JPH049215A - Manufacture of square pipe - Google Patents

Abstract

PURPOSE:To allow the manufacture of the square pipe by correcting the round pipe with the pipe correcting machine having the continuous and vertical type opposite rolls of the material of the specific Young-modulus. CONSTITUTION:The round pipe is formed to the square pipe by utilizing the pipe correcting machine 1 of continuous and vertical type opposite system using the material of Young's modulus (1.0-5.0)X10<10> Pa as the quality of material for the material of correcting roll, and setting the clash at the correcting time to (D-L)+ or - %, wherein the outside diameter of the round pipe before correction is D, and one side length of square pipe after correction is L. Therefore, the round pipe can be formed to the square pipe without fear of generating flow and with saving the preparing time.

Description

[Detailed description of the invention] "Industrial application field" The present invention relates to a method for manufacturing a square pipe.

``Conventional technology'' Conventionally, square pipes have generally been manufactured by modifying the production line for electric resistance welded steel pipes, or alternatively, square pipes have been manufactured by constructing a new square pipe manufacturing factory. Even in cases where both edge parts of the steel strip are welded to make a round pipe, the manufacturing method is exactly the same as that of ERW steel pipes, and then the round pipe (ERW steel pipe) is made into a large size pipe. A method of forming square pipes by roll forming is adopted.

``Problems to be Solved by the Invention'' By the way, as mentioned above, when a round pipe is formed into a square pipe by large roll forming, defects occur due to the difference in the peripheral speed of the large rolls, so it is necessary to increase the pipe forming speed. In order to improve productivity, many molding stands must be installed in parallel.
This method requires a large factory and requires a large amount of capital investment.

Furthermore, when round pipes and square pipes are manufactured in the same factory, it is necessary to replace a large number of forming rolls when switching between types, and there is a problem in that it takes a long time to restart production.

Furthermore, if a round pipe manufacturing factory is to be used as a manufacturing factory for both round pipes and square pipes, a forming roll stand for square pipes will be required, and the subsequent conveyor line will also need to be modified, and equipment will need to be installed. There are problems in that the investment amount is high, many large rolls of both round and square shapes are required, and running costs are also high.

"Means for Solving the Problems" The method for manufacturing a rectangular pipe according to the present invention has been made to solve the above-mentioned conventional problems, and its gist is that young Rate (1,0~
5.0) When the outer diameter of a round pipe before straightening is D and the side of a square pipe after straightening is L using a continuous vertical opposed roll type pipe straightening machine using a material of x fPa,
The purpose is to set the crush during straightening to (D-L):v- and form a round pipe into a square pipe.

``Function'' As shown in Fig. 1, the continuous vertical opposed roll type pipe straightening machine 1 is constructed by vertically arranging hourglass-shaped straightening rolls 1a with concave hyperboloids, and the straightening rolls 1a are arranged vertically. The pipe 2 is repeatedly deformed in the longitudinal direction of the pipe 2 and in the circumferential direction of the pipe 2 by crushing, thereby correcting the bending and roundness of the pipe 2.

Therefore, in boat fishing, the distance between the stands with a pair of straightening rolls 1a is an odd number multiple of the interval that the pipe 2 advances by rotating 90 degrees during straightening, and the feed angle of the straightening rolls 1a is The outer diameter range within which this is maintained is the outer diameter range that can be corrected (the second
(see figure), narrow the interval between the upper and lower straightening rolls la of each pair (larger crush) to crush the upper and lower parts of the round pipe 2, and reduce the height of the round pipe 2 as shown in Fig. 3 (A). If the value of A is the circumference length of Manufacturing becomes possible.

In this case, according to the inventor's experiments, if the upper and lower straightening rolls la are close to rigid bodies, deformation is not performed smoothly, leading to deterioration of the shape.

Generally, rolls made of cast iron are used as straightening rolls, but in order to achieve the present invention, straightening rolls la with low rigidity, such as those made of urethane, are desirable.

FIG. 4 shows the relationship between the Young's modulus of the material for the straightening roll and the molded shape of the rectangular pipe.As is clear from FIG.
0 to 5.0) x IO''Pa material (urethane roll here) must be used.

In addition, if the crush value is too large or too small, the shape of the square pipe will not be suitable, so in the experiment shown in Figure 4, the crush value was set to (D-L>:an, but in practical use The upper limit may be set within the range of (D-L)1 萱-.

"Example" A round pipe with an outer diameter of 60.5 m, a wall thickness of 3.0 m, and a material of 5O5310 was fixed using a continuous vertical opposed roll pipe straightening machine that used urethane rolls as straightening rolls to prevent crashes during straightening. (DL): When molded into a rectangular pipe with a setting of 0, a rectangular pipe with an appropriate square shape with a negative side of 47.5M was obtained.

"Effects of the Invention" In conventional large roll forming, the production of square pipes was at a maximum of 0.5 tons/hour due to the problem of spots caused by the difference in circumferential speed of the large rolls, but with the method of the present invention, the production rate of square pipes was at a maximum of 0.5 tons/hour. It is possible to produce square pipes at a rate of 10 tons/hour without fear.

Also, the setup change time from round pipe to square pipe is
Conventionally, it took 60 minutes to replace the large roll, but in the method of the present invention, the setting of the crush value of the straightening roll is simply changed, so it can be completed in an extremely short time of only 5 minutes.

Furthermore, since a urethane roll, for example, is simply used as the straightening roll instead of a cast iron roll, a relatively inexpensive equipment investment can be achieved.

Furthermore, it is possible to transform a conventional round pipe manufacturing factory into a factory capable of manufacturing both round and square pipes by simply modifying the conveyance equipment after the final straightening stand, which is a relatively inexpensive capital investment. can.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram showing how a square pipe is formed from a round pipe using a continuous vertical opposed roll type pipe straightening machine. Figure 2 is an explanatory diagram showing the shape change from a round pipe to a square pipe, Figures 3 (A) and (B) are explanatory diagrams showing the principle of forming a square pipe using a straightening machine, and Figure 4 is an explanatory diagram showing the shape change of a square pipe by a straightening machine. It is a graph showing the relationship between the ratio and the molded shape of a square pipe. 1... Continuous vertical opposed roll type vibe straightening machine 1a...
- Straightening roll 2...Round pipe 12...
square pipe

Claims (1)

[Claims] (1) As the material of the straightening roll, Young's modulus (1.0 to 5
．． When the outer diameter of a round pipe before straightening is D and the side of a square pipe after straightening is L, using a continuous vertical opposed roll type pipe straightening machine using a material of 0) × 10^1^0Pa, Set the crash during correction to (D-L) ±■■,
A method for manufacturing a square pipe, characterized by forming a round pipe into a square pipe.