WO1999036204A1

WO1999036204A1 - Neck rolling apparatus

Info

Publication number: WO1999036204A1
Application number: PCT/GB1999/000066
Authority: WO
Inventors: Clinton John Guest
Original assignee: Presspart Manufacturing Limited
Priority date: 1998-01-16
Filing date: 1999-01-18
Publication date: 1999-07-22
Also published as: GB9800816D0; AU2064799A

Abstract

The invention relates to an apparatus (2) for shaping generally cylindrically shaped objects, (5), for example cans, containers and pipes. The invention is particularly intented for forming necks or other kinds of annular indentations or projections in such objects. The apparatus comprises a rotatable mandrel (6) and a roller (8) the outer periphery of which forms a generally circular rolling surface (9) opposite the mandrel (6), at least a portion of the rolling surface comprising a cam surface (9A) whereby when the roller rotates the distance between the cam surface and the mandrel varies.

Description

NECK ROLLING APPARATUS

Field of the Invention

This invention relates to an apparatus for shaping objects such as cans, containers, pipes and so on by rolling. The invention is particularly, but not exclusively, intended for use, for example, in forming a neck, annular indentation and/or projection in such objects.

Background to the Invention

Many everyday objects such as containers, cans or pipes and other generally cylindrical shaped objects need to be provided with necks or other annular indentations or projections in their curved surfaces. The structures formed on the curved surfaces can be used for gripping or for clamping the object to another object.

A typical example is a can for a medical inhaler. The neck of the can is formed as an annular indentation by rolling or beading the can between a roller and a mandrel . A ferrule carrying a valve for dispensing the medicament can then be crimped onto the neck.

In a conventional neck forming apparatus, a can is lifted up to a mandrel which is slightly smaller than the can itself. A roller is brought up to and positioned against the neck of the can, urging it against the mandrel so as to form the neck of the can into the required shape. Various arms and linkages are required to position the roller with respect to the mandrel and to move it towards the mandrel as it rotates to provide the required amount of deforming force. Also, it takes a certain amount of time to position the can correctly about the mandrel, and to bring the roller up to the can on the mandrel so that the neck of the can can be formed.

When the roller rotates, the can, which is clamped between the roller and the mandrel, also rotates, as does the mandrel. The can is in effect rolled between the roller and the mandrel. The axis of rotation of the roller is moved towards that of the mandrel by the linkages holding the roller so as to urge the roller and mandrel together so deforming the can into the required shape. Once the can has been shaped, the roller is withdrawn, again by means of arms and linkages, releasing the can from the mandrel. This lateral movement of the roller typically results in drive gears of the roller being moved in and out of mesh.

This conventional arrangement suffers from several drawbacks in the time taken per can to perform the forming or rolling operation.

Also, because arms and linkages are necessary to position the roller with respect to the mandrel, inaccuracies in positioning arise at least partially because the gears are moved in and out of mesh during each rolling operation. This has caused a limitation in the number of cans per minute which can be produced and which meet the required technical specification in the shape of the neck. For example, typical machines currently available are limited to the production of around 100 cans per minute. At speeds greater than this the quality of the finished product is compromised. This is a clearly undesirable scenario in a medicament dispensing product.

There is therefore a need to provide an apparatus capable of producing the required shape by rolling to the specified accuracy whilst increasing the number of cans which can be produced per minute.

Summary of the Invention

Accordingly, the invention therefore provides an apparatus for deforming an object by rolling comprising a rotatable mandrel, a roller, the outer periphery of which comprises a generally circular, or part circular, rolling surface opposite the mandrel, at least a portion of the rolling surface comprising a cam surface whereby when the roller rotates the distance between the cam surface and the mandrel varies .

This produces a varying deforming force on the object being rolled between the mandrel and the roller.

In a further aspect of the invention there is provided a roller for deforming an object by rolling it between the roller and a mandrel comprising an outer periphery which forms a generally circular or part circular rolling surface and in which at least a portion of the rolling surface comprises a cam surface whereby when the roller rotates the distance between the cam surface and the axis of rotation of the roller varies.

Preferably, the periphery of the roller is shaped with respect to an object to be rolled such that the object can be introduced between the mandrel and the roller without altering the distance between the axis of rotation of the mandrel and that of the roller.

Preferably, the outer periphery of the roller comprises the rolling surface over a given angular extent and an indentation surface over a further given angular extent whereby an object is rolled as it passes between the rolling surface and the mandrel, but is not rolled if it passes between the indented surface and the mandrel .

Preferably, the rolling surface comprises a recess for receiving the object to be rolled. Preferably, the recess is positioned immediately before the cam surface. Preferably, the apparatus is arranged so that the recess is directly opposite the mandrel before the rolling process begins to allow the object to be introduced inbetween the roller and the mandrel. Preferably, the recess is curved. Preferably, the recess is sized and shaped to correspond to the size and shape of the object to be rolled.

Preferably, the mandrel, roller and cam surface are arranged to provide a decreasing distance between the cam surface and the mandrel when the roller rotates. This provides an increasing deforming force on the object as it is rolled between the mandrel and the cam surface of the roller.

Preferably, the distance of the cam surface from the axis of rotation of the roller increases as a function of the distance along at least part of the cam surface.

Preferably, the distance of the cam surface from the axis of rotation of the roller increases along a first section of the cam surface and is substantially constant along a second section of the cam surface.

Preferably, said distance increases along a third section.

Preferably, the second section follows the first section.

Preferably, the distance of the cam surface from the axis of rotation of the roller increases along the whole extent of the cam surfac .

Preferably, the distance of the cam surface from the axis of rotation of roller as a function of the distance along the cam surface, or section of the cam surface, increases at a variable rate.

Preferably, the rate of increase varies according to simple harmonic motion (SHM) . Preferably the rate of increase of the distance is substantially constant over the cam surface, or over one or more sections of the cam surface (though it may vary from section to section) .

Preferably, the average rate is between around .01 to .05mm per degree. Preferably, the average rate is between around 0.010 to 0.030mm per degree. Preferably, the average rate is between around 0.015 and 0.27mm per degree. Preferably, the average rate of increase is approximately equal to 0.019mm, 0.021mm, 0.024mm 0.026mm, 0.032mm per degree or 0.040mm per degree.

The optimum rate of increase or, where the rate of increase varies, the average rate of increase and indeed variation, will depend on the actual diameter of the roller, the length of the cam surface, the desired number of rotations of the object along the cam surface, the nature of the material forming the object to be rolled ie how easily it deforms, and other parameters known to those skilled in the art.

The rates of increase of 0.024mm, 0.032mm and 0.040mm quoted above are particularly suitable for a metal can of 22mm outside diameter, the metal being of 0.41mm thickness, travelling along a cam surface which extends over roughly 0.3, 0.4 or 0.5, of the periphery of a roller of 176mm diameter. The increasing force on the can as it is rolled between the mandrel and the cam surface of the roller is therefore spread over approximately 3, 4 or 5 rotations of the can. However, it has been found that reducing the number of rotations to around 2 or less during deformation, and/or 2 or less during qualification, improves the shape and consistency of shape of the can.

Preferably, the rolling surface comprises a first section having a constant increase in said distance over approximately 90° or less than 90°

Preferably, the first section is followed by a second section in which said distance is substantially constant over approximately 90° or less than 90°.

Preferably, around 180° of the outer periphery comprises a non-rolling indented portion.

Preferably, the distance from the rotation axis of sections of the outer periphery are blended into one another to provide a smoothly varying outer periphery.

Preferably, the apparatus is arranged so that the roller rotates in a pre-determined manner. Preferably, the roller rotates at a substantially constant speed during rolling.

Preferably, the roller is arranged to rotate at a gradually increasing speed once the start of the cam surface passes opposite the mandrel. Preferably, the speed of the roller decreases as the end of the cam surface approaches a position opposite the mandrel.

Preferably, drive means are provided for driving the roller in the pre-determined manner.

Preferably, the speed of the roller varies in accordance with simple harmonic motion. For example, it may vary in accordance with the simple harmonic motion of a reciprocating transfer slide, the slide being driven by a cam, the outer surface of which varies in simple harmonic motion. Alternatively a stepping motor, or spiral or other suitable means could be used which provides simple harmonic motion. The mandrel may rotate freely but preferably, the mandrel is driven in the same predetermined manner as the roller. The drive means may comprise a rack coupled to the transfer slide, so that the transfer slide not only moves the cans into and out of position but also drives the roller to shape the can. Alternatively rotating drive means such as a driving gear may be used, powered, for example by a separate motor.

Preferably, the cam surface is sized with respect to the object so that the object rotates at least a predetermined number of times as it passes between the rolling surface and the mandrel.

Preferably, the object rotates between 3 and 10 times for one rotation of the roller. Preferably, the object rotates 8 times for one rotation of the roller.

More preferably, the object rotates between 2 and 5 times and even more preferably 4 or just less than 4 for each roller rotation. In one embodiment of the invention, in which the roller is 176 mm in diameter and the can is 22 mm in diameter, the remaining portion of the rolling surface of the roller can account for a further 5, 4 or 3 rotations of the can before the roller, can and mandrel are back to the starting position. The total number of rotations of the can for each rotation of the roller is therefore eight in this preferred embodiment. The mandrel also preferably rotates eight times for one rotation of the roller.

In another embodiment, the object (a can) rotates approximately 1³A times over the cam surface and approximately lV» times over the remainder of the rolling surface .

In a preferred embodiment, the portion of the rolling surface following the cam surface is a substantially constant distance from the axis of rotation of the roller.

Preferably the portion of the rolling surface following the cam surface is sized with respect to the object so that the object undergoes a pre-determined number of rotations as it passes between that portion of the rolling surface and the mandrel .

Preferably, the mandrel is driven at the same speed as the roller.

Preferably, the mandrel is driven in the same pre- determined manner as the roller. For example, the speed of the roller and the mandrel may be constant. Preferably, the roller is a disc.

Preferably, an object is provided and the total increase in distance from the axis of rotation to the cam surface is substantially equal to or just larger than the movement required in the neck of the object.

Detailed description of a preferred embodiment

The present invention will now be described by way of example only with reference to the accompanying drawings .

Figure 1 is a plan view of apparatus for forming a neck in a can in accordance with the invention.

Figure 2 is a side cross-sectional view along AA' of the neck forming apparatus of figure 1.

Figure 3 is a side cross-sectional view along BB ' of the neck forming apparatus of figure 1.

Figures 4A, 4B and 4C are, respectively, plan, side cross- sectional and an enlarged side cross-sectional view of a roller according to the present invention.

Figures 5 and 6 are plan views of alternative rollers according to the present invention.

Figures 7A, 7B and 7C are graphs showing the SHM change in distance of the rollers of figures 4, 5 and 6. Figure 8 is a plan view of an alternative apparatus for deforming a can in accordance with the invention.

Figure 9 is a side cross sectional view along BB ' of the neck forming apparatus of figure 8.

Figure 10 is a close up plan view of the gear train for the apparatus of figure 8.

Figure 11 is a detailed side cross sectional view along AA' of the neck forming apparatus of figure 8 showing in particular the drive mechanism for driving the can roller.

Figure 12 is a plan view of another roller according to the invention, the table shows in detail the radius and the change in radius as a function of angle (every 10°) from the start point at 0°/360°.

Figure 13 shows a plan view, side cross sectional view and close up of another roller according to the invention.

Figure 14 shows a plan view, side sectional view and close up of another roller according to the present invention.

Figure 15A shows a plan view, side sectional view and close up of another roller according to the invention.

Figure 15B shows a plan view of the roller of figure 15A and a table detailing the radius and change in radius over the rolling surface of the roller. Figure 16 shows the plan view, side sectional view and close up of another roller according to invention.

Figure 17A shows a plan view, side sectional view and close up of another roller according to this invention.

Figure 17B shows a plan view of the roller of figure 17A and a table detailing the radius and change in radius as a function of angle (every 10°) for the roller.

Figure 18A shows a plan view, side sectional view and close up of another roller according to the invention.

Figure 18B shows a plan view of the roller of figure 18A the table details the radius and change in radius over the rolling surface. Figure 18B also shows a plan view of a driven gear clamped to the cam roller as shown in figure 11.

Figure 19 shows a cross sectional view of a 19 ml, 21 mm diameter aerosol can.

Referring to figures 1 to 3 , the apparatus for forming a neck in an object by rolling the object is shown at 2. Apparatus 2 comprises a lifting platform 4, which, in this embodiment, is moved by a track cam to lift an object to be shaped by rolling. In this case the object is a can 5.

A mandrel 6 is positioned adjacent to a roller 8 in the form of a disc. Roller 8 has rolling or forming surfaces 9 shaped in cross-section to correspond with cooperating forming surfaces on mandrel 6.

A reciprocating transfer slide transfer 10 brings a can 5 carried in slide transfer fingers (not shown) into position beneath mandrel 6. The fingers carry the can to a first position from a start position, release the can before returning to the start position to collect the next can. The transfer slide reciprocates backwards and forwards in simple harmonic motion. It is driven in such a manner by a shaped cam. Slide 10 is also connected to a parallel rack 12 positioned beneath roller 8. In this embodiment, as slide 10 moves backwards and forwards

(arrow 34) so does rack 12 (arrow 32) driving a tooth gear 14 attached to roller 8 and causing roller 8 to rotate. Drive is transferred via pinion 14 to gear 20. Gear 20 in turn provides drive via a pulley to drive pulley 18 within mandrel housing 16 and so to mandrel 6 (not shown) via the gear box.

Turning to figure 4A, roller 8 is seen in more detail. Roller 8 is, in this preferred embodiment, in the form of a disc with an outer periphery 9 forming a rolling or beading surface. Outer periphery 9 is generally circular in plan view and is divided into sections 9A, 9B and 9C. First section 9A forms a cam surface having a gradually increasing radius D with respect to the central axis of rotation 11 of disc 8. In this particular case, a 176mm diameter disc with a rise of 4.56mm over 190°, in other words an average 0.024mm per degree, is provided. In this case, the rate of rise varies so that the deforming force is less at the start and end of the cam surface than at the middle of cam surface 9A. This is shown more clearly in figure 7A in which the SHM variation in the rise (movement) d over the cam surface is shown as a function of the angular extent of cam surface 9A.

The remainder of the rolling surface forms second section 9B which has a substantially constant radius D with respect to centre 11.

Third section 9C forms a recess in the edge of the disc. Recess 9C connects, in a continuous manner, portions 9B and 9A of the outer periphery of disc roller 8. Recess 9C, preferably, has the same or similar radius of curvature as the forming surface of the mandrel and also preferably of the object to be rolled to allow the object to be introduced in between the roller and the mandrel.

Figure 4B shows the disc in cross-section and figure 4C shows a close up in cross-section of either of the rolling surfaces of sections 9A and 9B of disc 8. The main difference between sections 9A and 9B is the radius of the outer periphery of those sections with respect to the centre 11 of the disc. In section 9A the radius d increases at a variable rate in simple harmonic motion. The average increase is 0.024 per degree over the extent of section 9A, which in angular terms is 190°.

Alternative rollers 8 are shown in figures 5 and 6. The main differences are the length of sections 9A and 9B respectively and the rate of increase of the radius over section 9A. Figures 7B and 7C respectively show the SHM variation of the rise of the cam surface as a function of the angular extent of the cam surface of the rollers of figures 5 and 6. The radius of section 9B is constant in each of the three embodiments. The optimum rates of increase, or decrease, in the radius of the cam surface [the "movement ", d, of the cam surface] will depend on many factors including the radius of the roller and mandrel, the nature of the material of the object to be rolled, the depth, or height, and extent of the indentation or neck to be formed in the object the thickness of the material of the object and its pliability, the speed of rotation of the roller and so on. Indeed Figure 19 shows a typical aerosol can of 19ml volume, 21mm diameter with a required mean neck indentation ("movement" of the neck) of 1.48mm (within tolerance requirements of 1.36mm minimum and 1.60mm maximum. However, the movement over the cam surface of, for example, the roller of Figures 18A and 18B, is selected, in this case to be 1.76mm, to produce the required mean movement of 1.48mm in the neck of the can.

The apparatus works in the following manner. Reciprocating transfer slide 10 carries cans in the direction of arrow 34 in front of the machine. Each can 5 is in turn picked up by fingers on slide 10 (not shown) and positioned beneath mandrel 6 ready for rolling. As slide 10 introduces the can into the machine, rack 12, which is driven in SHM motion by the slide, causes roller 14 to return to a start position so as to receive can 5 in recess 9C. Lifting platform 3 raises can 5 into the gap formed between mandrel 6 and recess 9C of the roller.

When roller 8 rotates, the can is trapped between it and the mandrel . The mandrel is driven at the same speed as the roller and friction causes the can 5, trapped between the roller and the mandrel 6 to rotate at the same speed. Whilst can 5 rotates in a stationary position in the apparatus, in effect, it travels over the outer surface of the roller from recess 9C to the start of cam region 9A as cam region 9A travels to a position opposite mandrel 6.

In this first embodiment, the roller is driven slowly at first so that the effect of the can being pressed between mandrel 6 and roller 8 at the start of cam surface 9A is not too severe so as to deform the can in an undesirable manner. As the roller rotates a little further a different portion of the cam surface is moved opposite the mandrel. In consequence, the mandrel and roller exert a little more force on the can because the distance between the cam surface 9A and the mandrel has decreased ever so slightly and the speed of rotation also increases ever so slightly. The change in distance is shown in figures 7A, 7B and 7C for the rollers of figures 4,5 and 6 respectively. The rotational speed of the roller increases as the can travels over the cam surface and then decreases again as the end of the cam surface approaches a position opposite the mandrel .

In this preferred embodiment, the speed varies in accordance with simple harmonic motion ie increasing then decreasing before settling down to a constant speed as the constant radius portion 9B of the roller passes opposite the mandrel and engages the can.

In this first embodiment, the can rotates several times under the influence of cam surface 9A and mandrel 6 and then it rotates several times again under the influence of constant radius portion 9B of the roller and the mandrel. Portion 9B is called the dwell of the roller, since the can 'dwells' there without being deformed further. Increasing radius cam portion 9A deforms the object into the required shape over mandrel 6. Constant radius portion 9B then serves to further qualify and define the shape which has been formed in the can by the action of the increasing radius of portion 9A. In this particular embodiment the can rotates eight times for each single rotation of the roller. One rotation of the roller fully forms and qualifies the shape of the neck of the can.

Once the roller has completed a single revolution the can passes once again into recess 9C where it is no longer clamped between the mandrel 6 and roller 8. The can therefore drops onto or is now supported by lifting platform 4. Lifting platform 4 drops down again and the next pair of fingers on the slide move backwards to transport the lowered can onto the next stage. The whole process is repeated with the next can in line on the transfer slide.

The use of a roller with the unique shape shown in figures 4A, 5 and 6 has many advantages. The roller does not need to be moved closer to the mandrel in order to exert gradually increasing pressure on the can so as to form the can into the required shape. Rather, this is all achieved by the cam surface which provides a gradually increasing pressure on the can to form the desired shape. The cam surface ideally extends over a portion of the outer periphery of the roller equivalent to at least one rotation of the can. In one embodiment though, the length of the cam surface is equivalent to two or three times the circumference of the can so that the deformation can take place even more gradually.

In another embodiment (see figures 18A and 18B) , the length of the cam surface is equivalent to around two times that of the can circumference. However, the can has to be moved by the cam surface towards the mandrel before it is held in a rolling position between the cam surface and the mandrel so that deformation can take place. Therefore, the effective length of the cam surface is only around lV» times that of the can circumference. Thus, the effective length of the cam surface for a can of a particular size (diameter, and wall thickness) and a roller at a particular distance from the centre of rotation of the mandrel can be less than the actual length of the cam surface. The can is therefore subject to a gentle introduction of the deforming force. This appears to reduce the deleterious effect that the initial contact of the cam and mandrel about the can, can have on the final shape, and indeed consistency of the final shape, of the can.

If the roller of figure 4A is used, the can of 2mm diameter would rotate approximately five times as cam surface 9A passes in front of mandrel 6. If the roller of figure 5 is used the can would rotate approximately four times as cam surface 9A passes in front of the mandrel. If the roller of figure 6 is used, the can would rotate approximately three times as cam surface 9A passes in front of the mandrel .

The precise number of rotations required will depend on the nature of the material forming the can ie how quickly and easily it can be deformed and also the degree of deformation of the can required as well as the desired accuracy of the final product . The length of the remaining periphery of the roller following the cam surface will also depend on the number of revolutions of the can desired for that portion to qualify and further define the shape of the neck in the can.

Typically, the length of the qualifying portion of the roller may be 3 to 3.5 times the circumference of the can.

Of course, the number of rotations for formation over the cam surface or for qualification over the remainder of the rolling surface may exceed the minimum number required, being limited by the need to have a roller of a predetermined diameter. Excessive rolling can however affect the shape of the can and therefore an alternative solution to the problem of providing a roller of given diameter has been found (see the extended recess or indented surface portion 9C of figures 12 to 18B) . It can be seen from figure 2 that one advantage in providing a roller of a relatively large diameter is that sufficient room is provided between the axis of rotation of the roller and the axis of rotation of the mandrel for rack 12 to be positioned parallel to slide 10 and connected to it so to drive the tooth gear 14 mounted beneath the roller. This improves the simplicity of the design of the apparatus. Even when alternative drive means are used, as will be explained with reference to Figure 11, it is still desirable to have sufficient distance between the mandrel and the roller axes for slide 10 and for the gear train passing drive to the pulley in the mandrel housing.

At the end of the forming action by the rolling surfaces 9A and 9B of the roller, the can is delivered back to recess 9C and can drop simply and easily onto the platform. This means that the roller does not have to be withdrawn with respect to the mandrel to allow release of the can. Thus, any gears powering the roller stay in mesh at all times further enhancing the mechanical accuracy of the apparatus and hence of the finished product even when the apparatus is operating at speed. This is a significant advantage of an embodiment of the present invention. It can be seen that recess 9C does not simply join portion 9A to 9B in a straight line but is actually recessed further into roller 8. Nevertheless, a straight edge joining the end of portion 9B to the end of portion 9A could be used though it would work less well .

Figures 8, 9 and 11 show plan and side cross sectional views of an alternative apparatus according to the invention. Like reference numerals refer to like features. In the previous embodiment, slide 10 had been used drive the roller 8. However, the amount of force needed to drive the roller occasionally tripped the dog clutch on the slide mechanism. Therefore, drive is now passed to roller 8 from a separate source by driven gear 14 from driving gear 40. Driving gear 40 is connected to a rotating shaft 42 which transmits drive from sprockets via flexible coupling 44. The gear train 38 is situated in the gear box above the roller. The gear train passes drive via pulley 18A in the gearbox using tooth belt 36 to pulley 18B in the mandrel housing 16.

Whilst the rollers with SHM surfaces 9A shown in Figures 4A, 5 and 6 have overcome many of the problems associated with the known apparatus for rolling cans, in particular the ability to avoid taking gears into and out of contact with one another, some problems with producing the cans were still encountered. In particular when driving these cans under power, the cans produced were, from time to time, found to be oval. This is thought to be due to over rolling and/or the effect if the initial impact of the cam surface on the can.

The fixing methods connecting the roller to the cam shaft was also changed as shown by the holes for countersunk screws and dowels in the roller.

The rollers shown in Figures 12 to 18B show the various rollers that have been developed. The roller of Figure 12 and the rollers of Figures 18A and 18B provided the best results in terms of roundness of the resulting can and consistency in can shape. Furthermore, the apparatus using these rollers is now capable of producing cans at 140 cans per minute. This represents an increase of almost 50% on what was possible before using a conventional neck forming apparatus and between 10 and 30% on the less preferred rollers of the invention of Figures 4, 5 and 6, and 13 to 17.

The part circular, disc shaped roller in Figure 12 was produced by trial and error by hand. The shape of the roller was then determined. It was found that the cam surface had four sections, the first three of which, 9A-1, 9A-2, and 9A-3, incorporated a rise across all the three sections of 2.70mm. The fourth section 9B was of constant radius 88mm over an angular range of around 45 to 50°. The first section 9A-1 of cam surface 9A has a rise of 2.35mm over 90° giving an average rise of 0.26mm per 10° (or 0.33mm per 10° excluding the bend) . The middle section 9A- 2 was in effect a dwell or qualifying section and there was no increase in radius of the cam surface . The remaining section 9A-3 of the cam surface provided a 0.35mm rise over around 60°. The final section 9B of the rolling surface was also a dwell section for qualifying and finalising the can without causing any further indentation.

Section 9C, which in Figures 4, 5 and 6 was simply a curved recess sized and shaped to correspond to an object to be rolled, has been extended significantly in Figures 12 to 18. In effect, section 9C now forms an indented surface which provides a window in the timing of the apparatus so that an object can be introduced into the gap between the mandrel and section 9C at any time when section 9C is opposite the mandrel. This reduces the effect that any inaccuracy in the timing of the press may have on the location of the can between the roller and the mandrel. Furthermore by extending the length of section 9C beyond the minimum required to introduce a can between the roller and the mandrel, the total length of the rolling surface is minimized without having to reduce the diameter of the roller. Thus, the separation of the axes of rotation of the mandrel and the roller can be maintained at an optimum distance without having an extended rolling surface and so without over rolling the can.

It is of note that in the two sections 9A-1 and 9A-3 in the roller of figure 12 in which a rise was provided, the rise was fairly evenly distributed over the length of the section. Thus, the first section was divided into equal increments and the increase in radius was very roughly the same in each increment typically being 0.35mm per 10°. In section 9A-3, the increment was 0.05mm per 10°. It is thought this even rise over the whole section ensures a similar deforming force is applied to the can over its circumference, improving the final shape and consistency of the final shape.

The roller of Figure 13 has an SHM rise of 1.43 over 35° in section 9F . Section 9B is of a constant radius. This roller is not as good as the roller of Figure 12.

The roller of Figure 14 has three sections, the first two 9A-1, 9A-2 providing a rise in equal increments of 2.55mm over 70° and 0.30mm over 121° 30' respectively. The remaining section 9B provides a qualifying dwell over 45° at a radius of 88mm. Little improvement in the speed of the machine or the consistency in the quality of the final rolled product was seen compared to the roller of Figure 12.

The roller of Figure 15A and 15B were divided into three sections 9A-1, 9A-2 and 9A-3. The first section 9A-1 did not divide the increase in radius into equal increments. Three different radii were struck from three different centres to produce the cam surface. In the first section 9A-1 the rise of 0.7521mm over 60° was provided in non- equal increments. In section 9A-2, 0.8058mm rise was provided over 80° in very nearly equal increments. In section 9A-3, 0.1821 rise was provided over 71° 30 seconds in very nearly equal increments. In section 9B a dwell at a radius of 88mm was provided over 45°. Little improvement in speed or shape of can was seen.

The roller of Figure 16 was made using only one radius struck from a single centre position. In section 9A a rise of 1.50mm over 174° 20' in equal increments was provided. Little improvement was seen.

The roller of Figure 17A and Figure 17B roughly divides into three sections 9A-1, 9A-2 and 9A-3 in which the overall rise was kept relatively small compared to the required indentation. The increments in the radius were more or less constant in section 9A-2 and non-equal elsewhere. Very little dwell section was provided. Whilst an improvement was made, a consistent component was still not being made.

The roller of Figures 18A and 18B has only one section 9A having a total rise of 1.761mm over 90°. Thus, the angle over which the rise was provided was reduced and the overall rise ie the total movement over the cam surface was minimised as much as possible relative to the required indentation in the can. The amount of dwell was also limited to 90°. The remaining part of the roller of section 9C extends over 180° giving a much larger window within which the can is inserted between the roller and the mandrel. The start radius in this embodiment is at 270°. The rise in the cam surface immediately prior to 270° pushes the can towards the mandrel. Nevertheless, at 270° the cam surface and mandrel are still not sufficiently close together to apply deforming pressure. Rather, the cam surface very gently increases between 270° to about 255° again very gently pushing the can towards the mandrel. At about 255° deforming pressure starts to be applied to the can.

The increase in rise every 10° is very even over the extent of surface 9A. Whilst the length of surface 9A is equivalent to roughly twice the circumference of the can (thus, the can will rotate roughly twice over surface 9A) , because of the delay in applying deforming pressure to the can, the can undergoes only approximately 1% revolutions being rolled on surface 9A. Surface 9A ends at around 180° and there is a very gentle blend between the rise of surface 9A and the constant radius of surface 9B. The qualifying surface 9B ends just short of 90°. Thus, the can undergoes only around 1% resolutions of dwell before entering section 9C. When the can enters section 9C, it is blown off the mandrel by air into the fingers. It has been found that the shape of the roller in Figure 18B produces very consistent uniformly shaped cans at speeds of up to 140 cans per minute. Indeed, somewhat surprisingly, it has been found that providing a constant rise i.e. increments of equal size over the length of the cam surface has worked well .

Thus, in this improved embodiment the extended window 9C reduces the need for accurate timing within the apparatus. The gentle movement of the can towards the mandrel prior to section 9A and even more gentle movement of the can towards the mandrel at the start of section 9A appears to reduce the impact of the initial contact with the mandrel and the roller on the can. The gentle blend point at 180° also reduces the impact on the can of the change in radius. Furthermore, the provision of a constant rise over the deforming surface 9A ensures that most portions of the can are subject to a similar deforming force though, in this particular embodiment, only 1% revolutions

(approximately) of the can are subject to the deforming force. A qualifying surface of around 1³Λ resolutions in length is provided in section 9B. It can be seen that the last quarter of circumference of the can which is only subject to the deforming force once, passes between section 9B and the mandrel twice and thus is qualified twice. As can be seen in Figure 19, the movement of the roller in Figure 18B is 1.76mm, this provides a mean movement in the can neck of 1.48mm within tolerance limits of 1.36mm to 1.66mm. Thus, the movement in the cam surface is kept to a minimum compared to the required movement in the can neck.

Claims

1. An apparatus for deforming an object by rolling comprising a rotatable mandrel, a roller, the outer periphery of which comprises a generally circular rolling surface opposite the mandrel, at least a portion of the rolling surface comprising a cam surface whereby when the roller rotates the distance between the cam surface and the mandrel varies.

2. A roller for deforming an object by rolling it between the roller and a mandrel comprising an outer periphery which forms a generally circular or partly circular rolling surface and in which at least a portion of the roller surface comprises a cam surface whereby when the roller rotates the distance between the cam surface and the axis of rotation of the roller varies.

3. Apparatus or a roller according to claim 1 or 2 , in which an object is provided and the periphery of the roller is shaped with respect to the object to be rolled such that the object can be introduced between the mandrel and the roller without altering the distance between the axis of rotation of the mandrel and that of the roller.

4. Apparatus or a roller according to claims 1, 2 or 3 in which the outer periphery of the roller comprises the rolling surface over a given angular extent and an indentation surface over a further given angular extent whereby an object is rolled as it passes between the rolling surface and the mandrel, but is not rolled if it passes between the indented surface and the mandrel .

5. Apparatus or a roller according to claim 3 or 4 , in which the periphery comprises a recess for receiving the object to be rolled.

6. Apparatus according to claim 5, in which the recess is positioned immediately before the cam surface.

7. Apparatus according to claim 5 or 6, in which the apparatus is arranged so that the recess is directly opposite the mandrel before the rolling process begins to allow the object to be introduced in between the roller and the mandrel .

8. Apparatus according to claim 5, 6 or 7 , in which the recess is curved.

9. Apparatus according to any of claims 5 to 8 , in which the recess is sized and shaped to correspond to the size and shape of the object to be rolled.

10. Apparatus or a roller according to any preceding claim, in which the mandrel, roller and cam surface are arranged to provide a decreasing distance between the cam surface and the mandrel as the roller rotates with respect to the mandrel .

11. Apparatus or a roller according to any preceding claim, in which the distance of the cam surface from the axis of rotation of the roller increases as a function of the distance along at least part of the cam surface.

12. Apparatus or a roller according to claim 11 in which the distance of the cam surface from the axis of rotation of the roller increases along a first section of the cam surface and is substantially constant along a second section of the cam surface.

13. Apparatus or a roller according to claim 12, in which said distance increases along a third section.

14. Apparatus or a roller according to claim 12 or 13 in which the second section follows the first section.

15. Apparatus or a roller according to claim 11 in which the distance of the cam surface from the axis of rotation of the roller increases along the whole extent of the cam surface .

16. Apparatus or a roller according to any of claims 11-

15. in which the distance of the cam surface from the axis of rotation of roller as a function of the distance along the cam surface, or a section of the cam surface, increases at a variable rate.

17. Apparatus or a roller according to claim 16, in which the rate of increase is less at the start and end of the cam surface or section than in the middle.

18. Apparatus or a roller according to claim 16 or 17, in which the rate of increase varies in accordance with simple harmonic motion.

19. Apparatus or a roller according to any of claims 11 to 18 in which the average rate of increase is approximately equal to 0.024mm per degree, 0.032mm per degree or 0.040mm per degree.

20. Apparatus or a roller according to any of claims 11 to 18 in which the rate of increase is substantially constant over the cam surface or one or more of its sections.

21. Apparatus or a roller according to claim 20 in which the rate of increase is between approximately 0.010 to 0.030 mm per degree.

22. Apparatus or roller according to claim 20 or 21 in which the rolling surface comprises a first section having a constant increase in said distance over approximately 90° or less than 90°

23. Apparatus or a roller according to claim 22, in which the first section is followed by a second section in which said distance is substantially constant over approximately 90° or less than 90°.

24. Apparatus or a roller according to claim 22 or 23 in which around 180° of the outer periphery comprises a non- rolling indented portion.

25. Apparatus or a roller according to any preceding claim in which the distance from the rotation axis of sections of the outer periphery are blended into one another to provide a smoothly varying outer periphery.

26. Apparatus according to any preceding claim, in which the roller is arranged to rotate in a pre-determined manner for example at a constant speed.

27. Apparatus according to claim 26, in which the roller rotates at a gradually increasing speed once the start of the cam surface passes opposite the mandrel .

28. Apparatus according to claim 26 or 27, in which the speed of the roller decreases as the end of the cam surface approaches a position opposite the mandrel.

29. Apparatus according to claim 26, 27 or 28 comprising an elongate drive means for rotating the roller, a reciprocating transfer slide for moving objects through the apparatus and in which the elongate drive means is coupled to and reciprocates with the transfer slide.

30. Apparatus according to claim 26, 27 or 28 comprising a rotating drive means for rotating the roller.

31. Apparatus or a roller according to any preceding claim, in which an object is provided and the roller is sized so that the object rotates at least a predetermined number of times over the rolling surface for a full rotation of the roller.

32. Apparatus or a roller according to claim 31, in which the object rotates between 3 and 10 times for each rotation of the roller.

33. Apparatus or a roller according to claim 32, in which the object rotates 8 times for each rotation of the roller.

34. Apparatus or a roller according to claim 32, in which the object rotates around 4 or just less than 4 times for one rotation of the roller.

35. Apparatus or a roller according to any preceding claim, in which the portion of the rolling surface following the cam surface is a substantially constant distance from the axis of rotation of the roller.

36. Apparatus or a roller according to any preceding claim, in which the cam surface is sized with respect to the object so that the object undergoes a pre-determined number of rotations as it passes between the cam surface and the mandrel .

37. Apparatus or a roller according to any preceding claim, in which the portion of the rolling surface following the cam surface is sized with respect to the object so that the object undergoes a pre-determined number of rotations as it passes between that portion of the rolling surface and the mandrel .

38. Apparatus according to any preceding claim, in which the mandrel is driven at the same speed as the roller.

39. Apparatus according to any preceding claim in which the mandrel is driven in the same pre-determined manner as the roller.

40. Apparatus or a roller according to any preceding claim, in which the roller is a disc.

41. Apparatus or a roller according to any preceding claim in which an object is provided and the total increase in distance from the axis of rotation to the cam surface is substantially equal to or just larger than the movement required in the neck of the object.

42. Apparatus for deforming an object by rolling substantially as described herein with reference to and/or as illustrated in Figures 1 to 20.

43. A roller for deforming an object by rolling substantially as described herein with reference to and/or as illustrated in any of Figures 4A to 6 or any of Figures 12 to 18B.