JP5998941B2 - Manufacturing method of differential thickness steel plate and differential thickness forming apparatus - Google Patents

Description

  The present invention relates to a method for manufacturing a differential thickness steel plate and a differential thickness forming apparatus.

  As a manufacturing method of a differential thickness steel plate called a tailored blank in which a plate thickness difference is provided in the longitudinal direction of the steel plate, conventionally, a method of performing welding by overlapping plate materials at predetermined locations has been widely adopted. However, in particular, in the case of a complex-shaped differential thickness steel plate or the like that requires welding at a plurality of locations, there is a drawback that it takes time and cost for welding.

  On the other hand, in recent years, as a technique for producing a differential thickness steel sheet without depending on welding, a technique for changing the sheet thickness while changing the roll gap of a rolling mill (for example, Patent Document 1) is also disclosed.

  However, in order to change the sheet thickness while changing the roll gap of the rolling mill, there is a problem that complicated roll gap control is required.

JP 2006-272438 A

  The object of the present invention is to solve the above problems and provide a technique for producing a differential thickness steel sheet without welding and without performing complicated roll gap control.

  The manufacturing method of the differential thickness steel sheet of the present invention made in order to solve the above-mentioned problem is that the cross-section is substantially circular by performing bending with a forming roll arranged in multiple stages while feeding the strip continuously. A roll forming step of forming a substantially circular cross-sectional material, and a step of conveying to a differential thickness forming apparatus constituted by a fixed die and a mandrel having a different diameter in the longitudinal direction without welding the end of the substantially circular cross-sectional material And a step of forming a difference thickness in the longitudinal direction of the substantially circular material in cross section by inserting and removing a mandrel inside the fixed die, and a previous roll forming process in order to eliminate the bending of the substantially circular material in cross section and form a band plate It is characterized by having a bending back forming process for eliminating the added bending.

  The invention according to claim 2 is the differential thickness forming apparatus used in the method of manufacturing the thick steel plate according to claim 1, wherein the mandrel driving means for driving the mandrel is disposed above the mandrel and outside the substantially circular material in cross section. The installed mandrel and the mandrel driving means are connected by a plate material arranged in a gap formed at an end of the substantially circular cross-sectional material.

  The manufacturing method of the differential thickness steel sheet according to the present invention is composed of a fixed die and a mandrel having different diameters in the longitudinal direction without welding the end portion after performing bending forming while continuously feeding the strip. In this case, the difference thickness is formed in the longitudinal direction of the substantially circular material by inserting and removing the mandrel inside the fixed die, and then bending and back forming are performed to control welding and complicated roll gap. The differential thickness steel sheet can be continuously manufactured without performing the above. That is, according to the present invention, it is possible to manufacture a differential thickness steel sheet with a low-cost and simple apparatus configuration as compared with the conventional method.

It is explanatory drawing of the previous process (I-III) of the manufacturing method of the difference thickness steel plate of this invention. It is a vertical sectional view of the differential thickness forming apparatus. It is a difference thickness steel plate schematic after fabrication.

Preferred embodiments of the present invention are shown below.
1 and 2, 1 is a strip, 2 is a forming roll, 3 is a mandrel, 4 is a mandrel driving means, 5 is a plate material, 6 is a fixed die, and 7 is an end of a substantially circular material in cross section after roll forming. The gap formed is shown.

  The method for producing a differential thickness steel sheet according to the present invention includes a roll forming step (hereinafter referred to as (I) step) for forming a substantially circular cross-sectional material, and transports it to the differential thickness forming apparatus without welding the end of the substantially circular cross-sectional material. Bending applied in the process (hereinafter referred to as (II)), the process of forming a differential thickness in the longitudinal direction of the substantially circular section material (hereinafter referred to as (III)), and the previous roll forming process. Has a bending back forming process (hereinafter referred to as (IV) process).

  In the step (I), while the strip is continuously fed, bending is gradually performed by forming rolls arranged in multiple stages to form a substantially circular cross section having a substantially circular cross section. What is necessary is just to use what is generally used for manufacture of an ERW steel pipe as a forming roll. In the ERW steel pipe production line, after forming a substantially circular cross-sectional material having a substantially circular cross section, a process is provided in which the end portions are butted and welded to form a tubular body. Are transferred to the next process without welding.

  In the step (II), the end of the substantially circular material in cross section is not welded, but is conveyed to a differential thickness forming apparatus including a fixed die 6 and a mandrel 3 having a different diameter in the longitudinal direction.

  As shown in FIG. 2, the die has a narrowed portion 10 with a narrowed diameter on the steel material conveyance direction side, and the mandrel 3 has a large diameter portion 8 and a small diameter portion 9. The mandrel large-diameter portion 8 is disposed in the dice restrictor 10 when the thin-walled portion is manufactured, and the mandrel small-diameter portion 9 is disposed in the dice restrictor 10 during the manufacture of the thick-walled portion.

  The mandrel driving means 4 for driving the mandrel 3 is installed above the mandrel 3 and outside the substantially circular material in section, and the mandrel 3 and the mandrel driving means 4 are formed in the end of the substantially circular material in section. 7 are connected to each other by a plate member 5 arranged on the plate.

  In the step (III), the mandrel is inserted / removed inside the fixed die so as to form a desired difference thickness, and the difference thickness is formed in the longitudinal direction of the substantially circular material in section.

  In the step (IV), in order to eliminate the bending of the material having a substantially circular cross section and form a strip, bending back forming that eliminates the bending applied in the previous roll forming step is performed. Although the specific means is not particularly limited, for example, a facility that gradually bends back with a multi-stage roll, or a facility that forcibly bends back with a guide rail, as in the roll forming step (I), is used. be able to.

  The obtained differential thickness steel plate has a thick plate portion 11, a thin plate portion 12, and a change-over portion 13, and the plate thickness is changed in the longitudinal direction. Different tailored blanks. According to the present invention, by simply changing the position of the mandrel, it is possible to continuously produce differential thickness steel plates having various thickness distributions, and to reduce the manufacturing cost of tailored blanks.

  The present invention will be described more specifically with reference to examples. The size of the steel plate having the difference thickness portion in the longitudinal direction to be manufactured this time is a thick plate portion 113 mm, a thin plate portion 122 mm, and a width 180 mm, the thick plate portion 11 is 500 mm long, the thin plate portion 12 is 300 mm long, and the variable portion 13 The length is set to 200 mm.

  A differential thickness steel plate was produced as shown in FIG. That is, for a 440 MPa class hot-rolled steel sheet 1 having a sheet thickness t = 3.0 mm, a sheet width W = 210 mm, and a length L = 5000 mm, an approximately 35 mm (diameter 70 mm) radius is obtained by the process (I) which is a roll forming process. A molded body having a circular cross section is formed.

  The roll forming stand used this time has two upper and lower U-bending rolls from the entry side, two bending rolls that give curvature to the plate 1 from the left and right, upper and lower, and three sizing rolls that form the shape into a semi-circular shape using the upper and lower rolls. It was. The material of the roll is SKD61 and chrome plating is applied. Further, the molding speed is 5 m / min and no lubricant is used.

  This molded body having a substantially circular cross section is provided with a gap 7 of about 10 mm in the upper part, and is inserted into the step (III) which is a differential thickness step. At this time, 10 mm as the gap 7 can be stably obtained by setting the plate thickness of the plate member 5 on the entry side for driving the mandrel 3 in the differential thickness step to 10 mm.

  Next, in step (III), which is a thickness difference step, as shown in FIG. 2, a molded body having a substantially circular cross section is inserted between the fixed die 6 and the movable mandrel 3, and the mandrel is moved in the longitudinal direction. The differential pressure steel sheet having a substantially circular cross section is obtained. The inner diameter of the fixed die was set to a radius of 35 mm (diameter 70 mm) on the entry side and a 50 mm change zone, and then set to a radius 30 mm (diameter 60 mm) on the exit side. The large diameter portion 8 of the mandrel had a radius of 28 mm (diameter 56 mm), and the small diameter portion had a radius of 25 mm (diameter 50 mm).

  At the time of forming the thick plate portion, as shown in FIG. 2, the mandrel 3 is moved from the fixed die 6 to the apparatus entrance side, and the state where the mandrel 3 is not in contact with the inner surface of the plate material is maintained. Then, after moving to the longitudinal direction of 500 mm, the mandrel 3 is moved at a speed of 10 mm / second in the device exit direction to form the removal changing portion 13, and then driven to the position at the time of manufacturing the thin plate portion of FIG. By thinning and holding, the thin plate portion 12 is formed.

  By repeating the above operation, a substantially circular differential thickness steel sheet can be obtained. Thereafter, these were flattened with a roll or a die and cut into a predetermined length of 1000 mm, whereby the differential thickness steel plate shown in FIG. 3 was obtained.

DESCRIPTION OF SYMBOLS 1 Band plate 2 Forming roll 3 Mandrel 4 Mandrel drive means 5 Plate material 6 Fixing die 7 Gap 8 Large diameter part 9 Small diameter part 10 Throttle part 11 Thick plate part 12 Thin plate part 13 Change part

Claims (2)

A roll forming step of forming a substantially circular cross-sectional material having a substantially circular cross-section by gradually bending with a forming roll arranged in multiple stages while continuously feeding a strip.
Without welding the end of the substantially circular cross-sectional material, the step of conveying to a differential thickness forming device composed of a fixed die and a mandrel having a different diameter in the longitudinal direction;
Forming a differential thickness in the longitudinal direction of the substantially circular material by inserting and removing the mandrel inside the fixed die; and
A method for producing a differential thickness steel sheet, comprising: a bending back forming step for eliminating the bending applied in the previous roll forming step so as to eliminate the bending of the substantially circular material in cross section to form a strip. It is a differential thickness forming apparatus used for the manufacturing method of the thick steel plate of Claim 1,
A mandrel driving means for driving the mandrel is installed above the mandrel and outside the substantially circular material in section.
The mandrel and the mandrel driving means are connected by a plate material disposed in a gap formed at an end portion of the substantially circular cross-sectional material.

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