GB2144660A

GB2144660A - Dummy bar for use in horizontal continuous casting of round billets

Info

Publication number: GB2144660A
Application number: GB08321597A
Authority: GB
Inventors: Vitaly Maximovich Niskovskikh; Midkhat Mubarkovich Mansurov; Viktor Nikolaevich Khorev
Original assignee: OB URALMASH PROIZV
Current assignee: OB URALMASH PROIZV
Priority date: 1983-08-05
Filing date: 1983-08-11
Publication date: 1985-03-13
Also published as: FI832828L; SE8304335D0; JPS6049842A; AU1783483A; DE3329078A1; SE8304335L; FI832828A0; FR2550480A1; FR2550480B1; GB8321597D0

Abstract

The dummy bar comprises a rod (1), and a detachable head (2) in the form of a cylindrical sleeve whose outer diameter D=(0.99 to 0.998) D1 (the mould cavity internal diameter) in order to allow gas to escape during filling of the mould (3). The wall thickness of the sleeve changes over a length L of 100 to 150 mm in accordance with the equation: delta n=(0.1 to 0.2)+(0.03 to 0.04) Cn, where delta n is the wall thickness at a distance Cn from the end of the sleeve. The thickness at the end is (0.0004 to 0.0025)D1. Molten metal reaching the end of the sleeve freezes without penetrating into the gap, so that sealing of the head to the mould is unnecessary. <IMAGE>

Description

SPECIFICATION Dummy Bar for Use in Horizontal Continuous Casting of Round Billets The present invention relates to a dummy bar for use in a mould of a horizontal machine for the continuous casting of round billets.

Such a dummy bar is known (c.f. Technical Report No. B 452,893 relating to the development of a pilot version of a horizontal continuous casting machine at the Tulachermet Research and Production Association, 1975, State Registration Number 74,002,399, pp.

1 24-125), which comprises a rod, a detachable head in the form of a solid cylinder, and means for the removal of gases from the mould at the start of pouring.

The dummy bar in question requires that the gap between its detachable head and the wall of the mould be filled with a refractory material, such as asbestos cord. The means for the removal of gas from the mould is an opening provided in the head, through which the inside of the mould communicates with the atmosphere. This dummy bar fails to provide for effective removal of gas from the mould at the start of pouring. It is further disadvantageous in that much time is required to prepare the horizontal continuous casting machine for teeming.

Another such dummy bar is known (cf. E.

Germann, Nepreryvnoye lityo (Continuous Casting), Moscow, 196i,p.4O9, Fig. 1231), which comprises a rod, a detachable head in the form of a cylindrical sleeve, and means for the removal of gases from the mould at the start of pouring. The internal surface of the cylindrical sleeve, which faces the molten metal, is cone-shaped. The gas removal means is an opening provided in the detachable head.

The latter dummy bar construction again required that the gap between its detachable head and the wall of the mould be filled with a refractory material. The time taken to perform this operation is added to the time taken to prepare the caster for pouring. The dummy bar head is further disadvantageous in that it fails to provide for adequate removal of gases from the mould at the start of pouring.

What is described is a dummy bar for use in a mould of a horizontal continuous casting machine for producing round billets, which would make it possible to speed up the preparation of the casting machine for teeming and facilitate the removal of gases from the mould at the start of pouring.

The invention provides a dummy bar for use in a mould of a horizontal continuous casting machine for producing round billets, comprising a rod, a detachable head in the form of a cylindrical sleeve, and means for the removal of gas from the mould at the start of pouring, in which the diameter of the detachable head is smaller than that of the mould and is in the range of 0.99 to 0.998 of the diameter of the mould, the wall thickness of the cylindrical sleeve at its end ranging from 0.0004 to 0.0025 of the mould diameter, and changing over a length L of 100 mm to 1 50 mm in accordance with the equation: U~n=(0.1 to 0.2)+(0.03 to 0 04)Cnt where Cn is the distance from the end of the cylindrical sleeve, which is in the range of O to L.

The invention improves the initial casting conditions by permitting effective removal of gas from the mould at the start of pouring. It cuts down the time it takes to prepare the casting machine for pouring by dispensing with the filling of the gap between the detachable head and the mould wall. This improves operating conditions and reduces the amount of labour-consuming operations.

The present invention will be further described by way of example only, with reference to the accompanying drawing, which is an elevation view of a dummy bar installed in a mould of a horizontal continuous casting machine for producing round billets.

The dummy bar comprises a rod 1 and a detachable head 2 in the form of a cylindrical sleeve whose diameter D is smaller than the diameter D of the mould 3 and is in the range of 0.99 to 0.998 D. The wall thickness of the cylindrical sleeve is 0.0004 to 0.0025 D, at its end and changes over a length L of 100 to 1 50 mm according to the equation: 6,=(0.1 to 0.2)+(0.03 to 0.04)con, where An is the wall thickness of the sleeve at a distance Cn from the end of the sleeve, which distance is in the range of O to L.

The means for the removal of gas from the mould 3 at the start of pouring is the gap between the detachable head 2 and the mould 3, bearing in mind that the diameter D of the detachable head 2 is smaller than the diameter D1 of the mould 3.

The dummy bar is used as follows. The detachable head 2 is coupled to the rod 1 and installed at a required depth in the mould 3. As molten metal is poured into the mould 3, the gas freely escapes through the gap between the head 2 and the wall of the mould 3, because the diameter D of the head 2 is smaller than the diameter D, of the internal surface of the mould 3, being somewhere in the range from 0.99 to 0.998 of D,. Upon coming in contact with the end of the detachable head 2, the molten metal solidifies without penetrating into the gap. The thin wall at the end of the head 2 is heated by the melt and becomes plastic. The skin of the billet and the head 2 shrink during cooling, which rules out jamming of the head 2 in the mould 3 as the head 2 and the billet are withdrawn from the mould 3.

Thus the present invention simplifies the dummy bar construction and facilitates the removal of gases from the mould at the start of pouring. By dispensing with the labour consuming operation of filling the gap between the detachable head 2 and the walls of the mould 3, the time taken to prepare the caster for operation is reduced.

Claims

1. A dummy bar for use in a mould of a horizontal continuous casting machine for producing round billets, comprising a rod and a detachable head in the form of a cylindrical sleeve, the diameter of the detachable head being in the range of 0.99 to 0.998 of the diameter of the mould, the wall thickness of the sleeve being 0.0004 to 0.0025 of the mould diameter at the end of the sleeve and changing over a length L of 100 to 1 50 mm according to the equation: Sn=(0*1 to 0.2)+(0.03 to 0.04)con, where Sn is the wall thickness of the sleeve at a distance Cn from the end of the sleeve, Cn being in the range from 0 to L.

2. A dummy bar for use in a mould of a horizontal continuous casting machine for producing round billets substantially as described with reference to the accompanying drawing.

3. A method of casting using a dummy bar according to Claim 1 or 2, in which the head is attached to the rod and inserted into the mould, molten metal is poured into the mould and gas is allowed to escape between the head and the mould, and the head is withdrawn together with the solidified metal.