Abstract:
Method and apparatus for producing a twin-wall cup from paper or paper-like material including placing an inner cup with a sleeve and a base onto a mandrel, laying a flat segment onto an outer side of the inner cup, opposite to the mandrel, shaping the flat segment to form an outer jacket, which surrounds the inner cup, and fixing the outer jacket on the inner cup by means of a material engagement connection of outer jacket and inner cup, in particular by means of adhesive bonding, wherein at least one spacer is attached to an inner side of the flat segment and/or to an outer side of the sleeve of the inner cup before the flat segment is laid on the inner cup.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This claims priority from German Patent Application No. 10 2015 220 747.1, filed Oct. 23, 2015, the disclosure of which is hereby incorporated by reference in its entirety into this application. 
       FIELD, BACKGROUND AND SUMMARY OF THE INVENTION 
       [0002]    With the invention, a method for producing a twin-wall cup is to be improved. 
         [0003]    According to the invention, a method for producing a twin-wall cup from paper or paper-like material having the following steps is proposed for this purpose:
       placing an inner cup with an in particular conical sleeve and a base onto a mandrel,   laying a flat segment onto an outer side of the inner cup, opposite to the mandrel,   shaping the flat segment to form an in particular conical outer jacket, which surrounds the inner cup,   fixing the outer jacket on the inner cup by means of a material engagement connection of outer jacket and inner cup, in particular by means of adhesive bonding, and   attaching at least one spacer to an inner side of the flat segment and/or on an outer side of the sleeve of the inner cup before laying the flat segment on the inner cup.       
 
         [0009]    When winding an outer jacket onto an inner cup, the flat segment which is intended to form the outer jacket should be fixed to the inner cup before the actual winding operation, and therefore fixed until the conclusion of the winding operation. This is usually carried out by means of a clamping lever which presses the segment onto the inner cup. The opposing force is absorbed by a mandrel onto which the inner cup is pushed. The force needed for the secure fixing of the segment is necessarily so high that the previously applied adhesive between inner cup and segment is forced out of the pressing area. As a consequence, the air gap needed for the insulation of the cup between the inner cup and outer jacket is reduced to a non-tolerable extent in the area of the clamping lever. The finished cup is then restricted in terms of its function, possibly even unusable. In the method according to the invention, before the flat segment is laid on the inner cup, at least one spacer is attached to an inner side of the flat segment and/or to an outer side of the sleeve of the inner cup. The spacer is formed in such a way that it can no longer be deformed plastically or deformed only to a small extent. The spacer therefore serves to maintain the dimensions of the insulation gap even under the action of force from the clamping lever on the segment. As a result of the provision of the spacer, the segment can then be wound to form the outer jacket and it is possible to ensure that, on the finished cup, a substantially constant spacing between outer jacket and the sleeve of the inner cup is achieved. The twin-wall cup that is produced has very good insulating properties as a result. 
         [0010]    Paper, board or paperboard, for example, is viewed as a paper material or paper-like material. For example, paper, board or paperboard can be present in flat segments, and these flat segments can then firstly be wound to form a sleeve having a circumferential wall and also deformed to form a base element that is pot-like, for example. The sleeve and the base are then connected to form an inner cup. The outer jacket is also produced from a flat segment. Expediently, the paper material is coated in a liquid-tight manner. In any case, the inner side of the inner cup should be coated in a liquid-tight manner. On the outer side of the inner cup and on the outer jacket, it is possible to dispense with a liquid-tight coating, also to make printing of the outer jacket easier. However, plastic material present in flat form, for example, is also viewed as a paper-like material if this is processed in the same way or at least in a similar way to form a cup or a lid. Flat plastic materials are also plastic laminates, for example. To produce an inner cup, outer jacket or lid, the flat plastic material which is present in segment form is likewise wound around a central mandrel and connected in the area of the overlap in order to form an in particular conical sleeve. A pot-like base or pot-like lid element can also be shaped from the flat plastic material by a circular blank being folded upward approximately vertically with respect to its bottom surface in its edge region. The problems which occur in the case of plastic material to be processed in a manner similar to paper are, however, substantially the same which occur when processing paper material. Specifically, plastic material to be processed in a paper-like manner can also not be deformed highly, for example bent, without losing its insulating properties and leak-proof properties. The present invention can be used for plastic materials to be processed in a paper-like manner but is not specifically designed for plastic materials to be processed in a paper-like manner but of course can also be used for paper material with considerable advantages. 
         [0011]    In a development of the invention, the spacer is attached at least in the middle between the two side edges of the flat segment. 
         [0012]    In this way, the spacer can provide an abutment when fixing the flat segment to the inner cup, and the segment can be wound to form the outer jacket with less expenditure of pressure. 
         [0013]    In a development of the invention, the spacer on the finished cup runs in the direction from the base of the cup towards an opening of the cup. 
         [0014]    In this way, the spacer can in particular be attached without difficulty to the segment without preventing bending of the segment during the winding of the outer jacket. Specifically, in the case of spacers running from the bottom to the opening of the cup, that is to say vertically, the spacers can also be arranged distributed over the segment and nevertheless do not hamper the bending of the segment during the winding of the outer jacket. 
         [0015]    In a development of the invention, the attachment of the spacer comprises the application and solidification of at least one adhesive track, in particular hot-melt adhesive, wherein the spacer is formed by the solidified adhesive track. 
         [0016]    As a result, a spacer can be attached in a surprisingly simple way. In order to bond the outer jacket to the inner cup, nozzles for the application of adhesive are needed in any case. Before the flat segment is laid on the outer side of the inner cup, according to the invention one or more adhesive tracks are applied to the outer side of the inner cup, for example by means of a nozzle, alternatively or additionally at least one adhesive track is applied to the inner side of the flat segment. Following the solidification of this adhesive track, the latter then serves as a spacer and the flat segment can be laid on the inner cup and fixed by means of a clamping lever. The outer jacket can then be wound from the flat segment. 
         [0017]    In a development of the invention, the attachment of the spacer comprises the application and solidification of at least one track of paper pulp, wherein the spacer is formed by the solidified track of paper pulp. 
         [0018]    Paper stock is designated paper pulp. By means of a track of paper pulp, which solidifies following application, a spacer can be implemented comparatively economically. A great advantage here is that the track of paper pulp can be applied in the continuous method, for example by means of a nozzle. 
         [0019]    In a development of the invention, the attachment of the spacer comprises the application and solidification of at least one foam track, wherein the spacer is formed by the solidified foam track. 
         [0020]    A spacer can also be implemented in a simple and economical way in the continuous method by means of a foam track. Here, it is possible to use a foam which hardens automatically following application. 
         [0021]    In a development of the invention, the spacer has a height of at least 0.2 mm and at most 5 mm, preferably between 1 mm and 3 mm. 
         [0022]    In this way, practical spacings between outer jacket and inner cup can be implemented. Even with a spacing of 0.2 mm, a good insulating effect is achieved, a very good insulating effect at 1 mm. Up to a spacing of 5 mm, the twin-wall cup produced is sufficiently stable. Of course, this also depends on the thickness of the material of the outer jacket and on the number of bonding points between outer jacket and inner cup. In general, however, it is true that the greater the adhesive area between outer jacket and inner cup, the worse the insulating effect of the cup produced becomes. 
         [0023]    In a development of the invention, the spacer is applied to an inner side of the flat segment and, before the flat segment is laid on the inner cup, an outer side of the inner cup is provided with at least one adhesive track for fixing the outer jacket on the inner cup. 
         [0024]    In this way, the segment is provided with one or more spacers and the outer side of the inner cup with at least one adhesive track. As a result, both the spacer and the adhesive track can be applied in a manner unaffected by each other. As the flat segment is laid on the inner cup, although the adhesive track is compressed where it is touched by the spacer, because of the spacer or multiple spacers, a spacing is nevertheless then maintained between the outer jacket and the inner cup during the winding of the outer jacket. 
         [0025]    In a development of the invention, multiple strip-like spacers are applied distributed over the inner surface of the flat segment and/or over the outer surface of the inner cup. 
         [0026]    In this way, a particularly uniform spacing over the entire circumference of the sleeve of the inner cup can be ensured. 
         [0027]    In a development of the invention, multiple strip-like spacers running rectilinearly parallel to one another or, as viewed in the longitudinal direction of the strip-like spacers, with increasing or decreasing spacing from one another are arranged on the inner side of the flat segment. 
         [0028]    The application of multiple strip-like spacers running rectilinearly to the inner side of the flat segment can be carried out in a particularly simple way in that, specifically during a linear transport movement of the flat segment, the spacers are applied by means of nozzles. On the finished cup, these strip-like spacers then run exactly in the vertical direction only in a cylindrical cup; in the case of a conical cup, the spacers then run obliquely with respect to the vertical direction. In order to arrange for the spacers on the finished cup to run exactly parallel to the vertical direction even in the case of a conical cup, these spacers can be arranged with increasing or decreasing spacing from one another on the inner side of the flat segment. 
         [0029]    In an apparatus for carrying out the method according to the invention, at least one device, in particular a nozzle, for attaching the at least one spacer is provided. 
         [0030]    By means of a nozzle, a spacer can be applied in a particularly simple way, for example by applying an adhesive track, a track of paper pulp or a foam track. 
         [0031]    In a development of the invention, transport means are provided for moving the flat segment along a path that is rectilinear or circular in some sections, wherein the at least one device for attaching the spacer is arranged on a rectilinear or circular section of the path. 
         [0032]    In this way, during the rectilinear or circular transport of the flat segment, a spacer or multiple spacers can be applied in a very simple way. 
         [0033]    With the invention, an improved twin-wall cup of paper or paper-like material having an inner cup is provided, which cup has a sleeve and a base and is provided with an outer jacket which surrounds the inner cup, wherein, between the inner side of the outer jacket and the outer side of the sleeve of the inner cup, at least one strip-like spacer in the form of a solidified adhesive track, a track of solidified paper pulp and/or a solidified foam track with a height between 0.2 mm and 5 mm, in particular between 1 mm and 3 mm, is provided. 
         [0034]    By providing one or more such spacers, it is firstly ensured that, when winding the outer jacket around the inner cup, a constant spacing between outer jacket and inner cup is achieved. Furthermore, in the event of providing multiple spacers, it is also possible to achieve the situation where a user, when gripping the cup, does not inadvertently reduce the spacing between outer jacket and inner cup. As a result, the insulating behaviour of the cup in use can be improved; the outer jacket can possibly also be made from thinner or less stable material. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0035]    Further features and advantages of the invention emerge from the claims and the following description of preferred embodiments of the invention in conjunction with the drawings. Individual features of the different embodiments illustrated and described can be combined with one another in any desired way without exceeding the scope of the invention. In the drawings: 
           [0036]      FIG. 1  shows a schematic illustration of a method step of the method according to the invention during production of a twin-wall cup, 
           [0037]      FIG. 2  shows a plan view of a flat segment which, in  FIG. 1 , is wound to form an outer jacket, 
           [0038]      FIG. 3  shows a schematic illustration of a method step of the method according to the invention according to a further embodiment, 
           [0039]      FIG. 4  shows a plan view of the flat segment which, in  FIG. 3 , is used to produce an outer jacket, 
           [0040]      FIG. 5  shows a sectional view of a twin-wall cup according to the invention which has the flat segment illustrated in  FIG. 4  as outer jacket, 
           [0041]      FIG. 6  shows a flat segment for producing an outer jacket in accordance with the method according to the invention, according to a further embodiment, 
           [0042]      FIG. 7  shows a view of a cup according to the invention according to a further embodiment, wherein the sleeve of an inner cup and the outer jacket are illustrated dashed and transparently, 
           [0043]      FIG. 8  shows a side view of the cup from  FIG. 7 , wherein the complete inner cup and the outer jacket are illustrated transparently, 
           [0044]      FIG. 9  shows a plan view of a flat segment of a further embodiment of the invention, 
           [0045]      FIG. 10  shows a plan view of a flat segment according to a further embodiment of the invention, and 
           [0046]      FIG. 11  shows a plan view of a flat segment according to a further embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0047]      FIG. 1  shows, schematically, a section of an apparatus for carrying out the method according to the invention. Illustrated schematically is an inner cup  12 , which has been pushed onto a mandrel  14 . The inner cup  12  has a sleeve and a base connected in a substantially liquid-tight manner to the sleeve. The inner cup  12  can already be provided at its upper edge, opposite the base, with what is known as a mouth roll. The mouth roll is formed by rolling in the upper end of the sleeve and gives a user of the cup an acceptable feeling when said user places the mouth roll on the lips. 
         [0048]    During one step of the method according to the invention, an originally flat segment  16  is wound on the inner cup  12  to form an outer jacket, which can be cylindrical or frustoconical. To this end, the flat segment  16  is laid on the inner cup at a point  18  and the flat segment  16  is then pressed against the inner cup  12  by means of a clamping lever  20 . The clamping lever  20  exerts a force  22 , wherein an opposing force is applied by the mandrel  14  onto which the inner cup  12  has been pushed. 
         [0049]    At the point at which it is laid on the inner cup  12 , the flat segment  16  bears a spacer  24 . The spacer  24  is formed in the shape of a line or strip and, in the embodiment illustrated, consists of a solidified adhesive track. The adhesive track is applied to the segment  16  in the flat state of the latter and consists of a hot-melt adhesive. The adhesive track of hot-melt adhesive that is applied solidifies comparatively quickly as it cools down and, in the solidified state of  FIG. 1 , is still only slightly plastically deformable. The force  22  applied to the outer side of the segment  16  by the clamping lever  20  therefore leads only to slight plastic deformation of the spacer  24 . However, it can be gathered from  FIG. 1  that, on the right and left of the spacer  24 , a spacing between the segment  16  and the inner cup  12  is maintained. This spacing lies between 0.2 mm and 5 mm, in particular between 1 mm and 3 mm, according to an advantageous refinement of the invention, and this spacing is achieved over the entire circumference of the inner cup  12 , between the inner cup  12  and the finished outer jacket. 
         [0050]    After the flat segment  16  has been laid and pressed on by means of the clamping lever  20 , the flat segment  16  is wound to form an outer jacket. This is indicated schematically in  FIG. 1  by two arrows  26 . The arrows  26  are intended generally to illustrate an action of force on the segment  16 , so that the latter is wound around the inner cup  12 , for example by levers, fingers or half-shells  27  matched to the cup contour. A force is applied somewhat higher on the left than on the right, in order to be able to produce an overlap at the segment edges. 
         [0051]    The segment  16  is thus laid around the inner cup  12  until the areas adjoining a first side edge  28  and a second side edge  30  overlap. The overlap that is produced is then pressed against the inner cup  12  by means of a further clamping lever  32 . The segment  16  then forms an outer jacket, which is fixed in its final form by adhesive, which is not illustrated in  FIG. 1 . Here, the adhesive can be applied to the areas of the segment  16  which adjoin the side edges  28 ,  30 . In the embodiment illustrated, adhesive tracks, which are not illustrated in  FIG. 1 , running around the inner cup  12  are applied and then connect the segment  16  to the inner cup  12 . Such adhesive tracks are illustrated schematically, for example in  FIG. 5 ,  FIG. 7  and  FIG. 8 . 
         [0052]    With the method according to the invention, it is possible to avoid the segment  16  coming into contact with the inner cup  12  as a result of the clamping lever  20 . Instead, by means of the spacer  24 , even in the area between the clamping lever  20  and the inner cup  12 , a spacing between inner cup  12  and the segment  16  or the finished outer jacket is maintained. 
         [0053]    The illustration of  FIG. 2  shows the flat segment  16  before being laid on the inner cup  12 . It is easy to see the spacer  24  in the form of a solidified adhesive track of hot-melt adhesive. The adhesive track can be applied, for example, by means of a nozzle  34 , illustrated schematically in  FIG. 2 , while the flat segment is moved under the nozzle  34  in the direction of the arrows  36  by transport means, not illustrated. The transport means can be formed, for example, as a transport belt and, during a linear movement of the flat segment  16 , the spacer  24  in the form of an adhesive strip of hot-melt adhesive is applied by means of the nozzle  34 . As soon as this hot-melt adhesive has cooled, a solidified adhesive track is available, which then forms the spacer  24 . 
         [0054]    The illustration of  FIG. 3  shows a further embodiment of the invention. As distinct from the method explained by using  FIG. 1 , the flat segment  16  is provided with a total of three strip-like spacers  38 ,  40 ,  42 . The spacer  38  is arranged at the same position as the spacer  24  in  FIGS. 1 and 2 . The likewise strip-like spacers  40 ,  42  are arranged to be spaced apart by 90° relative to the spacer  38  and ensure that, as the flat segment  16  is wound to form an outer jacket which surrounds the inner cup  12 , a constant spacing between inner cup  12  and the segment  16  and the outer jacket is also ensured at a distance from the spacer  38 . By way of example, illustrated on the left is a half-shell  27 , with which the left-hand section of the segment  16  is moved inward. Illustrated on the right by way of example is a finger  29 , in order to move the right-hand section of the segment  16  inward and to produce the overlap. Of course, half-shells or fingers can be used on both sides. 
         [0055]    The illustration of  FIG. 4  shows the flat segment  16  from  FIG. 3  with the strip-like spacers  38 ,  40  and  42 . It can be seen from  FIG. 4  that, in the longitudinal direction of the strip-like spacers  40 ,  38 ,  42 , a distance between the spacers  38 ,  40 ,  42  decreases or increases, depending on the direction along the spacers  38 ,  40 ,  42  in which it is viewed. 
         [0056]    The central spacer  38  can, as illustrated in  FIG. 2 , be applied by using a stationary nozzle  34 , while the flat segment  16  is moved in a transport direction  44 . The spacers  40 ,  42  can be applied with nozzles which change their position during the transport past of the segment  16 . Alternatively, the spacers  38 ,  40 ,  42  can be applied one after another and an alignment of the segment  16  relative to the transport direction  44  is changed between the application of the individual spacers  38 ,  40 ,  42 . 
         [0057]    The illustration of  FIG. 5  shows a sectional view of a twin-wall cup  50  according to the invention which has been produced in accordance with  FIG. 3 . In the sectional view of  FIG. 5  it is possible to see only spacer  38 . Also in  FIG. 5 , it is possible to see a total of three adhesive strips  52  running around the inner cup  12 , which connect the frustoconical outer jacket  54  to a likewise frustoconical sleeve  56  of the inner cup  12 . 
         [0058]    The outer jacket  54  ends shortly above a base  58  of the inner cup  12  which, in the area of a bottom rib  60 , is connected to the sleeve  56  in a substantially liquid-tight manner. At its upper edge, opposite the base  58 , the sleeve  56  is provided with a mouth roll  62 . The outer jacket  54  ends shortly underneath the mouth roll  62 . 
         [0059]    It can be seen that, on the finished twin-wall cup  50 , not only the spacer  38  but also the spacers  40 ,  42  which cannot be seen ensure a spacing between outer jacket  54  and the sleeve  56  of the inner cup  12  when the cup is used. In addition, the adhesive tracks  52  are solidified on the finished cup  50  and prevent a user bringing the outer jacket  54  against the outer jacket  54  into contact with the sleeve  56  of the inner cup  12  and, as a result, considerably impair the insulating effect of the cup  50 . Instead, by means of the invention, very stable twin-wall cups can be produced, which are also suitable for high filling quantities of hot or cold beverages. 
         [0060]    The illustration of  FIG. 6  shows a flat segment  16  which has been provided with a total of three strip-like spacers  64 ,  66 ,  68 . As distinct from the spacers  38 ,  40 ,  42  of the segment  16  of  FIG. 4 , the strip-like spacers  64 ,  66 ,  68  are arranged parallel to one another. The spacers  64 ,  66 ,  68  can thus be applied by means of stationary nozzles during rectilinear transport of the flat segment  16 . 
         [0061]    The illustration of  FIG. 7  shows a twin-wall cup  70  according to the invention according to a further embodiment of the invention. In order to be able to illustrate the inner structure of the cup  70 , a sleeve  72  of the inner cup and an outer jacket  74  are illustrated transparently and merely indicated by dashed lines. A base  76  of the inner cup  72 , on the other hand, is illustrated by continuous lines. 
         [0062]    Likewise illustrated by continuous lines are a total of four strip-like spacers  78 ,  80 ,  82 ,  84 , which run parallel to a vertical direction of the cup  70  and are arranged spaced uniformly from one another between the outer jacket  74  and the inner cup  72 . Likewise illustrated by continuous lines are three adhesive tracks  86  running around the inner cup  72 , which are arranged spaced uniformly from one another. 
         [0063]    During the production of the cup  70 , firstly the inner cup  72  is pushed onto the mandrel  14 , see  FIG. 1 . The outer side of the inner cup  72  is provided with the three circumferential adhesive tracks  86 . 
         [0064]    Then, see  FIG. 1 , a flat segment  16 , which is provided with four strip-like spacers  78 ,  80 ,  82 ,  84  in the form of solidified adhesive tracks of hot-melt adhesive, is laid on the inner cup  72 . The segment is pressed against the inner cup  72  by means of the clamping lever  20 , see  FIG. 1 , and the segment is then shaped to form the outer jacket  74 . The shape of the outer jacket is then maintained by the adhesive action of the adhesive tracks  86 , which solidify and connect the outer jacket  74  to the inner cup  72 . The twin-wall cup  70  is extremely stable as a result and exhibits excellent insulating properties. The cup  70  can also be produced in a simple and economical way. 
         [0065]    The illustration of  FIG. 8  shows a side view of the cup  70  from  FIG. 7 , wherein once more the inner cup  72  including its base  76  and the outer jacket  74  is illustrated transparently and with dashed lines. 
         [0066]    The illustration of  FIG. 9  shows, in a plan view, a segment  90  which, according to the invention, can be wound to form an outer jacket. Arranged in the centre of the segment are multiple spacers  92  in the form of mutually parallel short strips spaced apart from one another. The spacers  92  have the shape of a circular section, which cannot be readily seen in the illustration of  FIG. 9 . The spacers  92  are applied, for example by means of a device, in particular a nozzle, while the segment  90  is moved along a circular path. 
         [0067]    The illustration of  FIG. 10  shows a segment  100  according to a further embodiment of the invention. Segment  100  can be wound to form a frustoconical outer jacket. 
         [0068]    Spacers  102 ,  104  and  106  are arranged in the form of multiple short strips on an inner side of the segment  100 . Overall, respectively five strip-like spacers  102 ,  104  and  106  are provided. The strip-like spacers  102 ,  104 ,  106  are applied by means of a device, in particular a nozzle, while the segment  100  is moved under the device on a path in the shape of a circular arc. 
         [0069]    The illustration of  FIG. 11  shows a segment  110  according to a further embodiment of the invention. The segment  110  can be wound to form an outer jacket. The segment  110  is provided with three spacers  112 ,  114  and  116  in the form of sections of a circular arc. The spacers  112 ,  114 ,  116  are arranged parallel to one another. The spacers  112 ,  114 ,  116  are applied by means of a device, in particular a nozzle, while the segment  110  is moved underneath the device along a path in the shape of a section of a circular arc.