Method of producing a stacking projection and corresponding tool

Abstract

In a method of producing a stacking projection and a corresponding tool a mandrel as part of the tool is inserted into a cup, wherein the mandrel comprises a receiving recess. The bottom part of the cup is then supported by a supporting tool and a collet is assigned to a region of the cup where the stacking projection is to be formed. Thereafter, at least a part of the collet is pressed radially inwardly in direction to the receiving recess such that a portion of the cup wall is pressed into the receiving recess to form the stacking projection. Simultaneously, the height of the cup is reduced by displacing the mandrel and/or the supporting tool with respect to the other in axial direction. Finally, pressure applied to the collet is released and the cup is removed with the mandrel from the collet and the supporting tool. By such method and corresponding tool the stretching of the wall material is avoided as well as any defect of an inner layer of polymer of this material and simultaneously the method of production and corresponding tool are simplified or of simply construction and can be used for high production rates of corresponding cups.

Claims

1. Method of producing a stacking projection inwardly protruding from a wall of a cup comprising: i) inserting a mandrel within the cup, which mandrel comprises a receiving recess at least open to the outer circumference of the mandrel, ii) supporting a bottom part of the cup by a supporting tool; iii) assigning a collet to a region of the cup wall where the stacking projection is to be formed; iv) pressing at least a part of the collet radially inwardly in direction to the receiving recess wherein a portion of the cup wall is pressed into the receiving recess to form said stacking projection; v) simultaneously to step iv) reducing the height of the cup by displacing the mandrel and/or the supporting too with respect to the other in axial direction, and vi) releasing pressure applied to the collet and removing the cup with the mandrel from the collet and the supporting tool and (vii) wherein in step iv) a plurality of collet fingers separated from each other by a slot there between are pressed radially inward.

2. Method according to claim 1, wherein in step iv) the collet with its collet fingers is axially displaced to enable- an outer surface of each collet finger to slides along an inwardly and downwardly converging slide surface of a ring tool surrounding at least the collet.

3. Method according to claim 2, wherein the supporting tool and the mandrel are axially displaced together with the collet.

4. Method according to claim 2, which comprises supporting the collet and its collet fingers by an inner surface of the ring tool in a release position of the collet and tilting the collet fingers radially inwardly and a lower part of the collet beneath the collet fingers radially outwardly to obtain a pivoting movement of the collet.

5. Method according to claim 2, which comprises axially moving the collet fingers with respect to the ring tool by retraction of the support tool with respect to the ring tool in axial direction, wherein the collet is moved together with the supporting tool.

6. Method according to claim 5, which comprises pressing, prior to steps iv), the cup wall against a step-like protrusion of each collet finger to form a particular ring-shaped embossment radially inwardly protruding from the cup wall into the receiving recess.

7. Method according to claim 6, which comprises arranging during steps iv) and v) the mandrel and the support tool in a first distance to each other bigger than a thickness of the material of a bottom plate of the cup arranged there between and reducing this first distance during steps iv) and v).

8. Method according to claim 7, which comprises after step vi), arranging an overwrap onto the cup wall and fixing the overwrap to the cup wall at least in positions above and below the stacking projection.

9. Method according to claim 1, which comprises holding the cup onto the mandrel after forming of the stacking projection and removing the cup with the mandrel from the collet and the supporting tool.

10. Method according to claim 1 wherein in step iv) the collet with its collet fingers is axially displaced such that an outer surface of each collet finger slides along an inwardly and downwardly converging slide surface of a ring tool surrounding at least the collet.

11. Method of producing a stacking projection inwardly protruding from a wall of a cup comprising: i) inserting a mandrel within the cup, which mandrel comprises a receiving recess at least open to the outer circumference of the mandrel, ii) supporting a bottom part of the cup by a supporting tool; iii) assigning a collet to a region of the cup wall where the stacking projection is to be formed; iv) pressing at least a part of the collet radially inwardly in direction to the receiving recess such that a portion of the cup wall is pressed into the receiving recess to form said stacking projection; v) simultaneously to step iv) reducing the height of the cup by displacing the mandrel and/or the supporting too with respect to the other in axial direction, and vi) releasing pressure applied to the collet and removing the cup with the mandrel from the collet and the supporting tool and wherein in step iv) a plurality of collet fingers are radially inwardly pressed which collet fingers are all separated from each other by a slot there between.

12. The method of claim 11 wherein in step iv) the collet with its collet fingers is axially displaced wherein an outer surface of each collet finger slides along an inwardly and downwardly converging slide surface of a ring tool surrounding at least the collet, the supporting tool and the mandrel are axially displaced together with the collet and wherein the collet and its collet fingers are supported by an inner surface of the ring tool in a release position of the collet and tilting the collet fingers radially inwardly and a lower part of the collet beneath the collet fingers radially outwardly to obtain a pivoting movement of the collet.

13. Method according to claim 11 wherein in step iv) the collet with its collet fingers is axially displaced wherein an outer surface of each collet finger slides along an inwardly and downwardly converging slide surface of a ring tool surrounding at least the collet.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, embodiments of the invention are illustrated in the Figures.

(2) The following are shown:

(3) FIG. 1 a vertical sectional view of the tool according to the invention in an open position;

(4) FIG. 2 a view similar to FIG. 1 in a closed position of the tool;

(5) FIG. 3 an enlarged illustration of a part of the cup where the stacking projection is formed;

(6) FIG. 4 a further embodiment of the tool in an open position, and

(7) FIG. 5 a vertical sectional view of two stacked cups.

DETAILED DESCRIPTION OF THE DRAWINGS

(8) In FIG. 1, a vertical sectional view of tool 1 according to the present application is illustrated. Tool 1 comprises a mandrel 9 which is inserted in a cup 4 wherein a corresponding cup wall 3 is an abutment with an outer circumference 11 or corresponding outer surface 31 of the mandrel 9. For holding the cup 4 onto the mandrel 9, a number of low pressure lines 30 are used which end in this outer surface 31, see also FIGS. 2 and 4.

(9) At a lower part of the mandrel 9, see its lower end 40, a receiving recess 10 is arranged, which is open to the outer circumference 11 and also in direction to a lower end surface 28. The mandrel is displaceable in axial directions 13 by a corresponding lifting and lowering mechanism, which is not explicitly illustrated in the Figures.

(10) In FIG. 1, an open position of the tool is illustrated, which means that the mandrel 9 can be lifted or lowered to arrange the corresponding cup 4 and particular its bottom part 5 on a supporting tool 6. This supporting tool is arranged beneath the mandrel and comprises an upper support surface 29 directed to lower end surface 28 of the mandrel 9. In the open position according to FIG. 1, lower end surface 28 and upper support surface 29 are arranged in a distance 24 such that a gap 39 is formed between the two surfaces. Corresponding lower end surface 28 is also part of the outer surface 31 of the mandrel 9.

(11) The supporting tool 6 is surrounded by a collet 7 which has a ring shape and further a plurality of collet fingers 14 in an upper end portion 34 of the collet, see also FIG. 2. Those collet fingers are separated by slots 15 and are arranged in particular in a region 8 of the cup 4 or mandrel 9 where the receiving recess 10 is arranged and where a stacking projection 2 should be formed, see also FIGS. 3 and 5.

(12) In the position according to FIG. 1, the collet fingers 14 are arranged in their release position 20, which means they are only in contact with the wall 3 from its outside by corresponding step-like protrusions 22 which are radially extending from an inner surface of the corresponding collet fingers 14.

(13) Outer surfaces 16 of corresponding collet fingers 14 opposite to corresponding inner surface are in contact with a slide surface 17 of a ring tool 18 surrounding the collet 7 and also the supporting tool 6. The ring tool 18 is a further part of tool 1 as well as the mandrel 9, the collet 7, and the supporting tool 6.

(14) The corresponding slide surface 17 is upwardly and outwardly diverging, see FIGS. 1 and 2, wherein the corresponding outer surfaces 16 of the collet fingers 14 are in contact with this slide surface.

(15) The slide surface 17 is part of an inner surface 19 of the ring tool 18 which also comprises a contact surface 36 which is assigned to an end flange 35 of the collet 7. This end flange 35 is arranged in a lower part 21 of the collet and radially extends outward. The contact surface 36 is outwardly and downwardly diverging.

(16) Within the ring tool 18, collet 7 and supporting tool 6 are axially displaceable, see also support 47 in FIG. 2, which is fixed to the supporting tool 6 and is used for displacing same in axial direction 13. Furthermore, there is an articulated joint 37 or hinge mechanism arranged between collet 7 and supporting tool 6 such that the collet may pivot or tilt about this articulated joint 37 with respect to the supporting tool 6 and, correspondingly, also with respect to axial direction 13.

(17) For example, in FIG. 2, the collet is tilted such that the collet fingers 14 are displaced more radially inwards wherein the end flange 37 is displaced more radially outwards in comparison to FIG. 1.

(18) The corresponding step-like protrusion 22 extends upwardly and inwardly converging and is used for forming the corresponding stacking projection 2 or ledge, see also FIG. 3. The step-like protrusion 22 has a tip 48 which is already in contact with the wall 3 from its outside in the release position 20, see FIG. 1. When the cup 4 is lowered by mandrel 9 to arrange the bottom part 5 of the cup 4 and in particular bottom plate 26 on upper support surface 29 of supporting tool 6 corresponding tip 48 will produce a small embossment 23 in the wall 3 which embossment has the form of the groove 38 extending to the interior of the cup. This embossment or groove in particular an the initial starting point for forming the stacking projection 2.

(19) The supporting tool 6 has further a groove 32 surrounding the upper support surface 29, wherein in this groove 32 a bottom edge 33 of the cup 4 is arranged, see FIGS. 1 and 2. This bottom edge 33 is also part of the bottom part 5 of the cup 4.

(20) In FIG. 2 the tool 1 is illustrated in a closed position, which means that mandrel 9 and supporting tool 6 are lowered within the ring tool 18. With lowering the supporting tool 6 also collet 7 is moved in axial direction 13 such that the outer surfaces 16 of the collet fingers 14 slide along the slide surface 17 in a cam action according to which these collet fingers 14 are displaced in direction to the receiving recess 10 and corresponding end flange 35 is radially displaced in outward direction. Corresponding bottom edge 33 will follow the contact surface 36 such that the collet 7 in total will make a pivoting or tilting movement around the articulated joint 37, see in comparison FIGS. 1 and 2. By the corresponding camming action between the outer surfaces 16 and the slide surface 17, the step-like protrusions 22 are pressed in direction and into the receiving recess 10 to form the stacking projection 2. Simultaneously, corresponding distance 24 or a gap 39 between lower end surface 28 and upper support surface 29 is decreased and might be decreased such that the gap only has a width corresponding to a thickness 25 of the corresponding material of the cup wall and in particular of the bottom plate 26 of the cup.

(21) In FIG. 2 the corresponding collet fingers 14 are in their pressing position 27 with the step-like protrusions 22 inserted into the receiving recess 10. As already outlined, by the simultaneous reduction of the gap 39 there is some kind of compression of the cup 4 in the area of the bottom part 5 which compression will prevent any stretching of the paper or the wall material during deforming by the step-like protrusions. This means, together with the inward movement of the collet fingers a corresponding height 12 of the cup 4 is reduced by such compression or lifting of the bottom plate 26 and also bottom part 5 which is just sufficient to allow the paper to fold and to form the stacking projection without stretching the paper. Consequently, there will be no thinning of, for example, an inner layer of polymer of the cup wall and also pinholes will not be formed which might cause leakage. Moreover, as the paper is not stretched, it also does not loose some of its mechanical strength and does not become weaker.

(22) According to one embodiment of the invention it is possible that the corresponding gap 39 is reduced by 1 mm to 3 mm between the two positions illustrated in FIGS. 1 and 2, wherein the gap might also be reduced by 1.5 mm to 2.5 mm and preferably by 2 mm.

(23) It is not necessary according to present invention, see for example FIG. 2, that the lower end surface 28 and upper support surface 29 are in contact with respect to each other with only the bottom plate 26 arranged therebetween. It is also possible that the corresponding gap 39 according to FIG. 1 is still present, but is, of course reduced in height by the corresponding amount.

(24) In FIG. 3 the particular section of the cup 4 where the stacking projection is formed, is illustrated in an enlarged form. The corresponding stacking projection 2 comprises a side wall 44 inwardly and upwardly converging wherein to the upper end of the side wall 44 an essentially horizontal top wall 45 is connected. Corresponding stacking projection 2 is formed in the region 8, see also the assignment of the collet fingers 14 and in particular of the step-like protrusion 22 to this region in FIGS. 1 and 2.

(25) According to the embodiment illustrated in FIG. 3 the corresponding stacking projection 2 is arranged directly above the bottom part 5 and in particular the bottom plate 26. Such stacking projection 2 is used for nesting cups into each other, see FIG. 5 with two cups. The inner cup 4 is supported by the top wall 45 of the stacking projection 2 wherein a corresponding inward curl 41 at a lower end of an overwrap 42 of corresponding double-walled cup 4 is supported by the top wall 45. This supporting will prevent any sticking of the cups such that it is possible to easily remove the inner cup 4 from the outer cup. Corresponding overwrap 42 extends up to an outward curl 43 at the upper end of the cup 4. Between overwrap 42 and cup wall 3 an insulating gap is formed.

(26) In FIG. 4 a second embodiment of a corresponding tool 1 is illustrated. According to this embodiment, there is a one-part supporting tool 6 and collet 7. This means, that corresponding collet fingers 14 extend upwardly from an upper end of the supporting tool 6, wherein the supporting fingers 14 have some elasticity or flexibility such that they may be bended inwardly in case the supporting tool with the collet fingers is lowered within ring tool 18. The ring tool 18 according to this embodiment has a vertical slide surface 17, wherein outer surfaces 16 of the collet fingers 14 are upwardly and outwardly diverging. This means, by lowering the supporting tool 6 within the ring tool 18 the collet fingers 14 will be pressed radially inwards by the corresponding contact with the slide surface 17. To improve corresponding elasticity/flexibility, a slot 46 may be arranged, see FIG. 4.

(27) The mandrel 9 according to FIG. 4 may be of the same construction as in FIGS. 1 and 2 and also comprises for example a low pressure line 30 for holding the cup onto the mandrel.

(28) According to the second embodiment it may be advantageous, in case there are two embossments 23 formed in the cup wall prior to bending this part of the cup wall in direction to a corresponding receiving recess 10 by pressing action of inwardly deflected collet fingers 14.

(29) The two embossments 23 are arranged in a distance from each other and in general at upper and lower ends of the stacking projection 2.

(30) The upper embossment 23 according to FIG. 4 may extend to the outside and the lower embossment to the inside. It is, however, also possible that both are directed to the inside, both are directed to the outside or the upper to the inside and the lower to the outside. Corresponding embossments are pre-embossed prior to arranging the cup within the supporting tool 6 and will simplify any bending of the cup wall to form the stacking projection.

(31) Such pre-embossment is not necessary according to the first embodiment of this invention, see FIGS. 1 and 2.

(32) It is again emphasized, that according to the present invention there is a simultaneous action of forming the stacking projection by tilting or pivoting the collet fingers 14 to the inside and compressing the cup in particular in the area of the bottom part and where the stacking projection 2 is formed. By this simultaneous action any stretching of the material of the material of the wall is prevented.

(33) FIG. 5 is a vertical section through two cups stacked in each other to illustrate the nesting or stacking according to the contact of the inward curl 41 with the stacking projection 2, see also the comments set forth above.