Jig for butt-welding piping

Abstract

To provide a jig for butt-welding piping that can ensure centering of a butted surface of piping during butt-welding and further can quickly confirm whether quality of welding is good or not after the butt-welding.SOLUTION: A jig for butt-welding piping is used in a piping fixing device in which a dent 511 is formed on a flat upper surface with a plate thickness of a plate-like main body pertaining to a clamp lower half part 5 that stands and a pair of holders 4 that clamp piping 3 arranged on a receiving member 52 mounted on the dent together with a clamp upper half part 6 is integrated with each other across a spacer 7 at the lower part of the clamp lower half part, which is formed in a rectangular shape in a planar view. A lateral length 1 Lm in a longitudinal direction of a base plate part 1 is set to be longer than a length β of the opening on the upper surface of the dent, and a vertical plate part 2, in which a plate thickness t2 is equal to 1 / 2 of a distance W between the holders, which goes from one side 11 toward the other side 12 in a transverse direction pertaining to the base plate part is erected in an L-shape in a side view with respect to the base plate part 1, and a length 1Ln1 from an inner corner point F between the erected plate part and the base plate part to the other side 12 of the base plate part is set to be equal to 1 / 2 of the lateral length, and further a mark 15 is formed on a central point along a side edge in a longitudinal direction pertaining to the lower surface of the base plate part.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a pipe butt welding jig used when butt welding pipes (including fittings).

Background Art

[0002] In semiconductor manufacturing factories and the like, stainless steel pipes are used for fluid transfer, and butt welding of pipes is performed there. Butt welding is performed as follows, for example. First, after placing one pipe on a receiving member 52 attached to a recess 511 of a lower half clamp 5 of a known pipe fixing device D as shown in FIG. 11, it is sandwiched and set with an upper half clamp 6. This setting is done with both upper half clamps 6, 6 open, placing the top plate portion 91 of a known positioning jig 9 on the upper end surface 522 of a semi-cylindrical receiving member 52 attached to the lower half clamp 5 on the back side, and arranging the positioning protrusion 92 to protrude into a space S (see FIG. 1) between holders 4A and 4B. Then, after making the butt surface of one pipe placed on the inner surface of the cylinder of the semi-cylindrical receiving member 52 attached to the lower half clamp 5 of the front-side holder 4A abut against the vertical surface of the protrusion 92, the upper half clamp 6 is rotated about the hinge shaft 531 to sandwich and set the pipe between the lower half clamp 5 and the upper half clamp 6. Next, the positioning jig 9 is removed, and the butt surface of the other pipe is made to abut against the butt surface of the one pipe, and this other pipe is placed on the inner surface of the cylinder of the semi-cylindrical receiving member 52 attached to the lower half clamp 5 on the back side. Subsequently, the upper half clamp 6 on the back side is rotated about the hinge shaft 531 to sandwich and set it between the lower half clamp 5 of the back-side holder 4B and the upper half clamp 6. In this way, the butted two pipes 3, 3 are sandwiched and set by the holders 4A, 4B as shown in FIG. 8 (b), and then, a welding head (not shown) of a known circumferential welding machine is introduced into the upper surface opening space S between the pair of holders 4, 4 and rotated to perform butt welding of the pipes 3, 3. Regarding the positioning jig 9 used for such butt welding of pipes, an improved invention has also been proposed (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-34894

[0004] Patent Document 1 adopts a configuration in which a shaft portion provided with a positioning portion at the tip is clamped by a pipe fixing cassette (pipe fixing device D in the present application), and the pipe itself is pulled out in an inclined state. Even in a poor working environment such as this, it is an invention of a positioning jig for pipe butt welding that enables the butting position during pipe setting to be easily performed. [Summary of the Invention] [Problems to be Solved by the Invention]

[0005] However, in fusion welding where the joint melts due to heat from TIG welding or the like of stainless steel pipes, a check is made as to whether the butt surface, which is the joint of the pipes, is welded at the center position, but this check has become difficult. In butt welding such as TIG welding, the original joint position after welding cannot be seen from the appearance on the pipe surface side. Also, in semiconductor manufacturing factories and the like, there are many small-diameter pipes with an outer diameter of about 15 mmφ, and the condition of the inner surface of the pipe cannot be confirmed without breaking it. It is extremely difficult to confirm the welding condition at the butt surface from the inner surface of the pipe without breaking it. If by any chance the butt surface is displaced from the center position of the weld bead width, the welding will be insufficient and cause problems. It is essential to check the position of whether the bead center after welding is at the position of the butt surface, and this check is impossible with Patent Document 1 or the conventional positioning jig 9. Eventually, it is done from the pipe surface side using calipers and scales, but not only is it time-consuming, but there is also a problem that it is easy to misread the scale. Also, depending on the customer's specifications, etc., the width of the weld bead may be specified, but the measurement of the bead width after welding could not be done with Patent Document 1 or the conventional jig. Furthermore, in the conventional positioning jig 9, the width α of the top plate portion 91 is smaller than the length β of the recessed upper surface opening (FIG. 11). With the top plate portion 91 placed on the upper end surface 522 of the semi-cylindrical receiving member 52, one pipe is set so that the butting surface 31 of the pipe tip abuts against the vertical surface of the protruding portion 92. Therefore, if the receiving member 52 is not firmly fixed to the plate-shaped main body 51 with the set screw 521, the positioning jig 9 will wobble, causing misalignment and making it easy to cause poor welding.

[0006] The present invention solves the above problems and aims to provide a pipe butt welding jig that can surely center the butting surface of the pipe during butt welding and can quickly confirm the quality of the welding after welding.

Disclosure of the Invention

Means for Solving the Problems

[0007] To achieve the above object, a first aspect of the present invention is a pipe butt welding jig used in a pipe fixing device formed by integrally sandwiching a spacer at the lower part of a clamp lower half, with a pair of holders that sandwich a pipe arranged on a receiving member attached to a recess provided on the flat plate-thickness upper surface of a plate-shaped main body related to the standing clamp lower half. The jig is a plate-shaped body rectangular in plan view, with the horizontal length in the longitudinal direction of a base plate portion with a flat lower surface set longer than the length of the upper surface opening of the recess, and a standing plate portion with a plate thickness from one side to the other side in the short direction related to the horizontally arranged base plate portion being 1 / 2 of the distance between the pair of holders is erected in an L-shape in side view with respect to the base plate portion. Further, the length from the inner corner point of the standing plate portion and the base plate portion to the other side of the base plate portion is 1 / 2 of the horizontal length, and a mark is provided at the central point along the longitudinal side edge related to the lower surface of the base plate portion. The pipe butt welding jig according to the second aspect of the present invention is characterized in that, in the first aspect, the V-shaped groove orthogonal to the inner vertical surface of the vertical plate portion is formed in a constant cross-sectional shape in the groove direction from the inner corner point to the other side of the base plate portion by recessing the upper surface of the base plate portion. The pipe butt welding jig according to the third aspect of the present invention is characterized in that, in the first aspect or the second aspect, a substitute scale for a ruler is provided along the short-side edge on the lower surface of the base plate portion.

Effects of the Invention

[0008] The pipe butt welding jig of the present invention can not only place the base plate portion stably on the lower half of the clamp to minimize welding defects, and can quickly determine whether the welding was performed centered on the butting position of both pipes after welding by using this jig, but also has great effects such as being able to measure the width of the weld bead by providing a scale on the jig.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

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Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Best Mode for Carrying Out the Invention

[0010] Hereinafter, the pipe butt welding jig according to the present invention (hereinafter, also simply referred to as "welding jig") will be described in detail. Figs. 1 to 10 show one form of the welding jig of the present invention. Fig. 1 is a perspective view in which one pipe is abutted and set against the welding jig placed on the lower half of the front clamp. Fig. 2 shows (A) the front view of the welding jig, (B) its plan view, and (C) its left side view. Fig. 3 shows (A) the front view of the welding jig and (B) its rear view. Fig. 4 is a plan view for marking on the pipe of Fig. 2(B). Fig. 5 is the front view of Fig. 4. Fig. 6 is a side view in which the welding jig is placed on the lower half of the front clamp of Fig. 1. Fig. 7 shows (A) a cross-sectional view taken along the arrow VII-VII in Fig. 6, including the main part of the pipe fixing device, (B) a cross-sectional view in which one pipe is abutted against the welding jig of (A) and placed on the lower half of the right clamp, and (C) a cross-sectional view in which the pipe is clamped between the lower half and the upper half of the right clamp from the state of (B). Fig. 8 shows (D) a cross-sectional view in which, after removing the welding jig of Fig. 7(C), the butt surface of one pipe is set against the butt surface of the other pipe and placed on the lower half of the left clamp, and (E) a cross-sectional view in which welding is performed on the butt surfaces of both pipes after (D). Fig. 9 is a plan view for examining the state of the butt surfaces of two pipes after welding. Fig. 10 shows a plan view for examining the width of the weld bead obtained by butt welding two pipes after welding. For easy understanding, each figure emphasizes the main part. In Fig. 3(B), the illustration of the V-shaped groove is omitted. Also, parts not directly related to the present invention are omitted.

[0011] The pipe butt welding jig T is a jig that centers the butt joint portion 31 of the pipe 3 to be welded, which is clamped by the pipe fixing device D (b in Fig. 7), and enables easy confirmation of the butt joint center position of both pipes after welding by marking using this jig. Furthermore, it enables measurement of the width 8R of the weld bead 8. Prior to the description of the welding jig T, first, the pipe fixing device D will be described.

[0012] The pipe fixing device D is a known device as shown in Figs. 1 and 11, where a pair of holders 4, 4 sandwich a spacer 7 and are integrated. Similar devices are shown in Fig. 1 of Japanese Patent No. 2870544 and Fig. 1 of Japanese Patent No. 4737739. The pair of holders 4, 4 sandwich and hold the pipes 3, 3 respectively, and the two pipes 3, 3 can be butted (b in Fig. 8). The holder 4 has a clamp lower half 5 and a clamp upper half 6 connected via a hinge plate 53. A semi-circular recess 511 in side view as shown in Fig. 6 is provided on the flat upper surface 51a of the plate-shaped main body 51 that engages with the standing clamp lower half 5. A semi-cylindrical receiving member 52, which is a half of a collet, is detachably attached to this recess 511 with a set screw 521 (see Fig. 11). After placing the pipe 3 to be butt welded on the inner surface 523 of the semi-cylindrical receiving member 52, the clamp upper half 6 is rotated about the hinge shaft 531 to clamp the pipe 3 with the clamp lower half 5. Recesses 611 and semi-cylindrical receiving members 62 are also provided at the parts of the clamp upper half 6 facing the recess 511 and the receiving member 52. By replacing the receiving members 52, 62, it is possible to accommodate pipes 3 with different outer diameters. The spacer 7 is sandwiched between the lower parts of both clamp lower halves 5, and the spacer 7 and the pair of holders 4, 4 are integrated by a fixing pin 59 shown in Fig. 6 to form a pipe fixing device D with a space S for the distance W between the holders provided on the upper side as shown in Figs. 7 and 11. The distance between the opposing surfaces 51f, 51f of the plate-shaped main bodies 51, 51 that engage with the pair of clamp lower halves 5 is the distance W between the holders. In the figure, reference numeral 61 indicates the plate-shaped body of the upper half 6 of the clamp, and reference numeral 63 indicates the fixing pin of the hinge plate 53. Reference numeral 65 indicates the swing hook member, reference numeral 66 indicates the rotation pin of the swing hook member, reference numeral 67 indicates the outer lever of the swing hook member, reference numeral 55 indicates the pin for latching the swing hook member provided on the lower half 5 of the clamp, and reference numerals 51g and 61g indicate the notch grooves.

[0013] The pipe fixing device D sandwiches the pipes 3, 3 with a pair of holders 4, 4 respectively, enabling both pipes 3, 3 to be butted against each other. Furthermore, by using this welding jig T, the center of the butted portion 31 (strictly speaking, the butting surface) of the pipe 3 can be determined. A stable centering can be achieved by arranging the butting surface 31 of the pipe 3 at the center of the distance W between the pair of holders. This welding jig T is used to stably set the pipe 3 on the holder 4 such that the center position (the middle) of the distance W between the holders becomes the butting surface 31 of the pipe 3 as shown in Fig. 8(B). Moreover, if the marking trace 35 is applied in advance using this welding jig T, the center position corresponding to the butting surface 31 of the pipe 3 set before welding can be accurately and smoothly confirmed after welding, and in addition, the width measurement of the weld bead 8 can also be performed (details will be described later).

[0014] The welding jig T is a plate-like body in the shape of a rectangle in plan view as shown in Fig. 2(B), which comprises a base plate portion 1 and a standing plate portion 2 (Figs. 2 and 3). The base plate portion 1 has a flat lower surface 1b in the shape of a rectangle, and its horizontal length 1Lm in the longitudinal direction, that is, the length of the long side, is set to be longer than the upper surface opening length β of the recess 511 (see Fig. 11). By forming the base plate portion 1 with a length exceeding the recess 511, the base plate portion 1 can be placed on the flat plate-thickness upper surface 51a related to the lower half 5 of the clamp that exceeds the recess 511 (Figs. 1 and 6). Specifically, the flat portions on both outer sides of the V-shaped groove 14 described later on the upper surface 1a side of the base plate portion are placed on the flat plate-thickness upper surfaces 51a on both outer sides of the recess 511. Even if the receiving member 52 is loosened by the set screw 521 and rattles in the recess 511 of the holder 4, the base plate portion 1, that is, the welding jig T, can be stably set on the lower half 5 of the clamp without being affected by this.

[0015] The vertical plate portion 2 is a plate portion that stands upright in an L shape in side view with respect to the base plate portion 1 having the upper surface 1a facing upward, as shown in Fig. 2(C). And the plate thickness t2 of the vertical plate portion 2 extending from one side 11 to the other side 12 in the short side direction of the horizontally disposed base plate portion 1 is set to be 1 / 2 of the distance W between the pair of holders. By setting the plate thickness t2 of the vertical plate portion to 1 / 2 of the distance W between the holders 4, 4, the outer vertical plate surface 2d of the vertical plate portion 2 can be erected and disposed in the middle of the distance W between the holders. Place the flat portion on the upper surface 1a side of the base plate portion on the flat plate thickness upper surface 51a of the lower half portion 5 of the clamp beyond the receiving member 52 (Figs. 1 and 6), and project the vertical plate portion 2 downward into the space S between the holders 4. Then, if the inner vertical plate surface 2c of the vertical plate portion 2 is brought into contact with the opposing surface 51f of the lower half portion 5 of the clamp (the opposing surface with the other opposing lower half portion of the clamp), as shown in Fig. 7, the outer vertical plate surface 2d of the vertical plate portion 2 will be positioned in the middle of the distance W between the holders.

[0016] Also, for the welding jig T of the present invention, the length 1Ln1 from the inner corner point F between the vertical plate portion 2 and the base plate portion 1 to the other side 12 of the base plate portion 1 is set to be 1 / 2 of the horizontal length 1Lm of the base plate portion 1 (Fig. 2). The length obtained by adding the plate thickness t2 to the length 1Ln is the length 1Ln in the short side direction (short side length) of the base plate portion 1. In addition, a mark 15 is provided at the central point along the longitudinal side edge of the lower surface 1b of the base plate portion 1 (Fig. 3). Here, the mark 15 at the central point is represented by a long line serving as a mark in the middle of the long side on the back side of the base plate portion 1, and short line marks for checking displacement are provided at regular intervals on both sides thereof. As shown in Fig. 3(B), for better usability, the mark 15 is formed on the side edge opposite to the longitudinal side edge where the vertical plate portion 2 is located.

[0017] Furthermore, the welding jig T is provided with a substitute scale 16 for a ruler in the central region along the short side edge of the lower surface 1b of the base plate portion 1. The scale 16 with numbers in mm units of a straightedge is engraved in mm units up to 10 mm in the central region on the short side of the lower surface 1b of the base plate portion 1 as shown in Fig. 3(B). The substitute scale 16 for a ruler and the mark 15 provided at the central point along the long side in the present embodiment are engraved on the flat lower surface 2b of the metal welding jig T with a marking pen, but they may also be by means of a printed sticker, painting, etc. Symbol 19 is a through-hole, through which a cord or the like is passed to prevent dropping and loss.

[0018] In addition, a V-shaped groove 14 orthogonal to the inner vertical plate surface 2c of the vertical plate portion 2 is formed by recessing the flat upper surface 1a of the base plate portion 1 so as to have a constant cross-sectional shape in the groove direction from the inner corner point F to the other side 12 of the base plate portion 1 (FIG. 2). Reference numeral 141 indicates the groove bottom. If the butting surface 31 of the pipe 3 to be butt-welded is applied to the inner vertical plate surface 2c of the vertical plate portion 2 and the pipe 3 is placed on the V-shaped groove 14 as shown in FIGS. 4 and 5, the pipe 3 is supported by the two groove inclined surfaces 14e or groove edges 142 of the V-shaped groove 14. By providing the V-shaped groove 14, the pipe 3 can be accurately orthogonal to the inner vertical plate surface 2c, and a marking trace 35 can be easily attached to the pipe 3 with a marker M on the other side end surface 121 side (FIG. 4). From the above-described configuration, the distance from the butting surface 31 to the marking trace 35 becomes half of the horizontal length 1Lm of the base plate portion 1. Thus, when the two pipes 3, 3 with the marking traces 35 are butted as shown in FIG. 8(B), the length from the point of the marking trace 35 attached to one pipe 3 to the point where the other pipe 3 is marked is set as the long side length 1Lm of the base plate portion 1, and the midpoint (intermediate point) between the two marking traces 35 of the lengths of both pipes becomes the butting surfaces 31, 31 of the two pipes 3, 3, resulting in a desired jig T for pipe butt welding.

[0019] Next, a method of using the pipe butt welding jig T from the preparation stage of pipe butt welding to after the welding is completed will be described (FIGS. 1 to 11). First, two pipes 3 to be butt-welded are prepared. The pipe 3 is a small-diameter stainless steel pipe 3 with an outer diameter of about 15 mmφ. Marking traces 35 are attached to the outer peripheral surfaces 3a of both pipes 3, 3. The pipe 3 is placed on the V-shaped groove 14, and the butting surface 31 is applied to the inner vertical plate surface 2c to form a marking trace 35 as shown in FIG. 4. If marking is performed by applying the tip of the marker M to the other side end surface 121 of the base plate portion 1 in contact with the pipe 3, the marking trace 35 can be easily formed. When making the above-mentioned marking, since the butting surface 31 is applied to the inner vertical plate surface 2c, if the butting surface 31 is not formed on a cut surface orthogonal to the pipe axis direction, a gap will be formed between the butting surface 31 and the inner vertical plate surface 2c. It is also possible to check for such gaps (defects). Also, just by placing the pipe 3 on the V-shaped groove 14, it is possible to check whether the pipe 3 is straight and orthogonal to the opposing surface 51f of the lower half 5 of the clamp that engages with the inner vertical plate surface 2c, that is, the holder 4..

[0020] Next, in the state of FIG. 11 where the upper half 6 of the clamp of the pipe fixing device D is open, the base plate portion 1 is turned upside down, and the upper surface 1a side is applied to the flat plate thickness upper surfaces 51a on both sides extending from the recess 511 of the lower half 5 of the clamp located on the left side of FIG. 7(A), and the welding jig T is placed and set on the lower half 5 of the clamp (FIG. 6). The inner vertical plate surface 2c of the vertical plate portion 2 is brought into contact with the opposing surface 51f of the plate-like main body 51 that engages with the lower half 5 of the clamp as shown in FIG. 7(A).

[0021] Subsequently, as shown in FIG. 7(B), the tip butting surface 31 of one pipe 3 is abutted against the outer vertical plate surface 2d of the vertical plate portion 2 related to the welding jig T, and the pipe 3 is placed on the inner cylindrical surface 523 of the receiving member 52 that engages with the lower half 5 of the clamp on the right side. Since the plate thickness t2 of the vertical plate portion 2 is 1 / 2 of the distance W between the pair of holders, the tip butting surface 31 of the pipe 3 protruding from the plate-like main body 51 of the lower half 5 of the right clamp is arranged in the middle of the distance W between the holders. The centering of one pipe 3 is achieved. Then, the open upper half 6 of the right clamp is closed, and the pipe 3 is clamped between the lower half 5 of the clamp (FIG. 7(C)). The inner cylindrical surface 623 of the cylindrical member 62 is in close contact with the pipe 3 placed on the inner cylindrical surface 523 of the receiving member 52. After the upper half 6 of the clamp is rotated around the hinge shaft 531 and the pipe 3 is clamped between the lower half 5 of the clamp, the hook 651 of the swing hook member 65 is hooked on the pin 55, so that the pipe 3 is clamped and set so as not to move to the right holder 4 in FIG. 7. When FIG. 7(C) is shown as a perspective view in which the entire pipe fixing device D is drawn, it becomes FIG. 1.

[0022] After that, remove the welding jig T, align the butting surface 31 of the pipe 3 with the butting surface 31 at the tip of the other pipe 3 as shown in Fig. 8(B), and place the other pipe 3 on the inner cylindrical surface 523 of the receiving member 52 engaged with the lower half 5 of the left clamp. Subsequently, rotate the upper half 6 of the clamp to sandwich the pipe 3 with the lower half 5 of the clamp, then hook the swinging hook member 65 onto the pin 55, and clamp and set the other pipe 3 so that the left holder 4 in Fig. 8 does not move. Then, as shown by the white arrow in Fig. 8(B), introduce the head of a known circumferential welding machine (here, a product of Swage Lock Co., Ltd.) into the upper opening space S between the pair of holders 4, 4 and perform TIG welding.

[0023] After the TIG welding in Fig. 8(C) is completed, take out the integrated product of the two pipes 3, 3 after butt welding, and also check whether the welding was performed accurately using this welding jig T. As shown in Fig. 9, align the two ends of the long side edge of the welding jig T with the marking traces 35 of the two butt-welded pipes 3, 3 where there is the central point mark 15. The distance between the two marking traces 35, 35 is made to match the long side length 1Lm of the welding jig T as described above. Therefore, if the two ends of the long side of the welding jig T are aligned with the two marking traces 35, 35 as shown in the figure, the mark 15 at the intermediate point provided in the middle should be the butting surface 31 (center position) before TIG welding. As shown in the figure, if the mark 15 at the central point engraved on the base plate portion 1 is located at the center of the width 8R of the weld bead 8, it can be easily confirmed that this is the original butting surface 31 and that the TIG welding was performed normally. In case the mark 15 at the central point is displaced from the center of the width of the weld bead 8, even if the weld bead 8 has a good appearance, it indicates that the TIG welding was not performed normally with the butting surface 31 in the middle, which tells us that there is a welding defect.

[0024] In addition, there is a case where the width 8R of the welding bead 8 is measured according to customer specifications or the like. In such a case, the zero point of the scale 16 provided on the short side of the welding jig T is aligned with one end side of the bead width 8R of the welding, and the direction of the welding jig T is changed as shown in FIGS. 9 to 10 to measure the bead width 8R. The measurement operation of the width 8R of the welding bead 8 is also performed using the welding jig T. Not only is it possible to properly center the pipe 3 on the pipe fixing device D before pipe welding, but also a series of operations such as checking the quality of the butt welding state after finishing the pipe butt welding and measuring the width 8R of the welding bead are carried out using only one of the welding jigs T.

[0025] The pipe butt welding jig T configured in this way can be stably attached and set to the lower half 5 of the clamp so that the butting surface 31 of the pipe 3 is in the middle of the holder distance W during pipe butt welding as shown in FIGS. 1 and 7. In the conventional positioning jig 9 shown in FIG. 11, the top plate portion 91 is placed on the upper end surface 522 of the receiving member 52 to set the pipe 3 to the lower half 5 of the clamp. Therefore, if the receiving member 52 is not firmly fixed to the recess 511 with the set screw 521, the receiving member 52 and the top plate portion 91 are displaced, resulting in problems in the formation of the welding bead 8. On the other hand, the welding jig T is not limited to the configuration in which the vertical plate portion 2 with a plate thickness t2 equal to 1 / 2 of the distance W between the pair of holders is erected on the base plate portion 1 so that the butting surface 31 of the pipe 3 is in the middle of the holder distance W. The horizontal length 1Lm in the longitudinal direction of the base plate portion 1 is set to be longer than the upper surface opening length β of the recess 511. The flat upper surface 1a of the base plate portion 1 outside both sides of the V-shaped groove 14 is placed on the flat plate thickness upper surface 51a related to the plate-like main body 51 on both outer sides of the recess 511, so that the welding jig T can be stably set to the lower half 5 of the clamp without being affected by the receiving member 52. This contributes to the formation of a good welding bead 8.

[0026] Also, after the butt welding of the two pipes 3 is completed, the joints of the butting surfaces 31 are melted in, and the joints cannot be seen from the appearance of the weld bead 8. Visually, it is impossible to tell whether the welding was performed accurately centered on the butting position of the two pipes 3, 3. Moreover, in the case of the small-diameter pipe 3 as in this embodiment, it is extremely difficult to examine the welding condition at the butting position from the inner surface 3b of the pipe. Such a problem is also solved by this welding jig T. The length 1Ln1 from the inner corner point F to the other side 12 of the base plate portion 1 is set to 1 / 2 of the horizontal length 1Lm of the base plate portion 1, and further, a mark 15 is provided at the central point along the longitudinal side edge related to the lower surface 1b of the base plate portion 1. With such a configuration, if the marking traces 35 are marked on both pipes 3, 3 with the marker M as shown in FIG. 4, by aligning both ends of the side edges on the long side of the lower surface 1b of the base plate with the marking traces 35, 35 of the integrated product of the two pipes 3, 3 after butt welding as shown in FIG. 9, it can be easily confirmed whether the mark 15 at the central point is located at the center of the width of the weld bead 8. If the mark 15 points to the center of the bead width 8R, it can be determined that the TIG welding was performed normally centered on the original butting surface 31. Moreover, when forming the V-shaped groove 14 and attaching the marking trace 35 to the pipe 3 with the marker M, since the pipe 3 is placed on the V-shaped groove 14, the pipe 3 does not move. The marking trace 35 can be attached at an accurate position.

[0027] Furthermore, in the case of this welding jig T, if a substitute scale 16 for a ruler is provided along the short-side edge related to the lower surface 1b of the base plate portion 1, by aligning the zero point of the scale 16 with one end side of the weld bead width 8R related to the butt-welded pipe 3 (FIG. 10), the width 8R of the weld bead 8 can be easily measured. Whether the weld bead width 8R meets the customer's requirements can be quickly confirmed after butt welding.

[0028] After finishing the butt welding of the pipe 3, in the conventional positioning jig 9 shown in Fig. 11 and the positioning jig for pipe butt welding of Patent Document 1, quality confirmation such as whether the welding was accurately performed at the butt position of both pipes 3, 3 and measurement of the weld bead width 8R could not be carried out. However, this welding jig T can meet these requirements with just this one jig. In addition to the positioning jig, the burden on the operator of bringing to the butt welding site tools for checking whether the welding was correctly performed at the pipe butt joint surface 31 and a ruler for measuring the width 8R of the weld bead 8, and the burden of checking the butt position which is time-consuming when using the above tools are not imposed on the operator.

[0029] Thus, the present invention is not only a welding jig T that enables accurate and stable setting of the pipe 3 in the pipe fixing device D and butt welding of the pipes 3, 3, but also with just this one jig, after completion of the butt welding, it is possible to smoothly confirm whether the center of the width of the weld bead 8 appearing on the outer peripheral surface 3a of the pipe coincides with the butt joint surface 31 of the pipe 3 during welding, and quality check of the pipe butt welding can be performed. In addition, the width 8R of the weld bead 8 can be measured by the substitute scale 16 provided on the lower surface 1b of the base plate portion 1, and various excellent effects are exhibited such as easily responding to the measurement requirements from customers and the like for the bead width 8R, which is extremely beneficial.

[0030] Note that the present invention is not limited to that shown in the above embodiment, and various modifications can be made within the scope of the present invention according to the purpose and application. The shapes, sizes, numbers, materials, etc. of the base plate portion 1, V-shaped groove 14, mark 15 at the central point, scale 16, standing plate portion 2, pipe 3, marking trace 35, etc. can be appropriately selected according to the application.

Explanation of Reference Numerals

[0031] 1 Base plate portion 1b Lower surface 1Lm Lateral length in the longitudinal direction (lateral length, long side length) 11 One side 12 The other side 14 V-shaped groove 15 Mark at the central point along the longitudinal side edge (central point mark, mark) 16 graduations 2 vertical plate parts 3 piping 4 holder 5 lower half of clamp 51 plate-shaped body 511 recess 51a flat upper surface of plate thickness 52 receiving member 6 upper half of clamp 7 spacer D pipe fixing device F inner corner point T jig for butt welding of pipes (welding jig) W distance between a pair of holders t2 plate thickness β upper surface opening length of recess

Claims

1. A pipe butt welding jig used for a pipe fixing device formed by integrating a pair of holders that sandwich a pipe arranged on a receiving member attached to a recess provided on a flat upper surface of a plate-shaped main body related to a lower half of a clamp that stands up. The pair of holders sandwich the spacer at the lower part of the lower half of the clamp. The jig is characterized in that: It is a plate-like body rectangular in plan view. The horizontal length in the longitudinal direction of a base plate portion with a flat lower surface is set to be longer than the upper surface opening length of the recess. A standing plate portion is erected in an L-shape in side view with respect to the base plate portion, where the plate thickness from one side to the other side in the short direction related to the horizontally arranged base plate portion becomes 1 / 2 of the distance between the pair of holders. The length from the inner corner point between the standing plate portion and the base plate portion to the other side of the base plate portion is set to 1 / 2 of the horizontal length. Further, a mark is provided at the central point along the longitudinal side edge related to the lower surface of the base plate portion. The pipe butt welding jig is characterized by the above features.

2. The pipe butt welding jig according to Claim 1, wherein a V-shaped groove orthogonal to the inner standing plate surface of the standing plate portion is formed by depressing the upper surface of the base plate portion, and the groove has an equal cross-sectional shape in the groove direction from the inner corner point to the other side of the base plate portion.

3. The pipe butt welding jig according to Claim 1 or 2, wherein a substitute scale for a ruler is provided along the short side edge related to the lower surface of the base plate portion.

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