Outside diameter measuring device

Abstract

To adjust a temperature characteristic of an outside diameter measurer over a wide range for one type of a material and for one shape of a component.SOLUTION: In a contact type outside diameter measurer for measuring an outside diameter of workpiece 55, there is included a sensor rod 20, one end of which is a tip part S including a contact piece 21 that is in contact with the workpiece 55, and the other end is connected to a linear scale 6 of a sensor part G that detects a movement distance of the contact piece 21. The sensor part G includes a substrate 3 provided with a sensor 4 that detects the movement distance of the linear scale 6 so as to detect the movement distance of the contact piece 21, an attachment plate 1 to which the substrate 3 is fixed via a substrate fitting hole 7 of the substrate 3, a sensor part body 10-2 which is of a lower thermal expansion material than the attachment plate 1, and a plurality of screws 5 for fixing the attachment plate 1 to the sensor part body 10-2 via each of two fitting holes 2 provided to the attachment plate 1.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a contact type outer diameter measuring instrument that measures, for example, the outer diameter of a cylindrical workpiece with high precision, and a method for adjusting its temperature characteristics, and is particularly suitable for attaching the outer diameter measuring instrument to a machine tool, grinding device, etc. for automatic measurement. [Background technology]

[0002] In the past, flexible and automated processing machines were used as a means of responding to market trends such as diversification of products and shortening of product life cycles, and in-process measurement is required to maintain and monitor processing quality regardless of small, medium, or mass production. In-process measurement requires highly reliable, highly accurate, and efficient measurements in the environment of the processing site. In addition, contact-type outer diameter measuring devices that abut a contactor against the master and workpiece are widely used to fully avoid the effects of cutting chips, cutting fluid, temperature fluctuations, machine vibrations, etc.

[0003] For example, in crankshaft processing machines such as crankshaft grinding machines used in automobile engines, in-process measurement is performed by measuring the outer diameter of a crankpin that rotates around the axis of a journal with an outer diameter measuring gauge while the crankpin is being ground. A known outer diameter measuring instrument measures the radius of a crankpin by contacting the outer periphery of the crankpin at three points, namely, a V-shaped block and a contact piece between the blocks, and is described in, for example, Patent Document 1.

[0004] Furthermore, in order to hold the workpiece more securely and obtain an accurate workpiece diameter even if there is a risk of measurement fluctuations due to assembly errors in the measuring device or vibrations such as chatter occur during processing of the workpiece, it is known to provide a digital sensor having a contact at its tip that comes into contact with the workpiece, and a V-base extending in the longitudinal direction and having a through hole formed in the center to accommodate the digital sensor, and the sensor is a linear sensor whose tip comes into contact with the object to be measured and is biased to press against the object to be measured, detecting fluctuations in the size of the object to be measured as the distance traveled by the tip, and this is described in Patent Document 2. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2007-160458 A [Patent Document 2] JP 2017-67512 A Summary of the Invention [Problem to be solved by the invention]

[0006] The outer diameter measuring gauges described in Patent Documents 1 and 2 measure the outer diameter of crankpins during grinding, and therefore are significantly affected in accuracy by not only machine vibrations but also large temperature fluctuations in the machining site environment and heat transfer from the workpiece being machined. Therefore, when measuring a workpiece being machined, such as measuring crankpins, it is necessary to adjust the temperature characteristics of the outer diameter measuring instrument. In addition, the temperature characteristics of the outer diameter measuring instrument are adjusted by assembling parts with the same shape but different thermal expansion coefficients.

[0007] Therefore, parts for adjusting temperature characteristics must be prepared in advance and replaced in multiple parts of the same shape and made of multiple materials, which makes inventory management difficult. Furthermore, preparing parts of the same shape and made of multiple materials results in low-volume production, and labor is required each time a part is replaced during adjustment, which results in high costs.

[0008] The object of the present invention is to solve the problems of the prior art and to adjust the temperature characteristics of a wide range of outer diameter measuring instruments using a small number of parts, ideally one type of material and one shape. In addition, the object of the present invention is to facilitate inventory management, perform simple and simplified adjustments, reduce labor, and reduce costs. Another object of the present invention is to ensure high and stable measurement accuracy and repeatability regardless of the environmental conditions at the processing site, especially the temperature conditions. [Means for solving the problem]

[0009] The present invention, which achieves the above object, is configured as follows. [1] An outer diameter measuring instrument comprising: a sensor rod having a contactor that abuts against a workpiece and extends in a longitudinal direction; and a sensor unit that detects the distance traveled by the contactor, wherein the sensor unit has a mounting plate whose fixed position can be adjusted in the left-right direction intersecting the longitudinal direction, a linear scale connected to the end of the sensor rod opposite the contactor, and a sensor that detects the distance traveled by the linear scale, wherein the sensor moves in the longitudinal direction in accordance with the amount of extension of the mounting plate in the left-right direction due to temperature. [2] The outer diameter measuring instrument described in [1], characterized in that the mounting plate is fixed to a member having a lower thermal expansion than the mounting plate at the sensor portion. [3] The outer diameter measuring instrument described in [1] or [2], characterized in that the mounting plate has a mounting hole and is fixed by a fixing member attached to the mounting hole. [4] The outer diameter measuring instrument described in [3], characterized in that the mounting hole includes a plurality of mounting holes arranged in the left-right direction, the fixing member includes a plurality of fixing members, and the mounting plate is fixed by the plurality of fixing members which are respectively attached to the plurality of mounting holes. [5] The outer diameter measuring instrument described in [4], characterized in that the mounting plate has a V-shaped notch in the center in the left-right direction. [6] The outer diameter measuring instrument described in [5], characterized in that the depth of the cut is deeper than the position of the mounting hole in the longitudinal direction. [7] The outer diameter measuring instrument described in [4], characterized in that the mounting plate comprises an arc-shaped rib J provided between the multiple mounting holes to which the multiple fixing members are respectively attached, a rib L in which the mounting holes are provided, and an X-shaped rib K connecting the rib J and the rib L.

[0010] Another configuration of the present invention that achieves the above object is as follows. [1] An outer diameter measuring instrument comprising: a sensor rod having a contactor that abuts against a workpiece; and a sensor unit that detects the distance traveled by the contactor, wherein the sensor unit has a sensor unit main body, a mounting plate fixed to the sensor unit main body, a linear scale connected to the end of the sensor rod opposite the contactor which passes through the sensor unit main body, and a sensor that detects the distance traveled by the linear scale, wherein the sensor unit main body is a member having lower thermal expansion than the mounting plate, the sensor moves in accordance with the amount of elongation of the mounting plate, and the mounting plate can be adjusted in its fixed position relative to the sensor unit main body within a range from the inside to the outside. [2] The outer diameter measuring instrument described in [1], characterized in that the mounting plate has a mounting hole within the range and is fixed to the sensor unit main body by a fixing member attached to the mounting hole. [3] The outer diameter measuring instrument described in [2], wherein the mounting hole includes a plurality of mounting holes, the fixing member includes a plurality of fixing members, and the mounting plate is fixed to the sensor unit body by the plurality of fixing members which are respectively attached to the plurality of mounting holes. [4] The outer diameter measuring instrument described in [3], characterized in that the mounting plate has a V-shaped notch in the center of the above range. [5] The outer diameter measuring instrument described in [4], characterized in that the depth of the cut is deeper than the position of the mounting hole. [6] The outer diameter measuring instrument described in [3], characterized in that the mounting plate comprises an arc-shaped rib J provided between the multiple mounting holes to which the multiple fixing members are respectively attached, a rib L in which the mounting holes are provided, and an X-shaped rib K connecting the rib J and the rib L. [7] An external diameter measuring instrument as described in any one of [3] to [6], characterized in that the mounting plate is fixed to the sensor unit body by two of the fixing members which are respectively attached to the two mounting holes provided on the left and right sides of the center of the range.

[0011] Another configuration of the present invention is a contact-type outer diameter measuring instrument for measuring the outer diameter of a workpiece, having one end as a tip portion having a contactor that abuts against the workpiece and the other end having a sensor rod connected to a linear scale of a sensor unit that detects the movement distance of the contactor, the sensor unit comprising: a substrate on which a sensor is mounted that detects the movement distance of the contactor by detecting the movement distance of the linear scale; a mounting plate to which the substrate is fixed via at least two substrate mounting holes in the substrate; a sensor unit main body made of a material with a lower thermal expansion than the mounting plate; and a plurality of screws that fix the mounting plate to the sensor unit main body via each of two mounting holes provided in the mounting plate.

[0012] In addition, in the above-mentioned configuration, it is desirable that the mounting holes be provided on both the left and right sides, and that two of the mounting holes be selected and the mounting plate be fixed to the sensor body by the screws, thereby making it possible to vary the spacing at which the mounting plate is constrained.

[0013] Furthermore, it is preferable that the mounting plate has symmetrical V-shaped notches in the center between the two mounting holes.

[0014] Furthermore, it is preferable to provide a guide for regulating the attitude of the object to be measured by inserting the object to be measured.

[0015] Furthermore, it is desirable that the mounting plate has an arc in the central portion that bulges toward the sensor unit at a position on the sensor unit side relative to the notch, and that the shortest distance from the left and right ends of the arc to a straight line connecting the centers of the two mounting holes is smaller than that of the central portion.

[0016] Furthermore, it is preferable that the mounting plate has a through hole between the notch and the arc in the direction of the sensor unit.

[0017] Furthermore, it is desirable that the sensor be located at the center of the board and be substantially aligned in a straight line with at least two of the board mounting holes in the left-right direction.

[0018] Furthermore, in the above, it is desirable that the mounting plate comprises a thin, arc-shaped rib J provided between the two mounting holes, a rib L in which the board mounting hole is provided, and an X-shaped rib K connecting the rib J and the rib L.

[0019] The present invention also provides a method for adjusting the temperature characteristics of a contact-type outer diameter measuring instrument that measures the outer diameter of a workpiece, the contact having one end formed as a tip having a contact that contacts a workpiece and the other end having a sensor rod connected to a linear scale of a sensor unit that detects the movement distance of the contact, the sensor unit having a substrate on which a sensor is mounted that detects the movement distance of the contact by detecting the movement distance of the linear scale, a mounting plate to which the substrate is fixed via a substrate mounting hole in the substrate, a sensor unit main body made of a material with a lower thermal expansion than the mounting plate, and a plurality of screws that fix the mounting plate to the sensor unit main body via each of two mounting holes provided in the mounting plate, the mounting holes being provided on the left and right sides in plurality, and any two of the mounting holes being selected to fix the mounting plate to the sensor unit main body with the screws, thereby varying the spacing by which the mounting plate is constrained.

[0020] Further, in a grinding device having a drive mechanism for rotating a workpiece which is a crank pin of a crankshaft of an internal combustion engine, a grinding wheel which rotates and can move back and forth in a direction perpendicular to the rotation axis, an outer diameter measuring instrument which is arranged at a position where a contactor abuts against the workpiece which is arranged in contact with the grinding wheel, and an arm which has one end side rotatably fixed to the drive mechanism of the grinding wheel, and the arm is rotatable so that the outer diameter measuring instrument can follow the position of the workpiece, the outer diameter measuring instrument has one end which is a tip portion having a contactor which abuts against the workpiece, and the other end has a sensor rod connected to a linear scale of a sensor unit which detects the movement distance of the contactor, and the sensor unit is equipped with a substrate on which a sensor is provided which detects the movement distance of the contactor by detecting the movement distance of the linear scale, a mounting plate to which the substrate is fixed via a substrate mounting hole of the substrate, a sensor unit main body which is made of a material having a lower thermal expansion than the mounting plate, and a plurality of screws which fix the mounting plate to the sensor unit main body via each of two mounting holes provided in the mounting plate. Effect of the Invention

[0021] According to the present invention, in an outer diameter measuring instrument that uses a sensor rod having a contact at the tip to detect the movement distance of the contact, the mounting plate of the substrate on which the sensor is mounted is fixed to the sensor body, which is made of a material with a lower thermal expansion than the mounting plate, through two mounting holes in the mounting plate, so that when the temperature rises, the left-right distortion of the mounting plate can be converted to the longitudinal direction. Also, the temperature characteristics of the outer diameter measuring instrument can be widely adjusted using a mounting plate with a small number of different shapes.

[0022] Therefore, inventory management becomes easy, adjustments can be made simply and simplified, and labor costs can be reduced. High accuracy and stable measurement accuracy and repeatability can be ensured regardless of the environmental conditions at the processing site, particularly the temperature conditions. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a front view of a grinding device equipped with an outer diameter measuring device according to an embodiment of the present invention; [Diagram 2] Side view of Figure 1 [Diagram 3] FIG. 2 is a partially cross-sectional plan view of the tip of an outer diameter measuring instrument according to an embodiment of the present invention; [Figure 4] FIG. 4 is an enlarged plan view of the sensor unit G in FIG. [Diagram 5] Cross-sectional view of the sensor section G in FIG. [Figure 6] FIG. 10 is a diagram for explaining the displacement of a mounting plate when heat is applied to an outer diameter measuring instrument according to an embodiment of the present invention; [Figure 7] FIG. 1 is a plan view showing a detailed shape of a mounting plate according to an embodiment of the present invention; [Figure 8] FIG. 13 is a diagram showing a simulation result when the temperature of the mounting plate according to the embodiment of the present invention is increased. [Figure 9] FIG. 11 is a plan view showing a detailed shape of a mounting plate according to another embodiment; [Figure 10] FIG. 11 is an enlarged plan view of a sensor unit G according to another embodiment. [Figure 11] FIG. 13 is a diagram showing a simulation result when the temperature of the mounting plate according to another embodiment is increased; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. 1 and 2 are schematic diagrams of an outer diameter measuring instrument 10 according to one embodiment of the present invention and a grinding device 80 equipped with the same, with Fig. 1 being a front view of the grinding device 80 and Fig. 2 being a side view of the grinding device 80. The workpiece 55 to be ground is a crank pin 55 of a crankshaft of an internal combustion engine.

[0025] 1, in a grinding device 80, a grindstone 84 that rotates (rotates counterclockwise in FIG. 1) is rotatably supported by a grindstone support member 83. The grindstone 84 is rotationally driven by a rotation drive mechanism (motor) 88, as shown in FIG. 2. The grindstone support member 83 is fixed to a grindstone base 82 that is provided so as to be movable forward and backward (B / F) in a direction perpendicular to the rotation axis of the grindstone 84.

[0026] A linear motion guide 85 is provided on the underside of the grindstone base 82 at a distance therefrom, and engages with the guide rail 81. The linear motion guide 85 slides on a rail fixed to the foundation. A linear motion mechanism 86 is provided on the grindstone base 82 to move the grindstone base 82 forward and backward.

[0027] One end of an arm 12 is attached to the upper part of the grindstone support member 83 so as to be rotatable about a rotation center 12a. The outer diameter measuring instrument 10 is attached to the other end of the arm 12 so as to be rotatable about a rotation center 12b. A crank pin 55, which is a workpiece, abuts against the grindstone 84, and the tip of the outer diameter measuring instrument 10 abuts against the crank pin 55 at a circumferential position different from the abutment portion between the crank pin 55 and the grindstone 84. The grindstone 84 and the crank pin 55 abut stably. When the crank pin 55 turns, the grindstone 84 moves forward and backward (F / B) accordingly, but the outer diameter measuring instrument 10 moves following the crank pin 55.

[0028] 2, a crankshaft drive unit that drives crankshaft 50 is disposed on the front side of the page, and a grindstone unit is disposed on the rear side. The crankshaft drive unit has rotation support units 62 that support both ends of crankshaft 50 for rotation, and crankshaft 50 is rotationally driven by a rotation drive mechanism (motor) 64 attached to one end of crankshaft 50.

[0029] The rotation of crankshaft 50 is detected by a sensor (not shown) and input as an input signal 94 to control device 100. Meanwhile, control device 100 issues a control output signal 96 for controlling motor 64. Similarly, a rotation signal 93 and a position signal 92 are input from linear motion mechanism 86 that drives grinding wheel 84 and grinding wheel base 82 to control device 100, and control device 100 outputs command signals 97 and 98, respectively. At this time, the outer diameter of crank pin 55, which is the workpiece, is input as input signal 91 from outer diameter measuring instrument 10 to control device 100.

[0030] The control device 100 drives the driving devices 64, 88, 86 based on these input signals 92-94, and judges whether the grinding device 80 has ground the crank pin 55 to a predetermined value based on an input signal 91 from the pin diameter measuring device 10. Then, when the outer diameter of the crank pin 55 falls within a predetermined allowable range, grinding is terminated.

[0031] 3 to 5 show the details of the outer diameter measuring instrument 10. FIG. 3 is a plan view showing a part of the tip S of the outer diameter measuring instrument 10 in cross section, FIG. 4 is a plan view showing an enlarged sensor section G, and FIG. 5 is a cross-sectional view of the sensor section G. As shown in FIG. 1, the outer diameter measuring instrument 10 has an elongated, roughly rectangular, box-shaped gauge body 10-1, one end of which is rotatably attached to an arm 12, and a sensor section body 10-2 fixed thereto. A V-base 19 is fixed to the tip S of the gauge body 10-1, through which a rectangular, trapezoidal, or circular cross-sectional hole is passed so that a sensor rod 20, which is an outer diameter measuring sensor, is held in the center.

[0032] A contact 21 provided at the tip S of the V-base 19 comes into contact with the workpiece 55, which is the object to be measured, and is biased to press the object to be measured. The sensor rod 20 extends from the tip S through the gauge body 10-1 to and is connected to the sensor unit G. A change in the size of the object to be measured is captured as a moving distance of the contact 21 of the sensor rod 20, and is detected by the sensor unit G provided at the other end of the gauge body 10-1.

[0033] The side of the V-base 19 that comes into contact with the workpiece 55 has a rectangular cross section cut into a V shape, and furthermore, the portion that becomes the upper side when attached to the grinding device 80 has a shape cut in the top and bottom directions to avoid interference with the grindstone 84. The sensor rod 20 that is disposed penetrating the center of the V-base 19 is connected to the linear scale 6 at sensor part G, and together with the sensor 4, constitutes a linear sensor. It has a contact 21 formed of a sphere such as a ruby ​​at its tip.

[0034] An upper mounting plate 44 and a lower mounting plate 45, each having a trapezoidal cross section, are attached to the inclined surfaces that form the V shape of the V base 19, and an upper holding member 41 and a lower holding member 42, which are arranged so as to make point contact with the workpiece 55, are fixed to each mounting plate 44, 45. Here, the upper holding member 41 and the lower holding member 42 are made of a metal round bar or round tube so as not to damage the workpiece 55 and not to deform during grinding.

[0035] In the sensor unit G, the mounting plate 1 is fixed to the sensor unit main body 10-2 with screws 5 through the mounting holes 2. A plurality of mounting holes 2 are provided on the tip S side of the mounting plate 1, three on each side in Fig. 4, and the mounting plate is fixed at any two of these locations. By selecting any two locations, the interval at which the mounting plate 1 is fixed can be changed.

[0036] A sensor 4 is provided in the center of the substrate 3, and the substrate 3 is fixed, for example, with screws through at least two substrate mounting holes 7 in the mounting plate 1. A sensor rod 20 has a contact 21 at one end for contacting the workpiece, and a linear scale 6 housed in the sensor unit G is connected to the other end. The linear scale 6 moves together with the movement of the sensor rod 20. A fine black and white pattern, for example, is drawn on the linear scale 6, and the sensor 4 emits light to and receives light from the pattern of the linear scale 6 to detect the amount of movement.

[0037] 6 is a diagram for explaining the displacement of the mounting plate 1 according to embodiment 1 when heat is applied to the outer diameter measuring instrument 10. The material of the mounting plate 1 is stainless steel, and the material of the sensor body 10-2 is a Ni-based alloy, which has a lower thermal expansion than that of the mounting plate 1. The mounting plate 1, which has a large thermal expansion coefficient, is fixed to the sensor body 10-2, which is made of a low thermal expansion material, by screws 5 at two points.

[0038] Therefore, the Poisson effect converts the elongation of the constrained portion (strain in the left-right direction B) into deformation (strain) in the unconstrained direction (longitudinal direction A) of the mounting plate 1. In other words, the amount of elongation in the unconstrained direction can be changed according to the amount of elongation of the constrained portion.

[0039] 6(a), the mounting plate 1 is fixed to the sensor unit body 10-2 at the outermost of the three mounting holes 2 provided on each side. In (b), the mounting plate 1 is fixed at the innermost. Therefore, the amount of extension in the direction of the arrow is greater in (a) than in (b).

[0040] For the same temperature rise, the position of board mounting hole 7 in (a) will move more in the longitudinal direction A in Figure 6. Boards 3 are attached to at least two board mounting holes 7, and sensor 4 is located in the center of board 3, approximately in a straight line in the left-right direction with board mounting hole 7, so the position of sensor 4 will move in the longitudinal direction A without rotating due to the moment. This reduces detection error by sensor 4, making it possible to achieve high accuracy even if there is a temperature rise.

[0041] Furthermore, since the mounting plate 1 and the substrate 3 are attached as shown in Fig. 4, the amount of elongation in the longitudinal direction A in Fig. 6 is the movement of the sensor 4 in the direction of the arrow A in Figs. 3, 4 and 5 relative to the linear scale 6. If there is a temperature rise as an environmental condition of the outer diameter measuring instrument 10, the amount of elongation and movement of the sensor rod 20 in the direction of the arrow A increases, and the diameter of the workpiece 55 is measured as being larger. In response to this, the movement of the sensor 4 in the direction of the arrow A in Figs. 3, 4 and 5 relative to the linear scale 6 compensates for the amount of elongation and movement of the sensor rod 20 (Fig. 3) due to this temperature rise.

[0042] However, this compensation amount needs to be adjusted as the temperature characteristics of the outer diameter measuring instrument 10 due to differences in the environment at the processing site and the characteristics of the outer diameter measuring instrument 10 itself. In response to this, as shown in Figures 6(a) and 6(b), the temperature characteristics of the outer diameter measuring instrument 10 can be adjusted by changing the position of the mounting hole 2 for fixing the mounting plate 1 to the sensor unit main body 10-2. Therefore, the temperature characteristics of the outer diameter measuring instrument can be adjusted widely using a single type of material and a single shape of part for the mounting plate 1, facilitating inventory management, allowing for simple and simplified adjustments and reducing labor hours, resulting in cost savings.

[0043] 7 is a plan view showing the detailed shape of the mounting plate 1. This shape is determined so as to efficiently convert the expansion in the left-right direction B due to thermal expansion into the longitudinal direction A. As already mentioned, part E, which is the fixing part, is provided with a plurality of mounting holes 2, and by changing the intervals between the fixing points, the amount of expansion in the longitudinal direction A can be changed according to the amount of expansion of the sensor rod 20, etc.

[0044] In part F, a V-shaped notch F is provided in the center of the left and right mounting holes 2. Due to this V-shaped notch F, when force is applied to the mounting plate 1 from the left-right direction B, the force is converted into elongation in the longitudinal direction A, compared to when there is no notch. Furthermore, since the mounting plate 1 is fixed to the sensor unit main body 10-2, which is a low thermal expansion material, at the mounting holes 2, a greater compressive stress is applied to the mounting plate 1 in the reverse direction, compared to when the sensor unit main body is made of a thermal expansion material equivalent to the mounting plate 1. The increased elongation in the left-right direction B is then efficiently converted into elongation in the longitudinal direction A. In other words, this has the effect of increasing the amount of compensation in the longitudinal direction A relative to temperature, and increasing sensitivity.

[0045] Additionally, each corner of the V-shaped cut F is rounded to avoid stress concentration. With a shape without the V-shaped cut F or a square cut shape, the compressive stress is offset in the center and vertical distortion (elongation) is not significant. It is desirable for the depth of the V shape to be deeper than the position of the mounting hole 2, and for the V shape to be symmetrical.

[0046] 7, the H portion is a through hole H provided approximately below the left and right mounting holes 2 (direction A, from the gauge body 10-1 toward the sensor unit G), and has the same effect as the V-shaped notch F. The I portion is located even further below (direction A) the through hole H, and the center portion of approximately the left and right mounting holes 2, the center portion in the left-right direction B, is an arc Ia that bulges downward (direction A). In other words, the through hole H is provided between the notch F and the arc Ia in the sensor unit direction.

[0047] As shown in Fig. 7, the left and right ends Ib of the arc Ia are shorter in distance from the mounting hole 2 in the longitudinal direction A than the center. Here, the distance from the mounting hole 2 in the longitudinal direction A means the shortest distance from the straight line connecting the centers of the mounting holes (the centers of the two mounting holes 2 to be screwed). Therefore, the amount of elongation due to temperature rise is smaller at the left and right ends of the arc Ia than at the center, preventing the spacing between the board mounting holes 7 from widening. This reduces the stress in the left and right direction B that is applied to the board 3 due to temperature rise. The screws 5 fix the mounting plate 1 to the sensor unit main body 10-2, and are installed so that the binding force does not change due to temperature rise.

[0048] FIG. 8 shows the results of a simulation performed by numerical analysis, which shows the direction of deformation when the temperature of the mounting plate 1 is increased. The arrows in the figure show the direction and magnitude of deformation, and it can be seen that the plate extends in the A direction.

[0049] Fig. 9 shows a mounting plate 1b according to another embodiment. Only one mounting hole 2 is provided on each of the left and right sides. Between the mounting holes 2 is a thin arc-shaped rib J, which is connected to rib L, in which two board mounting holes 7 are provided, by an X-shaped rib K. As the temperature rises, rib J tries to expand in the left-right direction B due to thermal expansion, but mounting hole 2 is fixed to sensor unit main body 10-2, which is made of a low thermal expansion material. Therefore, the rib J distorts in the longitudinal direction A near the center J-1 in Fig. 9. Because rib J is arc-shaped and thin, the amount of deformation is large.

[0050] Rib K is X-shaped, so it is easily deformed and the stretching in the downward direction in Fig. 9 is mitigated. The position of board mounting hole 7 moves upward in Fig. 9, in the longitudinal direction A, due to a rise in temperature. Therefore, the sensor is fixed to sensor body 10-2 by mounting hole 2 so that the mounting position on sensor body 10-2 is in the opposite direction to that of mounting plate 1 in embodiment 1 (upward is direction A in Fig. 9). This makes it possible to compensate for the amount of stretch and movement of sensor rod 20 (Fig. 3) due to a rise in temperature, similar to mounting plate 1 in embodiment 1.

[0051] FIG. 10 is an enlarged plan view of the sensor unit G when the mounting plate 1b according to another embodiment is used. Unlike that shown in FIG. 4, the mounting hole 2 is located on the A direction side of the sensor 4 provided at the center of the substrate 3. The substrate 3 is fixed via the substrate mounting hole 7 of the mounting plate 1b. The mounting plate 1b is fixed to the sensor unit main body 10-2 with screws 5 via the mounting holes 2 provided on the left and right. In FIG. 11, the mounting holes 2 are provided at one place on the left and right, but multiple holes may be provided on the left and right as in FIG. 4. However, since the mounting plate 1b is composed of thinner ribs J, K, and L, the amount of movement can be made larger than that of FIG. 4, and the amount of movement can be easily changed by changing the thickness of the ribs J, K, and L, especially the thickness of the X-shaped portion. Therefore, it is also possible to prepare ribs J, K, and L having different thicknesses, especially the thickness of the X-shaped portion.

[0052] FIG. 11 shows the results of a simulation based on numerical analysis, which shows the direction of deformation when the temperature of the mounting plate 1b is increased. It can be seen that the thin, arc-shaped rib J extends upward in FIG. 10, and that the position of the board mounting hole 7 moves in the direction A from the gauge body 10-1 toward the sensor part G due to the increase in temperature. [Explanation of symbols]

[0053] 1, 1b...mounting plate, 2...mounting hole, 5...screw, 3...board, 4...sensor, 6...linear scale, 7...board mounting hole, F...V-shaped notch, H...through hole, Ia...arc, Ib...left and right ends, J, K, L...rib, J-1...center, 10...outer diameter measuring instrument, 10-1...gauge body, 10-2...sensor body, S...tip, G...sensor, 12...arm, 12a, 12b...center of rotation, 19...V base, 20...sensor rod, 21...contact, 30...measuring mechanism, 41...upper holding member, 42...lower holding member, 44...upper Mounting plate, 45...lower mounting plate, 50...crankshaft, 52...rear flange, 53...journal, 54...crank web, 55...workpiece (crank pin), 61...crankshaft base, 62, 63...rotation support portion, 64...rotation drive mechanism (motor), 80...grinding device, 81...guide rail, 82...grindstone base, 83...grindstone support member, 84...grindstone, 85...linear guide, 86...linear mechanism, 88...rotation drive mechanism (motor), 91-94...input signal, 96-98...output signal, 100...control device

Claims

1. a sensor rod having a contact that contacts the workpiece and extending in a longitudinal direction; a sensor unit for detecting a moving distance of the contact, the sensor unit includes a mounting plate whose fixed position can be adjusted in a left-right direction intersecting the longitudinal direction of the sensor unit, a linear scale connected to an end of the sensor rod opposite the contact, and a sensor connected to the mounting plate so as to face the linear scale and for detecting a distance traveled by the linear scale; The outer diameter measuring instrument, characterized in that the sensor moves in the longitudinal direction in response to an amount of expansion of the mounting plate in the left-right direction due to temperature.

2. 2. The outer diameter measuring instrument according to claim 1, wherein the mounting plate is fixed to a member having a lower thermal expansion than the mounting plate at the sensor portion.

3. 3. The outer diameter measuring instrument according to claim 1, wherein the mounting plate has a mounting hole and is fixed by a fixing member attached to the mounting hole.

4. The mounting holes include a plurality of mounting holes arranged in the left-right direction, The fixing member includes a plurality of fixing members, 4. The outer diameter measuring instrument according to claim 3, wherein the mounting plate is fixed by the plurality of fixing members which are respectively attached to the plurality of mounting holes.

5. 5. The outer diameter measuring instrument according to claim 4, wherein the mounting plate has a V-shaped notch formed in a central portion in the left-right direction.

6. 6. The outer diameter measuring instrument according to claim 5, wherein the depth of the cutout is deeper than the position of the mounting hole in the longitudinal direction.

7. 5. The outer diameter measuring instrument according to claim 4, characterized in that the mounting plate comprises: an arc-shaped rib J provided between the plurality of mounting holes to which the plurality of fixing members are respectively attached; a rib L in which the mounting holes are provided; and an X-shaped rib K connecting the rib J and the rib L.

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