US3144245A

US3144245A - Heat treating furnaces

Info

Publication number: US3144245A
Application number: US143080A
Authority: US
Inventors: Joseph E Martin
Original assignee: Individual
Current assignee: Individual
Priority date: 1961-10-05
Filing date: 1961-10-05
Publication date: 1964-08-11
Anticipated expiration: 1981-08-11

Description

Aug. l1, 1964 J. E. MARTIN HEAT TREATING FuRNAcEs 4 Sheets-Sheet l Filed 0G11. 5, 1961 EN Tof?- ron/ver Aug. 11, 1964 J. l;` MARTIN HEAT TREATING FuRNA-cEs 4 Sheets-Sheet 2 Filed OGt. 5, 1961 NVEIVTOI? ATTORNEY FIG.

Aug. 11, 1964 J, E. MARTIN HEAT TREATING FURNACES 4 Sheets-Sheet 3 Filed Oct. 5, 1961 A T TOHNE'Y Aug. 11, 1964 J. E. MARTIN HEAT TREATING FURNACES 4 Sheets-Sheet 4 Filed Oct. 5, 1961 "MIMI" ATTRNEY United States Patent O 3,144,245 HEAT TREATING FURNACES Joseph E. Martin, 19255 John R, Detroit, Mich. Fitted Get, 5, 1961, Ser. No. 143,080 8 Claims. (Cl. 26S- 34) The present invention relates to improvements in retort furnaces, and more particularly to a heat treating furnace in which the retort is oscillated about its longitudinal axis to tumble the workpieces, and is reciprocated longitudinally to convey the workpieces through the furnace retort.

One object is to provide a retort furnace in which the retort is reciprocated to effect feeding of the workpieces and is provided with independent means for oscillating the retort about its axis, whereby the workpieces may be subjected to various periods of tumbling and different rates of feed while in the furnace.

Another object is to provide a heat treating furnace of the rotary retort type having separate and independent feed and tumbling means and thus insure proper heat treating of various workpieces by carburizing, carbonitriding and clean hardening of small workpieces and reduced section.

Another object is to provide a heat treating furnace in which the retort is mounted on a reciprocating frame and supported within the furnace casing in such a manner that the retort is reciprocated and oscillated simultaneously relative to the casing so that the workpieces will be subjected to the same degree of heat and exposed to the carburizing atmosphere throughout their entire surface with the result that the depth of hardening will be uniform through the different sections of the workpiece.

Another object is to provide a heat treating furnace of the retort type having a discharge gate which is arranged to normally retard discharge of the workpieces from the retort to the quenching tank and which may be displaced 180 to cause the workpieces to be discharged upon continued operation of the reciprocating shuffle mechanism.

Another object is to provide a retort furnace in which sealing members are yieldingly urged into engagement with the ends of the retort to provide an effective end seal and providing inlet and discharge members coupled with the retort by a butt sealing joint so that the members move longitudinally with the retort, but remain xed against rotation during oscillation or rotary to and fr movement of the retort.

Another object is to provide a continuous rotary type retort furnace which is capable of being adjusted for batch operation wherein the furnace is loaded and subsequently discharged simultaneously in batch fashion, or which can be operated continuously and can be fed by a metering type feeder with the workpieces discharged into a quenching tank where they are removed by an endless buckettype conveyor.

Another object is to provide a retort furnace for heat treating workpieces in which the combined reciprocating and oscillating movement imparted to the retort can be regulated to increase or decrease the tumbling rate as well as the time required for the workpieces to travel through the retort from the inlet end to the discharge of the retort.

Another object is to provide a retort furnace for heat treating metal workpieces so that the depth of hardening will be uniform throughout all sections of the workpiece, and in which the ends of the retort are sealed against the entrance of combustion products by sealing members formed of wear resisting metal arranged in abutting relation with the retort ends and yieldingly urged into sealing contact therewith during operation of the furnace.

Another object is to provide a retort furnace in which the retort is reciprocated and oscillated simultaneously t0 lCe effect a feeding and tumbling action with independent means for reciprocating the retort separate from the means for oscillating the same about its axis, whereby the furnace can be regulated to a fine degree in accordance with different techniques of heat treating various workpieces.

Another object is to provide a heat treating furnace in which the retort is rotatably supported on a reciproeating frame having guide rollers engaging trackways on a fixed frame so that the retort may be.` oscillated and reciprocated in the furnace and to provide effective contactually engaging sealing members between the retort and housing at the end portions thereof.

Another object is to provide a variable drive unit for oscillating the retort at dierent frequencies and to provide a separate power drive unit for reciprocating the retort which is capable of being adjusted to vary the reciprocating rate of the retort independently of the Variable oscillaing drive unit.

Another object is to provide a retort furnace for heat treating metallic workpieces with means for feeding a predetermined number of workpieces per minute and thus continuously supply the retort with a uniform number of workpieces which are traveled and conveyed through the furnace at a uniform rate and are tumbled during their passage through the furnace to insure uniform hardening depths throughout the entire workpiece area.

Another object is to provide a retort heat treating furnace which can be used as a batch-type furnace, or which can be operated continuously by feeding the workpieces mechanically by means of a feeding device including a conveyor and rotary dispensing measuring device.

Other objects and advantages of the invention will become apparent during the course of the following description of the accompanying drawings, wherein:

FIGURE 1 is a side elevational view of the retort furnace showing the manner in which the retort is mounted for longitudinal movement within the furnace structure.

FIGURES 2 and 2a are longitudinal cross-sectional yviews taken on line 2-2 of FIGURE l and looking in the direction of the arrows to illustrate various structural details.

FIGURE 3 is a vertical cross-sectional view taken on line 3 3 of FIGURE 1 and looking in the direction of the discharge end of the furnace and FIGURE 4 is an end elevational view looking in the direction of the discharge end of the retort furnace.

In the drawings, and more in detail, there is shown a retort-type heat treating furnace structure including a furnace housing generally designated 5 and a cylindrical retort generally designated 6 mounted within the furnace housing and supported by a reciprocating frame structure generally designated 7.

The retort housing S is supported on a frame structure including spaced runner-type base bars 8 to the ends of which are Welded or otherwise secured upright frame bars 9 at each end of the base bars 8. Intermediate the ends of the frame bars 9 there is provided reinforcing angle bars 10 which are welded or otherwise secured in place to form frame bars extending parallel with the base bars 8. Transverse frame bars 11 have their ends welded or otherwise secured to the longitudinal frame bars 1t) and the extreme upper ends of the upright frame bars 9 are connected by longitudinal frame bars 12 likewise welded or similarly secured in place.

The retort furnace housing 5 includes a pair of

metallic shell sections

13 and 14 of semi-circular section with the bottom shell 14 supported by the spaced apart transverse bars 11 and secured to the longitudinal frame bar 12 by welding or the like. The upperl section 13 is provided on its longitudinal edges with angle bars which are secured to one of the flanges of the angle bar 12 by suitable threaded fasteners or by welding. The

shell sections

13 and 14 are provided with refractory

brick liner sections

16 and 17 of semi-circular section and are supported by interposed plate strips 18. The upper section 13 is provided with a burner housing 20 having a portion 22 projecting into openings 23 in the housing tirebrick liner 17. As shown in FIGURE 1 the burner housings are arranged in spaced apart relation from one end of the housing 5 to the other end, and each burner housing 20 is provided With a fuel supply pipe 24 for feeding a liquid or gaseous fuel to the burner jet cone 26. The burner housings 20 are secured in place by threaded fasteners 27 which extend into correspondingly threaded openings in the upper metallic shell 13 of the housing. The burner supply pipes 24 are supported in an opening formed in a web 28 in the housing 20 and extend in a direction tangential to the circumference of the furnace housing 5.

Also secured to the upper section 13 of the furnace housing is a pair of spaced lugs 30 having openings 31 for receiving a hoist sling to facilitate installation of the furnace by a crane or other hoist, and to facilitate removal of the upper half of the housing for repairs or replacement of the lining or retort.

Also supported by the frame structure including the uprights 9 is a trackway 32 of angle section and said trackway is supported by tubular structural bars 33 (FIG. 4) which have one end welded or otherwise secured to each upright 9 while the inner ends are Welded or similarly secured to the webs of the channel bars 32 forming the trackway. As shown in FIGURE 3 the channel bars 32 are arranged in opposed relation and the ends thereof project beyond the

end walls

34 and 35 of the furnace housing 5.

Firebrick structures

36 and 37 are supported by the

end walls

34 and 35 similar to the

sections

16 and 17.

The ends of the channel bars forming the trackway 32 at one end of the retort furnace are supported on suitable frame bars 40 which are secured thereto by angle plates 41 which are welded or otherwise secured in place to form braces and additionally support the opposed channel members 32.

The carriage for the cylindrical retort is formed by a pair of opposed channel bars 43 (FIG. 3)which are substantially equal in length to the channel bars 32 and are connected together throughout their length by spaced transverse channel bars 44 secured in place as by welding at various locations. Rotatably mounted on both sides 0f the carriage and supported by the channel bars 43 is a series of anged wheels 45 which are mounted on short axle shafts 47. The wheels are received in the trackway formed by the opposed channel members 32. One end of the carriage is provided with a base plate 46 and secured to the ends of the opposed channel members 43 at the opposite end as by Welding is a pair of triangular shaped plates 48 to which is attached upright carriage members 49. The plate 46 is welded to the flanges of the opposed channel members 43 and is similarly provided with a pair of spaced channel members 50 connected at their upper ends by a plate 51 suitably secured in place as by welding or threaded fasteners. Carried by the carriage frame formed by the opposed channel members 43 is an additional pair of uprights 52 arranged in spaced relation from the uprights 49 and said uprights are reinforced by triangular plates 53 likewise welded in place.

Secured* to the other end of the carriage frame is a pair of upright frame members 55 for supporting transverse channel members 56, and mounted on said channel members is a pair of spaced grooved rollers 57 supported in journal housings 58 secured to the transverse channel members 56. All of the frame parts of the carriage structure are either welded together or secured by threaded fasteners.

The upright

carriage frame members

49 and 52 are arranged in spaced apart sets with the pair of uprights 49 connected by an angle bar 60 and the uprights 52 connected by a similar angle bar 61. Spaced journal housings 63 are mounted on the angle bar 60 in spaced apart relation and similar journal housings 64 are supported on the angle bar 61 with their axis corresponding to that of the journal housings 63.

Supported by the journal housings 63 and 64 is a pair of rotary shafts 66 of tubular section and suitable thrust washers 68 are provided on the shafts to prevent endwise movement. The shafts 66 extend through the end wall plate 35 of the furnace housing and project a considerable distance inwardly as shown in FIGURE 1. The inner ends of the shafts 66 are provided with rollers 70 secured in place by washers 71.

The retort generally designated 6 includes a cylindrical shell 72 having a reduced end portion 73 supported in a bearing structure which includes a collar '75 rigidly attached to the reduced end 73 of the retort which is supported by the spaced grooved rollers 57. The other end of the retort shell 72 is partially closed by a gate or baflle wall 78 forming an opening '79 (FIG. 3). rI'he inner end of the retort shell is rotatably supported on the rollers 70 mounted on the inner ends of the shaft 66.

Formed internally and extending longitudinally of the retort shell 72 is a rib 3@ adapted to engage the workpieces during oscillation of the retort shell about its axis to thereby tumble the workpieces and present different surfaces to the carburizing atmosphere.

Mounted on the feed or reduced end 73 of the retort shell 72 is the collar 8i? of a sprocket wheel 81 which is adapted to be driven by an electric motor 82 connected to an oscillating drive unit S3 of the type shown in United States Patent 2,887,887, issued to lennings, May 26, 1959. The oscillating drive unit is provided with a control lever 84 which may be manually operated to drive the output shaft and sprocket wheel S6 through an oscillatory arc of 180. The sprocket wheel 86 is connected to the sprocket Wheel 81 by means of a sprocket chain 37 so that when the manual control lever 84 is in one of its positions of adjustment the retort shell 72 will be oscillated to and fro about its axis on each side of a vertical plane through the axis. In another position or the manual control lever 84 the motor 82 which may be connected to a suitable source of electrical energy will rotate the retort shell 72 continuously about its axis. This arrangement is necessary to rotate the retort shell 72 to a position shown in FIGURE 3 so that when the furnace is used as at for instance a batch type, the gate 78 will be displaced from a normally lower position or one reversed from that shown in FIGURE 3 and permit the opening '79 to allow the workpieces to pass therethrough when the frame 7 is reciprocated to discharge the workpieces.

The frame structure 7 and the retort shell are reciprocated by means of a mechanical motion device including drive linkage driven by an electric motor 38. The armature shaft Iof the electric motor is provided with a suitable sprocket wheel over which is trained a sprocket chain 92 which drives a similar sprocket wheel afxed to one end of the shaft 94 journaled in suitable openings in the mechanical motion housing 97. A cam (not shown) is secured to the shaft 94 and engages one end of a reciprocating rod 96 slidably mounted in the bearing 97 The other end of the reciprocating rod 96 is pivoted as at 98 to a lever 10i). The lever 164) is pivoted as at 161 to a bracket 74 attached to the frame structure and the upper end of the lever is connected to a link 101' by means of a pivot pin 102 and the other end of the link is connected to one of the cross members 44 of the reciprocating frame by means of a pivot pin 105.

The electric motor 88 is of the variable speed type similar to the motor 82 and is connected to a suitable source of electrical energy controlled by a rheostat in circuit with the motor to permit the speed thereof to be regulated and thus increase or decrease the reciprocating rate of the carriage 7. The stroke of the carriage and shell can be regulated by adjusting the pivot pin 101 in suitable openings therein (not shown).

Supported by the plate 51 is an L-shaped tubular fitting 106 having an enlarged end portion 107 adapted to receive the feed end or reduced portion 73 of the retort shell. The enlarged end 107 is formed of a suitable heat and Wear resisting metal alloy so that the portion in abutting relation with the reduced end 73 of the retort shell will not be excessively Worn. An annular flange 103 is fitted on the L-shaped tubular member 106 and secured in place by Welding in any approved fashion.

Guide rods having threaded end portions 109 extend through suitable openings in the flanged plate 108 and the guide rods are threaded at one end as at 110 to receive retaining nuts 111 arranged on opposite sides of the plate 51. Abutment members 112 are threaded on the threaded portion of the guide rods and coil springs 113 are received on the rods with one end engaging the abutment member 112 and the other end engaging the flange plate 108. The L-shaped tubular fitting 106 is shaped to provide a hopper 115 into which the workpieces are deposited and eventually fed to the retort shell 72 through the reduced tubular portion 73.

The other end of the retort shell 72 is engaged by a drum-shaped housing 116 which is formed with annular wall 117 formed to provide a discharge pipe 118 having a discharge opening 119. The cylindrical wall 117 has its open end enlarged as at 119 to receive the end of the shell 72 and abut the cylindrical portion 117. The drumshaped housing 115 is formed with a plurality of circumferentially spaced bearing bosses 120 to receive the ends of guide rods 126 which extend through suitable aligned openings in the firebrick wall 37 and the end wall furnace plate 35. The outer ends of the guide rods 126 extend through openings in a plate 130 secured to one set of spaced apart uprights 52 on the reciprocating frame. The guide rods 120 have their threaded end portions 132 projecting through a similar plate 133 supported by the other set of uprights 49 on the reciprocating frame member. The guide rods 120 are retained against displacement by nuts 135 received on the threaded ends 132 of the rods. Coil springs 136 encircle the guide rods and have one of their ends in abutting relation with the plate 133, while their other ends are engaged by an abutment washer 137 held in place by suitable threaded fasteners or nuts 138. Thus, it will be seen, that reciprocation of the frame 7 will also reciprocate the retort shell 6, and the retort shell is held against displacement on the carriage by the annular member 7 5 being engaged by the set of grooved rollers 57 supported by the bearing housings 58.

Secured to the frame structure in an approved fashion is a water feed pipe 140 to supply coolant to the shafts 66. The Water is fed to the shafts 66 which passes toward the inner end thereof and then returns to the outer end of the shafts 66 where it is discharged by gravity.

The discharge fitting or drum 116 has its discharge pipe 118 extending through an elongated opening 150 in the lower furnace housing section 14 and terminates in a flange 151. Secured to the flange is a discharge pipe 152 which is also hanged as at 153 to mate with the flange 151 and be secured thereto by Welding or the like. The discharge pipe 152 extends downwardly between spaced pairs of transverse carriage frame members 44 and into a quench tank 155 disposed beneath the furnace structure. A discharge conveyor 156 may be provided for removing the workpieces or articles after the quenching operation.

Similarly, the conveyor 157 of the boot-type may be provided for feeding the workpieces from a hopper 158 to a rotary metering device 159 which has its hopper 160 disposed to receive the workpieces from the discharge end of the boot conveyor 157 and discharge the same through the outlet 161 to the hopper 115 of the L-shaped tting 106.

When the furnace is used in a cyclic fashion the workpieces are fed in sequence to the hopper and pass through the retort shell 72 upon energization of the motors S2 and 88 to simultaneously reciprocate and oscillate the retort shell. When the workpieces reach the opposite end adjacent the discharge drum 116 they are permitted to fall through the openings formed below the gate 78 and pass through the discharge tube 113 and into the quenching tank Where they are continuously removed by the endless conveyor 156, it being understood that the retort shell 72 is angularly displaced by manipulating the control lever Sd to position the shell and gate 78 as shown in FIGURE 3 before the control 84 is operated to connect the oscillating mechanism with the sprocket 86 and impart oscillatory movement to the retort as it is being reciprocated by the cam drive linkage 815-93. When the furnace is operated as a batch-type the workpieces may be manually fed to the hopper 115 and conveyed through the retort shell by the reciprocating shuffle linkage 93 while it is being oscillated by the oscillating drive unit 83.

During the batch cycle, the control lever S41- is manipulated to rotate the retort 72 to a position of angular displacement approximately from that shown in FIG- URE 3 so that the gate 78 Will be in its lowermost position. Then by reciprocating the frame by the electric motor 3S and operating the control S4 to effect an oscillating drive of the sprocket 86 the shell 72 will be oscillated during reciprocation thereof and the workpieces will be fed through the retort shell 72 and will be retained by the gate 78. After the cycle is completed the shell 72 may be angularly displaced 180 so that the gate 7h is now in the position shown in FIGURE 3. Upon continued reciprocation of the frame 7 the workpieces will be discharged from the shell 72 and will pass through the discharge duct 152 to the quenching tank 155. In order to accomplish the discharge cycle above, the motor S8 is energized while the motor 82 is arrested so that the retort shell 72 Will be reciprocated in a manner similar to a shuflie hearth furnace.

It will thus be seen that during operation of the furnace for heat treating metallic workpieces that the retort shell 72 can be oscillated at a predetermined amplitude by varying the speed of the motor 82, and similarly frequency rate of reciprocation of the frame 7 can be controlled by varying the current supply to the motor 88 and adjustin g the speed of the motor.

In some metallic workpieces it is desirable to tumble the same while passing through the retort at a rapid rate while feeding them to the discharge end at a relatively slow speed, and it will be seen that by regulating the speed of the

motors

82 and 88 that the tumbling and feed of workpieces traveling through the retort shell 72 will be nicely controlled and effect uniform heat treating of various workpieces which are of uneven section and irregular shape.

The heat treating furnace embodies a retort shell which projects into the furnace housing 5 through an opening in one of the end Walls and is supported adjacent the other end wall by the rollers 70. This structure prevents the escape of gases and is highly efficient. In addition, the retort is sealed at both ends against the intrusion of air or combustion gases by the

members

106 and 117 which contactually engage and seal the ends of the retort shell. The only openings necessary in the furnace housing are indicated at 74 and the openings for accommodating the supporting rods 120 and the roller supporting shafts 66. Thus, the shell is effectively sealed and gases may escape from the furnace housing through a suitable stack (not shown) when the burners are in operation Also, it is pointed out that the retort shell may be rotated in one direction by manipulating the control 4 and simultaneously the shell can be reciprocated when both

electric motors

82 and 88 are energized. It is necessary to employ a plurality of yieldingly mounted rods 120 for supporting the cylindrical head 117 so that 7 the same will not rotate with the retort shell, and since the Weight of the shell is supported by the rollers 7?, the rods 120 are not placed under a stress or strain.

What I claim is:

1. In a heat treating furnace for metal Workpieces, a stationary furnace housing, a source of heat in said housing, a retort having a heat treating chamber extending through an end Wall of said housing, means for reciprocating said retort longitudinally Within said housing, and independent means for oscillating said retort to and fro during reciprocation thereof.

2. In a heat treating furnace for metal Workpieces, a stationary furnace housing, a source of heat in said housing, a retort having a heat treating chamber movably mounted Within said housing, means for reciprocating said retort, means for oscillating said retort independently of the first named means, and baiiie means at the end of said retort to retard the iiow of workpieces moved through said retort by reciprocating shuie action.

3. In a heat treating furnace for metal Workpieces, a stationary furnace housing, a reciprocating frame mounted adjacent said housing, a retort extending into said housing and supported adjacent its ends by said frame longitudinally of the housing axis, means for reciprocating said frame and independent means for osciliating said retort Within said housing during the reciprocation of said retort to control the feeding and tumbling rate of the Workpieces through said retort.

4, In a heat treating furnace for metal Workpieces, a stationary furnace housing having end walls, a reciprocating frame mounted adjacent said housing, a retort rotatably supported at its ends by said frame and having one end extending into said housing and the other end extending through an opening in one of said end walls, means for feeding Workpieces to the external end of said retort, means for discharging worlrpieces from the other end of said retort, means for reciprocating said frame to reciprocate said retort Within said housing and independent means for oscillating said retort to and fro about its longitudinal axis duringreciprocation of said retort along the same axis.

5. In a heat treating furnace for metal Workpieces, a cylindrical housing having end Walls, a reciprocating frame mounted adjacent said housing, a retort mounted in said housing with one end extending through one of said end Walls, means on said reciprocating frame for supporting said retort to reciprocate with said frame, independent means for oscillating said retort about its longitudinal axis, means for feeding Workpieces to one end of said retort, means for retarding Workpieces as they travel toward the opposite end of said retort and discharge means extending through said housing for said Work` pieces.

6. In a heat treating furnace, an elongated furnace housing having end Walls, a cylindrical retort mounted Cil.

in said housing and extending through one of the end Wails thereof providing internal and external portions, a hopper fitting yieldingly engaging the external end of said retort, a hopper attached to said fitting, means for feeding Workpieces to said hopper, a closure cap having a discharge opening frictionally engaging the internal end of said retort, a discharge pipe extending through said housing and Connected to said discharge port, means for reciprocating said retort to feed Workpieces from the external end to the internal end, and independent means for osciliating said retort and tumble said Workpieces during reciprocation of said retort.

7. In a heat treating furnace for metallic Workpieces, a cylindrical furnace housing having end Walls, an elongated cylindrical retort mounted in said housing with one end extending through an end wall in said housing providing internal and external end portions, reciprocating support means for the internal and external ends of said retort, rollers on said support means for rotatably supporting said retort, a charging cap yieldingly engaging the external end of said retort, means for feeding workpieces to said cap, a discharge cap yieldingly engaging the internal end of said retort having a discharge opening, a discharge pipe extending through said furnace housing and connecting said opening, means for reciprocating said retort, and independent means for osciliating said retort about its longitudinal axis.

8. In a heat treating furnace for metal Workpieces, a cylindrical furnace housing, a series of heating units projecting into said housing and extending tangentially, end walls for said housing, a reciprocating frame adjacent said housing, a cylindrical retort mounted in said housing with one end projecting through an end Wall thereof, support means at each end of said frame for said retort, a hopper cap yieldingly engaging the external end of said retort, means for feeding workpieces to said hopper cap, a discharge cap yieldingly engaging the internal end of said retort and having a discharge opening, a discharge pipe extending through said housing and connected to said discharge opening, a bailie Wall adjacent said discharge cap to retard the discharge of Workpieces, means for reciproeating said frame and retort in a direction longitudinally of the retort axis, and independent means for oscillating said retort about its longitudinal axis whereby the feeding rate and tumbling rate of the Workpieces can be separately varied.

References Cited in the file of this patent UNITED STATES PATENTS 1,551,197 Krebs Aug. 25, 1925 1,671,546 Romph May 29, 1928 1,686,565 Knapp Oct. 9, 1928 1,797,125 Braekelsberg Mar. 15, 1931 1,965,881 Clark et al. July 10, 1934