DE1279600B - Process and roll calibration for rolling seamless tubes with external longitudinal ribs - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY GERMAN mfWW> PATENT OFFICE Int. CL:

B21c

EDITORIAL

German class: 7b-37/15

Number: 1279 600

File number: P 12 79 600.8-14 (M 75115)

Filing date: August 11, 1967

Opening day: October 10, 1968

The invention relates to a method and a roll calibration for rolling seamless steel tubes with two opposing outer longitudinal ribs, in which the tube blanks on a conical Roll mandrels of circular cross-section are cold pilgrimaged.

It is known to produce seamless tubes with external longitudinal ribs by cold pilgrimage, with im Roll jump or in the roll jump and in the apex recesses are provided which correspond to the ribs. The latter embodiment is intended for tubes with four longitudinal ribs, the mandrel such can be profiled that the outer ribs are assigned inner grooves.

It is also a method for hot forming a pipe with a circular internal cross-section and outer longitudinal ribs known, the tube walls in certain previously heated sectors be brought to a preliminary profile, the peculiarity of which is that one of a pipe ao proceeds, the wall thickness of which is greater than that of the final pipe and its inner passage cross-section is smaller than the inner passage cross-section of the finally desired pipe, and that a mandrel is inserted into the inside of the tube leads through which an expansion and a reduction in the pipe wall thickness until it is reached the finally desired outer profile is brought about.

The invention purposely does not use the idea of hot deformation, but proceeds from the known cold pilgrimage method mentioned, to produce outer longitudinal ribs with very precise gauge blocks to produce, however, without using closed roll caliber, so that the roll calibration simplified and there are no burrs in the roll gap that require post-processing.

According to the invention, the tube blanks are placed on a conical rolling mandrel with free spreading in the Roll gap rolled out to its final wall thickness in the first part of the rolling process.

At the same time, the outer longitudinal ribs are preformed. In the second part of the rolling process, the final shape of the outer longitudinal ribs is finish-rolled with the tube wall thickness unchanged. At the end of the first rolling section, a precisely measured amount of material is available for forming the longitudinal ribs. This spreads into the caliber gap in the second rolling section. It has surprisingly been found that when the method according to the invention is used, tubes with a width that is practically constant over the entire length and with on-process and roller calibration for rolling
of seamless tubes with external longitudinal ribs

Applicant:

Mannesmann Aktiengesellschaft,

4000 Düsseldorf, Mannesmannufer 2

Named as inventor:

Karl Ernst Schölten, 5810 Witten-Bommern

approximately plane-parallel rib end surfaces can be achieved.

The choice of the length of the two caliber sections in the development is of influence. The first paragraph requires a greater length than the second, because this is where the greater deformation work has to be done is. The ratio of these sections can be about 3: 1.

The height of the recesses for the longitudinal ribs increases in the caliber gap up to the final thickness of the longitudinal ribs away. Their width exceeds the final width of the longitudinal ribs by a considerable amount over the entire length of the caliber Measure, at least by 5 mm each, to allow the longitudinal ribs to spread freely.

The drawing shows cross-sections through the pilger roll caliber in three stages of the rolling process shown in

F i g. 1 during rolling in the first, in

F i g. 2 at the start of rolling in the second section and in

F i g. 3 on the caliber outlet.

The drawing shows that the diameter of the mandrel decreases conically from the onward pilgrimage to the finished pilgrimage.

Claims (2)

Patent claims: 1. Process for rolling seamless steel tubes with two opposing outer longitudinal ribs, in which the tube blanks on a conical rolling mandrel of circular cross-section are cold pilgrimage, characterized in that the tube blanks with free expansion in the roll gap in the first part of the 809 620/26 Rolling process rolled out to their final wall thickness and at the same time the outer longitudinal ribs are preformed be, and that in the second part of the rolling process, the final shape of the outer longitudinal ribs is finish-rolled with unchanged pipe wall thickness. 2. Pilgrim roller calibration for execution of the method according to claim 1, characterized in that the first to the second caliber section has a ratio of about 3: 1. 3. Pilger roll calibration according to claims 1 and 2, characterized by recesses of decreasing height up to the final thickness of the outer longitudinal ribs and of the final width the outer longitudinal ribs of a width that is significantly greater. Considered publications:
German patent specifications No. 938 662, 910 612. 1 sheet of drawings 809 620/26 9.68 © Bundesdruckerei Berlin