Method for optimizing a shear bank and corresponding shear bank

Description

[0001] The present invention relates to a method for developing a shear bench for a film having a thickness less than or equal to 10 micrometers and an associated shear bench.

[0002] Shearing benches are known comprising at least one set of a blade and a counter-blade configured to cut the film. The blade and the counter-blade are typically circular blades fixed on respective rollers. The film is capable of passing through the shearing bench between the rollers.

[0003] Several documents propose such benches, including JP 2007257695A, US 2010 / 0035088A1, JP 2004 / 276146 A, JP S52 101100 and JP S56 75338 A.

[0004] However, the performance of the shear bench is not entirely satisfactory. For example, the productivity of the shear bench as well as the quality of the film product are not optimal.

[0005] There is therefore a need for a shear bench with improved properties.

[0006] For this, the present description relates to a method for developing a film shearing bench, the method being according to claim 1.

[0007] According to particular embodiments, the development method comprises one or more of the characteristics of claims 2 to 7, taken in isolation or in all technically possible combinations.

[0008] Other characteristics and advantages of the invention will appear on reading the following description of embodiments of the invention, given by way of example only and with reference to the drawings which are: figure 1 , a schematic cross-sectional representation of an example of a shear bench, figure 2 , a schematic cross-sectional representation of part of the example shear bench according to the figure 1 , and the figure 3 , a flowchart schematically showing a process for developing the shear bench according to the figure 1 .

[0009] A shear bench 1 of a film is presented on the figure 1 . The shear bench 1 is configured to cut a film 2 (visible, in particular, on the figure 2 ).

[0010] In particular, the shear bench 1 is configured to cut a film 2 having one or more of the following properties.

[0011] The film 2 has a thickness of between 4 and 10 micrometers, preferably less than or equal to 6 micrometers.

[0012] Film 2 is, for example, made of polymer, for example of the polyamide or polyester type, such as polyethylene terephthalate, or PET.

[0013] The film 2 is in particular bi-oriented. By bi-oriented, it is understood that the film 2 has a first face and a second face opposite the first face. The first face is coated with at least one layer of ink which is in particular heat-meltable. The layer of ink on the first face is intended to be transferred during printing on a receiving medium. The receiving medium is, for example, associated with an adhesion layer and / or a layer for protecting the ink layer of the film 2. The second face of the film 2 is coated with at least one layer called the back intended to protect the film 2. The second face has in particular a sliding surface. In particular, the sliding surface allows scrolling under the print heads.

[0014] In the proposed example, the film 2 has a first PET face coated with a layer of ink composed of waxes, resins and at least one pigment, such as carbon black. The second face is coated with a layer composed of silicone derivatives.

[0015] The shearing bench 1 is in particular configured to cut the film 2 supplied in the form of a ribbon intended to slide in a direction of travel D1 through the shearing bench 1. In particular, the shearing bench 1 is configured to cut the film 2 having a length in the direction of travel D1 of between 300 meters and 1200 meters.

[0016] For the shear bench 1, a second direction D2 is defined which is substantially orthogonal to the running direction D1. In particular, the second direction is horizontal. In addition, a third direction D3 is defined which is orthogonal to the running direction D1 and orthogonal to the second direction D2.

[0017] The shear bench 1 comprises a plurality of elements. Each element is characterized by a plurality of parameters, all of the parameters forming the parameters of the shear bench 1.

[0018] In particular, the shearing bench 1 comprises at least one set of blades 10, a system 12 for unwinding the film 2 and a system 14 for applying the set of blades 10.

[0019] In the example of the figure 1 , nine sets of blades 10 are shown.

[0020] Each set of blades 10 comprises a blade 20 and a counter-blade 21 cooperating with the blade 20 (visible in particular on the figure 2 ).

[0021] Each blade 20 comprises a knife 22 comprising a cutting edge and a suspension 23 configured to apply the knife 22 against the counter-blade 21.

[0022] Each blade 20 is a circular blade. By “circular blade” is meant a blade in the shape of a circle in a plane perpendicular to the third direction D3. In particular, the cutting edge has a circular shape.

[0023] Each counter blade 21 is, for example, a ring comprising a cavity 24 configured to receive a portion of the blade 20 comprising the cutting edge. The counter blade 21 is a circular blade.

[0024] Each set of blades 10 comprises a plurality of technical parameters. The parameters are technical properties of the blade 20 and the counterblade 21.

[0025] For each set of 10 blades, the parameters are as follows: the thickness of the blade 20, the material of the blade 20, the diameter of the blade 20, the geometry of the blade 20, the thickness of the counterblade 21, the material of the counterblade 21, the diameter of the counterblade 21 and the geometry of the counterblade 21.

[0026] The thickness of the blade 20 is defined according to the third direction D3. The thickness corresponds in particular to that of the cutting edge of the blade 20 which is intended to be in contact with the film 2. For example, the thickness of the blade 20 is equal to 0.5 millimeters (mm).

[0027] The thickness of the counterblade 21 is defined along the third direction D3. The thickness of the counterblade 21 corresponds to the maximum thickness along the third direction D3.

[0028] The diameter of the blade 20 or the counter-blade 21 is defined according to the direction of travel D1 or according to the second direction D2.

[0029] The material of the blade 20 and the counterblade 21 comprises, for example, ceramic or steel. The knife 22 of the blade 20 comprises, for example, essentially tungsten carbide which is preferably coated with ceramic.

[0030] The geometry of the blade 20 is notably defined by a shear angle formed between the blade 20 and the film 2. In the example shown, the shear angle is substantially equal to 90 degrees.

[0031] The geometry of the blade 20 further includes the shape of the knife 22. In the example shown, the knife 22 includes a rectangular base ending in a point to form the cutting edge.

[0032] Alternatively or additionally, the lateral displacement of the blade 20 relative to the counter-blade 21 is also taken into account.

[0033] The applicant has, by means of tests and surprisingly, found that a knife 22 comprising a parabolic shape is particularly advantageous for cutting the film 2. In particular, the thickness of the cutting edge of a knife of parabolic shape is smaller than the thickness of the cutting edge of a knife of linear shape.

[0034] Other geometries of the blade 20 can be considered.

[0035] The film 2 unwinding system 12 comprises at least a first roller 25 having a first axis of rotation and a second roller 26 having a second axis of rotation substantially parallel to the first axis of rotation. The unwinding system 12 further comprises carrier supports 28 capable of carrying the first and second rollers 25, 26. In particular, the first and second rollers 25, 26 are movable in rotation about the first and second axis respectively relative to the carrier supports 28.

[0036] The first roller 25 is provided with blades 20 and the second roller 26 is provided with counter-blades 21.

[0037] The scrolling system 12 further comprises drive motors 30 for the first and second rollers 25, 26.

[0038] Regarding the 12-film 2 scrolling system, the parameters are as follows: the film 2 running speed, and the film 2 tension.

[0039] The running speed of film 2 is defined relative to shear bench 1. The running speed is, for example, equal to 400 meters per minute.

[0040] The tension of film 2 corresponds to the physical force applied to film 2 in the direction of movement D1 or in the third direction D3. For example, the force is approximately equal to 10 Newtons.

[0041] The application system 14 is configured to apply the blade 20 and the counter-blade 21 against each other to shear the film 2.

[0042] The application system 14 comprises at least one device 40 for moving the first roller 25 and / or the second roller 26 and at least one controller 42.

[0043] The movement device 40 comprises, for example, a vertical rail on which one end of the first and / or second roller 25, 26 is mounted to move in translation. The movement device 40 is configured to move the first roller 25 and / or the second roller 26 in the second direction D2. In addition, the movement device 40 is configured to move the first roller 25 and / or the second roller 26 in the third direction D3.

[0044] Controller 42 is, for example, a computer.

[0045] The controller 42 is notably configured to send commands to the movement device 40 and to control the operation of the movement device 40.

[0046] The application system 14 has, for example, the following technical parameters: the rotational speed of each blade 20, the rotational speed of each counterblade 21, the pressure applied to each blade 20, the pressure applied to each counterblade 21, ratio of the rotational speed of the blade 20 to the rotational speed of the counterblade 21, and the overlap of the blade 20 with the counterblade 21.

[0047] Preferably, the rotational speed of each blade 20 is the rotational speed of the first roller 25 and the rotational speed of each counter-blade 21 is the rotational speed of the second roller 26.

[0048] The pressure applied to each blade 20 or to each counter-blade 21 is a force exerted on each blade 20 or counter-blade 21.

[0049] The applied pressure depends on a plurality of factors. For example, the applied pressure depends on the rotation speed of the blade 20 or counter-blade 21 and a thickness of the film 2. The applied pressure is, for example, equal to 50 Newtons.

[0050] The ratio of the rotation speed of the blade 20 to the rotation speed of the counterblade 21 is a technical parameter having an impact on blade wear. In particular, when the speeds are very different, the blades 20, 21 are more worn. For example, the ratio is equal to 5%.

[0051] The overlap of the blade 20 with the counter-blade 21 is observed in a plane perpendicular to the direction of travel D1. As visible, for example, on the figure 2 , a part of blade 20 is contained in cavity 24, i.e. blade 20 overlaps with counter blade 21.

[0052] Only the parameters used for a shear bench 1 tuning process have been described. Other parameters may be considered.

[0053] To fine-tune the above parameters of such a shear bench 1, the fine-tuning method 100 is implemented, an example of implementation being described in the following.

[0054] The method comprises at least one selection step 110, one measurement step 120 and one comparison step 130.

[0055] During the selection step 110, the parameters of the shear bench 1 are chosen. In particular, the parameters of the blade assemblies 10, of the film 2 unwinding system 12 and of the application system 14 are chosen.

[0056] In a first example, the parameters are chosen randomly, from a range of predefined values ​​for each parameter.

[0057] In another example, each parameter is chosen according to a commercially available shear bench.

[0058] In another example, a table of compatible parameters is previously defined. One parameter is chosen, for example randomly, and the other parameters are defined using the table.

[0059] Preferably, the controller 42 determines a combination of parameters. In particular, the combination of parameters comprises a large number of variants, which implies an automated definition of parameters by the controller 42.

[0060] During the measurement step 120, the performance of the shear bench 1 having the chosen parameters is measured.

[0061] This performance is evaluated by assessing a plurality of physical quantities associated with shear bench 1.

[0062] The set of physical quantities forms a measured value. The measured value corresponds to an evaluation criterion. The evaluation criterion corresponds to one or more sub-criteria. The sub-criteria are, for example, the following: cadence, speed, fouling, film quality 2, and blade life.

[0063] The throughput sub-criterion is measured by determining the length of film 2 passed through shear bench 1 during a predefined period of time. For example, the length of film 2 passed during 24 hours is measured. For example, when the shear bench is often stopped, for example for maintenance reasons, the length of film 2 passed through shear bench 1 is low, other sub-criteria being kept constant.

[0064] The speed sub-criterion is evaluated by measuring the rotation speed of the rollers 25, 26, for example by a tachometer.

[0065] The fouling sub-criterion is measured, for example, by at least one image sensor, such as a camera, in particular capable of determining residues on the blade 20 and / or the counter-blade 21.

[0066] The sub-criterion of the quality of the film 2 is evaluated by taking into account one or more factors among the homogeneity or not of the thickness of the film 2, the homogeneity or not of the width of the film 2, the straightness or not of a cutting edge of the film 2 and the fraying or not of the cutting edge. For example, the sub-criterion of the quality of the film 2 is evaluated by a user of the shear bench 1 or by a control machine equipped with optical control sensors.

[0067] The sub-criterion of the service life of the blades is evaluated by measuring the correct operating time of the blade 20 and the counter-blade 21. By "correct operation", it is understood that the blade assembly 10 cuts the film 2 according to predefined requirements concerning in particular the cutting edge. In particular, the applicant has found that the service life of the blades 20, 21 is reduced when the blades 20, 21 heat up, for example due to a high rotation speed of the blades 20, 21.

[0068] From the measured sub-criteria, the measured value for shear bench 1 corresponding to an evaluation criterion of shear bench 1 is determined.

[0069] In particular, the sub-criteria are combined by applying a weighting during measurement step 120.

[0070] The weighting includes, for example, at least one multidimensional function. For example, for each sub-criterion considered, the function includes a functional variable. For example, if two sub-criteria are considered, the function includes two functional variables.

[0071] Preferably, the weighting is such that only the speed and fouling sub-criteria are used. In this example, the measured speed is a first functional variable and the measured fouling is the second functional variable. The result of the function is the measured value. At the end of the measurement step 120, the measured value is obtained.

[0072] In comparison step 130, the measured value is compared with a desired value.

[0073] The desired value is preferably defined prior to an implementation of the development method. The desired value is, for example, defined based on requirements for shear bench 1.

[0074] If the measured value is strictly lower than the desired value, the steps of choice 110, measurement 120 and comparison 130 are repeated, as visible on the figure 3 symbolizing an iteration by the arrow 150. During an iteration, at least one of the chosen parameters is modified among the parameters of each set of blades 10, of the scrolling system 12 and of the application system 14.

[0075] Preferably, the only parameters that vary from one iteration to another are: the thickness of each blade 20, the material of each blade 20, the thickness of each counter-blade 21, the material of each counter-blade 21, the rotational speed of each blade 20, the rotational speed of each counter-blade 21, and the running speed of the film 2.

[0076] The choice of these parameters as the only parameters is unexpected and results from the work carried out by the applicant. In particular, the choice makes it possible to reduce the number of parameters to be modified, while at the same time allowing an improvement in the performance of shear bench 1.

[0077] According to another unclaimed embodiment, the only parameters that vary from one iteration to another iteration are the following: the rotation speed of each blade 20, the rotation speed of each counter-blade 21, the running speed of the film 2, and the shear angle formed between the blade 20 and the film 2.

[0078] By definition, the shear angle between blade 20 and film 2 is the angle between the normal to film 2 and the position of blade 20.

[0079] The preceding parameters are called main parameters in the following.

[0080] Changing the main parameters allows the tuning process to be further simplified 100.

[0081] It was found that the main parameters are the parameters having the highest impact on the performance of the shear bench 1 among the parameters of the blade assemblies 10, the scroll system 12 and the application system 14.

[0082] In particular, it has been found that the main parameters involve a variation of other parameters among the set of parameters of the blade assemblies 10, the scrolling system 12 and the application system 14. Therefore, a variation of the main parameters makes it possible, at the same time, to vary other parameters.

[0083] For example, the speed of movement of the film 2 is linked to the pressure applied to each blade 20 and to the pressure applied to each counter-blade 21, in particular because the set of blades 10 cuts, over a period of time considered, a greater length of the film 2 if the speed of movement of the film 2 is increased.

[0084] Steps 110, 120 and 130 are preferably repeated until the measured value is greater than or equal to the desired value.

[0085] If the measured value is greater than or equal to the desired value, a selection step 140 is implemented.

[0086] During the selection step 140, the parameters chosen during the last previous iteration I of the method 100 are selected for the operation of the shear bench 1.

[0087] The method of developing 100 the shear bench 1 has a plurality of advantages.

[0088] Reducing the parameters, for example on the main parameters, allows to achieve satisfactory results regarding the operation of the shear bench 1, and to limit the complexity of development at the same time.

[0089] Such a reduction of parameters is specific to the cases of inked ribbons.

[0090] In fact, only parameters managing the contact of the blades 20 and counter-blades 21 are involved.

[0091] Furthermore, due to the nature of the film 2 to be cut, the sub-criteria are preferably specific since only speed and fouling are used.

[0092] In particular, the geometry of the films 2 obtained is not taken into account.

[0093] The development method 100 thus makes it possible to obtain the desired performance of the shear bench 1. Thanks to the development method 100, a shear bench 1 having improved properties is thus obtained.

[0094] In particular, in manual use, the shear bench 1 has a maximum speed of 500 meters per minute (the speed is limited), a life of the blades 20 / counter-blades 21 of between 5 and 8 million linear meters and makes it possible to obtain 4000 linear meters per hour.

[0095] In the case of automated use, the values ​​are even higher. The shear bench 1 has a maximum speed of between 800 meters per minute and 900 meters per minute, a service life of the blades 20 / counter-blades 21 greater than or equal to 10 million linear meters and allows 10,000 linear meters per hour to be obtained.

[0096] In both cases, there is no fouling. Only simple traces are observed, which do not impact the shearing, which can continue.

[0097] In addition, the overall efficiency rate, also called TRS, defined as the ratio between the number of meters produced with shear bench 1 and the number of meters that it would be theoretically possible to produce with shear bench 1 is equal to 85%.

[0098] A combination of the preceding embodiments when technically possible is also conceivable and includes the features of claim 1.

Claims

1. An optimization method for optimizing a shearing bench (1) for shearing a film (2) having a thickness less than or equal to 10 microns, the shearing bench (1) comprising a plurality of elements, each element being characterized by a plurality of parameters, the set of parameters constituting the parameters of the shearing bench (1), the plurality of elements comprising at least one blade assembly (10) comprising of a blade (20) and a counter-blade (21) that collaborates with the blade (20), a film progression system (12) for progressing the film (2) and a blade / counter-blade urging system (14) for urging the blade (20) and the counter-blade (21) against one another in order to shear the film (2), the method including: - a parameter selection step for selecting the parameters of the shearing bench (1); - a performance measurement step for measuring the performance of the shearing bench (1) presenting the selected parameters, so as to obtain a measured value for the shearing bench (1) that corresponds to an evaluation criterion for evaluating the shearing bench (1); and - a value comparison step for comparing the measured value with a desired value; when the measured value is strictly lower than the desired value, the steps of parameter selection, performance measurement, and value comparison are re-iterated by modifying parameters called main parameters among the selected parameters until such time as the measured value is greater than or equal to the desired value, the method then including a parameter selection step during the last iteration for the operating of the shearing bench (1), wherein said main parameters are the following: - the thickness of the blade (20), - the material of the blade (20), - the thickness of the counter-blade (21), - the material of the counter-blade (21), - the speed of rotation of each blade (20), - the speed of rotation of each counter-blade (21), and - the speed of progression of the film (2), the other selected parameters not being modified.

2. Method according to claim 1, wherein the film (2) has a first surface and a second surface opposite the first surface, the first surface is coated with at least one layer of ink.

3. Method according to claim 1 or 2, in which the evaluation criterion is a weighting of the following sub-criteria: - the throughput rate, - the speed, - fouling, - the quality of the film (2), and - the useful life of the blades (20, 21).

4. Method according to claim 3, wherein the weighting is such that only the sub-criteria of speed and fouling are used.

5. Method according to claims 3 or 4, wherein the film progression system (12) for progressing the film (2) comprises a first roller (25) and a second roller (26), wherein the speed sub-criterion is determined by measuring the rotational speed of the first and second rollers (25, 26), and wherein the fouling sub-criterion is measured by means of at least an image sensor.

6. Method according to any one of claims 1 to 5, wherein the film (2) is made of polyethylene terephthalate (PET).

7. Method according to any one of claims 1 to 6, wherein each blade (20) comprises of a cutter (22) comprising a cutting edge, the cutter (22) having a parabolic shape.