WO2006031160A1

WO2006031160A1 - A method, an apparatus and an arrangement in screw capsulating

Info

Publication number: WO2006031160A1
Application number: PCT/SE2005/001009
Authority: WO
Inventors: Thomas Pettersson
Original assignee: Tetra Laval Holdings & Finance S.A.
Priority date: 2004-09-16
Filing date: 2005-06-27
Publication date: 2006-03-23
Also published as: SE0402245D0

Abstract

The invention relates to a method, an apparatus and an arrangement in the screw capsulation of packaging blank parts (1) of double-top type. The method comprises the steps that a rotationally elastic element (10) is disposed between a gripping member (2) for each respective cap (3) and that drive member (7a) which rotates the gripping member (2) for screwing in position of a cap (3). Further, the method includes the step that the angle of rotation of each respective drive member (7a) is continuously registered, that the angle of rotation of each respective gripping member (2) is continuously registered, and that the rotation by each respective drive member (7a) of the gripping member (2) is discontinued when a predetermined difference has occurred between the angle of rotation thereof and the angle of rotation of the associated driving member (7a) corresponding to an intended tightening torque for the cap (3). The apparatus according to the invention displays self-locking chucks (2) which, on rotation in a first direction, have a gripping function and, on rotation in a second direction, have a releasing function, the chucks (2) being intended in said first direction to grip and rotate each respective cap (3) and, in said second direction, to release said cap (3). Each respective chuck (2) is controllably driven by a drive member (7a), a rotationally elastic element (10) being disposed between each respective drive member (7a) and chuck (2). A first angle indicator is connected between the rotationally elastic element (10) and each respective drive member (7) and a second angle indicator is connected between each respective rotationally elastic element (10) and each respective chuck (2). Control means is provided for regulating each respective drive member (7a). The control means is disposed to discontinue the motor rotation of each respective chuck (2) when the angle difference between the associated first angle indicator and second angle indicator reaches a predetermined value corresponding to a desired tightening torque of each respective cap (3). In the arrangement according to the present invention, the chucks (2) of the apparatus are disposed in line with one another in order, from opposing directions, to apply one cap (3) at each end of a double top (1) placed between the apparatuses.

Description

A METHOD, AN APPARATUS AND AN ARRANGEMENT IN SCREW CAPSULATING

TECHNICAL FEELD The present invention relates to a method, an apparatus and an arrangement in screw capsulation of packaging blank parts of the double-top type of the type described according to WO98/32586.

BACKGROUND ART It has long been known in the art to apply by machine a screw cap to a bottle or similar body intended for capsulation. In order to obtain a suitable tightening torque within the prior art technology, normally a chuck which supports the cap or a bracket which non-rotationally holds the bottle is supported by an adjustable torque clutch which, when the pre-set torque is achieved, disengages. However, the adjustable torque clutch gives, for certain situations and fields of practical application, unsatisfactory repeatability and accuracy as regards the torque obtained.

Further, the procedure for altering or adjusting the tightening torque is, in certain situations, perceived as circumstantial and time-consuming. In the employment of prior art technology for capsulation of double tops which are to be fitted with a cap at each end, the double top must, once the first cap has been applied in position, be turned and aligned before the second cap can be applied. This places extremely high demands on the apparatus which is intended to handle the double top. Further, the double top which, before being closed and sealed, is flexible and resiliently yieldable, runs the risk of being deformed by clamping. This is a deformation which, if it occurs, will persist since the capsulation operation seals the inner volume of the double top. SUMMARY OF THE INVENTION

The object of the present invention is to realise a method, an apparatus and an arrangement for screw capsulation of double tops which limits or totally obviates the above-disclosed shortcomings and drawbacks within the prior art technology. This object is attained by means of a method, an apparatus or an arrangement according to the appended independent Claims.

The method according to the present invention comprises the steps: that a rotationally elastic element is disposed between a gripping member for each respective cap and a drive member for each cap which rotates the gripping member for screw tightening of each one of them; that the angle of rotation of each respective drive member is continuously registered; that the angle of rotation of each respective gripping member is continuously registered; and that the rotation by each respective drive member of its associated gripping member is discontinued when a predetermined difference - corresponding to an intended tightening torque for the cap - has occurred between the angle of rotation of the gripping member and the angle of rotation of the associated drive member.

The above-mentioned predetermined angle difference may also be maintained for a predetermined time in order to ensure, in certain practical applications, that the sought-for tightening torque is obtained.

The apparatus according to the present invention comprises: a self-locking chuck for each capsulation side displaying, on rotation in a first direction, a gripping function and, on rotation in a second direction a releasing function and intended, in said first direction, to grip and twist a cap and also, in said second direction, to release the cap, as well as a drive member for adjustably rotating each respective chuck. Further, a rotationally elastic element is disposed between each respective drive member and each respective chuck and a first angle indicator is connected between each respective rotationally elastic element and each respective drive member, and a second angle indicator is connected between each respective rotationally elastic element and each respective chuck. Control means are also provided for controlling each respective drive member, the control means discontinuing the motor rotation of each respective chuck when the angle difference between each respective first and second angle indicators reaches a predetermined value corresponding to a desired tightening torque of each respective cap.

As a result, there will be obtained an apparatus for screw capsulation which, with a high level of repeatability, is capable of screwing caps in position with high precision as regards tightening torque. Further, there will be realised an apparatus where the tightening torque may readily be adjusted and, as a result, if desired also regulated in order to achieve different properties.

In one embodiment of the present invention, the control means of the apparatus may be disposed to maintain said predetermined angle difference during a predetermined time. This is in order, in demanding practical applications, to ensure that the sought-for tightening torque is obtained. The time which is required in order for the effects of any possible elasticity in the system to dissipate can amount at maximum to about 1 second.

The rotationally elastic elements may consist of any rotationally elastic construction elements or materials whatever which display the property that their rotational twisting increases with increased applied torque. It may, for example, be a body of polymer, some form of spring (helical or spiral spring, leaf spring), a torsion arrangement etc. In one embodiment of the present invention, each respective spring may consist of a helical leaf spring of spring steel. The first angle indicator may, in one embodiment, be connected to the drive member in order to provide continuous information about the actual angle of rotation for the output shaft of the drive member and the second angle indicator may be disposed in direct connection to the rotationally elastic element.

In that the apparatus is provided with its chucks in line with each other and is disposed to apply from opposing directions a cap to each end of a double top placed between the apparatuses, two caps from opposite directions may be screwed in position simultaneously on the double top intended for capsulation and placed between the chucks.

Further, a device may be provided for positioning a double top in position for capsulation. Said device need not, according to the present invention, hold the body rotationally stable, but may permit rotation of the body along an axis coinciding with the axis of rotation of the chucks. This will hereby avoid the risk that the double top is deformed as a result of excessive clamping forces. Such clamp deformation could otherwise be permanent, since the caps seal the inner volume of the double top.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING One preferred embodiment of the present invention will now be described in greater detail hereinbelow, with reference to the accompanying Drawing, in which equivalent or similar parts carry the same reference numeral and further in which:

Fig. 1 schematically illustrates one example of an arrangement for capsulation of a double top.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

With reference to Fig. 1, one embodiment of the present invention is shown where two apparatuses for screw capsulation are arranged to capsulate a double top 1. The arrangement consists of two capsulation units turned to face with their respective chucks 2 towards one another and disposed to apply, from opposite directions and simultaneously, a screw cap 3 at each end of the double top 1.

In that this takes place simultaneously, handling of the double top will be simplified since no non-rotational retention of the double top proper will be required in order that caps will be able to be tightened with the desired torque. The simultaneous tightening of the caps will balance one another out, in which event the means handling the double top need only hold the double top at the correct height. There is no requirement of holding the double top rotationally stable. On the contrary, the double top may rotate during the capsulation proper. In the illustrated example, the centre axis to the threaded portions 4 of the double top intended for the caps (hereafter referred to as the axis of threads) with the centre axis of the double top. Such is not always the case, since double tops may also display a configuration deviating from rotation symmetry in portions between the threaded portions. On each side of the double top, there is provided in the arrangement a chuck

2 with a through aperture for a cap 3 in line with the axis of the threads. The chucks 2 are further linearly reciprocally disposed in a direction in towards and away from the double top, respectively, with the aperture and the axis of rotation of the chuck in line with the axis of the threads.

At that side of the chuck 2 facing away from the double top 1 there is disposed an outlet from a capsulation magazine 5. The caps 3 in the magazine 5 are disposed in parallel edge-to-edge. The magazine slopes down towards the outlet and the caps are slidably displaced by force of gravity along the sloping plane towards the outlet where the leading cap is located with its centre line in line with the axis of rotation of the chuck and the axis of the threads. The magazine may also be set in vibratory motion in order to further increase reliability in the advancement of the caps 3.

For discharging caps 3 from the outlet of each respective magazine 5, there is disposed a linearly reciprocating gripping member 6 which, by applying and activating an area of governable reduced air pressure against the outside of the each respective cap, sucks it in position and then displaces it by means of a pneumatic cylinder ahead of it to a starting position in each respective chuck 2.

When a cap 3 is located in the starting position in a chuck 2, the rotation of the chuck is initiated in a first direction which coincides with that direction in which the cap is to be screwed in position. The chuck 2, which is here of the self-locking type, commences by gripping the cap by applying jaws against the radially outer edge portion of the cap. The greater the number of jaws and the larger the abutment surface which is utilised on gripping the cap the smaller will be the risk of deformation as a result of clamping. Advantageously, the jaws are uniformly distributed around the cap and designed in their respective engagement surfaces with a surface structure which is of complementary form in relation to the outer surface structure of the edge portion of the cap, which may, for example, be ridge or land- shaped in order to realise improved grip.

The rotation of the chuck 2 is executed by a motor 7 of servo type which, via a gear wheel 9 and a toothed belt 8, may transfer a rotation movement to a first end of a rotationally elastic element in the form of a leaf-shaped helical spring 10. The other end of the helical spring 10 is connected to the chuck 2 by the intermediary of each respective gear wheel 11 and toothed belts 12. The gear pulley 11 disposed at each respective chuck 2 is non-rotationally disposed at that part of the chuck 2 which realises its self-locking, tightening and, on change of rotational direction, releasing function.

In order to regulate the distance of the chuck 2 to that double top 1 which is to be capsulated, in actual fact to advance the cap during rotation so that the thread of the double top 1 will mesh with and subsequently follow the cap during the screwing in process, an adjustable linear tension device 13 is provided in combination with a second motor 14 which displays a thread along its outgoing shaft 15. This outgoing shaft 15 is parallel with the axis of the above mentioned threads and cooperates with an element of complementary formation to the thread of the outgoing shaft 15 in the form of a nut 16 which is connected to the chuck 2 for governing its position in relation to the double top 1.

Further, the apparatuses for capsulation are each carried by a mounting 17. The motor 7 for driving the chuck is fixedly disposed at the mounting 17, like the gear wheels 8 connected via the toothed belt 9, the motor 14 in the linear tension device and the magazine 5 for the caps.

At a frame 18 which is displaceably disposed in relation to the mounting 17, the chuck 2 is disposed with its toothed belt 11, the gear pulley 12 connected to the other end of the leaf-shaped helical spring 10, the leaf-shaped helical spring 10, as well as the nut 16. As was previously mentioned, the displacement is governed in that the nut 16 is in engagement with a complementarily formed thread on the outgoing shaft 15 of the motor 14, the regulation of the motor 14 entailing regulation of the relative position of the frame 18 and thereby the position of the chuck 2.

By continuously registering the actual angular position of the outgoing shaft of the motor 7 and comparing it with a continuous registration of the angular position of the shaft which connects the other end of the leaf-shaped helical spring 10 to the gear pulley 11, there will be obtained continuous information about the actual angular difference which in turn reflects the torque exercised by the chuck 2. This presupposes however a simple calibration in response to selected helical spring 10, and a correction for any possible gearing in the belt transmissions 8, 9; 11, 12. In the present embodiment, the gear ratio is 1:1, for which reason no gear correction is thus required in this case. For the continuous registration of the actual angular positions, use is made here of information direct from the servo-motor 7 as well as information from an angle indicator 19 which is connected to that shaft which connects the second end of the leaf-shaped helical spring 10 to the gear pulley 11. In order to permit displacement of the frame 18 in relation to the mounting 17 while retaining transfer of the rotational movement of the motor 7, as well as the rotational reading of the angle indicator 19, on the one hand the shaft which connects the second end of the leaf-shaped helical spring 10 to the gear pulley 11 and, on the other hand, the connection between the gear pulley 8 connected to the motor 7 via the toothed belt 9 and the first end of the leaf-shaped helical spring 10 are disposed to be telescopic by traditional spline arrangements 20.

Claims

WHAT IS CLAIMED IS:

1. A method of applying screw caps (3) on packaging blanks (1) of the double-top type, characterised in that a rotationally elastic element (10) is disposed between a gripping member (2) for each respective cap (3) and a drive member (7 a) for each respective cap (3), which rotates the gripping members for screwing in position of each one of the caps (3); that the rotational angle of each respective drive member (7a) is continuously registered; that the angle of rotation of each respective gripping member (2) is continuously registered; and that the rotation by each respective drive member (7a) of the associated gripping members (2) is discontinued when a predetermined difference has occurred between the angle of rotation of the gripping member (2) and the angle of rotation of the associated drive member (7a) corresponding to an intended tightening torque for each respective cap (3).

2. The method as claimed in Claim 1, characterised in that said predetermined angle difference is maintained during a predetermined time.

3. An apparatus in screw capsulation of packaging blanks (1) of double-top type comprising, a self-locking chuck (2) for each capsulation side displaying, on rotation in a first direction, a gripping function and, on rotation in a second direction, a releasing function and intended, in said first direction, to grip and rotate a cap and, in said second direction to release the cap; and a drive arrangement for controllable rotation of each respective chuck (2), characterised in that a rotationally elastic element (10) is disposed between each respective drive member (7 a) and each respective chuck (2), that a first angle indicator is connected between each respective rotationally elastic element (10) and each respective drive member (7a), that a second angle indicator is connected between each respective rotationally elastic element (10) and each respective chuck (2), that control means are provided for regulating each respective drive member, the control means discontinuing the motor rotation of each respective chuck (2) when the angle difference between each respective first angle indicator and second angle indicator reaches a predetermined value corresponding to a desired tightening torque of each respective cap (3).

4. The apparatus as claimed in Claim 3, characterised in that the control means are disposed to maintain said predetermined angle difference during a predetermined time.

5. The apparatus as claimed in Claim 3 or 4, characterised in that the ro itationally elastic elements consist of springs, preferably helical leaf-springs (10).

6. The apparatus as claimed in any of Claims 3 to 5, characterised in that each respective first angle indicator is connected to each respective drive member (7a) for continuous information on the actual angle of rotation of the outgoing shaft of each respective drive member (7 a); and that each respective second angle indicator is disposed in direct association with each respective rotationally elastic element (10).

7. An arrangement for the simultaneous application of two caps (3) from opposing directions on a double top (1) intended for capsulation, characterised in that an apparatus according to any of Claims 3 to 6 is disposed with its chucks (2) in line with one another, and that they are disposed, from each opposite direction, to apply a cap (3) at each end of a double top (1) placed between the apparatuses.

8. The arrangement as claimed in Claim 7, characterised in that means are provided for placing a double top (1) in position for capsulation and that said means permit rotation of the double top (1) about an axis coinciding with the common axis of rotation of the chucks (2).