GB1591323A - Freight containers for bulk storage transporters - Google Patents

Description

(54) IMPROVEMENTS IN FREIGHT CONTAINERS FOR BULK STORAGE TRANSPORTERS (71) We, P & B PLASTICS LIMITED of Shaw Heath Mill, Stockport, County of Chester, a British Company, 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 particu larly described in and by the following state ment:- This invention relates to improvements in disposable polyethylene liners for freight containers used for bulk storage transport.

Goods are transported by road, rail or sea in freight containers which are lifted bodily from one mode of transport to another and where granular or powdered substances are to be transported they are loaded into the con tainers through a hatch or hatches in the roof or upper door of the containers and dis charged through a hatch or hatches situated low down in the container end-wall or doors, by force of gravity using special equipment which gradually raises the end of the container opposite to the point of discharge.

Certain cargoes carried in bulk container boxes nesessitate the use of expendable totally-enclosed polyethylene liners in order to protect the cargo from contamination or ingress of water. This applies especially in the case of granular cargoes such as sugar, trevira (Registered Trade Mark) or terylene (Registered Trade Mark) chips and other chemical materials. The liners are fitted with polyethylene filler and discharging funnels positioned relative to the appropriate hatchets in the container box.

Each liner is manufactured in tubular form, the circumference being slightly larger than the periphery of the sidewalls, roof and floor of the container box itself, i.e. 9,550mm circumference for British containers and 10,000mm for continenetal containers. This tubular polyethylene is supplied on the reel and, for convenience in handling it is either in the profile of a flattened out centre-folded tube or a gussetted tube.

It has been proposed to form the liners trom polyethylene manufactured in flat tubes which are then cut to length, sealed at both ends and inserted into the container the upper edges of the sides of the liner being attached by string passing through holes in tags or lashing eyes bonded to the outside of the liner and secured to metal rings affixed to the sides of the container adjacent to the roof.

The liner is then inflated by means of com pressed air to engage the sidewalls, floor, roof and end-walls of the container.

In forming the ends of the liner the poly ethylene has been folded and welded or heat sealed into a rectangular box-shape leaving surplus material either hanging loosely inside the liner or welded into it, thus doubling the weight of the end walls of the liner and dis torting its shape, resulting in incomplete inflation and causing subsequent sagging of the liner and consequent trapping of a sub stantial weight of cargo in the folds of poly ethylene. The trapped cargo can only be moved manually and is thereby contaminated and rendered relatively or completely value less.

Furthermore, filler and discharge funnels fabricated from layflat polyethylene tubing are welded or heat-sealed on a flat surface into the liner body in a shallow diamond pattern around corresponding slots or holes of similar diamond pattern cut into the liner body, -thus weakening the liner through stress tears occurring at the junction of the funnels with the liner; also the inadequate shape and size of the aforementioned holes in the liner restricts the flow of cargo into or out of the liner.

The object of the invention is to remedy the aforesaid faults and the production of an improved liner with rectangular ends welded along fold ; the liner to shape the liner'to the ends of the container, súrplus material being cut away and removed during the welding or heat sealing cycle thus enabling the liner to be inflated to the configuration of the container.

According to the invention a method for the formation of a disposable polyethylene "liners for a freight container comprises laying a gussetted flat tube on a table marked out as a template marking the positions on the tube of holes corresponding with respective filler funnels, forming a hole or slit for each funnel, inserting filler funnels each on a respective former into the holes in the tube, welding the base of the funnels or an intermediate member bearing the funnels, onto the tube, removing the formers from the funnels, applying patches and eyelets at predetermined positions on the upper edges of the tube, closing each end of the tube by welding or heat sealing along lines to produce a rectangular container and removing surplus material from the ends of the tube.

The invention will be described with reference to the accompanying drawings Fig. 1 is a perspective view; Fig. 2 is a detail transverse section of a gussetted extruded polyethylene tube on line 2-2 Fig. 1; Fig. 3 is a perspective view of part of a funnel before opening out for welding into the liner; Fig. 4 is a perspective view of the liner after inflation; Fig. 5 is a detail perspective view on the line 5-5 Fig. 4.

The liner A is formed from tubular polyethylene film on tables marked out with overall dimensions filler and discharge funnel positions and reinforced eyelet positions etc.. The main variations are the number, dimensions and positions of the funnels.

There are various types of container boxes but they are all virtually the same height and width and these dimensions determine the circumference of the polyethylene liner tube which is made slightly oversize to allow for corrugations in the container box.

The polyethylene tube may be supplied in gussetted form as shown in Fig. 2 or as a centre folded lay-flat tube which has then to be opened out and refolded into gussetted formation as a first operation.

The liner is laid on a table marked out as a template with the centre line a of the liner to mark the position of the filler funnels B and holes b are cut in the line. The funnles B are then welded in position.

The filling funnels B and discharge funnels C are fabricated from layflat polyethylene tube Fig. 3 and are of a perimeter equivalent to that of the holes b cut out of the liner A.

The holes in the liner for square cross-section fillers have rounded corners to eliminate stress concentration and consequent tearing which occurs with angular corners. The method of securing the cylindrical funnels B to the liner A is by use of a former of circular crosssection for circular section funnels and a former of rounded-corner square crosssection for square section funnels, the perimeter of each shape of former being slightly less than that of the layflat tubing and the respective holes in the liner. The vertical sides of the former are covered with a standard barrier material in order to prevent the polyethylene from adhering to the former as a result of the heat generated in the welding or heat-sealing process. The tubular polyethylene funnel B is drawn over the former as a sleeve and the former plus funnel is inserted inside the liner and offered up to the appropriate hole b in the liner. Thus material surrounding the hole is then drawn down over both the funnel and the former, creating a lip bl which is then welded or heatsealed to the periphery of the funnel.

Alternatively the funnel instead of being welded or heat sealed directly onto the liner may be welded or heat sealed to holes in a flat sheet of polyethylene which is then welded or heat sealed to the liner with the funnel in register with a circular hole of the same diameter previously cut in the liner body, which obviates any error which may occur in welding or heat sealing the funnel directly to the liner which is an operation requiring considerable skill if incorrectly carried out only calls for the scrapping of the sheet instead of having to scrap the complete liner body.

A further method is to provide an elliptically shaped entry to the liner by positioning each layflat polyethylene funnel on a flat former of elliptical shape before insertion, into the liner. A slit long enough to accommodate the layflat tubing and former is made in the liner, the tubing and former being inserted so as to leave a small portion of the tubing projecting inside the liner body, the funnel being welded or heat sealed to the liner around the elliptical shaped edge bl. The side creases of the layflat polyethylene funnel inside the liner are removed by means of a parabola-shaped cut b2 (Fig. 3) which eliminates stress at the points where the side creases of the layflat tubular polyethylene funnel are joined to the liner. The surplus liner body material inside the funnel is then removed by severing it around the inside perimeter of the weld or heat seal.

The position of the discharge funnels C are marked from the template and are then welded into the liner body similarly to the filler funnels.

The above described alternative methods of bonding the funnel to the liner in each case prevent the creation of weak areas at the junction of the funnel with the liner body by ensuring that any stress applied thereto will be evenly distributed throughout the length of weld or heat seal which bonds the funnel B or funnel C, to the liner body A. They also eliminate restriction of the cargo flow when the liner is being filled or emptied.

A plurality of filling funnels B may be provided with a further funnel B1 for the escape of air from the liner during the filling operation and a funnel for funnels C for dis charging the contents of the liner positioned appropriately in the container.

The position of reinforcing patches a2 for eyelets a3 (Fig. 5) are marked off from the template and the eyelets inserted.

Finally the liner ends are closed in a boxing out process which converts the tube in to a regular rectangular box end by welding a4 from the outside of each corner eyelet a2 to the edge of the nearer gusset a5 Fig. 2 and then sealing the remaining opening a6 between the two gussets a5. During the welding operation a flying knife operates to cut off the surplus material a7 shown in dotted lines in Fig. 1.

The removal of the surplus material a7 reduces the weight of the ends of the liners and the elimination of pockets in which the granular or powdered cargo can become trapped. The removal of the surplus material may also allow for an extra ton of cargo in the liner.

The liner is also provided with a cloth based reinforcing material at intervals around the upper edges of its sides welded or heat-sealed or bonded with adhesive to the liner and containing eyelets formed with a flanged portion to pass through the liner on one side and closed on the opposite side by a disc having sharp pointed projections around its circumference which are pressed through the cloth based reinforcing material and into a recess in the flanged portion of the eyelet.

The eyelets are fited with hooks of a plastic material and the positions of the eyelets are aligned with metal rings on the upper wall of the container to which the liner is attached by means of the plastic hooks. Alternatively, a cord may be supplied extending through the metal rings in the container and secured, the plastic hooks on the liner then being attached to the cord.

The polyethylene film is normally of 175 micron thickness, but can be up to 375 micron thickness in the case of high density load materials such as nickel powder.

WHAT WE CLAIM IS: 1. A method for the formation of a disposable polyethlene liner for a freight container comprising laying a gussetted flat tube on a table marked out as a template, marking the positions on the tube of holes corresponding with respective filler funnels, forming a hole or slit for each funnel, inserting filler funnels each on a respective former into the holes in the tube, welding the base of the funnels or an intermediate member bearing the funnels onto the tube, removing the former from the funnels, applying patches and eyelets at predetermined positions on the upper edges of the tube, closing each end of the tube by welding or heat sealing along lines to produce a rectangular container and removing surplus material from the ends of the tube.

2. A method for the formation of a disposable polyethylene liner as in Claim 1, comprising welding the funnels to a polyethylene sheet constituting said intermediate member and welding the sheet to the liner with the funnels passing through the holes.

3. A method for the formation of a disposable polyethylene liner as in Claims 1 or 2 in which the flat tube is given a preliminary operation to convert a centre folded tube into a gusseted tube.

4. A method for the formation of a disposable polyethylene liner substantially as described with reference to the accompanying drawings.

5. A disposable polyethylene liner substantially as described when produced by the method of Claim 1.

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

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. charging the contents of the liner positioned appropriately in the container. The position of reinforcing patches a2 for eyelets a3 (Fig. 5) are marked off from the template and the eyelets inserted. Finally the liner ends are closed in a boxing out process which converts the tube in to a regular rectangular box end by welding a4 from the outside of each corner eyelet a2 to the edge of the nearer gusset a5 Fig. 2 and then sealing the remaining opening a6 between the two gussets a5. During the welding operation a flying knife operates to cut off the surplus material a7 shown in dotted lines in Fig. 1. The removal of the surplus material a7 reduces the weight of the ends of the liners and the elimination of pockets in which the granular or powdered cargo can become trapped. The removal of the surplus material may also allow for an extra ton of cargo in the liner. The liner is also provided with a cloth based reinforcing material at intervals around the upper edges of its sides welded or heat-sealed or bonded with adhesive to the liner and containing eyelets formed with a flanged portion to pass through the liner on one side and closed on the opposite side by a disc having sharp pointed projections around its circumference which are pressed through the cloth based reinforcing material and into a recess in the flanged portion of the eyelet. The eyelets are fited with hooks of a plastic material and the positions of the eyelets are aligned with metal rings on the upper wall of the container to which the liner is attached by means of the plastic hooks. Alternatively, a cord may be supplied extending through the metal rings in the container and secured, the plastic hooks on the liner then being attached to the cord. The polyethylene film is normally of 175 micron thickness, but can be up to 375 micron thickness in the case of high density load materials such as nickel powder. WHAT WE CLAIM IS:

1. A method for the formation of a disposable polyethlene liner for a freight container comprising laying a gussetted flat tube on a table marked out as a template, marking the positions on the tube of holes corresponding with respective filler funnels, forming a hole or slit for each funnel, inserting filler funnels each on a respective former into the holes in the tube, welding the base of the funnels or an intermediate member bearing the funnels onto the tube, removing the former from the funnels, applying patches and eyelets at predetermined positions on the upper edges of the tube, closing each end of the tube by welding or heat sealing along lines to produce a rectangular container and removing surplus material from the ends of the tube.

2. A method for the formation of a disposable polyethylene liner as in Claim 1, comprising welding the funnels to a polyethylene sheet constituting said intermediate member and welding the sheet to the liner with the funnels passing through the holes.

3. A method for the formation of a disposable polyethylene liner as in Claims 1 or 2 in which the flat tube is given a preliminary operation to convert a centre folded tube into a gusseted tube.

4. A method for the formation of a disposable polyethylene liner substantially as described with reference to the accompanying drawings.

5. A disposable polyethylene liner substantially as described when produced by the method of Claim 1.