JP2019174263A - Inner diameter measuring apparatus and method for measurement using the same - Google Patents

Abstract

To provide an inner diameter measuring apparatus for measuring the inner diameter of a measurement target object, the apparatus removing the necessity of a precise positioning before the gauge head of the inner diameter measuring apparatus is inserted into a measurement target object and allowing an accurate measurement while reducing the cost of the inner diameter measuring apparatus.SOLUTION: The inner diameter measuring apparatus for measuring the inner diameter of a cylindrical workpiece 170 includes: a guide 150 for guiding the workpiece; and at least three blocks 300 arranged radially around the guide. Each block includes: a gauge head 180 having a perfectly spherical contact 182 in contact with the inner surface of the workpiece; moving mechanisms 130, 140, 160, 220, and 230 for moving the gauge head from the center of the guide radially; and a detector 210 in contact with the moving mechanisms.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an inner diameter measuring apparatus for measuring an inner diameter of a cylinder or the like and a measuring method using the inner diameter measuring apparatus, and more particularly, to use an inner diameter measuring apparatus that does not require precise positioning of the inner diameter measuring apparatus on a measurement object during measurement. It relates to a measurement method.

  Conventionally, a three-dimensional measuring instrument has been used to accurately measure the inner diameter of a workpiece or an object to be measured having a circular inner peripheral surface. If it is guaranteed that the inner surface shape of the workpiece is circular, the three-dimensional measuring instrument is one of the most accurate measurement methods. However, it requires a dedicated measurement booth, requires many preparation steps for measurement, and further requires measurement skill, resulting in a reduction in work efficiency. For this reason, it is unsuitable for inspection of all mass-produced products, and a dedicated measuring device that can be attached to a processing machine or the like has been proposed for inspection of mass-produced products.

  Patent Document 1 discloses an inner diameter measuring device that measures the inner diameter of a workpiece. In the inner diameter measuring instrument described in this publication, the head of the measuring instrument is composed of four variable guides so that even a workpiece having a different inner diameter can be handled by one measuring instrument, and the peripheral wall of the head is each variable guide. Are formed in a cylindrical shape, and the corners of the respective variable guide base ends are arranged at the center of the measuring instrument main body. And the extension part 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 freely movable along the center line. Further, a taper pin is provided at the tip of the spindle, and the variable guide is moved in the radial direction by the taper pin with the taper surface of the taper pin being brought into contact with the concave corner of the variable guide base end.

  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 that measures a diameter by providing a measuring element at one end of a pair of measuring arms includes a plurality of guide members whose positions are variable. The guide member is elastically displaceable with respect to the axis of the dimension measuring instrument, and the open / close position when no force is applied is variable. The dimension measuring device further includes floating means for holding the displacement in a direction perpendicular to the axis. Set the open / close position of the guide member so that it does not contact the cylindrical surface, then move the axis of the dimension measuring device relative to the central axis of the cylindrical surface, and then open and close the multiple guide members to the predetermined position to reduce the inner diameter of the object to be measured. Measuring.

  Still another example of a conventional inner diameter measuring apparatus is described in Patent Document 3. The dimension measuring instrument described in this publication has an automatic centering mechanism that can accommodate a wide range of inner diameters. Specifically, a plurality of sets of arms rotatably supported by a fulcrum, a measuring element provided at one end of the plurality of sets of arms, and a displacement detection that detects the displacement of the other end of the arm provided with the measuring element And a biasing means capable of simultaneously biasing a plurality of sets of arms in the opening / closing direction and releasing the biasing of only the arm provided with the gauge, and a gauge for which the bias is released. The dimension measuring device includes measurement biasing means for biasing the arm with a predetermined pressure. A part of the guide member is used as a measurement arm.

JP 2005-106695 A Japanese Patent Laid-Open No. 11-201704 JP 2000-18939 A

  When measuring the inner diameter of workpieces that are mass-produced with a dedicated measuring device, in an example of measuring without losing accuracy, a measuring device is placed in advance at the measurement location and it is slightly larger than the outer diameter of the workpiece to be measured A cylindrical object having an outer diameter is fixedly arranged with respect to the measuring device. Then, the workpiece is inserted or fitted using the cylindrical object as a guide, and when the measurement position is reached, the measuring element is extended in the radial direction and measured. In that case, for example, about 15 to 30 μm is allowed as the one-side gap between the workpiece inner diameter and the guide.

  When this method is executed manually, the work must be positioned approximately at the center of the hole of the guide before the work is inserted into the guide, and a considerable amount of time is spent on the positioning. In addition, when trying to position a workpiece using an automatic machine or the like, a highly accurate and complicated device for positioning such as a transfer device for carrying in and out of the measurement position, a floating mechanism, and a relieving mechanism is used. It becomes necessary.

  On the other hand, in the inner diameter measuring device described in the above-mentioned Patent Document 1, although measures for measuring different inner diameters are taken into consideration, it is not sufficiently considered to measure the inner diameter with high accuracy. That is, in order to guide the measuring element to the workpiece measurement position, the variable guide having a four-divided shape is moved in the radial direction by the taper pin. However, when precise measurement down to about a submicron is attempted, the variable is divided into four so that the contact position of a pair of probe is positioned on a straight line including the center line C in a cross section perpendicular to the center line C. It becomes necessary to move the guide. Due to the difference in friction between the moving variable guides and the stationary member, the contact positions of the pair of measuring elements are not always positioned on the straight line including the center line C. If the contact position of the pair of measuring elements is not positioned on the straight line including the center line, an error is surely generated by the amount of deviation of the straight line connecting the measuring elements from the center line.

  Further, since different inner diameters can be measured, the amount of radial movement of the variable guide increases when measuring a large-diameter workpiece, and the cross section including the point where the center line C of the measuring instrument tilts and the probe contacts is elliptical. There is also a risk of changing to a shape. When such a situation occurs, even if the contact positions of the pair of probe elements are positioned on a straight line including the center line in the cross section, the axial positions, that is, the heights of the pair of probe elements are different, so that is the same amount. It becomes an error.

  Further, in Patent Documents 2 and 3, since the inner diameter measuring device has an automatic centering mechanism, there is a high possibility that desired positioning accuracy can be obtained, but a mechanism such as a floating mechanism and a selective bias release means is necessary. It has become. For precise measurement, it is necessary to match the diameter of the guide member with the object to be measured so that it does not differ much from the inner diameter of the object to be measured, for example, a gap on one side of about 15 to 30 μm. become.

  The present invention has been made in view of the above-mentioned problems of the prior art, and its purpose is to accurately position an internal diameter measuring device for measuring the internal diameter of an object to be measured before inserting the probe of the internal diameter measuring device into the object to be measured. Is to enable high-accuracy measurement while reducing the cost of the inner diameter measuring device. For this purpose, in the case of a measuring device for manual measurement, the workability of carrying in and out of the measuring place is improved, and in the case of measuring with an automatic machine, the automatic carrying-in mechanism and automatic mechanism are used. Another object is to reduce the cost of the apparatus by simplifying the unloading mechanism and positioning mechanism from the machine.

  A feature of the present invention that achieves the above object is that, in an inner diameter measuring device for measuring the inner diameter of a cylindrical workpiece, a guide for guiding the workpiece and at least three blocks arranged radially around the guide are provided. Each block is provided with a measuring element having a substantially spherical contact that abuts on the inner surface of the workpiece, a moving mechanism for moving the measuring element radially from the guide center, and an abutting arrangement for the moving mechanism. A detector is provided.

  In this aspect, the moving mechanism may include 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 be linearly movable. 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, and the detector in the one vertical portion. It is desirable to attach the measuring element to the other vertical part of the measuring element base by abutting the end of the measuring element.

  Further, the guide includes a disc-shaped guide portion that approximates the inner diameter of the workpiece and is smaller in diameter than the inner diameter of the workpiece, a disc-shaped guide base disposed below the guide portion, and the guide portion and the guide. A support column for supporting the base; a groove extending in the radial direction corresponding to the number of blocks on the back side of the guide part; and a through groove corresponding to the groove formed in the guide part on the guide base; It is desirable that the other vertical portion of the probe base can be inserted into the through groove.

  Another feature of the present invention that achieves 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 measuring elements each having a spherical contact. By operating the guide part so that the circumferential distribution of the gap formed between the outer diameter of the disk-shaped guide part of the guide of the inner diameter measuring device and the inner surface of the master is substantially constant, Obtaining a center, and storing the position of the measuring element in the ideal state obtained, and a measuring step of covering the guide part with a work and contacting the contactor, and in the measuring step, The center of a circle formed at the contact position or contact point of the contact is obtained from the data of the contact position or contact point of at least three contacts, and is obtained from the center of the circle obtained in the preparation step and the measurement step. Round From the amount of deviation of heart to seek the true internal diameter of the workpiece.

In this feature, when the true inner diameter of the workpiece is obtained, it is preferable to obtain it from a geometrical relationship using the target value of the workpiece to be measured and the radius of the contact. There are two sets of them that can move on the same straight line, and when the two same straight lines are orthogonal to each other, the inner diameter of the workpiece is Y ₁ + Y ₂ + 2 × Z _Y +2 × is given by _{C R,}
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, X ₂ is one of a set of positional data of the measuring element forming the _pair, Y 1, Y ₂ and the other set of positional data of the measuring element forming the pair, T _R is measured target value, C _R contact You may make it be a child radius.

  According to the present invention, in the measuring apparatus for measuring the inner diameter of the workpiece, the outer diameter of the guide portion serving as a guide for inserting the measuring portion into the workpiece is formed sufficiently smaller than the inner diameter of the workpiece so that a sufficient gap is formed. Therefore, when inserting a probe into the workpiece, it can be inserted easily and quickly, either manually or automatically. In addition, since the probe is made of a steel ball with a small diameter and high accuracy, even when a pair of probe contacts the inner surface of the workpiece at the time of measurement, it can be easily corrected even if it is not on a straight line including the center of the circular cross section. The time required for measurement can also be reduced.

  Therefore, in the inner diameter measuring device, precise positioning is not required before inserting the probe of the inner diameter measuring device into the object to be measured, and the cost of the inner diameter measuring device is reduced and high accuracy measurement is possible. In addition, in the case of a measuring device that performs manual measurement, the workability of carrying in and out of the measuring place is improved, and in the case of measuring with an automatic machine, the carrying mechanism to the automatic machine and the automatic machine are improved. The unloading mechanism and positioning mechanism from the apparatus are simplified, and the cost of the apparatus is reduced.

It is a top view of one Example of the internal diameter measuring apparatus which concerns on this invention. It is a partial cross section front view of the internal diameter measuring apparatus shown in FIG. It is a disassembled perspective view of the principal part of the internal diameter measuring apparatus shown in FIG. It is a figure explaining the measuring method using the internal diameter measuring apparatus which concerns on this invention. It is a figure explaining the measuring method using the internal diameter measuring apparatus which concerns on this invention.

  Hereinafter, an embodiment of an inner diameter measuring apparatus according to the present invention will be described with reference to the drawings. FIGS. 1 to 3 are views of an embodiment of the inner diameter measuring device 100, FIG. 1 is a plan view of the inner diameter measuring device 100, and FIG. 2 is a cross-sectional view showing a part of the inner diameter measuring device 100 shown in FIG. FIG. 3 is an exploded perspective view of the main part of the inner diameter measuring apparatus 100 shown in FIG.

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

  A protrusion 191 is formed at the central portion on 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. Part 158 is positioned. On the back side of the guide portion 158, grooves extending in the radial direction at a pitch of 90 ° are formed, and constitute a moving path of the contact 182 described later in detail. The upper surface of the guide portion 158 is a flat surface. The outer diameter of the guide part 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 when the work 170 is manually or automatically carried into and out of the measurement part. The diameter is about 1 mm.

  The guide base 156 on which the work 170 is placed has a disk shape, and the outer diameter thereof is larger than the outer diameter of the work 170. A through hole 155 is formed at the center of the guide base 156, and a projection 191 of the guide portion 158 is fitted on the upper surface side, and a projection 154 of a column 152 described later is fitted on the lower surface side. Grooves 157 having a rectangular cross section extending in the radial direction are formed at four positions at a 90 ° pitch in the circumferential direction at the intermediate position in the radial direction of the guide base 156. The support column 152 has a columnar shape extending vertically, and protrusions 154 and 153 are formed at both upper and lower ends and 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, the four blocks 300 arranged at a 90 ° pitch around the work 170 will be described. Since these four blocks 300 have the same configuration, only one of them will be described. The divided base 120 is placed on the base 110 such as a surface plate with a gap corresponding to the radius of the support column 152. The divided base 120 (120a to 120d) has a shape in which a corner of one side of a rectangle is dropped when viewed from above, and forms a cross-shaped base with an open central portion by directing the dropped corner toward the support 152 side. .

  Rails 130 (130a to 130d) extending radially (straight) in the radial direction of the support column 152 are fixed to the upper surfaces of the divided bases 120a to 120d by fixing means (not shown). Each rail 130a-130d is position-adjusted for every division | segmentation base 120 using the division | segmentation base adjustment tool 122 so that the rail 130 arrange | positioned on the adjacent division | segmentation base 120 may make a 90 degree pitch correctly. The rail 130 is prepared in order to accurately move a slider 140 described later in the radial direction (radially).

  Note that the rail 130 may be constituted by a pair of rails extending beyond the center of the support column 152, and these may be crossed at an angle of 90 ° accurately. In this case, the time required for positioning the rail can be reduced. However, a means for solving the interference between the support column 152 and the rail 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 bowl shape in cross section, and is formed to be movable on the rail 130 in the radial direction with little frictional resistance and without causing shaking or vibration. An attachment portion 236 formed at one end of the tension spring 230 is attached to one side surface of the slider 140 that is radially outward. 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 the base 160 for the measuring element 180 having a substantially inverted letter shape in front view is placed on the upper surface. The base 160 is composed of first and second vertical portions 162 and 164 and a bottom portion 166 connecting the two vertical portions 162 and 164. A part of the lower end of the second vertical portion 164 is a bottom portion. It extends below the lower surface of 166 and is used as a positioning portion 167 when placed on the slider 140.

  The second vertical portion 164 of the base 160 is formed on the back side of the guide portion 158 through the groove 157 formed in the guide base 156 of the guide 150 in the vertical direction when the measurement apparatus 100 is assembled. It extends into the radial groove 159. Further, a mounting hole 165 for mounting the measuring element 180 is formed in the surface near the upper end of the second vertical portion 164 and facing the first and second vertical portions 162 and 164.

  A contact portion 214 with which the detection head 218 of the detector 210 contacts is formed on the outer surface side of the first vertical portion 162 of the base 160 for the measuring element 180, that is, on the radially outer side of the support column 152. On the side, an abutting portion 222 with which the tip of the air cylinder 220 abuts is formed. Note that the width of the base 160 for the measuring element 180 is made smaller than the width of the slider 140 to narrow the width of the groove 157 of the guide base 156 and the groove 159 of the guide portion 158, and the second vertical portion 164 serves as a workpiece. The workpiece 170 is prevented from being damaged by interfering with the 170.

  In order to bring the detection head 218 of the detector 210 into contact with the base 160 for the measuring element 180, the detector 210 is held by the detector bracket 250. The detector bracket 250 has an S-shaped cross section, and the bottom 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 the upper portion 252 of the detector bracket 250. After inserting the detector 210 into the holding hole 212 so that the detection head 218 faces inward in the radial direction, a screw (not shown) is provided. The detector 210 is fixed to the holding hole 212 with a fixture such as the above. 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 almost directly below the holding hole 212, and further below that, 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 illustrated in the present embodiment, two or more through holes 234 may be provided for each detector 210. In that case, the position in the width direction of the through hole 234 is not necessarily 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 surface of the split base 120 by using a positioning tool 246 using a fixing tool such as a bolt (not shown). The air cylinder bracket 240 includes a bottom portion 242 and a vertical portion 244. A holding hole 224 that is a through hole is formed in the vicinity of the upper end portion 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 of the 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 air cylinder holding hole 224, the through hole 226 formed in the detector bracket 250, and the contact portion formed in the measuring element base 160 are also arranged in a straight line.

  In assembling the measuring apparatus 100 of this embodiment configured as described above, four divided bases 120 are placed on the base 110 such as a surface plate, and the rails 130 are fixedly arranged on the respective divided bases 120. In this state, the position of each divided base 120 is finely adjusted by using the divided base adjusting tool 122 so that the rails have a pitch of 90 °. The divided 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 at the center in the width direction of the slider 140 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 mounted on the side surface. Further, a 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. The contact portion 222 of the air cylinder 220 is fixed to the probe base 160.

  The air cylinder 220 is for bringing the contact 182 of the measuring element 180 into contact with or away from the work inner surface 172. By pushing and pulling the measuring element base 160, the work 170 is moved to the guide portion 158. When covering, the guide portion 158 is pulled out so as not to go outward in the radial direction, and during measurement, the guide portion 158 is pushed outward in the radial direction. The tension spring 230 is for securing a contact pressure on the contact 182 of the measuring element 180 at the time of measurement. The detector 210 may be anything that can measure length, and a linear encoder that is an optical or magnetic length measuring device, a pencil length measuring device described in the present embodiment, or the like can be used.

  On the other hand, the guide 150 is positioned by fitting the projection 153 of the support column 152 of the guide 150 into the positioning hole 114 formed in the central space of the base 110 where the four divided bases 120 are arranged. Next, the protrusion 154 at the upper end of the support column 152 is fitted into a through hole 155 formed in the center of the guide base 156. At that 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 mounted on the slider 140. Further, the projection 191 formed at the center of the back 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, the radial groove 159 formed on the back surface of the guide portion 158 and the second vertical portion 164 so that the guide portion 158 does not interfere with the probe base 160 placed on the slider 140. Align the circumferential position of.

  When the workpiece 170 is introduced into the inner diameter measuring apparatus 100 assembled in this way, the measurement is performed using the rail 130 and the slider 140 so that the contact 182 at the tip of the measuring element 180 does not contact the work inner surface 172. The child 180 is drawn inward in the radial direction. Since the outer diameter of the guide portion 158 is set to be smaller than the known nominal diameter of the workpiece 170 by c on one side, the workpiece 170 can be easily fitted to the outside of the guide portion 158, either manually or using an automatic machine. be able to.

  Next, a specific measurement method using the inner diameter measuring apparatus 100 configured as described above will be described with reference to FIGS. FIG. 4 is an example of a measurement method when detectors are arranged at 90 ° pitches at four locations in the circumferential direction, and FIG. 5 is a measurement method when detectors are arranged at six locations in the circumferential direction at 60 ° pitches. It is an example. In the case of FIG. 5, unlike the above embodiment, six sets including the divided base 120 are all required, but the basic configuration is the same. That is, the inner diameter measuring device 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 90 ° pitch to six at 60 ° pitch. Is prepared.

  FIG. 4 is a diagram showing the positional relationship between the small diameter, substantially spherical contact 182 disposed at the tip of the measuring element 180 used for indirectly measuring the inner diameter of the work 170 and the work 170. 4 (a) is a diagram schematically showing an ideal state in which the intersection of two sets of straight lines obtained by connecting the centers of two spherical contacts 182 arranged opposite to each other and the center of the inner surface 172 of the workpiece 170 are coincident with each other. FIG. 4B schematically shows a state in an actual measurement in which the intersection of two sets of straight lines obtained by connecting the centers of two spherical contacts 182 arranged opposite to each other and the center of the inner surface 172 of the workpiece 170 are different. FIG. In these drawings, the amount of deviation is exaggerated for easy understanding. This is the same in FIG.

  An object of the present invention is to quickly measure the inner diameter of a mass-produced product. Therefore, the clearance c between the inner surface 172 of the workpiece 170 and the outer diameter of the guide portion 158 of the guide 150 is set to an extent that does not hinder the covering of the workpiece 170 on the guide portion 158. When actually measuring the inner diameter of the workpiece 170, the following is executed as a preliminary preparation.

First, the input to the control unit (not shown) of a radius C _R the measuring apparatus 100 of inside diameter target value, such as T _R and the contact 182 of the workpiece 170 as described in the design drawing. Here, the target value T _R is the processing target of the workpiece 170, the contact 182 is one that is manufactured by using a steel ball or the like of the high-precision rolling bearings. Thus, in the embodiment of FIG. 4, since there is only enough submicron error between the radius C _R of the four contacts 182, radius C _R of each contact 182 is considered identical.

  Next, a workpiece 170 having a high roundness, that is, a strain that has been used in the past measurement is prepared as a master 170M, and the position of each slider 140 is adjusted so as to be in the state of FIG. 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 or the like, 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 opposed 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, the position detection by contact of each contact 182 with the workpiece 170 or the master 170M is detected as a one-to-one conversion as the amount of movement of the detection head 218 of the detector 210. Therefore, the output of each detector 210 when the state shown in FIG. 4A is obtained is stored as a reference position by a control unit (not shown).

  Next, the measurement object is exchanged from the master 170M to the workpiece 170. At that time, in order to speed up the work of transporting the work 170 to the measurement place, the work 170 is not positioned so as to be in the state shown in FIG. Therefore, generally, a non-uniform gap is 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.

At the time of measurement, as shown in FIG. 4B, the contact 182 that is the head of the measurement element 180 is moved so as to contact the work inner surface 172, so that the contact 182 is the center position O ₁ of the deflected work 170. Are located on the circumference 182 _{a to} 182 _d , but are not arranged on the circumference at an equal pitch. Moreover, the circumferential pitch between the contacts 182 is ideal 90 ° pitch positions 182 _{a0 to} 182 _d0 even on the coordinate system centered on the origin O fixed to the measurement apparatus 100 shown in FIG. Not necessarily. Therefore, the inner diameter of the workpiece 170 cannot be obtained even if the output of the detector 210 corresponding to the position of the contact 182 is used as it is. In order to obtain an accurate inner diameter of the workpiece 170 from the contact position data of the contact 182, the contact 182 is arranged at equal pitch positions 182 _{a0 to} 182 _d0 on the circumference of the center O ₁ , or the detected value is set by any method. Convert with In the former case, it takes time to detect the position, 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 of each contact 182 radially inward as − and the amount of movement outward in the radial direction as +. When detected, the pair of opposing contacts 182 and 182 in the X direction are moved from the virtual equal pitch points 182 _a0 and 182 _b0 on the coordinate system of the actual workpiece 170 having the center O ₁ to the actual position 182 _a. , it has become 182 _b. Accordingly, a line 263 connecting the centers of the pair of opposing contacts 182 and 182 in the X direction is also a straight line 261. Similarly, the pair of opposing contacts 182 and 182 in the Y direction is changed from the virtual equal pitch points 182 _c0 and 182 _d0 on the coordinate system of the actual workpiece 170 having the center O ₁ to the actual position 182 _c , It has become 182 _d. Accordingly, a straight line 264 connecting the centers of the pair of opposed contacts 182 and 182 is also a straight line 262.

A displacement amount of the straight line 263 to the straight line 261 is a Y direction displacement amount Y _L of the workpiece 170 from the ideal position, and a displacement amount of the straight line 264 to the straight line 262 is a displacement amount X of the workpiece 170 from the ideal position in the X direction X. _L. Shift amount X _L in the X direction, each of the ideal position of the two contacts 182, 182 which faces the Y-direction, that is, the position detection relative to the position detection value in the circumferential direction such gap when measured in the master 170M It is the average value of the difference between the values X ₁ and X ₂ . Similarly, the amount of displacement Y _L in the Y direction is based on the ideal position of each of the two contacts 182 and 182 facing in the X direction, that is, the position detection value of the circumferential equal gap when measured by the master 170M. This is the average value of the differences between the detected position amounts Y ₁ and Y ₂ . From these relationships,
X _L = (X ₁ −X ₂ ) / 2,
Y _L = (Y ₁ −Y ₂ ) / 2,
The distances X _max and Y _max between the centers of the two pairs of opposed contacts 182 are given by Z _{Y and the} like in the figure based on the geometrical relationship shown in FIG. Is expressed by the following equation. Here, FIG. 4C shows only the portion related to the geometric position in the Y direction for the sake of clarity, but the same applies to the geometric positional relationship in the X direction. The function SQRT () is a function that takes a square root.
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 ,
Also,
Z _Y = a _{(T R -C R) -SQRT (} (T R -C R) 2 -X L 2),
If the inner diameter of the workpiece 170 is a work 170 circularity _{becomes Y max + 2 × C R =} X max + 2 × C R.

  As described above, the workpiece 158 is placed on the work inner surface 172 so that the guide portion 158 of the guide 150 is freely inserted within the gap, and then the contact 182 of the measuring element 180 is placed at that position on the rail 130 and the slider. The inner diameter of the workpiece 170 can be easily and accurately measured simply by extending in the radial direction via 140 and contacting the inner surface of the workpiece. Therefore, accurate centering of the workpiece 170 with respect to the guide portion 158, which has been conventionally required, is 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 very slightly smaller than the inner diameter of the workpiece, for example, about 15 to 30 μm (gap on one side). With a small gap, it takes time to put the work on the guide. On the other hand, in the present invention, the gap can be increased to about 1 mm (both side gaps), so that the work 170 can be easily and quickly put on the guide portion 158 by both manual and automatic machines. The contact point of the contact 182 with the work inner surface 172 changes as the contact 182 moves on the work inner surface 172, but the above relationship is always maintained because the outer shape of the contact 182 is a spherical surface.

  In the above embodiment, four measuring elements 180 are arranged at a 90 ° pitch and the output of the detector 210 for all the measuring elements 180 is used, but the inner diameter of the workpiece 170 is measured even with three measuring elements 180. It is possible. This example will be described with reference to FIG. The result shows that one contact 182 in the X direction, which is one of the two contacts 182 arranged opposite to each other in the Y direction, and one of the X direction contacts is brought into contact with the work inner surface 172.

Specifically, a circle center O ₁ through which the centers of the contacts 182 pass is obtained from the three contact positions 182 _b , 182 _c , and 182 _d and fixed to the center position O ₁ and the inner diameter measuring device 100. the center position of the coordinate system determining the X-direction displacement amount X _L between the (ideal position) O. From the geometrical relationship shown in FIG.
_{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) because,
Y _max = Y ₁ + Y ₂ + 2 × Z _Y
Is obtained. Therefore the inner diameter of the workpiece 170 _{becomes Y max} + 2 × _{C R.}

  Next, an example in which the number of arranged measuring elements 180 is increased will be described with reference to FIG. Since the measuring device is increased in size by increasing the measuring element 180, it is not suitable for measuring a small inner diameter, but is used when the inner diameter of the work 170 is large and it is desired to check the roundness. It is possible. FIG. 5 shows a case where 3 to 6 measuring elements 180 are used. The specific configuration of the measurement block 300 is the same as that shown in FIGS.

  FIG. 5A is a view corresponding to the description of FIG. 4A, and is arranged so that the inner surface 172 of the workpiece or the inner surface of the master 170M is opposed to the guide portion 158 of the inner diameter measuring device 100 with a constant circumferential clearance c. The ideal position is shown. The pair of contacts 182 of the measuring apparatus 100 are arranged in the Y-axis direction as in the embodiment of FIG. 4, but are not arranged in the X-axis direction and form an angle of 60 ° with the Y-axis. Thus, two pairs of contacts 182 are arranged. That is, the pair of contacts 182 are arranged in the A axis direction that forms an angle of 120 ° with the Y axis, and the other pair of contacts 182 are arranged in the B axis direction that forms an angle of 60 ° with the Y axis. .

FIG. 5B is a diagram showing the positional relationship of each contact 182 in actual measurement as in FIG. 4B. As with the four-way measurements shown in FIG. 4 (b), stored in the control unit (not shown) radius C _R of the radius of the target value T _R and the contact 182 of the workpiece 170. 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 position change of each contact 182 from the ideal position is a fixed coordinate system to the internal diameter measurement device 100 obtains a shift amount X _L of the center position of the actual workpiece 170 with the center O of the ideal position is placed determines the inside diameter of the Y direction based on the shift amount X _L.

Specifically, from the measured values X _A1 and X _A2 and the measured values X _B1 and X _{B2 in the} B direction of the detector 210 corresponding to the movement amount of the contact 182, between the two centers O and O ₁ . The deviation amounts X _AL and X _BL in the A direction and the B direction are obtained as follows.
_{X AL = (X A1 -X A2} ) / 2
_{X BL = (X B1 -X B2} ) / 2
FIG. 5C is an enlarged view of a part of FIG. From the positional relationship shown in FIG. 5 (c), using a trigonometric _function, the deviation amount _{X B} in the X direction by the shift amount _{X A} and _{X BL} in the X direction by the _{X AL} is
X _A = X _AL / cos 30 °,
X _B = X _BL / cos 30 °
Next, the deviation amount X _L in the X direction because it is these mean values,
X _L = (X _A + X _B ) / 2
Is obtained. Using the outputs Y ₁ and Y ₂ of the detector 210 relating to the Y-direction contact 182 arranged in the same manner as the embodiment shown in FIG. 4, Y _max corresponding to the inner diameter of the workpiece 170 is shown in FIG. From the geometric relationship shown, it can be determined by the following formula. Here, FIG.5 (d) is a figure 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 × Z _Y
Since it is, the inner diameter of the workpiece 170 is obtained by _{Y max} + 2 × _{C R.}

  Also in the present embodiment, when the work 170 is put on the guide portion 158 of the guide 150, the gap can be increased as compared with the conventional case, and a precise centering operation between the guide portion 158 and the work 170 is not required. The time required for measurement setup can be greatly reduced. In addition, the measurement throughput can be improved because the measurement can be easily and rapidly performed manually or using an automatic machine.

  In the present embodiment, the case of using 3 to 6 probe is described, but the measurement can be similarly performed using 4 to 8 or more probe. Furthermore, even if the measuring elements are not arranged at an equal pitch, if the workpiece is measured based on the recording in the master after performing the recording in the ideal state, that is, in the coordinate system fixed to the measuring apparatus, By the above-described method, the inner diameter of the workpiece can be measured quickly and easily. Therefore, the time required for transporting the workpiece to and from the measurement location and the time required for centering the workpiece can be reduced, so that the work efficiency of the measurement work is improved.

DESCRIPTION OF SYMBOLS 100 ... Inner diameter measuring apparatus, 110 ... Base (surface plate), 112 ... Hole, 114 ... Positioning hole, 120, 120a-120d ... Divided base, 122 ... Divided base adjustment tool, 130, 130a-130d ... Rail, 140 ... Slider , 150 ... guide, 152 ... support, 153, 154 ... projection, 155 ... through hole, 156 ... guide base, 157 ... (radial direction) groove, 158 ... guide part, 159 ... (radial direction) groove, 160 ... base ( (For measuring element), 162 ... (first) vertical part, 164 ... (second) vertical part, 165 ... mounting hole, 166 ... bottom part, 167 ... positioning part, 170 ... work (object to be measured), 170M ... master, 172 ... work inner surface, 180 ... measuring element, 182 ... _contact, 182 a _~182 d _... contact _position, 182 a0 _{~182 d0 ...} contact virtual position, 18 _{a ~183} f _... contact position, 183 _{c0 ...} contact virtual position, 184 ... attaching portion, 191 ... projection, 210 ... detector, 212 ... holding hole, 214 ... contact portion, 218 ... detection head, 220 ... Air Cylinder, 222 ... abutting part, 224 ... holding hole, 226 ... through hole, 230 ... tension spring, 232 ... attachment part, 234 ... through hole, 236 ... attachment part, 240 ... bracket (for air cylinder), 242 ... bottom part 244: Vertical portion, 246: Positioning portion, 250: Bracket (for detector), 252 ... Upper portion, 254 ... Bottom portion, 256 ... Vertical portion, 300 ... Block, A, B ... Direction, c ... Clearance, _CR ... Contact child radius, O ... center, O 1 _... virtual center, _{T R} ... (target value) radius, X ... direction, _{X 1, X} 2 _... measured _{value, X A, X B, X} AL, X BL, X L ... Misalignment amount, X _{max ...} reference inner diameter, Y ... direction, _{Y 1, Y} 2 _... measured value, _{Y max ...} reference inner diameter, Y L _... positional deviation amount, _{Y Y} ... Y direction length, [Delta] Y ... shift amount

Claims (7)

In an inner diameter measuring device that measures the inner diameter of a cylindrical workpiece,
A guide for guiding the workpiece;
And at least three blocks arranged radially around the periphery of the guide,
The block is
A measuring element provided with a substantially spherical contact that abuts against the inner surface of the workpiece,
A moving mechanism for moving the measuring element radially from the guide center;
A detector disposed in contact with the moving mechanism;
An inner diameter measuring device comprising: The moving mechanism includes rails arranged on a straight line extending radially from the center of the guide;
A slider mounted on the rail so as to be linearly movable;
The inner diameter measuring apparatus according to claim 1, comprising:   The moving mechanism includes a measuring element base that holds the measuring element fixed to an upper surface of the slider, and includes an air cylinder having one end fixed to one vertical portion included in the measuring element base, The inner diameter measuring apparatus according to claim 2, wherein an end of the detector is brought into contact with a portion, and the measuring element is attached to the other vertical part of the measuring element base. The guide is
A disk-shaped guide portion that approximates the inner diameter of the workpiece and is smaller than the inner diameter of the workpiece;
A disc-shaped guide base disposed below the guide portion;
A support for supporting the guide portion and the guide base,
A groove extending in the radial direction corresponding to the number of the blocks is provided on the back side of the guide portion,
The through hole corresponding to the groove formed in the guide portion is further provided in the guide base, and the other vertical portion of the measuring element base can be inserted through the through groove. Inner diameter measuring device. An inner diameter measuring method for measuring an inner diameter of a cylindrical workpiece using an inner diameter measuring device provided with at least three measuring elements having a spherical contact,
By operating the guide part so that the circumferential distribution of the gap formed between the outer diameter of the disk-shaped guide part of the guide of the inner diameter measuring device and the inner surface of the master is substantially constant, A preparatory step of obtaining a center and storing the obtained position of the probe in the ideal state;
A measurement step of covering the guide portion with a work and bringing the contact into contact therewith,
In the measurement step, the center of a circle formed by the contact position or contact point of the contact is determined from the data of the contact position or contact point of at least three contacts,
A method for measuring an inner diameter, comprising: obtaining a true inner diameter of a workpiece from a deviation amount between a center of a circle obtained in the preparation step and a center of a circle obtained in a measurement step.   6. The inner diameter measuring method according to claim 5, wherein when the true inner diameter of the workpiece is obtained, the inner diameter is obtained from a geometric relationship using a target value of the workpiece to be measured and a radius of the contact. When there are four measuring elements, two of them can be moved together on the same straight line, and when the two identical straight lines are orthogonal, the inner diameter of the workpiece is Y ₁ + Y given by _{2 + 2 × Z Y + 2} × C R,
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, X ₂ is one of a set of positional data of the measuring element forming the _pair, Y 1, Y ₂ and the other set of positional data of the measuring element forming the pair, T _R is measured target value, C _R contact The inner diameter measuring method according to claim 5 or 6, wherein the inner radius is a child radius.