Abstract:
The present invention provides a method of assembling a filter element ( 8 ) with a cup-shaped capsule body ( 2 ) using a combined weld-head ( 70 ) and former ( 80 ), comprising the steps of positioning the filter element ( 8 ) at or near a mouth of the cup-shaped capsule body ( 2 ), moving the combined weld-head ( 70 ) and former ( 80 ) so as to contact and drive the filter element ( 8 ) into the cup-shaped capsule body ( 2 ), wherein, the filter element ( 8 ) is deformed by a sprung-loaded former ( 80 ) of the combined weld-head ( 70 ) and former ( 80 ) to form a cup-shaped filter element ( 56 ), and using a weld-head ( 70 ) of the combined weld-head ( 70 ) and former ( 80 ) to bond the cup-shaped filter element ( 56 ) to the cup-shaped capsule body ( 2 ). The present invention further provides a method of making a beverage capsule and a beverage capsule produced using this method.

Description:
[0001]    The present application relates to improvements in or relating to capsules. In particular, it relates to a weld-head and former for use in the assembly of capsules, such as beverage capsules. The application also relates to methods of assembly utilising said weld-head and former and uses of capsules produced by said methods. 
       BACKGROUND 
       [0002]    Capsules for containing beverage ingredients are well known. One type of known capsule is described in U.S. Pat. No. 5,840,189 and comprises a cup-shaped capsule body having a base, a truncated conical side wall and an open mouth. The open upper mouth is hermetically sealed by a lid. The cup-shaped capsule body and lid define a capsule volume in which is located a filter element and a portion of beverage ingredients. In use, the lid and base are both pierced to allow for the injection of hot water into the capsule volume, and the delivery of an extracted beverage out of the capsule volume. The filter element serves to allow the extracted beverage to pass there through while retaining the solid residue of the beverage ingredients. In U.S. Pat. No. 5,840,189 the filter element is permanently joined to an interior surface of the conical side wall at a location adjacent to the open mouth. 
         [0003]    U.S. Pat. No. 6,440,256 describes a method of forming and inserting a filter element into a cup-shaped capsule body of the type described in U.S. Pat. No. 5,840,189. In particular, the method first requires the folding and sealing of a filter material to form a filter element. The filter element is then transferred to the location of a cup-shaped capsule body by a first mandrel. A probe is then lowered relative to the first mandrel to strip the filter element off the first mandrel with a heated tip of the probe being used to tack weld a bottom of the filter element to the base of the cup-shaped capsule body. Next, the probe is withdrawn and a shaping mandrel is inserted to radially expand the filter element against the interior side wall of the cup-shaped capsule body. The shaping mandrel is then withdrawn and a welding mandrel is inserted to effect a peripheral weld between the filter element and the side wall. 
         [0004]    This prior art method involves a number of individual stages and require three separate mandrels. It is also unsuitable for assembling a filter element in a capsule where the filter element does not extend to the base of the cup-shaped capsule body. 
       SUMMARY OF THE DISCLOSURE 
       [0005]    According to the present disclosure there is provided a method of assembling a filter element with a cup-shaped capsule body using a combined weld-head and former, comprising the steps of: 
         [0006]    a) positioning the filter element at or near a mouth of the cup-shaped capsule body; 
         [0007]    b) moving the combined weld-head and former so as to contact and drive the filter element into the cup-shaped capsule body; 
         [0008]    c) wherein, during step b), the filter element is deformed by a sprung-loaded former of the combined weld-head and former to form a cup-shaped filter element; and 
         [0009]    d) using a weld-head of the combined weld-head and former to bond the cup-shaped filter element to the cup-shaped capsule body. 
         [0010]    Advantageously, the combined weld-head and former achieves, in a single operation, the multiple functions of inserting the filter element into the cup-shaped capsule body, shaping the filter element into a cup-shaped filter element, and the bonding together of the cup-shaped filter element and the cup-shaped capsule body. This allows for a less complicated and quicker assembly procedure. The method is also suitable for assembling a filter element in a capsule where the filter element does not extend to a base of the cup-shaped capsule body. 
         [0011]    A magnitude of a peak force applied to the filter element by the sprung-loaded former may be limited by allowing the sprung-loaded former to move relative to the weld-head against a spring bias. 
         [0012]    Typically, the filter material is made from a material having a relatively low tear strength. The present applicant has found that using a solid, non-compliant former to drive the filter element into the cup-shaped capsule body can lead to tearing of the filter element if too high a load is applied to the filter element by the former. By use of the sprung-loaded former of the present disclosure the likelihood of tearing of the filter element is lessened or avoided since the peak force applied by the former to the filter element may be moderated by the compliance of the former. 
         [0013]    Consequently, the magnitude of the peak force applied to the filter element is preferably less than the force required to tear the cup-shaped filter element. For example, the magnitude of the peak force applied to the filter element may be less than 45N, preferably less than 40N, more preferably less than 30N. 
         [0014]    At the end of step b), a portion of the cup-shaped filter element may be held in contact with the cup-shaped capsule body by the weld-head. Advantageously, this allows bonding of the cup-shaped filter element and the cup-shaped capsule body to take place immediately after the filter element has been deformed into the cup-shaped filter element. In other words, a single stroke of the combined weld-head and former not only inserts and deforms the filter element into the required shape but also readies the cup-shaped filter element for a bonding step. This avoids the need for a plurality of reciprocal machine movements to insert, deform and bond the filter element, which thus results in a faster assembly process. 
         [0015]    The cup-shaped filter element may be bonded to the cup-shaped capsule body such that the cup-shaped filter element is suspended within the cup-shaped capsule body, with a base of the cup-shaped filter element being out of contact with a base of the cup-shaped capsule body. 
         [0016]    During step d), a portion of the cup-shaped filter element may be bonded to the cup-shaped capsule body by using a heated portion of the weld-head. The weld-head may be heated by a resistive heater coil or resistive band. The heated portion may comprise a heated ceramic component. 
         [0017]    During step d), at least a portion of the cup-shaped capsule body may be softened by the heated portion of the weld-head, thereby allowing the weld-head to move further into the cup-shaped capsule body. 
         [0018]    The heat applied to the cup-shaped capsule body may result in softening of the material of the cup-shaped capsule body and/or may result in localised thinning of a side wall of the cup-shaped capsule body. In either case this may allow the weld-head to move further into the cup-shaped capsule body since the reaction force applied to the weld-head by the cup-shaped capsule body may be reduced by the material softening. 
         [0019]    During said further movement of the weld-head into the cup-shaped capsule body, further movement of the sprung-loaded former into the cup-shaped capsule body may be limited or avoided by allowing the sprung-loaded former to move relative to the weld-head against a spring bias. 
         [0020]    Advantageously, even where the weld-head does move further into the cup-shaped capsule body, movement of the former further into the cup-shaped capsule body is either limited or avoided due to the former being sprung-loaded. In other words, the additional displacement of the weld-head is partially or wholly accommodated by compression of the spring bias existing between the weld-head and the former. This significantly lessens or eliminates any additional loading being applied to the cup-shaped filter element during the bonding step. 
         [0021]    The sprung-loaded former may be slidably coupled to the weld-head, with a compression spring extending between the sprung-loaded former and the weld-head. As an alternative to a compression spring, the former may be sprung-loaded by, for example, use of an elastomeric spring, a gas spring, a gas strut, or another arrangement providing compliance between the weld-head and the former or compliance within the former itself. The element providing compliance may be a separate element or may form an integral part of either the weld-head or former. The material and/or the shape of the former may produce the compliance. 
         [0022]    The method may further comprise the step of: 
         [0023]    e) withdrawing the combined weld-head and former from the cup-shaped capsule body. 
         [0024]    During step e) the sprung-loaded former may flex to aid decoupling of the sprung-loaded former from the cup-shaped filter element. 
         [0025]    The former may be formed from a rigid material. In some aspects using a flexible former may reduce the risk that the cup-shaped filter element will be torn on withdrawal of the combined weld-head and former. A part or a whole of the former may therefore be formed from a flexible material. Alternatively, the former may comprise a geometric shape providing an inherent flexibility. 
         [0026]    The present disclosure also provides a method of making a beverage capsule, comprising the steps of: 
         [0027]    i) filling a portion of one or more beverage ingredients into a cup-shaped capsule body having a filter element bonded thereto by the method described above; and 
         [0028]    ii) closing and sealing the cup-shaped capsule body using a lid. 
         [0029]    The present disclosure also provides a beverage capsule produced using the method described above. 
         [0030]    The one or more beverage ingredients may be an extractable/infusible ingredient such as roasted ground coffee or leaf tea. The beverage ingredients may be a mixture of extractable/infusible ingredients and water-soluble ingredients. The water-soluble ingredient may be, for example, an instant spray-dried or freeze-dried coffee, a chocolate powder, a milk powder or a creamer powder. Milk powders may include dried skimmed milk, part-skimmed milk, and whole milk, dried milk protein concentrates, isolates, and fractions, or any combination thereof. Creamer powders may be manufactured from dairy and/or non-dairy food ingredients and typically contain emulsified fat, stabilized by protein or modified starch, dispersed in a carrier that facilitates drying, especially spray drying. The powdered ingredient may be agglomerated. 
         [0031]    The present disclosure also provides a combined weld-head and former for use in assembling a beverage capsule, comprising a weld-head and a former, wherein the former is sprung-loaded. 
         [0032]    The sprung-loaded former may be slidably coupled to the weld-head, with a spring extending between the sprung-loaded former and the weld-head. 
         [0033]    As noted above, the spring may be a compression spring, an elastomeric spring, a gas spring, a gas strut or another arrangement providing compliance between the weld-head and the former. The element providing compliance may be a separate element or may form an integral part of either the weld-head or former. 
         [0034]    The sprung-loaded former may comprise a forming body. 
         [0035]    At least a portion of the forming body may be flexible. 
         [0036]    The present disclosure also provide for use of a combined weld-head and former as described above to assemble a filter element with a cup-shaped capsule body. 
         [0037]    The cup-shaped capsule body may be formed from a polymeric material. For example, it may be formed from polypropylene, polyester, polystyrene, nylon, polyurethane, acetal, acetal grade polyoxylene methylene copolymer (e.g. Centrodal C), or other engineering plastics. 
         [0038]    The cup-shaped capsule body may comprise a laminated material. For example, the cup-shaped capsule body may comprise a laminate of polystyrene and polyethylene. In another example, the cup-shaped body may be formed from a laminate having layers of polystyrene, ethylene vinyl alcohol (EVOH) and polyethylene. 
         [0039]    The cup-shaped capsule body may comprise a barrier layer. The barrier layer may form one layer of a laminate structure of the cup-shaped capsule body. The barrier layer may be substantially impermeable to oxygen/air and/or moisture. Preferably the barrier layer acts to preserve the contents of the capsule from potential degradation due to exposure to oxygen/air and/or moisture. An example of a suitable barrier layer is EVOH. 
         [0040]    Suitable materials for the filter element include heat-sealable woven and non-woven materials, paper, and cellulose as well as plastics such as polypropylene and polyethylene. The paper or cellulose material may contain fibres of another material, for example, polypropylene or polyethylene. 
         [0041]    The sprung-loaded former may be made in whole or in part from a material which is heat resistant. The sprung-loaded former may be, formed from a rigid material such as aluminium, mild steel, copper, brass or stainless steel. It may also be made from a non-metallic material such as a ceramic or a polymer. The polymer may comprise synthetic resin bonded fabric, for example, a phenol formaldehyde resin including additional woven cotton or linen fabrics. One example of such is Tufnol® available from Tufnol Composites Ltd., of Birmingham, UK. The sprung-loaded former may be made in whole or in part from a material which is flexible. One example is silicone. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0042]    Aspects of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which: 
           [0043]      FIG. 1  is a cross-sectional representation of a combined weld-head and former, a cup-shaped capsule body and a filter element before assembly; 
           [0044]      FIG. 2  is a cross-sectional representation of the filter element being inserted into the cup-shaped capsule body by the combined weld-head and former; 
           [0045]      FIG. 3  is a cross-sectional representation of the filter element inserted into the cup-shaped capsule body and ready for bonding; 
           [0046]      FIG. 4  is a cross-sectional representation of the combined weld-head and former being withdrawn from the cup-shaped capsule body; and 
           [0047]      FIG. 5  is a perspective representation of a capsule formed using the cup-shaped capsule body of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION 
       [0048]    A capsule  1 , which may be, for example, a beverage capsule containing a portion of one or more beverage ingredients, is shown in  FIG. 5 . The capsule  1  comprises a cup-shaped capsule body  2  having a base  4  of a circular shape and an upwardly extending side wall  5 . An open upper end of the cup-shaped capsule body  2  is closed and sealed by a lid  3 . The capsule  1  contains a cup-shaped filter element  56  (shown in  FIG. 4 ) which serves to allow a liquid to pass there through while retaining a solid residue. The lid  3  provides an upper piercing surface of the capsule  1 . The base  4  provides a lower piercing surface of the capsule  1 . 
         [0049]    The cup-shaped capsule body  2  may be formed from a laminate having layers of polystyrene, ethylene vinyl alcohol (EVOH) and polyethylene. 
         [0050]    The lid  3  may be formed from polyethylene, polypropylene, polyesters including polyethylene terephthalate, polyvinyl chloride, polyvinylidene chloride, polyamides including nylon, polyurethane, paper, viscose and/or a metal foil. The lid may comprise a laminate, be metallised or formed of copolymers. In one example, the lid comprises a polyethylene-aluminium laminate. 
         [0051]      FIG. 1  shows the cup-shaped capsule body  2  and a filter element  8  from which the cup-shaped filter element  56  will be formed. The filter element  8  comprises a flexible, die-cut circular piece of suitable heat-sealable filter material. 
         [0052]      FIG. 1  also shows a combined weld-head and former  60  that is used to assemble the filter element  8  with the cup-shaped capsule body  2 . 
         [0053]    As shown in  FIG. 1 , the side wall  5  of the cup-shaped capsule body is provided on its inner face with a plurality of flutes  28  that project radially inwards so as to define channels  29  interposed between the flutes  28  which run down a substantial length of the side wall  5  from the open upper end  20  towards the base  4 . The side wall  5  is generally frustoconical in shape with a diameter at the open upper end  20  being larger than a diameter at the side wall  5  adjacent to the base  4 . An upper region of the side wall  5  adjacent to the upper rim  21  has an inwardly tapering section  22  extending downwardly from the upper rim  21 . In addition, the side wall  5  in the region of the base  4  is provided with an outwardly tapering section  23 . An upper end of the outwardly tapering section  23  connects to the remainder of the side wall  5  at an out-turned shoulder  24 . 
         [0054]    The combined weld-head and former  60  comprises a weld-head  70  and a sprung-loaded former  80 . 
         [0055]    The weld-head  70  comprises a generally solid body  71  having a bore  72  running there through. The bore  72  is located at a centre of the solid body  71  and orientated along a longitudinal axis of the weld-head  70 . An upper end of the solid body  71  is provided with a plurality of threaded bores  75  to allow the weld-head  70  to be coupled to a mechanism (not shown) that controls movement and heating of the weld-head  70 . A lower end face  73  of the weld-head  70  is perpendicular to the longitudinal axis. A welding zone  74  towards a lower end of the solid body  71  is shaped to conform with the cup-shaped capsule body  2 . In the illustrated example the welding zone  74  comprises two tapered surfaces that conform in shape to inwardly tapering section  22  of the cup-shaped capsule body  2 . The weld-head may be formed from a suitable material able to transmit heat energy via the welding zone  74 . Examples include mild steel, aluminium, copper and brass. 
         [0056]    The sprung-loaded former  80  comprises a forming body  86 , a coupling leg  83  and a spring  84 . The forming body  86  comprises a base  82  of a circular shape and a side wall  81  which extends upwardly from the base  82  and terminates in a circular rim  87 . The side wall  81  has a frusto-conical shape, the inclination of which generally conforms to the inclination of the side wall  5  of the cup-shaped capsule body  2 . An outer corner  85  at the junction between the side wall  81  and the base  82  is radiused to prevent any sharp edges which might tear the filter element  8 . The coupling leg  83  extends upwardly from the base  82  within the side wall  81 . The coupling leg  83  is cylindrical and located at a centre of the forming body  86  and is shaped and sized to be received as a sliding fit within the bore  72  of the weld-head  70 . The forming body  86  is made of a rigid material, such as aluminium or copper. Alternatively, a material with a degree of flexibility, such as a silicone rubber, could be utilised. 
         [0057]    The spring  84  is located about the coupling leg  83  and extends from an inner face of the base  82  to the lower end face  73  of the weld-head  70 . The spring is a helical compression spring. 
         [0058]    The coupling leg  83  is retained within the bore  72  by means of a threaded bolt, bore and washer arrangement  88  at an upper end of the coupling leg  83 . 
         [0059]    As assembled and viewed in the orientation shown in  FIG. 1 , the sprung-loaded former  80  at rest is biased downwards away from the weld-head  70  by the spring  84  such that a gap  90  exists between the circular rim  87  of the side wall of the forming body  86  and the lower end face  73  of the weld-head  70 . 
         [0060]    The steps in assembling the filter element  8  with the cup-shaped capsule body  2  are shown in  FIGS. 2 to 4 . 
         [0061]    In a first step shown in  FIG. 2 , the cup-shaped capsule body  2  is supported in a suitable holder (not shown) and the combined weld-head and former  60  is moved downwards by mechanical means such that the filter element  8  is driven down into the open upper end  20  of the cup-shaped capsule body  2  by the sprung-loaded formed  80 . This movement causes the previously flat filter element  8  to begin to be deformed into the cup-shaped filter element  56 . A central portion of the filter element  8  contacted by the base  82  of the forming body  86  will become a base  52  of the cup-shaped filter element  56 . An intermediate zone  53  of the filter element  8  will form a portion of a side wall  51  of the cup-shaped filter element  56 . A peripheral zone  50  of the filter element  8  will form a bonded zone of the side wall  51  of the cup-shaped filter element  56 . During this first stage the resistance to movement of the filter element  8  is low and consequently the sprung-loaded former  80  moves in unison with the weld-head  70  and the size of the gap  90  remains substantially unchanged. 
         [0062]    Insertion of the combined weld-head and former  60  continues until the point is reached, shown in  FIG. 3 , where the filter element  8  has been fully inserted and the weld-head  70  has been brought into contact with the peripheral zone  50  of the filter element  8 . At this point the filter element  8  has been fully deformed into the cup-shaped filter element  56 . Also, the welding zone  74  of the weld-head  70  acts to firmly hold the peripheral zone  50  of the filter element  8  against the inwardly tapering section  22  of the cup-shaped capsule body  2 . As can be seen from  FIG. 3 , the base  52  of the cup-shaped filter element  56  is held free of the base  4  of the cup-shaped capsule  2  by a distance  55 . Up to this point the resistance to movement of the filter element  8  remains low and consequently the sprung-loaded former  80  moves in unison with the weld-head  70  and the size of the gap  90  remains substantially unchanged. 
         [0063]    Bonding of the cup-shaped filter element  56  to the cup-shaped capsule body  2  now takes place due to heat energy from the welding zone  74  causing localised fusing of the material of the filter element  8  and the cup-shaped capsule body  2 . The heating of the material of the cup-shaped capsule body  2  has been found to have a tendency to soften and/or thin the cup-shaped capsule body  2 . This allows the weld-head  70  to move downwards, further into the cup-shaped capsule body  2 . This further inward movement of the weld-head  70  would have a tendency, if the forming body  86  were not sprung-loaded, to impart an increased force to the cup-shaped filter element  56  (which is now not free to move relative to the cup-shaped capsule body  2 ). However, the sprung-loaded form of the former  80  means that the further inward movement of the weld-head  70  is accommodated by compliance of the combined weld-head and former  60  —specifically it is accommodated by compression of the spring  84  so as to move the forming body  86  relative to the weld-head so as to reduce the size of the gap  90 . 
         [0064]    The final stage, shown in  FIG. 4 , is to withdraw the combined weld-head and former  60 . At this stage, withdrawal of the forming body  86  from the cup-shaped filter element  56  may be aided, the case where the forming body  86  is formed from a flexible material, by flexing of the forming body  86  which reduces the chances of tearing of the cup-shaped filter element  56 . 
         [0065]    The assembly of the cup-shaped filter element  56  and the cup-shaped capsule body  2  may then undergo further process steps in order to fill the capsule with a portion of one or more beverage ingredients and to apply the lid  3 . 
         [0066]    As part of the assembly method described above, the spring rate of the sprung-loaded former  80  should be chosen as required depending on the particular geometry of the cup-shaped capsule body  2  and the material of the filter element  8  to ensure that the peak load imparted to the filter element  8 /cup-shaped filter element  56  does not exceed its tearing strength. The spring rate of the sprung-loaded former  80  depends not only on the spring rate of the spring  84  itself but also the effects of friction between the components of the former  80 . In one experiment, a circular piece of filter material comprising woven paper and polyethylene of diameter 97 mm and thickness 0.1 mm, was bonded according to the method described above in a cup-shaped capsule body  2  having an inner face formed from polyethylene and an internal diameter at the open upper mouth  20  of 45 mm. The depth of the cup-shaped filter element  56  so formed was 33 mm. For this example a spring rate of from 2.0 to 4.0 N/mm, preferably 3.0 N/mm for the sprung-loaded former  80  was found to be beneficial. This was achieved with use of a helical compression spring having a spring rate of from 1.0 to 3.0 N/mm, preferably 2.0 N/mm. 
       Examples 
       [0067]    Tests were conducted to ascertain the tearing strength of a typical filter element. The results are shown in Table 1 below. The filter element comprised a circular piece of filter material comprising woven paper and polyethylene of diameter 97 mm and thickness 0.1 mm. A forming body  86  was driven at a fixed rate of 100 mm/minute until tearing of the filter element occurred. 
         [0000]    
       
         
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                 Peak force at 
               
               
                   
                   
                 point of tearing 
               
               
                   
                 Test 
                 (N) 
               
               
                   
               
             
             
               
                   
                 Run 1 
                 51.18 
               
               
                   
                 Run 2 
                 49.72 
               
               
                   
                 Run 3 
                 58.67 
               
               
                   
                 Run 4 
                 58.46 
               
               
                   
                 Run 5 
                 62.59 
               
               
                   
                 Run 6 
                 53.05 
               
               
                   
                 Run 7 
                 53.83 
               
               
                   
                 Run 8 
                 48.05 
               
               
                   
               
             
          
         
       
     
         [0068]    From this, it can be seen that, for this example, limiting the peak force applied to the filter element  8 /cup-shaped filter element  56  to under 48N is preferred to reduce or eliminate the chances of tearing. 
         [0069]    Comparative tests were then undertaken to compare the peak force applied to the filter element  8 /cup-shaped filter element  56  using the method of the present disclosure (making use of a sprung-loaded former  80 ) compared to an assembly method using a weld-head and former that consists of a solid bung former that is not sprung-loaded relative to the weld-head. As above, the filter material comprised woven paper and polyethylene of diameter 97 mm and thickness 0.1 mm. The capsule body  2  comprised an inner face formed from polyethylene and an internal diameter at the open upper mouth  20  of 45 mm. The depth of the cup-shaped filter element  56  formed was 33 mm. For the combined weld-head and former  60 , a spring rate of 3.0 N/mm for the sprung-loaded former  80  was chosen by use of a compression spring having a spring rate of 2.0 N/mm. The results are shown in Table 2 below. 
         [0000]    
       
         
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                   
                 Peak force 
                   
               
               
                 Test 
                 applied (N) 
                 Observations 
               
               
                   
               
             
             
               
                 Solid bung former 
                 50.30 
                 Tearing observed 
               
               
                 Run 1 
                   
                   
               
               
                 Solid bung former  
                 54.83 
                 No tearing 
               
               
                 Run 2 
                   
                   
               
               
                 Solid bung former 
                 52.58 
                 Tearing observed 
               
               
                 Run 3 
                   
                   
               
               
                 Sprung-loaded former 
                 25.22 
                 No tearing 
               
               
                 Run 1 
                   
                   
               
               
                 Sprung-loaded former  
                 27.62 
                 No tearing 
               
               
                 Run 2 
                   
                   
               
               
                 Sprung-loaded former  
                 25.37 
                 No tearing 
               
               
                 Run 3 
                   
                   
               
               
                 Sprung-loaded former  
                 27.00 
                 No tearing 
               
               
                 Run 4 
                   
                   
               
               
                 Sprung-loaded former  
                 26.93 
                 No tearing 
               
               
                 Run 5 
               
               
                   
               
             
          
         
       
     
         [0070]    Use of the sprung-loaded formed resulted in a significantly reducing peak load being applied to the filter element  8 /cup-shaped filter element  56  and in every case prevented tearing of the material. 
         [0071]    In the above aspect, the forming body  86  comprises an intergral, cup-shaped, thin-walled structure. However, other forms of forming member may be used as part of the sprung-loaded former  80 . For example, the forming body  86  may be formed from a plurality of separate parts. The forming body  86  may comprise a base  82  but no side wall.