US 3789785 A
To prevent bursting of a can due to the vacuum formed therein on cooling after sterilisation a part of the can, generally an end thereof, is subjected to a permanent deformation, effected before the can is fully cooled, which reduces the internal volume of the can.
Description (OCR text may contain errors)
United States Patent [191 Petit, deceased et al.
[451 Feb. 5, 1974 STERILISATION OF TINS Inventors:
Maurice Petlt, deceased, late of Paris, France; Georges Thomas,
Ville-D Avray, France Ets J.J. Carnau'd 8L Forges De Basse-Indre, Paris, France Sept. 17, 1971 Related U.S. Application Data Division of Ser. No. 886,585, Dec. 9, 1969, Pat. No. 3,704,140.
U.S. Cl. 113/1 G, 113/120 M Int. Cl B21d 51/26 Field of Search. 1.13/1 R, 120 M, 1 G; 99/214,
References Cited UNITED STATES PATENTS Wilson et al.. 113/120 M Nelson .1 113/120 M 2,258,800 10/1941 Pearlman et al. 113/120 M 2,258,801 10/1941 Pearlman et al. 113/120 M 1,162,520 11/1915 Shaffer 99/214 3,270,544 9/1966 Maeder et 211....
3,117,873 l/1964 Bartels et a1..."
1,918,004 7/1933 Taylor 2,013,654 9/1935 Hothersall 113/1 G FOREIGN PATENTS OR APPLICATIONS 740,699 8/1966 Canada 113/120 M Primary Examiner-Richard J. Herbst Attorney, Agent, or FirmDiller, Brown, Ramik & Wight Y [5 7] ABSTRACT To prevent bursting of a can due to the vacuum formed therein on cooling after sterilisation a part of the can, generally an end thereof, is subjected to a; permanent deformation, effected before the can is fully cooled, which reduces the internal volume of the can.
17 Claims, 11 Drawing Figures PAIENTEU 51974 sum 1 or 4 I FIG] \NVENTORS MnuRm'E PETH' 5p GEORGES THOMAS 2 M 04 I Q I ATTORNEYS PATENTED FEB 51974 SHEET 2 BF 4 Has FIG, 4
INVENTORS MAuszmE pawn- GEORGES THOMAS v i w ATTORNEYS PATENTEB SHEET 3 0F 4 1 STERiLi'SATlQN or TINS 2. Description 'of the Prior Art Qnemeth'od of foodstuff preservation is known as the Al PERT process, or as A'ppertisati'on after the name V ofits inventor Nicolas APPERT, and consists in heating food previously enclosed in a sealed can for a time of sufficient length and to a sufficiently high temperature as to ensure the total destruction or inhibition of the enzymes and micro-organisms, which are liable to cause deterioration of the food or to render it unsuitable or unfit for consumption.
It is also known that when food is preserved in metal cans, which are the containers most widely employed for this purpose throughout the world, once the can has been filled, fitted with its lid and sealed, it is inserted either into a hot-water bath, in the case of foods whose preservation can be assured by'heating to a temperature close to 100 C, or into an autoclave or other appropriate sterilising apparatus which makes it possible to heat the can and its contents to a higher temperature than 100 C, most frequently to a temperature of. between 1 10 and 130 C, but also to even higher temper: atures. v
The temperature and period of sterilisation represent an inseparable factor which is described by the expression sterilisation scale, the period required to ensure the necessary sterilising action being the shorter the higher the temperature, according to mathematical relationships in which the dimensions of the metal can and the nature and consistency of the food play a part.
'Numerous experimental studies have shown that it is of interest in the greater proportion of cases, for optimum retention of the nutritive value and of the organoleptic features of the food as well as for economy, to employ sterilisation scales applying a brief duration at high temperature; this renders it possible to obtain a saving of time during operation, the application of machinery of smaller size for one and the same production figure, and a lower expenditure of thermal energy.
- The fact of heating a can and its contents from the temperature they had at the instant of sealing the can, to a higher temperature, causes an increase in internal pressure; it is essential for the can to oppose-an appropriate resistance against this pressure, without undergoing permanent deformations and without impairing its hermeticity. 1
Consequently, it will be understood that the mechanical strength of the can opposed to the internal pressure represents a limit on the temperature at which it is possible to perform the sterilisation.
.A variety of measures, in respect of the structure of the can, as well as'in the design of the sterilising machinery and in the application of the sterilising operation, render it possible to counteract this difficulty without definite limit one of these measures consists in proceeding in such manner that, at the instant of a can end and most cans have two can ends ,which usually sealing the can, the can and its contents are at as high 7 a temp rature as possible, which cannot exceed C 2, in the case of foods rich in water, placed in cans at atmospheric pressure, but whichmay reach 104 to 105 C for jams, jellies and marmalades, as well as for syrups, and may even exceed this level if the canning operation is performed at a higher pressure'tha'n atmospheric pressure;
The fact of sealing the can when hot, renders it possible to heat the can to a higher sterilising temperature withou exceeding the critical internal pressure; in the point of fact, the final internal pressure is a function of, among other things of the difference between the temperature at the instant of sealing the can and the sterilising temperature.
This remedy entailstwo shortcomings however: sealing in the hot state involves a vacuum being engendered within the can, when the latter cools, which is the more powerful, the higher the sealing temperature has been; on the one hand, this increases the risk of collapsing the cylindricalwall of the can under th'e'action of atmospheric pressure or of even alight knock, and also intensifies the risk of recontamination of the contents of the can in the case of a leak caused by a faulty seam or by deformation of even a faultless seam following impact.
It is an object of the present invention to eliminate these shortcomings by reducing or eliminating the risk of can collapse and product recontamination.
It is also an object of the invention to allow sealing of cans at a temperature close to 100C, or even higher if need be, by initially sterilising them at a high temperature for a very brief period whilst preventing the generation of an excessive internal vacuum and the drawbacks the latter could cause.
Another object is to provide a general improvement in the degree of quality of the products preserved.
Yet another object of the invention is to allow reducing the necessary gauge of the materials to be employed to produce the body and ends of the preserving cans, whilst retaining a degree of quality at least equal to the mean degree obtainable at present.
The invention is not limited to cans of circular crosssection; it is also applicable to cans of other crosssections and to deep-drawn cans.
SUMMARY According to the invention there is provided in a process for sterilising a can comprising at least one deformable wall element in which the can is filled, is sealed in hermetic manner and is heated for a predetermined period to a predetermined.temperature, and is then exposed to a cooling action, the improvement which consists of permanently reducing the internal volume of the can during cooling thereof.
Preferably, at least one deformable wall element is incorporated in the structure of the can for the purpose of a volume reduction of this kind.
The deformable wall element usually consists of a are of slightly concave initial shape. When a can which is filled and then sealed undergoes the sterilising heating action, the progressive rise in pressure has the result of imposing a temporary outward deformation on these deformable elements. During the cooling action, the can ends do not return to their slightly concave initial shape until the internal vacuum has become sufficiently powerful to draw them inwards; the risks of collapsing the wall of the can and of recontamination of the contents occur as early as the cooling stage, being linked to the internal vacuum.
The application of the operation for permanent reduction of the internal volume of the can according to the invention will thus advantageously be performed, according to another feature of the invention, in such manner as to keep the vacuum within a predetermined threshold value.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic section of a part of a filled conventional preserve containing tin or can,
FIG. 2 is a diagrammatic cross-section of apparatus according to the invention,
FIG. 3 is a diagrammatic elevation of a machine embodying apparatus according to the invention and arranged for interposition in a can sterilising line,
FIG. 4 is a diagrammatic cross-section on line IV-IV of FIG. 3,
FIG. 5 illustrates, to an enlarged scale, a detail taken on line VV of FIG. 4,
FIG. 6 is a diagrammatic section of a part of a conventional can end,
FIG. 7 is a view similar to that of FIG. 6 but of a can end comprising a stiffening corrugation and flexible corrugations and illustrates different positions assumed by the can end consecutively during different stages of treatment in accordance with the invention,
FIG. 7A illustrates, to an enlarged scale, the stages of deformation-of a can end according to the invention,
FIG. 8 is an explanatory diagram,
FIG. 9 illustrates the application of the invention to a can provided with a can end of the easy opening type, and
FIG. 10 illustrates the application of the invention to a deep-drawn can.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, FIG. 1 illustrates a conventional can. body 10 of cylindrical shape, provided in conventional manner with can ends 11 and 12. The can is filled to a predetermined level 14 with a product 13. The level 14 may vary from one can to another, leaving a headspace between the can end 12 and the product, which headspace contains air and steam. The product 13 may be in the solid state, in the liquid state, or in both states. The volumes respectively occupied by the product, by the steam, and by air, are each variable as a function of the-temperature. A rise in temperature causes an increase in these volumes, by expansion of the product, by an increase in the vapour pressure and by expansion of the air and of occluded gases. The can ends ll, 12 serve the purpose of withstanding the thrusts caused by these increases in volumes: the deformability of the can ends renders it possible, by passing from a slightly concave initial shape to a more or less convex or domed shape, to have a substantial increase in the internal volume and the consequent retention above the product ofa headspace adequate to limit the pressure strains to permissible values, available for the steam, air and gases.
The contents contract during cooling and the can ends then return substantially to their initial position under the action of the vacuum caused by contraction and, if applicable, of the counter-pressure of a machine by which the can is sterilised.
As has already been stated above, the vacuum generated within the can may reach values which are the greater, the higher the temperature level above ambient at which the filling and sealing of the can has been performed. For the reasons stated, the prevailing tendency is to perform the filling operation at the highest possible temperature, but under the restriction imposed by the risk of collapse caused by the vacuum. This risk varies according to the shape of the can. For example, the risk of collapse is practically absent under the normal conditions for cans having a diameter not exceeding 71.5 mms and a height of l 15 mms, whereas a can having a height of I I8 mms and a diameter of I00 mms may collapse suddenly starting from a relative vacuum of 0.6 bar; and a can having a diameter of I53 mms and a height of 250 mms may collapse suddenly starting from a relative vacuum of 0.2 bar.
Apart from this risk of collapse, recontamination risks arise at the end of or after the sterilising process, especially if the can seams receive knocks which can impair their seal. Knocks are frequent however during and after the sterilising operation and may cause a seepage of cooling water into the can, this water generally not being biologically sterile.
These difficulties are eliminated or greatly reduced by reducing the final volume, that is the reduction obtained by a permanent deformation of at least one of the sides of the can in accordance with the invention, the reduction of the final volume resulting in a reduction or elimination of the vacuum generated by the cooling action. 4
According to one embodiment of the invention, the reduction in the volume of the can is produced by a punching operation performed by mechanical pressure exerted on at least one and preferably both of the can ends.
FIG. 2 illustrates apparatus for applying mechanical pressure to both ends of a can, the apparatus comprising two pressure-applying devices 21 and 22 each of which includes an annular centering portion with a lead-in taper 23, 24 for guiding a can 10 towards two punch elements 25, 26 having a configuration corresponding to that of the appropriate can ends 11, 12. The punch elements advantageously each have an annular pressure-applying face 25A, 26A respectively encircling a recess. Whereas the pressure-applying device 22 is unitary with a reciprocable member 28 (reciprocation being indicated by the doubIe-headed arrow F), the other pressure-applying device 21 is guided in a stationary guide 30 and is carried by rods 31 forming, for example, a part of a pressure limiting device 32 of the compressed air type, arranged to oppose a predetermined resistance against displacement of the rods 31. As shown in FIG. -2 the pressure-applying faces 25A, 26A are outwardly sloping frusto-conical surfaces.
FIGS. 3 to 5 diagrammatically illustrate a machine of a kind known per se, but provided with apparatus as just described with reference to FIG. 2, for applying pressure to the can ends.
Referring to FIGS..3, 4 and 5, a spindle 35 is rotatable in brackets 33, 34 carried by a fame 32. the brackets 33, 34 support two fixed cams 36, 37 and two drums 38, 39 are keyed on the spindle 35 and rotate therewith. Each of the drums 38, 39 are provided with a plurality of pressure-applying heads 40, 41 which rotate with the drums 38, 39. The drums also carry cam follower rollers 42, 43 which respectively co-operate with the earns 36, 37. The heads 40, 41 are axially aligned inpairs and are moved towards and away from each co pressed air to' the devices 32 carried by the drum Iii a machine as illustrated in FIG. 3 which comprises a horizontal spindle 35, cans are fed, as illustrated in FIG. 4, as they issue from a sterilising plant, not shown, and before they are completely cooled following the sterilising operation, gravitationally through a chute or funnel 46, and are received by a rotatable transfer member 47 arranged to move the cans in succession between pairs of heads 40, 41. The cams 36, 37 are arranged to effect the application of pressure to the ends of a can while the can is located in the sector shown at 48 and the release of treated cans occurs at the lower part through a chute or trough 49.
The machine may, if desired, have a vertical spindle and may receive cans fed thereto and removed therefrom in an upright position by means of a conveyor of any suitable kind.
The pressure-limited device 32 may alternatively be operable by spring or by hydraulic pressure or the pressure exerted on the can ends may be produced by direct action of a pressurised fluid on the can ends.
FIG. 6 illustrates the development of the deformation resulting from a mechanical force P on a can end 12 of normal kind in which the pressure causes the can end to deform to a condition as indicated at 12A. The maximum reduction of volume of the can which is thus possible to obtain by permanent deformation the can end close to the end seam is of the order of 3%, or 1.5% for each can end. I
In describing the mode of operation according to the invention, reference will be made to a known kind of can end, British Pat. Specification No. ll70877, indicated at 50 in FIG. 7, and which embodies an annular bead 51 connecting the end seam S3 to an annular stiffening corrugation 54 which in turn is connected to the center panel 53 by at least one flexible corrugation 55. Under the action of mechanical pressure'P, applied in accordance with the invention, a can end of this kind flattens out in final manner to a condition as indicated at'50A thus allowing a considerably greater can volume reduction, which isof the orderof 8 to 107;, or4 to 5% per can end. Starting from the condition 50A, the central areas of the can ends is liable to undergo a further resilient deformation to reach a position such as 508 under the action ofa residual internal vacuum. The line 50C indicates an outward displacement the can end is liable to undergo at the beginning of the sterilising operation under the action of the internal superatmospheric pressure, without permanent deformation and without the risk of unfolding of the end seam 52.
FIG. 7A is an enlarged scale illustration of the final flattening of the base 50 'of a can by means of a punch comprising three concentric annular pressure-applying 6 rings 127A, 1278, 127C which are axially displaced relative one to another. The broken line A indicates the outline of the can end 50 after the pressure exerted by the first ring 127A, the broken line B indicates the outline of the can end after the pressure of the second ring 1278, and the broken line C indicates the outline of the can end after the pressure of the third ring 127C. The permanent deformation assumed by the base in each of these cases is that shown; the broken line D illustrates the resilient deformation which may then be incurred complementarily by the central portion of the base 50.
The number of corrugations or folds of the can end affected by these deformations depends on the volume of the contents of the can at the temperature at which the pressure is applied, on the diameter of the can, and on the total number of pressure-applying rings of the punch.
The mechanically effected reduction in the volume of the can or of its headspace comprises a peripheral portion of permanent deformation by partial flattening of the flexible corrugations 55 while the center panel 53 remains flexible and follows the variations in the volume and pressure of the contents of the can. This is why, at the end of the cooling action, which generates a weak vacuum in the can, the center panel 53 of the can end passes resiliently from the position C to the position D.
Experience has shown that owing to the customary deivations from the filling level between one can and another for one and the same product,'or from the filling temperatures between one can and another, it is desirable to contemplate possibilities of volume reduction of the order of 10%, so that in the greater number of cases, it will be preferred to employ can ends which, according to British Patent Specification No. 1170877, comprises the combination of an outer stiffening corrugation close to the end seam with flexible corrugations closer to the center. In case of a diminution of the prevailing deviations, it may however be contemplated to employ less flexible can ends of conventional shape.
In the application of the invention, a pressure limit will be adopted, which should not be exceeded in the final stage, for example amounting to between 0.15 bar and 0.15 bar relative to atmospheric pressure. This condition determines the volume reduction to be effected, which will'be a function of:
the filling temperature;
the filling level;
the quantity of gas in the can which is linked to the two preceding factors;
the expansion or contraction coefficient of the product.
The magnitude of the volume reduction to be effected being determined in this manner, it is appropriateto determine the instant in which it is to be performed.
In view of the risk of recontamination, it is undesirable to effect the volume reduction when the can is cold, since the damage may then already be done. It is thus desirable to apply the punching pressure to the can ends as soon as they have returned to a lower temperature than that of the filling temperature by a sufficient amount for the value of the vapour pressure to generate the vacuum required for spontaneous inward displacement of the can ends. If, for example, this operation is performed whilst the vapour pressure substantially still has a value of 0.2 or 0.3 bar, the continuation of the cooling action will cause an additional drop in vapour pressure and a contraction of the product and of the air, that is to say an additional vacuum which may be sufficient to collapse the can body. Experience confirms that the magnitude of the contraction of the product and of the air is sufficient to generate a complementary vacuum which causes collapse of the can body unless definite precautions are taken.
These considerations result in arranging that the volume reduction during the cooling process is effected at a temperature level which is as high as possible, but below which the variations in vapour pressure become small; for example, the temperature level may be approximately 40 C at which temperature the water vapour pressure reaches 0.075 bar and beyond which its decrease slows down appreciably.
The level of approximately 40 C having been establis'hed, the value of the permissible filling temperature without risk of collapse can be determined for cans of each kind. This may be understood more clearly by reference to the diagram of FIG. 8 which shows the evolution of the pressure variations as a function of the temperature (T): the curve Pv shows the evolution of the vapour pressure variations, whereas the curve Pi illustrates the variations in the relative pressure within a particular can.
On the temperature axis T has been marked at T the aforesaid temperature level of approximately 40 C whose selection is determined by the corresponding value P0 of the vapour pressure, being for example, 0.075 bar. Based on the temperature level T at which it has been decided to perform a volume reduction operation, asecond temperature level T is determined which will-be that to be adopted for the filling and sealing of the can. This level is established by a definite maximum value delta-P of the vacuum which can be borne by the kind of can in question, without risk of collapsing.
Two cases may then be envisaged, depending on whether the temperature T, is considered adequate or insufficient for the sealing of the can. If it is considered inadequate, it is earmarked for performing an operation of volume reduction at the same temperature, and
another pressure stage delta P is taken to determine another temperature level T which will, in this case, be taken as being satisfactory as an initial level for sterilisation after the sealing of the can. This sterilisation (arrow 5) will include the rise in temperature up to a definite level T (point A), causing the generation within the can of a definite relative pressure P and an inflation of the can ends (position 50C, FIG. 7). During the following cooling action, a first stage R32 initially restores the temperature to the sealing level T at which the relative internal pressure is substantially nullified, so that the ends of the can will have resiliently returned to their initial position (50, FIG. 7). A next cooling stage R21 returns the temperature to the level T (point B) with the drop delta-P of the vapour pressure and the generation of a definite negative pressure P which will moreover be greater than delta-P owing to the effect of the contraction of the air and of the gases occluded and of the product itself. At this level, a first volume reduction operation is performed which generates a definite compression K causing the internal pressure to rise to a definite positive value P which determines the starting point V of the curve portion R illustrating the stage R of the cooling action leading to the temperature level T (point D) at which it has in all likelihood been decided to perform a volume reduction operation. This operation causes a recompression K which causes the internal pressure to rise to a definite positive level corresponding to the position of the point E. The last stage R of the cooling action which cools the can to ambient temperature, restores the relative internal pressure to a value very close to nought and an assurance is gained that the can will retain a correct saleable appearance even if the climatic storage conditions were to heat the can to temperatures which may amount to between 5 and 40 C, for example.
The level or levels ofinternal vacuum, like P P will evidently be chosen to have lower values than the limit beyond which the can in question runs the risk of spontaneous collapse. This limit. essentially is a function of the gauge of the metal of the can body, which renders it possible to emphasize the advantage of the invention, being the possibility of reducing this gauge without impairing the quality of the packaging.
The pressure force is limited to a lower value than that of bursting of the assembled can; this limitation, which is applied by the pressure-limiting device 32, FIG. 2, is a function of the shape and structure of the can. The can bodies will usually easily withstand pressure of3 bars, which renders it possible to contemplate relatively high pressure forces.
The technique of volume reduction according to the invention is applicable to cans provided with a can end of the so-called easy-opening type. In this case, the pressure-applying apparatus should make allowance for the fact that the easy-opening end should not be touched, and that only the can end at the opposite end of the can be acted upon. An example of an apparatus appropriate for this case is illustrated in FIG. 9 in which a can body 60 has a can end 61 analogous to that of FIG. 7, and an easy-opening end 62. Facing the can end 61 is a pressure-applying element 30 analogous to that of FIG. 2; the pressure-applying element 65 arranged facing the can end 62 differs, however, from the element 22 of FIG. 2, in that its punch-66 provides the can end with a surface arranged to support it over its entire area except for a peripheral area; and the groove provided around the punch and in alignment with the unsupported area provides a part 68 for abutment against the end seam 69. Because of this arrangement, the thrust displacement exerted on the can end 62 is limited to a small value, which may, if need be, be practically equal to nought, compatible with the deformability allowed by its peripheral area 67.
FIg. 10 illustrates apparatus intended for application of the invention to a deep-drawn can 70 which is equipped with a can end 71 of the easy-opening type. Aligned with the can end 71 is a pressure-applying element 65 of the kind described with reference to FIG. 9. In this embodiment, however, the pressure-applying element 72 exerts pressure on the deep-drawn base 73 and comprises a groove 76 having a surface the section of which corresponds to the radius of curvature by which the base 73 is joined to the body of the can. The central portion 74 of the pressure-applying element exerts pressure against the central portion of the base by means of springs 77 to prevent the base from becoming convex. The clearance between the element 74 and its guide 72 is greater than the maximum value scheduled for the pressure displacement, which, in this case also,
. 9 is determined by a pressure-limiting device (not shown). 7
The axial pressure P exerted under these conditions effects a displacement in axial translation of the whole of the supported portion of the base whilst rounding-off the portion 75 adjoining the base to the can body; this displacement may continue along a height as great as needed to secure the optimum final volume reduction defined by the condition of obtaining a final internal pressure between 0.15 and 0.15 bar, as described above. If the can end seamed to a deep-drawn can is a standard can end (and not one of the easy-opening type), it will evidently be capable of bearing a part of the volume reduction.
The process according to the invention is applicable not only to the can ends made of tin-plate or other steels, or of'aluminum, but is also applicable to ends made of any other materials offering the qualities required for application as ends for cans. Further, the invention is applicable not only to circular cans as herein described, but also to prismatic can or to frusto-conical or frusto-pyramidal cans of any desired cross-section.
When considering cans having a cross-section other than circular nad referring to a punch provided with an annular pressure-applying face, the term annular face should be understood as meaning a surface which is defined by outlines conforming to the external contour of the can end processed and which leaves uncovered the central part of the can end.
1. A volume controlling apparatus for use in conjunction with an apparatus for sterilizing products within a sealed can having at least one deformable end to deform the deformable end during a cooling process following sterilisation to control internal pressure within the can, said volume controlling apparatus comprising first and second can engaging members, mounting means for mounting said members in opposed spaced relation and for relative axial movement to clamp a can therebetween, at least one of said members having a portion of a configuration for directly engaging and applying pressure to the deformable can end to deform the deformable end as the associated can and product therein cools, and said mounting means including a pressure limiting means for controllably limiting the pressure appliedby said member portion to the can end, said pressure limiting'means being separate and apart from that portion of said mounting means which effect movement of said member to a can clamping position.
2. The volume controlling apparatus of claim 1 wherein said one member portion is of a configuration for opening out a selected corrugation in an associated can end.
3. The volume controlling apparatus of claim 1 wherein said one member portion is of a configuration for engaging a preselected portion only of a can end, and the associated one of said members having guide means separate and apart from said member portion for aligning said member portion with the preselected can end portion.
4. The volume controlling apparatus of claim 1 wherein said one member portion is in the form of a punch.
5. The volume controlling apparatus of claim 1 wherein said one member portion is in the form of a punch having axially stepped punch element means for sequentially engaging a can end to sequentially open out corrugations formed therein and effect a sequential controlled deformation of a can end into a respective can.
6. The volume controlling apparatus of claim 1 wherein said pressure limiting means directly supports one of said members.
7. The volume controlling apparatus of claim 1 wherein said one member portion is in the form of a punch, and said pressure limiting means directly supports said punch.
8. The volume controlling apparatus of claim 1 wherein said one member has a groove surrounding said member portion for receiving a peripheral end portion of a can, and said groove being of a predetermined depth for limiting the relative end deforming movement between said member portion and a can.
9. 'The volume controlling apparatus of claim 1 wherein said member portion is of an annular configuration to thus leave free of engagement at central part of an associated can end.
10. The volume controlling apparatus of claim 1 wherein said member portion is of a configuration to match the opposed surface of a respective can end.
11. The volume controlling apparatus of claim 1 wherein at least said one member has guide means for engaging the periphery of a can and centering the same, said guide means being in the form of a frustoconical surface.
12. The volume controlling apparatus of claim 1 wherein said one member portion of in the form of a punch having a plurality of concentric annular pressure applying rings displayed axially relative to each other.
13. The volume controlling apparatus of claim 1 wherein said apparatus is particularly adapted for use with a can having an integral end joined to a body by a radius, and said one member has a seat matching the contour of the intended can radius.
14. The volume controlling apparatus of claim 1 wherein said member portion is mounted separate and apart from the remainderof said one member and is supported by said pressure limiting device.
15. The volume controlling apparatus of claim 1 wherein said mounting means include two pressure applying members mounted for relative pressure applying movement towards one another, one of said can engaging members being mounted on one of said pressure applying members for movement together therewith, said pressure limiting means being carried by the other of said pressure applying members, and the other of said can engaging members being carried bysaid pressure limiting means.
16. The volume controlling apparatus of claim 1 wherein there is a plurality of said volume controlling apparatus, a shaft having an 1 axis, a pair of supports mounted for rotation about the shaft axis, a plurality of apparatus being carried by said supports in circumferentially spaced relation about said axis, guide means for supplying cans in sequence to said plurality of apparatus, and means for operating said plurality of apparatus in succession.
17. the volume controlling apparatus of claim 16 wherein said plurality of apparatus is located in a cooling path of sterilised cans at a location wherein the cans have cooled to predetermined temperature.