JPH0257456B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method and apparatus for manufacturing a curved pipe, such as a piping elbow, from a tubular material.

(Prior art) Metal curved pipes such as piping elbows are manufactured by punching a metal plate into a predetermined shape and welding both end faces of the metal plate, which is a complex process and requires surface smoothness. It also has the disadvantage of poor dimensional accuracy, and metal products that are difficult to weld cannot be manufactured. Therefore, by inserting a tubular material into a forming hole provided between a pair of molds and press-fitting it from the straight part on the entrance side of the molding hole to the curved part on the exit side of the molding hole, the material is plastically deformed into a curved pipe. Techniques for this have been proposed in Japanese Patent Application Laid-Open No. 102230/1983.

(Problem to be solved by the invention) However, in the conventional technology of this kind, when trying to use a cored metal to improve the inner surface precision, it is difficult to use the cored metal in a way that does not interfere with the supply of tubular material or the discharge of curved pipes. Since it is not possible to hold the metal core in the forming hole, a steel ball is unavoidably used instead of the core metal, but the management and handling of the ball is troublesome and is a bottleneck in mass production. There has been a need for the development of a manufacturing method and an apparatus for manufacturing a curved tube that can be formed while reliably holding the tubular material in the forming hole without any problems in supplying the tubular material or ejecting the formed curved tube.

(Means for Solving the Problems) The present invention relates to a method for manufacturing a curved pipe and an apparatus therefor that meet the above-mentioned demands. In the method for manufacturing a curved tube, the tube is plastically deformed by inserting the tube and press-fitting it from the straight section on the inlet side of the forming hole into the curved section on the outlet side using a press mechanism, wherein a tubular guide is inserted into the forming hole. A core metal for forming the part is inserted, and its exit side end is connected to the tip of a rotatable curved holding rod installed outside the mold to hold the core metal in the forming hole. The method is characterized in that the curved pipes sent out from the outlet are received in the curved holding rod one by one, and the curved holding rod is rotated so that the connection with the core metal is released, and the bent pipe is removed from the curved holding rod. The first invention provides a method for manufacturing a curved pipe, in which a pair of semicircular molding grooves are provided on mating surfaces to form a forming hole consisting of a straight hole on the inlet side and a curved hole on the outlet side. a metal mold, a core metal inserted into the molding hole to form a tubular guide part between the hole wall, a press mechanism detachably provided on the entrance side of the tubular guide part, and the core metal Rather than adopting two modes: a closed mode in which the curved holding rod is engaged and connected to the outlet side end of the mold with a retaining portion at its tip, and an open mode in which it is separated from the core metal, the curved holding bar is installed outside the mold. A second invention provides a curved pipe manufacturing apparatus characterized by comprising a rotatable core metal holding mechanism.

(Example) Next, an example of the present invention will be described in detail with reference to illustrated process diagrams.

In the figure, 1 and 1 are a pair of split-type molds, 2 is a molding hole consisting of a semicircular molding groove provided on the mating surfaces of the molds 1 and 1, and the molding hole 2 is an outlet. It consists of a curved hole portion 2a on the side and a straight hole portion 2b on the entrance side. 3 is the molding hole 2 of this mold 1, 1
The core metal 3 is made up of a curved rod part 3a and a cylindrical rod part 3b having a slightly smaller diameter than the curved hole part 2a and the straight hole part 2b, and the core metal 3 is inserted into the core metal. A tubular guide portion 4 having a curved lower end is formed between the molding hole 3 and the hole wall of the forming hole 2. Reference numeral 5 denotes a press mechanism provided above the entrance side of the tubular guide section 4 so as to be movable up and down, and its leg section 5a can be inserted into and removed from the tubular guide section 4 at will. Reference numeral 6 denotes a core metal holding mechanism installed outside the molds 1, 1, and the core metal holding mechanism 6 is a plate rotatably attached to the upper outside of one of the molds 1 with a shaft 7. A base plate 9 is stretched over the body 8, and the proximal end of a curved holding rod 10 having a radius of curvature close to that of the curved rod portion 3a is fixed to the base plate 9. A closed mode in which the curved holding rod 10 is engaged and connected to an engaging portion 12 such as a recessed portion with a locking portion 11 formed at its tip;
It is designed to take two opening modes, one separated from the other.

In order to manufacture a curved tube using such an apparatus, as shown in FIG. In this way, the linear hole portion 2 is
b into the cylindrical gap of the tubular guide part 4 formed between the hole wall and the cylindrical rod part 3b, and then, as shown in FIG. 4 and push the tubular material 21 into the curved cylindrical gap between the curved hole portion 2a and the curved rod portion 3a, the tubular material 21 will have a cylindrical rod portion 3b, a straight hole portion 2b, and Since it is bent while being guided by the curved rod portion 3a and the curved hole portion 2a, the curved tube 22 is formed without wrinkles. Therefore, the press mechanism 5 is raised once and the leg tube part 5a is extracted from the forming hole 2, as shown in FIG.
If the tubular material 21 is inserted into the forming hole 2 again and the leg tube section 5a of the press mechanism 5 pushes the tubular material 21 between the curved hole section 2a and the curved rod section 3a, the curved tube 22 described above will be formed into this tubular shape. When the material 21 is made into a curved tube, the mold 1,
At this time, the core metal 3 inserted into the molding hole 2 is pushed out of the mold 1, and the exit side end of the core metal 3 is held by the tip of the curved holding rod 10 installed outside the mold 1. Since it is fixed and held at a predetermined position within the forming hole 2, accurate molding is performed without movement of the core metal 3, and the core metal holding mechanism 6 does not get in the way when inserting the tubular material 21. There is no
Further, since the curved pipe 22 pushed out from the exit side end of the forming hole 2 is received by one curved holding rod 10, as shown in FIG. It can be easily removed by simply rotating it in the direction in which it is uncoupled.
Even during this removal, the core metal holding mechanism 6 does not get in the way, and while the core metal holding by the curved holding rod 10 is released, the core metal 3 inserted into the forming hole 2 is shaped like a tube. Since the normal position is maintained by the curved tube 22 left in the guide section 4, the next time the curved retaining rod 10 is rotated in the opposite direction to take the closed position, its tip will be aligned with the core metal 3. It will automatically engage with the outlet side end, allowing continuous work.

(Effects of the Invention) As is clear from the above description, the present invention includes a pair of molds having a molding hole in which a straight hole continues with a curved hole, and a mold that is inserted into the molding hole to form a hole wall. By skillfully combining a core metal that forms a tubular guide section between the two and a rotatable core metal holding mechanism that has a curved holding rod that holds the core metal at its tip at the outlet end of the forming hole, The present invention will greatly contribute to the development of the industry as a method for easily mass-producing wrinkle-free curved pipes from raw materials and as a device with a simple structure for carrying out this method.

[Brief explanation of drawings]

FIG. 1, FIG. 2, FIG. 3, and FIG. 4 are process explanatory diagrams of the method of the present invention using the apparatus of the present invention. 1: Mold, 2: Molding hole, 2a: Curved hole, 2
b: Straight hole portion, 3: Core metal, 3a: Curved rod portion, 3
b: Cylindrical rod portion, 4: Tubular guide portion, 5: Press mechanism, 5a: Leg tube portion, 6: Core metal holding mechanism, 10:
Curved holding rod.

Claims (1)

[Claims] 1. Inserting a tubular material from the entrance of a forming hole provided between a pair of molds and press-fitting it from the straight part on the entrance side of the forming hole to the curved part on the exit side using a press mechanism. In the manufacturing method of the curved pipe, the core metal for forming the tubular guide portion is inserted into the forming hole, and the exit side end thereof is inserted into the mold. The mandrel is connected to the tip of a freely curved holding rod to hold it in the forming hole, and in this state, the curved pipe sent out from the outlet is
A method for manufacturing a curved tube, which comprises receiving the curved tube individually into a curved retaining rod, and then rotating the curved retaining rod so as to release the connection with the core metal, thereby removing the curved tube from the curved retaining rod. 2. A pair of molds 1 each having a semicircular molding groove formed on their mating surfaces to form a molding hole 2 consisting of a linear hole portion 2b on the inlet side and a curved hole portion 2a on the outlet side.
1, a core metal 3 that is inserted into the forming hole 2 and forms a tubular guide section 4 between it and the hole wall, and a press mechanism 5 that is removably installed on the entrance side of the tubular guide section 4. The curved holding rod 10 has two modes: a closed mode in which the curved holding rod 10 is engaged and connected to the outlet side end of the core bar 3 with a locking portion 11 at its tip, and an open mode in which it is separated from the core bar 3. A manufacturing device for a curved pipe, comprising a rotatable core metal holding mechanism 6 installed outside of the molds 1, 1.