METHOD AND APPARATUS FOR ELECTRICALLY-HEATED REFRACTORY MOULDS AND MANDRELS

Abstract

The present concept is an electrically heated refractory mandrel which includes a mandrel shell including a top surface, side surfaces and a bottom surface. An interior frame work is mounted within the mandrel shell and defines a number of openings. Heater panels are dimensioned to fit within the openings defined within the interior frame work wherein each heater panel includes heater elements for heating preselected surfaces of the mandrel shell.

Description

The present application claims the benefit of previously filed U.S. Provisional Application 61/894,478 filed Oct. 23, 2013 under the title METHOD AND APPARATUS FOR ELECTRICALLY-HEATED REFRACTORY MOULDS AND MANDRELS, by Keith Ryan.

FIELD OF THE INVENTION

The present concept relates generally to a method and apparatus for forming and curing thermally-catalyzed refractory materials, and more particularly is directed toward the forming and curing of thermally-catalyzed refractory material by electrically produced heat for moulds and mandrels used in the steel and foundries industry.

BACKGROUND OF THE INVENTION

Historically working linings which are used in for example in ladles and tundishes often have a two layer lining wherein the first layer is a safety or base layer and wherein second layer is a working lining which is replaced periodically due to wear.

Historically the working lining has often been sprayed on to the base refractory lining in order to repair those areas of the lining which have become worn.

More recently there has been a move to the use of dry material and/or the so-called dry vibe which does not require the use of any water to be mixed with the refractory material. From a metallurgical perspective the steel will have a lower hydrogen content with the dry vibe material since there is no water left over to break down into hydrogen/oxygen. The dry vibe process also normally produces a better quality surface finish and a longer lining life due to the fact that the surface finish is smoother.

Therefore in order to replace the lining in a tundish which is typically used in the steel making and also in the foundry industry the tundish which normally is a female mould requires that a refractory lining be installed in this female mould in order to pour the molton metal into the tundish.

Typically a male mandrel is placed within the female tundish with enough space around the entire exterior surface of the mandrel in order to install the dry vibe refractory lining in place.

Thereafter forced air gas burners are used to heat the mandrel up to the required temperature which in turn will heat the dry vibe thermally catalyzed refractory material in order to fully cure the refractory material and in turn produce a monolithic lining within the tundish.

The current process is extremely inefficient and it is estimated that approximately 40 to 60 per cent of the heat produced by the forced air gas burners is lost to the atmosphere.

In addition the burners are expensive to purchase, require complicated gas regulation certification and are potentially unsafe due to the production of hydrocarbon, carbon monoxide and other noxious gases in the vicinity of the use of the gas burners.

Lastly it is very difficult to ensure that the mandrel is heated in a uniform manner since the gas burners tend to be flame contact with the tundish mandrels and therefore there normally is a fairly large temperature distribution across the mandrel resulting in uneven heating and setting of the refractory.

Therefore there is a need for a process for forming and curing thermally-catalyzed refractory materials which is less expensive, is thermally more efficient, provides a more uniform heating of the thermally-catalyzed refractory material and is safer to operate.

BRIEF DESCRIPTION OF THE DRAWINGS

The present concept will now be described by way of example only with reference to the following drawings in which:

FIG. 1 is a schematic top perspective view of a tundish mandrel together with a hopper mounted thereon showing the various surfaces of the tundish mandrel.

FIG. 2 is a schematic top perspective view of the tundish mandrel together with a partially broken away refractory lining as typically would be set around the outer surfaces of the tundish mandrel, wherein the mandrel is also partially broken away to reveal an interior framework.

FIG. 3 is a schematic bottom perspective view of a tundish mandrel with the bottom surface partially removed revealing the interior framework and also a number of heater panels.

FIG. 4 is a schematic bottom perspective view of the interior framework that is installed within the tundish mandrel together with some heater panels installed within some openings.

FIG. 5 is a schematic rear perspective view of a heater panel showing the rear face and connector lugs.

FIG. 6 is a schematic perspective front view of a heater panel showing the front face together with the heater elements.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present concept the tundish mandrel shown generally as 100 is shown together with a refractory hopper 102 deployed onto the tundish mandrel 100 and connected with brackets 104.

Tundish mandrel 100 includes the following major components namely top surface 106 which includes brackets 104, side surfaces 108, bottom surface 110.

Refractory hopper 102 includes the following major components namely hopper compartment 120, discharge 122, lifting lug 124, legs 126 and rails 128.

The reader will note that refractory hopper 102 can be attached to the tundish mandrel 100 with brackets 104 using any suitable connecting means including bolts and nuts.

Referring now to FIG. 2 which shows a schematic cut away refractory lining 129 which typically would be formed by tundish mandrel 100.

Refractory lining 129 is normally dry deposited in between the gaps produced between the tundish mandrel and for example a tundish which is not shown. The tundish mandrel would be placed into the tundish leaving a gap around its entire periphery including the bottom surface 110 and all of the side surfaces 108. This gap will allow the placement of thermally catalyzed refractory materials therein producing refractory lining 129 after it has been heated and cured. Thereafter the tundish mandrel is removed and the tundish itself now has a new working lining for future use.

The reader will note that by way of example only we are using a tundish mandrel 100 as an example of the present concept. There is no reason why the same concept could not be used in other applications as for example a ladle lining and/or in other areas where refractory linings are required.

Referring now to FIG. 2 through 6 the reader will note that there is an interior framework 130 within tundish mandrel 100.

FIG. 3 for example shows a partial cutaway view of tundish mandrel 100 wherein the bottom surface 110 is cut away to reveal the interior framework 130 and heater panels 131.

Referring now and more particularly to FIGS. 4 through 6, FIG. 4 shows the interior framework 130 which defines a number of openings 132 including but not limited to side openings 134, bottom openings 136 and corner openings 138.

Each opening 132 is designed to hold a heater panel 131.

Referring now to FIGS. 5 & 6 which show an individual heater panel 131, which includes heater elements 140, an insulated board 142, a panel frame 144, a front face 146, a rear face 148 and connector lugs 150.

Heater panels 131 are manufactured in standard sizes to fit within openings 132 of the interior framework 130.

The interior framework 130 will be designed in such a manner to accept as many as possible standard size heater panels 131 around the outer surface of tundish mandrel 100.

In Use

Tundish mandrel 100 includes a number of electrically heated heater panels 131 which are distributed around the surfaces in particular side surface 108 and bottom surface 110 in this example of the tundish mandrel 100 in order to heat the refractory lining 129.

Preferably there will be a series of heater panels containing heater elements inside the mandrel with reflectors to direct all of the radiant heat to the side surface 108 and/or the bottom surface 110 of the mandrel.

The elements will be secured and placed at an optimum distance away from the mandrel side surfaces 108 and the mandrel bottom surfaces 110.

The top surface 106 of tundish mandrel will preferably be insulated to reduce heat loss.

Each heater panel 131 can be individually controlled and/or a series of heater panels 131 can be banked together to be controlled in such a manner that the multiple sources of heat distributed throughout the mandrel will allow one to consistently heat the side surface 108 and the bottom surface 110 of tundish mandrel 100 in as uniform a way as possible.

The materials of construction for tundish mandrel 100 will be chosen in such a manner to provide good conductivity of heat through the side surfaces 108 and the bottom surface 110 and thereby further reduce ineffective heat transfer.

Additionally since this process essentially eliminates the gas burners which are normally located very close to the top surface 106 of tundish mandrel 100 it is possible to mount refractory hopper 102 onto the top of tundish mandrel 100 thereby allowing easy delivery of refractory material into hopper compartment 120 and out through discharge 122 and onto top surface 106.

Normally in process the refractory material would then be raked such that it flows down along the outer wall of the tundish and the side surfaces 108 of the tundish mandrel thereby creating refractory lining 129 as depicted in FIG. 2.

Often refractory material is placed in the bottom of the tundish adjacent to bottom surface 110 of tundish mandrel 100 to ensure that material flows properly to this location.

Referring to FIG. 1, tundish mandrel 100 therefore includes a mandrel shell 160 which includes the side surface 108, the bottom surface 110 and the top surface 106. Within mandrel shell is an interior framework 130 which includes a number of openings 132 as well as heater panels 131 which are electrically connected to an electrical control source.

It should be apparent to persons skilled in the arts that various modifications and adaptation of this structure described above are possible without departure from the spirit of the invention the scope of which defined in the appended claim.

Claims

1. An electrically heated refractory mandrel comprising:

a) a mandrel shell including a top surface, side surfaces and a bottom surface,

b) an interior frame work mounted within the mandrel shell defining a number of openings,

c) heater panels dimensioned to fit within the openings defined within the interior framework wherein each heater panel includes heater elements for heating preselected surfaces of the mandrel shell.

2. The electrically heated refractory mandrel claimed in claim 1 further including a hopper detachably mounted onto the mandrel for discharging refractory material onto the top surface of the mandrel.