Knife length adjustment device and film cutting system

Abstract

A knife length adjusting device, characterized in that it comprises: a knife holder (1) comprising a knife holder main body (10) and a knife fastening assembly (11) arranged axially displaceably on the knife holder main body (10); and a blade adjustment module (2) comprising a push rod (20), a push rod drive (21), and a drive device (22); wherein the push rod (20) abuts against the blade mounting assembly (11), the push rod drive (21) is driveably connected to the push rod (20), and the drive device (22) is driveably connected to the push rod drive (21).

Description

Technical FieldThe present application relates to the field of film cutting technology, in particular to a knife length adjusting device and a film cutting installation.Prior ArtFilm cutting systems (also called film cutting machines) are mainly used for cutting protective films for the front and back of smartphones and tablets. In contrast to the traditional punching process, which requires custom-made punching tools for each design and is time and labor intensive in small series with variant-rich special preparations, the foil cutting plant solves these application problems and is the optimal solution for small series with variant-rich special preparations. This system uses an electric motor driven cutting blade that accurately cuts protective films for electronic devices and cuts mobile phone films into prescribed shapes and widths.Prior to the cutting operation, the knife must be inserted manually into a knife holder of the system. Usually, the blade extension length is set manually based on experience. However, this adjustment method leads to uncontrollable variations in the length and thus to uneven cutting depths.Alternatively, gauges allow adjustment of the blade extension length, but this method significantly increases the failure rate of the blade tips. In addition, manufacturing tolerances of the blade holder have a direct effect on the blade extension length.Furthermore, product-specific dimensional deviations in the event of a blade change inevitably lead to inconsistencies in the cutting depth.Content of the Present ApplicationThe present application relates to a knife length adjusting device and a foil cutting apparatus for solving the above technical problems.A knife length adjusting device comprising:a blade holder comprising a blade holder main body and a blade mounting assembly axially slidably disposed on the blade holder main body; anda knife adjustment module comprising a push rod, a push rod drive, and a drive device; wherein the push rod abuts the knife mounting assembly, the push rod drive is drivingly connected to the push rod, and the drive device is drivingly connected to the push rod drive.In some embodiments, the push rod drive includes a drive nut and a lead screw; wherein the lead screw is drivingly connected to an output shaft of the drive device, the lead screw is threaded to the drive nut, and the drive nut is fixedly connected to the push rod.In some embodiments, the drive nut includes a nut body and a push rod connection part; the nut body is provided with a threaded hole, and the push rod connection part is disposed along the outer periphery of the threaded hole and extends toward the blade holder; the push rod is connected to the push rod connection part and is coaxial with the threaded hole.In some embodiments, a guide bore is disposed on the outer periphery of the threaded bore, and the push rod drive further includes a guide rod disposed on the guide bore.In some embodiments, the knife adjustment module further comprises a mounting frame; wherein the drive device is disposed on the mounting frame and the guide rod is disposed on the mounting frame.In some embodiments, the knife adjustment module includes a first engine block disposed on a side of the drive nut that is remote from the knife mount.In some embodiments, the knife adjustment module further comprises a mounting frame; wherein the drive device is disposed on the mounting frame and the first engine block is disposed on the mounting frame.In some embodiments, the knife adjustment module further includes a second engine block disposed on a side of the drive nut toward the knife mount.In some embodiments, the knife length adjustment device further comprises a knife changer; wherein the knife changer comprises a knife changer push rod disposed opposite the knife mounting assembly and a knife changer rod drive drivingly connected to the knife changer push rod.In some embodiments, the blade change push rod is arranged with a through bore through which the blade change push rod is plugged onto the push rod.In some embodiments, the blade holder main body is disposed with a package mounting bore and a blade exit bore connected to the package mounting bore; wherein the blade mounting assembly is slidably disposed in the package mounting bore; the tool mounting component comprises: a first blade mounting bearing disposed at a first end of the package mounting bore, a second blade mounting bearing disposed at a second end of the package mounting bore, and a return spring abutting at both ends against the first blade mounting bearing and the second blade mounting bearing; the push rod abuts against the first blade mounting bearing.In some embodiments, the first blade mounting bearing is provided with a magnetic attraction structure.A foil cutting system which comprises the knife length adjusting device upwards.The technical solution provided in the embodiments of the present application has the following advantages over the related art.The knife length adjusting device presented in the present application first adjusts the knife to the zero point position via a knife adjusting module and then adjusts the extension length of the knife on the basis of the preset length of the knife corresponding to the standard film. Then, the standard sheet is cut, and the extension length is adjusted a plurality of times according to the preset setting positions to obtain an optimum cutting result. The optimal cut position is stored and updated into all standard film information to provide a basis of extension length information for subsequent cuts of the standard film. This prevents machining errors due to manual adjustments and damage to the cutting tip due to adjustments of the device.Brief Description of the DrawingsThe accompanying drawings are incorporated in and form a part of this specification. They show embodiments of the present application and together with the description serve to explain the principle of the present application.In order to more clearly explain the embodiment of the present application or the prior art technical solution, the drawings necessary for the description of the embodiment or the prior art will be briefly presented below. It is obvious that for a person skilled in the art without any curative work, further drawings can be created on the basis of these drawings.One or more embodiments will be explained by way of example with reference to the corresponding figures in the accompanying drawings. These exemplary explanations do not represent a limitation of the embodiments. Elements having like reference numerals in the accompanying drawings designate similar elements unless expressly stated otherwise. The figures in the attached drawings do not represent any dimensional requirements. FIG. 1 is a structural schematic diagram of an adjustment device according to some embodiments of the present application. FIG. 2 is an exploded structural view of an adjustment device according to some embodiments of the present application. FIG. 3 is a schematic view of the cross section taken along line A-A in FIG. 1. FIG. 4 is a structural schematic illustration of a knife adjustment module in accordance with some embodiments of the present application. FIG. 5 is a structural schematic illustration of a drive nut in accordance with some embodiments of the present application. FIG. 6 is a structural schematic illustration of a mounting frame in accordance with some embodiments of the present application. FIG. 7 is a structural schematic illustration of a blade changer according to some embodiments of the present application. FIG. 8 is a structural schematic illustration of a blade holder in accordance with some embodiments of the present application.Reference Number:Knife holder 1, knife holder main body 10, knife mounting assembly 11, assembly mounting bore 101, knife output bore 102, first knife mounting bearing 111, second knife mounting bearing 112, return spring 113, magnetic attraction structure 1111; knife adjustment module 2, push rod 20, push rod drive 21, drive device 22, guide rod 23, mounting frame 24, first motor block 25, second motor block 26, knife change device 27, housing 29, drive nut 211, threaded spindle 212, nut body 2110, threaded bore 2111, push rod connection part 2112, guide bore 2113, knife change push rod 271, through bore 2710, first housing 291, second housing 292.DETAILED DESCRIPTION OF THE EMBODIMENTSIn order to better clarify the objects, technical solutions, and advantages of the present application, the technical solutions of the present application will be clearly and fully described with reference to the accompanying drawings. It is understood that the described embodiments are only some examples of the present application and do not include all possible embodiments. All other embodiments that a person skilled in the art can achieve without any creative work based on the present application also fall within the scope of protection of the present application.The following disclosure includes many different embodiments or examples for implementing the various structures of the present application. To simplify the disclosure of the present application, specific examples of components and arrangements are described below. These are, of course, only illustrative and are not intended to limit the present application. Moreover, in various examples, reference numerals and / or letters may be used repeatedly. These repetitions are for convenience and clarity and do not provide any reference to the relationships between the various embodiments and / or arrangements.For convenience in description, spatial relationship terms may be used herein to describe the relative position or movement of one element or feature with respect to another element or feature as depicted in the figures. These terms for relative relationships are, for example, "inside", "outside", "inside", "outside", "below", "above", "above", "front", "rear", etc. These terms for spatial relationships are intended to encompass positions of the device during use or operation other than the positions depicted in the figures. For example, if the position or location of a device in the image is reversed or its state of motion changes, these directional indications will also change accordingly, e.g., an element described as "below another element or feature" or "below another element or feature" will then be oriented as "above another element or feature" or "above another element or feature.". Thus, the example term "below... " may include both the positions "up" and "down". The device may additionally be aligned (rotated 90 degrees or in another direction) and the descriptions of relative spatial relationships used in the text are interpreted accordingly.The method for adjusting the blade length described in the present application can be applied to foil trimming in a foil cutting facility to adjust the extension length of the blade so that the cutting depth of the foil is uniform. Specifically, the method includes:S1: setting a knife to a zero point position based on preset information on the zero point position of the knife.Specifically, the information on the zero point position of the knife serves as a basis for setting the extension length of the knife. Each knife is adjusted in length based on this zero point position, thereby ensuring a smooth adjustment of the length and avoiding manual errors or errors by devices.S2: acquiring standard sheet information of a standard sheet; wherein the standard sheet information includes information on a preset length of the knife.In these embodiments, the standard sheet information is a kind of information about a sheet type to be cut. The standard sheet information may include information on the material and thickness of the sheet and the preset length of the knife, wherein the information on the preset length of the knife is indispensable to provide a preset extension length of the knife for each type of sheet. The preset extension length of the blade is approximately equal to the actual extension length required, but is not necessarily the optimum length, since the preset extension length does not meet the actual cutting requirements due to various tool and blade errors in actual cutting.S 3: Adjusting the extension length of the knife based on the preset length information of the knife.Specifically, the extension length of the knife is adjusted based on the preset length information of the knife based on the zero point position of the knife and the preset length information of the knife.S4: cutting the standard sheet; adjusting the extension length of the knife a plurality of times based on the preset set positions to determine an optimum cutting position; and recording optimum cutting position information for the standard sheet.In these embodiments, the preset setting positions may be set according to the cutting accuracy. The higher the cutting accuracy, the smaller the adjustment length for a single adjustment position and the more adjustment positions may be required. Adjustment is made by the preset setting positions based on the preset extension length of the knife during cutting. The optimum cutting position can be determined by the comparison. The cutting position information of the optimal cutting position corresponding to the standard sheet is recorded and adopted as the optimal standard sheet information.S5: Update the optimum cutting position information in the standard sheet information.In these embodiments, the blade extension length information is updated into the standard sheet information, so that upon subsequent cutting, the blade extension length can be adjusted for sheets of the same type based on the preset blade length and the optimal cutting position information, thereby achieving uniform cutting accuracy for this sheet type.In another embodiment, the method further comprises:S6: Repeating steps S1 to S5 after replacing a worn blade.Specifically, this means that the cutting accuracy decreases after longer cutting and wear of the blade. After the blade is exchanged, by repeating the above steps, the effects of the machining errors of the blade on the cutting accuracy of the film can be eliminated.In these embodiments, step S1 comprises:S10: Determining a knife reference point by a hard boundary.S11: Set the knife to the zero point position based on the knife reference point and the zero point position of the knife.In order to ensure the accuracy of the zero point position of the knife, it is necessary to set the zero point position by a hard limit. Specifically, when setting the knife to the zero point position, the knife is first set to the knife reference point and then the knife is extended or retracted by a preset length so that the knife reaches the same zero point position each time and errors in the zero point position are avoided. For example, in one embodiment, the knife is first constrained by retraction on the hard boundary so that it returns to the knife reference point. Starting from this reference point, it is extended by a preset length, for example 0.5 mm, so that the knife returns to the zero point position. At each setting of the knife, the zero point position is first restored to ensure accuracy in subsequent settings.In the present embodiments, the preset setting position described in step S 4 includes a shortening stage and an extension stage that are set based on the preset length of the knife.Moreover, the shortening stage comprises at least two stages and the extension stage comprises at least two stages. Several steps ensure the accuracy of the adjustment. The more steps are present, the shorter the adjustment length of the individual steps and the higher the accuracy.Based on the above-described embodiments, the present application further provides an adjusting device comprising a knife holder 1 and a knife adjusting module 2, as shown in Figs. 1 to 3.The blade holder 1 includes a blade holder main body 10 and a blade mounting assembly 11 axially slidably disposed on the blade holder main body 10. The displaceably arranged knife fastening assembly 11 offers the necessary preconditions for setting the extension length of the knife.The knife adjustment module 2 includes: a push rod 20, a push rod drive 21, and a drive device 22; wherein the push rod 20 abuts the knife mounting assembly 11, the push rod drive 21 is drivingly connected to the push rod 20, and the drive device 22 is drivingly connected to the push rod drive 21.In a further embodiment, the blade adjustment module 2 can additionally be provided with a housing 29 serving as a structural base for the fitting and mounting of the individual components in order to realize modular production and modular mounting of the product. Specifically, the housing 29 may include a first housing 291 and a second housing 292 that structurally support and protect the driving device 22 and the driving part.In these embodiments, in conjunction with the illustration in FIG. 4, the push rod drive 21 comprises a drive nut 211 and a threaded spindle 212; the threaded spindle 212 is in drive connection with the output shaft of the drive device 22, the threaded spindle 212 is screwed to the drive nut 211, and the drive nut 211 is firmly connected to the push rod 20. The threaded spindle transmission is a precision gear which forms an accurate basis for the adjustment of the extension length of the knife of the foil cutting installation. In an embodiment, the push rod 20 and the drive nut 211 may be made as an integral structure to reduce assembly errors between the two.In another embodiment, the push rod drive 21 may be realized by a ball screw or a rack.As an optional embodiment, the driving device 22 may be a motor or a reduction gear motor that can output driving force precisely based on a driving signal.In these embodiments, as illustrated in FIG. 5, the drive nut 211 includes a nut body 2110 and a push rod connecting part 2112; the nut body 2110 is provided with a threaded hole 2111, the push rod connecting part 2112 is disposed along the outer periphery of the threaded hole 2111 and extends toward the blade holder 1; the push rod 20 is connected to the push rod connecting part 2112 and is coaxial with the threaded hole 2111. By disposing the push rod connecting part 2112 along the outer periphery of the threaded hole 2111, interference with transmission of power to the screw shaft 212 can be prevented. In addition, the coaxial arrangement of the push rod 20 and the threaded bore 2111 makes it possible to avoid impairment by the lever arm which is produced in the force transmission process and which would lead to minor accuracy errors.Moreover, a guide hole 2113 is formed on the outer periphery of the threaded hole 2111, and the push rod driver 21 further includes a guide rod 23 formed on the guide hole 2113, which ensures the power transmission accuracy of the drive nut 211 and prevents slight deviations during the movement of the drive nut 211, which would result in a decrease in the tool adjustment accuracy.Of course, as a further alternative embodiment, the guiding of the drive nut 211 can be realized by a guide groove, wherein correspondingly a structure corresponding to the shape of the guide groove is arranged on the drive nut 211.In a further embodiment, the knife adjustment module 2 in conjunction with FIGS. 3 and 6 comprises a mounting frame 24; wherein the drive device 22 is arranged on the mounting frame 24 and the guide rod 23 is arranged on the mounting frame 24.Moreover, the blade adjustment module 2 includes a first motor block 25 disposed on a side of the drive nut 211 that is remote from the blade holder 1. Specifically, the first engine block 25 may be disposed on the mounting frame 24 (as an integral part of the mounting frame 24), of course, it may otherwise be disposed on the relatively fixed housing 29. The first motor block 25 serves as a hard limit and provides the knife adjustment module 2 with an adjustment reference point. When the drive device 22 retracts the knife, the drive device 22 (i.e., the engine) is blocked and stops by the first motor block 25, so that the drive nut 211 is blocked in this position. In each adjustment operation, the drive nut 211 can be locked in this position, ensuring that each knife adjustment is made based on this reference point, which in turn ensures the accuracy of each adjustment.In another embodiment, the knife adjustment module 2 further comprises a second motor block 26 arranged on a side of the drive nut 211 towards the knife holder 1. The second motor block 26 prevents the drive nut 211 from moving too far under the drive of the drive device 22, which would result in the lead screw 212 striking against the push rod connection part 2112, which would result in damage to the lead screw 212 or reduced accuracy.In this embodiment, as shown in FIG. 7, the adjustment device further comprises a knife changer 27; wherein the knife changer 27 comprises a knife changer push rod 271 disposed opposite the knife mounting assembly 11 and a knife changer rod drive 272 drivingly connected to the knife changer push rod 271.In particular, the blade change bar drive 272 may be a manual drive mechanism, which in conjunction with FIGS. 1, 3 and 7 is a manual switching device disposed outside the housing and connected to the blade change push bar 271 in the housing. By switching this manual switching device, the blade change push rod 271 can push out the blade mounting assembly 11 and thus the blade 3.Moreover, the blade change push rod 271 is provided with a through hole 2710 through which the blade change push rod 271 is fitted onto the push rod 20. In this way, the push rod 20 can be used as a guide member, thereby ensuring the stability of movement of the blade change push rod 271.In these embodiments, referring to FIGS. 3 and 8, the blade holder main body 10 is provided with a unit mounting bore 101 and a blade output bore 102 connected to the unit mounting bore 101; the blade mounting unit 11 is slidably disposed in the unit mounting bore 101. The tool mounting component 11 includes: a first blade mounting bearing 111 disposed at a first end of the assembly mounting bore 101; a second blade mounting bearing 112 disposed at a second end of the assembly mounting bore 101; and a return spring 113 abutting at both ends on the first blade mounting bearing 111 and the second blade mounting bearing 112. The push rod 20 abuts against the first knife mounting bearing 111. The return springs 113 always exert an elastic force on the first knife mounting bearing 111, so that the first knife mounting bearing 111 always abuts against the push rod 20 and thus an adjustment clearance is prevented from occurring.Moreover, the first blade mounting bearing 111 is provided with a magnetic attraction structure 1111 to enable quick mounting of the blade while simplifying the structure of the blade mounting assembly 11.Based on the above-described adjusting device, the blade adjustment is performed as follows.T1: The drive device 22 (e.g., an engine) rotates counterclockwise, retracting the knife and moving the drive nut 211 back until it abuts the first motor block 25. When the locking force has reached a certain value, this position is defined as a reference point. After confirming the reference point, the driving device 22 rotates clockwise based on the preset zero point position of the knife (e.g., 0.5 mm above the reference point) to move the knife by 0.5 mm to the zero point position.T2: By manually inputting or scanning the code, the standard sheet information containing the preset length of the knife is retrieved to determine the knife length required for cutting the standard sheet.T3: Based on the preset length information of the knife, the driving device 22 rotates clockwise, drives the driving nut 211 axially away from the driving device 22, and simultaneously moves the push rod 20 pressing against the knife mounting assembly 11 and the knife 3 mounted thereon by the same distance, i.e. the knife length required for cutting the standard film.T4: Cutting the standard sheet: Based on the preset setting positions, e.g., five shortening stages and five extension stages, the extension length of the knife is adjusted one after another, one stage each being set and a cut being performed. By comparison, the optimum cutting position is obtained and the optimum cutting position information for the current standard sheet is recorded.T5: The optimum cutting position information is updated in the standard sheet information.T 6: At the time of tool change, the blade change rod drive 272 (i.e., the manual switching device) is manually operated so that the blade change push rod 271 descends and is pressed downward together with the first blade mounting bearing 111. If the knife is at a longer distance from the knife holder 1, the knife to be exchanged is pulled out manually or with a tool and at the same time a new knife 3 is inserted. Subsequently, the above steps T1 to T5 are repeated to readjust the length of the knife and eliminate the machining errors of the knife.In the above embodiments, the center of gravity is on a specific embodiment, respectively. Parts not described in detail in some embodiments can be taken from the corresponding descriptions in other embodiments.In describing the present application, it is to be noted that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "top", "bottom", "front", "rear", "left", "right", "vertical", "horizontal", "at the head", "at the bottom", "inside", "outside", "clockwise", "counterclockwise", etc. refer to the positions or positional relationships shown in the accompanying drawings and serve only for facilitating the description of the present application and do not mean or imply that the designated devices or elements have a particular position, have to be constructed in a particular position or have to be operated in a particular position, and therefore should not be understood as limiting the present application.Moreover, the terms "first", "second", and "third" are used merely for description purposes and should not be understood as indicating a relative meaning or as implicitly indicating the number of technical features specified. Thus, features labeled "first," "second," or "third" may explicitly or implicitly comprise one or more of these features. In the specification of the present application, "plural" means two or more unless expressly stated otherwise.Unless expressly stated or limited otherwise in the present application, terms such as "installed", "connected", "coupled", and "attached" are to be understood in the broadest sense, e.g., they may represent a connection, a releasable connection, or a unit; they may be a mechanical connection or an electrical connection; they may be directly connected or indirectly connected via an intermediate medium; they may represent a connection within two elements or an interaction between two elements. For a person skilled in the art, the concrete meaning of the above terms in the present application is understood from the concrete circumstances.Unless expressly stated or limited otherwise in the present application, the first feature "on" or "under" the second feature may include direct contact between the first and second features or contact between the first and second features via another feature therebetween. Moreover, the first feature "above", "above", and "above" the second feature includes the first feature being directly above or obliquely above the second feature or merely the first feature being higher than the second feature in the horizontal direction. The first feature "below", "below", and "below" the second feature includes the first feature being directly below or obliquely below the second feature or merely the first feature being lower than the second feature in the horizontal direction.In the description of the present application, terms such as "an embodiment", "some embodiments", "example", "concrete example", or "some examples" refer to the specific features, structures, materials, or characteristics described in connection with this embodiment or example, which are included in at least one embodiment or example of the present application. In this specification, the above terms are not to be understood as referring to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined as appropriate in one or more embodiments or examples. Moreover, those skilled in the art may combine and summarize the various embodiments or examples described in this specification.It is obvious that various changes and variations can be made in the present application by those skilled in the art without departing from the spirit and scope of the present application. The changes and modifications made in the present application fall within the scope of the claims of the present application and the technical solutions equivalent thereto, so that these changes and modifications are also subject matter of the present application.The above describes concrete embodiments of the present application, but the scope of the present application is not limited thereto. Those skilled in the art of the present application can easily recognize various equivalent modifications or substitutions within the scope of the disclosed technique, which are also included in the scope of the present application. The scope of the present application is therefore to be determined by the scope of the claims.

Claims

A knife length adjusting device, characterized by comprising: a knife holder (1) comprising a knife holder main body (10) and a knife mounting assembly (11) axially slidably disposed on the knife holder main body (10); and a knife adjusting module (2) comprising a push rod (20), a push rod drive (21), and a drive device (22); wherein the push rod (20) abuts the knife mounting assembly (11), the push rod drive (21) is drivingly connected to the push rod (20), and the drive device (22) is drivingly connected to the push rod drive (21).The knife length adjusting device of claim 1, wherein the push rod drive (21) comprises a drive nut (211) and a lead screw (212); the lead screw (212) is drivingly connected to an output shaft of the drive device (22), the lead screw (212) is screwed to the drive nut (211), and the drive nut (211) is fixedly connected to the push rod (20).The knife length adjusting device according to claim 2, wherein the drive nut (211) comprises a nut body (2110) and a push rod connecting part (2112); the nut body (2110) is provided with a threaded hole (2111), and the push rod connecting part (2112) is disposed along the outer periphery of the threaded hole (2111) and extends toward the knife holder (1); the push rod (20) is connected to the push rod connecting part (2112) and is coaxial with the threaded hole (2111).The knife length adjusting device according to claim 3, wherein a guide hole (2113) is disposed on the outer periphery of the threaded hole (2111), and the push rod driver (21) further comprises a guide rod (23) disposed on the guide hole (2113).The knife length adjusting device according to claim 4, wherein the knife adjusting module (2) further comprises a mounting frame (24); the driving device (22) is arranged on the mounting frame (24), and the guide rod (23) is arranged on the mounting frame (24).The knife length adjusting device according to claim 2, wherein the knife adjusting module (2) comprises a first motor block (25) arranged on a side of the drive nut (211) that is remote from the knife holder (1).The knife length adjusting device according to claim 6, wherein the knife adjusting module (2) further comprises a mounting frame (24); the drive device (22) is arranged on the mounting frame (24), and the first motor block (25) is arranged on the mounting frame (24); the knife adjusting module (2) further comprises a second motor block (26) arranged on a side of the drive nut (211) towards the knife holder (1).The knife length adjustment device of claim 1, wherein the knife length adjustment device further comprises a knife changer (27); the knife changer (27) comprises a knife change push rod (271) disposed opposite the knife mounting assembly (11) and a knife change rod drive (272) drivingly connected to the knife change push rod (271); the knife change push rod (271) is disposed with a through bore (2710) through which the knife change push rod (271) is plugged onto the push rod (20).The knife length adjusting device according to claim 1, wherein the knife holder main body (10) is disposed with a package mounting bore (101) and a knife output bore (102) connected to the package mounting bore (101); the knife mounting assembly (11) is slidably disposed in the package mounting bore (101); the tool mounting component (11) comprises: a first knife mounting bearing (111) disposed at a first end of the package mounting bore (101), a second knife mounting bearing (112) disposed at a second end of the package mounting bore (101), and a return spring (113) abutting at both ends against the first knife mounting bearing (111) and the second knife mounting bearing (112); the push rod (20) abuts against the first knife mounting bearing (111); the first blade mounting bearing ( 111) is provided with a magnetic attraction structure ( 1111).A foil cutting system comprising the knife length adjusting device according to any one of claims 1 to 9.

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