US2671969A - Oven for drying or baking molds and cores - Google Patents

Description

March 16, 1954 c. F. MAYER 2,671,969

OVEN FOR DRYING 0R BAKING MoLDs AND coREs Filed Dec. 2, 1952 2 Sheets-Sheet 2 jkl tlll

M) ya@ IN VEN TOR. CARL E' MA YE@ rroR/vy Patented Mar. 16, 1954 UNITED STATES PATENT avrete OFFICE OVEN FOR DRYING OR BAKING MOLDS AND CORES 10 Claims.

Thisinvention relates, generally, to that class ing or for baking green sand molds and cores.

thereby to convert them into so-called skin dried or dry sand molds and cores.

An oven of the particular type with which my present invention is concerned consists of an elongated structure enclosing a tunnel-like passage that is open at its ends and through which the molds and cores are continuously moved by conveying means. Heated gaseous iiuid is constantly circulated through a part of the oven, thereby to create a heating zone that usually occupies the greater portion of the length of said passage, and wherein the molds or cores are dried or baked, while a lower temperature illid. desirably atmospheric air at ambient temperature, is impelled through an adjacent part of the oven, usually substantially the remaining portion of the length of said passage, thereby to provide a cooling zone wherein the molds and cores are cooled to at least a comfortable handling temperature before leaving the oven.

Obviously, other factors remaining constant,

.it takes longer to bake molds or cores to a dry state, than it does to surface dry them; and it takes longer to dry or bake thick wall molds than .those having thin walls, or 4massive cores, than those of less bulk. Furthermore, the composition of molds and cores that are handled during 2 a Vparticular run of the oven, may differ somewhat from the composition of molds and cores handled at other times, and these diverse circumstances call for heating periods of different duration in order to avoid over or under drying I or baking.

As is well known to those acquanited with the type of oven to which the invention pertains, it has heretofore been the practice to alter the drying or baking period by changing the speed s of the conveyor. This practice, however, connes the ilexibility of the oven, so to speak, solely to the variable speed of the conveyor.

It is a purpose of my invention to increase this range of iiexibility by providing also, means for changing the length oi the heating zone. In adjusting the oven tothe requirements of a particular run, the speed of the conveyor and the length of the heating zone are coordinated to accomplish the highest rate of production with the proper degree of drying or baking.

In view of the various before-mentioned considerations, it is another object of my invention to provide an oven of the type above described including means for conveniently changing the length of the heating zone according to different requirements, and. wherein the minimum length cooling zone resulting from the maximum extension of the heating zone is suflicient to cool the work to a handling temperature. The lengthening of the cooling zone, on the other hand, 130 its full capacity which results from shortening the heating zone as much as possible has no detrimental effect, but rather an advantageous one. In the carrying out of my invention I employ supply duct means and receiving duct means that extend substantially the full length of the oven structure and I desirably arrange them with the supply duct means adjacent the top of the oven passage and the receiving duct toward or at the bottom thereof, although my invention is not particularly limited to this arrangement. Intermediate the ends of the supply and receiving duct means are provisions for dividing each of said duct means into sections of varying lengths, my present preference being a plurality of dampers spaced apart along the respective supply and receiving duct means, with the corresponding dampers of the two duct means in substantially the same vertical plane.

It is another object of my invention t0 operatively connect corresponding dempers of the supply and receiving duct means so that they may be operated in unison and so that they will open simultaneously and close in the same fashion.

A further object of the invention is to provide mechanism by which all of the dampers are interconnected in'such a Wag,7 that only one of the upper dampers, and the corresponding lower damper, willfbe closed at any one time; and it is a still further object to include in said mechanism indicating means showing the length of the heating zone and the length of the cooling zone that results from each adjustment of said mechamsm.

These and other objects-including simplicity of structure and unique duct arrangement resulting in increased efciency, are attained in the embodiment of the invention illustrated in the accompanying drawings, wherein:

Fig. l represents a longitudinal section through the oven substantially on the line I-I of Fig. 4;

Fig. 2 is a fragmentary side elevation, on a scale twice that of l, showing the damper adjusting mechanism and the indicating means; Fig. 3 is a similar view showing the opposite side of the oven and the operative connections between the corresponding upper and lower dampers, and

Figs. 4 and 5 are transverse sections on the 3 line AA, looking in the direction of the arrows 4, 4 and 5, 5 respectively.

In the drawings, like parts are designated by like reference characters throughout the several views.

The oven consists of an elongated structure, designated generally by the reference numeral I, that is made up in most part of a casing cornposed of a top wall 2, side walls 3 and 4 and end walls 5 and 6, all desirably insulated in the usual way, the latter walls 5 and 6 being provided with an inlet opening 'i and an outlet opening 8, respectively. This casing is supported upon a floor I6 Over a pit I I that is dened by a bottom wall I2, side walls 3a and It, and end walls 5a and 6a, said end walls being spaced a substantial distance from the respective end walls 5 and E of the casing, the walls I2 and 3a to 6a' being of concrete or similar material and integral with the oor Il). It is apparent from the disclosure so far that the'walls I2, ."1a and 4a are parts of the elongated structure I that encloses-a tunnel-like passage designated A.

Supported within and transversely of the passage A, adjacent the top wall 2` and. near the respective end walls 5 and 6, are exhaust ducts I5 and I6, each having branches il and I8, respectively, that. extend down along the side walls 3V and 4 of the casing, the opposed branches of the exhaust duct I6 continuing substantially to the bottom of said walls, while those of the exhaust duct I5 stop in proximity to the lower end of the inlet opening 1A. Said branches are provided with inlet means or slotsv I9. Proiecting laterally from cach of the exhaust ducts it',4 and I.6, through openings in the respective walls 5 and. v,.are duct extensions that communicate, through conduits 22, with the inlets ci the shells of impellers or blowers 24, shown as driven by electric motors 26. The outlets of the shells of desirably co-extensive in length. with the supp-y fe duct 36, are auxiliary supply ducts or headers 33 that communicate at intervals therealonf with the duct through cross ducts 35,A any suitable number being employed. Communicatin". with and depending from the headers 33 are drop ducts 3l that are spaced apart along the pas,- sage A, and are provided with outlet means or openings 3S. The duct 30, alone, or in combination with one or more of the ducts and headers communicating therewith, constitutes the supply duct means hereinbefore referred to.

Situated in the lower portion of the structure I. is a receiving duct means, presently in the form of a continuous duct 49 that is suitably sup.- ported midway between the bottoms of the casing walls 3 and 4, and is provided throughout4 its length with inlet means or openings 4 i. The duct 4G is shown as terminating adjacent the inlet end of the passage A in the vertical plane of the corresponding end of the supply duct 30, and. at its opposite end it proiects between the downwardly extending branches I3 of the exhaust duct` I6, wherewith it communicates through lateral ducts 42. y

The upper or supply duct means, comprising,

4 in the present instance, the supply duct 30 and headers 33, is provided with dampers 45, and fil', that are spaced apart a substantial distance longitudinally of said duct means. The lower or receiving duct means is equipped with a like number of dampers, designated 45a, 46a and 41a, those of the lower series being directly below the corresponding dampers of the upper series.

While the several dampers may be equipped with individual adjusting means for opening and closing them, I prefer to provide operative connections between the corresponding upper and lower dampers so that they may be operated in unison and in the same manner-that is to say, so that both will be opened or closed at the same time. The corresponding upper and lower dampers may be thought or" as a set; and it is a further desire to interconnect the several sets by suitable adjusting mechanism whereby the dampers of only one set will be closed at any one time. To these ends provide the damper adjusting mechanism illustrated in Fig. 2, and I operatively connect the dempers of each set by the means shown in Fig. 3. Referring to the latter View, the shafts of the dampers i5 and e5, where they project beyond the wall 3, have secured to them arms 553 whose distal ends are connected together by a link 5I, shown in the present instance as having attached thereto a weight 53. Secured to the shafts of the dampers 4l and Ma are arms 55, shown as arranged in reverse relation to the arms 5); and the arms 55 are operatively connected by a link 's on which is shown av weight 58. Fastened to the shafts of the dampers 46 and 45a are sprocket wheels 60 about which is engaged a chain 62.

Referring now to 2: gear quadrants 65 and 5B are fastened to the ends of the shafts of the respective dempers 45 and 47, where said shafts extend beyond the wall li. These quadrants are shown as extending from the opposite sides of the shafts to that from which the arms 56 and 55 proiect. Accordingly, the weight of said arms and their connecting links and weights, tends to hold the quadrants F55 and 65 against the respective stops 68 and 63. Fastened to the corresponding end of the shaft of damper 46 is a gear segment i9. As will be noted, this segment is in a central position when the damper 46 is closed. It will further be observed that the clampers 45 and 4@ of the central set are closed. when those of the other sets are open. A bar 12 is shown as supported alon'rside the oven wall 4 by guides or rollers i3. A rack 'M on said bar constantly meshes with the gear segment lil. Shorter racks 'l5 and i6 on the bar 'i2 are arranged for cooperation with the respective gear quadrants and 65. A lever 'i8 is pivoted at 'i9 to the wall l and has connection with the bar i2 throuffh a link 230. Accordingly, when the lever is swunnr on its pivot, as by means of a handlel S2, it will move the bar 'l2 longitudinally.

When the dampers of any one set are closed, they divide the respective supply and receiving duct means into so-called heating cooling sections which, in turn, determine the length of the heating and cooling zones of the passage A. Accordingly, the length of these zones may be varied by closing the dampers of the different sets, it being remembered that when the dampers of any one set are closed, those of the other sets are open. According. to the arrangement of the dempers illustrated in the drawings, the heating zone extends from the vicinity of the inlet opening -1 of the oven casing to the central set of dampers, or, in other words, to the set comprising dampers 46 and 46a. It follows, therefore, that the cooling zone extends from the vertical plane of said dampers to near the outlet opening 8 of the oven casing.

Supported upon the oven structure I, about midway between the ends thereof, is a conventional type of heater 85, red by oil or other medium. The inlet of the circulating space of the heater is placed in communication with the receiving duct 4B by conduit means 88 that extends across the top of the structure and down the opposite sides thereof and thence inwardly through openings in the side walls 3 and 4 and joins the duct 40, as best shown in Figs. l and 4. The outlet of the circulating space of said heater is placed in communication, through conduit means 89, with the inlet of the shell of an impeller or fan designated 90. This impeller or fan is driven by an electric motor 9|. 'I'he outlet of said shell opens through the top wall 2 into the supply duct 30. It is evident, from the arrangement described, that when the impeller or fan 90 is in operation, gaseous fluid will be withdrawn from the heating Zone of the passage A through the duct 48, duct means 38, the circulating space of the heater 85 and duet means 89 into the shell 90, from which it will be expelled into the duct 38, to be distributed throughout the heating Zone by said duct and the drop ducts 31.

Surmounting the structure I above the cooling zone is an impeller or fan 95 that receives atmospheric air through a pipe 96 that is connected to the inlet of the shell of' said impeller or fan. The outlet of said shell has communicative connection through an opening in the top wall 2, with the section of the supply duct 30 in the cooling zone. The impeller or fan 95 is driven by a motor 98 and when in operation draws in atmospheric air and distributes it throughout the cooling zone by way of the section of the supply duct means situated in said zone and including, in the present case, the corresponding sections of the headers 33 and the drop ducts 31 that depend therefrom. At the same time, air is withdrawn from the cooling zone through the section of the receiving duct 48 1ocated therein and this air is exhausted to the atf mosphere through the connections previously described, including the exhaust duct I6 and its branches I8 ,and the adjacent irnpeller or blower 24.

An endless conveyor |99, schematically illustrated in the drawings, serves to carry the Work, which may consist of molds and/or cores, continuously through the passage A, the upper, work-supporting flight of the conveyor entering the passage through the inlet opening 1, and leaving the passage through the outlet opening 8. The conveyor, in the present embodiment of the invention, consists of endless chains that are guided about pairs of large sprockets |92 and |03, mounted on shafts that are journaled in supports shown as located in the pit adjacent the end walls 5a and il@4 thereof. Occupying an offset of the pit is an electic motor |85 that drives, through a change speed mechanism |86 and a chain or belt |81, the shaft to which the sprockets |13 are fastened. The work-supporting part of the conveyor may be made up of cross bars or rods that are carried by and between the opposed chains of the conveyor. Except in a broad sense, the conveyor constitutes no part of the present invention, and accordingly itis believed unnecessary to illustrate and describe, in detail, the structural features of the conveyor and its supporting and guiding means.

In the use of the oven, the work is moved at an appropriate speed through the passage A by the conveyor |00, whereon it rests, and while traveling through the heating zone the work is subjected to the hot gaseous fluid that is blasted downwardlly and laterally against and about the work by the duct and drop ducts 31. Said fluid is then returned through the section of the receiving duct that is located in the heating zone, and through the duct means 88, to the heater 85, where it is reheated, and from which it is conveyed by the duct means 89 to the shell of the impeller or fan 98. Under the influence of the impeller or fan, the reheated fluid is returned to the heating zone through the supply duct means. As the work continues on through the cooling zone, its temperature is lowered by the atmospheric air that is circulated through said zone in the manner already described.

The exhaust ducts |5 and I6, with their branches, serve to arrest atmospheric air that tends to enter the oven through the openings 1 and il, and prevent escape of the gaseous fluid from the oven, which latter is laden with vapors that are driven off from the work during the treating process.

In practice, and by way of example, the aggregate length of the heating and cooling zones may approximate feet; and the sets of dampers may be four feet apart, with` the central set approximately 34 feet from the receiving end of the heating zone, and, accordingly 16 feet from the exit end of the cooling zone. On this basis I have shown as applied to the side wall 4 of the oven casing, in association with the lever 18 that serves as a pointer, three index marks that have associated with them designations showing the length of the heating zone and the length of the cooling zone when the lever points to any selected one of the index marks. With the damper adjusting mechanism in the position illustrated in Fig. 2, the dampers 46 and 46au of the middle set are closed, while the `dampers of the other sets are open, and as a consequence thereof the heating zone is 34 feet longand the cooling zone 16 feet long, this fact being indicated by the designation 34' I-I-lf C. When the lever is swung by means of the handle 82 to the left, as theparts are viewed in Fig. 2, until said lever points to the left hand index mark, the gear quadrant will be swung through by the rack l5, which, as previously pointed out, is carried by the bar 12 which has connection with said lever through the link 89, thereby to close the dampers 45 and 45a. At the same time the rack 14 will swing the gear segment 10 through 90 to open the dampers 46 and IlliaV of the middle set. The-dampers 4'! and 4l'a of the third set will remain open for the reason that, under the present circumstances,

the rack 18 will move away from the gear quadrant 68 and leave it against the stop 69, and the dampers 41 and 41a open. Under such an adjustment of the mechanism, the heating zone will be 30 feet long and the cooling Zone 20 feet long, according to the designation to which the lever now points. It is evident from what has been said that when the lever is swung to its other extreme position, the dampers 41 and 4'1a will be closed, while the othersl will be open.

accises 7 This adjustment ci the. dempers will lengthen the heating zone to 38 feetl and shorten the cooling zoneto l2 feet.

Thus the length. of the heating' zone, and consequently the effective duration ofV theA heating period, may be varied according to the requirements of the work being handled.

Having thus described my invention, what I claim is:

l. An elongated oven structure having an inlet opening at one end and an outlet opening at the other and enclosing a through passage, conveying` means for continually moving work through said passage, continuous supply duct means opening into said passage substantially throughout the length thereof, continuous receiving duct means communicating with said passage approximately irorn end to end thereof., means intermediate the endsof each or" said' duct means by which the latter means may be separated at different selected locations therealong into a heating section and a cooling section, communicative connections between the heating sections of the two duct means, heating and impelling means in said communicative connections arranged to withdraw gaseous fluid from the through passage through the heating section of the receiving duct means and heat said fluid and return it to the passage through the heating section of the supply duct means, air impelling and conducting meansfor delivering atmospheric air to the cooling section of the supply duct means, and exhaust means in communication with the cooling section of the receiving duct means for withdrawing air from said passage.

2. The combination and arrangement of. parts den'ned by claim l, and additional exhaust means communicating with the through passage immediately adjacent each end thereof.

3. An elongated oven structure having an inlet opening at one end and an outlet opening at the other and enclosing a through passage, conveying means for continually moving Work through said passage, continuous supply duct means opening into said passage substantially throughout the length thereof, continuous receiving duct means communicating with said passage approximately from end to endv thereof, means intermediate the ends 0f said duct means by which each of said duct means may' be. separated at different selected locations therealong, but substantially corresponding locations with respect to the other duct means, into a heating section and a cooling section, com-Y municative connections between the heating sections oi the two duct means, heating andv impelling means in said communicative connections arranged to withdraw gaseous uid from the through passage through the heating section of the receiving duct means and heat said uid and return it to the passage through the heating section o1" the supply duct means, air impelling and conducting means for delivering atmospheric air to the cooling section of the supply duct means, and exhaust means in communication with the cooling section of the receiving duct means for withdrawing air from said passage.

4. The combination and arrangement of parts defined by claim 3, and further exhaust means communicating with the through passage immediately adj acent each end thereof'.

5. An elongated oven structure havingv an inlet opening at one end and an outlet opening at the other and enclosing a through passage, convey-- ing means for continually moving work through said passage, continuous supply duct means opening into said passage substantially throughout the length thereof, continuous receiving duct means communicating with said passage approximately from end to end thereof, a series of dampers in and spaced apart longitudinally of each of said duct means for separating the duct means into heating sections and cooling sections of varying lengths, respectively, means fol` opening and closing said dampers at will, the individual dempers of the supply duct means being in substantially the vertical plane of the corresponding dampers of the receiving duct means, communicative connections 'between the heating sections of the two duct means, heating and impelling means in said communicative connections arranged to withdraw gaseous duid from the passage through the heating section of the receiving duct means and heat said iiuid and return it to said passage through the heating section of the supply duct means, air impelling and conducting means for delivering atmospheric air to the cooling section of the supply duct means, and exhaust means for withdrawing the air from the passage through the cooling section or the receiving duct means.

6. An elongated oven structure having an inlet opening at one end and an outlet opening at the other and enclosing a through passage, conveying means for continually moving work through said passage, supply duct means opening into said passage substantiallyl throughout the length thereof, receiving duct means communicating with said passage approximately from end to end thereof, a plurality of dampers in the supply duct means and spaced apart longitudinally thereof, a similar number or" dempers in the receiving duct means and spaced apart longitudinally oithe latter according to the spacing apart of the former dempers, each damper associated with the supply duct means being in substantially the same vertical plane as the corresponding damper of the receiving duct means and constituting therewith a set, operative connections between the dempers of each set whereby they are caused to move simultaneously and in substantially like manner, the dampers of each duct means being intermediate the ends of said means and being adaptedv to divide the duct means into a heating section and a cooling section, communicative connections between the heating sections of the two duct means, heating and impelling means in said communicative connections arranged to Withdraw gaseous fluid from said passage through the heating section of the receiving duct means and heat said fluid and return it to the passage through the heating section of the supply duct means, air impelling conducting means for delivering atmospheric air to the cooling section of the supply duct means, and exhaust means for withdrawing air from said passage through the cooling section of the receiving duct means.

7. The combination and arrangement of parts dened by claim 6, and further exhaust means communicating with the passage immediately adjacent the ends of the passage.

S. The combination and arrangement of parts defined.' by claim 6, and damper adjusting mechanism oy which the dampers of any selected set may be closed while the dampers or" the other sets are disposed in open position.

9. The combination and arrangement of parts defined by claim 6; and, in addition thereto, damper adjusting mechanism by which the' dampers of any selected set may be closed While the dampers of the other sets are disposed in open position, and indicating means designating the length of the heating Zone and the length of the cooling zone resulting from each damper adjustment.

10. The combination and arrangement of parts dened `by `claim 6; and, in addition thereto, damper adjusting mechanism by which the dampers of any selected set may be closed while the dampers of the other sets are disposed in open position, said mechanism including an element that is moved to different positions when the different sets of dampers are closed, and a designation at each position indicating the length of the heating zone and the length of the cooling zone when said element is in said position.

CARL F. MAYER.

References Cited in the file of this patent UNITED STATES PATENTS Number Number Name Date Dreffein Oct. 28, 1930 Hormel Mar. 12, 1935 Byron Oct. 5, 1937 Byron Nov. l, 1938 Mayer Aug. 15, 1944 Barnett Oct. 2, 1945 FGREIGN PATENTS Country Date Switzerland May 2, 1932

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