JPS6138710A - Manufacture of clad pipe - Google Patents

Abstract

PURPOSE:To simplify an installation and to improve a product yield by using a pipe, wound previously into a coil shape, as an inner pipe, in a manufacture of welding a butting part after covering the inner pipe by a stainless steel-strip uncoiled from a coil. CONSTITUTION:A steel pipe A wound previously around a drum 11 is used for an inner pipe, and a stainless steel strip B wound up into a coil shape is used for an outer pipe. The pipe A is uncoiled from the drum 11 to straighten its warp by a straightening machine 12, and is lapped on the strip B uncoiled from a steel-strip coil 21. Then the strip B is passed through a forming part 24, formed by arranging plural pairs of press-forming upper and lower rolls, and is bent so as to gradually form it into a circular cross section in astate of wraping the inner pipe A in it, then the strip B is formed into a perfectly circular outer pipe B1 along the outer periphery of inner pipe A. Next, after welding a butting part of pipe B1 by a welding part 25 and grinding successively the bead part of pipe B1, the pipe B1 is drawn to form it into a tight contact state with the pipe A.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a clad tube consisting of an inner tube and an outer stainless steel tube.

2. Description of the Related Art Conventionally, this kind of clad pipe is molded by bending a coil-wound band plate, which is the material of the inner pipe, into a cylindrical shape at the inner pipe forming part and welding it to form an inner pipe, and then forming an inner pipe to cover the inner pipe. A stainless steel strip drawn from another coil is gradually bent into a circular cross-section, and the butted parts are welded, or a pre-fabricated pipe cut into short pieces to a predetermined length is supplied. There was a method in which a pipe was used as an inner tube and a stainless steel strip was fed out and polymerized as described above.

Problems to be Solved by the Invention However, according to these conventional methods, the former not only requires large-scale equipment, but also has to match the fast running speed of the inner tube with the slow forming speed of the outer tube. This will result in loss of equipment. According to the latter, when the outer tube is squeezed at the final shaping section, the outer tube stretches in the length direction, leaving a gap at the joint between the inner tube and the outer tube must be cut to fit the inner tube. However, there were problems such as poor yield.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a method for manufacturing a rad tube, which simplifies equipment, eliminates losses, and has a good yield.

Means for Solving the Problems In order to achieve the above object, the present invention takes out a pipe M1 for an inner pipe previously wound into a coil shape from the drum 11, straightens the bend, and then removes the edge from the belt coil 21. Then stack it on top of the supplied stainless steel strip B. Then, the stainless steel strip B is gradually formed into an outer tube B1 having a circular cross section using a plurality of sets of upper and lower rolls 24a and side rolls 24b't4+ in the forming section 24, and the butted portions are welded. According to the invention, a preformed and coiled pipe A is used for the inner tube A1, and a coiled stainless steel strip B is used for the outer tube B1. The pipe A is stretched by the bend straightening section 12, and the steel strip B is gradually formed into a circular shape along the straightening section 12, and the abutted portions are welded. In addition, in the process after the outer tube B1, bead polishing and drawing processing are added to make it a finished product.

EXAMPLE The present invention will be described below based on an example shown in the drawings.

As shown in FIG. 1, the inner tube of the present invention is an iron pipe A that has been previously wound around a drum 11, and the outer tube is a stainless steel strip B that has been wound into a coil. Therefore, in the present invention, the iron pipe A for the inner pipe is connected to the drum 11.
The pipe A is unrolled from the steel plate coil 21, the bend is corrected, and the stainless steel snout band B is overlaid.

Then, the stainless steel band B is bent so that it approaches a circular cross section in a posture that gradually wraps around the inner tube A1 by passing the stainless steel belt B through the entire set of upper and lower rolls 241, 242 and side rolls 24b for pressure forming. After forming a complete circle along the outer periphery of the tube, weld the abutting portions of the outer nuclear tube as shown in Figure M4. Thereafter, the outer tube B1 bead portion B2 is polished and drawn to be in close contact with the inner tube.

Devices for achieving the above method include a straightening machine 12 for straightening the bends in the inner pipe, a pair of upper and lower pipe guide rolls 13, and a plate guide No. 10 for guiding the outer pipe B. Rule 22a and plate guide No. 20-2
2b, a spreading section 23 (shown in the second figure) that wraps both ends of the steel strip B and performs width adjustment [7] and polymerizes the pipe A, a plurality of sets of upper and lower forming rolls 24a (shown in the third figure), and
Molding section 2 arranged in multiple sets of squeeze rolls 24b'i
4 and two squeeze rolls on the front and back 2s by 2r1
A welding part 25 (shown in the fourth figure) having a torch 25 and a meeting member is provided between the outer tube B1 and the welding part 25 which is vertically installed above the abutting part in the width direction of the outer tube B1.

With the apparatus up to this point, a double tube is formed in which the inner tube A1 and the outer tube B1 shown in FIG. Squeeze the inner tube Al! to complete the process.

The present invention is applicable to all types of clad pipes, including the case where the inner pipe is made of cladding and the outer pipe is made of stainless steel.

Effects of the Present Invention Since the present invention is configured as described above, the apparatus is simplified, the equipment cost is reduced, and the yield is improved.

Furthermore, since the welded portions of the inner tube and the welded portion of the outer tube are overlapped while being shifted in the circumferential direction, the strength of the cladding tube itself is improved.

[Brief explanation of the drawing]

Fig. 1 is a front view of a manufacturing apparatus showing an embodiment of the present invention, Fig. 2 is an enlarged sectional view taken along the line ■-■ of Fig. 1, and Fig. 3 is a m-m of Fig. 1.
-'m enlarged sectional view, FIG. 4 is an ff-mV enlarged sectional view of FIG. 1, and FIG. 5 is a v--■ enlarged sectional view of FIG. A... Pipe for inner pipe, A1... Inner pipe, B... Steel strip for outer pipe, B1... Outer %, B2... Bead, 11...
・Drum, 12...Bending correction J '13...Pipe guide roll, 21...Steel strip coil, 23...Spreading part, 24...Forming part, 25...Welding part

Claims (1)

[Claims] The inner pipe A, which has been previously wound into a coil shape, is placed on the drum 1.
After the steel strip B is unrolled from 1 and its bends are corrected, it is stacked on top of the stainless steel strip B that is unwound from the strip coil 21, and in the forming section 24, the steel strip B is gradually shaped into a circular cross section through multiple sets of upper and lower rolls 24a and side rolls 24b. A method for manufacturing a clad pipe, comprising forming the outer pipe B1 into an outer pipe B1, and welding the butted portions.