US3322219A

US3322219A - Bag filling machines

Info

Publication number: US3322219A
Application number: US463151A
Authority: US
Inventors: John M Van Pernis
Original assignee: Black Products Co
Current assignee: Amcor Flexibles North America Inc
Priority date: 1965-06-11
Filing date: 1965-06-11
Publication date: 1967-05-30
Anticipated expiration: 1984-05-30

Description

2 y 1967 J. M. VAN PERNIS 3,322,219

BAG FILLING MACHINES Filed June 11, 1965' 2 Sheets-$heet 1 y 30, 1967 J. M. VAN PERNIS 2 3,322,219

BAG FILLING MACHINES Filed June' 11, 1965 2 Sheets-Sheet 2 United States Patent 3,322,219 BAG FILLING MACHlNES John M. Van Pemis, Chicago, Ill., assignor to Black Products (10., a corporation of Illinois Filed June 11, 1965, Ser. No. 463,151 8 Claims. (Cl. 177-114) This invention relates to bag filling machines of the closed chamber type, such as shown in Zenke Patent No. 3,073,401, issued Jan. 15, 1963.

It was pointed out in the Zenke patent that it is desired to provide an air space at the top of a closed conditioning chamber in order to improve the fluidizing characteristics of the material with which the bags are filled, and also to provide a uniform rate of material flow through the spout, thereby promoting greater accuracy in the filling operation.

The arrangement of that patent is characterized by a level repsonsive device located within the conditioning chamber and which controls the operation of the inlet valve to the end that the initial level of the material within the conditioning chamber is constant from one filling operation to the next, the air pressure in the free space being gradually increased during the bag filling step to compensate at least partially for the decrease in gravitational head.

However, certain difliculties are encountered in the Zenke arrangement in that the incoming stream of powdered or granular material will sometimes interrupt the motion of the sensing element of the level responsive device, and cause a false signal to be given. Also, in the case of very fine powders, the material will seep into the bearings of the level responsive device which impairs its sensitivity, and eventually may result in false signals.

Although it is possible to mitigate or overcome the above ditficulties by special locations and arrangements in the one case, and by the use of special dust tight constructions in the other case, these special arrangements add materially to the expense of the installation.

Also the level responsive device may not be too effective in the case of irregular feeding rates due to the bridging of the material in the supply hopper. The sudden collapse of the bridge will cause a large quantity of material to pass through the valve before it can be closed due to lag in response.

Another objection to the prior art construction is that some materials, of which silica sand is an example, are fed into the conditioning chamber while still hot. The temperature of the material causes rapid deterioration of any rubber parts incorporated in the level responsive device and the inlet valve. The expense of replacement parts and down time is undesirable.

Deterioration can also be caused by ozone in the atmosphere, or by the use of oily materials, or when filling with other materials which may chemically react with the rubber parts.

An object of my invention is to provide an improved bag filling machine which overcomes the above difiiculties.

According to my invention, I have found that it is possible to eliminate both the inlet valve and the level responsive device if the inlet pipe is extended down into the conditioning chamber to an extent which corresponds to the amount of free space desired.

According to this arrangement I have found that the pressure developed within the conditioning chamber, due to the fluidizing air and/or to the addition of top air, will block or prevent the movement of granular or powdered material downwardly through the inlet pipe, even though the level of the material in the conditioning chamber drops below the lower end of the inlet pipe as the bag is being filled.

At the same time, the initial gravitational head of the material is maintained constant from one operation to the next so as to provide the desired uniform conditions at the beginning of each bag filling operation.

At the conclusion of the bag filling operation, the air pressure within the conditioning chamber is released with the result that the material sets itself in motion, and thus is permitted to flow downwardly from the supply hopper and through the inlet pipe until the chamber is again filled up to the desired level.

The present invention also has the advantage in that it simplifies the electric control circuit by the elimination of the interlocking relay which is required when a level responsive device is used to control a feed valve.

Other objects, features and advantages will become apparent as the description proceeds.

With reference now to the drawings in which like reference numerals designate like parts:

FIG. 1 is an elevation of a bag filling machine embodying my invention, a part of the conditioning chamber being broken away;

FIG. 2 is a fragmentary section through the lower part of the conditioning chamber showing the diffuser pad;

FIG. 3 is a sectional view showing a suitable type of pressure relief valve;

FIG. 4 is a diagram of the electrical control means;

FIG. ,5 is a fragmentary sectional view of the conditioning chamber showing a modified inlet pipe; and

FIG. 6 shows a further modification.

FIG. 1 shows a bag filling-machine 10 which is adapted for location beneath a supply hopper 11. The bag filling machine 10 includes a conditioning chamber 12 which communicates with the hopper 11 by means of an inlet pipe 13.

The bag filling machine 10 also includes a supporting framework 14, and a scale mechanism generally indicated by the reference numeral 15. A spout 16 communicates with the lower end of the conditioning chamber 12 by a flexible rubber tube 17, and suitable spout supporting mechanism 18 is provided which also provides a connection with the scale mechanism 15.

A diffuser pad 20 (FIG. 2) is located at the bottom of the conditioning chamber 12 and is connected to an air supply pipe 21. A bag 19 may be supported from the spout 16.

When air'is caused to flow through the supply line 21 andthe diffuser pad 20, the material adjacent to the pad 20 within the conditioning chamber 12 is fluidized and will flow in a horizontal direction through the spout 16 into the bag 19. When the weight of the bag and contents reaches a predetermined amount such as pounds, the scale mechanism 15 is tripped and an air actuated pinch valve 22 engages the tube 17 to cut off the flow of material through the spout 16 in order to terminate the bag filling step. The fluidizing air to the pad 20 is also preferably cut off at this time by a solenoid valve 23 (FIG. 2).

Communicating with the upper end of the conditioning chamber is a top air pipe 24, and a vent pipe 25. Interposed in each of these pipes are

valves

26 and 27, respectively, which preferably are air actuated pinch valves, similar to the pinch valve 22.

' The top air supply comprises a low pressure air pump 28, preferably a constant delivery pump having, for example, a rated delivery of from 60 down to 45 cubic feet per minute at pressure settings of from 3 to 6 pounds per square inch, respectively. However, the foregoing values are cited only to identify the type of pumpother sizes and ratings may be selected according to the particular situation. In general, air is supplied at a rate of from 40 to 100 cubic feet per minute at from 2 to 6 pounds per square inch pressure. This constant delivery pump is sometimes referred to as a positive displacement blower.

The top air supply is also equipped with a relief valve 29 located between the pump 28 and the top air valve 26 so that the pressure can be regulated from between 2 to 6 pounds per square inch, Under this arrangement, and with a relatively large top air pipe 24, such as 2 inches ID, the pressure within the free space 30 of the conditioning chamber will be brought up to the desired degree practically instantaneously, that is, within a small fraction of a second after the top air valve 26 has been opened, and prior to the time that the material level 31 drops below the lower end of the inlet pipe 13.

A suitable pressure relief valve is shown in FIG. 3 and comprises a T-connection 32 formed in the top air pipe 24 and having a short vertical branch 33. Slots 34 are formed in the wall of the branch 33. A slidable cap 35 is loosely mounted on the branch 33 so as to cover the slots 34, but the air pressure within the top air pipe 24 elevates the cap so as to expose a portion of the slots 34, thus providing an effective pressure control of the system. The degree of pressure can be regulated by adding weights 36 to the cap 35 by means of a spindle 37.

When the top air valve 26 is closed, air from the pump 28 will bleed out through the slots 34. Thus it is possible to provide a large volume of air at a controlled pressure, the exact degree of pressure to be determined according to the characteristics of the powdered or granular material.

The air supply for closing two of the air actuated pinch valves, the cut off valve 22 and the top air valve 26, is controlled by a normally open solenoid valve 46. The air supply for closing the air actuated vent valve 27 is controlled by the normally closed solenoid valve 23. The latter also controls the air supply 21 to the fluidizing pad 20, as shown in FIG. 2. A suitable constant pressure regulating valve 47 may be used if desired between the supply pipe 21 and the solenoid valve 23 to isolate the fluidizing air from variations in the shop air line.

FIG. 4 shows a control circuit 40 which includes the

solenoid valves

23 and 46, and a switch 41 which is actuated by the scale mechanism 15. When the switch 41 opens, the

pinch valves

22 and 26 close, and the pinch valve 27 opens. The circuit 40 also includes a holding relay 42 which comprises a relay coil 43 and a switch 44 actuated thereby. The switch 44 also serves as a starting switch, being initially closed by a start button 45 to initiate the bag filling step.

In operation, the manual closing of the switch 44 opens the pinch valve 22 and the air valve 23 so that the material adjacent to the fluidizing pad 20 wil be fluidized and flow horizontally through the pinch valve 22 and into the bag 19. At the same time, the free space 30 serves as an air expansion chamber, permitting a portion of the fluidizing air to flow upwardly through the material 38 in the conditioning chamber 12 to improve its fluidizing characteristics.

The establishment of the control circuit 40 also opens the top air supply 24, and closes the vent 25 so that almost instantaneously a low pressure of from 2 to 6 pounds is established within the free space 30 and exerted upwardly on the material 39 within the inlet pipe 13.

The object of the arrangement is, in the case of fine powders, to prevent initial movement of the inlet matetrial 39 because the pressure is suflicient to maintain the inlet material stationary, but not to check the flow if once set in motion. This is achieved by the practically instantaneous build-up of pressure. There is no downward movement of the inlet material during the bag filling step. The free space 30 permits the chamber material 33 to be conditioned throughout the full cross section of the chamber 12.

Although the air in the supply pipe 21 is at a pressure of from 60 to 70 pounds, due to dynamic conditions, a pressure gauge communicating with the plenum space 48 between the fluidizing pad 20 and the bottom wall may give a reading of as low as 2% or 3 pounds.

When the bag 19 is full, the scale mechanism 15 trips, breaking the circuit 40 which closes the

pinch valves

22 and 26, cutting off the flow through the spout 16 and terminating the bag filling step. At the same time, the top air supply 24 is cut off and also the fluidizing air supply 21. The vent valve 27 is opened and the drop in air pressure within the chamber 12 permits the inlet material 39 to set itself in motion, whereupon the conditioning chamber 12 is automatically filled up to the desired level, determined by the location of the lower end of the inlet pipe 13. Thus, the free space 30 is maintained and the apparatus is ready from the next bag filling step.

In the practical embodiment shown, the conditioning chamber was 36 inches high between

flanges

49 and 50, and of rectangular cross section, 12 inches by 14 inches. The lower part, below the flange 49, was of trapezoidal cross section, and represents about one-half cubic foot additional in volume.

The machine was designed to pack lime and bentonite in lOO-pound bags. For this purpose the inlet pipe 13 was 6 inches in diameter and determined 18 inches above the lower flange 47. An eight inch pipe has also been used for bentonite, and a four inch pipe for silica sand. A four inch pipe has also been satisfactorily used for /s-inch cubic pellets, but there in some air leakage through the inlet pipe 13. However, the air leakage can be reduced by the use of a hinged flap 52, shown in FIG. 6, lightly biased into the closed position so as to be caught by the air flow.

The lower end of the pipe 13' may be flared as shown 7 at 51 in FIG. 5. This reduces the crowning of the initial material level, For instance, with a six inch pipe, the diameter of the flared lower end would be 8 inches, leaving a wall clearance of only 2 or 3 inches.

In the practical embodiment given, the charge, or amount of material contained in the conditioning chamber up to the bottom of the inlet pipe 13, represents from one and a half to two times the contents of the bag when filled. Thus, the material level drops down almost to the lower flange 49.

The scale mechanism 15 is that of the Lau Patent No. 2,733,040, but the invention is also intended to be used with scale mechanism of Lao Patent No. 3,133,608.

In some instances, the shutting off of the air supply to the fluidizing pad may be sufiiciently effective to cut off the flow of material through the spout as to permit elimination of the cut off valve 22. Also the automatic cut off may be controlled by a timer in volumetric bag filling, rather than by the scale mechanism 15. Also, in the case of a few materials, fluidization may not be necessary, and in other instances the fluidizing air may be supplied by means other than a diffuser pad which is lbpcated on the bottom wall of the conditioning cham- The invention is of particular utility when pneumatic controls are preferred to the electro-pneumatic control shown herein for the reason that the level responsive devices known to me are electrically operating. According to my invention, it is now possible to combine the advantages of a free space and controlled material level with the advantages of a completely pneumatic control system due to the elimination of an electrically operating level responsive device.

Although only preferred embodiments of my invention have been shown and described herein, it will be understood that various modifications and changes may be made in the constructions shown without departing from the spirit of my invention, as pointed out in the appended claims.

I claim:

1. A bag filling machine comprising a closed conditioning chamber, a bag filling spout communicating with the lower end of said chamber for filling a bag suspended therefrom, a cut off valve located between said filling spout and said conditioning chamber, means operative for closing said cut off valve at a predetermined time, a vertically disposed inlet pipe extending through the top wall of said chamber and terminating substantially below said top wall to provide a means for determining the initial level of material within said conditioning chamber, air supply means communicating with said chamber and including a constant delivery pump, a pressure relief valve therefor, and a normally open air supply valve, means for closing said air supply valve when said cut off valve is closed, a vent pipe leading from the upper portion of said chamber, a normally closed vent valve for said vent pipe, and means for opening said vent valve at the time that said cut off valve is closed, whereby the release of pressure within said conditioning chamber will permit material to flow through said inlet pipe into said chamber.

2. A bag filling machine as claimed in claim 1 having a hinged flap mounted on the lower end of said inletpipe.

3. A bag filling machine as claimed in claim 1 in which the lower end of said inlet pipe is flared.

4. A bag filling machine comprising a closed conditioning chamber, a bag filling spout communicating with the lower end of said chamber for filling a bag suspended therefrom, a cut off valve located between said filling spout and said conditioning chamber, sive means operative for closing said cut off valve when the weight of the bag and contents exceeds a predetermined Weight, a vertically disposed inlet pipe extending through the top Wall of said chamber and. terminating substantially below said top wall to provide a means for determining the initial level of material within said conditioning chamber, air supply means communicating with said chamber and including a constant delivery pump, a

pressure relief valve therefor, and a normally open airsupply valve, means controlled by said bag weight responsive means for closing said air supply valve when said'cut off valve is closed, a vent pipe leading from the upper portion of said chamber, a normally closed vent valve for said vent pipe, and means controlled by said bag weight responsive. means for opening said vent valve at the time that said cut off valve is closed, whereby the release of pressure within said conditioning chamber will permit material to flow through said inlet pipe into said chamber. I r I f 5. A bag filling machinecomprising'a closed conditioning chamber, afilling spout communicating with the lower end of said filling chamber for filling a bagsuspended therefrom, a cut off valve located between saidv filling spout and said conditioning chamber, bag weight responsive means operative for closing said cut off valve when the weight of the bag and contents exceeds a predetermined weight, a fluidizing pad disposed at the lower end of said conditioning chamber, a vertically disposed inlet pipe extending through the top wall of said chamber and terminating substantially below said top-wall to provide a means for determining the initial level of material within said conditioning chamber and providing a free space thereabove, top air supply means communicating with said free space and including a constant delivery bag weight respon-' pump and a pressure relief valve therefor, means actuated by said bag weight responsive mechanism for shutting off said top air supply means when said cut off valve is closed, and vent means controlled by said bag weight responsive mechanism for venting said chamber at the time that said cut off valve is closed, whereby the release of pressure within said conditioning chamber will permit material to flow through said inlet pipe into said chamber.

6. A bag filling machine as claimed in claim 5 which includes air supply means for said fluidizing pad, and means controlled by said bag weight responsive means for shutting off said fiuidizing pad air supply means at the time that said cut off valve is closed.

7. A bag filling machine as claimed in claim 5 in which said initial level determines a charge of material in said chamber representing from one and a half to two times the contents of the bag when filled.

8. A bag filling machine comprising a closed conditioning chamber having an outlet at its lower end, a bag filling spout communicating with said outlet for filling a bag suspended therefrom, a cut off valve located between said filling spout and saidconditioning chamber,

bag weight responsive means operative for closing said .cut off valve when the weight of the bag and contents exceeds a predetermined weight, a fiuidizing pad disposed at the lower end of said conditioning chamber adjacent to said outlet, a vertically disposed inlet pipe extending through thetop wall of said chamber and terminating substantially below saidtop wall to provide a means for determining the initial level of material within said conditioning chamber, top air supply means including a constant delivery pump and a pressure relief valve therefor communicating with the upper portion of said chamber, a normally open top air valve,'means actuated by said bag weight responsive means for closing said top air valve when said cut off valve is closed, a vent pipe leading from the upper portion of said chamber, a normally closed her will permit material to flowlthrough said inlet pipe vent valve for said vent pipe, and means controlled by said bag weight responsive means for opening said vent valve at the time that said cut off valve is closed, whereby the release of pressure within said conditioning chaminto said chamber.

References Cited RICHARD, B. WILKINSON, Primary Examiner. o. H. MILLER, A si t nt E miner-

Claims

1. A BAG FILLING MACHINE COMPRISING A COLSED CONDITIONING CHAMBER, A BAG FILLING SPOUT COMMUNICATING WITH THE LOWER END OF SAID CHAMBER FOR FILLING A BAG SUSPENDED THEREFROM, A CUT OFF VALVE LOCATED BETWEEN SAID FILLING SPOUT AND SAID CONDITIONING CHAMBER, MEANS OPERATIVE FOR CLOSING SAID CUT OFF VALVE AT A PREDETERMINED TIME, A VERTICALLY DISPOSED INLET PIPE EXTENDING THROUGH THE TOP WALL OF SAID CHAMBER AND TERMINATING SUBSTANTIALLY BELOW SAID TOP WALL TO PROVIDE A MEANS FOR DETERMINING THE INITIAL LEVEL OF MATERIAL WITHIN SAID CONDITIONING CHAMBER, AIR SUPPLY MEANS COMMUNICATING WITH SAID CHAMBER AND INCLUDING A CONSTANT DELIVERY PUMP, A PRESSURE RELIEF VALVE THEREFOR, AND A NORMALLY OPEN AIR SUPPLY VALVE, MEANS FOR CLOSING SAID AIR SUPPLY VALVE WHEN SAID CUT OFF VALVE IS CLOSED, A VENT PIPE LEADING FROM THE UPPER PORTION OF SAID CHAMBER, A NORMALLY CLOSED VENT VALVE FOR SAID VENT PIPE AND MEANS FOR OPENING SAID VENT VALVE AT THE TIME THAT SAID CUT OFF VALVE IS CLOSED, WHEREBY THE RELEASE OF PRESSURE WITHIN SAID CONDITIONING CHAMBER WILL PERMIT MATERIAL TO FLOW THROUGH SAID INLET PIPE INTO SAID CHAMBER.