US2898101A - Heat treating furnace having double-ended chain conveyor - Google Patents

Description

c. T. HNNM ET Al. 2,898,101

Aug. 4, 1959 HEAT TREATINGV'FURNACE HAVING DOUBLE-ENDED CHAIN CONVEYOR Filed Dec. 5, 1956 2 Sheets-Sheet 1 INVENTORS. C. 7.- HHN/VUM Aug- 4, 1959 c. T. HANNuM ErAL 2,898,101

HEA'L` TREATING FURNACE HAVING DOUBLE-ENDED CHAIN coNvEYoR Filed Deo. 5. A'195e 2 sheets-sheet 2 INVENTORS F@ 5 c///vA/z//v BY H. M THR/4MM @AA/@Af assignors to Surface Combustion Corporation, Toledo, Ohio, a corporation of Ohio Application December 5, 1956, Serial No. 626,488 6 claims. (c1. 26a-4) This invention pertains to a conveyor `for heat-treating vfurnaces and more particularly to a chain conveyor for the same with `means associated therewith for pushing Vand pulling the work to be heat-treated.

The atmospheric batch-type furnace with alvestibule outside the charge-discharge opening and which contains a quench tank below the opening is extremely popular l;in the heat-treating eld. t Thisl is principallyV due to` the fact that this type of furnace is compact and can be used with a variety of rheat-treating processes including carburizing, nitriding, hardening, carbon restoration, and :annealing Such furnaces, however, present a problemconcerning 'cadequate means for charging and: discharging the work `since the work must be charged and discharged through xdzhe-V same openingand the area over the quench tank Ymust be kept` unobstructed for vertical movement of the quench-elevator; A commonly used apparatus consists ofone or Lmore retractable hooked rods extended through -tfhe"vestibu'le opening to grasp thefwork tray and-which are 'usually adequate for manual operation but' are not #readily adaptable 'for automatic operation. Also, the -rodslrequire that'a considerable area of clear'space be @maintained in front of the furnace so that the retraction of the rods will be unobstructed. Other types of chargerfdischarge apparatus have also been tried Y with-*only imoderate'degrees of success.

` lAccordingly, a new Vand novel :conveyor hasl been de- L"veloped that-operates from the front and/or rear end Lof the furnace automatically. lThenew conveyor has :automatic releasable means for engaging and 'disengaging fthe trays carrying the work and further does'not obstruct the operation of the quench elevator. i

For further 'consideration of the invention, its ad l"vanta'ges" and novelty, refer to the following portion of the specification, the appended claims, and the accompanying'drawing. t

` In thedr'awing: v A

Figure l is a cross-sectional view-on line 1-1 of Figure 2 of apparatus `embodying the invention,

"I Figure 2 a cross-`sectonal view onV line-2 2 of Figurefl,` Figure 3 is an tion: of Figure 2, and

Figures 4 and 5 are detailed views ofother portions of the apparatus of Figures 1 and 2.

. Referring to the drawing, the furnace 11 comprises a heating chamber 12 and vestibule chamber 13, the former being formed by refractory wall `14 and the latter by metal wall 15. Chamber 12 is heated by radiant tubes 16 placed on both sides of the roller conveyor 17 which consists of two lines of rollers. 18 supported in holders 20 on platform 21. A trough is formedbetween the holders by platform 21 Y and members 23 in which chain 22 and cart 36 rests. The chain is preventedl from buckling downwardly by platform v21 and upwardly by ;members 23- j j v j Chain 22 comprises wheels 24,"pairs of which are conenlarged, `cross-sectional view'of a por? -ofl chain 22' is pushed upwardly by a cam l62 located at axles in a linear manner.

2,898,101 Patented ug. 4, 1959 2 nected by 'axles 25; links 26 and 27 interconnect the sprocket 28 driven ,through motor 29 and reducer 30 outside the rear end of chamber 12.' The outer'end Aof the chain is directed by guides 31 into an elongated receptacle 32, forming volume 33,-1ocated beneath the chamber 12. Receptacle 32 communicates with a housing 34 forming chamber 35 encompassing'sprocket'iZS. The entire chain is thus enclosed in a gas-tight space comprising chamber 112, volume 35, and volume 33, and an atmosphere gas maythu's'be maintained in chamber 12 with a minimum of leakage.

Apush-pull cart 36 is attached to the rupper end of chains 22 through link 39 and comprises a cast body 37 to which three pairs of wheels 38 are' attached. The body has a projection 40 which is of'suticient height to ucontact a tray on rollers 18. lThe body also has a hori- -zontally extending arm 41 to which a rotatable dog 42 jisattached by pivot 43. The lower end of dog 42V is heavier so as to maintain the opposite Vend in an upward,

-engageable position with a projection ofthe tray except 'when the lower end is moved upwardly by cam 44. In- "stead of a projection, a recess or hole in the tray may be vprovided into which the upper end of the dog projects.

Cam 44 is located on Vthe rearward end of a platform v51 which is located below a second platform 52, both containing rollers 18 and being interconnected by bars 5,3,.3. The unit forms an elevator which is vertically moved by. a hydraulicI or 'pnuernatic piston 54 and directed by guides 55 and'56 into quench tank 57.

From this elevator, work may be removed through vestibule vdoor 58 by means of manually operated hooked rods or by a second chain similar to the one at the rearward end ofthe furnace. The @chain 22' is identical to chain 22 except Vbeing somewhat shorter in length. It is driven by another sprocket 28 and rides in a similar trough. The cart 36 and its components are likewise similar. The chain is guided here, around the sprocket, by a fabricated metal sheet 60 and has a receptacle 61 which need not be gas tight. The lower end of dog 42 the forward end of upper platform 52.

In operation, ay tray of` work to be heat-treated is placed on charge. table 63 and chain 22 4is moved forwardly. Projection 40 of the chain thencontacts the forward edge of the tray until it reaches the end of its forward vtravel near lthe forward end. of platform 52 '1 which is lowered into alignment with the roller's'lS on fthe charge table and in' the heating chamber.

At this point, the chain is retracted, leaving the tray'on platform 52.` The upper end of. dog42 is depressed by cam 62 so that the dog cannot catch on the tray and withdraw it. Door 58 is then closed, door 64 opened, andv chain 22 advanced toward the forward end of the furnace until dog 42 engages thetray. Thischain is then withdrawn tothe rear end of the heat treating chamber, leaving 'the tray properly positioned on'rollers 18 inthe chamber. At ,the end of the treating period and 'with door 64 again opened, chain 22 is advanced Iand the tray pushed back into vestibule 13 by means of' projection 1,40.' The tray then rests on platform 51'which lhas `been raised. Chain 22 is again withdrawn and is free lof 4the tray since the upper portion of the dog 42 is lowered by means of cam 44. The platforms are again lowered so that the work is immersed in the quenching medium and platform 52 is again at the level of the charge table i and furnace hearth. While the work is being quenched another tray of work may be charged into the furnace if desired. Platform 52 is raised after the'quenching period is overand the tray is discharged from platform 51 by chain 22 and dog 42' which remains in its upward The chain meshes with a position when the chain is advanced and engages the tray when the chain is reversed.

It may be seen through the above illustration that the invention provides a quick, efficient means for transporting work in, into, and out of a furnace and allows a tray to be charged while a previously heat-treated tray of work is being quenched. Maximum output may thus be achieved with a given furnace.

The foregoing has been intended to serve in an illustrative and not a limiting sense, the only limitation being in accordance with the scope of the claims appended hereto.

We claim:

l. A heat-treating furnace comprising: a heating chamber; means for heating said chamber; a door controlled opening at the front end of said chamber; a quench tank outside said chamber and below said opening; iirst conveying means for slidably supporting work in chamber; a trough in said chamber parallel to the direction of travel of the work to be heat treated; a quench elevator having an upper position and a lower position, the latter being in said quench tank; second conveying means for slidably supporting work on said elevator, said second means being aligned with said first conveying means when said elevator is in its upper position; a conveying chain extending through an opening in the back of said chamber, with a rst end in said chamber and a second end outside said chamber, said rst end being located in said trough; a sprocket located outside the back end of said chamber and enmeshing said chain between its ends; a projection on said first end and extending above the level of the conveying means; a releasable dog associated with said rst end and spaced from said projection in a direction toward the front end 'of said chamber, one end of said dog extending above the level of said conveying means when in its normal position; and a cam on said elevator for releasing said dog, whereby said cam will lower that end of said dog extending above said conveying means when said chain is driven by said sprocket toward the charge end of the furnace and release said dog from engagement with a tray when said chain is withdrawn.

2. Apparatus according to claim l characterized by a gas-tight housing outside said chamber which encloses said sprocket and that portion of said chain outside said chamber.

3. In a heat-treating furnace having a heating chamber; means for heating said chamber; a door controlled opening at the front end of said chamber; a quench tank outside said chamber and below said opening; first conveyor means for supporting and moving work in said chamber; a quench elevator having lower and upper platforms which are parallel and in spaced relationship with one another; means for moving said elevator in a vertical manner between an upper and lower position, said lower platform being aligned with said conveyor means when said elevator is in its upper position and said upper platform being aligned with said conveyor means and said lower platform being in said quench tank when said elevator is in its lower position; the improvement which comprises: guide means adapted to be located in said chamber parallel to the direction of travel of work to be heat treated; a conveying chain extending through an opening in the back end of said chamber, with a rst end in said chamber and a second end outside said chamber, said rst end being associated with said guide means which guides and prevents the chain from buckling; a sprocket located outside the back end of said chamber and enmeshing said chain between its ends; a projection on said rst end and extending above the level of the conveying means; a releasable dog associated with said rst end and spaced from said projection in a direction toward the front end of said chamber, one end of said dog extending above the level of said conveying means when in its normal position; means for reversibly driving said sprocket; and cam means attached to the rear portion of said lower platform for releasing said dog from engagement with a tray of heat-treated work when said cam means is in contact with said dog. 5 4, Apparatus according to claim 3 characterized by a charge table located on the side of said quench tank opposite the heating chamber; second conveyor means on said charge table aligned with said first conveyor means; second guide means parallel to the direction of travel of work on said charge table; a second conveying chain, the iirst end of which is associated with said second guide means, said second chain being guided and prevented from buckling by said second guide means; a second sprocket located adjacent the front of said charge table and enmeshing said second chain; second means for reversibly driving said second chain; a second projection on said first end of said second chain and extending above the level of said second conveyor means; a second releasable dog aflxed to said first end of said second chain and spaced from said projection toward said chamber, one end of said dog extending above the level of said second conveyor means when in its normal position; and second cam means attached to the forward portion of said upper platform for releasing said dog from engagement with a tray of work to be heat-treated when said second cam means contacts saidsecond dog.

5. A heat-treating furnace comprising: a heating charnber; means for heating said chamber; a door controlled opening at the front end of said chamber; a vestibule outside of and attached to the front end of said chamber; conveying means for slidably supporting work in said chamber; guide means located in said chamber par allel to the direction of travel of work to be heat treated; a double-ended conveying chain extending through an opening in the back of said chamber with a first end in said chamber and a second end outside said chamber, said rst end being located in said guide means; a sprocket located outside the back end of said chamber enmesh ing said chain between its ends; a projection on the first end of said conveying chain to engage work on the conveying means; a releasable dog `attached to the iirst end of said conveying chain and spaced from said projection in a direction toward the front end of said chamber, said dog having a normal Work engaging position, and means within said vestibule for selectively releasing said releasable dog, said means being externally operable, whereby when said chain is advanced from the rear of the heating chamber toward the vestibule to discharge work from .the chamber said means may be operated to release said dog and the chain can be returned to said chamber leaving the work in said vestibule, and when said chain is advanced from the heating chamber into the vestibule to extract work from said vestibule, the releasable dog will remain in its normal position to engage the work so that the work will be pulled from the vestibule into said chamber when Ithe chain is returned thereto.

6. Apparatus according to claim 5 and comprising an elevator located within said vestibule, said elevator having lower and upper platforms which are parallel and in spaced relationship with one another; externally operable means for moving said elevator in a vertical manner between an upper and lower position, said lower platform being aligned with said conveying means when said elevator is in its upper position and said upper platform being aligned with said conveying means when said elevator is in its lower position; and wherein said means for releasing said releasable dog comprises a cam attached to the rear portion of said lower platform whereby when said chain is advanced from the rear of the heating chamber toward the vestibule with the elevator in its upper position, the cam will contact and release said releasable dog, and the chain can be returned to said chamber leaving the work in said vestibule, and

when said chain is advanced from the heating chamber into the vestibulewith the elevator in its lower position, the releasable dog will remain in its normal position to engage the work so that the Work will be pulled from the vestibule into said chamber when the chain is returned thereto.

References Cited in the le of this patent UNITED STATES PATENTS Hollander Feb. 16, 1909 6 Lister July 24, 1923 Ipsen Oct. 28, 1952 Ipsen May 19, 1953 Dow May 19, 1953 Leftwich July 28, 1953 Holcroft Feb. 16, 1954 Ipsen June 15, 1954 Joy Sept. 6, 1955 Ipsen May 29, 1956 Wingate Jan. 1, 1957

Images