JP2006029865A - Device and method for measuring internal diameter of cylindrical body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and a method for measuring internal diameter of a cylindrical body, which reduces cost, and improves productivity, and operability of measurement. <P>SOLUTION: The device for measuring internal diameter of a cylindrical body is provided with the moveable body 27 comprising: a frame main body 18 arranged in the cylindrical body 10 with clearances from the inner wall 17 of the cylindrical body 10; and at least three radially disposed front guide members 19-22 and the rear guide members 23-26 provided in front of and the rear of the frame main body 18 respectively, and moveable along the inside wall 17 of the cylindrical body 10. The device is also provided with dial gauge pairs provided on both radial sides while centering the center position O of the moveable body 27 in the section perpendicular in the moving direction of the moveable body 27, energized always radially outward, and having spindles 29, the top of the gauge heads 28 of which are in contact with the measurement parts S of the inner wall 17 of the cylindrical body 10. Moreover the two pairs of the dial gauge pairs are arranged on the sections perpendicular to the direction of the moveable body 27, on the different positions. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to an inner diameter measuring device and method for measuring the inner diameter of a cylindrical body, for example, a long barrel of an extruder.

If the inner diameter of the barrel (also called cylinder) of the extruder used as a device for melting and plasticizing by heating the plastic raw material exceeds the reference value (allowable value) due to corrosion and wear, the barrel Therefore, it is necessary to periodically measure the inner diameter of the barrel.
As an apparatus for measuring the inner diameter of a cylindrical body such as a barrel, for example, one described in Patent Document 1 is known. However, the inner diameter measuring device described in Patent Document 1 is a device for measuring the end of a steel pipe in order to connect large diameter steel pipes, and has a long inner diameter like a barrel of an extruder. When is small, the end portion including the intermediate portion cannot be measured.
Therefore, in order to measure the inner diameter of the barrel, the built-in screw is removed, the barrel is disassembled into a plurality of segments, and the inner diameter is measured by an inside micrometer or barrel gauge from both sides of each segment.

JP 7-43103 A (FIG. 1)

However, since the barrel is disassembled into a plurality of segments, it takes time for disassembling and assembling work, which is costly and unproductive. In addition, it is necessary to carry out heat insulation work attached to each segment, and when handling heavy barrels, handling properties were poor. Furthermore, in the measurement with the inside micrometer or the barrel gauge, the measurement takes time and the workability of the measurement is inferior.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an apparatus and a method for measuring the inner diameter of a cylindrical body that can reduce costs and improve productivity and workability of measurement.

The cylindrical body inner diameter measuring apparatus according to claim 1, which meets the object, is a cylindrical body inner diameter measuring apparatus that is inserted into a cylindrical body or a cylindrical body that is partially missing, and measures the inner diameter of the cylindrical body. ,
A frame main body disposed in the cylindrical body with a gap from the inner wall of the cylindrical body, provided at the front side of the frame main body, and at least three radially arranged to move along the inner wall of the cylindrical body. A plurality of front guide members, and a movable body provided on the rear side of the frame main body, each including at least three rear guide members arranged in a radial manner to move along the inner wall of the cylindrical body,
Provided on both sides in the radial direction centering on the center position of the moving body in a cross section perpendicular to the traveling direction of the moving body, and constantly biased outward in the radial direction, the measurement object site on the inner wall of the cylindrical body A dial gauge pair having a spindle with which the probe contacts,
Moreover, there are two pairs of dial gauges, and the two pairs of dial gauges are provided at different positions on the cross section perpendicular to the traveling direction of the moving body.
The cylindrical body has a circular internal cross section, and the cylindrical body with a part missing is a circular part with a partial internal cross section. Define as good.

The cylindrical inner diameter measuring device according to claim 2 is the cylindrical inner diameter measuring device according to claim 1, wherein the two sets of dial gauge pairs are provided at a 90-degree crossing position with respect to the center of the movable body. It has been.
The cylindrical inner diameter measuring device according to claim 3 is the cylindrical inner diameter measuring device according to claim 1 or 2, wherein the front guide member and the rear guide member are provided with freely rotatable guide balls, With respect to the frame main body, the frame main body is disposed so as to be able to advance and retract radially outward with reference to the center position of the frame main body.
The cylindrical inner diameter measuring device according to claim 4 is the cylindrical inner diameter measuring device according to any one of claims 1 to 3, wherein either one of the front and rear of the frame body is moved to pull or push the frame body. A coupling mechanism for coupling the means is provided.

According to a fifth aspect of the present invention, there is provided a method for measuring an inner diameter of a cylindrical body, wherein the moving body is inserted into a cylindrical body or a cylindrical body that is partially missing, and moves along the inner wall of the cylindrical body. A spindle is provided on both sides in the radial direction centering on the center position of the movable body in an orthogonal cross section, and is constantly urged outward in the radial direction so that the measuring element at the tip of the spindle contacts the measurement target portion of the inner wall of the cylindrical body. Two pairs of dial gauges are provided at different positions on a cross section perpendicular to the traveling direction of the movable body, and the inner diameter of the cylindrical body is measured using the two pairs of dial gauge pairs,
The inner diameter at two crossover positions at 90 ° with respect to the center of the cylindrical body on the cross section perpendicular to the axial direction of the cylindrical body at one side end of the cylindrical body is set as a reference diameter by the measuring means. A reference diameter measuring process to be measured;
A zero value setting step of setting each of the two pairs of dial gauges to a zero value at the measurement position of the cylindrical body as the reference diameter;
The movable body moves along the axis of the cylindrical body without rotating in a cross section perpendicular to the axial direction of the cylindrical body, and the increase / decrease value with respect to the reference diameter is measured by the two pairs of dial gauges. An increase / decrease value measurement process,
An actual inner diameter calculating step of obtaining an actual inner diameter of the cylindrical body by adding the increase / decrease value to the reference diameter.

5. The cylindrical inner diameter measuring apparatus according to claim 1, wherein the dial has a moving body that moves along the inner wall of the cylindrical body, and a spindle that contacts a measuring element at the tip of the measuring object portion of the inner wall of the cylindrical body. Since two pairs of dial gauges are provided at different positions on the cross section perpendicular to the traveling direction of the moving body, even if the cylinder body is long and has a small diameter, for example, without being disassembled. Can be measured and the time for disassembly and assembly can be shortened, resulting in a reduction in cost and an increase in productivity. Further, the measurement can be performed in a short time as compared with the conventional measurement using an inside micrometer or a barrel gauge, and the workability of the measurement is improved.

Particularly, in the cylindrical body inner diameter measuring apparatus according to claim 2, since the two pairs of dial gauges are provided at the 90-degree crossing position with respect to the center of the moving body, the inner diameter of the cylindrical body can be more accurately determined. Can be measured.
In the cylindrical body inner diameter measuring apparatus according to claim 3, since the front guide member and the rear guide member are provided with a freely rotatable guide ball, the movable body is moved along the inner wall of the cylindrical body with a small force. Can move. In addition, the front guide member and the rear guide member are arranged so as to be able to advance and retract radially outward with respect to the center position of the frame body, so that the front guide member and the rear guide member are also applicable to cylindrical bodies having different inner diameters. Because it can, versatility increases.
In the cylindrical body inner diameter measuring device according to claim 4, since a connecting mechanism for connecting a moving means for pulling or pushing the frame body is provided on either the front or back of the frame body, various movements are provided. The moving body can be moved using the means.

In the method for measuring the inner diameter of the cylindrical body according to claim 5, the two inner diameters at one end of the cylindrical body are measured as the reference diameter by the measuring means in the reference diameter measuring step, and the reference diameter is measured in the zero value setting step At each measurement position, set each of the two pairs of dial gauges to zero, and move along the axis of the cylinder without rotating the moving body in the increment / decrement measurement process. By measuring the increase / decrease value with respect to the reference diameter with the gauge pair and adding the increase / decrease value to the reference diameter in the actual inner diameter calculation step, the actual inner diameter of the cylindrical body can be obtained. For example, measurement can be performed without disassembling, and the time for disassembling and assembling can be shortened. As a result, costs can be reduced and productivity can be improved. Further, the measurement can be performed in a short time as compared with the conventional measurement using an inside micrometer or a barrel gauge, and the workability of the measurement is improved.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
Here, FIG. 1 is a front sectional view of a barrel that is measured by applying a cylindrical inner diameter measuring apparatus according to an embodiment of the present invention, and FIG. 2 is a barrel that is measured by applying the cylindrical inner diameter measuring apparatus. 3 is a front view of the inner diameter measuring device of the cylindrical body, FIG. 4 is a side view of the inner diameter measuring device of the cylindrical body, and FIGS. 5A and 5B are inner diameter measurements of the cylindrical body, respectively. FIGS. 6A, 6B, and 6C are explanatory views showing the use status of the positioning guide bar of the apparatus, and FIGS. 6A, 6B, and 6C are measurement results of the barrel by the cylindrical body inner diameter measuring method according to one embodiment of the present invention. FIGS. 7A and 7B are respectively an explanatory diagram of an inner diameter measurement position by the inner diameter measurement method of the cylindrical body and an explanatory diagram of a measurement position by a modification.

As shown in FIGS. 1 to 4, an inner diameter measuring device 60 of a cylindrical body according to an embodiment of the present invention has a circular cross section inside a twin-screw extruder that applies heat to a plastic raw material to melt and plasticize it. Is a device that measures the inner diameter K of the barrel 10 by being inserted into the barrel 10 which is an example of a cylindrical body lacking a part of (for example, a range of less than 90 °). The barrel 10 of the twin-screw extruder includes two screws 11 and 12 that form a pair, and the barrel 10 is configured by assembling four barrel segments 13 to 16.

The barrel 10 has an inner diameter (nominal diameter) K of 100 to 1000 mm and a length L of 1000 to 10,000 mm (in this case, the inner diameter K = 320 mm and the length L = 4100 mm). In the following description, it is assumed that the cylindrical inner diameter measuring device 60 measures the inner diameter on the screw 11 side as the inner diameter K. Further, the barrel 10 from which the two screws 11 and 12 are extracted is horizontally arranged, and the direction in which the cylindrical inner diameter measuring device 60 moves inside the barrel 10 is the front-rear direction, and the horizontal direction perpendicular to the front-rear direction. Are defined as the vertical direction.

As shown in FIGS. 3 and 4, the cylindrical inner diameter measuring device 60 includes a frame main body 18 disposed in the barrel 10 with a gap from the inner wall 17 of the barrel 10, and a front side of the frame main body 18. The four front guide members 19 to 22 that are provided and move radially along the inner wall 17 of the barrel 10 and the rear side of the frame main body 18 are respectively moved along the inner wall 17 of the barrel 10. The movable body 27 includes four rear guide members 23 to 26 arranged in a radial manner.

The cylindrical body inner diameter measuring device 60 is further provided on both sides in the radial direction around the center position O of the moving body 27 in a cross section orthogonal to the traveling direction of the moving body 27, and is always urged outward in the radial direction. From the two dial gauge pairs, that is, the dial gauge pair consisting of dial gauges 51 and 52 and the dial gauges 53 and 54, each having a spindle 29 with which the probe 28 at the tip of the inner wall 17 is measured. The two dial gauge pairs are provided at different positions on the cross section perpendicular to the traveling direction of the moving body 27 (positions rotated by 90 ° in the present embodiment). Yes. These will be described in detail below.

As shown in FIGS. 3 and 4, the frame body 18 is a short pipe disposed on the rear side of the moving body 27 around the center position O of the moving body 27 in a cross section orthogonal to the traveling direction of the moving body 27. Mounting member 31 made of a material, rib members 32 to 35 made of pipe material radially divided into four circumferential directions on the inner peripheral surface of the mounting member 31, and radially inner sides of the rib members 32 to 35 The end portion is fixed to the outer peripheral portion of the rear end portion, and is connected to the connecting member 36 made of a pipe material disposed horizontally, and the outer peripheral portion of the front end portion of the connecting member 36, and is divided into four equal parts in the circumferential direction. And mounting members 37 to 40 each made of a pipe material. The front guide members 19 to 22 are in the same position as the rear guide members 23 to 26 as viewed along the axial direction of the barrel 10. The rib members 32, 34 arranged vertically are orthogonal to the rib members 33, 35 arranged horizontally, and the attachment members 37, 39 arranged inclined by 45 ° with respect to the horizontal direction are attached to the attachment member 38. Therefore, the rib members 32 and 34 and the rib members 33 and 35 are 45 ° out of phase with the attachment members 37 and 39 and the attachment members 38 and 40, respectively.

Each of the front guide members 19 to 22 and the rear guide members 23 to 26 has the same size and specifications, and a freely rotatable guide ball B (with a spherical diameter of 25. 4 mm), and is disposed so as to be able to advance and retract radially outward with respect to the frame body 18 with respect to the center position O of the frame body 18. The front guide members 19 to 22 and the rear guide members 23 to 26 are provided substantially vertically on the bottom surface of the operation portion provided with the guide ball B on the radially outer side, and a male screw portion is formed. And a female threaded portion that is screwed into the male threaded portion is formed at four positions of the distal end portion of the mounting members 37 to 40 and the mounting member 31 via a positioning fixing nut (not shown). The position in the radial direction can be adjusted.

The dial gauges 51 to 54 are attached by screw fastening via brackets 30 fixed to four places of the attachment member 31. Moreover, the dial gauge pair of the dial gauges 51 and 52 and the dial gauge of the dial gauges 53 and 54 are attached. The pair is provided at a position where the pair intersects 90 degrees with respect to the center O of the moving body 27. The dial gauges 51 and 52 are attached in the vicinity of the rear guide members 23 and 25, while the dial gauges 53 and 54 are attached in the vicinity of the rear guide members 24 and 26. The dial gauges 51 and 52 and the dial gauges 53 and 54 are provided with a phase shift of about 5 ° in the clockwise direction of the center O of the moving body 27 with respect to the rear guide members 23 and 25 and the rear guide members 24 and 26, respectively. It has been. The probe 28 of the dial gauges 51 to 54 can move back and forth in the radial direction by 5 mm, and moves 1 mm radially inward and 4 mm radially outward relative to the nominal diameter K (320 mm in this embodiment). Is set to

As shown in FIG. 3, a female thread portion 41, which is an example of a coupling mechanism, is formed at the rear end portion of the coupling member 36 of the frame body 18, and a male thread portion 42 that engages with the female thread portion 41 is formed at the distal end portion. A cylindrical body inner diameter measuring device 60 can be moved inside the barrel 10 by pushing the frame main body 18 with an operating rod 43 which is an example of the formed moving means. The length R of the operation rod 43 mainly made of a pipe material is 1 to 10 m (here, R = 4 m), and a scale of 200 mm is marked so that the movement distance can be measured.

In order to move the movable body 27 without rotating in a cross section perpendicular to the axial center direction of the barrel 10 when the cylindrical inner diameter measuring device 60 is moved inside the barrel 10 by the operating rod 43, FIG. As shown in A) and (B), a positioning guide bar 44 is used.
The rod-shaped positioning guide bar 44 having a rectangular cross section has a hooking groove 45 that can be hooked at the rear end of the mounting member 31 of the moving body 27 at the base end, and the lower surface 46 at the center is the barrel 10. It is configured to come into contact with the upward tip 47 of the inner shape of the cross section and slide. A female threaded portion 48 communicating with the latching groove 45 is formed at the base end portion of the positioning guide bar 44, and the positioning guide bar 44 is fixed by a fixing bolt 50 formed with a male threaded portion 49 screwed into the female threaded portion 48. Can be fixed to the mounting member 31.

Next, a cylindrical body inner diameter measuring method according to an embodiment of the present invention using the cylindrical body inner diameter measuring apparatus 60 will be described with reference to the drawings. In advance, the positioning guide bar 44 and the operating rod 43 are attached to the cylindrical inner diameter measuring device 60, and the inner peripheral surface of the barrel 10 from which the screws 11 and 12 are removed is cleaned. The measurement will be described only on the screw 11 side.
(1) As shown in FIGS. 3, 4, and 6 (A) to (C), on one side (measurement start side) end of the barrel 10 and on a cross section orthogonal to the axial direction of the barrel 10 And measuring means, for example, an inside micrometer or a barrel gauge, for measuring the inner diameters at two positions (Y direction and Z direction in FIG. 6) at 90-degree crossing positions with respect to the center of the barrel 10 (= center position O of the moving body 27). Measure as reference diameters D _KY and D _KZ (reference diameter measurement process). D _KY = 319.93 mm, D _KZ = 319.93 mm, and a reference diameter D _KX (= 319.84 mm) in the X direction (vertical direction) is also measured for reference.

(2) The cylindrical inner diameter measuring device 60 is taken into the barrel 10 and each of the dial gauges 51 to 54 is set to a zero value at the measurement position of the barrel 10 having the reference diameters D _KY and D _KZ (zero value setting) Process).
(3) The moving body 27 is moved by the operating bar 43 while looking at the scale of the operating bar 43 without rotating the moving body 27 in a cross section perpendicular to the axial direction of the barrel 10 via the positioning guide bar 44. The inner diameter is moved 200 mm along the axial center of the barrel 10, and at this position (measurement distance N = 200 mm), the dial gauge pair of the dial gauges 51 and 52 and the dial gauge pair of the dial gauges 53 and 54 are used as the reference diameter D. _{Increase /} decrease value (± α) with respect to _KY and D _KZ is measured (increase / decrease value measurement step). At this time, the light of the flashlight is applied to the display portions of the dial gauges 51 to 54, and the operator reads the increase / decrease value with binoculars or a telescope. In FIG. 6B, the increase / decrease value (+) represents the case where the inner diameter is smaller than the zero value, and the increase / decrease value (−) represents the case where the inner diameter is larger than the zero value.

(4) The above-mentioned (3) is repeated a predetermined number of times (in this embodiment, about 20 times), and the increase / decrease value is measured over the entire length of the barrel 10. However, FIG. 6 shows the measurement distance N = 2000 mm, and is omitted thereafter.
(5) After measuring the increase / decrease value, add the increase / decrease value to the reference diameters D _KY and D _KZ to obtain the actual inner diameters D _JY and D _JZ of the barrel 10 (actual inner diameter calculation step). As an example, a case where the measurement distance N = 200 mm will be described. In the dial gauge pair of the dial gauges 51 and 52 in the Y direction, the actual inner diameter D _JY = D _KY (319.93 mm) −0.11 mm + 0.28 mm = 320.10 mm, and the dial gauges of the dial gauges 53 and 54 in the Z direction In the pair, the actual inner diameter D _JZ = D _KZ (= 319.93 mm) +0.04 mm + 0.17 mm = 320.14 mm.
In FIG. 6, for each measurement distance N, the actual average diameter H = (D _JY + D _JZ ) / 2 is obtained from the actual inner diameter D _JY and the inner diameter D _JZ obtained by calculation, and further named. A difference (K−H) between the diameter K and the average diameter H is obtained and graphed. The barrel 10 is repaired or replaced depending on the difference between the average diameter H and the nominal diameter K.

The present invention is not limited to the above-described embodiments, and can be changed without departing from the gist of the present invention. For example, some or all of the above-described embodiments and modifications are included. The combination of the cylindrical inner diameter measuring apparatus and method of the present invention is also included in the scope of the present invention.
In the above-described embodiment, the barrel 10 of the twin-screw extruder having a partially missing circular shape inside the cross section is used as the cylindrical body. However, the present invention is not limited to this, and the circular shape is not missing as necessary. A barrel of a screw extruder can also be used. Further, the cylindrical body is not limited to the barrel of the extruder, but may be other cylindrical bodies.
The two pairs of dial gauges are provided at the 90-degree crossing position with reference to the center of the moving body, but the present invention is not limited to this, and can be provided at positions other than the 90-degree crossing position as necessary.

In the present embodiment, the dial gauges 51 and 52 are provided with a phase shift of about 5 ° in the clockwise direction of the center O of the moving body 27 with respect to the rear guide members 23 and 25 due to the mounting space. However, the present invention is not limited to this, and the phases can be arranged to coincide with each other as necessary.
As described above, in the Y direction and the Z direction, which are inclined by about 40 ° with respect to the horizontal direction and the vertical direction, respectively, so that the measurement target portions S of the inner wall 17 of the barrel 10 shown in FIG. Although the dial gauge pair of the dial gauges 51 and 52 and the dial gauge pair of the dial gauges 53 and 54 are arranged, the present invention is not limited to this. For example, as shown in FIG. When measuring only the measurement target region S, the moving body can be rotated in a cross section orthogonal to the axial direction of the barrel 10 for measurement.
In the present embodiment, the inner diameter measuring device 60 of the cylindrical body is moved once in the barrel 10 in the axial direction to measure the inner diameter of the barrel 10. More accurate measurement can be performed by sequentially changing in the circumferential direction and moving the inner diameter measuring device of the cylindrical body a plurality of times in the axial direction in the barrel and measuring at a short pitch in the circumferential direction.

The dial gauges 51 to 54 are fixed to the attachment member 31 by screw fastening through the bracket 30. However, the dial gauges 51 to 54 are not limited to this, and the advancement / retraction in the radial direction is performed in accordance with the advance / retreat in the radial direction of the front guide member and the rear guide member. Can also be installed.
The front side guide members 19 to 22 and the rear side guide members 23 to 26 are provided with guide balls B that are freely rotatable. Further, the front guide members 19 to 22 and the rear side guide members 23 to 26 advance and retract radially outward with respect to the center position O of the frame body 18. However, the present invention is not limited to this, and it is possible to use a guide member having another structure in place of the guide ball as long as it can be guided according to the situation, and can be fixed without being advanced or retracted. .
The front guide members 19 to 22 and the rear guide members 23 to 26 are provided at four positions in the circumferential direction. However, the present invention is not limited to this, and three or five or more are provided depending on the situation. The front guide member and the rear guide member may be radially arranged.

The frame body 18 is mainly configured to include the attachment member 31, the coupling member 36, and the attachment members 37 to 40, but is not limited thereto, and may have other structures.
Although the female thread part 41 which is an example of the connection mechanism for connecting the male thread part 42 of the operation rod 43 was provided in the rear-end part of the frame main body 18, it is not limited to this, An internal thread portion can be provided at the end), and another moving means such as a tow rope can be used as the moving means instead of the operation rod.

Although an inside micrometer or barrel gauge was used as a measuring means for measuring the reference diameters D _KY and D _KZ , it is not limited thereto, and other measuring means can be used as necessary.
Although the barrel 10 is arranged horizontally, the present invention is not limited to this, and the barrel may be arranged vertically or inclined with respect to the vertical depending on the situation.
The positioning guide bar 44 is attached to the cylindrical inner diameter measuring device 60 so that the movable body 27 is not rotated in a cross section perpendicular to the axial direction of the barrel 10, but the present invention is not limited to this. It can also be performed without attaching a positioning guide bar. Also, in the case of a uniaxial barrel, as in the case of a biaxial barrel, a rotation prevention measure corresponding to the positioning guide bar may or may not be taken.

It is a front sectional view of the barrel which measures by applying the cylindrical inner diameter measuring device concerning one embodiment of the present invention. It is a side view of the barrel which applies and measures the internal diameter measuring apparatus of the cylindrical body. It is a front view of the internal diameter measuring apparatus of the cylinder. It is a side view of the internal diameter measuring apparatus of the cylindrical body. (A), (B) is explanatory drawing and a perspective view which show the use condition of the positioning guide bar of the internal diameter measuring apparatus of the cylindrical body, respectively. (A), (B), (C) is explanatory drawing which shows the measurement result of the barrel by the internal-diameter measurement method of the cylindrical body which concerns on one embodiment of this invention. (A), (B) is explanatory drawing of the measurement position of the internal diameter by the internal diameter measurement method of the cylindrical body, respectively, and explanatory drawing of the measurement position by a modification.

Explanation of symbols

10: barrel (cylindrical body), 11, 12: screw, 13-16: barrel segment, 17: inner wall, 18: frame main body, 19-22: front guide member, 23-26: rear guide member, 27: movement Body: 28: Measuring element, 29: Spindle, 30: Bracket, 31: Mounting member, 32-35: Rib material, 36: Connecting member, 37-40: Mounting member, 41: Female screw part (connecting mechanism), 42: Male thread portion, 43: operation rod (moving means), 44: positioning guide bar, 45: latching groove, 46: lower surface, 47: upward tip, 48: female thread portion, 49: male thread portion, 50: fixing bolt, 51 to 51 54: Dial gauge, 60: Inner diameter measuring device for cylindrical body

Claims (5)

A cylindrical body inner diameter measuring device that is inserted into a cylindrical body or a cylindrical body that is partially missing and measures the inner diameter of the cylindrical body,
A frame main body disposed in the cylindrical body with a gap from the inner wall of the cylindrical body, provided at the front side of the frame main body, and at least three radially arranged to move along the inner wall of the cylindrical body. A plurality of front guide members, and a movable body provided on the rear side of the frame main body, each including at least three rear guide members arranged in a radial manner to move along the inner wall of the cylindrical body,
Provided on both sides in the radial direction centering on the center position of the moving body in a cross section perpendicular to the traveling direction of the moving body, and constantly biased outward in the radial direction, the measurement object site on the inner wall of the cylindrical body A dial gauge pair having a spindle with which the probe contacts,
In addition, there are two pairs of dial gauges, and the two pairs of dial gauges are provided at different positions on a cross section perpendicular to the traveling direction of the movable body. . 2. The cylindrical body inner diameter measuring apparatus according to claim 1, wherein the two sets of dial gauge pairs are provided at a 90-degree crossing position with respect to the center of the movable body. apparatus. 3. The cylindrical inner diameter measuring device according to claim 1, wherein the front guide member and the rear guide member each include a rotation-free guide ball, and An inner diameter measuring device for a cylindrical body, wherein the inner diameter measuring device is arranged so as to be able to advance and retreat radially outward with respect to the center position of the frame body. The cylindrical body inner diameter measuring apparatus according to any one of claims 1 to 3, wherein a connecting mechanism for connecting a moving means for pulling or pushing the frame main body is provided at one of the front and rear of the frame main body. An apparatus for measuring an inner diameter of a cylindrical body, which is provided. A moving body that is inserted into a cylindrical body or a cylindrical body that is partially missing and moves along the inner wall of the cylindrical body is centered on the center position of the moving body in a cross section perpendicular to the traveling direction of the moving body. A pair of dial gauges, which are provided on both sides in the radial direction and are constantly urged outward in the radial direction and have spindles that contact the measurement target portion of the inner wall of the cylindrical body with the probe at the tip thereof, are orthogonal to the traveling direction of the moving body. Two sets are provided at different positions on the cross section, and the inner diameter of the cylindrical body is measured using the two pairs of dial gauge pairs,
The inner diameter at two crossover positions at 90 ° with respect to the center of the cylindrical body on the cross section perpendicular to the axial direction of the cylindrical body at one side end of the cylindrical body is set as a reference diameter by the measuring means. A reference diameter measuring process to be measured;
A zero value setting step of setting each of the two pairs of dial gauges to a zero value at the measurement position of the cylindrical body as the reference diameter;
The movable body moves along the axis of the cylindrical body without rotating in a cross section perpendicular to the axial direction of the cylindrical body, and the increase / decrease value with respect to the reference diameter is measured by the two pairs of dial gauges. An increase / decrease value measurement process,
A method of measuring an inner diameter of a cylindrical body, comprising: an actual inner diameter calculating step of obtaining an actual inner diameter of the cylindrical body by adding the increase / decrease value to the reference diameter.

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