METHOD FOR MANUFACTURING SEAMLESS TUBE

Japanese Patent JP3119160

B2

PROBLEM TO BE SOLVED: To prevent defective bite, the contraction of a tube end, and the occurrence of an uneven thickness, and to improve quality and productivity even when piercing rolling a thick tube with high expansion ratio and low ratio of piercing by specifying the shape of a plug to be used when manufacturing the seamless tubes by Mannesmann tube manufacturing method.
SOLUTION: The rolling part of the plug 2 to be used is bisected to preceding stage rolling part and succeeding stage rolling part. And also, when the radius of curvature and length in the axial direction of the tip spherical surface of the preceding stage rolling part are expressed by rp and L1 respectively, a taper angle and length in the axial direction of the succeeding stage rolling part are expressed by θ and L1, and the taper angle and length in the axial direction of a reeling part are expressed by θ1 and L3 respectively, formulas I to IV must be satisfied by these. In addition, this plug can be effectively used at the time of piercing rolling with the expansion ratio 1.15 or over and the ratio of piercing 2 or below. Also, this plug is applicable regardless of a difference between the cone type and the barrel type of a main roll and the type of a guide part, and the same effect can be obtained.

JPS63248502	MANUFACTURE OF SEAMLESS TUBE
JPS61202721	MANUFACTURE OF BILLET FOR CLAD PIPE
JP2000239807	HEAT RESISTANT AUSTENITIC STAINLESS STEEL

Tomio Yamakawa
Isso Shimoda

JP11985696A

December 18, 2000

May 15, 1996

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SUMITOMO METAL INDUSTRIES,LTD.

B21B19/04; B21B25/00; (IPC1-7): B21B25/00; B21B19/04

JP81210A
JP5954404A

Morio Mori (1 outside)

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