Steel-shelled ceramic spacer block

Abstract

A spacer member for supporting a metallic alloy product during heat treatment comprising a ceramic core and a tubular housing is disclosed. The tubular housing, which encloses the ceramic core, comprises a bore, a wall portion, and two end portions. In order to resist deformation during usage, the tubular housing is made from high temperature steel, a high temperature steel alloy, or cold rolled steel. The wall portion has at least two substantially flat surfaces having corner edges that have a radius of at least ⅜ inch and ends that are tapered at least ¼ inch. In addition, the flat surfaces also have a coating that reduces the sticking of a metallic alloy product. The end portions each have at least one aperture to allow the inside to adjust itself to ambient atmospheric pressure. A method of making a spacer member is also disclosed.

Description

FIELD OF THE INVENTION [0001] The present invention relates to spacer blocks positioned between aluminum ingots in preheat furnaces and, more particularly, to an improved spacer block that is more robust and has a longer useful life. BACKGROUND OF THE INVENTION [0002] Heating of aluminum ingots is a well-established practice for achieving desired properties in the ingot and to render the ingot sufficiently malleable for reduction in thermo-mechanical processes. During a preheating step, aluminum ingots are heated to temperatures below the melting point of the aluminum alloy. Preheating serves to control the metallurgical properties of the ingot, reduce cracking, and reduce the forces needed to further process the ingot. Up to six ingots can typically be vertically stacked in a preheat furnace at one time. Spacer blocks are typically positioned between the stacked ingots to maintain a gap between the ingots and prevent them from sticking to one another, allow hot gases to circulate b...

AI Technical Summary

Benefits of technology

[0010] This need is met by the spacer member of the present invention, which may be used for supporting a metallic alloy product subject to heat treatment. The spacer block comprises a tubular housing with a core of a ceramic material. The tubular housing, which encloses the ceramic core, comprises a wall portion, two end portions, and a bore. The wall portion has at least two substantially flat surfaces in parallel with each other, with the flat surfaces having corner edges that have a radius of at least 3 / 8 inch and ends that are tapered at least ¼ inch inward toward the bore of the tubular housing. In addition, the flat surfaces also have a coating that reduces the sticking of a metallic alloy product. The end portions each have at least one aperture to allow the internal portions of the block to adjust to ambient atmospheric pressure.

[0011] The spacer member of the present invention may be produced by providing a tubular housing comprising a bore and a wall portion having at least two substantially flat surfaces in parallel with each other wherein the flat surfaces have corner edges and ends, tapering the ends at least ¼ inch inward toward the bore of the tubular housing, attaching an end portion having at least one aperture to an end of the tubular housing, filling the tubular housing with a ceramic material, and attaching another end portion having at least one aperture to the other end of the tubular housing. The flat surfaces may then be coated with a non-stick coating for preventing sticking of a heat-treated metallic alloy product to the spacer member.

Problems solved by technology

Additional drawbacks to conventional spacer blocks relate to their composition.

(427° C.) and higher, aluminum alloy spacer blocks exhibit a diminished strength capacity that is typically unsatisfactory for providing adequate ingot support.

Deformation and adhesion of the spacer blocks to the ingots is particularly problematic for the ingots at the bottom of the stack where the load is the greatest.

However, often the spacer block is so tightly adhered to the ingot that it must be knocked off with a large hammer or an axe.

An additional problem associated with sticking of conventional spacer blocks to the ingot is the formation of marks, which are typically left on an ingot upon removal of the spacer block.

Spacer blocks often produce defects in the surface of the ingot.

When an ingot having such a defect is subsequently rolled, the defect becomes a surface imperfection in the rolled product.

For many applications of rolled product, such defects are unacceptable in the marketplace.

Another drawback to the aluminum spacer blocks is the tendency of various aluminum alloys used for conventional spacer blocks to creep at high temperatures.

High temperature creep of aluminum spacer blocks is also a problem in preheat furnaces operated at higher temperatures, e.g., at or above about 1120° F.

This often results in the entire spacer block being flattened into a thickness of about ½. When the spacer block between the ingots is greatly reduced to about ½ inch, airflow between the ingots is greatly reduced which results in uneven heating, extended cycle times, and insufficient exposure of the ingot surfaces to the furnace atmosphere.

Images