GB1576540A

GB1576540A - Sealing devices

Info

Publication number: GB1576540A
Application number: GB3967977A
Authority: GB
Original assignee: Schweizerische Industrie Gesellschaft
Current assignee: Schweizerische Industrie Gesellschaft
Priority date: 1976-11-23
Filing date: 1977-09-23
Publication date: 1980-10-08
Also published as: IT1091245B; DE2740176A1; CH598994A5

Description

(54) IMPROVEMENTS RELATING TO SEALING DEVICES (71) We, SIG SCHWEIZERISCHE IN DusTRIE-GEsELLscHAFr, a Swiss Body corporate, of 8212 Neuhausen am Rheinfall, Switzerland, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to a sealing device adapted to be mounted on a packaging machine for forming filled bags.

A previously proposed sealing device has two identical continuously driven drums which have in a peripheral direction at least one row of depression bordered by longi tudinal and transverse ridges and between which two sealable packing sheets filled with portions of a substance to be packed are supplied in such a manner that the portions come to lie in the drum depressions whereupon these sheets are sealed together along the longitudinal and transverse ridges.

The two drums are electrically heated and are set in contrarotation so that the two sheets are pressed onto one another between the longitudinal and transverse ridges of the drums to form the sealing seams. Such a device works satisfactorily as long as the drums have a relatively low peripheral speed and provided that only a few rows of adjacent-lying depressions produce only a low output or if more expensive packing materials which are insensitive to uneven sealing pressure and sealing temperature are used.

A sealing device according to the invention comprises a drum which is adapted to be continuously driven and which has on the periphery thereof at least one row of surface depressions bounded by longitudinal and transverse ridges, means for supplying two sealable packaging sheets to the periphery of the drum with discrete portions of a material to be packaged therebetween in such a manner that such discrete portions come to lie in the drum depressions, at least one pair of sealing rollers urged .resiliently onto the longitudinal ridges to form at least two longitudinal seams -in the packaging Sheets and at least one sealing jaw which is adapted to be altemately::.raised from the drum and then urged resiliently onto its successive transverse ridges to form transverse seams in the packaging sheets The invention is further described, by way of example, with reference to the accompanying diagrammatic drawings, in which: Fig. 1 is a partially sectioned sideview of a sealing device for forming filled bags, and Fig. 2 is a plan view of the device of Fig. 1 likewise partially sectioned.

The illustrated device has a drum 1 having two adjacent-lying rows of surface depressions, each depression comprising a flat milled portion 2, the depressions being of equal size and uniformly distributed about the periphery of the drum with ten depressions in each row. The drum 1 is mounted on a shaft 3 which is continuously driven by a motor 44 by way of a bevel gears 4 and a main shaft 5. Between and around the milled portions 2 are longitudinal ridges 6 and transverse ridges 7, the terms "longitudinal" and "transverse" referring to the rows of milled portions 2. The drum 1 is provided with ten electrical heating rods 8 which are housed inside the drum in the vicinity of the transverse ridges 7.

The drum 1 is supplied with a first packaging sheet 9 of sealable, e.g. weldable material on which two adjacent-lying rows of portions 10 of the materials to be packaged, e.g. tea, are placed in the form of flat piles by a metering device (not shown).

The spacing between the portions 10, which are supplied between the sheets 9 and 10, is chosen so that each portion comes to rest on the drum in a recess 11.'A second packing sheet 12 of the same typè is additionally supplied to the drum 1 so that it comes to lie on the first sheet 9 and Abe portions 10 are enclosed in the recesses i1 between the two sheets 9 and 12, this being illustrated only at 101. It may be seen that, when the sheets 9 and 12 are joined to gether along the ridges 6 and ? by sealing seams, a web of closed bags or sachets 13 is formed, each of said bags each coriddin- ing one portion 10 and being held together by longitudinal seams 14 and transverse seams 15.

Four sealing rollers 16 and four sealing rollers 17 are provided for manufacturing the longitudinal seams 14. Each pair of seal ing rollers 16' - 5 .'freely rotatably mounted on the ends of a respective axle 18 which is journalled at its middle on one end of a lever 19. The other end of the lever 19 is pivotable about a frame-fixed pin 20 and the lever is urged by a compression spring 21 towards the drum 1 so that the sheets 9 and 12 are' pressed together between the rollers 16 and the longitudinal ridges 6.

In so doing, the rollers 16 are set in rotation as a result of friction. Since the drum 1 is heated. by the heating rods 8, - it is not absolutely - - necessary to heat the sealing rollers.:1.6. -'also, -,th6ugh obviously this could easily. be done.

Fig. 2 shows another variation in which a pair of rollers 16 is urged by compressed air towards the drum.. 1, said compressed air being supplied: to a frame-fixed piston guide 22. In the guide 22 a piston 23 is movable and presses upon the lever 19 associated with the relevant pair of rollers 16.It is clear that in an actual construction both pairs of rollers - 16 are urged either by springs 21 or by compressed air towards the drum - 1. - Whereas :the four sealing rollers 16 are located. at. a- point at which the sheets 9 and 12 - run up tangentially to the drum 1, the four sealing rollers 17 are mounted at a point at which these sheets 9, 12 run off from the drum. The four rollers 17 are fixed to a shaft 24 whose mounting (not shown) is urged by compression springs towards the drum 1.The' shaft 24 is driven by way of levej-gears 25 by the main shaft 5 and in such a manner that the peripheral speed of the - rollers 17 is somewhat greater than the peripheral speed of the drum 1, the result being a certain- tautening of the longitudinal seams 14 so that the sheets 9 and 12 are held in close contact with the drum 1. The sealing rollers 17 are therefore used to -tauteW -and subsequently seal the sheets 9 and 12.

To form the transverse seams 15 also, the sheets 9 and 12 are sealed twice in succes sion by means of two sealing jaws 26 which are, each urged in the region of a transverse ridge 7 towards the drum 1. As may be seen from; Fig. 2, each sealing jaw 26 com prises two portions 261 and 262 which are heated by a heating rod 27. The heating rod 27 is held rmly on a carrier 29 by holders 28 (npt shown in Fig. 2). which are arranged in pairs.The sealing jaw portions 261 and 262 are individually movable relative to the heating rod 27 and are spring-loaded, this construction being described in detail in (Serial No. 1,558,140) filed concurrently herewith. This is particularly advantageous with relatively long sealing jaws to obtain a uniform pressure and temperature-distri- bution. In Fig. 2 it is merely indicated that the sealing jaw portions 261 and 262 may be urged. resiliently away from the carrier 29 by compression springs 30 or by.pistons 31 subjected to compressed air.However, limiting means described in the -above-- mentioned Patent Specification are' also pro vided to prevent the portions 261 and 262 from becoming detached from the carrier 29.

The carrier 29 is fixed on a flat milled por tion 32 - of a hollow cylinder 33, e.g. - by means of screws (not shown). The ends of the hollow cylinder 33 are supported by means of ball bearings 34 in two bearing brackets 35 which have eccentric hubs 36 which rest on a shaft 37 and are fixed thereon by means of rods 38. The shaft 37 is driven by the main shaft 5 by way of level gears 39. The bearing brackets 35 are omitted from Fig. 1. On the side of the hollow cylinder 33 opposite the milled por tion 32 is fixed an arm 40 which carries a roller 41 or a slide ring. The roller 41 is guided in a ftame-fixed guide 42 radially with respect to the drum 1.When the shaft 37 eccentric to the hollow cylinder 33 is at its greatest distance from the carrier 29, the sealing jaw 26 is urged resiliently to wards the transverse ridge 7 lying opposite it at that moment so that a transverse seam 15 is formed. This position is illustrated for the first sealing jaw 26 following the sealing rollers 16. When the shaft 37 is on the other hand at its shortest distance from the carrier 29, the sealing jaw 26 is raised off the drum 1, this being shown for the second sealing jaw 26 following the sealing rollers 16. Be tween these two extreme positions, the face of the sealing jaw 26 facing the drum 1 effects a movement along an approximately elliptical path 43 and the jaw 26 presses against the periphery of the drum 1 because of the action of the springs 30 or of the compressed air. The speed of the sealing jaw 26 during proximity is substantially equal to the peripheral speed of the drum 1 so that the sheets 9 and 12 are urged on to one another over an angle of rotation of several decrees. The two shafts 37 rotate ten times faster than the drum 1 so that the two sealing jaws, 2 are effective on each of the transverse ridges 7. At this point it should be mentioned that in Fig. 1 the bevel gears 4, 25 and 39 are illustrated purely diagrammatically so that their relative di mensions as illustrated are no indication of their transmission ratios.

The described device forms satisfactory longitudinal and transverse seams åt high output. The device is easily accessible and the structural outlay is relatively low.

The drum 1 may alternatively have only one or more than two rows of surface depressions 11, in which case its base may a trough-shaped instead of flat. In the present connection, "sealing" may also include welding, i.e. attachment of where the sheets, one to another, in which the entire thickness of the material of the sheets 9 and 12-fuses and not only the material of coating layers.

It is clear following the illustrated sealing device, the packaging machine may additionally be provided with a cutting device to cut the longitudinal- and transverse seams 14 and 15 at their centres and thereby separate the individual filled bags 13.

WHAT WE CLAIM IS: 1. A sealing device for a packaging machine for forming filled bags or sachets, comprising a drum which is adapted to be continuously driven and which has on the periphery thereof at least one row of surface depressions bounded by longitudinal and transverse ridges, means, for supplying two sealable packaging sheets to the periphery of the drum with discrete portions of a material to be packaged therebetween in such a manner that such discrete portions come to lie in the drum depressions, at least one pair of sealing rollers urged resiliently onto the longitudinal ridges to form at least two longitudinal seams in the packaging sheets and at least one sealing jaw which is adapted to be alternately raised from the drum and then urged resiliently onto its successive transverse ridges to form transverse seams in the packaging sheets.

2. A sealing device as claimed in claim 1, in which there are first and second pairs of sealing rollers and two sealing jaws so that each longitudinal and transverse seam is formed by a first sealing means and is reinforced by a second sealing means.

3. A sealing device as claimed in claim 2, in which the first pair of sealing rollers is freely rotatable while the second pair of sealing rollers is adapted to be driven in such a manner that their peripheral speed is somewhat greater than that of the drum.

4. A sealing device as claimed in claim 1, 2 or 3, in which the or each sealing jaw comprises at least two portions which are individually resiliently urged away from a carrier which, in operation, is periodically moved towards and away from the drum.

5. A sealing device as claimed in claim -4, in which the sealing jaw is mounted to move along a substantially elliptical path and presses against the periphery of the drum as a result of the resilient bias, the sealing jaw speed, whilst pressing against the periphery of the drum, substantially equalling the peripheral speed of the drum.

6. A sealing device as claimed in claim 5, in which the carrier is fixed on a hollow cylinder which is eccentrically supported relative to a driven shaft and is provided with an arm having a head which is guided in a frame-fixed guide radially with respect to the drum.

7. A sealing device as claimed in claim 4 or 5 in which the sealing jaw portions are heated by a common electrical heating rod which is held firmly on the carrier by holders arranged in pairs.

8. A sealing device as claimed in any one of claims 1 to 7 in which the resilient loading of the sealing rollers and/or sealing jaws is effected by compression springs.

9. A sealing device as claimed in any one of claims 1 to 7 in which the resilient loading of the sealing rollers and/or seal ing jaws is effected pneumatically.

10. A sealing device for a packaging machine for forming bags or sachets, con structed and adapted to operate substantially as herein described with reference to and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. output. The device is easily accessible and the structural outlay is relatively low. The drum 1 may alternatively have only one or more than two rows of surface depressions 11, in which case its base may a trough-shaped instead of flat. In the present connection, "sealing" may also include welding, i.e. attachment of where the sheets, one to another, in which the entire thickness of the material of the sheets 9 and 12-fuses and not only the material of coating layers. It is clear following the illustrated sealing device, the packaging machine may additionally be provided with a cutting device to cut the longitudinal- and transverse seams 14 and 15 at their centres and thereby separate the individual filled bags 13. WHAT WE CLAIM IS:

1. A sealing device for a packaging machine for forming filled bags or sachets, comprising a drum which is adapted to be continuously driven and which has on the periphery thereof at least one row of surface depressions bounded by longitudinal and transverse ridges, means, for supplying two sealable packaging sheets to the periphery of the drum with discrete portions of a material to be packaged therebetween in such a manner that such discrete portions come to lie in the drum depressions, at least one pair of sealing rollers urged resiliently onto the longitudinal ridges to form at least two longitudinal seams in the packaging sheets and at least one sealing jaw which is adapted to be alternately raised from the drum and then urged resiliently onto its successive transverse ridges to form transverse seams in the packaging sheets.