NZ200812A - Aerodynamic stacker for can ends - Google Patents

Description

2 008 1 Woruv ^C(S): . — ^SS^ISi.^SwSSSwl-E?^^ Class: . q " ''''''"' PubSication Date: . .£8. SEP-1984 ' * ;P.O. Journal No: ;No.: Date: ;NEW ZEALAND ;PATENTS ACT, 1953 ;COMPLETE SPECIFICATION ;"AERODYNAMIC STACKER" ;^ JUt\ !■*$# &>:■: ?/We, W.R. GRACE & CO. , a corporation organized and existing under the laws of the State of Connecticut, United States of America, of 1114 Avenue of the Americas, New York, New York 10036, United States of America, hereby declare the invention for which we pray that a patent may be granted to jjssx/us, and the method by which it is to be performed, to be particularly described in and by the following statement: - (followed by page la) ,200c <£l £ 1a w.n. grace a co.

GJE 6081/122- AERODYNAMIC STACKER This invention relates to aerodynamic stackers for can ends, that is to say apparatus by which can ends can be stacked by aerodynamic forces.

A final stage in the manufacture of can ends 5 consists in lining the channel and curl around each can end with a gasket of plastic sealing composition that is deposited in liquid form, often while the ends are heated, and then cured. Although the composition may be cured by heating in an oven before the ends are 10 stacked it is generally preferred to stack them while curing and solidification of the composition is progressing. The liquid composition may be a composition based on organic solvent in which suitable polymeric and other materials have been dispersed and/or dissolved or 15 it may be an aqueous composition. Aqueous compositions may be made by redispersing polymeric material together with appropriate additives in water or may be made by mixing appropriate additives into a latex of the chosen polymeric material, these latter compositions being 20 termed "latex based compositions". Sometimes the lining of can ends with latex based composition is conducted on can ends that are preheated and the stacking occurs while the can ends are cooling and while the composition is solidifying and curing.

Stacking by hand is slow and so it is conventional to use mechanical stackers. Magnetic stackers are. commonly used when the ends are lined with an aqueous 2 008 1 2 dispersion composition. Typically about 300 to 800 ends are lined per minute and are then transported edge-wise along a short conveyor at about 80 metres per minute to a magnetic stacker which repositions them in a face-wise 5 stacker arrangement. Magnetic stackers can also be used with solvent based compositions.

Aerodynamic stackers were developed some years ago, initially for stacking aluminium can ends lined with a solvent based composition, but are now used for 10 stacking tin plated can ends as well. An aerodynamic stacker is described in British Patent Specification No. 1,039,064.

In aerodynamic stackers can ends are transported edge-wise from the station at which they are lined with 15 the liquid composition by a conveyor to a pneumatic device that is positioned to receive the can ends from the conveyor and which repositions them in a face-wise alignment, and there is a trough that receives the can . ends from the pneumatic device and holdsthem as a stack. 20 The pneumatic device comprises a tubular chamber and the can ends are fed edge-wise into this chamber from one side. . Vacuum is generally applied through the walls of the chamber at a position distant from the inlet end and this results in the can ends being pulled 25 into the chamber, substantially coaxial with the chamber. An advantage of aerodynamic stackers is that they work satisfactorily at very high production rates, for instance with the conveyor operating at about 230 metres per minute.

The intention during lining is to ensure that the lined composition is solely within the rim around the can end and is uniformly distributed across the channel of the rim, with the majority of the composition being deposited in the curl. It is necessary that this distribution is not destroyed during stacking. Aerodynamic stackers have proved to be effective for stacking, without destroying this uniform distribution, when the lined composition is based on organic solvent or is an 2 00 aqueous composition made by redispersing polymeric material.

With the increasing usage now of latex based compositions it has become desirable to be able to stack 5 can ends lined with latex based compositions using aerodynamic stackers. Thus it is desirable to be able to convert an existing production line, that includes an aerodynamic stacker and that was previously used with solvent based compositions, to latex based compositions. 10 Also it would be desirable to be able to introduce new production lines that use latex based compositions in -combination with aerodynamic stackers.

Before supplying a composition for a particular use it is normal to conduct laboratory testing that is 15 designed to simulate commercial use, and such tests with latex based compositions suggested that they would be suitable for aerodynamic stacking. Unfortunately it has been found in commercial practice that unsatisfactory results occur when a latex based composition is lined 20 onto can ends which are then stacked by an aerodynamic stacker. In particular it is found that there is a significant tendency for the latex composition to overflow onto the outside of the curl, for the distribution in the channel to be uneven, and for bubbling of the composition 25 in the channel and curl to occur ..especially when the ends were heated before lining.

It was particularly surprising that these problems were encountered since we had never observed them in the laboratory tests involved in the initial formulation 30 of the compositions. We concluded that the fault resided either in the heating conditions used for heating the can ends or in the formulation of the composition, and we made many modifications to the compositions, for instance increasing their viscosity, and in the heating 35 conditions in an attempt at overcoming the problem.

We found that these various modifications did minimise the problem but did not, in our view, totally solve it. We then surprisingly found that the problem could be 2 008 12 4 totally eliminated by appropriate modification of the aerodynamic stacker itself.

A device according to the invention for stacking in face-wise alignment can ends carried to the device in 5 edge-wise alignment by a conveyor comprises a substantially tubular chamber, a side inlet into the chamber through which the can ends may be fed edge-wise by the conveyor, a deflector surface substantially radially opposite the side inlet and against which the can ends make impact, 10 pneumatic repositioning means for repositioning in face- wise alignment in the chamber the can ends received through the inlet, and withdrawal means for withdrawing stacked can ends from the chamber,, and in this device the deflector surface is constructed to minimise the impulsive forces 15 on the can ends when they are deflected by the deflector . surface.

The invention is based on the surprising observation that when the can ends enter the pneumatic chamber of the stacker from one side of the chamber they cross 20 the chamber and strike the opposite side, which we term Lthe deflector surface, with sufficient impulsive forces • to disrupt the uniform and partially solidified lining in the channel and curl of the can ends. The modification of the deflector surface minimises these radially acting 25 impulsive forces and can also reduce the axially acting impulsive forces encountered as the can ends are forced axially into the stack of can ends. As a result all these forces can be reduced to such an extent that the lining is not disrupted and the can ends maintain the 30 desired uniform lining even when they are being stacked at the high speeds at which aerodynamic stackers can operate.

The deflector surface may be parallel to the axis of the pneumatic chamber and may be formed of 35 resilient material, the resilience of the surface being such as to achieve the necessary reduction in impulsive forces. For instance the chamber is usually formed of steel or other rigid material and a flexible, steel -leaf spring or other resilient material may be fitted 2 :00 8; \ along the deflector surface.

Preferably the apparatus is provided with a deflector surface that is at an acute angle to the axis of the pneumatic chamber. Such, a surface can be rigid, relying solely upon the reduction in incidence angle for reducing the impulsive forces, but preferably also is resilient. Best results are achieved by providing means for adjusting the acute angle, so that the angle can be adjusted during use to obtain optimum results.

The pneumatic repositioning means in the chamber generally include outlet ports through the walls of the chamber at a position distant from the inlet and through which suction may be applied to pull the can ends into the chamber in face-wise alignment.

The withdrawal means for withdrawing stacked can ends from the chamber may comprise merely the open end of the chamber but generally include a trough for receiving stacked can ends from the chamber. The withdrawal means generally also comprise driving means in the chamber for mechanically advancing stacked can ends away from the inlet, for instance a pair of wheels having flexibly mounted cogs, one wheel in each side of the chamber, generally as described in British Patent Specification No. 1,039,064.

The conveyor preferably feeds the can ends edgewise upwardly towards the pneumatic chamber in which event there may be a nose portion overhanging the side inlet and the deflector surface may be over part or all of this nose portion.

Although the invention is most-conveniently applied by fitting an appropriate deflector member onto the tubular rigid walls of a conventional pneumatic tubular chamber the invention naturally also includes apparatus in which the tubular chamber is initially constructed with its deflector surface formed at an angle and/or of material such that the impulsive forces on the can ends are less than they would be if the 2 00812 6 deflector surface was of conventional rigid construction coaxial with the chamber.

The invention also includes apparatus including both the described device and a conveyor for supplying . the can ends in edge-wise alignment to the inlet to the tubular chamber. It also includes a method .of lining and stacking can ends comprising lining the can ends • with a latex based liquid composition and stacking them, while the composition is still liquid, by means of the described stacking device, and then completing curing of the composition. The ends are preferably heated before lining.

The invention is illustrated in the accompanying drawings in.which Figure 1 is a diagrammatic cross-section of. -an aerodynamic stacker to which the invention may be applied and Figures 2, 3 and 4 are enlarged views of part of this apparatus modified in three different ways in accordance with the invention.

The aerodynamic stacker shown in Figure 1 is similar to that illustrated in British Patent Specification No. 1,039,064 except that it stacks upwards rather than downwards. Thus the stacker comprises a conveyor 1 by which can ends 2 can be transported edge-wise at high speed, for instance 230 metres per minute, to a pneumatic device 3 that leads to a trough 4.

The pneumatic device 3 comprises a tubular chamber 5 that is open at each end and which has a side inlet 6 for the can ends, thereby resulting in an overhanging nose portion 7.

One or more ports 8 are provided in the walls of the chamber for applying suction by means of appropriate devices (not illustrated) in a box 9 that surrounds the sides and base of the chamber 5. This suction results in the can ends 2 being pulled coaxially into the chamber but they strike the upper surface 10 of the nose portion and are deflected by this surface.

To assist the stacking of the can ends a pair of wheels 11 are provided, each extending through an. aperture 24 in opposite sides of the tubular chamber. The wheels have flexibly mounted cogs 25 and are driven by rotating shafts 26. The can ends are forced by suction onto the cogs and the wheels are rotated by the.shafts . 5 26 so as to force the can ends into a stack 12 and to force this stack along the trough 4. The cogged wheels 11 are preferably driven and mounted by a flexible transmission, for instance as described in British Patent Specification No. 1,039,064.

The trough 4 may be substantially cylindrical or may be open along part or all of its length and may be of any shape suitable for receiving the stack of can ends, for instance as described in Specification No. 1,039,064. The tubular chamber 5 and trough 4 may be 15 of uniform diameter or the chamber may taper slightly generally having its greatest diameter at the inlet end.

In the modification according to the invention . shown in Figure 2 a spring steel leaf 13 is fitted around the nose portion in a position radially opposite the 20 inlet 6, so as to provide a resilient deflector surface 10 substantially coaxial with the tubular chamber 5.

Although the modification of Figure 2 gives improved results with many compositions more reproducible improvement is obtained using inclined deflector surfaces, 25 as shown in Figures 3 and 4.

In Figure 3 the deflector surface 10 is inclined at an acute angle to the axis of the chamber 5 and is provided by a thin layer of wear resistant material 14 (for instance unfoamed rubber) backed 30 .by wedges 15, 16 and 17 of foamed rubber, thereby providing a resilient inclined deflector surface 10. The surface 14 may be flat or may be .curved, at least in the area where the can ends strike it.

The assembly may be secured to the wall of the. 35 tubular chamber by any suitable means, including for instance screws or adhesive at points 22 and,23.

In the modification shown in Figure 4 the 2 008 1 deflector surface 10 is provided with means for adjusting its angle of inclination to the axis of the chamber 5 . The surface 10 is again provided by a wear resistant . material 14 backed by foam rubber or other resilient 5 foam or other material 15, thereby providing a resilient deflector surface 10. In order that the angle is adjustable a framework, shown diagrammatically as 18,./ is fitted on the nose portion 7 and a bolt 19 extends from a backing 20 secured to the deflector through the 10 framework 18 to an adjustable nut 21. The surface 14 is secured to the wall of the chamber at 22 as previously.

In use the angle of the surface 10 can be controlled merely by adjustment of the nut 21 to what-15 ever angle gives the best results with the particular composition and lining conditions being used.

Claims (16)

2 0 what i/we claim IS: 9

1. A device for stacking in face-wise alignment can ends carried to the device in edge-wise alignment .. by a conveyor and comprising a substantially tubular chamber, a side inlet into the chamber through which the can ends may be fed edge-wise by the conveyor, a deflector surface substantially radially opposite the side inlet and. against which the can ends make impact, pneumatic repositioning means for repositioning in face-wise alignment in the chamber the can ends received through the inlet, and withdrawal means for withdrawing stacked can ends from the chamber, and in which the deflector surface is constructed to minimise the impulsive forces on the can ends when they are deflected by the deflector surface.

2. A device according to claim 1 in which the deflector surface is provided by a deflector member that is fitted onto the inner wall of the tubular chamber.

3. A device according to claim 1 or claim 2 in which the deflector surface is substantially parallel to the axis of the chamber and is provided by the surface of a resilient deflector member.

4. A device according to claim 1 or claim 2 in which the deflector surface is at an acute angle to the axis of the chamber.

5. A device according to claim 4 including means for adjusting the.said acute angle.

6. A device according to claim 4 or claim 5 in which the deflector surface is the surface of a resilient 1° . •• deflector member.

7. A device according to claim 3 or claim 6 in which the resilient deflector member is a leaf spring.

8. A device according to claim 3 or ..claim 6 in which the resilient deflector member has a deflector surface formed of resilient wear resistant material backed by resilient foamed material. / .

9. A device according to claim 8 in which the resilient deflector member comprises a deflector surface, of unfoamed rubber backed by foamed rubber.

10. A device according to any preceding claim in which the repositioning means comprise, outlet ports through the chamber at a position distant from the inlet and through which suction may be applied to pull the can ends into the chamber in face-wise alignment.

11. A device according to any preceding claim in which the withdrawal means comprise driving means in the chamber for. mechanically advancing stacked can ends away from the inlet.

12. A device according to any preceding claim in which the withdrawal means comprise a trough for receiving stacked can ends from the chamber.

13. A device according to any preceding claim including also the conveyor positioned to feed the can ends in edge-wise alignment through the side inlet.

14. A method in which a stack of lined can ends is provided by lining the can ends with a latex based composition and then stacking them while.the composition is still liquid using a device according to any preceding claim-.

15. . A device as claimed in any one of claims 1 to.13, substantially as hereinbefore described with reference . to any of the accompanying drawings.

16.. A method as claimed in claim 14 when performed substantially as hereinbefore described with reference to any of the accompanying drawings. DATED THIS i ^ day of „,-v. • k j. park & son "iJUNiigjf' t&JZfy&s&k agents fob the applicants