JPS61180612A - Manufacture of spiral steel tube having projection - Google Patents

Abstract

PURPOSE:To make squashing of projections as small as possible and prevent lowering of adhesion of concrete by adding force that sends a steel tube having projections in a forming machine at plural places. CONSTITUTION:The spiral steel tube 1 having inside projections is made by rewinding a coil by an uncoiler, flattening a steel plate 10 having projections by a leveler 12, prebending the edge part by a prebender 14 and sending into a forming machine 15. At this time, sending force of the steel plate 10 having projections is applied by driving rolls 23 arranged between the leveler 12 and prebender 14. The driving rolls 23 are constituted of three sets of rolls 23. Sending force of the steel plate 10 having projections is dispersed to three places and rolling force applied to individual roll 23a is made small, and thus, squashing of projections is made as small as possible.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a spiral steel pipe with projections.

The development of steel pipes with protrusions as composite pile pipes is progressing. This is an attempt to improve the strength of the pile by combining steel pipes and concrete.

Examples of steel pipes with projections include a steel pipe with internal projections 1 and a steel pipe with external projections shown in FIG. Since concrete adhesion efficiency is higher when the protrusion 2 has an inclination angle α (10 to 45°) with respect to the pipe axis direction, a spiral pipe is formed using a hot-rolled steel plate with protrusions. This is commonly done. The shape of this protrusion 2 is a trapezoid shown in FIG. 3, and its dimensions are, for example, a top width W10n and a height h.
&Om, the angle is 045 to 60', and the pitch is p35m. In order to obtain the optimum concrete adhesion efficiency, the height h must be greater than &Ow, and must not be crushed during pipe making.

Now, as shown in FIG. 4, the spiral steel pipe is manufactured by unwinding the coil with an uncoiler 11, flattening the steel plate 10 with a leveler 12, prepending the edges with a prepender 14 to prevent peaking, and sending it into a forming machine 15. We are making pipes. In this case, the force for feeding the steel plate 10 is applied by a drive roll 13 disposed between a leveler 12 and a prepender 14. Do9 (Brawl 13
As shown in FIG. 5, a pair of rolls 13a, 1S
A rolling blade pm is applied between the rolls 13a and 13a, and the roll 13a is rotationally driven by a motor (not shown), so that the steel plate 10 is fed into the forming machine 15 by the frictional force between the roll 13a and the steel plate 10. This feeding force must be larger than the sum of the coil unwinding force in the uncoiler 11, the pushing force to the repeller 12, the bripender 14, and the forming machine 15, and the bearing resistance of each device, and the thickness of the steel plate 10 must be 16 m. If it exceeds, when the friction coefficient is set to 0.35 to 0.40, the required rolling blade Pm will be 100 to 200 m. On the other hand, when calculating the amount of crushing of the protrusions from the shape and number of protrusions 2, the protrusion width 3
fl, the number of protrusions is 38, and the diameter of the roll 13h is 500 dens, and the allowable crushing height is 0.3.
As shown in Figure 6, the deformed area is 24.5X3X38=
2793m".Here, the yield stress σy of the steel material is
28 Kg/m”, the crushing height is 0.3
In order to set it to rm, it is necessary to make the reduction blade Pm within 78 tlB. Therefore, if the steel plate 10 is thick, the projections 2 will be crushed.
It was supposed to reduce the adhesion performance of concrete.

As a countermeasure to this, we considered the amount of crushing during pipe manufacturing,
It may be possible to increase the height of the protrusion during hot rolling, but
This is not preferable because it puts a considerable burden on the hot rolling operation.

This invention aims to solve the above-mentioned problems and to provide a method for manufacturing a nine-pronged spigilled steel pipe. This is how it was done.

An example of an apparatus for carrying out the method of this invention is shown in FIG. This device differs from the one shown in FIG. 4 in that the drive roll 23 is composed of three sets of rolls 23&. By applying the force to feed the steel plate 10 into the forming machine 15 in a distributed manner at three locations, the reduction blades acting on the individual rolls 23a can be made smaller, and the amount of crushing of the protrusions can be minimized.

For example, by adding the required metalworking lower blade Pm200 in three parts, the lowering blade borne by one set of rolls 23a can be made within 7Qttn, and the crushing amount of the protrusion having the dimensions and shape of the above example can be reduced to 0. It can be within 31.

The method for producing a spiral steel pipe with projections according to the present invention is as described above, and the crushing of the projections during pipe manufacturing can be minimized as much as possible. This can prevent deterioration in concrete adhesion performance when forming a composite pipe with concrete.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing an example of equipment for carrying out the method of the present invention, Figures 2 (a) and (b) are cross-sectional views and vertical cross-sectional views of a steel pipe with internal projections, and Figure 3 is an explanation of the shape of the projections. 4 is an explanatory diagram of conventional pipe making equipment, FIG. 5 is an enlarged explanatory diagram of the drive roll of FIG. 4, and FIG. 6 is an explanatory diagram of the amount of crushing deformation of the protrusion. Applicant's agent Patent attorney Takehiko Suzue Figure 4
Figure 1 Figure 3 Figure 5 Manufacturing method 3, relationship with the case of the person making the amendment Patent applicant (412) Nippon Kokan Co., Ltd. 4, agent 5, voluntarily amended” is corrected to “2.511I11 or higher.” (2) r 0.3 stated on page 3, line 13 of the same as above.
Correct "m" to "r O, 3w or less".

Claims (1)

[Claims] A method for producing a spiral steel pipe with protrusions, characterized by applying force at multiple locations to feed the steel plate with protrusions into a forming machine.