US2799465A - Method and apparatus for filling receptacles - Google Patents

Description

c. F. CARTER 2,799,465

METHOD AND APPARATUS FOR FILLING RECEPTACLES July 16, 1957 5 Sheets-Sheet 1 Filed Feb. 28, 1955 INVENI'OR Ulwmzwel? Carha" ATTORNEYS y 1957 c. F. CARTER 2,799,465

' METHOD AND APPARATUS FOR FILLING RECEPTACLES Filed Feb. 28, 1955 5 Sheets-Sheet 2 A9 43A .25 LL as l 3 f0 ATMOSPHERE on. cam/em Carter ATTORNEYS c. F. CARTER 2,799,465

METHOD AND APPARATUS FOR FILLING .RECEPTACLES July 16, 1957 5 Sheets-Sheet 5 Filed Feb. 28, 1955 INVENTOR ATTORNEYS July 16, 1957 c. F. CARTER 2,799,

METHOD AND APPARATUS FOR FILLING RECEPTAQEES Filed Feb. 28, 1955 V 5 Sheets-Sheet 4 INVENTOR LZfiremefi! Carier BY mAAw Am ATTORNEYS 2,799,4fi Patented July 16, 195? METHOD AND APPARATUS FOR FILLING RECEPTACLES Clarence F. Carter, Danville, iii. Application February 28, 1955, SerialNo. 4%,942

16 Claims. c1. 249-62) This invention relates generally to a method of filling receptacles particularly adapted for use where very finely divided material is involved and to a filling machine particularly adapted for dispensing such finely divided material into receptacles such as valve type bags. More specifically, as set forth hereinafter, the invention is directed to an automatic bag filling machine which employs a reduced pressure or vacuum within a bag enclosing shroud to draw finely divided material into the bag and, further, to a method of filling receptacles in a series of increments with very finely divided material to produce highly compacted material as the final product.

Through the years a variety of different filling methods and machines for filling receptacles have been developed and have to varying degrees met with satisfactory accep-;

fluffy by reason of air entrained between the powder par-j ticles. Whereas such entrained air may serve a useful purpose in facilitating freer flow of the material through the dispensing machine to the receptacle being filled, it is a distinct drawback from the standpoint of achieving the desired degree of material compacting within the filled receptacle. Removing this entrained air and thereby compacting the material presents a real problem in filling the receptacle with these powdered materials.

In the past, one suggested solution to compacting finely divided material by freeing it of air which becomes entrained between the powder particles has been to subject the receptacle during filling to rapid vibration. Under this filling method, as the particles tend to settle down, material is added to the receptacle until the receptacle contains the desired weight of material for its particular size. ently being used, it has a distinct disadvantage in that it may require a period of several hours of continuous receptacle vibration and repeated material additions to fill a drum with the desired weight of powdered material as for example in the case where silica gel or carbon black is being dispensed. In comparison with this length of time required for vibratory filling, the filling method of the instant invention can achieve the same degree of material compacting in filling the same size drum in a matter of one minute.

As a further problem encountered in the handling and dispensing of very finely divided powders, the characteristic of such powders to become dispersed in the atmos- Whereas this filling method has been and ispresphere surrounding the filling machine and thereafter settle on the machine parts and areas adjacent the machine has been recognized as a definite problem in the development of filling machines. Accordingly, it is of the utmost importance that a filling machine for use in handling such finely divided powders be constructed to reduce to a minimum the escape of powders either from the machine mechanism itself or from the receptacle as it is being filled. The construction of the filling machine of the instant invention and its mode of operation have been developed to possess the required characteristics for the handling of finely divided powders. As a further advantage of the filling machine described in detail hereinafter, its automatic operation, commencing from the time of introduction of the bag to be filled into the shroud and continuing through the completion of the bag filling cycle, contributes to reducing the chance for escape of powdered material into the surrounding atmosphere.

It is a primary object of the instant invention to provide a method of filling receptacles with finely divided materials or powders, which method requires a minimum of time in the filling operation and produces a high degree of compacting of the material dispensed into the receptacle.

A further object of this invention is to provide a method of filling receptacles under vacuum in a series of increments wherein the vacuum which is effective to draw the material into the receptacle and simultaneously assist in withdrawing entrained air from the material is momentarily decreased between each increment of fill dispensed into the receptacle to permit an instantaneous reverse flow of air back into the receptacle while continuing to withdraw entrained air from the powdered material mass.

It is also a principal object of this invention to provide a bag filling machine having a shroud providing a chamber for enclosing the bag being filled to subject the bag exterior to a reduced pressure and further having a filling spout with a seal element actuatable to retain the bag on the spout so as to preclude seepage of powdered material from the bag interior during filling.

It is an additional object of the instant invention to provide a filling machine having .a shroud suspended from a scale mechanism and providing a chamber for receiving the bags being filled, together with valves for controlling vacuum imparted to the shroud chamber, venting the bag interior, powdered material flow and relief to atmospheric pressure of the shroud interior, all actuatable in proper sequence to effect incremental filling of the bag.

Other and more specific objects, features and advantages of the instant invention will be apparent from the detailed description set forth hereinbelow. Such description given in connection with the accompanying drawings which form a part of this application is illustrative merely by Way of example of a preferred form of the invention. It will also be appreciated that the method of the instant invention may be practiced in using a variety of different structures other than that specifically illustrated in this application. Accordingly, the invention consists of such novel method features, arrangements and combinations of parts as may be shown and described in connection with the apparatus herein set forth.

In the drawings:

Figure l is a front elevational view of a bag filling machine incorporating the features of the instant invention; Figure 2 is a side elevational view of the machine of Figure l;

- Figure 3 is a sectional view taken on line 33 of Figure 2;

Figure 4 is a detailed section of its related parts;

the filling spout and the side wall of shroud 40.

Figure 5 is a sectional view taken on line 55 of Figure 4; and

Figure 6 is a schematic view of the circuitry employed in the automatic operation of the bag filling machine.

Referring specifically to the overall views of the bag filling machine as shown on Figures 1 and 2, such machine includes a support frame 10 having upright legs 11 interconnected by a plurality of transverse members 12. A scale mechanism 13 is suspended from one of the upper transverse members 12. This mechanism consists of a primary scale beam 14 fulcrumed at one end on a rod 15, which rod in turn is suspended by means of parallel cables 16 from a bar 17 which extends across the supporting transverse member. To facilitate proper vertical location of the fulcrum for beam 14 a turn buckle 18 is interposed in each of the cables 16.

The opposite end of primary scale beam 14 is interconnected with one end of a secondary scale beam 19 by means of a pair of cables 20 engaging with pins 21 carried in the adjacent overlying ends of beams 14 and 19. The secondary scale beam 19 is fulcrumed on a rod 22 which is suspended from the upper-transverse member by means of a cable 23 connected between the rod and such member.

The secondary scale beam 19 overlies beam 14 with the end thereof opposite pin 21 extending between cables 16 and carrying a threaded rod 25 having a counterweight 26. It will be appreciated that adjustment of counterweight 26 by threading it along rod 25 will be effective to alter the response characteristics of the scale so that such mechanism may be adjusted to respond to different total weights of material dispensed into the bags being filled.

Adjacent threaded rod 25 and extending upwards from the end of scale beam 19 there is provided a pin 27 having a stud 2S threaded into its upper end to engage with the actuator of an electric switch WS. This switch contains a pair of normally closed contacts. Upon actuation of the scale mechanism in response to material dispensed into the receptacle being filled, the pin 27 and its stud 28 will be moved upwardly as carried by beam 19 to effect opening of switch WS.

To limit movement of the secondary scale beam 19, a pair of studs 30 are mounted respectively above and below the beam end. These studs are threaded into their supports, each preferably with a locking nut provided thereon, so that adjustment as to the possible range of movement of the beam 19 may be made. Also coupled with the outer end of beam 19 is a dash pot device 31. This device, secured on the skeleton frame lth'has its shaft 32 connected to the outer end of beam 19 so as to retard movements of the beam as the material is dispensed into the receptacle being filled. Thus, the dash pot device tends to overcome the possibility of the scale mechanism partaking of undesirable rapid movement which might prematurely effect opening of the switch W8.

A shroud 40 is suspended from the scale mechanism 13 by means of a cable 41 connected medially of the ends of primary scale beam 1 by a pin 42. Cable 41 has a turn buckle 43 interposed therein to facilitate adjustment of the position of shroud 40 relative to the scale mechanism. The cable 41 is coupled at its lower end to a pin 44. The pin 44 engages beneath one leg of an angle 45 while the other leg of such angle is rigidly secured to As shown more clearly in the sectional view of Figure 3, the shroud 40 provides a generally rectangular interior 53 supported longitudinally of and adjacent one corner of the shroud by means of hinge ears 54 and 55, carried respectively by the shroud 40 and door 52.

The hinge cars 55, midway of the length of shroud door 52, extend rearwardly of the door pivot to provide an arm 56. Supported on the shroud adjacent the arm 56 is a pneumatic actuator 57 having the actuating rod thereof pivotally connected to the arm 56 with the cylinder of such actuator pivotally supported on the shroud. It will be readily appreciated that by appropriately directing pressurized fluid to the actuator 57, the door 52 will be opened or closed accordingly. To seal the joint between door 52 and shroud 40, there is provided a flexible seal strip 60 which is secured along the edge of the shroud by means of a metal strip 61.

As shown on Figure 2 an electric switch DS is mounted on frame 10 with its actuator positioned so as to be engaged by arm 56 when the door is in its closed position. The contacts of switch D8 are normally open and therefore such switch contacts are closed only when the door 52 is closed under control of the pneumatic actuator 57.

To restrict lateral sway of the shroud 40 while permitting free unrestricted longitudinal movement of the shroud under the yielding movements of the scale mechanism, there are provided a series of flexible cables connected between the support frame and the shroud. Thus, cables and 66 are connected between elements secured respectively to the lower forward end of the shroud 40 and support frame 10. Likewise, the rear lower end of shroud 40 is restrained by flexible cables 68 connected to the bottom of the shroud and the transverse members on opposite sides of the shroud. To restrain backward and forward movement of the shroud, flexible cables 70 and 71 are connected to elements carried respectively by the lower rear end of the shroud and one of the lower transverse members. Similar restraining cables at the upper rear corner of the shroud are provided in the form of cables 74 and 75 to restrain side to side sway and cables 77 and 78 to restrain back and forth movement of the upper end of the shroud. It will be appreciated that a limited amount of slack in all the hereinabove-mentioned anti-sway cables is provided so as to permit limited up and down movement of the shroud as the scale mechanism responds to the material dispensed into the bag being filled.

A pair of parallel members 80 and 81 are mounted interiorly of and at the upper end of the shroud with member 80 being rigidly secured to the shroud 40 and member 81 being secured to and carried by the shroud door 52. Likewise, a pair of parallel members 83 and 84 are provided adjacent the lower end of the shroud interior with member 83 being secured to the shroud and member 84 being mounted on and carried by the shroud door 52. In the closed position of door 52 the pairs of parallel members are positioned as shown in Figure 1 so as to leave a space extending longitudinally between each pair to receive the respective upper and lower seams of the bag being filled. These members are grooved so as to promote application of vacuum to the entire exterior surface of the bag being filled.

It will be noted that the members 83 and 84 have a comparatively large height, substantially greater than the width of the seam of the bag which will be inserted between them. The size of these two'members may be 65' varied as desired to accommodate bags of different lengths.

Thus, for example, where bags substantially as long as the shroud 40 are being filled,.the members '83 and 84 would be substantially shorter to provide an'open space above such memberswithin the shroud which will accommodate such a long bag' during the filling operation. Thus,'-it is a simple matter to appropriately vary the size of members 83 and 84 toadapt the bag filling machine of the instant invention to the handling of bags of different overall length.

A relief valve is provided mounted in the rear wall of the shroud 40 to control communication of the shroud averages interior with atmospheric pressure. As shown, this valve is of the diaphragm type wherein opening and closing of such valve is effected by regulating the flow of pressurized fluid to one side of a diaphragm within the valve. The timing of the opening and closing of relief valve 90 will be described in more detail with regard to the description of the schematic diagram of Figure 6.

A vacuum control valve 95 is mounted in the upper wall of the shroud 40 and controls communication of the shroud with a source of vacuum or low pressure through a conduit 96. As part of the conduit 96 there are flexible sleeve sections 97 which permit relative movement between shroud 40 and the frame as the scale mechanism responds to the weight of material dispensed into the bag being filled. As in the case of relief valve 90, valve 95 is shown as being of the diaphragm type and its actuation is effected by appropriate control of a pressurized fluid admitted to such valve.

As shown more clearly in Figure 4, the shroud 40 is provided adjacent the rear upper corner thereof with a housing 100 which serves to mount the filling spout 101 that extends inwardly of the shroud interior. It will be appreciated that the bag to be filled when positioned for filling will have the filling spout extending through the bag mouth. The spout 101 consists of a main tubular member 102 having a flange 103 bolted to housing 100 by bolts 104. A pair of seal elements 105 and 106 are carried on the periphery of tubular member 102. Each of these seal elements includes a flexible resilient sleeve enclosing a ring which serves to support the resilient sleeve and hold it in position on the filling spout. A spacing tube 110 is disposed between the seal elements 105 and 106 and a ring 111 provided in engagement with the outer end of seal element 106. The seal elements, spacing tube and ring are held on member 102 against the shoulder on such tubular member by a spout tip 112 threaded on to the outer end of tubular member 102.

The tubular member 102 of the filling spout is provided with a longitudinal bore 115 communicating at its opposite ends with seal element 105 and a conduit 116 for the admission of pressurized fluid to the seal. A similar longitudinal bore 117 is provided in tubular member 102 and communicates at its opposite ends with the interior of seal element 106 and a conduit 118 for the admission of pressurized fluid to this seal. The regulation and control of the admission of pressurized fluid to the respective seal elements 105 and 106 is explained .in more detail hereinafter in connection with the description of Figure 6. As to seal element 105, it will be appreciated that within the scope of the instant invention the seal may be disposed in the wall of cavity 120 to expand into contact with the exterior of the spout instead of as shown on the drawing.

Generally, seals 105 and 106 perform the function of retaining the mouth of the bag being filled in proper cooperation with the filling spout. Figure 4 illustrates in section the relationship of a bag B and its mouth M to the filling spout when the bag is properly positioned for filling. Such figure also shows, with regard to seal elements 105 and 106, the expanded relation of such elements in dotted lines, thus illustrating how the respective seals cooperate with the bag mouth M.

Attention is called to the fact that the seal element 105 is disposed within an annular cavity 120 formed within the housing 100. Thus, when the bag to be filled is properly positioned within the shroud the valve mouth therein will extend into the cavity 120 so that upon the expansion of seal 105 by the introduction of pressurized fluid thereinto the outer end of the bag mouth will be rigidly clamped and held in engagement with the outer wall of cavity 120. On the other hand, seal element 106 being disposed toward the outer end of the filling spout will engage with the bag mouth at a point where such mouth is not backed up or supported. Accordingly, it is contemplated that normally a lesser pressure willbe applied to expand seal element 106 than that applied to seal element 105 since undue pressure and therefore excessive expansion of seal element 106 might result in tearing the tubular bag mouth M.

The housing also provides an upstanding pocket 121 which communicates at its lower end with the annular cavity 120. This pocket receives the upper bag seam as the bag is slid on to the filling spout for the filling operation. An expandable resilient tube seal 122 is provided in a groove 123 formed in the top and side walls of pocket121. It will be appreciated that upon the admission of pressurized fluid to seal 122 the expansion thereof will effect clamping of the upstanding top bag seam to assist seal elements and 106 in retaining the bag in position on the filling spout and also to preclude escape of material from the bag as it is discharged thereinto through spout 101.

It will be noted that a plurality of openings 125 are provided extending outwardly from the cavity 120 to communicate with the atmosphere exterior of the shroud. By providing .such openings the high vacuum within the shroud, exterior of the bag being filled, will not tend to draw material from the bag outwardly through the bag mouth M past seal elements 105 and 106. Instead the shroud vacuum and the presence of a low pressure within the bag results in any flow of air past the seal elements passing into the bag, thus precluding the escape of the powdered material into the shroud or atmosphere surrounding the filling machine.

The filling spout 101 through its tubular member 102 is connected to a material supply conduit 130. As in the case of the vacuum conduit 06, material supply conduit includes a pair of flexible sleeves 131 to permit relative movement between the shroud and the stationary end of conduit 130. A material supply hopper 132 is coupled to the outer end of conduit 130 with a material valve 133 interposed between the bottom of the hopper and conduit 130. Also connected with conduit 130 is a vent valve 134 which, as will appea r from the description given below, functions to admit gaseous fluid into conduit 130 and thence into the bag being filled through the filling spout to effect initial opening of the bag for receipt of the material. As illustrated, valves 133 and 134 are of the diaphragm type wherein opening and closing is effected by regulation of the admission of a pressurized fluid to one side of the valves diaphragm.

A manually operated three-way valve 135 is shown on Figure 2, disposed in the line leading to vent valve 134. This valve is manually operated to connect either a pressure source or atmospheric pressure with the inlet to vent valve 134. Thus, when it is desired to open the bag to be filled as mounted within the shroud, valve 135 may be set to communicate atmospheric pressure to vent valve 134 and the vacuum created within the shroud, exteriorly of the bag, used to draw open such bag. On the other hand, if it be desired to employ positive bag opening pressure, valve 135 may be adjusted to communicate the pressure source with the inlet to valve 134 so that the bag within the shroud will be opened by application of positive pressure to the interior thereof.

Having described in detail the structural features of the instant invention as shown in the embodiment of the drawings, reference will now be had to the schematic diagram of Figure 6 which illustrates the manner in which automatic operation of the filling machine is secured. in this figure the leads from the power source as, for example, a 110 volt, 60 cycle alternating current source are designated at L-1 and L2. As previously described, the contacts of the weight switch WS are normally closed and are not opened until such time as the weight of the material within a bag being filled causes the scale mechanism 13 to respond so that its pin 27 causes opening of the weight switch. The weight switch contacts designated WS are shown normally closed. On Figure 6 the remaining contacts of the various relays and of door switch DS are shown in their open state as they exist prior to commencing of an automatic bag filling c cle.

A start push button 150 which is normally open and a normally closed stop button 151 are connected in series with the contacts WS and the coil of a relay RA. Contacts RAl of relay RA are connected in shunt across start button 150 so as to form a holding circuit for relay RA, once the contacts of push button 150have been momentarily closed to energize the relay. Contacts RAz of relay RA are connected across the leads of the power source in series with contacts WS and the coils of solenoids SA, SB, SC, and SD. Thus, upon closing of contacts RAz the solenoids will be energized through contacts WS.

The solenoids SA and SB are connected to actuate separate 3-way valves which are operable to couple alternatively pressurized fluid or atmospheric pressure with the pneumatic door actuator 57. As described above, door actuator 57 is connected to effect opening and closing of the shroud door 52. In the relation shown on Figure 6, the valves controlled by solenoids SA and SB are disposed to retain the door actuator in its position for the door 52 to be fully opened. Upon energization of solenoids SA and SB, the valves controlled thereby are moved to couple pressure to the left side of the actuator piston and vent the right side of such piston, as shown on Figure 6, to atmosphere. Such action will cause the actuator to effect closing of door 52.

Solenoids SC and SD are connected to actuate 3-way valves so as to either admit pressure to the filling spout seals 105, 106 and 122 or to connect such seals with vacuum and thereby release the seals from their clamping action. As previously mentioned, due to the positioning of seals 105 and 106 a lower pressure is generally applied to seal 106 than that used in inflating seals 105 and 122. Accordingly, as shown in Figure 6, solenoid SC when energized operates its 3-way valve to admit the desired inflating pressure to seal 1% and likewise solenoid SD when energized admits a somewhat higher pressure to inflate seals 105 and 122.

As pneumatic actuator 57 closes the shroud door 52 as a result of the energization of solenoids SA and SB, such door, by means of arm 55, closes the door switch contacts DS. Contacts DS are connected in serie with the operating coil of a relay RB through a lead 152 extending through the normally closed contacts of stop button 151 and weight switch contacts WS. One pair of contacts RB]. of relay RB are connected in shunt with relation to contacts DS to form a holding circuit for relay RE. A second set of contacts RBz of relay RB serve to set up a circuit extending through contacts WS for energization of solenoids controlling the vacuum valve, relief valve and material supply valve of the filling machine.

In addition to energizing relay RB, the closing of the door switch contacts DS effects energization of a timer 155. This timer is set to energize the coil of a solenoid SE for a predetermined period of time, in the order of two or three seconds, after which such solenoid is deenergized. Solenoid SE is coupled to a 3-way valve which is effective to operate the vent valve 134 so as to admit alternatively pressurized fluid or vacuum to the diaphragm of valve 134- to either close or open'such valve. As shown in Figure 6, pressure is communicated to the valve 134 with solenoid SE de-energized. Upon energization of solenoid SE, the 3-way valve is actuated to communicate vacuum to the vent valve so as to open such valve for the period of energization of the solenoid SE, after which time valve 134 is closed by pressure again being applied to its diaphragm.

Contacts RBa of relay RB are closed upon energization of such relay to start a timer 16 The timer 16% connected in series with contacts RB: across the power source is operable to efiect intermittent energization of a relay RC. The timer 160 maybe of any suitable. con: struction although preferably, for reliability and rapid operation, an electronic timer is used. As shown at 161, the timer is provided with a dial and pointer which may be adjusted as desired to vary the" interval of time during which relay RC is energized. The purpose and function of varying or controlling the interval of relay RC energization will be more apparent with reference to the stated operation of the invention as set forth hereinafter.

The contacts RCrof relay RC are connected in series with contacts R82 and upon the closing of contacts RC1 after contacts RBzhave been closed, solenoids SF and SG are energized through the weight switch contacts WS. Solenoid SF operates a 3-way valve which controls the opening and closing of the vacuum valve and solenoid SG acit'lates E1 3-way valve Which in tliiil Controls the opening and closing of relief "valve 90. In their deenergized state, as shown in Figure 6, thevacuum valve 95 will be closed by the admission of pressurized fluid to the diaphragm of such valve. At the same time the relief valve 90 is open by reason of a vacuum or low pressure being communicated with its diaphragm. Upon energization of solenoids SFand SG the vacuum valve is opened and the relief valve closed.

In addition to energizing solenoids SF and SG, upon closing of contacts RC1 a circuit is set up leading to a vacuum control 165. Vacuum control 165 includes a pressure responsive switch, the contacts of which close in response to the vacuum existent within the shroud. With the shroud door closed, the vacuum valve open and the relief 'valve closed, the pressure within the shroud will diminish. Initially, the bag positioned on the filling spout within the shroud will be opened with air being admitted to the bag interior by reason of the opening of vent valve 134 through the energization of solenoid SE. However, solenoid SE only remains energized for the relatively short period of, for example, 2 or 3 seconds, asdetermined by the setting of timer and upon deenergization of solenoid SE and closing of the vent valve, the vacuum within the shroud tends to increase. The vacuum control is set to close its contacts upon the shroud vacuum reaching a predetermined point. When such low pressure or vacuumobtains within the shroud, the vacuum control contacts close to complete the circuit through the coil of a relay RD.

Contacts RDI of relay RD close to set up-a holding circuit bypassing the vacuum control 165. The provision of contacts RDl shunting the contacts of the vacuum control 165 has been found to be desirable to prevent intermittent opening and closing of relay RD. This action, in the absence of holding contacts RDi might occur upon opening of the material supply valve accompanied by a drop in the shroud vacuum which in turn would cause a response in the vacuum control 165 resulting in opening of its contacts thereby de-energizing relay RD and closing the material supply valve until the shroud vacuum builds back up to operate the vacuum control.

A second set of contacts RDz are likewise closed upon energization of relay RD at which time a solenoid SH is energized. Solenoid SH is coupled to actuate a 3- way valve which controls the opening and closing of the material supply valve 133. Preferably, material valve 133 operates after about a 2-second delay following the obtaining of the vacuum within the shroud for which control 165 is set. This permits the pressure within the shroud and bag interior to stabilize before admitting material into the bag. As shown on Figure 6 with solenoid SH de-energized, pressure is admitted to the diaphragm of valve 133 to maintain it closed. Upon energtzation of solenoid SH, vacum is admitted to the diaphragm of valve 133 to open such valve for the admission of material from the supply hopper into the bag'to be filled through the filling spout.

Referring again to timer 160, it has been stated that 9 this timer functions to intermittently energize relay RC, Thus, it will be seen that each time relay RC is energized, closing its contacts RC1, the vacuum valve will open, the relief valve close and, when the vacuum within the shroud becomes sutficient to actuate the vacuum control 165, the material valve will open. Likewise, when relay RC is de-energized, under the control of timer 160, the vacuum valve will close, the relief valve open and the material supply valve close.

When the desired weight of material in the form of successive increments of material has been discharged into the bag retained within the shroud, the scale mechanism 13 will respond, resulting in its pin 27 actuating the weightswitch. Thereupon, the weight switch contacts WS will open, de-energizing the various relays and solenoids in the control circuit and returning the apparatus, upon the opening of contacts RAr, to a status in readiness for the next succeeding bag filling cycle. The next bag filling operation may be commenced after the filled bag is removed and an empty bag placed in the shroud on the filling spout.

By appropriately setting the timer 160, the size of the material fill increments may be fixed. Thus, if a relatively large number of increments are to be dispensed to completely fill the bag, the timer 160 will be set to eifect energization of relay RC for a shorter period than if larger and fewer material increments are desired to complete the bag filling. It will likewise be appreciated that the degree of vacuum used in operating the filling machine will determine to some extent the quantity of material drawn into the bag for a given time interval of energization of relay RC.

The interval of time between successive actuations of relay RC will determine the period during which the relief valve is opened and therefore the extent to which the vacuum within the shroud is diminished. It is critically important in connection with the instant invention that the relief valve does not remain open to return the shroud pressure to atmospheric between fill increments. If such is permitted in filling bags wih finely powdered material the inrush of air and pressure increase tends to fluff up the powdered material, producing a result directly contrary to the desired objective of compacting the material and withdrawing air entrained between the particles of the powdered material. Accordingly, the relay RC is only momentarily de-energized between filling increments so that the relief valve will only open for an instant to diminish the shroud pressure without returning it to atmospheric. To give specific figures, merely by way of example, the relief valve will open only for one-half second or less to drop the shroud pressure around inches of mercury. Thus, where 20 inches of mercury vacuum is being used in the filling operation, so that this degree of vacuum exists within the shroud to draw the material into the bag, the relief valve will open momentarily to drop the shroud pressure to about 15 inches of mercury between each fill increment. This sudden pressure increase after each increment of material is discharged into the bag causes a reverse flow of air through the interstices of the bag wall to clean the bag and momentarily wrinkle the wall to free it of powder which accumulates as air is withdrawn through the porous bag during introduction of powderedmaterial. At the same time, there is continuously maintained a vacuum above the material tending to withdraw entrainedair from the powdered material mass within the bag. The existence of the vacuum promotes compacting of the material while the bag wall pores are cleaned of powder preparatory to receiving the next increment of fil i The degree of compacting achieved by utilization of the principles of the herein disclosed invention may be varied in several ways. First, if a high degree of final product density in the receptacle is desired, a greater number of smaller size increments may be combined to complete the filling of the receptacle than would be used if a lower density product is wanted. Secondly, the degree' of vacuum used in the filling operation may be se lected to secure the desired compacting or density of product from the filling operation. Thus, where a high vacuum is employed, the filled receptacle will have a higher density of their fill than where a lower vacuum is used in the filling operation. Also, in connection with filling machines, the final fill product density may be altered by changing the orifice characteristics of the filling spout.

With regard to the vacuum preferably used in the filling operations, a range of from 4 inches to 28 inches of mercury may be employed depending to some extent on the specific material being handled. With most finely divided powdered materials a vacuum of from 22 inches to 25 inches has been found to be ideal. However, as a specific example, in filling with carbon black a vacuum of 18 inches has proved desirable, since at higher vacuums undue compacting and caking of the carbon black material may occur.

The overall operation of the apparatus will be understood with reference to the description of the schematic diagram of Fig. 6. By way of general summary, however, a brief review of the operations that take place will be given. Assuming that an empty bag, usually in a flattened condition, has been placed in the shroud with the filling spout extending into the mouth of the bag, the start button is pressed to initiate the automatic filling cycle. This action energizes relay RA which closes a relay holding circuit through contacts RA1 and through contacts RAz energizes solenoids to eifect closing of the shroud door and inflation of the various filling spout seals to retain the bag on the spout. The closing of the shroud door closes contacts DS which results in energizing relay RB and timer 155. Timer energizes the vent valve solenoid to maintain such vent valve open for a relatively short period to admit air to open the bag prior to commencing introducing the fill material.

Relay RB through its contacts RBa starts operation of timer which intermittently energizes relay RC. Contacts RC1 of relay RC complete with contacts RBz the circuit to solenoids SF and SG which control operation respectively of the vacuum valve and the relief valve. Contacts RC1 also set up a circuit to the pressure responsive vacuum control 165, which control closes its con tacts when the shroud pressure reaches the desired degree of vacuum. ,Upon closure of the vacuum control contacts, which takes place after the vent valve has admitted bag opening air to the bag and thereafter closed to permit build-up of the vacuum within the shroud, relay RD is energized. Contacts RD1 of this latter relay close a holding circuit around the vacuum control and contacts RDz of relay RD complete a circuit for energization of solenoid SH. Solenoid SH effects opening of the material valve which preferably takes place about 2 seconds after the vacuum controlhas responded to shroud vacuum, permitting material to flow into the bag under the influence of vacuum present within the shroud and bag. It may be noted here that the vacuum within the shroud exists to generally the same degree within the bag by reason of seepage of air through the pervious walls of the bag.

Each time relay RC is de-encrgized under control of timer 160 the flow of material will be termined by closing of the material valve and the vacuum within the shroud diminished'by momentary opening of the relief valve with the vacuum valve closed. When timer 160 re-energizes relay RC, the sequence of operations of the relief valve, vacuum valve and material valve repeats. Such repeti tion for incremental'filling of the bag continues until the scale mechanism responds to a full material load within the bag. At the occurrence of this, the contacts WS arejopened by the scale mechanism and the circuits to the various control relays and solenoids de-energized;

De-energization of solenoids SA and SB causes actuator 57 to open the shroud door while de-energization of solenoids SC and SD causes deflation of the filling spout seals to release the bag from the filling spout.

Having thus described my invention, whatI claim iszi 1. A method of filling a receptacle with finely divided particulate material which comprises creating a vacuum within the receptacle to be filledpad'rfiitting' material into the interior of said receptacle, terminating the admission of material after only an increment of the quantity of material required to fill the receptacle has bee'irdispen'sed into the receptacle, momentarily diminishing the vacuum within the receptacle to cause an instantaneous reverse flow of air back into the receptacle while continuously maintaining a substantial sub-atmospheric pressure within the receptacle to withdraw air from between the material particles to compact the material, and repeating the above recited steps until the increments of material fill the receptacle to the desired degree.

2. A method of filling a receptacle with finely divided particulate material which comprises creating a vacuum within the receptacle to be filled, admitting an increment of material into the receptacle under the effect of the vacuum within the receptacle, terminating the flow of material into the receptacle, momentarily diminishing the vacuum within the receptacle While continuously maintaining a substantial sub-atmospheric pressure within the receptacle to withdraw air from between the material particles to compact the material, and repeating the above-recited steps until the increments of material fill the receptacle to the desired degree.

3. A method of filling a collapsible receptacle with finely divided particulate material which comprises creating a vacuum within and surrounding the receptacle to be filled, admitting gaseous fluid into the interior of the receptacle to expand same to its fully opened condition, discharging an increment of material into the receptacle while the vacuum is maintained within the receptacle, terminating the flow of material into the receptacle, momentarily diminishing the vacuum within the receptacle while continuously maintaining a substantial sub-atmospheric pressure within the receptacle to withdraw air from between the material particles to compact the material, repeating the third, fourth and fifth steps recited above to dispense a series of increments of material into the receptacle, and terminating the repetition of the third, fourth and fifth steps when a predetermined weight of material has been dispensed into the receptacle.

4. In a bag filling machine, a shroud providing a chamher for receiving a bag during the filling thereof and having an access door to permit introduction and removal of the bags being filled, a scale mechanism supporting said shroud whereby said mechanism will indi cate the weight of material dispensed into thebag within the shroud, a feed spout carried by said shroud with the outlet end thereof disposed within said shroud for insertion into the mouth of a valve type bag, a seal element encircling said feed spout adjacent the entrance of said spout into said shroud and adapted to be actuated to retain the valve bag on said spout within said shroud and preclude escape of material from the bag into said shroud, a material supply hopper, a material supply conduit connecting said feed spout and said material hopper and having a valve interposed therein actuatable to control the flow of material from the hopper to said feed spout, a second valve operable to control admission of a gaseous fluid through said spout and into the bag to effect opening of the bag retained on said spout, and means for applying a vacuum to the interior of said shroud to draw material from said hopper into the bag retained on said spout. t

5. In a bag filling machine as recited in claim 4 wherein said seal element includes an expandable resilient member having an interior space whichmay be siibje cted' 12 to fluid pressure to expand said member into engagement with the mouth of the bag to be filled.

6. In a bag filling machine as recited in claim 4 wherein pairs of parallel members are provided adjacent the top and bottominterior of said shroud with one of each of said pairs of members being mounted on and mov able with said access door whereby upon opening of said door said pairs of members will be moved apart to facilitate positioning of the upper and lower bag seams to be disposed. between the members on closing of the access door. v

7. In a bag filling machine as recited in claim 6 where in the interior surfaces of the chamber of said shroud and the surfaces of the seam members exposed to the shroud interior are grooved to promote application of vacuum to the entire exterior surface of the bag being filled.

8. In a bag filling machine as recited in claim 4 wherein an annular cavity is provided surrounding the feed spout adjacent its point of entry into said shroud, and said seal element encircling the feed spout is disposed within said cavity to clamp the mouth of thevalve bag between the periphery of said feed spout and the wall of said cavity.

9. In a bag filling machine as recited in claim 8 wherein an upstanding pocket communicating at its lower end with said annular cavity is provided adjacent the point of entry of said feed spout into said shroud, and an expandable seal element extends around the top and sides of said pocket to clampingly retain the upper bag's'eam within said pocket.

10. In a bag filling machine as recited in claim 8 further having an expandable seal embedded in the periphery of the outer end of said spout to function when expanded as a preliminary seal in retaining the valve bag on the spout.

11. In a bag filling machine, a supporting frame, a scale mechanism suspended from said supporting frame consisting of a primary scale beam fulcrurried adjacent one end thereof, a secondary scale beam fulcrumed intermediate the ends thereof and overlying said primary scale beam, means interconnecting the opposite end of said primary beam and one end of said secondary beam for transmission of forces between said beams, the opposite end of said secondary scale beam having a counter weight adjustable to alter the response of the scale mechanism, a shroud suspended from a point intermediate the ends of said primary scale beam and providing a chamber for receiving a bag during the filling thereof with an access door to permit introduction and removal of the bags being filled, a feed spout carried by said shroud with the outlet end thereof disposed within said shroud forinsertion into the mouth of a valve type bag, a seal element encircling said feed spout adjacent the entrance of said spout into said shroud and adapted to be actuated to clampingly retain the valve bag on said spout within said shroud, a material hopper, a material supply conduit connecting said feed spout and said material hopper and having a valve disposed therein actuatable to control the flow of material from the hopper to said feed spout, a vent valve operable to'control admission of a gaseous fluid through said spout and into the bag to effect opening of the bag clamped on said Spout, and means for applying a vacuum to the interior of said shroud to draw material from said hopper into the bag clamped on said spout.

12. In a bag filling machine as recited in claim 11 further having a dash pot device connected to said opposite end of said secondary scale beam to retard movements of'suc h beam during filling of the bag retained within said shroud. I V

13. Ina bag' filling machine as r ecitedin claim 11 wherein said shroud is yieldably connected said frame to restrict lateral movement of said shroud relative to said frame while permitting limited vertical movement of said shroud as said scale mechanism responds to the introduction of material into the bag being filled.

14. In a bag filling machine as recited in claim 11 wherein means is provided adjacent said opposite end of said secondary scale beam operative in response to movements of such end to terminate the bag filling operation when the desired weight of material has been dispensed into the bag within the shroud.

15. In a bag filling machine, a shroud providing a chamber for receiving a bag during the filling thereof and having an access door to permit introduction and removal of the bags being filled, switch means mounted to have the contacts thereof closed upon closing of said access door, a scale mechanism supporting said shroud and having means operable upon introduction of the desired weight of material into bag being filled to terminate the filling operation, a feed spout disposed within the upper end of said shroud and having a seal element actuatable to engage with the mouth of the bag being filled to retain same on said spout, a material supply hopper, a material supply conduit interconnecting said feed spout and said hopper and having a material valve interposed therein actuatable to control the flow of material through said feed spout, a vent valve operable to control admission ,of a gaseous fluid through said spout and into the bag to effect opening of the bag retained on said spout, a vacuum valve for coupling the interior of said shroud with a source of vacuum, a relief valve for communicating the interior of said shroud with atmospheric pressure, means operable upon closing of said switch means to open said vent valve for a predetermined time period, timer means actuated upon closing of said switch means to close said relief valve and open said vacuum valve and after a predetermined time interval to open said relief valve and close said vacuum valve, and pressure responsive means connected to open said material valve when the pressure within said shroud reaches a predetermined vacuum.

16. In a bag filling machine as recited in claim 15 further having a fluid driven actuator connected to effect opening and closing of said access door, and means for selectively controlling flow of pressurized fluid to said actuator to open and close said doom.

References Cited in the file of this patent UNITED STATES PATENTS 1,037,824 Fasting Sept. 3, 1912 2,060,011 Andreas Nov. 10, 1936 2,181,756 Cook Nov. 4, 1939 2,232,437 Bushman Feb. 18, 1941 2,513,143 Carter June 27, 1950 2,531,743 Ray Nov. 28, 1950 2,613,864 Carter Oct. 14, 1952 2,650,058 Read Aug. 25, 1953 2,718,345 Howard Sept. 20, 1955

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