Abstract:
Valving employed to control side closing elements of bag clamping apparatus of a bag filling machine is altered to cause the elements to move slowly to close the sides of a bag being filled whereby air is permitted to escape externally through slowly closing openings at the sides of the bag. At a predetermined time determined by the size and contents of the bag the openings are closed rapidly thereby sealing the bag once fitted.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable 
     STATEMENT REGARDING FEDERALLY SPONSORE RESEARCH OR DEVELOPMENT 
     Not Applicable 
     The present invention relates to bag clamping apparatus and more particularly to a modification of the sequencing of the operation of the side sealing air cylinders of U.S. Pat. No. 5,301,492 to allow de-aeration of a bag externally rather internally. 
     BACKGROUND OF THE INVENTION 
     In the aforesaid U.S. patent, air in a bag being filled escapes internally of the filling nozzle and reduces the area for product flow. 
     It is a primary object of the present invention to utilize in its entirety the apparatus illustrated in the aforesaid patent but to modify the sequencing of an element of the apparatus to permit air to escape externally through small open edge regions of the bag that are not closed until the bag is partially full. 
     BRIEF SUMMARY OF THE INVENTION 
     The structure of the apparatus employed in the present invention is identical to that illustrated in U.S. Pat. No. 5,301,492 and the description of operation is also identical except as specifically modified herein. Thus the description of operation of the device of the patent is incorporated herein by reference. 
     The only change relative to the device of the patent is in the sequencing of the gusset forming air cylinder  21  of FIG. 2 of the patent. In the patent the side sealing air cylinder caused the actuating elements  25  to grip and seal the edge of the bag against the end faces  3  of the filling spout and thus seal the bag. In consequence evacuation of air was internal. 
     According to the present invention this air cylinder is independently controlled such that the air cylinder is initially driven to extend by a low pressure, 1 bar, to maintain elements  25  away from the end faces  3  whereby openings in the edge regions of the bag are provided through which air may escape during filling externally to atmosphere. After a predetermined time which varies with bag size, the valve is switched to allow high pressure (6 bars) to be applied to cylinder  21  to rapidly bring the arms  25  against the end faces  3  and seal the bag. This action occurs when the bag is partially full. The degree of filling is a function of the material filling the bag. As determined by grain size, weight of the material, the bag is sealed at a time before dust and fines begin to escape. 
     The change in operation is achieved by the addition of three valves, two three-way, one four-way valve and a pressure regulator to control air flow to air cylinder  21 . 
     The above and other features, objects and advantages of the present invention, together with the best means contemplated by the inventors thereof for carrying out the invention will become more apparent from reading the following description of a preferred embodiment and perusing the associated drawings in which: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1 and 2 are the FIGS. 1 and 2 of U.S. Pat. No. 5,301,492; 
     FIG. 3 is a schematic diagram of the original valve controls for the various air cylinders employed in controlling the apparatus of FIGS. 1 and 2; 
     FIG. 4 is a valve operating chart for the valves of FIG. 3; 
     FIG. 5 is a schematic diagram of the modification of the valving to achieve the purposes of the present invention; and 
     FIG. 6 is an operating chart of the sequencing of the cylinders of the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIGS. 1 and 2, the operation of all elements is as stated in the patent except the operation of the air cylinder  21 . This cylinder controls the movement of the actuating elements  25  to move the coplanar pressure faces  27  to press the loosely open ends of a bag against end faces  3  of the filling spout. 
     Referring to FIG. 3, the valve controls, valves A, B, C &amp; D for the four air cylinders  23 ,  17 ,  11  and  21  are illustrated. The operation sequence of these valves is illustrated in FIG.  4 . An “X” indicates that the solenoid controlling the valve is energized. 
     Air cylinder  23  is, as are all of the air cylinders, illustrated in its start position, that is, prior to a bag being placed on the apparatus. The cylinders  23 ,  17 ,  11  and  21  are fed pressurized air from a source  41  via valves A and B/C and D. One or the other of the valves supplies air to manifold  43  or  44  and  55  or  56 , respectively. The pressure lines supply air to the cylinders through one-way adjustable exhaust controls  45  and  47  located on each port of each air cylinder. 
     In operation, upon a bag being placed on the spout, elements  11  and  23  are activated, valve A, FIG.  4 . The bird beak  10 , is then opened and gusset  27  is brought against side  3  by valve C to air cylinders  11  and  21 . The bag is filled and the valves return to the condition illustrated in columns A-D (valves A-D) of FIG.  4 . 
     It should be noted that the elements as set forth in FIGS. 1 and 2 are not necessarily in their start position, for instance, elements  22  are in the bag clamping position. 
     Referring now specifically to FIG. 5, the modified valve structure for control of air cylinder  21  is illustrated. Air cylinder  11  remains controlled by valve C-D. A four-way valve  40 , two three-way valves  42  and  44  and a pressure regulator  46  are added to the pneumatic system. 
     A pressure of 6 bar derived via lead  48  from the pressure supply  41  illustrated in FIG. 3, is applied to port  1  of valve  40 . Port  3  of valve  40  is applied to a vent  50 . Port  2  is connected to receive air from the cylinder  21  when deflected to its operative position. Port  4  of valve  40  is connected via pressure regulator  46  to port  1  of valve  42  and via lead  52  to port  3  of valve  42 . Output port  2  of valve  42  is connected to port  3  of valve  44  while its port  2  is connected to manifold  54  of the control for cylinder  21 . 
     In operation and reference is made now to FIG. 6 as well as FIG. 5, upon valve  40  assuming the position illustrated in FIG. 5; the valve  42  causes its port  2  to be in communication with port  1  and simultaneously valve  49  is shifted momentarily (via timer) to allow port  2  to communicate with port  1  to allow relief of high pressure (6 bar) air through vent  50 . A pressure of 1 bar is applied via regulator  46  to the manifold  54  since valve  49  is returned to a position providing communication between ports  2  and  3 . Such communication causes the piston of cylinder  21  to extend under 1 bar of pressure resisting it from collapsing thereby maintaining element  25  at a distance from bird beak side  3 . After a predetermined time that depends on bag size, the valve  40  is actuated to interconnect ports  1  and  2  of the valve (as illustrated in FIG. 5) and high pressure is applied to manifold  54  to collapse element  25  against side  3  under 6 bar pressure. With valve  40  in the position illustrated exhaust air from cylinder  21  retracting is directed to vent  50 . Reversal of the interconnection of the ports of valve  40  causes the piston of cylinder  21  to return to the home (extended) position illustrated in FIG.  5 . Having assumed its home position the piston of cylinder  21  is rested there by action of valve  40  to interconnect its ports  1  and  2 . 
     In the operation described in FIGS. 5 and 6, the opening of the face clamps by cylinder  11  pulls the side sealing clamps  25 - 27  toward the spout by the change in geometry of the bag as the bird beak opens. The outward pressure on the side sealing air cylinder  21  prevents gravity from drawing the side sealing clamps  25 - 27  against the side of the spout  2 - 3  thus creating openings between the bag and the side of the spout for external venting. These openings are then closed by application of 6 bar pressure through the valving sequence which directs high pressure to the opposite port on this cylinder. 
     Once given the above disclosure, many other features, modifications and improvements will become apparent to the skilled artisan. Such features, modifications and improvements are, therefore, considered to be a part of this invention, the scope of which is to be determined by the following claims.