Can For Liquids And Process For Closing Same

Abstract

The can of the invention is intended for containing liquids, such as oils, is made of a plastic material, and is substantially circular in cross-section. The top end wall is provided with a central opening having a reinforced rim and is adapted to be closed with a heat sealing foil. An elevated border at the outer circumference of the top end wall concentrically surrounds the rim and is connected with said rim by a wall portion having the shape of a flat cone.

Description

The present invention refers to a can for liquids, particularly for lubricant oils, consisting of plastics material, preferably of thermoplastics such as polyethylene or polypropylene. The invention essentially refers to a can with a volume of maximally two liters, a size which is usual for cans for lubricant oils.

The invention essentially consists in the fact that the can has a cylindrical jacket of approximately circular cross-section and is provided at its top front face with a central opening provided with a reinforced rim and having a diameter smaller than the diameter of the can, preferably a diameter approximately corresponding to one-third of the can diameter, and being adapted to be closed by a film applied to the opening by heat sealing, in the fact that the top front face of the can has an elevated border surrounding the reinforced rim of the opening and being connected to said reinforced rim by a wall portion having the shape of a flat cone, and in the fact that the wall-thickness of the jacket amounts to 0.1 -0.5 mm, preferably to about 0.35 mm. A can according to the present invention is preferably manufactured by expanding a hose by internal pressure whereby the low wall thickness of the can is achieved. Up to now it was considered essential that an oil can has to be stiff and mechanically strong, however, a can according to the present invention may, in view of its typical shape, have a low wall thickness. By giving the jacket of the inventive can an approximately circular cross-section, the jacket is supported by the contents of the can. When subjecting a filled can to a load acting on the front faces of the can, such load, which, when acting on an empty can, would result in a deformation of the can jacket, is equally distributed to the content of a can filled with some liquid and thus will act in a sense to maintain the shape of the jacket. In this case, it is sufficient if the can jacket has a cross-section of only approximate circular cross-section. For instance, it is sufficient if the jacket has a polygonal cross-section which approximates a circular cross-section. The elevated border surrounding the reinforced rim of the central opening contributes to further strengthening of the can and the reinforced rim of the central opening contributes to further strengthening the top front face of the can. The reinforced rim of the central opening can be positioned in approximately the same plane as the elevated border of the can. By giving the central opening and, in consequence, the reinforced rim of the central opening an essentially smaller diameter than the diameter of the can, preferably a diameter corresponding to one-third of the can diameter, a strengthening effect for the top front face of the can is provided by the reinforced rim, and furtheron weakening of the can, which would occur if the opening were given a greater diameter, is avoided.

Oil cans of known construction, which are provided with essentially plane front faces, are opened by perforating one front face with a pointed object, for instance a screw driver, at two locations so that the oil can run out from one perforation and air can enter the can through the other perforation. Since, as already mentioned, the liquid can contents provide for a strengthening effect on the can jacket when subjecting the front face of the can to a load, there would result the danger of ejecting oil or the like contained in the can when perforating and thus subjecting the can to load. The foil closing the central opening and being applied thereto by heat sealing equipment, enables the can to be opened without subjecting the front face of the can to unpermissible load.

According to a preferred embodiment of the invention, that annular portion of the front face of the can, which is adjacent to the strengthened rim of the opening, has a greater wall thickness than the can jacket and rises from the border of the can in direction to the reinforced rim in form of a flat cone.

When closing the can by a heat sealing foil, the die of the heat sealing equipment is heating the reinforced rim of the opening and, at least partially, also the wall portion adjacent the reinforced rim, said wall portion having the shape of a flat cone. When heat sealing the can, the pressure exerted by the die is absorbed by the can contents, however, the top front face of the can is thereby yielding such that the annular portion and/or, respectively, the conically shaped portion of the top front face is pressed downwardly and assumes when having the shape of a convex cone, either an approximately horizontal position or even the form of a flat convex cone. When applying the heated die of the heat sealing equipment to the top front face of the can, at least the reinforced rim, in some cases also the annular portion of the top front face, is heated to plastic condition. In view of the wall portion having the shape of a flat cone and having a greater wall thickness than the can jacket, said wall portion will, after termination of the heat sealing process, maintain its deformed shape because the front face "freezes" in its position assumed after having been pressed downwards by said die. The can contents is therewith subjected to pressure such that the can jacket is under tension even if, with time elapsing, a small amount of the can contents emerges from the can by diffusion. With this, it is avoided that the can becomes unattractive with time elapsing. For enhancing this effect it has proved convenient to give the annular wall portion or, respectively, the conical wall portion adjacent the reinforced rim of the opening, twice, preferably three times the wall thickness of the can jacket. According to the invention, preferably the wall thickness of the annular portion of the top front face is greater adjacent the reinforced rim than at its outer peripheral portions and is, for instance, decreasing in direction to the periphery like a wedge. By accumulating a bigger mass of material in the area of transition from the reinforced rim to the annular portion, this annular portion is more reliably fixed in its inwardly pressed position.

A preferred method for closing a can of the kind described, with a heat sealing foil, essentially consists, according to the invention, in the fact that the reinforced rim surrounding the central opening and to be closed by a heat sealing foil, and if desired the annular and, respectively, conical portion of the front face of the can, is heated by the heat sealing die, to a temperature within the softening range of the material and is inwardly pressed by said heat sealing die to a position in which it is "chilled" such that the can contents is subjected to pressure.

The invention thus provides a can and, respectively, an oil can which, in filled condition, without further resists the stresses occurring on transport. It has even been experienced that by giving the can jacket a small wall thickness the load resistance of a filled can is increased in view of the fact that the can jacket, which has the shape of a thin and flexible foil, is not subjected to the danger of breakage on deformation, which danger would be present with cans having a thick-walled can jacket.

The invention is further illustrated with respect to the drawing which shows several embodiments.

In FIGS. 1,2 and 3 an oil can is shown schematically.

FIG. 1 is a cross section along line I --I of FIG. 2.

FIG. 2 is a top plan-view of FIG. 1.

FIG. 3 is a section along line III--III of FIG. 2.

FIGS. 4 to 8 show a modified embodiment of an oil can according to the invention.

FIG. 4 illustrates the can in an axial section along line IV -- IV of FIG. 5 prior to filling.

FIG. 5 is a top plan-view of the can shown in FIG. 4.

FIG. 6 is a bottom view of the can shown in FIG. 4.

FIG. 7 shows, in a section similar to that of FIG. 4, the filled can closed with a heat sealing foil.

FIG. 8 shows a detail of a can as seen in direction of arrow VIII of FIG. 5.

The can shown in FIGS. 1,2 and 3 is cylindrical in shape and is provided at its top front face 2 with an opening 4 reinforced by a rim 3 and to be closed,after filling of the can,with a heat sealing foil. The opening 4 is centrally arranged at the top front face 2. At the circumference of the top front face 2 an elevated border 5 is provided which is interrupted by depressions 6 lying between edges 8 diverging in direction to axis 7 of the can. These depressions 6 act as beaks by which the oil emerging from the opening 4 is collected to a suitable jet. These depressions 6 simultaneously give a stiffening effect for the elevated border 5.

The can is manufactured by blowing the desired material into a mold bipartited along axis 7 of the can. The elevated border 5 forms a so-called recessed portion which engages the concave cone surface 9 and would be caught by the mold halves when opening the mold. To avoid this, a convex, annular cone surface 11 is provided at bottom 10 of the mold, which in a top plan-view, essentially coincides with the concave cone surface 9 at the top front face of the can and encloses with the axis of the can an angle alpha which is approximately equal to or smaller than the angle beta enclosed by the concave cone surface 9 and the axis 7 of the can. This arrangement provides the possibility of shifting the molded can 1 in direction of arrow 20 when opening the mold, so that the molded can is released from the mold. The bottom 10 of the can is inwardly vaulted so that the cans may be stacked. In a stack of cans the cone portions 9 and 11 engage one another, thus securing a reliable stack. The taper 11 of the bottom has the shape of a convex cone and may be provided with a number of noses (not shown) corresponding to the number of depressions 6 forming beaks and having a distance from one another,corresponding to the distance of depressions 6. In this case, the noses provided at the bottom of a can are engaging the depressions 6 of the next lower can, which is of advantage when stacking labelled cans which need alignment of the labels in the stack.

In the embodiment shown in FIGS. 4 to 6, 1 represents the can jacket, 12 the elevated border provided at the top front face of the can and being transient to the can jacket, 3 the reinforced rim of the opening to be closed by the heat sealing foil, and 2 the annular portion of the top front face which, in this case, directly connects the reinforced rim 3 to the elevated border 12. The bottom 15 is, again, provided with an edge 13 formed by a convex cone surface 11 and a concave cone surface 14. The depression 19 only serves for aligning the can in the printing apparatus.

The wall thickness of the can jacket 1 again amounts to approximately 0.1 -0.5 mm and conveniently amounts approximately to 0.35 mm. Such a wall thickness is too small to resist the pressure exerted when pressing the heat sealing foil onto the reinforced rim and so small that the can would become depressed and assume an unpleasant aspect on partial diffusion of the can contents.

The reinforced rim is given a completely plane surface at its upper side.When applying the heat sealing foil, an air tight seal is thereby achieved at the very first moment. When pressing down the heat sealing die the whole can contents is used for load transmission. The can contents, however, is yielding to some extent, particularly when some air is enclosed. The top front face 3,2 of the can is therefore pressed into position 3',2' shown in FIG. 7. On heating portions 3,2 by means of the heat sealing die, these portions 3,2 are plastically deformed and, afterwards, chilled in position 3',2' so that these portions are forced to maintain this position. The wall thickness of the annular portion 2 is at least twice the wall thickness of the can jacket 1, conveniently at least three times the wall thickness of the can jacket . This favors position 3',2' as fixed position. In the case described, the arrangement is such that the wall thickness of the annular portion 2 is a maximum in the area of the reinforced rim 3 and is steadily decreasing in direction of the outer edge 12. This provides an accumulation of material in the area of the reinforced rim 3, which further contributes to fixing the portions 3,2 in position 3',2' shown in FIG. 7. In this embodiment, the elevated border 12 has a semi-circular cross-section and thus is in the position to provide the necessary abutment for deformation of the annular portion 2 which is not or nearly not heated in the area of the elevated border 12.

As is shown in FIG. 8 in an enlarged scale , two teats are provided at two diametrally opposed positions. These teats have a greater height that the wall thickness of the can at the respective position, so that when cutting off these teats a cavity is cut open and a pouring opening as well as an air-admitting opening is provided. To facilitate application of a knife for cutting off the teats 17, a torus 18 is provided which surrounds the corresponding teat.

When filling the can or the like by introducing a liquid jet through the central opening, the liquid is surging upwardly along the cylindrical can jacket 1. The cone surface 9 (FIGS. 1,2 and 3) delimiting the elevated border 5, and, respectively, the vaulted shape of the elevated border 12 (FIGS. 4 to 6) deflect the surge downwards, so that the filling velocity can be substantially increased without running the danger than liquid is splashing out of the can. This is an essential advantage when filling the cans.

Claims

1. A can for a liquid medium, particularly lubricating oil, comprising a. a substantially cylindrical body portion of a thermoplastic material selected from the group consisting of polyethylene and polypropylene and having a wall thickness of 0.0039 to 0.0197 inches, b. a bottom member of the same material as and integral with said body portion at one end thereof, c. a top member of the same material as and integral with said body portion at the opposite end thereof from said bottom member and provided with a central opening of a diameter substantially less than the diameter of said body portion, d. a reinforcement rim forming part of said top member along the free edge at said central opening and susceptible to being heat sealed to a foil covering said opening, and e. an annular portion of said top member surrounding said central opening comprising an inner annular section extending outwardly and downwardly from said reinforcement rim and merging with an outer annular section which is inclined outwardly and upwardly toward the top of said

2. The can according to claim 1, in which the wall thickness of said

3. A can for a liquid medium, particularly lubricating oil, comprising a. a substantially cylindrical body portion of a thermoplastic material selected from the group consisting of polyethylene and polypropylene and having a wall thickness of 0.0039 to 0.0197 inches, b. a bottom member of the same material as and integral with said body portion at one end thereof, c. a top member of the same material as and integral with said body portion at the opposite end thereof from said bottom member and provided with a central opening of a diameter substantially less than the diameter of said body portion, d. a reinforcement rim forming part of said top member along the free edge at said central opening and susceptible to being heat sealed to a foil covering said opening, and e. an annular portion of said top member surrounding said central opening comprising an inner annular section extending outwardly and downwardly from said reinforcement rim and merging with an outer annular section which is inclined outwardly and upwardly toward the top of said cylindrical body portion, the wall thickness of said inner annular section of the top member being greater than the wall thickness of said

4. The can according to claim 3, in which the wall thickness of said inner annular section decreases gradually outwardly from said reinforcement rim.

5. The can according to claim 3, in which the juncture between said outer annular section of the top member and the top of said cylindrical body portion is in the shape of an upwardly convex annular bead of

6. The can according to claim 3, in which the wall thickness of said

7. The can according to claim 3, in which said inner annular section includes a middle concentric region in which the wall thickness is at

8. The can according to claim 7, in which the thickness of said middle concentric region is about three times the wall thickness of said cylindrical body portion.