GB2100218A

GB2100218A - Method of and apparatus for packing goods between opposed webs

Info

Publication number: GB2100218A
Application number: GB8214017A
Authority: GB
Original assignee: Kramer and Grebe GmbH and Co KG; Kraemer and Grebe KG
Current assignee: Kramer and Grebe GmbH and Co KG; Kraemer and Grebe KG
Priority date: 1981-05-13
Filing date: 1982-05-13
Publication date: 1982-12-22
Also published as: DE3118912A1; FR2505774A1; CH655697A5; NL8201936A; IT8248392A0; SE8202893L; DK214282A

Abstract

An apparatus for packing goods between opposed webs (2, 9) comprises a drawing station (3, 5, 6) for forming wells (7) in a lower web (2), and a heat-sealing station for heat-sealing an upper web (9) around the edges of the wells (7) in the lower web (2) after the goods have been introduced in the wells (7). In the heat-sealing station, vertically displaceable welding elements (10, 13) for longitudinal and transverse seams are arranged below the webs (2, 9). Longitudinal welding elements (10) are arranged over the web width in accordance with the particular number of longitudinal seams required and the length of said longitudinal welding elements is equal to or greater than the length of the individual packs to be formed. The transverse welding elements (13) are situated downstream of the longitudinal welding elements and are displaceable in the longitudinal direction of web advance. The welding elements, which are interchangeable with one another, are constructed as plug-in elements. <IMAGE>

Description

SPECIFICATION Method of and apparatus for packing goods This invention relates to a method of and apparatus for packing goods between two sheets and is particularly concerned with a method and apparatus in which a trough or well is formed in one sheet to receive the goods which are introduced into the trough or well, whereafter the edge of the trough or well is heat-sealed to a second sheet.

In previously proposed methods and apparatus for effecting such packing, the heat-sealing operation is carried out by a welding frame which is generally of aluminium plate with projecting transverse and longitudinal ribs in accordance with the desired outline of the heat seal. Heating rods or heating plates are provided in the plate which deliver to the aluminium plate heat which is regulated by means of a sensor and a thermostat.

The longitudinal and transverse ribs via which the heat is transmitted to the sheets are heated by the aluminium plate.

A pack is normally heat-sealed at the edges between two transverse seams and two longitudinal seams, and a plurality of packs may also be sealed in one working operation. The requisite welding plate comprises for this purpose a plurality of longitudinal and transverse welding ribs corresponding to the particular pack size in question.

The welding plate is arranged above the two sheets to be heat-sealed, whereas below the sheets a chamber is provided which has webs in accordance with the arrangement and width of the seams or the transverse and longitudinal welding ribs. In order to carry out the heat-sealing operation, the chamber is lifted by a lifting apparatus, whereupon the welding plate is lowered by pneumatic apparatus. In the process the sheets are pressed together and brought to sealing temperature by the heat transmitted to the sheets from the welding plate, whereby the sheets are heat-sealed to one another.

This conventional arrangement necessarily involves a number of serious disadvantages.

Thus, it has been found that it is very difficult to achieve uniform heat distribution to the longitudinal and transverse ribs. The temperature differences are in some cases so great that in a heat-sealing operation one part of the seams being formed does not seal whilst another part in burned by overheating.

In the case of blister packs, wherein the upper sheet consists of card, it is necessary to work with excessive sealing temperatures and sealing times in order to reach the necessary sealing temperature between the two sheets, so that as a result there are additional energy and time losses during operations.

Moreover the area of the seam(s) varies depending on the number and size of the packs to be welded. Since the pneumatically driven welding plate is always driven with the same force, independently of the area of the seam(s) this leads to considerable differences in the pressure per unit of area, so that often this is inadequate for satisfactory sealing.

Finally, another welding plate and welding chamber is required for each pack size with which the machine is to be used, so that not only are conversion times considerable but also there are considerable costs involved in setting up the machine and storage of the welding plates and chambers.

It is an object of the present invention to provide a method of and apparatus for packing goods in which heat sealing can be carried out uniformly and quickly, while reducing the risk of overheating the sheet material.

According to one aspect of the present invention there is provided a method of packing goods between two sheets, wherein a trough or well is formed in one sheet, the goods are introduced into the trough or well, and the edge of the trough or well is heat-sealed to a second sheet, and wherein individual welding elements are brought from below to between and adjacent the troughs or wells distributed over the sheet width so as to form a first heat-sealed seam(s) between the lower sheet and the upper sheet which is at least the length or width of the pack, a second heat-sealed seam(s) being thereafter formed between the lower sheet and the upper sheet which is at least the width or length respectively of the pack by means of welding elements brought in from below thereby to seal the packs.

Preferably the two sheets travel through a packing machine and the first seam(s) is (are) formed in the direction of travel and the second seam(s) is (are) formed transverse to the direction of travel.

According to another aspect of the present invention there is provided apparatus for packing goods between two sheets, wherein the apparatus comprises means for feeding a first sheet of material, a deep-drawing station for forming troughs or wells for the goods in the sheet material, an insertion station for putting the goods into the troughs or wells, and a heat-sealing station at which the edge of the trough or well preformed from the first sheet is heat-sealable to a second and upper sheet by pressure and heat, and wherein vertically displaceable welding elements for forming longitudinal and transverse heatsealed seams are arranged at the heat-sealing station for engaging the sheets from below to effect heat-sealing, longitudinal welding elements being arranged in interchangeable fashion parallel to the side edge of the sheets in accordance with the number of longitudinal seams required over the sheet width, the length of the longitudinal welding elements being equal to or greater than the length (in the direction of travel of the sheets) of the individual packs, and transverse welding elements being arranged substantially at right angles to the side edges of the sheets and being displaceable in the longitudinal direction of travel of the sheets.

As a result of the arrangement of the welding elements, the present apparatus has a wide range of versatiiity as well as bringing a number of considerable advantages. The sheet width can be divided substantially optionally in a simple manner depending on the particular pack size intended, without it being necessary to replace a welding frame in a time-consuming operation, and the transverse welding can be suitably carried out.

Because the welding elements are brought up from underneath the sheets, it is no longer necessary to work with excessive heating temperatures and times, as for example when dealing with blister packs. A uniform heat-sealed seam is obtained, since the welding elements brought towards the sheet from below are at approximateiy the melting temperature of the sheets to be sealed. Thus overheating of the sheets cannot occur even with multiple weldings.

Finally, the present apparatus also dispenses with the entire arrangement for lowering a welding frame, so that the production costs for the installation can be reduced considerably. Thus there is no format-dependent welding frame or format-dependent welding mould.

Preferably, the transverse welding elements are of the same length as the longitudinal welding elements. Consequently the welding elements are interchangeable, which means simplified handling and further cost advantages.

The width of the welding elements conveniently corresponds to twice the width of a longitudinal or transverse seam, so that a normal seam width is obtained after sealing following a central severing.

The height of the welding bar is preferably such that it can accommodate only one heating rod or element and a temperature sensor. Consequently, only an inconsiderable mass has to be heated, so that a uniform heat-sealing temperature is achieved over the welding element, overheating of other pack regions is obviated, and energy is saved. At the same time no heat accumulation problems occur in central zones of the welding frame such as have been common in conventional instailations of this kind.

It is convenient to separate the welding element from its support by means of an insulating plate. Below the support there are arranged elastic elements for applying the welding pressure, and these elastic elements may consist of springs, rubber or piston and cylinder units. The result is thereby achieved that the welding element is always pressed with the same force of application against the sheets to be sealed. In this way a constant surface pressure is achieved irrespective of the particular pack size, thus ensuring that the seams are of uniform high quality.

Covering the two sides of the welding elements with insulating panels provides additional protection of the side regions of the pack from overheating.

In order to enable the invention to be more readily understood, reference will now be made to the accompanying drawings, which illustrate diagrammatically and by way of example two embodiments thereof and in which: Figure 1 is a side view of a packaging machine, Figure 2 is a view of longitudinal welding elements at a heat-sealing station in the machine shown in Figure 1, Figure 3 is a view corresponding to Figure 2 but showing a modification of the heat-sealing station, Figure 4 is a view of a transverse welding element at a heat-sealing station in the machine shown in Figure 1, and Figure 5 is a vertical section through a welding element.

Referring now to the drawings, a packaging machine is shown diagrammatically in Figure 1 and comprises a deep drawing station where troughs or wells are formed in a sheet of heatsealable plastics material for receiving the goods to be packed, the sheet constituting a lower sheet, a filling station in which the goods are put into the troughs or wells, a heat-sealing station in which an upper sheet is heat-sealed on to the lower sheet thereby closing the troughs or wells, and a cutting station in which the individual packs are detached from one another.

The lower sheet 2 in the form of a web or band is drawn stepwise off a rotatably mounted supply roller 1 and fed to the deep drawing station, passing between an upper preheating plate 5 and a lower preheating plate 6, whereby it is brought to the required softening temperature. A deep drawing mould 3 is mounted together with the lower preheating plate 6, on vertically displaceable rails 4.

During the advance of the lower sheets 2, a section of the sheet is heated at each step between the preheating plates 5 and 6 whilst the section which has previously passed between the plates is shaped by a deep drawing mould to form a trough or well 7 or a plurality of troughs or wells situated adjacent one another. The open troughs or wells 7 are then fed to the filling station where the goods are put into the troughs.

The filling station which is not described is followed by the heat-sealing station of the packaging machine, in which the upper sheet 9 also of heat-sealable plastics material is drawn from a rotatably supported supply roller 8 and fed from above into contact with the lower sheet 2.

Vertically displaceable lifting rails 12 are also arranged in the region of the welding station, below the sheets 2 and 9. The lifting rails support transverse welding elements 1 3 and a supporting plate 26 for longitudinal welding elements 10 while a counter-pressure plate 11 is situated opposite the longitudinal welding elements 10 above the sheets 2 and 9.

Figures 2 and 3 show vertical sections through two different supporting plates 26, longitudinal welding elements 10 and counter-pressure plates 11. In each case the longitudinal welding elements 10 are constructed as plug-in elements, which are insertable in bores 27 within the supporting plate 26. The bores 27 are so arranged in the supporting plate 26 that a longitudinal welding element 10 can be mounted so as to lie between or adjacent a pack in accordance with the required particular subdivision of the total sheet width into the various pack widths. In the constructional form shown in Figure 2, four packs situated side by side are provided over the sheet width, whereas in the constructional form shown in Figure 3 where are only two packs adjacent one another over the sheet width.The bores 27 may be so arranged that for example, up to six packs adjacent one another can be heat-sealed simultaneously over the width of the sheet. When the pack width changes it is simply necessary to re-plug the longitudinal welding elements 10 appropriately.

As Figures 1 to 3 illustrate, there is a counterpressure plate 11 opposite the longitudinal welding elements 10, and in the constructional form shown in Figure 2 profiled strips 24 are arranged in the counter-pressure plate 11 in correspondence with the positions of the bores 27 in the supporting plate 26. Thus, independently of the plugged-in pattern of the longitudinal welding elements 10 there is always a profiled strip 24 situated opposite each such element for the heatsealing operation. In the constructional form shown in Figure 3 the underside of the counterpressure plate 11 is provided with a rubber covering 25. Thus here also heat-sealing can be carried out without any problem irrespective of the arrangement in which the longitudinal welding elements 10 are plugged.

Downstream of the supporting plate 26 in the direction of advance of the sheets 2 and 9, transverse welding elements 13 are arranged on the lifting rails 12. The transverse welding elements 13 are also constructed as plug-in elements and preferably have the same length as the longitudinal welding elements 10, so that they are interchangeable with these. The position of the transverse welding elements 1 3 on the lifting rails 1 2 is displaceable in the direction of advance of the sheets, so that adaptation to the particular pack length is possible without difficulty.As Figure 4 shows, the transverse welding elements 13 are plugged into a supporting rail 28 which in its turn is held by the lifting rails 1 2. Counter-pressure rails 29 with profiled strips 30 are situated opposite the transverse welding elements 13, above the sheets, for executing the transverse seam. An important advantage of the present construction that the individual adjustabiiity of the transverse welding elements allows alignment of the upper sheet 9 to the lower sheet 2, for which purpose an adjusting arrangement involving much outlay was required in conventional apparatus of this kind.

The construction of the welding elements will be discussed in more detail now with reference to Figure 5. The welding elements 10 and 13 each comprise a welding bar 1 7 the height of which is dimensioned only such as to be able to accommodate a heating element 1 9 and a temperature sensor 20. Thus, the mass to be heated is kept small, resulting in low energy consumption through minimum heat dissipation, and a uniform temperature adjustability. The welding bar 1 7 is held on a support 18, and between the support 18 and the welding bar 17 there is arranged an insulating plate 21 which minimises heat loss.At the two sides of the welding elements there are situated insulating panels 22 which cover both the welding bar 1 7 and also the support 1 8 and which prevent undesirable heat transfer to the side surfaces of the containers. The welding elements are held in opposition to the pressure of elastic elements such as compression springs 23 on pins 31. This ensures that the welding bars are applied with a constant pressure towards the counter-pressure plate or the counter-pressure rail. The compression springs 23 may also be replaced for example by rubber or piston-cylinder units.

As may be seen from Figure 1, the sealed containers are fed to a transverse cutting device 14 and also a longitudinal cutting device 15, whereby the individual containers are detached from the sheet. The containers are then passed by means of a discharge belt 1 6 to further processing such as putting into large receptacles for example.

As will be clear from the foregoing description, the present construction dispenses with the hitherto necessary provision of respective welding frames adapted to the particular pack sizes dealt with, with the drive associated with such several frames, but in addition also allows a considerably improved and uniform quality of weld seam to be achieved.

Claims

1. A method of packing goods between two sheets, wherein a trough or well is formed in one sheet, the goods are introduced into the trough or well, and the edge of the trough or well is heatsealed to a second sheet, and wherein individual welding elements are brought from below to between and adjacent the troughs or wells distributed over the sheet width so as to form a first heat-sealed seam(s) between the lower sheet and the upper sheet which is at least the length or width of the pack, a second heat-sealed seam(s) being thereafter formed between the lower sheet and the upper sheet which is at least the width or length respectively of the pack by means of welding elements brought in from below thereby to seal the packs.

2. A method as claimed in Claim 1, wherein the two sheets travel through a packing machine, and wherein the front seam(s) is (are) formed in the direction of travel and the second seam(s) is (are) formed transverse to the direction of travel.

3. A method of packing goods substantially as hereinbefore described with reference to Figures 1, 2, 4 and 5 or Figures 1, 3, 4 and 5 of the accompanying drawings.

4. Apparatus for packing goods between two sheets, wherein the apparatus comprises means for feeding a first sheet of material, a deepdrawing station for forming troughs or wells for the goods in the sheet material, an insertion station for putting the goods into the troughs or wells, and a heat-sealing station at which the edge of the trough or well preformed from the first sheet is heat-sealable to a second and upper sheet by pressure and heat, and wherein vertically displaceable welding elements for forming longitudinal and transverse heat-sealed seams are arranged at the heat-sealing station for engaging the sheets from below to effect heat-sealing, longitudinal welding elements being arranged in interchangeable fashion parallel to the side edge of the sheets in accordance with the number of longitudinal seams required over the sheet width, the length of the longitudinal welding elements being equal to or greater than the length (in the direction of travel of the sheets) of the individual packs, and transverse welding elements being arranged substantially at right angles to the side edges of the sheets, and being displaceable in the longitudinal direction of travel of the sheets.

5. Apparatus as claimed in Claim 4, wherein the welding elements are constructed as plug-in elements, such that by plugging the elements in in selected positions it is possible to achieve both a positive engagement and also an electrical connection for a heating element arranged within the welding element.

6. Apparatus as claimed in Claim 4 or 5, wherein the length of the transverse welding elements is equal to that of the longitudinal welding elements.

7. Apparatus as claimed in any one of Claims 4 to 6 wherein the width of a welding element corresponds to double the width of a heat-sealed seam.

8. Apparatus as claimed in any one of Claims 4 to 7, wherein each welding element comprises a welding bar held on a support, the welding bar being separated from its support by means of an insulating plate.

9. Apparatus as claimed in Claim 8, wherein an elastic element is arranged below the support of the welding element for applying the welding pressure.

10. Apparatus as claimed in Claim 9, wherein the elastic element consists of a compression spring.

11. Apparatus as claimed in Claim 9, wherein the elastic element consists of rubber.

12. Apparatus as claimed in Claim 9, wherein the elastic element consists of a piston and cylinder unit.

1 3. Apparatus as claimed in any one of Claims 4 to 12, wherein the height of the welding bar is such that is can accommodate substantially only a heating element and a temperature sensor.

14. Apparatus as claimed in any one of Claims 4 to 13, wherein the two sides of a welding element are covered by insulating panels.

1 5. Apparatus as claimed in any one of Claims 4 to 14, wherein a counter-pressure plate is arranged above the longitudinal welding elements.

1 6. Apparatus as claimed in Claim 15, wherein profiled rubber strips are arranged in the counterpressure plate above the positions of the welding elements.

1 7. Apparatus as claimed in Claim 15, wherein the counter-pressure plate comprises a rubber covering over a continuous area at its underside.

18. Apparatus for packing goods between two sheets substantially as hereinberore described with reference to Figures 1, 2, 4 and 5 or Figures 1, 3, 4 and 5 of the accompanying drawings.