JP2007285467A - Pipe centering tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pipe centering tool contributing to centering and facilitation of measurement of the straight pipe length between joints, when piping a plurality of mutual pipes different in the pipe center by using the joint (an elbow) and a straight pipe. <P>SOLUTION: A first head part 1 and a second head part 4 are respectively arranged to be detachably out-fittable with a pipe joint. These first head part 1 and second head part 4 are connected by an expansion shaft 7 constituted so as to be freely expandable and holdable in an optional expansion position. When rotatably constituting this expansion shaft 7 around its axis, centering can also be performed in response to various pipes. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  In the present invention, when connecting pipes with a straight pipe through a joint (also referred to as “elbow”) between a plurality of pipes having different pipe cores, the pipe can be easily centered, and the length of the straight pipe between the joints The present invention relates to a pipe centering tool for facilitating and speeding up measurement.

  As shown in FIG. 9, conventionally, two parallel straight pipes (pipes) 50 and 51 having different pipe cores are connected using two 45 ° elbows 52 and 53 in a pipe such as a vinyl chloride pipe. There are many situations. FIG. 9 shows, for example, a pipe in a newly built house or a building, and a water supply pipe or a drain pipe through an opening 56 opened to the floor 55 at a position shifted from the existing straight pipe 50 and the pipe core by a distance D from the foundation 54. This shows a case where the straight pipe 51 is to be piped through the intermediate straight pipe 57.

  For example, in the case of a vinyl chloride pipe joint, once the adhesive is applied and the ends of the straight pipe 57 are inserted and connected to each other, for example, elbows 52 and 53 (that is, after both are bonded and integrated) ) The straight pipe 57 cannot be removed from the elbows 52 and 53.

  Therefore, it is necessary to calculate the exact pipe dimension L of the straight pipe (intermediate straight pipe) 57 connecting the elbows 52 and 53 at both ends at the piping work site. If the length of the intermediate straight pipe 57 is inaccurate, accurate centering cannot be performed, and the pipe 51 cannot be raised to a desired position.

  As a method for calculating the pipe size of the intermediate straight pipe 57, two methods have been conventionally employed. One of them is first between two parallel straight pipes 50 and 51 (since the straight pipe 51 is piped after that in the actual piping process, it is between the core C of the opening 56 of the floor 55). Measure the center misalignment amount D of this, calculate the dimension L1 between the joints 52 and 53 using a mathematical formula of an isosceles right triangle, and subtract the d2 dimension ahead of the pipe insertion allowance from the joint core from the dimension L1. Then, the intermediate straight pipe length L (L0-2d2) is obtained.

  In the second method, the pipe is first cut into rough dimensions to form the intermediate straight pipe 57, and the intermediate straight pipe 57 and the joints 52 and 53 are temporarily assembled on site to measure the exact dimensions. It is a method.

Many jigs have been proposed for large-diameter pipes that enable centering between pipes (see Patent Documents 1 and 2, for example). No jigs that can be measured have been proposed.
JP-A-9-174287 JP-A-11-351449

  However, in the first method, not only does the calculation formula take time, but a calculation error causes waste of materials and labor. Although this is a calculation error, the L1 dimension can be obtained by calculation, but d2 cannot be obtained by calculation, and it is necessary to measure d2 in the field, which is not easy in practice and often causes an error. This is because there is one cause. This is because the measurement starting points 52a and 53a of the elbows 52 and 53 are not clearly shown on the surface of the elbow, and therefore cannot be accurately specified unless they are very skilled craftsmen. If it is an unfamiliar craftsman, there is a high possibility that an error will occur in this dimension d2. Therefore, if an error occurs in the dimension measurement of d2, an error also occurs in the intermediate straight pipe length L. For example, when the intermediate straight pipe 57 is short, a concave portion 58 is formed between the tip of the intermediate straight pipe 57 and the inner surface of the elbow 53, and dust and dirt accumulate in the concave portion 58, which grows for a long time. Ultimately, the problem of clogging the inside of the pipe has actually occurred.

  In the second method, there was a problem of labor and material waste of cutting the tube twice.

  In addition, the place where the pipe construction as described above is not always a good work environment, and the situation where the above work must be performed under a narrow work environment such as between the foundation and the floor is taken into consideration. In this case, the above measurement cannot be performed with high accuracy. This has hindered rapid piping construction work.

  Accordingly, an object of the present invention is to contribute to facilitating the measurement of the centering and the straight pipe length between joints when piping between a plurality of pipes having different pipe cores using a joint (elbow) and a straight pipe. It is to provide a centering tool.

  A pipe centering tool according to the present invention for solving the above-described problems is provided with a first head and a second head, respectively, to which a pipe joint (elbow) can be detachably fitted, and the first head and the first head. The two heads are connected to each other by an expansion / contraction shaft configured to be extendable and holdable at an arbitrary expansion / contraction position.

  According to this configuration, when connecting two parallel pipes having different pipe cores using two joints, first, one end of the pipe centering tool is inserted into one pipe via the pipe joint (connection). In addition, by inserting the other end into the pipe joint and then extending or shortening the telescopic shaft, it is possible to easily match the other pipe core and at the same time easily measure the accurate pipe dimensions.

  In the above configuration, if the telescopic shaft is configured to be rotatable about its axis, the pipe joint of the two pipes is displaced by hand, and the pipe fitting that is externally fitted can be manually handled even in complicated cases such as not parallel. As a result of being able to grasp and rotate, the angle adjustment with the existing pipe or the pipe piped thereafter can be easily performed.

  The telescopic shaft is formed by inserting and polymerizing a plurality of inner shafts and outer shafts having different diameters in the axial direction, and a reduced diameter portion to be slidably contacted with the outer peripheral surface of the inner shaft is formed near the end of the outer shaft. Preferably formed. Then, when the inner shaft is moved relative to the outer shaft, that is, when the telescopic shaft is expanded or contracted, the sliding when the reduced diameter portion formed on the outer shaft slides on the outer peripheral surface of the inner shaft. As a result of the resistance, the expansion and contraction shaft as a whole can be expanded and contracted without any looseness (expansion and contraction without mutual displacement between the inner and outer shafts of the joint), and can be held at any position at the same time. As a result, this contributes to accurate dimension measurement of an intermediate straight pipe (intermediate straight pipe) to be connected between the joints.

  Furthermore, in any one of the above-described configurations, a pipe centering tool formed by integrally attaching a distance measuring joint (elbow) to each of the first head and the second head may be used. This differs in that the pipe centering tool does not have a joint on the head, but in the case of the pipe centering tool of this configuration, a predetermined joint is fixed and integrated in advance on the head. However, in this case as well, it is used for the same use as the above-described pipe centering tool, and has the respective effects.

  According to the present invention, when two parallel pipes having different pipe cores are connected using two joints, the pipes can be easily aligned with existing pipes or pipes to be piped at the same time. It is possible to easily and accurately measure the pipe size of the intermediate straight pipe that connects the two.

  As a result, if the pipe centering tool of the present invention is used, an accurate pipe dimension can be measured quickly and easily even if it is not a skilled craftsman, and it can contribute to a short construction period of piping work. As a result, it can greatly contribute to the prevention of waste materials caused by erroneous measurement.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First embodiment]
FIG. 1 shows a pipe centering tool A according to a first embodiment of the present invention, in which (a) is a perspective view (a state in which a telescopic shaft 7 is fully extended) and (b) is a longitudinal sectional view (a telescopic shaft). 7 is a state in which the head 7 is slightly shortened, and only the heads at both ends are shown in cross-section), and (c) is a cross-sectional view (the state in which the telescopic shaft 7 is completely shortened and the heads at both ends are in contact with each other).

  As shown in FIGS. 1A to 1C, the pipe centering tool A includes a first head 1, a second head 4, and an expansion / contraction that connects the first head 1 and the second head 4. It is mainly composed of the shaft 7.

  2 (a) is an exploded perspective view of the pipe centering tool A, FIG. 2 (b) is an internal plan view of the first head 1 (a view taken along the arrow IIb-IIb in FIG. 2 (a)), and FIG. The perspective view of the telescopic shaft 7 in a state where the telescopic shaft 7 is somewhat extended, FIG. 4D is an internal plan view of the second head 4 (IId-IIb arrow view in FIG. 1A).

  As shown in these drawings, the first head 1 has an outer shape in which two large and small diameter cylinders are combined in two stages, and is placed on the first cylindrical portion 2 having a large diameter. The second cylindrical portion 3 having a small diameter is concentrically connected in a stepped manner. The internal space 8 of the first head 1 has a stepped space similar to the outer shape. A circular hole 9 into which one end of a telescopic shaft 7 described later is inserted is provided at the center of the top plate 3a of the second cylindrical portion 3, and an oval groove 10 is provided on the back surface of the top plate 3a so as to surround the circular hole 9. Is formed. The oval groove 10 is a recess for tightly fitting a first flange 11 formed near the end of the telescopic shaft 7 to be described later, and the shape thereof is a parallel surface 10a in which a pair of opposing surfaces are linear. The other pair of opposing surfaces are surrounded by an arcuate surface 10b. The first and second heads 1 and 4 may be made of any material other than a plastic material such as vinyl chloride as long as the same strength can be obtained.

  The second head 4 has substantially the same configuration as the first head 1. The difference between the first head 1 and the second head 4 is that the end on the large diameter side of the telescopic shaft 7 is engaged and connected to the first head 1, whereas the second head 4 is telescopic. It is a point which has the structure engaged and connected with the edge part by the side of the small diameter of the axis | shaft 7. FIG. In other words, the circular hole 12 at the center of the top plate 6a of the second cylindrical portion 6 of the second head 4 has an inner diameter through which the end of the thin telescopic shaft 7 can be inserted. And the recessed part by the oval groove 13 of the back surface of the top plate 6a is a point which has the form which fits and accommodates the 2nd collar part 14 of the similar shape smaller than the 1st collar part 11. FIG. The oval groove 13 is a recess for fitting a first flange 14 formed near the end of the telescopic shaft 7 to be described later, and the shape thereof is a parallel surface 13a in which a pair of opposing surfaces are linear and the like. The pair of opposed surfaces is surrounded by an arcuate surface 13b.

  The telescopic shaft 7 has a configuration similar to a rod antenna, and gradually decreases in diameter from the first head 1 to the second head 4 with several steps of diameter change. It is configured to be stretchable. The telescopic shaft 7 is rotatable about its own axis, and can be positioned by rotating an elbow attached to the head as will be described later.

  The aforementioned first flange 11 is formed near the end of the telescopic shaft 7 with the large diameter, and the tip of the first flange 11 is formed with a female thread 16 for screwing with the large-diameter bolt 15. Yes. A rod portion 17 extends from the female screw portion 16. As described above, the first flange 11 is formed of a pair of parallel surfaces 11a and a pair of arcuate surfaces 11b so as to fit into the oblong groove 10 exactly. The telescopic shaft 7 does not rotate as a whole when fitted into the. However, as described above, the telescopic shaft 7 itself has a multi-ply structure, so that it can rotate between the outer shaft and the inner shaft inserted therein. These points are the same in the case of the small second flange 14 provided on the small diameter side of the telescopic shaft 7. In other words, the oblong groove 10 (the oblong groove 13) and the first flange portion 11 (the second flange portion 14) serve to prevent the telescopic shaft 7 from rotating. A female screw portion 19 for being screwed onto the small diameter bolt 18 is also formed at the tip of the second flange portion 14. In the figure, reference numerals 15a and 18a denote spring washers for preventing bolts from loosening. The telescopic shaft 7 may be made of another metal as long as it is a material having high rigidity and high strength such as stainless steel, and may be made of plastic if equivalent rigidity and strength can be obtained.

  FIG. 3A is an enlarged view of a part of the telescopic shaft 7 extracted, and the left side from the axis C is shown as a longitudinal section. (B) is a sectional view taken along line IIIb-IIIb in (a), and (c) is a perspective view showing a procedure for attaching a sliding resistance material 24 to the lower end portion of a thin pipe (inner shaft) 7B. It is.

  The telescopic shaft 7 has a so-called multi-tube structure in which hollow pipes of different sizes are gradually inserted and polymerized in several stages, so that the inside of a thick hollow pipe (hereinafter referred to as “outer shaft”) 7A. A thin hollow pipe (hereinafter referred to as “inner shaft”) 7B is slidably inserted (inserted).

  A first reduced-diameter portion (throttle portion) 20 that is caulked around the entire circumference is formed at the distal end portion of the outer shaft 7A, and the second reduced-diameter portion 21 is located at a position away from the distal end by a certain distance. Is formed. In these first and second reduced diameter portions 20, 21, the inner surface of the outer shaft 7A is in sliding contact with the outer peripheral surface of the inner shaft 7B to induce sliding resistance. Furthermore, an end collar 22 is formed at the tip of the inner shaft 7B, and the outer peripheral edge of the end collar 22 is also in sliding contact with the inner surface of the outer shaft 7A, thereby adding sliding resistance. Therefore, the outer shaft 7A and the inner shaft 7B are in sliding contact with each other at three locations, the sliding resistance is increased, and a position holding function that can be held at an arbitrary expansion / contraction position is exhibited.

  A circular engagement hole 23 is formed near the end flange 22 of the inner shaft 7B. A rectangular sliding resistance material 24 locked in the engagement hole 23 is attached to the outer peripheral surface of the inner shaft 7B. That is, the sliding resistance material 24 is formed in a circular arc shape so as to be in contact with the peripheral surface of the inner shaft 7B, and has a circular protrusion 25 protruding inward in the vicinity of the end thereof. When the circular protrusion 25 of the sliding resistance material 24 is fitted into the engagement hole 23 provided in the lower end portion of the inner shaft 7B, the sliding resistance material 24 moves in the axial direction on the peripheral surface of the inner shaft 7B. It is locked in a restrained state. The sliding resistance material 24 is provided at opposing positions on both sides of the inner shaft 7B. However, in order to increase the sliding resistance, it is not limited to both sides, and three or four places on the peripheral surface may be provided.

  As can be seen from FIGS. 3A and 3B, the sliding resistance member 24 has an axial length extending from the end flange 22 provided at the tip of the inner shaft 7 </ b> B to the second reduced diameter portion 21. ing. When the inner shaft 7B is fully extended, the tip of the sliding resistance material 24 comes into contact with the second reduced diameter portion so that it cannot extend any further. That is, the second reduced diameter portion 21 and the sliding resistance member 24 work together as a stopper in the axial direction of the inner shaft 7B constituting a part of the telescopic shaft 7.

  The inner shaft 7B is configured such that the entire length of the telescopic shaft 7 is expanded and contracted while sliding in the outer shaft 7A. In this case, the inner shaft 7B is the first and second reduced diameter portions of the outer shaft 7A. 20 and 21 are supported in contact with each other, and as a result of their own end collar 22 being in contact with and supported by the inner surface of the outer shaft 7A, the inner shaft 7B is supported at three points. Is as described above. As a result of increasing the sliding resistance by such a configuration, a position holding function that can be held at any stretched position is exhibited.

  With the above-described configuration, the inner shaft 7B operates while being slidably supported by the outer shaft 7A during the expansion / contraction operation of the expansion / contraction shaft 7, so that there is no rattling, and thus the entire length of the expansion / contraction shaft 7 can be set to an arbitrary length. And can hold the position exactly. That is, the inner shaft 7B can be stopped at an arbitrary position due to the presence of sliding resistance. This has the significance of not causing a measurement error because the length of the telescopic shaft 7 does not change when measuring the length of the intermediate straight pipe described later.

  Further, even if the diameter of the telescopic shaft 7 is changed by several steps due to the presence of the sliding resistance, the shaft center O is kept in a consistent state without causing any runout. Thus, the telescopic shaft 7 can expand and contract against this sliding resistance, and rotates around the axis O (see FIG. 1 (b)) between the inner shaft 7B and the outer shaft 7A. It is possible. By such a function capable of rotation, the pipe can be easily centered by rotating the elbow (joint) 35 in accordance with the mating pipe position to be connected as shown in FIG.

  As shown in FIG. 4, the pipe centering tool A itself does not have a joint (elbow). However, in use, the first head 1 and the second head 4 at both ends have pipe joints ( Elbow) 35 can be externally fitted. That is, the first cylindrical portions 2 and 5 of the first and second heads 1 and 4 have an outer diameter that allows the pipe joint 35 to be fitted. In this case, as shown in FIG. 8A, if thin felt or rubber is wound around the peripheral surfaces of the first cylindrical portions 2 and 5, the inner surfaces of the pipe joints 34 and 35 and the outer peripheral surfaces of the cylindrical portions 2 and 5 Can be prevented from coming into direct sliding contact, and the pipe joints 34 and 35 can be removed relatively easily after the centering operation is completed. This is particularly significant when the pipes are all plastic pipes such as PVC pipes. That is, when the pipe joints 34 and 35 are crowned and pushed into the heads of the pipe centering tools, the inner surfaces of the pipe joints 34 and 35 are tapered, so that when both are plastic pipes, they are in a fixed state. Therefore, it is possible to remove the rubber relatively easily by interposing rubber between them.

  As shown in FIG. 1C, the pipe centering tool A having the above configuration can be carried in a compact form by shortening the telescopic shaft 7 when not in use. As in 1 (a) and 1 (b), it can be used for centering piping by measuring a predetermined amount, and for measuring the length of a straight pipe between joints.

  Hereinafter, an example of the usage mode of the pipe centering tool A according to the first embodiment of the present application described above will be described with reference to FIGS. An example of this use is when piping from the foundation 30 of the building or house to the floor 31, and as a typical example, two parallel pipes 32 and 33 having different pipe cores are connected to two 45 ° elbows 34 and 35. The case where it connects using is shown.

  FIG. 5A: The floor 31 is arranged at a position spaced apart from the foundation 30, and the existing straight pipe 32 projects from the foundation 30. The floor 31 is preliminarily provided with a straight pipe 33 that rises from this and an opening 36 having a slightly larger diameter. One end of a 45 ° elbow 34 is fitted into the existing straight pipe 32. And the pipe centering tool A concerning 1st Embodiment of this invention is prepared.

  FIG. 5B: Next, the first head 1 of the pipe centering tool A is fitted into the other end of the elbow 34, and the pipe centering tool A is mounted on the elbow 34.

  FIG. 5C: Thereafter, the 45 ° elbow 35 is also attached to the second head 4 of the pipe centering tool A, and the telescopic shaft is gradually extended toward the opening 36 of the floor 31.

  FIG. 5D: The telescopic shaft 7 is extended to a position where the axial core C1 of the elbow 35 coincides with the opening core C2 opened on the floor 31 by visual inspection. Stop stretching. FIG. 5D shows just this state. In this state, the distance L1 between the elbow ends is measured using a tape measure or the like. Since the insertion amount L2 is known from the pipe diameter, the required length L of the intermediate straight pipe 37 to be connected between the joints can be easily obtained by L = L1 + 2L2.

  FIG. 6 is a front view showing another usage mode of the pipe centering tool A. FIG. This example is a case where the pipe centering tool A is used for piping between the floor 31 and the wall 31A orthogonal to the floor 31, not the floor 31.

The point of use of the pipe centering tool A in this piping example is almost the same as that described above. However, at the position of the elbow 35 in FIG. 5D, the straight pipe 33A to be piped to the wall 31A orthogonal to the floor 31 is used. Since the elbow 35 cannot be brought to the position, the pipe core cannot be aligned. 5D, the elbow 35 is grasped by hand by the rotation function of the telescopic shaft 7, and the shaft core C1 of the elbow 35 and the opening core C2 of the opening 36A of the wall 31A (that is, the straight pipe 33A to be piped from now on). Rotate 180 ° to the point where it is estimated that it corresponds to the axis). Thereafter, the length L of the intermediate straight pipe 37A may be calculated by the same method as described in FIG. 5D.
[Second Embodiment]
FIG. 7 shows a pipe centering tool B according to the second embodiment. (A) is a perspective view of the state which extended the expansion-contraction shaft 7, (b) is a front view of the state which shortened completely.

  The difference from the first embodiment is that the pipe centering tool A itself of the first embodiment does not have a pipe joint at the head (it is mounted at the time of piping work), but the second embodiment. In the case of the form, joints (elbows) 34A and 35A for distance measurement are fixedly mounted in advance on both ends of the heads and integrated, and the whole thing shown in the drawing constitutes the pipe centering tool B. is there. The distance measuring joints (elbows) 34A and 35A are fixed to the head in advance with an adhesive and cannot be replaced with other elbows having different angles. Of course, it is not used for piping. The example shown in Fig. 7 is an example of a 45 ° elbow. If necessary, several types with elbows (11 °, 22 °, 30 °, 45 °, 60 °, 90 ° elbow) are available. It is necessary to keep.

  The excellent point of the second embodiment is derived from the fact that the distance measuring joints 34A and 35A are exclusive items of the pipe centering tool B. That is, as shown in FIG. 7A, distance measurement markings 34m and 35m are provided in advance over the entire circumference of the outer peripheral surface at a position corresponding to the insertion end of the distance measurement joints 34A and 35A (this) Is possible because it is an exclusive product), and by measuring the distance L between the marking 34m of the ranging joint 34A and the marking 35m of the ranging joint 35A, an intermediate straight pipe that is directly required without adding the insertion amount L2 The length of the pipe can be obtained, and the piping work is further speeded up.

  The method of using the pipe centering tool B according to the second embodiment is the same as that of the first embodiment. Therefore, the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  FIG. 8 shows a modification of the head. Since (a) is as described above, the description thereof is omitted here. (B) connects the 1st cylindrical part 2 (5) and the 2nd cylindrical part 3 (6) in (a) as the truncated cone shape 41. FIG.

  The outer diameter of the second cylindrical portion 3 (6) is made smaller than the outer diameter of the first cylindrical portion 2 (5) as shown in (a), or it is formed into a truncated cone shape 41 and tapered as shown in (b). The reason for this is to prevent the first cylindrical portion 2 (5) from hitting the inner surface of the distance measuring joint when the pipe or the distance measuring joint is fitted to the head. If there is no fear of hitting, as shown in (c), the first cylindrical portion and the second cylindrical portion in (a) may be connected with the same diameter (that is, the entire head is formed into a bottomed cylindrical shape 42). Just fine).

  The present invention is suitable for easily measuring the length of an intermediate straight pipe connecting between a plurality of pipes having different pipe cores, and is suitable for plastic pipes such as polyvinyl chloride pipes, metal pipes such as steel pipes and copper pipes. Can be used extensively for plumbing work.

The pipe centering tool concerning 1st Embodiment of this invention is shown, (a) is the perspective view (state in which the expansion-contraction axis was fully extended), (b) is a longitudinal cross-sectional view (state in which the expansion-contraction axis was shortened somewhat) (C) is a cross-sectional view (a state in which the telescopic shaft is completely shortened and the heads at both ends are in contact with each other). (A) is an exploded perspective view of a pipe centering tool, (b) is an internal plan view of the first head (IIb-IIb arrow view in (a)), and (c) in FIG. The perspective view of the expansion-contraction axis | shaft of the extended state, the figure (d) is an internal top view (IId-IId arrow line view in (a)) of a 2nd head. (A) is the figure which extracted and expanded a part of expansion-contraction axis | shaft, and the left side from the axial center line is shown with the longitudinal cross-section. (B) is a sectional view taken along line IIIb-IIIb in (a), and (c) is a perspective view showing a procedure for attaching a sliding resistance material to the lower end portion of a thin pipe (inner shaft). . It is a front view which shows the relationship between the piping centering tool and piping joint (elbow) concerning 1st Embodiment. It is the front view which showed an example of the usage condition of the piping centering tool of 1st Embodiment, and is the state figure which attached the piping joint to the existing straight pipe. It is the front view which showed an example of the usage condition of the piping centering tool of 1st Embodiment, and is a state figure which carried out fitting mounting of the piping centering tool to the piping joint. It is the front view which showed an example of the usage condition of the pipe centering tool of 1st Embodiment, and is a state figure which attaches a pipe joint to the other end of a pipe centering tool, and expands | extends an expansion-contraction shaft gradually. It is the front view which showed an example of the usage condition of the piping centering tool of 1st Embodiment, and is a state figure which extended the expansion-contraction axis to the place where the opening core of a floor, ie, a standing pipe, and the axial center of a piping joint correspond. It is the front view which showed another usage condition of the piping centering tool of 1st Embodiment. It is a pipe centering tool concerning 2nd Embodiment, (a) is a perspective view of a state when the expansion-contraction shaft has been extended. (B) is a front view of a state in which the telescopic shaft is completely shortened. The modification of the head of a piping centering tool is shown, (a) is a perspective view when winding prevention member is wound around the head cylindrical part peripheral surface. (B) is a perspective view when the head is formed in a truncated cone shape, and (c) is a perspective view when the head is formed in a cylindrical shape. It is a front view which shows the centering method in the conventional piping construction, and the measuring method of intermediate straight pipe length.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... 1st head 2 ... 1st cylindrical part 3 ... 2nd cylindrical part 4 ... 2nd head 5 ... 1st cylindrical part 6 ... 2nd cylindrical part 7 ... Telescopic shaft 7A ... Outer shaft 7B ... Inner shaft 11 ... 1st collar 14 ... 2nd collar 20, 21 ... Diameter reduction part 22 ... End collar 24 ... Sliding resistance material 34, 35 ... Piping joint 34A, 35A ... Ranging joint 34m, 35m ... (for ranging) marking

Claims (4)

A first and second heads on which the pipe joint can be detachably fitted are provided, and the first head and the second head can be extended and retracted, and can be held at an optional extension position. Pipe centering tool connected by a shaft. The pipe centering tool according to claim 1, wherein the telescopic shaft is configured to be rotatable about its axis. The telescopic shaft is formed by inserting and polymerizing a plurality of inner shafts and outer shafts having different diameters in the axial direction, and a reduced diameter portion to be slidably contacted with the outer peripheral surface of the inner shaft is formed near the end of the outer shaft. The pipe centering tool according to claim 1 or 2. The pipe centering tool according to any one of claims 1 to 3, wherein a distance measuring joint is fixedly attached to each of the first head and the second head.

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