US 3355536 A
Description (OCR text may contain errors)
NOV. 28, 1967 MHDGLEY ET AL 3,355,536
RIM ROLLING MACHINE AND METHOD 2 Sheets-Sheet 1 Filed Aug. 18, 1965 INVENTORS Y E I & DM 1, WJ LR CIL R mm VI] ATTORNEYS Nov. 28, 1967 E WDGLEY ET AL 3,355,536
RIM ROLLING MACHINE AND METHOD Filed Aug. 18, 1965 2 Sheets-Sheet 2 FIGS INVENTORS ERIC L. M l DGLEY,
ATTORN EYS United States Patent 3,355,536 REM ROLLING MACHINE AND METHOD Eric L. Midgley and Carl R. Jank, Danvers, Mass, as-
signors to Sweetheart Plastics, Inc., Wilmington, Mass., a corporation of Maryland Filed Aug. 18, 1965, 501'. No. 480,551 11 Claims. (Cl. 264-322) ABSTRACT OF THE DISCLOSURE Rim rolling plastic containers comprising feeding the containers in nested relationship horizontally and rotating them in a chamber wherein radiant heaters apply heat to the rims evenly While the side wall of each container is protected by side wall of the next stacked container. Thereafter, the heated rims are turned by the rotating screw rim rollers and are then discharged in a horizontal direction.
This invention relates to a method and apparatus for rolling the rims of plastic containers. More particularly, the invention relates to a method and apparatus for rolling the rims of plastic dishes and cups.
It has long been the practice to form paper cups with rolled rims to give them a finished appearance and added strength, and make them more comfortable when placed in the month while in use. The same advantages are derived by rolling the rims of plastic cups and they, too, are now formed with rolled rims albeit with some difiiculty. Some of the characteristics of plastic which make it difficult to roll container rims are the relative stiffness and brittleness of the material and the narrow temperature range within which the material may be worked. Further, when the temperature of the stock is in the working temperature range, it has very little stiffness and has a tendency to sag and distort unless supported. Consequently, during the formation of the rolled rims it is undesirable to heat the main body of the containers which are not subjected to the rolling operation, as they may sag or otherwise distort.
One important object of this invention is to provide apparatus for rolling the rims of containers, which is relatively inexpensive to manufacture, and which operates at great speed so as to add negligibly to the cost of the manufacture of the containers.
Another important object of this invention is to provide apparatus for consistently producing plastic cups or other containers with well-formed rolled rims suitable for further mechanical handling during counting, packaging and vending.
Still another important object of this invention is to provide a method for rolling the rims of containers which provides an even curl in the rim about the entire periphery of the container.
Yet another important object of this invention is to provide a method of rolling the rims of containers, which avoids the necessity of contact heating the rims of the containers while confining the heat generally to the rims being rolled.
To accomplish these and other objects this invention includes among its features a chamber having means within it for supporting containers in nested relationship with the axis of the stack of nested containers in a horizontal plane. Means are provided adjacent the support for rotating the containers while in the nested condition as they move in an axial direction through the chamber. Radiant heaters are disposed in the chamber for evenly heating the rims of the containers as they move through and rotate in the chamber. A plurality of screw rim rollers are disposed in the chamber, and the threads of the rollers receive the rims and turn them inwardly as the individual rim rollers are rotated.
These and other objects and features of this invention along with its incident advantages will be better understood and appreciated from the following detailed description of one embodiment thereof, selected for purposes of illustration and shown in the accompanying drawing, in which:
FIG. 1 is a front view partly in section of a rim rolling machine constructed in accordance with this invention;
FIG. 2 is a cross-sectional view taken along the corresponding section line in FIG. 1;
FIG. 3 is a top View partly in section of the rim rolling machine;
FIGS. 4 and 5 are side views, partly in section, of a cup showing its rim before and after it has been rolled by the machine; and
FIGS. 6, 7 and 8 are fragmentary cross-sectional views illustrating the successive steps performed by the machine to roll the cup rim.
The machine shown in the drawing includes in its general organization a supporting frame 10 supporting a housing 12 within which the rim rolling operation takes place, a conveyor mechanism 14 to direct containers into the housing 12 and a receiving station 16 on which the containers may be counted or otherwise handled after being treated in the chamber 12. Before discussing each of the different components of the machine, the function performed by the machine will be described in connection with FIGS. 4 and 5. i
In FIG. 4 a thin-walled plastic cup 20 is shown having a bottom Wall 22, a side wall 24 and a rim 26. The rim 26 includes an upper generally horizontal flange 28 and a downturned skirt 30. The rim 26 including the horizontal flange 28 and the skirt 30 as shown in FIG. 4, are in the configuration produced by the cup forming machine and prior to being subjected to the rim rolling operation performed by the machine of this invention. It will be appreciated that the down-turned skirt 30 if left in the configuration shown in FIG. 4 would not be comfortable to the month, particularly because of the exposed downturned edge 32. It will also be appreciated that the skirt 30 in cooperation with the flange 28 and the outer surface of the upper portion of the side wall 24 defines an inverted trough which may collect air or other impurities that would make the cups unusable. Further, the downturned skirt 30 may interfere with or engage the next lower cup in a stack of identical cups nested together in a manner which would interfere with the feeding of such cups in a vending machine.
The cup shown in FIG. 4 is made acceptable by rolling the rim 26 into the configuration shown in FIG. 5. In that figure it will be noted that the skirt 30 is curled under the horizontal flange 28 to substantially close the troughshaped cavity defined by the skirt and side wall, to hide or confine the raw edge 32 of the skirt so that the rim is comfortable to the mouth, and to shorten the axial height of the skirt so that it will not interfere with the next lower cup in a nested stack. The machine of this invention imparts to the rim 26 the configuration shown in FIG. 5.
The conveyor mechanism 14 disposed on the right side of the machine as viewed in FIG. 1, includes a conveyor belt 34 supported on an idler roller 36 and a driven roller 38, and the belt travels in the direction of the arrows 46. A motor 42 on shelf 44 secured to the legs 46 of the frame It) drives the driven roller 38 of the conveyor through a gear box 48 and belt and pulley assembly 59.
The upper run 52 of the belt 34 serves as a support for the cups as they are fed by the conveyor assembly to the treating chamber 12. The cups are guided along their course on the upper run of the belt by a pair of rails 53 and 54 that extend from adjacent the idler roller 36 over the top run 52 of the conveyor and through the housing 12 to the receiving station 16. In FIGS. 1 and 3 a nested stack of cups is suggested disposed on the upper run 52 of the belt 34, the cups being oriented with their rims 26 facing in the direction of the housing or chamber 12. The cups are fed while stacked in closely nested association by the conveyor belt 34 to a position adjacent opening 56 in the side wall 58 of the housing 12.
Disposed above the conveyor mechanism 14 adjacent the driven pulley 38 is a rotating brush-like driving wheel 60 also driven by motor 42 through gear box 48 and a belt 62. The wheel 60 assists the conveyor belt 34 in pushing the continuous stack of nested cups, rim first, through the opening 56 in the side wall 58 of the chamber 12. The driving wheel 6!] has soft bristles 64 which engage the rims 26 of the cups supported on the upper run 52 of the belt and the rails 53 and 54 and rotates clockwise as viewed in FIG. 1.
The housing 12 is defined in part by the side wall 58 and also includes opposite side wall 64 and bottom wall 66, as well as front, back and top walls (not shown). The walls may be lined with heat insulating material. The rails 53 and 54 extend across the center of the chamber 12 and leave the chamber through an opening 68 in the side wall 64. As shown in FIG. 2, three radiant heaters 70, 72 and 74 extend parallel to the rails 53 and 54 within the chamber 12 and are arranged 120 apart with the heater 70 directing its heat downwardly above the stack of cups and the heaters 72 and 74 disposed slightly below the axis of the cups and direct their heat to the lower opposite sides.
Disposed below the rails 53 and 54 and positioned to engage the rim 26 of each of the cups in the stack is a roller 76 having a knurled surface 78 which imparts a rotary motion to the cups as they are pushed through the chamber 12 on the rails. The roller 76 as shown in FIG. 1 is driven by the motor 42 through gear box 48 and a belt 80. The belt 80 engages a pulley 82 connected to the end of shaft 84 which supports the roller 76.
The shaft 84 also supports one of three screw-type rim rollers 86. The others are identified by reference characters 88 and 90. The screw rim roller 86 carried on shaft 84 rotates at the same speed as the roller 76, and the diameter of the roller 76 is substantially the same as the diameter of the screw rim rollers measured across the rim roller grooves. The screw rim rollers 88 and 90 are geared to the screw rim roller 86 by planetary gears (not shown) or some similar connection, so that all three screw rim rollers rotate at the same speed and in the same direction so as to impart the same movement to the rims of the cups. If the shaft 84 is rotating in the direction suggested by arrow 92, the screw rim roller 86 rotates clockwise as viewed in FIG. 2, and the other two screw rim rollers rotate in the same direction.
In the manner shown in FIGS. 6-8, the screw rim rollers 86, 88 and 90 turn the down-turned skirts 30 of the rims 26 inwardly to form the rims into the configuration shown in FIG. 5.
In FIG. 6 the rim 26 of the cup is shown in engagement with the beginning of the first volute of the screw rim roller 86. It will be noted that the horizontal flange 28 of the rim bears against the side of the volute, and the down-turned skirt of the rim bears against the bevelled portion 93. In FIG. 7 the cup 20 is shown after the screw rim roller 86 has turned through perhaps 180. In that figure the down-turned skirt is partially turned inwardly by the trailing side 95 of the volute 97. In FIG. 8 this skirt is shown fully rolled having traveled approximately an additional 180" in the volute as the rim roller has rotated to complete its first revolution. In FIG. 8 it will also be noted that the next container is entering the volute at the inlet point. Thus, in approximately one revolution of the screw rim rollers the rolled rim is substantially fully formed, and as the rim continuesto travel through the volute to the rear end of the screw rim rollers, the rim has an opportunity to set.
The bevel 93 provided in each of the screw rim rollers first serves to return the skirt to its initial position wherein it is substantially cylindrical with respect to the cup axis if it has moved from that condition. The heat applied to the rims as the cups move in the chamber 12 has a tendency to cause the rims to uncurl and the skirts 30 to move radially outward because of the memory of the material. Thus, the bevel 93 first corrects the shape of the down-turned skirt and then provides an access for the skirts entering the volutes 97.
After the rims are rolled to the configuration shown in FIG. 5 the cups continue to move in nested relationship on the rails 53 and 54 through the opening 68 to the receiving station 16. At the station 16 a counter or other device may be used to separate the containers in stacks of any particular number, and an operator may remove the counted stacks of containers from the rails and place them in a box or other shipping carton.
With the foregoing description of the components of the machine, the reader may appreciate some of its advantages and refinements. First, it will be noted that while the entire body of each cup passes through the chamber 12 containing the radiant heaters 70, 72 and 74, substantially only the down-turned skirts 30 are subjected to the heat of the heaters because the cups are in closely nested relationship, and the side wall and bottom wall of each cup is contained within the next cup in the stack. Consequently, each cup is protected by the next succeeding cup, and substantially only the skirts 30 of the rims are exposed.
Second, the roller 76 with the knurled surface 78 imparts a uniform rotation to the cups by engaging each of their rims. The roller 76 is rotating at a very substantial speed of perhaps 1,000 r.p.m. so as to impart a significant speed of rotation to the cups themselves. Consequently, a very uniform application of heat is made to the rims as no portion on the rim perimeter is exposed for a longer period than any other portion to the heaters 70, 72 and 74. a
The positive action of turning the cups while they are exposed to the radiant heaters insures maximum uniformity of heat distribution. Further, the horizontal orientation of the cups as they pass through the chamber 12 allows each to be supported on the roller 76 so that one cup does not interfere with anothers rotation. That is, there is a minimum of frictional contact between adjacent cups so that one does not interfere with the next and create a jerky or uneven rotation of the cups. Stated in another way, because the containers are on their sides, they will have less of a tendency to key together and adhere to one another.
From the foregoing description those skilled in the art will appreciate the numerous features of this invention. Of particular importance is the ability of the machine to apply heat evenly to the rims and of the volutes' 97 of the screw rim rollers to form an even curl about each of the cups. Further, the nested relationship of the cups provides an air insulation about each cup within the next cup in the row. Consequently, while heat is applied to the rims, a lesser quantity of heat is applied to the side and bottom walls of the cups, and therefore they are not heated to a forming temperature and do not distort when the rims are heated.
Those skilled in the art will appreciate that numerous modifications may be made of this invention without departing from its spirit. Moreover, although in the foregoing description the machine is described primarily in terms of rolling cup rims, it is to be understood that the machine has wider application. Therefore, it is not intended that the breadth of this invention be limited to the single embodiment illustrated and described. Rather it is intended that the scope of this invention be determined by the appended claims and their equivalents.
What is claimed is:
1. A machine for rolling the rims of thin-walled plastic nestable cups having side and bottom walls and a rim comp-rising