US3533135A

US3533135A - Apparatus for manufacturing containers

Info

Publication number: US3533135A
Application number: US588834A
Authority: US
Inventors: Od Wikar Christensson
Original assignee: Individual
Current assignee: Individual
Priority date: 1965-11-01
Filing date: 1966-10-24
Publication date: 1970-10-13
Anticipated expiration: 1987-10-13
Also published as: GB1108718A; NL6615250A; NO121422B; SE308198B; DE1604479B1

Description

Oct. 13, 1970 OD w. CHRISTENSSON 3,533,135

APPARATUS FOR MANUFACTURING CONTAINERS Filed 001.- 24, 1.866

Fig. I

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w INV EN OD W. CHRISTENSSON BY OZZQ'JQQQQQJ Jay/W ATTORNEYS United States Patent- 3,533,135 APPARATUS FOR MANUFACTURING CONTAINERS d Wikar Christensson, Ekbacksvagen 32-34, Bromma, Sweden Filed Oct. 24, 1966, Ser. No. 588,834 Claims priority, application Sweden, Nov. 1, 1965,

Int. Cl.B29c 17/00 U.S. Cl. 18-19 8 Claims ABSTRACT OF THE DISCLOSURE A method and apparatus for forming liners onto the interior surface of open top stiff outer containers, wherein the liner is also attached to the open edge of the container and thereover to the outside of the container. The containers are placed in a mold with the upper side parts of the container projecting out of the mold. Support plates extend upwardly out of the mold to support the said upper side parts to prevent buckling thereof, during the drawing of the liner onto the container.

This invention relates to containers, and in particular, it relates to an apparatus for firmly attaching a flexible type lining material such as plastic or the like to the interior surface of a container of a relatively stiff material such as cardboard or the like. Although the invention is not limited to plastic linings and cardboard containers, for purposes of illustration and convenience the relatively flexible lining material will be referred to as plastic material and the relatively stiff container material will be referred to as a cardboard material.

It is known to place a flexible lining into an open top container by first placing the container into an open top die with the open end of the container facing upwardly, and then placing a sheet of lining material over the die cavity, and subsequently attaching the lining to the interior surface of the container by a deep drawing process using either pressure or a vacuum. However, serious problems have limited the successful operation of this known procedure.

It is practically impossible to provide an absolutely perfect bond between the lining and the container. Therefore, to assure that the lining will not become loose, it is necessary to form the lining not only on the interior surface of the container, but also on the free edge of the container around the opening therein, and possibly also slightly beyond the free edge onto the exterior surface of the container. This result could be obtained, perhaps, by allowing the free edge of the container to extend upwardly out of the die cavity. However, this would not be practical since the forces exerted on the container during the drawing process would cause that portion of the container projecting out of the die to buckle and thus yield outwardly and perhaps even tear. Of course, this problem might be solved by using a very heavy material to form the container. However, this would be an avoidance rather than a solution to the problem since the heavier container material would be uneconomical, and in many instances undesirable as a packaging material.

Thus, it is a purpose of the present invention to provide an apparatus for firmly and durably securing a flexible lining material onto a container of a material which is relatively stiff, for example, more stiff than the flexible lining material, but not necessarily of such stiffness and rigidity that it could withstand buckling during the drawing operation without the features of the present invention.

The container to be lined may be formed by punching a blank of cardboard or a similarly stiff material and ice tangular open top container from such a blank it is often necessary to place certain flaps extending from one side of the container into overlapping relationship with adjacent sides of the container. Consequently, some of the container sides will comprise at least two layers of material while other sides will comprise only a single layer of material. Of course it is also possible to form an open top rectangular container wherein. all the sides comprise only a single layer of material, for example, where the sides are joined together at the corners. The present invent-ion is applicable to all shapes of open top containers regardless of the number of sides formed only by a single layer of material.

The container is then placed into an open topped die with the open top of the container facing upwardly. In practice, a large number of dies may be formed side by side. A large sheet of flexible lining material is then placed over all of the dies and then drawn onto the interior surface of the containers located in the dies by known deep drawing procedures.

It is important that the lining material be strongly and durably bonded to the interior surface of the container material thereby forming an intimately joined unit. As noted above, it is quite difficult to obtain a strong bond between the plane sides of the interior of the container and the lining. For this reason it is necessary to form a bond not only at the interior of the container but also at its upper free edge and also for a limited extent along the outside of the container. This result is obtained by allowing the upper edge of the container to project out of the die during the deep drawing operation.

However, as noted above, it is not generally practical to allow a portion of the container to project out of the die since that portion will then be subjected to buckling, and perhaps tearing, during the deep drawing operation. Tests have shown that in producing generally rectangular containers, that those sides of the container which extend above the upper edge of the die, and are composed of only a single layer of cardboard material, will buckle, yield outwardly and even tear during the deep drawing opera tion. Such a container must, of course, be discarded. Further, in some instances, a damaged container will cause damage to other containers locate-d in adjacent dies.

'One cause of container buckling is very hard to overcome. Experience has shown that thickness'of the lining material can vary up to -15% in one and the same sheet. When such a sheet is employed in a deep drawing operation to form the lining, the traction power at the edges of the container will be stronger or weaker depending on the thickness of the lining material at the respective edge. Thus, it is possible for a strong portion of the lining material to be located at a weak position on the container and thereby cause buckling and tearing.

One way to overcome this buckling problem might be to place the container completely within the die. However, for reasons explained above, it would not then be possible to obtain a strong and durable bond between the lining material and the interior surface of the material.

Briefly, the present invention provides an apparatus for allowing the container to extend beyond the upper edge of the die while at the same time preventing buckling of the container material.

According to the operation of the preferred apparatus of the present invention the container is placed into a die which is shaped to substantially mate with the outer surface of the container. The depth of the die is less than that of the container. Consequently, the upper edge of the container will project out beyond the upper edge of the die. To eliminate buckling of the upper edge of the container, while at the same time allowing the lining material to be formed completely along the upper edge, a rigid support means is placed against the exterior surface of those container sides which are not capable of withstanding buckling forces during the deep drawing operation. In a container of the type referred to, the sides having only a single layer of material will require a support means while the sides formed by a double layer of material will not require a support means. To assure that the lining material becomes attached to the upper edge of the container, the support means will extend upwardly along the exterior surface of the container to a point short of the free edge. For example, the support means may stop at 1 mm. short of the free edge. Also, the support means will extend for a width shorter than the width of the side being supported.

With the support means thus in place the sheet of lining material is placed over the containers and applied thereto by the usual deep drawing procedures.

According to the apparatus of the present invention, shallow recesses are formed in the sides of the die against which the sides of the container requiring support will be placed. Then support plates are positioned in these recesses in such a manner that they extend upwardly beyond the upper edge of the die to a height slightly below the height of the container to be placed in the die. In this manner the plates will provide the necessary support while at the same time not interfering with the proper placement of the lining material onto the free edge of the container. In one common type of rectangular container formed from a punched blank, two opposite sides of the container are formed with a double layer of material while the other two sides are formed from only a single layer of material and thus require support at their upper edges during the deep drawing operation. In a die adapted for use with such a container the two support plates will be located on opposite sides of the die. In this instance it is desireable to connect the two plates at a level below the die thereby forming the two support plates from a single piece of material having a U-shaped cross-section, the two support plates forming the legs of the U. A moveable support plate may be provided at the bottom of the die cavity both for supporting the container and for thrusting the container outwardly after completion of the operation.

Thus, it is an object of the present invention to provide an improved apparatus for firmly and durably fixing a flexible lining material onto a relatively stiff container which method and apparatus overcome disadvantages present in previous methods and apparatus.

Another object of the present invention is to provide an apparatus for providing a strong and durable bond between a flexible lining material and a relatively stiff container material which method and apparatus are more economical than previously known methods and apparatus. 1

It is still another object of this invention to provide an apparatus for allowing a lining material to be placed along the free edge of an open topped container while at the same time providing a means to eliminate buckling of the vulnerable portions of the container.

Other objects and the attendant advantages of the present invention will become apparent from the detailed description to follow together with the accompanying drawings wherein:

FIG. 1 illustrates a typical container of the type to be lined with the method and apparatus of the present invention.

FIG. 2 shows a deep drawing die according to the present invention.

FIG. 3 is a section view of the die shown in FIG. 2 taken in the plane illustrated by the line 33 of FIG. 2.

A typical container to be lined by employing the method and apparatus of the present invention may be an open top rectangular container 11, as shown in FIG. 1, r example, having a bottom and upwardly diverging sides. In forming the container 11 the short sides 12 are so manipulated that they comprise two layers of cardboard while the long sides 13 include only a single layer of cardboard. Consequently, the short sides 12 offer considerably greater resistance to buckling than the long sides 13.

A die 15, as shown in FIG. 2, has a generally rectangular frame, made of a suitable material such as light metal, and having a cavity, the shape of which is substantially mateable with the outer surface of the container 11. The cavity in die 15 also includes air channel 16 running down the short sides of the cavity for facilitating the passage of air between the container 11 and the die 15 during the deep drawing operation. During deep drawing, air in the die is of course drawn out through the space 20 between the side walls and the bottom plate 19. A shallow recess 17 is provided in each of the long sides of the cavity against which the sides 13 of the container are to be placed. A thin side plate 18 is mounted in each recess 17, the plate being of a thickness substantially equal to the depth of the recess 17. The side plates 18 may be of any suitable material, such as for example, steel. The recesses 17 extend laterally for a distance substantially less than the side of the cavity in which the recess is formed; and the side plates 18 are of a width slightly less than that of the recess 17.

During the deep drawing operation the container 11 is placed into the die 15 to such a depth that approximately 10-20% of its overall height extends upwardly beyond the upper edge of die 15. The Width of side plates 18 is chosen so that they will provide sufiicient support to those parts of the container which extend upwardly beyond the upper edge of die 15 to prevent buckling and outward yielding of that portion during the deep drawing operation.

As explained earlier, the purpose of having a portion of the container 11 extending out of the die is to assure that the lining will be applied not only to the interior surface of the container 11 but also to the upper free edge and slightly beyond the upper free edge onto the exterior surface of the container. Not only will this provide a more firm and durable bond between the lining materal and the container, but it will also provide a smooth upper edge thereby facilitating the placement of a cover onto the container. Another advantage of mounting the container in a die in this fashion is to obtain a radially outwardly extending flange of lining material at the top of the container onto which waste material can run during the filling of the container without staining the usually decorative exterior surface of the container 11.

The side plates 18 may be attached to the die 15 in any suitable manner. In the preferred operation of the invention the side plates 18 are mounted Within the die 15 so that they will extend upwardly along the outer surface of the container 11 above the die 15 to a point close to but below the upper free edge of the container 11, for example, 1 mm. below that edge. As shown in FIG. 2 and 3 the side plates are mounted at opposite sides of the cavity. Consequently, the side plates may be formed as a one-piece member having a U-shaped crosssection wherein the two side plates 18 form the legs of the U.

While the present embodiment illustrates fairly Wide single side plates, 18, it is also possible to provide a plurality of more narrow side plates. Of course, if the short sides 12 of the container are also weak sides formed of a single layer of material, then recesses 17 and side plates 18 may also be provided in the short sides of the cavity.

For most etficient operation, it is preferable that the side plates 18 be as thin as possible and at the same time not unnecessarily wide since there will be a reduction in adherence of the lining along the upper edge of the container in the area of the side plates. Of course,

this reduction in adherence should be minimized to prevent loosening of the liner from the container.

A vertically moveable support plate 19 is provided at the bottom of the die both for supporting the bottom of the container 11 during the deep drawing of the lining and also for thrusting the finished container from the die.

FIG. 3 illustrates the overall relationship between the elements of the die, the container 11 and the lining 14. It can be seen that the side plates 18 extend upwardly to a point slightly below the upper edge of the container 11. This allows the lining material 14 to cover at least the free edge of the container adjacent the side plates 18. Of course, where no side plates are present the liner material 14 may continue over the free edge and adhere to the exterior surface of the container. As shown in FIG. 3 the container 11 rests upon the support plate 19. Also, FIG. 3 illustrates the generally U-shaped cross-section of the side plates as arranged in one embodiment of the invention.

The operation of the invention is as follows. In actual production a great number of dies are usually joined together side by side and end to end. An empty container 11, which may be held together at this point by suitable means such as glue or the like, is placed into each die 15.

A large sheet of suitable lining material is then positioned over the plurality of dies and heated to a forming temperature, and subsequently deep drawn into the containers in a manner known per se, such as, for example, by vacuum and/or pressure. During this deep drawing operation the lining material will form on the interior of the container and also along the free edge. The force exerted on the package will not buckle the package or cause it to yield outwardly since those sides of the container requiring additional support are mounted adjacent a side plate 18. The package thus formed is then pushed out of the die by the vertically moveable support plate 19 and moved into another compartment for filling and sealing.

Thus, with the present invention it is possible to avoid buckling and yielding of the upper edge of the container above the die 15 during the forming of the lining, while at the same time it is possible to produce the container of a cheaper cardboard material. Further, since the risk of buckling and outward yielding has been eliminated, it is possible to increase the speed with which the lining can be applied to the container. Thus, the present invention obtains a higher production rate and a more durable bond between the lining and the container while employing a less expensive container material.

While the invention has been described in considerable detail above with respect to a preferred method of operation and respect to a preferred embodiment of the apparatus, it should be apparent that the invention is capable of numerous variations and modifications within the spirit and scope of the invention as defined in the appended claims wherein:

I claim:

1. A die apparatus for use in forming a lining in a container comprising: a cavity formed in said die having an open top bounded by a free edge and an interior surface formed by a bottom and a plurality of side walls between said bottom and said free edge, an opening through said cavity interior surface for gas communication with the interior of the cavity other than through the open top said cavity being substantially mateable with the outer surface of a container to be lined, at least one side wall having a recess formed therein, said recess extending horizontally along said side wall for a distance less than the width of said side wall, and a side plate mounted in said recess and extending upwardly out of said die beyond said free edge, said plate being thin and generally parallel to the side wall in which it is mounted.

2. An apparatus as claimed in claim 1 wherein the bottom of the cavity is formed by a vertically moveable support plate for supporting the said container.

3. An apparatus as claimed in claim 1 wherein said cavity has an even number of sides and wherein there is provided at least two side plates, each one being mounted in a recess in opposite side walls of said cavity.

4. An apparatus as claimed in claim 3 in which said two side plates are joined together at their lower ends to form a member having a U-shaped cross-section.

5. An apparatus as claimed in claim 4 in which horizontal lines lying in the planes of each of the said two side plates are substantially parallel to each other.

6. An apparatus as claimed in claim 1 wherein the depth of the said recesses is substantially equal to the thickness of the said side plate.

7. An apparatus as claimed in claim 1 wherein at least one of the cavity walls without a recess formed therein for a side plate has formed therein a vertically extending channel to facilitate flow of fluid therethrough.

8. An apparatus as claimed in claim 1 in which the side plate is made from a thin steel material.

References Cited UNITED STATES PATENTS 231,508 8/1880 Thompson 249-112 XR 696,686 4/1902 Lyons 249-112 XR 776,979 12/1904 Williams 18-38 974,350 11/1910 Bratton 2491l2 XR 1,019,506 3/1912 McCool 18-38 1,206,150 11/1916 Slick. 1,257,230 2/1918 Higgenbotham 249112 XR 1,787,503 1/1931 Zube 1844 XR 1,896,372 2/1933 Rieser 18-19 XR 1,919,070 7/1933 McKay et al. 18-19 1,951,071 3/1934 Stripe 249-112 2,479,350 8/ 1949 Haggart 18-42 3,121,258 2/1964 Lagler.

WILLIAM J. STEPHENSON, Primary Examiner U.S. Cl. X.R. l8-35, 44