JPS61131829A - Manufacture method of round pipe with hexagonal pad - Google Patents

Abstract

PURPOSE:To make a round pipe formable so accurately in an efficient manner, by forming a pad part having each taper part at both sides in a longitudinal intermediate part of the round pipe, and then machining an outer surface of the pad part into a section hexagonal form. CONSTITUTION:A blank pipe A0 is finished up in the specified size by means of hot or cold finishing. In order to give the specified cold working value uniformly to the overall length, the blank pipe A0 is processed with cold drawing. Next, both sides of the round pipe A after the cold working are cut outward, and a pad part 2 is left formed in a longitudinal central part. The pad part 2 a taper part 3 ranged from both round pipe parts 1 at both sides of it. Next, an outer surface of the pad part 2 is chamfered, machining it into a section hexagonal form, and it is finished up to the specified final product outer facing distance. In the case where application of the pipe is for a guide pipe, the taper part 3 is machined and then chambered (5) whereby each side of pad part outer surfaces is finished so as to become a rectangle in length as specified.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a round tube with a hexagonal pad, which is used as a control rod guide tube for a high-speed smoker.

[Prior art]

In recent years, so-called breeder reactors have been developed and are approaching the stage of practical use. The core of this type of nuclear reactor consists of fuel assemblies, control rods arranged between the fuel assemblies, radial brackets surrounding these fuel assemblies, neutron shields, etc. They are housed in adjacent guide tubes and sheath tubes, respectively. A gap is provided between these tubes, and the refrigerant is allowed to flow through this gap to extract the generated heat.For this purpose, a rad is provided as a spacer on the outer surface of the intermediate portion of the guide tube, etc. to ensure the above-mentioned gap.

By the way, the materials used to construct the reactor core are subject to particularly severe restrictions as they handle fast neutrons generated by nuclear fission, and for this reason, the guide tubes with spacer pads and the like are also integrally molded without welding. It is preferable that the As shown in Figures 2 (a) and (b), such a guide tube has a round tube part (1) with a regular hexagonal outer diameter cross section in the middle of a round tube with uniform outer and inner diameters. A very special feature is that a pad part (2) having a circular inner diameter of the same size is formed, and a tapered part (3) is provided between this pad part (2) and both light tube parts (1). In the shape of
Moreover, it is required that a predetermined amount of cold working (reduction) be applied uniformly over the entire length.However, as mentioned above, the use of such a pipe is new, Until now, no such manufacturing method has been proposed.

The present invention has been made in view of these circumstances, and it is an object of the present invention to provide a method that can rationally manufacture the above-mentioned round tube with hexagonal pads.

[Means to solve the problem]

For this reason, the present invention cold-works a round tube by a predetermined amount over its entire length, thereby ensuring a uniform amount of cold working in the longitudinal direction, and then forming tapered portions on both sides. The outer surface of the pad is machined into a round tube shape so that the pad part is formed at the middle part in the longitudinal direction, and then the outer surface of the pad part is cut into a hexagonal cross section. The tube can be manufactured accurately and efficiently while being subjected to a predetermined amount of cold working.

Hereinafter, the details of the present invention will be explained based on the drawings.

FIG. 1 shows an example of the manufacturing process according to the present invention.

First, the raw pipe (Ao) is finished to predetermined dimensions by hot finishing or cold finishing. Prior to the original cold working to impart a predetermined amount of strain, the raw pipe is subjected to cold working and recrystallization heating (ω in the figure and a)) for the purpose of adjusting the grain size.

For this reason, first, cold drawing is performed to apply a stress reduction of around 15%, and then heat treatment is performed to adjust the crystal grain size to an appropriate state. Such a series of treatments is performed as necessary depending on the material of the raw pipe, and is not necessarily required depending on the material.

The raw pipe (A6) treated in this manner is subjected to cold drawing in order to uniformly apply a predetermined amount of cold working over the entire length ((1'/) in the figure).

If the application is the above-mentioned concrete rod guide tube, a cold work amount of 20±5% is usually required. The dimensions of the round tube (A) after cold working are such that the outer diameter is equal to or larger than the hexagonal diagonal dimension of the pad portion, and the inner diameter is the inner diameter dimension of the final product.

Next, both sides of the round tube (A) are machined to form a remaining pad portion (2) in the center in the longitudinal direction ((V) in the figure). The pad portion (2) has tapered portions (3) on both sides thereof, which are continuous with both the light tube portions (1). Note that, at this stage of completion of external machining, the pad portion (2) is in the shape of a round tube. Furthermore, both light tube sections (1) are finished to the final product dimensions by external machining.

Next, the outer surface of the pad portion (2) is chamfered (4) and cut into a hexagonal cross section to obtain a predetermined final product size and shape.
l ((VD) in the figure).Furthermore, if the pipe is used as a guide pipe as mentioned above, the outer surface of the pad part must be square (rectangular) on each side, so the taper part ( 3) is cut and chamfered (5), and finished so that each side of the outer surface of the pad part (chamfered part (4)) becomes a rectangle of a predetermined length to obtain the dimensions and shape of the final product ((■) in the figure).
.

The material for this type of tube body is usually SUS 316.
etc. are used.

〔Example〕

A round tube with hexagonal pads having the following dimensions was manufactured.

The manufacturing procedure is shown in the table below along with the dimensions of each part of the tube at each step.

Round tube part outer diameter: 110.6g ■ Total length inner diameter: 104.6Jll Immersion pad part outer surface distance: 114.6H Soup pad part length = 40 [Effects of the invention] According to the present invention described above, There is an effect that a round tube having a hexagonal pad portion in the middle portion can be manufactured accurately and efficiently while applying a predetermined amount of cold working.

BRIEF DESCRIPTION OF THE DRAWINGS The first diagram is an explanatory diagram showing step by step an example of the manufacturing process according to the method of the present invention. Figures 2 (a) and (b) show a round tube with a hexagonal pad to be manufactured using the method of the present invention. Figure 2 (a) is a perspective view, and Figure 2 (b) is a longitudinal cross-section of the pad part. It is a diagram. In the figure, (1) is the round tube part, (2) is the pad part, and (3) is the round tube part.
) indicates the Taber part.

Claims (1)

[Claims] A round tube is machined with a specified amount over its entire length. After cold working, it has tapered parts on both sides. The pad portion is formed at the longitudinally intermediate portion. Then, the outer surface of the pad part is cut into a cross-section. 6, which is characterized by cutting into a square shape. Manufacturing method for round tubes with square pads.