US3713631A

US3713631A - High temperature furnace and conveyor therefor

Info

Publication number: US3713631A
Application number: US00121827A
Authority: US
Inventors: A Enk; D Franks
Original assignee: Midland Ross Corp
Current assignee: Surface Combustion Corp; Grimes Aerospace Co
Priority date: 1971-03-08
Filing date: 1971-03-08
Publication date: 1973-01-30
Anticipated expiration: 1990-01-30
Also published as: AU3905272A; CA958532A; GB1383833A

Abstract

A billet reheating furnace having a refractory surfaced walking beam conveyor with a lateral discharge means located within the furnace below the hearth line of the furnace at the discharge end of the walking beam conveyor. The walking beam conveyor is supported on pivotal stiff legs so it may be readily lowered beneath the hearth for servicing. A reciprocable transfer means is provided to lower a heated workpiece from the end of the walking beam conveyor to the lateral discharge means without impact. The transfer means cooperates with the walking beam conveyor to rotate the workpiece a portion of a revolution.

Description

United States Patent [1 1 Enk et al.

[541 HIGH TEMPERATURE FURNACE AND CONVEYOR THEREFOR [75] inventors: Albert T. Enk, Toledo; David B.

Franks, Maumee, both of Ohio [73] Assignee: Midland-Ross Corporation, Toledo,

Ohio

[22] Filed: March 8, 1971 [21] Appl. No.: 121,827

[52] U.S. Cl. ..263/6 A [51] Int. Cl. ..F27b 9/14, F27d 3/00 [58] Field of Search ..263/6 R, 6 A

[56] References Cited UNITED STATES PATENTS 3,450,394 6/1969 Wilde et al. ..263/6 A FOREIGN PATENTS OR APPLICATIONS l,143,841 2/1963 Germany ..263/6 A 1 Jan. 30, 1973 3/1955 ltaly ..263/6A l/l963 Germany ..263/6 A [57] ABSTRACT A billet reheating furnace having a refractory surfaced walking beam conveyor with a lateral discharge means located within the furnace below the hearth line of the furnace at the discharge end of the walking beam conveyor. The walking beam conveyor is supported on pivotal stiff legs so it may be readily lowered beneath the hearth for servicing. A reciprocable transfer means is provided to lower a heated workpiece from the end of the walking beam conveyor to the lateral discharge means without impact. The transfer means cooperates with the walking beam conveyor to rotate the workpiece a portion of a revolution.

PATENTEUJAN so 1975 SHEET 18F 4 x Hamill "II" I Q NN PATENTEUJAH 30 1975 SHEET 2 OF 4 INVENTORS. 7: ENK

Arron Ne PATENTEDJAH 30 I975 SHEET 30F 4 wall INVENTORS. ALBERT 7'. ENK on W0 8. FEHNKS B fl-r'rakuev' HIGH TEMPERATURE FURNACE AND CONVEYOR THEREFOR BACKGROUND OF INVENTION I those having a temperature on the hearth which approaches or exceeds the yield temperature of most steel alloys, for example about 2200 F. The invention is especially adapted for the heating to a forging temperature of large elongated titanium or alloy steel billets having rectangular cross sections and weighing up to about 4000 pounds. The billets are normally heated to between about l9502250 F. by a furnace temperature of about 2l002300 F. on a refractory hearth having walking beam members. Under these adverse conditions load bearing portions of the refractory require frequent repair. In prior art furnaces superficial or minor repairs of the refractory hearth members were made from inside the furnace with the walking beams in place. Major repairs required shutting down the furnace and dismantling the supports for the movable walking beam members so that they could be moved to a position where they would be accessible from outside the furnace chamber.

Another problem with prior art high temperature furnaces was that the means for discharging the workpieces had to be located outside the furnace closure or be water cooled. Up to the time of this invention no method had been devised whereby the alloy steel required for the discharge means could retain its structural strength without being water cooled if it were permanently located inside the furnace. Also no suitable transfer means had been developed for delivering a heavy billet without severe impact from the end of a walking beam conveyor to a laterally disposed conveyor located at a lower level.

SUMMARY OF INVENTION Generally speaking, the high temperature furnace of this invention comprises a refractory lined furnace chamber having a refractory hearth including refractory surfaced walking beam members for conveying workpieces stepwise through the furnace chamber. The top rails of the walking beam members are carried on rollers which ride on a vertically movable carriage. The carriage is supported upon a plurality of vertically disposed elongated leg members hingedly connected at intervals along the carriage. The leg members are tiltable in unison in either direction along the path of work travel. During normal operation of the furnace, each supporting leg member is caused to swing in unison with the others through an arc of less than and only in the upper half of a quadrant defined by vertical and horizontal lines extending through its lower axis. To facilitate the repairing of the refractory surfaces of the walking beam members, provisions are made for swinging the leg members beyond their normal limits to a substantially horizontal position without dismantling the carriage or disconnecting the supporting leg members. Located within the furnace at the discharge end of the walking beam conveyor is a pit containing a roller conveyor for receiving heat treated workpieces from the discharge end of the walking beam conveyor and conveying them out of the furnace through a relatively small opening in its side. The roller conveyor is at a lower elevation than the walking beam conveyor. By being in a pit at the end of the furnace chamber, the roller conveyor is isolated from the intense heat in the main body of the furnace. This permits the use of allow steel in the roller conveyor without the need for internal water cooling. A transfer means, which reciprocates in an inclined plane extending between the conveyors, lowers the workpieces without impact from the discharge end of the walking beam conveyor to the roller conveyor.

Accordingly, it is a general object of this invention to solve the aforementioned problems and provide a conveyor system for a high temperature furnace that is of simple and rugged construction and which reduces the amount of down time normally associated with such furnaces.

These objects and other objects and advantages and the manner of attaining them will be apparent from the following description made with reference to the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a side elevation view in section of the high temperature furnace and conveyor of this invention with parts broken away. 7

FIG. 2 is a sectional plan view taken along lines 22 of FIG. 1.

FIG. 3 is a sectional view taken along lines 3-3 of FIG. 1.

FIG. 4 is a sectional view taken along lines 4-4 of FIG. 1 showing the details of the reciprocable transfer means for lowering the workpieces from the walking beam conveyor to the roller conveyor.

Referring to the drawings, there is shown a high temperature billet heating furnace 10 having a generally rectangular heating chamber 12 with ceramic refractory surfaced roof 14, wall 16, and hearth 18 sections. The hearth section is formed of walking beam members 20 parallelly interspersed between fixed hearth members 22. These members extend horizontally from an entrance opening 24 at the charge end of the chamber to a pit section 26 located at its discharge end. The ingress and egress of atmosphere through the clearance gaps 27 between the movable and fixed hearth members is prevented by water seal troughs 28 carried upon a platform 30 along both sides of the bottom portion of each walking beam member. Seal flanges 32 depending from the sides of the adjoining fixed hearth members extend into the troughs below the liquid level and remain immersed as the walking beam members are raised and lowered during normal operation. A pair of rails 34 extend along the underside edges of each platform 30 and support the walking beams on a pluralityv of pairs of rollers 36 that are mounted by means of laterally disposed axle shafts 38. The ends of the shafts are contained in bearing members 39 anchored at fixed intervals on spaced apart parallel girders 40 forming a portion of the movable undercarriage 41. These rollers permit the walking beam members to be moved in horizontal directions independently of the movement of undercarriages 41. To maintain the walking beams in alignment with the undercarriages, interlocking guide means 42 located between the pairs of rollers 36 are provided.

Vertical movement is imparted to the walking beam members by undercarriages 41 which are hingedly mounted on a plurality of tiltable supports 44 normally disposed in a substantially vertical position. The working length of the supports is greater than the thickness of the fixed hearth members, and preferably is greater than one and one-half times such thickness. For example, in a furnace with fixed hearth members having a thickness of about 3 feet, the length of the supports measured between their pivotal axes was about feet. This allows the top of the walking beam members to be lowered to a position below the bottom of the fixed hearth members by tilting the supports 44 approximately 90. The purpose of this is to make the refractory surfaces of the walking beam members accessible for maintenance and replacement from outside the furnace without disconnecting the supports from the undercarriage. Another feature of this arrangement is that the components of the water seals are also readily accessible for inspection, cleaning, and repair. Preferably the supports comprise pairs of downwardly converging stiff leg members 46 having braces 48 connected across their upper sections. The upper extremities of each pair of leg members are affixed to one of the aforementioned axle shafts 38. Shaft members 53 are journaled in bearing members at the lower ends of the supports and have their ends fixedly mounted in retainer blocks 54 attached to stationary piers 56. The widths of the supports and piers relative to the open space between the pair of girders of their respective undercarriage are such that the girders will rest directly on the outside ends of the piers and the supports will be received between the girders when the undercarriage is lowered for the purpose of making the refractory surface of its walking beam member accessible for repair. The discharge end of the carriage is located so that it will clear a vertical wall section 58 extending downward from beneath the discharge end of the hearth to the furnace foundation floor 59.

The pit 26 contains a roller conveyor 62 which extends lengthwise across the hearth at the discharge end of the walking beam conveyor inside the furnace chamber. The width, depth, and length dimensions of the pit are such that it has the radiation characteristics of a deep slot. The ratio of its average width measured from the end of the hearth to the end wall of the furnace chamber and its average depth measured from the hearthline to the bottom of the pit may be between 0.2 and 2., but is preferably between 0.5 and l. The length to width ratio of the pit may be between 5. and 1. Accordingly, the radiation heat transfer from the furnace to the pit is reduced to about 25-75 percent of that which would occur between the furnace and a flat black body lying on the hearth and having the same average length and width dimensions as the pit. A black body as used herein is a body which absorbs all radiation incident upon it. The use of such a pit has two related advantages. lt conserves the heat generated within the furnace by reducing the radiation from the hot surfaces of the furnace to the cooler surfaces of the pit. Also, it protects the alloy steel of the roller conveyor which is located in the lower one-half to onethird of the pit. The portion of the end wall 64 of the furnace chamber below the hearthline forms a side wall 66 of the pit. To keep the width of the pit opening at a minimum, the refractory brickwork forming this side wall of the pit may be corbeled or otherwise extended inwardly towards the end of the hearth at the hearthline. The other side wall '68 extends downwardly on a sharp incline from the discharge end of the walking beam conveyor to the narrow bottom section of the pit where the roller conveyor is located.

The roller conveyor 62 comprises a plurality of V notched rollers 70 mounted on parallel shafts 72 located in the lower half of the pit. The conveyor is arranged to convey workpieces endwise out of the furnace through a small discharge opening in the side of the furnace and to do this in a direction which is lateral to the direction of travel through the furnace. The shafts may extend through the refractory side walls of the pit and have their ends mounted in bearings 74 located outside the furnace chamber. Hollow shafts may be used in conjunction with a water cooling means 76 for cooling the alloy steel rollers and shafts.

A reciprocable transfer means 80 is provided to receive workpieces from the end of the walking beam conveyor and lower them without impact onto the roller conveyor. It comprises pairs of longitudinally reciprocable arms 82 lying in an inclined plane extending from adjacent the end of the walking beam conveyor through the centerline of the roller conveyor. The arms of each pair are parallel to each other and spaced apart sufficiently to permit the ends of their respective walking beam members to pass between them without contact. The lower ends of the arms ex tend between the rollers of the roller conveyor through seal members 84 in the bottom of the pit and are connected to a rigid reciprocable frame 86. Horizontally disposed

rotatable shafts

88 and 90 are anchored to the top and bottom sections of the frame by bearing members 92 having axial thrust preventing means. Flanged wheels 94 are fixedly located adjacent the ends of the shafts and are confined between rigidly mounted

channel members

96 and 98 to prevent tilting of the frame, particularly as it is being reciprocated in the straight channels. To insure that both sides of the frame travel in unison even though the workpiece load is not distributed evenly between all the transfer arms, spur gears 100 are affixed to the ends of the top shaft 88. They engage rack gear sections 102 affixed to the channel members. Accordingly, any movement of one side of the frame back or forth in its channel will cause and equal movement of the other side of the frame. Preferably, a single hydrculic cylinder and piston means 104 or other reciprocating device is connected to the bottom of the frame along its vertical centerline to raise and lower the transfer frame and arms. The tip of the arms may be provided with a 90 V notched cap 106 designed to rotate a square billet 45 as it is removed from the walking beam conveyor, and then deliver it in this on-edge position to the roller conveyor. Such a cap also helps in the alignment and holding of a round billet.

A reciprocating means 110, such as a hydraulic cylinder and piston, is connected to the undercarriage at the charge end of the furnace. The length of the stroke is set so that the normal angular traverse of the carriage supports is preferably less than 20 and is limited to that portion of the quadrant located between 8 and 36 from a vertical line extending through the lower axis of any one of the supports. Preferably it is limited to that portion lying between 10 and 30. The vertical component of movement of the carriage is about 4 inches for supports having a length of about 5 feet between their pivotal axes. A similar reciprocating means 112 is connected to the walking beam members and is capable of moving them in horizontaldirections independently of the movement of the carriage. This means 1 12 may comprise a separate unit for each walking beam member and have a releasable connector 114 joining them together so that they may be operated in unison or independently of each other. In a furnace for processing billets up to 12 inches in width or diameter the horizontal travel stroke was set for about 9 inches. To lower the walking beam members and the undercarriages below the fixed hearth members, their respective reciprocating means may be disconnected and eased downwardly until the girders of the undercarriages rest upon the piers 56.

While the principles of this invention are described with reference to a preferred embodiment illustrated in the drawings, it is to be understood that the description is made by way of example and that the scope of the invention is to be limited only as defined in the appended claims.

We claim:

1. A high temperature billet reheating furnace comprising: a heating chamber defined by roof, wall, and hearth members having refractory surfaces suitable for furnace operating temperatures of l950 F. and above, said hearth members including at least one horizontally disposed movable hearth member interspersed between fixed hearth members, a horizontally disposed carriage mounted beneath said movable hearth member on normally vertically disposed tiltable stiffleg members having their upper ends hingedly secured at fixed locations on said carriage and their lower ends hingedly attached to stationary piers, roller means for mounting said movable hearth member on said carriage, means for horizontally reciprocating said movable hearth member with respect to said carriage, means for independently reciprocating said carriage to tilt and leg members through angles of less than 20 within arc segments extending between 8 and 36 from vertical lines passing through the lower axes of said leg members to impart vertical movement to said carriage.

2. A furnace according to claim 1 wherein said fixed hearth members have an average vertical thickness which is relative to the length of said carriage leg members and the length of said leg members as measured between their upper and lower axes is at least 1.5 times said thickness.

3. A high temperature billet reheating furnace comprising an elongated heating chamber defined by roof, wall, and hearth members having refractory surfaces suitable for furnace operating temperatures of l900 F. and above, said hearth members including at least one horizontally disposed movable hearth member interspersed between horizontally disposed fixed hearth members forming a walking beam type conveyor for transporting laterally disposed workpieces through said furnace chamber, a horizontally disposed carriage mounted beneath said movable hearth member on a plurality of normally vertically disposed stiff leg members having their upper ends hingedly secured at fixed locations to said carriage and their lower ends hingedly secured to stationary piers, rollers means for mounting said movable hearth member on said carriage, means for horizontally reciprocating said movable hearth member with respect to said carriage, means for independently reciprocating said carriage to tilt said leg members in unison from substantially vertical positions to impart vertical movement to said movable hearth member, an abruptly offset pit section extending below the hearthline at the discharge end of said chamber, a second conveyor mounted in the bottom portion of said pit section for conveying workpieces endwise through a discharge door opening in the side of said chamber and an axially reciprocating transfer means for receiving workpieces from the end of said walking beam conveyor and lowering them onto said second conveyor without impact.

4. A furnace according to claim 3 wherein said fixed hearth members have an average vertical thickness which is relative to the length of said carriage leg members and the length of said leg members as measured between their upper and lower axes is at least 1.5 times said thickness.

5. A furnace according to claim 3 wherein said pit has an average depth to average width ratio between 0.2 and 2. with the width being measured along an extension of the hearthline from the discharge end of the walking beam conveyor to the opposite side wall of the pit and its average depth being measured from the hearthline extension to the bottom of the pit.

6. A furnace according to claim 3 wherein said second conveyor is a roller conveyor made substantially of heat resistant alloy steel.

Claims

1. A high temperature billet reheating furnace comprising: a heating chamber defined by roof, wall, and hearth members having refractory surfaces suitable for furnace operating temperatures of 1950* F. and above, said hearth members including at least one horizontally disposed movable hearth member interspersed between fixed hearth members, a horizontally disposed carriage mounted beneath said movable hearth member on normally vertically disposed tiltable stiff leg members having their upper ends hingedly secured at fixed locations on said carriage and their lower ends hingedly attached to stationary piers, roller means for mounting said movable hearth member on said carriage, means for horizontally reciprocating said movable hearth member with respect to said carriage, means for independently reciprocating said carriage to tilt and leg members through angles of less than 20* within arc segments extending between 8 and 36* from vertical lines passing through the lower axes of said leg members to impart vertical movement to said carriage.

3. A high temperature billet reheating furnace comprising an elongated heating chamber defined by roof, wall, and hearth members having refractory surfaces suitable for furnace operating temperatures of 1900* F. and above, said hearth members including at least one horizontally disposed movable hearth member interspersed between horizontally disposed fixed hearth members forming a walking beam type conveyor for transporting laterally disposed workpieces through said furnace chamber, a horizontally disposed carriage mounted beneath said movable hearth member on a plurality of normally vertically disposed stiff leg members having their upper ends hingedly secured at fixed locations to said carriage and their lower ends hingedly secured to stationary piers, rollers means for mounting said movable hearth member on said carriage, means for horizontally reciprocating said movable hearth member with respect to said carriage, means for independently reciprocating said carriage to tilt said leg members in unison from substantially vertical positions to impart vertical movement to said movable hearth member, an abruptly offset pit section extending below the hearthline at the discharge end of said chamber, a second conveyor mounted in the bottom portion of said pit section for conveying workpieces endwise through a discharge door opening in the side of said chamber and an axially reciprocating transfer means for receiving workpieces from the end of said walking beam conveyor and lowering them onto said second conveyor without impact.