JPH07214111A - Method for operating roll of three-roll reducer - Google Patents

Abstract

PURPOSE:To reduce the roll cost by converting cutting both the groove-bottom part of roll and edge part of each grooved roll of stands into an intermediate roll for relevant stand and the stand of the preceding stage and using that roll for these stands. CONSTITUTION:Both the groove-bottom part and edge part of each grooved roll 1 of the stands are converting cut into the intermediate roll for relevant stand and the stand of the preceding stage and that roll is used for these stands. Consequently, the roll is converting cut about twice into the intermediate roll until the roll is converting cut into the dimensions of the grooved roll for these stands, usable for these stands and the number of rolling pass of each roll until the roll is converting cut into the dimensions of the grooved roll for the preceding stand is remarkably increased and the roll consumption unit is improved. Furthermore, the effect on the seamless tube of a product by using the roll which is converting cut into the intermediate roll for these stands is not a problem especially in all the dimension of outside diameter, degree of ellipse and ellipticity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roll operating method of a three-roll reducer for drawing and rolling a stretched mother pipe in the manufacture of a seamless pipe by a Mannesmann-mandrel mill system.

[0002]

2. Description of the Related Art A manufacturing process for a seamless pipe is performed by heating a round or square billet and then piercing it, a thinning process of stretching and rolling the pierced hollow shell, and a predetermined finishing of the stretched mother pipe. It consists of a constant diameter rolling process of drawing and rolling to size.
Known rolling mills in the thickness reduction process include a plug mill, a mandrel mill, an assel mill, and a pilga mill. Among the seamless pipe manufacturing methods, the Mannesmann-Mandrel mill method, which has excellent productivity, heats a round billet of the material to 1200 to 1260 ° C in a rotary hearth type heating furnace, and then punches it with a plug and roll with a punching machine. Roll to make a hollow shell. The hollow shell at this stage has an outer diameter of several sizes and a very large wall thickness as compared with the product.

In the mandrel mill for the next step of reducing the wall thickness, roll stands incorporating a pair of hole type rolls are placed at 90 ° to each other.
The roll arrangement is changed by 4 to 8 units continuously, and thinning and stretch rolling are continuously performed to a predetermined wall thickness between the mandrel bar inserted in the hollow shell and the hole rolls. Normally, the mandrel mill is generally subjected to a reduction of about 7 to 15 mm in order to reduce the roughness of the inner surface. The mandrel bar is pulled out from the thickness-reduced and stretch-rolled mother tube by a stripper (not shown). If the temperature of the blank tube is too low compared to the workability before thinning and drawing rolling, the mother tube is heated to 900 to 1100 ° C in a reheating furnace, but if the temperature does not drop, it is drawn and rolled. Machined to reduce the outer diameter and adjust the wall thickness a little to finish it to a specified finish size.

A three-roll outer diameter reducing mill such as a three-roll reducer has a stand arranged so that the angle formed by the rolling direction of each roll is 120 ° in a plane perpendicular to the rolling direction. The rolls are alternately arranged by shifting the rolling direction by 60 ° between the adjacent stands, and the number of main stands is determined by the working degree. Adjust the wall thickness,
Finish 3 to 4 stand to finish to the desired product size.
The above-mentioned three-roll outer diameter reduction rolling mill is economical because it can integrate the outer diameter setup of the mandrel mill because it can obtain a high degree of outer diameter processing, and can omit tools and improve productivity. In many cases, it does not have a roll gap changing mechanism for adjusting the reduction amount as compared with a two-roll rolling mill.

For this reason, a three-roll outer diameter rolling mill having no roll gap changing mechanism is used in a stand which is used when the roll is abraded, the surface of the roll is roughened, and seizure is generated at the edge portion. Since the rolls of the former stand are modified, the roll modification amount becomes excessive and the roll unit consumption deteriorates. The outer diameter workability per single stand of the three-roll rolling mill is about 4 to 7%. For example, in the case of a hole type roll having an outer diameter of 100 mm, the hole type of the stand and the stand in the preceding stage is 100 mm ×
(0.04 to 0.07%) = 4 to 7 mm average cutting is required. The hole rolls of the three-roll rolling mill are sequentially re-cut and reused as large hole rolls, but the number of rolling passes in one use is 2000 to 5000 passes.
The average roll-cutting amount of the hole-type roll used in the mill for producing seamless pipes of various sizes having a finished outer diameter of 27.2 to 139.8 mm is 2 to 3 mm.

The rolls of a three-roll rolling mill are usually modified by using a special lathe that can simultaneously modify three rolls with a circular disc bite, or by individually modifying the rolls by an NC lathe. As shown in FIGS. 1 and 2, the method of simultaneously cutting three rolls with a circular disc bite is such that the circular disc bite 2 and the roll 1 located at the offset L from the center of the roll 1 are rotated and rotated. To do. At the time of cutting a perfect circular hole type, the offset L is set to 0, but by changing the offset L, a hole type having an arbitrary ellipticity can be obtained.

When cutting the roll edge radius Ai and roll groove bottom radius Bi of the roll-shaped roll as shown in FIGS. 1 and 2, the cutting of the roll-shaped roll by the disc cutting tool is made as follows: , And the roll diameter is D, DC = Bi−Aicos 60 ° + (Ai ² −Bi ² ) / D
+ (Ai ² sin ² 60 °) / {Bi-Aicos 60 °
+ (Ai ² −Bi ² ) / D} L = √ {[(D / 2) −Bi] ² − [(D / 2) − (D
C / 2)] ² } can be uniquely determined.

[0008]

Table 1 shows an example of the hole shape of the hole type roll in the case of hot drawing a mother tube having an outer diameter of 151.0 mm to a diameter of 101.6 mm. The hole type rolls shown in Table 1 have a roll phase of 60 ° between adjacent stands.
Shift, No. Main stand consisting of 1 to 7 stands and No. It is assembled into a finishing stand consisting of 8 to 10 stands. The roll of the three-roll drawing mill incorporating this hole-type roll is refurbished when rough surface of the roll or seizure of the edge portion occurs. For example, No. Roll of 6 stands will be No. It is remodeled into a 5-stand roll hole type. In this case, the cutting allowance is (11
It becomes 9.0-111.5) /2=3.75 mm. Assuming that the number of rolling passes up to reworking is N, the milling unit per rolling at the roll groove bottom is 3.75 mm / N in this case.
Becomes The three-roll drawing mill having no roll gap adjusting mechanism has a drawback that the above cutting is inevitably generated.

[0009]

[Table 1]

The object of the present invention was made in view of the above circumstances, and provides a roll operating method of a 3-roll reducer capable of significantly improving the roll unit in a 3-roll drawing mill without a roll gap adjusting mechanism. Especially.

[0011]

[Means for Solving the Problems] The inventors of the present invention have made extensive studies to achieve the above object. As a result, in the reshaping of the hole-type rolls of the three-roll drawing mill without the roll gap adjusting mechanism, the hole-type rolls of each main stand are used as intermediate rolls between the stand and the preceding stand, with both the roll groove bottom and the edge. By revamping and using it on the stand, the roll unit can be greatly improved, and if the hole roll size of the finishing stand is maintained at the standard size, the outer diameter of the product seamless pipe after drawing rolling can be improved. It was confirmed that the ellipticity and ellipticity were not particularly problematic, and the present invention was reached.

That is, according to the first invention of the present application, in the reshaping of the hole-type rolls of the three-roll outer diameter reduction rolling machine having no roll gap adjusting mechanism, the hole-type rolls of each main stand are provided at both the bottom and the edge of the roll groove. The roll operation method of the three-roll reducer is characterized in that the roll is modified into an intermediate roll between the stand and the preceding stand and used in the stand.

Further, according to the second invention of the present application, in the reshaping of the hole type rolls of the three-roll outer diameter reduction rolling machine which does not have the roll gap adjusting mechanism, the hole type rolls of each main stand are provided with both the roll groove bottom portion and the edge portion. , The intermediate roll between the stand and the preceding stand is used for the stand, and the hole-type roll of the first finishing stand is cut to bring it closer to the regular reduction amount. It is a role operation method.

Further, according to the third invention of the present application, in the reshaping of the hole type rolls of the three-roll outer diameter reduction rolling machine which does not have the roll gap adjusting mechanism, the hole type rolls of each main stand are provided at the bottom and the edge of the roll groove. The feature is that the roll is modified to be an intermediate roll between the stand and the preceding stand and used in the stand, and a roll gap adjusting mechanism is provided in at least the first finishing stand to adjust the roll gap so as to approach the regular reduction amount. This is the roll operation method of the 3-roll reducer.

[0015]

In the first invention of the present application, the hole type roll of each main stand is provided at both the bottom and the edge of the roll groove.
Remodeled to an intermediate roll between the stand and the front stand,
By using the stand, the hole roll of the stand can be used as the intermediate roll about twice before it is cut to the size of the hole roll of the former stand. The number of rolling passes of each roll until it is cut to the roll size is significantly increased, and the roll unit can be greatly improved. Moreover, the effect on the product seamless pipe by modifying the intermediate roll and using it on the stand is such that the outer diameter dimension, the ellipticity, and the ellipticity are not particularly problematic.

Further, in the second invention of the present application, the hole type roll of each main stand, both of the roll groove bottom portion and the edge portion, is reworked into an intermediate roll between the stand and the preceding stage stand, and the roll is used in the stand. , Until the hole roll of the stand concerned is modified to the hole roll size of the former stand, it can be modified to an intermediate roll about twice and used on the stand, until it is modified to the hole roll size of the former stand. The number of rolling passes of each roll can be significantly increased, and the roll unit can be greatly improved. Also, 1
By modifying the hole-type roll of the 2nd finishing stand so as to approach the regular rolling amount, the rolling load at the time of shifting from the final main stand to the 1st finishing stand by using the intermediate roll in each main stand is reduced, The seizure of the edge can be prevented.

Further, according to the third aspect of the present invention, the hole type roll of each main stand is refurbished into an intermediate roll between the stand and the preceding stand, both of the roll groove bottom portion and the edge portion, and used in the stand. , Until the hole roll of the stand concerned is modified to the hole roll size of the former stand, it can be modified to an intermediate roll about twice and used on the stand, until it is modified to the hole roll size of the former stand. The number of rolling passes for each roll of
The roll unit consumption can be greatly improved. Also,
At least the first finishing stand is equipped with a roll gap adjusting mechanism, and by adjusting the roll gap so as to bring it closer to the regular reduction amount, the transition from the final main stand using the intermediate roll to the first finishing stand is performed at each main stand. The rolling load is reduced and seizure of the roll edge can be prevented.

In the present invention, the regular hole roll of each main stand is modified into an intermediate roll. The radius of the edge of the hole of the intermediate roll is Ai × 2 and the groove bottom radius is Bi × 2.
Is designed so as not to exceed 1.5% in comparison with the regular hole type, and is cut using the same circular disc bite. Further, the hole roll of the first finishing stand in the present invention is modified so as to approach the regular reduction amount, for example, when the regular hole roll of each main stand is modified twice. The rolling amount at the edge part is a normal roll and is twice the radius of the roll groove bottom of the final main stand (2Bi) to twice the radius of the roll edge part of the first finishing stand (2A).
In the range where the value obtained by subtracting i) does not exceed twice as large as 0.6 mm, the roll edge radius Ai of the first finishing stand.
, The seizure of the roll edge of the first finishing stand has no practical problem.

Further, if a housing having a gap adjusting mechanism is used for the roll of the first finishing stand,
Even if the regular hole type rolls of each main stand are modified twice, the rolling amount at the edge part is the regular roll and the roll groove bottom radius of the final main stand is twice (2Bi) to the first finish. Adjust the roll position so that the value obtained by subtracting twice the roll edge radius of the stand (2Ai) does not exceed twice the 0.6mm roll edge radius of the first finishing stand. As with the above, the seizure of the roll edge of the first finishing stand has no practical problem. As the gap adjusting mechanism for the roll of the first finishing stand in the present invention, an eccentric ring that supports the outer circumference of a bearing that supports the roll shaft is rotated by a worm shaft to rotate a cylinder or a worm wheel to adjust the roll reduction amount. Method (Actual Kaihei 4-6440
6, Japanese Utility Model Laid-Open No. 4-64407, Japanese Patent Laid-Open No. 58-
25805, JP-A-60-18208, etc.)
Alternatively, a method of rotating the reduction screw by a screw reduction device (JP-A-5-96308, etc.) can be mentioned.

[0020]

EXAMPLES As shown in Table 2, No. Main stand consisting of 1 to 7 stands and No. In a three-roll drawing and rolling machine consisting of finishing stands consisting of 8 to 10 stands, a regular roll in Table 2 was used to hot-roll and draw a mother tube having an outer diameter of 151.0 mm to an outer diameter of 101.6 mm. After 3200 passes, the roll of the main stand had rough skin and edge seizure. Therefore, No. The roll of the main stand consisting of 1 to 7 stands was refurbished by using the same circular disc bite as the hole type shown in the intermediate roll (1) column in Table 2, and the same use was made on the stand, and the outer diameter 151 When a mother tube of 0.0 mm was hot-squeezed and rolled to an outer diameter of 101.6 mm, the intermediate roll (1) had two rolling passes.
Rough skin and edge seizure occurred after 800 passes. Furthermore, No. The roll of the main stand consisting of 1 to 7 stands was refurbished using the same circular disc bite as the hole type shown in the intermediate roll (2) column in Table 2, and the same outer diameter 151 When a mother tube of 0.0 mm was hot-squeezed and rolled to an outer diameter of 101.6 mm, the intermediate roll (2) had roughened rolls and edge seizure after 2700 rolling passes. When this intermediate roll (2) is used, No. 1 which is the first finishing stand is used. 8
The roll of the stand is No. 1, which is the final main stand.
No. 7 which is the first finishing stand from twice the groove bottom radius Bi of the regular roll of 7 stands. The value obtained by subtracting twice the edge radius Ai of the roll of 8 stands is -0.6 mm.
It was used after being modified. The results are shown in Table 3.
The roll material used was chilled for both the main stand and finishing stand.

[0021]

[Table 2]

[0022]

[Table 3]

As shown in Table 3, the number of rolling passes until surface roughening and edge seizure on each roll of the main stand was 3200 for the regular roll and 280 for the intermediate roll (1).
0, Intermediate roll (2), 2700 passes, 87 in total
I could roll up to 00 passes. On the other hand, 5500 more passes could be rolled compared to the conventional method of 3200 passes in which the regular rolls were cut into the rolls of the front stand. As a result, the conventional roll unit is 100 mm with a groove bottom average cutting allowance of 6.6 mm when the regular roll is recut into the roll of the front stand.
2.06 mm per 0 pass, while 10
It is 0.76 mm per 00 passes, which is about 3 times better. In addition, the obtained seamless pipe had a level of no problem in use in terms of average finished outer diameter, ellipticity, and ellipticity.

[0024]

As described above, according to the method of the present invention, it is possible to greatly improve the basic unit of the hole type roll of the three-roll drawing mill, and to significantly reduce the roll cost in the seamless pipe manufacturing. be able to.

[Brief description of drawings]

FIG. 1 is a front view showing a roll hole type cutting situation by a circular disc bite.

FIG. 2 is a side view showing a roll hole type cutting situation by a circular disc bite.

[Explanation of symbols]

 1 roll 2 disc bite Ai roll edge radius Bi roll groove bottom radius D roll diameter DC disc bite outer diameter L offset amount

Claims (3)

[Claims] 1. In the reshaping of a hole-type roll of a three-roll outer diameter reduction rolling machine which does not have a roll gap adjusting mechanism, the hole-type roll of each main stand is provided with the stand and the preceding stand both at the roll groove bottom and the edge. The roll operation method of the three-roll reducer, which is characterized in that the roll is modified to the intermediate roll and used on the stand. 2. In the reshaping of a hole roll of a three-roll outer diameter reduction rolling machine having no roll gap adjusting mechanism, the hole roll of each main stand is provided with the stand and the preceding stand both at the roll groove bottom and the edge. The roll operating method of the three-roll reducer, characterized in that the hole-type roll of the first finishing stand is cut so as to approach the regular rolling amount, after being cut into the intermediate roll of the above. 3. In the modification of a hole-shaped roll of a three-roll outer diameter reduction rolling machine having no roll gap adjusting mechanism, the hole-shaped roll of each main stand is provided with a stand and a preceding stand both at the roll groove bottom and the edge. A roll of a three roll reducer characterized by being cut into an intermediate roll for use in the stand and provided with a roll gap adjusting mechanism in at least the first finishing stand to adjust the roll gap to approach a regular reduction amount. Operation method.