The present invention relates to an apparatus and a method for deforming a predetermined wall zone of a thin walled container, particularly thin walled containers or tube-form bodies which may be of cylindrical or other form.
The invention is particularly suited to embossing of thin walled metallic bodies (particularly aluminium containers) by embossing or the like. More specifically the invention may be used in processes such as registered embossing of thin walled bodies, particularly registered embossing of containers having pre-applied (pre-printed) surface decoration.
It is known to be desirable to deform by embossing or the like the external cylindrical walls of metallic containers such as aluminium containers. In particular attempts have been made to emboss the walls of containers at predetermined locations to complement a printed design on the external surface of such a container. In such techniques it is important to coordinate the embossing tooling with the preprinted design on the container wall. Prior art proposals disclose the use of a scanning system to identify the position of the container relative to a datum position and reorientation of the container to conform to the datum position.
Prior art embossing techniques and apparatus are disclosed in, for example, WO-A-9803280, WO-A-9803279, WO-A-9721505 and WO-A-9515227. Commonly in such techniques the container is loaded into an internal tool which acts to support the container and also co-operate with an external tool in order to effect embossing. Such systems have disadvantages, as will become apparent from the following.
Another technique is disclosed in US-A-4487048 in which container bodies are rolled between an inner tool and an outer tool, the body being coaxially retained with respect to the inner tool. The outer tool is radially moved during the deforming (beading) operation and rolled on the inner tool and the intermediately disposed container body.
US-A-3698337 discloses a further technique in which a tubular elastomeric member is positioned within a die contained can body and is pressurised to mold the can body to the shape of the die.
An improved technique has now been devised
According to a first aspect defined in claim 1, the present invention provides apparatus for use in deforming a predetermined wall zone of a thin walled container, the apparatus comprising:
According to a further aspect defined in claim 4, the invention provides a method of deforming a thin walled container at a predetermined wall zone comprising:
Co-alignment of the tooling and the wall zone of the body is required in order to ensure that embossing deformation accurately lines up with pre-printed decoration on the body. In the technique of the present invention, the body is not passed from being supported at a holding station to being supported by the tooling but, by contrast, remains supported at the holding station throughout the deforming process.
Re-configuration of the tooling avoids the requirement for the or each holding or clamping station to have the facility to re-orientate a respective body.
The technique is particularly suited to embossing containers having wall thicknesses(t) in the range 0.25mm to 0.8mm (particularly in the range 0.35mm to 0.6mm). The technique is applicable to containers of aluminium including alloys, steel, tinplate steel, internally polymer laminated or lacquered metallic containers, or containers of other materials. Typically the containers will be cylindrical and the deformed embossed zone will be coordinated with a pre-printed/pre-applied design on the circumferential walls. Typical diameters of containers with which the invention is concerned will be in the range 35mm to 74mm although containers of diameters outside this range are also susceptible to the invention.
Beneficially the tooling will be re-configurable by rotation of the tooling about a rotational tooling axis to co-align with the predetermined wall zone.
The determination means preferably dictates the operation of the tooling rotation means to move/rotate the tooling to the datum position. The determination means preferably determines a shortest rotational path (clockwise or anti-clockwise) to the datum position and triggers rotation of the tooling in the appropriate sense.
The length of time available to perform the steps of re-orientation and deformation is relatively short for typical production runs which may process bodies at speeds of up to 200 containers per minute. Re-orientation of the tooling (particularly by rotation of the tooling about an axis) enables the desired re-orientation to be achieved in the limited time available. The facility to re-orientate clockwise or anti-clockwise following sensing of the container orientation and shortest route to the datum position is particularly advantageous in achieving the process duration times required.
Because the internal tooling is movable toward and away from the container wall (preferably toward and away from the axis/centreline of the container), embossed relief features of greater depth/height can be produced. This is because prior art techniques generally use an internal tool which also serves to hold the container during deformation (embossing) and therefore typically only slight clearance between the internal tool diameter and the internal diameter of the container has been the standard practice.
A particular benefit of the present invention is that it enables a greater area of the container wall (greater dimension in the circumferential direction) to be embossed than is possible with prior art techniques where the emboss design would need to be present on a smaller area of the tool. Rotating/cam-form tooling, for example, has the disadvantage of having only a small potential area for design embossing.
Re-configurable, particularly collapsible/expandable internal tooling provides that greater depth/height embossing formations can be provided, the internal tooling being collapsed from engagement with the embossed zone and subsequently retracted axially from the interior of the container.
Embossed feature depth/height dimensions in the range 0.5mm and above (even 0.6mm to 1.2mm and above) are possible which have not been achievable with prior art techniques.
The external and internal tools may co-operate in a forming operation to deform a portion of the cylindrical container wall therebetween; wherein tooling actuation means is provided such that:
As described above, the technique of the invention is particularly suited to embossing containers having relatively thick wall thickness dimensions (for example in the range 0.35mm to 0.8mm). Such thick walled cans are suitable for containing pressurised aerosol consumable products stored at relatively high pressures. Prior art techniques have not been found to be suitable to successfully emboss such thicker containers, nor to produce the aesthetically pleasing larger dimensioned emboss features as is capable with the present invention (typically in the range 0.3mm to 1.2mm depth/height).
The technique has also made it possible to emboss containers (such as seamless monobloc aluminium containers) provided with protective/anti-corrosive internal coatings or layers without damage to the internal coating or layer.
Preferred features of the invention are defined in the appended claims and readily apparent from the following description.
The invention will now be further described in a specific embodiment, by way of example only, and with reference to the accompanying drawings, in which:
Referring to the drawings the apparatus and technique is directed to plastically deforming (embossing or debossing) the circumferential wall of an aluminium container 1 at a predetermined position relative to a preprinted decorative design on the external container wall. Where the embossing deformation is intended to coincide with the printed decorative design, this is referred to in the art as Registered Embossing.
In the embodiment shown in the drawings, a design 50 comprising a series of three axially spaced arc grooves is to be embossed at 180 degree opposed locations on the container wall (see figure 16a). For aesthetic reasons it is important that the location at which the design 50 is embossed is coordinated with the printed design on the container 1 wall. Coordination of the container 1 axial orientation with the tooling to effect deformation is therefore crucial.
Referring to figures 5 to 7 the forming apparatus 2 comprises a vertically orientated rotary table 3 operated to rotate (about a horizontal axis) in an indexed fashion to successively rotationally advanced locations. Spaced around the periphery of table 3 are a series of container holding stations comprising clamping chucks 4. Containers are delivered in sequence to the table in random axial orientations, each being received in a respective chuck 4, securely clamped about the container base 5.
A vertically orientated forming table 6 faces the rotary table 3 and carries a series of deformation tools at spaced tooling stations 7. Following successive rotary index movements of rotary table 3, table 6 is advanced from a retracted position (figure 5) to an advanced position (figure 8). In moving to the advanced position the respective tools at tooling stations 7 perform forming operations on the container circumferential walls proximate their respective open ends 8. Successive tooling stations 7 perform successive degrees of deformation in the process. This process is well known and used in the prior art and is frequently known as necking. Necked designs of various neck/shoulder profiles such as that shown in figure 3 can be produced.
Necking apparatus typically operates at speeds of up to 200 containers per minute giving a typical working time duration at each forming station in the order of 0.3 seconds. In this time, it is required that the tooling table 6 moves axially to the advanced position, the tooling at a respective station contacts a respective container and deforms one stage in the necking process, and the tooling table 6 is retracted.
In addition to the necking/shoulder-forming tooling at stations 7, the tooling table carries embossing toling 10 at an embossing station 9. The embossing tooling (shown most clearly in figures 11 to 16) comprises inner forming tool parts 11a, 11b of respective arms 11 of an expandible internal tool mandrel 15. Tool parts 11a, 11b carry respective female embossing formations 12.
The embossing tooling 10 also includes a respective outer tool arrangement including respective arms 13 carrying tooling parts 13a, 13b having complementary male embossing formations 14. In moving to the table 7 advanced position the respective internal tool parts 11a, 11b are positioned internally of the container spaced adjacently the container 1 wall; the respective external tool parts 13a,13b are positioned externally of the container spaced adjacently the container 1 wall.
The internal mandrel 15 is expandible to move the tooling parts 11a, 11b to a relatively spaced apart position in which they abut the internal wall of the container 1 (see figure 12) from the collapsed position shown in figure 11 (tools 11a, 11b spaced from the internal wall of the container 1). An elongate actuator rod 16 is movable in a longitudinal direction to effect expansion and contraction of the mandrel 15 and consequent movement apart and toward one another of the tool parts 11a,11b. A the cam head portion 17 of the actuator rod 16 effects expansion of the mandrel 15 as the actuator rod 16 moves in the direction of arrow A. The cam head portion 17 acts against sloping wedge surfaces 65 of the tool parts 11a, 11b to cause expansion (moving apart) of the tool parts 11a, 11b. The resilience of arms 11 biases the mandrel 15 to the closed position as the rod 16 moves in the direction of arrow B.
Outer tool arms 13 are movable toward and away from one another under the influence of closing cam arms 20 of actuator 21 acting on a cam shoulder 13c of respective arms 13. Movement of actuator 21 in the direction of arrow D causes the external tooling parts 13a to be drawn toward one another. Movement of actuator 21 in the direction of arrow E causes the external tool parts 13a to relatively separate. Arms 13 and 11 of the outer tool arrangement and the inner mandrel are retained by cam support ring 22. The arms 11, 13 resiliently flex relative to the support ring 22 as the actuators 21, 16 operate.
As an alternative to the cam/wedge actuation arrangement, other actuators may be used such as hydraulic/pneumatic, electromagnetic (e.g. solenoid actuators) electrical (servo/stepping) motors.
The operation of the embossing tooling is such that the internal mandrel 15 is operable to expand and contract independently of the operation of the external tool parts 13a.
The internal mandrel 15 (comprising arms 11) and the external tooling (comprising arms 13) connected at cam support ring 22, are rotatable relative to table 6, in unison about the axis of mandrel 15. Bearings 25 are provided for this purpose. A servo-motor (or stepping motor) 26 is connected via appropriate gearing to effect controlled rotation of the tooling 10 relative to table 6 in a manner that will be explained in detail later.
With the tooling 10 in the position shown in figure 11, the mandrel 15 is expanded by moving actuator rod 16 in the direction of arrow A causing the internal tooling parts 11a to lie against the internal circumferential wall of cylinder 1, adopting the configuration shown in figures 12, 12a. Next actuator 21 moves in the direction of arrow D causing cam arms 20 to act on cam shoulder 13c and flexing arms 13 toward one another. In so doing the external tooling parts 13a engage the cylindrical wall of container 1, projections 14 deforming the material of the container 1 wall into respective complementary receiving formations 12 on the internal tooling parts 11a.
The deforming tooling parts 11a, 13a, can be hard, tool steel components or formed of other materials. In certain embodiments one or other of the tooling parts may comprise a conformable material such as plastics, polymeric material or the like.
An important feature is that the internal tooling parts 11a support the non deforming parts of the container wall during deformation to form the embossed pattern 50. At this stage in the procedure, the situation is as shown in figures 13, 13a. The configuration and arrangement of the cam arms 20, cam shoulders 13c of the external embossing tooling and the sloping (or wedge) cam surface of internal tooling parts 11a (cooperating with the cam head 17 of rod 16) provide that the embossing force characteristics of the arrangement can be controlled to ensure even embossing over the entire area of the embossed pattern 50. The external cam force action on the outer tool parts 13a is rearward of the embossing formations 14; the internal cam force action on the inner tool parts 11a is forward of the embossing formations 12. The forces balance out to provide a final embossed pattern of consistent depth formations over the entire zone of the embossed pattern 50.
Next actuator 21 returns to its start position (arrow E) permitting the arms 13 of the external toling to flex outwardly to their normal position. In so doing tooling parts 13a disengage from embossing engagement with the container 1 external surface. At this stage in the procedure, the situation is as shown in figures 14, 14a.
The next stage in the procedure is for the internal mandrel to collapse moving tooling parts 11a out of abutment with the internal wall of the cylinder 1. At this stage in the procedure, the situation is as shown in figures 15, 15a.
Finally the tooling table 6 is retracted away from the rotatable table 3 withdrawing the tooling 10 from the container. At this stage in the procedure, the situation is as shown in figures 16, 16a.
In the embodiment described, the movement of the tools to effect embossing is translational only.
The rotary table is then indexed rotationally moving the embossed container to adjacent with the next tooling station 7, and bringing a fresh container into alignment with the embossing tooling 10 at station 9.
The embossing stages described correspond to stages 106 to 112 in the flow diagram of figure 1.
Prior to the approachment of the embossing tooling 10 to a container 1 clamped at table 3 (Figure 11 and stage 106 of figure 1) it is important that the container 1 and tooling 10 are accurately rotationally oriented to ensure that the embossed pattern 50 is accurately positioned with respect to the printed design on the exterior of the container.
According to the present invention this is conveniently achieved by reviewing the position of a respective container 1 whilst already securely clamped in a chuck 4 of the rotary table 3, and rotationally reorientating the embossing tooling 10 to the required position. This technique is particularly convenient and advantageous because a rotational drive of one arrangement (the embossing tooling 10) only is required. Chucks 4 can be fixed relative to the table 3 and receive containers in random axial rotational orientations. Moving parts for the apparatus are therefore minimised in number, and reliability of the apparatus is optimised.
The open ends 8 of undeformed containers 1 approaching the apparatus 2 have margins 30 printed with a coded marking band 31 comprising a series of spaced code blocks or strings 32 (shown most clearly in figure 4). Each code block/string 32 comprises a column of six data point zones coloured dark or light according to a predetermined sequence.
With the container 1 clamped in random orientation in a respective chuck 4 a charge coupled device (CCD) camera 60 views a portion of the code in its field of view. The data corresponding to the viewed code is compared with the data stored in a memory (of controller 70) for the coded band and the position of the can relative to a datum position is ascertained. The degree of rotational realignment required for the embossing tooling 10 to conform to the datum for the respective container is stored in the memory of main apparatus controller 70. When the respective container 10 is indexed to face the embossing tooling 10 the controller instigates rotational repositioning of the tooling 10 to ensure that embossing occurs at the correct zone on the circumferential surface of the container 1. The controller 70 when assessing the angular position of the tooling relative to the angular position to be embossed on the container utilises a decision making routine to decide whether clockwise or counterclockwise rotation of the tooling 10 provides the shortest route to the datum position, and initiates the required sense of rotation of servo-motor 26 accordingly. This is an important feature of the system in enabling rotation of the tooling to be effected in a short enough time-frame to be accommodated within the indexing interval of the rotating table 3.
The coding block 32 system is in effect a binary code and provides that the CCD camera device can accurately and clearly read the code and determine the position of the container relative to the tooling 10 datum by viewing a small proportion of the code only (for example two adjacent blocks 32 can have a large number of unique coded configurations). The coding blocks 32 are made up of vertical data point strings (perpendicular to the direction of extent of the coding band 31) in each of which there are dark and light data point zones (squares). Each vertical block 32 contains six data point zones. This arrangement has benefits over a conventional bar code arrangement, particularly in an industrial environment where there may be variation in light intensity, mechanical vibrations and like.
As can be seen in figure 4, because the tooling 10 in the exemplary embodiment is arranged to emboss the same pattern at 180 degree spacing, the coding band 31 includes a coding block pattern that repeats over 180 degree spans.
The position determination system and control of rotation of the tooling 10 are represented in blocks 102 to 105 of the flow diagram of figure 1.
The coding band 31 can be conveniently printed contemporaneously with the printing of the design on the exterior of the container. Forming of the neck to produce, for example a valve seat 39 (figure 3) obscures the coding band from view in the finished product.
As an alternative to the optical, panoramic visual sensing of the coding band 31, a less preferred technique could be to use an alternative visual mark, or a physical mark (e.g. a deformation in the container wall) to be physically sensed.
Referring to Figure 17, the technique is particularly switched to forming aesthetically pleasing embossed formations 50 of a greater height/depth dimension(d) (typically in the range 0.3mm to 1.2mm) than has been possible with prior art techniques. Additionally, this is possible with containers of greater wall thickness(t) than have been successfully embossed in the past. Prior-art techniques have been successful in embossing aluminium material containers of wall thickness 0.075mm to 0.15mm. The present technique is capable of embossing aluminium containers of wall thickness above 0.15mm, for example even in the range 0.25mm to 0.8mm. The technique is therefore capable of producing embossed containers for pressurised aerosol dispensed consumer products which has not been possible with prior art techniques. Embossed monobloc seamless aluminium material containers are particularly preferred for such pressurised aerosol dispensed products (typically having a delicate internal anti-corrosive coating or layer protecting the container material from the consumer product). The present invention enables such containers to be embossed (particularly registered embossed).
As an alternative to the technique described above in which the embossing tooling is rotated to conform to the datum situation, immediately prior to the container being placed in the chuck 4 and secured, the position of the container may be optically viewed to determine its orientation relative to the datum situation. If the orientation of the container 1 differs from the desired datum pre-set situation programmed into the system, then the container is rotated automatically about its longitudinal axis to bring the container 1 into the pre-set datum position. With the container in the required datum position, the container is inserted automatically into the clamp 4 of the holding station, and clamped securely. In this way the relative circumferential position of the printed design on the container wall, and the position of the tooling is coordinated. There is, thereafter, no requirement to adjust the relative position of the container and tooling. This technique is however less preferred than the technique primarily described herein in which the embossing tooling 10 is re-orientated.
The invention has primarily been described with respect to embossing aluminium containers of relatively thin wall thicknesses (typically substantially in the range 0.25mm to 0.8mm. It will however be readily apparent to those skilled in the art that the essence of the invention will be applicable to embossing thin walled containers/bodies of other material such as steel, steel tinplate, lacquered plasticised metallic container materials an other non-ferrous or non-metallic materials.