JPS6289521A - Manufacture of curved steel material - Google Patents

Abstract

PURPOSE:To blank out steel belts to be formed to a curved steel material from a steel plate without unavailing by melt cutting each steel belt to constitute the curved steel material from the steel plate in the shape of straight line that is the stretched shape of the curved steel belt and to combine into specific sectional shape, then heating to curve. CONSTITUTION:As the straight steel material is curved by an extruder 13, loaded on a conveyer 14 and its top end is passed through a heat generating heater 16 to a chuck 18. At bending the intermediate part, the top end of that bending part is fixed oppositely to the heat generating heater 16 and a feeding device 15 is driven to extrude the steel material. The periphery of the steel material opposed to the heat generating heater 16 is red heated in a narrow width, and in accordance with its extruding, a guide bar 19 is rotated to bend the straight steel material and to cool quickly with water.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to a flexible arm such as a boom of an excavator,
The present invention also relates to a method of manufacturing a curved steel material used for the skeleton of a center used in tunnel construction or a curved steel frame for buildings, which is formed into a desired cross-sectional shape by welding.

[Conventional technical background and its problems]

As shown in Figure 1, the boom of an excavator car has a shape that gradually becomes thicker in a straight line from the base end, curves in the middle, and then tapers in a straight line, and is a hollow body with a rectangular cross section. It is. When manufacturing this boom, the straight parts at both ends and the curved part in the middle are separately formed and welded together, and each strip plate that makes up the straight part and the curved part is melt-cut from a steel plate. It is constructed by welding each band-shaped plate to each other.

By the way, when each of the above-mentioned strip plates is obtained by melt-cutting a steel plate, there is no problem with straight sections, but when cutting curved strip plates, they are taken in a curved form according to the design, so it is difficult to cut straight sections. Unlike the previous model, there was a large loss in the cutting process, which resulted in a large amount of wasted material.

In addition, in recent years, with the development of computers, it has become possible to accurately calculate the desired strength of building materials such as H-shaped steel, and steel materials with the required strength are often formed with welded structures. There has been an increasing demand for curved members, but when welded steel materials are cold bent, there is a problem in that the welded parts become brittle and the required strength cannot be obtained.

[Purpose of the invention]

This invention was developed to solve the above problems, and even if the desired curved steel material has an irregular shape, it is possible to cut out the strip-shaped plate constituting the steel material without waste from the steel plate. Another object of the present invention is to establish a manufacturing method that reliably maintains a predetermined strength.

[Summary of the invention]

The method for manufacturing a curved steel material according to the present invention includes melt cutting each of the strip plates constituting the desired curved steel strip from a steel plate in a shape obtained by stretching the curved shape into a straight line, and then welding each of the cut linear strip plates. Combined into a predetermined cross-sectional shape by means,
It is manufactured by bending the assembled straight steel materials using high-frequency induction heating. By the way, 1. For example, when forming a linear strip plate with a uniform shape such as H-beam steel, it is sufficient to cut both edges in the longitudinal direction in a straight line parallel to each other by melting, but even if the plate is unequal and stretched straight, it will not form a circular arc. When obtaining a linear strip plate in which It is formed into a shape drawn by a curved line with approximately the same length as the circumference of the outer circle.

[Embodiments of the invention]

Figures 1 and 2 show the boom of an excavator car, and assuming that this is a curved steel material 1 to be manufactured, a curved strip plate 2 that becomes the side wall is extended into a straight line as shown in Figure 3. The straight strip plate 3 is cut by melting from a steel plate.
is obtained from the curved strip plate 2 drawn according to the design.

As shown in FIG. 4, the curved band plate 2 has straight parts 5, 5 tapered at both ends of an intermediate curved part 4, and furthermore, the inner circle 6 and the outer circle 7 of the curved part 4 are The upper edge 8 and lower edge 9 of the straight portion 5 protrude as an extension of the tangent to the circle.

Therefore, when forming the curved portion 4 as a linear strip plate 3, the central angle α of the inner circle 6 in the curved portion 4 is divided equally or into arbitrary angles, and the intersection points 01 to On with the inner circle 6 are and points P1 to Pn where the divided line is extended and intersects the outer circle 7
get. The inner circle 6 in FIG. 4 is drawn as a straight line 6' as shown in FIG. 5, and this straight line 6' is drawn to an arbitrary length. Next, a temporary line is drawn perpendicular to one point of the straight line 6', and a point Q□ is obtained by placing a height Q□ between points O and P□ in FIG. 4 on the temporary line. Next, use a compass to measure the shortest distance a□ between points P□ and 22 in Figure 4, draw a temporary arc with the compass centered around point Q1 in Figure 5, and draw a straight line 6.
From ', raise the height Q2 between points o2 and 22 in Figure 4 at a right angle and find the point Q2 that intersects the temporary arc 6 Furthermore, from point Q2°, the length a2 between points P2 and 23 in Figure 4 Draw a temporary arc again using the compass you took, and draw a straight line 6′ as before.
From this, a point Q3 is found on the temporary arc using the height Q3 between points o3 and 23 in FIG. The final Qn is determined in this way, and the curved portion 4' is obtained by connecting each point Q-Qn with a curve 9'. The curve 7' connecting the points Q and -Qn is approximately equal to the circumferential length of the outer circle 7 in FIG. 4, and the more finely divided the central angle α is, the closer the length can be to the same length. Further, the length of the straight line 6' is longer than the circumferential length of the inner circle 6.

Next, when drawing the straight line part 5, as shown in FIG. 〜Tn, and as shown in FIG. 5, point 01 in FIG. 4, Sl, S, and S2... Sn Points S at intervals of the same size as each interval of
j...Sn, draw a temporary line that intersects at right angles from each point S~Sn in Figure 5, and mark each temporary line with the height h in Figure 4.
The upper edge line 8' is obtained by finding points Ti to Tn by sequentially taking points T1 to Tn in FIG. 5 and connecting the points T1 to Tn in FIG.

The ends of the upper edge line 8' and the lower edge line 9' have a radius r shown in FIG.
connected by an arc of

The above-mentioned straight strip plates 3 serve as the side plates of the boom, and in addition to these, curved strip plates 10 and 11 are required as the upper and lower plates as shown in FIG. The linear strip plate 3 serving as the lower plate may be formed into a flat plate as shown in FIG. Then, it is bent and formed using a roll or press.

Straight steel material 1 which becomes the base material of the desired curved steel material by combining each of the above linear strip plates into a predetermined cross-sectional shape by welding.
Mold 2.

Next, Figures 6 and 7 show a curved steel member 1' which has an H-shaped cross section and the height h between the outer circle and the inner circle is equal over the entire length, and the straight steel member 12' is shown in Figs. To obtain it, you can obtain it in the same way as the above-mentioned inequality, but as shown in Fig. 8, the sixth
Straight strip plates having the same dimensions as the height h in the figure and the circumference length of the outer circle are formed and assembled into an H shape by welding.

In order to form the straight steel material 12, 12' formed as described above into the desired curved steel material 1, 1'', the extruder 13 shown in FIG. Roller conveyor 14 on which steel material 12.12' is placed
and a feeding device 15 that pushes the steel material 12, 12' in one direction in the longitudinal direction, a heating heater 16 using high frequency induction in front of the tip of the conveyor 14, a cooling device 17 that injects water from the outer periphery of the heating heater 16, and a cooling device 17 at the tip. It has a bending device 20 which is rotatably provided with a guide rod 19 equipped with a chuck 18.
．． 12' in cross-section, and the bending device 20 is moved along the rail 21 and fixed in a predetermined position.

To bend the straight steel material 12 with this extruder 13, the straight steel material 12 is placed on the conveyor 14, and the tip is bent with the heating heater 1.
6 and pass it through the chuck 18, but the straight steel material 1
2, the tip is fixed to the chuck 18; however, when bending the middle section, the tip of the section to be bent is fixed to the heating heater 16 facing oppositely. Therefore, the heat generating heater 16 is energized, the feeding device 15 is driven, and the steel material 1 is
When 2 is extruded, the outer periphery of the steel material facing the heating heater 16 is heated to a red-hot state in a narrow width, and as the guide rod 19 rotates as it is extruded, the straight steel material 12 is curved and quenched with water. It is something that will be done. The radius of the curve is determined by the length of the guide rod 19, and this radius is defined by the radius of the inner circle 7 in FIG.

When the straight steel material 12 is curved in this way, the outer circle 8 of the curved steel material 1 does not extend and is finished with the length of the original curved line 8', and the inner circle 7 is shrunk from the original length of the straight line 7''. It is molded to be thicker due to shrinkage.

〔Effect of the invention〕

The method for manufacturing a curved steel material according to the present invention involves forming a straight steel material with a welded structure extending in a straight line, and then bending it by high-frequency induction heating. Since each curved strip plate is extruded into a straight line and cut by melting from a steel plate, the proportion of waste left from the steel plate is extremely reduced, and the yield can be significantly improved. Furthermore, when cutting the board, the cutting is done in a straight line or a line close to a straight line, so the cutting operation can be performed very easily. Furthermore, since the steel material of the welded structure is heated in a narrow width by high-frequency induction heating and immediately quenched after being bent once, internal stress is removed, the structure of the welded metal becomes dense and uniform, and the surface hardens. It can be manufactured with even higher strength.

[Brief explanation of drawings]

Fig. 1 is a side view showing a curved steel material formed by the manufacturing method according to the present invention, Fig. 2 is a sectional view taken along the line ■-■ in Fig. 1;
Fig. 3 is a perspective view showing each straight band plate cut out from a steel plate, Fig. 4 is a front view showing a curved band plate given by design, and Fig. 5 is a diagram obtained from the shape shown in Fig. 4. 6 is a front view showing another example of curved steel material, FIG. 7 is an enlarged sectional view taken along the line ■-■ in FIG. 6, and FIG. 6 is a front view showing a straight steel material from which the steel material shown in FIG. 6 is obtained, and FIG. 9 is a plan view showing an extruder using high frequency induction heating. DESCRIPTION OF SYMBOLS 1... Curved steel material, 2... Curved strip plate, 3... Straight strip plate, 4... Curved part, 5... Straight part, 6...
・Inner circle, 7...outer circle, 8...upper edge, 9...lower edge,
10.11. ... Curved strip plate, 13... Extruder, 14... Roller conveyor, 15... Feeding device,
16... Heat generating heater, 17... Cooling device. 18... Chuck, 19... Guide rod, 20...
Bending device, 21... Rail Fig. 1 M5 Fig. 4

Claims (1)

[Scope of Claims] When manufacturing a desired curved steel material in which a plurality of strip plates are formed into a desired cross-sectional shape by welding means and are curved along a longitudinal direction, the following steps are required: 1) curvature drawn in a desired circular arc; Between the outer circle and the inner circle of the curved strip plate, the inner circle side is a straight line, and from the straight line, the distance between the outer circle and the inner circle of the desired curved strip plate is approximately the same length as the circumference of the outer circle. 2) Straight steel material obtained by welding each linear strip plate according to the desired cross-sectional shape is cut by high frequency induction in a narrow width around the outer periphery of the steel material. 1. A method for producing a curved steel material, characterized in that heating is applied sequentially to sections to be curved, the heated portion is curved to a desired curvature, and is rapidly cooled.