JPS6320423Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a tube end expanding device for connecting tubes.

Among conventionally known pipe connection methods, there is a so-called bell-shaped welded joint, as shown in FIG.
The pipe is expanded, and the other connecting pipe 3 is fitted inside it without being expanded, and the pipe end is surrounded and welded. is necessary. For this reason, especially for the purpose of installation at a piping site, a segmented pipe expander has been devised as shown in FIGS. The dies 4 are inserted radially, and expansion shafts 6 with conical enlarged diameter portions 5 connected to the centers of these dies are disposed concentrically and movably from the outside. Projection angle 7 protruding along the conical line
As shown in Fig. 2a, when the tube expansion shaft is moved in the direction of the arrow X, the conical expanded diameter portion Since each die is expanded radially, the tube end 2 is expanded. In addition, the aforementioned tube expansion shaft 6
The movement is achieved by screwing the end of the rod 11 of the piston 10 of the hydraulic cylinder 9, which is arranged concentrically around the shaft, to the end of the expanding shaft, and sending pressure to one port 12 of the hydraulic cylinder. There is. The pipe end expansion work can be easily carried out at the piping site using the above-mentioned pipe expander, but carbon steel pipes commonly used for piping have variations in pipe thickness, as shown in Figure 3a. For example, if the upper thickness t ₁ illustrated in the same figure is larger than the lower part thickness t ₂ or if the electric resistance welding part 13 shown in FIG. 3b runs along the tube wall, in such a case, the tube expansion In the former case, the thick side of the large pipe is difficult to extend, and in the latter case, the electric resistance welded part is difficult to extend compared to the base material, so the 3a
As shown in the figure, misalignment d may occur in the tube expansion section, and furthermore, due to the weight of the mechanism of the hydraulic cylinder 9 that moves the tube expansion shaft 6, as shown in FIG. It is unavoidable that the tube may droop and the axis of the expanded tube may become misoriented.

This invention was made in view of the current situation. Next, an embodiment of the invention will be described with reference to the drawings. In FIGS. The segment-shaped dies 14 are inserted radially, and the protruding outer flanges 15 at the ends thereof are brought into contact with the tube ends, respectively, and the dies 14 are placed in the center of the arranged dies 14, as will be described later. A truncated hexagonal pyramidal tube expansion stand 18 having a sliding hole 17 into which the mandrel shaft 16 is slidably inserted is concentrically inserted, and each pyramidal surface 19 of the tube expansion stand is engaged with the inclined surface 20 inside each die. At the same time, the dovetails 21 protruding from each of the conical surfaces are engaged and fitted into the dovetail grooves 22 cut on the inclined surface of the die to form the Y shown in FIG. 4a.
By moving the tube expansion table in the direction of the arrow, each die can be expanded radially. Next, the dies are slid in the connecting pipe 1 in contact with the bottom surface of the tube expansion table, and the mandrel shaft 16 is placed in the center. Another sliding hole 2 that is slidably inserted
The tube end has a centering jig board 24 having a centering jig board 24 having a diameter of 3, and further has another sliding hole 25 in contact with the side surface of the outer flange of the die and into which the mandrel shaft 16 is slidably inserted. A dish-shaped pressure receiving plate 26 having an inner diameter of a countersunk hole larger than the planned pipe expansion diameter of the section is arranged, and a hydraulic cylinder 9 is also arranged in contact with the outer surface of the pressure receiving plate, and a mandrel shaft 16 is arranged in the center thereof. A sliding hole 27 that is slidably inserted is bored, and a hole is inserted through the sliding hole, the pressure receiving plate sliding hole, the tube expansion table sliding hole, and the centering jig board sliding hole at both ends. Insert the mandrel shaft 16 with a male thread onto it, screw the fixing nut 28 into the male thread on the centering jig board 24 side, and attach the male thread at the other end to the piston 10 in the hydraulic cylinder 9. Rod 11
The ends are screwed in. The P port of an electromagnetic switching valve 30 connected to a hydraulic pump 29 is connected to the port 12 that sends pressure to the piston side of the cylinder, and the port 31 on the rod side of the cylinder is connected to the R port, so that pressure oil does not flow. When the piston is pushed, the mandrel shaft 16 moves to the right in FIG. 14
expands, and then the tube end 2 is expanded. Now, a limit switch 32 is installed in the dish wall of the pressure receiving plate 26 so that the end of the actuating piece 33 can be pushed up freely when the tube end 2 is expanded. If the electromagnetic section of the electromagnetic switching valve is controlled by forming a circuit that is in contact during operation, the pressure oil will push the piston 10 during the pipe expansion operation, causing the mandrel shaft 16 to move to the right, thereby closing the pipe end 2. starts pipe expansion, but in a predetermined pipe expansion state, the operating piece 33 of the limit switch 32 is pushed up to shift to the OFF state, so that the pressure supply ends and the pipe expansion operation is stopped.

As described above, according to this invention, the dovetail 21 of the tube expansion stand 18 is fitted into the dovetail groove 22 of the die 14 during tube expansion, so each die can smoothly maintain a concentric state. Since the centering jig board 24 is always located on the inside of the connecting pipe 1 where the pipe is not expanded, the mandrel shaft 16 is similarly located at the center of the connecting pipe, which prevents eccentricity in the expanded state. There is no chance of this happening at all. Now, if the allowable bending angle in the expanded state is θ, then the centering jig board 2
The outer thickness of 4 is L, the outer diameter is D, and the inner diameter of connecting pipe 1 is
When D _i , arctan ((D _i −D)/L)<θ, so the dimensions of the important parts of the tube expansion device according to this invention can be easily obtained.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional side view showing a pipe connection method using a so-called bell-shaped welded joint, Fig. 2a is a longitudinal sectional side view of a conventional example of a tube end expansion device, and Fig. 2b is an A-A in the previous figure. 3a is a longitudinal sectional view showing the misalignment of the tube expansion section, FIG. 3b is a longitudinal front view, and FIG. 3c is a longitudinal sectional side view showing the center inclination of the tube expansion section. FIG. 4b is a longitudinal cross-sectional side view showing an embodiment of this invention, and FIG. DESCRIPTION OF SYMBOLS 1... Connecting pipe, 2... Pipe end, 3... Other connecting pipe, 4... Segment-shaped die, 5... Conical enlarged diameter part, 6... Tube expansion shaft, 7... Projection angle, 8... ...Sliding groove, 9...Hydraulic cylinder, 10...Piston, 1
1... Rod, 12... Port, 13... Electric resistance stitching part, 14... Segment-shaped die, 15... Outer flange, 16... Mandrel shaft, 17... Sliding hole, 18...
Truncated hexagonal pyramidal tube expansion stand, 19...Pyramidal surface, 20...
Die inclined surface, 21...Tingle shape, 22...Dovetail groove, 23...Sliding hole, 24...Centering jig board, 25
...Sliding hole, 26 ... Dish-shaped pressure receiving plate, 27 ... Sliding hole, 28 ... Fixing nut, 29 ... Hydraulic pump, 30 ... Solenoid switching valve, 31 ... Port, 32
... Limit switch, 33... Actuation piece.

Claims (1)

[Scope of utility model registration request] A plurality of segment-shaped expansion dies are fitted radially into the end of the connecting pipe to be expanded, and a truncated polygonal conical tube expansion stand that slides along the mandrel axis is concentrically inserted into the center of the expansion die. The pyramidal surfaces of are brought into engagement contact with the inner inclined surfaces of the respective dies, and the claw-shaped dovetails protruding from the pyramidal surfaces are engaged and fitted into the dovetail grooves of the die inclined surfaces, and further fitted into the bottom surface of the tube expansion table. A centering jig board is provided that contacts the inner surface of the connecting pipe and the outer surface of the mandrel shaft, and connects a fixing nut screwed onto the end of the mandrel shaft to the centering jig board. A tube end expanding device characterized in that the expansion die is expanded in a radial direction by moving the tube expansion table using a centering jig board according to the movement of the mandrel shaft in the axial direction.