US2713213A

US2713213A - Self-cleaning screen for material handling apparatus

Info

Publication number: US2713213A
Application number: US410305A
Authority: US
Inventors: Bogaty Stanislaus
Original assignee: Proctor and Schwartz Inc
Current assignee: Proctor and Schwartz Inc
Priority date: 1954-02-15
Filing date: 1954-02-15
Publication date: 1955-07-19
Anticipated expiration: 1972-07-19

Description

July 19, 1955 s. BOGATY 2,713,213

SELF-CLEANING SCREEN FOR MATERIAL HANDLING APPARATUS Filed Feb. l5, 1954 3 Sheets-Sheet l /7 lg l@ i July 19, 1955 s. BOGATY 2,713,213

SELF-CLEANING SCREEN FOR MATERIAL HANDLING APPARATUS Filed Feb. l5, 1954 5 Sheets-Sheet 2 `@QOOO COO/@@@QGG/Q@ July 19, 1955 s. BoGATY 2,713,213

SELF-CLEANING SCREEN FOR MATERIAL HANDLING APPARATUS Filed Feb. l5, 1954 5 Sheets-Sheet 3 United States hatent fiee Patented July SELF-CLEAr THG SCREEN FR MTERAL NBLING APPAITUS Stanislaus Bogaty, hilndelphia, Pm, assigner to Proctor and Schwartz, Inc., Phiiadelphia, Pa., a corporation of Pennsylvania Application February l5, 1954, Serial No. @0,335

i3 Claims. (Cl. 34m-3?.)

The present invention relates to new and useful irnprovements in self cleaning screens for material handling apparatus and more particularly to new and useful improvements in self-cleaning screens which may he positioned above a conveyor transporting fine material through a dryer or liite equipment and prevent the material from circulating through the apparatus with the drying or other treating medium.

ln the treating and drying of tobacco in dryers and other equipment having circulation of the drying or other treating medium both up and down through the material being treated, the standard procedure has been to reduce the volume of the medium circulating up through the material to such a point where particles of the material being treated will not become entrained in the flow of the treating medium. This practice is prevalent even though a necessarily decreased output results from this reduced circulation because the use of a more intensive circulation would require a screen to prevent the small particles of material from being circulated through the material treating apparatus along with the drying medium.

The only presently existing hold-down screens are of the stationary type which become badly clogged after a few hours of operation and the conveyor type which must be girt supported and are too expensive to be installed in most types of equipment.

With the foregoing in mind the principal object of the present invention is to provide a self-cleaning screen readily adaptable for installation in new or presently existing material handling equipment which will increase the output of the apparatus.

Another object of the present invention is to provide a novel continuously operating self-cleaning screen particularly adapted for use in drying apparatus such as, for example, tobacco dryers wherein the circulation of drying medium is in dierent directions in alternate compartments in the dryer.

A further object of the present invention is to provide a self-cleaning tobacco screen of the type set forth above which will increase the capacity and output of the dryer by permitting a faster circulation or' the drying medium.

A still further object of the present invention is to provide a novel self-cleaning screen having the features and characteristics ser forth above which is relatively inexpensive both in original cost and in maintenance cost and is highly eiiicient and effective in operation and use.

These and other objects of the present invention and the various features and details of the operation and construction thereof are hereinafter more fully set forth and described with reference to the accompanying draw-l ings, in which:

Fig. l is a side elevational view of a dryer having the self-cleaning screen of the present invention incorporated therein;

Fig. 2 is an end elevational view of the dryer illustrated in Fig. l;

Fig. 3 is an enlarged longitudinal sectional View of a plural compartment dryer similar to the dryer illustrated in Fig. l;

Fig. 4 is an enlarged longitudinal sectional view of the screen and screen operating mechanism;

VlFig. 5 is a transverse sectional View taken on line 5 5, Fig. 3 illustrating the mounting of the self-cleaning screen in relation to the conveyor carrying the material through the dryer;

Fig. 6 is a fragmentary sectional View taken on line 6 6, Fig. 3;

Fig. 7 is an enlarged fragmentary transverse sectional view taken on line 7 7, Fig. 4 illustrating the means for mounting the self-cleaning screen of the present invention;

Fig. 8 is a plan view of a dryer illustrating a modified arrangement of the mechanism for operating the selfcleaning screen; and,

Fig. 9 is a side elevational view partially in section of the dryer and screen operating mechanism illustrated in Fig. 8.

The present invention consists essentially of providing a reciprocating screen or screens in a dryer or other material treating apparatus having a material treating medium circulating in opposite directions through adjacent sections of the material being treated. The screens are mounted so that each portion of the screen is moved back and forth longitudinally of the material treating apparatus between compartments or sections of the apparatus having the treating medium circulating in opposite directions. in this manner one section of the screen is initially in a position in the path of travel of the me- @lum after the medium passes through the material being treated and thus screens out any particles of the material being treated which are en "ained in the medium. That section of the screen is then moved to a position in the apparatus wherein the medium is traveling in the opposite direction and the particles of material on the screen are blown or forced haelt into the bed of material being treated.

This type of screen is particularly adaptable for use in apparatus for drying and conditioning cut tobacco where the drying medium is blown through a bed of cut tobacco carried by a foraminous conveyor since the small particles of tobacco have a tendency to become entrained in the stream of drying medium passing through the bed of tobacco. in addition, a brush or similar device may be mounted adjacent one end of the dryer housing to remove particles of material from the screen as it is projected out from the end of the dryer housing. By this construction set forth above, particles of the material be* ing dried which are taken out of the stream of drying medium by the screen are continuously removed from the screen and returned to the bed of material thus preventing clogging or" the screen and the resultant decrease in emciency of the dryer.

Referring new to the drawings and particularly Figs. l and 2 thereof, the present invention is illustrated for use in conjunction with a dryer hut it is apparent that the self-cleaning screens may be used with any type of material treating apparatus wherein a treating medium is forced in opposite directions through a bed of material. Reference numeral l() designates generally a. dryer of conventional construction comprising a housing l1 divided into a plurality of compartments l2 by baiiles or similar members 13 extendinu transversely of the dryer housing.

The upper run of a conveyor l of conventional forarninous construction passes longitudinally through the dryer housing Li substantially at the midpoint of the compartments 12. The conveyor l. is mounted to ride on

tracks

15, 15 at the opposite side edges of the drying chamber, for example, as illustrated in Fig. 2, and overlapping side guards or plates 16 mounted at the opposite sides of the conveyor 14 form a trough-like upper surface on the conveyor which receives and supports a bed of any desired thickness of the material to be dried.

In a dryer of this type the drying medium is circulated in opposite directions in adjacent compartments of the dryer so that the drying medium passes downwardly through the bed of material to be dried during a portion of the drying cycle and upwardly through the bed of material during the remaining part of the drying cycle. ln the illustrated embodiments of the present invention the drying medium is passed up through the conveyor and the material being dried in the iirst compartment and in the opposite direction in the next adjacent compartment. To accomplish this a conventional blower 17 is mounted in each compartment as shown in Fig. l to cause the desired circulation of the drying medium. In addition, heating elements 18 are also provided longitudinally of the dryer housing l1 to condition and heat the drying medium prior to passage through the material being dried.

In accordance with the present invention, means are provided to remove any particles of material which be come entrained in the drying medium passing upwardly in the dryer housing through the bed of material being dried. One form of apparatus for accomplishing this is illustrated in Figs. l to 7, inclusive of the drawings. ln this embodiment a foraminous screen 2l of any conventional construction comprising a series of screen sections 22 is mounted interiorly of the dryer housing 11. A pair of

tracks

23, 23 disposed at opposite sides of the dryer housing mount the screen 21 a short distance above the upper run of the conveyor 14 in spaced parallel relation therewith.

Rollers

24,24 mounted adjacent the edges of the screen frames 25 in engagement with the tracks support the screen in this position and permit free longitudi- Vnal movement of the screen relative to the dryer housing.

As set forth previously, an important feature of the present invention is the provision of means to continu- 'ously remove from the' screen the particles of material being dried which are filtered out of the stream of dr ing medium passing through the bed of material. To this end, the screen 21 is of a length substantially equal to the length of the dryer housing and is mounted for reciprocating movement back and forth from a rearward limit position interiorly of the housing adjacent the discharge end thereof to a forwardlimit position toward the feed end of the housing a distance equal to the longitudinal length of one of the compartments 12. By this construction the section of the screen adjacent the discharge end of the housing has the drying medium forced downwardly therethrough when the screen is in its rearward limit position which removes any particles of the material being dried from the screen; and in the forward limit position thereof is positioned in the next to last compartment of the dryer housing where theY drying medium is forced upwardly through the screen so that the screenrremoves all particles of material from the stream of drying medium. Each other section of the screen except the section adjacent the feed end of the dryer housing is alternately moved from a position whereinthe drying medium is forced upwardly through the yscreen to a position wherein the drying medium passes downwardly through the screen and removes the particles of material therefrom. Y

Thersection of screen adjacent the feed end of the dryer housing has the drying medium blown upwardly therethrough when the screen is in its rearward limit position and is projected forwardly of the feed end of the housing during movement of the screen to its forward limit position. brush 26 extends transversely of the dryer housing adjacent the feed end thereof and is continuously rotated, for example, by means of a small electric motor 27 and a chain drive 28. When the screen is projected forwardly of the feed Vend of the housing the brush engages the lower surface of the screen thus removing any particles To clean the feed end of the screen a therein and the drying medium passes upwardly through" the bed of material and then through the screensrin the the pinions is caused by a reversible motor 33 and suit-V able driving connections, for example, as indicated at 34 in Fig. 2. Rotating the pinions one direction ywith respect to Fig. 3 will cause the screen to move to its forward limit position in the dryer housing and rotating the pinions in the oposite direction will move the screen'to its rearward limit position. Reversing the direction Vof travel of the screen is controlled by forward and rearward

limitswitches

35 and 36, respectively, which are mounted on one of the tracks 23 and are operable to be engaged and actuated by a switch actuating member 37 carried by the screen frame 25.- As the screen reaches the end of its forward stroke the switch actuating member 37 engages the forward limit switch 35 thus reversing the motor 33 and causing the screen to move toward its rearward limit position. ln a similar manner when the screen reaches its rearward limit position the switch actuating member 37 engages the rearward limit switch 36 again reversing the motor 33 and causing the screen to move to its forward limit position.

Various modifications of the screen arrangement may be made depending on the arrangement of ow of the drying medium in the housing. For example, if the flow of drying medium is down the first compartmentl and up in the last compartment, the cleaning brush 26 will be mounted adjacent the discharge end of the dryer housing and the screen will be projected rearwardly of the discharge end of the housing.` Also, if the ow of drying medium is down in both the first and last compartments, the screen may be made shorter than the dryer housing by a length equal to the length of one of thecompartments and the screen may be'reciprocated back and forth in the housing from one end thereof to the other thus eliminating any necessity for a cleaning brush.

Figs. 8 and 9 illustrate a modified form of screen arrangement in the present invention Vwherein separate sfreen sections 41 and 42 are mounted for movement independent of one another on separate pairs of tracks 43 and 44, respectively. In addition separate drive mechanism is provided for each screen Vsection and the screen 41 is reciprocated back and forth in the dryer housing by means of a reversible motor 45 driving a drum 46' mounted on fixed shaft 47. A cable 48 passes about theV drum 46 and has its ends secured to opposite ends of the screen section 41. In addition, resilient tensioning Vmeans is provided in the cable as indicated at 49. When ltheV of the cable 53 are secured to opposite ends of the screen 42, and resilient tensioning means are provided in the cable 53 as indicated at 54. Driving the motor 51 in opposite directions causes movement of the screen 42 back and forth in the dryer housing. The dryer illustrated in Figs'. 8 and 9 has two

separate compartments

55 and 56 forward compartment 55, and downwardly throughV the screens and bed of materialto be dried in the rear cornat least one screen to be positioned in the pathofrthe www drying medium in the compartment 55 at all times, For example, with reference to Fig. 9 at the beginning of one cycle of operation the screen 42 is in the path of the drying medium passing upwardly through the bed of material to be dried. The screen 41 is then moved to the feed end of the housing and when it reaches this position engages and actuates a limit switch 57 which causes operation of the motor 51. The motor 51 will then move the screen 42 to the discharge end of the dryer housing wherein the drying medium will be forced downwardly through the screen to clean the same. Upon reaching the discharge end of the dryer housing the screen 42 engages and actuates a limit switch 5S to reverse the operation of the motor 51 and cause the screen 42 to be moved to the feed end of the housing. Upon reaching the feed end of the housing screen 42 engages and actuates a third limit switch 59 which causes operation of the motor 45 thereby' moving the screen 41 to the discharge end of the housing where it is cleaned by the drying medium passing downwardly therethrough. When the screen 4i reaches the discharge end of the housing a fourth limit switch 61 is engaged and actuated by the screen 4l reversing the operation of the motor 45 and causing the screen 41 to be moved toward the feed end of the housing. This opration set forth above is repeated continuously while material is passing through the dryer housing and thus the screens 41 and 42 will remove any particles of the material being dried from the drying medium passing upwardly through the bed of material in the compartment 55 and the screens will be cleaned in the compartments 56 and then return to the compartment 55.

From the foregoing it is apparent that the present invention provides a novel self-cleaning screen for dryers and similar apparatus which removes any particles of the material being treated which are entrained in the drying medium passing through the material thus permitting an increase in the rate of flow of the drying medium with a resultant increase in the output of the apparatus, .in addition the present invention provides a novel continuously operating self-cleaning screen wherein the particles of material caught by the screen are automatically removed therefrom and redeposited on the bed of material being treated.

While particular embodiments of the present invention have been illustrated and described herein it is not intended to limit the invention to such a disclosure and changes and modifications may be incorporated and embodied therein within the scope of the foilowing claims:

I claim:

l. A seif cleaning screen for dryers and similar equipment comprising; a housing, conveyor means passing through said housing, blower means operable to force a treating medium through the conveyor means in opposite directions in adjacent portions of the housing, a plurality of screen sections mounted in said housing in spaced parallel relation with said conveyor, said screen sections being mounted in adjacent portions of said housing whereby the treating medium is caused to pass in opposite directions through said adjacent screen sections and said conveyor, and drive means operable to actuate said screen sections to the next adjacent portion of the housing wherein treating medium is forced therethrough in the opposite direction.

2. A self cleaning screen for dryers and similar equipment comprising; a housing, conveyor means passing through said housing, blower means operable to force a treating medium through the conveyor means in opposite directions in adjacent portions of the housing, a plurality of screen sections positioned in said housing in spaced parallel relation with said conveyor, means mounting said screen sections for reciprocating movement relative to said housing, said screen sections being mounted in adjacent portions of said housing whereby the treating medium is caused to pass in opposite directions through said adjacent screen sections, and drive means operable to actuate said screen sections and said conveyor in one direction to the next adjacent portion of the housing wherein the treating medium is forced therethrough in the opposite direction and then actuate said screen sections baci; to their original position in the housing.

3. A self cleaning screen for dryers and similar equipment comprising; a housing, conveyor means passing through said housing, blower means operable to force a treating medium through the conveyor means in opposite directions in adjacent portions of the housing, a plurality of screen sections positioned in said housing above said conveyor in spaced parallel relation therewith, means mounting said screen sections in said housing for reciprocal movement between forward and rearward limit positions, said adjacent screen sections being mounted in adjacent portions of said housing whereby the treating medium is caused to pass in opposite directions through said adjacent screen sections and said conveyor, and drive means operable to reciprocate said screen sections baci; and forth between said forward limit positions wherein the screen sections are coextensive with one portion of the housing and said rearward limit position wherein said screen sections are coextensive with the next adjacent portion of said housing whereby the treating medium is successively passed in opposite directions through said screen sections.

4. A self cleaning screen for dryers and similar equip ment operable to remove particles of material from a stream of treating medium passing through a bed of material being dried and return the particles to the bed of material comprising; a housing including a plurality of separate sections, a foraminous conveyor passing through the housing operable to convey the bed of material therethrough, blower means to circulate the treating medium through the material carried by said conveyor, said medium being circulated in one direction through the material in one section of the housing and in the opposite direction through the material in the next adjacent section of the housing, a plurality of screen sections mounted in said housing in spaced paraliel relation with said conveyor, said adjacent screen sections being mounted in adjacent sections of said housing whereby the treating medium is caused to pass in opposite directions through said adjacent screen sections and said conveyor, and drive means operable to actuate said screen sections to the next adjacent screen of the housing wherein the treatinfI medium is forced therethrough in the opposite direction.

5. A self cleaning screen for dryers and similar equipment operable to remove particles of material from a stream of treating medium passing through a bed of material being dried and return the particles to the bed of material comprising; a housing including a plurality of separate sections, a foraminous conveyor passing thro h the housing operable to convey the bed of material therethrough, blower means to circulate the treating medion through the material carried by said conveyor, said medium being circulated in one direction through the material in one section of the housing and in the oppl :itc direction through the material in the next adjacent section of the housing, a screen substantially equal to the length of the housing comprising a plurality of screen sections equal in number to said plurality ot' hous- "iig sections, means mounting said screen in Said housing for reciprocal movement between one predetermined limit position wherein the screen is entirely within said housing a second predetermined limit Vposition 'wherein one screen section is projected beyond one end of housing and each other screen section is moved to toe next adjacent section of the housing, and drive means operable to reciprocate said screen back and forth between said predetermined limit positions.

6. A self cleaning screen for dryers and similar equi ment operable to remove particles of material from a stream of treating medium passing through a bed of materiai being dried and return the particles to the bed screen sections equal in number to said plurality of hous- Y ing sections, a pair of spaced parallel track members mounted adjacent opposite sides of said housing above said conveyor, rollers on said screen in engagement with said tracks mounting said screen insaid housing for reciprocal movement between one predetermined limit position wherein the screen is entirely within said housing and a secondiV predetermined limit position wherein one screen section is projected beyond one end of said housing and each other screen section is moved to the next adjacent section of the housing, and drive means operable to reciprocate said screen back and forth between saidpredetermined limit positions.

7. A self cleaning screen for dryers and similar equipment operable to remove particles of material from a stream of treating medium passing through a bed of materialbeing dried and return the particles to the bed of material comprising; a housing including a plurality of separate sections, a foraminous conveyor passing through Ythe housing operable to convey the bed of material therethrough, blower means to circulate the treating medium through the material carried by said conveyor, said medium being circulatedv in one direction through the material in one section of the housing and in the opposite direction through the material in the next adjacentrsection of the housing, a screen substantially equal to the length of the housing comprising a plurality of screen sections equal in number to said plurality of housing sections, means mounting said screen in said housing for reciprocal movement between one predetermined limit position wherein the screen is entirely within said housing and a second predetermined limit position wherein one screen section is projected beyond one end of said housing and each other screen section is moved e to the next adjacent section of the housing, driveimeans operable to reciprocate said screen back and forth between said predetermined limit positions, and a rotatable brush member mounted adjacent said one end of said housing operable to engage said screen during movement thereof to said second limit position and remove any particles of mate ial from the screen.

8.' A self cleaning screen for dryers and similar equipment operable to remove particles of material from a stream of treating medium passing through a bed of material being treated and return the particies to the bed of material comprising; a housing, means dividing the housing into a plurality of interconnected transverse compartments, a foraminous conveyor extending longitudinaily through the housing operable to convey the bed of material through each of said compartments, blower means operable to circulate the treating medium down through the material carried by the conveyor in one compartment and in the opposite direction in the next adjacent compartment, a plurality of screen sections mounted in said housing in spaced parallel relation with said conveyor, said adjacent screen.. sectionsl being mounted in and coextensive with'adja'cent compartments in said housing whereby the treating medium is caused to pass in opposite directions through said adjacent screen sections, and drive means operable to actuate said screen sections to the nextadjacent compartment of the housing wherein the treating mediumis forced therethrough in the opposite direction.

Y9. A self cleaning screen for dryers and similar equipment operable to remove particles of material from a stream of treating medium passing through a vbed of material being treated and return the particles to the bed of material comprising; a housing, means dividing theY housing into a plurality of interconnected transverse.v

compartments, a foraminous conveyor extending longitudinally through the housing operable to convey the bed ofrnaterial through each of said compartments, blower means operable to circulate the treating medium down through the material carried by the conveyor in'one com artment and in the opposite directionin the next adjacent compartment, a screen substantially equal to the length of the housing comprising a plurality of screen sections equal in number to said plurality of housing compartments, means mounting said Screen inY said housing for reciprocal movement between one predetermined limit position wherein the screen is entirely within said housing and a second predetermined limit position Wherein one screen section is projected beyond one end of said housing and each other screen section is moved to the next adjacent compartment of the housing, and drive means operable to reciprocate said screen back and forth between said predetermined limit positions. Y

lt). A self cleaning screen for dryers and similar equipment operable to remove particles of material from a stream of treating medium passing through a bed of material being treated and return the particles to the bed of material comprising; a housing, means dividing the housing into a plurality of interconnected transverse compartments, a foraminous conveyor extending longitudinally through the housing operable to convey the bed of material through each of saidV compartments, blower means operable to circulate the treating medium down V'through the material carried by the conveyor in one compartment and in the opposite direction in the next Y adjacent compartment, a screen substantially equal to the length of the housing comprising a plurality of screen sections equal in number to said plurality of housing compartments, a pair of spaced parallel track members mounted adjacent opposite sides of said housing above said conveyor, rollers on said screen in engagement with said tracks mounting said screen in said housing for reciprocal movementV between one predetermined limit position wherein the screen is entirely Within said housing and a second predetermined limit position wherein one screen section is projected beyond one end of said housing and each other screen section is moved to the next adjacent compartment of the housing, drive means operable to reciprocate said screen back and forth between said predetermined limit positions, and a rotatable brush member mounted adjacent said one end of said housing operable to engage said screen during movement thereof to Vsaid other limit position and remove any particles of material from the screen.

ll. A self cleaning screen for dryers and similar,VY Y equlpment comprising, aV housing, conveyor means passing through said housing, blower means operable to force a treating medium through the conveyor means in opposite directions in adjacent portions of the housing, a first screen section mounted in one portion of said housing for reciprocal movement between said one portion of the housing to the next adjacent portion of the housing, a second screen section mounted in said next adjacent portion ot the housing for reciprocal movement from said portion to said one portion of the housing, and drive means operable to reciprocate said screen sections back and forth between said housing portions.

l2. A self cleaning screen for dryers and similar equipment operable to remove particles of material from a stream of treating medium passing through a bed of material being treated Yand return theparticles to the bed of material comprising; a housing, means dividing the` bed of material through each or" said compartments, blower means operable to circulate the treating medium down through the material carried by the conveyor in one compartment and in the opposite direction in the next adjacent compartment, a rst screen section coextensive with one of said housing compartments, a second screen section coextensive with said next adjacent housing compartment, means mounting said screen sections for reciprocal movement back and forth between said rst and said next adjacent housing compartments, and drive means operable to reciprocate said screen sections back and forth in said housing.

13. A self cleaning screen for dryers and similar equipment operable to remove particles of material from a stream of treating medium passing through a bed of material being treated and return the particles to the bed of material comprising; a housing, means dividing the housing into a plurality of interconnected transverse compartments, a foraminous conveyor extending longitudinally through the housing operable to convey the bed of material through each of said compartments, lower means operable to circulate the treating medium down through the material carried by the conveyor in one cornpartment and in the opposite direction in the next adjacent compartment, a rst screen section coextensive with one of said housing compartments, a second screen section coextensive with said next adjacent housing compartment, means mounting said screen sections for reciprocal movement back and forth between said rst and said next adjacent housing compartments, drive mechanism for each of said screen sections operable to reciprocate the same back and forth between said housing compartments, and control mechanism actuated by movement of said screen sections operable to actuate said drive mechanism.

References Cited in the file of this patent UNITED STATES PATENTS 1,026,432 Dey May 14, 1912 1,361,626 Schwartz et al. Dec. 7, 1920 2,216,986 Roe Oct. 8, 1940 FOREIGN PATENTS 182,007 Germany Mar. 5, 1907 871,076 France Jan. 3, 1942