Title of Invention

A DEVICE FOR HOLDING ELECTRICAL HEATING ELEMENT COILS INSIDE FURNACES FOR ANNEALING STEEL PRODUCTS.

Abstract

A device for holding electrical heating element coils inside furnaces for annealing steel products, characterised in that the device comprises a metallic socket 1 having a threaded round bore 1a, fixed to the inner surface 2 of furnace shell 3 by- welding; a metallic plug 4 having a threaded round surface 4a and a flat surface 4b with a groove 5 cut along a diameter thereof, fitted into the socket like a bolt in a nut; a whistle-shaped metallic pipe 7 having a narrower round end 6 fixed perpendicularly to the flat surface 4b of the plug 4 at the centre of the groove 5 by welding, a conical part 6a and a cylindrical wider part 7a; a non-metallic bush 8 with a hexagonal nut 9 embedded therein, fitted tightly in the conical and cylindrical parts of the pipe 7 being introduced through the open end 10 thereof; a round metallic rod 11 having a narrower threaded part 12 which is introduced into the bush 8 from the open end 10 of the pipe 7 and fixed therein by screwing into the hexagonal nut 9, and an unthreaded wider part 12a with a flared end 13; and a non-metallic bobbin 16 having a narrower flange 17, a wider flange 18, a central bore 14 extended throughout the bobbin length and two slota 15, 15a cut on the wall of the central bore 14 in the diametrically opposite positions starting from the narrower flange 17 and extending upto the middle part of the bobbin length, into which the flared end 13 of the unthreaded wider part 12a of the rod 11 is introduced upto the middle part of the bobbin length and fixed in the central bore 14 by turning the bobbin 90° around the axis thereof, the space along the bobbin length lying between the narrower and wider flanges being provided for holding the electrical heating element coils of super kanthal by winding there around at a pitch 64 mm for heating uniformly different zones inside the furnaces, to a temperature of 950°C in ambient atmosphere. Reference Figure 1 of the drawings.

Full Text

The present invention relates to a device for holding electrical heating element coils inside furnaces for annealing steel products. In most of the mini steel plants, annealing of steel products is performed in batch-type annealing furnaces which are lined internally with refractory bricks having sinusoidally curved grooves for fixing electrical heating element coils thereinto. The drawbacks of refractory brick lining and holding system of heating element coil in refractory having high thermal mass are s (a) a large amount of heat energy is absorbed in the bricks during heating, which is lost during cooling thereof, when the furnace is switched off and (b) time required for both heating and cooling of the furnace is too long, leading to increased idle time and hence loss in productivity of the furnat The object of the invention is to provide a device for holding electrical heating element coils inside ceramic fib lined annealing furnaces in replacement of the existing refractory brick works to reduce Toss of heat energy, and the time for heating and cooling of the furnaces. The invented device comprises basically a metallic socket which is welded to the inner surface of the furnace shell after removing the ceramic bricks therefrom, the socket having a cylindrical bore with threaded internal surface; a threaded metallic plug with a groove on its outer flat surface, which is fitted in the bore of the socket in the manner of fixing a bolt in a nut; a whistle shaped metallic pipe which is fitted on the outer flat surface of the plug by welding the narrow end of the pipe in the groove of the plug; a ceramic bush v/ith a hexagonal nut embedded therein, which is fitted inside the pipe; a metallic rod having a threaded end which is fitted in the hexagonal nut embedded in the ceramic bush and a flared end which is introduced into the central hole of a non-metallic bobbin on which the electrical heating element coils i.e. of super kanthal are wound in the space between the two flanges thereof at the required pitch i.e. 64 mm so that the heat generated in all the zones inside the furnaces is uniformly distributed, the furnaces being lined internally with ceramic fibre upto the end of the rod lying outsic the central hole of the bobbin. The invention is described fully and particularly without restricting its scope in any manner v/ith reference to the accompanying drawings in which - Figure 1 is a partly sectional elevation of the invented device. Figure 2 is a sectional view of the furnace. Referring to Fig. 1, the device comprises a metallic socket 1 having a threaded bore 1a and being fixed to the inner wall 2 of furnace shell 3 by welding; a metallic plug 4 having a threaded round survace 4a and a flat surface 4b with a groove 5 cut along a diameter thereof, fitted into the socket like a bolt in a screw; a whistle-shaped metallic pipe 7 having a narrov/er round end 6 which is fixed perpendicularly to the flat surface 4b of the plug 4 at the centre of the groove 5 by welding, a conical part 6a and a cylindrical wider part 7a; a non-metallic bush 8 v/ith a hexagonal nut 9 embedded therein, fitted tightly in the conical and cylindrical parts of the pipe 7, being introduced through the open end 10 thereof; a round metallic rod 11 having a narrower threaded part 12 which is introduced into bush 8 from the open end 10 of pipe 7 and fixed therein by screwing into the hexagonal nut 9, and an unthreaded wider part 12a v/ith a flared end 13; and a non-metallic bobbin 16 having a narrower flange 17, a wider flange 18, a central bore 14 extended throughout the bobbin length and two slots 15, 15a cut on the wall of the central bore 14 in the diametrically opposite positions starting from the narrower flange 17 and extending upto the middle part of the bobbin length, into which the flared end 13 of the unthreaded wider part 12a of the rod 11 is introduced upto the middle part of the bobbin length and fixed in the central bore 14 by turning the bobbin 90° round the axis thereof, the space along the bobbin length lying between the narrower and wider flanges being provided for holding the super kanthal electrical heating element coils by winding therearound at a preferred pitch 64 mm for heating uniformly different zones inside the furnaces to a temperature of 950°C in ambient atmosphere, without causing any adverse effect on the bush and bobbin. Typical dimensions and materials of the various components of the device are presented in Table I. The performance of a number of annealing furnaces fitted v/ith the invented device, instead of the conventional refractory bricks, for holding the electrical heating element coils has been studied over a period in a steel plant. The loss of heat energy in the furnace has been reduced by 25-30%. The time for heating and cooling of the furnaces has been also reduced appreciably with consequent reduction in the idle time of the furnace. We Claim :- 1. A device for holding electrical heating element coils inside furnaces for annealing steel products, characterised in that the device comprises a metallic socket 1 having a threaded round bore 1a, fixed to the inner surface 2 of furnace shell 3 by welding; a metallic plug 4 having a threaded round surface 4a and a flat surface 4b with a groove 5 cut along a diameter thereof, fitted into the socket like a bolt in a nut; a whistle-shaped metallic pipe 7 having a narrower round end 6 fixed perpendicular to the flat surface 4b of the plug 4 at the centre of the groove by welding, a conical part 6a and a cylindrical wider part 7a; a non-metallic bush 8 with a hexagonal nut 9 embedded therein, fitted tightly in the conical and cylindrical parts of the pipe 7 being introduced through the open end 10 thereof; a round metalli rod 11 having a narrower threaded part 12 which is introduced int the bush 8 from the open end 10 of the pipe 7 and fixed therein t screwing into the hexagonal nut 9» and an unthreaded wider part 1 with a flared end 13; and a non-metallic bobbin 16 having a narrower flange 17, a wider flange 18, a central bore 14 extended throughout the bobbin length and two slots 15, 15a cut on the v/al of the central bore 14 in the diametrically opposite positions starting from the narrower flange 17 and extending upto the middl part of the bobbin length, into which the flared end 13 of the unthreaded wider part 12a of the rod 11 is introduced upto the middle part of the bobbin length and fixed in the central bore 14 by turning the bobbin 90° around the axis thereof, the space alor the bobbin length lying between the narrower and wider flanges being provided for holding the electrical heating element coils of super kanthal by winding there around at a pitch 64 mm for heating uniformly different zones inside the furnaces, to a temperature of 950°C in ambient atmosphere. 2. The device as claimed in claim 1, wherein the socket, plug, pipe and rod are each made of stainless steel of type AISI-304. 3. The device as claimed in claim 1 or 2, wherein the bush and bobbin are each made of ceramic containing (by weight %) : hard-fired A12O3 - 50 to 60, SiO2 - 39 to 49, Fe2O5 - 1.0 max. A device for holding electrical heating element coils inside furnaces for annealing steel products, characterised in that the device comprises a metallic socket 1 having a threaded round bore 1a, fixed to the inner surface 2 of furnace shell 3 by- welding; a metallic plug 4 having a threaded round surface 4a and a flat surface 4b with a groove 5 cut along a diameter thereof, fitted into the socket like a bolt in a nut; a whistle-shaped metallic pipe 7 having a narrower round end 6 fixed perpendicularly to the flat surface 4b of the plug 4 at the centre of the groove 5 by welding, a conical part 6a and a cylindrical wider part 7a; a non-metallic bush 8 with a hexagonal nut 9 embedded therein, fitted tightly in the conical and cylindrical parts of the pipe 7 being introduced through the open end 10 thereof; a round metallic rod 11 having a narrower threaded part 12 which is introduced into the bush 8 from the open end 10 of the pipe 7 and fixed therein by screwing into the hexagonal nut 9, and an unthreaded wider part 12a with a flared end 13; and a non-metallic bobbin 16 having a narrower flange 17, a wider flange 18, a central bore 14 extended throughout the bobbin length and two slota 15, 15a cut on the wall of the central bore 14 in the diametrically opposite positions starting from the narrower flange 17 and extending upto the middle part of the bobbin length, into which the flared end 13 of the unthreaded wider part 12a of the rod 11 is introduced upto the middle part of the bobbin length and fixed in the central bore 14 by turning the bobbin 90° around the axis thereof, the space along the bobbin length lying between the narrower and wider flanges being provided for holding the electrical heating element coils of super kanthal by winding there around at a pitch 64 mm for heating uniformly different zones inside the furnaces, to a temperature of 950°C in ambient atmosphere. Reference Figure 1 of the drawings.

Documents:

2218-cal-1998-granted-abstract.pdf

2218-cal-1998-granted-assignment.pdf

2218-cal-1998-granted-claims.pdf

2218-cal-1998-granted-correspondence.pdf

2218-cal-1998-granted-description (complete).pdf

2218-cal-1998-granted-drawings.pdf

2218-cal-1998-granted-examination report.pdf

2218-cal-1998-granted-form 1.pdf

2218-cal-1998-granted-form 2.pdf

2218-cal-1998-granted-form 3.pdf

2218-cal-1998-granted-form 6.pdf

2218-cal-1998-granted-pa.pdf

2218-cal-1998-granted-reply to examination report.pdf

2218-cal-1998-granted-specification.pdf