Abstract:
An earplug arrangement enables low cost manufacture and storage of earplugs and convenient dispensing of individual earplugs. The earplugs are formed from an extrusion of a maximum diameter of about 12 mm and with narrow locations spaced apart by about 1 to 5 cm to separate the extrusion into a chain of at least ten earplugs, where the last earplug of the chain of earplugs formed by the extrusion can be cut from the rest of the chain for insertion into a person&#39;s ear canal. The chain of earplugs is stored in a plurality of loops in a container, as in a plurality of loops wrapped about a cylinder. The extrusion can include a stiffening core of stiff first material and an extruded covering of a soft resilient foam second material surrounding the core, the thickness of the second material being less than half as great at the narrowed locations as at maximum diameter locations while the core is of uniform cross-section along the entire length of the extrusion.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    Applicant claims priority from Provisional patent applications 60/311,440, 60/311,441, and 60/311,610, all filed Aug. 10, 2001. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    Earplugs are commonly produced by punching a plug out of a plate of material or molding individual earplugs in individual molds. It is also possible to form earplugs by extruding material that is cut into earplugs. U.S. Pat. No. 5,753,015 describes feeding a small diameter core of round cross-section through an extrusion head while resilient foam material is extruded around the core, to provide a continuous extrusion. As the extrusion cools, it is cut into discrete pieces of about 25 mm length to thereby form individual earplugs. Patent publication WO 02/26465 describes extruding foamable material that will form a slow recovery foam, through an extrusion head, and using a knife blade to cut the extrusion whenever it projects by about 25 mm from the extrusion head, to thereby form individual earplugs. In both cases, the individual earplugs resulting from cutting the extrusion as it emerges from the extrusion head, must be packaged. Earplugs which were very easily packaged and withdrawn from the packaging would be of value.  
         SUMMARY OF THE INVENTION  
         [0003]    In accordance with one embodiment of the present invention, an earplug arrangement and method for forming it are provided, which enables low cost production, storage, shipping, and dispensing. The earplug arrangement includes multiple earplugs connected in series to form a chain of earplugs. The chain of earplugs is formed by an extrusion of foamable material which is stored in a plurality of loops, with individual earplugs obtained by severing the last earplug in the chain from the rest of the chain. During extrusion, locations of minimum diameter are formed at uniform spacings of about 1 cm to 5 cm to define the opposite ends of earplugs. This facilitates bending of the chain to store it in loops or turns, and facilitates severing of the last earplug from the chain.  
           [0004]    In one arrangement, the chain include a core of elastomeric material which is at least twice as stiff as the material of the foam covering that was extruded around the core. The core resist column-like collapse when the earplug is pressed into the ear canal. The core also holds the chain together and allows the ends of the earplugs to be of a small diameter less than one-fourth the maximum diameter along the extrusion, to more clearly define the individual earplugs and facilitate cutting of earplugs from the chain.  
           [0005]    The novel features of the invention are set forth with particularity in the appended claims. The invention will be best understood from the following description when read in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    [0006]FIG. 1 is a partial sectional side elevation view showing a process and equipment for producing a chain of earplugs and also showing a portion of such chain of earplugs, where the chain comprises a single material.  
         [0007]    [0007]FIG. 2 is a side elevation view of one earplug of the chain of FIG. 1, after it has been cut from the chain.  
         [0008]    [0008]FIG. 3 is a front elevation view of compressing apparatus of FIG. 1, taken on line  3 - 3  thereof.  
         [0009]    [0009]FIG. 4 is a sectional side view of a method and equipment for generating a chain of earplugs of another embodiment of the invention, with a core of material that is stiffer than the extruded covering lying around the core, and showing a portion of the chain of earplugs.  
         [0010]    [0010]FIG. 5 is a side elevation view of one of the earplugs of the chain of FIG. 4, after it has been cut from the chain.  
         [0011]    [0011]FIG. 6 is a sectional view taken on line  6 - 6  of FIG. 5.  
         [0012]    [0012]FIG. 7 is a sectional side view showing a method and equipment for producing a chain of earplugs of another embodiment of the invention, and showing a portion of the chain of earplugs.  
         [0013]    [0013]FIG. 8 is a side elevation view showing one of the earplugs of the chain of FIG. 7 after it has been severed from the chain.  
         [0014]    [0014]FIG. 9 is a sectional view taken on line  9 - 9  of FIG. 8.  
         [0015]    [0015]FIG. 10 is a partially sectional isometric view showing a holder for holding a chain of earplugs and dispensing them.  
         [0016]    [0016]FIG. 11 is a sectional view of a portion of the holder of FIG. 10.  
         [0017]    [0017]FIG. 12 is a partially sectional isometric view of a holder of another embodiment of the invention, with a chain of earplugs therein.  
         [0018]    [0018]FIG. 13 is an isometric view of a chain of earplugs stored in zig-zag loops.  
         [0019]    [0019]FIG. 14 is a partially sectional side elevation view showing a method and equipment for constructing a chain of earplugs of another embodiment of the invention, and showing a portion of the chain, wherein only the front ends of the earplugs are rounded. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]    [0020]FIG. 1 illustrates an extrusion head  10  with an opening  12  through which flowable polymer material  14  is extruded. The polymer material  14  is a foamable material, and after passing out through the opening  12 , the material expands in diameter as it foams, until it reaches a maximum diameter D and solidifies to become a resilient solid foam  16 . The diameter D is about 12 mm so it can fit snugly into a person&#39;s ear canal and block sound. Accordingly, the extrusion  18  is constructed so it can be cut into individual earplugs.  
         [0021]    In accordance with the present invention, applicant does not cut the earplugs as they emerge or soon after they emerge from the extrusion head  10 , but instead leaves a long extrusion  18  which forms a chain of earplugs  19  for easier storage and dispensing. A compressor  20  is located close to the extrusion head  10  to pinch the extrusion emerging from the opening  12 . This leaves locations  22  of minimum diameter E at spacings S of between about 1 cm and 5 cm so individual earplugs  24  between adjacent locations  22  are long enough to be easily inserted into the ear canal and pulled out without excessive waste of material. The compression occurs close to the extrusion head before the extruded material has fully solidified (preferably within 5 cm of the extrusion head), and the compressor does not heat the extrusion.  
         [0022]    [0022]FIG. 3 shows one form of compressor  20 , which includes four compressor elements or dies  31 - 34  and actuators  36  for moving the compressor elements simultaneously close together toward the extrusion axis  37  to compress the extrusion and then away from the extrusion. This results in the locations  22  of small diameter. The particular compressor elements have sides  38  that abut one another. It is also possible to have compressor elements that overlap one another. The compressor  20  is preferably located close to the extrusion head, where the foamable material has not foamed to its full diameter D. As a result, foamable material on either side of the compression location continues to foam and grow so as result in each earplug  24  having rounded ends  40 . The particular foam material  16  is preferably a slow recovery foam material, which can be rolled to a small diameter and inserted into the ear canal, and which resiliently expands over a period such as thirty seconds to fill the ear canal and block it. If a resilient foam of the rapid recovery type, which recovers to its full diameter within one second, is used, then earplugs of such material are difficult to insert into the ear canal unless means are provided to prevent column-like collapse.  
         [0023]    [0023]FIG. 2 illustrates one earplug  24  which results from a pair of cuts at two locations  22  of the chain of FIG. 1. The earplug has rounded ends  40  and has a small protuberance or nipple  44  at each of its rounded ends where it was cut. The earplugs are not cut from the chain until at least one hour, and usually at least one day, after the extrusion is formed when the chain is of room temperature.  
         [0024]    [0024]FIG. 4 shows a system  50  for producing an extrusion  52  that forms a chain of earplugs  54  of another embodiment of the invention. As a foamable and flowable material  60  is extruded through an opening  62  of the extrusion head  64 , a core  70  of elastomeric material at least twice as stiff as the foam is fed through the extrusion opening  62 . The result is the extrusion  52  that includes the core  70  and a covering  72  of resilient polymer foam, the foam material preferably being a fast recovery foam rather than a slow recovery foam. A compressor  74  similar to the compressor  20  of FIG. 3 is provided to create locations of small diameter that are spaced apart by about 1 to 5 cm, and where the extrusion later can be cut to form individual earplugs. The compressor  74  preferably compresses the foamable material to substantially eliminate it at the location  76 , so the location  76  consist of only the core  70 . In practice, a small amount of the covering material lies around the core at the locations  76 . The narrow locations facilitate cutting of earplugs from the chain, and make the chain easy to bend into loops, to turns for storage.  
         [0025]    [0025]FIG. 5 illustrates one of the earplugs  80  which has been cut from the chain  54  of earplugs of FIG. 4. The earplug has rounded ends  82 , except for nipples  84  where the chain was cut at the narrow location  76 . FIG. 6 shows that the diameter K of the core  70  is less than half and preferably less than one-quarter the diameter J of the covering. The core  70  is highly useful to prevent column-like collapse as one end, referred to as the front end of the earplug, begins to enter the ear canal as the opposite rear end is pressed forwardly. Without the core  70 , it is very difficult to install a resilient foam earplug into the ear canal. In FIG. 6 the core diameter K is about 2 mm, which is no more than one-fourth the earplug maximum diameter D of about 12 mm.  
         [0026]    [0026]FIG. 7 illustrates a system  100  of another embodiment of the invention, which is similar to that of FIG. 4, except that a core  102  is provided which is in the form of a sleeve. As shown in FIG. 9, the sleeve-shaped core  102  has a gap  104 , which is preferably no more than 90°, which allows covering material  110  of resilient fast-recovery foam to flow into the inside of the sleeve  102  to fill it. A compressor  72  similar to compressor  20  of FIG. 3, compresses the covering  110  of resilient foam that surrounds the sleeve  102 , at intervals spaced about 1 cm to 5 cm apart. This leaves locations  112  where the chain of earplugs  114  can be bent to form into a loop, where an earplug can be easily severed form the chain, and where the ends  116  of the earplugs are rounded. FIG. 8 shows one of the earplugs  120  of the diameter D, with protrusions or nipples  122  at its opposite ends. FIG. 9 shows that the diameter P of the sleeve is about 3 mm which is less than half and no more than about one-fourth the maximum diameter Q of the earplug.  
         [0027]    [0027]FIG. 14 illustrates a modified apparatus  130  with a compressor  72  adjacent to the extrusion head  132 , and another compressor  134  spaced from the extrusion head. The compressor  72  forms earplug rounded front ends  140  that enter the ear canal, and locations  142  of reduced diameter where the earplugs can be cut. The other compressor  134  is spaced from the extrusion head  132  and forms the rear ends of the earplugs so they are less rounded, but have narrow locations  152  where the earplugs can be severed. The chain of earplugs  152  has alternate minimum diameter locations  142 ,  152  that are different.  
         [0028]    [0028]FIG. 10 illustrates a chain of earplugs  160  in a holder  162  which includes a cylindrical drum  164  and a box  166  that surrounds the drum. The drum is rotatably mounted on the box so it can be turned to move the end of the chain at the last earplug  170  of the chain, out through a dispenser opening  172 . A cutter  174  which has a blade operated by depressing a handle, cuts earplugs from the end of the chain. The chain of earplugs extends in a plurality of loops, or turns of 360 degrees about the drum axis  176 , with considerable bending occurring at the narrowed locations of the chain. The chain of earplugs has a length of at least 50 cm and preferably at least 100 cm, to contain at least ten earplugs and preferably at least 20 earplugs (and more preferably at least 100 earplugs). Each of the turns extending around the drum contains at least five earplugs.  
         [0029]    [0029]FIG. 11 shows one example of a cutter  180 . The cutter includes a pair of blades  182 ,  184 . A handle  186  can be depressed to move the blade  182  beyond the axis  190  of the chain of earplug  192 . A mechanism (not shown) moves the other blade  184  simultaneously in the opposite direction across the first blade  182  to shear an earplug between them. A pair of advancing wheels  192 ,  194  advance the chain of earplugs.  
         [0030]    [0030]FIG. 12 shows another holder  200  which includes a stationary centerpiece  204  that is preferably in the form of a cylinder or partial cone, and with a chain of earplugs  206  wrapped in a plurality of turns about the centerpiece. A box  210  surrounds the chain of earplugs, and has an opening  212  through which an end portion  214  of the chain can extend. A retainer  216  retains the ends of the chain, and the last earplug  220  of the chain can be cut off at the retainer  216 .  
         [0031]    [0031]FIG. 13 shows still another arrangement, where a chain of earplugs  230  is stored in back-and-forth loops such as  232 ,  234 , each of which may be considered to be a complete turn.  
         [0032]    Thus, the invention provides earplugs that can be manufactured and stored in a low cost and efficient manner, and a method for constructing the earplugs. The earplugs are formed as an extrusion of about 12 mm diameter to fit snugly in a human ear canal, and can be stored as by wrapping it in a plurality of loops or turns, and with individual earplugs being dispensed by cutting a length of about 1 cm to 5 cm from the extrusion. The extrusion preferably is formed with locations of reduced diameter spaced by between about 1 cm and 5 cm apart, where the extrusion can be readily cut and which provides increased flexibility to the chain to bend it into a turn. The extrusion is preferably formed by compressing it to form the narrow locations, with the compression occurring close to the extrusion head where the foamable material has not yet completely foamed so ends of the earplugs continue to foam and form rounded ends. It is possible to provide a chain of earplugs without narrowed locations, but at least 50 cm long so it can be cut into at least 10 earplugs. The extrusion can include a core which is a solid core or sleeve (a sleeve preferably has a gap) to stiffen the earplug, and with the thickness of resilient foam covering material that surrounds the core having a reduced thickness less than one-quarter maximum thickness at the locations of minimum diameter. It is possible to have slight compressions between opposite ends of the earplug to stiffen it.  
         [0033]    Although particular embodiments of the invention have been described and illustrated herein, it is recognized that modifications and variations may readily occur to those skilled in the art, and consequently, it is intended that the claims be interpreted to cover such modifications and equivalents.