JPS6068112A - Manufacture of welded pipe of titanium, zirconium, or its alloy - Google Patents

Abstract

PURPOSE:To improve the accuracy of a welded pipe of titanium, etc. and to prevent the wear of a roll by distributing an outer-diametral drawing rate to each roll while limiting the total drawing rate, from squeezing rolls to the final rolls of sizing, to the range of specified percentage. CONSTITUTION:A hoop 1 of titanium, etc. is formed into an open pipe after passing through forming rolls F1-F7, and a preparation work for welding is controlled by squeezing rolls SQ. A welded pipe welded in its longitudinal direction by a torch 2 of TIG welding, is passed through four stages of rolls F8-F11 having a cahiber with true roundness and is finished into the desired outer- diametral tolerance and out of roundness. At that time, when the total outer- diametral drawing rate, ranging from the squeezing rolls SQ to the final rolls F11 of sizing, is limited to 1-2%, and is distributed to each roll; the required accuracy of the out of roundness, etc. is obtained, and also the wear of roll due to excessive drawing rate is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a welded tube of titanium, zirconium, or an alloy thereof.

When manufacturing tubes made of titanium, zirconium, or their alloys (hereinafter referred to as titanium, etc.), a plate-shaped hoop of the material is passed between forming rolls to form an oven tube, and then the joining edge is squeezed with a squeeze roll. A method is known in which the tube is welded in the vicinity and then the outer diameter is adjusted using a plurality of sizing rolls to continuously form the tube in M shape. The amount of outside diameter reduction of welded pipes with the sizing rolls affects the outside diameter tolerance and roundness of the product, but sufficient consideration has not been given to the reduction of welded pipes such as titanium, and steel pipes and The experience with SUS pipes was directly utilized.

By the way, in the manufacture of welded titanium pipes, relatively soft copper alloy rolls are used to prevent seizure, so if the reduction amount (2 to 5%) of steel pipes etc. is applied, the sizing reduction amount will be reduced. There was a problem in that the copper alloy roll was larger than necessary and the wear of the copper alloy roll became severe.

The present invention has been made in view of the above points, and its purpose is to provide a necessary and sufficient outer diameter for adjusting the tolerance and roundness of the outer diameter of the pipe when manufacturing welded titanium pipes, etc. It is an object of the present invention to provide a method for manufacturing a welded pipe made of titanium or the like, which determines the amount of diameter reduction and applies it to a drawing roll such as a sizing roll, thereby preventing wear caused by unnecessary reduction of the roll.
:Ali, the gist is that after forming a plate-shaped hoop made of titanium, zirconium, or an alloy thereof into an open tube by passing it between forming rolls, welding the joining edge near the squeeze roll, After that, in a method of continuously manufacturing a tube by adjusting the outer diameter with a plurality of sizing rolls, the total amount of outer diameter reduction from the squeeze roll to the final sizing roll is set to 1 to 2%, and L7 is applied to each of the above rolls. It's all about distribution.

The present invention will be explained in detail below.

First, the outline of the manufacturing process of a welded pipe made of titanium or the like will be explained based on the embodiment shown in FIG.

In FIG. 1, (I) shows the forming process, and the forming process (■) involves rolling a strip of titanium or the like into a seven-stage forming roll (F).
1 to F7) to form a circular oven tube.

The middle side of Fig. 1 shows the welding process, and the welding process (n) is to weld the edge joints of the oven tube in the longitudinal direction after the forming process (■) is completed, and is used for open tube amplifiers. A squeeze roll (SQ) that controls the set amount and edge butt shape;
It consists of a TIG welding torch (2) placed either before or after the welding torch.

(III) in FIG. 1 shows the sizing process, in which the welded tube is passed through sizing rolls (F8 to F11) consisting of four rolls with perfect circular holes. O is used to finish the outer diameter tolerance and roundness. In the figure, (31 is the uncoiler 1 (S) indicates the side roll.

Next, in the gist of the present invention, we will explain in detail the reason why the total amount of outside diameter reduction from the squeeze roll to the final sizing roll is set to 1 to 2%. This is based on a mock test using the mold described below, which was conducted to understand the appropriate sizing conditions for titanium tubes (hereinafter referred to as titanium tubes).If the total reduction amount is less than 1%, the roundness cannot be improved. This is because if it exceeds 2%, the contact length between the roll and the tube becomes long and the roll wear becomes severe.

The method, results, and discussion of the mock test using the pear will be explained.

〔Test method〕

fl+ Sample material 2296X O,7- A titanium tube was molded with the sizing roll completely floating, and a tube with poor roundness was sampled immediately after welding and used as a sample material.0 (2) Test piece and mold The shape test piece used was one in which the test material was cut into approximately 50 mm pieces and the end surfaces were polished with emery paper.

In this experiment, carbon steel CSA5C with six types of perfect circular hole shapes was used.
mN) mold was used, and the hole diameter is shown in the first barley.

Table 1 also shows the nominal reduction ratio when rolling down using each mold, but these values were calculated from the average outer diameter of the test piece and the hole diameter. Because all of the test materials were sampled by continuous molding, all of the specimens used in this test had almost the same average outer diameter.

Table 1 Hole diameter of the six types of molds used (L%) Average outer diameter of d411' test piece (22,56 m
m) (31 Test method) The titanium tube was placed between the upper and lower molds with the welded part of the titanium tube always directly above, and rolled down in the vertical direction by a universal testing machine. In this case, the crosshead speed of the testing machine was 0.5. txm/
min, and the pressure was lowered until the upper and lower dies came into close contact and the load began to rise rapidly. In this test, using the mold shown in Table 1, the titanium tube was rolled down sequentially in the unlubricated state as ■→■→■→■→■→■, and the dimensions, roundness, rolling load, etc. It was measured.

[Test results and considerations]

FIG. 2 shows the relationship between the hole diameter and the outer diameter of the titanium tube after sizing. In the figure, the horizontal axis shows the hole diameter shown in Table 1 and the nominal drawing ratio (%), and the vertical axis shows the titanium tube outer diameter. The outer diameter of the titanium tube was measured by a six-point method, and the average value, maximum, and minimum values are all shown in the figure. In the figure, the outer diameter tolerance (
If you pay attention to the maximum diameter - minimum diameter), the outer diameter tolerance of the material is approximately 0.
．． 5 vIIl+ had a nominal aperture rate of 0.7%
If the pressure above is applied, it becomes 0.1B or less. On the other hand, the average outer diameter is slightly larger than the hole diameter, and the drawing ratio is 1%.
In the above, the difference between the two is uniformly about 007 addition. This value is considered to be mostly due to the elastic recovery of the titanium tube, since the elastic deformation of the hole shape can be ignored.This amount of elastic recovery is approximately 0.31% when converted to circumferential strain, and this value is Almost equal to the yield strain of titanium tube.

FIGS. 6(A) and 6(B) respectively show the roundness measurement diagram of the material tube before rolling and after rolling of the mold. Of course, profiles after rolling down of other types were also measured, but FIG. 6 is shown here as a representative example. In the figure, a indicates a welded portion, b indicates a profile, and C indicates a reference circle. Figure @4 shows the relationship between nominal aperture ratio and roundness.

The degree of small bends (irregularities) in the pronto tube was also shown by distinguishing the pronto marks. In other words, here, the degree of small bending is determined by the number of intersections between the roundness measurement diagram and the standard circle. indicates a case where the number of intersections is 4 to 5. According to Figure 6 (A)) and Figure 4, the roundness of the material is approximately 350/
'm, when the nominal drawing ratio is less than 1%, the roundness is large and the correction is insufficient, and when the nominal drawing ratio is 1% or more, the roundness is almost constant.
'm, and the small song is also corrected. The test results are for the case where the amount of reduction exceeds 2% (sequential reduction), but in a test similar to this test except for the order of reduction, a test in which the material is directly reduced by the desired mold (single reduction) was also held. A detailed explanation of the results in this case will be omitted, but the conclusion is that the results of outer diameter measurement and roundness measurement differed depending on the method in the case of sequential rolling and in the case of single rolling. FIG. 5 is a diagram showing the relationship between the rolling load during mold rolling and the clearance between the upper and lower molds. In the figure, the solid line and the broken line indicate the cases of sequential rolling and single rolling, respectively. Also,
The figure shows the point 0 (bl is the IJ point at the start of rolling down).
showing balance. From the figure, it can be seen that for the cloth subjected to sequential rolling and single direction rolling, in other words, the larger the drawing ratio is with one die, the rolling load begins to rise from the time point i- when the clearance is large. Applying this to the sizing roll, if the rolling reduction amount of one stand is increased,
The contact length between the titanium tube and the roll die surface becomes longer,
As a result, it is expected that the copper alloy rolls will experience increased wear. Therefore, it can be seen that distributing the appropriate drawing ratio equally to each stand is a good idea from the standpoint of preventing roll wear.

As for mock exams based on patterns, as mentioned above, there are
The results were confirmed by applying the amount of outside diameter reduction based on the above results to a real root sizing roll.

[Implementation method]

Using 31.75φ x 0.5゜ as the target titanium tube,
The actual machine used was one with four sizing rolls, as shown in Fig. 1. The rolls are stopped in the middle of forming, and each sizing roll (F8 ~
A titanium tube of Fu) i over a was sample-linked. The outer diameter and roundness of these titanium tube samples were measured, and the relationship with various sizing conditions was determined. Note that the upper and lower roll clearances were set to 0, and all new rolls (without wear) were used for pipe making.

[Implementation results and considerations]

The measurement results of the outer diameter tolerance and roundness of the titanium tube sample-linked as described above are shown in FIGS. 6(A) and 6(B).

In these figures, the horizontal axis represents the plastic reduction rate, and this value was calculated using the following formula.

lP-F/dBq-1l x 10 (1 (%), δF = plasticity rate, dF: average outer diameter of the titanium tube after passing through each sizing roll, dBQ, average outer diameter of the titanium tube after passing through the sizing rolls) The vertical axes indicate the outer diameter M (am') and the circularity Cμm), respectively.

As is clear from Fig. 6 (At (B)), the outer diameter tolerance,
The roundness decreases as the drawing ratio increases, and when the plastic drawing ratio is 0.5 to 0.6% or more, sufficient roundness (outer diameter tolerance) is achieved even when compared with the ASTM standard.

Therefore, from the results of this implementation, a value of 0.5 to 0.6% is obtained as the appropriate sizing reduction rate. As already mentioned, the elastic recovery strain of the titanium tube is approximately 0.6
If we estimate 1%, the appropriate sizing reduction rate (total strain) is 0,
81 to 0.91%, and this value is close to the result obtained in a mock test using a mold. From the above results, it was confirmed that the appropriate sizing reduction rate is 1 to 2% as described in the previous section.

Regarding this implementation, the above items were investigated for other titanium tubes, but similar results were obtained, and the above-mentioned 1 to 2% is applicable as an appropriate sizing reduction rate regardless of the size of the titanium tube. It has been found.

As described above, according to the method for manufacturing a welded pipe made of titanium or the like of the present invention, the total amount of outer diameter reduction from the squeeze roll to the final sizing roll is distributed to each roll as 1 to 2%. Diameter tolerance and roundness can be adjusted with high precision, and roll wear due to unnecessary rolling can be prevented, making it possible to extend the life of the roll. In addition, since the amount of outer diameter reduction can be clearly set, it is possible to optimally design the roll hole shape after the squeeze roll, taking the outer diameter reduction amount into consideration, and determine the appropriate hoop width. These incidental matters, which had previously been done through trial and error, can now be handled efficiently and contribute to improved productivity.

[Brief explanation of the drawing]

Figure 1 is a schematic process diagram showing the manufacturing process of welded titanium pipes, etc. Figure 2 is a diagram showing the relationship between the hole diameter and the nominal draw flat and the titanium tube outer diameter, Figure 6 (A) (B) Figure 4 is a diagram showing the relationship between the nominal drawing hand and roundness, Figure 5 is a diagram showing the relationship between the clearance between the upper and lower dies and the rolling load, Figure 6 (AJ (Bl is a diagram showing the relationship between plastic drawing!7*, outer diameter tolerance, and roundness. fi+... hoop, 12)... welding torch, Fl-
F7... Forming roll, SQ... Squeeze roll, F
8~Fll...Sizing roll. Figure 5 x'' F-type old υy lands Figure 6 (A) Snow βi principal element tlll 岑 (zujijunεpillar ki f'7) Procedural amendment (voluntary) June 13, 1982 Special Patent Application No. 178957 of 1982 2 Name of the invention Method for manufacturing welded pipes of titanium, zirconicum, or their alloys 3 Relationship with the Nagisa incident of wearing T-sleeves Special 1f FIFJ Applicant (119) Kami P Steel Works Co., Ltd. 4 Agent Cloud 577 (1) In the 15th line of page 8 of the specification, is there ``Phase of maximum deviation (unit: pm) J?'' ``Phase of maximum deviation f (unit: pm) J
I am corrected.

Claims (1)

[Claims] l. A plate-shaped hoop made of titanium, zirconium, or an alloy thereof is passed between forming rolls to form an oven tube, and then the joining edge is welded near the squeeze roll, and then multiple In a method of continuously manufacturing pipes by adjusting the outside diameter using several sizing rolls, the total amount of outside diameter reduction from the squeeze roll to the final sizing roll is distributed to each roll as 1 to 2%. A method for manufacturing a welded pipe of titanium, zirconium, or an alloy thereof. 2. The method for manufacturing a welded pipe of titanium, zirconium, or an alloy thereof according to claim 1, wherein the distribution is approximately equal.