CN102553962A - Rolling forming method for centrifugal casting composite pipe - Google Patents

Abstract

The invention discloses a rolling forming method for a centrifugal casting composite pipe, and belongs to the technical field of rolling forming of centrifugal casting composite pipes. The specific steps comprise: heating a composite pipe, wherein the heating temperature is controlled in 1160-1240 DEG C; performing pre-expansion deformation on the heated composite pipe, such that the diameter expanding rate of the inner diameter is 10-25%; and performing piercing-rolling forming on the deformed composite pipe. The method of the present invention has the following advantages that: the heated composite pipe is sequentially subjected to pre-expansion deformation and piercing-rolling forming, such that no crack is generated on the inner wall of the formed composite pipe, the qualification rate of the finished products is improved, and the production cost is substantially reduced.

Description

Spun casting multiple tube method for rolling and molding

Technical field

The present invention relates to centrifugal casting multiple tube rolling and forming technology field, specifically disclose a kind of spun casting multiple tube method for rolling and molding.

Background technology

Spun casting multiple tube as cast condition pipe with metallurgical melting layer just can reach instructions for use after generally will passing through rolling deformation, and at the multiple tube research and development initial stage, mainly through extruding or extruding+cold-rolling process roll forming, totle drilling cost is higher relatively for centrifugal base; And adopt pierced billet technology roll forming cost lower.But centrifugal base multiple tube adopts the method for direct pierced billet; Ratio of briquetting is extremely low; This is main relevant with the institutional framework and the state of centrifugal base itself; The characteristics of centrifugal base tissue are that nearly outer wall exists very thin one deck equiax crystal, inwardly are made up of thick column crystal, near being thick equiax crystal in the about 8mm scope of inwall.Because as cast condition pipe crystal grain is thick; During the distortion of pierced billet at high temperature, matrix intensity is low, bad plasticity; It is abominable than other rolling mode (as pushing, rolling in week) to the force mechanism of pipe to add pierced billet mode of texturing itself; Therefore, pipe inner layer metal in the pierced billet process very easily cracks, and causes waste product.

Summary of the invention

The technical problem that the present invention will solve provides a kind of spun casting multiple tube method for rolling and molding that can significantly improve product qualified rate.

For solving the problems of the technologies described above, the technical scheme that the present invention taked is: heat multiple tube (1), and heating and temperature control is at 1160 ℃～1240 ℃;

(2) multiple tube after the heating is expanded distortion in advance, make the enlarging rate of its internal diameter reach 10%～25%;

(3) to carrying out the pierced billet moulding through multiple tube after expanding distortion in advance.

Said spun casting multiple tube outer layer metal is 14MnV, and inner layer metal is 316L, and the pipe specification is ￠ 220*60, internal diameter ￠ 100.

In the above-mentioned steps (2) multiple tube after the heating is expanded distortion in advance; Can make composite pipe blank inner layer metal inwall and nearly interior wall tissue that crystallization again takes place; Crystal grain obtains refinement, has improved organization factors, improves the high-temp plastic and the intensity of inner layer metal; Make its inner layer metal in follow-up pierced billet operation not ftracture, be easy to moulding.Through repetition test repeatedly, be lower than 10% if find the enlarging rate of multiple tube internal diameter, then crystallization does not more take place in multiple tube interior wall tissue basically, does not reach the purpose of improving organization factors; If the enlarging rate of multiple tube internal diameter is higher than 25%, then the multiple tube outer layer metal radially is easy to generate crackle, does not also reach requirement, therefore the multiple tube after the heating is expanded distortion in advance, and the enlarging rate of its internal diameter is controlled between 10%～25%, just can reach requirement.

Beneficial effect of the present invention is following: through to the process expansion distortion in advance earlier of the multiple tube after the heating, carry out the pierced billet moulding again, make that crackle no longer appears in the multiple tube inwall after the moulding, improve product qualified rate, greatly reduce production cost.

The specific embodiment

To spun casting composite pipe blank 14MnV/316L (outer layer metal is 14MnV, and inner layer metal is 316L), the pipe specification is ￠ 220*60, and internal diameter ￠ 100 adopts method of the present invention to be rolled moulding, and concrete grammar is following:

(1) composite pipe blank is heated 1160 ℃～1240 ℃ of soaking zone furnace temperature in ring-like stove.

(2) composite pipe blank is expanded distortion in advance, adopt reaming to come directly towards to after ￠ 114 reamings, the composite pipe blank actual inner diameter is ￠ 113, and the internal diameter enlarging rate is 13% ((113-100)/100*100%).

(3) composite pipe blank is bored a hole.

The multiple tube inwall that will pass through after the above-mentioned steps pierced billet moulding compares with the multiple tube inwall that is out of shape direct pierced billet moulding without preparatory expansion; Can find that crackle obviously no longer appears in the former multiple tube inwall; Reach instructions for use; And latter's multiple tube inwall has more crackle, does not meet instructions for use, causes waste product.

Claims (2)

1. spun casting multiple tube method for rolling and molding is characterized in that its method step is following:

(1) the spun casting multiple tube is heated, heating and temperature control is at 1160 ℃～1240 ℃;

(2) multiple tube after the heating is expanded distortion in advance, make the enlarging rate of its internal diameter reach 10%～25%;

(3) to carrying out the pierced billet moulding through multiple tube after expanding distortion in advance.

2. spun casting multiple tube method for rolling and molding according to claim 1 is characterized in that, said spun casting multiple tube outer layer metal is 14MnV, and inner layer metal is 316L.