US 3445262 A
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Description (OCR text may contain errors)
May 20, 1969 GRECK ET AL METHOD FOR LINING CONTAINER CLOSURES Sheet of 2 Filed April 1. 1965 ywztinv- ATTORNEY May 20, 1969 GRECK ET AL METHOD FOR LINING CONTAINER CLOSURES Sheet 2 of 2 Filed April 1, 1965 a W aw United States Patent 3 445 262 METHOD FOR LlNINiG CONTAINER CLOSURES Eugene Greek, Westfield, and George Kokinda, Clark,
N.J., assignors to American Flange & Manufacturing Co. Inc., New York, N.Y., a corporation of Delaware Filed Apr. 1, 1965, Ser. No. 444,638 Int. Cl. B05b 7/16; B44d 1/02; B05c 9/14 US. Cl. 117-37 1 Claim ABSTRACT OF THE DISCLOSURE This invention relates to the gasketing of container closures and is particularly concerned with an improved method and apparatus for applying such gaskets in a semiliquid state and subsequently curing the same at an elevated temperature.
In the manufacture of container closures it has become the practice in the gasketing or lining operation to deposit within the closure a quantity of readily flowable semiliquid material which, upon subsequent curing at an elevated temperature, becomes a resilient gasket permanently adhered to the interior surface of the closure. It is generally known that success in achieving an effective container closure seal is in a large part attributable to the specific sealing relationship between the closure gasket and the container finish or sealing surface to which the closure is applied. This invention discloses a novel method, and a novel apparatus for carrying out that method for closely controlling, on a high speed production basis, the exact placement and configuration of the cured gasket within the finished closure so as to effect a uniform, pressure resistance seal.
As the practice of forming gaskets within the closure shells themselves is adapted to an ever wider variety of caps, covers, can ends and the like and particularly to much lighter weight closure members such as those formed of thin aluminum, the problem of accurately controlling the exact placement and form of gaskets which are applied under high speed production conditions becomes acute. Prior to its application to a closure the semiliquid gasket compound is stored in a jacketed reservoir which maintains the compound in a warm or preheated condition so as to insure proper metering and flowability of the compound into the closure. It has been found, according to this invention, that an improved gasket results when the compound is constantly maintained in this preheated condition until the very instant it is ejected from the lining nozzle or metering device onto the closure member. The closure members, having the uncured gasketing compound applied thereto, are kept relatively cool or at least free from the influence of any heat source until they are placed in a heated oven to cure the gasket compound. The reason for maintaining these temperature conditions is that, prior to the oven curing, any Warming elfect on the closure only causes the semiliquid gasket compound to run or slump along the surface to which it is applied. Any preliminary heating of the lined closure to a level which is less than the reaction temperature required to cure the gasket compound has a deleterious effect on the finished gasket formation.
In some prior art gasketing or lining arrangements the need for heating the metering device has been recognized ice and in fact infra-red heat lamps have been employed for this purpose. In these prior art arrangements the lined and uncured closure were then transferred from the metering station onto a heated conveyor belt which carried the closures through the baking or curing oven and then through a cooling chamber to facilitate immediate further handling of the finished product.
This invention provides a novel improvement over these prior art arrangements in disclosing a method of gasketing closures so as to effect greater control in handling the uncured gasketing compound and greater uniformity in the finished gasket configuration. The novel apparatus of this invention for carrying out this method comprises an improved localized heating means employed in conjunction with the compound metering device and an improved conveying apparatus for transferring the closures to the curing oven without significant preheating of the closures.
It is accordingly a principal object of this invention to provide a new and improved method for gasketing container closures.
Another object is to provide a novel apparatus for carrying out that method.
Another object is to provide an improved method and apparatus for forming gaskets on closure member surfaces with a high degree of accuracy and uniformity.
A further object is to provide an improved method and apparatus for applying semiliquid gasket compound to container closures and curing the same at an elevated temperature.
A still further object is to provide a method and apparatus for applying semiliquid gasketing compound to closure members and transferring the same into a curing oven with a minimum of compound flow once the same has been applied to the closure.
A more detailed object is to provide an improved heated metering nozzle for applying semiliquid gasket compound to closure members.
A further detailed object is to provide a precooled conveyor belt for transferring closures into a gasket curing oven.
Further and more detailed objects will be in part obvious and in part pointed out as the description of the invention, taken in conjunction with the accompanying drawing proceeds.
In the drawing:
FIG. 1 is a vertical sectional view of the closure lining apparatus of the invention;
FIG. 2 is an enlarged sectional view of the heated lining nozzle;
FIG. 3 is a top plan view of a series of closure lining devices operatively arranged about the improved curing apparatus of the invention; and
FIG. 4 is a vertical sectional view of the curing apparatus of FIG. 3.
The compound applying operation as illustrated in FIGS. 1 and 2, shows a semiliquid gasketing material, commonly referred to as lining compound, stored in a reservoir 1 and surrounded by a heating jacket 2. The liquid heating medium 3 held by the jacket 2 is kept at a constant temperature by any suitable device such as the heating coil 4. The purpose of this preliminary warming is to impart to the lining compound a consistency that will allow the same to be pumped through the line 5 to the nozzle 6 and there deposited into the closure 7. In this particular compound applying arrangement the nozzle 6 is held in a stationary position by a support member 8 fixed to table 9. The closure member 7 is raised into a position adjacent the end of fixed nozzle 6 to receive the lining compound by means of a spinning vacuum chuck comprising a resilient seat member 10 secured to the upper end of a rotating and vertically reciprocating shaft 14. The shaft 14 is slideably keyed at 15 to a sleeve 16 which surrounds the upper portion thereof. The lower end of shaft 14 is operatively connected to an actuating means not shown for vertically reciprocating the shaft 14 within the sleeve 16. The sleeve 16 and consequently the shaft 14 are rotated by the ring gear 17 which drives the pinion 18 keyed to sleeve 16 at 19. Thus, the shaft 14 and the sleeve 16 are rotated together while the shaft 14 can at the same time be reciprocated in that sleeve. The chuck actuating and driving assembly is carried within a sleeve 20 forming part of housing 21, through intervening bearing members 22 and 23 by means of locknut 24. The housing 21 formed within the table 9 is also provided with a removable access plate 25 which surrounds the chuck and forms a continuation of the table surface 9. Vacuum is drawn through the chuck seat 10 through a passageway consisting of a bore 26 which extends through the upper portion of shaft 14 and which communicates with a port 27 extending laterally through the side of shaft 14 and opening 28 in the sleeve 16-. A vacuum pipe 29 extends through the housing sleeve 20 and the bearing 22 into a communication with the opening 28. A rubber seal 30 carried at the upper end of the sleeve 16 seals against the shaft 14 to prevent loss of vacuum therebetween.
In operation the shaft 14, and consequently the chuck seat 10, is constantly rotated while a vacuum is drawn therethrough so that as a closure 7 is pushed onto the seat 10, it is retained thereon. As the shaft is rotated an intermittent vertical reciprocating action is also imparted thereto so that a closure 7 retained on the seat 10 is raised above the plane of the plate 25 into lining position adjacent the end of nozzle 6 as shown in FIG. 2. The nozzle 6 is of the electropneumatic type such as is manufactured by the Dewey and Alm-y Division of W. R. Grace Company and sold under the trademark Darex. The nozzle is actuated, through a series of conventional electrical switches, in timed relation to the upward movement of the chuck seat 10' so that a predetermined amount of the lining compound is ejected into a closure seated on the chuck seat as soon as the closure is positioned adjacent the nozzle. Upon application of the lining compound to the closure it is returned to its lowered position and removed from the chuck.
One critical step in the closure lining process with which this invention is particularly concerned is the actual flowing or metering of the lining compound into the closure. The effectiveness of a closure in achieving a tight seal is largely dependent on the contour and placement of the gasket within the closure. This requires that a high degree of uniformity be maintained in the initial applica-' tion of the semiliquid compound to the closures not only from a single nozzle over sustained periods of operation but also between a number of separate nozzles operating continuously. In order to attain this uniformity it has been found necessary not only to heat the reservoir 1 so that the compound therein possesses the optimum consistency for application but in addition, the nozzle 6 must be heated in order to insure against clogging of the compound 31 therein. However, inasmuch as an elevated temperature of he curing oven is required in order for the semiliquid compound to be cured so as to take on a permanent set, any minor heating of the cap prior to the baking or curing step only acts as a detriment in causing the compound to slump or flow within the cap after it has been applied. It has thus been found advantageous to heat the nozzle in such a manner that the compound within the nozzle may be heated to the point that it may be accurately and rapidly metered therefrom without heating the closure. By keeping the closure cool it has been found that tendency of the compound to flow after it is applied to the closure is retarded. Attempts at accomplishing this result have been made through the use of infra-red heat lamps but in the high speed production of lightweight aluminum closures the heat lamp arrangement has proved deficient in several respects. In the first place, the lamp applies heat to the nozzle in a relatively uncontrolled manner so that it is difficult to maintain the compound 28 Within the nozzle at a constant predetermined temperature. This deficiency becomes particularly apparent if the continuous operation of the nozzle is interrupted for any reason at which time the nozzle overheats causing a change in the flow characteristic of the compound and may even get hot enough to trigger the cure reaction so that the nozzle clogs. Thus the very condition which the heat lamp is supposed to prevent is in fact frequently brought on. In addition, the lamp arrangement heats not only the nozzle but a substantial area therearound creating a hazard for people involved in normal operating adjustments and cleaning. It has also been found the severe heat may have a deleterious effect on certain parts of the lining mechanism such as the rubber chuck seat 10 and the rubber vacuum seal 30.
In this invention the nozzle 6 and the semiliquid lining compound therein are heated by means of a localized heating element shown in FIGS. 1 and 2 comprising a coil of copper tubing 13 surrounding the nozzle 6 and connected through a pair of lines 11 and 12 to the reservoir jacket 2. Circulation of the heating medium 3 through the coil 13 is provided by the pump 32. A suitable electric heating coil and controls could alternately be employed without departing from the scope of the invention. Also the actual number of coils surrounding the nozzle could be increased so as to substantially enclose the same if desired. Of major importance is the fact that the compound 31 Within the nozzle 6 is thus kept at the constant uniform temperature required for optimum metering of the compound from the nozzle opening 33. The compound is ejected from the nozzle into a relatively cool environment so that upon application to the closure surface any tendency of the uncured gasket 34 to flow or slump down into the top of the closure is retarded. This results in much greater control over the placement and the contour of the gasket in the finished closure. Another advantage of the disclosed localized heating means of this invention is the prevention of over heating of the nozzle in the event of a temporary interruption in the operation of the closure feeding means. The temperature of the compound 31 within the nozzle cannot rise above the temperature of the compound within the reservoir 1 since both are heated by the same heating medium 3, thus any possibility of the compound hardening within the nozzle is eliminated. Also to be noted is the fact that the immediate environment surrounding the lining nozzle does not become heated so that there is no problem of having to use heat resistant rubber parts and lubricants nor is there danger of operators getting burned in carrying out normal operational adjustments, maintenance and cleanmg.
The next step in the closure manufacturing process with which this invention is particularly concerned is the conveying of the lined caps into the curing or baking oven as illustrated in FIGS 3 and 4. In this step of the operation it has also been found desirable to keep the lined closure relatively cool prior to its entry into the oven, since here, as in. the actual lining step, any warming eflfect on the closure prior to its entrance into the oven, only causes further flowing or slumping of the compound on the closure surface giving the unwanted result described earlier. Once the cap actually enters the oven, the elevated temperature thereof triggers the hardening reaction and the shape of the gasket becomes permanent. FIG. 3 illustrates a typical production set up wherein a plurality of lining machines indicated at 35a, 35b and 350 are arranged about a main conveyor 37 which carries the lined caps 7 into the oven. Each of the lining machines 35a, 35b and 350, for purposes of illustration is seen to comprise a lining nozzle 6, and a pair of transfer fingers 38 which removes the lined closure from the spinning chuck onto a short conveyor belt 39 which in turn deposits the lined closures onto the oven conveyor 37. The fingers 38 reciprocate horizontally in the plane of the conveyor belts 39 and in timed relation to the vertical reciprocation of the seat member so that they move toward the conveyor belt when the seat member 10 is in the plane of the conveyor belt and away from the conveyor belt when the seat member 10 is above the plane of the conveyor belt. It can now be appreciated that a high degree of uniformity in the gasket contour and placement is difiicult to achieve if slumping or flowing of the compound within the closure is not restricted from the time the compound is applied to the closure until it enters the oven. This is particularly true in a production set up as illustrated where there are substantial time differentials between various lining machines and the curing oven.
This condition has been remedied, by an arrangement, shown in FIG. 4 comprising a curing oven 40 having an entrance 41, an exit 42 and insulated top and bottom walls 43 and 44 respectively. Located rearwardly of the oven 40 is a cooling chamber 45 having an air inlet 46 and an exhaust 47. Also operatively arranged in relation to the oven 40 is a front idler roller 48 a rear drive roller 49 and a pair of lower guide rollers 50 and 51. The conveyor belt itself, generally indicated at 37, is of an open mesh metal construction so as to allow the relatively free passage of air therethrough and is disposed about the rollers 48, 49, 50 and '51 so that only the upper reach 52 passes through the oven 40 while the lower reach 53 passes be low the oven and is insulated therefrom.
In operation the upper reach 52 of the conveyor belt 37 carries the lined closures through the oven 40, where by the conveyor belt, the closure and the compound are heated to the elevated curing temperature required to trigger the hardening reaction in the compound which then takes a permanent set. The gasketed closures are then conveyed from the oven over the intake opening 46 of the cooling chamber 45 where relatively cool air is drawn around the closures and through the belt causing the temperature of both to be substantially reduced. The finished closures are then dumped ofi the end of the belt into a bin 54. The lower reach 53 returns below the oven and is insulated therefrom so that the belt during this travel continues to cool. Thus by the time that additional closures lined with the uncured compound are deposited upon the front end of the upper reach 52, there is very little heat and its accompanying detrimental eifects, left in the belt which can be transferred to the closures. Accordingly the use of this cool belt arrangement allows a high degree of uniformity in gasket contour and placement to be achieved between the various lining machines regardless of their spacing from the entrance to the oven.
From the foregoing then it is clearly evident that, firstly, the novel nozzle heating arrangement results in closer gasket control during the actual lining operation and, secondly, the novel oven conveyor belt arrangement provides closer gasket control when utilizing several lining nozzles during the curing operation. Both of these improvements provide a method of gasketing closures wherein the detrimental influence of heat is kept to a bare minimum.
Other and different variations of the invention may well suggest themselves to those skilled in the art without departing from the scope and spirit of the invention. It is accordingly to be understood that the method and apparatus for carrying out that method, shown in the accompanying drawing and described in the foregoing description, are to be considered as illustrative of the invention and are not to be considered as being set forth in a limiting sense.
Having described my invention what we claim is new and desire to secure by Letters Patent is:
1. The method of gasketing container closure members comprising storing a quantity of semiliquid lining compound in a jacketed reservoir, circulaitng a heating medium within said jacket to maintain said compound in a readily flowable heated condition, bringing said closure members into close proximity to a metering nozzle, dispensing a quantity of said heated semiliquid lining compound from said reservoir onto a relatively cool closure member by means of said metering nozzle, heating said nozzle by means of said heating medium so as to maintain the lining compound therewithin in readily flowable heated condition but without any appreciable heating of said closure member, transferring said closure members onto the entrance end of a horizontal endless conveyor belt, conveying said closure members through a curing oven and heating the belt and the closure members to an elevated compound curing temperature, removing said closure members from the exit end portion of said belt, and allowing said belt to cool continuously throughout its return travel outside the curing oven from the point the closure members are removed until additional closure members are conveyed into said oven whereby the amount of heat imparted to closure members prior to their entry into the oven is minimized so as to retard the flowability of the semiliquid lining compound prior to curing.
References Cited UNITED STATES PATENTS 2,658,796 11/1953 Kopperschmidt 118-302 X 2,889,806 6/1959 Conant 1l7-1l9.6 X
OTHER REFERENCES Rand, Jr.: Mechanical Applications of Flowed-In Gaskets, Rubber Age, January 1953, pp. 477-481.
DAVID KLEIN, Primary Examiner.
US. Cl. X.R.
184; l17l05.l, 105.3 120; 118-302, 70, 324