CA2316815C

CA2316815C - Cutting device for a plastic seal

Info

Publication number: CA2316815C
Application number: CA002316815A
Authority: CA
Inventors: Wolfhard Schwarz
Original assignee: Alcoa Deutschland GmbH Verpackungswerke
Current assignee: Alcoa Deutschland GmbH Verpackungswerke
Priority date: 1997-12-29
Filing date: 1998-12-23
Publication date: 2005-06-14
Anticipated expiration: 2018-12-23
Also published as: CA2316815A1; JP2001526971A; CZ293237B6; HUP0100047A3; PL188265B1; DE19758040A1; HUP0100047A2; EP1044085A1; EA200000725A1; EP1044085B1; ES2173665T3; UA42893C2; DE59803573D1; DE19758040C2; EA001669B1; WO1999033618A1; CZ20002414A3; PL341385A1; HU222222B1

Abstract

The invention relates to a device for making a cut in the peripheral direction of a plastic seal, comprising at least one blade, said blade being held by a holding device, and a fixing device for the seal.
The invention is characterised in that the holding device (11) can be moved in relation to a path of motion (7) of the seal (3) by means of a control mechanism (29), in that the seal (3) is arranged in such a way that it can turn around its middle axis (5), and in that the cut is made by turning the seal (3) around its middle axis (5), the distance between the seal (3) and the blade (15) remaining constant or essentially constant whilst the seal is being turned.

Description

Cutting apparatus for a plastic closure --.
Description The invention relates to an apparatus for making at least one cut running in the circumferential direction of a plastic closure, having at least one cutter, held by a holding device, and having a securing device for the closure, wherein the closure is mounted rotatably about its centre axis 1 0 ~ the cut can be made by a rotation of the closure about its centre axis.
A cut made in the circumferential direction o'f a plastic closure serves, for example, for forming a guarantee ring which, when opening a container on which the plastic closure is fitted, is separated at least in certain portions from the plastic closure and/or is irreversibly deformed in such a way that opening of the container for the first time is indicated. Apparatuses of the type referred to here are known. They have a plurality of fixedly arranged cutters, which are passed by by a plastic closure which can be displaced along a path of movement. In general, three cutters arranged one behind other - seen in the direction of displacement of the closure - are used for this purpose, the closure being pressed against the said cutters and rolling along them as a result of its displacement movement along the path of movement. In this operation, a partial cut running over 120° of the circumferential surface of the closure is respectively made in the said circumferential surface by each cutter, the said cuts adjoining one another and thereby forming a continuous cut. Although a continuous cut is made in the circumference of the closure by the known cutting apparatus, the cut has a varying depth - seen in the circumferential direction - on account of the arrangement of the cutters and the cutting edge geometry. The cut profile is such that the depth of the cut is very small in the initial region of a cutter, greater towards the centre of the cutter and less again from the centre towards the end region of the cutter. Due to this depth-of-cut profile, it ' cannot be ensured in all cases that the forces acting on the guarantee ring when the container is opened are adequate to damage or deform the said ring in the desired way, with the result that opening for the first time cannot be detected with certainty. A further disadvantage of the cut of varying depth is that the guarantee ring can already be separated from the closure in certain portions, in the regions with the greatest depth of cut, during its production or fitting onto the container, which in turn reduces the reliability of the guarantee ring.
It is therefore the object of the invention to provide an apparatus by means of which a cut running in the circumferential direction of a closure can be made with a constant, or least substantially constant depth.
To achieve this object, a cutting apparatus > according to one embodiment of the invention has a holding device that can be displaced with respect to a path of movement of the closure by means of a control system, the closure is mounted rotatably about its centre axis and the cut can be made by a rotation of the closure about its centre axis, the distance between the closure and the cutter being constant or substantially constant during the rotation. In the case of a circumferential cut, the closure is rotated through 360°. For making the cut running in the circumferential direction of the closure, the closure is firstly brought together with the cutter, which is fixed by a holding device, and, after making contact with the cutter, is rotated in a defined manner about its centre axis. At least one cut running in the circumferential direction of the closure is thereby made with a constant depth. The uniform depth of cut over the circumference of the closure is achieved by the distance between the closure and the cutter not being changed during the rotation of the closure about a centre axis. That is to say, at least the region of the cutter at the smallest distance from the centre axis of the closure has a fixed position with respect to the closure during the cutting operation. Since only a single cutter is required for making the cut running in the circumferential direction of the closure, the construction of the cutting S apparatus can be simplified and consequently the costs thereof can be reduced.
Particularly preferred is an exemplary embodiment of the cutting apparatus which is distinguished by the fact that the path of movement of the closure is a circular path and that the holding device holding the cutter can be displaced along a closed, curve-shaped contour path, the centre point of which lies on the centre point of the circular path.
The cutting apparatus has a carousel-like construction, that is to say the closure and the cutter, or the holding device holding the cutter, are displaced together along the path respectively assigned to them, preferably at the same circumferential speed, during the cutting operation.
In a preferred exemplary embodiment of the cutting apparatus, the control system is designed as a cam control system, which here has a disc cam. The latter is felt by a feeling element, interacting with the holding device for the cutter. The feeling element is preferably connected to the holding device on which the cutter is fastened. Thus, the contour path along which the holding device is displaced is defined by the disc cam.
In an advantageous development of the invention, the depth of cut can be set. This makes it possible to adapt or set the cutting apparatus to plastic closures with different wall thicknesses or shapes and/or of different plastics.
Also preferred is an exemplary embodiment of the cutting apparatus in which the position of the cutter with respect to the closure can be set. As a result, a defined angle of cut can be set, with the result that the cut surface is inclined with respect to an imaginary horizontal by an angle which is greater . _ Q _ than 0° and less than 90°. In another exemplary embodiment, it is provided that the cut surface formed during the cutting operation is parallel to the imaginary horizontal, in other words runs perpendicularly with respect to the circumferential surface of the closure.
Further advantageous embodiments emerge from the remaining subclaims.
The invention is explained in more detail below with reference to the drawing, in which:
Figure 1 shows a plan view of an exemplary embodiment of the cutting apparatus according to the invention and Figure 2 shows a side view of an exemplary embodiment of a securing device for the closure.
Figure 1 shows a plan view of a basic diagram of an exemplary embodiment of an apparatus, referred to in the following as cutting apparatus 1, for making at least one cut in a closure 3, which consists of plastic and is used for closing a container, for example a bottle. The closure 3 is mounted rotatably about its centre axis 5 by means of a securing device, represented in Figure 2, and can be displaced along a path of movement 7, represented by dashed lines. In this exemplary embodiment, the path of movement 7 is a circular path with the centre point 9. The closure 3 is represented in Figure 1 in several positions A to F, which it assumes or passes through one after the other inside the cutting apparatus 1.
The cutting apparatus 1 comprises a holding device 11, which can be displaced about the centre point 9 of the path of movement 7 and has a setting element 13, on which a cutter 15 is fastened. The setting element 13 is guided in a groove 17 and can be fixed on the holding device 11 with the aid of at least one fastening means 19, for example by means of two locking screws. The longitudinal centre axis 20 of the groove 17 intersects the centre point 9, that is to say the cutter 15 can be displaced both in the direction of the centre point 9 and in the direction of the path of movement 7 by a displacement of the setting element 13 in the groove 17. The holding device 11 further comprises a guiding part 21 for the closure 3, which has a semicircular depression 23, open at the edge, for receiving the closure. The depression 23 is made in the guiding part 21, starting from a planar side face 25 of the said part facing the path of movement 7. The cutter 15 fastened on the setting element 13 is positioned on the holding device 11 in such a way that, in order to come into engagement with the closure, it protrudes into the depression 23 of the guiding part 21, thereby fixing the depth of the cut to be made into the circumference of the closure 3. The depth of cut can be adjusted in a simple way by varying the position of the setting element 13, on which the cutter 15 is fastened, within the groove 17. At the end of the holding device 11 facing away from the guiding part 21 there is provided a feeling element 27, which interacts with a control system 29 of the cutting apparatus 1, which will be discussed in more detail below.
The control system 29 is designed in this exemplary embodiment as a cam control system, which comprises a contour disc 31, which is also referred to as a cam disc, is of a substantially circular design and the centre point of which lies on the centre point 9 of the path of movement 7 of the closure 3. The contour disc 31 has a fixed position and, when there is a displacement of the holding device 11 and the closure 3, does not rotate at the same time but remains in the position represented in Figure 1. The contour disc 31 has a curve-shaped outer contour 33, which is felt by the feeling element 27 of the holding device 11, mounted displaceably in the direction of the longitudinal centre axis 20. As a result, when there is a rotation about the centre point 9, the holding device 11 is positively driven and is displaced along a contour path, the profile of which corresponds to the outer contour 33 of the contour disc.

The contour disc 31 has a sub-portion 35.1, which extends over a circumferential region of about 110° and is designed as a portion of a circular path.
The sub-portion 35.1 is adjoined - seen in the direction of displacement of the holding device 11 and of the closure 3 (arrow 37) - by a sub-portion 35.2, which extends over a circumferential region of about 140° and is likewise designed as a portion of a circle, the radius of which is less than the radius of the sub-portion 35.1. The sub-portion 35.2 is adjoined by a third sub-portion 35.3, which extends over a circumferential region of about 35°. The radius of the contour disc 31 in the region of the sub-portion 35.3 is greater than the radius both in the region of the sub-portion 35.2 and in the region of the sub-portion 35.1. The transitional region from the sub-portion 35.3 to the sub-portion 35.1 has a profile which is curved inwards - seen in the direction of the centre point 9 - in other words is concave. The transition from one sub-portion to the other extends over a relatively large circumferential region of the contour disc 31 and does not have any sharp edges or abrupt changes. The shaping of the transitions can be used to set the rate of displacement at which the holding device 11 can be displaced with respect to the path of movement 11.
In a displacement, that is to say rotation, of the holding device 11 in the direction of the arrow 37 about the centre point 9 by means of a guiding device (not shown), its distance, and consequently the distance of the cutter 15, from the path of movement 7 of the closure 3 changes on account of the positive driving by the feeling element 27. In the circumferential regions of the contour disc 31 of constant radius, in other words in the sub-portions 35.1, 35.2, 35.3, the holding device 11 has a constant distance from the path of movement 7 of the closure 3.
The function of the cutting apparatus 1 is explained in more detail below on the basis of a cutting operation: in the position A, the closure 3 is transferred from a processing station (not shown) for the closure 3 to the cutting apparatus 1. As shown in Figure 1, the closure 3 is thereby introduced into the semicircular depression 23 of the guiding part 21 of the holding device 11 and is centred. In this position, the side face 25 of the guiding part 21 lies on the path of movement 7. Then, the closure 3 and the holding device 11 are displaced together in the direction of the arrow 37, the closure 3 along the path of movement 7 and the holding device 11 along the contour path predetermined by the outer contour 33 of the control disc 31. On account of the smaller radius of the contour disc 31 in the region of the sub-portion 35.2 in comparison with the sub-portion 35.1, the holding device 11 is displaced with respect to the path of movement 7 of the closure in the direction of the centre point 9. The distance between the holding device 11 and the path of movement 7 is increased in such away that the guiding part 21 releases the closure 3, that is to say the closure 3 fixed by the securing device, not shown in Figure 1, is guided outside the range of effect of the depression 23. In the region between the position B and the position D, the closure 3 and the holding device 11 are at a constant distance from each other. In the transfer region between the position B and the position D, the closure 3 can be processed, preferably at least one perpendicular incision is made into the region of the closure circumference, in which subsequently the guarantee ring is formed by a circumferential cut.
The cut running in the circumferential direction of the closure 3 is made in the region of the sub-portion 35.3. In this sub-portion, the holding device 11 is displaced outwards in the direction of the path of movement 7, with the result that the closure 3 is guided in the depression 23 of the guiding part 21, the distance between the closure 3 and the cutter 15 protruding into the depression 23 being so small that the cut can be made into the circumference of the closure 3. For this purpose, the closure 3 is rotated in the region of the sub-portion 35.3 at least by 360°
about its centre axis 5, whereby a cut running in the circumferential direction of the closure 3 is made.
The fact that the contour disc 31 has a constant radius in the region of the sub-portion 35.3 has the effect that the distance between the closure 3 and the cutter is constant during the 360° rotation, in other words 10 so too is the depth of the cut. In the position F, the closure 3 is subsequently guided out of the cutting apparatus 1.
Figure 2 shows an exemplary embodiment of a securing device 39 for the closure 3, which has a pin 15 shaped holding element 41 and a gearwheel 43 connected to the latter in a rotationally fixed manner. The gearwheel 43 interacts with a drive device (not shown), by means of which the rotational speed of the closure 3 about its centre axis 5 can be set. The rotational speed of the closure 3 in the region of the sub-portion 35.3 is at least so high that it carries out a 360°
rotation, whereby the cut running in the circumferential direction is made.
In a further exemplary embodiment - not shown the cutting apparatus 1, described on the basis of Figure 1, has a plurality of holding devices 11, with in each case at least one cutter. As a result, its throughput, that is to say the number of closures processed by the cutting apparatus, can be increased.
It is also advantageous that, by the use of a plurality of cutters, their service life is increased and consequently so too are the maintenance intervals of the cutting apparatus at which the cutters which are subject to wear are exchanged. In each case, one closure and one holding device, having a cutter, are guided together from the run-in (position A) of the cutting apparatus to its run-out (position F), that is to say they have the same circumferential speeds.

The cutter 15 fastened on the setting element 13 is preferably designed as an exchangeable insert, with the result that when the cutter is worn it can be exchanged simply and quickly. In the exemplary embodiment represented in Figure 1, the cutter 15 has a straight cutting edge, which is aligned, purely by way of example, tangentially with respect to the circumference of the closure. In order to make a cut of constant depth in the circumference, the cutter can also be inclined with respect to the closure at an acute or obtuse angle.
To sum up, it can be stated that, with the cutting apparatus 1, an exact cut running in the circumferential direction of a closure can be made in the said closure, whereby preferably a guarantee ring, also referred to as a guarantee band, is formed. The depth of cut is fixed by the contour disc 31, which controls the relative movement of the holding device 11 with respect to the path of movement 7 of the closure 3. With the aid of the setting element 13, on which the cutter 15 is fastened, a fine setting of the depth of cut can be performed, in order for example to compensate for tolerances of the individual parts of the apparatus. During the cutting operation, the distance between the cutter and the closure is constant, with the result that the cut has a constant depth over the entire circumference of the closure, whereby the originality-indicating function of the guarantee ring can be ensured with great certainty. It is also found, moreover, that cuts running in the circumferential direction which do not run all the way around, that is to say are not uninterrupted, can also be made into the closures. To accomplish this, it is merely necessary to limit the rotating movement of the closure which is in the sub-region 35.3, for example to 120°, 240° or the like.

Claims

The embodiments of the present invention in which an exclusive property or privilege is claimed are defined as follows:

1. An apparatus for making a cut running in the circumferential direction of a plastic closure, having at least one cutter, held by a holding device, and having a securing device far the closure, wherein the closure is mounted rotatably about its centre axis and the cut can be made by a rotation of the closure about its centre axis, characterized in that the closure can be guided along a path of movement, in that the holding device can be displaced with respect to the path of movement by means of a control system and in that the holding device can be moved along with the closure.

2. The apparatus according to claim 1, wherein the path of movement is a circular path and in that the holding device holding the cutter can be displaced along a preferably closed, curved-shaped contour path, the centre point of which lies on the centre point of the circular path.

3. The apparatus according to claim 2, wherein the circumferential speed of the closure and that of the cutter are equal or substantially equal.

4. The apparatus according to any one of claims 1 to 3, further comprising a plurality of holding devices with in each case at least one cutter.

5. The apparatus according to any one of claims 1 to 4, wherein at least one sub-portion of the contour path is a portion of a circular path.

6. The apparatus according to any one of claims 1 to 5, wherein the control system is a cam control system with a contour disc which can be felt by a feeling element interacting with the holding device.

7. The apparatus according to claim 6, wherein the feeling element is connected to the holding device.

8. The apparatus according to any one of claims 1 to 7, wherein the holding device comprises a guiding part with a preferably semicircular depression for the closure.

9. The apparatus according to any one of claims 1 to 8, wherein the cutter protrudes into the depression.

10. The apparatus according to any one of claims 1 to 9, wherein the depth of cut of the cutter can be set.

11. The apparatus according to any one of claims 1 to 10, wherein the position of the cutter with respect to the closure can be set.