JPH0415434Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a pipe welding fixture used for butt welding pipes such as air ducts.

[Prior Art] Conventionally, when such pipes are welded, a common method is to firmly fix the outside of the pipe with a clamp or the like. In that case, the jig will be large-scale, and it will take time to align the terminal and axis.
There were drawbacks such as difficulty in clamping if one pipe was short or bent, and the jig could get in the way during welding.

Therefore, in order to eliminate these drawbacks, a jig for centering and fixing the pipe from the inside has been devised and is commercially available.

[Problems to be solved by the invention] By the way, the commercially available jig has the following problems:
As shown in FIG. 10, by pulling the mandrel 22 in the center, the surrounding pieces 23 are attached to the pipes 21A, 2
It is pressed against the inner surface of 1B for centering and fixing.It is simple and can be centered and fixed in a short time, and there is no interference during welding. However, when butting together pipes with slightly different inner diameters, the pipe with the smaller inner diameter is fixed first, so the pipe with the larger inner diameter cannot be fixed firmly. There were problems such as the need to apply an external force in the direction.

[Means for solving the problem] The pipe welding fixing jig of the present invention was developed to solve the above problem, and has two conical inclined surfaces with different taper degrees on both sides of the outer periphery. a mandrel having an abacus bead shape, an inner surface having a conical surface corresponding to the conical inclined surface, and an outer surface having a cylindrical surface corresponding to the inner surface of the pipe, aligned with the corresponding conical inclined surface of the mandrel; two sets of piece groups each consisting of a plurality of segment-like pieces provided; a ring-shaped spring that engages each piece of each piece group to apply a force in a diametrical direction; and the mandrel. and a disc-shaped plate disposed on both sides of the piece group, and a nut that passes through the center hole of the mandrel and the plate and screws together, and connects the two sets of piece groups through the plates on both sides. It consists of a bolt that can be compressed from the outside.

[Function] The present invention has the above-mentioned configuration, and for biconical inclined surfaces with different taper degrees of the mandrel,
Since groups of pieces with corresponding inner surfaces are arranged opposite each other, when the bolt is tightened, the pieces on both sides are pressed through the plates on both sides, and the pieces on the slope side with a smaller degree of taper are pressed first. The pipe expands and fixes one pipe from the inside, and the piece on the slope side with the larger degree of taper expands later, tightening the other pipe from the inside while moving the other pipe in the direction of butt, and then tightening both pipes. It is fixed firmly, and even if there is a slight difference in the inner diameter of both pipes, there will be no problem, and the butt part will automatically be tightly fixed.

[Embodiment] The present invention will be explained based on the drawings. Fig. 1 is a longitudinal sectional front view showing an entire embodiment of the invention, and Fig. 2 is a longitudinal sectional front view showing an entire embodiment of the invention.
The figure is a partially cutaway side view.

Here, 1 is a mandrel, which has an abacus bead shape with two conical inclined surfaces 7A, 7B having different taper degrees on both sides of the outer circumference, and in this embodiment, inclined surfaces 7A, 7B.
The taper degrees are 45° and 30°, respectively, and the inclined surface 7
The boundary between A and 7B forms an annular top portion 11.
Furthermore, as shown in FIGS. 4 and 5, the mandrel 1 has a central hole 8 at the center, a hollow part 9 on the outer periphery of the central part, and a plurality of radial holes 1 extending from the hollow part 9 to the top 11 of the outer periphery.
It has 0. On the inclined surfaces 7A and 7B of the mandrel 1, two sets of pieces consisting of a plurality of segment-like pieces 2A and 2B having inner surfaces 12A and 12B forming conical surfaces respectively corresponding to the inclined surfaces are arranged. will be established. As shown in FIGS. 7 and 8, each piece 2A, 2B has a protruding edge 14 on its outer periphery, and the outer cylindrical surface of the protruding edge forms an outer surface 13 that contacts the pipes 21A, 21B. The taper degrees of the inner surfaces 12A and 12B are set to 45° and 30°, respectively.
A cut groove 15 is provided on the outward end surface of 2B, and a ring-shaped coil spring 3 is provided in the groove 15 to apply a force in the diameter reduction direction to direct each piece toward the center.
is loaded.

Furthermore, a disk-shaped plate 4 is arranged on both outer sides of the mandrel 1 and the groups of pieces 2A and 2B, and a bolt 5 is inserted through the center hole 8 of the mandrel and the center hole 16 of the plate. A nut 6 is screwed onto the bolt 5,
A washer 20 is interposed between the plate 4, bolt 5, and nut 6.

Here, as shown in FIG. 6, the bolt 5 has a vertical hole 17 in the axial direction, and a horizontal hole 18 in the radial direction that branches from the vertical hole 17 and communicates with the cavity 9 of the mandrel 1 in the center.
Furthermore, the distal end portion has a mutually parallel flat surface 19.

Next, to explain the operation of this embodiment, this jig is inserted into the butt welded part of the pipes 21A and 21B as shown in FIG. The plates 4, 4 are pressed by screwing them in. Then, first, the pieces 2B having the inner surface 12B with a taper degree of 30 degrees are expanded all at once, and the outer surface 13 is pressed against the inner surface of the pipe 21B, thereby fixing the pipe 21B.

Furthermore, when nut 6 is screwed in, the taper degree is 45°.
The piece 2A with the inner surface 12A expands and contacts the outer surface 13 with the inner surface of the pipe 21A, and the pipe 2
1A is moved in the butting direction, brought into close contact with the pipe 21B, and fixed. Therefore, argon gas is introduced from the vertical hole 17 of the bolt 5, passes through the vertical hole 17, the horizontal hole 18, the cavity 9, and the radial hole 10, and then flows through the core metal 1.
Argon gas is ejected from the top 11 of the pipe, and further argon gas is sent into the pipe abutting portion through between the pieces 2A and 2B. Therefore, welding can be carried out under an argon gas atmosphere in a state as shown by welded portion 24 in FIG. Note that automatic welding can be easily performed by rotating the pipes 21A and 21B around this jig. After welding is completed, the nut 6 is loosened, each group of pieces 2A and 2B is contracted by the force of the spring 3, and the jig can be pulled out from the pipe.

[Effects of the invention] Since the present invention has the above-described structure and operation, when butt welding pipes, even if the inner diameters of the pipes are slightly different, the butt parts can be brought into close contact without any gaps. Without losing the axis,
It can be fixed securely, works well even if one pipe is short, and the tip of the welding torch does not interfere with the jig when welding the entire circumference.
Furthermore, since it has a very simple structure, centering and fixing of the pipe can be easily done in a short time.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional front view of one embodiment of the present invention;
Figure 3 is a partially cutaway side view of the same part, Figure 3 is a partially vertical front view of the plate, Figure 4 is a partially vertical front view of the mandrel, Figure 5 is the same side view, Figure 6a is a part of the bolt. Vertical front view, b is a side view of the same end, c is a plan view of the same end, FIG. , FIG. 9 is a longitudinal sectional front view of the conventional example, and FIG. 10 is a side view of the same frame. 1... Core metal, 2A, 2B... Top, 3... Spring, 4... Plate, 5... Bolt, 6...
Nut, 7A, 7B...Conical inclined surface, 8...Mandrel center hole, 12A, 12B...Inner surface, 13...Outer surface, 16...Plate center hole, 21A, 21B
……pipe.

Claims (1)

[Scope of utility model registration request] An abacus-shaped mandrel having two conical inclined surfaces with different degrees of taper on both sides of the outer circumference, an inner surface forming a conical surface corresponding to the conical inclined surfaces, and a cylindrical surface corresponding to the inner surface of the pipe. two sets of segment-shaped pieces having an outer surface and arranged in a row on the corresponding conical inclined surface of the mandrel; A ring-shaped spring that applies radial force,
The two sets of disk-shaped plates arranged on both sides of the mandrel and the piece group, and nuts that pass through the center holes of the mandrel and the plate and screw together, and the plates on both sides. A fixing jig for pipe welding consisting of a bolt that allows the pieces to be compressed from the outside.