CS209835B2 - Method of making the permanent moulds - Google Patents

Abstract

1,269,690. Making casting moulds; drawing. KABELUND METALLWERKE GUTEHOFFNUNGSHUTTE A.G. 13 Nov., 1969 [19 Nov., 1968], No. 55624/69. Heading B3A, B3F and B3P. A longitudinally curved mould, for example a copper arc type mould for a continuous casting machine, is made by pressing a longitudinally curved mandrel having external dimensions equal to the internal dimensions of the mould, preferably a chromium plated mandrel, into a longitudinally curved metal tube, cold forming the tube so that it conforms in shape to the mandrel and removing the mandrel. A mandrel 2 inserted in a tube 1 is pressed through a ring 3 to make the tube conform to the shape of the mandrel. The hardness of the tube is increased from 30-35 kp./mm.<SP>2</SP> to approximately 90 kp./mm<SP>2</SP>. during the cold forming step. The mould formed may be of rectangular, square or polygonal section or it may be conical.

Description

The invention relates to a process for the manufacture of molds consisting of a piece of metal, for example a copper tube, in particular molds bent into a circular arc for continuous casting machines.

The continuous casting of high melting metals, such as iron and steel, involves the use of ingot molds which are either one-piece or multi-part. The one-piece ingot molds consist of a cylindrical or prismatic tube, for example of pure copper, which has proved its good thermal conductivity. In the production of high-performance ingot molds, in particular for casting small and medium cross-section ingots, copper is also used with certain additives which cause deposition hardening while maintaining high thermal conductivity of the ingot mold.

In the manufacture of copper tube molds, for example for a machine for continuous casting into a circular arc, the procedure has so far been to fill the starting tube with a variety of filler materials and then bend it with a suitable bending device. However, this production method necessarily results in the cross-section of the bent tube being changed by the upsetting of the inner and the stretching of the outer fibers, thereby producing, for example, a mold of known trapezoidal shape. In addition, it is not possible in this way to achieve the necessary accuracy of both the cross-section of the ingot mold and the linear deviation, which is usually about ± 0.1 mm, calculated over a length of 700 to 800 mm. In addition, another problem is that the tube must have only a relatively low hardness in order to be able to bend, whereas a much higher hardness is required for the finished mold.

The process according to the invention removes these drawbacks and consists in that a mandrel, in particular a curved mandrel, which has the final dimensions and shape of the ingot mold cavity and a straight metal, is pressed into a cast, molded, drawn or otherwise manufactured piece of straight metal tube. the tube is preformed, then the preformed metal tube is pressed tightly onto the mandrel by cold forming, whereupon the mandrel is extruded from the metal tube without changing the final dimensions of the mold cavity.

With the process according to the invention, it is possible to produce molds which are characterized by a high dimensional stability, a high-quality surface and a hardness sufficient for their use as a mold for the continuous casting of metals. These properties can be achieved by the process according to the invention irrespective of whether it is a straight mold with or without a flange, a straight mold with conical or pyramidal converging walls, or a curved or conical or pyramidal conical mold. mold. The high quality of straight or curved bodies of rectangular, square, polygonal or similar cross-section to the chill bodies is essential.

In working way. according to the invention, the external dimensions of the mandrel, whether curved or straight, are chosen only slightly smaller than the internal dimensions of the initial metal tube. The pressing of the mandrel into the metal tube and the subsequent cold forming of the metal tube by pressing on the mandrel of high surface quality causes an increase in the mechanical strength of the mold to be produced. Therefore, a mandrel having not only good surface quality but also high surface hardness is advantageously used.

An example of manufacture according to the method of the invention is shown schematically in the accompanying drawings, in which Figures 1 to 7 show the metal tube to be processed and the mandrel to be used in the successive stages of production in a circular arc of a curved mold for a continuous casting machine.

First, a straight copper pipe 1 having a Brinell hardness of about 294.2 to 343.2 MPa for the length of the ingot mold with the addition of a machining allowance is cut off from the continuously drawn copper tube. Then, the copper tube 1 is placed

Claims (2)

Method for producing molds made of a piece of metal, for example copper pipe, in particular molds bent into a circular arc for continuous casting machines, characterized in that a mandrel is pressed into a cast, molded, drawn or otherwise produced piece of straight metal pipe. in particular, a curved mandrel, presses in all its length · hard · chrome mandrel 2,. made in accordance with the internal dimensions of the finished mold and adapted to a shape corresponding to the curvature of the circularly curved continuous casting machine The copper tube 1 is initially forced into a shape corresponding approximately to the shape of the mandrel 2, as shown in FIG. 2. The copper tube 1 with the embossed mandrel 2 is then squeezed through the pressing ring 3, Fig. 3, thereby pressing the pressure against the surface of the mandrel 2. This forming of the copper; Cold tubes will cause complete dimensional stability of the copper tube and increase its Brinell hardness from an initial of about 294.2 to 343.2 MPa to about 686.5 to 882.6 MPa. To remove the mandrel 2 from the copper tube 1 of precise dimensions and high hardness. FIG. 5 shows a support 4 for a copper tube 1 on which the copper tube 1 rests at its end when the mandrel 2 is pushed out. After the mandrel 2 has been pushed out of the copper tube 1 and passed through the support 4, FIG. an ingot mold is formed in the form of a circular arc and shown schematically; In the case of conical molds, the mandrel 2 is naturally extruded from the metal tube lt in the opposite direction. Inventive compounds which possesses the final internal dimensions and shape of the mold cavity and a straight metal tube is pre-shaped by it, then pre-shaped metal pipe is pressed tightly against the mandrel by cold deformation, whereupon the mandrel is a metal tube of finite rozměJrů unchanged _(cavity mold extruded.