Patent Grant
7175409
The present invention relates to a lip rolling machine for forming lips on thermoplastic containers, such as disposable cups, food packages, etc.
Lip-rolling machines are used to produce a rolled rim on plastic containers. After trimming of the container from a thermoplastic sheet, the open end of the container has a rather sharp edge with an outward flare. The reason for rolling this edge is at least two-fold. First, drinking from a cup made in this fashion is a less than suitable undertaking for the user. Second, it is difficult to manufacture a lid which will fit about the flared edge and still maintain a suitable seal against the container rim.
Conventional lip rolling machines utilize an open ended, clam-shell type electric heating oven to heat and form lips on horizontally-nested thermoplastic containers, such as cups, as they are advanced off a production line. U.S. Pat. No. 6,093,010, issued Jul. 25, 2000, to Lamson, discloses a typical thermoforming process, including a clam shell oven. The oven often generates heat to cause internal surface temperatures of the oven to reach in excess of 500° F. with the heaters themselves getting up to 1200° F. However, when the production line is stopped—due, for example, to a thermoforming machine malfunction—a length of cups remain in the hot open oven. If this length of cups (approximately two feet of nested cups) is not removed from the oven when the line is stopped, these cups may catch fire or melt. Moreover, the line uses guide rails to stabilize the cups within the oven, but because of the extreme heat generated by the open-ended oven, it is necessary to run cooling water through the guide rails to keep the rails from overheating. This requirement adds to the expense and complexity of the machinery. Traditional lip rolling machines induce large amounts of heat into the open oven, and thus, utilize large amounts of energy.
Typically, lip rolling machines guide the cups along water rails up to a lip rolling screw assembly, within the clamshell oven, with the top open and the oven hot. Once the cups engage the screw(s), the oven lid is closed and the rim rolling process begins. As a result, a length of cups equal to or greater than the distance between a crowd roller assembly and the lip rolling screw assembly must be removed and discarded due to the insufficiency of heat applied to the cups from the oven being open and the lack of pressure applied by the crowd rollers.
The present invention is provided to solve these and other such problems with prior art devices.
The present invention provides a lip rolling system for rolling lips about the open mouths of stacked thermoplastic containers can generally be described as comprising a supply line of nested thermoplastic containers, a screw assembly positioned to receive the nested thermoplastic containers, a mechanism for directing the nested thermoplastic containers toward the screw assembly, and a heat source having an initial position to direct a supply of heated air at the containers as they are engaged by the screw assembly.
It is an aspect of the disclosed system that the heat source may be removed from the initial position to a safety position automatically in response to a signal. Such a signal may be generated in response to a temperature sensor, system error, or any other such triggering episode.
Finally, an embodiment of the disclosed heating system for a lip rolling machine generally comprises a heat source set at an initial position and having a housing with an open exit end directed toward a container area, an air source coupled to the heat source, and wherein a supply of air from the air source is communicated to the heat source and heated to a temperature before being discharged from the exit end toward the container area.
Other features and advantages of the invention will be apparent from the following specification taken in conjunction with the following drawings.
In order to better describe the features of the present invention, a number of drawing figures are appended hereto in which:
While this invention is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail a preferred embodiment of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiment illustrated.
Referring generally to the appended
As shown in
As the individual containers proceed along the supply line they are engaged on a screw assembly (12). At the screw assembly (12) a supply of air is heated in a heat source such as a heater (14) to a desired temperature. Preferably, the temperature of an individual container during the lip rolling is within the range of from about 400° to about 1200° F., more preferably within the range of from about 550° to about 600° F. However, the actual temperature of the container rim area will depend on the material thickness.
The supply of heated air is discharged toward the containers (C), particularly the rim of the container, as they are engaged on the screw assembly, and the lips of the containers (C) are then rolled in the screw assembly (12). The rolling process once engaged by the screw assembly (12), generally speaking, is not unlike that known by those skilled in the art. That is, the heated lip is rolled under the rim by engaging the toothed turns of the screw curling (16).
Air may be supplied to the heater (14) by an air blower (18), as shown in
The screw assembly (12) may be prevented from operating until the supply of air reaches the desired temperature. This is possible by making the screw assembly (12) responsive to any number of sensors (not shown) monitoring parameters such as temperature, line speed, production errors, or the like, using a controller (20). For example, should a sensor detect the absence of containers in the feed line, the screw assembly could cease operation thereby reducing wear-and-tear on the system. The present embodiment utilizes a 480 volt (30 amp) 3-phase controller manufactured by Avatar (Model No. A3P-48-30).
Typically, the screw assembly (12) will include a plurality of screw curlings (16), as many as five, but may be a single screw curling (16) for some operations. Three equidistantly-spaced screw curlings (16) is the preferred arrangement, as shown in
In order to direct the nested stack of containers (C) to the screw assembly (12), a crowd brush (22) is used in the present embodiment. The crowd brush (22), as shown in FIGS. 3 and 4, turns such that the extending nylon bristles (24) contact the containers and impart lateral motion to the individual containers keeping them fully nested together.
As the containers (C) encounter the screw curlings (16) a heat source (14), such as a forced air heater, discharges a supply of heated air at the containers in the container area (A) proximate the screw curlings (16). The concentrated air supply is preferably directed at the container rim.
The concentrated heat at the screw assembly (12) provides a number of benefits in the present invention. First, it allows the use of thinner material at the container rim. Potentially, as much as a 50% reduction in material thickness at the rim, or within the range of from about 0.030 to about 0.015 inches on a small cup—the thickness, being a function of the cup size, will increase accordingly. Such thin materialed containers used on prior art lip rolling devices which heat the container for a longer duration in a clamshell oven (70), as shown in
Second, the concentrated heat supply allows heating to be limited to the rim area of the container. Prior art devices would heat the entire container, which could result in an unstable container base, as well as system components, such as guide rails (90). To offset such indiscriminate and extensive heating, water is run through the guide rails (90) used within the clamshell oven (70). The present invention avoids the added complexity of these water-filled guide rails.
Another benefit of the concentrated heat supply relates to spinning of the container. Turning the container is the only way to provide even heating in the prior art clamshell oven (70). Crowd rollers (80) positioned at the entrance of prior art ovens (and friction) are used to spin the containers, adding more to the complexity of the prior art. Further, because the duration for each cup within the oven is substantial, the friction-induced spinning leaves a “contact line” on the outer surface of each nested container. The line can be a detraction from the container's aesthetics. By contrast, the present invention needs no crowd rollers and utilizes the screw curling (16) to turn individual containers while each is being heated. The duration of spinning for each container is significantly reduced, eliminating the occurrence of the “contact line” on the outer surface.
As a safety measure—one not present in the prior art—the heater (14) is preferably attached or otherwise affixed to a reciprocating mechanism (26). Such a mechanism (26), a pneumatic, electric, or hydraulic cylinder, for example, would allow the heater (14) to be moved to any number of positions along a shaft or rod (28). One such position would be proximate the nested stack of containers, as shown in
In the event of a malfunction or production stoppage, the heater (14) could be moved to a position distant from the nested stack of containers. Immediately the source of heat is removed from the thermoplastic containers, greatly reducing the frequency of melted containers and, in severe cases, fire. Both are common occurrences with the clamshell arrangement.
The step of moving the heater (14) to and from a position proximate to the nested stack of containers (C) can be accomplished by a variety of means. As mentioned above, by mounting the heater (14) to a movable mechanism (e.g., a cylinder or the like), actuation of the mechanism can be used to appropriately place the heater (14). Basically, there are two positions: an initial position (1) proximate the stack of containers (C) and a safety position (S) away from the stack of containers (C).
Actuation of the heater (14)—i.e., movement to and from either of the two positions (I) or (S)—can be triggered by a temperature reading, an operation condition (e.g., production stoppage), operator override, or the like. Sensors, or other known devices, may be placed about the present invention to detect the desired condition. For example, a temperature sensor (30) may be used to detect a temperature threshold of the heated air expelled from the heater (14). A temperature outside a desired range would result in the actuation of the cylinder (32) in response to a signal generated in response to the sensor (30) moving the heater (14) to the safety position (S), as shown in
Alternatively, or in addition to the actuation of the heater (14) for safety, it is possible to provide a mechanism for deflecting or diverting the supply of heated air from the containers (C) in response to similar signals. One such means for diverting the supply of heated air may include an adjustable plenum, a close-able duct, a deflection plate, or the like.
Referring again to
With reference to
The screw curlings (16) and the chrome rollers (17) are positionally fixed about an opening (34) through which the containers are passed as their lips are rolled. That is, the curlings (16) and rollers (17) are preferably not adjustable for different container sizes. Rather, the curlings (16) and rollers (17) are fixed to a plate (36), as illustrated in
While the specific embodiment has been illustrated and described, numerous modifications come to mind without significantly departing from the spirit of the invention, and the scope of protection is only limited by the scope of the accompanying Claims.
The present application is a divisional application which, under 35 U.S.C. §121, claims the benefit of U.S. patent application Ser. No. 09/966,996, filed on Sep. 28, 2001, and now U.S. Pat. No. 6,719,552, issued Apr. 13, 2004.
| Number | Name | Date | Kind |
|---|---|---|---|
| 3363283 | Weber | Jan 1968 | A |
| 3914102 | Brown | Oct 1975 | A |
| 4235579 | Kurz et al. | Nov 1980 | A |
| 4391768 | Arends et al. | Jul 1983 | A |
| 4566923 | Mueller | Jan 1986 | A |
| 5118277 | Padovani | Jun 1992 | A |
| 5324249 | Konzal | Jun 1994 | A |
| 6093010 | Lamson | Jul 2000 | A |
| 6129537 | Merz | Oct 2000 | A |
| 6135754 | Lamson | Oct 2000 | A |
| 6135756 | Arends | Oct 2000 | A |
| 6164949 | Lamson | Dec 2000 | A |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 09966996 | Sep 2001 | US |
| Child | 10681465 | US |
