Pipe butt welding jig

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 for butt welding of 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 5 of a clamp according to a known pipe fixing device D as shown in FIG. 11, it is clamped and set with an upper half 6 of the clamp. This setting is performed with both upper halves 6, 6 of the clamp 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 5 of the rear clamp, and arranging the positioning protrusion 92 to protrude into a space S (see FIG. 1) between holders 4A and 4B. Then, after the butt joint surface of one pipe placed on the inner surface of the cylinder of the semi-cylindrical receiving member 52 attached to the lower half 5 of the front holder 4A abuts against the vertical surface of the protrusion 92, the upper half 6 of the clamp is rotated about the hinge shaft 531, and the pipe is clamped and set between the lower half 5 of the clamp and the upper half 6 of the clamp. Next, the positioning jig 9 is removed, and the butt joint surface of the other pipe is made to abut against the butt joint 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 5 of the rear clamp. Subsequently, the upper half 6 of the rear clamp is rotated about the hinge shaft 531, and it is clamped and set between the lower half 5 of the clamp of the rear holder 4B and the upper half 6 of the clamp. Thus, the butt-jointed two pipes 3, 3 are clamped and set by the holders 4A, 4B as shown in FIG. 8 (ii), 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, and butt welding of the pipes 3, 3 is performed. Regarding the positioning jig 9 used for such butt welding of pipes, improved inventions have also been proposed (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003] [Patent Document 1] Japanese Patent Publication No. 2005-34894

[0004] Patent Document 1 describes an invention for a positioning jig for butt welding of pipes, which employs a configuration in which a shaft portion with a positioning portion at its tip is clamped by a pipe fixing cassette (referred to as pipe fixing device D in this application), making it easy to determine the abutting position when setting up pipes even in poor working environments such as when the pipes themselves are pulled out at an angle. [Overview of the project] [Problems that the invention aims to solve]

[0005] However, in fusion welding, such as TIG welding of stainless steel pipes, where the joint melts due to heat, it is necessary to check whether the butt joint of the pipes is centered during welding, but this check is difficult. In butt welding such as TIG welding, the original joint position after welding cannot be seen from the surface of the pipe. In addition, many pipes in semiconductor manufacturing plants have an outer diameter of about 15 mm, and the condition of the inside of the pipe cannot be checked without cutting it open. Checking the welding condition of the butt joint from the inside of the pipe without cutting it open is extremely difficult. If the butt joint is misaligned with the center of the weld bead width, the welding will be insufficient, causing problems. It is essential to verify that the weld bead center aligns with the butt joint, but this verification is impossible with Patent Document 1 or conventional positioning jigs 9. Ultimately, this is done using calipers or a scale from the pipe surface, but this is not only time-consuming but also prone to misreading the scale. Furthermore, while the width of the weld bead may be specified according to customer specifications, measuring the bead width after welding was not possible using Patent Document 1 or conventional jigs. Furthermore, in the conventional positioning jig 9, the width α of the top plate portion 91 is smaller than the recessed top opening length β (Figure 11). With the top plate portion 91 placed on the upper end surface 522 of the semi-cylindrical receiving member 52, a pipe is set so that the abutting 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 body 51 with set screws 521, the positioning jig 9 will wobble, causing misalignment and making welding defects more likely.

[0006] The present invention aims to solve the above problems by providing a jig for butt welding pipes that ensures accurate centering of the butt joint surface of pipes during butt welding and allows for quick confirmation of the quality of the weld after welding. [Disclosure of the Invention] [Means for solving the problem]

[0007] To achieve the above objective, a first aspect of the present invention is a pipe butt welding jig used in a pipe fixing device in which a recess is provided on the flat, thick upper surface of a plate-shaped body relating to the lower half of an upright clamp, and a pair of holders that clamp a pipe placed on a receiving member attached to the recess are integrated with the upper half of the clamp, with a spacer sandwiched at the lower part of the lower half of the clamp, and the jig is a rectangular plate-shaped body in plan view, with the longitudinal lateral length of the base plate portion having a flat lower surface being equal to the upper opening length of the recess The pipe butt welding jig is characterized by having a longer base plate portion, with a vertical plate portion erected in an L-shape in a side view relative to the base plate portion, wherein the thickness of the plate portion from one side to the other in the shorter direction of the horizontally arranged base plate portion is 1 / 2 of the horizontal length, and a mark is provided at the center point along the longitudinal side edge of the lower surface of the base plate portion. A second aspect of the present invention, a pipe butt welding jig, is characterized in that, in the first aspect, a V-shaped groove perpendicular to the inner vertical plate surface of the vertical plate portion is formed in the upper surface of the base plate portion, recessing it and extending from the inner corner point to the other side of the base plate portion in a cross-sectional shape equal to the groove direction. A third aspect of the present invention, a pipe butt welding jig, is characterized in that, in the first or second aspect, a ruler-like scale is provided along the short-side edge of the lower surface of the base plate portion. [Effects of the Invention]

[0008] The pipe butt welding jig of the present invention stably places the base plate on the lower half of the clamp to minimize welding defects, and after welding, it is possible to quickly determine whether the welding was performed centered on the butt joint of both pipes using this jig. Furthermore, by adding a scale to the jig, the width of the weld bead can also be measured, providing significant advantages. [Brief explanation of the drawing]

[0009] [Figure 1] This is a perspective view of one embodiment of the pipe butt welding jig of the present invention, in which a pipe is set by butting it against the welding jig placed on the lower half of the clamp on the front side. [Figure 2] (a) is a front view of a pipe butt welding jig, (b) is a top view thereof, and (c) is a left side view thereof. [Figure 3] (a) is a front view of a pipe butt welding jig, and (b) is a rear view thereof. [Figure 4] Figure 2(b) is a plan view illustrating the process of marking pipes set in a pipe butt welding jig. [Figure 5] Figure 4 is a front view. [Figure 6] This is a side view of the main part showing how the pipe butt welding jig is placed on the lower half of the clamp on the front side of Figure 1. [Figure 7] (a) is a view taken along the line VII-VII in Figure 6, (b) is a cross-sectional view in which one pipe is butted against the pipe butt welding jig in (a) and placed on the lower half of the left clamp, and (c) is a cross-sectional view in which the pipe is clamped by the right holder from the state in (b). [Figure 8] (ii) is a cross-sectional view after removing the pipe butt welding jig shown in Figure 7(iii) and setting the butt joint surface of one pipe against the butt joint surface of the other pipe, and (v) is a cross-sectional view after welding has been performed on the butt joint surfaces of both pipes after (ii). [Figure 9] This is an explanatory plan view showing how to examine the butt joint surface of two pipes after welding. [Figure 10] This is an explanatory plan view showing how to check the weld bead width of two pipes after welding. [Figure 11] This is a descriptive perspective of conventional technology. [Modes for carrying out the invention]

[0010] The following describes in detail the pipe butt welding jig (hereinafter also simply referred to as "welding jig") according to the present invention. Figures 1 to 10 show one embodiment of the welding jig of the present invention. Figure 1 is a perspective view in which a pipe is set against the welding jig placed on the lower half of the front clamp. Figure 2 shows (a) a front view of the welding jig, (b) a plan view thereof, and (c) a left side view thereof. Figure 3 shows (a) a front view of the welding jig and (b) a rear view thereof. Figure 4 is a plan view of marking the piping in Figure 2 (b). Figure 5 is a front view of Figure 4. Figure 6 is a side view in which the welding jig is placed on the lower half of the front clamp in Figure 1. Figure 7 shows (a) a cross-sectional view in which the piping fixing device is located along the VII-VII line in Figure 6, with the main part of the piping fixing device included. (b) is a cross-sectional view in which a pipe is set against the welding jig in (a) and placed on the lower half of the right clamp. (c) is a cross-sectional view in which the pipe is clamped between the lower half and upper half of the right clamp from the state in (b). Figure 8 shows a cross-sectional view where (d) is the joint of one pipe after removing the welding jig shown in Figure 7(c), with the butt joint of the other pipe placed against the butt joint of the first pipe and set on the lower half of the left clamp, and (e) is a cross-sectional view after welding has been performed on the butt joints of both pipes following (d). Figure 9 is a plan view showing the appearance of the butt joints of the two pipes after welding, and Figure 10 is a plan view showing the width of the weld bead after butt welding the two pipes. For clarity, each figure highlights key parts, and the V-shaped groove is omitted in Figure 3(b). Also, parts not directly related to the present invention are omitted.

[0011] The pipe butt welding jig T is a jig that can center the butt joint portion 31 of the pipe 3 to be welded, which is clamped by the pipe fixing device D (a in FIG. 7), and by marking using this jig, the butt joint center position of both pipes can be easily confirmed after welding, and further, the width 8R of the weld bead 8 can also be measured. Before explaining the welding jig T, first, the pipe fixing device D will be explained.

[0012] The pipe fixing device D is a known device as shown in FIGS. 1 and 11, in which 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. A pair of holders 4, 4 sandwich and hold the pipes 3, 3 respectively, and both pipes 3, 3 can be brought into a butted state (b in FIG. 8). The holder 4 has a lower clamp half 5 and an upper clamp half 6 connected via a hinge plate 53. A semi-circular recess 511 in a 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 upright lower clamp half 5. A semi-cylindrical receiving member 52, which is a collet half, is detachably attached to this recess 511 with a set screw 521 (see FIG. 11). After arranging the pipe 3 to be butt welded on the inner surface 523 of the semi-cylindrical receiving member 52, the upper clamp half 6 is rotated about the hinge axis 531 to clamp the pipe 3 with the lower clamp half 5. Recesses 611 and semi-cylindrical receiving members 62 are also provided at the parts of the upper clamp half 6 facing the recess 511 and the receiving member 52. By replacing the receiving members 52, 62, it is possible to cope with pipes 3 having different outer diameter sizes. The spacer 7 is sandwiched between the lower parts of both lower clamp halves 5, and the spacer 7 and the pair of holders 4, 4 are integrated by the 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 lower clamp 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 notch grooves.

[0013] The pipe fixing device D sandwiches the pipes 3, 3 with a pair of holders 4, 4 respectively, and the two pipes 3, 3 can be brought into butt joint state. Furthermore, by using this welding jig T, the center alignment of the butt joint portion 31 (strictly speaking, the butt joint surface) of the pipe 3 can be achieved. Stable center alignment can be achieved by arranging the butt joint 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 so that the center position (center) of the distance W between the holders becomes the butt joint surface 31 of the pipe 3 as shown in Fig. 8 (b). Not only that, if the marking trace 35 is applied in advance using this welding jig T, the above-mentioned center position corresponding to the butt joint 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 rectangular plate-shaped body in plan view as shown in Fig. 2 (b) having a base plate portion 1 and a standing plate portion 2 (Fig. 2, Fig. 3). The base plate portion 1 has a flat rectangular lower surface 1b, and its horizontal length in the longitudinal direction 1Lm, 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 exceeding the recess 511 (Fig. 1, Fig. 6). Specifically, the flat portions outside both 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 outside both 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] As shown in Figure 2(c), the upright plate portion 2 is a plate portion erected in an L-shape in a side view relative to the base plate portion 1 with its upper surface 1a facing upward. The plate thickness t2 of the upright plate portion 2 extending from one side 11 to the other side 12 in the shorter direction relative to the horizontally arranged base plate portion 1 is set to be half the distance W between the pair of holders. By setting the plate thickness t2 of the upright plate portion to half the distance W between the holders 4, 4, the outer upright plate surface 2d of the upright plate portion 2 can be positioned upright in the middle of the distance W between the holders. The flat portion on the upper surface 1a side of the base plate portion is placed on the flat plate thickness upper surface 51a of the lower half of the clamp portion 5 that extends beyond the receiving member 52 (Figures 1 and 6), and the upright plate portion 2 is directed downward and protrudes into the space S between the holders 4. Then, by bringing the inner surface 2c of the vertical plate portion 2 into contact with the opposing surface 51f of the lower half portion 5 of the clamp (the opposing surface with the other lower half portion of the clamp), the outer surface 2d of the vertical plate portion 2 will be positioned in the middle of the distance W between the holders, as shown in Figure 7.

[0016] Furthermore, in 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 1 / 2 of the horizontal length 1Lm of the base plate portion 1 (Figure 2). The length 1Ln plus the plate thickness t2 is the short side length (short edge length) of the base plate portion 1. In addition, a marker 15 is provided at the center point along the longitudinal side edge of the lower surface 1b of the base plate portion 1 (Figure 3). Here, the marker 15 at the center point is represented by a long line in the middle of the long side on the back side of the base plate portion 1, and short line marks for checking misalignment are provided at regular intervals on both sides of it. As shown in Figure 3(b), in order to improve usability, the marker 15 is formed on the side edge opposite to the longitudinal side edge where the upright plate portion 2 is located.

[0017] Furthermore, the welding jig T is provided with a ruler-like scale 16 in the central area along the short-side edge of the lower surface 1b of the base plate portion 1. The scale 16 is a straight ruler with millimeter-sized numerals, and as shown in Figure 3(b), it is marked in millimeter units up to 10 mm in the central area on the short side of the lower surface 1b of the base plate portion. In this embodiment, the ruler-like scale 16 and the mark 15 provided at the central point along the long side are engraved on the flat lower surface 2b of the metal welding jig T by scribing, but they may also be done by printing stickers or painting. Reference numeral 19 indicates a through-hole, which can be used to thread a string or other material through to prevent the item from falling or getting lost.

[0018] In addition, a V-shaped groove 14 perpendicular to the inner vertical plate surface 2c of the vertical plate section 2 is formed by recessing the flat upper surface 1a of the base plate section 1, so that the cross-sectional shape is the same in the direction of the groove from the inner corner point F to the other side 12 of the base plate section 1 (Figure 2). Reference numeral 141 indicates the bottom of the groove. By placing the abutting surface 31 of the pipe 3 to be butt-welded against the inner vertical plate surface 2c of the vertical plate section 2 and placing the pipe 3 on the V-shaped groove 14 as shown in Figures 4 and 5, the pipe 3 is supported by the two groove slopes 14e or groove edge 142 of the V-shaped groove 14. By providing the V-shaped groove 14, the pipe 3 can be precisely orthogonal to the inner vertical plate surface 2c, and a marking mark 35 can be easily made on the pipe 3 with a marker M on the other end surface 121 side (Figure 4). From the above configuration, the distance from the abutting surface 31 to the marking mark 35 is 1 / 2 of the horizontal length 1Lm of the base plate section 1. Thus, by butting the two pipes 3, 3 with marking marks 35 together as shown in Figure 8(d), the desired pipe butt welding jig T is formed such that the length from the point of the marking mark 35 on one pipe 3 to the point of the marking on the other pipe 3 is the length of the long side of the base plate 1, which is 1Lm, and the midpoint between the two marking marks 35 of the lengths of both pipes is the butt joint surface 31, 31 of the two pipes 3, 3.

[0019] Next, we will explain one method of using the pipe butt welding jig T from the preparation stage to after the welding is completed (Figures 1 to 11). First, prepare two pipes 3 to be butt-welded. Pipes 3 are small-diameter stainless steel pipes with an outer diameter of approximately 15 mm. Marking marks 35 are made on the outer surface 3a of both pipes 3, 3. Place the pipes 3 in the V-shaped groove 14 and, with the butt-joint surfaces 31 in contact with the inner vertical plate surface 2c, form the marking marks 35 as shown in Figure 4. The marking marks 35 can be easily formed by applying the tip of the marker M to the other end surface 121 of the base plate portion 1 that contacts the pipes 3. During the marking process described above, the abutting surface 31 is brought into contact with the inner vertical plate surface 2c. Therefore, if the abutting surface 31 is not formed on a cut surface perpendicular to the pipe axis, a gap will form between the abutting surface 31 and the inner vertical plate surface 2c. This allows for checking for such gaps (defects). Furthermore, simply placing the pipe 3 in the V-shaped groove 14 allows for checking whether the pipe 3 is straight and perpendicular to the inner vertical plate surface 2c, i.e., the opposing surface 51f of the lower half of the clamp 5 related to the holder 4.

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

[0021] Next, as shown in Figure 7(b), the abutting end surface 31 of one pipe 3 is brought into contact with the outer vertical plate surface 2d of the vertical plate portion 2 of the welding jig T, and the pipe 3 is placed on the inner surface 523 of the receiving member 52 of the lower half portion 5 of the clamp on the right side. Since the plate thickness t2 of the vertical plate portion 2 is half the distance W between the pair of holders, the abutting end surface 31 of the pipe 3 protruding from the plate-shaped body 51 of the lower half portion 5 of the right clamp is positioned in the middle of the distance W between the holders. The pipe 3 is now centered. Then, the open upper half portion 6 of the right clamp is closed, and the pipe 3 is clamped between it and the lower half portion 5 of the clamp (Figure 7(c)). The inner surface 623 of the cylindrical member 62 is in close contact with the pipe 3 which is resting on the inner surface 523 of the receiving member 52. The upper half of the clamp 6 is rotated around the hinge axis 531 to clamp the pipe 3 between the upper half and the lower half of the clamp 5. Then, the hook 651 of the swing hook member 65 is hooked onto the pin 55, thereby clamping and setting the pipe 3 in place in the right-side holder 4 in Figure 7 so that it does not move. Figure 1 is a perspective view showing the entire pipe fixing device D from Figure 7(c).

[0022] After that, the welding jig T is removed, and the abutting surface 31 of the other pipe 3 is brought into contact with the abutting surface 31 of the pipe 3 as shown in Figure 8(d), and the other pipe 3 is placed on the inner surface 523 of the receiving member 52 related to the lower half of the left clamp 5. Next, the upper half of the clamp 6 is rotated to clamp the pipe 3 with the lower half of the clamp 5, and the swing hook member 65 is hooked onto the pin 55, and the other pipe 3 is clamped and set so that the left holder 4 in Figure 8 does not move. Then, as shown by the white arrow in Figure 8(d), the head of a known circumferential welding machine (in this case, a Swagelok product) is introduced into the upper opening S between the pair of holders 4, 4 and TIG welding is performed.

[0023] After completing the TIG welding as shown in Figure 8(e), the integrated piece of both pipes 3,3, which has been butt-welded, is removed, and the welding jig T is used to check whether the welding was performed accurately. As shown in Figure 9, the ends of the long side edges of the welding jig T, which has a central point marker 15, are aligned with the markings 35 of the two butt-welded pipes 3,3. As previously described, the distance between the two markings 35,35 is set to match the long side length of the welding jig T, which is 1Lm. Therefore, if the ends of the long side of the welding jig T are aligned with the two markings 35,35 as shown in the figure, the intermediate point marker 15 placed in the middle should become the butt joint surface 31 (center position) before TIG welding. As shown in the figure, if the central point marker 15 engraved on the base plate 1 is located in the center of the width 8R of the weld bead 8, it is easy to confirm that this is the original butt joint surface 31 and that the TIG welding was performed correctly. If, for any reason, the center point marker 15 is off-center from the center of the width of the weld bead 8, it indicates that the TIG welding was not performed properly with the butt joint surface 31 in the center, even if the weld bead 8 has a good appearance. This indicates a welding defect.

[0024] Furthermore, there are cases where the width 8R of the weld bead 8 needs to be measured according to customer specifications. In such cases, the zero point of the scale 16 on the short side of the welding jig T is aligned with one end of the weld bead width 8R, by changing the orientation of the welding jig T as shown in Figures 9 to 10, and the bead width 8R is measured. The welding jig T is used to perform the measurement of the width 8R of the weld bead 8. The entire process, from ensuring proper centering of pipe 3 to the pipe fixing device D before welding, to checking the quality of the butt weld after the pipe butt welding is complete and measuring the weld bead width 8R, is performed using only one welding jig T.

[0025] As shown in Figures 1 and 7, the pipe butt welding jig T configured in this way can be stably attached and set on the lower half of the clamp 5 so that the butt surface 31 of the pipe 3 is in the middle of the distance W between the holders during pipe butt welding. In the conventional positioning jig 9 shown in Figure 11, the top plate 91 is placed on the upper end surface 522 of the receiving member 52 and the pipe 3 is set on the lower half of the clamp 5. If the receiving member 52 is not firmly fixed in the recess 511 with the set screw 521, the receiving member 52 and the top plate 91 will shift, causing problems in the formation of the weld bead 8. On the other hand, this welding jig T is not merely a configuration in which a vertical plate portion 2 with a plate thickness t2 that is half the distance W between a pair of holders is erected on the base plate portion 1 so that the butt joint surface 31 of the pipe 3 is in the middle of the distance W between the holders. The longitudinal lateral length 1Lm of the base plate portion 1 is set to be longer than the upper opening length β of the recess 511. Since the flat upper surface 1a portions of the base plate portion 1 located on both sides of the V-shaped groove 14 are placed on the flat upper surface 51a of the plate-shaped body 51 located on both sides of the recess 511, the welding jig T can be stably set on the lower half of the clamp 5 without being affected by the receiving member 52. This contributes to the formation of a good welding bead 8.

[0026] Furthermore, after the butt welding of the two pipes 3 is completed, the joint of the butt surface 31 is fused together, and the joint is not visible from the appearance of the weld bead 8. From the outside, it is impossible to tell whether the welding was performed accurately around the butt joint of both pipes 3, 3. Moreover, in the case of a small-diameter pipe 3 as in this embodiment, it is extremely difficult to check the welding condition at the butt joint from the inner surface 3b of the pipe. This welding jig T solves such problems as well. 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 a marker 15 is provided at the center point along the longitudinal side edge of the lower surface 1b of the base plate portion 1. With this configuration, if marking marks 35 are made on both pipes 3,3 with a marker M as shown in Figure 4, then by aligning both ends of the long side edge of the lower surface 1b of the base plate with the marking marks 35,35 of the integrated pipes 3,3 after butt welding, as shown in Figure 9, it is easy to check whether the marker 15 at the center point is located in the center of the width of the weld bead 8. If the marker 15 points to the center of the bead width 8R, it can be seen that the TIG welding was performed normally around the original butt surface 31. Furthermore, when forming the V-shaped groove 14 and making a marking mark 35 on the pipe 3 with the marker M, the pipe 3 is placed on the V-shaped groove 14, so the pipe 3 does not move. The marking mark 35 can be made in a precise position.

[0027] Furthermore, in a configuration like this welding jig T, where a ruler-like scale 16 is provided along the short-side edge of the lower surface 1b of the base plate portion 1, the width 8R of the weld bead 8 can be easily measured by aligning the zero point of the scale 16 with one end of the weld bead width 8R of the butt-welded pipe 3 (Figure 10). This allows for quick confirmation after butt welding whether the weld bead width 8R meets the customer's requirements.

[0028] After the butt welding of pipe 3 is completed, conventional positioning jigs 9 shown in Figure 11 and the positioning jig for butt welding of pipes described in Patent Document 1 could not be used to verify the quality of the welding, such as whether the welding was performed accurately at the butt joint of both pipes 3,3, nor could the weld bead width 8R be measured. However, this welding jig T can meet these requirements with just this one jig. It eliminates the burden on the worker of bringing tools to the butt welding site in addition to the positioning jig, such as tools to check whether the welding was done correctly at the pipe butt joint surface 31 and a ruler to measure the width 8R of the weld bead 8, as well as the burden of checking the butt joint position, which is time-consuming when using the above tools.

[0029] Thus, the present invention is a welding jig T that enables precise and stable setting of pipe 3 in pipe fixing device D, allowing butt welding of pipes 3, 3. Moreover, with this single jig, it is possible to smoothly confirm whether the width center of the weld bead 8 that appears on the outer surface 3a of the pipe after the butt welding is completed coincides with the butt surface 31 of pipe 3 at the time of welding, thereby enabling quality check of the pipe butt welding. In addition, the substitute scale 16 for a ruler provided on the lower surface 1b of the base plate 1 allows for the measurement of the width 8R of the weld bead 8, making it easy to meet customer requests for measurement of the bead width 8R. This exhibits various excellent effects and is extremely beneficial.

[0030] Furthermore, the present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the present invention depending on the purpose and application. The shape, size, number, material, etc. of the base plate portion 1, V-shaped groove 14, central point marker 15, scale 16, vertical plate portion 2, piping 3, marking marks 35, etc. can be appropriately selected according to the application. [Explanation of symbols]

[0031] 1. Base plate section 1b Bottom side 1Lm: Length in the longitudinal direction (horizontal length, long side length) 11 One side 12 Other side 14 V-shaped groove 15. Landmark at the center along the longitudinal edge (center marker, landmark) 16 divisions 2. Vertical board section 3 Piping 4 holders 5. Lower half of the clamp 51 Plate-shaped body 511 Dent 51a Flat plate top surface 52 Receiving member 6. Upper part of the clamp 7 Spacers D Piping fixing device F Inside corner point T-shaped 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 in a pipe fixing device, comprising a plate-shaped body with a recess on the flat, plate-thick upper surface of the lower half of the upright clamp, a pair of holders that clamp a pipe placed on a receiving member attached to the recess with the upper half of the clamp, and a spacer sandwiched at the lower part of the lower half of the clamp to form a single unit, A pipe butt welding jig characterized by having a rectangular plate-like body in plan view, with a base plate portion having a flat bottom surface and a longitudinal length set longer than the top opening length of the recess, and having a vertical plate portion erected in an L-shape in side view relative to the base plate portion, wherein the thickness of the plate portion extending from one side to the other in the short direction of the horizontally arranged base plate portion is half the distance between the pair of holders, and the length from the inner corner point between the vertical plate portion and the base plate portion to the other side of the base plate portion is half the longitudinal length, and further having a mark provided at the center point along the longitudinal side edge of the bottom surface of the base plate portion.

2. The pipe butt welding jig according to claim 1, wherein a V-shaped groove perpendicular to the inner surface of the vertical plate portion is formed in the upper surface of the base plate portion, recessing the base plate portion and extending from the inner corner point to the other side of the base plate portion in the same cross-sectional shape as the groove.

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

Images