US2039329A - Drying sheet material - Google Patents

Description

vMay 5, 1936 M. M.` MERRxTT 2,039,329

DRYING SHEET MATERIAL Filed Nov. 5, 1934 3 Sheets-Sheet 1 l I 'E A '/4 l I f6 //2 o l l J g JHMJLJ LJ L] L] Lw] LW] LJLL-JL LJ [HH] L] Lr] L1A-.HL C' lq H o C l l 1L G D L In venor u h If U rl r v I. M i

May 5, 1936- M. M. MERRlT-r 2,639,329

DRYING SHEET MATERIAL Filed Nov. 5, 1954 5 .Sheets-Sheetl 2 Inventor' www May 5, 1936. I

M. M, MERRITT DRYING SHEET MATERIAL Filed Nov. 5, 1934 3 Sheets-Sheet 3 Patented May 5, 1936- UNITED STATES PATENT Aorf-ICE DRYING SHEET MATERIAL Matthew M. Merritt, Middleton, Mass., assignor to The Tanning Process Company, Boston, Mass., a corporation of Massachusetts Application November 5, 1934, Serial No. 751,512

16 Claims. (Cl. 34-40) This invention relates to the drying of articles of manufacture, such as various kinds of sheet material, and of various natural products. While the invention is illustrated as applied to the drying of hides and skins secured in slicked-out con- .dition upon drying boards, it will be understood skins. In the tunnel construction, there is invariably provided a more or less complicated conveyor mechanism and heated air in large quantities is passed continuously through the tunnel during the travel of the conveyor. The hides or skins emerge from the tunnel usually thoroughly dried but in a condition so hard and harsh to the touch that they must be sammied or put in dampened-back condition before any further operation may be performed looking to the finishing of the hide or skin. This criticism applies with equal force to the hides or skins dried in a loft or other chamber with heated air supplied for the pur#- pose. In the case of large chambers, there is considerable variation in the moisture content of the air in various parts of the chamber and dead air spaces are common, with the result that there is a notable lack of uniformity in the quality of c the hides or skins as well as in the degree to which they have dried. In general, it maybe stated that the quality of the hides and skins suffers from this forced drying in heated atmosphere, and that these prior methods are costly in operation and usually require expensive heating and/or conveyor apparatus ,for their practice.

It is an object of the invention to provide an improvedmethod for drying sheet material and other articles without the necessity of heating the air, and also a simple and inexpensive apparatus for practising the methods It is a further object of the invention -to secure a better product as a result of the drying operation. Y

To these ends, and in accordance wi'than im portant characteristic of the invention, the drying of sheet material and of other articlesvis secured by removing air at regular intervals from a surface or surfaces of the piece of work to be treated while at the same time leaving a'reservoir layer of moisture-containing air upon and in contact with said surface or surfaces. 'I'his Vtaken' several days in the drying loft, they are reservoir layer of air is a layer which is much less rapidly and much less 'completely changed in comparison with the air which is removed at intervals to be replaced by drier air. By this method the surface of the piece of work under- 5 going treatment remains moist throughout the early stages of the drying operation and, in even the later stages, dries but little faster than the interior portions of said piece of work. It is important that the surface of the piece ofwork 10 shall not be dried too rapidly since to do so would I interfere with, if not altogether terminate, the capillary action by which moisture is transferred continuously from interior portions of the work to the surface thereof. Hence air at ordinary 15 room temperatures is employed, and preferably never above F. Furthermore, as an important characteristic of the invention, air is repeatedly removed fromV surfaces of the piece of Work by sweeping operations performed through 20 mechanical means (analogous to a broom) distinguishable from air blowing devices as exemplifled by a fan which may be at a considerable distance from the article to be dried and bear no special relation thereto. The sweeping opera- 25 tions, as herein defined, possess distinct advantages in that they avoid direct high velocity impingement of air on any localized surface of the piece of work to be dried and indeed may be substantially uniform with respect to the surfaces of the sheet material to be dried and, further, may be selectively timed to secure the desired resuits.

Since capillary action is relatively rapidand varies little, if at all, in hides and skins of the 35 same tannage, thicker pieces of Work such as hides may be dried in substantially the same time as thinner pieces of work of the same character by supplying the requisite amount of air to take up the moisture at the surfaces of the hides. It is a fact, for instance,'that heavy hides may be dried in about the same time as thin skins, such as sheepskins. Whereas, heretofore, hides have dried in a few hours by the method herein dis- 5 closed. By the described mechanical sweeping of the air from the surface of a sheet of material there is secured a progressive and uniform drying of all parts of the article which it is impossible to obtain when excess amounts of heated air are employed in the drying, operation as in certain prior constructions. Furthermore, in the case of hides and skins, the latter are left in a verydifferent condition from hides and skins which have been 55 dried rapidly in hot air. In the latter case. asv

stated above, the hide or skin is harsh to the touch, thin, and shrunken in area. Such shrinkage is usually very marked, so much so that fastenings are often pulled from the drying board by the shrinking hide or skin. Hides and skins treated by the method herein disclosed are relatively soft to the touch, plump, and of full area, there being no tendency to shrinkage, as in hides and skins treated by prior methods. Since no heated air is employed in the treatment, the methcd is distinctly economical and easily carried out without the costly equipment now regarded as so necessary in most tanneries and in many other industries where articles of manufacture are dried.

For practising the method there is provided a simple and highly ecient machine wherein hides, skins, leather, and other sheet material may be supported in extended condition while an air removing or sweeping device is passed over the surface of the piece of work in spaced but close juxtaposition thereto to change the air at regular intervals. Conveniently the air removing device comprises a member carried by a shaft by which it is caused to sweep over the surfaces of two pieces of work spaced from each other slightly more than the width of the said member. Since the sweeper member does not contact the surface of the piece of work there is left a layer of air on the surface of the work which serves as a carrier reservoir to receive moisture by evaporation from the skin and distribute it into the adjoining air which is being periodically removed by the sweeper member. By providing a. plurality of such members upon the same shaft a large number of pieces of work may be treated simultaneously. In the illustrated construction four pairs of drying boards are mounted in spaced relation on opposite sides of, and above and below, the shaft which carries the sweeper members so that a sweeper extending crosswise of the shaft may sweep over and adjacent to the surfaces of eight pieces of work on as many drying boards during one revolution ofthe shaft.

Preferably and as shown, the sweeper members are regularly staggered with respect to each other beginning at each end of a set of such members and ending at the middle of said set of members so that the sweeper members with their carrying shaft provide two propellers, each of which tends to move the air from each end of the set of members toward the middle thereof. The purpose of this arrangement is to move air from each end of the group of drying frames toward the middle of the group where otherwise there might be some deficiency of outside air to take the place of that removed from between the drying boards at the center of the group.

In the described arrangement wherein a plurality of pieces of work on a corresponding number of drying boards are arranged for treatment by a sweeper member carried by a shaft located approximately atthe center of the space defined by said drying boards, it is important that a baille plate be provided opposite and in close juxtaposition to the vertical edges of the lower pair of drying boards on the side of the downward sweep of the air removing member, with a corresponding baille plate similarly disposed with respect to the vertical edges of the upper pair of drying boards on the side of the upward sweep of the sweeper member. The first-mentioned baffle plate has the function of restricting the amount of moistureladen air, removed from the upper pair of drying boards, which will be carried downwardly over the lower pair of drying boards on the same side of the shaft, whereas the upper baiiie plate on the side of the upward sweep of the sweeper member restricts the amount of moisture-laden air, from the lower pair of drying boards on that side; which will be carried upwardly to the upper pair of drying boards on the same side.

These and other important characteristics and features of the invention, together with novel combinations of parts, will now be described in detail in the specification and then pointed out more particularly in the appended claims.

In the drawings,

Fig. 1 is a view in front elevation (with certain parts broken away) of a drier illustrating one embodiment of the invention;

Fig. 2 is an end view (with parts broken away) of the drier in Fig. 1, looking from theright in said figure;

Fig. 3 is a detail view illustrating a modification of the air moving members;

Fig. 4 is a section through an air moving member showing also a special construction of a shaft designed to introduce air into the drier; 'I

Fig. 5 is a view of the construction shown in Fig. 4 looking from the right in the latter figure; and

Fig. 6 is a view similar to Fig. 2 but on a much smaller scale illustrating a modication of the construction.

In the drawings there is disclosed a drier, especially constructed to practice the method of drying hides and skins referred to in foregoing paragraphs, in which means is provided for supporting drying boards I0 upon which hides or skins may be spread out in extended condition, the said means comprising guideways I2 each adapted to receive one or more drying boards. As illustrated, each guideway I2 receives two drying boards placed back to back, in which case only the exposed surface of the drying board supports a hide or skin for a drying operation. It is to be understood, however, that the guideways I2 may be constructed to receive only one drying board adapted to support a hide or skin on each surface thereof. In the illustrated drier, four sets of guideways I2 are provided, the arrangement being such that the drier may be loaded by introducing the drying boards by sliding them along the guideways I2.

As shown most clearly in Fig. 2, a shaft I4 is provided substantially at the central longitudinal axis of the drier, the said shaft I4 having secured thereto, in regularly spaced relations to `each other, a plurality of air moving or sweeper members or arms I6 so spaced with respect to the guideways I2 as to have the side edges of said sweeper members equally'spaced from the drying boards as said arms pass between the drying boards during rotation of the shaft I4. It will be clear that during rotation of the shaft I4 the members or arms I5 will be caused to sweep air from over l:he surfaces of the hides or skins on the drying boards I0 and that this sweeping of the air from the space between two adjacent skins takes place intermittently as the member or arm passes in succession through the spaces between four different pairs of drying boards. While in the illustrated construction the shaft I4 is rotated at a rate of 96 revolutions per minute, it will be imderstood that this rate of rotation may be varied to suit conditions depending upon such factors as the amount of moisture in the skins as originally introduced into the drier and the amount of moisture in the a'ir supplied to the drier. For instance, the rate of travel of the sweeper members may advantageously be higher than 96 R.. P. M. when the hides or skins are first introduced into the drier, and less than that number during the last hour or so of the drying operation thereby securing more uniform results.

Upon inspection of Fig. 2, it will be observed that the guideways I2 are so constructed that the drying boards I are limited in their approach to each other in a horizontal direction both above and below the shaft I4. This is to leave a space I8 above and below said shaft through which air may enter the drier to take the place of air which is swept from the spaces between the drying b oards. The arrangement is preferably such that air also enters the drier from above since the top of the drier is open, thus permitting warm dry air to enter the drier from the upper part of the room or from an air shaft (not shown).

If desired the shaft at the center of the drier may be constructed as a tube 20, as shown in Fig. 4, in which case said shaft 20 will be provided with openings 22 through which air may escape into the drier, it being understood that, in such a construction, means may be provided (such as a'blower, not shown) for forcing air through the tubular shaft 20 so that it may escape through the openings 22 located in the plane of the air moving members or arms I6. Since the arms I6 when inoperation cause the air to be discharged outwardly away from the center of the drier, due to centrifugal action, the introduction of dry air at the center of the drier will facilitate the drying operation.

In the illustrated construction baille plates are provided to control the entrance of air into the drier, said baiiie plates being shown at 24 and 26 in Figs. l and 2. The baffle plate 24 is provided in order to limit the amount of moist cool air, from skins in the spaces between the drying boards in the upper left quadrant of the drier (Fig. 2), that shall be received by the spaces between the drying boards' in the lower left quadrant of the drier. It jis to be understood that the baiile plate 24 does not prevent the entrance of any air from above into the last-mentioned spaces, but it prevents entrance -of air from the lower part of the room where there collects cool moist air that has come from the' drier and more immediately from the skins in the upper quadrant on that side of the drier. To provide for a more adequate supply of air to the drying boards in the lower left quadra-nt of the drier (Fig. 2), the bafiie plate at this portion of the drier may be displaced outwardly, as shown at 28 in Fig. 6, in which case the drier has an inlet for air open equally to all the drying boards. Air may be drawn into the lower left quadrant of the drier'from each end of the relatively large space provided by said baille plate 28 and by an inclined member 30. The inclined member 30 serves to direct moist air from the skins in the left upper quadrante/ofY the drier in an outward direction and to prevent it from entering the space below said inclined member 30 until it has become diffused fairly widely with other air in the room. In a similar manner the baffle plate 26 (Fig. 2) is intended to restrict the amount of moist air from the spaces between the drying boards in the lower right quadrant of the drier in Fig. 2 which shall enter into the spaces between the drying boards in theupper right quadrant of the drier (Fig. 2)

the arrangement being such that air from the spaces between the drying boards in the lower right quadrant of the drier will be projected by centrifugal force into the room space at the right of the drier and will be prevented in large degree from moving upwardly with the moving arms I6 because of the bafiie plate 26. To provide for a more adequate supply of air to the drying boards in the upper right quadrant, a baille plate 3 2 (Fig. 6) may be utilized in place of the baffle plate 26 in which case air may enter into the spaces between the drying boards equally from above and from each end of the drier into the space above the baffle plate 32, the baffle plate 32 being held in position by one or more braces like that shown at 34 in Fig. 6.

To facilitate movement of air into the drier through openings I8, the sweeper members I6 are arranged in sets wherein the members are regularly staggered with respect to each other beginning at each end of the set and ending at the middle thereof in a helical arrangement. See in this connection Figs. 1 and 2 of the drawings wherein corresponding members I6 have been indicated by reference characters a, b, c, etc. and a', b', c', etc. The effect of the described arrangement is that of a blower by which air is conducted from the openings I8 at each end of the drier to the middle portion thereof. Hence the central portions of the drier receive substantially as much fresh air as those portions near to the ends of the drier.

Upon reference to Fig. 1 it willbe observed that the sweeper members or arms I6 are spaced a slight distance from the surfaces of the pieces of leather on the drying boards I0. In other words, the members or arms I6 sweep rather closely to the surfaces of the skins on the drying boards. If desired the members I6 may be made wider to remove a greater'body of.v air from the space between adjacent hides or skins. This may be conveniently accomplished by` attaching a strip of canvas or other flexible material to each member I6, the said flexible material projecting beyond the edges of the members I6 to sweep closer to the surfaces of the pieces of leather undergoing treatment. Where a piece of canves 40 (Fig. 3) is used, it may be so constructed and arranged as to leave a fringe 42 of loose threads along each horizontal edge. By this construction, the spaces between the drying pieces of leather may be almost entirely bridged by the members I6 with their canvas strips 40. By having the edges of the canvas frayed to provide the loose threads 42, there is eliminated any possibility of injury to the surface of the leather should the latter for any reason project into the space between the drying boards, as might happen in case of some slight warping of a drying board. At the same timefalmost all of the air in the space between two adjacent drying boards will be swept from said space, thus hastening the drying operation, since the latter is dependent to a large extent upon the rapidity with which air is removed and less .saturated air supplied to the surfaces of the leather undergoing treatment.

While the sweeper members I6 of the drier are shown in Figs. 1 to 5, inclusive, as consisting of straight or fiat bars, it will be understood that these members may be of a different formation. For example, the sweeper arms may be of a curved shape with the convex portion thereof facing in the direction of rotation of the carrying shaft, all as shown in connection with sweeper arms I) in Fig. 6 of the drawings. It is believed that these arms 50 will have the eifect of ejecting the air from the drier more eiliciently than the straight or flat arms shown in Fig. 2 of the drawings, through a greater 'centrifugal action on the air in the spaces between the drying boards.

In some instances, pieces of. leather are secured to the drying boards I0 without use of staplesv or other fasteners.v In such cases the leather may tend to separate from the drying board in the later stages of the drying operation. If such should occur, the separated portion would be struck by the rotating sweeper I6 and eventually the whole piece of leathervwould be thrown from the drier or, alternatively, folded in such a way as to clog the machine and cause damage to the ntating arm. As a matter of precaution I may p ovlde a screen, such as that shown at 52 in Fig.- 2 of the drawings, covering a portion of the surface of the leather to retain the leather in a plane at one side of the sweeper arm. Such a screen, if used, will be secured to the guideways I2 over approximately one-half of the area of each drying board, the part covered being that first reached by the sweeper arm in its rotation past said drying boards.

In the operation of the drier,. the hides or skins to be dried are flrst spread out in their slicked-out condition upon drying boards l0 which are then introduced into the machine by sliding them along the guideways l 2. Upon starting the shaft I4 (or shaft 20) in rotation, the members I6 are caused to sweep over the surfaces of said hides or skins on the drying boards, rotation of the shaft being continued until the skins are dried.

During the operation of the machine, air is swept from over the surface of each piece of leather undergoing the drying operation and dry or unsaturated air is supplied to take the place of that removed. In the illustrated construction the sweeper members move intermittently over the surfaces of the leather to remove air which has received moisture from a reservoir layer of air in contact with the leather. 'I'his reservoir layer of air receives water vapor from the leather by evaporation from the surface of the latter. From another viewpoint, the reservoir layer of air on the surface of the leather may be regarded as a layer which is substantially less rapidly and less completely changed in comparison with the layer of air which is swept away by the sweeper member. Hence the reservoir layerof air contains more `moisture which it receives by evaporation from the surface of the leather and which it passes cn by diifusion to the next adjacent-layer of air which is repeatedly removed in the described sweeping operations.v The rate of removal of the air should be such as to secure the maximum evaporation without drying the surface, since if the surface were to become dry it would. interfere with capillary action which brings the moisture within the leather to the" surface thereof. Hence, the timing of the sh'aft carrying the sweeper members should be determined by reference to the moisture content of the air supplied to the drier and of the leather at the time of its introduction into the drier. In general the drier the air the less is the speed of the sweeper members over the leather.

It is contemplated to introduce dryair into the room where the drier is located by air ducts (not shown) located along the ceiling of the room, the top of the drier being open equally to all the drying boards in the upper quadrants of the drier.

Since the air which has taken up moisture from the hides or skins is also cooled in that operation, it drops to the bottom of the room and hence the system of air circulation includes means (not shown) to effect removal of the saturated air from a point at or adjacent to the floor of the room.

Having described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. That improvement in methods of drying hides and skins which comprises mechanically sweeping from a surface of a hide or skin a layer of air in close juxtaposition to said surface, at the same time leaving a reservoir layer of air of substantially uniform thickness on said surface, permitting other air to ilow in over the said surface to become diffused with said reservoir layer of air, and repeating the sweeping operations at regular intervals until the hide or skin is dried to the desired degree.

2. That improvement in methods of drying hides and skins which comprises mechanically sweeping from a surface of a hide or skin a relatively thin layer of air in close juxtaposition to said surface, supplying other air at ordinary room temratures, and timing the repetition of the sweeping operations at such intervals that the surface of the hide or skin is not dried much more rapidly than the internal portions thereof.

3. That improvement in methods of drying hides and skins which comprises mechanically sweeping from a surface of a hide or skin a relatively thin layer of air in close juxtaposition to said surface, at the same time leaving a substantially uniform reservoir layer of air on said surface, and supplying other air of a temperature not above about 100 F. to become diffused with said reservoir layer o'f air.

4. That improvement in methods of drying hides and skins which comprises supporting two' hides or skins spread out upon drying boards arranged in parallel spaced relation, mechanically sweeping air from the space between the hides or skins on their respective drying boards, at the same time leaving a thin substantially uniform reservoir layer of moisture-containing air on the surfaces of the hides or skins, supplying other air to ilow in over the said reservoir layer to reduce the moisture content thereof, and repeating these operations with air at ordinary room temperatures.

5. In a drier for sheet material, a plurality of pairs of supports for sheet material arranged in parallel spaced relation, each support being adapted to support sheet material in substantially fiat condition, and sweeper members of a width less than that o'f the space between the sheet material on two adjacent supports and movable through the spaces between said supports to remove layers of air from between the pieces of sheet material on said supports, the drier being open at one side with the spaces between the supports communicating directly with the outside air so that air may enter said spaces in a uniform manner, and said drier being open at another side with said spaces communicating directly with the outside air so that air may escape directly from said spaces in a uniform manner during operation of said movable sweeper members.

6. In a drier for sheet material, a plurality of pairs of work supports arranged vertically 'in spaced parallel relation, said work supports being adapted to have sheet material attached thereto in substantially at condition, and sweeper members movable repeatedly between said pairs of work supports to remove at each stroke a layer of air of substantial thickness from the space between each pair of said work supports, the drier being open at the top side equally over all the vertically arranged work supports so that air may directly enter the spaces between all the work supports in a uniform manner, and said drier being open at another side equally with respect to all the Work supports so that air may escape directly and uniformly from said spaces during the operation of said movable sweeper members.

7. A drier for sheet material comprising an enclosure adapted to receive supports for sheet material arranged in spaced parallel relation, each support being adapted to support sheet material in substantially fiat condition, and a` plurality of sweeper members each movable in the spaces between adjacent supports to remove a layer of air closely adjacent to the surfaces of the sheet material-on said adjacent supports, said drier having an inlet and an outlet communicating direct.- ly with each of said spaces for the admission and escape of air directly to and from said spaces during the operation of said sweeper members, whereby the sheet material on all the work supports receive uniform treatment.

8. A drier for sheet material comprising an enclosure adapted to receive a support for sheet material upon which the latter is spread out in substantially at condition, a rigid member movable over the surface of the sheet material. on said support in spaced relation thereto, and a strip of flexible material secured to said rigid member and extending into close juxtaposition to said surface to remove a layer of air closely adjacent to said sheet material whereby other air may flow in to take the place of that removed.

9. In a drier for sheet material, a shaft, a plurality of pairs of spaced parallel work supports at one side of said shaft, a like number of pairs of similarly spaced parallel work supports on the otherside of said shaft, each work support being adapted to have sheet material attached thereto in substantially fiat condition, a plurality of sweeper members operated by said shaft, each sweeper member being arranged to move in the spaces between the opposed work supports of two pairs of work supports similarly placed on opposite sides of said shaft, and'means to cause said shaft to move said sweeper members repeatedly through the spaces between the work supports, whereby air is repeatedly removed from such spaces and other air allowed to take its place, said drier having an inlet and an outlet communicating directly with each of said spaces for the admission and the 'escape of air directly4 to and from said spaces, whereby the sheet material on all the work supports receives uniform treatment.

10. In a drier for sheet material, a shaft, a plurality of sets of spaced parallel guideways at one side of said shaft adapted to receive portable work supports, other sets of spaced parallel guideways on the other side of said shaft also adapted to receive portable work supports, each work support being adapted to have sheet material attached thereto in substantially at condition, a plurality of sweeper rmembers each of 'awidth less than K that of the spacebetwee'rrwerk supports on two adjacentguideways and operated by said shaft to move' in the spaces between the work supports and in spaced relation to the surfaces of said sheet material, said members being arranged in 'staggered relation on said shaft, and means to rotate said shaft whereby said sweeper members arel work supports and to permit other air to take the place of the air' thus removed.

11. In a drier for sheet material, a shaft, a pair of spaced parallel work supports arranged at one side of said shaft and substantially at al right angle thereto, a like pair of similarlyspaced parallel work `supports arranged in like manner on the other side of said shaft, each work support being adapted to have sheet material attachedthereto in substantially flat condition, a member operated by said shaft to move in the space between the work supports of each pair and in spaced relation to the surfaces of the sheet material carried by said work supports, means to rotate said shaft whereby said member is caused to sweep over the surfaces of said sheet material on the work supports at regular intervals to remove air from between said work supports and to permit other air to take the place of the air thus removed, and two baffle plates spaced from each other a distance greater than the combined width dimensions of the two pairs of work supports and arrangeddiagonally opposite to veach other on opposite sides of said shaft, each baille plate being arranged to extend across the corresponding edges of a pair of work supports substantially at right angles to the work supporting surface thereof, thereby to form a wall along said edges of the work supports.

12. In a drier for hides, skins, leather and other similar pieces of work, a horizontal shaft, four pairs of drying boards located on opposite sides of said shaft and above and below a line passing horizontally through said shaft, each drying board being adapted to carry a piece of work in ilat condition on a surface thereof, the drying boards of each pair being in spaced parallel relation to each other with the boards of the four pairs arranged in two planes dened by the boards of any given pair, a member secured to said shaft and movable in the spaces between the drying boards of each pair in spaced relation to the pieces of work on said drying boards, and means to operate said shaft whereby said member iscaused to remove air at regular intervals from said spaces and to permit other air to take the place of the air thus removed.

13.' In a, drier for hides, skins, leather, andother similar pieces of work, a horizontal shaft, four pairs of drying boards located on opposite sides of said shaft and above and below a line passing horizontally through said shaft, each drying board being adapted to carry a piece of `work in boards of each pair in spaced relation to the pieces of work on said drying boards, means to rotate said shaft whereby said member is caused to remove air at regular intervals from said spaces and to permit other airto take the place of the air thus removed, a baille plate extending across the outside edges of the lower pair of drying boards on one side of said shaft, and another baffie plate extending across the outside edges of the upper pair of drying boards on the other side of said shaft. l

14. In a drier for hides, skins, leather, and other similar pieces of work, a plurality of drying boards spaced from each other and in parallel relation, each board being adapted to carry a piece of work in fiat condition on a surface thereof, a shaft extending across the edges of said drying boards, a plurality of members operated by said shaft, each member being arranged to pass between two adjacent drying boards to sweep over the surfaces of the pieces of work on the drying boards in spaced relation thereto, and means to rotate said shaft, said members being attached to said shaft in regularly staggered relation beginning at or adjacent to each end of said shaft and extending toward the middle thereof.

15. In a drier for hides, skins, leather, and other similar pieces of work, a shaft, a plurality 'of pairs of drying4 boards located in parallel planes upon opposite sides of said shaft, each board being adapted to carry a piece of work in Iflat condition on a surface thereof, members secured to said shaft and so arranged that each drying boards at regular intervals to remove air from the spaces between said drying boards, said shaft being tubular and having openings therein whereby air may be directed into the spaces between said drying boards from said tubular shaft. 16. In a drier for sheet material, a pair of work supports arranged in spaced parallel relation, each work support being adapted to have sheet material secured thereto in substantially flat condition, a rigid member movable between said work Supports substantially equidistant therefrom, and a strip of flexible material secured to said rigid member and having portions extending into close juxtaposition to the surfaces of said sheet material on the work supports, the arrangement being such that the member with its exible material removes almost all of the air from between the two drying boards as it is moved along therebetween, the flexible material serving to assist in removing air without danger of injury to the exposed surfaces of said sheet material.

M. MERRI'IT.

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