CS224967B1 - The semi-product for the production of tubes - Google Patents

Description

BACKGROUND OF THE INVENTION The invention relates to a blank in particular for the manufacture of pipes.

Currently, semi-finished products are used for the production of hollow bodies with a straight face without shape changes, with a face provided with a punch, pre-drilled along its entire length, or semi-finished products with a frustoconical end, the face forming a smaller base. ,

Semi-finished products with such treated ends do not provide sufficient conditions for the successful conducting of the punching process in terms of the accuracy and quality of the tubes produced. The smooth ends of the blanks do not allow the application of punching lubricants. For successful punch rolling, one of the basic prerequisites is the reliable engagement of the workpiece by the work rolls. In the currently used blank shapes, poor engagement often results, resulting in rolling loss of time and deteriorated quality of the perforated hollow blank at its front end. During the unsteady punching process (at the beginning and at the end), the metal formed is intensively twisted, which, at the ends of the hollow blanks produced, appears to result in an increased number of defects. This causes a relatively large portion of both ends to be cut off as proper technological waste.

These disadvantages are overcome by the semi-finished product according to the invention

Λ the principle is that at least one end of the workpiece is provided with a hollow extension, the cavity of which is located along the longitudinal axis of the workpiece.

The blank according to the invention makes it possible to eliminate the centering operation, which results in metal savings in the machining of the punch or punch. there is no need to center the workpieces before punching. The treatment ensures perfect engagement of the workpiece forming the conditions for

Z224 967 production of pipes of the best quality. It eliminates the adverse effects of the unsteady process at the beginning and end of rolling, which are characteristic of the processing of currently used blanks. The semi-finished product also ensures the production of tubes with parameters that cannot be achieved when using classic semi-finished products with the required quality of the tubes. It is about achieving high values of tube to wall thickness, especially when rolling tubes on three-roll stands.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of a blank having a hollow extension having a cylindrical shape, and FIG. 2 the same having two cylindrical successive cylinders. the hollow insert may also have, for example, a cavity in the shape of a truncated cone with a larger base in the direction away from the blank

The blank χ is provided at its ends with a hollow extension 2, 2 * whose face 4, 4 * is rigidly attached to the end of the blank 1. The cavity 3, 3 * is in the longitudinal axis of the blank 1 and can be shaped. The shape and size of the hollow nozzle 2, 2 'is dependent on the initial dimensions of the blank 11 and the desired dimensions of the finished product. Advantageously, the hollow boss 2, 2 'may be made of a more economical material.

The shaped cavity blank according to Fig. 1 with dimensions of $ 90 x 1750 mm made of ČSN 12050 steel with a cavity diameter of 60 mm and a depth of 100 mm was punched on a three-cylinder punching machine and reached D / s = 10 without increasing front diameter and back triangulation the ends of the perforated pipe.

The semifinished product 1 according to the invention can be used in tube forming operations.

Claims (1)

SUBJECT OF THE INVENTION 224 967 Semi-finished product for the manufacture of pipes, characterized in that at least one end of the semi-finished product is provided with a hollow extension (2), the cavity (3) of which is disposed along the longitudinal axis of the semi-finished product.