Patent Grant
11919063
This invention concerns processes and machines for deforming thin walled tubular bodies, and while not limited to any specific material, is particularly although not exclusively useful in deforming aluminium alloy preforms for containers, and similar items.
A wide range of products, e.g. deodorants and other personal hygiene and grooming products, pharmaceuticals, foods, beverages and even car valeting, household cleaning and polishing products, garden and domestic insecticides, paints and the like, are to an ever increasing extent being packaged in containers formed from aluminium monobloc preforms. These are impact extruded, drawn wall ironed (DWI), or shaped by any other suitable method, to have a closed bottom end and a cylindrical side wall. The open top end of the preform is then shaped and optionally trimmed in a so-called necking machine, to form a neck profile to which a dispensing valve or other closure or dispensing fitment can be fitted. Prior to such shaping, the outside of the preform is painted and/or overprinted with trade dress and product information, and the inside may be coated for compatibility with the contents. To provide for better product differentiation, increased attractiveness to the consumer, and/or improved ergonomics, selected regions of the preform side wall may be pressed outward (embossed), pressed inward (debossed), or otherwise permanently deformed to a non-round shape. Often there is a need to align this selective shaping with the painted/overprinted trade dress. These aligned shaping processes are collectively referred to herein as “registered shaping” (or in the specific cases of aligned embossing/debossing, “registered embossing”).
WO01/58618, EP1214991 and EP1214994 disclose registered embossing carried out using suitably modified necking machines. This is arrangement is efficient; as it does not slow production rates compared to the manufacture of un-embossed containers, and does not add significantly to factory staffing or floor space requirements. The disclosed necking machines include a rotary table for conveying a series of the preforms in steps through the machine. The preforms are carried by the rotary table with their bases inserted into a series of holders spaced apart at the step interval around the circumference of the rotary table. A reciprocating tool table has a number of necking tool stations in alignment with the open ends of preforms carried by the rotary table. As the rotary table is indexed, the tool table is reciprocated towards and away from it at each stationary step. Each tool on the tool table along the conveying direction is arranged to perform a successive rolling/shaping/cutting operation, simultaneously at each reciprocation (i.e. the tools work together in parallel; but in succession as far as an individual preform is concerned, as it is indexed from one tool station to the next). In this way, the open end of each preform is shaped to form the required neck profile. Other parts of each preform may be shaped to a different, but still circular, cross-sectional profile by similar tools in this sequence, in the same way.
The tool table is provided with a registered embossing tool station. Here an embossing tool is brought into and out of operative engagement with each successive preform held by the rotary table, by each successive reciprocation of the tool table. In WO01/58618, EP1214991 and EP1214994 the registered embossing tool station is shown positioned upstream of the necking tools; although this is not critical, so long as suitable access to the container interior by the embossing tool remains. To properly perform the registered embossing, the printing, graphics or trade dress on the outside of the preform (hereafter “printing”, for short) must be properly aligned with the embossing tool. No such alignment is required in a standard necking machine, because all transverse cross-sections of the preform remain circular. In these standard machines, the preforms are therefore supplied to and held in the rotary table with the printing in random orientations. In WO01/58618, EP1214991 and EP1214994, the necking machines are accordingly further adapted: either to provide for controlled rotation of the embossing tool for alignment with the printing; or to provide for controlled rotation of each preform for alignment of its printing with the embossing tool. Such controlled rotation of the preform is carried out by rotation of the containers in the holders, or by rotation of the holders to bring the container into the required rotational orientation.
When required, further registered embossing tools may be provided at other stations on the reciprocating tool table. Besides or instead of embossing tooling, it is also known to provide one or more other tools at the tool stations on the reciprocating tool table, which shape the preform to an out-of-round transverse cross-sectional profile. In order to achieve the desired registered shaping, the preforms and/or these other tools must be suitably rotated relative to each other in the same way as described above for the registered embossing tools.
The orientation of the printing is determined by a sensor which detects at least one mark which is in predetermined register with the printing. The mark may be any mark capable of being sensed automatically by an appropriate sensor. Conveniently, it may be a printed or painted mark applied as part of the printing and therefore inherently consistently in register with it. Such a printed mark is optically sensed, and its position determined and used to control rotation of the or each embossing tool or the corresponding preform, as the case may be, for the proper alignment between the registered shaping tool(s) and the printing, needed to carry out the registered shaping. Where a single mark is used, the preform may be rotated until the mark is sensed, at which point the rotation is either stopped or, if necessary, continued through a predetermined fixed angle and then stopped, in both cases to bring the printing into the desired alignment with the registered shaping tool. In both cases the sensor is conveniently placed in or close to the rotation station in the necking machine. Alternatively, as disclosed in WO01/58618, the sensor may detect a uniquely coded mark in a series of such marks, which enables the orientation of the printing to be detected without rotating the preform relative to the sensor. The direction in which the tool or preform needs to be rotated through the smallest angle for registered shaping, and the size of that angle, can then be determined. This reduces the cycle time for acceptably accurate rotational positioning of the preform or tool. This is an important consideration because necking machines typically operate at speeds of up to 250 containers per minute, giving tool station cycle times of as little as 0.24 seconds. The coded mark sensor may be located in any suitable position in the necking machine, upstream of the rotation station where this is present, or upstream of the registered shaping station(s) otherwise. The sensor can be mounted on the tool table or on a fixed part of the necking machine, positioned to detect the coded markings on the preforms held in the rotary table.
Known registered shaping machines of these kinds can achieve alignment accuracies between the printing and the out-of-round selective deformation produced by the shaping tool, of within +/−4 degrees. While this is satisfactory for many applications, a higher registration accuracy is desirable, particularly in the case of containers provided with detailed printing and correspondingly fine or detailed embossing, in which registration errors are more noticeable.
A further limitation of existing registered shaping machines is that the size and the possible location of the selectively shaped region is somewhat restricted. The registered shaping tool is moved into and out of engagement with the preform by movement of the tool table axially of the preform, with the table being withdrawn between tool operations, to allow indexing of the preforms from station to station by movement of the rotary table. The stroke of the tool table is adapted primarily to the requirements of the necking tool array. This movement may be less than the depth of the preform, so that the registered shaping cannot be applied over the entire axial length of the preform, but is limited instead to those regions closest to the preform open end.
Also, the nature of known registered embossing tooling still limits the region on the preform where satisfactory registered embossing is possible and limits the form and size of the possible deformations. In WO01/58618, the embossing tooling comprises inner and outer forming tool (die) parts each mounted at the end of a resilient arm and urged respectively into inner and outer surfaces of the preform by cams. Complementary ones of the cams respectively engage a rearward shoulder of each inner forming tool part and a forward shoulder of each outer forming tool part, when the tool table moves to its extended, forward position. This moves the inner and outer tool parts into engagement with the preform in a pincer-like action. For debossing (as opposed to embossing), the inner forming tool parts support the non-deforming regions of the preform during deformation. Male portions of the outer forming tool parts then deform the wall of the preform into female portions of the inner forming tool parts. The opposite applies in the case of embossing, with male portions of the inner tool parts deforming the wall of the preform outwardly into female portions of the supporting outer forming tool parts. Where the axial length of the inner and outer forming tool parts is small, the forward and rearward engagement shoulders on these respective parts, together with the resilient mounting arms at their rearward ends, ensures that the pincer-like pressure applied to the preform is sufficiently even along the axial length of the co-operating forming tool parts for satisfactory registered embossing. However, where the axial extent of the forming tool parts is enlarged so as to cover a greater proportion of the length of the preform, controlling the evenness of the forming pressure and movements of the forming tool parts becomes increasingly difficult, without unacceptably increasing the stiffness of the resilient mounting arms. EP 1214991 discloses an embodiment of a registered embossing tool with inner and outer forming tool parts which co-operate with a pincer-like action, and a further embodiment in which an inner supporting tool is moved into and out of engagement with the preform by a pivoting arm, and an eccentrically mounted, rotary outer forming tool which co-operates with the inner supporting tool. U.S. Pat. No. 2,955,556 concerns an hydraulic press tool used in the manufacture of sheet metal cabinets, washing machine casings, electrical drier casings and other products of like nature, by expanding a welded cylinder of sheet metal. An expanding die mechanism includes so-called driver and driven die sections, all actuated by the same hydraulic cylinder. Outer dies surround the expanding die and are operated by one or more further hydraulic rams. One or more yet further hydraulic rams are used to load the sheet metal cylinder into, and unload it from, the tool. The entire tool is therefore large, heavy, and immobile; being supported at floor level and requiring stanchions extending below floor level to provide such support.
Increases in the range of positions on the preform where registered embossing is possible, and in the magnitude of the deformation achievable at positions within this range, are therefore desirable, with respect to the described prior art.
Accordingly, in a first independent aspect, the present invention provides a registered shaping machine comprising:
The registered shaping machine may comprise at least two such reorientation actuators, one of which rotates the preform during one reciprocation of the tool table and/or during one indexing movement of the conveyor, and another of which rotates the preform during another reciprocation of the tool table and/or during another indexing movement of the conveyor. Additionally or alternatively the registered shaping machine may comprise at least one such reorientation actuator, the or each of which rotates a respective such registered shaping tool. In all of these arrangements, the relative rotational motion therefore can take place over a longer time interval. This entails lower maximum rotational speeds, lower angular momentum and lower accelerations/decelerations, which can reduce control errors such as overshoot/undershoot and drive element slippage.
The registered shaping machine may comprise at least two such sensors, with the relative rotation taking place initially to a first accuracy under the control of output from the first sensor, and then to a second accuracy higher than the first accuracy and under the control of output from the second sensor.
The sensor or sensors may be adapted to detect the position of a marker present in each preform. For a faster alignment between each preform and the registered shaping tool, the marker may comprise one in a series of unique physical markers, each individually identifiable by the sensor. The sensor or sensors may comprise an optical sensor and the marker a visible mark. The sensor or sensors may comprise a vision system such as a laser scanner, CCD array, electronic camera or the like but the invention is not restricted thereto.
The registered shaping machine may comprise a further sensor operatively arranged to determine the angular orientation of the preforms in a plane normal to the reciprocation axis after being relatively rotated to the second accuracy and to reject those of the preforms for which this determined angular orientation falls outside a predetermined range. Preforms which are inaccurately oriented for the registered shaping operation are thereby automatically rejected from the machine, e.g. before they reach the tooling.
The at least one reorientation actuator may comprise one or more actuators selected from any of the following types:
A. An actuator operatively arranged to reorient preforms prior to or as they are being loaded onto the conveyor, whereby the loaded preforms are carried by the conveyor in their reoriented state.
B. An actuator having a fixed portion mounted to a fixed part of the machine, the actuator being operatively arranged to reorient successive holders by which the preforms are carried by the conveyor.
C. An actuator comprising a series of actuators mounted to the conveyor and each operatively arranged to reorient a respective holder for carrying a respective one of the series of preforms on the conveyor.
D. An actuator comprising a series of actuators mounted to the conveyor and each operatively arranged to reorient a respective preform (either relative to or together with its holder).
E. An actuator having a fixed portion mounted to a fixed part of the machine, the actuator being operatively arranged to engage and reorient successive preforms on the conveyor (whether relative to or together with their holders) as the conveyor is indexed.
F. An actuator mounted to the tool table and operatively arranged to engage and reorient a successive preform with each reciprocation of the tool table.
G. An actuator operatively arranged to rotate the at least one registered shaping tool in the plane normal to the reciprocation axis.
These types of actuators may be used in any suitable combination, under the control of the outputs of the first and second sensors; for example as follows in Table 1, where “1” denotes control by the first sensor output and “2” denotes control by the second sensor output:
1Two such actuators required, spaced apart by an integer multiple of the indexing displacement and controlled by the first and second sensor outputs, respectively.
2Two such actuators required, spaced apart by an integer multiple of the indexing displacement and controlled by the first and second sensor outputs, respectively.
3Two such actuators required, spaced apart by an integer multiple of the indexing displacement and controlled by the first and second sensor outputs, respectively.
4Two such actuators required, at different tool stations upstream of the registered deformation tool and controlled by the first and second sensor outputs, respectively.
5The two actuators may rotate the tool in two different indexing cycles of the conveyor. Only a single actuator may be provided for the tool, in which case the second sensor may also be omitted.
The invention correspondingly provides a method of deforming preforms using a registered shaping machine, comprising:
The method may allow the shaping to be applied in a predetermined angular position on the preform to an accuracy of 3 degrees or better with a probability of at least 99%, preferably at least 99.9%, more preferably at least 99.98%.
The method may further comprise necking the deformed preforms to form a container body.
The method may further comprise packaging a group of at least 100 of the container bodies for despatch to a filling station.
The improved accuracy of registration allows consistent production runs of container bodies, all having registered shaping within significantly lower error tolerances than has hitherto been achievable using the prior registered shaping methods. Thus the invention correspondingly provides a packaged group of at least 100 contemporaneously or serially manufactured container bodies, each comprising a deformed portion at a predetermined angular position about an axis of the container body and measured relative to a marker on the container body, at least 98.0% of the container bodies having an error of less than 3 degrees in the position of their deformed portion relative to the marker.
In a second independent aspect, the present invention provides a tool for deforming a thin-walled tubular preform, comprising:
The mechanism interconnecting the inner and outer dies allows the tool to be operated by movement of a tool table, without the need for any further actuators. The tool can therefore be made compact enough and yet sufficiently robust to be fitted to the movable tool table of a registered shaping/necking machine, to provide versatile registered embossing/debossing of container preforms. For example, in the simplest case, the inner die moves outwardly while remaining parallel to the preform axis and the outer die moves inwardly while also remaining parallel to the preform axis. However, it is also possible for the inner die to move outwardly to a position in which it lies at an angle to the preform axis, and for the outer die to also move to a position in which it lies either parallel to or at an angle to the preform axis; this angle being the same or different to the angle of the inner die relative to the preform axis. In all cases, there is no freedom for unconstrained tilting movement of either the inner die or the outer die. On the other hand, a wide variety of deformations of the wall of the preform are possible between the co-operating inner and outer dies, repeatably and consistently applied over the entire length of the preform which is inserted between them.
The mechanism by which the inner and outer dies are interconnected may comprise:
The inner actuating member may comprise a draw bar whose movement is arrested by engagement with a machine frame as the tool is extended towards the preform.
Alternatively movement of the inner actuating member may be arrested by engagement of the inner actuating member with the preform or with apparatus in which the preform is held, as the tool is moved towards the preform.
Relative movement of the inner actuating member and the inner die may urge the inner die outwardly away from the preform axis.
Relative movement of the outer die and the frame/housing may urge the outer die inwardly towards the preform axis.
The first clamp mechanism may comprise:
Correspondingly, the second clamp mechanism may comprise:
The inner and outer mechanism portions may take any suitable form capable of providing the required motion conversion, e.g. relatively slidable wedge and cam surfaces; a pin and slot connection; a cam and cam follower roller; parallel, inclined racks and an intermediate toothed roller; a rack and eccentric sector gear; a 1-bar linkage, etc.
Alternatively the mechanism by which the inner and outer dies are interconnected may comprise:
The holder may be connected to a draw bar whose movement is arrested by engagement with a machine frame as the tool is extended towards the preform.
Alternatively movement of the holder may be arrested by engagement of the holder with the preform or with apparatus in which the preform is held, as the tool is moved towards the preform.
Relative movement of the frame/housing inner part and the inner die may urge the inner die outwardly away from the preform axis.
Relative movement of the outer die and the frame/housing outer part may urge the outer die inwardly towards the preform axis.
In this case, the first clamp mechanism may comprise:
Correspondingly, the second clamp mechanism may comprise:
As before, the inner and outer mechanism portions may take any suitable form capable of providing the required motion conversion, e.g. relatively slidable wedge and cam surfaces; a pin and slot connection; a cam and cam follower roller; parallel, inclined racks and an intermediate toothed roller; a rack and eccentric sector gear; a 1-bar linkage, etc.
In any of these deforming tool arrangements, the frame/housing may be mounted to the tool table of an embossing or necking machine, either fixed to reciprocate with it, or mounted via an extensible actuator which has the effect of increasing the deforming tool stroke compared to the tool table stroke, thereby enabling longer/deeper deformation zones in the tubular preform.
The above and other preferred features and advantages of the invention are further explained below with reference to illustrative embodiments shown in the drawings, in which:
Referring to the drawings, the apparatus and technique is directed to plastically deforming (cold forming, e.g. embossing or debossing, or other more general re-shaping to an out-of-round condition) the circumferential wall of a tubular preform 1 for a container (“can”) made for example from aluminium alloy or the like, e.g. as shown in
Referring to
A vertically orientated tool table 6 faces the rotary table 3 and carries a series of deformation tools at spaced tooling stations 7. With each successive rotary step or indexing movement of rotary table 3, tool table 6 is moved horizontally from a retracted position (
Typically a majority of the tools 11 have preform shaping parts which are fixed to the tool table. This is therefore known as “static tooling” (despite the movement of the tool table, and the fact that such tools may have other moving parts). When operating upon oriented preforms, such static tooling may be appropriately configured to produce registered out-of-round deformation, i.e. registered shaping; again optionally performed in successive stages by a number of successive tools 11. The oval flattening 103 at the top of the container 1 shown in
Some tools 11 at one or more of the tooling stations 7 may have relatively moving parts, such as orbital rollers for smoothing circumferential regions of the preform, or for forming circumferential grooves or shoulders. Edge trimming tools with moving parts may also be provided.
Some tools 11 at one or more of the tooling stations 7 (e.g. the station also referenced 9) may be registered embossing tools (also referenced 10 in the illustrative example of
After all shaping operations are complete, the fully formed containers leave the container forming apparatus 2 via transfer device 109 and a takeaway conveyor 110, leading e.g. to a packing line or a filling line.
Container forming apparatus typically operates at speeds of up to 250 containers per minute giving a typical working time duration at each forming station in the order of 0.24 seconds. In this time, it is required that the tool table 6 moves axially to the advanced position (see
Prior to the engagement of the registered embossing tooling or any other registered shaping tooling 11 with a container 1 carried by the table 3, it is important that the container 1 and the tooling concerned are accurately rotationally oriented to ensure that the embossed pattern 102 and/or any other registered shaping such as 103 are accurately positioned with respect to the printed design 50 on the exterior of the container.
This accuracy is improved by carrying out the relative reorientation process over two or more reciprocations of the tool table 6 and/or two or more indexing steps of the rotary table 3 or equivalent conveyor. Registration accuracy may be further improved by checking the position of a respective preform on two (or more) separate occasions prior to operation of the registered embossing tooling 10 or other registered shaping tooling 11. On each occasion, the angular orientation of the preform in the plane normal to the tool table movement axis is checked automatically, and the tooling 11 or the preform 1 or both are then rotated automatically so as to bring the tooling and the printed design 50 into closer registration. The rotation immediately following the first orientation check may bring the tooling and printed design 50 into approximate angular alignment so that, typically, the amount of further rotational movement required to bring the preform 1 and the tooling into close alignment following the second orientation check, is small. Lower rotational speeds, accelerations and decelerations are therefore needed to effect this further rotational movement within the cycle times available during indexing of the rotary table (conveyor) 3 and movement of the tool table 6. This is particularly the case if the two orientation checks and corresponding angular alignment movements take place during successive indexing movements of the rotary table 3 (and thus in successive reciprocation cycles of the tool table 6). Improved alignment accuracy results, as maximum speeds, accelerations and angular momentums are lower, so there is less likelihood of orientation actuator positional overshoot/undershoot, or of significant slippage between the reorientation mechanism and the container (or the registered shaping tool, if applicable).
If desired, further checks and reorientations may be performed similarly on further successive indexing movements of the rotary table (conveyor) 3, for even finer alignment between the registered shaping tooling 11 and the printed design 50. However two separate checking and alignment stages may be adequate in many cases. Following the final realignment and prior to operation of the registered shaping tooling, the orientation of the preform 1 can be checked again a final time, to review whether it is within a permitted tolerance. Out of tolerance preforms can then be rejected.
The first reorientation of the preform 1 relative to the registered shaping tool 11 can conveniently be carried out by a dedicated reorientation actuator F1 (
The second reorientation of the preform 1 relative to the registered shaping tooling 11 can conveniently be carried out by rotationally reorienting the tooling 11 to the required position using a reorientation actuator G (
The orientation of the preforms at the station 114 prior to reorientation (first orientation check) can be sensed by a camera or other suitable sensor 116, carried by the tool table 6 or fixed to the machine frame adjacent to tool station 114. The preform's orientation for moving the registered embossing (or other registered shaping) tool(s) into more accurate alignment with it in the second reorientation (second reorientation check) can be sensed by a further camera or other suitable sensor 118, carried by the tool table 6 or fixed to the machine frame adjacent to the first registered shaping station, e.g. registered embossing tool station 9. The 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. This reorientation scheme corresponds to actuator combination and control arrangement (xxvii) in Table 1 above.
Other reorientation schemes are also feasible, for example including the others shown in Table 1. In arrangement (xxvi) in Table 1, the reorientation actuator(s) G and sensor 118 are omitted, and another reorientation actuator F2 and corresponding sensor 120, are added to the tool table at station 122, upstream of station 114. The two reorientation actuators F1, F2 are in this case similar, except that optionally the gear ratio and/or step angle of the motor is lower in the case of F1 compared to F2, to permit finer (but lower speed) angular adjustment. Similarly, the resolution of sensor 116 (and/or angular displacement determination methodology, see below) may be more accurate than for sensor 120. No reorientation of registered shaping tooling is required, so this scheme is equally convenient for a multi-step (multi-tool) registered shaping process as it is for a single step process.
In arrangement (xxviii), two separate cameras or other suitable sensors 118, 124 control the movement of the reorientation actuator(s) G, which may be a single actuator as schematically shown in
In arrangement (i), rather than the previously described reorientation actuators and cameras/sensors, a first reorientation actuator A1 (
Arrangement (viii) uses Type B actuators, e.g. B1, B2,
The open ends 8 of undeformed container preforms 1 approaching the apparatus 2 have margins 30 printed with a coded marking band 31 (
To perform either the first or the second orientation checks, a suitably positioned electronic 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 (e.g. of a machine controller, not shown) for the coded band and the position of the preform relative to a datum position is ascertained. The degree of rotational realignment required for the registered shaping (e.g. embossing) tooling 10 to conform to the datum for the respective preform is stored in the memory. The controller then instigates rotational repositioning of the preform 1 (or the tooling 10, 11, where applicable), using the corresponding actuator, to ensure that deformation occurs at the correct zone on the circumferential surface of the preform 1. The controller when assessing the angular position of the tooling relative to the angular position to be deformed on the preform utilises a decision making routine to decide whether clockwise or counterclockwise rotation of the preform 1 (or tooling 10/11, if a Type G actuator is concerned) provides the shortest route to the datum position, and initiates the required sense of rotation of the reorientation actuator accordingly. This is an important feature of the system in enabling rotation of the preform or 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 camera device can accurately and clearly read the code and determine the position of the preform 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 e.g. seven 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 the like.
The coding band 31 can be conveniently printed contemporaneously with the printing of the design 50 on the exterior of the preform 1. Forming of the neck feature 39 preferably obscures the coding band from view in the finished product.
When performing the first orientation check, lower accuracy is required than when performing the second orientation check. For the first check the controller may simply determine the coding block which is closest to a datum point (e.g. the centre point along the movement axis in the field of view). The controller may then rotate the preform 1 through the number of angular increments between adjacent coding blocks that would be required to bring that coding block into view closest to the datum point, which corresponds to the correct orientation for registered embossing to take place. (Rotation taking place in the direction of shortest travel to bring about such registration, as explained above). Optionally, the fraction of the inter-block angular increment that the closest block lies away from the datum point prior to rotation, (negative for fractions behind the datum point, positive for fractions beyond the datum point) is determined and added to the calculated number of angular increments. For the second orientation check, the controller may simply check that the expected coding block lies closest to the datum point, and then rotate the preform (or embossing tool 10, if applicable) through the required fraction of the inter-block angular increment to bring the expected coding block to the datum position. If the expected coding block is not found to be closest to the datum point at the beginning of the second orientation check, the required number of inter-block increments has to be added to the fractional increment. A final registration error of less than +/−1 mm, or less than 3 degrees, or even less than +/−0.5 mm, 1.5 degrees can be consistently achieved by these methods and equipment.
An alternative to the optical, panoramic visual sensing of the coding band 31, could be to use an alternative visual mark, or a physical mark (e.g. a deformation or hole in the container wall or an irregularity in the container rim) to be physically sensed.
The illustrated tool 148 comprises two sets of dies for performing the embossing/debossing/shaping operations at two diametrically opposed locations on the preform. More or fewer sets of dies may be provided, engageable with the preform at spaced locations around its circumference, as dictated by particular shaping requirements. The construction and operation of each set of dies is generally similar, so for brevity the following description is mainly confined to one set only. Each die set consists of an inner die 150 and outer die 152, each having a working face patterned with the profile corresponding to the shape that is to be imparted to the preform.
The tool 148 further comprises a draw bar 154 running axially through its centre, coupled to or comprising an inner actuating member 155. A holder 156 is provided, through which the inner actuating member 155 is movable along the same axis along which the preform is inserted into the tool. (In fact, in use the preform 1 is generally held stationary, and the tool is moved to engulf the preform, so here “inserted” and “movable” are used in a relative sense). The holder 156 comprises an upper pair of longitudinally projecting arms 158a, disposed symmetrically on either side of a centre plane of the tool 148 (the plane of the page in
As shown in
Once the inner die 150 contacts the wall of the preform 1, further outward movement is constrained. Continued movement of the holder 156 relative to the inner actuating member 155 would therefore be resisted by the engaged cam and bearing surfaces 178/180a-c. However, to prevent any undesired straining of the preform 1 by the engaged inner dies 150, further forward movement of the holder 156 on the inner actuating member 155 is arrested by a shim washer 157 engageable between co-operating stop shoulders on the draw bar 154 and holder 156.
At the same time as the inner dies are being moved outwardly by the engaged cam and bearing surfaces 178/180a-c, the rollers 192a and 192b press inwardly upon the outer dies 152 via the inclined surfaces 194. The roller 192b therefore overcomes the resistance of the bias springs 166, and the rollers 192a, 192b begin to travel along the inclined surfaces 194 of the wedge blocks 184a, 184b, as shown in
The holder 256 is fixed to the end of the draw bar 254, these two parts preferably being integrally formed as a single component, as shown in
The wedge blocks 174a, 174c are optionally replaced by lands 274a, 274c integrally formed with the central beam 272, to provide the cam surfaces 178. Wedge block 174b may be similarly replaced, or omitted entirely (together with the corresponding inner die pocket and bearing surface 180b).
Operation of the tool 268 is as follows. When the draw bar 254 has grounded on the machine frame, advancement of it, the carrier 256 and the attached dies 150, 152 in the insertion direction, ceases. At this point, the inner die 150 is fully inserted into the preform 1 and the outer die 152 lies next to the corresponding outer surface of the preform 1. The dies at this point are held open and out of contact with the preform by the bias springs 166. As shown in
Because at this point the carrier 256 has ceased to advance, continued advancement of the central beam or frame/housing inner part 272 together with the rest of the frame/housing 268 causes the inner die 150 to move perpendicularly outward along the guide rods 160 (see arrow 300,
The sequence in which the inner and outer dies 150, 152 first begin to move is dictated by the order in which on the one hand the rollers 192a, 192b encounter the inclined surfaces 194 and on the other hand the bearing surfaces 180a, 180c encounter the cam surfaces 178. Appropriate timings can be obtained by suitably adjusting the relative positions of these components along the insertion direction. For example for a debossing operation, it may be preferable to first position the inner die against the inner surface of the preform to support the preform wall (apart from at the female areas of the inner die). The outer die can then be closed against the outer surface of the preform so that the male parts of the outer die impinge on the preform wall and displace it into the female parts of the inner die. Due to the support provided by the inner die, the deformation of the preform wall will then be confined substantially to the male/female die parts, producing clean and precise embossments. On the other hand for an embossing operation, by the same logic, it may be preferable to position the outer die in contact with the preform wall before contacting the preform with the inner die.
In any of the tool arrangements described with reference to
The draw bar 154 may be omitted from the arrangement shown in
The inner and outer dies may be coupled to move with the holder 156, 256 in the insertion/withdrawal direction of the tool by any suitable mechanical coupling which leaves them free to move in the transverse direction, thereby closing upon the preform wall and opening again. The guide ears 162, 164 may for example be replaced by guide blocks formed as separate components to the respective dies 150, 152. These guide blocks slide on the pairs of guide rods 160 or slide in or on any other suitable guide track(s) provided in or on the holder 156. The dies 150, 152 may for example comprise yokes by which they are secured to trunnions on the guide blocks, or comprise another similar hinged connection; in each case providing a pivot axis orthogonal to the plane of movement of the dies. The springs 166 or another suitable resilient biasing element or elements may then be arranged to act between the inner and outer dies, rather than between the guide blocks or the like. Thus, the different ends of a given die may move transversely by different amounts under the action of the first and second unyielding clamp mechanisms respectively. Likewise the leading end (or trailing end) of one die may move transversely by a different amount than the co-operating end of the other die. In this way it is possible to deform a thin-walled tubular preform to a wider variety of shapes than has previously been the case. Such angular movement may also assist in manoeuvring the inner dies into a non-cylindrical (e.g. previously registered shaped) preform.
Hence it is possible to use the tool to emboss/deboss preform walls which have already been formed to a non-cylindrical shape. For example, flared, tapered, convex and concave profiles may be produced both in the circumferential and axial directions of the tubular preform, or at any orientation in between. Such profile shaping may be carried out instead of or as well as embossing or debossing, either in registration with patterns painted, printed or otherwise applied to the exterior surface of the preform, or not.
As illustrated diagrammatically in
| Number | Date | Country | Kind |
|---|---|---|---|
| 1709167 | Jun 2017 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/GB2018/051565 | 6/8/2018 | WO |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2018/224840 | 12/13/2018 | WO | A |
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| Number | Date | Country | |
|---|---|---|---|
| 20200180008 A1 | Jun 2020 | US |
