JPS61108426A - Method for adjusting fin pass formation load in formation of electric welded steel pipe - Google Patents

Abstract

PURPOSE:To prevent the generation of the wedge wave of a blank pipe by equalizing and also by optimizing the upper and lower rolls loads of each fin pass roll stand, also by controlling within a fixed limit the bend stress caused in the longitudinal direction of the blank pipe. CONSTITUTION:The down-hill quantity of the lower roll 3 of fin pass rolls 1F, 2F, 3F is adjusted as per the following. Namely a load cell 4 is provided on the rolling reduction device part of the upper and lower rolls 2, 3 of a fin pass stand 1. The pass line of each fin pass roll 1F, 2F, 3F is set up by the adjustment of the upper and lower rolling reduction devices so as to be within the load range conforming to the equation from the measured value of the load cell 4. The generation of a wedge wave of the blank pipe can be thus prevented and the upper and lower rolls loads of the stand 1 can be equalized nearly. And the load level of the first fin pass upper roll which has hitherto been bigger in its load especially can be reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method of forming an ERW steel pipe in which the seam line extends parallel to the pipe axis, and more specifically, relates to a method of forming an ERW steel pipe in which the seam line extends parallel to the pipe axis. Fin pass forming cylinder 1 of the raw pipe in the forming process of the electric resistance welded steel pipe which is formed into a circular cross section after being bent and formed! It rA to the adjustment method.

[Conventional technology]

In general, for ERW steel pipes whose seam lines extend parallel to the pipe axis, a strip is cut in advance to the developed dimensions of the ERW steel pipe to be manufactured, and is sequentially formed into the desired shape using various forming rolls during rough and intermediate forming processes. The final forming process is a fin pass roll to form part of the seam edge stably, and it is made into a blank pipe with a predetermined shape and size. , J, and then welding the joints and notches using a squeeze roll.

Conventionally, in the arrangement of fin pass rolls in such tube forming, the pass lines are arranged horizontally. It was also thought that the loads on the upper and lower rolls were the same for each stand due to the law of action and reaction.

However, in the three-dimensional continuous forming method for ERW steel pipes, the strip during forming behaves as if it were a continuous beam, and the
When downhill molding is performed in the intermediate molding region, the behavior further becomes 111iIIk.

If the fin pass rolls, which are each fulcrum, are arranged so that the pass line is horizontal as in the past, the loads on the upper and lower rolls will be significantly different, causing edge waves, edge collapse, and bending of the strip. This may cause problems such as defects.

In order to solve these problems, we have developed a forming method that applies tensile stress to the strip by changing the rotation speed of the fin pass rolls, and we have improved the shape by installing a number of edge guide rolls between the fin pass rolls. There is a method, but the equipment becomes complicated and it is not a good idea.

[Problem that the invention seeks to solve]

The object of the present invention is to provide a method that most fundamentally solves the essence of the above problem by adjusting the fin bath forming load.

[Means for solving problems]

The present invention equalizes and optimizes the upper and lower roll loads of each fin pass roll stand, and suppresses the bending stress generated in the longitudinal direction of the raw pipe within a certain limit.

Each stand's unloading path is F'=p width.

PkFLB, ('=1, 2.3)Δ P 4
F = P iF 171 - P QF t81
When F~F=(PkF width+P=F+e+)/2, the present invention is as follows.

-10% ΔP IF/PIF<30%-100
%kuΔP 2F/ 1'2F< 10%-10%kuΔ
Adjust the downhill amount of the lower rolls of fin pass rolls IF, 2F, and 3F, that is, the pass line, so that Pxv/Fir<150% (1).

Adjustment of the downhill amount of the trawls of the fin pass rolls lF, 2F, and 3F is performed by installing a load cell 4 in the compression device of the upper and lower rolls 2, 3 of the fin pass stand 1 illustrated in FIG. The pass line of each fin pass roll is set by adjusting the vertical lowering device so that the load range conforms to the above formula.

The reason why the setting range of each fin pass stand is limited as described above is as follows. That is, when the load ia exceeds the above-mentioned load range, the bending moment in the longitudinal direction of the pipe in the fin pass forming area increases, and the action of compressive force on the edge of the raw pipe increases. For this reason.

This is to prevent edge waves from occurring in the raw tube on the first fin pass roll entry side and in the area between each fin pass roll stand.

〔Example〕

As shown in the ZI diagram, a load cell was installed in the upper and lower pressure device of the Finpass roll, and while measuring the load on each upper and lower roll, the downhill of the outer roll was adjusted to conform to the above formula (1). . Table 1 shows the results with and without the application of the present invention when downhill molding was performed in the intermediate molding area. Table 1 shows an example of the forming load ratio of the finpass ball roll in comparison with a comparative example and an example in which the trawl height was constant using conventional forming.

Table 1 Comparative example of fin pass forming load ratio Comparative example ΔP +r / PIF 9.7% 36
．． 1% ΔP = v / 72F 1.1%
-115%ΔPtw/P, F 17.9% 1
In the 68% example, no knee or sea waves occurred, but in the comparative example, sea waves and sea waves occurred at the pier in front of the 17th/pass roll IF.

〔Effect of the invention〕

According to the present invention, the generation of edge waves in the raw pipe becomes aT tm, and the 1. Troll 61■IIIt- can be made almost uniform and can reduce the load on the first fin pass upper roll, which conventionally had a particularly large load, so it can prevent molding or failure due to excessive load on the first fin pass roll. It is now possible to manufacture tube sizes using conventional equipment without modifying the stand.

[Brief explanation of drawings]

Since FIG. 1 is preferably used for implementing the present invention, t6
FIG. 3 is a top view of a fin pass roll stunt. l... Fin bath roll stand 2... Upper a-ru 3... Lower roll 4...
Load cell applicant: Kawasaki Steel Corporation Ono 1) Tsutomu 1 1″′″l! ”m″′″= i゛g
* :J Masu Physician Kazunori Saito Figure 1

Claims (1)

[Claims] 1. In a continuous forming method for electric resistance welded steel pipes, the downhill amount of the lower roll of the fin pass is set so that the difference ΔP_i_F (i=1, 2, 3) between the loads of the upper and lower rolls of the fin pass satisfies the following formula. A fin pass forming load adjustment method in forming an ERW steel pipe, which is characterized by adjusting the line. -10%<ΔP_1_F/@P@_1_F<30%-1
00%<ΔP_2_F/@P@_2_F<10%-10
%<ΔP_3_F/@P@_3_F<150% Here, ΔP_i_F=P_i_F_(_T_)−P_i_F_
(_B_) (i = 1, 2, 3) P_i_F_ (_T_): Load on the i-th fin path upper roll (i = 1, 2, 3) P_i_F_ (_B_): Load on the i-th fin path lower roll (i = 1, 2, 3) @P@_i_F=(P_i_F_(_T_)+P_i_
F_(_B_))/2(i=1,2,3)