JP7324900B2 - Inside diameter measuring device - Google Patents

Description

The present invention relates to an inner diameter measuring device for measuring the inner diameter of a cylinder or the like and a measuring method using the same, and in particular, an inner diameter measuring device that does not require precise positioning of the inner diameter measuring device to the object to be measured during measurement, and an inner diameter measuring device that uses the same. Regarding the measurement method.

A three-dimensional measuring instrument is conventionally used to accurately measure the inner diameter of a workpiece or an object to be measured that has a circular inner peripheral surface in cross section. A three-dimensional measuring machine is one of the most accurate measuring methods if it is guaranteed that the inner surface of the workpiece is circular. However, this method requires a dedicated measurement booth, many preparation steps for measurement, and a high degree of measurement skill, resulting in a decrease in work efficiency. Therefore, it is not suitable for inspection of all mass-produced products, and for inspection and measurement of mass-produced products, a dedicated measuring device that can be attached to a processing machine or the like has been proposed.

Patent Literature 1 discloses an inner diameter measuring device for measuring the inner diameter of a work. In the inner diameter measuring device described in this publication, the head of the measuring device is composed of four variable guides, and the peripheral wall of the head is formed by each variable guide so that one measuring device can handle workpieces with different inner diameters. , and the corners of the proximal ends of the variable guides are arranged at the center of the main body of the measuring device. The extending portion of each variable guide is movably held between the fixed member and the fixed plate, each variable guide is independently movable in the radial direction, a micrometer is provided on the bracket on the back surface of the fixed plate, and the spindle is movable along the center line. Further, a tapered pin is provided at the distal end of the spindle, and the tapered surface of the tapered pin is brought into contact with the concave corner of the base end of the variable guide so that the tapered pin moves the variable guide in the radial direction.

Another example of measuring the inner diameter of an object to be measured is described in Patent Document 2. In the dimension measuring instrument described in this publication, a measuring instrument for measuring the diameter by providing a probe at one end of a set of measuring arms has a plurality of positionally variable guide members. The guide member is elastically displaceable with respect to the axis of the size measuring instrument, and is variable in open/close position when no force is applied. The dimension measuring instrument further comprises floating means for holding the displacement in the direction perpendicular to the axis. Set the opening/closing position of the guide member so that it does not come into contact with the cylindrical surface, then relatively move the axis of the dimension measuring instrument on the central axis of the cylindrical surface, and then open/close a plurality of guide members to a predetermined position to adjust the inner diameter of the object to be measured. are measuring.

Yet another example of a conventional inner diameter measuring device is described in Patent Document 3. The dimension measuring instrument described in this publication has an automatic centering mechanism so that it can be used for a wide range of inner diameters. Specifically, a plurality of sets of arms rotatably supported at a fulcrum, a probe provided at one end of the plurality of arms, and displacement detection for detecting the displacement of the other end of the arm provided with the probe. an urging means capable of simultaneously urging a plurality of sets of arms in the direction of opening and closing and releasing the urging of only the arms provided with probes; The dimension measuring instrument has measurement biasing means for biasing the arm with a predetermined pressure. A part of the guide member is used as a measuring arm.

JP 2005-106695 A JP-A-11-201704 JP-A-2000-18939

When measuring the inner diameter of a mass-produced workpiece with a dedicated measuring device, one example of measuring without compromising accuracy is to place the measuring device in advance at the measurement location and measure the inner diameter slightly larger than the outer diameter of the workpiece to be measured. A cylinder of outer diameter is fixedly arranged with respect to this measuring device. Then, the workpiece is inserted or fitted using the cylindrical object as a guide, and when the measurement position is reached, the probe is extended in the radial direction for measurement. In that case, for example, about 15 to 30 μm is allowed as the one-sided clearance between the inner diameter of the work and the guide.

When manually executing this method, the workpiece must be positioned approximately at the center of the hole of the guide before the workpiece is inserted into the guide, and this positioning takes a considerable amount of time. In addition, when an attempt is made to position a workpiece using an automatic machine, etc., highly accurate and complicated devices for positioning such as a transfer device for carrying in and out from the measuring position, a floating mechanism, and a relieving mechanism are required. It becomes necessary.

On the other hand, in the inner diameter measuring device described in Patent Document 1, although the measurement of different inner diameters is taken into consideration, it is not sufficiently considered to measure the inner diameter with high accuracy. That is, in order to guide the probe to the measurement position of the workpiece, a four-divided variable guide is radially moved by a tapered pin. However, when trying to make precise measurements down to the order of submicrons, a variable sensor is divided into four so that the contact positions of a pair of probes are positioned on a straight line that includes the center line C in a cross section perpendicular to the center line C. It becomes necessary to move the guide. The contact positions of the pair of probes are not always positioned on a straight line including the center line C due to the difference in friction between each moving variable guide and the stationary member. If the contact positions of the pair of probes are not positioned on the straight line including the center line, an error will certainly occur by the deviation of the straight line connecting the probes from the center line.

In addition, since it is possible to measure different inner diameters, the amount of radial movement of the variable guide increases when measuring large-diameter workpieces, and the center line C of the measuring instrument itself is tilted so that the cross section including the contact point of the probe is elliptical. There is also the possibility that the shape will change. If such a situation occurs, even if the contact positions of the pair of probes are positioned on a straight line that includes the center line in the cross section, the difference in the axial position, that is, the height, of the pair of probes will cause be an error.

Furthermore, in Patent Documents 2 and 3, since the inner diameter measuring device has an automatic centering mechanism, there is a high possibility that the desired positioning accuracy can be obtained, but a mechanism such as a floating mechanism or selective bias release means is required. It has become. Also, in the case of precision measurement, it is necessary to match the diameter of the guide member to the object to be measured so that there is a one-sided gap of, for example, about 15 to 30 μm, which is not much different from the inner diameter of the object to be measured. become.

SUMMARY OF THE INVENTION The present invention has been made in view of the problems of the prior art described above, and an object of the present invention is to provide an inner diameter measuring device for measuring the inner diameter of an object to be measured, in which the stylus of the inner diameter measuring device is precisely positioned before being inserted into the object to be measured. is not required, and the cost of the inner diameter measuring device is reduced while highly accurate measurement is enabled. For this purpose, in the case of a measuring device that measures manually, the workability of carrying it into and out of the measuring place is improved. Another object of the present invention is to reduce the cost of the device by simplifying the unloading mechanism and the positioning mechanism from the machine.

The features of the present invention for achieving the above objects are as follows.

[1] An inner diameter measuring device for measuring the inner diameter of a cylindrical work, comprising a guide for guiding the work, and at least three blocks radially arranged around the guide, wherein the blocks are: A measuring element having a substantially spherical contact that contacts the inner surface of the work, a moving mechanism that radially moves the measuring element from the center of the guide, and a detector arranged in contact with the moving mechanism. The guide has a shape in which a disc-shaped portion approximate to the inner diameter of the work and smaller in diameter than the inner diameter of the work and a disc-shaped portion larger in diameter than the inner diameter of the work are overlapped, and the guide is an inner diameter measuring device having a movement path for the probe.
[2] The inner diameter measuring device according to [1], wherein the large-diameter disc-shaped portion has a larger diameter than the outer diameter of the work.
[3] The inner diameter measuring device according to [1] or [2], wherein the moving passages are provided according to the number of the blocks and consist of grooves extending in the radial direction of the guide.

Another feature of the present invention is an inner diameter measuring device for measuring the inner diameter of a cylindrical work, comprising a guide for guiding the work, and at least three blocks radially arranged around the guide, Each block comprises a probe having a substantially spherical contact that contacts the inner surface of the workpiece, a moving mechanism that radially moves the probe from the center of the guide, and a detector placed in contact with the moving mechanism. Be prepared.

In this feature, the moving mechanism preferably includes a rail arranged on a straight line extending radially from the center of the guide, and a slider mounted on the rail so as to move linearly, the moving mechanism comprising: A probe base for holding the probe is fixed to the upper surface of the slider, an air cylinder having one end fixed to one vertical portion of the probe base is provided, and the detector is attached to the one vertical portion. It is desirable to attach the stylus to the other vertical portion of the stylus base by abutting the ends of the stylus.

Further, the guide includes a disc-shaped guide portion having a diameter similar to the inner diameter of the work and smaller than the inner diameter of the work, a disc-shaped guide base disposed below the guide portion, and the guide portion and the guide. A post for supporting a base is provided, grooves extending in the radial direction corresponding to the number of blocks are provided on the back side of the guide part, and through grooves corresponding to the grooves formed in the guide part are provided in the guide base, It is desirable that the other vertical portion of the probe base can be inserted through this through groove.

Another feature of the present invention for achieving the above object is an inner diameter measuring method for measuring the inner diameter of a cylindrical workpiece using an inner diameter measuring device having at least three probes each having a spherical contact, comprising: The disc-shaped guide portion of the guide of the inner diameter measuring device is operated so that the circumferential distribution of the gap formed between the outer diameter of the disc-shaped guide portion and the inner surface of the master becomes substantially constant. a preparation step of obtaining the center and storing the position of the probe in the obtained ideal state; and a measurement step of placing a work on the guide portion and bringing the contact into contact, wherein the measurement step comprises: The center of a circle formed by the contact positions or contact points of the contact is obtained from data of the contact positions or contact points of at least three of the contacts, and the center of the circle obtained in the preparation step and the center of the circle obtained in the measurement step are obtained. To obtain the true inner diameter of the workpiece from the amount of deviation of the center of the circle.

In this feature, when obtaining the true inner diameter of the work, it is preferable to obtain it from a geometrical relationship using the target value of the work to be measured and the radius of the contactor, and the four probes are used. , and they can be moved on the same straight line in groups of two, and when the two straight lines are perpendicular to each other, the inner diameter of the work is Y ₁ +Y ₂ +2×Z _Y +2 given by × _CR ,
here,
Z _Y = (T _R -C _R )-SQRT((T _R -C _R ) ² -X _L ² ),
X _L =(X ₁ -X ₂ )/2,
X ₁ and X ₂ are position data of one set of probes forming a pair, Y ₁ and Y ₂ are position data of the other pair of probes forming a pair, _TR is the target value of the object to be measured, and _CR is contact. may be child radii.

According to the present invention, in a measuring device for measuring the inner diameter of a work, the outer diameter of the guide section that serves as a guide for inserting the measuring section into the work is formed sufficiently smaller than the inner diameter of the work so that a sufficient gap is formed. Therefore, when inserting the stylus into the work, it can be easily and quickly inserted either manually or by an automatic machine. In addition, since the probes are made of small-diameter, high-precision steel balls, when the pair of probes contact the inner surface of the workpiece during measurement, even if they do not lie on a straight line that includes the center of the circular cross section, correction can be easily made. The time required for measurement can also be reduced.

Therefore, the inner diameter measuring device does not require precise positioning before inserting the probe of the inner diameter measuring device into the object to be measured, thereby reducing the cost of the inner diameter measuring device and enabling highly accurate measurement. In addition, in the case of a measuring device that measures manually, the workability of carrying it into and out of the measuring place is improved. This simplifies the transport mechanism from and the positioning mechanism, reducing the cost of the device.

1 is a plan view of one embodiment of an inner diameter measuring device according to the present invention; FIG. FIG. 2 is a partially cross-sectional front view of the inner diameter measuring device shown in FIG. 1 ; FIG. 2 is an exploded perspective view of the main part of the inner diameter measuring device shown in FIG. 1; It is a figure explaining the measuring method using the inside diameter measuring device concerning the present invention. It is a figure explaining the measuring method using the inside diameter measuring device concerning the present invention.

An embodiment of an inner diameter measuring device according to the present invention will be described below with reference to the drawings. 1 to 3 are diagrams of an embodiment of an inner diameter measuring device 100. FIG. 1 is a plan view of the inner diameter measuring device 100, and FIG. 2 is a cross section of a part of the inner diameter measuring device 100 shown in FIG. FIG. 3 is a front view, and FIG. 3 is an exploded perspective view of main parts of the inner diameter measuring device 100 shown in FIG.

The inner diameter measuring apparatus 100 includes a guide 150 arranged at the center of a workpiece 170 to be measured (object to be measured), and four blocks 300 having the same configuration arranged around the workpiece 170 at 90° intervals. The blocks 300 are radially arranged around the guide 150 . The guide 150 is for guiding the measurement apparatus 100 to the vicinity of the inner surface 172 of the work, and is a disc-shaped guide portion whose outer diameter is formed with a gap c on one side with respect to the inner surface 172 of the work. 158, a guide base 156 configured to support the guide portion 158 from the back side and place the workpiece 170 thereon, and a columnar support erected on the back side of the guide base 156 to support the guide base 156. 152.

A protrusion 191 is formed in the central portion of the back side of the guide portion 158, and is fitted into a through hole 155 (see also FIG. 3) formed in the central portion of the guide base 156. Portion 158 is positioned. Grooves extending in the radial direction at 90° pitches are formed on the rear side of the guide portion 158, and constitute passages for moving the contacts 182, the details of which will be described later. Note that the upper surface of the guide portion 158 is a flat surface. The outer diameter of the guide portion 158 is larger than the diameter of the work inner surface 172 so that a sufficient gap c is formed so that it does not take time to manually or automatically carry the work 170 into or out of the measuring portion. It has a small diameter of about 1 mm.

A guide base 156 on which the work 170 is placed has a disc shape and an outer diameter larger than that of the work 170 . A through hole 155 is formed in the central portion of the guide base 156, and a projection 191 of a guide portion 158 is fitted on the upper surface side, and a projection 154 of a post 152, which will be described later, is fitted on the lower surface side. A radially extending groove 157 having a rectangular cross-section is formed at four locations in the radially intermediate position of the guide base 156 at a pitch of 90° in the circumferential direction. The post 152 has a columnar shape extending vertically, and projections 154 and 153 are formed at the upper and lower ends thereof at the axial center. The upper protrusion 154 is used for positioning with the guide base 156, and the lower protrusion 153 is used for positioning with the base 110 such as a surface plate.

Next, four blocks 300 arranged at a pitch of 90° around the workpiece 170 will be described. Since these four blocks 300 have the same configuration, only one will be described. A split base 120 is placed on a base 110 such as a surface plate with a gap corresponding to the radius of the support 152 . The divided base 120 (120a to 120d) has a rectangular shape with one corner cut off when viewed from the top, and a cross-shaped base with an open center is formed by directing the side with the cut corner toward the support 152 side. .

Rails 130 (130a to 130d) extending in a straight line (radially) in the radial direction of the strut 152 are fixed to the upper surfaces of the split bases 120a to 120d by fixing means (not shown). Each rail 130a-130d is position-adjusted for each split base 120 using a split base adjuster 122 so that the rails 130a-130d located on adjacent split bases 120 have an exact 90° pitch. The rail 130 is prepared for accurately moving a slider 140, which will be described later, in the radial direction.

It should be noted that the rails 130 may be made up of a pair of rails that extend beyond the center of the stanchion 152 and intersect at an angle of exactly 90°. In this case, the time required for positioning the rail can be reduced. However, a means for solving the interference between the support 152 and the rails 130 and the interference between the rails 130 is required.

A slider 140 serving as a rail guide is mounted on the upper surface of the rail 130 . The slider 140 has a Π-shaped cross section, and is formed so as to be movable on the rail 130 in the radial direction with little frictional resistance and without shaking or vibration. A mounting portion 236 formed at one end of the tension spring 230 is mounted on one radially outer side surface of the slider 140 . The attachment position of the tension spring 230 is one or more for each slider 140 .

The upper surface of the slider 140 is a flat surface, and a base 160 for a measuring element 180 having a substantially inverted Π shape in front view is placed on the upper surface. The base 160 is composed of first and second vertical portions 162, 164 and a bottom portion 166 connecting the two vertical portions 162, 164. A part of the lower end of the second vertical portion 164 It extends downward from the lower surface of 166 and is used as positioning part 167 when placed on slider 140 .

The second vertical portion 164 of the base 160 passes vertically through a groove 157 formed in the guide base 156 of the guide 150 when the measurement apparatus 100 is assembled, and is formed on the rear side of the guide portion 158. Extends into radial groove 159 . Further, a mounting hole 165 for mounting a stylus 180 is formed in the vicinity of the upper end of the second vertical portion 164 and on the surfaces where the first and second vertical portions 162 and 164 face each other.

On the outer surface side of the first vertical portion 162 of the base 160 for the probe 180, that is, on the radially outer side of the support 152, a contact portion 214 with which the detection head 218 of the detector 210 contacts is formed. A contact portion 222 with which the tip of the air cylinder 220 contacts is formed on the side. By making the width of the base 160 for the probe 180 smaller than the width of the slider 140, the width of the groove 157 of the guide base 156 and the groove 159 of the guide portion 158 are narrowed, and the second vertical portion 164 is located at the workpiece. This prevents interference with the work 170 and damage to the work 170 .

The detector 210 is held by a detector bracket 250 in order to bring the detection head 218 of the detector 210 into contact with the base 160 for the stylus 180 . The detector bracket 250 has an S-shaped cross section, and a bottom portion 254 (see FIG. 3) is fixed to the split base 120 with a bolt or the like (not shown). A holding hole 212, which is a through hole, is formed in an upper portion 252 of the detector bracket 250. After the detector 210 is inserted into this holding hole 212 so that the detection head 218 faces radially inward, a screw (not shown) is inserted. The detector 210 is fixed in the holding hole 212 with a fixture such as. A through-hole 226 through which the air cylinder 220 is inserted is formed in the vertical portion 256 of the detector bracket 250 and substantially directly below the holding hole 212, and a through-hole 234 through which the tension spring 230 is inserted. is formed. Although one through-hole 234 for the tension spring 230 is shown in this embodiment, there may be two or more for each detector 210 . In that case, the widthwise position of the through hole 234 does not necessarily have to be formed directly below the holding hole 212 .

In order to hold the tension spring 230 and the air cylinder 220, the air cylinder bracket 240 is positioned and fixed to the end face of the split base 120 using the positioning portion 246 thereof using fasteners such as bolts (not shown). The air cylinder bracket 240 has a bottom portion 242 and a vertical portion 244. A holding hole 224, which is a through hole, is formed in the vicinity of the upper end of the vertical portion 244. After the air cylinder 220 is inserted, a nut or the like is fixed. It is used to fix the air cylinder 220 with a tool. A mounting portion 232 for a tension spring 230 is provided below the holding hole 224 in the vertical portion 244 . The mounting portion 232 is formed so as to be aligned with the through hole 234 formed in the detector bracket 250 and the mounting portion 236 formed in the slider 140 . Similarly, the holding hole 224 for the air cylinder, the through hole 226 formed in the bracket 250 for the detector, and the abutting portion formed in the base 160 for the stylus are also configured to be positioned on a straight line.

In assembling the measuring apparatus 100 of this embodiment configured as described above, four divided bases 120 are placed on a base 110 such as a surface plate, and a rail 130 is fixedly arranged on each divided base 120 . In this state, the positions of the split bases 120 are finely adjusted using the split base adjusters 122 so that the rails are at a pitch of 90 degrees to each other. The split base adjuster 122 is also used as a positioning adjustment mechanism for measuring the maximum diameter of the workpiece 170 .

Next, the slider 140 is placed on each rail 130 , and the probe base 160 is placed on the central portion of the slider 140 in the width direction, and then positioned. The mounting portion 184 of the probe 180 is fixedly held on the second vertical portion 164 of the probe base 160 . At the same time, the detector bracket 250 is positioned on the upper surface of the split base 120, and the air cylinder bracket 240 is positioned and attached to the side surface. Further, the tension spring 230 is attached between the slider 140 and the air cylinder bracket 240 , the detector 210 is attached to the detector bracket 250 , and the air cylinder 220 is attached to the air cylinder bracket 240 . Then, the contact portion 222 of the air cylinder 220 is fixed to the probe base 160 .

The air cylinder 220 is for bringing the contactor 182 of the probe 180 into contact with the inner surface 172 of the workpiece or keeping it away from the inner surface 172 of the workpiece. When covering, it is pulled in from the guide portion 158 so as not to protrude radially outward, and when measuring, it is pushed out radially outward from the guide portion 158 . Also, the tension spring 230 is for securing contact pressure to the contactor 182 of the probe 180 during measurement. The detector 210 may be any object as long as it can measure a length, and a linear encoder, which is an optical or magnetic length measuring device, or the pencil type length measuring device described in this embodiment can be used.

On the other hand, the guide 150 is positioned by fitting the protrusion 153 of the post 152 of the guide 150 into the positioning hole 114 formed in the central space of the base 110 in which the four divided bases 120 are arranged. Next, the protrusion 154 on the upper end of the support 152 is fitted into the through hole 155 formed in the center of the guide base 156 . At this time, the rectangular groove 157 formed in the guide base 156 and the second vertical portion 164 are aligned in the circumferential direction so as not to interfere with the probe base 160 placed on the slider 140 . Furthermore, a protrusion 191 formed at the center of the rear surface of the guide portion 158 is fitted into the through hole 155 formed at the center of the guide base 156 . At this time, as in the case of the guide base 156, a radial groove 159 and a second vertical portion 164 are formed on the back surface of the guide portion 158 so that the guide portion 158 does not interfere with the probe base 160 placed on the slider 140. align the circumferential positions of the

When the workpiece 170 is introduced into the inner diameter measuring apparatus 100 assembled in this manner, the rail 130 and the slider 140 are used to prevent the contactor 182 at the tip of the probe 180 from coming into contact with the inner surface 172 of the workpiece. The child 180 is pulled radially inward. Since the outer diameter of the guide portion 158 is set to be smaller than the known nominal diameter of the work 170 by c in the gap on one side, the work 170 can be easily fitted to the outside of the guide portion 158 either manually or by using an automatic machine. be able to.

Next, a specific measuring method using the inner diameter measuring apparatus 100 configured as described above will be described with reference to FIGS. 4 and 5. FIG. FIG. 4 is an example of a measurement method when detectors are arranged at four locations in the circumferential direction at a pitch of 90°, and FIG. 5 is a measurement method when detectors are arranged at six locations in the circumferential direction at a pitch of 60°. is an example of In the case of FIG. 5, unlike the above-described embodiment, six sets including the split base 120 are required, but the basic configuration is the same. That is, the inner diameter measuring apparatus 100 includes six blocks having the same configuration and the guide 150 in which the number of grooves 157 and 159 provided in the guide base 156 and the guide portion 158 is changed from four at a pitch of 90° to six at a pitch of 60°. prepare.

FIG. 4 is a diagram showing the positional relationship between a small-diameter, substantially spherical contactor 182 disposed at the tip of a probe 180 used to indirectly measure the inner diameter of the workpiece 170 and the workpiece 170. FIG. 4(a) schematically shows an ideal state in which the center of the inner surface 172 of the workpiece 170 coincides with the intersection of two sets of straight lines obtained by connecting the centers of two spherical contactors 182 arranged opposite to each other. , FIG. 4B schematically shows a state in actual measurement in which the center of the inner surface 172 of the work 170 is different from the intersection of two sets of straight lines obtained by connecting the centers of the two spherical contactors 182 arranged opposite to each other. FIG. 4 is a diagram showing; In these figures, the amount of deviation and the like are exaggerated for easy understanding. This also applies to FIG.

An object of the present invention is to rapidly measure the inner diameter of mass-produced products. Therefore, the gap c between the inner surface 172 of the work 170 and the outer diameter of the guide portion 158 of the guide 150 is set to such an extent that the work 170 can be placed over the guide portion 158 without hindrance. When actually measuring the inner diameter of the workpiece 170, the following is performed as a preliminary preparation.

First, the target value _TR such as the inner diameter of the workpiece 170 and the radius _CR of the contactor 182 described in the design drawing are input to the control unit (not shown) of the measuring device 100 . Here, the target value _TR is a processing target value of the workpiece 170, and the contactor 182 is manufactured using a steel ball or the like of a high-precision rolling bearing. Therefore, in the embodiment of FIG. 4, the radii C _R of each contact 182 are considered the same because there is only submicron or less error between the radii C _R of the four contacts 182 .

Next, a work 170 with a high degree of circularity, that is, a work 170 with little distortion that was used in past measurements is prepared as a master 170M, and the position of each slider 140 is adjusted so as to obtain the state shown in FIG. 4(a). This position is also called an ideal position, and is a coordinate system fixed to the measuring apparatus 100 . In the case of a new measurement, etc., a master 170M having a high roundness and substantially the same diameter may be separately prepared.

In the state shown in FIG. 4A, two straight lines 261 and 262 connecting the centers of a pair of opposing contacts 182 are orthogonal to each other, and the orthogonal point O coincides with the center of the master 170M. The position of each contact 182 is stored. In actual measurement, position detection by contact of each contactor 182 with the work 170 or master 170M is detected by converting the amount of movement of the detection head 218 of the detector 210 into a one-to-one ratio. Therefore, the output of each detector 210 in the state of FIG. 4A is stored as a reference position by a control unit (not shown).

Next, the object to be measured is changed from the master 170M to the work 170. FIG. At this time, the work 170 is not positioned so as to be particularly in the state shown in FIG. Therefore, a non-uniform gap is generally formed in the circumferential direction between the work inner surface 172 and the outer diameter of the guide portion 158 of the guide 150, and the range of the gap varies from about 0 to 2c.

During measurement, as shown in FIG. 4(b), the contactor 182, which is the head of the probe 180, is moved so as to come into contact with the work inner surface 172 _. are positioned on the circumference 182 _a to 182 _d centered on , but they are not arranged at equal pitches on this circumference. Moreover, the circumferential pitch between the contacts 182 is within the ideal 90° pitch positions 182 _a0 to 182 _d0 even on a coordinate system centered on the origin O fixed to the measuring apparatus 100 shown in FIG. 4(a). does not necessarily have to be Therefore, even if the output of the detector 210 corresponding to the position of the contactor 182 is used as it is, the inside diameter of the workpiece 170 cannot be obtained. In order to obtain an accurate inner diameter of the workpiece 170 from the contact position data of the contactor 182, the contactor 182 is arranged at equal pitch positions _182a0 to _182d0 on the circumference of the center _O1 , or the detected value is calculated by some method. Convert with In the former case, position detection takes time, so the latter is selected in the present invention.

On the coordinate system fixed to the measuring apparatus 100, the position of each contact 182 is determined by each detector 210, with the amount of movement in the radial direction of each contact 182 being − and the amount of movement in the radial direction being +. Upon detection, the pair of opposing contacts 182, 182 in the X direction move from virtual equal-pitch points _182a0 , _182b0 on the coordinate system of the actual workpiece 170 with center _O1 to the real position _182a , _182b . Along with this, a line 263 connecting the centers of the pair of contactors 182, 182 facing each other in the X direction is also a straight line 261. FIG. Similarly, a pair of opposing contacts 182, 182 in the Y direction are shifted from virtual equal-pitch points _182c0 , _182d0 on the coordinate system of the actual workpiece 170 having the center _O1 to real positions _182c , _182d . Along with this, a straight line 264 connecting the centers of the pair of contactors 182 , 182 facing each other is also a straight line 262 .

The displacement amount of the straight line 263 to the straight line 261 is the Y-direction displacement amount Y _L of the workpiece 170 from the ideal position, and the displacement amount of the straight line 264 to the straight line 262 is the X-direction displacement amount X of the workpiece 170 from the ideal position. is _L. The displacement amount _XL in the X direction is the ideal position of each of the two contactors 182, 182 facing each other in the Y direction. It is the average value of the difference between the values X ₁ and X ₂ . Similarly, the deviation amount Y _L in the Y direction is based on the ideal position of each of the two contactors 182, 182 facing each other in the X direction, that is, the position detection value of the circumferential equal gap measured by the master 170M. is the average value of the difference between the position detection amounts Y ₁ and Y ₂ . From these relationships
X _L =(X ₁ -X ₂ )/2,
Y _L =(Y ₁ -Y ₂ )/2,
, and the distances X _max and Y _max between the centers of the two pairs of opposing contacts 182 are based on the geometrical relationship shown in _FIG . is expressed by the following equation. Here, in order to clarify the drawing, FIG. 4(c) shows only the portion related to the geometrical position in the Y direction, but the same applies to the geometrical positional relationship in the X direction. The function SQRT( ) is a square root function.
X _max =X ₁ +X ₂ +2×Z _X ,
here,
Z _X = (T _R -C _R )-SQRT((T _R -C _R ) ² -Y _L ² )
Y _max =Y ₁ +Y ₂ +2×Z _Y ,
again,
Z _Y = (T _R -C _R )-SQRT((T _R -C _R ) ² -X _L ² );
If the workpiece 170 is a perfect circle, the inner diameter of the workpiece 170 is Y _max +2× _CR =X _max +2× _CR .

As described above, the guide portion 158 of the guide 150 is placed over the guide portion 158 so that the guide portion 158 of the guide 150 can be freely inserted into the inner surface 172 of the work within the range of the gap. The inner diameter of the workpiece 170 can be measured simply, easily and accurately simply by extending it in the radial direction through the workpiece 140 and bringing it into contact with the inner surface of the workpiece. Therefore, the accurate centering of the workpiece 170 with respect to the guide portion 158, which has been conventionally required, becomes unnecessary, and the work process for measurement is greatly reduced. In particular, in the conventional method of accurately centering the workpiece with respect to the guide, the outer diameter of the guide is made very slightly smaller than the inner diameter of the workpiece, for example, by about 15 to 30 μm (clearance on one side). In a small gap, it takes time to cover the work with the guide. On the other hand, in the present invention, the gap can be increased to about 1 mm (clearance on both sides), so that the guide portion 158 can be easily and quickly covered with the workpiece 170 either manually or by an automatic machine. Although the contact point of the contactor 182 with the work inner surface 172 changes as the contactor 182 moves on the work inner surface 172, the above relationship is always maintained because the contactor 182 has a spherical outer shape.

In the above embodiment, four probes 180 are arranged at a pitch of 90°, and the output of the detector 210 for all probes 180 is used. Is possible. This example will be described with reference to FIG. 4(d). It shows the result of bringing two contactors 182 facing each other in the Y direction and one contactor 182 in the X direction, which is one of the contactors in the X direction, into contact with the inner surface 172 of the workpiece.

Specifically, the center _O1 of a circle passing through the centers of the contactors 182 is obtained from the three contactor positions _182b , _182c , and _182d , and the center position _O1 and the inner diameter measuring device 100 are fixed. Then, the X-direction deviation amount _XL between the center position (ideal position) O of the coordinate system obtained by the calculation is obtained. From the geometrical relationship shown in FIG. 4(d),
X _L =SQRT((T _R −C _R ) ² −((Y ₁ −Y ₂ )/2) ² )−X ₂
Similar to the above example,
Z _Y = (T _R −C _R )−SQRT((T _R −C _R ) ² −X _L ² ), so
Y _max =Y ₁ +Y ₂ +2× _ZY
is obtained. Therefore, the inner diameter of the workpiece 170 is Y _max +2× _CR .

Next, an example in which the number of probes 180 arranged is increased will be described with reference to FIG. Adding the probe 180 increases the size of the measuring device, so it is not suitable for measuring small inner diameters, but it is used when the inner diameter of the work 170 is large and you want to check the roundness. Is possible. FIG. 5 shows a case where 3 to 6 probes 180 are used. A specific configuration of the measurement block 300 is the same as that shown in FIGS.

FIG. 5(a) is a diagram corresponding to the description of FIG. 4(a), in which the inner surface of the workpiece 172 or the inner surface of the master 170M is arranged to face the guide portion 158 of the inner diameter measuring device 100 with a constant circumferential gap c. It also shows the ideal position. A pair of contacts 182 of the measuring device 100 are arranged in the Y-axis direction as in the embodiment of FIG. Two pairs of contacts 182 are arranged as shown. That is, one pair of contacts 182 is arranged in the A-axis direction forming an angle of 120° with the Y-axis, and the other pair of contacts 182 is arranged in the B-axis direction forming an angle of 60° with the Y-axis. .

FIG. 5(b) is a diagram showing the positional relationship of each contactor 182 in actual measurement, similar to FIG. 4(b). As in the case of the four-direction measurement shown in FIG. 4B, the target radius _TR of the workpiece 170 and the radius _CR of the contactor 182 are stored in control means (not shown). Since the six contactors 182 use steel balls or the like of precision rolling bearings, their radii _CR are substantially the same. Based on the change in the position of each contactor 182 from the ideal position, which is the coordinate system fixed to the inner diameter measuring apparatus 100, the deviation amount _XL between the center O of the ideal position and the center position where the actual workpiece 170 is placed is obtained. , the inner diameter in the Y direction is obtained based on this deviation amount _XL .

Specifically, from the measured values X _A1 and X A2 in the A direction and the measured values X _B1 and X _B2 in the B direction _of the detector 210 corresponding to the amount of movement of the contactor 182, the distance between the two centers O and _O1 The shift amounts X _AL and X _BL in the A direction and the B direction are obtained as follows.
X _{A L} =(X _A1 -X _A2 )/2
_XBL =( _XB1 - _XB2 )/2
FIG. 5(c) shows an enlarged part of FIG. 5(b). From the positional relationship shown in FIG. 5(c), using a trigonometric function, the X-direction shift amount _XA due to _XAL and the X-direction shift amount _XB due to _XBL are:
X _A = X _{A L} /cos30°,
X _B =X _BL /cos30°
Since the deviation amount _XL in the X direction is the average value of these,
X _L =(X _A +X _B )/2
is obtained. Using the outputs Y _{1 and} Y ₂ of the detector 210 for the Y-direction contacts 182 arranged in the same manner as in the embodiment shown in FIG. From the geometrical relationship shown, it is obtained by the following formula. Here, FIG. 5(d) is a diagram corresponding to FIG. 4(c).
Z _Y =T _R -SQRT((T _R -C _R ) ² -X _L ² ),
Y _max =Y ₁ +Y ₂ +2× _ZY
Therefore, the inner diameter of the workpiece 170 is obtained by Y _max +2× _CR .

Also in this embodiment, when the workpiece 170 is placed on the guide portion 158 of the guide 150, a larger gap than in the conventional art can be provided, and precise centering work between the guide portion 158 and the workpiece 170 is not required. , the time required for measurement setup can be greatly reduced. In addition, since the measurement can be performed easily and quickly either manually or by using an automatic machine, the throughput of the measurement is improved.

In this embodiment, the case of using 3 to 6 probes has been described, but measurement can be similarly performed using 4 to 8 or more probes. Furthermore, even if the stylus is not arranged at an equal pitch, if the ideal state, i.e., the measurement in the coordinate system fixed to this measuring device is performed and recorded by the master, and then the workpiece is measured based on the recording by the master, The inner diameter of the work can be measured quickly and easily by the above method. Therefore, the time required for transporting the workpiece to and from the measuring location and the time required for centering the workpiece can be reduced, thereby improving the working efficiency of the measuring work.

DESCRIPTION OF SYMBOLS 100... Inside diameter measuring apparatus 110... Base (surface plate) 112... Hole 114... Positioning hole 120, 120a-120d... Split base 122... Split base adjuster 130, 130a-130d... Rail, 140... Slider , 150... Guide, 152... Post, 153, 154... Protrusion, 155... Through hole, 156... Guide base, 157... (Radial direction) groove, 158... Guide part, 159... (Radial direction) groove, 160... Base ( 162 (first) vertical portion 164 (second) vertical portion 165 mounting hole 166 bottom 167 positioning portion 170 work (object to be measured) 170M Master 172 Work inner surface 180 Probe 182 Contact 182 _a to 182 _d Contact position 182 _a0 to 182 _d0 Virtual contact position 183 _a to 183 _f Contact position 183 _c0 Virtual contact position 184 Mounting portion 191 Protrusion 210 Detector 212 Holding hole 214 Contact portion 218 Detection head 220 Air cylinder 222 Contact portion 224 Holding Hole 226...Through hole 230...Tension spring 232...Mounting part 234...Through hole 236...Mounting part 240...Bracket (for air cylinder) 242...Bottom part 244...Vertical part 246...Positioning part 250...Bracket (for detector), 252...Top, 254...Bottom, 256...Vertical part, 300...Block, A, B...Direction, c...Gap, _CR ...Contact radius, O...Center, _O1 ...Virtual Center, _TR ... (target value) radius, X... direction, _X1 , _X2 ... measured value, XA, _XB , _XAL , _XBL , _XL ... _positional deviation amount, _Xmax ... reference inner diameter, Y … direction, Y ₁ , Y ₂ … measured value, Y _max … reference inner diameter, _YL … misalignment amount, Y _Y … length in Y direction, ΔY … misalignment amount

Claims (6)

In an inner diameter measuring device for measuring the inner diameter of a cylindrical work having an inner peripheral surface with a circular cross section,
a guide for guiding the workpiece;
at least three blocks radially arranged around the guide;
The block is
a probe having a substantially spherical contact that contacts the inner surface of the workpiece;
a movement mechanism for radially moving the probe from the center of the guide;
a detector disposed in contact with the moving mechanism; a control unit;
with
Said guide
a disk-shaped portion that approximates the inner diameter of the workpiece and has a smaller diameter than the inner diameter of the workpiece;
A disk-shaped portion having a diameter larger than the inner diameter of the work is superimposed on each other,
Said guide
Having a moving passage for the probe,
The inner diameter measuring device, wherein the controller compares the output obtained by the detector with a pre-stored ideal position, and obtains the inner diameter from the amount of deviation. 2. The inner diameter measuring device according to claim 1, wherein said controller calculates said deviation amount based on a difference between said output and said ideal position. 2. The control unit according to claim 1, wherein the control unit obtains the center position of a circle through which the center of the contactor passes from the output, and obtains the deviation amount from the geometric relationship between the center position and the ideal position. Inner diameter measuring device. The ideal position is obtained by the detector when a master having a predetermined roundness and having the same shape as the work instead of the work is placed on the guide in alignment with the center of the guide and measured. 2. The inner diameter measuring device of claim 1, determined based on the output obtained. 2. The inner diameter measuring device according to claim 1, wherein the large-diameter disc-shaped portion has a diameter larger than the outer diameter of the workpiece. 6. The inner diameter measuring device according to claim 1 , wherein said moving passages are provided according to the number of said blocks and consist of grooves extending in the radial direction of said guide.