EP1157815A2

EP1157815A2 - Method and device for wicket stacks

Info

Publication number: EP1157815A2
Application number: EP01660074A
Authority: EP
Inventors: Hannu Lahtinen
Original assignee: Amerplast Oy
Current assignee: SUOMINEN FLEXIBLE PACKAGING LTD.
Priority date: 2000-04-27
Filing date: 2001-04-26
Publication date: 2001-11-28
Also published as: EP1157815A3; FI111238B; PL347307A1; FI20000993A0; FI20000993L

Abstract

Method and device in the manipulation of product stacks, so-called wicket stacks, composed of bag-like and/or sheet-like products by means of wicketing. In wicketing, products are during their manufacturing process stacked in wicket stacks into a wicket pin/wicket pins (21, 21') located in a wicket pin assembly (30; 40; 50; 60), which stacks are removed from the wicket pin/pins (21, 21') manually or by means of a machine. According to the invention the position of the wicket pin/pins (21, 21') with respect to their base (32, 42, 52) and/or the position of said base (32; 42; 52) with respect to the conveying mechanism (7) transferring the wicket pin assembly (30; 40; 50; 60) is changed from a first position (A) used in the forming of the stack to a second position (B) that substantially differs from said first position. The second position (B) is advantageous for the removal of the stack (33) from the wicket pin/pins (21, 21') manually or by means of a machine, or for another operation conducted for the stack.

Description

The invention relates to a method in manipulation of stacks formed of bag-like and/or sheet-like products, in which stacks formed of said products into wicket pin/pins in connection with the manufacturing process of the same are subjected to operations, advantageously said stacks are removed from the wicket pin/pins manually or by means of a machine. The invention also relates to a wicket pin assembly for implementing the method.
In the manufacturing process of bag-like and/or sheet-like products, such as plastic bags and films, shopping bags of plastic or similar products of paper, the original material in the form of a film or a sheet is seamed and/or cut to form a single product, such as a plastic bag. Such a manufacturing process is typically highly automated, and continuous in nature, wherein single products are produced in the manufacturing line at high speed, for example several articles within a second. To enable flexible further processing of the manufactured product said product is stored in connection with the manufacturing process in stacks formed on top of each other into so-called wicket pins. One such wicket stack can contain tens or hundreds of single products on top of each other.
In the following, the manufacturing process of plastic bags as well as storing of the same in wicket stacks in wicket pins are described as examples of a manufacturing process of the aforementioned kind.
In the manufacture of plastic bags, a plastic film coming from a reel is guided as original material at suitable tension via rolls or the like to a so-called sealing station, in which the film layers guided on top of each other by means of heat sealing are formed into a bag by sealing, which bag in connection with the sealing at the same time is detached or released as a separate unit to the manufacturing line. Thereafter the single bag attained in this manner is lifted up from the manufacturing line for example by means of arms fixed to a rotating pivot, which arms utilize negative pressure when gripping the bag. By means of their rotating movement the aforementioned arms move and stack the plastic bag into wicket pins in a stacking station, at the same time releasing their grip from said bag. For the purpose of stacking the bag in the wicket pins, the bag itself, or alternatively, an additional part released from said bag at a later stage (for example a part detached by tearing) has, in connection with the above-described sealing, been provided with holes that match to the wicket pins. The wicket pins themselves are attached to a base plate or a corresponding base, which is further connected to a conveying mechanism, for example to an endless chain, belt or a rotating drum. To said conveying mechanism several wicket pins with their bases, i.e. so-called wicket pin assemblies are connected in such a manner that when one wicket stack is finished in the stacking station, i.e. when the pins/pin connected to one base have/has collected a predetermined amount of bags, the thereby produced wicket stack is replaced with an empty wicket pin assembly by means of the transport mechanism, in a manner synchronized with the function of the rest of the apparatus. At the same time said full wicket stack in the wicket pin assembly of its own is transferred forward to a so-called removal station. In the removal station the wicket stack is removed from the wicket pin assembly either manually or by means of a machine.
An apparatus with an operating principle of the above kind, suitable to be used in the manufacture of plastic bags, is disclosed for example in the patent publication US 5,667,468. A similar manufacturing process is described hereinbelow again at a more appropriate part of the text and by means of Fig. 1 as an example of such a manufacturing process in which the method and device according to the invention can be applied.
There are also other solutions of prior art to manufacture bag-like and/or sheet-like products from a film, sheet or the like used as original material, but these solutions will not, however, be described in this context as they do not constitute a part of the invention. Similarly, there are various methods for stacking aforementioned products into a wicket pin/wicket pins, which methods will not be described in more detail in this context either, as they are not part of the invention. In the following, such solutions of prior art are described which relate to the wicket pin assembly itself, in other words to the structure and functions of the base used in the process of fixing the wicket pin/pins to the conveying mechanism, and further to methods and devices for removing the wicket nips from said wicket pin assembly.
Patent publication US 5,667,468 discloses a solution for fixing the wicket pins to a conveyor, in this case to a base plate to be fixed on an endless belt. The method described in the aforementioned publication allows the act to change the mutual distance of the wicket pins attached to the base plate by means of a screw rod, wherein the wicket pin assembly can be adjusted for different mutual distances of the wicketing holes and thus for different products. When the wicket pins are positioned vertically at right angles with respect to the base plate, the angle of the wicket pins with respect to the base plate, in other words the angle of inclination of the pins can be fine-tuned/set by means of adjustment screws, but during the actual use the wicket pins have substantially fixed positions with respect to the base plate and the conveyor.
Patent publication US 5,618,147 discloses a wicket pin assembly in which instead of fixed pins, a U-shaped so-called wicket wire functions as wicket pins. The base plate is equipped with a fixing mechanism to which the wicket wire is fixed vertically substantially at right angles with respect to the base plate. When a desired amount of products has been stacked in the wicket wire functioning as wicket pins, it is possible to remove said stack from the base plate together with the wicket wire, and the base plate can at the same time be equipped with a new wicket wire. The fixing mechanism of the wicket wire to the base plate includes the possibility to fine-tune/set the angle of inclination of the wicket wire, but during the actual use the wicket wire is still in a substantially fixed position with respect to the base plate and the conveyor.
A wicket pin assembly whose function during the use corresponds to a prior art wicket pin assembly in which, during the use, the wicket pins have substantially fixed positions with respect to the base plate and the conveyor, is described again hereinbelow at a more appropriate part of the text in connection with the description of the method and device according to the invention. A wicket pin assembly that illustrates primarily the functional aspects of the state of the art with respect to the present invention is described in principle and in a simplified representation in the same context in Fig. 2.
The above-described wicket pin assemblies according to the state of the art share such a feature that the removal of the stacks from the wicket pins (US 5,667,468) or the removal of the stack together with the wicket wire (US 5,618,147) in the removal station requires a lifting movement in the direction of the wicket pins and/or wicket wire. When the base plates of the wicket assemblies are fixed to the conveying mechanism typically on a horizontal plane, the stacks are thus removed upwards by means of an upwards-directed lifting movement. Such a lifting movement, when it is conducted manually as a frequently repeated work stage, is very strenuous and wearing for the worker. Due to the stacking process that takes place in the stacking station the wicket pins are also typically installed in such a fixed position on their base that when they enter the removal station at the location of the user of the machine, the wicket pins incline 6 to 10 degrees away from the vertical position and from the user of the machine. Thus, the removal of the stacks is further complicated, because the user is forced to work with his/her arms and wrists in an unnatural position, which in the long run easily causes stress injuries for the worker. For example due to the aforementioned reasons, the aim has been to mechanize and automate the removal of the stacks from the wicket pin assembly.
Patent publication US 5,911,553 discloses a solution in which fixed wicket pin assemblies that are attached to a rotating drum are removed from said wicket pin assemblies by means of a machine and automatically by means of a mechanical actuator. The wicket pins/wicket pin assemblies arrive in the removal station in the same position, slightly inclined outside said actuator from the vertical position, in which the stacking of the product into the wicket pins is conducted. The mechanical actuator removes the stacks from the wicket pins by means of a substantially upwards-directed lifting movement similar to the one used by a worker in a corresponding situation while performing the same process. Because in the aforementioned solution a mechanical actuator is designed to perform movements resembling the set of movements performed manually by the worker, this results in that the structure of the actuator becomes complex and expensive. Furthermore, as the stack hangs in a folded position during the lifting stage, the risk that the product is damaged is increased especially if the stack is gripped only from the end where the wicket holes are located. The risk that the product is damaged because the stack is folded is increased when larger products, for example large plastic bags are manufactured, because the weight of the stack is thereby also increased in a corresponding manner.
The above-described solutions according to the state of the art share such a feature that the position of the wicket pins or wicket wire on the base and with respect to the conveying mechanism is designed in such a manner that it is advantageous in view of stacking the product into the wicket pins in the stacking station. Because the aforementioned position of the wicket pin assembly remains substantially the same during the shift from the stacking station to the removal station, this complicates the removal of the stack manually or by means of a machine, or other corresponding process to which the stack is subjected, in a manner described above.
It is an aim of the present invention to introduce a method in which it is possible to avoid the problems of prior art described above in the removal of stacks formed into a wicket pin assembly manually and/or by means of a machine.
To attain this purpose, the method according to the invention is primarily characterized in what will be presented in the characterizing part of claim 1.
Furthermore, it is a purpose of the present invention to disclose a wicket pin assembly to implement the aforementioned method. The wicket pin assembly according to the invention, in turn, is primarily characterized in what will be presented in the characterizing part of the independent claim 12.
The other dependent claims present some preferred embodiments of the method and wicket pin assembly according to the invention.
The present invention is based on the observation that the removal of the stack from the wicket pin assembly both manually and by means of a machine can be considerably facilitated if the wicket pin assembly itself actively takes part in the delivery of the stack, in other words for the delivery/removal of the stacks the wicket pins are transferred and/or turned to a second position that differs significantly from the first position of the wicket pins used in the forming of the stacks, said second position being advantageous especially in view of the delivery/removal of the stacks.
In a preferred embodiment of the invention the wicket pins are transferred and/or turned to a substantially horizontal position and/or substantially towards the worker for the delivery/removal of the stack. Thus, in the removal station the stack can be pulled out of the wicket pin assembly in a direction advantageous in view of the worker, in other words the worker can pull the stack off the wicket pin assembly horizontally towards himself/herself. This movement is natural for the worker and it is can be conducted more easily. It is also less strenuous than the lifting movement required in the solutions of prior art. If the aim is to conduct the removal of the stack and/or any other process for the stack preceding the removal automatically and by means of a machine, in the actuator performing this task it is substantially necessary to conduct movements only in the direction of the x-, y- arid z-axes which are at right angles with respect to each other, the implementation of which movements is easy and thanks to the straightforward constructions the costs remain low.
When the wicket pins are turned to a substantially horizontal position, the product stack is at the same time hanging freely in a substantially vertical position, which reduces the risk that the stack is damaged during removal and/or another process. This is a considerable advantage especially when larger and thereby heavier products are manipulated. If the stack removed from wicket pins fixed permanently to the wicket pin assembly is simultaneously threaded by its wicket holes to a wicket wire, carrier sleeves or the like, it is easier to perform this process both manually and by means of a machine when the stack hangs freely in the vertical position. After the stack is removed, in said horizontal position of the wicket pins it is also easy to provide the wicket pins with new sleeves or the like, or to install a new wicket wire in its place in the assembly, said wicket wire functioning in a manner similar to wicket pins.
Because the solution implementing the method according to the invention can be primarily implemented in the wicket pin assembly itself, the method can be easily adopted in already existing apparatuses by replacing the fixed-position wicket pin assemblies connected to the conveying mechanism with wicket pin assemblies according to the invention.
In the following, the invention will be described in more detail by means of examples and with reference to the appended drawing, in which

Fig. 1: shows in a side-view the principle of stacking plastic bags into wicket pin assemblies according to the invention fixed on an endless belt,
Fig. 2: shows in a side-view the principle of state of the art wicket pin assembly and the functional aspects of the same in view of the present invention when seen from the cross-sectional plane of an endless belt,
Fig. 3: shows in a side-view the principle of a first embodiment of the wicket pin assembly according to the invention, when seen from the cross-sectional plane of an endless belt,
Fig. 4: shows in a manner similar to Fig. 3 the principle of a second embodiment of the wicket pin assembly according to the invention,
Fig. 5: shows in a manner similar to Fig. 3 the principle of a third embodiment of the wicket pin assembly according to the invention,
Fig. 6: shows in a side-view the principle of an embodiment according to the invention in which the manipulation/removal of the stack is conducted in the end of an endless belt, and
Fig. 7: shows in a top-view the principle of the embodiment of the invention according to Fig. 6.

Fig. 1 shows in a side-view the principle of stacking plastic bags into wicket pin assemblies according to the invention that are fixed on an endless belt, in connection with the manufacturing process of the product.
In Fig. 1 a plastic film 1 coming from a reel or the like is guided via rolls or the like at a suitable tension to a sealing station 2, in which film layers guided on top of each other by means of heat sealing are formed into a bag by sealing, which bag in connection with the sealing at the same time is detached as a separate unit to a transfer line 3. The single bag attained in this manner is lifted up from the conveying line 3 for example by means of arms 5 fixed to a rotating pivot 4. The arms 5 are arranged in the pivot 4 in the direction of the axis of said pivot, two or more arms in parallel in such a manner that when the pivot is rotating, the transfer line 3 and the belt 7 do not prevent the movement of the arms. The aforementioned arms can utilize for example negative pressure arranged inside the arms, which negative pressure by means of holes/openings made in the contact point of the arms and the bag, causes the bag to attach to said arms. The arms 5 move and stack the plastic bag into wicket pins in a stacking station 6 at the same time releasing their grip from said bag. For this stacking into the wicket pins the bag itself, or alternatively an additional part released from said bag at a later stage is in connection with the sealing in the sealing station 2 provided with holes that match to the wicket pins 21, 21'. It is also possible that the bag is not provided with aforementioned holes beforehand, but the wicket pins 21, 21' punch the holes to the bag by their pointed ends when the bag is being stacked. The wicket pins 21, 21' themselves are connected to a base 32, which is further connected to the endless belt 7. To the endless belt 7, several wicket pins with their bases, i.e. so-called wicket pin assemblies 30 (Fig. 3) are connected in such a manner that when one wicket stack is finished in the stacking station 6, i.e. when the wicket pins connected to one base have collected a predetermined amount of bags, the thereby produced full wicket stack is replaced with an empty wicket pin assembly 8 by means of the belt 7, in a manner synchronized with the function of the rest of the apparatus. At the same time said full wicket stack in the wicket pin assembly of its own moves forward to a so-called removal station 9. In the removal station 9 the wicket stack is removed from the wicket pin assembly either manually or by means of a machine.
Fig. 2 shows in a simplified side-view the principle of a wicket pin assembly that illustrates primarily the functional aspects of the state of the art in view of the present invention when seen from the cross-sectional plane of the endless belt 7 (see e.g. US 5,667,468). In the wicket pin assembly 20 shown in Fig. 2, the wicket pins 21, 21' are fixed to a substantially stable position on a base 22, which base is attached on the belt 7. In the situation shown in Fig. 2, the wicket pins are also equipped with sleeves 23, 23', which sleeves are removed from the wicket pins along with the stack of bags 25. As was already mentioned above, the mutual distance between the wicket pins 21, 21' and the position of the same on the base 22 can be set for different kinds of products, and the angle 24 of the wicket pins can be fine-tuned or set by means of adjustment screws, the wedge-shaped structure of the base, etc. (not shown in Fig. 2), but during the actual use, the wicket pins 21, 21' have substantially fixed positions with respect to the base 22 and the conveyor 7. The removal of the stack of bags 25 from the wicket pin assembly 20 is accomplished by means of a lifting movement upwards substantially in the direction of the wicket pins 21, 21', which, when conducted manually takes place in such a manner that the worker performing the operation stands in Fig. 2 on the lefthand side of the assembly with respect to the wicket pin assembly 20.
Fig. 3 shows in a manner corresponding to Fig. 2 the principle of a first embodiment of the wicket pin assembly 30 according to the invention. The wicket pins 21, 21' are fixed on a member 31, which is arranged to pivot with respect to the base 32, which base 32 is further fixed on the belt 7. The stacking of the bags in the stacking station 6 (Fig. 1) takes place when the member 31 is in position A, wherein the wicket pins 21, 21' are in a vertical position which is advantageous in view of the stacking process. For the delivery/removal of the stacks in the removal station 9 the member 31 is turned into position B, wherein the wicket pins 21, 21' at the same time turn to a horizontal position and allow the stack of bags 33 to hang freely from the wicket pins 21, 21'. Thus, the stack of bags 33 can be easily removed from the wicket pins 21, 21' by means of a simple horizontal movement substantially in the direction of the wicket pins.
In Fig. 3, the turning of the member 31 and the wicket pins 21, 21' from the first position A to the second position B is arranged to take place by means of an external turning member 34, which turning member is arranged to pivot around an articulation point 35 at its upper end. When the turning member 34 turns around said articulation point, the lower end of the turning member pushes the member 31 from the position A to the position B. The articulation/axis 36 between the member 31 and the base 32 is equipped with return member, such as a spring 37 which, when the turning member 34 returns to its rest position, returns the member 31 and the wicket pins 21, 21' back to the position A by means of springback factor. The movement of the turning member 34 can be attained by placing an active actuator, such as a pressurized air cylinder (not shown in Fig. 3) that moves said turning member, to a suitable location in the turning member 34. Alternatively, the movement of the turning member 34 can be implemented by means of an actuator, such as a rotary actuator functioning by means of pressurized air and turning the axis located in the articulation point 35 around its longitudinal axis, or by means of an electric actuator, such as a step motor or a servomotor.
The advantage of the embodiment of the invention utilizing an external turning member 34 is that the mechanical structure of the wicket pin assembly 30 itself remains simple. Furthermore, only one turning member 34 is typically necessary in the apparatus, which turning member is advantageously placed in connection with the removal station 9.
Alternatively, the movement of the wicket pins 21, 21' from the position A to the position B can be attained also by means of an active actuator placed in the wicket pin assembly itself. Fig. 4 shows in a manner corresponding to Fig. 3, the principle of a second embodiment of the wicket pin assembly 40 according to the invention. In Fig. 4 the movement of the member 41 from the position A to the position B is attained by means of an actuator 43 arranged on the base 42, said actuator being connected to the member 41 by means of a member 44. The member 44 can be a cogged belt, a chain, or the like, which is advantageously arranged to affect the member 41 via a joint/an axis 46. The actuator 43 can be for example a pressure operated rotary cylinder with spring-return, or alternatively an electrically operated device, such as a servomotor. The driving force of the actuator 43 is coupled to the base 42 via contactors/connectors 45 located on said base when the wicket pin assembly 40 is conveyed by the belt 7 to the removal station 9, or to another suitable point on the travel path of the belt 7. When pressurized air is used as driving force according to Fig. 4, the contactors/connectors 45 can have a similar operating principle as plug-in connectors, or when electricity is used, a similar operating principle as slide contacts. When slide contacts are used, the driving force is coupled to the base 42 automatically without separate coupling actions when it is conveyed to said point in the travel path of the belt 7 by means of the belt 7. The return from the position B back to the position A can take place by means of an active actuator 43 or also by means of a suitable passive return member, such as a spring, or the like.
By placing the active actuator 43 to the wicket pin assembly 40 itself in the manner described above, it is possible to attain the advantage that along the travel path of the mechanism (belt 7) conveying the wicket pin assemblies, the turning from the position A to the position B, and vice versa, can be conducted easily at a desired point in the travel path of the belt 7 by adding only the members necessary in the coupling of the driving force of the actuator 43 that are connected to the contactors/connectors 45, to a suitable location along the travel path. Thus, in addition to the removal of the wicket stack 33 from the wicket pin assembly 40 it is also possible to subject the wicket stack 33 to another operation before said removal. Such an operation can be for example perforation of the stack and/or sealing of the stack to join the stacked products together. By placing the active actuator 43 to the wicket pin assembly 40 itself it is not necessary to separately allocate space along the travel path of the belt 7 for an external actuator, such as the turning device 34 shown in Fig. 3, and for the other actuators connected thereto.
Fig. 5 shows in a manner corresponding to Figs 3 and 4, the principle of a third embodiment of the wicket pin assembly 50 according to the invention. In this embodiment the movement of the mechanism (belt 7) conveying the wicket pin assemblies 50 is used for guiding the wicket pins 21, 21' from the position A to the position B. In the solution of Fig. 5, a fixed guiding member, such as a guiding rail or the like (not shown in Fig. 5) rising in the direction of motion of the belt 7, is placed to a suitable location in the direction of movement of the belt 7, advantageously for example directly before the removal station 9. The differential motion of said fixed guiding member and a member 53 that moves along with the belt 7 and is fixed to the wicket pin assembly 50, pushes the member 53 upwards in Fig. 5 when the belt 7 moves to the location of the guiding member at the same time turning the member 51 and the wicket pins 21, 21' fixed thereto from the position A to the position B. The return from the position B back to the position A can take place in a corresponding manner actively by means of a second guiding member for example in the departure from the removal station 9 or also by means of a passive return member, such as a spring 56. In the embodiment shown in Fig. 5 the fixed guiding member is located underneath the wicket pin assembly 50 and the belt 7, but it is obvious that said guiding member can also be placed on the side or on top of the wicket pin assembly 50. The turning and returning guiding members can both also be located on different sides of the wicket pin assembly 50, if necessary.
When the motion of the mechanism, such as a belt 7 conveying the wicket pin assemblies 50 is used for turning the wicket pins 21, 21' in the manner described above, the advantage is attained that other separate active actuators are not necessarily required at all to implement the invention
In the embodiment shown in Fig. 5 the member 51 is arranged to turn with respect to the conveying mechanism (belt 7), substantially without a raising base part (52), which is shown in Figs. 3 and 4 (bases 32 and 42). In all wicket pin assemblies 30;40;50 according to the invention it is possible to select the height of the base so that it is advantageous for the application in question, for example to ensure the free hanging of stacks of different sizes in the position B, or so that it complies with the requirements set by the applied conveying and transfer mechanism.
It is also possible that in the above-described embodiments 30;40;50 of the invention the movement from the position B to the position A can be implemented by means of an active actuator, in other words without a method of the above kind that utilizes the springback factor. On the other hand, said return movement can also be accomplished manually by the worker removing the stack, and/or by a mechanical actuator that performs some other operation for the stack. In a corresponding manner the movement from the position A to the position B can be implemented passively by means of springback factor or the like if the respective movement from the position B to the position A is performed by means of an active actuator.
The turning of the member 31;41;51 and the wicket pins 21, 21' from the position A to the position B is advantageously conducted in the removal station 9, or right before the full wicket pin assembly 30;40;50 arrives in the removal station. When necessary, the turning can, however, be conducted at another location along the travel path of the belt 7 after the formation of stack into the wicket pin assembly 30;40;50 in question has been finished in the stacking station 6. The return from the position B to the position A, in turn, can be conducted either in the removal station 9 or after the removal station before an empty wicket pin assembly arrives in the stacking station 6 again. The turning movement from the position A to the position B and vice versa is synchronized with the operation of the rest of the apparatus, for example under the control of a control system controlling the rest of the apparatus.
The structure of the wicket pin assemblies 30;40;50 shown in Figs. 3 to 5 is intended solely for a turning movement only on a single plane substantially perpendicular to the direction of travel of the belt 7. Within the scope of the inventive aspects of the invention that will be disclosed hereinbelow in the claims, it is however, possible to implement other kinds of structural solutions as well in which the wicket pins 21, 21' turn with respect to the base (e.g. 32;42;52) and/or the belt 7 either on a plane perpendicular to the direction of travel of the belt 7 and/or on a plane directed otherwise. To implement this the base (e.g. 32;42;52) can comprise one or more auxiliary members and necessary joints, axes or the like to fix the wicket pins 21, 21' on said base. Furthermore, the fixing of the base 32;42;52 on the belt 7 can be arranged in such a manner that in the transfer from the position A of the wicket pins to the position B, the base 32;42;52 itself can turn/swing with respect to the belt 7.
Figs. 6 and 7 show a further embodiment according to the invention in which the wicket pin assembly 60 and its base as well as the wicket pins 21, 21' fixed thereto are rotated substantially on the plane defined by the direction of travel of the belt 7 and the upper surface of said belt. The operation can be implemented for example by using a two-piece base in the wicket pin assembly 60, the lower part of the assembly being fixed in a stable manner to the belt 7, but the upper part of the base that is fixed on top of said lower part and connected to the wicket pins 21, 21' is arranged to rotate with respect to the lower part of said base on the plane defined by the direction of travel of the belt 7 and the upper surface. In Fig. 6 the full stacks arriving from the stacking station 6 are transferred by means of a conveying mechanism 7, such as a belt or the like to a turning station 61 in which the wicket pin assembly 60 and its wicket stack are rotated approximately a quarter of a revolution in such a manner that the freely hanging section of the stack, in other words the end of the stack hanging over the base turns to the end of the belt 7 (top-view in Fig. 7). Thereafter, when the belt 7 moves forward, the wicket pin assembly 60 moves to a removal station 9 located at the end of the belt 7, wherein without turning the wicket pins 21, 21' with respect to the base contained in the wicket pin assembly 60, the wicket pins 21, 21' turn as a result of the movement of the belt 7 substantially to a horizontal position suitable for the removal of the stack and/or other operation (side-view in Fig. 6) In the aforementioned position the stacks hang freely and they can thus be easily removed from the ends of the belt 7.
The advantage attained by the embodiment of the invention shown in Figs. 6 and 7 is that it is not necessary to allocate space for the removal station 9 and the work conducted therein on the side of the belt 7. This enables the placement of the apparatus also in narrow spaces. It is advantageous to turn/rotate the uppermost part of the base of the wicket pin assembly 60 or another two-piece base with respect to the lower part and the belt 7 by utilizing the differential motion of the wicket pin assembly 60 moving along with the belt and a suitable guiding member with a fixed position. When exiting the removal station 60, the return movement of the wicket pin assembly 60 for stacking taking place in the stacking station 6 can also be advantageously implemented by means of a guiding member of said kind. The turning of the wicket pin assembly 60 with respect to the belt or a corresponding conveying mechanism can, of course be implemented by means of a suitable active actuator, for example by pushing with a pressurized air cylinder. The return movement can be implemented in the above-described ways by using a passive return member, such as a spring.
With reference to the embodiment shown in Figs. 6 and 7, it is also possible that in principle, the wicket pin assembly 60 operates in a similar manner as the assembly shown in Fig. 3 or 4. In other words, when the wicket pin assembly 30;40;60 enters the turning station 61, in said turning station the member 31;41 and the wicket pins 21, 21' are turned with respect to the base 32, 42 from the position A to the position B, and the removal of the stack 33 from the wicket pins 21, 21' is conducted in the same station 61 from the direction of the end of the belt 7.
It will be obvious for anyone skilled in the art that the various embodiments of the invention are not restricted solely to the examples presented above, but they may vary within the inventive aspects of the claims to be presented hereinbelow.
The invention is not restricted to be used in any particular manufacturing method of the products mentioned herein. Furthermore, the stacking of said products into a wicket pin assembly can take place by using methods and solutions of prior art suitable at a given time. It is possible to provide the product with suitable holes for the wicket pins, or the stacking of the products into wicket pins can also take place in such a manner that the pointed ends of the wicket pins themselves punch the holes into the product during wicketing.
In the embodiment according to the invention the wicket pins can be pins which are permanently fixed to the wicket pin assembly, as well as wicket wires etc. that are used together with or instead of the wicket pins, which wicket wires are detached from the wicket pin assembly with the wicket stack when said wicket stack is removed from said assembly. In wicket pins and/or wicket wires it is also possible to use various sleeves, holders, clips, etc., which are fixed in their position in the empty wicket pins and/or wicket wires before stacking, or at the same time when the stack is released from the wicket pin assembly.
In the embodiment according to the invention there may be one or several members functioning as wicket pins and their mutual placement, cross-sections and sizes can comply with the application in question.
These aforementioned features of the wicket pins and/or wicket pin assembly vary according to the product that is being manufactured at a given time. The wicket stack can, for example, function as a storage for the finished product and at the same time as a practical means for transport for example in the stacking of shopping bags of plastic, in which the stacking into the wicket pin can be conducted by utilizing the hole functioning as a handle for the shopping bag. The product stacked into the wicket stack can also contain holes/a hole for wicket pins/pin in a separate part to be torn off later during use. The product to be stacked can also be a semi-finished product, which is intended for further processing, such as for example packing bag which is filled through the bottom. Thus, the bags in a stack of bags formed into the wicket pins are filled one at a time, said bags being designed in such a manner that when they are filled up they can at the same time be automatically released from the wicket stack by tearing, or by means of other prior art methods.
After the wicket stack is formed into the wicket pin/pins in the stacking station 6, it is also possible that before the wicket stack is removed from the wicket pin/pins, the entire wicket stack is subjected to a process. Such a process can be for example perforation of the stack and/or sealing of the stack to join the stacked products together thereby facilitating the further processing of the stack. It is, of course, obvious that the aforementioned measures can be advantageously conducted in the removal station 9 before the stack is removed by utilizing the second position B of the wicket pins according to the invention. Naturally, the turning of the wicket pins from the position A used in the stacking to the position B can for the aforementioned processes also be conducted in another location than in the removal station 9 after the wicket stack is formed into the wicket pins. Even though the focus in the description hereinabove is on the advantages attained by means of the method and wicket pin assembly according to the invention in the removal of a wicket stack from the wicket pin assembly, it is obvious for anyone skilled in the art that by means of the invention it is possible to attain corresponding advantages also in connection with other processes conducted for wicket stacks before the stack is removed from the wicket pin assembly.

Claims

A method in the manipulation of stacks (33) composed of bag-like and/or sheet-like products, which stacks (33) are formed of said products in connection with their manufacturing process in a stacking station (6) into a wicket pin/wicket pins (21, 21') of a wicket pin assembly (30;40;50;60), which wicket pin assembly (30;40;50;60) is fixed to a conveying mechanism (7) by means of a base (32, 42, 52) and which stacks (33) are removed from the wicket pin/pins (21, 21') manually and/or by means of a machine when the conveying mechanism (7) has transferred the wicket pin assembly (30; 40; 50; 60) to a removal station (9), characterized in that when the wicket pin assembly (30;40;50;60) moves or is moved to the removal station (9), the position of the wicket pin/pins (21, 21') with respect to the base (32, 42, 52) and/or the position of the base (32,42,52) with respect to the conveying mechanism (7) is changed from a first position (A) used in the forming of the stack in the stacking station (6) to a second position (B) that substantially differs from said first position.
The method according to claim 1, characterized in that in said second position (B) the direction of the longitudinal axis of the wicket pin/pins (21, 21') is selected to be substantially horizontal.
The method according to any of the preceding claims, characterized in that in said second position (B) the pointed end/ends of the wicket pin/pins (21, 21') are directed substantially towards the machine tender who manually removes the stack, or towards a mechanical arrangement that conducts the removal and/or another operation.
The method according to any of the preceding claims, characterized in that in said second position (B) the stack (33) attached to the wicket pin/pins (21, 21') is hanged from the wicket pin/pins (21, 21') substantially freely and in a straight position.
The method according to any of the preceding claims, characterized in that to change the position of the wicket pin/pins (21, 21') from said first position (A) to said second position (B), the wicket pin/pins (21, 21') are transferred and/or turned with respect to the base (32;42;52) on a plane substantially perpendicular to the direction of movement of the conveying mechanism (7).
The method according to any of the preceding claims, characterized in that to change the position of the wicket pin/pins (21, 21') from said first position (A) to said second position (B), the base (32; 42;52;60) is turned with respect to the conveying mechanism (7) on a plane substantially parallel to said plate-like base.
The method according to any of the preceding claims, characterized in that the transfer from said first position (A) of the wicket pins (21, 21') to said second position (B) is synchronized with the function of the apparatus manufacturing the product and stacking it into wicket stacks, said transfer taking place either when the full wicket pin assembly (30; 40; 50; 60) is conveyed by the conveying mechanism (7) to a removal station (9) intended for the delivery/removal of the stacks (33), or when the full wicket pin assembly (30; 40; 50; 60) is located in said removal station (9).
The method according to any of the preceding claims, characterized in that the transfer from said second position (B) of the wicket pins (21, 21') back to said first position (A) is synchronized with the function of the apparatus manufacturing the product and stacking it into wicket stacks, said transfer taking place either when the empty wicket pin assembly (30; 40; 50; 60) is located in said removal station (9), or when it is transferred away from the removal station (9).
The method according to any of the preceding claims, characterized in that said second position (B) of the wicket pin/pins (21, 21') used in the delivery/removal of the stack is used in the manual and/or automatic installation of a wicket wire to be fixed to the wicket pin assembly (30; 40; 50; 60).
The method according to any of the preceding claims, characterized in that said second position (B) of the wicket pin/pins (21, 21') used in the delivery/removal of the stack is used in the manual and/or automatic installation of sleeves, clips etc. to be fixed to the wicket pin/pins or wicket wire.
The method according to any of the preceding claims, characterized in that said second position (B) of the wicket pin/pins (21, 21') used in the delivery/removal of the stack is used for carrying out an operation for the wicket stack, such as perforation or sealing of the stack (33) before the stack is removed from said wicket pin/pins.
A wicket pin assembly (30; 40; 50; 60) that comprises a base (32; 42; 52) for fixing said assembly (30; 40; 50; 60) to a conveying mechanism (7), and a wicket pin/wicket pins (21,21') fixed to said base (32; 42; 52), which wicket pin assembly (30; 40; 50; 60) is used in the manipulation of stacks (33) formed of bag-like and/or sheet-like products, in which manipulation stacks (33) are formed of said products in connection with their manufacturing process in the wicket pin/pins (21, 21') when the wicket pin assembly (30; 40; 50; 60) is in a stacking station (6), where it is transferred by means of the conveying mechanism (7), and when the wicket pin assembly (30;40;50;60) is transferred to a removal station (9) by means of the conveying mechanism (7), the stacks (33) are removed manually and/or by means of a machine from the wicket pin/pins (21, 21'), characterized in that the wicket pin assembly (30;40;50;60) comprises a member/members (31; 41; 51) for changing the position of the wicket pin/pins (21, 21') with respect to the base (32;42;52) and/or the position of the base (32;42; 52) with respect to the conveying mechanism (7) from a first position (A) used in the forming of the stack in the stacking station (6) to a second position (B) which is used in the removal station (9) and which substantially differs from said first position.
The wicket pin assembly according to claim 12, characterized in that in said second position (B) the direction of the longitudinal axis of the wicket pin/pins (21, 21') is arranged to be substantially horizontal.
The wicket pin assembly according to any of the preceding claims 12 to 13, characterized in that in said second position (B) the pointed end/ends of the wicket pin/pins (21, 21') are arranged to be directed substantially towards the machine tender who manually removes the stack (33) or towards a mechanical arrangement that conducts the removal and/or another operation.
The wicket pin assembly according to any of the preceding claims 12 to 14, characterized in that to change the position of the wicket pin/pins (21, 21') from said first position (A) to said second position (B), the wicket pin assembly (30;40;50) comprises a member/members (31; 41; 51) for transferring and/or turning the wicket pin/pins (21, 21') with respect to the base (32; 42; 52) on a plane substantially perpendicular to the direction of movement of the conveying mechanism (7).
The wicket pin assembly according to any of the preceding claims 12 to 15, characterized in that the wicket pin assembly (30; 40; 50; 60) is arranged to turn with respect to the conveying mechanism (7) on a plane substantially parallel to the plate-like base (32; 42; 52; 60).
The wicket pin assembly according to any of the preceding claims 12 to 16, characterized in that the wicket pin assembly (30; 40; 50; 60) contains members for fixing to said assembly a wicket wire that functions in a similar manner as a wicket pin.
The wicket pin assembly according to any of the preceding claims 12 to 17, characterized in that the wicket pin assembly (30; 40; 50; 60) contains members for adjusting the mutual position and angle (24) of the wicket pin/pins (21, 21').
The wicket pin assembly according to any of the preceding claims 12 to 18, characterized in that the actuator used for turning the wicket pin/pins (21, 21') from said first position (A) to said second position (B), and/or vice versa is a turning member (34) placed outside the wicket pin assembly (30).
The wicket pin assembly according to any of the preceding claims 12 to 18, characterized in that the actuator (43, 44) used for turning the wicket pin/pins (21, 21') from said first position (A) to said second position (B), and/or vice versa, is placed in the wicket pin assembly (40) itself.
The wicket pin assembly according to any of the preceding claims 12 to 18, characterized in that to turn the wicket pin/pins (21, 21') from said first position (A) to said second position (B), and/or vice versa, the wicket pin assembly (50) comprises means (53) for conducting said operation by utilizing the movement of the conveying mechanism (7) itself.
The wicket pin assembly according to any of the preceding claims 12 to 21, characterized in that to return the wicket pin/pins (21, 21') from said second position (B) to said first position (A), or vice versa, the wicket pin assembly (30; 40; 50: 60) comprises a return member, for example a return spring (36; 56).
The wicket pin assembly according to any of the preceding claims 12 to 22, characterized in that the wicket pin assembly (30; 40; 50; 60) is arranged suitable to replace a prior art wicket pin assembly (20) fixed to a conveying mechanism (7).