US3251620A - Apparatus for bulk curing tobacco - Google Patents

Description

May 17, 1966 F. J. HASSLER APPARATUS FOR BULK CURING TOBACCO 4 Sheets-Sheet 1 Filed Sept. 30, 1965 m S 5 k w 1 4 o N, w. x 5 9 w a ma nn w 'QIII} E M b w l m M J Z 4 E w 4 I f; 4422 Lu W V H m a WW I )6 m H/S fl 7" TOENEYS y 7, 1966 F. J. HASSLER 3,251,620

APPARATUS FOR BULK CURING TOBACCO Filed Sept. 30, 1965 4 Sheets-Sheet 2 INVENTOR. FZflA/C/S J, #45516? BY 6W M 5% HIS flTTOE/VEYS' 1966 F. J. HASSLER 3,251,620

APPARATUS FOR BULK CURING TOBACCO Filed Sept. 30, 1963 4 Sheets-Sheet 3 92 ""TI L1 v ll 8 A INVENTOR. FF/M/C/S J. #455155 HIS flTTOFA/EYS May 17, 1966, F. J. HASSLER APPARATUS FOR BULK CURING TOBACCO 4 Sheets-Sheet 4.

Filed Sent. 30, 1963 United States Patent Filed Sept. 30, 1963, Ser. No. 328,146 1 Claim. (Cl. 294-55) This application constitutes a continuation-in-part of my copending application, Serial No. 35,499, filed June 13, 1960, now Patent No. 3,105,713; as well as a -continuation-in-part of my copending application, Serial No. 164,789, filed January 8, 1962, which is now abandoned.

The present invention relates an improved apparatus for curing tobacco in bulk, however, the invention is not necessarily so limited.

A fundamental problem in tobacco production is the great amount of hand labor required in the conventional method of production. Approximately three-fourths of the total labor required in the production of tobacco is devoted to harvesting and processing operations. In recent years much has been done in the way of mechanizing harvesting operations and the labor saving through mechanization has been substantial. However, there has been little advance in the techniques for processing the harvested tobacco. Thus, the techniques for processing tobacco today are, with the exception of a few minor improvements, the same as employed more than a century ago.

In curing tobacco it has long been the practice to string the tobacco leaves on elongated sticks which are supported in a curing barn, The stringing operation is a cumbersome and time-consuming operation which must be done by hand. When the tobacco has been strung and placed in the barn, it is carried through a curing operation which can be roughly divided into four stages.

These stages will be described in detail in the following remarks. Accordingly, it sufiices for the present to state that the first stage is a leaf yellowing stage wherein physiological transformations evidenced by yellowing of the tobacco leaf occur. In the second stage, the leaf is dehydrated to halt the physiological transformations occurring in the leaf. In the third stage the dehydration is accelerated so that the stern of the tobacco leaf is dried out. At this point, the tobacco leaf is substantially bone dry and the leaf itself is very fragile. In the final stage, moisture is added to the leaf so that it softens and can be handled. Thereafter, the tobacco is ready for removal from the curing barn for subsequent processing.

It is obvious that the curing of tobacco could be greatly simplified if it were possible to cure the tobacco inbulk. This would eliminate the cumbersome stringing operation since it would then be possible to cure the tobacco in large bundles. Unfortunately, however, the leaf yellowing stage described above involves exothermic reactions in the tobacco leaf. Thus, when tobacco is cured in bundles, large amounts of heat must be dissipated.- For this reason, it has been considered impossible-to satisfactorily control a bulk curing operation.

In the practice of bulk curing, it is found desirable to align the tobacco leaves in a suitable frame with their longitudinal axes parallel and their tips all pointed in the same direction. Air of a controlled temperature and humidity is then forced longitudinally through the leaves. In orderto economize on space, it is also desirable to force the conditioned air through two successive tiers of the framed tobacco, however, this presents a problem, in that the tier first exposed to conditioned air tends to cure out in advance of the second tier. This problem is parice ticularly noticeable in the stem drying stage of the cure cycle, where it is found that the stems of the second tier take a longer time to dry than the stems of the first tier. This problem has been circumvented in the present application by creating tobacco supporting racks especially designed to support the tobacco leaves vertically .in the curing barn and alternatively with their stems pointed upwardly or downwardly. Such racks enable an arrangement of tobacco leaves in two tiers in the curing barn, wherein the stems in each tier are exposed to substantially the same atmosphere throughout the cure cycle and complete the cure cycle at substantially the same time.

Accordingly, it is an object of the present invention to provide an improved tobacco supporting frame or rack for supporting tobacco leaves alternatively with their stems pointed upwardly or downwardly.

It is another object of the present invention to provide an improved method and apparatus for curing tobacco in successive tiers at substantially a uniform rate in each tier.

Other objects and advantages reside in the construction of parts, the combination thereof, the method of manufacture and the mode of operation, as will become more apparent from the following description.

Referring to the drawings:

FIGURE 1 is a perspective view of the tobacco curing barn;

FIGURE 2 is an end elevational view of the barn taken from the direction indicated by the arrows 2-2 of FIGURE 1;

FIGURE 3 is a sectional view of the barn taken substantially along the lines 3-3 of FIGURE 1;

FIGURE 4 is a plan view of the interior of the barn;

FIGURE 5 is a longitudinal sectional view of the barn, illustrating heating apparatus employed therein;

FIGURE 6 is a perspective view illustrating the method of placing tobacco leaves in a rack;

FIGURE 7 is a perspective view illustrating a completed rack of tobacco;

FIGURE Sis a fragmentary plan view of an assembled rack with the tobacco removed;

FIGURE 9 is an end view taken in the direction of the arrows 9-9 of FIGURE 8;

FIGURE 10 is a fragmentary sectional view of the barn, equivalent to FIGURE 3, wherein specially constructed racks are employed to support the tobacco leaves in the upper tier in an inverted position;

FIGURE 11 is an enlarged and exploded perspective view of the specially constructed rack;

FIGURE 12 is an enlarged side elevational view of the rack'of FIGURE 11 with parts broken away; and

FIGURE 13 is an end elevation of the rack of FIGURE 11 illustrating tobacco leaves positioned in the rack.

Referring to the drawings in greater detail, FIGURE 1 illustrates a tobacco barn 10 which is designed specifically for use in the present method. The exterior covering for the barn is formed with a plurality of arched sheet metal panels 11. At the forward end of the barn, as viewed in FIGURE, 1, an overhang 12 is provided. This overhang provides a shelter where tobacco leaves may be Rearward of the partition 14 is another partition 16 which cooperates with a rear end wall 18 to establish a furnace room. The partition 16 isolates the furnace room from the central part of the barn.

As best seen in FIGURE 3, the central part of the barn is divided into three sections by a pair of dividers 20a and 20b extending between the partitions 14 and 16. The doors 14a and 14b and 140 open separately into these sections.

The dividers 20a and 2012, as well as the side walls of the barn, support horizontal rails 22 which form supporting shelves for tobacco racks placed thereon. FIGURE 3 schematically illustrated tobacco racks or supporting frames 24 supporting tobacco leaves 26 mounted on the rails 22. In the tobacco barn illustrated, two tiers of tobacco racks are placed in each of the three sections of the barn.

FIGURES 4 and illustrate a heating system which is installed in the barn. This system includes a furnace 30 located in the furnace room between the partition 16 and the end wall 18. Leading from the furnace at fioor level are three outlet ducts 36a, 36b and 360, each of which is regulated by a hand damper 34. These three ducts pass centrally through the three sections of the central portion of the barn and are each provided with a plurality of spaced openings or ports 38 in the sides thereof through which air may escape. A blower unit 32 located within the furnace forces air into the duct 36. The air leaving the ports 38 moves upwardly between the bulked tobacco leaves and ultimately flows into a return duct 40 located centrally in the barn at an elevation above the dividers 20a and 20b. This duct 40 is provided with spaced ports 42 into which the air moves.

A damper 44 is located in the duct 40 between the several ports 42 and the blower 32. Above the damper is an outlet duct 46, best seen in FIGURE 4, communicating with the outside atmosphere. By adjustment of the damper 44, varying amounts of fresh air may be admitted to the heating system, or, if desired the duct 46 may be closed, such that the air within the system is recirculated without addition of fresh air.

The blower 32 operates to establish a pressure differential between the top and bottom of the curing barn in the central curing section, such that the air is forced to move upwardly through the tobacco. The design of the racks is such as to force the circulated air to flow between the bulked tobacco leaves.

One embodiment of an individual rack 24 is illustrated in FIGURES 8 and 9. This rack includes an elongate side member 50 with outwardly extending rods 52 fixedly secured to each end thereof. A second side member 54 of equal length has apertures 53 therein complementary to the rods 52, the arrangement being such that the rods 52 may be projected into the apertures 53 to assemble the rack. Suitable nuts 55 are threaded onto the rods 52 to fix the assembly. The side member 54 carries a plurality of parallel fixedly attached spikes 56 which, in the assembled rack, abut a shoulder 58 provided on the side member 50.

In bulking tobacco, the rack is used in association with a bin 60 illustrated in FIGURE 6. This bin has an open top and one open side. The end walls 62 of the bin are hingedly joined to the rear panel 63 and are normally locked in the position illustrated in solid line detail. In inserting the tobacco into the rack, the side member 50 is seated on the bottom of the bin and is located by slots 64 provided in the end walls 62. The rods 52 carried by the side member 50 project upwardly in the slots 64. The bin 60 is then filled with tobacco leaves each of which has its base butted against the rear panel 63. The side member 54 is then pressed downwardly into the bin 60 to force the spikes 56 through the tobacco leaves. Any suitably designed press mechanism may be employed to force the side member 54 into the bin 60 in accurate registry with the side member 50.

After the side member 54 has been forced into the bin 60 and secured by means of nuts 55 engaging the lyzed.

, increases with an increase in temperature.

rods 52, the end walls 62 are swung outwardly so that the rack may be removed from the bin. A completed rack of tobacco is illustrated in FIGURE 7. In the completed rack, the shoulder 58 provided on the side member 56 supports the ends of the spikes 56 so that the weight of the tobacco does not deform the spikes.

In loading the racks in the curing barn, the racks are slid along the rails 22 and pushed one after the other into the barn. The dimensions of the racks are modular with respect to the interior of the barn, so that when a full complement of racks are butted one against the other, they exactly fit between the partitions 14 and 16, leaving substantially no room for escape of air around the sides of the racks. In this regard, it will be noted in FIGURE 3 that the leaf stems are directed upwardly and the downwardly directed leaf portions flare outwardly from the racks and cooperate with the rails 22 to minimize the escape of air around the ends of the racks. The air which is forced upwardly through the central portion of the barn must therefore move in and around the tobacco leaves.

As mentioned hereinbefore, the initial portion of the tobacco curing cycle involves exothermic reactions and it is important that the temperature of the tobacco leaves be carefully controlled during this portion of the cycle. This is done by forcing air of the correct temperature and humidity through the tobacco.

At the beginning of the curing process, the tobacco leaf contains complex starch and protein molecules, chlorophyll, nicotine, water and many other components. The leaf moisture content is normally to percent of the total green weight of the leaf. In the initial curing stage, designated the leaf yellowing stage, the major chemical conversions are the simplification of complex starch and protein molecules and the disappearance of chlorophyll by oxidation. Rapid desiccation at this stage would arrest all chemical conversions and accordingly the moisture content of the leaves must be maintained above 70 percent. During this stage, starch molecules are hydrolyzed to simpler sugars. The disappearance of chlorophyll proceeds at a rate parallel to the conversion of starch. Thus, the leaf color is a good indication of the state of the leaf. When all chlorophyll has disappeared, the major portion of the starch has been hydro- This is evidenced by a yellowing of the leaf as the disappearing chlorophyll unmasks yellow leaf pigments.

The rate at which the aforementioned reactions occur Hence, the cure time is shortened with increasing temperature. However, when the temperature exceeds F., and undesirable browning resulting from oxidation of polyphenols occurs, along with other reactions which result in an accumulation of undesirable components. Under the circumstances, it is found preferable to control the leaf temperature to around 100 F. This is accomplished by circulating air which has a temperature in the range 90 to 100 F. through the tobacco. During this stage of the cure a relative humidity of 85 to 95% is employed. The dampers are therefore set to allow a high humidity.

The yellowing stage is normally accomplished within 30 to 60 hours depending upon the state of the leaves when the cure is begun. During this period, the moisture content of the leaf reduces to about 70 or 75%.

After yellowing is accomplished, that is, after the leaf s at the desired chemical state, further chemical reaction 1s arrested by dehydrating the leaf. This stage of the cure process is known as the leaf drying stage. To accomplish dehydration, the air temperature is elevated at a rate of 2 to 3 F. per hour and is ultimately held. in the range of to F. To insure maximum desiccation, the dampers are adjusted to exhaust the humid air with no recirculation. The normal time required for the leaf drying stage is from 20 to 30 hours, during which the leaf moisture content is reduced to a level of 30 to With average atmospheric conditions the air circulated through the curing barn during this stage has a relative humidity of around 40% After dehydration of the leaf, the cure is carried into a stem drying stage, wherein moisture is extracted from the midribs. In this stage, the temperature is increased at the rate of 2 to 5 F. per hour to 160 to 170 F. During this stage the dampers are set to achieve 90 to 100% recirculation of air, thus conserving on fuel. After to 30 hours of drying under these conditions, the stems become brittle while the moisture content of the leaf lamina approaches zero. The leaf becomes crisp and fragile in this stage and it is necessary to recondition or reorder the leaf before removal from the curing barn.

In the final stage of the tobacco cure, moisture is added to the leaf. ways. Under favorable environmental conditions of 50 to 70 F. and 85 to 100% relative humidity, air can be drawn in from outside the barn and forced through the tobacco without additional heat, then exhausted from the barn. However, when the ambient atmosphere is not sufficiently humid, it is found preferable to employ a humidifier, not shown, located within the duct work. The controls are set to provide a temperature of from 80 to 100 F. and a relative humidity of around 85% with full recirculation of air. Normally, the leaf is conditioned to a moisture content of 15 to by weight. The time required for this reconditioning is 6 to 10 hours. The tobacco is then ready for removal from the curing barn.

It is found that bulk curing on the cycle indicated produces a marketable tobacco leaf comparable to the best obtained with conventional curing techniques. At the same time, it is found that the cure obtained is more uniform than that obtained conventionally, such that a higher average market price is realized. Another important advantage resulting from the method and apparatus disclosed herein is a substantial reduction in the amount of labor required to effect the cure.

While the apparatus described in the foregoing can be employed to produce the marketable tobacco leaves, it is found in practice that the cure cycle in the stem drying stage is delayed in the upper tier of bulked tobacco leaves by virtue of the fact that the drying air reaches the stems in the upper tier only after passing through the lower tier of tobacco and around the leaf tips of the upper tier. By the time the drying air reaches the stems in the upper tier, it has picked up a considerable amount of moisture and its drying efficiency is reduced. It is, therefore, desirable for the purpose of drying the tobacco leaves as rapidly as possible, to have the stems of the upper tier directed downwardly, that is, directed upstream with respect to the direction of air flow. I

In the lower tier, it is desirable to have the tips point upstream with respect to the air flow, where they are most directly responsive to changing air conditions. Thus the leaf tips, which constitute the thinnest portion of the leaf, are the first to yellow to the desired state during the leaf yellowing stage. The leaf tips are also most directly susceptible to excessive cure which would produce a brown coloration in the leaf. With the leaf tips in the lower tier directed downwardly, they are so located that the operator of the curing barn can readily inspect the leaf tips to determine the extent of cure and, when the yellowing stage has progressed to the desired point and the drying stages commenced, this is the first portion of the leaf to encounter a drying air which will arrest further chemical reaction.

In the upper tier there is an unavoidable time lag which makes control over the yellowing condition of the leaf tips diflicult whether the leaf tip is pointed upstream or downstream. In practice, however, it is found that the upper leaf tips are sufficiently sensitive to changing air conditions at either leaf position that they closely follow the cure of the leaf tips in the lower tier.

This maybe accomplished in two An accurate control over the cure cycle is important. Thus, during the tobacco season, the lowermost leaves on the tobacco stalks are picked and cured early in the season. After this first cure, the next higher leaves on the tobacco stalk are picked and cured. Then later in the season, still higher leaves on the stalk may be picked ing stage is terminated at the proper time.

and cured. Due to varying weather conditions and variations in the ages of the leaves, no two cures can be expected to progress in the same manner and each cure must be closely supervised to insure that the leaf yellow- The arrangement whereby the leaf tips are directed upwardly in the upper tier and downwardly in the lower tier is found to aflord optimum control over the cure operation consistent with economy of time.

Such an arrangement is illustrated in FIGURE 10, which shows two tiers 70 and 72, wherein tobacco leaves 26 are supported. In the upper tier 72, the stems 26a of the leaves point downwardly. In the lower tier 70, the stems 26a point upwardly. Since the stems in each tier are exposed to substantially the same atmosphere, the stems dry out at substantially the same rate. This arrangement results in a time saving of several hours throughout the cure cycle when compared to the tier arrangment of FIGURE 3.

This time saving assumes importance when it is considered that while the lowermost leaves on the tobacco stalksin a given field are being cured in the barn, the upper leaves on the same stalks continue to age in the field. The shortened cure time permitted by the present.

of FIGURE 10. During the cure of the tobacco, the

leaves become quite limp and fragile. With a rack having a single row of spikes, as illustrated in FIGURES 8 and 9, the leaf must be engaged near the cut end of the stern, where the leaf is thickest, to keep the leaves from tearing away from the spikes. When this is done, the tips are too frail to stand erect under their own weight when pointed upwardly. The result is that the leaf tips in the upper tier settle downwardly, blocking a normal air flow through the upper tier.

In the embodiment of FIGURE 10, this problem is avoided by employing a rack having two rows of spikes mounted in spaced relation so that the tobacco leaves will be supported at two points, one, closer to the tip and the other closer to the cut end of the stem, This arrangement of spikes is found not to interfere with the flow of conditioned air through the bulked tobacco leaves and, at the same time, is found to give adequate support to the tobacco leaves whether the tips are pointed upwardly or downwardly.

The constructional details of this rack appear in FIG- URES ll, 12 and 13. In the exploded view of FIG- URE 11, it can be seen that the rack comprises two interfitting parts, a U-shaped frame 74 and a spike carrying cross member 75. The frame 74 includes a base member 76 with arms 78 pivoted to the opposite ends thereof, the arms 78 being pivoted to brackets 80 which are welded to the base member 76. Adjacent the upper ends of the arms 78 are latch members '82 adapted to interengage the cross member 75.

The cross member 75 comprises an elongate channel member 84 provided with inwardly directed flanges 86 at the sides thereof. Spaced along both sides of the channel member 84 are a plurality of spikes 88 which pass through suitable aligned apertures in the flanges 86 and in the base portion of the' channel member 84. The upper ends of the spikes '88 are turned to the rightpumle upper ends of these spikes 88 are turned at right angles to form fingers 88a, which are locked in tongues 90 struck out of the base of the channel member 84.

The inwardly directed flanges 86 extending along the sides of the channel member 84 are cut away at the ends of the channel member to provide a clearance for movement of the upper ends of the arms 78 under the base of the channel member 84. The arms '73 are adapted to be secured in this position by means of spring members 92 attached with tongues 94 and 96 to the opposite ends of the channel member 8-4. Each spring member 92 is provided with a downwardly directed V-shaped detent portion 98 which projects through a slot 97 in the base of the channel member 84. The V-shape of the detent portions 98 permits the springs 92 to be cammed upwardly by the latch members 82. in the arms 78, as these arms are pivoted into position under the channel member 84. Apertures 100 in the latch members 82 receive the detents 98 when the arms 78 have been pivoted into position.

The assembled rack is illustrated in FIGURES l1 and 12. In loading the rack, the cross member 75 is removed and tobacco leaves are then piled loosely on the frame, using the upwardly directed arms 78 to limit the spread of the pile of leaves. When the tobacco has been piled to a sufficient depth, the cross member 75 is pressed downwardly to force the spikes through the tobacco leaves. Thereafter, the arms 78 are pivoted into latching position. In order to secure the cross member 75 against accidental separation from the frame, the legs 98a of the spring detent 98 are formed at an acute angle with respect to the base of the channel member 84. This construction is best illustrated in FIGURE 12. Separation of the rack components will not occur unless the spring members 92 are deliberately bent upwardly.

For supporting the racks in the barn, the various curing compartments in the barn are provided with horizontal rails 102 on each side thereof. As best illustrated in FIGURE 10, these rails 102 have V-shaped grooves formed therein, which are adapted to receive the edges of inwardly directed flanges 104 formed on the sides of the arms 78 of the rack. To insure free sliding movement of the flanges 104 on the rails while maintaining a good air seal, the ends of the V-shaped grooves formed in the rails may be closed and a suit-able lubricant placed in the troughs formed by the V-grooves.

As best illustrated in FIGURE 13, the side of the base portion of the frame 74 opposite the flanges 104 is provided with an upturned flange 108. When the tobacco supporting rack is positioned in the curing barn, the upturned flange 108 supports the ends of the lowermost row of spikes of the rack and thereby prevents the spikes from turning downwardly under the weight of the tobacco leaves placed thereon. Also, clearly illustrated in FIGURE 13, is a second downwardly turned flange 106 formed on the opposite side of the base portion of the frame 74. This flange 106 is adapted to overlie the cross member 75 'of the adjacent rack when the racks are assembled in tiers in the curing barn. This completes an air seal between adjacent racks, so that in the fully assembled barn the conditioned air which is introduced under pressure in the lower part of the barn is forced to move through and between the bulked tobacco leaves.

In the foregoing description, it will be apparent that the tobacco'rack of FIGURES 11, 12 and 13 constitutes an easily assembled and maintained tobacco rack which is adapted to support tobacco leaves in either of two orientations, namely, an orientation wherein the leaf tips are pointed upwardly and an orientation wherein the leaf tips are pointed downwardly. FlGURE 13 illustrates the tobacco leaves approximately centered on the supporting frame. However, it will be apparent that for leaves supported with the stems directed upwardly, the leaves can be positioned with more of the tips hanging downwardly, and, conversely, with the tips directed upwardly, the leaves can be supported with more leaf stems hanging downwardly.

Although the preferred embodiment of this apparatus has been described, it will be understood that within the purview of this invention various changes may be made in the form, details proportion and arrangement of parts, the combination thereof, the method of manufacture and mode of operation, which generally stated consist in a device capable of carrying out the objects set forth, as disclosed and defined in the appended claim.

I claim:

Apparatus for supporting tobacco leaves in bulk, comprising a frame member having a generally straight base portion and a pair of generally straight side arms each being pivotally mounted at one end to an adjacent end of said base portion for movement into an operative position extending generally at right angles to said base portion, a separate generally straight cross member adapted to span said operatively positioned side arms in parallel relation to said base portion so as to form a substantially rectangular open centered rack in operative position, said cross member supporting a plurality of elongated parallel spikes adapted to traverse the open center of said operatively positioned rack from said cross member to said base portion, said spikes being arranged in two parallel rows extending between said pair of side arms in operative position, and detachable means interengaging the cross member with each of said side arms adjacent the one end thereof when said rack is disposed in said operative position, the construction and arrangement being such that in assembling said rack into said operative position said cross member may be moved substantially rectilinearly in the direction of longitudinal extent of said spikes to thrust said spikes through a plurality of tobacco leaves piled loosely in said frame member in transverse relation to said base portion, said parallel rows of spikes engaging the tobacco leaves at two points along the length thereof.

Reterences Cited by the Examiner UNITED STATES PATENTS 1,666,648 4/1928 Harrington 2945.5 2,566,589 9/1951 Touton l3l-l40 2,610,883 9/1952 Aleshin 2945.5 2,808,283 10/1957 Vickers 294-5.5 3,134,583 5/1964 Wilson 2945.5 X

GERALD M. FORLENZA, Primary Examiner.

MELVIN D. REIN, Examiner.

G. F. ABRAHAM, Assistant Examiner.

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