US2912283A - Bag-filling machine - Google Patents

Description

Nov. 10, 1959 A. s; WIDZER 2,912,283

BAG-FILLING MACHINE Filled Aug. 20, 1956 2 I 2 Sheets-Sheet 1 INVENTOR. ARTHUR S.W1D2ER Y aim w. (JAM United States Patent BAG-FILLING MACHINE Arthur S. Widzer, Louisville, Ky., assignor to The B. F. Goodrich Company, New York, N.Y., a corporation of New York 1 Application August '20, 1956, Serial No. 604,981

Claims. (Cl. 302-29) The present invention relates to the art of filling bags or other containers with a predetermined weight of material, More specifically, this invention relates to bagfilling, packing and weighing machines for use with pulverulent materials.

In the present state of the art the packing of bags with dry pulverulent materials is carried out on an industrial scale by means of a machine including a weigh scale arranged to shut off the flow of materials when the desired weight of material has been put in the bag. Many means have been employed for feeding the material to the bag including valve-controlled gravity feed hoppers, screw type feeders, and even. air fluidization. However, known forms of this equipment hasnumerous disadvantages including (1) low accuracy in the weights attained from one bag to the next, (2) poor packing of the material in the bag resulting in the use of bags larger than need be, (3) severe dusting problem, especially with the finer materials, and (4) the necessity. for large, cumbersome hoppers, etc.

The principal object of this invention is to provide a bag-filling machine which will more effectively pack dry, pulverulent materials, especially the extremely fine materials which oherwise would require a quite large bag for the commercially acceptable 50 and 100 lb. quantities. Another important object is to provide such a machine which will provide a high order of accuracy in amounts of material put in each bag. Still another object is to provide a material-feeding device :which does not require a high static head of material for efficient flow and which for that reason is more compact and more flexible, and which also does not suffer from sticking and jamming. Other valuable objects will appear in the following more detailed description taken in connection with the accompanying drawings in which:

Fig. 1 is a front elevation, partly schematic, of a complete bag-filling installation incorporating the materialfeeding device of this invention;-

Fig. 2 is a perspective view of the material-feeding device of this invention, the view showingfthe disposition of the porous fluidizing surfaces in the material-receiving chamber;

Fig. 3 is an elevation in section taken along the longi tudinal center line of the material feeding device shown in Fig. 2; v f

Fig. 4 is a transverse sectional view through the material-receiving chamber, the section being taken along the line 44 of Fig. 3; and

Fig. 5 is a transverse sectional view through the horn, the section being taken along the line 5'--5 of Fig. 3.

In accordance with the present invention a materialfeeding device is provided which moves material around a turn, so to speak, the device including a materialreceiving chamber, adapted to receive material by gravity flow, and a material-conveying duct connected to the chamber at -a substantial angle, for example at about 90. Material is forced out of this device by means of fluidizing air or gas supplied by a number of gas-dispersing means including as a minimum- (1) acircumferen- 2,912,283 Patented Nov. 10, 1 959 2 tially-continuous gas dispersing means located in the duct means and- (2) a second gas dispersing means located in the chamber means, dispersing means (1) and (2) being so arranged to supply a continuous cushion of fluidizing gas extending from the chamber proper through the feed throat (region where chamber and duct interconnect) to the discharge end' of the duct. Other gas dispersing means can be supplied, particularly one or more such means adapted to fluidize a considerable depth of material over the described second gas dispersing means.

In the device of this invention, as illustrated in the drawings, a material-receiving chamber and materialconveying duct arranged to receive material by gravity flow and to discharge through the duct in a generally horizontal direction, is provided with a continuous zone of fluidization extending around the bend so to speak. This is accomplished by providing a gas porous liner in the duct with a portion thereof extending into the chamber to eliminate settling in the feed throat. Witha generally rectangular chamber the depth of fluidization is increased by a gas dispersing porous surface arranged on each side of the chamber and angled upwardly into the entering material at an angle greater than with respect thereto so as to sweep a considerable depth of material above the bottom of the chamber (and above the diffusing surfaces) In Fig. 1 the material-feeding device of the present invention is shown to be incorporated in a bag-filling machine of an ordinary type. The basic housing of the device is that of a screw-feed type of housing modified by the removal of the screw and the addition of a fluidizing horn or spout and auxiliary porous air diffusing surface or surfaces inside the chamber. As shown, the machine of Fig. 1 comprises a base or stand 10 on which is supported a scale arm 11, the arm 11 being supported, in the usual fashion, ona knife blade (not shown) integral with the arm and resting on a pivot block 11a secured in base 10. On the same block 11a there is supported, in a similar fashion, a second arm 12 which has in its right hand end 13 a knife blade 13a which makes contact with the corresponding end 14 of arm 11. The combined total of (1) the tare weight of arms 11, 12, of the to-bedescribed equipment attached to arm 12, and of the desired bag weight, are set: on the left hand of the scale arm 11 by means of large sliding weight 15. The weight 15 is advanced and retracted by means of a screw 16 secured in an upwardly-projecting bracket 17 integral with the end of arm 11. The weight 15 counterbalances both the weight of the material-feeding device, indicated generally in Fig. 1 by the numeral 18, and the weight of the bag mounted on the horn.

The material-feeding device is flexibly-connected, by means of a flexible bellows-type connector 19, to a downwardly-inclined vibratory conveyor duct 20. Material flowing down duct 20 drops into device 18 by gravity. The material-receiving chamber thus includes the lower housing and a portion of the height of bellows 19. Material is continuously fed to conveyor 20 from a gravity feed supply hopper 21, the latter being flexibly connected to the duct 20 by means of a flexible bellows connector 22. Thus the feeding device 18 and the supply hopper 21 are isolated one from the other so that the static head of material imposed on the feeding device 18 is small and even in a large machine need not be more than 1 or 2 feet. This separation between supply hopper and bag-filling machine makes it possible to install the latter anywhere, even where the available ceiling height is small. The supply hopper 21 could even be located below the device 18, provided the conveyor 20 were an elevator style conveyor. The hopper 21 could also be located on a floor above the bag-filling machine, or in a different room or building;- r

The material-feeding device comprises an outer housing 30, generally rectangular in shape, to which is connected a horizontal bag-filling spout or duct 31, better known as a horn because of the shape imparted to its outer end for ready insertion in an end-opening bag. bag 32 is slid onto the horn 31 and 'held in place thereon by means of a weighted clamp arm 33 which is pivotally secured to the housing 30. t

The weight of the bag 32 and its contents tends to rotatearm 12 in'a clockwise direction, as viewed in Fig. 1, the knife blade 13a making contact with end 14 of arm 11 and rotating the latter in the same direction. Secured in the knife blade,or otherwise rigidly connected to arm 11, is a valve-actuator arm 34, the arm 34 normally engaging the buttonof anorrnally closed spring-load electrical switch 35 when the bag is being filled. When closed, the switch 35 in turn maintains energization of the solenoid coil of a normally-open solenoid air valve 36. Thus, clockwise rotation of arm 11 causes switch arm 34 to disengage the switch and allow valve 36 to close, cuttingoff air to the bag-filling machine. Closing of valve 36 cuts off the flow of air through line 37 and causes the flow of material to bag 32 to cease when the desired weight of material has been delivered.

The valve actuator arm 34 is provided with a locking device or hold'closed bracket 39 which prevents reopening of the valve 36 when a freshly-filled bag is removed fromthe horn. After an empty bag is in place on the horn the operator grasps thehandle 40 of arm 34 and releases the valve-actuator arm, thereby engaging switch 35 and opening valve 36 to start the air flow. When desired,the valve handle can be operated manually to stop the flow of material.

Referring now to'Figs. 2 to 4, it will be seen that the feeder device '18 is a box-like outer chamber 30, closed at the top where bellows 19 is seated around an upstanding flanged opening 50. The outer casing 30 comprises two vertical end plates 51 which taper slightly toward the'bottom, a pair of inclined side plates 52 having horizontal flanges 53, a flat cover plate 54 which carries the bellows retaining flange 50, and a bottom support plate or bracket 55. The end plates,'bottom support plate, and side plates are welded together while the top plate 54 is removably secured by bolts tapped into the flanges 53 and end'plates 51. A gasket 56 is provided to seal the cover plate 54.

The bottomof'the housing 30 is formed of a section of-pipe, a portion of its circumference being cut away and the remaining arcuate section welded over the side plates 52 so as to form an arcuate bottom 57 to the housing 30. The arcuate bottom -57 is the screw bore or housing of the originalscrew feed machine. This arcuate bottom,-however, is very useful and, together with the slanting sidewalls, forms a-housing very easily fluidized because its cross-sectional area'becomes smaller towards the bottom.

Inside the outerhous'ing 30 thus described, there is provided a pair of opposed,upwardly-inclined or slanting plates 60, each such platehavinga horizontal lip 61 secured between'flanges 53 'andtop plate 54. The lower edges of plates 60 are cut on a bias so as to be aligned with the lower edges of the outer side plates 52', but the lower edgesof the plates are not secured together. More will be said below about the angle of inclination of the plates 60. "The space between each pair of plates 52, 60 forms an air chamber or air jacket 63, one on either side of the housing 30.

Air is supplied to'the air chambers 63, in a manner to be described below, through line 37,-the latter being attached to a hose-type fitting 62 tapped through the cylindrical bottom section 57 of the outer housing. Holes 64 bored in plates 52 interconnect chambers 63 with the bottom section 57.

Secured in about the center of each'of the inclined portions of plates 60 is a rectangular plate like-insertv65 of porous (sintered) bronze of the type which will be readily permeable to air at pressures below about 10 p.s.i. gage. The porous plates 65 are thicker than plates 60 and are secured into the latter with a flange on the air chamber side, the plates 65 being merely pressed into the openings in the air chamber plates 60. Thus air entering air chambers 63 will flow through the porous plates 65 and will be eificiently dispersed into the pulverulent material entering the housing.

The a'ir chamber plates '60 are inclined upwardly at an angle greater than with respect to the material entering housing 30 such that air flows through the material on intersecting .pathways sweeping completely across the stream of material and fluidizing a considerable depth of material above bottom '57 (and above the porous plates 65). This depth of fluidization is believed to (1) eliminate bridging and (2) reduce not only the air pressures requiredbut also the static head of material required for good operation.

Inside the horn 31'there is disposed a circumferentially continuous porous bronze liner '66 which is supported therein by a top shoulder 67, an end-sealing brass ring 68,and several -pairs of radially-disposed, adjustable support-studs 69 disposed along the liner as will be described below.

A portion of the upper circumference of porous liner 66 is cut away so that the lower half 66a can fit against against a'shoulder or recess 60a in the outer, lower edge of 'each of side plates 52, thereby forming an air seal. The open, lower'half'66a of liner 66 thus extends the length of bottom housing section 57 forming therewith an arcuate air chamber 71.

An arcuate air passageway 72 connects air chamber 71 with an annular air chamber 70 defined by horn 31 and liner '66. Thus air'entering fitting 62 will be distributed through air chambers 63, 70 and 71 and will be applied to all porous bronze surfaces. The result is a unique type of 'fluidization in which practically the entire body of pulverulent material within the 'housing 30 and horn 31 is maintained in a fluidized condition. Since there is no other way for the air to escapeythe material will flow smoothly around the corner into the horn 31, the air-blanketprovided by the extension 66a of the horn liner 66 preventin'g'blocking of the feed throat. Inside the horn' liner 66, the circumferentially continuous-nature of the air flow maintains the fluidization and there is no opportunity'for material to settle out, bridge or otherwise obstruct thehorn.

With air flowing through plates 65 onupwardly inclined, intersecting pathways a considerable depth of material in the top portion of housing 30 and even into bellows 19 will be fluidized. At the bottom, the liner extension 66a diffuses air in all directions completely cushioning the bottom and sweeping the edges of plates 52, 60 so that material falling out of suspension at the plates (below diffusers 65) will be refluidized. Since the cushion of fair supplied by the liner 66 is continuous from the housing 30, into'and through horn 31, there is no tendency for material to settle out at the feed throat or entrance to thefhorn. Moreover, the slanting plates 60 funnels the material, through a decreasing crosssectional area into the radially dispersed cushion of air supplied by the liner extension 66a.

In use, a most unexpected feature of the material feeding device is the quick collapse of the fluidized zone. Deliveryofmaterial ceases almost instantly when the flow of air is cut .011. Moreover, when theflow of .air is resumedLdelivery of material commences equally as promptly. Asa result, accuracy as great .as plus or minus 0.1 lb. is obtained when filling 50.1b. bags. In addition, the machine is so consistentlywaccurate that it is necessary to check weigh only a few bags during a long period of operation, as a mere precautionary measure.

.Aturthertdesirable.feature or the .bagrfilling machine is its eificient operation with very small heads of material and low air pressures. In a full size machine for filling 50 lb. bags with very finely divided polyvinyl chloride paste resin proper operation is obtained with less than one foot of material in the casing 30 and supply coupling 19. This low head requirement shows that fluidization supplies substantially all of the energy required for moving the material whereas in known types of bag-filling machines employing fluidization, hoppers containing 9 or feet or more of material are required for proper operation. Air pressures of less than 25 lbs./ sq. in. are suflicient, although excellent results are obtained with 3 to 10 lbs/sq. in. In the machine illustrated in which the horn has about a 4 inch I.D., only about 200 cubic feet per hour of air at 6 lbs./sq. in. is found to be sufficient for adequate fluidization.

Another most surprising result obtained with the machine of the drawings is a saving of almost 10 percent on bag costs. I It was found that 50 lbs. of very fine polyvinyl chloride paste resin could be packed into 40 lb. bags. This resin must be maintained in its free-flowing, small particle-sized condition. It was found that the resin suffered no milling, compacting or agglomeration during the bagging operation. Strangely enough, there is less of a dusting problem with the machine of this invention than is normally encountered with other types of machines employing screw or other types of material-feeding devices.

It is to be understood that the porous plates 65 and horn liner 66, indicated as being made of air-porous sintered bronze, can be made of any air or gas porous material such as perforated metal, fine screening, felt padding, porous ceramics, and others. The sintered bronze is preferred because it can be obtained in nearly any porosity, it is easily worked and it has high structural strength and resistance to abrasion.

In the above description, it is also to be understood that the exact placement of the various air porous surfaces can be varied and that the principle can be employed in housings having different shapes and configurations from the illustration. The essential feature, in a feeder designed to feed material through a duct or horn at a substantial angle (i.e. 90) to the direction of flow of the material supply, is a circumferentially-continuous gas diffusing means in the horn extending through the feed throat into the supply chamber proper. These can be formed by one porous lining as is shown in the drawings or by two or more separate difiusers arranged to supply fluidization of the type described. When a bag-filled machine is operated with a fluidizing horn of this description, but without diffuser plates 65 or their equivalent, effective operation is secured but greater static heads of material must be imposed on the chamber to insure ready flow of material.

Iclaim:

1. In a material handling apparatus having a materialreceiving chamber means and a material-conveying means connected at a substantial angle, the combination therewith of a first gas dispersing means located in said conveying means, a second gas dispersing means located in said chamber means and forming a continuation of said first gas dispersing means so that both said first and second gas dispersing means combine to supply a continuous cushion of fluidizing gas extending from said chamber means through the region where the said conveying means intersects the said chamber means to the discharge end of said conveying means, and additional gas dispersing means in said chamber means so arranged between said second gas dispersing means and the material entry of said material-receiving chamber as to disperse gas in said material to a considerable depth over said second gas dispersing means.

2. In a'bag-filling machine having a gravity-supplied material-receiving chamber and a material-conveying horn connecting therewith at about a right angle, the

combination comprising a circumferentially-continuous, gas-porous lining in said horn, a gas-porous lining located near the bottom of said chamber, said gas-porous linings being adapted to supply a continuous cushion of gas extending from said chamber through the region where the said horn intersects the said chamber to the discharge end of said horn, additional gas-porous surfaces disposed in said chamber above the said bottom gas-porous lining and arranged to fluidize a considerable depth of material above said bottom gas-porous lining, and means for supplying gas under pressure to said linings and said surfaces.

3. In a bag-filling machine having a material-receiving chamber adapted to receive material by gravity and a generally horizontal bag-filling horn connected to said chamber, the combination comprising a circumferentiallycontinuous, gas-porous lining within said horn, a gasporous lining disposed near the bottom of said chamber and forming a continuation of said horn lining, said horn lining and its said continuation being adapted to provide a continuous cushion of gas extending from the chamber through the region where said horn joins said chamber to the discharge end of said horn, gas dispersing means in said chamber disposed above the last-named said lining extension and angled upwardly into incoming material, and means for supplying gas under pressure to said linings and said gas-dispersing means.

4. A bag-filling machine comprising a gravity-fed material-receiving chamber and a horizontal bag-filling horn, a circumferentially-continuous, gas-porous lining in said horn supported in spaced relation with the inside surface of the horn, an extension of said lining disposed in said chamber and supported in spaced relation with the inside surfaces of the latter, said last-named extension and the said horn lining being adapted to provide a continuous cushion of gas extending through the throat of the horn to its discharge end, an inclined plate disposed on each side of said chamber and spaced from the inner surfaces of said chamber, said plates being inclined so as to define a space decreasing in cross-sectional area toward the bottom of said chamber, gas porous areas in said plates disposed so as to fluidize a considerable depth of material above the said lining extension, and means for supplying gas under pressure to all the spaces defined between the chamber and horn, on the one hand, and the gas porous linings and areas, on the other hand.

5. In a bag-filling machine having a material-supplying means and a bag-weighing means, the combination therewith of a material feeding device comprising a material-receiving housing adapted to receive material from said supplying means by gravity flow, a horizontal bag-filling horn communicating with the interior of said housing, a circumferentially-continuous, gas-porous lining circumferentially spaced within said horn and having an extension extending into and spaced above the bottom of said housing, an inclined plate mounted on each side of said housing and spaced therefrom said plates defining an internal space tapering down to said liner extension, a gas porous area in each said inclined plate, and means responsive to said bag-weighing means for supplying gas under pressure to the spaces defined between the said gas porous horn lining and the said horn and between the said horn lining extension, the said inclined plates, and the said housing.

References Cited in the file of this patent UNITED STATES PATENTS 862,231 Bates Aug. 6, 1907 2,181,756 Cook Nov. 28, 1939 2,316,814 Schemm Apr. 20, 1943 2,466,386 Curioni Apr. 5, 1949 2,527,466 Townsend Oct. 24, 1950 2,770,439 Stafford Nov. 13, 1956 2,795,389 Aust June 11, 1957

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