The present invention relates to a device for cutting off and providing a film part unit from a food-packaging film strip and a corresponding method according to the preambles of the independent claims.
It is known from practice to draw a strip of wound food-packaging film from a coil and feed it to a cutting station. In the cutting station, the end of the film strip is pushed, according to the length to be cut off, above an intended cutting point. The cutting point is there defined by a knife which provides a cut across the entire width of the film strip. The protruding portion of the film strip is subsequently cut off entirely by the knife at the cutting point. The resulting separate film part is then fed manually to a downstream working process.
In the known cutting process, every part is cut off individually from the film strip. Due to the very thin film thicknesses customary in the food-packaging sector, the film must be pushed into the cutting station in a manner requiring a complex design in order to prevent possible wrinkling when the film is moved. Nevertheless, the thin film can easily be damaged or form undesired wrinkles.
The present invention is based on the object of improving the known system and the corresponding method so that the film parts can be cut in a manner that saves time, costs and material, and is reliable and gentle on the material, while the film is least strained and remains smooth and no wrinkles or distortions arise.
The present invention satisfies the object stated with the features of the independent device claim.
By pulling the pre-cut film part unit in the conveying direction, so that a configuration of the cutting station, where a film part unit is pre-cut but still remains connected to the film strip and a previously pre-cut film part unit is cut off from the film strip in one working step, enables pulling the film strip and thus simultaneously the subsequent film in the conveying direction and thereby into the cutting station. Since the film is moved due to a tensile load in the conveying direction, it is ensured that the film remains smooth during the motion and does not deform undesirably. In addition, such pre-cutting and cutting off can be done in a time-efficient manner in one working step.
In a further embodiment, the cutting station can comprise a knife assembly defining the film part unit, where a severing knife arranged last in the conveying direction provides a cut that is transverse to the conveying direction and separates the film part unit from the film strip. The severing knife arranged last in the conveying direction ensures in a simple and reliable manner that a previously pre-cut film part unit is cut off from the film strip.
In a particular embodiment, the knife assembly can comprise at least one pre-cutting knife, in particular several pre-cutting knives spaced apart, extending from the severing knife against the conveying direction and/or at an angle to the conveying direction. The arrangement of such a pre-cutting knife makes it possible to divide the film part unit by way of the pre-cut into parts of desired dimensions, each having a cutting geometry matching the contour of the pre-cutting knife. The format of the parts is thus determined, at least to a certain degree, by the pre-cutting knife. The optional provision of several spaced pre-cutting knives makes it possible to pre-cut several parts at the same time, and also allows respectively adjoining parts to be pre-cut. The latter allows for optimal use of the area of the film strip since the entire film strip can be pre-cut into parts. This reduces film wastage.
In a further embodiment, the knife assembly can advantageously comprise a further severing knife which is arranged in the conveying direction upstream of the severing knife and provides a cut transverse to the conveying direction which completely severs at least one film-part of the film part unit from the film strip. Such an arrangement of a further severing knife makes it possible for the film part unit to have several film parts arranged consecutively in the conveying direction and thereby increases the number of film parts in the film part unit.
At least one further pre-cutting knife, in particular several further pre-cutting knives spaced apart, can extend in a particular manner from the further severing knife at an angle to and/or against the conveying direction. The arrangement of such a further pre-cutting knife makes it possible to divide the film part unit by pre-cutting it into further film parts having desired dimensions. The format of the film parts is thus determined, at least in part, by the pre-cutting knife. The optional provision of several spaced pre-cutting knives makes it possible to pre-cut several film parts at the same time, and also allows pre-cutting respectively adjoining further film parts. The latter enables optimal use of the area of the film strip, since the entire film strip can be pre-cut into film parts, each having cutting geometries adapted to the contour of the corresponding pre-cutting knives. This further reduces film wastage.
In a further embodiment, the cutting station can comprise a movable punch knife with the knife assembly. The punch knife makes it possible to quickly and reliably pre-cut the film part unit in one working step and to cut off the adjoining already pre-cut film part unit from the film strip.
Furthermore, it is proposed that the device comprises a movable transfer unit which is adapted to selectively couple to a pre-cut film part unit located in the cutting station and move it in the conveying direction, in particular, move it out of the cutting station. The pre-cut film part unit is moved reliably by the transfer unit from the cutting station in the conveying direction. The film is then conveyed under tensile load into the cutting station, which prevents wrinkling or the formation of folds in the film. The selective coupling allows controlling the point in time of coupling and decoupling. Optionally moving the film part unit out of the cutting station allows for a subsequent film part unit to be pre-cut in the cutting station and the pre-cut film part unit to be subsequently processed.
Furthermore, the transfer unit can be adapted to move a film part unit located in the cutting station with its connection point to the film strip to that location where the severing knife provides a cut transverse to the conveying direction. This ensures that the film part unit to be moved is cut off at the designated location from the film strip and also combines this function with pulling an uncut film part unit along into the cutting station and pulling a pre-cut film part unit out of the cutting station.
The transfer unit can advantageously be adapted to couple and/or decouple the film part unit only on one side of the film. Coupling and/or decoupling the film part unit on only one side of the film allows for the transfer unit needing to approach only from one direction for coupling/decoupling the film part unit, which has the effect of a simpler and more compact design of the cutting station and the transfer unit. In addition, the contact between the film part unit and the transfer unit is reduced to one side of the film part unit, which facilitates both coupling and decoupling of the film part unit.
In one particular embodiment, the transfer unit can comprise a suction device, in particular a suction plate. The suction device reduces the risk of damaging the film part unit during coupling/decoupling and during movement with the transfer unit. The optional embodiment in the form of a suction plate makes it possible to move the film part unit in a flat and/or planar position and shape.
In a further embodiment, the device can comprise a film conveyor unit which can selectively couple and hold a partial section of the film strip located in the conveying direction upstream of the cutting station and/or move it in the conveying direction. As a result, the film to be fed is supported by the film conveyor unit and the force acting upon the connection point between the pre-cut film part unit and the remaining film strip is reduced. This prevents unintentional damage or premature tearing of the film part unit at the connection point, in particular when narrow connection points are provided. Selectively coupling and holding can also reduce a potentially adverse effect of the cutting operation on the portions of the film strip that are upstream of the film conveyor unit.
The film conveyor unit and the transfer unit can advantageously be connected to one another by way of a movable, rigid structure, in particular by way of a carriage. This allows the movements of the film conveyor unit and the transfer unit to be coupled to one another, so that both units can be moved in only one motion. During movement of the two units, the rigid structure further ensures that their distance remains the same, so as not to damage or collapse the film. The optional version with a carriage allows for a simple and reliable connection of the film conveyor unit to the transfer unit.
The film conveyor unit can preferably comprise a clamping device which can selectively clamp the partial section of the film strip on both sides of the film strip. The clamping device allows for reliable and rapid coupling and holding and/or movement of the partial section of the film strip. Clamping the film strip from both sides increases the reliability of force transmission from the film conveyor unit to the film strip and reduces the risk of damaging the film at the clamping point. Furthermore, the two-sided clamping especially reduces possible adverse effects of the cutting process on portions of the film strip located upstream of the film conveyor unit.
The present invention further satisfies the object stated with the features of the independent method claim.
Pre-cutting a film part unit, while it remains connected to the film strip, and cutting off a film part unit, adjoining in the conveying direction and pre-cut in a preceding working step, from the film strip during the same working step allows for the remaining film strip to also be pulled for pre-cutting in the conveying direction in that the pre-cut film part unit is pulled in the conveying direction. Since the film is moved only due to a tensile load in the conveying direction, it is ensured that the film remains smooth during the motion and does not collapse or deform undesirably. Furthermore, more elaborate advancing of the film for pre-cutting is no longer necessary. In addition, pre-cutting and cutting off can be done in a time-efficient manner in one working step.
In a further embodiment, the film part unit can be pre-cut into at least one film part that is connected to the film strip and at least one film part that is completely cut off from the film strip. This increases the number of cut film parts in the film part unit for every working step and thus the yield of film parts per unit time.
Furthermore, the film part unit can be pre-cut with a knife assembly and the adjacent film part unit can also be cut off with this knife assembly, in particular with a punch knife, which is comprised by the knife assembly. Pre-cutting and cutting the film part unit off with the same knife assembly makes it easy to perform both cutting operations in the same working step.
The pre-cut film part unit can advantageously be moved with its connection point to the film strip to a position in the conveying direction at which it is cut off from the film strip during a pre-cutting step of a trailing film part unit. This ensures that the film part unit is cut off from the film strip at a location exactly designated for this.
In a further embodiment, the pre-cut film part unit can be selectively coupled by a transfer unit, in particular by a movable suction device, especially by a movable suction plate, and moved in the conveying direction. The film part unit is reliably moved by the transfer unit in the conveying direction. By selectively coupling the film part unit and moving in the conveying direction, the film is safely and reliably moved under tension to the pre-cutting step, which prevents wrinkling or the formation of folds in the film. The optional coupling and movement of the film by way of a movable suction device reduces the risk of damage to the film part unit during coupling and movement with the transfer unit. The optional coupling and movement of the film part unit by way of a suction plate allows for the film part unit to move in a flat and/or planar position and shape.
Furthermore, the film part unit cut off from the film strip can be moved to a downstream processing station. This enables automated, fast and direct processing of the film part unit cut off.
In a further variant of the invention, a partial section of the film strip, which in the conveying direction is upstream of the pre-cut film part unit, can be moved simultaneously with the pre-cut film part unit in the conveying direction, in particular at a uniform distance from the pre-cut film part unit. As a result, the film to be fed is supported in its motion and the force acting upon the connection point between the pre-cut film part unit and the remaining film strip is reduced. This prevents unintentional damage or premature tearing of the film part unit at the connection point, in particular when narrow connection points are provided. The optionally movement at a uniform distance further reduces unintentional damage or collapse of the film as it moves.
For better understanding of the invention, a possible embodiment of the invention shall be explained in more detail with reference to the figures described below, where
The configuration of the device according to the invention shall first be described with reference to
As can be seen in
Transfer unit 3 and film conveyor unit 4 are positioned on a carriage 6 which moves to and fro along conveying direction 5 and pull a film strip 7 intermittently in conveying direction 5 through cutting station 2. Film strip 7 extends in the region of cutting station 2 in a taut and wrinkle-free manner, approximately along conveying direction 5.
Conveying direction 5 of film 7 is drawn as a dashed arrow in all figures.
Cutting station 2 comprises a punch 8 that moves to and fro linearly and perpendicularly to conveying direction 5 between an open retracted position and a closed cutting position and that comprises a punch knife 10 with a knife assembly 11 on a side 9 facing film strip 7. Punch 8 is driven by a linear actuator 12. Cutting station 2 further comprises a punching table 13 which is arranged opposite punch 8, so that film strip 7 runs between punch 8 and punching table 13. During operation, film strip 7 is pulled intermittently by transfer unit 3 over punching table 13.
Located in the conveying direction 5 upstream of cutting station 2 is a film supply unit 14 which rotatably supports film strip 7 in the form of a peelable film coil 15. Film coil 15 can be rotatably driven and/or braked to assist the peeling operation.
Disposed in conveying direction 5 downstream of cutting station 2 is a processing station 16 which comprises hollow molds 17 for molding packaging halves for hollow figurines.
Transfer unit 3 comprises a suction plate 18. Suction plate 18 is planar on its underside 19 facing film strip 7 and on its upper side 22 and in the open position of punch 8 can retract into pre-cutting unit 2 in order to there suction a pre-cut film part unit 20b by way of negative pressure, pull it out in conveying direction 5 from cutting station 2 and finally deposit it in processing station 16.
Located on upper side 22 of suction plate 18 are negative pressure lines 23 which are connected to through holes 21. For the sake of clarity, negative pressure lines 23 are shown schematically only in
As can be seen in
As can be seen from
Transfer unit 3 and film conveyor unit 4 are connected rigidly and at a defined distance from each other by way of two longitudinal members 27 of carriage 6 which extend parallel to each other and parallel to conveying direction 5. The respective ends of longitudinal members 27 are connected to each other by two cross members 26 as well as suction plate 18. Suction plate 18 is disposed movable in the vertical direction, i.e. perpendicular to conveying direction 5, in a manner controllable by actuators, not shown, on longitudinal members 27. Carriage 6 is driven by a controllable movement unit, not shown, and moved to and fro in conveying direction 5.
Knife assembly 11 comprises a severing knife 31 which in conveying direction 5 is arranged last and provides a cut that is transverse to conveying direction 5 and that separates pre-cut film part unit 20b at connection point 30 of film strip 7 when moved out of the cutting station. Severing knife 31 is there an elongate blade which extends perpendicular to conveying direction 5 and plumb-vertical to the film strip end located in cutting station 2.
Knife assembly 11 further comprises two spaced blade-like pre-cutting knives 32 which extend from severing knife 31 against conveying direction 5 and in parallel thereto.
Knife assembly 11 also comprises a further blade-like severing knife 33 which is arranged in conveying direction 5 upstream of severing knife 31 and also provides a cut transverse to conveying direction 5 across the entire width of film strip 7. Further severing knife 33 extends parallel to severing knife 31 and perpendicular to pre-cutting knives 32. The cut provided by this further severing knife 33 completely separates parts 29 shown in
Knife assembly 11 comprises two further blade-like pre-cutting knives 35 which extend parallel to and against conveying direction 5 from further severing knife 33 and there continue pre-cutting knives 32. The common length of pre-cutting knives 32, 35 corresponds to the length of cuts 36 in
When comparing knife assembly 11 shown in
The mode of operation of device 1 according to the invention and the method according to the invention shall be explained in more detail with reference to
Clamping jaws 24, 25 are open in the state shown in
Suction plate 18 is located in conveying direction 5 at the level of hollow molds 17. Individual parts 28, 29 of a cut off film part unit 20c were just placed on hollow molds 17 of processing station 16 due to the interruption of the negative pressure at suction plate 18 and suction plate 18 has already traveled some distance vertically upwardly away from hollow molds 17. Carriage 6 with suction plate 18 and clamping jaws 24, 25 is in conveying direction 5 in its maximum position. Punch 8 is in its retracted position.
Carriage 6 subsequently drives suction plate 18 and film conveyor unit 4 against conveying direction 5 until suction plate 18 enters cutting station 2 in the corridor formed between punch 8 and punching table 13 and is stopped above pre-cut film part unit 20b. Carriage 6 with suction plate 18 and clamping jaws 24, 25 is against conveying direction 5 in its maximum position. Punch 8 continues to be in its retracted position.
Suction plate 18 now moves vertically onto pre-cut film part unit 20b until underside 19 is in planar contact with film part unit 20b. Film part unit 20b is now suctioned by negative pressure and thereby coupled on one side to suction plate 18 in a planar manner. Both parts 28 that are still connected to film strip 7 as well as parts 29 that are already cut off from film strip 7 are coupled by suction plate 18.
Shortly after suction plate 18 has coupled to film part unit 20b, oppositely disposed clamping jaws 24, 25 also move toward each other and clamp a partial section of film strip 7 that is in conveying direction 5 upstream of cutting station 2. This state is shown in
Carriage 6 subsequently moves suction plate 18 with suctioned and pre-cut film part unit 20b in conveying direction 5 to a defined position, so that connection point 30 is aligned with severing knife 31 and can be cut off by the latter in a punching operation. In the motion of the carriage, the pulling motion of suction plate 18 is transferred to the remaining film strip 7 due to connection point 30 still existing between pre-cut film part unit 20b and remaining film strip 7, and remaining film strip 7 is thereby also pulled in conveying direction 5 and a portion thereof is conveyed into cutting station 2 and comes to rest as a pre-cut film part unit 20a below punch knife 10 on punching table 13.
Film conveyor unit 4 with closed clamping jaws 24, 25 there supports film strip 7 in its motion in conveying direction 5 and thus limits the tensile force acting on connecting point 30. Pre-cut film part unit 20b unintentionally tearing off at connection point 30 during the pull is thus prevented in the case of a long and heavy film web 7 and/or a film coil 15 which is hard to unroll.
Parts 28, 29 deposited in processing station 16 in the meantime have been formed with a forming die, not shown, to hollow half shells, and are then transported via a gripper, also not shown, to a subsequent working step.
Located beneath punch 8 is now a film part unit 20a that is still uncut, as shown in
Punch 8 now moves with knife assembly 11 toward punching table 13, thereby transferring its knife assembly 11 in the form of cuts onto film strip 7. Closed clamping jaws 24, 25 avoid that the motion of punch knife 10 is adversely transferred to portions of film strip 7 that are in conveying direction 5 located upstream of clamping jaws 24, 25.
Film part unit 20b on punching table 13 is now pre-cut, as shown in
Clamping jaws 24, 25 subsequently open.
Carriage 6, with open clamping jaws 24, 25 and parts 28, 29 coupled to suction plate 18, now moves in conveying direction 5 until suction plate 18 is located above hollow molds 17.
In a subsequent working step, suction plate 18 is moved with film part unit 20c toward hollow molds 17 and the negative pressure applied to suction plate 18 is terminated. As a result, film part unit 20c, with its individual parts 28, 29 completely separated from each other, is placed accordingly onto hollow molds 17.
The subsequent working step is similar to the working step previously described for
According to further possible embodiments, the food-packaging film cut off and provided according to the present invention can be a metal film, in particular an aluminum film, a plastic film or a film as an aluminum-plastic composite.
In further possible embodiments, the food-packaging film cut off and provided according to the invention can be a film for packaging chocolate, preferably a film for packaging hollow chocolate figurines.
According to further possible embodiments, the food-packaging film cut off and provided according to the invention can have a film thickness in the range from 5 μm to 100 μm, in particular a thickness in the range from 10 μm to 50 μm, especially a thickness in the range from 15 μm to 30 μm.
Number | Date | Country | Kind |
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10 2015 220 738.2 | Oct 2015 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2016/075348 | 10/21/2016 | WO | 00 |