US3681853A

US3681853A - Dryer for sheet material

Info

Publication number: US3681853A
Application number: US124334A
Authority: US
Inventors: Norman C Reid
Original assignee: Pako Corp
Current assignee: Pako Corp
Priority date: 1971-03-15
Filing date: 1971-03-15
Publication date: 1972-08-08
Anticipated expiration: 1989-08-08
Also published as: CA943758A; FR2129660A5; DE2212583A1; NL7202813A; IT952242B; GB1384624A

Abstract

This is a dryer for sheet material such as photographic prints and film which is particularly constructed to handle individual relatively large size prints and includes a walking beam transfer mechanism for transporting the sheets through the drying chamber with means for circulating warm air around and over the surfaces of the prints being dried in a manner to reduce the tendency of the sheet material to curl.

Description

United States Patent [151 3,681,853

Reid 1. Aug. 8, 1972 [54] DRYER FOR SHEET MATERIAL v 3,47l, 1 34 'lO/ 1969 Cone ..263/6 A i [72] Inventor: Norman C. Reid, Minneapolis, i I

Minn. Primary Examiner-Carroll B. Dorlty, Jr.

' 1 At --J h W. Ad [73] Assignee: Pako Corporation, Minneapolis, mmey n 4 mm v 57 ABSTRACT Wed: March 1971 This'is a dryer for sheet material such as photographic [21] Appl. No.: 124,334 prints and film which is particularly constructed to handle individual relatively large size prints and in- 52 us. Cl ..34/1s1 263/6 A dudes Walking beam transfer mechanism trans 51 Int. Cl ..F2 6b 13/00 Porting the Sheets through the drying with [58] Field of Search ..34/ 148, 151, 155, 162; means for circulating warm air around and Over the 2 3 E, 6 A surfaces of the prints being dried in a manner to reduce the tendency of the sheet material to curl.

[S 6] References Cited g UNITED STATES PATENTS I 5 Claims, 6 Drawing Figures 2,907,118 10/1959 Maescher ..34/ 155 i 33 33 :/L; v oflla'Tfl'lm'ni'dlg" C ,z 2 2 23 u 22 h l 29 3 E' M I? l f r E s l2 g 3/ I 2'6 25 j I: T T T 32 I i ::l l V -'t l H v 6i! int, l I q \1 /l DRYER FOR SHEET MATERIAL It has long been a problem in the drying of photographic prints and film to provide drying apparatus for individual separate sheets which maintains goodcontrol over the sheets during the transporting thereof individual sheets such as photographic prints and film and having a plurality of transversely spaced apart oscillating transfer elements in the form of a walking beam mechanism to transport the sheets through the drying chamber and provided with means for directing warm air onto the surfaces of the sheets being dried in a manner to urge the sheets toward the transfer elements and reduce the tendency to curling of the shee without scratching the'top surfaces thereof.

It is still a furtherobject to provide a drying device for sheet material whereby the device can be adjusted to vary the rate of travel through the drying chamber and thus vary the drying time and the feeding rollers are always driven at a speed which feeds the individual sheets onto the transfer bed at a slower rate than the transfer mechanism carries said sheets across the drying chamber regardless of the adjustment of the transport speed.

It is still a further specific object to provide a dryer the sheets of'material'to be dried, and'feed; the same through the entrance opening 13. Such a sheet S is illustrated in FIG. 2 as it is passing through the rollers and 16. The surface of the

rollers

15 and 16 issoft material, such as sponge rubber, in order to avoid damaging and scratching the surface of the sheets being fed therethrough and only the hot air in the heating contacts the top surface of the sheets after delivery through the feeding

rollers

15 and 16. Excess moisture is removed from the sheets and is collected on a drainage panel 17 which carries the collected liquid out of the drying chamber and delivers it to a collection pan 18 in which the sheets to be dried may be stored transfer mechanism which is adapted to transport the individual sheets to be dried through the drying chamber, without contacting the soft emulsion surfaces such as those used with photographic prints and film, thus minimizing the possibility of scratching such surfaces during the drying operation.

These and other objects and advantages of this invention will be apparent from the following description made in connection with the accompanying drawing wherein like reference characters refer to similar parts throughout the several views, and in which:

FIG. 1 is a side elevational view of the dryer with the cover closed;

FIG. 2 is a top plan view thereof with the cover removed and portions broken away;

FIG. 3 is a transverse vertical sectional view taken substantially along the line 3-3 of Fig. 1;

FIG. 3A is a transverse vertical section through one of the

channel members

22 or 23 of the walking beam mechanism;

FIG. 4 is a central longitudinal sectional view taken substantially along the line 4-4 of FIG. 2; and

FIG. 5 is a view similar to FIG. 4 taken substantially along the line 5-5 of FIG. 2.

The dryer illustrated in the accompanying drawings embodies an outer casing designated as an entirety by the numeral 10, which has a cover 11 which in the form shown is pivotally mounted as by the pivot rod 12. The casing and cover combine to form an enclosed drying chamber having an entrance opening 13 and a discharge opening 14 at opposite ends thereof. Two pairs of squeegee-

type feeding rollers

15 and 16 receive prior tobeing fed into the dryer. Suitable means for driving the

squeegee rollers

15 and 16 are provided, such as the meshed worm gears 19 and 20, which are driven by a main drive shaft 21 which is driven by a motor M which has a suitable speed control C.

A transfer bed is formed in the drying chamber by a walking beam transport mechanism which receives the sheets S from the

rollers

15 and 16 and carries the same through the drying chamber and discharges said sheets through the discharge opening 14 aftera predetermined time interval has elapsed. In the specific fonn shown, the walking beam mechanism includes a plurality of parallel spaced apart stationary support members 22 and a plurality of oscillating transfer member 23 which are interposed between the stationary channel members 22 and which intermittently engage and transport the sheets S through the drying chamber. Obviously, other transport mechanisms could be used which contact only one side of the sheets and which permit the flow of drying air downwardly through the chamber. Both the support members 22 and the transfer members 23 are coated with a suitable material which has low thermal conductivity properties and which will also prevent the corrosion of the members due to the chemical solutions used to process the photographic sheets S. As best shown in FIG. 3A, a soft vinyl resin material, respectively designated 22a and 23a, is applied to

channel members

22 and 23 and has the foregoing coating properties. This material also has a higher friction coefficient than the

metal channel members

22 and 23. Of course, other materials having the desired properties could be used also. The oscillatv ing members 23 are all mounted on a single oscillating frame structure 24 and an eccentric driving mechanism 25 imparts the oscillating motion to said frame and the transfer members 23. The oscillating members 23 travel in a generally circular path which carries them up above the stationary members 22 during the forward portion of their movement and thus brings them into contact with the sheets during the sheet advancing portion of the oscillating path. As the members 23 are oscillated back during the return portion of the path, they drop down below the stationary members which then support the sheets in stationary position until said sheets are re-engaged by the driving members during the next forward advancing portion of their movement.

The eccentric drive mechanism embodies a pair of cross shafts 26 which are driven by the maindrive shaft 21 as by the meshed gears 27. An eccentric driving connection is made between the respective ends of the shafts 26 and the adjacent portion of the frame 24 as by pins 28 which are eccentrically connected to rotary wheels 29 respectively mounted on shafts 26, as best shown in FIGS. 2 and 5. Slots 24a are provided in the frame 24 to receive the pins 28.

It is important that the transfer speed of the sheets S on the drying bed is somewhat faster than the speed at which said sheets are fed onto the bed by the

feed rollers

15 and 16. This speed differential is established and maintained by the driving ratios of the gears 19 and 20 i which drive said rollers and the gears 27 which drive the cross shafts 26. When the driving speed of the motor M is varied the speed of the

feed rollers

15 and 16 and the speed of shafts 26 will be simultaneously varied and the predetermined speed differential will be maintained.

A plurality of heating elements 30 are provided for heating the air and a blower 31 draws the air downwardly through the transfer bed and into contact with the heating elements 30. The flow of air from the blower 31 is divided substantially equally by a raised divider a formed on the inside of the bottom of housing 10. A center heating element 30 is mounted above the divider 10a and combines with the two outer heating elements to heat the air circulated downwardly from the blower 31. Substantially equal volumes of air are circulated through the outer conduit passages 32 which deliver the heated air into the drying chamber from opposite sides thereof in order to substantially balance the flow of air into the upper portion of the chamber which then flows downwardly onto the sheets and through the transfer bed to be heated and recirculated. A plurality of spoilers or air directing baffles 33 may be provided on the inside of the cover 11 to direct the air discharged through the passages 32 generally downwardly.

It will be seen that I have provided a relatively simple, yet highly efficient, dryer for individual sheets such as photographic prints or film, including a transport mechanism which combines with the balanced air flow circulated primarily in a downward direction through the drying chamber to maintain a positive air pressure on the top surface of the sheets S and a partial vacuum on the bottom surface to increase driving contact with said oscillating transport mechanism while at the same time tending to prevent curling of the sheets. The intermittent contact of the sheets with the stationary and oscillating support members produces a constantly varying random contact area between the bottom side of the sheets being dried and the

members

22 and 23 so that the thermal conduction between a specific area of the surface of the support members is minimized. The low thermal conductivity of the coating on both the stationary and oscillating

members

22 and 23 combines with the constant varying random contact area of said members with the sheets being dried to produce uniform drying of the entire surface of the sheets. This eliminates streaking of the photographic surface which is frequently a problem with uneven drying. The transport mechanism does not require any positive contact with the upper surface of the sheets other than the force of the air pressure which gently presses downwardly thereon as described. This eliminates any possibility of scratching the relatively soft upper surface of photographic prints or film while rt be ci ursefhe understood that various changes may be made in the form, details, arrangement and proportion of the parts without departing from the scope of this invention which generally stated consists in the manner set forth in the appended claims.

What is claimed is:

l. A dryer for flexible sheet material such as photographic prints and film, said dryer comprising a drying chamber with a sheet inlet opening and a sheet discharge opening therein,

a substantially horizontal walking beam transpo mechanism having spaced transfer members to permit the flow of heated air downwardly therethrough and including a plurality of moving transfer members engaging only the bottom side of the sheet material to be dried to transport the same through said drying chamber,

means for supplying heated air to the top surface of said sheets to be dried to combine with weight of the sheets to form the only external forces urging said sheets downwardly into contact with the moving transfer members, and

feeding means for delivering the sheet material through said inlet opening on to said transfer members at a speed slower than the speed at which said sheets are moved across the transport mechanism by said transfer members.

2. Structure set forth in claim 1 and means for varying the speed with which said sheets are transferred through said drying chamber.

3. The structure set forth in claim 1 and a pair of opposed air directing passages located on opposite sides of said drying chamber and directing heated air into the upper portion of said chamber through said opposed passages whereby the flow of air will be directed primarily downwardly to maintain contact between the sheets and the members of said transport mechanism.

4. The structure set forth in claim 1 and said bed including a plurality of spaced stationary support members interposed in laterally spaced relation between said moving transfer members, said moving members lifting said sheets out of engagement with the stationary members and subsequently re-depositing said sheets on the stationary members at an advanced position toward the discharge end of said drying chamber, the sheets being dried being free and unconfined in said chamber to produce constantly varying random contact areas between the lower surface of the sheets and the members of said transport mechanism.

5. The structure set forth in claim 1 and said transport mechanism members being constructed so that at least the area of contact thereof with the sheets is of a material having a low coefficient of heat conductivity to minimize localized heat transfer between the members of said transport mechanisms and the engaged portions of the sheets.

Claims

1. A dryer for flexible sheet material such as photographic prints and film, said dryer comprising a drying chamber with a sheet inlet opening and a sheet discharge opening therein, a substantially horizontal walking beam transport mechanism having spaced transfer members to permit the flow of heated air downwardly therethrough and including a plurality of moving transfer members engaging only the bottom side of the sheet material to be dried to transport the same through said drying chamber, means for supplying heated air to the top surface of said sheets to be dried to combine with weight of the sheets to form the only external forces urging said sheets downwardly into contact with the moving transfer members, and feeding means for delivering the sheet material through said inLet opening on to said transfer members at a speed slower than the speed at which said sheets are moved across the transport mechanism by said transfer members.

4. The structure set forth in claim 1 and said bed including a plurality of spaced stationary support members interposed in laterally spaced relation between said moving transfer members, said moving members lifting said sheets out of engagement with the stationary members and subsequently re-depositing said sheets on the stationary members at an advanced position toward the discharge end of said drying chamber, the sheets being dried being free and unconfined in said chamber to produce constantly varying ''''random'''' contact areas between the lower surface of the sheets and the members of said transport mechanism.