Method and apparatus for forming a fabricated thermoplastic container

Abstract: A device for forming a rolled rim (R) at the unrimmed mouth of the body of a container (C) having a body which is fabricated from a sheet of an expanded thermoplastic material, the device including a first member with a first annular rim-forming surface (150), and a second member which is reciprocable relative to the first member. The second member has a second annular rim-forming surface (154) which forms a generally closed rim-forming chamber with the first annular rim-forming surface (150) when the second member is in a first position relative to the first member, the second member being reciprocable to a second position in which the first annular surface and the second annular surface are separated to permit the withdrawal of a container (C) with a rolled rim (R) at the mouth from the first member. The device further includes a transfer mechanism for inserting a container with an unrimmed mouth (UC) over a frustoconical portion of the first member (124) to position such container to have a rim rolled in the mouth thereof in such rim-forming chamber and to withdraw a container (C) with a rolled rim (R) at the mouth from the first member. The rim-forming chamber is heated and there need be no relative rotation between the rim-forming chamber and the container during the forming of a rolled rim (R) in the container (C).

Description: This invention relates to a method of forming a container which has a peripheral wall and a closed end forming a hollow body, the peripheral wall thereof ending with a mouth wall, the free edge thereof being rimmed, to an apparatus for forming a rim at the mouth wall of an unrimmed container having a body with a closed end and being formed from a thin rollable thermoplastic material, and for outputting the rimmed container being formed, and to a container made by the apparatus and according to the method referred to above. In a known method and an apparatus of the preamble to claim 15 (US-A-3,969,173) unrimmed containers are made from sheet material which is rolled to a sleeve which is shrinked over a cup-shaped mandrel, provided with an end piece, whereupon the edge of the mouth wall is compressed to form a compact bead. For that purpose, the apparatus includes first tooling means on the mandrel and second tooling means which can be moved toward the first tooling means so as to form a rimming die wherein the bead at the mouth of the container is formed by some compressed material of the wall. The cross-sectional area of that bead however is small and should be larger to better stiffen the container at the mouth thereof and to provide a smooth edge for drinking. The known method includes the steps a), b), f) and partially c), g), h) and i) of claim 1. In step c), the mouth wall covers the mandrel and therefore is not free. No separate heating step d) for the mouth wall and the rim forming tooling means is provided. The first tooling means is a ring mounted on the mandrel, therefore will not be moved (step e) to the mandrel and removed (step h) therefrom. Relative movement of the first and second tooling means (step g) is carried out by only one active movement of the second tooling means which drag and compress the mouth wall against the first tooling means so as to form a bead, yet not for producing a rolling action upon the mouth wall, as with invention. From EP-A-0 055 844 it is known to curl the top rim of containers. To that end, the containers are transferred from mandrels of the container making line to a mandrelless top curl forming turret which receives the containers in a cup-shaped cavity, yet with the top rim extending out of the cavity. When the cavity wall together with the container moves along the circular path of the turret, a tool is engaging the protruding rim and curles it back on itself. This method has a disadvantage in that the containers must be separated from the main production line and transferred to a special turret where the containers are supported from the outside. Furthermore, mineral oil is used in the curling step to assist it. The problem to be solved is to provide a method and an apparatus for forming a container with a rolled rim at the mouth thereof which can be implemented in a simple manner. The solution of this problem can be taken from claim 1 and claim 15 respectively. In accordance with the present invention there is provided a method and apparatus for forming a rolled rim at the mouth of a container that is formed by fabrication from a sheet of a thermoplastic material, which method and apparatus involves the pressing of the side seam along its length to reduce the thickness thereof and the pressing of the bottom to form a radially thin annular bearing surface with a raised central portion therein. Further, the method and apparatus avoids the need for having relative rotation between the container and the rimming apparatus, although it is contemplated that apparatus for effecting relative rotation between the container and the rimming apparatus during the rimming operation can be provided, if desired. The rim-forming method employs, and the rim-forming apparatus incorporates, a mandrel for receiving the container to be rimmed, and this mandrel incorporates tooling at its base to form a first part of a substantially closed annular chamber for forming the rolled rim in the container. A second part of the substantially closed annular chamber is formed by an annular member which is reciprocable between a first position in which it is adjacent to the tooling at the base of the mandrel to form the substantially closed annular chamber between the first part and an annular surface portion of such reciprocable annular member, and a second position which is away from the tooling at the base of the mandrel to permit the rimmed container to be removed from the mandrel. The rim forming method also avoids the need to transfer an unrimmed cup from the mandrel which it is formed to a rimmer assembly and the apparatus therefor. Accordingly, it is an object of the present invention to provide an improved method and apparatus for forming a rolled rim in a container that is fabricated from a sheet of a thermoplastic material. It is also an object of the present invention to provide an improved method and apparatus for forming the body of a container that is fabricated from a sheet of a thermoplastic material. It is also an object of the present invention to provide an improved method and apparatus for forming a container with a bottom having an annular bearing surface of reduced radial thickness for improved resistance to accidental tipping for a given height to width ratio. For a further understanding of the present invention and the objects thereof, attention is directed to the drawing and the following brief description thereof, to the detailed description of the preferred embodiment and to the appended claims. Brief Description of the Drawing Fig. 1 is an elevational view of a cup making machine which incorporates rim-forming tooling according to a preferred embodiment of the present invention, a portion of the structure of such machine being omitted for the sake of clarity; Fig. 2 is a plan view, at an enlarged scale, of the machine of Fig. 1, with some of the structure that was omitted from Fig. 1; Fig. 3 is a fragmentary elevational view, at an enlarged scale and partly in cross-section, of the machine of Figs. 1 and 2 at the right hand end of the machine as it is illustrated in Figs. 1 and 2; Fig. 4 is an elevational view, partly in cross-section and partly schematic, of the rim-forming tooling of the apparatus of Figs 1-3 in an early state of the operation of such tooling; Fig. 5 is a fragmentary view at an enlarged scale of a portion of the apparatus illustrated in Fig. 4 taken on line 5-5 of Fig. 4; Fig. 6 is a fragmentary view at an enlarged scale of a portion of the apparatus illustrated in Figs. 4 and 5 taken on line 6-6 of Fig. 5; Fig. 7 is a broken fragmentary view at an enlarged scale and partly in vertical cross-section of a portion of the apparatus illustrated in Figs. 4 through 6; Fig. 8 is a fragmentary view at an enlarged scale and partly in vertical cross-section of the upper portion of the apparatus illustrated in Fig. 4; Fig. 9 is a fragmentary view at an enlarged scale and partly in vertical cross-section of the apparatus illustrated in Fig. 8 at a still later state of the operation of such apparatus; Fig. 10 is a fragmentary sectional view taken on line 10-10 of Fig. 3; Fig. 11 is a perspective view illustrating a portion of the apparatus of the present invention; Fig. 12 is a fragmentary elevational view, partly in cross-section, illustrating a modified embodiment of the apparatus illustrated in Figs. 8 and 9; Fig. 13 is an elevational view, partly in cross-section, of a container which has been produced by the apparatus of Fig. 12; and Fig. 14 is a sectional view taken on line 14-14 of Fig. 13. Detailed Description of the Preferred Embodiment As is shown in the drawing figures, the rim-forming tooling of the apparatus of the present invention is utilized to form a rolled rim R, Fig. 9, preferably a tightly rolled rim, at the open mouth of a container C, Fig. 9, by rolling the marginal portion of an unrimmed container UC, Fig. 8. The container C, which is shown as being manufactured in an inverted position in relation to its normal use position, may be considered to be circular in cross-section and is shown as having a nestable or generally frustoconical configuration. The rolled rim R of the container C is located at the open, larger end thereof, and the container C also has a smaller end E, Fig. 9, which is closed, as is described in the aforesaid U.S. Patent No. 3,854,583, so that the container C, when in an upright position, can hold a liquid, for example, hot coffee. Of course, it is contemplated that cylindrical or other non-nestable containers can be provided with a rolled rim at an open end thereof similar to the rolled rim R of the container C. In any case, the container C, or at least a body portion B thereof, Fig. 9, is preferably fabricated from a rectangular blank of a suitable heat-shrinkable thermoplastic material in accordance with the teachings of the aforesaid U.S. Patent No. 3,854,583, and apparatus generally similar to that disclosed in the aforesaid U.S. Patent No. 4,053,346 or generally similar to that disclosed in the aforesaid U.S. Patent No. 4,072,549, appropriately modified to incorporate the rim forming tooling of this invention, may be employed in the manufacture of such containers. Alternatively, apparatus according to the following description may be employed to manufacture such container C. In the manufacture of containers for the serving of single service quantities of a beverage, viz., 6-20 oz. containers, by any of the types of apparatus referred to above, each container, typically, is fabricated from a blank of a rigid, oriented, expanded polymeric material, for example, expanded general purpose or medium impact polystyrene, with an initial thickness of approximately 0,45 - 0,64 mm (0.018-0.025 inch) and with a density of approximately 160 - 192 kg/m³ (10-12 PCF). Of course, the use of other types of rigid thermoplastic materials is contemplated, but expanded polystyrene, alone or in combination with other materials, for example, with coextruded thin surface layers of polyethylene for lustre, is preferred for reasons of economy, rigidity, and insulating characteristics. A cup making machine 100 according to Figs. 1-3 comprises vertically spaced and horizontally extending carriage chains 102 and 104 which are trained around coaxial winder turret carriage sprockets 106 and 108, respectively, at the left hand end of the machine 100 and around coaxial rimmer turret carriage sprockets 110 and 112, respectively, at the right hand end of the machine, for travel in an endless pattern having spaced apart straight lineal portions 114 and 116. The sprockets 106 and 108 are secured to a vertical winder turret shaft 118 which is rotatably driven about its central axis by a conventional motor operated drive unit 120 so that the carriage chains 102 and 104 travel in unison through the machine. The cup making machine 100 also comprises a series of horizontally spaced apart and vertically extending shrink mandrel carriage units 122 each of which is secured both to the carriage chain 102 and the carriage chain 104 for travel therewith. Each shrink mandrel carriage 122 has, at its upper end, a frustoconically shaped shrink mandrel portion 124, each shrink mandrel portion 124 having its smaller end 126 at the top thereof. The winder turret shaft 118 also carries a winder turret 130 at its upper end for synchronized rotation of the turret 130 with the sprockets 106 and 108. The winder turret 130 is provided with a multiplicity of cylindrical sleeve forming mandrels 132 which are evenly spaced from the central axis of the turret 130 and equidistantly around the periphery thereof. The sleeve forming mandrels 132 extend downwardly from the turret 130, and each mandrel 132 is positioned to travel in axial alignment with a shrink mandrel carriage unit 122 for a semi-circular portion of each rotation of the winder turret 130. Cylindrical sleeves S are formed in succession on the sleeve forming mandrels 132 from rectangular blanks which are successively severed from a web W, Fig. 2, of indefinite length of a suitable heat-shrinkable material at a sleeve winding station, which is illustrated generally by reference numeral 134, the details of which are not a feature of the present invention. Each sleeve S is formed on the sleeve forming mandrel 132 which is positioned approximately at the 6 o'clock position of the winder turret 130, as is illustrated in Fig. 2 where the turret 130 is rotating in a counterclockwise direction, and each sleeve S is then transferred from the sleeve forming mandrel 132 on which it is formed to the shrink mandrel portion 124 of the mandrel carriage unit 122 which is aligned with such sleeve forming mandrel 132 when such sleeve forming mandrel 132 has advanced to approximately the 9 o'clock position of the turret 130, as it is illustrated in Fig. 2, by a mechanism which is not a part of the present invention. The relationship between a sleeve forming mandrel 132 and a mandrel carriage unit 122 immediately after the transfer of a sleeve S from the former to the latter is illustrated in Fig. 7. The mandrel carriage units 122 with cylindrical sleeves S on the mandrel portions 124 thereof are thereupon advanced successively through a heating section 148 of the cup making machine. The heating section 148, preferably, is in the form of elongate electric infrared radiant heaters above and on opposite sides of the mandrel carriage units 122 as they advance from the left hand end of the cup machine 100 to the right hand end thereof, and because of the heat shrinkability of the material of the sleeves S, the heating section 148 gradually causes the cylindrical sleeves S on the shrink mandrel portions 124 of the mandrel carriage units 122 to shrink into tight engaging relationship therewith, forming the bodies of unrimmed containers such as the body of the unrimmed container UC illustrated in Fig. 8. Further, each mandrel carriage unit 122 is rotated about its own axis by means which do not constitute a part of the present invention as it passes through the heating section 148 to provide for uniform shrinkage of the sleeves S on the mandrel portions 124. Each unrimmed container UC is provided with an end piece EP in juxtaposition therewith by an end piece punch station, indicated generally at 140, which punches circular pieces from a web of a suitable material, for example, material of the same type used in the fabrication of the cylindrical sleeves S, and which successively deposits end pieces EP in horizontally extending recesses of the mandrel carriage units 122, specifically in a horizontally extending recess 128 (Fig. 7) at the smaller end 126 of the shrink mandrel portion 124 of each mandrel carriage unit 122, as the mandrel carriage units 122 are moving along the lineal portion 116 of their travel through the cup machine 100. The unrimmed containers UC and the end pieces EP are joined together and the body of the unrimmed containers are rimmed at the right hand end of the cup machine 100 by apparatus including a rimmer turret 142 and a plurality of rimmer assemblies, indicated generally at 144 in Figs. 1, 3, 4, 8, and 9, which are evenly spaced from the central axis of the turret 142 and equidistantly around the periphery thereof. The rimmer turret 142 is secured to the upper end of a generally vertically extending shaft 146, which also carries the sprockets 110 and 112, and each of the rimmer assemblies 144 is positioned in axial alignment with a shrink mandrel carriage unit 122 for a semi-circular portion of each rotation of the rimmer turret 142. Each mandrel carriage unit 122 is provided with a first rim-forming surface 150, Figs. 8 and 9, immediately below the mandrel portion 124. As is shown in Figs. 10 and 11, the rim forming surface 150 is formed in split members 156 and 158 which rotate with the shaft 146 and which are repeatedly brought together and then separated as will be hereinafter described more fully. The first rim-forming surface 150 receives the marginal portion of the unrimmed container UC when the unrimmed container UC is depressed by the action of a rimmer assembly 144, as it moves from its Fig. 8 position to its Fig. 9 position, by means which will be hereinafter described more fully, and the rim-forming surface 150 assists in the outward flaring and reversing of such marginal portion that is a part of the process of rolling the rimmed rim R therein. The rimmer assembly 144 also includes an annular member 152, Figs. 8 and 9, which is reciprocable coaxially of the aligned vertical central axes of the rimmer assembly 144 and the shrink mandrel portion 124 of the mandrel carriage unit 122, the reciprocation of the annular member 152 being effected in a manner which will be hereinafter described more fully, The annular member 152 is provided with a second rim-forming surface 154 and is reciprocable between a rimming position, as shown in Fig. 9, in which the second rim-forming surface 154 of the annular member 152 and the first rim-forming surface 150 of the mandrel carriage unit 122 cooperate with one another to form a substantially closed, generally toroidal rimming chamber, and a retracted position, as shown in Fig. 8, to permit the container C to be removed from the cup making machine, such removal being accomplished along the lineal portion 116, in advance of the bottom punch station 140, for example, by a conventional vacuum take-off device, not shown. For proper rimming of the unrimmed container UC without providing for relative rotation between the unrimmed container UC and the riding chamber that is defined by the rim-forming surface 150 and the rim-forming surface 154, it is necessary to heat the marginal portion MW of the unrimmed container UC at the open mouth thereof while the rolled rim R is being formed therein. For example, in the case of an unrimmed container UC which is fabricated from a sheet of expanded, general purpose or medium-impact polystyrene, it is desirable that the temperature of the marginal portion MW of the unrimmed container UC near the open mouth thereof be approximately 88-110°C (190-230 degrees F) during the formation of a rolled rim R therein. This heating is accomplished in the preferred embodiment of the present invention by an arcuate warm air distributor 160, Figs. 3 and 10, which distributes warm air from a conventional air heater-blower, not shown, against each set of first and second split members 156 and 158 as they rotate with the rimmer turret shaft 146 from approximately the 11:30 o'clock position shown in Fig. 10 to approximately the 7:30 o'clock position. Thus, the heat which is stored in each of the split members 156 and 158 of each set of split members during each rotation of the shaft 146 is transferred to the marginal portion of the unrimmed container UC during the forming of the rim R therein by the rim-forming surface 150 that is made up by such set of split members 156 and 158. Each mandrel carriage unit 122 is provided with a central rod 164 which is vertically reciprocable and which is provided with a cam engaging ball member 166, Fig. 7, at its bottom to cause the central rod 164 to rise when the ball member 166 engages a cam, not shown, at the conclusion of the rimming of a container C to assist in the ejection of the container C from the mandrel carriage unit 122, as will be hereinafter described more fully. The weight of each mandrel carriage unit 122 plus the weight of ball member 166 and the rod 164 will result in a gravity return of the unit which includes such members after the ball member 166 moves out of contact with the cam. The central rod 164 reciprocates within a tube 168 which is both reciprocable and rotatable and which carries the shrink mandrel portion 124 of the mandrel carriage unit 122. The tube 168 has a sprocket 170 non-rotatably and reciprocably affixed thereto, and the sprocket 170 engages a fixed chain, not shown, to impart rotation to the tube 168 and the mandrel portion 124 as the mandrel carriage unit 122 is cycled through the cup-making machine 100, especially in the heating station 148 for uniform heating of each sleeve S during the shrinkage thereof. The tube 168, in turn, is surrounded by a non-rotatable annular housing member 180 which carries opposed guide wheels 182 and 184 which are rotatable about horizontal axes and front and rear guide wheels 186 and 188 which are rotatable about vertical axes. The guide wheels 182 and 184 and the guide wheels 186 and 188 are positioned near the upper end of each mandrel carriage unit 122, and one of the guide wheels 182 and 184, shown as the guide wheel 184, engages the top of an upwardly facing U-shaped guide track 190 which extends around the machine 100 while both of the guide wheels 186 and 188 engage the inside of one of the legs of the guide track 190 to guide the movement of each such mandrel carriage unit 122 as it moves in its cycle around the machine 100. The other of the guide wheels 182 and 184, shown as the guide wheel 182, engages a cam surface 192 to control the horizontal elevation of each mandrel carriage unit 122. The annular housing member 180 is provided with sprocket support members 214 and 216 (Fig. 5) which are attached to an alignment plate 212 (Fig. 6) and which supports the sprocket 170 at a fixed elevation with respect to the annular housing member, notwithstanding the reciprocation of the central rod 164 to which the sprocket is non-rotatably attached. The reciprocation of the sleeve 168 is actuated by a cam follower 196 which is attached to a sleeve 194 which, in turn, is affixed to the sleeve 168. The cam follower 196 engages a cam surface 198, Fig. 3, to cause the sleeve 168 and the mandrel portion 124 of the mandrel carriage unit 122 to move toward the associated rimmer assembly 144 as the mandrel carriage unit 122 begins its semi-circular arcuate travel around the sprockets 110 and 112 to bring the shrink mandrel portion 124 into the position relative to the rimmer assembly 144 which is illustrated in Fig. 8. Further, the reciprocation of the central rod 164 relative to the sleeve 168 is actuated by a cam follower 200 which is attached to a sleeve 202 which, in turn, is affixed to the central rod 164 to cause the central rod 164 to rise from its Fig. 7 position, where its upper extremity is part of the horizontally extending recess 128 to receive the end piece EP, to its Fig. 8 position where it presents the end piece EP and the then inturned marginal end portion of the unrimmed container UC for engagement by the adjacent rimmer assembly 144 for the sealing of the marginal end portion of the unrimmed container UC and the portion of the end piece EP which it overlies to one another. The movement of the cam follower 200 and the sleeve 168 is actuated by a cam surface 204, Fig. 3, which engages the cam follower 200 after the cam follower 196 has engaged the cam surface 198. As is shown in Fig. 6, the vertical orientation of the lower end of the mandrel carriage unit 122 during the vertical motion of the sleeve 168 and the central rod 164 is stabilized by an upper guide wheel 206 and a lower guide wheel 208 which ride in a vertical slot 210 in the alignment plate 212 which is attached to the housing member 180 and which extends downwardly therefrom. As is shown in Fig. 9, each rimmer assembly 144 has an end pressing member 218 which engages the end E of an unrimmed container UC during the forming of a rim R therein to simultaneously join an outer peripheral portion of end piece EP to an overlapping, inturned marginal portion MP of the unrimmed container UC. In that regard, each mandrel carriage unit 122 has a back-up member 220 at the top of the central rod 164 which is reciprocable therewith and which supports the underside of the end piece EP during the end pressing operation. Preferably, the joining of the end piece EP to the inturned marginal portion MP of the unrimmed container UC, in the case of a container C whose end piece EP and body B are formed from compatible thermoplastic materials, is performed by heat sealing, to avoid the need for a separate adhesive, and this may be accomplished by the apparatus of the present invention since the warm air distribution 160 will impart sufficient heat to the end pressing member 218 and the back-up member 220, which are metallic and which have sufficient mass to retain substantial thermal energy, to accomplish a heat sealing operation without the need for supplemental heating of such members. As is clear from Fig. 9, both the end pressing member 218 and the back-up member 220 are contoured to provide a slight inward dishing of the central portion of the end piece EP so that the completed container C will be supported or an annular bearing ring BR which is formed by the inturned marginal portion MP of the unrimmed container UC with more stability in its upright orientation. Further, since the back-up member 220 is supported on the central rod 164 which is reciprocable, it may be maintained at an elevation which is lower than its Fig. 9, end pressing position, Fig. 7, as it passes through the heating section 148 to shield the end piece EP from overheating in the heating section 148. The end pressing member 218 is mounted at the lower end of a vertically extending elongate central rod 222 which is reciprocable against the downwardly directed action of a spring 172 that is trapped between a fixed member 174 and a collar 178 which bears against an upwardly facing shoulder 176 of the rod 222. The central rod 222 is reciprocable within a sleeve 224 which is reciprocable against the downwardly directed action of a spring 226, and the spring 226 is trapped between an annular member 228 and a collar 230 which is secured in an outwardly facing annular recess 232 in the annular member 228. The sleeve 224 is also rotatable with respect to the central rod 222 and upper and lower bushings 246 and 248, respectively, are provided between the sleeve 224 and the central rod 222 to facilitate such rotation. Further, the sleeve 224 is rotatable with respect to the annular member 228 and a bushing 236 is provided between the annular member 228 and the sleeve 224 to facilitate such rotation. The annular member 228 and the bushing 236 are axially fixed with respect to the sleeve 224 by a collar 238 which is secured in an outwardly facing annular recess 240 in the sleeve 224 and by the upwardly directed force which is imposed against its underside by the spring 226. Downward movement of the central rod 222 at an appropriate point in the travel of the rimmer assembly 144 of which it a part, to move the end pressing member 218 into its Figs. 8 and 9 pressing position, is imparted by a cam roller 242 which is attached to the fixed member 174 for rotation about a horizontal axis and which engages a fixed cam surface 244. The cam surface 244 is positioned to engage the cam roller 242 approximately at the 7 o'clock position in Fig. 10 and terminates to release the central rod 222 and the end pressing member 218 to return to the Fig. 4, disengaged, positions thereof approximately at the 11 o'clock position in Fig. 10. The sleeve 224 of each rimmer assembly 144 carries an annular assembly 234 which includes an upper outer annular member 250 that is secured to the outside of the sleeve 224, the annular member 152 which is resiliently attached to the lower end of the upper outer annular member 250 by means of a plurality of circumferentially spaced apart bolt and spring assemblies 254, shown as three of such bolt and spring assemblies, the rim forming surface 150 constituting a surface of the annular member 152, and an upper annular member 256 which has an inner frustoconically shaped surface 258 that engages the outside surface of an unrimmed container UC on a shrink mandrel portion 124 of a shrink carriage unit 122 as the rimming process is about to begin, Fig. 8. Thrust bearings 260 are positioned between an annular surface 262 of the annular member 152 and an annular surface of a collar portion 266 of the upper outer annular member 250 to provide for relative rotation between the upper outer annular member 250 and the lower annular member, on the one hand, and the upper inner annular member 256, on the other hand. This will permit the upper inner annular member 256 to rotate with the shrink mandrel portion 124 of the shrink carriage unit, which is affixed to the tube 168 of the shrink carriage unit by a screw 252, Fig. 8, as the tube 168 is rotated, as heretofore explained. Downward movement of the sleeve 224 and the annular assembly 234 which is carried thereby at an appropriate point in the travel of the rimmer assembly 144 of which it is a part, to move the surface 258 of the upper inner annular member 256 into engagement with the outer surface of an unrimmed container UC and then to move the rim forming surface 150 of the lower annular member into its Fig. 9, rim forming, position with respect to the split member 156, is imparted by a cam roller 266 which is attached to the annular member 228 for rotation about a horizontal axis and which engages a cam surface 268. The cam surface 268 is positioned to engage the cam roller 266 approximately at the 7 o'clock position in Fig. 10 and terminates to release the sleeve 224 and the annular assembly 234 to return to the Fig. 4, disengaged, positions thereof approximately at the 12 o'clock position in Fig. 10. As is apparent from Fig. 8, during the downward stroke of the sleeve 224, the inside surface 258 of the upper inner annular member 256 will engage the unrimmed container UC before the rim forming surface 150 of the annular member moves into its Fig. 9, rim forming position. Further axial movement of the annular member 152 with respect to the upper inner annular member 256 is accomplished by the travel of the outer annular member 250 which is caused by the cam 268 and which compresses the spring 254 to complete the rimming process. As is shown in Fig. 7, each mandrel carriage unit 122 also includes an annular lower shrink mandrel 268 whose outer surface 270 is aligned with the outer surface of the shrink mandrel portion 124 of the mandrel carriage unit to engage the inside of a lower marginal portion of a sleeve S and a segmented clamping member 272 which is constricted by a clamping spring 274 and which resiliently engages the outside of the lower marginal portion of the sleeve S to securely position the sleeve S with respect to the mandrel carriage unit at the time when the sleeve S is transferred to the mandrel carriage unit 122 from the sleeve forming mandrel 132 and through the travel of the mandrel carriage unit 122 through the heating section 148. The lower shrink mandrel 268 is attached to the tube 168 by a set screw 276 for rotation and reciprocation therewith, and the downward travel of the tube 168 to remove the lower shrink mandrel 268 and the segmented damping member 272 from engagement from such lower marginal portion, now the lower marginal portion of an unrimmed container UC, is timed to occur before the mandrel carriage unit 122 moves into alignment with a rimmer assembly 144. Rotation of the structure which includes the shrink mandrel 124, the lower shrink mandrel 268 and the segmented clamping member 272 with respect to the nonrotatable housing member 180 is permitted by attaching a flange 278 at the bottom of the lower shrink mandrel 272 to an annular collar 284 which surrounds a reduced diameter portion 280 of the housing member 180, and by positioning an annular bearing member 282 therebetween. Further, rotation of the tube 168 with respect to the housing member 180 is permitted by positioning upper and lower bushings 286 and 288, respectively, therebetween. The sequential opening and closing of the first split member 156 and the second split member 158 of each annular member 152 with respect to one another, as heretofore described and as is illustrated in Fig. 11, is accomplished by pivoting the split members 156 and 158 for oscillation with respect to one another at a vertical axis 290, by attaching a first link 292 to an annular post 294 which extends upwardly from the first split member 156, by attaching a second link 296 to a rod 290 which extends upwardly from the second split member 158 through the annular post 294, by providing a first cam roller 300 attached to an interior portion of the first link 292, by attaching a second cam roller 302 to an interior portion of the second link 296, and providing a cam 304, Fig. 10, which is engaged by the cam rollers 300 and 302, as the annular member 152 rotates around the rimmer assembly shaft 146, as heretofore described. The first split member 156 and the second split member 158 are resiliently biased toward their closed positions by a double ended spring 306, one end of which is secured to a first pin 308 that extends upwardly from the first link 292 and the second end of which is secured to a screw pin 310 that extends upwardly from the second link 296. Fig. 12 illustrates a modified embodiment of the portion of the apparatus of Figs. 1-11 which is illustrated in Figures 8 and 9. Elements of the apparatus of Fig. 12 which are similar, but not identical, in construction and function to elements of Figs. 8 and 9 will be identified by an apostrophe following the three digit identification of the corresponding element in Figs. 8 and 9, or by an apostrophe following the letter identification, as the case may be. The apparatus of Fig. 12 utilizes an upper annular member 256′ which differs from the upper annular member 256 of Figs. 8 and 9 in that its inner, frustoconically shaped surface 258′ engages the outside surface of an unrimmed container UC′ on a shrink mandrel portion 124′ of a shrink carriage unit 122′, shown fragmentarily, along its entire height as the rimming process is about to begin. The radial spacing between the outside surface of the shrink mandrel portion 124′ and the inner, frustoconically shaped surface 258′ is not greater than the wall thickness of the major portion of the unrimmed container UC′, to ensure that the unrimmed container UC′ is securely engaged between the upper annular member 256′ and the shrink mandrel portion 124′. The body of the unrimmed container UC′ will have a generally vertically extending seam in its sidewall. This seam is not shown in Fig. 12 but it is formed by overlapping the ends of a blank from which the body of the unrimmed container UC′ is formed, and this seam will originally be approximately twice as great in thickness as the thickness of the other portions of the sidewall of the unrimmed container UC′. By virtue of the spacing between the upper annular member 256′ and the shrink mandrel portion 124′, as heretofore described, and the fact that the unrimmed container UC′ is formed from an expanded polymeric material which is compressible under load, the generally vertically extending seam of the body of the unrimmed container UC′ will be compressed in thickness so that its thickness will be not substantially greater that the wall thickness of the unrimmed container UC′. Because the vertical extent of the inner, frustoconically shaped surface 258′ of the upper annular member 256′ of the embodiment of Fig. 12 extends beyond the juncture of the sidewall and the end of the unrimmed container UC′, it is necessary to provide the apparatus of Fig. 12 with an end pressing member 218′ which is reduced in its outer diameter relative to its counterpart in the embodiment of Figs. 8 and 9, namely the end pressing member 218, so that the end pressing member 218′ fits entirely within the outline of the end of the unrimmed container UC′, which is formed, in part, from a separate end piece EP′. Further, the face of the end pressing member 218′ which engages the bottom of the unrimmed container UC′, namely the face 218′a, is contoured to form a radially outermost and radially thin bearing ring BR′ in the bottom of the unrimmed container UC′ and a raised central portion CP′ within such bearing ring BR′. Thus, a cup formed by the apparatus of Fig. 12 is more resistant to accidental tipping on a flat surface than a cup of comparable height and width formed by the apparatus of Figs. 8 and 9, whose bearing ring BR will be substantially thicker, in the radial direction, than the bearing ring BR′ of the embodiment of Fig. 12. A generally frustoconically shaped cup which is formed by apparatus according to the embodiment of Fig. 12 is generally identified by reference numeral 21 in Fig. 13. The cup 21 is formed from an expanded polymeric material and has a generally vertically extending sidewall 22 with a generally vertically extending side seam 23 therein, the side seam being formed by overlapping the ends of a blank from which the sidewall 22 is fabricated. The cup 21 further has a rolled bead 24 at its upper, open mouth, which is the larger end of the cup 21, and a closed bottom 25 at its lower end which is formed in part from the end piece EP′ of Fig. 12 and in part from an inturned marginal portion 27. The inner portion 27 is entirely within the bearing ring 26 and is elevated with respect thereto, thus remaining out of engagement with such table top or surface during the normal use of the cup 21. As is clear from Fig. 14, the thickness of the side seam 23 is not substantially greater than the thickness of the sidewall 22 in the portions thereof which are immediately adjacent thereto, in spite of the fact that the side seam 23 is formed by overlapping the opposed ends of a blank from which the sidewall 22 was fabricated. Such reduced side seam thickness, which results from the positional relationship of the upper annular member 256′ and the shrink mandrel portion 124′, as heretofore explained, and from the fact that the cup 21 is formed from an expanded material which can be compressed in its thickness under suitable load, permits a multiplicity of like cups 21 to be nested together more closely than their prior art fabricated cup counterparts. This is an advantage for all cup applications, and is particularly advantageous for vending machine cups where close nesting is particularly important. By virtue of its thinner side seam 23, nested like cups 21 can also be mechanically denested more reliably, and this is also particularly advantageous for vending machine cup applications. The cup 21 is also provided with a series of circumferentially spaced apart, radially inwardly projecting, like stacking lugs 28 around a lowermost generally vertically extending portion 29 of the sidewall 22. Thus, the bottom 25 of a cup 27 will engage the tops of the stacking lugs 28 of a like cup 21 when nested therein to maintain a uniform spacing between the rims 24 of like cups 21 in a nested stack thereof and to prevent jamming of the cups in the stack. Cup 21 is also provided with a rim stacking feature for use in addition to or in place of the bottom stacking features of the stacking lugs 28, namely a generally vertically extending portion 31 of the sidewall 22 at the uppermost portion thereof. A juncture 32 between the portion 31 and the portion of the sidewall 22, which is below the lowermost edge of the rolled bead or rim 24, is positioned to rest on the inside of the top of the bead or rim 24 of a like cup 21 in a nested stack of such cups, and the thickness of the sidewall 22, by virtue of its fabrication from a sheet of an expanded thermoplastic material, may be adequate to prevent jamming between like cups 21 in a nested stack thereof. Although the best mode contemplated by the inventors for carrying out the present invention as of the filing date thereof has been shown and described herein, it will be apparent to those skilled in the art that suitable modifications, variations and equivalents may be made without departing from the scope of the invention, such scope being limited solely by the terms of the following claims:

Claims: A method of forming a container (C) which has a peripheral wall and a closed end (E) forming a hollow body (B), the peripheral wall thereof ending with a mouth wall (MW), the free edge thereof being rimmed, comprising the steps of: a) providing a blank of thermoplastic material for said hollow body (B); b) producing said hollow body (B) from said blank as an unrimmed container (UC); c) supporting said unrimmed container (C) from inside by a mandrel (124) so that said mouth wall (MW) is free and accessible to operation; d) heating said mouth wall (MW) and first and second tooling means (156, 158; 152) having first and second annular rim forming surfaces (150; 154), respectively, onto a forming temperature adapted to the thermoplastic material of the hollow body (B); e) moving said first tooling means (156, 158) to said mandrel (124) and applying said first rim forming surface (150) to said mouth wall (MW) so that the free edge thereof is adjacent to said first forming surface (150); f) applying said second rim forming surface (154) of said second tooling means (152) to said mouth wall (MW) so as to overly it; g) moving said first and second tooling means (156, 158; 152) actively relative to one another and to said mouth wall (MW) so as to carry said free edge of said mouth wall (MW) in engagement with said first forming surface (150) and roll said mouth wall back, and when said second forming surface (154) is approaching said first forming surface (150), engaging said free edge of said mouth wall by said second forming surface (154) and roll the wall back further so as to form a rolled rim (R); h) moving said first and second tooling means (156, 158; 152) away from one another and from said mandrel (124), and i) ejecting the container (C) on which a rolled rim (R) is formed. The method of claim 1 wherein said mandrel (124) is a frustoconically shaped member. The method of claim 2 wherein said mandrel (124) and said first tooling means (156, 158) are shifted without relative rotational movement onto one another during forming of the rolled rim (R). The method of claim 3 wherein in step g) movement of said first and second tooling means (156, 158; 152) relative to one another is a shifting movement without rotation. The method of any of claims 1 to 4 wherein a first heating is performed in step b) for forming said hollow body (B), followed by said heating of step d) for forming said mouth wall (MW). The method of any of claims 1 to 5 wherein said heating step d) also extends over step e). The method of claim 6 wherein said heating step d) is continued over steps f) and g) so that heat is transferred from said first and second tooling means (156, 158; 152) onto said mouth wall (MW) during said rolled rim (R) is being formed. The method of any of claims 1 to 7 wherein said blank of thermoplastic material is an expanded sheet (S) of general purpose polystyrene or medium impact polystyrene and wherein said forming temperature in step d) is approximately 88 to 110°C (190 to 230°F). The method of any of claims 1 to 8 wherein in step g) said first and second tooling means (156, 158; 152) form a generally torodial chamber, the free edge of said mouth wall (MW) travelling along the wall of the torodial chamber which is covered by said rolled rim (R) being formed. The method of any of claims 1 to 9 wherein said blank is sheet-like and said thermoplastic material is an expandable polymeric material, and wherein said hollow body (B) has a longitudinally extending seam (23) formed from overlapping ends of the blank, said method further comprising the step j) of engaging the body (B) of the container along its outer surface to reduce the thickness of the generally longitudinally extending seam (23) substantially along its entire length to a thickness which is not substantially greater than the thickness of the wall of the body (B). The method of claim 10 wherein the body (B) of the container is supported substantially along its whole inner surface and is substantially engaged along and around its outer surface. The method of claim 11 wherein the step of engaging the body (B) of the container along its outer surface is performed by providing annular member means (256, 256') having a generally frustoconically shaped inner surface (258, 258'); wherein one of said mandrel (124, 124') and said annular member means (256, 256') is reciprocable relative to the other, and further comprising the steps of advancing one of said mandrels (124, 124') and said annular member means (256, 256') toward the other at the beginning of the forming of the rolled rim (R); and retracting the one of said mandrel (124, 124') and said annular member means (256, 256') away from the other at the conclusion of the forming of the rolled rim (R). The method of any of claims 1 to 12 wherein during steps e) through g) a heated-up backup member (220, 220') and a heated-up pressing member (218, 218') engage the closed end (E) of the unrimmed container (UC) and press it conforming to the shape of these members (220, 220'; 218, 218'). The method of claim 13 wherein said closed end (E) comprises material from an end piece (EP, EP') and from an inturned marginal portion (27) of the sidewall (22) of the container. An apparatus for forming a rim (R) at the mouth wall (MW) on an unrimmed container (UC) having a body (B) with a closed end (E) and being formed from a thin, rollable thermoplastic material (S), and for outputting the rimmed container (C) being formed, said apparatus comprising: transporting means (102, 104, 122, 200) including a mandrel (124) for taking up said unrimmed container (UC) and moving same along a rim forming station and to an ejection station, first tooling means (156, 158) having a first annular rim-forming surface (150) and being movable together with said mandrel (124) along said rim forming station, second tooling means (152) having a second annular rim-forming surface (154), a rimmer assembly (144) for moving said second tooling means (152) toward, and away from, said first tooling means (156, 158) so that said rim-forming surfaces (150, 152) take an open position with space between said surfaces (150, 152) and a closed position for forming an annular chamber, characterized in that said mandrel is sized in relation to said unrimmed container (UC) so that the mouth wall (MW) thereof is unsupported by said mandrel whereas said first tooling means (156, 158) is shaped to enter into said mouth wall (MW) and is seperable from said mandrel, heating means (160) is provided for heating said mouth wall (MW), said first annular rim-forming surface (150) and said second annular rim-forming surface (154), and in that a further reciprocating means (182, 184, 186, 188, 190, 192) is provided for moving said first tooling means (156, 158) relative to said mandrel (124) so that the mouth wall (MW) of the unrimmed container (UC) moves to and along said first rim-forming surface (150), and when said second tooling means (152) approaches said first tooling means (156, 158), also along said second rim-forming surface (154). The apparatus of claim 15 wherein said first tooling means is formed in split members (156, 158) which orbit along a path which partially coincides with the path of the transporting means (102, 104, 122, 200), and wherein said split members (156, 158) are brought together to encompass said unrimmed container (UC) at the mouth wall (MW) thereof, mainly during travel of the tooling means and the transporting means along the coinciding path length, and are separated to permit withdrawal of the then formed container (C) from the split members (156, 158). The apparatus of claims 15 or 16 wherein said first tooling means (156, 158) has a collar which extends from said first annular rim-forming surface (150) and is introduced into the mouth of the unrimmed container (UC) by said further reciprocating means for supporting the mouth wall (MW) during formation of the rolled rim (R). The apparatus of claim 17 wherein said collar is generally frustoconically shaped. The apparatus of any of claims 15 to 19 wherein said mandrel (124, 124') is of generally frustoconical shape, and annular member means (256, 256') has a generally frustoconically shaped inner surface (258, 258'), both for engaging the unrimmed container (UC) from inside and outside, said further reciprocating means (182, 184, 186, 188, 190, 192) being adapted to move said mandrel relative to said annular member means. The apparatus of claim 19 wherein said mandrel (124, 124'), said annular member means (256, 256') and said further reciprocating means (182, 184, 186, 188, 190, 192) are constructed to press the body (B) of the container so that when there is a seam (23) formed from overlapping ends of the blank, the thickness of said means (23) is reduced to a thickness which is not substantially greater than the thickness of the wall (22) of the body (B). The apparatus of claims 19 and 20 further comprising a backup member (220, 220') and an end pressing member (218, 218') which have disposed said closed end (E) therebetween, third reciprocating means (164, 200) and fourth reciprocating means (222, 242, 244) being arranged for driving said backup member and said pressing member together so as to form said closed end (E) of the container. A container (C) comprising a rolled rim (24) and a longitudinally extending seam (23), the thickness thereof essentially corresponding to the thickness of the body wall (22) made according to the method of claims 10 and 11. The container (C) of claim 22 comprising a closed bottom (25) having a bearing ring (26) and an inner elevated portion made according to the method of claims 13 and 14. The container (C) of claim 23 comprising stacking lugs (28) in the sidewall (22) of the container near the bottom (25) thereof made according to the method of claim 13. The container (C) of any of claims 22 to 24 comprising a generally cylindrical portion (31) of the sidewall (22) near the rolled bead (24) and having a juncture (32) to the main body (B) of the container which is positioned so that a lower container of a nested stack will rest on the underside of the rolled bead (24) of an upper container in the stack.

Inventors: BLACKWELDER MAURICE W, BURTCH JOHN E, HILL JAMES A, BLACKWELDER, MAURICE W., BURTCH, JOHN E., HILL, JAMES A.
Applicants: OWENS ILLINOIS PLASTIC PROD, OWENS-ILLINOIS PLASTIC PRODUCTS INC.
Application year: 1990
Main classification: B29C57
IPC codes: B29C53, B29K101, B31B49, B29C57, B29L22, B29L31, B29K105, B29K25