JPH0743066B2 - Unequal thickness curved pipe - Google Patents

Description

TECHNICAL FIELD The present invention relates to a curved wall tube having wear resistance.

(Prior art) A curved pipe for pumping slurry containing aggregate such as concrete and mortar is selectively worn on the inner surface of the outer pipe wall in the bending radius direction of the bending pipe. An eccentric wall-thickness tube with gradually increasing wall thickness is used.

This type of uneven wall thickness pipe is generally sand-cast integrally with the pipe end flange portion.

(Problems to be Solved by the Invention) However, since the flange portion is integrally cast, the molding of the mold is complicated, and the size is increased, and the productivity is inevitably reduced.

Further, since the uneven thickness curved pipe is exalted, the handling thereof is troublesome in storage and transportation.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an uneven thickness curved pipe that is easy to handle and has excellent moldability.

(Means for Solving the Problems) The uneven thickness curved pipe of the present invention made to achieve the above object has a wall thickness gradually increasing from the inner side to the outer side in the bending radius direction of the curved pipe. In an uneven thickness curved pipe 1 having a pipe portion 2, a thick wall portion 3 for inserting a flange having a substantially uniform thickness in a circumferential direction is provided at a pipe end portion of the uneven thickness curved pipe.
Is formed as the constitution of the invention.

(Operation) At the end portion of the uneven thickness curved pipe 1 having the intermediate pipe portion 2 whose thickness in the outer side in the bending radius direction is uneven, the insertion flange connection having a substantially uniform thickness in the circumferential direction is formed. Since only the thick wall portion 3 is formed, it is possible to reduce the size of the entire uneven thickness curved pipe, which is convenient in handling.

In addition, the mold can be downsized and simplified in casting.

Furthermore, even when connecting the insertion flange, since the thick portion 3 is formed at the pipe end, the flange is attached to the uneven wall thickness pipe without damaging the thin pipe wall inside the intermediate pipe portion 2. A strong and reliable connection can be made.

(Example) Next, the Example of this invention is described with reference to drawings.

The midway pipe portion 2 of the uneven thickness curved pipe 1 according to the embodiment shown in FIGS. 1 to 3 extends from the inner side to the outer side in the bending radius direction of the curved pipe,
The wall thickness of the pipe is gradually increased. On the other hand, a thick portion 3 for connecting an insertion flange having a substantially uniform thickness over the circumferential direction is formed at the pipe end portion.

The thick-walled portion 3 is formed so that its thickness is substantially the same as the maximum pipe thickness at the outermost side in the bending radius direction of the curved pipe, and the outermost surface is flush with the outermost surface of the midway pipe portion 2. Has been done.

The uneven thickness curved pipe 1 is usually cast from cast iron for ease of casting. As cast iron, gray cast iron, ductile cast iron and the like are used, but the latter gives higher strength. In particular, those in which the matrix is bainized by heat treatment after casting have excellent wear resistance and are suitable. Of course, it is also possible to use alloy cast iron to which appropriate alloy components are added in order to impart wear resistance and corrosion resistance.

As a cast iron method for the uneven thickness curved pipe 1, a full mold casting method is preferable. According to the full-mold casting method, a vanishing model having the same shape as that of the uneven thickness curved pipe 1 is made of a foamed synthetic resin such as Styrofoam, and a runner model and a sprue model are adhered to the model and placed in a casting frame. The dry side may be filled around and the desired molten metal may be injected into the model. The model into which the molten metal is injected burns due to contact with the molten metal and disappears by vaporization,
Replaces cast metal.

The uneven wall thickness tube 1 cast as described above may be welded by fitting the insertion flange 4 at an appropriate time before use as shown in FIG. Of course, it is possible to form a screw on the thick portion 3 and use it as it is as a pipe joint.

(Effects of the Invention) As described above, the uneven thickness curved pipe of the present invention has only the thick wall portion for the insertion flange connection formed at the end of the uneven thickness curved pipe. The curved product tube itself can be miniaturized, the cost for molding a mold can be reduced, and the handling can be facilitated.

Furthermore, since the thick portion formed at the pipe end is formed to have a substantially uniform thickness along the pipe circumferential direction, when connecting a flange or the like, the inside of the bending radius of the intermediate pipe and the vicinity thereof There is no danger of damaging the thin wall.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an uneven thickness curved pipe according to an embodiment, FIG. 2 is a sectional view taken along the line AA of FIG. 1, and FIG. 3 is a sectional view taken along the line BB of FIG.
FIG. 4 is a partial cross-sectional view showing a state in which an insertion flange is welded and joined to a pipe end portion of an uneven thickness curved pipe. 1 ... Unbalanced thickness curved pipe, 2 ... Midway pipe part, 3 ... Thick wall part.

Claims (2)

[Claims] 1. An uneven thickness curved pipe 1 having a midway pipe portion 2 in which the wall thickness of the curved wall gradually increases from the inner side to the outer side in the bending radius direction of the curved pipe. An eccentric wall-thickness tube having a thick-walled portion 3 for connecting an insertion flange having a substantially uniform thickness in the circumferential direction. 2. The uneven thickness curved pipe according to claim 1, wherein an insert flange is fitted and welded to the thick wall portion 3.