IE44714B1 - Bag filling machine for powdery material - Google Patents

Description

Bag-filling machines- have been used for many years to avoid the high labour costs in bagging flowable material. In the bagging of powdery material such as flour, the first bags used were burlap or cotten bags.

These were permeable to air and hence as the bags were filled air could escape through the pores and of course some of the flour also escaped through the pores. A standard method of filling powdery material into such bags was from the bottom up. A long spout was used and the bag was raised over the entire length of the spout so that the bottom of the spout was near the bottom of the bag. Then as the bag was filled, the bag was lowered more or less in unison with the filling, theoretically to fill the bag from the bottom up without much aeration of the powdery material during filling.

The industry has recently changed from cloth bags to kraft paper bags which are less permeable to air passage but, nevertheless, still somewhat permeable.

Even more recently, however, barrier bags have come into use, these being kraft paper bags with a plastic liner: such a plastic liner does not let the air escape during filling and it has been found to be difficult to fill these bags with powdery material such as powdered milk.

Another problem that arises in the bagging of powdered milk or flour is that strict sanitary precautions must be observed. With many prior bag-filling machines using a barrier bag, after the plastic liner was filled by the machine, a man had to separately twist together the top of the plastic bag, put a twist tie on it then tuck this fastened top of tlie plastic liner down inside the kraft paper bag. The man's hands would touch the inside of the bag and therefore this was not p.irl icularly sanitary. Also it took about four or five men to operate such a bag-filling machine, and yet the machine had a low throughput, only about two to four 50pound bags being filled per minute. One reason for this low throughput was the 50-pound slug of powdered material dropped through the air and became aerated in entering the bag, and it took time for the air to escape. A certain amount of time had, therefore, to elapse after the bag was filled to allow the powdery material to settle before the bag could be closed. This limited the productivity of the men and machine.

In some cases with the old machines, so much air became entrained in the powdery material that the bag did not have sufficient capacity to contain a full '50-pound slug of aerated material and the bag would overflow.

In the case of certain prior art machines, not only would such an overflowing of the powdery material be wasteful and conducive to insanitary conditions in the region of the machine, but it could also effect the accuracy of the weighing of a filled bag by changing the tare weight of mechanism supporting the bag during the filling operation.

For instance, British Patent Specification No. 315 939 discloses a machine involving a car movable on rails on to a floor-mounted weighing scale. A frame on the car has grippers for holding a bag upright in position to be engaged by a fill spout, the bag resting on the floor of the car. As the scale weighed not only the bag and its contents, but also the entire rail car and the bag support frame, any spillage would inevitably - 4 load the rail car and frame to alter the tare weight of the arrangement.

An. object of the invention is, therefore, to provide a bag-filling machine in which spillage of powdery material, if it occurs, is unlikely to affect the tare weight of the bag-weighing arrangement and, therefore, to interfere with proper filling of bags under automatic weighing control.

Thus the invention provides a bag-filling machine comprising a base; a bag-filling station on said base; gripper means carried on said base and adapted to grip a bag near to the top thereof; actuator means to move said gripper means; a hopper for powdery material and having an Outlet; an auger in said hopper; means for controlling said actuator means to raise said gripper means and a bag gripped thereby, to position an opening of the bag on said outlet of said hopper; fill control means to control the filling of a bag on said hopper outlet; weighing means responsive to the weight on said gripper means relative to said base; drive means to rotate said auger to move material in said hopper to said outlet; and means responsive to the attainment of a pre-determined filled weight of a bag on said gripper means as determined by said weighing means to actuate said fill control means to stop the filling of said bag.

Preferably. the machine includes a primary filling station adapted to fill a bag thereat with a powdery material to a major portion of the maximum capacity of the bag, and means to shift the bag from said primary filling station to said bag-filling station to fill said bag to said predetermined weight.

In preferred embodiments, the gripper means are adapted to grip over the sides of a bag to hold its sides closed, a preferred arrangement being for the - 5 gripper means to grip over the top of the bag at its top corners.

The machine desirably includes an inner clam shell valve on the bottom of said hopper and an outer clam shell spout surrounding said inner clam shell valve, said actuator means being adapted to raise said gripper means to raise a bag gripped thereby over said outer clam shell spout.

Preferably said drive means has a first higher speed and a second lower speed, and is controlled by means responsive to the attainment of a predetermined unfilled weight by a bag being filled to change from said first to said second speed. The means responsive to said predetermined filled weight of a bag are preferably adapted to change said drive means from said second slower speed to a sto£jped condition.

The invention will be further described with reference to the accompanying drawings, in which:FIGURE 1 is a front elevational view of a machine incorporating the invention,* FIGURE 2 is a plan view of the machine of Figure 1; FIGURE 3 is an end view of the machine of Figure 1; FIGURE 4 is an enlarged sectional view on line 4-4 of Figure 1; FIGURE 5 is a perspective view showing the front of the machine; and FIGURE 6 is a closer perspective view of the front of the machine.

The drawings show a bag-filling machine 11 incorporating the invention. This machine has a base in the form of a frame 12 on which are mounted an - δ alignment station 13, a bulk or primary filling station 14, a dribble or secondary filling station 15, and a sealing and closing station 16. A magazine 17 is connected to supply bags sequentially to the machine 11. A bulk storage bin 18 that may be on the frame 12 or be separate therefrom is connected to supply powdery material to a primary conditioning station 19 that in turn supplies a secondary conditioning station 20 that then supplies the powdery material to the primary and secondary filling stations 14 and 15.

Bags are supplied sequentially from the magazine 17 to the alignment station 13 whereat the top edge of each bag is aligned at a reference line 26. Each bag is then moved laterally along the vertical plane of each bag to the bulk filling station 14 whereat the bag receives a major portion of its nominal capacity of powdery material. It then is again shifted laterally to the dribble filling station 15 whereat it receives a further portion of the powdery material sufficient to fill the bag to a predetermined calibrated weight as determined by a weight scale associated with grippers supporting the bag at this dribble filling station 15. The bag next moves to the sealing and closing station 16 where it is sealed and closed.

The magazine 17 is adapted to receive the bags standing vertically on their bottom edges with their openable ends at the top, A removal mechanism 23 having vacuum cups 24 moves against the endmost bag 25 in the magazine 17 and pulls it from the magazine to the vertical plane of the alignment station 13. The removal mechanism 23 then moves the bag upwardly to the horizontal reference line 26 to orient the top openable edge of the bag at this reference line 26. Before said vacuum cups release the bag, the bag is clamped by clamps 27 in the aligned position at reference line 26. 4471^ - 7 Front and rear movable frames 28 and 29 are shown in Figure 3 with the front movable frame 28 shown in more detail in Figures 5 and 6. These frames are similar and only the front frame 28 will be described. This front frame is supported on four arms 30 that are keyed to a shaft 31 pivoted on the frame 12. The movable frame 28 is mounted on the lower end of these arms 30 and either carries movable sprockets and a chain or, as shown, pulleys 32 and a V-belt 33. One or more motors 34, such as expansible fluid motors, are connected to the arms 30 to swing the movable frame 28 between the closed position of Figures 3 and δ and an open position as shown in Figure 5. In the closed position, the inboard runs of the V-belts 33 of the front and rear frames will engage the front and rear faces of the bag 25 near the top openable end thereof and maintain alignment of the top of the bag at reference line 26. When the belts of the movable frames 28 and 29 are closed on the bag, as shown in Figures 3 and 6, then the clamps 27 are released. A motor 35 acts through a clutch 36, shafts and universal joints to drive the two belts 33 in synchronism so that when the inner runs of the belts are closed on the bag 25, the bag will be moved from the alignment station 13 to the bulk filling station 14.

The powdery material may be contained in a bulk storage bin 18 that, for example, may be quite large and contain, for instance, 50,000 pounds of the material when full. The primary conditioning station 19 includes a container 39 that may be immediately below bulk storage bin 18 with an openable valve therebetween that will isolate the weight of the material in the bin 18 from the material in the container 39. Alternatively, as shown, a delivery screw 40 may be connected to deliver the powdery material from the bin 18 to the container 39. The level of material in container 39 is regulated - 8 by a level control 38. A second delivery screw 42 is connected to deliver the powdery material from the bottom of the primary conditioning container 39 to the bottom of a secondary conditioning container 43 at the secondary conditioning station 20. This forces the powdery material upwardly into container 43 until a level control 44 is actuated to deactivate the drive 45 of the delivery screw 42. The lower end .of the container 43 is connected by conduits 46 and 47, respectively, to first and second bag-filling hoppers 48 and 49 at the first and second filling stations 14 and 15, respectively.

Both of these hoppers 48 and 49 are funnel-shaped with clam shell valves 64 and 65 on the respective lower ends of these hoppers at the discharge outlets, and outer clam shell spouts 50 and 51 surrounding the valves 64 and 65, respectively. Augers 52 and 53 are provided in the hoppers 48 and 49, respectively, (and driven by auger motors 54 and 55, respectively. Agitators 56 and 57 are disposed in the hoppers 48 and 49, respectively, and are in the form of stirring rods disposed closely adjacent to the conical inside surface of the hoppers. These agitators are driven by agitator motors 58 and 59, respectively. The filling of the container 43 from the bottom up under the control of the level control 44 ensures that the conduits 46 and 47 and also the hoppers 48 and 49 are kept completely full of powdery material up to the covers 60 and 61 on the hoppers 48 and 49, respectively. A vacuum line 62 may optionally be connected to the upper portions of the containers 39 and 43 through a vacuum break 63 so as to maintain a partial vacuum in the upper parts of these containers 39 and 43. A vacuum probe 66 can be raised and lowered by a motor 68 to extend downwardly through the hollow stem of the auger 52 and into any bag 25 being filled at the bulk filling station 14.

Gripper means are provided to support the bags 25 from a position near the top of the bag. These means - 9 may be constituted by one set of grippers but as shown are two sets of grippers, one set at eaeh of the filling stations. Grippers 72, that may be closed, by a motor 73, are supported on arms 74 that have an elbow pivot 75 for horizontal movement and a shoulder pivot 76 for vertical movement, the shoulder pivot 76 being supported on the frame 12. An air cylinder motor 77 extends horizontally between the arms 74 to move the grippers horizontally toward and away from each other. Another air cylinder motor 78 reacts against the frame 12 to raise and lower the arms 74 and hence raise and lower the grippers 72.

The grippers at the secondary filling station 15 have an arrangement similar to that at the bulk filling station 14 but include a bag-weighing unit 81. Figure 4 shows the gripper arrangement for the secondary filling station 15 as including grippers 82 that may be opened and closed by a motor 83 and are carried on arms 84 having an elbow pivot 85 for horizontal movement of the forearm and that are supported on a shoulder pivot 86 for vertical movement of the arms 84 and grippers 82. A motor such as an air cylinder motor 87 is connected between the forearms to move these arms 84 toward and away from each other. A motor such as an air cylinder motor 88 is connected to raise and lower the arms 84. The motor 88 reacts against a movable frame 89 that is pivoted at 90 to a beam 91, pivoted at 92 to the frame 12. A load cell may act as the unit 81 and connect the rear of the beam 91 to the fixed frame 12. Thus as a bag 25, carried by the grippers 82, is filled with powdery material, the beam 91 tends to tip counter clockwise as viewed in Figure 4 and this is resisted by the load cell 81 to weigh the bag and its contents.

At the bulk filling station 14, the outer clam shell spout 50 has front and rear halves 94 and 95 that may be closed to facilitate spouting of the bag and - 10 opened to open the bag top and to allow material to flow into the bag 25. Bag sensors 96 pivoted relative to the front and rear clam shell halves 94 and 95 determine whether or not a bag has been positioned on the spout 50 so that material will not be discharged when a bag is absent or improperly spouted. The secondary filling station 15 has a similar arrangement With an outer front clam shell 98 and outer rear clam shell 99, being also openable and closable to facilitate respouting of the bag, and front and rear sensors 100 are pivoted relative to the outer front and rear clam shell halves to detect the presence or absence of a bag or an improperly spouted bag.

A split belt conveyor 103. has belts 104 and 105 spaced slightly apart and this conveyor is positioned below the bulk and secondary filling stations 14 and 15. The space between the belts 104 and 105 is provided to permit an empty, flat, bag to move from the alignment station 13 to the first filling station 14 with the bag in this space between the belts. Later the bags may be lifted onto the spout 50 as shown in Figure 5 and then filled and after' filling they will be lowered onto both belts 104 and 105 to be supported thereby.

The sealing and closing station 16 has a conveyor 108 that is a single belt conveyor on the same level as the conveyor belts 104, 105. All of these conveyors may be raised and lowered as shown in the phantom position of Figure 3 in order to accommodate bags of different dimensions, for example bags of from 25 to 110 pound capacity. The sealing and closing station 16 also has a supporting V-belt 109 at the front and a V-belt 110 at the rear riding on pulleys 111 and driven by a motor 35. These V-belts provide support to hold the bag in a vertical position so that it will not tip over, and to maintain the top edge of the bag at the reference - 11 line 26. The motor 35 drives all the bag transport means in synchronism so that bags are conveyed throughout at a constant rate.

The sealing and closing station has means to open the top of the bags to expose inner heat-sealable material areas for air-blast cleaning of such areas in preparation for heat-sealing of bags. A wire 124 pushes back the longer rear lip 115 of bag 25 above the part of the bag held closed by belts 109, 110 and a downstream IO air jet 125 and an upstream air jet 126 blow on the inside of the front lip and rear lip 115 to clean them of any powdery residue. By reason of this air-blast cleaning of the front and rear lips of bags prior to sealing, the bag top is closed securely. Also the sealing and closing station has means to heat-seal inner heat-sealable materials of such bags for protection of bag contents from deleterious effects caused by absorption of moisture, etc. during storage.

The sealing and closing station 16 also has means 114 to fold over the longer rear lip 115 of the bag 25 which carries a heat-sensitive adhesive and which is then carried over a vented plenum chamber where controlled, heated air is impinged on the adhesive to activate it, after which the folding of the flap is completed by means which bring it in contact with the adjacent area of the bag to which it seals itself under influence of compression belts 117 which press on the folded top and assist in securing the folded flap.

Control means 120 is provided, including a control panel mounted so as to be accessible to a machine attendant and which contains all controls necessary for proper functioning of the machine. The various control and limit switches such as the bag sensors 96 and 100 are connected into this control means and control the various motors in a sequence of operation. - 12 The bag-filling machine II as above described is usuable with almost any solid particulate or flowable material and is particularly advantageous with powdery material of the nature of foodstuffs such as dried milk or flour or other powdery materials such as may be manufactured by various industries. The powdery material will be present in the bulk storage bin 18 and supplied by the delivery screw 40 to the primary condition ing station 19 equipped with level controls 38. Container 39 has sides converging toward delivery screw 42 that further conveys material to hoppers 48 and 49 and the secondary conditioning station 20 that is thus filled from the bottom up and the product level therein is controlled by level control 44. It can be seen that when the level of product in the secondary conditioning station 20 reaches a preset maximum as determined by level control 44, screw 42 will be stopped allowing screw 40 to fill the primary conditioning station 39 until stopped by its level control 38. The entire conditioning system thus filled contains sufficient product for air entrained in the product on entering the system to be dissipated from the powdery material even while material is being withdrawn at the bulk and dribble filling stations during operation. Dissipation of air is aided by the partial vacuum established by the vacuum line 62 above both conditioning containers. This is also aided by the agitators 56 and 57 to make certain that no pockets of air might be trapped inside these hoppers 48 and 49.

The height of the material in the container 39 to the level set by the level control 38 is of the same order as the height of a bag being filled, being preferably one to two times the height of such bag.

It has been discovered that when material is stored in a bulk storage bin such as the bin 18 having a large vertical dimension, the sheer weight and compaction of the material when such bin is full often - 13 prevents air from escaping from the powdery material near the bottom. Therefore, when material is delivered from the bin, e.g. by a mechanism such as the delivery screw 40, it is often still in an aerated condition, so that if it were to be supplied from such a bin directly to bag-filling hoppers similar to hoppers 48 and 49 and then immediately supplied into the bags, as in the prior art machines the material delivered to the bags would often be highly aerated. In the above described embodiment of the invention, however, the primary conditioning system enables air to escape from the powdery material entering this system from the bin 18, by the temporary storage of a relatively small quantity of material in a mass of relatively small vertical height. In the prior art machines in which aerated powdery material was often delivered to the bags for the reasons indicated, time had to be allowed for the material to settle in a bag and let the air out of the material before the bag could be sealed and closed. This severely restricted the productivity of the prior art bag-filling machines and in severe cases it was often found that the delivery of the material to the bags had to be slowed or left uncompleted because the bag simply did not have enough capacity to contain all the material, when aerated, and the material might overflow before the bag had reached the required weight.

Reverting to the operation of the described machine, bags 25 are supplied by the magazine 17. The removal mechanism 23 pulls off one bag at a time from the rear end of the magazine 17 and moves it to the vertical plane beneath the horizontal reference line 26. The removal mechanism 23 then moves the bag upwardly until the top apenable edge of the bag is at this reference line 26. ‘Provided the bag top is level with respect to reference line 26 as determined by two cooperating sensors, which must both engage the bag top, - 14 the bag is then clamped in this attitude by clamps 27.

At this time the vacuum cups 24 may release their hold on the bag. At this time also, the control means 120 actuates the motors 34 to close the V-belts oh the bag 25 in the position 25A at the alignment station 13, see Figure 6. The control means 120 then actuates a clutch 36 to move the belts and advance the bag from the alignment position 25A to a position 25B at the primary or bulk filling station 14. In this advancing movement the bottom of the bag moves into the space between the belts 104 and 105, also driven through clutch 36. Motors 73 are actuated so that the grippers 72 grip over the top corners of the bag 25, the bag having meanwhile been maintained with its top edge in the horizontal reference line 26 by the V-belts 33 so that the grippers 72 grasp successive bags at the same horizontal reference line position. The motors 34 then swing the belts 33 away from the bag because it is now being held by the grippers 72. The bag is in a position similar to the position 25A shown in Figure 6, except that the bag is not yet filled.

Next the front and rear outer clam shells 94 and 95 are closed and because the front outer clam shell 94 is longer it strikes the upwardly extending rear lip 115 of the bag and pushes it backwardly despite the urging of the air cylinder 77 which urges the arms 74 apart. This creates a positive opening between the front and rear faces of the bag 25. Next the air pressure is released on motor 77 and motor 78 lifts the arms 74 and hence the closed outer clam shell spout 50 penetrates between the front and rear faces of the bag. The grippers 72 are lifted sufficiently to spout the bag 25 positively on the outer clam shell spout 50 to the position 25C shown in Figure 5.

The release of air pressure on air motor 77 during this upward movement of the bag permits the arms - 15 74 to move together slightly as necessary tc permit the bag to be raised upwardly on the outer clam shell spout without stressing the bag.

When the bag is thus raised on to the outer clam shell spout, air motor 122 causes the two halves of the outer clam shell spout to open in preparation for filling the bag. At this time, also, sensors 96 are either engaged or not depending on whether or not the bag has been properly positioned and is ready to receive a lo charge of material. The bag thus spouted remains almost completely closed because it is a side gusseted bag and the grippers 72, being clamped on the gussets, prevent the opening of the gussets at the top and hence restrain the opening of the entire bag; thus there is a minimum of air volume inside the bag at this time.

Next the auger 52 is driven by the motor 54 and the clam shell valve 64 opens to bulk fill the bag in the position 25C as supported by the grippers 72. A major portion, e.g. 90%, of the nominal capacity of the bag is filled by material forced downwardly into the bag at this bulk filling station 14. The substantially completely de-aerated powdery material is forced downwardly into the bag, opening this only to the extent required to accommodate it, thus precluding the entrance of practically any air into the bag. Thus the bag is filled from the top down by material forced thereinto by the auger 52. This auger may have a large diameter, for example about one-third of the width of the bag, with a single-start thread. In one machine constructed in accordance with the invention the auger was five inches in diameter for a bag of about 15 inches in width which might hold 50 pounds of material.

As an option, the vacuum probe 66 may be lowered into the bag through the hollow stem of the auger 52.

This vacuum probe is a tube clothed with a porous - 16 material along its length so that it will evacuate any air which might tend to be within the material in the bag. This vacuum probe is lowered by the motor 68 and is withdrawn just before the inner clam shell valve 64 is closed.

After the slug of material filling the major portion of the capacity of the bag has been forced into the bag, the auger 52 is stopped and the inner clam shell valve 64 is closed. The grippers 72 are lowered by the motor 78 so that the nearly filled bag rests on the two belts 104 and 105 in position 25B shown in Figure 6, with the top edge of the bag aligned with respect to reference line 26. The motors 34 for the arms 30 are then actuated to close the V-belts on the top portion of the bag, for maintaining the top of the bag on reference line 26, and then the motor 73 releases the grippers 72. The V-belt 33 then may be actuated at the same time that the conveyor 104, 105 is actuated to move the partly filled bag to the secondary filling station 15.

At the secondary filling station 15, the motors are actuated so that the grippers grip over the top comers of the bag in a position 25D, see Figure 6. The grippers grip the gussets to keep the gussets closed and to maintain the top edge of the bag at this same reference line 26. The V-belts 33 are then actuated to move away from the bag. The outer clam shell spout 51 is then actuated closed so that the outer front clam shell 98 engages and pushes rearwardly the upwardly extending rear lip 115 of the bag to slightly open the bag. The motor 87 is then deactivated to remove the outwardly urging force between the two arms 84. Motor 88 is actuated to raise the arms 84, grippers 82 and the nearly filled bag upwardly to the position 25E shown in Figure 5, the openable end of the bag being received on the outer clam sh^ll spout 51. - 17 The auger motor 55 is a two-speed motor and it is started in its higher-speed to commence driving the auger 53 at the same time that the inner clam shell valve 65 opens. The dribble or secondary fill of the bag which thereby commences would relatively rapidly fill the bag to its chosen capacity, in this case to a calibrated weight value corresponding to the weight of the bag and a desired weight of contents. However, when the bag reaches a predetermined weight value corresponding, for example, to about 99 percent full, then the motor 55 is switched to its second, lower, speed condition for a final and gradual topping-off of the contents within the bag. When the load cell or scale 81 signals that the bag has attained the said calibrated weight value, this stops the auger drive motor 55 and closes the inner clam shell valve 65 to maintain this precise weight of the bag and contents. This final filling of the bag at the position 25E takes place at approximately the same time as the bulk filling of the next bag in the sequence at the .filling station 14, so that a continuous process of filling bags is achieved by the machine 11.

The motor 88 then lowers the arms 84 and grippers 82 so that the completely filled bag rests on the conveyor belts 104 and 105 with the top edge of the bag aligned with respect to reference line 26. This is the position as shown in Figure 6. Next the V-belts 33 are moved inwardly by the motors 34 so as to maintain the top edge of the bags at the reference line 26. The motors 83 release the grippers 82 and the conveyor 103 is actuated along with the drive of the V-belts 33 to move the completely filled bag off the end of the conveyor 103 on to the conveyor 108. This conveyor 108 is driven continuously by motor 35 so as to transport the now filled bag throughout the sealing and closing device. Also belts 109, 110 are driven continuously and in synchronism to receive and movingly support the top of the bag at the reference line 26. - 18 The filled bag first moves into the bag cleaning and sealing means 114 whereat the top of the bag is partly opened and subject to a scrubbing action by high pressure air jets directed onto inner heat-sealable areas of the bag and the top rear lip, having thereon a heat-sensitive adhesive, for the purpose of removing excess dust which might impair the security of heat-seals and/or secure bag closure. Next, in sequence, the bag passes through a series of spring-loaded heated platens the heat of which activates the heat-sealable material, and through a set of compression rolls the purpose of vihich is to set the seal. Continued movement of the bag on conveyor 108 moves the bag through the bag-closing means 116 whereat the longer rear lip 115 is partly folded over, adhesive thereon is activated by heat, the lip folding completed and the resulting bag closure secured by the compression belts 117.

Many different types of bags may be filled by the use of the machine described. Pinch-bottom bags are shown in the drawings, these being bags that have gussets along the full length of the sides, caused by a folding of the material and often termed folded-side-gusseted“ bags. Square bottom bags may also be used and these may or may not be side gusseted. In every case the grippers 72 and 82 grasp the sides of the bag to maintain the bag closed, restraining opening movement of the bag until the bag is forced open by the entrance of the powdery material. The machine is especially suitable for filling barrier bags Consisting, as previously noted, of a kraft paper outer bag with a plastic liner serving as a barrier to moisture and the entrance of vermin and the like and particularly desirable where foodstuffs are being bagged. The barrier or plastic liner may be of many types, being permanently, semipermanently, and/or only partly attached to the interior of the kraft outer bag. #4714 - 19 The V-belts 33 and V-belts 109, 110 act as clamping conveyor means engaging the flat faces of the bags just below the level of the grippers 72 and 82 to maintain the bag upright during the lateral shifting and to maintain the top lip of the bag always in alignment at the reference line 26. This lateral shifting is effected by the first shifting means or conveyor 103 as the primary supporting and conveying means of the bags. The grippers 72 and 82 of course grasp the bag above the level of these V-belts 33 and 109, 110. It will also be noted that the motor 88 is an actuator means to relatively bring together the bag and the outer clam shell spout at the secondary bag filling station. In the preferred embodiment illustrated this relative movement is caused by a raising of the bag on to the outer clam shell spout but to support it by the grippers 82 on the scale 81.

The actuator means also includes the grippers 72 and 82 and because these grippers grasp the side gussets of the bags they act as restraining means restraining opening of the bag against the forced opening by the entry of the powdery material.

The primary and secondary conditioning stations 19 and 20 together constitute a de-aeration means to substantially de-aerate the powdery material. The material is supplied to and. stays for a sufficiently long time period in each of the containers 39 and 43 and at a sufficiently small vertical height of material for any air therein to escape from this material before it is discharged to a bag. Also the delivery screw 42, once hoppers 48 and 49 have been filled, forces the powdery material upwardly from the bottom up into the container 43 and thus it does not have a chance to fall downwardly out of the end of this delivery screw, as in the prior art machine, and hence the powdery material does not become again aerated. - 20 Other aspects of the machine disclosed herein are claimed in Patent Specification Nos.44713, 44715 and 44716. '

Claims (7)

1. CLAIM S;1. A bag-filling machine comprising a base; a bag-filling station on said base; gripper means carried on said base and adapted to grip a bag near to the top thereof; actuator means to move said gripper means; a hopper for powdery material and having an outlet; an auger in said hopper; means for controlling said actuator means to raise said gripper means and a bag gripped thereby, to position an opening of the bag on said outlet of said hopper; fill control means to control the filling of a bag on said hopper outlet; weighing means responsive to the weight on said gripper means relative to said base; drive means to rotate said auger to move material in said hopper to said outlet; and means responsive to the attainment of a predetermined filled weight of a bag on said gripper means as determined by said weighing means to actuate said fill control means to stop the filling of said bag.

2. A bag-filling machine according to claim 1, including a primary filling station adapted to fill a bag thereat with a powdery material to a major portion of the maximum capacity of the bag, and means to shift the bag from said primary filling station to said bagfilling station to fill said bag to said predetermined weight.

3. A bag-filling machine according to claim 1 or 2, wherein said gripper means are adapted to grip over the sides of a bag to hold said sides closed.

4. A bag-filling machine according to claim 3, wherein said gripper means are adapted to grip over the top of a bag at the top corners thereof.

5. A bag-filling machine according to any one 4 4714 - 22 of claims 1 to 4, including an inner clam shell valve on the bottom of said hopper and an outer clam shell spout surrounding said inner clam shell valve, said actuator means being adapted to raise said gripper 5 means to raise a bag gripped thereby over said outer clam shell spout.

6. * A bag-filling machine according to any one of claims 1 to 5, wherein said drive means has a first higher speed and a second lower speed, and is 10 controlled by means responsive to the attainment of a predetermined unfilled weight by a bag being filled to change from said first to said second speed.

7. A bag-filling machine according to claim 6, wherein said means responsive to said predetermined 15 filled weight of a bag are adapted to change said drive means from said second slower speed to a stopped Condition.