US 3266217 A
Description (OCR text may contain errors)
Aug. 16, 1966 G. VAN DEN 805 APPARATUS FOR HYDRAULIC CONTROL OF THE TRANSVERSE SEALING JAWS OF A PACKAGING MACHINE Filed Dec. 19, 1963 IN VEN TOR: ER/PIT WW DEN B05 BY United States Patent 3,266,217 APPARATUS FOR HYDRAULEC CGNTRGL OF THE TRANSVERSE SEALENG .lAWS 6F A PACKAG- ING MACHlNE Gerrit van den Bus, Weert, Netherlands, assignor to Hamac-Hansella Aktiengesellschaft, Viersen, Germany, a corporation of Germany Filed Dec. 19, 1963, er. No. 331,664 Claims priority, application Germany, July 19, 1963, H 49,763 11 Claims. (Cl. 533-480} This invention relates to an apparatus for hydraulically closing the transverse sealing jaws of a packaging machine of the type in which a tube of packaging material is advanced by such jaws in an intermittent fashion to bring successive regions to a filling position and to seal off such regions after they have been filled.
In machines of this kind, the jaws are movable toward and away from each other and also in an up-and-down direction. They are operated so as to come together at the upper end of their travel, thus engaging the tube above the region just filled; then they move downwardly to draw the tube down through a predetermined distance; then they separate and travel upward so that the procedure can be repeated. During each period of rest of the tube, the items to be packaged are introduced into the tube from above to fill the tubular part that has been pulled down. When the jaws come together they form a top seal on the filled portion, and may cut it off to form a filled bag. At the same time, the bottom seal of the next tube portion is produced.
An object of the invention is to provide an improved hydraulic mechanism for controlling the movements of the jaws toward each other, and by means of which the speed of operation and thereby the output of the packaging machine can be increased, and the idling ope-ration of the machine improved, thereby reducing wear and tear.
According to the invention the apparatus involves two opposed hydraulic cylinders on whose pistons the sealing jaws are mounted in opposed relationship, the cylinders being actuated by a pumped pressure fluid, the pump being a piston pump driven in timed relation to the packaging procedure. The device is characterized by a communication between the pump and a special cylinder with which a pressure-regulating valve is associated; and by an auxiliary pump and a regulating valve which feed extra pressure fluid into the first-mentioned piston pump at the instant of the commencement of the suction or return stroke of the latter.
In accordance with one of the features of the invention, the last-mentioned regulating valve has a cylindrical bore in which a rotating :plug is mounted for rotative movements in timed relation to the packaging procedure. There is an annular groove in the cylindrical bore which is in constant communication with the auxiliary pump. There is also a communication between the regulating valve and the main pressure-fluid piston pump, this communication leading to the cylindrical bore referred to. On the rotating plug there is a groove or cut-out which connects the last-mentioned communication with the annular groove previously referred to at predetermined positions of the plug during the course of its rotative movements.
Further details of the invention will become clear from the following description of a preferred embodiment of the invention, and reference should be made to the accompanying drawing in which the apparatus is schematically depicted.
The reference numeral 1 is directed to a schematic rep resentation of the transverse sealing jaws of a packaging machine of the character mentioned. These jaws are se- 3,266,217 Patented August 16, 1966 cured to the piston rods of two pistons 22 mounted in opposed relationship in fluid pressure cylinders 2. Between the pistons and the forward ends of the cylinders compression springs 3 are arranged, designed to open the jaws 1 against the action of the pressure fluid, preferably oil. In place of the springs 3, tension springs arranged on the exterior of the cylinders could be used for the same purpose.
The cylinders 2 are in communication with each other via the pipe or conduit 4. A pressure regulating unit 9 is also in communication with the pipe 4. The unit 9 consists of a cylinder in which a piston 93 is mounted. A pipe extends from one end of the cylinder to the pipe 4. A spring 92 presses at one end against the piston 93 and bears with its other end against an adjusting device 911 which can be projected into the cylinder 9 by varying amounts by screwing it or unscrewing it with respect to the cylinder wall. In this way, a predetermined spring pressure can be exerted against the piston, variable at will.
The arrangement is so designed that the stroke-volume of the piston 8 is somewhat greater than that of the combined pistons 22, as a result of which the piston 93 a ways exerts a predetermined pressure against the spring 92. Thus, the pressure in the system, and thus the pressure between the jaws 1, is determined by the adjustable spring pressure against the piston 93.
A communication 5 extends from pipe 4 to fluid pressure pump 6. The pump '6 is, in the illustrated embodiment, shown as a piston pump. The piston 8 has a piston rod 82 on whose end a cam follower 77 is mounted, hearing against the eccentric disk 7. The latter is driven in the direction of the arrow by means of the driving mechanism of the packaging machine. As the follower 77 rolls on the periphery of the eccentric disk 7 the piston 8 is caused to partake of a reciprocating motion within the cylinder 6. A spring 81 is mounted in this cylinder and urges the piston constantly upward, thus holding the follower 77 against the periphery of the disk. 7. The spring 31 is by itself insulficient for this purpose; it is aided by the springs 3 (via the oil pressure) and by the oil transmitted to it by means of the pump 11.
On the pressure side of the pump 6 there is a safety valve 18, illustrated in the form of a ball valve whose ball 181 is pressed by a spring 182 against its seat. A communication 183 leads to the oil reservoir.
The pump 6 is also in constant communication, by a pipe 10, with a regulating valve 14. The fixed block 141 of this valve has a central cylindrical bore 142 in which a rotatable plug 16 is mounted. This plug is rotated by the drive of the packaging machine. In the wall of the bore 142 there is an annular groove 15 which communicates with a conduit 12. The pipe or communication 10 extends through the body of the valve 14 and terminates in communication with the cylindrical bore 142. The plug '16 has on its periphery a groove 17 which is of such size that it connects the mouth of the communication 10 with the annular groove 15 whenever the groove 17 (during the course of the rotative movements of the plug 16) comes into registry with the mouth of the communication 10.
The communication 12 leads to a pressure fluid pump 11 which in the illustrated embodiment is a gear pump consisting, r'or example, of two meshing gears which rotate in opposite directions as shown by the arrows. The pump 11 is fed from the oil supply or oil reservoir (not shown) through a filter 111.
In the communication 12 there is also provided a pressure relief valve 13, which, like the safety valve 18, has been shown as a ball valve, the ball I131 being pressed by a spring 132 against its valve seat. The outlet side of 3 the pressure relief valve 13 is connected to the conduit 19 forming part of the lubricating system of the entire machine.
The apparatus operates as follows: The eccentric disk 7, driven :in timed relation to the packaging machine, presses during its rotation against the roller 77 and thus moves the piston 8 on the piston rod 82 against the action of the spring 81. As a result, the fluid in advance of the piston is caused to flow through the conduits 5 and 4 to the cylinders 2 whereby the sealing jaws 1 are brought together into a closed relationship. The springs 3 are so chosen that the fluid pressure against the pistons 22 is great enough to overcome the pressure of the springs 3. When the piston S in cylinder 6 has reached its lowest point of movement, the continued rotation of the disk 7 results in a return movement of the piston 8 under the influence of the spring 81. However, because of the inertia of the pressure fluid in the conduits 4 and 5, a reduced pressure temporarily manifests itself in cylinder 6. In accordance with the invention, at this instant of time the rotating plug 16 of the regulating valve 14 (which, like the pressure pump 6, is driven in timed relation to the packaging machine) will have rotated to a point at which the groove 17 establishes communication between the conduits 10 and 12 and thus with pump 11. As a result, pressure fluid flows through the conduit 12 and through the regulating valve 14 to and through the conduit 10 into the cylinder 6. Since the capacity of the cylinder 6 corresponds exactly to the combined capacity of the cylinders 2 and the pressure regulating unit 9, an excess of pressure fluid exists in the system 2, 4, 5, 9 and 10 at the end of the return stroke of the piston 8. The curvature of the eccentric disk 7 is of such character that the piston 8 remains for a short period of time at its uppermost position. As a result, it is possible during this short period of time for the excess fluid, under the action of the springs 3, to flow ofi through the regulating valve 14, the movements of the plug 16 being so regulated that the groove 17 still connects the conduits 10 and 12. At the conclusion of this procedure, the connection between the conduits 1t) and 12 is broken off by further rotation of the plug 16, and the pump 11 thereupon delivers oil through the pressure relief valve 13 into the lubricating system 19. The auxiliary pump 11 thus serves also as a pressure pump for the lubricating system of the packaging machine.
The ability quickly and temporarily to introduce added fluid into the pump chamber 6 at the instant of commencement of each return stroke of the piston 8 results in all-owing the packaging machine to be operated much more rapidly.
In a preferred embodiment of the invention the springs 3, 92, 132, and 182 are so chosen that the force of the springs 3 upon the pressure fluid is in the region of 6 atmospheres in the cylinders 2, the force of the spring 92 is such as to transmit to the piston 93 and thus to the pressure fluid in the conduits 4 and 5 a pressure of from 10 to atmospheres, the valve 13 opens under an excess pressure of 2 atmospheres, and the safety valve 18 opens under an excess ressure of atmospheres.
What is claimed is:
1. In a packaging machine in which a tube of packaging material is drawn between a pair of sealing jaws, the jaws being movable toward each other to clamp the tube between them and produce a transverse seal in the tube, and away from each other to release the tube:
hydraulic apparatus for controlling said movements of said jaws comprising a piston-cylinder device allocated to each of said jaws, said jaws being connected to the pistons of their respective devices, a piston pump communicating with said cylinders through a conduit, means for moving the piston of said pump through alternate pressure and suction strokes, a regulating valve, an auxiliary pump adapted to communicate with said piston pump through said regulating valve, and means for controlling said regulating valve to establish communication between said auxiliary pump and piston pump only during the suction stroke of said piston pump.
2. In a packaging machine, the elements defined in claim 1 including a pressure control valve communicating with the conduit connecting said piston pump and piston-cylinder devices.
3. In a packaging machine, the elements defined in claim I wherein said regulating valve comprises a body having a cylindrical bore, a plug rotatably mounted within said bore, said plug having a groove in its surface, a first conduit connecting said auxiliary pump to said regulating valve and terminating at the inner surface of said bore, and another conduit connecting said piston pump to said regulating valve and terminating at the inner surface of said bore near the terminal of said first conduit, said plug being rotatable intermittently to bring said groove into communication with the terminals of said conduits in the inner surface of said bore, said regulating valve control means serving to rotate said plug in timed relation to the operation of said piston pump.
4. In a packaging machine, the elements defined in claim 3, in which said bore is provided with an annular groove at the termination of said first conduit, whereby said groove in the plug is in constant communication with the conduit leading to said auxiliary pump.
5. In a packaging machine, the elements defined in claim 3 including a pressure relief valve communicating with the conduit between said auxiliary pump and said regulating valve.
6. In a packaging machine, the elements defined in claim 3 wherein said auxiliary pump is a gear pump.
7. In a packaging machine, the elements defined in claim 1 including a safety valve communicating with said piston pump.
8. In a packaging machine, the elements defined in claim 1 wherein the pressure fluid from said piston pump urges said jaw-carrying pistons toward each other, and in which there are springs within said cylinders for urging said pistons away from each other.
9. In a packaging machine, the elements defined in claim 1 including an eccentrically driven disk for moving the piston of said pump through its pressure stroke, and a follower carried by said pump piston and adapted to be engaged by said disk.
10. In a packaging machine, the elements defined in claim 9 including a spring within said piston pump for urging said piston along its suction stroke.
11. In a packaging machine, the elements defined in claim 5 wherein the outlet from said pressure relief valve communicates with the lubricating system of the packaging machine.
References Cited by the Examiner UNITED STATES PATENTS 2,437,821 3/1948 Hughes -545 FRANK E. BAILEY, Primary Examiner. S. ABEND, Assistant Examiner.