Two-piece container and method of assembling the container halves

Abstract

 A container and method and apparatus for adhesive bonding of two telescopic container halves (2,3) wherein each container half has a cylindrical body, the inner container portion (14) being circumferentially loaded to temporarily reduce its diameter and being forced in centered relation to the outer protion (8) into a bead of adhesive (20) laid in the interior of the outer portion to coat the raw edge (18) on the inner portion, the inner portion shearing through the adhesive (20) without wiping it off from the interior of the inner portion and thereafter the hoop stress on the inner portion being relieved so it springs out and squeezes excess bonding material from between the inner and outer portion and thus obtains a thin film adhesive bond with good stress shear characteristics while holding the film in compression therebetween during curing or setting of the adhesive.

Description

[0001] The invention is directed to a method and apparatus. for assembling thin-walled container halves.

[0002] Attempts at assembling thin-walled container halves by conventional methods have failed in that even if one of the halves is necked in prior to attempts at assembly, the flimsy nature of the side walls prevents their retaining a cylindrical shape and thus great difficulty has been experienced in rounding the parts and then axially pushing them together.

[0003] In French Patent No. 1,224,793 a container is formed of thick-walled cylinder halves, one of which is necked out and the second necked in, the second half being telescoped into the first and the halves are then welded together.

[0004] This may be effective for thick-walled containers which retain their shape after reforming, but thin-walled containers, particularly if made from relatively soft metal such as aluminum, are very unstable in retaining their shape and thus are difficult to assemble and in forming the edges, are hard to control. This is especially significant for highspeed production of 400-1000 units per minute.

[0005] In the prior art, the bonding of telescoped container halves usually involves a welding or brazing of the metal parts. Adhesive bonding as heretofore has been tried but has been found wanting.

[0006] Various problems occur in obtaining an adequate sealin using adhesive bonding. Attempts have been made by merely coating the exterior edge portion of the inner container portion or the interior edge portion of the outer container portion. The two halves then are telescoped. However, during the insertion movements the edge of the uncoated portion would scrape off the coating from the coated portion and the residue remaining would not in each instance be sufficient to provide a bond of required integrity.

[0007] The object of this invention is to provide a novel container as well as a method and apparatus for assembling the container halves which overcome the foregoing problems.

[0008] Accordingly, the present invention provides a container.having a pair of sections positioned end to end, each section having a thin-walled flexible metal body with ar open end defined by an end portion, said end portions being telescoped and forming a lap seam, said end portions being radially spaced from each other in said seam and an adhesive material in the space between said end portions bonding the same to each other.

[0009] The present invention also provides a method of bonding a pair of container sections end to end wherein each section has a metal thin-walled cylindrical body with an open end defined by an end portion having a raw edge comprising the steps of applying a bead of adhesive material of predetermined width on the interior side of the edge portion of one of said sections, and inserting the other section into said one section while applying a hoop stress to the end portion of said other section to reduce the diameter thereof to slightly less than the internal diameter of said one section, imbedding said end portion of said other section within said bead of adhesive while maintaining said end portion of the other section in radially spaced relation to said end portion of said one section to provide clearance therefrom and thereby leaving a film of adhesive material of predetermined thickness between the external side of the edge portion of the other section and the internal side of the edge portion of the one section, and then releasing the hoop stress on said end portion of said other section to cause excess bonding material to be squeezed out from therebetween and leaving a thin coating of said material therebetween.

[0010] In addition the present invention provides an apparatus for assembling a pair of thin-walled cup-shaped container sections adapted to be assembled end to end and each section comprising a cylindrical body wall having an open end defined by an end portion of the body wall which normally assumes an out of round shape; comprising a support; means for mounting said sections in axially spaced aligned relation and the end portion of each opposing the other; a die assembly mounted on the support in a position to receive one of the.container sections at one side thereof and the other container section at the opposite side thereof; said die assembly comprising an opening there through; outer guide means at opposite sides thereof for guiding the end portions of respective container sections into said opening; said opening being defined at one side of the die assembly by a cylindrical surface disposed inwardly as said guide means as a continuation thereof and of a diameter to snugly engage the external side of a container section insertable therein to shape and hold the same round; said guide means on the other side of said guide assembly extending through said shoulder and defining an inner edge thereof; said shoulder having a radial extent slightly greater than the thickness of the body wall of the container inserted into said cylindrical surface area, and means for advancing said container sections toward one another and telescoping the end portion of one container end portion into the other.

[0011] In use of the apparatus of the invention, the first and second container halves are advanced toward each other at opposite sides of the die and the second half is forced through the necking surface and is slightly necked in while the first half is disposed in receiving position. Thus, as the second half is being necked in, it also wedges into the first half. These operations are concurrent. Before the halves are fitted one into the other, the second or entry- ing half has a coating of adhesive applied thereto along its entering edge, although it will be understood the adhesive may be applied within the outer (first) container half at its juncture edge portion.

[0012] The outer container is held round (squared) in the die assembly. The entering portion of the inner container is slightly necked in while relatively advancing the two halves toward each other and while holding them under control so that the inner container portion easily enters the open end of the outer portion. The inner portion is under compression and after release from the die, springs outwardly and produces a hoop tension in the outer portion.

[0013] The adhesive preferably is a vinyl plastisol material which solidifies on being heated after the container sections are mated. The container sections are released when telescoped and the inner section expands and compresses the trapped adhesive and thus maintains intimate pressed contact between the parts so that they adequately bond with the adhesive as it cures or sets. Suitable adhesive materials for bonding the two container sections together can be any known materials having adhesive properties including vinyl plastisols, thermosetting epoxy resins and thermoplastic resins such as polyethylene, polypropylene. Other adhesive materials include vinyl plastisol formulations, carboxylated polyolefin resins and especially carboxylated polypropylene resins of the type disclosed in U.S. Patent 3,616,047.

[0014] These and other features and advantages of the invention will become more apparent from the specification and the drawings, wherein:

Fig. 1 is an axial sectional view through the apparatus and container sections showing the parts preparatory to being joined; and

Fig. 2 is the same section showing the parts joined.

Fig. 3 is a side elevational view partly in axial section of apparatus of the invention;

Fig. 4 is a cross-sectional view taken substantially on line 4-4 of Figure 3;

_Fig. 5 is an enlarged cross-sectional view taken substantially on line 5-5 of Figure 1;

Fig. 6 is an.enlarged fragmentary view of a portion of the die member in cross-section showing the can parts in position preparatory to entering the die; and

Fig. 7 is a fragmentary axial vertical section taken substantially on line 7-7 of Figure 5 showing the can parts in assembled position.

[0015] In figures 1 and 2 there are shown two can halves 2 and 3. The upper can section 2 fits into a cylindrical bore 3 in a die assembly 4 and has its lower edge 5 seated upon arr inwardly projecting shoulder 6. The bore 3 is of a diameter slightly larger than the outer diameter of the cylindrical body portion 8 of can section 2 which complementally fits into the bore 3.

[0016] The shoulder 6 extends radially inwardly of the inner surface of the upper can body 8 and defines an apical guide edge 10 with a frusto conical guide surface 12 open through the bottom side 14 of the die member 4.

[0017] The lower can body 14 is inserted into the guide 16 and is forced upwardly against the constricture imposed by the upwardly converging guide surface 12 which slightly compresses the open edge portion 16 of the can body 14.

[0018] The raw edge 18 of the inner or lower can body 14 is forced into the bead of adhesive 20 which may be vinyl plastisol or an eopxy. The adhesive material 20 is laid onto the interior side of the upper container body adjacent to its lower edge and if it is of thermoplastic material it is heated so that the edge portion 16 may be forced into it.

[0019] It will be noted that the guide edge 10 causes the outer side 20 of the inner edge portion 16 to be spaced radially inwardly from the inner side 19 of the upper portion so that the adhesive is not scraped off by the edge 18 as it is inserted into the upper can body but a predetermined band layer 24 of adhesive material remains in the space 25 and also some of the adhesive material flows over the interior side 26 of the inner upper edge portion 16. When the telescoped container portions are released by opening the die assembly, the inner edge portion 16 springs outwardly and compresses the adhesive material against the overlapping portion of the outer container section. The adhesive is thus compressively held between the two can parts and excess material is squeezed out so that an excellent thin adhesive bond is obtained which is stressed in shear when the container is filled with pressurized beverages for which this container is primarily intended and the gases load the ends axially.

[0020] The preferred apparatus of the invention is illustrated in Figures 3-7. With reference to these Figures, the apparatus 31 comprises a support frame 32 which has a plurality of vertically aligned bearings 33 and 34 mounted thereon in which an operating shaft assembly 35 is journaled.

[0021] The shaft assembly is split into two counter- rotary sections 38 and 40.

[0022] Shaft section 38 is connected to one jaw or clamp holder 42 and the shaft section 40 is connected to jaw or clamp holder 44 of a die 45. The jaw sections each carry a half section segment 46 of a die ring 47. Each section 46 has a tongue 48 fitted into a groove 50, in the associated jaw or clamp holder 42 or 44. In addition, there is provided an end stop 52 at each end of segment 46 abutting the end of the same, the stop being attached by screws 54, 54 threaded into the associated end portion of the jaw section 42 or 14. Jaws 42, 44 have arms 55, 56 respectively at one of their ends keyed by keys 57, 58 to the respective shaft sections 38 and 40.

[0023] The shaft sections 38 and 40 are connected to pistons 64, 66 of air or hydraulic motors 68, 70, the pistons operating in cylinders 72, 74.

[0024] Thus, the clamps and their associated die sections are opened and closed by reversely turning the respective shaft sections in order to admit cup-shaped container halves or cups 75, 76 which are made of metal, preferably aluminum of about 6-10 mils in thickness.

[0025] Associated delivery and discharge mechanism is used to bring the cups to the assembly apparatus 31 and to remove the assembled container but are of no concern as to the present invention.

[0026] As best seen in Figure 3 and 4, the assembly apparatus is provided with vacuum holders 78, 79 which are mounted on the frame and each have an arcuately shaped pocket with a vacuum slot 81 connected with an associated vacuum line 83.

[0027] The holders 78, 79 releasably hold the upper and lower halves 75, 76 of the container with the open end portions 85, 86 (Fig. 6) thereof facing each other. The clamps are then closed about these open end portions as seen in the right half of Fig. 6. If desired, the clamps may first be closed and the halves advanced toward each other and entered into the upper and lower ends of the die 47. It will be noted that the upper and lower end portions 88, 90 of the dies are provided with truncated conical guide surfaces 93., 92 which flare downwardly and upwardly respectively and at their outer ends are of a diameter greater than that of the body portions 93, 94 of the upper and lower cup sections. Thus, the edge portions 85, 86 of the body portions 93, 94 are easily guided into the center portion of the die.

[0028] The center portion of the die has an upper cylindrical die portion with a surface 97, which is equal to substantially the outside diameter of the upper cup. The upper cup is advanced into the surface 93 which rounds the lower edae portion of the upper cup by an upper pusher 100 which has a cap 101 at the lower end of rod 102 of a piston which operates in an air cylinder 103 carried by the frame.

[0029] The upper cup slips alonq the holder 78 and is quided into the cylindrical die surface 97 until the lower edqe 105 of the upper cup seats upon the shoulder 106 at the bottom of the squaring surface 107. Simultaneously, with the upper cup being inserted into the cylindrical section 107, the lower cup is pushed upwardly by an air or hydraulic cylinder 107 which has a base pod 108 bearing against the bottom or base 109 of the lower or male cup. The edge portion 36 of the lower cup has been previously coated with an appropriate adhesive 109. The edge portion 86 of the lower cup is very slightly necked-in but not deformed as it moves past the shoulder 106. The inner edge of the shoulder 106 is of a diameter slightly less than the inner diameter of the upper cup, and the shoulder 106 has a radial dimension slightly larger than the thickness of the metal of the body wall of the upper cup.

[0030] It has been found that the fit of the lower cup edge portion into the upper edge portion merely springs the metal of the lower cup very slightly without permanent deformation and that upon release from the die, the hoop compressive forces on the edge portion 56 are slightly relieved and tensile hoop stresses develop in the edge portion 85. Thus, a tight fit is insured between the two halves and the adhesive which is preferably thermoplastic polyolefin resins such as carboxylated polypropylene or polyethylene as well as thermosetting resins such as epoxy resins. These resins, when heated, will distribute and bond in shear the op- osing outer surface 112 of the inner portion 86 to the inner surface 113 of the outer portion 85. It will be noted that no inner support is required to relescope the two cups into each other and no wrinkling occurs at the juncture so that a good, leak-proof bond is developed which resists separation of the two halves in shear. It will be understood that any cold adhesive or thermoplastic adhesives may be used to bond the two halves.

[0031] After the two cup halves are assembled, the die is opened and the upper and lower pushers separated and a vacuum withdrawn from the holders and the assembled unit is withdrawn or drops out and the following two halves are entered into the apparatus at opposite sides of the die and assembled in a continuous process.

[0032] Thus apparatus and method of bonding the two can portions has been achieved which not only covers the raw edge of the inner section but also arranges the parts in a manner to obtain adequate adhesive at the interface and also the parts cooperate to squeeze out excessive adhesive material so as to obtain a good adhesive bond by utilizing the spring-back of the material which is preferably aluminum alloy of known kind such as H19-3004 of about 6-8 mils in thickness although it is also contemplated that steel materials could be used.

Claims

1. A container having a pair of sections positioned end to end, each section having a thin-walled flexible metal body with an open end defined by an end portion, said end portions being telescoped and forming a lap seam, characterized by said end portions being radially spaced from each other in said seam, and an adhesive material in the space between said end portions bonding the same to each other.

2. The container of claim 1 characterized in that both of said end portions are loaded circumferentially in tension.

3. The container of claim 1 or 2 characterized by said sections being coated interiorly and one of said end portions being within the other and said one end portion having a raw uncoated edge imbedded into said adhesive within said container.

4. The container of claim 1, 2 or 3, characterized by said sections being made of aluminum.

5. The container of any of claims 1 to 4, characterized by said sections being 6-11 mils thick.

6. A method of bonding a pair of container sections end to end wherein each section has a metal thin-walled cylindrical body with an open end defined by an end portion having a raw edge comprising applying a bead of adhesive material of predetermined width on the interior side of the edge portion of one of said sections, and inserting the other section into said one section, characterized in that the section is inserted into said one section while applying a hoop stress to the end portion of said other section to reduce the diameter thereof to slightly less than the internal diameter of said one section, and characterized by the further steps of imbedding said end portion of said other section within said bead of adhesive while maintaining said end portion of the other section in radially spaced relation to said end portion of said one section to provide clearance therefrom and thereby leaving a film of adhesive material of predetermined thickness between the external side of the edge portion of the other section and the internal side of the edge portion of the one section, and then releasing the hoop stress on said end portion of said other section to cause excess bonding material to be squeezed out from therebetween and leaving a thin coating of said material therebetween.

7. The method according to claim 6, characterized by limiting the extent of insertion of said end portion of the other section to less than the band width of said bead to thereby bury the raw edge of the other section within said adhesive material.

8. The method according to claim 6 or 7, characterized in that said hoop stress is limited to a factor within the elastic limit of the material of said end portion to essentially prevent permanent set thereof.

9. The method according to claim 6, 7 or 8 characterized in that said raw edge is imbedded within the adhesive and said adhesive is caused to cover the interior side of said end portion of said other section.

10. An apparatus for assembling a pair of thin-walled cup-shaped container sections adapted to be assembled end to end and each section comprising a cylindrical body wall having an open end defined by an end portion of the body wall which normally assumes an out of round shape; characterized by a support; means for mounting said sections in axially spaced aligned relation and the end portion of each opposing the other; a die assembly mounted on the support in a position to receive one of the container sections at one side thereof and the other container section at the opposite side thereof; said die assembly comprising an opening there through; outer guide means at opposite sides thereof for guiding the end portions of respective container sections into said opening; said opening being defined at one side of the die assembly by a cylindrical surface disposed inwardly as said guide means as a continuation thereof and of a diameter to snugly engage the external side of a container section insertable therein to shape and hold the same round; said guide means on the other side of said guide assembly extending through said shoulder and defining an inner edge thereof; said shoulder having a radial extent slightly greater than the thickness of the body wall of the container inserted into said cylindrical surface area, and means for advancing said container sections toward one another and telescoping the end portion of one container end portion into the other.

11. The apparatus according to claim 10, characterized by mounting means comprising a pair of vacuum cups disposed at opposite sides of the die assembly releasably supporting the respective container sections for movements toward each other.

12. The apparatus according to claim 10 or 11, characterized by means for moving said container sections toward each other.

13. The apparatus according to claim 10, 11 or 12 characterized by said die assembly comprising a pair of complemental segments, and means for closing said segments prep- atory to assembly of said container sections and separable to release the assembled containers.

14. The apparatus according to claim 13, characterized by said support comprising a pair of counterrotating shafts, and said die assembly comprising a pair of radially separable and closable segments connected to respective shafts, and means programmed to close and open the die segments to respectively dispose the die in assembly position and in release position.

15. The apparatus according to any of claims 10 to 14, characterized by said die assembly comprising a die ring having a frusto-conical guide surface tapered toward the die center and forming a through opening therein; a cylindrical squaring surface extending from the inner end of one of said guide surfaces; and a stop shoulder at the end of said cylindrical surface remote from said one guide surface, said shoulder having a radial width substantially equal to or slightly larger than the thickness of the meta] wall of a cup adapted to be inserted thereinto; the other of said guide surfaces extending through said shoulder and forming the inner marginal edge thereof.

16. The apparatus according to claim 15, characterized by said die ring being split diametrically into two halves and a holder for each half having a tongue and groove interlock therewith, and means on each holder for securing the related ring half thereto.

Drawing