US2785214A

US2785214A - Induction melting furnace

Info

Publication number: US2785214A
Application number: US514046A
Authority: US
Inventors: Segsworth Robert Sidney
Original assignee: General Engineering Co Ltd
Current assignee: General Engineering Co Ltd
Priority date: 1955-06-08
Filing date: 1955-06-08
Publication date: 1957-03-12
Anticipated expiration: 1974-03-12

Description

March 12 1957 R. s. sEGswoTl-l 2,785,214

INDUCTION MELTING FURNACE Inventor Roar/er s. sfcswoRrH March 12 1957 R. s. sEGswoRTH j Inventor 2 Sheets-Sheet 2 ROBERT S. SECSWORTH Attys support for the coil.

United States Patent O NDUCTION MELTIN G FURNACE Robert Sidney Segsworth, Toronto, Ontario, Cana'daz assignor to The General Engineering Company Limited, Toronto, Ontario, Canada Application June 8, 1955, Serial No. 514,046

Claims. (Cl. 13-27) This invention relates to improvements in induction melting furnaces.

Heretofore, when an induction melting furnace has been employed for melting various materials, it has been the practice to change crucibles between melts of different materials. Crucibles have the disadvantage of being more expensive and less rugged than fixed rammed linings.

It is the main object of the invention to provide an iniproved induction melting furnace characterized by a removable rammed lining whereby the same flexibility of change of melting pot is achieved as with crucibles.

It is another object of the invention to provide an improved construction of induction melting furnace embodying an embedded fixed induction heating coil.

v It is a further object of the invention to provide an induction melting furnace embodying improved tilting mechanism.

Other objects of the invention will be appreciated from a study of the following specification taken in conjunction with the accompanying drawings.

In the drawings:

Figure l is a sectional elevation view of the improved induction melting furnace of the invention;

Figure 2 is an elevation of the induction melting furnace of the invention;

Figure 3 is a view of the device of Figure 2 but showing'the furnace in dumping motion; and

Figure 4 is a view of the device of Figure 2 showing the furnace in full dumping position.

Referring to the drawings, the furnace structure of v.the invention comprises the tiltable furnace box 10 supported on the base structure 11. Preferably, non-magnetic material is used throughout. Where metal is required, bronze or other non-magnetic metal is used. Otherwise, asbestos board or like rigid insulating material such as is known in the trade by the name Transite, is employed in the construction.

The outer furnace box 10 is built up of rigid insulating board to form the bottom wall 13 and front and

rear walls

14 and 15, the side walls thereof not being shown in Figure 1. An induction heating coil 16 is formed of a plurality of turns of copper tubing 17, the

ends

18 and 19 of which extend through

openings

20 and 21 in the rear wall to

terminal blocks

22 and 23. The induction coil 16 is held rigidly in place by means of a mixture of a light weight castable refractory material such as Portland cement and expanded mica particlesknown by the name Vermiculite. The mixture is cast around the coil while in the inner furnace box 12 to provide thermal and electrical insulation as well as mechanical l The inside surfaces 24 of the coil are then covered with a layer of refractory cement reinforced by a single layer of asbestos cloth applied therewith to form a coil lining 25.

A conventional crucible (not shown) may be set into the coil to be used as a melting pot. The space between "ice the Crucible and coil lining may be packed with an appropriate insulating material.

It is preferred, however, to form a melting pot 26 by inserting a thin metallic former 27 around which a refractory material 28 may be rammed. A dry ramming refractory mix containing a small amount of sodium silicate and moisture is employed for forming the pouring lip 29. The metallic former 27 may be washed out with the first melt. It is preferred, however, to employ a former having a slight inward taper and to coat it with paraffin to enable removal after ramming prior to undertaking a melt in the pot so formed. Power may be applied for a short time to facilitate the removal of such a tapered liner. The flexibility thus afforded in pot shape, not removal and replacement is readily apparent to skilled persons in contrast with the size and shape limitations of crucibles. Moreover, a rammed pot is serviceable to higher temperatures in general than a corresponding7 crucible.

The inner furnace box 12 containing the coil 16 and pot 26 is removably mounted in the outer furnace box 10. The latter comprises the bottom wall 13, side walls 30, front and

rear walls

14 and 15 and the top retaining panel 31. The walls of both the inner and outer furnace boxes are held in assembly by means of

bronze screws

32 and 33 at the wall joints. A stop 34 held by bronze screw 35 retains the inner furnace box in spaced relation to the rear wall 15 to permit introduction of water conducting power leads 36 for fixture to

terminals

22 and 23. The leads 36 are clamped by a clamping block 37 to the outer edge of the bottom wall 13 by bronze bolts 37a.

The base structure 11 and tipping apparatus is shown in more detail in Figures 2 to 4. The bottom wall 13 of the outer furnace box 10 is supported by the forwardly located primary fulcrum bracket 38 on the pivot pin 39 in support 40 of platform 41. Two fulcrum arms 41a rise forwardly and upwardly from a base plate 42 on either side of the outer furnace box as at 48 near below the lip in the region of the front panel 14.

fn operation, the cylinders 43 in their retracted position, support the outer furnace box 10 substantially in an upright position by means of the pivotal connection 49 of their piston arms 50 to the side mounting brackets 51 of box 10. Actuation of the pressure cylinder causes outward extension of their pist-on arms causing initial tipping of the box 10 and furnace, therein, on primary fulcrum bracket 38 about pivot pin 39, as shown in Figure 3. Figure 4 illustrates final or secondary tipping motion of the box 18 on the `secondary fulcrum pins 47 upon moving into registry with the sockets 46 of the fulcrum arms 41a. Notice Ithat Isockets 46 are spaced a distance from the pivot pin 39 equal to the radius -of the forwardly extending socket slot 52 of primary fulcrum bracket 38 wherein the said radius is described from the secondary fulcrum pins 47.

it will be Iapparent that 'any well-known source of pressure medium may be employed for actuating the pressure cylinders. While it is desired that the apparatus shown be 4constructed so that single acting pressure cylinders only are required wherein the furnace box 10 returns to the upright position under action of gravity, double acting cylinders may also be employed.

It is contemplated that a plurality of inner furnace boxes each containing the induction heating coil and rammed lining may be kept on hand to provide `an even greater flexibilitty of operation. The inner furnace box is readily removed by removal of the top retaining panel of box 10.

It is intended that alternatives and modifications falling Within the scope of ordinary skill in the art shall be embraced by the present disclosure which sets forth the preferred practice of the invention.

What l claim as my invention is:

1. An'induction melting furnace comprising: afurnace box having an open `end and formed from a rigid heat insulating material; aninduction heating coil in said box spaced fromthe walls thereof; an insulating cement between said coil and saidwalls rigidly supporting said coil in Vsaid box; and la removable rammed refractory melting pot form-ed within said coil and serving as a removable lining forsaid furnace.

2. Au induction melting furnace comprising: a furnace box having 'an Vopen end 'and formed from a rigid heat insulating material; an induction heating coil in said box spaced'fromfthe 'wallsthereof; an insulating cement between said coil -and said walls rigidly supporting said coil in said box; a refractory material rammed to a shape delining within said-coil melting pot; and an outer furnace box having side walls formed of a rigid insulating maieri-al' designed removably to mount said rst, mentioned furnace box.

3. An induction melting furnace comprising: a furnace ybox having an open end and formed from la rigid heat insulating material; anim-duction heating coil in said box 'spaced from the walls thereof; an insulating cement between said Vcoil and said walls rigidly supporting said coil in said box; a Vrefractory material rammed to a shape dewithin said coil VaV melting pot; a lining of 'asbestos cloth extending over the inner Surfaces of .said coil between said coil and said rammed refractory material; and an louter furnace box having side walls formed of Ia rigid insulating material. designed removablyto mount said first mentioned furnace box.

4. An induction melting-furnace comprising: a furnace box having an open endend formed from a rigidV heat insulating material; .aninduction .heating coil in said box spacedfrom thewalls thereof; lan insulating cement between said coil and said Walls rigidly supporting said coil in .said 'box; a refractorymaterial rammed to a shape erung within said coil a. melting pot; a metallic former defining the inner .side wail surfaces of said melting pot 'and Yadaptedito be removed therefrornby melting; and

hrst mentioned furnace box. v

5. An induction melting furnace comprising: a furnace box ha' ing an open end and formed from a rigid heat insulating material; an induction heating coil in said box spaced from the walls thereof; an insulating cement between said coil and said walls rigidly supporting said coil in said box; a refractoryrmaterial .rammed to `a shape-defining within said coil a melting pot; an outer furnace box having side walls formed of a rigid insulating material designed to removably' mount said 'first mentioned furnace box; primary fulcrum means mounting said outer furnace box for tipping motion; and a pressure cylinder supporting said outer furnace box on said primary fulcrum means in a melting position and designed to move said outer furnace box on said primary fulcrum means toward a pouring position.

6. An induction melting Ifurnace comprising: 'a furnace box having yan open end and formed from a rigid heat insulating material; an induction heating coil in said box spaced from the walls thereof; an insulating cement between said coil and said walls rigidly supporting said coil in said box; la refractory material rammed to a shape defining within said coil a melting pot; a pouring spout extending 'beyond said coil and lsaid furnace box at the open end thereof; and an outer furnace box having side walls formed of la rigid insulating material designed removably to mount sai-d rst mentioned furnace box.

7. An induction melting furnace comprising: a furnace box having an open end and formed from a rigid heat insulating material; an induction heating coil in said box spaced from the Walls thereof; an insulating cement between said coil and said Walls rigidly supporting said coil in said box; a refractory material rammed to a shape defining Within said coil a melting pot; a pouring spout extending beyond said coil and said furnace box at the open end thereof; an outer furnace box having side walls formedV of a rigid insulating material designed to removably mount said rst mentioned furnace box; primary fulcrum means mounting said outer furnace boxfor tipping motion; and a pressure cylinder supporting said outer furnace box on said primary fulcrum means in a melting position and designed to move said outer furnace boxv on said primary fulcrum means toward a pouring position.

v8. An induction melting .furnace comprising: a furnace box having an open end and formed from a rigid heat insulating material; an induction heating coil `in said box spaced from the walls thereof; an insulating cement between said Vcoil .and said walls rigidly supporting said coil in said box; a refractory material rammed to a shape defining Within said coil a melting pot; a pouring spout extending beyond said coil and said urnace box at lthe open end thereof; an outer furnace box having side Walls formed of a rigid insulating material designed to removably mount said first mentionedfurnace box; primaryfulcrum means mounting said outer furnace box for tipping motion; aapressure cylinder supporting said outer furnace box on said primary fulcrum means in a melting position and designed to move said outer furnace box on said Aprimary :fulcrum means toward a pouring position; and

Vheating coil supported in internal spaced `relation in said inner furnace box; and a refractory cement rigidly supporting said coil in said inner furnace box.

l0. An induction furnace comprising; an ,outer furnace box formed of slabs or rigid insulating material; a a support for said box including tilting mechanism therefor formed of substantially. non-magnetic material;` a removable Vinner furnace box supported in said outerbox and formedof a rigid heat-insulating material; an inductionheating coil supported in internal spaced relation lin said inner furnace box; a refractory Vcement rigidly supportingV said coil in said inner furnace boxzend a rammed refractory material defining a melting pot within said coil.

References Cited in the le of this patent UNITED STATES PATENTS