Apparatus For Employing Seals To Closures For Containers

Abstract

Apparatus for emplacing a seal on a closure for a container in which a seal forming material is deposited on the surface of the closure initially in a pattern of discrete droplets and fused to form a homogeneous layer.

Description

This invention relates to the sealing of closures for containers and particularly to means for emplacing seals thereon.

The seals that are provided may take two forms. In one, a barrier is formed to prevent leakage of fluids through the seal material. In the other, a gasket is formed to prevent leakage of fluids at the juncture between the closure and the container. An example of the first form of seal is that type used on the underside of a can end having a pull tab or other opening means associated with it, in which case the seal is emplaced on the inner surface of the can end to cover any joint or seam. An example of the second form is that type which extends around the inside of the top of a screw-on lid or crimp-on bottle cap.

In the application of such seals to container closures in the past, under high production speed conditions, the industry has been limited to applying circular seals in the first instance, and then applying these circular seals in one of two ways. One way has involved rotating a closure relative to a stationary applicator device. The other way has involved moving an applicator in a circular path adjacent a stationary closure. Both ways have involved expensive, complicated mechanisms to achieve the relative rotative movement required.

By contrast, and one of the features of this invention, is that the applicator is fixed in position and it is not necessary to rotate the closure during the application of the seal. The closures are simply moved stepwise past the applicator to bring each closure, in turn, into a stationary position adjacent the applicator. This stepwise movement of the closure is the only relative movement that occurs between it and the applicator. As will be seen, the applicator stays fixed in spaced relationship to the path of movement of the closures past it, and the seal material is actually projected from the applicator onto the closure that is adjacent it and stationary at the time.

Another feature is that the seal material may be projected from the applicator onto the closure in the configuration required for the seal. Hence, the invention is not limited to producing circular seals. As will be seen, it is possible to produce seals that are rectangular, triangular, oval or other shapes, and that may even appear as a C or other open pattern as required. Additionally, it is possible to apply several seals simultaneously to the same closure.

There is a very practical advantage in the use of this invention in applying seals to can ends. Such seals may be applied at a rate of production matching the speed of a high performance can end forming machine, which is about 350 can ends per minute. Thus, the seals may be applied right at the discharge end of the forming machine, on line with it, so that handling of the can ends is minimized.

In substance, the invention entails the forcible ejection of seal material in a controlled burst from a multi-orificed nozzle. The axes of the orifices parallel one another and the orifices are quite small. The burst is exceedingly short timewise, lasting only approximately from 5 to 50 milliseconds. To form a circular seal the centers of the orifices are on a circle and they preferably are equally spaced going around the circle. To form seals of other configurations the pattern of orifices is varied accordingly.

Comparatively high pressure is used to eject the seal material which pressure is in the range of from approximately 100 to 500 pounds per square inch. The closure surface to receive the seal material is spaced from the nozzle. This space may be in the range of from one-sixteenth to three-quarters of an inch. The result of the forcible ejection or burst of material from the nozzle is a string of discrete droplets matching the pattern of the orifices in the nozzle. Following the initial deposit of the string of droplets onto the surface of the closure the droplets fuse into a homogeneous layer to form a seal of the desired configuration.

Specific objects and other advantages of the present invention will be readily apparent from the following detailed description of the drawings in which:

FIG. 1 is a diagrammatic side view showing the application of two seals to can ends on a conveyor that moves them through a heat tunnel;

FIG. 2 is a semi-diagrammatic view, with parts being shown in cross section, illustrating an assembly comprising two applicators, plus the controls and air pressure conduits associated therewith;

FIG. 3 is an enlarged fragmentary cross sectional view;

FIG. 4 is a fragmentary cross sectional view taken on the line 4--4 of FIG. 2;

FIG. 5 is a fragmentary cross sectional view taken on the line 5--5 of FIG. 2;

FIG. 6 is a plan view of the inner face of a can end having two push-out tabs;

FIG. 7 is a view similar to FIG. 6 showing a string of droplets of material applied to each of the push-out tabs;

FIG. 8 is a view similar to FIG. 7 showing finished seals;

FIG. 9 is a perspective view illustrating a variety of pull-tab opener on a can end;

FIG. 10 shows the inner face of the can end of FIG. 9 with droplets of hot-melt applied thereto;

FIG. 11 is a view similar to FIG. 10 showing the hot-melt material fused to form seals;

FIG. 12 is a cross sectional view of a typical screw-on bottle cap showing droplets of sealing material applied thereto;

FIG. 13 is a view looking down into the bottle cap of FIG. 12 showing the emplacement of the droplets of sealing material;

FIG. 14 is a view similar to FIG. 13 showing the hot-melt material fused to provide a gasket type seal;

FIG. 15 is a view of the inner surface of a can end having a pull-tab affixed thereto;

FIG. 16 is a view similar to FIG. 15 showing a string of droplets of hot-melt material applied thereto;

FIG. 17 is a view similar to FIG. 16 showing the hot-melt material in fused condition.

Attention is directed to FIGS. 6 through 8 wherein a can end is shown requiring a barrier type seal. This particular can end is made of aluminum and it includes the usual curl or peripheral groove 11 encircling a flat central area 12, which area has been pierced to provide two push-in tabs 13 and 14. In each case, the metal of the can end is cut through on a semi-circular line 15 leaving a hinge section 16 so that the tab may be pushed inwardly from its normal closed position in order to open the can, while remaining attached to it. Tab 14 is much smaller in size than tab 13 and it is used to permit the initial escape of pressure of a carbonated beverage, whereas tab 13 provides a pouring opening. As shown in detail in FIG. 3, the metal is "worked" in the formation of each tab such that there is an overlap 17 of the outer periphery of the free edge of the tab with respect to metal of the can end immediately adjacent it. The overlap is on the inside of the can end in order to prevent internal pressure developed by carbonated beverages from popping oven the tab. In any event, a seam results that requires sealing and since the tab is essentially circular in configuration, it is preferred that a circular seal be provided to cover the seam and the hinge area 16.

As shown in FIG. 7, the initial step in the emplacement of a seal is the deposit of a string 18 of individual, discrete droplets 19 of seal material in a circular pattern coincident with seam 15. This is done around both tabs 13 and 14. In the case of the larger tab, twelve such droplets are deposited. In the case of the smaller tab, only six droplets are deposited. The droplets are then fused as shown in FIG. 8 to provide, in each case, a homogeneous layer or film 20 that covers the seam and thereby prevents the escape of fluid.

Similar barrier types of seals are shown in FIGS. 9-11 and in FIGS. 15-17, wherein removable tabs are employed. Going first to FIGS. 9-11, there is shown a can end 21 having two rectangular openings 22-22 therein. A rectangular tab 23, having an upstanding free end 24, is provided to cover holes 22-22. Tab 23 is held in place on the can end over the holes by such means as adhesive. This type of can end is usually made of tin-plated steel and the purpose of the seal is two-fold, first to prevent leakage of fluid, and second to prevent interaction between the contents of the can and the raw metal edges at the cut-out openings 22-22, which imparts a bad taste to many canned beverages.

As shown in FIG. 10, two strings 25-26 of eight droplets each are deposited on the underside of the can end in two rectangular patterns coincident with the seams provided at the juncture of the tab and the edges of openings 22-22. Upon the fusing of the sealing compound a continuous rectangular homogeneous seal is provided for each juncture as shown at 27-27. Substantially the same type of seal is provided in the case of the can end illustrated in FIGS. 15-17 wherein a somewhat larger, single opening 28 is provided in the can end. The sides 29-29 of this opening flair and the ends 30-30 are rounded, being exemplary of another shape seal that may be formed using the principles of this invention. Again a tab 31 is adhesively affixed to the outside of the can end. Also the seam at the juncture of the opening and tab 31 is sealed and the raw metal of the cut edge of opening 28 covered, by first depositing a string 32 of 15 droplets, in this case, in a configuration coinciding with the shape of the seam and then fusing the droplets to form a seal as illustrated at 33 in FIG. 17.

FIGS. 12-14 illustrate a gasket type seal that may be formed. In FIG. 12, a typical screw-on bottle cap is shown at 34. The central area of the inside of the top of this cap is depressed as at 35 to provide a peripheral groove 36. A string 37 consisting of 12 droplets of seal material is deposited in groove 36 and fused to provide a continuous, unbroken seal 38 as shown in FIG. 14.

Various types of materials may be used to form seals for container closures in accordance with the principles of this invention. These materials are plastic ones. As used here, the word "plastic" means a material that is initially fluid in one state but capable of transforming into another state in which its form is fixed. In all instances, the plastic material is initially deposited as a string of discrete droplets. That is, at least at the instant when the material hits the surface of a closure it is in the form of such droplets. In the case of a thermoplastic material being deposited on a relatively cool can end the initially fluid droplets immediately congeal and remain discrete until they are heated to coalesce or fuse into one another. If the can end is heated sufficiently at the time of the deposit, the thermoplastic droplets fuse substantially instantaneously and then set upon cooling of the can end. On the other hand, in using a thermosetting material, the droplets are deposited in fluid form, they then flow together or coalesce to be set in this form by the application of heat. Some plastic materials, particularly rubber based ones may not require the application of heat. They are self-setting types in which the droplets are initially deposited in fluid form, coalesce into the desired seal configuration and become set in this configuration. Generally therefore, the plastic material is fluid upon deposit, coalesces with or without a change in state, and then becomes set in the desired configuration.

Plastic material that may be used also has certain requirements placed on it by the Food and Drug Administration since it contacts beverages that are to be consumed, and of course, the material should not chip, flake or drop into the contents of the can.

An important consideration, from the viewpoint of emplacing the seal, is the viscosity of the material. It should have a relatively low viscosity while in a fluid state. Further, it should have good "tack" characteristics. It is desirable that the material have a somewhat low tensile strength so that the seal layer may be torn without difficulty upon the opening of a push-in tab or a removable tab. A thermoplastic material meeting these requirements has been developed, being identified as DuPont LCH-23180. This material is used at a temperature of approximately 300.degree.F. It is to be understood that any plastic material meeting the designated requirements, and that is acceptable under Title 21, Food and Drug Administration Number 121.2550, Sub Part F, of the Federal Register, may be used.

The above is an overview to illustrate some of the more general aspects of the invention. A detailed description of a preferred embodiment of the invention now follows. In this embodiment a thermoplastic material is used for purposes of explaining the invention.

Reference is now made to FIG. 1 of the drawings, wherein a conveyor is shown diagrammatically at 39. It is preferred that the seals of this invention be applied immediately after the can ends have been formed. This may be done at the discharge end of the production machine, with the conveyor 39 operating in the same stepwise advancing motion of the machine.

An applicator assembly is shown generally at 40, with a can end 41 stopped beneath it. The applicator assembly 40, which is shown in greater detail in FIG. 2, is designed to apply two circular seals simultaneously to a can end, which seals are similar to those illustrated in FIGS. 7 and 8. The conveyor passes from the applicator assembly 40 into a heat tunnel 42 in order to fuse the discrete droplets into the homogeneous layer that comprises the seals. Thus, in the instance shown, the thermoplastic sealing compound is applied in a liquid state at about 300.degree.F. Since the can lids are at room temperature, the droplets solidify to an extent upon striking the relatively cool can end. Thereafter, the can ends move into heat tunnel 42. Using the compound to which reference has been made it is found that fusion of the material takes approximately 8 to 10 seconds at 350.degree.F. in the tunnel.

In FIG. 2, the broken line shown at 43 is representative of the upper surface of the conveyor 39 by which can lids are positioned beneath the applicator assembly 40. This assembly comprises essentially two "guns" which have some of the characteristics of those guns used to extrude hot-melt adhesives. These guns are of the airless type in that there is no stream of air issuing from the guns along with the liquids issuing therefrom. Pressurized air is used, however, to actuate the guns.

For this purpose air at relatively low pressure approximately 15 to 60 pounds per square inch, is used. Such a supply of pressurized air is indicated diagrammatically at 44. This supply of pressurized air to each of the guns of the assembly 40 is controlled at a solenoid valve 45 for one gun and at a solenoid valve 45a for the other gun. As shown, these two solenoid valves 45-45a are supplied by a common line 46 from a second source 47 of pressurized air at approximately 80 pounds per square inch. One of the guns of assembly 40 is designated generally at 49. This gun is designed to deposit the 12 droplet pattern onto the tab 13, whereas the other gun, indicated generally at 50, is designed to deposit the six droplets required for tab 15.

Solenoid operated valve 45 is connected to a three-way relay valve 52 by a conduit 53. Valve 52 is pilot operated, a spring return type and normally closed. Similarly solenoid operated valve 45a is connected by a conduit 53a to a relay valve 52a that is identical to relay valve 52. A conduit 54 connects relay valve 52 to gun 49, whereas a conduit 54a connects relay valve 52a to gun 50. Individual operation of the respective solenoid valves 45-45a is under the control of an electric timer shown diagrammatically only at 55. Electric timer 55 also includes as part of its circuitry a detector 56 capable of signalling the arrival and proper positioning of a can end at the assembly 40 for application of sealing material thereto. For an electrical timer which can be employed, see patent application Ser. No. 108,082, filed Jan. 20, 1971, assigned to the assignee of this application, now U.S. Pat. No. 3,682,131. By means of the electrical timer the frequency of the operation and the "open" time of each gun of the assembly may be controlled and therefore the amount of material discharged for each gun is controlled.

To accommodate their arrangement in the assembly, the two guns 49 and 50, although essentially of the same construction, have differently shaped parts. As shown, gun 49 comprises a block 57, the upper portion of which is bored out to provide a cylinder 58. A plate 59 encloses the top of the cylinder. Immediately below plate 59 an opening 60 is provided in block 57 to vent to the atmosphere the area of cylinder 58 above a piston head 61 disposed within cylinder 58. A rod 62 extends from piston head 61 down through a bore 63 in block 57 below cylinder 58, the bore providing a bearing and guide for the rod. In the lower area thereof, the block 57 has a chamber 64 therein through which rod 62 passes. A collar 65 is secured to rod 62, and a strong spring 66, surrounding the rod, and interposed between the upper surface of the collar 65 and the surface at the top of chamber 64, serves to urge the piston downwardly.

The lower end of rod 63 is configurated to provide a ball valve 67. The ball valve 67 closes as a result of the force of spring 66 against a circular seat in a valve member 68. Valve member 68 resides in the lower end of a bore 69 that passes through a receiver 70. Receiver 70 includes an upper, plate portion 71 that is affixed to the underside of the block 57 by means not shown, and a lower hub portion 72 that is generally cylindrical projecting downwardly from plate 71. The hub portion 72 is threaded externally as shown at 73 and it receives an internally threaded adapter 74. Adapter 74 has a planar floor therein as shown at 75. When the adapter is in place, threaded onto hub 72 as shown, the floor 75 abuts the lower end of hub 72 and it provides a base for the valve member 68. The upper part of valve member 68 has a bore 76 therein that is somewhat larger than the ball valve 67. Member 68 also has a bore 77 therein extending axially vertically below ball valve 67 that is substantially smaller in diameter than ball valve 67. With the ball valve seated as shown in FIG. 2 the passageway or bore 77 through the valve member 68 is closed. There is a matching bore 78 that passes axially through the floor of adapter 74. As shown in FIG. 4 the underside of the floor portion of adapter 74 has cruciform grooves 79 cut into it, which grooves provide passageways radiating outwardly from the bore 78. The upper external part of adapter 74 may be configurated, as shown, to receive a tool such as a wrench for tightening it into place on hub 72. The lower external areas of adapter 74 is threaded as at 80 to receive the matching female threads of a nozzle 81.

Nozzle 81 in the upper part thereof comprises a collar 82 carrying internal threads to fasten the nozzle to the adapter 74. The lower part of the nozzle comprises essentially a disk 83. The upper surface of the disk 83 is planar as shown at 84 and when the nozzle is threaded into place, the surface 84 abuts the lower face of adapter 74, which is also planar in all areas surrounding the cruciform grooves 79, so that an essentially fluid tight juncture is provided. The upper surface 84 of the disk 83 of the nozzle has an annular groove 85 cut therein. This groove is in communication with the outer ends of the cruciform grooves 79 in the underside of adapter 74.

In the instance shown, 12 nozzle orifices 86 are drilled through the disk part 83 of the nozzle. The axes of these orifices are parallel with one another and they are on a circle centered on the vertical axis common to the center of ball valve 67 and to the aligned bores 77 and 78 respectively through valve member 68 and the floor 75 of adapter 74. The underside of the nozzle is configurated such that a boss 87 is provided immediately surrounding each orifice. It may be seen therefore, that with ball valve 67 raised from its seat on valve member 68, there is a passage past the ball valve down through matching bores 77 and 78, radially outwardly through the cruciform grooves 79, into annular channel 85, and thence through the nozzle orifices 86.

The hollowed out area within the block 57, comprising chamber 64 and the bore 69 in hub 72, holds thermoplastic or hot-melt sealing material. This material is forceably pumped into the chamber through a bore 88 from a heated reservoir 89 following conventional practices. A pump for this purpose is shown diagrammatically at 90 with a conduit for the material being shown at 91. Because of the hot-melt nature of the material, the block 57 is heated by means such as electrical resistance heaters, one of which only is shown diagrammatically at 92.

The other gun 50 making up the assembly 40 is substantially the same as the one that has been described, except that in this instance a nozzle 93 is disposed with its central axis at right angles to the axis of a bore 77a that opens through a valve member 68a downstream of the seat provided for a ball valve 67a. The other parts that are the same in the two guns are identified by the same reference numerals followed by the suffix a.

In the case of gun 50, an essentially cylindrical adapter 94 is used, which adapter is threaded externally as shown. The upper part of adapter 94 threads into a tapped bore in the lower part of a mount block 95 that is secured to an end plate 96 by means not shown. End plate 96 corresponds to the plate portion 71 of receiver 70 of gun 49. A right angular bore 97 extends from the bore 77a opening into a central bore 98 passing vertically through adapter 94. As in the case of the adapter previously described, the lower face of adapter 94 is planar with cruciform grooves 99 being cut therein. The nozzle 93 is essentially the same as nozzle 83, although smaller, and having only six nozzle orifices 100 therein. In this case, an annular groove 101 is cut into the upper surface of the disk part of nozzle 93 to provide communication between the outer ends of cruciform grooves 99 and orifices 100.

The pump 90 delivers hot-melt sealing compound to the chambers 64, 64a of the two guns 49 and 50 at a pressure of approximately 350 pounds per square inch. This material is heated to approximately 300.degree.F. and maintained at this temperature by the electrical resistance heaters 92, 92a that are located within the blocks of the guns. Although it is not believed essential, a recirculating system may be employed for the hot-melt material that is similar to the recirculating system disclosed in U.S. Pat. application Ser. No. 246,392, filed April 21, 1972.

There are certain relationships in the sizes of various parts of a gun, and particularly the nozzle thereof, that are important. Using gun 49 as the example, it is found that the cross sectional area of the passageway, the aligned bores 77-78, downstream of ball valve 67 should be just slightly larger than the combined cross sectional areas of the nozzle orifice 86. With this relationship established, it is preferred that the combined cross sectional areas of the cruciform grooves 79 be about the same as the two cross sectional areas just referred to. The same relationship should be established with respect to the cross sectional area of the annular groove 85. Otherwise expressed, the flow, volume-wise, of hot-melt material should be about the same in all parts of the stream from the valve seat to the discharge ends of the orifices.

More specifically, using a hot-melt having a viscosity of 300 centipoise at a temperature of 300.degree.F. each orifice should be approximately 0.010 inches in diameter and approximately 0.064 inches in length. Thus, since nozzle 93 of gun 50, in the example illustrated, has just one-half of the number of orifices used in nozzle 81 of gun 49, the cross sectional area of the passageway immediately below the seat for ball valve 67a should be approximately one-half of the corresponding area of the equivalent passageway in gun 49.

It is characteristic of the type ball valve shown for each of the guns 49 and 50 that an exceedingly fast opening movement and closing movement of the vlave is achieved. This is important in the successful emplacement of seals of the type disclosed. The advantages of this type of valve operation is discussed in U.S. Pat. No. 3,116,020, which patent is owned by the assignee of this application. The exceedingly fast movement of the ball valve relative to its seat incident to the starting and the stopping of the discharge of hot-melt material from the nozzle is stressed, because it is required in order to cleanly deposit discrete droplets of the hot-melt. Without this precise, rapid movement of the valve member, stringing of the material and a generally messy operation may result.

Operating within the comparatively high pressure range of the hot-melt material, for example at 350 pounds per square inch, the material is forcibly ejected or shot from the nozzles. Equally important, the lower ends of the orifices are spaced up away from the surface that is to receive the droplets. The spacing may be varied over a comparatively wide range for example, from one-sixteenth of an inch to approximately three-quarters of an inch. The almost instantaneous opening of the ball valve (67 or 67a) forcibly ejects a stream of hot-melt material from each nozzle orifice, (were the valve to remain open this stream would continue) but, the exceedingly fast closure action of the ball valve causes the stream to break cleanly at the lower end of the orifice, separating it from material remaining in the orifice. In this way, precisely shaped droplets of uniform size are deposited in a controlled fashion.

The timer 55 is arranged to control the solenoid operated valves 45 and 45a individually. The signal originating at detector 56 and going to timer 55 determines the frequency of the operating cycles. The timer itself, which is adjustable, establishes the "open time" for each of the valves 45 and 45a. This open time, of course, in in milliseconds. The pilot valves 52 and 52a directly control the application of air pressure to the cylinders 58 and 58a. Each pilot valve is normally closed so that no pressurized air flows through it. When air is directed to a pilot valve it opens to permit pressurized air to a cylinder. When air to the pilot valve is cut off, a spring within the valve custs off air from supply 44 and simultaneously exhausts the air from a cylinder. Indirectly, the solenoid valves therefor control the open time for the respective ball valves 67 and 67a of the respective guns 49 and 50. This in turn determines the amount of hot-melt that is fired from each gun. The timer itself is capable of fine adjustment. The solenoid valves are sensitive and quick acting. The same is true for the pilot valves. The closing of the ball valves 67 and 67a is under the action of the springs 66 and 66a. These springs are highly responsive types having 15 to 20 pounds compression strength. The net result is the split second characteristic of the bursts of material from the guns.

An expediency that is helpful in preventing a build-up of material on the nozzles is indicated at 102. As stated, an orifice may be approximately 0.010 inches in diameter. It is preferred that the discharge face of the nozzle be in the shape of a frustum of a cone surrounding each orifice and that a minimal land area 103 be provided surrounding each orifice. This land area may be approximately 0.005 inches wide.

Especially important in the application of two different sized seals simultaneously as shown in FIGS. 1-8 of the drawings, is the individual adjustment for the solenoid valves 45-45a. In this way two different seal patterns may be applied in the same on station time, with proportionate amounts of hot-melt compound being deposited by the guns such that the sizes of the droplets are the same in each pattern.

Of course, for single seal application only one gun is required, as for example in the case of the bottle cap shown in FIG. 12. Further, to deposit the non-circular patterns shown in FIGS. 9-11 and 15-17 the shapes of the nozzles used are changed accordingly.

Claims

We claim:

1. A nozzle for applying plastic sealing material to the surface of a closure for a container, said gun having a valve therein capable of opening and closing within the time range of from 4 to 50 milliseconds,

said nozzle being configurated to provide a vertical passageway in communication with the downstream side of said valve,

said nozzle further configurated to provide a plurality of horizontal passageways having inner ends thereof in communication with said vertical passageway and radiating outwardly therefrom,

said nozzle further configurated to provide an endless groove disposed in a horizontal plane and connecting the outer ends of all of the horizontal passageways, and

said nozzle further configurated to provide a plurality of discharge orifices that are disposed vertically with their axes parallel to one another and having their upper ends in communication with said endless groove and their lower ends all residing in the same plane.

2. A nozzle as set forth in claim 1 in which said orifices are all of the same size and approximately in the range of 0.006 to 0.020 inches in diameter by approximately 0.03 to 0.15 inches long.

3. A nozzle as set forth in claim 1 in which the orifices are all of the same size and in which the cross sectional area of said vertical passageway is only slightly greater than the combined cross sectional areas of all of the orifices.

4. A nozzle as set forth in claim 1 in which the cross sectional area of said vertical passageway is approximately equal to the combined cross sectional areas of said horizontal passageways.

5. A nozzle as set forth in claim 1 in which said horizontal passageways are cruciform in shape, and said endless groove is annular.

6. A nozzle as set forth in claim 1 in which said orifices are disposed in a circular pattern in equally spaced relation.

7. An extrusion nozzle assembly comprising:

an airless spray gun having a hollow cylindrical end portion;

valve means disposed in said hollow cylindrical portion;

an adapter attached to said end portion;

a control passageway in said adapter cooperating with said valve means;

radial grooves formed in the end face of said adapter and connected to said central passageway;

a nozzle attached to said adapter;

a groove formed in the inner face of said nozzle for communication with said radial grooves in said adapter;

orifices formed in said nozzle parallel to and uniformly spaced apart from each other; and

said orifices connected to said groove formed in the inner face of said nozzle and the outer face of said nozzle.

8. The apparatus of claim 7 in which said radial grooves in said adapter are arranged in a cruciform pattern.

9. The apparatus of claim 7 in which the orifices in said nozzle are arranged in a circular pattern.