US3398939A - Shuttle hearth furnaces - Google Patents

Description

Aug. 27, i968 w. A. MORTON SHUTTLE HEARTH FURNACES 5 Sheets-Sheet l Filed Aug. 26, 1966 INVENTOR.

William A. Morton ug. 27, 1968 w. A. MoRToN 3,398,939

SHUTTLE HEARTH FURNACES INVENTOR.

William A. Moron lAug. 27, 1968 w. A. MORTON SHUTTLE HEARTH FURNACES 5 Sheets-Sheet 3 Filed Aug. 26, 1966 INVENTOR.

William A. Morton GNN E.. el

www sv fom Nv VMMMVVMVMM@ Unite ABSTRACT F THE DISCLOSURE Work is heated in a furnace while it is moved from a point of entry to exit. A pair of normally raised herringbone walker frames carry the work. The frames are advanced, lowered, retracted and raised in one cycle. The cycle is repeated until the work is shuttled through the furnace. The walker frames are positioned between longitudinal walls which support the work when the frames are lowered below the height of the longitudinal walls. Seals between the walker frames and the longitudinal walls prevent heat from escaping from the furnace while the work is being shuttled.

This invention relates to shuttle hearth furnaces and is particularly adapted for use in metallurgical furnaces which operate at high temperatures.

Certain mass produced fiat metal products are made from bars. The surfaces of the products are heated in a furnace and generally are pushed on conventional water cooled skids. The skids frequently cause defective surfaces of the products because of the contact with the water cooled skids. The marred metal is costly to separate from the unmarred metal. This is particularly true of most non-ferrous and stainless steel metals. Roller hearth furnaces have been designed to eliminate the defects above mentioned to the metal plate, however, roller hearth furnace has limitations as to span and temperature, and requires expensive alloys for the rolls. The skid type requires a pushing device for moving the work load. In addition it requires considerably more fuel to heat the cooling water. These tWo types of conveyors support the work substantially in the midhorizontal plane through the furnace.

The present invention solves these problems by providing an economical dry conveyor which is not subject to any cooling requirement and substantially eliminates surface defects due to relative frictional motion between the work pieces during their movement through the furnace. The present invention also provides for uniform heating of the work. Work is supported in a normally raised position by a pair of walking beams. The walking beams each carry a vertical wall of spaced herringbone refractories. The Walking beam which sup-ports the herringbone refractory is capable of supporting bars, slabs and the like and move them in spaced relation through the middle horizontal plane of the furnace. This allows top, bottom and side heating without `abrading the surfaces of the metal. The herringbone configuration is capable of supporting any size bar because the vertex of the herringbone refractory reaches the trailing edge line of the succeeding herringbone refractory. The herringbone walls are spaced so as to allow heat to pass through the bottom portion of the herringbone wall to thereby heat the under side of the work. The work is also normally in the raised position and supported where States Patent C) ice desired only by the herringbone configuration whereby heat can also be uniformly applied and distributed along the end faces of the work. The herringbone configuration insures uniform heating of all parts of the work because the herringbone does not touch the same point on the work as the work is being shuttled through the furnace by the carrier members. The use of the herringbone configuration also permits effective transverse firing below the bottom surface of the work. The work may be advanced within the furnace in batches or groups to reduce the number of lifts and la go-getter for removing the work pieces from the furnace at the exit end of the furnace may pick up the batches either singularly or in groups and the lift and traverse mechanism for the walking beam or walker which supports the herringbone refractory wall would, with such object in view, be coordinated with the go-getter.

It must be noted that the herringbone construction may take on many forms such as a single angle with its apex at the center of the furnace with a series of zigzag walls forming several apexes across the furnace. The zigzag walls or herringbone construction properly supports work of varying thicknesses and lengths at required intervals. Transverse spaces between the wall forming the herringbone construction are essential for proper heating.

Using such .a shuttle hearth furnace saves fuel by eliminating water skids and increases product yield by uniformly heating the work `above and below due to the substantial elimination of continuous contact at the same point throughout the hearth.

I provide a shuttle hearth furnace for moving work from a point of entry to exit while subjecting it to heat comprising a structure having side Walls and a roof, a plurality of longitudinal walls spaced transversely forming a portion of the furnace hearth, and depending upon the size of the furnace one or more longitudinal horizontal walker frames positioned within the spaces between the walls, the walker frames support vertical refractory walls, the top surface of the refractory on the walker frames is normally raised above the top horizontal surface of the walls, and means performing the following cycle of movement on the walker frame: horizontally moving each of the walker frames in the direction of exit, lowering each of the walker frames to a point below the top surface of the walls, horizontally moving each of the walker frames in the direction of entry, then raising the walker frame to the original normal position whereby work normally resting on the top of the walker frames is above the top surface of the walls and is advanced toward the exit of the furnace.

It should be understood that when two rows of short pieces are moved through the furnace that one Walker may be moved more frequently than the other to discharge one row at a greater speed than the other, and selectively with single long work pieces passing through the furnace, the walker movements may be synchronized to cause the pieces to advance uniformly when supported by more than one walker.

I preferably provide that the refractory walls on the walker vframes are of herringbone shape and that successive herringbone configurations are longitudinally spaced. I provide a plurality of spaced burner jets having a horizontal row within each side wall of structure, one row positioned above the herringbone hearth and another row positioned below the herringbone hearth. I provide flue exhaust ports between the spaced burner jets below the top surface of the herringbone refractory. I preferably provide that the longitudinal walls have a plurality of ports through which heat from the burner jets positioned below the herringbone refractory may pass one side wall of the structure, and through the herringbone refractory wall to the other side wall of the structure all to insure uniform distribution of fuel and the resultant heating gases. I provide a go-getter at the exit end of the furnace having a frame, a trackway, a pair of rollers mounted on the frame and riding on the trackway, a vertical member extending downwardly from the frame, and a pair of horizontal arms extending from the vertical member, the arms spaced apart to enter the exit end of the furnace adjacent to each of the herringbone refractory walkers. The go-getter arms are then raised lifting the work and the frame is moved from the exit end removing the work from the furnace.

A suitable dry sealing means as between the movable and fixed members of the hearth is provided at each longitudinal joint where such members exist, whereby unwanted external atmosphere .is prevented from entering the furnace during the operation of the elements required to support the work in the furnace and advance it through the furnace for heating.

Other details, objects and advantages of the invention will become apparent as the following description of a present preferred embodiment and present preferred method of practicing the same proceeds.

In the accompanying drawings I have shown a present preferred embodiment of the invention and have illustrated a present preferred method of practicing the same in which:

FIGURE 1 is a longitudinal cross-sectional view of the furnace structure;

FIGURE 2 is a sectional end view of FIGURE l;

FIGURE 3 is a top sectional view of FIGURE l;

FIGURE 4 is a lfragmentary sectional view of a longitudinal wall taken on line IV-IV of FIGURE 3;

FIGURE 5 is a diagrammatic illustration of the exit zone of the furnace showing a sequence of steps for spacing billets; and

FIGURE 6 is an enlarged fragmentary view of the seals shown in FIGURE 2.

The furnace structure 10 having a point of entry 12 and an exit 1 has side walls 16 and 18 and roof 20. The furnace structure has a -plurality of longitudinal walls 22, 24 and 26 spaced transversely forming a portion of the furnace structure hearth. A pair of walker frames 28 and 30 are normally above the top surface of the longitudinal walls 22, 24 and 26. This is to allow even heat to pass on the ends of bar stock 36. The furnace structure 10 has a plurality of burner jets 38 forming a horizontal row with each side wall 16 and 18. Another horizontal row of spaced burner jets 40 are positioned below the top surface of the herringbone refractories 32 and 34 and within the side walls 16 and 18 of the structure 10 and between the lower spaced burner jets 40 are a plurality of flue ports 46 which are connected to flue stack 48. The herringbone structure 34 and 32 is shaped wherein each is aligned so that the vertexes 42 and 44 reach to a distance of at least the trailing edge line of the succeeding herringbone refractory formed between points 50, 52 and 45, 47. The longitudinal walls 22, 24 and 26 have port openings 51 as shown in FIGURE 4 which allow heat from the Iburner jets 40 to pass from walls 22 and 26 through the refractory 34 and 32 and through the center wall 24. To remove the bar stock 36 from the furnace 10 at the exit end 14, a go-getter 62 having a frame 53, a trackway 54, a pair of rollers 56 and a vertical member 58 having a pair of horizontal arms 60 extending from the vertical member 58 is inserted into the exit end 14 adjacent the walker frames 28 and 30 and `supporting refractory walls 32 and 34. The arms 60 are then raised removing the bar stock 36.

The means used to shuttle or convey the bar stock 36 from the entry end 12 to the exit end 141s as follows: a horizontal bar 64 is positioned beneath the walker frames 28 and 30 in a pit 66 directly lbeneath the furnace structure 10. Each horizontal bar 64 has a plurality of upwardly extending rods 68 which are pivotally connected to the horizontal bar 64. The other end of the upwardly extending rod 68 is connected to the horizontal bar 0r drum 70. The horizontal bar or drum 70 has further upwardly extending arms 72 which are connected to axle 74 having rollers 76 engaging the bottom of walker frames 28 and 30. The one end of the horizontal bar 64 is connected to the piston 78 engaging hydraulic cylinder 80. Hydraulic piston 82 engaging hydraulic cylinder 84 is connected to walker frame 28. The other walker frame 30 has a similar arrangement whereby it has identical cylinders and pistons connected in a similar manner as previously shown for walker frame 2S. When the piston 78 extends to the left the walking frame 28 is lowered and when the piston extends to the right walking frame 28 is raised. A similar lift cylinder raises and lowers walking frame 30. Cylinder 84 moves piston l82 horizontally whereby walking frame 28 is moved horizontally depending on the movement of the piston 82. A sequence for moving rods 36 through the furnace .10 is as follows: A rod is placed on charge table 86 and pusher 88 pushes the bar stock 36 into the entry end 12 of the furnace 10 and onto the refractories .34 and 32 supported by walking frames 28 and 30 respectively. Piston 82 moves to the left moving the walking frame 28 and a similar piston moves walking frame 30 at the same time to the exit end. The piston 78 moves t-o the left lowering walking frame 28 and a similar piston and linkage arrangement lowers walking frame 30. The frames 28 and 30 are lowered to a point whereby their top surfaces are at least just below the top surface of the walls 22, 24 and 26 upon which the bar stock 36 rests. The piston 82 moves to the right and back to the original entry end 12 of the furnace 10 and the piston 78 moves to the right to the entry end 12 whereby walking frames 28 and 30 are raised to receive the next piece of bar stock 36 and move the original bar stock 36 further into the furnace on to the exit end.

The go-getter 62 lifts the bar stock 36 out of the exit end 14 of the furnace 10. FIGURE 5 shows the spacing of billets 36 after they have entered the exit zone and into the soak zone of the furnace. The go-getter fork arm 60 picks up the four end billets and retracts them away from the advancing billets. The arm again lifts and retracts thereby spacing the remaining three billets as down to the last billet. This is accomplished by a series of lift, retracting and drop steps of the arm and can be suitably controlled by a servo mechanism (not shown in the drawings). The advance magnitude of the shuttle hearth can be varied to function with the arm 60. When the billets 36 enter the soak zone the flow of heat volume is accelerated while maintaining the temperature below the allowable critical to insure nal uniformity.

During the operation of the walker frames 28 and 30 the entire hearth is sealed whereby unwanted external atmosphere is prevented from entering the furnace. `A partition 104 extends vertically downward from wall 22. Another partition 106 attached to walker frame 28 extends vertically downward. A seal plate 108 pivots at 110 about the bottom of partition 106 with the other end contacting continuous pipe 112. A counterweight 114 pivoted at 110 urges plate 108 against the continuous pipe 112. Whenever the walker frame 28 moves up the partition 106 moves with it and the counterweight 114 and seal plate 108 are in the position shown in chain line whereby the hearth is sealed during movement of the frame 28. A similar seal arrangement is used between the other spaces. The hearth bed is supported by sub-supports 90, 92, .94, 96, 98, and 102.

It must be understood that various time mechanisms can be used in connection with the go-getter, the pusher and the two hydraulic cylinders whereby the speed of travel and the amount of bar stock fed into and lifted out of the furnace can be regulated. Whenever the 'bar stock is being carried through the furnace by the herringbone configuration 32 and 34 the herringbone configuration generally does not touch the bar stock at the same point, which is an advantage of using the herringbone configuration. The herringbone configuration is normally in the raised position permitting unifonm heat to reach the ends of the bar stock which are eventually supported on walls 22 and 26 and in the center by wall 24.

It must be further understood that two work pieces can move through the furnace at the same time and they may move at different rates. While the lift and traverse mechanisms have been described in synchronization for moving single pieces, the mechanisms can operate independently.

While l have shown and described the present preferred embodiment of my invention, it is to be understood that I do not limit myself thereto and that my invention may 'be otherwise variously practiced within the scope of the following claims.

I claim:

1. A shuttle hearth furnace for moving work from a point of entry to exit while subjecting it to heat comprising:

(a) A strructure having side walls and a roof;

('b) A plurality of longitudinal walls spaced transversely forming a portion of the furnace hearth;

(c) A pair of longitudinal horizontal walker frames positioned within the spaces between the walls, the walker frames Ihave refractory on top forming a vertical wall, -the top surface of the refractory on the walker frames is normally raised above the top horizontal surface of the walls; and

(d) Means performing the following cycle of movement on the walker frame: horizontally moving each of the walker frames in the direction of exit, lowering each of the Walker frames to a point lbelow the top surface of the walls, horizontally moving each of the walker frames in the direction of entry, then raising the walker frame to the original normal position whereby work normally resting on the top of the walker frames is above the top surface of the walls and is advanced toward the exit of the furnace.

2. A shuttle hearth furnace as recited in claim 1 including a -dry means for sealing between each horizontal walker frame and the adjacent wall on each side of the walker frame whereby lunwanted external atmosphere is prevented from entering the furnace during movement of the walker frames.

3. A shu-ttle hearth furnace as recited in claim 1 wherein the refractory wall on the walker frames is herringbone shaped and the successive herringbone configurations are longitudinally spaced.

4. A shuttle hearth furnace as recited in claim 3 including:

(a) A plurality of spaced burner jets having a horizontal row within each side wall of the structure and positioned above the herringbone hearth;

(b) A plurality of spaced burner jets having a horizontal row within each side wall of the structure positioned below the top surface of the herringbone refractory; and

(c) The longitudinal walls having a plurality of ports through which heat from the burner jets positioned below the herringbone refractory may pass from one side wall of the structure, and through the herringbone refractory wall to the other side wall of the structure.

5. A shuttle hear-th furnace as recited in claim 4 including a plurality of flue ports in each of the side walls positioned between the burner jets below the herringbone refractory hearth.

6. A shuttle hearth furnace as recited in claim 5 wherein the herringbone refractory is shaped wherein the vertex of the herringbone reaches to a distance at least up to the trailing edge of the succeeding herringbone refractory.

7. A shuttle hearth furnace as recited in claim 6 including a go-getter at the exit end of the furnace, the go-getter having:

(a) A frame;

(b) A trackway;

(c) A pair of rollers mounted on the frame and riding on the trackway;

(d) A vertical member extending downwardly from the frame; and

(e) A pair of horizontal arms extending from the vertical member, the arms spaced apart to enter the exit end of the furnace adjacent to each of the herringbone refractory walkers, the arms are below the herringbone refractory when entering, they are then raised lifting the work and the frame is moved from the exit end removing the work from the furnace.

8. A shuttle hearth furnace as recited in claim 7 wherein the means performing the cycle of movement on each walker frame comprises:

(a) A horizontal arm beneath the walker frame;

(-b) A plurality of upwardly extending rods having one end pivotally attached to the horizontal arm;

(c) A plurality of horizontal rods coupled to the upwardly extending rods;

(d) A pair of rollers corresponding to each horizontal rod, the rollers in contact with the bottom of the walker frame;

(e) Means coupling the rollers to the horizontal rod,

Whenever a vertical rod angularly moves an associated movement results in raising or lowering the roller height from `the horizontal arm;

(f) A first hydraulic piston and cylinder having the piston connected to one end of the horizontal arm, movement of the piston changes the height o-f the rollers whereby the Walker frame is raised or lowered; and

(g) A second hydraulic piston an'd cylinder having the piston horizontally connected directly to one end of the walker frame whereby movement of the piston results in horizontal movement of the walker frame.

9. A shuttle hearth furnace as recited in claim 8 wherein the means sealing comprises:

(a) A first partition attached to the edge of the wall adjacent to the walker frame and vertically extending downwardly;

(b) A second partition attached to the edge of the walking frame and vertically extending downwardly; and

(c) A seal plate pivote-d about the second partition having its other end urged against the bottom of the first partition.

10. A method of spacing apart a batch of heated billets for a uniform soak in a shruttle hearth furnace'after they reach the exit zone of the furnace which comprises, controlling a series of lift, retraction and drop steps of a discharge fork which engages the heated billets.

11. A method as recited in claim 10 including varying the magnitude of the advance of the shuttle hearth within any series of advances of the shuttle hearth.

12. A method as recited in claim 11 including accelerating the flow of heat volume while maintaining the temperature 'below the allowable critical to insure final uniformity.

13. A shuttle hearth furnace as recited in claim 2 wherein the dry means for sealing comprises:

(a) A first partition attached to the edge of the wall adjacent to the walker frame and vertically extending downwardly;

(b) A second partition attached to the edge of the walker frame adjacent to the wall having the first partition and vertically extending downwardly;

7 8 (c) A seal plate pvoted about the second partition 2,3 80,452 7/ 1945 Kohout 263--21 having its other end urged against the bottom of the 3,119,606 1/ 1964 Suydam et al 263--6 X rst partition' FOREIGN PATENTS References Cited D UNITED STATES PATENTS 5 813,362 5/ 1959 Great Bntam.

1,400,367 12/ 1921 McCann 263-6 JOHN J. CAMBY, Acting Primary Examiner.

1,924,218 8/1933 Stevens 263-6 UNITED STATES PATENT OFFICE CERTIFICATE OE CORRECTION Patent No. 3,398,939 August 27, 1968 William A. Morton It s certified that error appears in the above identified patent and that saicl Letters Patent are hereby corrected as shown below:

Column 3, line 5, after "pass" insert from line 45, "l" should read 14 Column 4 line 52 after "arm" inser' 60 Column 6, line 4, after "edge" insert line Signed and sealed this 3rd day of February 1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR

Commissioner of Patents Edward M. Fletcher, Jr.

Attesting Officer

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