GB2378674A - Deformation of thin walled bodies - Google Patents

Abstract

A thin walled body such as a container is gripped at a holding station and tooling is engaged to deform the wall of the body at a predetermined zone. The predetermined wall zone is co-aligned with the tooling by means of coordinated movement of the tooling (typically by means of rotation about a tooling axis) prior to engagement with the wall zone.

Description

Deformation Of Thin walled Bodies The present invention relates to

deformation of generally 5 thin walled bodies, 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) 10 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 20 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

25 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

30 in, for example, WO-A-9803280, WO-A-9803279, WO-A-9721505 and WO-A9515227. Commonly in such techniques the

-2 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.

An improved technique has now been devised.

According to a first aspect, the present invention provides a method of deforming a thin walled body, the method 10 comprising: i) holding the body gripped securely at a holding station; 15 ii) engaging tooling to deform the wall of the body at a predetermined wall zone, the tooling being provided at a tooling station which is adjacent the holding station during deformation; 20 wherein the predetermined wall zone is co-aligned with the tooling by means of co-ordinated movement of the tooling prior to deforming engagement with the wall of the body.

25 According to a further aspect, the invention provides apparatus for deforming a thin walled body, the apparatus including: i) a holding station for holding the body gripped 30 securely;

-3 ii) a tooling station including tooling to deform the body at a predetermined wall zone of the body, the tooling station being positioned at a location adjacent the holding station during 5 deformation; iii) determination means for determining the orientation of the cylindrical body relative to a reference (datum) situation; iv) means for coordinated movement to reconfigure the tooling to co-align with the predetermined wall zone prior to deforming engagement of the tooling with the body.

Co-alignment of the tooling and the wall zone of the body is typically 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, 20 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.

25 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 30 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 5 cylindrical and the deformed embossed zone will be co-

ordinated 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 10 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 20 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 25 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 30 clockwise or anti-clockwise following sensing of the container orientation and shortest route to the datum

-5- position is particularly advantageous in achieving the process duration times required.

According to a further aspect, the invention provides 5 apparatus for use in deforming a wall zone of a thin walled container, the apparatus comprising internal tooling to be positioned internally of the container, and external tooling to be positioned externally of the container, the external and internal tooling co-operating in a forming 10 operation to deform the wall zone of the container, the internal tooling being moveable toward and away from the centreline or axis of the container between a retraction/insertion tooling configuration in which the internal tool can be inserted or retracted from the 15 interior of the container, to a wall engaging configuration for effecting deforming of the wall zone.

Correspondingly a further aspect of the invention provides a method of deforming a thin walled container, the method 20 comprising: inserting internal tooling into the interior of the container, the internal tooling being in a first, insertion configuration for insertion; moving the tooling to a second, (preferably expanded) position or configuration closely adjacent or engaging the internal container wall so as to facilitate deformation of a wall zone of the container; returning the tooling from the second position toward

-6- the first tooling configuration thereby to permit retraction of the internal tooling from the container.

Because the internal tooling is movable toward and away 5 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 lO (embossing) and therefore typically only slight clearance between the internal tool diameter and the internal diameter of the container has been the standard practice.

In accordance with the broadest aspect of the invention, 15 the relief pattern for embossing may be carried on cam portions of internal and/or external tools, the eccentric rotation causing the cam portions to matingly emboss the relevant portion of the container wall.

20 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 25 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 30 internal tooling provides that greater depth/height embossing formations can be provided, the internal tooling

-7- being collapsed from engagement with the embossed zone and subsequently retracted axially from the interior of the container. 5 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.

According to a further aspect, the invention provides 10 apparatus for use in deforming the cylindrical wall of a thin walled cylindrical container, the apparatus comprising an internal tooling part to be positioned internally of the container, and an external tooling part to be positioned externally of the container, the external and internal 15 tools co-operating in a forming operation to deform a portion of the cylindrical container wall therebetween; wherein tooling actuation means is provided such that: (a) the external and internal tools are movable 20 independently of one another to deform the container wall; and/or (b) deforming force applied to the external and internal tools is positioned at force action zones spaced at opposed sides of the zone of the 25 container wall to be deformed.

As described above, the technique of the invention is particularly suited to embossing containers having relatively thick wall thickness dimensions (for example in 30 the range 0.35mm to 0.8mm). Such thick walled cans are suitable for containing pressurised aerosol consumable

-8 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 5 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) 10 provided with protective/anticorrosive internal coatings or layers without damage to the internal coating or layer.

According to a further aspect, the invention therefore provides an embossed container or tube-form product/ the 15 product comprising a product side-wall having a thickness substantially in the range 0.25mm to 0.8mm and a registered embossed wall zone, the embossed deformation having an emboss form depth/height dimension substantially in the range 0. 3mm to 1.2mm or above.

Preferred features of the invention are defined in the appended claims and readily apparent from the following description. The various features identified and defined

as separate aspects herein are also mutually beneficial and 25 may be beneficially included in combination with one another. The invention will now be further described in a specific embodiment, by way of example only, and with reference to 30 the accompanying drawings, in which:

- 9 - Figure 1 is a flow diagram of a process according to the invention; Figure 2 is a view of a container to be operated upon in 5 accordance with the invention; Figure 3 is a side view of the container of figure 2 in a finish formed state; lo Figure 4 is a 360 degree view of a positional code in accordance with the invention; Figure 5 is a schematic side view of apparatus in accordance with the invention; Figures 6 and 7 are half plan views of apparatus components of figure 5; Figures 8,9 and 10 correspond to the views of figures 5,6 20 and 7 with components in a different operational orientation; Figure 11 is a schematic close up sectional view of the apparatus of the preceding figures in a first stage of the 25 forming process; Figure lla is a detail view of the forming tools and the container wall in the stage of operation of figure 11; 30 Figures 12, 12a to 16,16a correspond to the views of figures 11 and lla; and

- 1 0 Figure 17 is a schematic sectional view of an embossed zone of a container wall in accordance with the invention.

Referring to the drawings the apparatus and technique is 5 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 10 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 15 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 20 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 25 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 30 orientations, each being received in a respective chuck 4, securely clamped about the container base 5.

-11 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 5 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 10 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 flqure 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 20 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.

25 In accordance with the invention, in addition to the necking/shoulderforming tooling at stations 7, the tooling table carries embossing soling lO at an embossing station 9. The embossing tooling (shown most clearly in figures 11 to 16) comprises inner forming tool parts lla, llb of 30 respective arms 11 of an expandible internal tool mandrel 15. Tool parts lla, llb carry respective female embossing

-12 formations 12.

The embossing tooling 10 also includes a respective outer tool arrangement including respective arms 13 carrying 5 tooling parts 13a, 13b having complementary male embossing formations 14. In moving to the table 7 advanced position the respective internal tool parts lla, llb are positioned internally of the container spaced adjacently the container 1 wall; the respective external tool parts 13a, 13b are 10 positioned externally of the container spaced adjacently the container 1 wall.

The internal mandrel 15 is expandible to move the tooling parts lla, llb to a relatively spaced apart position in 15 which they abut the internal wall of the container 1 (see figure 12) from the collapsed position shown in figure 11 (tools lla, llb spaced from the internal wall of the container 1). An elongate actuator rod 16 is movable in a longitudinal direction to effect expansion and 20 contraction of the mandrel 15 and consequent movement apart and toward one another of the tool parts lla, llb. 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 25 against sloping wedge surfaces 65 of the tool parts lla, llb to cause expansion (moving apart) of the tool parts lla, lib. 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 5 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 10 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 15 (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 20 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 25 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

-14 mandrel 15 is expanded by moving actuator rod 16 in the direction of arrow A causing the internal tooling parts lla to lie against the internal circumferential wall of cylinder 1, adopting the configuration shown in figures 12, 5 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 10 1 wall into respective complementary receiving formations 12 on the internal tooling parts lla.

The deforming tooling parts lla, 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 lla 20 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 25 tooling and the sloping (or wedge) cam surface of internal tooling parts lla (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 30 cam force action on the outer tool parts 13a is rearward of the embossing formations 14; the internal cam force action

-15 on the inner tool parts lla 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 soling to flex outwardly to their normal position. In so doing tooling parts 13a disengage from embossing engagement with the 10 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 lla out of abutment with 15 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 20 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. It is however 25 feasible to utilise rotational external/internal embossing tooling as is known generally in the prior art.

The rotary table is then indexed rotationally moving the embossed container to adjacent with the next tooling 30 station 7, and bringing a fresh container into alignment with the embossing tooling 10 at station 9.

-16 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 lo to a 5 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 File position of a respective container 1 whilst already securely clamped in a chuck 4 of the rotary table 3, and rotationally reorientating the 15 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 20 random axial rotational orientations. Moving parts for the apparatus are therefore minimized in number, and reliability of the apparatus is optimized.

The open ends 8 of undeformed containers 1 approaching the 25 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 30 sequence.

-17 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 5 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 10 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 15 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 lO provides the shortest route to the datum 20 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 COD 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 30 small proportion of the code only (for example two adjacent blocks 32 can have a large number of unique coded

-18 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 5 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.

20 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 30 sensed.

- 1 9 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 5 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.

10 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 pressurized aerosol dispensed consumer products which has not been 15 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 20 consumer product). The present invention enables such containers to be embossed (particularly registered embossed). As an alternative to the technique described above in which 25 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 30 container 1 differs from the desired datum pre-set situation programmed into the system, then the container is

-20 rotated automatically about its longitudinal axis to bring the container l 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 5 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 co-

ordinated. There is, thereafter, no requirement to adjust the relative position of the container and tooling. This 10 technique is however less preferred than the technique primarily described herein in which the embossing tooling lo is re-orientated.

The invention has primarily been described with respect to 15 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 20 other material such as steel, steel tinplate, lacquered plasticized metalliccontainer materials an other non-

ferrous or non-metallic materials.

Claims (1)

1. -21 Claims:

   A method of deforming a thin walled body, the method 5 comprising: (i) holding the body gripped securely in a holding station; 10 (ii) whilst gripped in the holding station engaging tooling to deform the circumferential wall of the body at a predetermined wall zone, the tooling being provided at a tooling station which is adjacent the holding station during 15 deformation; wherein the predetermined wall zone is co- aligned with the tooling by rotation of the body about an axis prior to securing at the holding station.

   2. A method according to claim 1, wherein the body is gripped nonrotatably in the holding station.

   A method according to claim 1 or claim 2, wherein the 25 body is optically viewed to determine its orientation relative to a datum and subsequently rotated about said axis to a datum orientation; with the body in the datum orientation, the body is inserted into a clamp of the holding station.

   -22 4. Apparatus tor deforming a thin walled body, the apparatus including: i) a holding station for holding the body gripped 5 securely; ii) a tooling station including tooling to deform the body at a predetermined wall zone on the circumferential wall, the tooling station being 10 positioned at a location adjacent the holding station during deformation; iii) determination means for determining the orientation of the cylindrical body relative to 15 a reference datum situation; iv) means for co-ordinated movement to reconfigure the body about an axis of the body to accord with the datum situation prior to the body 20 being gripped at the holding station.

   5. Apparatus according to claim 4, wherein the body is gripped nonrotatably at the holding station.

   25 6. Apparatus according to claim 4 or claim 5 including optical viewing means to determine the orientation of the body relative to the datum situation.