the center of its back surface by the clamp 23, and a pair of grips 242, 243 are formed on both ends of the main body 241. At least one of the gripping portions 242, 243 can be moved close to the other, and the caliper 10 can be held by sandwiching the main scale 11 of the caliper 10 between these gripping portions 242, 243.

[0027] [Control Device] The caliper 10, which is the measuring device described above, is connected to a control device 30. In Figures 1 and 2, the control device 30 has a housing 32 connected to the caliper 10 by a cable 31, and an operation unit 33, a proximity sensor changeover switch 38, and a display unit 34 are provided on the surface of the housing 32.

[0028] FIG. 6 shows an enlarged view of the operation unit 33 of the control device 30. The operation unit 33 allows the user to select functions set for each direction using a joystick or other lever on the surface of the housing 32 that can be tilted or slid up, down, left, or right. Selectable functions include, for example, the following. Each function will be described later. Upward: Measurement operation speed selection. Diagonally upward-left: Automatic measurement in the closing direction with dither. Diagonally upward-right: Automatic measurement in the opening direction with dither. Leftward: Automatic measurement in the closing direction. Rightward: Automatic measurement in the opening direction. Diagonally downward-left: High-speed movement in the closing direction. Diagonally downward-right: High-speed movement in the opening direction. Downward: Upper and lower tolerance settings. Of these, the "measurement operation speed selection" for the upward direction and the "upper and lower tolerance settings" for the downward direction relate to settings of the control device 30. Operations in the other directions instruct the drive unit 40 to move the slider 12 of the caliper 10 relative to the main scale 11 during measurement. The open direction and the close direction are the directions in which the jaws 111, 121 of the caliper 10 open (the direction in which the slider 12 moves to the right in FIG. 3 ) and close direction (the direction in which it moves to the left). Note that the following explanation illustrates the measurement of the outer dimensions of the workpiece 9 using the jaws 111, 121 of the caliper 10, with movement of the slider 12 in the close direction corresponding to application to the workpiece 9 and movement in the open direction corresponding to release from the workpiece 9. Note that when measuring the inner dimensions of the workpiece 9 using the jaws 114, 124, application to and release from the workpiece 9 are in the opposite directions, that is, movement of the slider 12 in the open direction corresponds to application to the workpiece 9 and movement in the close direction corresponds to release from the workpiece 9. The proximity sensor selector switch 38 switches between enabling and disabling the proximity detection function of the proximity sensor 47 described above.

[0029] 7 shows an enlarged view of the display unit 34 of the control device 30. The display unit 34 is configured, for example, with a liquid crystal display element capable of displaying two lines of 16 alphanumeric characters. The displayed contents include, for example, a measurement value 341, a lower limit tolerance 342, an upper limit tolerance 343, a measurement operation speed 344, and a measurement value judgment result 345. Of these, the measurement value 341 is a value measured by the vernier caliper 10, which is a measuring device. The lower limit tolerance 342 and the upper limit tolerance 343 are values ​​set in the control device 30 by operating the operation unit 33 downward. The measurement operation speed 344 is the speed (three levels: low speed "Low," medium speed "Mid," and high speed "High") at which the drive unit 40 drives the vernier caliper 10 during a measurement operation. The measurement value judgment result 345 is determined by the control device 30 based on the value (measurement value 341) measured by the caliper 10, and if the measurement value 341 is between the lower limit tolerance 342 and the upper limit tolerance 343, it is judged as passing (GO), and if not, it is judged as failing (NG).

[0030] FIG. 8 shows the functional blocks of the control device 30. The control device 30 is composed of a small computer system 35, and by executing stored programs, the desired functions, including the operation control unit 36 ​​and data processing unit 37, are deployed on the system. The operation control unit 36 ​​identifies the operation content of the operation unit 33, and when the operation is in the upward or downward direction described above, executes the "measurement operation speed selection" or "upper and lower tolerance setting" process, respectively. When the operation is in any other direction, it moves the drive unit 40 in the open or closed direction, causing the caliper 10 to perform automatic measurement or other operations. To control the movement of the drive unit 40, the operation control unit 36 ​​includes a movement control unit 361 and a stop control unit 362.

[0031] The movement control unit 361 can control the rotational speed of the motor 43 using PWM control, and moves the slider 12 (measuring member) using the drive unit 40 to bring the jaw 121 into contact with the workpiece 9. The movement control unit 361 drives the motor 43 of the drive unit 40 at a rotational speed adjusted by a predetermined duty ratio under PWM control, rotating the drive roller 44 and moving the drive unit 40 and slider 12 in the opening or closing direction along the main scale 11. By moving the slider 12 in the opening direction, the jaw 121 on the slider 12 side moves in a direction away from the jaw 111 on the main scale 11 side and the workpiece 9. The movement of the slider 12 in the opening direction can be stopped a predetermined time after the start of movement. This ensures a gap between the jaws 111 and 121 that allows the workpiece 9 to be introduced. The movement of the slider 12 in the opening direction may also be stopped by a separate operation.

[0032] When the movement control unit 361 is in a stopped state and the proximity sensor 47 is enabled by the proximity sensor changeover switch 38, it monitors the output of the proximity sensor 47 of the caliper 10, and when the proximity sensor 47 detects that the workpiece 9 has approached the caliper 10, it starts the drive unit 40 or moves the slider 12 (measuring member). This allows the user to automatically perform the operation of bringing the jaws 111, 121 into contact with the workpiece 9 simply by performing the operation of bringing the workpiece 9 closer to the jaws 111, 121.

[0033] The stop control unit 362 detects contact between the jaw 121 of the slider 12 and the workpiece 9 and stops the drive unit 40. By moving the slider 12 in the closing direction using the movement control unit 361, the jaw 121 on the slider 12 side moves in a direction approaching the jaw 111 on the main scale 11 side and the workpiece 9. The movement of the slider 12 in the closing direction is stopped when the jaw 121 abuts against the workpiece 9 and the workpiece 9 is sandwiched between the jaw 121 and the jaw 111. The detector 13 detects the relative position of the slider 12 with respect to the main scale 11. While the slider 12 is moving, the measurement value (detected position value) detected by the detector 13 changes successively. When the movement of the slider 12 is stopped by abutting against the workpiece 9, the measurement value detected by the detector 13 remains constant.

[0034] The stop control unit 362 measures and monitors the measurement value detected by the detector 13 and the current value of the drive current supplied to the motor 43 while the movement control unit 361 moves the slider 12 in the closing direction. If the measurement value detected by the detector 13 continues to change, the stop control unit 362 determines that the slider 12 is moving normally and continues the movement in the closing direction by the movement control unit 361. Note that if the measurement value detected by the detector 13 continues to change but the current value of the drive current exceeds a predetermined threshold, it is possible that the load on the motor 43 is increasing due to abnormal sliding caused by the inclusion of dust or other foreign matter, and appropriate measures to address the abnormal movement, such as cleaning, are taken. If the measurement value detected by the detector 13 remains constant and does not change, and the current value of the drive current to the motor 43 exceeds a predetermined threshold, the stop control unit 362 determines that the jaw 121 has contacted the workpiece 9, performs a predetermined stopping operation, and then stops the movement in the closing direction by the movement control unit 361. A more accurate determination can be made by measuring the drive current value multiple times in succession and calculating the average value. In addition, if the measurement value by the detector 13 is constant but the current value of the drive current does not exceed a predetermined threshold and movement continues, there is a possibility that an abnormality such as a reading error has occurred in the detector 13, and appropriate measures such as inspection should be taken to address the abnormality.

[0035] As described above, by monitoring two types of values, the stop control unit 362 does not determine that contact has occurred, even if, for example, a reading error occurs in the detector 13 and the same measured value is continuously output (i.e., a constant value), unless the current value exceeds the threshold. Next, if dust or other foreign matter gets into the main beam 11 while the slider 12 is moving, deteriorating the sliding properties, and the measured value continues to change even though the current value of the drive current exceeds a predetermined threshold, contact is not determined. This allows for the construction of a system that is robust against measurement anomalies.

[0036] The stop control unit 362 executes a dithering process and a constant-pressure contacting process as the stopping operation. In the dithering process, when the stop control unit 362 detects contact between the jaw 121 and the workpiece 9, the stop control unit 362 repeatedly moves the jaw 121 away from the workpiece 9 using the drive unit 40 and then brings the jaw 121 back into contact with the workpiece 9. Specifically, the drive unit 40 moves back and forth in the opening and closing directions by rapidly rotating the motor 43 forward and backward, and repeatedly brings the jaw 121 into contact with the workpiece 9 during movement in the closing direction. This allows the contact state between the jaw 121 and the workpiece 9 to be adjusted. The vibrations generated by rapidly rotating the motor 43 forward and backward in this manner create a so-called dithering effect, which smooths out the contact between the jaw and the workpiece. The constant-pressure contacting process is executed following the dithering process described above. In the constant pressure contact process, a constant pressure current is supplied to the motor 43, the workpiece 9 is brought into contact with the jaws 121 at a constant pressure, and this state is maintained for a predetermined time. As a result, the workpiece 9 is properly sandwiched between the jaws 111 and 121, and the outer dimensions of the workpiece 9 are measured by the caliper 10.

[0037] When the instruction from the operation unit 33 is "automatic measurement in the closing direction with dither" or "automatic measurement in the opening direction with dither," both dither processing and constant pressure contact processing are executed as the stopping operation, but when "automatic measurement in the closing direction" or "automatic measurement in the opening direction" is instructed, dither processing is omitted. The movement speed by the drive unit 40 in these automatic measurements is based on the "measurement operation speed" set by the operation unit 33. However, when "high-speed movement in the closing direction" or "high-speed movement in the opening direction" is specified, the movement speed is always set to the maximum, and recording of measurement values ​​is omitted.

[0038] With the workpiece 9 properly clamped between the jaws 111, 121 by the operation control unit 36 ​​and drive unit 40, the data processing unit 37 records the current measurement value obtained from the caliper 10, and executes predetermined processing using the measurement value calculation unit 371 and pass / fail determination unit 372. The measurement value calculation unit 371 processes the measurement value from the caliper 10 and records it as the outer dimension of the workpiece 9, and displays it on the display unit 34 as the measurement value 341. The pass / fail determination unit 372 records the lower and upper tolerances set by the operation unit 33 and displays them on the display unit 34 as the lower and upper tolerances 342 and 343, and displays the measurement value determination result 345 as pass "GO" if the obtained measurement value of the workpiece 9 is between the lower and upper tolerances, or as fail "NG" if it is not.

[0039] [Measurement Operation] Figure 9 shows the operation of measuring the outer dimensions of the workpiece 9 using the measurement system 1 of this embodiment. To perform the measurement, the user selects the measurement operation speed and sets the upper and lower tolerance limits in the control device 30, and then issues a measurement command (e.g., "automatic measurement with dithering in the closing direction") via the operation unit 33. When the user brings the workpiece 9 close between the jaws 111 and 121 for measurement, if the proximity sensor 47 is enabled, the movement control unit 361 detects the approach of the workpiece 9 and automatically initiates operation by the drive unit 40 (Process S1). The introduction of the workpiece 9 can be performed manually by the user or fully automated using another handling robot. In the control device 30, the movement control unit 361 supplies a drive current to the motor 43, and the drive unit 40 moves the slider 12 in the closing direction at a predetermined speed (Process S2). During the movement, the stop control unit 362 monitors the measurement value from the detector 13 and the current value of the drive current to the motor 43, and determines whether the workpiece 9 has come into contact with the jaw 121 (process S3). If the stop control unit 362 does not determine whether the workpiece 9 has come into contact with the jaw 121, it repeats the movement of the slider 12 (process S2) and the determination of contact (process S3). On the other hand, if it determines whether the workpiece 9 has come into contact with the jaw 121, it executes a stop operation.

[0040] As a stopping operation, the stop control unit 362 determines whether the measurement operation instructed by the user is dithered (process S5), and if so, performs dither processing. In dither processing, the drive current is controlled to repeatedly rotate the motor 43 forward and backward for short periods of time, adjusting the contact state between the workpiece 9 and the jaw 121 (process S6). Following dither processing, a constant-pressure contact processing is performed. In constant-pressure contact processing, a constant-pressure current is supplied to the motor 43, causing constant-pressure contact between the workpiece 9 and the jaw 121 (process S7), and the system waits for a predetermined time to elapse (process S8).

[0041] After the above stopping operation, the control device 30 causes the measurement value calculation unit 371 to calculate the measurement value and display it on the display unit 34, and the pass / fail judgment unit 372 to judge whether the measurement value is pass / fail and display the judgment result on the display unit 34 (Process S9). Once the desired measurement result is obtained, the user issues a command for "high-speed movement in the opening direction" via the operation unit 33 to remove the workpiece 9. In the control device 30 that received the command, the movement control unit 361 supplies a drive current to the motor 43, and the drive unit 40 moves the slider 12 in the opening direction at a predetermined speed (Process S10). The movement control unit 361 repeats the movement until it is determined that a predetermined time has elapsed (Process S11), and then stops the motor 43 when the predetermined time has elapsed (Process S12). As a result, the slider 12 stops at a position away from the workpiece 9, and the jaw 121 is separated from the workpiece 9, allowing the user to remove the workpiece 9. As described above, the measurement system 1 of this embodiment can be used to measure the outer dimensions of the workpiece 9.

[0042] [Operation and Effect of the Present Embodiment] In the present embodiment, the caliper 10 (measuring device) is configured by adding a drive unit 40 to a measuring device main body that is made up of a main scale 11 (reference member), a slider 12 (measuring member), and a detector 13. In the measuring device main body, the main scale 11, slider 12, and detector 13 provide a basic function for measuring the dimensions of the workpiece 9. Components of an existing measuring device can be reused as the main scale 11, slider 12, and detector 13.

[0043] In the drive unit 40, the pressing mechanism 50 presses the drive roller 44 against the rolling surface 112, thereby ensuring a desired frictional force between the drive roller 44 and the rolling surface 112, and the motor 43 drives the drive roller 44 to rotate, thereby applying a driving force from the drive roller 44 to the rolling surface 112 in the measurement direction. The reaction force of the driving force from the drive roller 44 is transmitted to the slider 12 (measuring member) via the connection pin 42 (connection part), and the slider 12 is driven in the measurement direction D relative to the main scale 11 (reference member). Therefore, by controlling the motor 43 in the drive unit 40, the movement of the slider 12 relative to the main scale 11 can be controlled, and the measurement operation can be automated.

[0044] In the drive unit 40, a pressure roller 51 (pressing member) is pressed against the pressing surface 113 by a coil spring 52 (biasing member) at two positions (multiple positions) on either side of the drive roller 44 in the measurement direction. This stabilizes the position of the drive unit 40 relative to the main scale 11 (reference member), providing a stable pressing force regardless of the direction of the driving force from the drive roller 44 in the measurement direction D, thereby stabilizing the driving force applied from the drive roller 44 to the rolling surface 112. The drive unit 40 uses a pair of pressure rollers 51 as the pressing members, which are rotatably supported by the pressing mechanism 50 and can roll on the pressing surface 113. The rolling pressure rollers 51 can reduce movement resistance in the measurement direction D even when pressed against the pressing surface 113, which is effective in stabilizing the measurement operation. Furthermore, a bearing mechanism such as a ball bearing can be used to support the pressure rollers 51, further reducing operating resistance.

[0045] In the drive unit 40, the pressing mechanism 50 has a pantograph mechanism 59 having a pair of swinging arms 53 whose middle portions are connected so as to be freely rotatable, and a coil spring 52 (urging member) installed between the pair of swinging arms 53, and the pantograph mechanism 59 is arranged between the pressing surface 113 and a holding portion 411 that faces the pressing surface 113 of the drive unit 40, and the pair of swinging arms 53 each hold a pressing roller 51 (pressing member) at a tip portion 531, and an end portion 532 opposite the tip portion 531 abuts against the holding portion 411, and the coil spring 52 is configured to urge the swinging arm 53 in a direction such that the pressing roller 51 moves away from the holding portion 411. Therefore, the pair of swing arms 53 are urged by the coil spring 52, which serves as a urging member, and the pantograph mechanism 59 is urged in a direction extending from the holding portion 411 toward the pressing surface 113, thereby pressing the pressing roller 51, which serves as a pressing member, against the pressing surface 113. In the drive unit 40, the pressing force against the pressing surface 113 can be set to a predetermined value by the coil spring 52. The coil spring 52 is installed between the pair of swing arms 53 and can always generate a predetermined pressing force against the pressing surface 113 regardless of the frame 41 of the drive unit 40, thereby stabilizing the driving force. The urging member can be an elastic member such as a coil spring or resin foam.

[0046] As described above, with the caliper 10 (measuring device) of this embodiment, adding the drive unit 40 to the measuring device main body, which is composed of the main scale 11 (reference member), slider 12 (measuring member), and detector 13, automates the measurement operation, improving operability. In the drive unit 40, the slider 12 (measuring member) is moved using the driving force of the motor 43 and drive roller 44, while the driving force is stabilized by the pressing mechanism 50, thereby stabilizing the measurement operation. Furthermore, elements of an existing measuring device can be reused as the main scale 11, slider 12, and detector 13, which make up the measuring device main body, thereby reducing costs.

[0047] In this embodiment, the measurement system 1 is configured by combining the above-mentioned caliper 10 (measuring device) with a control device 30 that controls the detector 13 and drive unit 40, and the control device 30 has a movement control unit 361 that uses the drive unit 40 to move the slider 12 (measuring member) relative to the main scale 11 (reference member) and bring it into contact with the workpiece 9, and a stop control unit 362 that detects contact between the jaw 121 on the slider 12 and the workpiece 9 and stops the drive unit 40. In the measurement system 1 having such a control device 30, after the user has set up the control device 30, if the proximity sensor 47 is enabled, control of the drive unit 40 by the control device 30 is started by bringing the workpiece 9 close to the caliper 10, and the measurement operation of the workpiece using the caliper 10 can be automated. In the control device 30, the proximity sensor 47 or the movement control section 361 detects the approach of the workpiece 9 and automatically starts the drive unit 40, causing the slider 12 to move toward the workpiece 9, and when the jaw 121 on the slider 12 side comes into contact with the workpiece 9, the stop control section 362 stops the drive unit 40. Thereafter, the position of the slider 12 relative to the main scale 11 is detected by the detector 13, allowing the dimensions of the workpiece 9 to be measured.

[0048] The stop control unit 362 references two types of values, the position value detected by the detector 13 and the current value of the drive current of the drive unit 40, and determines that the jaw 121 on the slider 12 side and the workpiece 9 are in contact when the position detected by the detector 13 remains constant over a predetermined time period and the current value of the drive current exceeds a predetermined threshold. The stop control unit 362 can reliably detect contact between the jaw 121 on the slider 12 side and the workpiece 9 by simultaneously referencing the fact that the position detected by the detector 13 remains constant over a predetermined time period, i.e., a state in which the movement of the slider 12 is blocked by the workpiece 9 abutting against the jaw 121, and the fact that the current value of the drive current exceeds a predetermined threshold, i.e., a state in which the movement is blocked despite continued drive by the motor 43. In contrast, even if a reading error occurs in the detector 13 and the same measurement value is continuously output (i.e., a constant value), it is not determined that contact has occurred unless the current value exceeds the threshold. Furthermore, if dust or other foreign matter gets into the main scale 11 while the slider 12 is moving, deteriorating the sliding properties and the measured value continues to change even when the current threshold is exceeded, contact will not be determined. This makes the system robust against measurement anomalies.

[0049] When the stop control unit 362 detects contact between the jaw 121 on the slider 12 side and the workpiece 9, the stop control unit 362 performs a dithering process by causing the drive unit 40 to move the jaw 121 on the slider 12 side away from the workpiece 9 and then bring the jaw 121 on the slider 12 side back into contact with the workpiece 9. By performing such a dithering process, the stop control unit 362 repeats the operation of the jaw 121 on the slider 12 side contacting and separating from the workpiece 9 multiple times, thereby stabilizing the contact state between the jaw 121 on the slider 12 side and the workpiece 9 and also enabling the removal of dust from the contact area, thereby obtaining a stable measurement state.

[0050] Following the dithering process described above, the stop control unit 362 further performs a constant pressure contact process in which the jaw 121 on the slider 12 side is pressed against the workpiece 9 with a constant pressure for a predetermined time, and then stops the movement control unit 361. By performing such a constant pressure contact process, the stop control unit 362 presses the jaw 121 on the slider 12 side against the workpiece 9 with a constant pressure for a predetermined time, thereby obtaining more stable measurement results.

[0051] The measurement system 1 of this embodiment uses a stand 20 (support device) that supports the caliper 10 (measuring device), and the stand 20 has a holder 24 that supports the end of the main scale 11 (reference member). In such a stand 20, the measuring device can be supported by the holder 24, and measurement of the workpiece 9 can be performed efficiently by holding the workpiece 9 between the jaws 111, 121 of the caliper 10 and then operating the drive unit 40 with the control device 30. When supporting the caliper 10, the holder 24 supports the end of the main scale 11, so it does not interfere with the movement of the slider 12.

[0052] Second Embodiment Figure 10 shows a pressing mechanism 50A according to a second embodiment of the present invention. This embodiment has the same basic configuration as the first embodiment described above, but differs in the configuration of the pressing mechanism. In the pressing mechanism 50 of the first embodiment described above (see Figure 5), the pantograph mechanism 59 is configured using a pair of pressing rollers 51 as pressing members, a pair of coil springs 52 as biasing members, and a pair of swing arms 53, and is sandwiched between the pressing surface 113 and the holding portion 411. In contrast, the pressing mechanism 50A of this embodiment uses a single coil spring 52A as the biasing member of the pantograph mechanism 59A.

[0053] In the pressing mechanism 50A, the pantograph mechanism 59A is configured by rotatably connecting the intermediate portions of a pair of swing arms 53A via a connecting shaft 54. A pressure roller 51 is rotatably supported on the tip end 531 of each swing arm 53A, and each pressure roller 51 abuts against the pressing surface 113. The opposite ends of each swing arm 53A are formed in an L-shape, and each end 532 abuts against the holding portion 411. The pair of end portions 532 are disposed opposite each other across position C in the measurement direction D of the drive roller 44, and a coil spring 52A is stretched between them under tension. In the pantograph mechanism 59A, the coil spring 52A biases the pair of end portions 532 toward each other, and the pair of swing arms 53A biases each pressure roller 51 in a direction away from the holding portion 411. As a result, the pantograph mechanism 59A is sandwiched between the pressing surface 113 and the holding portion 411 of the drive unit 40 that faces the pressing surface 113, and the pressing surface 113 is pressed by the pressing roller 51. With this embodiment, too, it is possible to obtain the same effects as those of the first embodiment described above.

[0054] Third Embodiment Figure 11 shows a pressing mechanism 50B according to a third embodiment of the present invention. This embodiment has the same basic configuration as the first embodiment described above, but differs in the configuration of the pressing mechanism. In the pressing mechanism 50 of the first embodiment described above (see Figure 5), a pantograph mechanism 59 having a pair of swing arms 53 is sandwiched between the pressing surface 113 and the holding portion 411. In contrast, the pressing mechanism 50B of this embodiment does not use a pantograph mechanism, and each of the pair of swing arms 53B is swingably supported on the frame 41 of the drive unit 40.

[0055] The pressing mechanism 50B has a pair of swinging arms 53B arranged along the pressing surface 113. The pair of swinging arms 53B are rotatably supported at their mutually closer ends by a support shaft 54B, and the support shaft 54B has its end supported by the frame 41 of the drive unit 40. The ends of the pair of swinging arms 53B that are mutually distant from each other hold pressure balls 51B as pressing members. The pressure balls 51B are formed of a low-friction resin material or a steel ball and are capable of rolling on the pressing surface 113. Receiving portions 533 are formed in the middle of each of the pair of swinging arms 53B, and a coil spring 52B is interposed in a compressed state between the pair of receiving portions 533. The coil springs 52B bias the pair of swinging arms 53B in a direction that presses the pressure balls 51B against the pressing surface 113. In the pressing mechanism 50B, the pair of swing arms 53B, the pair of support shafts 54B, the pair of pressing balls 51B, the pair of receiving portions 533, and the coil spring 52B are arranged symmetrically on both sides of the position C in the measurement direction D of the drive roller 44. Therefore, in the pressing mechanism 50B, the pressing ball 51B, which is a pressing member, is pressed against the pressing surface 113 by the coil spring 52B, which is a biasing member, and the pressing mechanism 50B can achieve the same function as the pressing mechanism 50 of the first embodiment described above. In this embodiment as well, the same effects as in the first embodiment described above can be achieved.

[0056] [Fourth Embodiment] Figure 12 shows a pressing mechanism 50C according to a fourth embodiment of the present invention. This embodiment has the same basic configuration as the first embodiment described above, but the configuration of the pressing mechanism is different. In the pressing mechanism 50B of the third embodiment described above (see Figure 11), a pair of swing arms 53B were each swingably supported on the frame 41 of the drive unit 40. Furthermore, each swing arm 53B used a pressing ball 51B that rolls on a pressing surface 113. In contrast, the pressing mechanism 50C of this embodiment uses a single swing arm 53C and a pressing pad 51C that slides on the pressing surface 113 as a pressing member.

[0057] In the pressing mechanism 50C, a single swing arm 53C is swingably supported on the frame 41 by a central support shaft 54C. A pressing pad 51C, which serves as a pressing member, is provided on each end of the swing arm 53C. The pressing pad 51C is formed of a material whose surface that slides against the pressing surface 113 is coated with a low-friction resin such as fluororesin, or the pressing pad 51C itself is made of a low-friction resin. A coil spring 52C, which serves as a biasing member, is interposed in a compressed state between the pressing pad 51C and the swing arm 53C, and the pressing pad 51C is pressed against the pressing surface 113 by the coil spring 52C. In the pressing mechanism 50C, the swing arm 53C, the support shaft 54C, the pair of pressing pads 51C, and the pair of coil springs 52C are also arranged symmetrically on both sides of position C in the measurement direction D of the drive roller 44. In the pressing mechanism 50C, the pressure pads 51C are pressed against the pressing surfaces 113 by the coil springs 52C, the swing arms 53C swing in response to the reaction force from the coil springs 52C, and the pair of pressure pads 51C press the pressing surfaces 113 on each side evenly. In this embodiment as well, the same effects as in the first embodiment can be obtained.

[0058] Fifth Embodiment Figures 13 and 14 show a pressing mechanism 50D according to a fifth embodiment of the present invention. This embodiment has the same basic configuration as the first embodiment described above, but differs in the configuration of the pressing mechanism. In the pressing mechanism 50 of the first embodiment described above (see Figure 5), a pantograph mechanism 59 having a pair of swing arms 53 and a coil spring 52 (biasing member) supports the pressing roller 51 (pressing member), and the pantograph mechanism 59 is sandwiched between the pressing surface 113 and the holding portion 411 to press the pressing roller 51 against the pressing surface 113. In contrast, the pressing mechanism 50D of this embodiment does not use a pantograph mechanism, but instead uses a leaf spring-like swing arm 553 that also functions as a swing arm and biasing member to support the pressing roller 51 and press it against the pressing surface 113.

[0059] The pressing mechanism 50D has a base plate 550 installed on the inner surface of the frame 41 facing the pressing surface 113. The base plate 550 is made of an elastic material, such as steel, that can be processed into sheet metal. The base plate 550 has a rectangular planar shape extending along the measurement direction D. By making cuts 551 along the long sides from both short sides and making acute bends 552, swing arms 553 are formed that rise obliquely toward the measurement direction D and tilt in opposite directions. Tips 554 of the swing arms 553 are rounded, and ends of shaft members 555 are supported inside each pair of tips 554 on both sides aligned in a direction intersecting the measurement direction D. A pressing roller 51 (pressing member) is supported at the middle of each shaft member 555.

[0060] The pressure roller 51 is supported by a pair of swing arms 553 and pressed against the pressure surface 113. The swing arms 553 also function as biasing members, and the elasticity of the swing arms 553 biases the pressure roller 51 toward the pressure surface 113, ensuring a desired pressing force against the pressure surface 113. That is, with the pressure roller 51 (pressing member) pressed against the pressure surface 113, the length and angle of the swing arms 553 can be adjusted according to the distance between the substrate 550 and the pressure surface 113, thereby allowing the elasticity of the pair of swing arms 553 on each side, which also function as biasing members, to press the pressure roller 51 against the pressure surface 113 with a predetermined pressing force. In the pressing mechanism 50D, the swing arms 553, the shaft members 555, and the pressure roller 51 are also arranged symmetrically on both sides of the position C in the measurement direction D of the drive roller 44. This embodiment also achieves the same effects as the first embodiment. Furthermore, in this embodiment, an elastic plate material is used as the substrate 550, and by cutting a portion of the substrate 550 by sheet metal processing and bending it at a predetermined angle, the swing arm 553 can be formed continuously from the substrate 550, making manufacturing easy and inexpensive. Note that the swing arm 553 may be formed by connecting a leaf spring to the substrate 550, or the swing arm 553 may be made of an arm material with low elasticity and supported on the substrate 550 via a support member made of elastic material as a biasing member.

[0061] Other Embodiments The present invention is not limited to the above-described embodiments, and modifications within the scope of achieving the object of the present invention are included in the present invention. In the above-described embodiments, the caliper 10 was used as an example of a measuring device for measuring the dimensions of a workpiece. However, the present invention can also be applied to measuring devices that use a reference member and a measuring member, such as a height gauge or a depth gauge, that are relatively movable in the measurement direction and can contact the workpiece. In the measurement system of the above-described embodiment, dithering and constant pressure contact processes were performed when contacting or stopping the workpiece 9. However, these processes may be omitted as appropriate if the material of the workpiece 9 provides good stability during contact. In the above-described embodiments, the control configuration of the control device 30 and the specific configurations of the operation unit 33 and display unit 34 are merely examples, and different configurations may be used as long as the functionality of the measurement system 1 of the present invention is obtained.

[0062] 1...Measuring system, 10...Caliper (measuring device), 11...Main scale (reference member), 111...Jaw, 112...Rolling surface, 113...Pressing surface, 12...Slider (measuring member), 121...Jaw, 122...Thumb roller mounting portion, 13...Detector, 14...Display unit, 20...Stand (support device), 21...Base, 22...Support, 23...Clamp, 24...Holder, 241...Main body, 242...Gripping portion, 243...Gripping portion, 30 ...Control device, 31...Cable, 32...Housing, 33...Operation unit, 34...Display unit, 341...Measured value, 342...Lower limit tolerance, 343...Upper limit tolerance, 344...Measurement operation speed, 345...Measurement value judgment result, 35...Computer system, 36...Operation control unit, 361...Movement control unit, 362...Stop control unit, 37...Data processing unit, 371...Measurement value calculation unit, 372...Acceptance / failure judgment unit, 38...Proximity sensor changeover switch, 4 0... drive unit, 41... frame, 411... holding portion, 42... connection pin (connection portion), 43... motor, 44... drive roller, 45... transmission mechanism, 46... gear box, 47... proximity sensor, 471... detection beam, 50, 50A, 50B, 50C, 50D... pressure mechanism, 51... pressure roller (pressing member), 51B... pressure ball (pressing member), 51C... pressure pad (pressing member), 52, 52A, 52B, 52C...coil spring (biasing member), 53, 53A, 53B, 53C...oscillating arm, 531...tip portion, 532...end portion, 533...receiving portion, 54...connecting shaft, 54B, 54C...support shaft, 550...substrate, 551...notch, 552...bending, 553...oscillating arm (also serves as biasing member), 554...tip portion, 555...shaft member, 59, 59A...pantograph mechanism, 9...workpiece, D...measurement direction, S1 to S12...processing.

Claims

1. A measuring device for measuring the dimensions of a workpiece, comprising: a reference member and a measuring member that are movable relative to each other in a measurement direction and can each come into contact with the workpiece; a detector that can detect the relative position of the measuring member with respect to the reference member; and a drive unit that moves the measuring member in the measurement direction relative to the reference member, wherein the reference member has a rolling surface that extends in the measurement direction and a pressing surface that is parallel to the rolling surface and extends in the measurement direction on the opposite side to the rolling surface, and the drive unit has a connection part that is connected to the measuring member and can transmit a driving force in the measurement direction, a drive roller that is driven by a motor and can roll on the rolling surface, and a pressing mechanism that presses the pressing surface, wherein the pressing mechanism has a pair of pressing members that are pressed against the pressing surface at multiple positions on both sides of the drive roller in the measurement direction, and a biasing member that biases the pressing member toward the pressing surface.

2. A measuring device according to claim 1, wherein the pressing member is a pair of pressing rollers rotatably supported by the pressing mechanism and capable of rolling on the pressing surface.

3. A measuring device according to claim 1 or 2, wherein the pressing mechanism comprises a pantograph mechanism having a pair of swinging arms rotatably connected at their intermediate portions, and the biasing member installed between the pair of swinging arms, the pantograph mechanism being disposed between the pressing surface and a holding portion of the drive unit that faces the pressing surface, the pair of swinging arms each having the pressing member held at its tip, and the end opposite the tip abutting against the holding portion, and the biasing member biases the swinging arm in a direction that moves the pressing member away from the holding portion.

4. A measuring device according to claim 1 or claim 2, wherein the pressing mechanism has a pair of oscillating arms with the pressing member held at the tip thereof, the pair of oscillating arms each rising obliquely from a base plate facing the pressing surface and formed with directions of inclination opposite to each other, and the pair of oscillating arms each formed from an elastic member and also serving as the biasing member.

5. The measuring device according to claim 1 or 2, further comprising a proximity sensor for detecting the proximity of the workpiece.

6. A drive unit mounted on a measuring device main body, the drive unit moving the measuring member in the measurement direction relative to the reference member, the drive unit having a reference member and a measuring member that are movable relative to each other in the measurement direction and can each come into contact with a workpiece, and a detector that can detect the relative position of the measuring member with respect to the reference member, the reference member having a rolling surface that extends in the measurement direction and a pressing surface on the opposite side to the rolling surface that is parallel to the rolling surface and extends in the measurement direction, the drive unit having a connection part connected to the measuring member and capable of transmitting a driving force in the measurement direction, a drive roller that is driven by a motor and can roll on the rolling surface, and a pressing mechanism that presses the pressing surface, the pressing mechanism having a pair of pressing members that are pressed against the pressing surface at multiple positions on both sides of the drive roller in the measurement direction, and a biasing member that biases the pressing member toward the pressing surface.

7. A measurement system comprising the measuring device according to claim 1 and a control device for controlling the detector and the drive unit, wherein the control device comprises a movement control section for using the drive unit to move the measuring member relative to the reference member and bring it into contact with the workpiece, and a stop control section for detecting contact between the measuring member and the workpiece and stopping the drive unit.

8. A measuring system as described in claim 7, wherein the stop control unit refers to the position value detected by the detector and the value of the drive current of the drive unit, and determines that the measuring member and the workpiece are in contact when the position value detected by the detector remains constant for a predetermined time and the current value of the drive current exceeds a predetermined threshold value.

9. A measuring system as described in claim 7, wherein the stop control unit, upon detecting contact between the measuring member and the workpiece, repeats the operation of moving the measuring member away from the workpiece by the drive unit and the operation of bringing the measuring member into contact with the workpiece again a plurality of times, and then stops the movement control unit.

10. A measuring system as described in claim 7, wherein, when the stop control unit detects contact between the measuring member and the workpiece, the stop control unit causes the drive unit to move the measuring member away from the workpiece and then bring the measuring member back into contact with the workpiece, repeating this operation multiple times, and then pressing the measuring member against the workpiece with a constant pressing force for a predetermined period of time, and then stopping the movement control unit.

11. A measuring system according to claim 7, wherein the movement control section detects that the workpiece has approached the measuring device and moves the measuring member using the drive unit.

12. A measurement system according to claim 7, further comprising a support device for supporting said measurement device, said support device having a holder for supporting an end of said reference member.

13. A measuring method for measuring the dimensions of a workpiece using the measuring device described in claim 1, comprising: moving the measuring member relative to the reference member using the drive unit, bringing the measuring member into contact with the workpiece; detecting contact between the measuring member and the workpiece using the detector; stopping the drive unit; and measuring the dimensions of the workpiece using the detector.

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