US2027317A - Tenter drier - Google Patents

Description

79 i936@ n F. B. MORRlLL gmg? TENTER DRIER Filed Aug. 16, 1952 v2 Sheets-sluwe?I l f INVENTOR.

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vm 79 l@ F. 'B MORRHLL www TENTER DRIER Filed Aug. 16, 1932 2 Sheets-Sheet 2 IN VEN TOR.

Patented Jan. 7, 1936 UNTED STATES .ETENT OFFICE TEN'EER BRIER Application August le, i932, Serial No. 629,009

12 Claims.

The invention relates to driers for sheet material inl general, and has special application to driers in which the sheet material is moved through an enclosure having provision for heating and circulating the air therein, while the material is held by hooks or clamps or other devices gripping its marginal edges to hold it in distended relation, of which arrangement the tenter driers used for simultaneously stretching and drying textile fabrics comprise typical examples.

With the object of improving the operation of such apparatus both through increasing the rate of drying or the sheet material and avoiding the undesirable and harmful effects on the material and the increased cost or" operation hitherto involved in all prior known ways of increasing the average rapidity of drying, the invention involves in its broadest aspect the use of an air stream directed over the sheet material to induce a movement of the air at the proximate surface of the material away from the said surface, so that the water vapor or other fluid vapor evolved from the sheet material will be given off and carried away at a higher rate than hitherto attainable. Additionally, the invention also includes the withdrawal of air from the opposite surface of the material, so that the air is likewise moving away from this surface also, resulting in the reduction of the air pressure Aat both. sides oi the material appreciably below the average atmospheric pres-` sure existing within the drying enclosure, or in other words, creating a negative pressure at both surfaces of the material being dried. In its preferred form' the invention is carried into effect though discharging air in jets or sheets over one surface of the material at a velocity high enough to induce and aspirato a iiow of air away from the proximate surface, allowing the air thus impelled and aspirated to pass around the iar edge of the material and withdrawing it from the opposite surface of the material through suction side or" the air-impelling devices used, whereby a continuous circulation may be attained with the economies resulting therefrom.

.Additional features or the invention include the provi n of heaters for the air used to absorb and ry oii the vapor from the fabric, which heaters are arranged the suction instead or the discharge streams of the air-impelling 7ices, so that the essential momentum of the ning air blasts will not be diminished, and h are removed from their usual position nded along one margin of the traveling material and are placed edgewise to such margin, providing an unobstructed course for the air discharged from the air-impelling device, or for the leaders carrying such air, directly from the impeller, ian, or blower into the spaces between the several runs of the material being dried. The ar- (Cl. 34e-48) rangement ci the heaters to extend edgewise to th direction of travel of the material additionally maires possible the use of screens immediately in the heaters in the path of travel of the air entering the heaters, whereby the lint coming from the material being dried and eventually gathering into bunches at various points and especially on oily parts within the enclosure cannot be carried into the heater when dislodged and carried along by the air stream, thus effeetually preventing the creation of a decided lire. hazard and the spotting of the sheet material through deposit or" the bunches of lint or other dirt thereon with resultant oil-staining or incomplete drying, or both, at the spots thus covered. Further, such arrangement of the heaters errnits the screens to extend edgewise to the path of travel of the material, whereby they may be easily reached by a person standing outside the enclosure and slid out edgewise for the purpose ci stripping the accumulated lint therefrom, and may similarly be replaced without having to enter or open the not enclosure,

Other aims of the invention, and the manner in which they are carried into eiect, are as will appear hereinafter.

Illustrative embodiments of the invention are shown in the accompanying drawings in which:-

Fig. l is a side elevation of a tenter drier ernbodying the invention, with certain of the side panels forming a portion of the housing removed to show the general arrangement of the blowers, heaters, and screens.

Fig. 2 is a vertical section on line 2-2 of Fig. l.

Fig. 3 is an enlarged side elevation of one of the three sections which go to make up the length of t e drier of Fig. l.

Fig. 4 is a plan view of the parts of Fig. 3, showing the parts as far inward as the line of travel of the material, and also showing the panels forming the adjacent side or" the housing 'm their operative relation.

The tenter drier in which the invention is illustratively embodied is of a familiar type used for stretching and drying fabrics and is in general the same in construction and manner of operation as that shown and described in my copending application filed August l0, 1931, Serial No. 556,154, except where speciiically described as otherwise, and comprises a housing indicated generally at i through which extend two endless traveling chains one of which is carried in stationary guides or tracks 3 and the other in guides or tracks 5 mounted on a framework l movable toward and from the opposing chain guides to suit the width of the fabric being stretched and dried, both chains being similarly directed in successive zigzag and parallel runs bak and forth throughout the length ci the housing, changing their direction sprockets at the end of each run.

Each chain is provided with a great number of tenter pins or clamps 9 on which the margins of the cloth are impaled or otherwise fixed, so that the cloth is tightly stretched widthwise while passing through the machine in a series of spaced and parallel runs in which the cloth travels successively in opposite directions.

The interior of the housing is divided vertically into three drying stages in which different conditions of heat and moisture may be maintained, the divisions being effected by horizontal baffles II, I3, extending the full length of the runs of the cloth, but `spaced apart as shown along approximately the middle line of the housing to provide for passage of the air from one stage upward into the stage immediately above. At the bottom, a single baiiie I5 extends partway across for the length of the lowest or outgoing run of the fabric, to define a cooling chamber wherein the fabric is cooled before being discharged from the enclosure, being subjected in this chamber to the cooling effects of fresh air entering through a series of ports I1 along the length of the machine, which entering fresh air serves to make up for the amount of saturated air discharged from the hot or Wet stage at the top of the machine through the exhaust port, such discharge being either natural or induced around by a fan, as desired.

Several runs of the fabric in each of the three drying stages serve to define sub-divisions or chambers which are each closed at one end by a cylinder around which the cloth makes its turn and at the other end by a bafile located between two such vertical adjacent cylinders, as shown in my companion application aforesaid, and these chambers of each stage all communicate with each other at the side where the movable frame is located, as indicated in Fig. 2. The chambers between the two top runs of cloth in each stage, and between the two bottom runs of cloth in the intermediate and bottom stages, are closed at the side away from the movable frame I by Vertical baffles 2l which extend for the full length of the runs of cloth, and through the top and bottom edges of each of these baiiles there extend at frequent intervals the horizontally-disposed long narrow nozzles 23 which form the discharge ends of leaders 25 in connection with the housings 21 surrounding the rotors 29 of a plurality of fans or blowers mounted at intervals as desired along the iength of the several stages. Three blowers are located one to each stage on each of the two vertical fan-shafts 3i arranged in each section of the drier, the pair of fan-shafts in each section being driven through pulleys 33, 35, and intermediate belts 3.' from a single electric motor 39, this being a convenient arrangement and not restrictive.

The blowers of each stage are enclosed in an air-chamber located at one side of the path of the traveling cloth, and dened on the top by the baflies I3, (except in the case of the hot or top stage, where the housing I forms the top wall), on the bottom by baiiies 4I which are slightly shorter in the direction of the travel of the cloth than each of the three sections comprising the length of the machine, on the side toward the cloth by vertical baiiles 43 coextensive with the bottom bailies 4I and through which protrude the leaders 25 on their way to the nearby margin of the cloth, and on the side away from the cloth by the removable panels 45 forming a part of the housing along this side of the machine. As is customary, these panels are held in place against the vertical frames 41 of the machine by means of turnbuttons 49 and nuts 5I. In the two open ends of each air-chamber or fan-chest as thus 5 defined are located the heaters 5S, comprising steam pipes equipped with radiating fins 5T. As shown, the pipes extend at right angles to the path of the cloth, so that the direction of extent of each heater as a whole is transversely 10 with respect to the path of the cloth, though it is contemplated in certain instances to dispose the heaters otherwise, so long as they be kept out of the path of the air discharged from the blowers. The path of the air in entering and leaving the l5 air-chamber is as shown by the arrows in Figs.

2, 3 and 4.

Screens 59 are provided across the path of the air drawn through the heaters 53 by reason of the action of the fans. Being disposed across the 20. only openings into the fan-chests, the lint and dirt which accumulate at points in the drier and are subsequently dislodged to be picked up by the air streams cannot find entrance to the heaters, nor can it reach the blowers to be discharged on 25 to the fabric. The screens are slidably mounted in guides 6I at top and bottom of the open ends of the fan-chambers, extending through vertical slots 62 in the panels 45; the handles 63 on the vertical outward ends of the screens are easily 30 accessible and the screens may be withdrawn from the machine for cleaning and returned into operating position with the utmost ease and without need to get inside the hot machine for this purpose. This cleaning operation being 35 greatly simpliiied, it is more frequently performed, with resultant benefit in the operation of the machine.

As shown in Fig. 2, throughout the three stages and with the exception of the extreme L top and bottom runs of thecloth, each clothdened chamber into which the nozzles 23 discharge is fianked above and below by suction chambers, that is, chambers which are in com- A munication with the suction side of the blowers. 2') Thus, the air discharged from the nozzles 23 between two runs of the cloth passes around the far edges of these two runs and returns under or over the nozzles and the long narrow vertical panels 2| and around the ends or under the bottom edge of panel 43 to the intake side of some blower in its own stage, passing through a screen 59 and being reheated in its passage through the adjacent heater 53 before being again impelled by such blower out through the nozzles 23. Owing to the natural tendency of heated air to rise, a certain amount of the air circulating in the two lower stages rises through the longitudinal passage between the confronting ends of the baies II and I3 defining these stages and enters the air-chambers of the stage above; this action is made possible and induced by the escape or withdrawal of air from the top stage through the port I9. Through the accompanying ingress of fresh air through the port Il, the air is kept from being harmfully reduced in its power to absorb fluid vapor from the fabric, and the average pressure within the machine can remain substantially the same as that of the atmosphere outside.

As also shown in Fig. 2, the entering or top most run of the fabric is subjected to the action of blasts of heated air projected over both surfaces of the cloth, the extra nozzle 35 being dis- 76 posed immediately above the fabric and having a slightly greater capacity than the narrower nozzles 23 used elsewhere. This is for the purpose of warming up the cloth thoroughly immediately upon its entry into the machine, to increase the rapidity of evolution of water vapor. A portion of this topmost blast which acts upon theA cloth when the latter is in its wettest condition is discharged from the housing through port end to end in the length of the machine, in a thin sheet traveling at fairly high velocity across and substantially parallel to the plane of this proximate surface of the fabric. The requirement is that the air thus discharged shall move over the adjacent surface of the cloth with sufcient momentum to entrain or aspirate the air lying closely adjacent to the proximate surface of the cloth, so that this latter air will be induced' to follow the path of the high speed jet and move away from the surface of the cloth, rather than along or through such surface. The condition created is exactly the opposite to that vexisting in prior driers in which the air from the circulating blowers was merely discharged in uncontrolled manner between two adjacent runs of the material; in such prior structures the air blast exerted a positive pressure on the two proximate surfaces of these runs of fabric which caused them to belly away from the line of the blast, frequently forcing the two runs of cloth apart so violently as to liftor tear their margins from the tenter pins, this possibility limiting the volume and velocity of the air which could be used; whereas in the present machine the two adjacent runs of cloth between which the blasts are introduced in sheet form belly toward each other and toward the path of the blasts passing over them, taking the form indicated in dotted lines at 63, Fig. 2, with even the lower of the two adjacent runs bowed upward toward its associated blast against the force of gravity, and establishing the fact that the air pressure at the proximate sides of these two runs is reduced below that at the opposite surfaces of these two runs, even though the air at such latter surfaces is at less than atmospheric pressure owing to the suction of the blowers. By the present arrangement is attained the novel result of reducing the air pressure at the surface of the cloth below that of the average air-pressure in the enclosure through blowing over it a stream of air which is itself discharged at greater than atmospheric pressure. The momentum of the moving sheet of air causes the cloth to belly toward this moving sheet and probably to enter into contact with the moving air stream, and apparently to assume a streamlined form conforming to the lines of flow. This streamlined form, as is well known, gives rise to enhanced suction effects, where such form is subjected to a moving current of air, and the forces representing such suction are directed away from and at substantially right angles to the convex side of the arched surface throughout the greater part of its length.

By reason of these phenomena, or for other reasons, the air pressure at the proximate surfaces of the two runs of cloth between which the blasts are introduced is reduced appreciably below that which would otherwise exist within the interior of the housing, which through being in communication with the surrounding atmosphere through the exhaust. port I9 and the make-up air port l1 may be considered on an average to be of substantially atmospheric pressure. This reduction in the air pressure below that of the surrounding atmosphere, or negative pressure, is created at both surfaces of each of the two runs of cloth in question, as noted, but is appreciably greater at the surface of each run of cloth which is toward the sheets of moving air, as witnessed by the inward bellying of the cloth; the relative difference of the suction has been found to be on the order of 40% greater at the convex surface than at the concave surface, under certain conditions. A very decided negative pressure has been found to exist between the planes of the two adjacent air sheets expelled under pressure from the two vertically-separated lines of nozzles 23.

'I'he practical result of the working of the novel arrangement is that the cloth is dried with a rapidity and thoroughness hitherto unattainable through commensurate expenditures of heat and mechanical energy. Through the efficiency of the machine, the cloth can be dried rapidly at temperatures well below those at which similar prior machines have tobe operated in order to attain a commercially practicable rate of output; the result in the improved machine is that the cloth is put out in better physical condition and free from harshness and other undesirable characteristics familiarly resulting from drying at high temperatures, The cloth dries evenly across its entire width, so that dyes will take evenly across its full width, as distinct from the characteristic result in prior devices of drying the selvages while the midwidth of the fabric remained wet, resulting in injurious shading of the cloth. The increased efficiency of the improved drier can be understood in view of the well-known fact that the reduction in the barometric pressure of air of a few hundredths of an inch of mercury results in a marked increase in the rate at which wat-er vapor is given oif into the air, especially when it is considered that the present arrangement produces a negative pressure at both surfaces of the clo-th in place of the older arrangement of a negative pressure at one surface and a very decided positive pressure at the other, and that the improved machine not only cancels the positive pressure at the side of the cloth that is toward the blast, but goes farther and substitutes a negative pressure or suction at this surface, Another factor is that fresh air at full atmospheric pressure is continually entering the machine, while similarly the saturated air is co-nstantly being discharged through port le at the top of the machine at full atmospheric pressure and hence with its maximum moisture-carrying capacity substantially undirninished. The novel arrangement is free from the fault of blowing the cloth from off the tenter pins, referred to, and no adverse result limiting the pressure or volume of air blown o-ver the fabric has been found.

While I have illustrated and described certain forms in which the invention may be embodied, I am aware that many modifications may be made therein by any person skilled in the art, without departing from the scope of the invention as expressed in the claims. Therefore, I do not wish to be limited to the particular forms shown, or to the details of construction thereof, but what I do claim is:-

1. A drier for sheet material having in combination a blower impelling an air-stream under pressure, means maintaining the material in position, and wide thin nozzles in proximity to the material directing the air-stream at high speed transversely over the proximate surface of the material so as to diminish the effective air-pressure adjacent this surface of the material throughout an area traversed by such air-stream.

2. A drier for sheet material having in combination material-supporting means engaging the cloth at spaced points in its area, devices taking air from one surface of the material and discharging it over the opposite surface, and airdirecting means disposing the material so as to have the form of an arch extending in the direction of air travel with its convex surface toward the discharged air-stream.

3. A drier for travelling sheet material having in combination a drying compartment for the material, an air-chamber alongside the path of travel of the material, and in communication with the air surrounding the traveling material through its nds which are spaced apart lengthwise of the traveling material, screens covering the air-passages in such ends and disposed perpendicularly to the traveling material in two dimensions and at right angles to the compartment wall for quick removal, a blower discharging air from within the chamber over the material, and

Y heaters interposed between the screens and the blower.

4. In a drier for sheet material, in combination, air-impelling means, means holding the material stretched widthwise in spread-out relation, nozzle means directing a stream of air from the impelling means over the sheet material in a manner aspirating the air at the proximate surface of the material obliquely away from the plane of the said surface, and means preventing air from beyond the extent of the surface of the material from being drawn over the surface by such stream of air.

5. In a drier for sheet material, in combination, air-impelling means, means engaging the margins of the material and holding the material in spread-out relation, and wide thin nozzles directing a stream of air exceeding in its pressure the air-pressure at the proximate surface of the material, over the said surface so as to induce a movement of the air at this surface obliquely away from the plane of such surface and a movement of the material toward the stream of air.

6. In a drier for sheet material, in combination, air-impelling means, means positively supporting and transporting the damp material in spread-out relation, means directing a stream of air from the impelling means over the sheet material at high speed and in spaced relation thereto to induce a movement of the air at the proximate surface of the material away from the said surface, and means preventing air from beyond the extent of the surface of the material from being drawn over the surface by such stream of air.

7. In a drier for sheet material, in combination, air-impelling means, means positively supporting and propelling the damp material in spread-out relation, and nozzles delivering air from the impelling means in thin sheets at high velocity over the surface of the material and substantially parallel to the plane thereof and in spaced relation to the surface,'in such manner and with such momentum as t aspirate the air lying adjacent the surface into the path of the delivered air and away from the surface of the material.

8. A drier for sheet material having in combination means maintaining the material in position in expanded sheets of single thickness, means for withdrawing air from one surface of the material, and means in proximity to the material directing a thin sheet-like high-speed stream of this air under pressure transversely over and parallel to the other surface of the material to reduce the average air-pressure against such latter surface below that existing at the rst named surface.

9. A drier for sheet material having in combination means maintaining the material in position in expanded sheets of single thickness, and means in proximity to the material directing a thin sheet-like high-speed stream of air under pressure transversely over and parallel to the surface of the material so as to produce a negative air-pressure over the greater part of the area traversed by such stream at the surface of the material that is adjacent the air-stream.

l0. A drier for sheet material having in combination a housing, tenter chains propelling the material through the housing and maintaining the material in fully expanded sheets through engagement at spaced points in its length, and means in proximity to the material creating and directing a thin sheet-like high-speed air-stream transversely over the material in substantially spaced and parallel relation thereto so as to tend to draw the material and the air at the surface thereof toward the air-stream throughout the greater part of the area traversed by the airstream.

11. A drier for sheet material having in combination a casing, a blower circulating air in the casing, tenter chains disposing and propelling the material in a fully expanded sheet with one surface exposed to the suction of the blower, and nozzle means in proximity to the material directing the air discharged by the blower transversely over and parallel to the opposite surface of the material in a thin sheet-like high-speed stream so as to reduce the average pressure at the latter surface below the average pressure at the first mentioned surface.

12. A drier for sheet material having in combination a casing, travelling means carrying the material therethrough in spaced and parallel runs, a blower discharging air between two successive runs of the material, and nozzle means dividing the blast of the blower into thin highspeed spaced sheets disposed fiatwise with relation to each other and entering between the said two runs in non-impinging direction with respect to the latter.

FRANK B. MORRILL.

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