Claims
- 1. An induction heating furnace comprising:
- (a) an induction coil assembly having a central axis and a preselected axially extending length, said induction coil assembly comprising a coil, an upper, a lower and an intermediate yoke, said upper and lower yokes being axially separated from each other by a predetermined distance and electromagnetically coupled together by said intermediate yoke; and
- (b) means for holding a material to be heated by said furnace-comprising a crucible, having a preselected shape, and a shell surrounding and generally conforming to said shape of said crucible, said shell comprising bars of non-magnetic metallic material and located so as to be surrounded by, but not touching, said induction coil assembly, said shell extending past both said upper and lower yokes each by a respective preselected distance.
- 2. An induction heating furnace according to claim 1, wherein said upper, lower and intermediate yokes each comprises stacked laminates formed of sheets of ferrous material.
- 3. An induction heating furnace according to claim 2, wherein said upper and lower yokes comprise laminates of a non-grain-oriented electrical steel material, and said intermediate yoke comprises laminates of a grain-oriented electrical steel material.
- 4. An induction heating furnace according to claim 1, wherein said crucible, said shell, and said upper and lower yokes, all have a cylindrical shape.
- 5. An induction heating furnace according to claim 1, wherein said bars have opposite ends respectively joined to top and bottom rings respectively positioned above and below said upper and lower yokes.
- 6. An induction heating furnace according to claim 5, wherein each of said bottom rings has a flange.
- 7. An induction heating furnace according to claim 5, wherein said holding means further comprises a bottom plate resting on said flange of said bottom ring.
- 8. An induction heating furnace according to claim 1, wherein said upper and lower yokes are separated from said coil by at least one respective insulative segment and said intermediate yoke is also separated by said coil by at least a sheet of dielectric material.
- 9. An induction heating furnace according to claim 1, further comprising upper and lower covers respectively connected to said upper and lower yokes.
- 10. An induction heating furnace according to claim 1, wherein said induction coil assembly is separated from said shell by a layer of insulative material and an air gap.
- 11. An induction heating furnace according to claim 10, wherein said layer of insulative material is of grout material.
- 12. An induction heating furnace according to claim 8, wherein said coil has a layer of silicon rubber material separating the coil from said sheet of dielectric material.
- 13. An induction heating furnace according to claim 1, wherein said coil is pre-stressed by said upper and lower yokes so as to reduce its operational movement, vibration and noise.
- 14. An induction heating furnace according to claim 1, wherein:
- (a) said upper and lower yokes each has substantially the same inner and outer diameter dimensions referenced to said central axis; and
- (b) said intermediate yoke has an inner diameter which is greater than that of said inner diameter dimension of said upper and lower yokes, said intermediate yoke also has an outer diameter which is less than the outer diameter dimension of said upper and lower yokes.
- 15. An induction heating furnace according to claim 14, wherein said upper and lower yokes: comprise an arrangement of stacked laminates, having
- (a) groups of first and second sheets each having different lengths and with the length of the second sheets being less than the length of the first sheets; and
- (b) sequential and repeating arrangements of a pair of said first sheets and then a single one of said second, sheets wherein each of said second sheets is sandwiched between multiples of pair of said first sheets, each of said first multiples sheets having their width spanning said inner and outer diameter dimensions of said upper and lower yokes, and each of said second sheets having one of its ends coinciding with a circumference defined by said outer diameter dimension.
- 16. An induction heating furnace according to claim 14, wherein said upper and lower yokes comprise an arrangement of stacked layers, having:
- (a) groups of first and second sheets having different lengths and with the length of the second sheets being less than the length of the first sheets; and
- (b) sequential and repeating arrangements of one of said first sheet and then one of said second sheet, each of said first sheet having a width spanning said inner and outer diameter dimensions of said upper and lower yokes, and each of said second sheets has one of its ends coinciding with a circumference defined by said outer diameter dimension.
- 17. An induction heating furnace according to claim 15, wherein at least one of said upper and lower yokes includes at least one non-magnetic wedges therein having provisions for accepting a power cable for operation of said coil.
- 18. An induction heating furnace according to claim 16, wherein each of said upper and lower yokes further comprises one or more ceramic wedges located at areas of said induction coil assembly having provisions for accepting a power cable for operating said coil.
- 19. An induction heating furnace according to claim 14, wherein said intermediate yoke comprises groups of sheets each having the same length and spanning said inner and outer diameter dimensions of said intermediate yoke, said groups being uniformly distributed about the region of a circumference defined by said inner and outer diameter dimensions of said intermediate yokes.
- 20. An induction heating furnace according to claim 1, further comprising an upper member serving as a top portion, a central portion, and a lower member serving as a bottom portion, said top, central and lower portions being mated together by sealing members, said upper member, central portion and lower member providing a sealed environment for said induction furnace allowing it to serve as a vacuum type induction furnace.
- 21. An induction heating furnace according to claim 20, wherein said sealing members comprise O-rings.
Parent Case Info
This is a continuation-in-part of application Ser. No. 07/532,010 filed on Jun. 1, 1990, now U.S. Pat. No. 5,272,720 which, in turn, is a continuation-in-part of application Ser. No. 07/473,000 filed Jan. 31, 1990, now U.S. Pat. No. 5,257,281. The disclosure of each of the U.S. applications Ser. Nos. 07/532,010 and 07/473,000 are herein incorporated by reference.
US Referenced Citations (11)
Foreign Referenced Citations (5)
Number |
Date |
Country |
0053070 |
Jun 1982 |
EPX |
0152849 |
Aug 1985 |
EPX |
0232846 |
Aug 1987 |
EPX |
2368542 |
May 1978 |
FRX |
2127333 |
Dec 1971 |
DEX |
Non-Patent Literature Citations (1)
Entry |
Patent Abstracts of Japan, vol. 5, No. 112 (M-79) 21 Jul. 1981 & JP-A-56 053 868 (Fuji Denki Seizo K. L.) 13 May 1981. |
Continuation in Parts (2)
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Number |
Date |
Country |
Parent |
532010 |
Jun 1990 |
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Parent |
473000 |
Jan 1990 |
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