GB2203975A

GB2203975A - Casting mould

Info

Publication number: GB2203975A
Application number: GB08812733A
Authority: GB
Inventors: Alexandr Leonidovich Tsikerman; Vladimir Nikolaevich Kurlykin; Mikhail Anatolievich Kisselman; Lev Avramovich Volokhonsky; Alexandr Leonidovich Andreev; Valentina Kuzminichna Trunova; Sergei Vitalievich Orlov; Viktor Borisovich Gutkin; Igor Mikhailovich Bershitsky
Original assignee: VNI PK T I ELEKTROTERM OBORU
Current assignee: VNI PK T I ELEKTROTERM OBORU
Priority date: 1986-10-24
Filing date: 1986-10-24
Publication date: 1988-11-02
Anticipated expiration: 2006-10-24
Also published as: GB8812733D0; WO1988003177A1; FR2606128B1; FR2606128A1; SE8802285L; SE461915B; JPH0248345B2; DE3690795C2; GB2203975B; DE3690795T1; JPH01500976A; SE8802285D0

Abstract

A casting mould comprises a sleeve (1) provided with stiffening ribs (2) and a steel envelope (3) oriented coaxially to the sleeve (1) and forming, together with the latter, a cooling cavity (4) divided by the stiffening ribs (2) into channels (5), whereas the sleeve (1) is bimetallic and its external layer (6) is made of steel and its thickness is 0.1-0.3 of the height of the stiffening rib (2).

Description

MOULD Technical Field The invention relates to metallurgy and has specific reference to moulds, Background of the Invention There is known a mould (cf. B.I.Medovar et al."Elec troshlakovie pechi", "Naukova dumka", Xiev, 1976, p. 91 (in Bussian) ) for remelting processes comprising a tube mude of copper or copper-base alloy and a steel shell disposed coaxially with the tube and forming a cooling jacket therewith. The steel shell is connected to the tube by means of bolts.

The known mould has a short service life, for its copper tube lacks aaequate stiffness and deforms under high thermal stresses which are brought about by a tern- perature gradient in the tube wall as high as 5 to 1OoC/mm.

This, in its turn, causes high-temperature stresses in the wall and, hence, its deformation. The conditions under which the remelting moulds are bound to operate call for strengthening the mould structure.

Also known is a mould (US Patent No. 389901?, IPC B22 D 27/02, published 12.08.75, Associated electrical Industries Limited, London) the copper tube whereof with reinforcing ribs is contained in a coaxial steel shell forming a cooling jacket The ribs forming a number of passages in the jacket are attached each through the lingth of one side, e.g. by brazing to the outer side of the tube , whereas the other side thereof is bolted to the steel shell.

The copper tube of the known mould also cannot resist the thermal stresses in its wall and deforms consequently, rendering the mould inoperative before long. The vertical ribs brazed to the wall of the copper tube are of no avail in thise case, for no brazing can prevent ribs from being torn off the tube.

A heavily deformed tube invites difficulty in withdrawing the ingot therefrom and renders further operation of themould problematic.

Disclosure of the Invention The main object of the present invention is to provide a mould of modified design which would stiffen the mould and prolong its service life.

The object of the invention is realized by providing a mould comprising a ttibe b 1t reinforcing ribs, and steel shell disposed coaxially with the tube and forming therewith a cooling jacket separated by the ribs into passages wherein according to the invention the tube is a bimetallic one the outward steel layer whereof is of a thickness equalling 0.1-0.3 time the height of a rib.

It is preferable to have inner layer of the tube made of copper.

The inherently stiff tube as described hereinabove adds to the reliability of the mould and extends its service life. The steel-backed copper layer of the tube can be of minimum thickness so that a saving in non-ferrous metals (copper, chromium bronze) which are in short supply is obtainable.

Brief Description of the Drawings A preferred embodiment of the invention will now be described with reference to the accompanying drawings in which Figure 1 is a sectional elevation of a mould according to the invention; Figure 2 is a horizontal section on the line II-II of Fig. 1, according to the invention Best Mode for Carrying Out the Invention The mould contains a tube 1 (Figs 1, 2) having reinforcing ribs 2 to which is welded a steel shell 3 located coaxially with the tube 1 and forming with the tube 1 a cooling jack- 4. The cooling jacket 4 is separated by the reinforcing ribs 2 into passages 5 for circulating a cooling agent. The pipe 1 is of the bimetallic construction and contains an outside steel layer 6 and an internal layer 7 being a working one and made of copper or chromium bronze.The outside layer 6 is a single whole with the ribs 2 and has a thickness of 0.1-0.3 time the height of a rib 2. The cooling agent is admitted into the jacket 4 over pipes 8 and discharged therefrom over pipes 9. Consumable electrodes 10 are melted in a slag batch 11 and an ingot 12 is formed in the tube 1.

The outside layer of the bimetallic tube of a thicness less than 0.1 the height of a rib cannot make for an adequate stiffness of the tube and with a thickness of this layer greater than 0.3 the height of a rib causes an increase in the thermal resistance of the outside layer in excess of the thermal resistance of the inside layer and this leads to overheating of the tube and an increase in the rate of its erosion.

The mould operates as follows, The mould is mounted on a stool (not shown). The cooling agent is admitted into the passages 5 through the pipes 8 and discharged therefrom though the pipes 9.

A slag bath 11 is set up at the bottom of the tube 1 mounted on the stool and the consumable electrode 10 is lowered into the bath. A voltage applied across the slag bath 11 and the consumable electrode 10 heats up the electrode and causes it to melt. Molten metal passes through the slag bath 11 and solidifies into the ingot 12 in the lower end of the tube 1.

The process of electroslag remelting imposes thermal loads as high as 0.5.106 to 1.5.106 W/m2 on components of the mould. The resulting high thermal stresses set up in the wall of the tube 1 may cause irrecoverable deformations. The outside steel layer 6 of the bimetallic tubel significantly stiffens the structure and improves the reliability of the mould. The bimetallic construction of the tube 1 is conducive to reducing the thickness of its internal working layer without impairing the overall stiffness of the mould and to reducing the requirements in copper and also the erosion of the tube 1 is lessened.

All in all, the reliability of the mould - a key compo event of any remelting arrangement - is significantly increased.

Industrial Applicability The present invention can be applied for remelting processes: electro-slag, vacuum - arc, electro-arc, electron-beam. The present day remelting technology involving formation of solid and hollow ingots, shaped castings from various steel grades, nonferrous and refractory metals can find application in many industrial engineerings.

Claims

Claim

1. A mould comprising a tube (1) having reinforing ribs ( 2) and a steel shell (3) disposed coaxially with the tube (1) and forming therewith a cooling jacket (4) separated by the ribs (2) into passages (5) c h a r a c t e r i z e d in that the tube (1) is a bimetallic one an outward steel layer (6) whereof is of a thickness equalling 0.1-0.3 time the height of the reinforcing rib (2).

2. A mould as claimed in claim 1, c h a r a c t e r i z e d in that an inner layer (7) of the tube (1) is made of copper.