US3561586A

US3561586A - Apparatus for feeding fluent dry material

Info

Publication number: US3561586A
Application number: US831545A
Authority: US
Inventors: Patrick J Sweeney
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-06-09
Filing date: 1969-06-09
Publication date: 1971-02-09
Anticipated expiration: 1988-02-09

Abstract

Apparatus for feeding fluent dry material comprising two conveyors, one positioned above the other, the upper conveyor being adapted to feed material to the lower conveyor, and the two conveyors having a common discharge. The upper conveyor is operable to feed material forward at a relatively high rate, first filling the lower conveyor, and then continuing to feed the material forward into the discharge. As the quantity of material fed approaches a quantity somewhat less than a desired quantity, the upper conveyor is stopped. Then the lower conveyor, which is adapted to feed the material at a relatively low controllable rate, is operated to deliver the material into the common discharge to bring the total amount delivered up to the desired quantity.

Description

ARTICLE-HANDLING APPARATUS This invention is concerned with conveyor systems, for conveying rodlike articles, particularly cigarettes and other similarly light articles (including for example cigarette filter rods), in stack formation on conveyors in relation to which the articles lie transversely. in particular this invention is con cerned with a sensor for controlling the stack flow at a junction of two or more stacks to or from which the articles are carries by separate conveyors, though a sensor according to this invention may be used in other circumstances in which a signal is required in relation to the height of the stack of articles beneath the sensor, for example while loading cigarettes into a tray.

A conveyor system according to this invention includes two substantially horizontal conveyors extending in opposite directions from ajunction zone above which is arranged a sensor mechanism comprising two sensor members which are arranged to rest on the articles in positions lying respectively approximately above the ends of the two conveyors, and including a conveyor speed-regulating mechanism which controls the speed of one of the conveyors and is coupled to each sensor member by a lostmotion device so that the speed-regulating mechanism can be moved in one predetermined direction as a result of movement of either one of the sensor members while the other sensor member remains stationary.

In a preferred arrangement the predetermined direction in which either sensor member can move the speed-regulating mechanism corresponds to downward movement of either of the sensor members. ln other words, the speed-regulating mechanism always takes up a position determined by whichever sensor member is in a lower position. The converse is however in principle possible.

Furthermore, a preferred arrangement is one in which the twosensor members are pivoted about spaced axes parallel to the articles, and in which the sensor members extend towards one another and cross one another as viewed in a direction parallel to the articles. l

The parts of the plates resting on the articles are preferably shaped so as to have a convex underneath surface as viewed in the direction of the articles.

Examples of arrangements according to'this invention are shown in the accompanying drawings. In these drawings:

FIG. 1 is a side view of one arrangement;

FIG. 2 is a plan view; and

H6. 3 is a side view of a different arrangement.

The sensor shown in accompanying drawings consists of two sensor plates l and 11 which have downwardly convex portions 12 and 13 resting on ahorizontal stack of cigarettes carried by two: band conveyors l4 and 15. The Junction Zone" lies below the plates and 11. A single row of cigarettes is fed upwards into the junction zone by two bands 17 and 18 which return over small idler pulleys 19 and 20. The conveyors l4 and pass round further pulleys 21 and 22, and the horizontal surface on which the complete horizontal stack rests is completed by two small bridgepieces 23 and 24.

It will be seen that the convex parts 12 and 12 of the plates 10 and 11 lie on opposite sides of .a vertical plane passing through the single row of cigarettes 16, this plane being the vertical centerline'of the T junction. Moreover, the plates 10 and 11 and the conveyors l4 and 15 form a symmetrical arrangement so that the function of the conveyors 14 and 15 can be interchanged.

The plates 10 and 11 are secured respectively ,to spindles 25 and 26 by which they are pivotably mounted. As shown in FIG. 2, the two plates are slightly staggered laterally and each has two slots leaving three legs 27, the arrangement being such that the legs of each plate can pass through the slots in the other plate. In other words, the plates intennesh with one another.

Outside the cigarette flow channel, the spindles 25 and 26 carry respectively two arms 28 and 29 which are connected by links 30 and 31 to the

arms

32 and 33 of a bellcrank secured to a spindle 34 of a rotary speed-regulatingmechanism 35 which controls the direetion of rotation and the speed of ,a motor driving the conveyor 15. Each link 30 or 31 passes through a hole in the cooperating

arm

32 or 33 and has end nuts so that it can transmit a pull from the arm 28 or 29 to the

arm

32 or 33, as the case may be, but not a push. In other words, there is a lostmotion connection between each arm 28 or 29 and the

arm

32 or 33 of the bellcrank. As a result of this lost-motion connection, the bellcrank position is determined by whichever of the plates 12 or 13 is the lower position. The bellcrank is biased in an anticlockwise direction, for example by the weight of the arm 32.

FIG. 1 shows the plates 12 and 13 in their lowest positions, while the highest possible positions are shown in chain dotted lines, the limit of upward movement being determined by stops 36 and 37. it is important to note that the volume (in terms of the number of cigarettes) lying between the uppermost and lowermost positions of the sensor plates is substantial, i.e. the same order as the average volume of the junction zone. This is significant as it means that the sensor also serves as a useful reservoir to allow for short term variations in the rates of feed to and from the junction zone.

Plates 38 and 39 cooperate with the ends of the pivoted plates 12 and 13 to prevent the escape of cigarettes, and are appropriately slotted to intermesh with the sensor plates. As shown in H6. l,the plate 38 at its llower end 38A extends horizontally for a short distance so as to serve as a top wall confining the upper surface of the stack of cigarettes for a short distance from the junction. The plate 39, on the other hand, merely curves upwards slightly to a point close to a band 50 which serves as a top wall confining the upper surface of the stack in the other direction from the junction.

In one possible example, the conveyor band 14 continuously carries to the left a stack of cigarettes delivered by the bands 17 and 18, while the conveyor 15 serves as part of a reservoir which receives cigarettes (i.e. with the conveyor 15 moving to the right) when the upward supply of cigarettes 16 exceeds the rate of withdrawal of cigarettes by the conveyor 14; on the other hand, when the rate of withdrawal of cigarettes by the conveyor 14 exceeds the rate of supply to the junction by the bands 17 and 18, the conveyor 15 moves to the left so as to deliver cigarettes from. the reservoir. Further details of this arrangement are described in British Pat. application Nos. 54034/68 and 4l95/69. The sensor in this case may control the speed and direction of movement of the conveyor 1 5, while another sensor (which may be similar to the sensor shown in the drawings) may control the speed of the conveyor 14; for example, the far end of the conveyor 14 which is not shown may be at a further junction with an upward deliver similar to that shown in FIG. 1.

An important advantage of a double plate sensor according to this invention is that each plate can be made particularly sensitive to a drop in the level of cigarettes caused by an excessive delivery away from the junction by a conveyor beneath it or nearer to it. Considering for example a mode of operation in which, for the moment, the conveyor 15 is stationary while the conveyor 14 is rotating at a speed which exactly carries away the amount of cigarettes fed upwards by the bands 17 and 18; if then the speed of the conveyor 14 where to increase slightly, or if the rate of upward delivery of cigarettes by the bands 17 and 18 were suddenly to decrease according to our observation this change would be most quickly manifested by a drop in the level of cigarettes at the end of the conveyor 14, that is to say adjacent to the stationary bridge piece 23 as a result a hollow would form in the upper surface of the stack of cigarettes, and the convex part 12 of the pivoted plate 11 is so shaped (as nearly as possible) that it will sink snugly into the hollow, thus rotating the spindle 34 of the speed-regulating mechanism 35 in a clockwise direction which causes the conveyor 15 to start moving to the left at a speed such as to meet the deficiency in the cigarette supply to the conveyor 14. If the double plate sensor were replaced by a single central sensor (i.e. lying directly above the bands 17 and 18), the response would be slower as the level of cigarettes would take longer to fall away beneath such a centrally positioned sensor (and in a APPARATUS FOR FEEDING FLUENT DRY MATERIAL BACKGROUND OF THE INVENTION This invention relates to apparatus for feeding fluent dry materials, and more particularly to such apparatus for use in bulk material handling.

The invention is particularly useful in dry batching systems such as employed in the manufacture of animal feed. In such systems, different dry fluent materials are fed by conveyors from a plurality of storage hoppers to a weighing station for proportioning of the materials for batching.

Screw conveyors, as heretofore used in such systems, have had certain objectionable characteristics. For example, in prior systems utilizing screw conveyors, either accuracy or flow rate had to be compromised. Systems in which the quantity must be proportioned accurately required conveyors with relatively low feed rates to provide the control required for greater accuracy, but such a system required additional time to feed a given quantity of material, thus reducing the production rate. Conversely, use of conveyors with relatively high feed rates for feeding the material rapidly caused difficulty in accurate control of the quantity of material fed.

Dry fluent material, when conveyed, tends to build up adjacent the flights of the conveyor so that the relationship of the flights to the discharge determines, to some extent, the amount of material which will continue to flow after the conveyor has stopped. The angle of repose, which is affected by moisture content (a day-to-day variable), also affects the amount of material which will continue to flow once the conveyor is stopped. The fluidity of the material, which is affected by the moisture content, affects the power required to move the material and thus the time required for the conveyor to stop. These variables preclude predetermining with any degree of accuracy the point at which the conveyor can be stopped accurately to deliver a given quantity of material.

Accurate delivery of a given quantity of material is not only necessary for a high-quality product but also has economic advantages. In order that no less than the desired quantity be delivered, inaccuracies are normally on the high side, producing overages for which the customer does not pay. While a sin gle overage is insignificant, the aggregate over a longterm operation is significant and may amount to substantial lost income.

SUMMARY OF THE INVENTION Accordingly, among the several objects of this invention may be noted the provision of apparatus for feeding fluent dry material, particularly useful for batching operations as above described, adapted for operation rapidly to deliver accurately measured quantities of the material; the provision of such apparatus adapted for manufacture as original equipment or as a modification of existing equipment; and the provision of such apparatus which is economical to manufacture and reliable and easy to use.

In general, apparatus made in accordance with this invention comprises an upper conveyor for the material and a lower conveyor for the material located below the upper conveyor. The upper conveyor is adapted to feed the material forward to a point of discharge at a relatively high volumetric rate and has an outlet for discharge of material into the lower conveyor rearward of said point of discharge. The lower conveyor is adapted to feed material received from the upper conveyor forward to a point of discharge at a relatively low volumetric rate. The arrangement is such that the upper conveyor may be operated rapidly to feed out an amount somewhat less than said quantity, and the lower conveyor may then be operated to feed out the remainder for accurately controlled feeding of said quantity. Other objects and features will be in part apparent and in part pointed out hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a vertical section of a batch system showing two conveyor units for feeding fluent dry material;

FIG. 2 is an enlarged vertical section on line 2-2 of FIG. 1;

FIG. 3 is an enlarged horizontal section on line 3-3 of FIG. 1, showing an opening between the upper and lower conveyors ofone of the conveyor units;

FIG. 3A is a view similar to FIG. 3 showing a modification; and

FIG. 4 is a vertical section showing a modification.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. I of the drawings, there is indicated at 1A a first conveyor unit and at 18 a second conveyor unit for feeding dry fluent material to a weighting station 3 (e.g., a scale having a hopper for receiving the material). The first conveyor unit 1A comprises an upper conveyor 5 for the material and a lower conveyor 7 for the material located below the upper conveyor. The upper conveyor is adapted to feed the material forward (to the right, as illustrated at IA) to a point of discharge above the weighing station at a relatively high volumetric rate and has an outlet 9 for discharge of the material into the lower conveyor 7 rearward of the point of discharge. The lower conveyor 7 is adapted to feed the material received from the upper conveyor 5 forward (to the right, as illustrated at IA) to a point of discharge above the weighing station at a relatively low volumetric rate. The arrangement is such that the upper conveyor 5 may be operated rapidly to feed out an amount of material somewhat less than the desired quantity and then the lower conveyor 7 may be operated to feed out the remainder for accurately controlled feeding of said quantity.

The upper conveyor 5 of unit IA comprises an elongate trough 11 having an end wall 13 at its discharge end (its right end, as illustrated). Outlet 9 is constituted by an elongate slot in the bottom of trough 11 extending rearward for some distance from the discharge end of the trough. Extending endwise in the trough is a drag conveyor generally designated 15, comprising a series of flights 17 in the form of paddles on an endless chain I9. The flights conform to the shape of the bottom portion of the trough. At D1 is indicated means for driving the drag conveyor at relatively high. speed in the direction for travel of the flights on the lower reach of the chain toward the discharge end of the trough.

The lower conveyor 7 comprises a trough 23, having a length corresponding to the length of the slot 9 and a width corresponding to the width of slot 9, mounted underneath the trough II at the discharge end of the latter by welding or otherwise suitably securing its upper edges to the bottom of trough I1. At the discharge end of trough 23 (its right end, as illustrated) is a downwardly directed discharge chute 25 for delivering material to the weighing station. Wall 13 has a downward extension constituting the discharge end of the lower conveyor 7. Extending endwise in trough 23 is a screw conveyor generally designated at 27, comprising a shaft 29 having radial flights 31 which form a continuous lengthwise spiral extending along the shaft. At D2 is indicated a means for driving the screw conveyor 27 in a direction of travel which causes the material to feed toward the discharge end of the trough 23. The screw conveyor 27 and the bottom of the trough 23 are angled with respect to the drag conveyor I5 and the trough 19 so that the axes of the two conveyors form an acute angle having an apex adjacent the discharge.

The screw conveyor shaft 29 may have its discharge end journaled in a bearing 32 fastened to end wall 13. Having the bearing 32 mounted on the outside of the end wall 13 is desirable if the material conveyed is highly abrasive. If not, the bearing may be positioned within the discharge chute as indicated at 320 in FIG. 3A by having the trough 23 extend into the discharge chute and provided with an end wall 33 attached thereto for mounting the bearing 32a. The bottom part of the trough 23 is cutaway within the discharge chute 25, providing a bottom discharge 35 for the lower conveyor. Mounting the bearing 32 within the discharge chute may reduce installation cost, particularly where an existing conveyor is being modified to incorporate this invention.

The second conveyor unit illustrated generally at 1B is similar to the first conveyor unit LA hereinbefore described except that it has a screw conveyor generally indicated at 37 extending endwise in the trough 11, instead of the drag conveyor 15. The drag type of conveyor is preferred for new installations because it has a higher delivery capability than the same size screw conveyor. However, the majority of existing batching systems employ screw conveyors, so that existing systems may be modified to includemany of the advantages of this invention by installing the lower conveyor below an existing screw conveyor, as illustrated generally at 18.

HO. 4 illustrates an alternate arrangement wherein the upper conveyor is installed in an inclined position with respect to the horizontal so that the conveyor ascends in the direction of the flow. When so installed, the incline may provide sufiicient angular displacement for the lower conveyor 70 so that the axes of the two conveyors may be generally parallel.

The upper and lower conveyor drives, indicated generally at D1 and D2, respectively, operate in an alternating cycle. Starting the upper conveyor drive Dl begins the cycle by feeding the fluent dry material forward at a relatively high rate, filling the lower conveyor 7. Having filled the lower conveyor, the upper conveyor 5 continues feeding the material forward through the discharge chute 25 into the weighing station hopper 3. As the quantity of material fed approaches an amount somewhat less than the desired quantity, the upper conveyor drive D1 is stopped. Starting the lower conveyor drive D2 feeds additional material forward through the discharge chute 25 into said hopper 3 at a relatively low controllable rate. When the quantity of material fed reaches the desired quantity, the lower conveyor drive D2 is stopped. Additional material may be fed by jogging the lower conveyor. Having obtained the desired a quantity of material, the cycle is ready to be repeated.

A quantity of material sufficiently short of the desired quantity at which the upper conveyor 5 should be stopped is generally the amount of material held in the upper conveyor 5 directly above the outlet 9, plus one-half of the material held in the lower conveyor 7. Feeding said quantity of material via the lower conveyor causes the material remaining in the lower conveyor to vibrate down the angled trough 23 rather than slide into the discharge chute. Material remaining in the upper conveyor will vibrate in the rearward end of the lower conveyor. Operating the lower conveyor so as to leave it approximately one-half full insures the availability of sufficient material to deliver the desired quantity and provides flexibility in the operation of the equipment.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

lclaim:

1. Apparatus for feeding out a quantity of fluent dry material comprising an upper conveyor for the material and a lower conveyor for the material located below the upper conveyor, the upper conveyor comprising a trough having conveyor means extending lengthwise thereof adapted to feed material in the said upper conveyor trough in the direction toward one end thereof constituting its forward end at a relatively high volumetric rate, said upper conveyor trough having an elongate bottom outlet at its forward end for bottom discharge of the material, the lower conveyor comprising a trough extending under said elongate bottom outlet of the upper conveyor trough for receiving material therefrom, conveyor means extending lengthwise of the lower conveyor trough adapted to feed material in said direction along the lower trough toward one end thereof constituting its forward end at a relatively low volumetric rate, said lower conveyor trough having a bottom outlet at its forward end, a forward portion of the bottom outlet of the upper conveyor trough and the bottom outlet of the lower conveyor trough being in direct communication with a common delivery station for direct gravity flow of the material to said delivery station from each conveyor trough, the rearward portion of the bottom outlet of the upper conveyor through being in communication with the lower conveyor trough rearward of the bottom outlet of the latter, whereby the upper conveyor may be operated to supply the lower conveyor trough and then rapidly to feed out an amount of material somewhat less than said quantity directly from the upper conveyor outlet to the delivery station with the lower conveyor means out of operation, and the lower conveyor means may then be operated to feed out the remainder for accurately controlled feeding of said quantity.

2. Apparatus as set forth in claim I wherein the forward portion of the bottom outlet of the upper conveyor trough is directly above the bottom outlet of the lower conveyor trough.

3. Apparatus as set forth in claim 1 wherein each of the upper and lower conveyors is a screw conveyor.

4. Apparatus as set forth in claim 1 wherein the upper conveyor is a drag conveyor and the lower conveyor is a screw conveyor.

5. Apparatus as set forth in claim 1 having a discharge chute extending down from the bottom outlet of the upper conveyor trough and the forward end of the lower conveyor trough ex tends partially into said chute.

6. Apparatus as set forth in claim 1 wherein the axes of both conveyor means are generally parallel.

7. Apparatus as set forth in claim 1 wherein the axis of the lower conveyor is angled with respect to the horizontal so that it ascends in the direction of flow.

8. Apparatus as set forth in claim 1 having separate drive means for each conveyor.

Claims

2. Apparatus as set forth in claim 1 wherein the forward portion of the bottom outlet of the upper conveyor trough is directly above the bottom outlet of the lower conveyor trough.

5. Apparatus as set forth in claim 1 having a discharge chute extending down from the bottom outlet of the upper conveyor trough and the forward end of the lower conveyor trough extends partially into said chute.