Abstract:
The present invention relates to a method of reforming an upper portion of a blow molded plastic container. The method comprising the steps of directing energy from a non-contact heater onto the upper portion to soften the upper portion, and compressing the upper portion between at least a first forming tool and a second forming tool to reform the upper portion. A plastic container, as well as an apparatus for reforming an upper portion of a blow molded plastic container, are also disclosed.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates generally to plastic containers. More specifically, the present invention relates to methods and apparatuses for reforming the upper portion of a plastic container, and particularly, a blow molded plastic container.  
         [0003]     2. Related Art  
         [0004]     Capping processes for plastic containers typically require the upper portion of the container, such as the neck finish, to meet exacting dimensional tolerances. To achieve the necessary tolerances, the upper portions of containers are typically produced using injection molding processes, for example, by injection blow molding the containers. However, injection blow molding processes are at a significant output-to-cavity disadvantage when compared to other types of blow molding, such as extrusion blow molding. In addition, injection blow molding often requires expensive injection manifolds and involves sensitive injection processes.  
         [0005]     According to another method of making containers, a preform with a pre-configured upper portion (e.g., neck finish) is made by injection molding. Subsequently, a container is blow molded from the lower portion of the preform. However, the upper portion can become distorted during blow molding due to the heat applied to the preform. This can cause the pre-configured upper portion to fall out of tolerance.  
         [0006]     Furthermore, in order to achieve desirable tolerance levels using conventional extrusion blow molding technology, the containers typically have to undergo some type of cutting, stamping, and/or trimming operation. However, these operations have not proven to be reliable for producing the required dimensional tolerances.  
         [0007]     Therefore, there remains a need in the art for improved methods, apparatuses, and containers that overcome the shortcomings of conventional solutions.  
       BRIEF SUMMARY OF THE INVENTION  
       [0008]     According to one exemplary embodiment, the present invention relates to a method of reforming an upper portion of a blow molded plastic container. The method comprising the steps of directing energy from a non-contact heater onto the upper portion to soften the upper portion, and compressing the upper portion between at least a first forming tool and a second forming tool to reform the upper portion.  
         [0009]     According to another exemplary embodiment, the present invention relates to a blow molded plastic container having a upper portion with a flange reformed in accordance with the aforementioned method.  
         [0010]     According to yet another exemplary embodiment, the present invention relates to an apparatus for reforming an upper portion of a blow molded plastic container. The apparatus comprises a non-contact heat source adapted to heat the upper portion of the plastic container, and first and second reforming tools spaced apart from the heat source. The first and second reforming tools are adapted to compress the heated upper portion between the first and second reforming tools to reform the upper portion.  
         [0011]     Further objectives and advantages, as well as the structure and function of preferred embodiments will become apparent from a consideration of the description, drawings, and examples. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     The foregoing and other features and advantages of the invention will be apparent from the following, more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawings wherein like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements.  
         [0013]      FIG. 1  is a schematic representation of the step of heating an upper portion of a container according to an exemplary embodiment of the present invention;  
         [0014]      FIG. 2  is a schematic representation of the step of compressing the upper portion of the container between two forming tools according to an exemplary embodiment of the present invention;  
         [0015]      FIG. 3  is an enlarged fragmentary view of the portion of  FIG. 2  within the area A, prior to completion of the compressing step;  
         [0016]      FIG. 4  is an enlarged fragmentary view of the portion of  FIG. 2  within the area A, upon completion of the compressing step; and  
         [0017]      FIG. 5  is side view of a plastic container according to an exemplary embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]     Embodiments of the invention are discussed in detail below. In describing embodiments, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology so selected. While specific exemplary embodiments are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations can be used without departing from the spirit and scope of the invention. All references cited herein are incorporated by reference as if each had been individually incorporated.  
         [0019]      FIGS. 1-4  depict an exemplary method and apparatus according to the present invention. Referring to  FIG. 1 , plastic container  200  includes an upper portion  202 . In the exemplary embodiment shown, plastic container  200  is in the shape of a bowl, for example, a soup bowl, and the upper portion  202  includes a substantially annular, outwardly-extending flange  204 . Flange  204  can be adapted and configured to receive a closure, such as a metal lid, a layer of film (e.g., thermo-sealed or glued film), a snap-on lid, or a double-seam metal lid, although other configurations are possible. One of ordinary skill in the art will know and appreciate that plastic container  200  and/or upper portion  202  can take other forms. For example, plastic container  200  may alternatively be a beverage container, and upper portion  202  may alternatively include a threaded neck finish, or feature other geometries for sealing applications.  
         [0020]     The upper portion  202  is typically formed during the blow molding of container  200 , for example, during extrusion blow molding. The upper portion  202  may additionally or alternatively be formed, or modified, during a trimming or other operation that takes place, for example, after the container is blow molded. Alternatively, the upper portion  202  may be formed in connection with an injection or compression molding process, for example, on containers made using a reheat blow molding process or an injection/extrusion/blow molding process. Alternatively, the upper portion  202  may be formed in connection with an injection molded preform, in which the upper portion  202  is preconfigured during injection molding of the preform.  
         [0021]     The present invention provides a method and apparatus that reforms the upper portion  202 , for example, to provide the shape and dimensional tolerances required for the capping and/or sealing process. The method includes softening the upper portion  202 , for example, by heating it with a non-contact heater  206 . By “non-contact” is meant that the energy from non-contact heater is transferred to the upper portion  202  by radiation, convection, or other methods that don&#39;t involve physical contact with the upper portion  202 . Heater  206  can comprise an infrared heater, a radiant heater, a quartz lamp, focused light energy, or a heated forming tool. One of ordinary skill in the art will know and appreciate that other “non-contact” techniques are available for softening upper portion  202 . For example, energy from a laser or other focused light may be used to soften upper portion  202 . Heater  206  may be adapted and configured to focus the heating energy onto the upper portion  202 , for example, to heat flange  204  to its softening temperature, while leaving the remainder of container  200  relatively unheated.  
         [0022]     Once the upper portion  202  of container  200  is softened, two or more forming tools can be used to reform the upper portion  202 . Referring to the exemplary embodiment of  FIG. 2 , a first forming tool  207  and a second forming tool  208  can be used to reform the upper portion  202 , and more specifically, the flange  204 . According to one exemplary embodiment, the first and second forming tools  207 ,  208  are constructed of metal, such as bronze, stainless steel, or aluminum, although other materials can alternatively be used.  
         [0023]     In the exemplary embodiment shown in  FIG. 2 , the forming tools  207 ,  208  are substantially opposed to one another, and can be moved from the position shown in  FIGS. 2 and 3  to the position shown in  FIG. 4 , thereby compressing and reforming the upper portion  202 . When in the position shown in  FIG. 4  (i.e., the “closed position”), the first forming tool  207  and the second forming tool  208  mate to define a cavity  210  in which the upper portion  202  (e.g., the flange  204 ) is reformed to the desired shape and size. The first and second forming tools  207 ,  208  can include cooperating surfaces that engage one another (when the forming tools are in the closed position) to orient the forming tools  207 ,  208  with respect to one another and to maintain the cavity  210  at the intended shape and size. For example, first forming tool  207  can include a first engagement surface  212  and second forming tool  208  can include a corresponding second engagement surface  214 . The amount of pressure applied by the first and/or second forming tools  207 ,  208  to move them to the closed position shown in  FIG. 4 , and the amount of time the forming tools  207 ,  208  are held in the closed position, can be adjusted empirically to obtain the desired geometrical, dimensional, and surface finish characteristics for the upper portion  202 . A spring and cam system can be used to control the movement and pressure of the first and second forming tools  207 ,  208 . Alternatively, hydraulic or pneumatic means can be used to control the forming tools.  
         [0024]     Still referring to  FIGS. 2-4 , the first forming tool  207  can extend around the periphery of the upper portion  202 . For example, first forming tool  207  can comprise a ring-shaped portion have an aperture corresponding in shape and size (e.g., diameter) to the upper portion  202  of container  200 , allowing the container  200  to extend therethrough. According to an alternative embodiment, first forming tool  207  can have a recess or depression that corresponds in shape and size of the entire container  200 . As shown in  FIGS. 2-4 , the second forming tool  208  can approach the container  200  from above, and compress the upper portion  202  downward and against the first forming tool  207 , although other configurations of the first and second forming tools  207 ,  208  are possible.  
         [0025]     While the exemplary embodiment of  FIGS. 2-4  shows two forming tools, one of ordinary skill in the art will know and appreciate that in some situations, it may be preferable to use more than two forming tools, for example, depending on the shape, size, and configuration of the container  200  and/or upper portion  202 .  
         [0026]     According to an exemplary embodiment of the invention, one or both of the forming tools  207 ,  208  can be substantially unheated. For example, the forming tools  207 ,  208  may be kept at room temperature (ignoring the heating effects due to contact with the upper portion  202 ). Accordingly, when the heated upper portion  202  contacts the forming tools  207 ,  208 , the relatively cool forming tools  207 ,  208  cause the upper portion  202  to cool and solidify. Thus, compressing the softened upper portion  202  with the relatively cool forming tools  207 ,  208  reforms, cools, and solidifies the upper portion  202  (e.g., the flange  204 ), resulting in a reformed upper portion  202  having a smooth surface finish, as well as high geometrical and dimensional tolerances. Air vents, channels, or similar cooling structures can be provided in one or both of the forming tools  207 ,  208  to help maintain the forming tools  207 ,  208  at or near room temperature. Additionally or alternatively, coolant can be pumped through channels in one or both of the forming tools  207 ,  208  to actively cool the forming tools  207 ,  208  to desired temperature. For example, one of ordinary skill in the art will know and appreciate that a pump can be used to circulate a coolant, such as a water/glycol mixture, through a cooling system and into channels in the forming tools  207 ,  208 , although other configurations are possible and contemplated.  
         [0027]     The container of the present invention can be made of monolayer plastic construction, or alternatively, of multilayer plastic construction. In the case of a container of multilayer plastic construction, intermediate layers may or may not extend into the upper portion of the container. For polypropylene, it has been found that the softening temperature is in the range of about 220 to 320° F., preferably about 275 to 315° F., and more preferably about 300° F. According to one exemplary embodiment, the surfaces of the forming tools that contact the upper portion of the container are maintained at a temperature of less than 100° F.  
         [0028]     Referring to  FIG. 5 , a plastic container  200  having an upper portion  202  reformed in accordance with the present invention is shown. As shown in  FIG. 5 , the upper portion  202  exhibits high geometrical and dimensional tolerances, such as the thickness T, width W, and outer diameter D of the flange  204 . The reforming method of the present invention can facilitate use of high-output blow molding processes (e.g., continuous extrusion blow molding) to produce the container, while obtaining the high geometrical and dimensional tolerances for the upper portion  202  typical of lower output processes such as injection blow molding. The reforming method can also facilitate the production of multi-layer containers, due to the robust layer formation associated with the continuous extrusion blow molding process.  
         [0029]     The embodiments illustrated and discussed in this specification are intended only to teach those skilled in the art the best way known to the inventors to make and use the invention. Nothing in this specification should be considered as limiting the scope of the present invention. All examples presented are representative and non-limiting. The above-described embodiments of the invention may be modified or varied, without departing from the invention, as appreciated by those skilled in the art in light of the above teachings. It is therefore to be understood that, within the scope of the claims and their equivalents, the invention may be practiced otherwise than as specifically described.