US3516454A - Packing apparatus - Google Patents

Description

June 23, 1970 B. A. SMITH 3,516,454

PACKING APPARATUS Fil ed Feb. 28, 1966 4 Sheets-Sheet 1 74 m m m m H4 H2 95 04 I64 INVEN'I'OR BAR T A. SMITH A'ITORNEY June 23, 1970 SMITH 3,516,454

PACKING APPARATUS Filed Feb. 28, 1966 4 Sheets-Sheet 2 BI 84 e2 84 F'IG :EI

INVENTOR BART A. SMITH BY M M ATTORNEY June 23, 1970 B. A. SMITH PACKING APPARATUS 4 Sheets-Sheet 5 Filed Feb. 28, 1965 INVENTOR BART A. SMITH BY [(j W ATTORNEY United States Patent 3,516,454 PACKING APPARATUS Bart A. Smith, San Jose, Calif., assignor to FMC Corporation, San Jose, Calif., a corporation of Delaware Filed Feb. 28, 1966, Ser. No. 530,552 Int. Cl. B65b 1/16 US. Cl. 14168 3 Claims ABSTRACT OF THE DISCLOSURE A pressurized chamber is used to fill dry, fluidizable material into a bag which has been placed upon a filling nozzle projecting from the bottom of the chamber. When the bag is being filled, both fluidizing and pressurizing air is conducted into the chamber while the material inlet at the top of the chamber is sealed. When the bag is filled, control means closes the filling nozzle and the pressurizing air inlet and opens the material inlet to allow material to enter the chamber from an overhead hopper while the air in the chamber exhausts through said material inlet. At the end of a predetermined and regulatable period of time, the material inlet is again sealed and the chamber is repressurized to await the operators initiation of another bag filling cycle.

The present invention pertains to packing apparatus, and more particularly to a machine for packing flexible bags with dry, fluidizable, powdered or granular products.

Fluidized packing apparatus for powdered or granular materials has achieved general usage in the packaging industry in recent years in packing a wide variety of materials into bags, with cement, sugar, and the various dry chemicals and fertilizers being typical examples of such material. These structures operate under the principle of fluidization in which a low pressure air source is incorporated in the material supp-1y bin near the outlet spout to place the dry material contained therein in a fluid" condition when it is discharged into bags or other suitable small containers. Generally, this fluidizing air is introduced into the supply chamber at low velocities through a porous pad and is allowed to percolate up through the powdery or granular product. As the air surrounds each of the tiny particles of the material, the particles are freed to move under the effects of the pressure head created by the weight of material above. Thus, a condition is achieved in the material which causes it to behave in the manner of a true fluid and this condition adapts the material for rapid filling as well as dense packing in containers.

Since products which are thus subject to fluidization are quite variable in their other characteristics such as particle size, density, and the like, it has been found that dilferent operating conditions are often required when different materials are packed with the same apparatus. In order to partially remedy some of the apparatus adjustment problems resulting from the difference in packing materials and to render fluidized packing machinery generally adaptable to a wide variety of supply bin and hopper installations, a recent development in the industry has been the use of a device known as a low head or pressure packer. In these devices, the powdered or granular material is fed into bags or the like from a conditioning or pressurizing chamber which is ar ranged to be sealed from the main supply hopper wherein the bulk of the material is stored during the intermittent bag filling operations. In addition to the fluidizing air introduced near the bottom thereof, this pressurizing chamber is provided with an additional air supply to maintain a desired pressure head upon the material while it is discharged into the bags. It is with this pressurized type of fluidized packing apparatus that the present invention is involved.

It has been found that both the filling rate of the machine and the density of the final packed material are to a large extent controlled by the pressure head upon the material in the pressurizing chamber during the filling of the bags. Furthermore, a uniform and high pressure head tends to neutralize the differences between the various materials and to achieve more uniform packing characteristics for the wide variety of materials from large cereal grains to fine cements. In order to achieve the best possible results in filling, it is necessary not only to at all times control the pressure within the pressurizing chamber but also to carefully control the amount of material in said chamber before each individual bag filling operation. The prior art devices which are in general use today have not been found to be completely dependable in this latter regard. Such devices either depend upon the operator to control the amount of material in the pressurizing chamber just prior to discharge, or they utilize additional level indicating devices which generally may not be readily adjusted for changing filling conditions.

It is, therefore, an object of the present invention to provide a packing apparatus for powdered or granular material which will achieve uniform filling characteristics for any given material through a careful control of the pressure and other conditions affecting the material as it is fed into bags or other small containers.

Another object of the present invention is to provide an improved packing apparatus for dry divided materials which places the material under pneumatic pressure as it is filled into small containers and wherein such pressure may be easily controlled and adjusted for handling a wide variety of materials.

Another object of the present invention is the provision of a fluidized filling apparatus for filling flexible bags which includes separate air sources for the fluidizing of the material within a pressurized filling chamber and for the pressurizing of the material, which sources may be separately adjusted relative to one another so as to achieve the desired fluidizing and pressurizing effects upon the material whereby both a rapid discharge of the material and an accurate final bag weight are obtained.

Another object of the present invention is to provide a fluidized filling apparatus which will automatically reset itself to predetermined ideal conditions after each bag filling cycle.

Another problem which has arisen with known fluidized filling machinery concerns the provision for allowing the excess air to escape from the flexible bags as they are filled. Formerly, bags were provided with vents which would permit a certain amount of air to be discharged without loss of material. However, with the new bag materials'such as the synthetics, which are finding increased use, bag venting is not always provided for by the bags themselves, and the filling nozzles must therefore contain some provision for venting in order to prevent bags from bursting under the filling pressures. It has been found that a carefully controlled air discharge rate is highly desirable not only from the health standpoint in reducing the hazardous dust conditions which might otherwise arise but also in providing rapid filling with high packing densities and in achieving a higher degree of accuracy in the final Weight of the filled bags as determined by the conventional counterweighted scale beam devices.

Another object of the present invention, therefore, is to provide an improved self-venting filling nozzle for a fluidized packing apparatus which will carefully control the rate of air discharge from the bag during the filling thereof, which will not be subjected to clogging or other disorders caused by unwanted accumulations of material in the venting passages, and which will permit the rate of air discharge from the bag to be modified when the apparatus is adjusted for handling a different material.

These and other objects and advantages of the present invention will become apparent from the following description and the accompanying drawings in which:

FIG. 1 is a partially diagrammatic side elevation of the packing apparatus of the present invention.

FIG. 2 is a partially diagrammatic front elevation of the apparatus shown in FIG. 1.

FIG. 3 is a front elevation of a portion of the apparatus shown in FIG. 2 particularly illustrating the pinch valve mechanism for controlling the flow through the discharge nozzle.

FIG. 4 is an enlarged diagrammatic section taken along the lines 4-4 of FIG. 2 showing the lowermost portion of the pressurizing chamber.

FIG. 5 is an enlarged diagrammatic section through the discharge nozzle of the present invention illustrating its disposition within a typical valve-type bag.

FIG. 6 is a section through the nozzle of FIG. 5 taken along the lines 6-6.

FIG. 7 is a schematic illustration of the pneumatic control system for the packing apparatus of FIG. 1.

Referring now more particularly to the drawings, FIG. 1 shows one embodiment of the packing apparatus 20 of the present invention which is seen to generally comprise a pressurizing tank 22 adapted to receive material from an upper storage bin or hopper 24 and to discharge the material intermittently into bags through a discharge nozzle 26 projecting forwardly from the lowermost portion of the tank. Flow from the upper hopper into the pressurizing chamber of tank 22 is through a conventional butterfly valve mechanism 27 including a cylindrical inlet conduit 28 bolted to the upper end of the tank and a butterfly valve member 29, which is arranged to be rotated into a closed position in tight sealing engagement with the wall of the inlet conduit to seal off the pressurizing chamber, as is illustrated in FIG. 1. Flow from the pressurizing chamber to the discharge nozzle 26 and into the bag or other container is controlled by a pinch valve mechanism 32, particularly shown in FIG. 3.

Briefly described, the operation of the packing apparatus 20 encompasses the placing of a predetermined quantity of dry, fiuidizable material within the pressurizing chamber of tank 22. and the closing of the butterfly valve mechanism 27 so as to make the chamber air-tight. Once the pressurizing chamber is sealed, air is directed into the chamber through an inlet 34 (FIG. 4) to place the dry product therein under pneumatic pressure. The material is continuously fluidized during this operation by means of an enclosed plenum chamber 36'at the bottom of the pressurizing chamber which directs air to the material through a porous membrane 37 and places it in the aforedescribed fluid condition. A bag B (FIGS. 5 and7) which is to be filled is placed upon a pivotable bag chair 40 with an inlet valve V of the bag tightly engaged with the discharge nozzle 26. The bag and the discharge nozzle are then brought into contact with a bag clamp 42 so as to retain the bag in an upright position upon the bag chair during the filling operation which is simultaneously initiated by the opening of the pinch valve mechanism 32. When the bag reaches a predetermined weight, a scale mechanism 44 supporting the bag chair is tripped to actuate a pneumatic control circuit that removes the bag from contact with the bag clamp and permits it to pivot upon the bag chair and fall freely away from the machine.

Describing the structure of the packing apparatus 20 of the present invention in greater detail, it will be seen from FIGS. 1 and 2 that the pressurizing tank 22 is mounted upon a rectangular frame structure 45 and includes a large upper section 46 which is formed with inwardly sloping walls, with the air inlet 34 being located in the rear wall at the lower edge thereof (FIG. 4) for the introduction of the pressurizing air to the chamber of the tank. The upper tank section also includes a cylindrical opening 47 in the upper wall thereof aligned with the inlet conduit 28 of the butterfly valve mechanism 27 for the reception of material from the upper storage hopper 24. The front wall of the upper tank section includes a glass window 49 which permits the operator of the apparatus to view the conditions existing within the pressurizing chamber at all times and to quickly determine the nature of any difficulties being experienced with the material as it is packed.

The pressurizing tank 22 also includes a lower, generally inclined section, as best seen in FIG. 4, 'which is comprised of a tubular enclosure 51 bolted to the lower peripheral edge of the upper section 46 and a bottom door 52. The door is hinged to the frame structure 45 of the ma chine by means of a pair of pivot pins 53 (FIGS. 1 and 4) each of which is journalled in a hub 52a of the door and a block 52b (FIG. 1) of a frame member 4511. The rearward ends of the enclosure 51 and door 52 are removably secured together by means of a threaded hasp pin 54 which is pivotally mounted between a pair of flanges 55 (FIG. 1 and FIG. 4) extending from the rear wall of the enclosure 51, said pin being arranged to be inserted through an aperture 56 in the trailing edge of the door and tightly secured by a handle 57 threaded to the distal end of the pin to lock the door to the bottom of the enclosure. The lower enclosure 51 includes, at the lower edge of its front wall, an outlet spout 60 which is positioned just forwardly of the inclined fluidizing membrane 37 to direct the fluidizing material into the discharge nozzle 26 through a connecting flexible tube 62 of rubber or the like clamped to the cylindrical walls of the spout and to the discharge nozzle. The plenum chamber 36 which disperses the fluidizing air through the membrane 37 and into the chamber is formed as a recessed portion at the lower edge of the door. The membrane may be constructed from canvas or similar material 'which is pervious to air but which will prevent the tiny material dust particles from entering the plenum chamber. The membrane is securely affixed to the upper face of the door structure and is spaced by means of lands 66 from a fiat recessed wall at the lower edge of the door which serves to define the upper portion of the plenum chamber and extends completely across the width of the enclosure 51. The peripheral edge of the door includes an upwardly projecting lip 68 which, when the door is in its normal closed position, is adapted to main tain tight sealing engagement with a sealing strip 69 of neoprene, or the like, circumscribing the lowermost edge of the tubular enclosure 51. Thus, when the hasp handle 57 is securely tightened, the door 52 provides the inclined lowermost surface of the pressurizing chamber and directs the powdered or granular material contained within the chamber toward the outlet spout 60. It will be noted that the plenum chamber and its enclosing membrane are located at the lowermost forward portion of the pressurizing chamber so that the material adjacent the outlet spout will be most effectively moved to the discharge nozzle in a completely fluidized condition. By removing the hasp handle 57, the door 52 may be swung downwardly so that the interior of the pressurizing chamber can be cleaned out periodically or so that other adjustments may be made to the chamber or its appurtenances.

As previously mentioned, flow through the discharge nozzle 26 is controlled by means of a pinch valve mechanism 32 which is positioned around the flexible sleeve 62 that is attached at its ends to the discharge nozzle and to the outlet spout 60. The pinch valve is best illustrated in FIG. 3 and will be seen to comprise an air-operated cylinder 74 and piston 78, the cylinder being vertically mounted upon a bracket 76 that is rigidly secured to the for-ward face of the frame 45 of the machine. The piston 78 is directly aflixed to an upper pinch bar 80 which is arranged to be actuated in conjunction with a lower pinch bar 81 between which the flexible sleeve may be tightly squeezed to completely block the outflow of material from the pressurizing chamber. The pinch bars are interdependently controlled by means of tWo identical bellcrank linkages on either side of the sleeve, each of which includes an elongated link 84 pivotally connected at its lower end to the lower pinch bar 81, a short link 85 pivotally connected at its lower end to the upper pinch bar 80, and a bellcrank 86 pivotally connected to the bracket 76 and to each of the links 84 and 85. When the piston 78 is in its uppermost position (as shown in FIG. 3), the pinch bars 80 and 81 are spaced far enough apart so that the flexible sleeve is fully open to allow the flow of material therethrough. When the piston 78 is moved to its lowermost position, by means to be described hereinafter, the links 84 and 85 are moved relatively to one another to bring the pinch bars together and squeeze the tube, thereby stopping the flow of material. A pair of compression springs 90 are mounted about rods 91 which are fixed to the lower pinch bar 81 at each end thereof and extend through the upper pinch bar 80, the springs aiding in maintaining the valve in the closed, tube-pinching position. For a further and more complete description of the pinch valve mechanism, reference is made to the Letters Patent of Neil S. Stafford et al., Pat. No. 2,770,439, which shows and describes a generally similar device.

The bag clamp 42 (FIG. 1) is ready to operate once the bag B which is to be filled is placed by the operator upon the discharge nozzle 26. The nozzle and bag are adapted to be moved upwardly together into engagement with a pair of resilient clamp elements 94 overlying the discharge end of the nozzle. Clamp elements 94 are stationarily supported by a bracket 95 which is fixed at its rearward end to a vertical support column 96 that is mounted upon the scale mechanism 44 and parallels the forward face of the machine frame structure 45. Welded to an enlarged portion 100 at the rearward end of the discharge nozzle is a bracket member 102 (FIG. which includes a pair of upwardly extending ears 104 straddling the nozzle. Each of the upstanding ears is pivotally mounted by means of pivot pins 106 to the vertical support column 96. The upper ends of the ears are pivotally connected to the trailing end of a piston rod 112 which is moved within an air cylinder 114. When the cylinder 114 is actuated, by means to be described hereinafter, to move the piston rod 112 realwardly, the discharge nozzle is raised into bag clamping engagement with the clamp elements 94 as the bracket 102 is pivoted about the axis of the pins 106.

While the upper end of the bag B is being gripped upon the discharge nozzle 26, the lower end will be positioned upon a pair of curved seating elements 120 of the bag chair 40 with the vertical edge of the bag resting against a curved back rest member 122 attached to the seating elements 120 by means not shown. As best seen in FIG.

2, the back rest member 122 comprises two separate elements which are adjustably fastened together so that the back rest may be vertically shortened or extended to accommodate various sized bags. The seating elements: are adjustably affixed to a pair of pivotal bracket members 124 which are rotatably mounted upon a pivot shaft 125. The pivot shaft is mounted between a pair of sup port brackets 126 that extend forwardly from and are vertically adjustably attached to the vertical support column 96. When the upper end of the bag is released by the bag clamp 42, the weight of the filled bag will cause the bag seating elements 120 and their associated support brackets 124 to pivot forwardly about the axis of the pivot shaft and allow the bag to fall freely away from the machine. Tension springs 128 are mounted between the associated brackets 124 and 126 to return the seating elements 120 to their normal generally horizontal positions (FIG. 1) when the bag has been discharged.

The scale mechanism 44, best seen in FIG. 1, comprises a pair of parallel scale beams 130 which rest at their center arched portions upon knife edge supports 132 mounted upon the frame structure 45 of the machine. The forward edges of the scale beams include knife edge supports 134 which are arranged to be received within scale cups 136 attached to the vertical support column 96. The forward end of the scale beams therefore pivotably support the support column 96 and its attached devices including the bag chair 40 and the bag clamp 42. A counterweight 140 is pivotally attached to the scale beams near the trailing ends thereof to balance the major portion of the weight to be applied to the scale by the filled bags. A threaded, horizontally positioned rod 142 is also rigidly attached to one of the scale beam members (FIG. 1) and includes a hand crank 144 at its forward end. A small poise weight 146 is threadedly mounted upon the rod 142 and is also slidably mounted upon a rod 148 attached to the rod 142 to extend in parallel relationship thereto. The operator of the machine, by rotating the rod 142 through the hand crank 144, may vary the position of the poise weight and thereby adjust the scale for different bag weights. Depending from the rearward edge of the scale beams is a trip lever arm 150 which includes at its outer edge a contact member 152 adapted to actuate the pneumatic control system, in a manner to be explained hereinafter, when the scale beams are pivoted about the knife edge supports 132. The scale mechanism 44 as well as the previously described bag chair 40 and bag clamp 42, are generally similar to analogus devices disclosed in a prior United States patent to Rose, No. 2,866,484, and reference in herein made to said patent for a further and more complete description of the structure and operation of these mechanisms.

FIG. 7 schematically illustrates the pneumatic control system for the machine. Incoming air from a compressor or similar apparatus is directed from a line through a filter 162 to a branch line 163 which directs the air into the plenum chamber 36 at the bottom of the pressurizing chamber of tank 22 for fluidizing the material therein. Line 163 includes a conventional pressure regulating mechanism 164 for reducing the pressure to a relatively low pressure which, for use with most dry, fluidizable materials, is generally between 5 and 10 p.s.i.g. A separate low pressure-high volume blower is provided for supplying the pressurizing air by means of a line 172 connected to the pressurizing chamber inlet passage 34. The pressure in the line 172 is regulated by means of a conventional pressure regulator 174 so that it is just slightly less (from one to three pounds with about one pound preferred) than the pressure in the fluidizing pressure line 163.

A second branch line also receives air from the inlet line 160 and includes a pressure regulator 182 which regulates the pressure in the line 180 to a value considerably higher than the fluidizin-g or pressurizing air, in the neighborhood of from around 60 to around 80 p.s.i.g. under normal operating conditions. The high pressure air in line 180 is directed by means of a line 184 through a conventional four-way pneumatic control valve 186 (pilot-operated) to one of two lines 188 and 189 which control the operations of the air cylinder 114 of the bag clamp 42 and the air cylinder 32. Valve 186 may be of the type marketed by Bellows-Valvair Division of I.B.E.C., Akron, Ohio, under the designation of Special BarmC-20 motor.

Incoming high pressure air in line 180 is also directed to a line 190 and through a four-way pneumatic control valve 194 (pilot-operated) with a special time delay feature and to one of two lines 195 or 196 which supply air to and exhaust air from an air cylinder 198 controlling the operation of the butterfly valve 27, and to an air cylinder 199 which controls the admittance of the pressurizing air to the pressurizing chamber from the line 172. Air cylinder 198 operates a piston rod 202 which is connected to an externally extending shaft of the butterfly valve member 29 by means of crank arm 203. Air cylinder 199 operates a piston rod 205 which includes a closure member 206 at its inner end arranged to be moved into a position to block the supply of air from the line 172 to the pressurizing chamber.

The time delay valve 194 includes a conventional fourway valve spool 210 which normally occupies the position shown in FIG. 7 to admit high pressure air to line 195 and permit line 196 to exhaust. When the pneumatic control circuitry is actuated to bleed off air from the left side of the valve (as viewed in FIG. 7), the valve spool will be shifted to the left to reverse the pressurizing air from line 195 to 196 and thereby close the inlet 34 to the pressurizing chamber and open the butterfly valve 27 to permit the product in the upper hopper 24 to gravitate into the pressurizing chamber. The adjustable time delay mechanism 212, by restricting the flow of control air seeking to rebalance the pressure on the valve spool 210, causes the valve spool to be automatically shifted back to the position shown'in FIG. 7 only at the end of a predetermined amount of time which time will correspond to the time necessary to refill the pressurizing chamber with an amount of material approximately equal to that discharged during the bag filling portion of the operating cycle. Under normal operating conditions with a typical fluidizable material, this time will be about two and one-half seconds. An air-operated four-way valve suitable for use with the present invention is Valve Model No. F1013C-02Al manufactured by the C. A. Norgren Co. of Littleton, Colo., which includes an adjustable time delay mechanism allowing the time during which the valve spool 210 remains shifted in its alternate position to be varied from between zero and five seconds.

The control valve 186 is moved to the position shown in FIG. 7 by means of a conventional pneumatic control system which is initiated manually by a start button 220 which actuates a poppet'bleed valve located on the font face of the machine to bleed oil pressure from the left end of the valve (FIG. 7). This position of the control valve 186 corresponds to the bag filling portion of the operating cycle, as is apparent from FIG. 7. The valve 186 may be shifted to its alternate position either by means of a stop button 222 on the front face of the machine which actuates a poppet bleed valve to reverse the operation of the start button, or, automatically, by means of the scale stop button 224 which actuates a similar poppet bleed valve and which is adapted to be pressed by the contact member 152 of the scale mechanism 44 when the scale beams 130 are shiftedas the bag attains the desired full weight. As can be seen from FIG. 7, the manual stop button 222 and the scale stop button 224 also serve to bleed 013? control air pressure to shift the time delay valve 194, which valve will then be reset automatically after a predetermined time delay as previously explained.

The control valve 186, however, will remain shifted in one of its two alternate positions until one of the appropriate actuating buttons 220, 222 or 224 is pressed. If desired, means can be incorporated in the control system to prevent actuation of the bag filling operation until after the time delay valve has been reset. Such means, for example, might take the form of a continuous pressure bleed off on the right side (FIG. 7) of the control valve 186 until the time delay valve 194 is shifted back to the FIG. 7 position.

In operating the device of the present invention the operaotr first places an empty bag B upon the discharge nozzle 26 with the nozzle inserted into the bag valve V in tight engagement therewith (FIG. 5). He then presses the start button 220 to shift the valve 186 into the position shown in FIG. 7 allowing the high pressure air from line 184 to enter the air cylinder 114 to raise the discharge nozzle 26- and bag into engagement with the bag clamp 42. The high pressure air from line 184 is simultaneously directed to the air cylinder 74 to move the piston 78 to its uppermost position and allow the fluidized material to be discharged from the pressurizing chamber 22 into the bag. Before the operator presses the start button, the piston rods 202 and 205 will automatically have been moved to the positions shown in FIG. 7 whereby the butterfly valve-27 will be closed and tightly sealed and the inlet 34 to the pressurizing chamber will be open so that the pressure of the air in the line 172 will maintain a constant pressure head upon the material in the chamber. This pressure head will result in a rapid discharge of the material through the discharge nozzle and in a high packing density in the bag.

When the bag reaches the predetermined proper weight, the contact member 152 supported by the scale beams will be caused to press the scale stop button 224 and shift the valve 186 to the right and the valve spool 210 to the left, as seen in FIG. 7. This 'will cause the pinch valve 32 to operate to block the flow of material to the discharge nozzle, and it will cause the piston rod 112 to be moved forwardly to release the bag from the clamp 42 and allow it to fall freely from the machine. Also, the pressure will be removed from line and directed to line 196 to reverse the position of the piston rod 205 and thus block the admittance of the pressurizing air to the pressurizing chamber and to reverse the position of piston rod 202 to open the butterfly valve mechanism 27 and allow additional material to enter the chamber. While former devices of the type described used venting means to rid the pressurizing chamber of excess air during its recharging, it has been found particularly desirable in connection with the present invention to allow the pressurizing air from the chamber to discharge past the incoming material and through the butterfly valve mechanism 27. It has been surprisingly found that this does not slow up the recharging of the pressurizing chamber but, in fact, promotes it since the upwardly traveling air tends to at least partially tfluidize the incoming material and prevent any bridging or clogging effects in the upper hopper. After the predetermined time delay, the valve spool 210 will again shift to the position shown in FIG. 7 to direct the pressurizing air to line 195 which, in turn, closes the butterfly valve and opens the inlet 34 to pressurize the chamber. In order to obtain the best results in the operation of the machine, there should be from one and one-half to two bags of material left in the pressurizing chamber when the bag on the scales is filled. This will insure against over-pressurization of the bag and prevent the fluidizing air from the plenum chamber 36 from blowing air holes in the material left in the pressurizing chamber and thereby decreasing the fluidizing effectiveness.

A further feature of the present invention resides in the particular construction of the discharge nozzle 26. It has beenfound that it is highly desirable to control the discharge of air from the bag during the filling portion of the operating cycle. The controlled discharge of air from the bag will promote faster initial filling with a desired slowing of filling as the last few pounds of material are placed in the bag. This latter feature is highly desirable since it contributes to greater accuracy in final bag weights. In order to accomplish this controlled discharge of air, the discharge nozzle is made self-venting and is provided with three grooves 230 (FIG. 6) which allow the air to exit past the bag valve as the bag becomes nearly full. It will be noted that the grooves are on the underside of the discharge nozzle, and, therefore, will not become clogged with material from the bag which will tend to gravitate from the grooves. This feature is particularly important since it is desirable to maintain unifonnity in the air discharge rate in order to attain the desired filling speeds and high packing densities. Since bags vary as to their provisions for air discharge during filling, and since different products will require different rates of air discharge from the bags, it is important that the means for air discharge be capable of ready modification. In the present instance, the rate of air discharge is determined by the cross-sectional area of the grooves 130 and these can be widened or plugged rather easily. Furthermore, new grooves can be added if it is desired to considerably increase the rate of air discharge from the bags. While not shown, it is to be understood that a conventional dust shroud should be placed about the discharge nozzle to prevent the dust and powdery material that is discharged past the nozzle from becoming a serious health and safety hazard.

From the foregoing description, it will be apparent that the packing apparatus of the present invention is particularly advantageous for operating upon a wide variety of powdered or granular products since it is designed to be easily adjusted for handling different materials. The feature whereby the pressurizing chamber is automatically open for only a predetermined time interval to allow the chamber to be filled after each bag filling cycle with an exact amount of material is of particular importance since this promotes uniformity in the conditions which determine the filling characteristics. The problems encountered in having too little material in the chamber or in having too much material in the chamber are thereby eliminated. Furthermore, the eifective operation of the butterfly valve in introducing material into the pressurizing chamber is assured since the valve will never have to operate with a full supply of material in the chamber and a blocked inlet. An additional advantage of the present invention can be seen in the design of the discharge nozzle which allows for a predetermined rate of air discharge so that the bags can be filled at the desired rates.

While but one embodiment of the invention has been shown and described, it will be understood that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.

The invention having thus been described, what is believed to be new and desired to be protected by Letters Patent is:

1. Apparatus for packing dry fiuidizable material comprising a conditioning chamber having at its upper end a material inlet for receiving said fiuidizable material and at its lower end a material outlet for discharge of a predetermined amount of the material to a container, a hopper positioned directly above said chamber, said hopper having an outlet at its lower end connected to said chamber material inlet, inlet valve means positioned in said material inlet for opening and closing said inlet to the flow of material into said chamber and for sealing said inlet when closed to prevent the escape of air from said chamber, outlet valve means for opening and closing said chamber outlet to control the flow of material therethrough, a first air supply inlet in said chamber, means for supplying a dispersed stream of fiuidizing air to said chamber through said first air supply inlet near said chamber outlet and for preventing air from exhausting from said chamber through said first air supply inlet during the refilling of the chamber with material, a second air supply inlet in said chamber, means for supplying pressurizing air to said chamber through said second air supply inlet to create a pressure head upon the material within the chamber and for preventing air from exhausting from said chamber through said second air supply inlet during the refilling of the chamber with material, both said pressurizing air supply means and said fiuidizing air supply means providing air in the range of from about 5 p.s.i.g. to about 10 p.s.i.g., and control means for closing said outlet valve means while opening said inlet valve means and stopping the flow of pressurizing air to said chamber, said material inlet and said material outlet to said chamber and said first and second air supply inlets comprising the only openings in said chamber whereby the pressurized air in said chamber at the time when said outlet valve is closed will be forced to exhaust past said inlet valve to partially fiuidize the incoming material from said hopper and to prevent bridging of said material in said inlet.

2. Apparatus for packing dry fiuidizable material as set forth in claim 1 wherein the pressure of said fluidizing air is slightly greater than that of said pressurizing air.

3. Apparatus for packing dry fiuidizable material comprising a conditioning chamber having at its upper end an inlet for receiving said fiuidizable material and at its lower end an outlet for discharge of a predetermined amount of the material to a container, a hopper positioned directly above said chamber, said hopper having an outlet at its lower end connected to said chamber material inlet, inlet valve means positioned in said material inlet for opening and closing said inlet to the flow of material into said chamber and for sealing said inlet when closed to prevent the escape of air from said chamber, outlet valve means for opening and closing said chamber outlet to control the flow of material therethrough, a first air supply inlet in said chamber, means for supplying a dispersed stream of fiuidizing air to said chamber through said first air supply inlet near said chamber outlet and for preventing air from exhausting from said chamber through said first air supply inlet during the refilling of the chamber with material, a second air supply inlet in said chamber, means for supplying pressurizing air to said chamber through said second air supply inlet to create a pressure head upon the material within the chamber and for preventing air from exhausting from said chamber through said second air supply inlet during the refilling of the chamber with material, both said pressurizing air supply means and said fiuidizing air supply means providing air in the range of from about 5 p.s.i.g to about 10 p.s.i.g, and control means for closing said outlet valve means while simultaneously opening said inlet valve means and stopping the flow of pressurizing air to said chamber after said predetermined amount of material has been discharged to said container, said control means including time delay means for closing said inlet valve means and resuming the supply of said pressurizing air to said chamber after said inlet valve means has been open a predetermined period of time and while said outlet valve means remains closed so that said chamber will contain a predetermined amount of material at a predetermined maximum pressure when said outlet valve means is opened after said predetermined period of time to discharge said material, said control means further including manually actuatable means for opening said outlet valve, said chamber having openings only at said inlet and said outlet and at said first and second air supply inlets whereby when said outlet valve means is closed and said inlet valve means is opened excess air in said chamber will be expelled through said inlet and past the incoming material.

References Cited 3,159,432 12/1964 OstrOWski et a1. 302 53 3,187,401 6/1965 ODonnell 81: a1. 222-195 X FOREIGN PATENTS UNITED STATES PATENTS 700,897 12/ 1964 Canada.

9 1942 Hartman 141 1'o 1, 05,452 11/1965 Germany.

LAVERNE D. GEIGER, Primary Examiner 9 Rose 6/1965 Stockel et aL 10 E. I. EARLS, Assistant Examiner 7/1966 Stockel et a1 141-68 5/1967 Van Pernis. CL

9/1955 Evans 302 53 X 141317; 222-193; 302-53.

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