Technical Field

The present invention relates to guiding means, in particular guiding means for use in a filling machine for filling packaging containers made from a paper-based packaging laminate and having a folded and sealed top.

Background

Though the present invention relates to guiding means and to a cam curve and its cooperation with a cam follower it is considered important to explain the quite narrow context in which the present invention evolved, namely a filling machine for filling packaging containers of gable-top type. In such a filling machine, a sleeve formed from a packaging laminate is folded and sealed in one end, sterilized and filled with a flowable product, such as a beverage. The top end is folded and sealed in a particular way such that the characteristic gable shape is achieved. In a folding step the packaging material is folded along weakening lines or crease lines and in order to manage perfect folds and seals at a rate of thousands of packages per hour it may be preferred to pre-fold the crease lines. By means of this operation the container top will readily fold during the final fold and seal operation. Variations of such a prefolding operation are disclosed in numerous patent applications, e.g. US6357203, US5588279, US3120089. According to one prefolding technique an anvil element is inserted in the top of the packaging container during the prefolding operation. The purpose of the anvil element is to provide a sharp edge to prefold the packaging material against. The anvil element is, for obvious reasons, inserted through the open top end of the container, and after the prefolding operation is performed it is removed. Due to the fact that prefolding is performed at a high rate, and that the top after prefolding is folded inwards, it may occur that the container is pulled upwards with the anvil element, causing a failure in the filling machine.

One of the applications for the present invention is manifested in a mechanism for preventing the container from being pulled upwards.

Notwithstanding the very narrow context in which the present invention was evolved, the present invention may also be seen in a larger perspective. In another context the present invention enables a cam follower from following a predetermined path during a reciprocating motion in a cam path. Summary

As a solution to the stated problem the present invention provides guiding means comprising a cam path for guiding a cam follower. The cam path is functionally divided into an engagement stroke and a disengagement stroke each having a first end and a second end, and the two strokes coincide at the respective ends thereof such that they follow a common path. Further, there is a first junction where the engagement stroke adjoins a rectilinear portion of the disengagement stroke and a second junction where the disengagement stroke adjoins a rectilinear portion of the engagement stroke. While not excluding another formulation based on what is considered as valid prior art the present invention is characterized in that in the area of the first and second junction respectively, each rectilinear portion is depressed in relation to the adjoining stroke portion.

The benefit and further nature of the depressions will be specified in the detailed description and to some extent in the further embodiments of the invention as defined below.

In one or more embodiments it is preferred that the depression has a width

corresponding to the width of the rectilinear portion, such that a partial delimiter is formed towards the adjoining stroke portion. In this way the rectilinear portion will display an unobstructed path for the cam follower, while at the same time a partial wall is formed in the area of the junction, preventing the cam follower from entering the wrong stroke portion as it passes the junction.

In still further embodiments it may be preferred that the engagement stroke and the disengagement stroke, respectively, each are formed from a rectilinear stroke portion and a curved stroke portion, and wherein the curved stroke portion of the engagement stroke adjoins the rectilinear stroke portion of the disengagement stroke, and vice versa. In a related embodiment the disengagement stroke may be identical to the engagement stroke, though being rotated 180° in the plane of the cam path.

The depression may be localized to the area of the junction, yet it may also extend over a greater length of the stroke. One example could be that the depression is formed from each stroke having a gradual decrease in depth along its rectilinear stroke portion towards its curved stroke portion. In an embodiment where this is true for both strokes, and the strokes further are arranged to have the same depth at a corresponding position of the stroke (the start, the middle, the end or anywhere inbetween, two advantages will be obtained. Firstly, the preferred relationship for each junction will be automatically obtained, and secondly, the cam curve may be machined in a simple manner from the same tool. Further embodiments are disclosed in the detailed description.

To better benefit from the advantages of the present invention according to any embodiment thereof it is preferred that it further comprises a cam follower. In one or more embodiments it is preferred that the cam follower is biased towards the cam path such as to follow a profile of the cam path as defined by the depression. Towards the cam path would correspond to a direction orthogonal to the plane in which the cam follower moves when following the cam curve.

One way of biasing the cam follower is to use a coil spring, forcing the cam follower in the correct direction. To further increase the stability of the biased cam follower it may include a guide arrangement, one embodiment of which is disclosed in the detailed description.

Brief Description of the Drawings

Fig. 1 is a schematic view illustrating a device according to one embodiment of the present invention in a first use position, a disengaged position.

Fig. 2 illustrates the device of Fig. 1 in a second use position, an engaged position.

Fig. 3 is an exploded view of a device which may be used for the embodiment of Figs. 1 and 2.

Fig. 4 is a schematic graph illustrating various cam profiles.

Detailed Description of Embodiments

Fig. 1 and Fig. 2 show schematically the general thinking behind a device where the invention according to one embodiment thereof may be used.

Starting with Fig. 1 a packaging container 102 is shown. The packaging container 102 is indexed incrementally between the different processing steps performed in a filling machine, and in the position it is shown it has been made ready for prefolding or prebreaking. Crease lines 104, 105 are schematically shown in the upper portion of the container 102, and these are the subject for the prefolding action.

During prefolding an anvil element 106 is inserted into the container and is positioned below a transversal crease line 105 (see Fig. 2). The drawing of Fig. 1 is highly schematical, yet for the purposes of understanding the overall technique it will do, and it is shown how the anvil element 106 is arranged on a frame structure 108. The frame structure 108 in its entirety moves up and down in a reciprocating fashion during operation, thus moving the anvil element 106 into and out of packaging containers 102. An intermittent conveying motion of the packaging containers will thus have to be synchronized with the reciprocation motion of the frame structure 108. This may be performed in different ways, and there are several known ways of doing it, yet these will not be discussed any further in the present application.

When the anvil element 106 is arranged inside the package, a prefolder element (not shown) will provoke a fold along one or more of the crease lines, e.g. as described in any one of the cited patent documents.

Once the prefolder element has engaged the packaging container and thus provoked the fold, it will disengage the package and be moved out of the way. One way of operating the prefolder element, or rather elements since they are usually arranged to act in opposed pairs, is to have the elements mechanically linked to the frame structure 108 and have their motion controlled by a cam curve. This provides a simple and reliable control system for which the synchronization of motions is more or less failsafe. There are more or less elaborate alternatives to such a construction, ranging from a solution where the prefolder elements are comprised by an inverted V-shaped slot of a plate, or prefolder elements having a separate drive system.

After the completion of this prefolding action the anvil element 106 is to be retracted from the interior of the packaging container 102, which for the present embodiment is performed by raising the frame structure 108 as mentioned before. In this operation there may be a risk for the packaging container to join the upward motion of the anvil element, since the fit of the anvil element inside the packaging container may be quite snug. To prevent this from happening a pivotably arranged stopper means 110 is arranged, and in Fig. 1 it is located in a first position. The stopper means 110 is hingedly suspended at a lower end thereof, at pivot point P (referring to the views of Figs. 1 and 2), and a cam follower 112 is arranged in an upper portion of the stopper means 106 (referring to the same views). The cam follower 112 is arranged in a cam curve 114, positionally locked to the frame structure 108. When leaving the packaging container the anvil element will have to pass the stopper means engaging the upper rim of the packaging container. To allow for this passage it is preferred that the anvil element has an hourglass shape or similar. In the first position the stopper means 110 allows for a packaging container to be indexed into position. Looking at Fig. 2, a packaging container has indexed into position and the frame structure 108 has been lowered. The lowering of the frame has resulted in two events worth mentioning; firstly the anvil element 106 has been lowered into the package, and secondly the stopper means 110 has assumed a position in which it prevents the packaging container from moving upwards. In order for the stopper means 110 to arrive at this position the cam follower 112 has followed the cam curve 114 along the right branch thereof (as seen in the view of Figs. 1 and 2). The shape of the cam curve 114 enables for the stopper means to assume a position in which it engages the packaging container 102 (the position of Fig. 2), maintains this position a predetermined period of time, and return to a position where the it is disengaged from the packaging container (the position of Fig. 1) while the frame structure follows a continuous reciprocation motion up and down (in the reference system of Figs. 1 and 2). The stopper means 110 thus may assume one static engaged position, corresponding to the position of Fig. 2, one static disengaged position, corresponding to the position of Fig. 1, and two dynamic transfer positions where it is moved between the two static positions. The cam curve 114 being the control means obviously mirrors this behaviour, and for the purpose of simplifying the explanation the cam curve 114 may be said to comprise an engagement stroke 114A and a disengagement stroke 114B. The engagement stroke 114A runs from the lower end of the cam curve 114 to the upper end thereof, along the route of the cam follower (along the right in Figs. 1 and 2). The disengagement stroke 114B runs from the upper end of the cam curve 114 to the lower end thereof, also along the route of the cam curve (along the left of Figs. 1 and 2). Both strokes begin with a rectilinear segment, corresponding to the disengaged position and the engaged position, respectively. The end positions are common for the disengagement stroke and the engagement stroke, and consequently there are two junction points 114C and 114D respectively, where the two strokes meet.

Referring now to the exploded view of Fig. 3 for a more detailed explanation of the construction of the cam curve 114 and the cam follower 112: Even if the illustration of Fig. 3 is less schematic than the one of Fig. 1 and 2, the same numbering has been used for like components, since this is believed to increase clarity.

In each junction point 114C and 114D, there is a potential risk of the cam follower following the wrong path, or that it gets stuck in the junction point. However unlikely a machine including such a device performs its iterative reciprocating motion about 10 000 times per hour, meaning that even unlikely occurances may happen.

Several efforts have been made to circumvent this potential problem. According to the present invention a solution is provided in the configuration of the cam path 114. In each junction point, where the engagement stroke enters the common rectilinear path of the disengagement stroke and where the disengagement stroke enters the common rectilinear path of the engagement stroke, the cam paths will be arranged at different levels. Simply put the rectilinear portion of the stroke will be arranged at a lower level such that the other portion follows a step function in regard of its depth. The rectilinear portion of the stroke will follow a smooth path, while the stroke entering it will experience a step S (see Fig. 3) downwards.

This difference in levels will enable a more reliable guidance of the cam follower, since it will be less prone to take a wrong turn in the junctions. Each step function will act as an additional delimiter or a one way valve figuratively speaking, in that nothing prevents the cam follower from taking the right way, while a partial wall will stop it from taking the wrong way.

The step functions may be accomplished in several different ways; there may be a local depression of the rectilinear stroke in the area of the junction; there may be a local protrusion in the other stroke in the area of the junction; each of the strokes may have a continuous slope from the beginning to the end of the stroke; etc. In the embodiment of Fig. 3 it is indicated that the rectilinear portions of the engagement stroke and the disengagement stroke of the cam path slopes upwards in the direction of movement of the cam follower, while the transitions portions are essentially flat.

Regarding terminology relating to directions; in the above description references to directions have been based on either the views of the drawings or to an intuitive meaning, all with the goal to simplify understanding. To generalize the expressions the following interpretations may be made: "Lower" will correspond to a direction away from the cam follower, essentially orthogonally to the plane in which the cam curve is arranged, and inwards in the illustrations of Fig. 1 and 2. "Depression" will correspond to a positional shift in the same direction as "lower" as will "downwards", while "protrusion" will correspond to a positional shift opposite to "depression". The "engagement stroke" corresponds to the stroke in which the stopper means 110 engages with the packaging container 10, while it may be noted that the stopper means only engages with the packaging container during the final portion of the stroke. The "disengagement stroke" corresponds to the stroke in which the stopper means is disengaged from the packaging container. References to "left" and "right" refer to the arrangement in Figs. 1 and 2 respectively.

To further improve the performance of an inventive device the cam follower may have a resilient suspension, such that it is biased towards the cam path 114 (rather, orthogonally to, and towards a plane including the cam path). In this way the cam follower 112 will always strive towards being arranged in the bottom of the cam path 114 which to an even higher extent prevents it from following the wrong path.

The biasing function may be provided as exemplified in Fig. 3. The cam follower 112 is arranged at one end of a shaft 118, while the other end of the shaft 118 is slidably attached to the stopper means 110. A biasing force is provided by a coil spring 120 arranged concentrically around the shaft 118. Suspension means 122 may be arranged to improve the performance of the cam follower 112. The construction is simple, and it is to be understood that a skilled person given the task of doing so could readily come up with alternative constructions for the achievement of the requested function. Not all elements of Fig. 3 are described, since it is considered superfluous. It is readily apparent what their function is, and the skilled person looking at Fig. 3 would on the one hand realize the function of the elements, and on the other hand be able to generalize and understand that there are other constructional solutions.

In the graph of Fig. 4 some various cam profiles are shown. The profile starts from the left with the rectilinear path of the stroke, and the profile indicates how the depth of the stroke may vary according to some exemplifiary embodiments. A shift downwards indicates an increase in depths. Note that three examples given do not represent an exhaustive list.

The materials chosen for the manufacture of the different parts of the present invention are not crucial. Any suitable material may be used, and what is considered as suitable may vary with the particular application. In the embodiment of Fig. 3 the stopper means as well as the piece of material housing the cam curve are made from stainless steel, while the cam follower is made from PTFE, yet the present invention should not be limited in this aspect, since the skilled person would realize that these materials may be replaced by other materials.