Abstract:
A method for shaping an aerosol container ( 10 ) to a desired body contour. A container body ( 12 ) is formed into a cylindrical shape and installed into a mold ( 30 ) whose inner surface defines the desired body contour. A bladder ( 74 ) is fitted onto a tool ( 50 ) insertable into an open end (M) of the container body. Once the tool is inserted, the bladder is inflated with a hydraulic fluid. Pressurizing the bladder forces the bladder against a sidewall of the body forcing the body outwardly and deforming it against the inside of the mold. After the container body is shaped, the bladder is de-pressurized and the tool withdrawn leaving the container with a defined body contour. The hydraulic fluid with which the bladder is pressurized is, at all times, contained within the bladder and does not contact the container sidewall so no subsequent drying of the container is required after the shaping process is complete.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     None  
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002]     N/A  
       BACKGROUND OF THE INVENTION  
       [0003]     This invention relates to shaped metal containers and the like, and more particularly, to hydraulic shaping of such cans.  
         [0004]     Aerosol containers are used to store a fluid or fluent material under pressure and to release the material, as a spray, foam, or gel when a valve is activated. The containers are formed from flat sheets of material which are first cut into rectangular shapes. The resulting blanks are then formed into a cylinder which is open at one end. The container is then filled with the material to be dispensed by the container. A valve assembly is attached to the upper, open end of the container. The contents of the container are subsequently released through a dispensing valve operable by the user of the container.  
         [0005]     Current manufacturing processes for aerosol containers have certain drawbacks. A major one is that during fabrication, as the can is being shaped so to have a desired external contour, fluid used in the shaping process comes into contact with the inside of the can. This necessitates a subsequent drying step after can forming is complete so the fluid does not, over time, corrode the sidewall of the can and cause it to deteriorate or fail. The drying operation is performed by heating the container to a temperature sufficient to dry off any fluid adhering to the container after the shaping operation. While this is not a particularly complicated process, it does add manufacturing time and cost to the container.  
       BRIEF SUMMARY OF THE INVENTION  
       [0006]     The present invention is directed to a method of shaping aerosol containers. A method of the invention uses a hydraulic shaping technique in which hydraulic fluids do not come into direct contact with the container thereby eliminating a subsequent drying step in the manufacturing process. Use of this “dry” process thereby reduces the number of manufacturing steps required to produce a can, decreases production time, increases the throughput of containers, and decreases manufacturing costs.  
         [0007]     In accordance with the invention, a blank is formed into a cylindrical can body shape, and a dome shaped base is crimped to the bottom of the body. The partially assembled can is now directed to a shaping station where it is installed between a pair of mold halves which define the final contour of the body. A bladder is mounted onto a tool and lowered into the container through an open, mouth end of the container. When the bottom of the tool is seated against the base of the container, a hydraulic fluid is injected into the bladder causing the bladder to expand outwardly against the sidewall of the body. Continued pressurization of the bladder causes continued expansion of the bladder and forces the container sidewall against the inner face of the mold. The pressure causes the container sidewall to distort into the contour shape defined by the inner surface of the mold. Once the container fully conforms to the desired shape, the fluid is evacuated from the container leaving the container body conformed to the desired shape determined by the mold. The tool is then withdrawn. During the forming process, no fluid contacts an interior surface of the container thereby eliminating the need for a subsequent drying operation.  
         [0008]     Other objects and features will be in part apparent and in part pointed out hereinafter.  
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0009]     The objects of the invention are achieved as set forth in the illustrative embodiments shown in the drawings which form a part of the specification.  
         [0010]      FIG. 1  is an elevation view, partly in section, of an aerosol container having a container body shaped to a desired body contour;  
         [0011]      FIG. 2  is an elevation view, partly in section, of a tool used to position a bladder in the container for use in shaping the container body to the desired contour;  
         [0012]      FIGS. 3-6  illustrate the “dry” contour shaping process of the invention; and,  
         [0013]      FIG. 7  is a perspective view of one-half of a multi-cavity mold for producing containers with contoured bodies. 
     
    
       [0014]     Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.  
       DETAILED DESCRIPTION OF INVENTION  
       [0015]     The following detailed description illustrates the invention by way of example and not by way of limitation. This description will clearly enable one skilled in the art to make and use the invention, and describes several embodiments, adaptations, variations, alternatives and uses of the invention, including what I presently believe is the best mode of carrying out the invention. As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.  
         [0016]     Referring to the drawings, a container such as aerosol dispensing container is indicated generally  10 . The container comprises a body  12  initially formed from a blank, as is well-known in the art, and a dome shaped base  14  to which the lower end of the can body is crimped, again as is well-known in the art. Container body  12  is generally cylindrically shaped and initially open at both ends.  
         [0017]     The container is a shaped container. As shown in  FIG. 1 , a central portion of the body has a decreased diameter section  16 . As described hereinafter, the can body is shaped during a portion of the manufacturing process. The particular shaping shown in  FIG. 1  is exemplary only, and those skilled in the art will understand that other desired shapes can be realized in accordance with the present invention. A valve assembly  20  is attached to the top, open mouth end of the container. The container shown in  FIG. 1  is a 3-piece container. It will be understood by those skilled in the art that the can shaping process described herein can also be used with 2-piece containers without departing from the scope of the invention.  
         [0018]     Once a desired container body contour has been decided upon, a mold  30  is made to produce the contour during the manufacturing process. Mold  30  is a multi-piece mold comprising mold halves  30   a  and  30   b , and a mold base  32 . When the three pieces of the mold are brought together, they create a cavity C. Further, mold  30  is fabricated as a multi-cavity mold. As shown in  FIG. 7 , mold  30  is shown to be a four-cavity mold. It will be understood by those skilled in the art that the mold could have more, or fewer, cavities without departing from the scope of the invention. Each mold half  30   a  and  30   b  is mounted on a movable plate  36  (only mold half  30   a  being shown mounted to a plate  36  in  FIG. 7 ). The plates are, in turn, installed on rods  38  (three of which are shown in  FIG. 7 ) for reciprocal movement toward and away from each other. The inner surface  40   a  and  40   b  of the respective mold halves are formed to produce a desired contour of container  12  as is described hereinafter. As shown in the drawings, the respective mold halves each have identically formed inner surfaces so to form the contour shape shown for container  10  in  FIG. 1 . That is, a container with a reduced center section  16  intermediate upper and lower sections of a greater diameter. Again, those skilled in the art will appreciate that the shape shown in the drawings is exemplary only and that other contours could be realized by mold  30  within the scope of the invention.  
         [0019]     During the manufacturing process, a blank (not shown) is formed into a cylindrical body shape such as shown in  FIG. 3 . A dome shaped base  14  is then crimped to the bottom of container body  12 . The partially assembled can is now transported to a shaping station where the container is positioned between the mold haves such as shown in  FIG. 3 . As indicated by the arrows, once container  10  is in place, the two mold halves  30   a ,  30   b  are moved together to encircle the container. At the same time, mold base  32  is moved upwardly into position to seat against the bottom of dome shaped container base  14 . The upper dome shaped support surface  42  of base  32  is contoured to approximate the dome shape of base  14 . Finally, a tool  50  is lowered into container  10  from above the container.  
         [0020]     Referring to  FIG. 2 , a tool  50  includes upper and lower tool members  52 ,  54  respectively. Each member is circular in plan and has a central bore  56 ,  58  respectively for mounting the member on a threaded shaft  60 . The diameter of each member is less than that of the diameter of the mouth formed in the partially assembled container  10 , as shown in  FIG. 3 . This allows the tool to be readily inserted into container  10  through its mouth M.  
         [0021]     The position of lower member  54  is fixed on the lower end of shaft  60 , while the position of upper member  52  is adjustable. This allows tool  50  to be used with different size molds for containers of different lengths. Once the members are installed on shaft  60 , they are locked in place on the shaft using nuts  62 . The upper end of shaft  60  is adapted for connection to a mechanism  180  by which the tool is lowered into, and raised from, container  10  in a timed sequence controlled by a controller  200 .  
         [0022]     A sleeve  64  is sized to be mounted between upper and lower tool members  52 ,  54 . Each tool member has an inwardly extending shoulder  66 ,  68  respectively, whose width corresponds to the thickness of sleeve  64 . Accordingly, the upper and lower ends of the sleeve are seated on the respective shoulders with each end of the sleeve fitting over a reduced diameter shank portion  70 ,  72  of the respective tool members.  
         [0023]     An inflatable bladder  74  is stretched over the outside of sleeve  64 . The upper and lower ends of the bladder are over fitted over the top and bottom portions of the sleeve and extend along the inner surface of the sleeve a short distance. The sleeve/bladder assembly is sealed at each end by respective pairs of O-ring seals  76   a ,  76   b  and  78   a ,  78   b . The sleeve further has a series of spaced openings  80  formed therein for a hydraulic fluid pumped into the space defined by the sleeve and the upper and lower tool members to push against bladder  74  and force it outwardly against a sidewall of container body  12 . The number and locations of the openings shown in the drawings are illustrative only.  
         [0024]     The bladder is inflated by a hydraulic fluid pumped into the tool to pressurize the bladder. The fluid used for this purpose is a food grade type fluid which is pumped into the bladder and evacuated from the bladder using a pumping means  190  controlled by controller  200 . Tool member  52  has a vertical bore  82  extending from the bottom of the tool member upwardly into the member. Bore  82  extends parallel to bore  56 . A horizontal bore  84  extends inwardly into member  52  and intersects bore  82  at the upper end of the bore. A nipple  86  is fitted into bore  84  and connects to one end of a pressure hose  88  the other end of which connects to pumping means  190 .  
         [0025]     Referring to  FIGS. 3-6 , the sequence of operations for performing the “dry” shaping process of the invention first includes partially completed container  10  being transported to a manufacturing station where mold  30  and tool  50  are located. At this station, the mold halves  30   a ,  30   b  are brought together about the container body (as indicated by the arrows), and mold base  32  is elevated to contact and support the base of the container (as also indicated by an arrow). Simultaneously, tool  50  is lowered by mechanism  180  (as indicated by the arrow) into mouth M of the container until the bottom of lower tool member  54  contacts the bottom of the container. The resulting configuration is as now shown in  FIG. 4 .  
         [0026]     In  FIG. 4 , it will be noted that the sidewall of container body  12  contacts the inner surface of the mold halves throughout the center section  16  of the container body, but that the mold is formed so that its upper and lower segments are spaced away from the upper and lower sections of the container body. At this time, bladder  74  is unpressurized. Those skilled in the art will appreciate that  FIG. 4  is illustrative only, and that, depending upon the can shape desired, various sections of a container, will be in contact with, or spaced away from, the mold surfaces.  
         [0027]     Now, as shown in  FIG. 5 , controller  200  activates pumping means  190  to pump fluid into tool  50  to inflate the bladder. As the bladder is inflated, it expands uniformly outwardly pressing against the sidewall of container body  12  and pushing it outwardly against the inside surface of mold  30 . The upper and lower sections of the container body expand outwardly due to the force of the expanding bladder, but center section  16  of the body is constrained by the mold surface and cannot expand. The deformation of the upper and lower sections of body  12  against the mold create the desired container contour defined by mold  30 .  
         [0028]     After the bladder has been pressurized to a level sufficient that it expands enough to compress the container sidewall against the inside surface of mold  30 , controller  200  activates the pumping means to evacuate the hydraulic fluid from tool  50 , deflating the bladder so it draws inwardly against sleeve  64 . However, body  12  of container  10  remains in its deformed position  
         [0029]     Finally, as shown in  FIG. 6 , once bladder  74  is depressurized, controller  200  operates mechanism  180  to withdraw tool  50  out of the mouth of the container. Mold halves  30   a  and  30   b  now separate (as indicated by the arrows), and mold base  32  is withdrawn from the bottom of the container. Container  10  now has the desired body contour defined by the mold with upper and lower body sections which are greater in diameter than center section  16  of the container body. It is important to note that during the shaping operation, the hydraulic fluid with which bladder  74  is inflated is contained within the bladder at all times. None of the fluid comes into contact with the container sidewall, at any time, so no subsequent drying of the container is now required once the shaping process is complete.  
         [0030]     After the shaping step, the container is moved to a new station where valve  20  is connected to the mouth of the container by crimping, for example. Finally, the container is filled with fluent material dispensed by the container.  
         [0031]     In view of the above, it will be seen that the several objects and advantages of the present invention have been achieved and other advantageous results have been obtained.  
       SEQUENCE LISTING  
       [0032]     Not Applicable.