GB1604560A - Method of producing a closure cap - Google Patents

Description

(54) IMPROVEMENTS RELATING TO A METHOD OF PRODUCING A CLOSURE CAP (71) We, NATIONAL C CORPORATION, a Corporation organised under the laws of the State of Delaware, United States of America, of 8101 West Higgins Road, Chicago, Illinois 60631, United States of America. do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a method for applying a liner of a mouldable and curable material such as a plastisol to unlined closure caps.

For many years the conventional bottle closure consisted of a metal cap which had a cork disk secured therein which would seal against the top of a package to seal the contents therein.

In more recent years substantial activity in the plastics field has lead to the substantial ultilisation of plastics as a lining material in the industry, replacing the conventional cork liner.

Various types of methods and apparatus for applying liners to unlined cap closures have been proposed and are in existence at the present time. One type of apparatus that has been used extensively is described in Aichele United States Patent No. 3,135,019.

This patent discloses a machine for applying liners of thermoplastic material to cap closures, particularly crown caps. In the machine described in this patent, the caps are preheated and a heated thermoplastic material in a soft plastic condition is fed in metered amounts to the respective unlined caps. The thermoplastic material is then shaped or moulded and set into a liner formation by a moulding head that is rotated in a continuous fashion. A sljecific type of plastics metering means for the above machine which is described in Aichele United States Patent No. 3,212,131 is capable of feeding small charges of thermoplastic material at rates of approximately 300 caps per minute.

Another crown cap lining machine is described in United States Patent No. 2,954,585 which describes a method in which predetermined amounts of a thermosetting plastics lining material are deposited into unlined caps which are then transferred with the un- cured plastics to a moulding and curing turret which has circumferentially spaced clamps into which the plastics container caps are fed and clamped therebetween. The clamping members coact to clamp the lined caps during which heat is applied to cure the cap liners and the cured lined caps are then discharged through a take-off mechanism associated with the turret.

The present invention seeks to provide a method of producing lined cap closures which is an improvement on the existing methods, particularly with regard to speed.

According to the present invention, there is provided a method of producing lined cap closures at a rate of more than 1000 per minute with a continuously rotating feed wheel having a plurality of pockets, a moulding and curing head having a plurality of stations, and a take-off wheel having a plurality of pockets, the method comprising aligning a dispensing unit above the path of movement of the pockets of the feed wheel, delivering unlined cap closures to the respective pockets of the said feed wheel, delivering a continuous supply of pressurised fluid lining compound at substantially room temperature and under pressure to the dispensing unit, sensing the position of the pockets of the feed wheel with respect to the path of the pockets and electrically actuating the dispensing unit each time a pocket is aligned therewith while maintaining the dispensing unit at substantially room temperature.

Recently, a more acceptable type of lining material has been developed which is capable of producing small voids in the material as the liner is being formed in the cap closure and it is believed that the method of the present invention is particularly suitable for use with such lining material This lining material includes a plastisol material, fillers and waxes plus a blowing agent which is deposited into the unlined cap closures and is subsequently heated to cure the liquid lining compound. During the curing process, the blowing agents dissolve at a predetermined temperature and create small voids in the finished and cured lining material in the cap closure. It has been determined that the small voids aid in producing a proper seal with a container, such as a glass bottle, which in many instances has small nicks or uneven upper edges to which the cap closure must be sealed.

Preferably the method of the present invention includes heating each of the stations sufficiently to cure the compound on each cap while the cap is on the moulding and curing head.

Likewise it is preferred for the method of the present invention to be performed with a dispensing unit having an elongated chamber with an upper inlet and a lower outlet and a plunger reciprocable within the chamber to open and close the lower outlet, and a solenoid surrounding the chamber, the method including the steps of actuating the solenoid each time a pocket is aligned with the dispensing unit to raise the plunger and open the outlet to allow compound to flow through the chamber towards the cap closures on the feed wheel whilst maintaining the dispensing unit at substantially room temperature. In such a method it is preferred that the plunger is biased towards a lower closed position and is raised by the solenoid.

The lined cap closures are completed by the step of heating the cap closures in the stations of the mouldings and curing head between the said feed wheel and the said take-off wheel by means of at least one stationary heating element located adjacent the moulding and curing head.

The invention may be carried into practice in various wavs but one machine for performing the method of the invention, and a method of lining caps using the machine, will now be described by way of example with reference to the accompanying draw Ings, in which: Figure 1 is a schematic top plan view of the cap lining machine; Figure 2 is a fragmentary sectional view, as viewed generally along line 2-2 of Figure 1; and Figure 3 is an enlarged fragmentary sectional view as viewed along line 3-3 of Figure 1.

Figure 1 of the drawings shows a cap lining machine 10 consisting of a frame or base 12 which has a moulding and curing head 14 rotatably supported thereon and a feed means 16 for continuously supplying unlined caps having a curable fluid compound to the rotating moulding and curing head 14 at an inlet station 17. A take-off mechanism or means 18 is located at an outlet station 19 for removing the finished lined caps from the curing and moulding head.

The moulding and curing head or turret 14 (Figure 2) consists of a turret plate 20 which is fixed to a shaft 22 that is rotatably supported in a bearing structure 24 mounted on the base 12 and is rotated through a suitable drive means. which will be described in more detail later. A plurality of moulding and curing stations 26 (48 in number being illustrated in the drawings) are equally spaced around the periphery of the plate 20 and each is designed to receive a cap having a charge of lining material to be cured while moving between the inlet station and the outlet station. The details of each station are illustrated in Figures 2 and 3, and include a plunger 28 which is reciprocated within openings 30 located in vertically spaced support plates 32 which are fixed to the plate 20 by members 33 for rotation therewith. Each of the plungers 28 has a moulding tip 34 at the lower end thereof and is normally biased into the position illustrated at the left-hand portion of Figure 2 to a closed position by a biasing spring 36. In the closed position, each moulding tip 34 cooperates with a recess or pocket 38 defined in the plate 20 to clamp and grip a cap 39 for moulding and curing the lining compound.

Each of the plungers 28 is moved to an open position by a camming mechanism which includes a camming surface 40 defined on the upper surface of a member 42 which extends around the perimeter of the moulding head and is fixedly secured to the base plate 12 through suitable support structure 44. Each plunger 29 has a cam roller 46 which is rotatably supported on the upper end thereof and is aligned with the camming surface 40, as illustrated in Figures 1 and 2. The camming surface 40 is configured such that the respective plungers 28 are reciprocated between raised and lowered positions during each cycle of rotation of the plate 20. More specifically, the camming surface 40 has an inclined portion 48 located in close proximity to the take-off mechanism 18 which cams the plungers 28 upwardly to raise the moulding tips 34 sufficiently and allow the caps to be removed from the pockets 38 by the take-off mechanism 18. The camming surface 40 maintains the plungers 28 in the raised position to allow the feeding mechanism 16 to insert new caps with uncured lining material into pockets 38 at the inlet station 17.

Each of the stations 26 is heated during each revolution of the turret plate 20 to maintain the moulding tips 34 and the surfaces of the pockets 38 at a curing temperature which is preferably of the order of 400 F. For this purpose, heating means 50 are located around the periphery of the turret plate 20. The heating means 50 consists of arcuate gas burners 52 and 54 which are positioned as illustrated in Figures 1 and 2.

The gas burner 52 directs flames to the lower surface of the plate 20 while the gas burner 54 directs flames to the periphery of the plate 20 and each of the moulding tips 34.

In order tci maximise the heating of the tips 34, a heat shield or reflector 56 is located adjacent the inner periphery of the tips 34 to reflect the heat towards the tips. Of course, while gas heaters have been shown, electric heaters could be utilised instead.

The take-off mechanism 18 consists of a star wheel 60 that has a plurality of circumferentially spaced pockets 62 defined thereon which are capable of removing completed lined caps from the respective recesses 38 defined in the plate 20 for transfer to a take-off conveyor 64 for subsequent processing and packaging. The star wheel 60 is supported on a shaft 66 which is rotatably mounted on the base 12.

The feeding mechanism 16 consists of a star or feed wheel 70 that is supported on a shaft 72 which is rotatably supported within a bearing 74 secured to the base 12. The feed wheel 70 is rotated by the drive means which will be described in more detail later.

The feed wheel includes a plurality of circumferentially spaced pockets 76 (Figure 1) which are defined between circumferentially spaced projections 78 and each pocket 76 is designed to receive an unlined cap 39 from a supply source 80. The supply source 80 includes a hopper or bowl 81 which is rotated to deliver orientated caps to a supply chute 82.

The star wheel 70 has its peripheral portion received between a pair of fixed arcuate segments 83 and 84 which are interconnected at the periphery thereof through a member 86 and are fixedly secured to the base 12 through suitable means not shown. The arcuate members 83 and 84 extend from the cap closure inlet 90 to the transfer station between the feed means 16 and the turret 14.

As illustrated in Figure 3, the upper plate has a substantially circular opening 92 while the lower plate has an opening 94, these two openings being aligned with an outlet 96 of a dispensing means 100.

With the arrangement so far described, unlined caps 39 are fed from the source 80 in orientated fashion so that they are inverted as illustrated in Figures 2 and 3 and are delivered to the respective pockets 76 on the periphery of the feed wheel 70. As the inverted cap closures 39 are transferred along the peripheral path defined by plates 83, 84, and 86. predetermined amounts of curable fluid compound at substantially room temperature are dispensed into the centres of the cap closures through the dispensing means which will now be described.

The dispensing means is preferably a commercially available unit sold as a "Hot Melt" solenoid gun by the Aro Corporation, Bryan, Ohio, United States of America, under Model Nos. 656301/656302.

It has been determined that the commercially available unit with minor modifications can be utilised for dispensing predetermined charge of curable liquid lining compound at substantially more than onethousand cycles per minute to unlined caps which are continuously moving with the pockets of the feed wheel 70. The details of the dispensing means 100 and the actuating means 128 are illustrated in Figure 3.

The dispensing means 100 consists of a housing 102 that has an arm 104 extending therefrom and the arm 104 is held in a fixed position on a support 106 extending above the base 12 (Figure 1). The housing 102 has a circular centre chamber 110 defined therein which is in communication with the outlet 96 and is adapted to be connected to a source of pressurised curable liquid lining compound through a flexible hose 112. The chamber 110 has a polygonal member 114 reciprocated therein with a needle 116 at the lower end of the polygonal member. The needle is normally biased to a closed position illustrated in Figure 3 through a biasing spring 120 engaging the upper surface thereof to close the outlet 96. The member 114 and the needle 116, which define needle means, are reciprocatable between a first closed position and a second open position through electric means which will now be described.

The electric means includes a solenoid 122 with the member 114 defining the plunger for the solenoid. The solenoid 122 is connected to a control box 124 which has a wire 126 leading therefrom to a receiving unit 128 of a photoelectric means. The photoelectric means also includes a light source 130 which is accurately positioned with respect to the periphery of the feed wheel 70 through a support mechanism 132 that is fixed to the base 12. The control circuit may include a D-C power source with a time delay relay circuit therein.

Thus, as the feed wheel 70 is rotated, each time a projection 78 passes between the photocell 130 and the receiving pulsing unit 128, a pulse is transmitted to the control box 124 and then to the solenoid 122 to move the needle means from its first closed position to a second open position to allow a predetermined amount or charge 140 of material to be dispensed through the outlet 96 of the dispensing means 100. Since the pulsating signal which energises the solenoid 122 is sensed from the rotating feed or star wheel 70, the predetermined charge is accurately positioned within the centre of the unlined cap 80 at all times. Furthermore, by having openings 92 and 94 in the respective plates 83 and 84, if no unlined cap closure is located within a given pocket, the dispensed material can travel directly through the openings and be collected in a collection mechanism (not shown) fol reuse.

The liquid lining compound is continuously fed to the chamber 110 from a source (not shown) in a pressurised state which is preferably of the order of 400 PSI. The compound flows between the surface of the polygonal plunger 114 and the surface of the circular chamber 110 to the lower reduced end having the needle 116 therein. It has been established that the lining compound, which is at room temperature, actually aids in maintaining the plunger and chamber surfaces at close to room temperature so that the dispensing means can be operated at rates of substantially more than onethousand cycles per minute without heating the lining compound in the gun.

It will be seen that the entire drive mechanism is devoid of any intermeshing gears substantially to increase the life of the unit and decrease he maintenance costs should there be a need for replacement of any of the components of the drive mechanism. As illustrated in Figure 1, the drive mechanism consists of a motor 144 fixed to the base 12 and with a drive sprocket 146 on its output shaft. A further driven sprocket 148 is fixed to the shaft 22 and a timing belt 150 is entrained over the sprockets 146 and 148. Since the timing belt and sprockets 146 and 148 can accurately rotate the moulding and curing head 14 in relation to the rotation speed of the motor 144, synchronised rotation is assured.

The feed wheel 70 is likewise driven from th same motor 144 and for this purpose the turret shaft 22 has a second sprocket 154 secured thereto while shaft 72 has a further sprocket 156 secured thereto and a timing belt 158 is entrained over the two sprockets 154 and 156. The belt 158 is also utilised for operating the unlined cap feeding mechanism 82 which feeds the caps 39 in a proper orientated fashion to the feed wheel 70. For this purpose, a further idler sprocket 160 is supported for rotation on the base 12 through a shaft 162. An additional sprocket 164 is also supported on the base 12 and the belt 158 is entrained over both of these additional sprockets. A further timing belt 166 is entrained over additional sprockets respectively located on the shaft 162 and on a shaft 170 which forms part of the hopper feed mechanism 80 illustrated in Figure 1.

Thus, the feed wheel 70 and hopper drive mechanism are all driven in correlated synchronised relation with respect to the moulding head 14.

In addition, the take-off feed mechanism 18 also is driven through the same power source and consists of a further additional timing belt 174 which is entrained over a further drive sprocket 176 (Figure 2) on shaft 72 and an additional sprocket 178 secured to the shaft 66 on the take-off sprocket or star wheel 60.

Thus, all of the driven components are driven by a single source and are accurately synchronised with respect to each other through the various timing belts. This particular drive mechanism has a significant advantage in that the timing belts can more accurately synchronise the driving relation of the various components with respect to each other. Furthermore, in case there is a breakdown of any of the timing belts and/or sprockets associated therewith, the various components can readily be replaced in a matter of minutes without any substantial maintenance time. In contradistinction, when drive gears are utilised in a system of this type, if a gear is damaged and needs replacement, it is necessary substantially completely to tear down the entire unit which may require hours of maintenance.

By way of example and not of limitation, a specific drive mechanism will now be described. In order to produce 1080 caps per minute, a motor having an output shaft rotated at 45 R.P.M. had a sprocket having 36 teeth secured thereto and the turret shaft had a sprocket with 72 teeth with a timing belt interconnecting the two sprockets. The turret had 48 stations while the feed wheel had 24 pockets. The output star wheel had 18 pockets and a sprocket with 18 teeth while the feed shaft had a further sprocket with 36 teeth. Thus, all wheels including the drive for the source 80 were operated in synchronised relation and lined caps were produced at a rate of 1080 per minute. This is in contrast to an identical moulding head having 48 stations with a reciprocal feed mechanism and a plunger actuated liquid compound feed mechanism which had a production rate of less than 700 closures per minute.

The lining compound utilised to obtain the above production was a compound purchased from Chemical Products Division, CPL Corporation, East Providence, Rhode Island, United States of America, under the designation of D-3133.

Actual runs showed that the lining compound could be fully cured during the movement of the closures between the inlet and outlet stations with the metal on each of the stations maintained at a temperature in the neighbourhood of 400 F. The hot melt gun was operated at substantially room temperature and the lining compound was used to maintain the chamber surfaces at substantially room temperature by eliminating the heating eiements incorporated into the existing commerical "Hot Melt" gun produced by the Aro Corporation.

It is believed that the apparatus described above with some further refinements could produce lined closures at rates approaching 2000 closures per minute utilising the commercially available gun.

Attention is drawn to our co-pending British Patent Application No. 25770/78 (Serial No. 1604559) which describes and claims apparatus for carrying out the method

Claims (6)

claimed herein. WHAT WE CLAIM IS:-

1. A method of producing lined cap closures at a rate of more than 1000 per minute with a continuously rotating feed wheel having a plurality of pockets, a moulding and curing head having a plurality of stations, and a take-off wheel having a plurality of pockets, the method comprising aligning a dispensing unit abode the path of movement of the pockets of the feed wheel, delivering unlined cap closures to the respective pockets of the said feed wheel, delivering a continuous supply of pressurised fluid lining compound at substantially room temperature and under pressure to the dispensing unit, sensing the position of the pockets of the feed wheel with respect to the path of the pockets and electrically actuating the dispensing unit each time a pocket is aligned therewith while maintaining the dispensing unit at substantially room temperature.

2. A method as claimed in Claim 1 which includes heating each nf the stations sufficiently to cure the compound on each cap while the cap is on the moulding and curing head.

3. A method as claimed in Claim 1 or Claim 2, in which the dispensing unit has an elongate chamber with an upper inlet and a lower outlet and a plunger reciprocable within the chamber to open and close the outlet, and a solenoid surrounding the chamber, including the steps of actuating the solenoid each time a pocket is aligned with the dispensing unit to raise the plunger and open the outlet to allow compound to flow through the chamber towards the cap closures on the feed wheel whilst maintaining the dispensing unit at substantially room temperature.

4. A method as claimed in Claim 3, in which the plunger is biased towards a lower closed position and is raised by the solenoid.

5. A method as claimed in any preceding Claim, further comprising the step of heating the cap closures in the stations of the moulding and curing head between the said feed wheel and the said take-off wheel by means of at least one stationary heating element located adjacent the moulding and curing head,

6. A method of producing lined cap closures substantially as described herein with reference to the accompanying drawings.