Round corner cutter for film packaging bag

Abstract

The utility model relates to a filleted corner cutter for a film packaging bag, which comprises a movable cutter and a fixed cutter, the movable cutter comprises a movable cutter body, the movable cutter body is integrated with a left guide fork and a right guide fork on two sides, the upper side and the lower side of the movable cutter body are movable cutter horizontal knife edge surfaces, and four corners of the movable cutter body are movable cutter filleted corner knife edge surfaces. The movable knife horizontal knife edge surface and the movable knife fillet knife edge surface are tangent in an arc shape and form an arc-shaped knife edge; the front end of the left guide fork consists of a movable knife inclined guide surface, a movable knife horizontal guide surface, a movable knife bevel surface and a movable knife left guide surface; the fixed cutter and the movable cutter are oppositely and fixedly installed, the fixed cutter is of a hollow structure, a front lower inclined vertical face and a front upper inclined vertical face are arranged on the front portion of the fixed cutter, and a fixed cutter horizontal cutter edge face, a fixed cutter fillet cutter edge face, a fixed cutter inclined guide face, a fixed cutter horizontal guide face, a fixed cutter bevel face and a fixed cutter left guide face are symmetrically arranged on the upper portion, the lower portion, the left portion and the right portion of the fixed cutter respectively; the filleted corner cutter for the thin film packaging bag solves the problems that corners of the packaging bag cut by an existing filleted corner cutter for the thin film packaging bag are prone to being eccentric left and right, and the filleted corner cutter is prone to being clamped.

Description

Technical Field

[0001] The utility model relates to the field of production of film packaging bags, and particularly to a round corner cutter for cutting round corners at four corners of a film packaging bag. Background Art

[0002] In the current field of production of film packaging bags, generally a serrated knife or a flat knife is used to cut the seals of adjacent packaging bags to separate the continuously produced packaging bags. However, the seal separation of such packaging bags is serrated or flat, which is easy to prick hands or scratch adjacent packaging bags. With the improvement of living standards, the development and progress of society, round corner cutting or separation of the seal of the packaging bag, as shown in the attached Figure 10 , the appearance of the packaging bag is more beautiful and is being more and more widely used. However, at present, the structure of the round corner cutting tools on the market is not very reasonable, resulting in eccentricity of the round corners at the seal part of the packaging bag. In particular, it often causes tool jamming during production, leading to a reduction in production efficiency. Summary of the Utility Model

[0003] The purpose of the utility model is to solve the above-mentioned deficiencies and provide a round corner cutter for film packaging bags, which solves the problems that the corners of the packaging bags cut by the current round corner cutter for film packaging bags are prone to left - right eccentricity, and the round corner cutter itself is prone to tool jamming, etc.

[0004] To achieve the above object, a round-corner cutter for a thin-film packaging bag is designed, which includes a moving cutter 10 and a fixed cutter 11. The moving cutter 10 includes a moving cutter body 100. The moving cutter body 100 and the left guiding fork 101 and the right guiding fork on both sides are of an integral structure. The left guiding fork 101 and the right guiding fork are symmetrically located on the left and right sides of the moving cutter body 100. On the upper and lower sides of the moving cutter body 100, there are moving cutter horizontal cutting-edge surfaces 120. At the four corners of the moving cutter body 100, there are moving cutter round-corner cutting-edge surfaces 121. The moving cutter horizontal cutting-edge surfaces 120 and the moving cutter round-corner cutting-edge surfaces 121 are arc-tangent and form an arc-shaped cutting edge 110. On the upper and lower sides of the front ends of the left guiding fork 101 and the right guiding fork, there are successively a moving cutter inclined guiding surface 122, a moving cutter horizontal guiding surface 123 and a moving cutter inclined angle surface 124. On the sides of the left guiding fork 101 and the right guiding fork, there are respectively a moving cutter left guiding surface 125 and a moving cutter right guiding surface. The moving cutter left guiding surface 125 and the moving cutter right guiding surface are symmetrically arranged left and right. The moving cutter inclined guiding surface 122 is arc-tangent to the moving cutter round-corner cutting-edge surface 121. The fixed cutter 11 is fixedly installed opposite to the moving cutter 10 and fits with the moving cutter 10. The fixed cutter 11 is of a hollow structure. At the front part of the fixed cutter 11, there are a front lower inclined vertical surface 203 and a front upper inclined vertical surface. The front lower inclined vertical surface 203 forms a forward expansion surface with its lower bottom edge as the base, and the front upper inclined vertical surface forms a forward expansion surface with its upper top edge as the base. With the horizontal intersection line extending forward from the front lower inclined vertical surface 203 and the front upper inclined vertical surface as the center line, on the upper and lower sides of the hollow part of the fixed cutter 11, there are fixed cutter horizontal cutting-edge surfaces 220. At the four corners of the hollow part of the fixed cutter 11, there are successively a fixed cutter round-corner cutting-edge surface 221, a fixed cutter inclined guiding surface 222, a fixed cutter horizontal guiding surface 223 and a fixed cutter inclined angle surface 224. On the left and right sides of the hollow part of the fixed cutter 11, there are fixed cutter left guiding surfaces 225. The fixed cutter horizontal cutting-edge surfaces 220 and the fixed cutter round-corner cutting-edge surfaces 221 form a round-corner cutting edge and respectively fit with the moving cutter horizontal cutting-edge surfaces 120 and the moving cutter round-corner cutting-edge surfaces 121. The fixed cutter inclined guiding surface 222 and the fixed cutter horizontal guiding surface 223 respectively fit with the moving cutter inclined guiding surface 122 and the moving cutter horizontal guiding surface 123. The fixed cutter inclined angle surface 224 and the fixed cutter left guiding surface 225 respectively correspond to the moving cutter inclined angle surface 124 and the moving cutter left guiding surface 125.

[0005] Further, the rounded cutting edge surface 121 of the moving knife is an arc less than 90°, and the center of the arc is outside the center of the moving knife 10; the arc-shaped cutting edge 110 forms the shape of a rounded waste edge 501 when viewed from the front to the back, and its function is to perform arc shearing on the sealing edge of the film to form a rounded packaging bag. When viewed from above, it is arc-shaped, and its function is to perform point shearing like scissors during shearing, rather than cutting off at once, with a neat cut; a first guiding surface 112 is provided in the middle of the inner sides of the left guiding fork 101 and the right guiding fork. The height of the first guiding surface 112 exceeds the rounded cutting edge surface 121 of the moving knife but is lower than the horizontal guiding surface 123 of the moving knife, and is parallel to the left guiding surface 125 of the moving knife; a second guiding surface 113 is provided behind the first guiding surface 112. The second guiding surface 113 is arranged to expand outward and backward, and this expansion extends to the intersection line of the inclined guiding surface 122 and the horizontal guiding surface 123 of the moving knife and reaches the rear ends of the left guiding fork 101 and the right guiding fork. Here, through the setting of the first and second guiding surfaces, it is beneficial to the guiding operation of the left guiding fork 101 and the right guiding fork.

[0006] Further, the horizontal cutting edge surface 220, the rounded cutting edge surface 221, and the inclined guiding surface 222 of the fixed knife all extend backward and expand symmetrically downward and upward to form a symmetrically arranged lower extended surface 230 and upper extended surface of the fixed knife. The lower extended surface 230 and the upper extended surface of the fixed knife contract inward in the left-right direction, thereby facilitating the running resistance of the left guiding fork 101 and the right guiding fork and being beneficial to the discharge of the rounded waste edge 501. The lower extended surface 230 of the fixed knife intersects the horizontal guiding surface 223 of the fixed knife at the extended intersection point 232.

[0007] Further, the left guiding surface 125 of the moving knife is composed of an upper left guiding surface 140, a left side vertical surface 141, and a lower left guiding surface. The upper left guiding surface 140 and the lower left guiding surface are symmetrically arranged up and down. The left side vertical surface 141 forms a concave platform relative to the upper left guiding surface 140 and the lower left guiding surface toward the right. The upper left guiding surface 140 and the lower left guiding surface are fitted with the left guiding surface 225 of the fixed knife, and the left side vertical surface 141 corresponds to the corresponding position of the left guiding surface 225 of the fixed knife. The structural design here is beneficial to reducing the running resistance of the moving knife 10.

[0008] Further, the gap between the left side vertical surface 141 and the upper left guiding surface 140 is 0.1 - 0.5 mm, and the height of the left side vertical surface 141 is between one-third and two-thirds of the left guiding surface 125 of the moving knife, so as to achieve a good balance between guiding and frictional resistance; the gap between the inclined surface 124 of the moving knife and the inclined surface 224 of the fixed knife is 0.1 - 0.5 mm.

[0009] Furthermore, the included angle between the front lower inclined facade 203 and the front upper inclined facade and the vertical direction is 12 - 18°, the included angle between the moving knife inclined guiding surface 122 and the longitudinal direction is 12 - 20°, the distance between the extension intersection point 232 and the adjacent left guiding fork 101 is 2.0 - 5.0 mm, the front - rear width of the fixed knife horizontal cutting edge surface 220 is 2.0 - 5.0 mm, and the width of the narrowest part in the front - rear direction of the moving knife horizontal cutting edge surface 120 is 1.5 - 3.0 times that of the horizontal cutting edge surface 220.

[0010] Furthermore, moving knife mounting holes 111 are provided on the front end faces of both the left guiding fork 101 and the right guiding fork. The moving knife mounting holes 111 are located at the center positions of the guiding forks and are provided with internal threaded holes. By providing the moving knife mounting holes 111, it is convenient to install and fix the moving knife 10.

[0011] Furthermore, positioning holes 210 are symmetrically arranged on the left and right of the upper top surface 200 of the fixed knife 11, which is convenient for installing and fixing the fixed knife 11. A guiding groove 211 is provided at the center of the upper top surface 200 of the fixed knife 11, and the guiding groove 211 penetrates backward to the rear facade 201, thus facilitating the initial installation and positioning of the fixed knife 11.

[0012] Furthermore, fork - end guiding surfaces 130 are provided at the outer fork - end portions at the rear ends of both the left guiding fork 101 and the right guiding fork. The fork - end guiding surfaces 130 contract towards the rear and inner sides of the corresponding guiding forks. By providing the guiding surfaces, when initially installing the moving knife 10, it is convenient for the left guiding fork 101 and the right guiding fork of the moving knife 10 to enter the fixed knife 11.

[0013] Furthermore, a fixed - knife lower concave platform 240 is provided backward from the fixed - knife horizontal cutting edge surface 220 and the fixed - knife rounded - corner cutting edge surface 221 of the fixed knife 11. The depth of the fixed - knife lower concave platform 240 is 0.1 to 0.3 mm, thus facilitating the rebound of the film packaging bag after being cut by the rounded - corner cutter and reducing the knife jamming caused by the packaging bag.

[0014] Compared with the prior art, the structure of the present utility model is novel and reasonably designed. Through the mutual cooperation of the fixed - knife parts that fit with the moving - knife horizontal cutting edge surface and the moving - knife rounded - corner cutting edge surface, the rounded - corner trimming of the packaging bag is realized. Through the arc - shaped cutting edge, the scissor - like shearing of the packaging bag and the guiding of the left and right guiding forks are achieved. The shearing is smooth, the installation and adjustment are convenient, and it is not easy to jam the knife. It solves the problems that the corners of the packaging bag cut by the rounded - corner cutter for the current film packaging bag are prone to left - right eccentricity, and the rounded - corner cutter itself is prone to knife jamming, etc., and is worthy of popularization and application. [Description of the Drawings]

[0015] Figure 1 is the three - dimensional structure schematic diagram of the present utility model Figure 1 ;

[0016] Figure 2 is the three - dimensional structure schematic diagram of the present utility modelFigure 2 ;

[0017] Figure 3 is the front view schematic diagram of the present utility model;

[0018] Figure 4 is the rear view schematic diagram of the present utility model;

[0019] Figure 5 is the three-dimensional structure schematic diagram of the fixed knife of the present utility model;

[0020] Figure 6 is the front view schematic diagram of the fixed knife of the present utility model;

[0021] Figure 7 is the three-dimensional structure schematic diagram of the moving knife of the present utility model;

[0022] Figure 8 is the front view schematic diagram of the moving knife of the present utility model;

[0023] Figure 9 is the top view schematic diagram of the moving knife of the present utility model;

[0024] Figure 10 is the schematic diagram of the rounded-corner packaging bag of the present utility model;

[0025] Figure 11 is the schematic diagram of cutting the rounded corners of the rounded-corner packaging bag of the present utility model;

[0026] In the figure: 10, moving knife; 11, fixed knife; 100, moving knife body; 101, left guiding fork; 110, arc-shaped cutting edge; 111, moving knife mounting hole; 112, first guiding surface; 113, second guiding surface; 120, moving knife horizontal cutting edge surface; 121, moving knife rounded-corner cutting edge surface; 122, moving knife inclined guiding surface; 123, moving knife horizontal guiding surface; 124, moving knife bevel surface; 125, moving knife left guiding surface; 130, fork-end guiding surface; 140, upper left guiding surface; 141, left vertical surface; 200, upper top surface; 201, rear vertical surface; 203, front lower inclined vertical surface; 210, positioning hole; 211, guiding groove; 220, fixed knife horizontal cutting edge surface; 221, fixed knife rounded-corner cutting edge surface; 222, fixed knife inclined guiding surface; 223, fixed knife horizontal guiding surface; 224, fixed knife bevel surface; 225, fixed knife left guiding surface; 230, fixed knife lower extension surface; 231, fixed knife outlet line; 232, extension intersection point; 240, fixed knife cutting edge lower concave platform; 500, continuous packaging bag before cutting; 501, rounded-corner waste edge; 502, finished packaging bag. [Specific embodiments]

[0027] The present utility model will be further described below in conjunction with the accompanying drawings:

[0028] As shown in the attached Figure 1 to the attached Figure 9As shown in the figure, the utility model provides a round-corner cutter for thin-film packaging bags, which includes a moving knife 10 and a fixed knife 11. The moving knife 10 includes a moving knife body 100. The moving knife body 100 is an integral structure with the left guiding fork 101 and the right guiding fork on both sides. The left guiding fork 101 and the right guiding fork are symmetrically located on the left and right sides of the moving knife body 100. The upper and lower sides of the moving knife body 100 are moving knife horizontal cutting edges 120, and the upper, lower, left, and right four corners are four moving knife round-corner cutting edges 121. The moving knife round-corner cutting edge 121 is an arc less than 90°, and the center of the arc is outside the center of the moving knife. The moving knife horizontal cutting edge 120 is arc-tangent to the moving knife round-corner cutting edge 121. The moving knife horizontal cutting edge 120 and the moving knife round-corner cutting edge 121 together form an arc-shaped cutting edge 110. When viewed from front to back, the arc-shaped cutting edge 110 forms the shape of a round-corner waste edge 501, and its function is to form an arc-shaped shear on the sealing edge of the thin film to form a round-corner packaging bag. When viewed from top to bottom, it is arc-shaped, and its function is to perform point shearing like scissors during shearing, rather than cutting off at one time, and the shearing is neat. The left guiding fork 101 and the right guiding fork are symmetrically located on both sides of the moving knife body 100. The front end of the left guiding fork 101 is composed of a moving knife inclined guiding surface 122, a moving knife horizontal guiding surface 123, a moving knife inclined angle surface 124, and a moving knife left guiding surface 125. Specifically, the upper and lower sides of the front ends of the left guiding fork 101 and the right guiding fork are successively provided with a moving knife inclined guiding surface 122, a moving knife horizontal guiding surface 123, and a moving knife inclined angle surface 124. The sides of the left guiding fork 101 and the right guiding fork are respectively provided with a moving knife left guiding surface 125 and a moving knife right guiding surface. The moving knife left guiding surface 125 and the moving knife right guiding surface are symmetrically arranged left and right. The moving knife inclined guiding surface 122 is arc-tangent to the moving knife round-corner cutting edge 121. The middle parts of the inner sides of the left guiding fork 101 and the right guiding fork are provided with a first guiding surface 112. The height of the first guiding surface 112 exceeds the moving knife round-corner cutting edge 121 but is lower than the moving knife horizontal guiding surface 123, and is parallel to the moving knife left guiding surface 125. A second guiding surface 113 is arranged behind the first guiding surface 112. The second guiding surface 113 expands outward and backward, and this expansion extends to the intersection line of the moving knife inclined guiding surface 122 and the moving knife horizontal guiding surface 123 and reaches the rear end of the guiding fork. Through the setting of the first and second guiding surfaces, it is beneficial to the guiding operation of the left guiding fork 101 and the right guiding fork.

[0029] The fixed knife 11 is also of an integrated structure. The fixed knife 11 fits with the moving knife 10 and is fixedly installed opposite to the moving knife 10. The fixed knife 11 is of a hollow structure, with a front lower inclined surface 203 and a front upper inclined surface provided at the front part. The front lower inclined surface 203 forms a forward expansion surface based on its lower bottom edge, and the front upper inclined surface forms a forward expansion surface based on its upper top edge. Taking the horizontal intersection line extending forward from the front lower inclined surface 203 and the front upper inclined surface as the center line, a fixed knife horizontal cutting edge surface 220, a fixed knife rounded cutting edge surface 221, a fixed knife inclined guiding surface 222, a fixed knife horizontal guiding surface 223, a fixed knife inclined angle surface 224, and a fixed knife left guiding surface 225 are symmetrically arranged above, below, left, and right respectively. Specifically, fixed knife horizontal cutting edge surfaces 220 are provided on both the upper and lower sides of the hollow part of the fixed knife 11. Fixed knife rounded cutting edge surfaces 221, fixed knife inclined guiding surfaces 222, fixed knife horizontal guiding surfaces 223, and fixed knife inclined angle surfaces 224 are sequentially provided at the four corners of the hollow part of the fixed knife 11. Fixed knife left guiding surfaces 225 are provided on both the left and right sides of the hollow part of the fixed knife 11. Among them, the fixed knife horizontal cutting edge surface 220 and the fixed knife rounded cutting edge surface 221 form a rounded cutting edge and fit with the moving knife horizontal cutting edge surface 120 and the moving knife rounded cutting edge surface 121 respectively. The fixed knife inclined guiding surface 222 and the fixed knife horizontal guiding surface 223 fit with the moving knife inclined guiding surface 122 and the moving knife horizontal guiding surface 123 respectively. The fixed knife inclined angle surface 224 and the fixed knife left guiding surface 225 correspond to the moving knife inclined angle surface 124 and the moving knife left guiding surface 125 respectively. The backward extension parts of the fixed knife horizontal cutting edge surface 220, the fixed knife rounded cutting edge surface 221, and the fixed knife inclined guiding surface 222 expand symmetrically downward and upward to form a fixed knife lower extension surface 230 and a fixed knife upper extension surface. The fixed knife lower extension surface 230 and the fixed knife upper extension surface contract inward in the left-right direction, facilitating the running resistance of the left guiding fork 101 and the right guiding fork and being conducive to the discharge of the rounded waste edge 501. The fixed knife lower extension surface 230 intersects with the fixed knife horizontal guiding surface 223 at an extension intersection point 232.

[0030] When specifically designing the rounded cutting knife of the present utility model, it is about how to determine the arc-shaped cutting edge 110. The contour lines of the moving knife horizontal cutting edge surface 120 and the moving knife rounded cutting edge surface 121 can also be calculated and customized according to the bag width of the packaging bag and the size of the arc angle of the packaging bag required by the customer.

[0031] As a further embodiment, the left guiding surface 125 of the moving knife is composed of an upper left guiding surface 140, a left vertical surface 141, and a lower left guiding surface. The left vertical surface 141 forms a concave platform to the right relative to the upper left guiding surface 140 and the lower left guiding surface. The upper left guiding surface 140 and the lower left guiding surface fit with the left guiding surface 225 of the fixed knife, and the left vertical surface 141 corresponds to the corresponding position of the left guiding surface 225 of the fixed knife. The left guiding surface 125 of the moving knife and the right guiding surface of the moving knife are symmetrically arranged left and right. The inclined surface 124 of the moving knife does not fit with the inclined surface 224 of the fixed knife, and the left vertical surface 141 does not fit with the left guiding surface 225 of the fixed knife, which is beneficial to reducing the running resistance of the moving knife 10. Further, the gap between the left vertical surface 141 and the upper left guiding surface 140 is 0.1 to 0.5 mm, and the height of the left vertical surface 141 is between one-third and two-thirds of the left guiding surface 125 of the moving knife to achieve a good balance between guiding and frictional resistance; the gap between the inclined surface 124 of the moving knife and the inclined surface 224 of the fixed knife is 0.1 to 0.5 mm.

[0032] As a further embodiment, the included angle between the front lower inclined vertical surface 203 and the front upper inclined surface and the vertical direction is 12 to 18°, the longitudinal included angle of the inclined guiding surface 122 of the moving knife is 12 to 20°, the distance from the extended intersection point 232 to the adjacent left guiding fork 101 is 2.0 to 5.0 mm, the front-back width of the horizontal cutting edge surface 220 of the fixed knife is 2.0 to 5.0 mm, and the narrowest width of the front-back direction of the horizontal cutting edge surface 120 of the moving knife is 1.5 to 3.0 times that of the horizontal cutting edge surface 220.

[0033] As a further embodiment, the moving knife mounting holes 111 are provided on the front end surfaces of the left guiding fork 101 and the right guiding fork. The moving knife mounting holes 111 are located at the center positions of the guiding forks and are provided with internal threaded holes. By providing the moving knife mounting holes 111, it is convenient to install and fix the moving knife 10. The positioning holes 210 are symmetrically arranged left and right on the upper top surface 200 of the fixed knife 11, which is convenient for installing and fixing the fixed knife 11; a guiding groove 211 is provided in the center of the upper top surface 200 of the fixed knife 11, and the guiding groove 211 penetrates backward to the rear vertical surface 201, so as to facilitate the initial installation and positioning of the fixed knife 11.

[0034] As a further embodiment, fork-end guiding surfaces 130 are provided at the outer fork-end ends of the rear ends of the left guiding fork 101 and the right guiding fork. The fork-end guiding surfaces 130 contract toward the rear side and the inner side of the guiding fork. By providing the fork-end guiding surfaces 130, it is convenient for the left guiding fork 101 and the right guiding fork of the moving knife 10 to enter the fixed knife 11 during the initial installation of the moving knife 10.

[0035] As a further embodiment, a concave platform 240 is provided backward from the horizontal cutting edge surface 220 and the rounded cutting edge surface 221 of the fixed knife 11. The depth of the concave platform 240 of the fixed knife is 0.1 to 0.3 mm, so as to facilitate the rebound of the thin film packaging bag after rounding cutting and reduce the knife jamming caused by the packaging bag.

[0036] As shown in the attached Figure 10 figure, the continuous packaging bag 500 before cutting is a long strip that is connected together before and after sealing and runs from top to bottom in the direction shown by the arrow in the figure; during the cutting interval of continuous production of the packaging machine, for the long strip of the continuous packaging bag 500 before cutting containing the rounded waste edge 501, its rounded waste edge 501 is blocked and guided and is surrounded between the left guiding fork 101 and the right guiding fork. The moving knife body 100 runs backward, and the arc-shaped cutting edge 110 on the moving knife body 100 forms a shearing effect with the fixed knife 11 to cut the sealing part of the continuous packaging bag 500 before cutting. The cut-off rounded waste edge 501 is pushed out from behind the fixed knife 11, and the lowermost one is the finished packaging bag 502 cut off. As shown in the attached Figure 11 figure, it is a standard rounded packaging bag, and the four corners of this packaging bag are arc-shaped.

[0037] To sum up, the present utility model discloses a rounded cutter for a film packaging bag, which includes a moving knife and a fixed knife. The moving knife includes a moving knife body, and the moving knife body is integrally structured with the left and right guiding forks on both sides. The moving knife body includes upper and lower horizontal cutting surfaces and four extended rounded cutting surfaces at the four corners of the knife body; the fixed knife is also an integral structure, fits with the moving knife, and is fixedly installed opposite to the moving knife. In this rounded cutter for a film packaging bag, when the sealing part of the film packaging bag moves downward to the center of the rounded cutter, the moving knife moves backward through the left and right guiding forks and moves opposite to the fixed knife. The arc-shaped cutting edge on the moving knife cuts the sealing part of the packaging bag with the linear cutting edge of the fixed knife to form a packaging bag with rounded corners. Compared with the prior art, it has a reasonable structure, smooth cutting, is convenient for installation and adjustment, and is not easy to get stuck with the knife.

[0038] The content not described in detail in this specification belongs to the prior art well-known to those skilled in the art. The standard parts used can be purchased from the market. The special-shaped parts can be customized according to the description in the specification and the attached drawings. The specific connection methods of each part all adopt conventional means such as bolts, rivets, and welding that are mature in the prior art. The machines, parts, and equipment all adopt conventional models in the prior art, and the circuit connection adopts the conventional connection method in the prior art, which will not be elaborated here.

[0039] The present utility model is not limited by the above-mentioned embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present utility model shall be equivalent replacement methods and are all included in the protection scope of the present utility model.

Claims

1. A rounded corner cutter for film packaging bags, comprising a movable knife (10) and a fixed knife (11), characterized in that: The movable knife (10) comprises a movable knife body (100), wherein the movable knife body (100) and a left guide fork (101) and a right guide fork on both sides are an integral structure, wherein the left guide fork (101) and the right guide fork are symmetrically located on the left and right sides of the movable knife body (100); movable knife horizontal blade surfaces (120) are provided on the upper and lower sides of the movable knife body (100), and movable knife rounded blade surfaces (121) are provided at the four corners of the movable knife body (100), wherein the movable knife horizontal blade surface (120) and the movable knife rounded blade surface (121) are arc-shaped. Cutting and forming an arc-shaped blade edge (110), the upper and lower sides of the front ends of the left guide fork (101) and the right guide fork are respectively provided with a movable blade oblique guide surface (122), a movable blade horizontal guide surface (123) and a movable blade oblique angle surface (124), the side surfaces of the left guide fork (101) and the right guide fork are respectively provided with a movable blade left guide surface (125) and a movable blade right guide surface, the movable blade left guide surface (125) and the movable blade right guide surface are symmetrically arranged, and the movable blade oblique guide surface (122) is tangent to the movable blade rounded blade edge surface (121) in an arc shape; The fixed knife (11) is fixedly installed opposite to the movable knife (10) and fits with the movable knife (10). The fixed knife (11) is a hollow structure. A front lower oblique vertical surface (203) and a front upper oblique vertical surface are arranged at the front of the fixed knife (11). The front lower oblique vertical surface (203) forms a forward expansion surface based on its lower bottom edge and the front upper oblique vertical surface forms a forward expansion surface based on its upper top edge. The horizontal intersection line of the front lower oblique vertical surface (203) and the front upper oblique vertical surface extending forward is used as the center line. The upper and lower sides of the hollow of the fixed knife (11) are provided with fixed knife horizontal blade surfaces (220). The four corners of the hollow of the fixed knife (11) are provided with fixed knife rounded blade surfaces (221), fixed knife oblique guide surfaces (222), The fixed knife (11) has a horizontal guide surface (223) and a beveled surface (224) for the fixed knife. The left guide surface (225) for the fixed knife is provided on both the left and right sides of the hollow of the fixed knife. The horizontal blade surface (220) and the rounded blade surface (221) of the fixed knife form a rounded blade and respectively match the horizontal blade surface (120) and the rounded blade surface (121) of the movable knife. The beveled guide surface (222) and the horizontal guide surface (223) of the fixed knife respectively match the beveled guide surface (122) and the horizontal guide surface (123) of the movable knife. The beveled surface (224) and the left guide surface (225) of the fixed knife respectively correspond to the beveled surface (124) and the left guide surface (125) of the movable knife.

2. The rounded corner cutter for film packaging bags according to claim 1, characterized in that: The movable knife rounded edge surface (121) is an arc less than 90 degrees, and the center of the arc is located outside the center of the movable knife (10); the arc-shaped edge (110) forms a rounded waste edge (501) shape when viewed from the front to the back, and is an arc shape when viewed from the top to the bottom; a first guide surface (112) is provided at the middle of the inner side of the left guide fork (101) and the right guide fork, the height of the first guide surface (112) exceeds the movable knife rounded edge surface (121) but is lower than the movable knife horizontal guide surface (123), and is parallel to the movable knife left guide surface (125); a second guide surface (113) is provided at the rear side of the first guide surface (112), the second guide surface (113) is expanded outward and backward, and the expansion extends to the intersection of the movable knife oblique guide surface (122) and the movable knife horizontal guide surface (123), and to the rear end of the left guide fork (101) and the right guide fork.

3. The rounded corner cutter for film packaging bags according to claim 2, characterized in that: The fixed knife horizontal blade surface (220), the fixed knife rounded blade surface (221), and the fixed knife oblique guide surface (222) all extend backward and expand symmetrically downward and upward to form a fixed knife lower extension surface (230) and a fixed knife upper extension surface that are symmetrical in the upper and lower directions. The fixed knife lower extension surface (230) and the fixed knife upper extension surface shrink inward in the left-right direction. The fixed knife lower extension surface (230) intersects with the fixed knife horizontal guide surface (223) at an extension intersection point (232).

4. The rounded corner cutter for film packaging bags according to claim 1, characterized in that: The movable knife left guide surface (125) is composed of an upper left guide surface (140), a left vertical surface (141) and a lower left guide surface. The upper left guide surface (140) and the lower left guide surface are symmetrically arranged up and down. The left vertical surface (141) forms a concave platform to the right relative to the upper left guide surface (140) and the lower left guide surface. The upper left guide surface (140) and the lower left guide surface are matched with the fixed knife left guide surface (225). The left vertical surface (141) corresponds to the corresponding position of the fixed knife left guide surface (225).

5. The rounded corner cutter for film packaging bags according to claim 4, characterized in that: The gap between the left vertical surface (141) and the upper left guide surface (140) is 0.1 to 0.5 mm, the height of the left vertical surface (141) is between one third and two thirds of the left guide surface (125) of the movable knife, and the gap between the movable knife bevel surface (124) and the fixed knife bevel surface (224) is 0.1 to 0.5 mm.

6. The rounded corner cutter for film packaging bags according to claim 3, characterized in that: The angles between the front lower inclined surface (203) and the front upper inclined surface and the vertical direction are 12 to 18 degrees, the angle between the movable knife inclined guide surface (122) and the longitudinal direction is 12 to 20 degrees, the distance between the extended intersection point (232) and the adjacent left guide fork (101) is 2.0 to 5.0 millimeters, the front-to-back width of the fixed knife horizontal blade surface (220) is 2.0 to 5.0 millimeters, and the width of the movable knife horizontal blade surface (120) at its narrowest point in the front-to-back direction is 1.5 to 3.0 times that of the horizontal blade surface (220).

7. The rounded corner cutter for film packaging bags according to any one of claims 1 to 6, characterized in that: The front end surfaces of the left guide fork (101) and the right guide fork are both provided with a movable knife mounting hole (111), the movable knife mounting hole (111) is located at the center of the guide fork and is provided with an internal threaded hole.

8. The rounded corner cutter for film packaging bags according to any one of claims 1 to 6, characterized in that: The upper top surface (200) of the fixed knife (11) is symmetrically provided with positioning holes (210), and the upper top surface (200) of the fixed knife (11) is centrally provided with a guide groove (211), and the guide groove (211) extends backwards to the rear vertical surface (201).

9. The rounded corner cutter for film packaging bags according to any one of claims 1 to 6, characterized in that: The rear outer fork ends of the left guide fork (101) and the right guide fork are both provided with fork end guide surfaces (130), and the fork end guide surfaces (130) shrink toward the rear side and the inner side of the corresponding guide fork.

10. The rounded corner cutter for film packaging bags according to any one of claims 1 to 6, characterized in that: A fixed blade concave platform (240) is arranged backward from the fixed blade horizontal blade surface (220) and the fixed blade rounded blade surface (221) of the fixed blade (11), and the depth of the fixed blade concave platform (240) is 0.1 to 0.3 mm.

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