Tank opening edge cutting device for metal tank and edge cutting process of tank opening edge cutting device

Abstract

The invention discloses a can opening edge cutting device for a metal can and an edge cutting process of the can opening edge cutting device. The device comprises a cutter holder assembly, an outer cutter assembly, a cam assembly, an inner cutter driving assembly and an inner cutter assembly. The cam assembly is rotationally assembled in the first assembly cavity of the tool apron assembly, a second assembly cavity is formed in the cam assembly, and a cam curved surface section protruding in the radial direction is arranged on the circumferential surface; the inner cutter driving assembly coaxially extends into the second assembling cavity; the inner cutter assembly is eccentrically assembled in the inner cutter driving assembly and is driven by the inner cutter driving assembly to rotate in the second assembling cavity; the inner cutter assembly comprises an inner cutter, the outer cutter assembly comprises an outer cutter, during edge cutting, the inner cutter is arranged corresponding to the inner side of the edge cutting position of the can opening, and the outer cutter is arranged corresponding to the outer side of the edge cutting position; cutting force is formed through radial movement and rotation of the inner cutter and the outer cutter, and the edge of the can opening is cut. The rough-edge-free and high-efficiency thick material edge cutting can be achieved with small force, the contradiction between the machining takt and the machining precision is solved, the structure is compact, and occupied space is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the field of metal can processing, and in particular to a can mouth trimming device for metal cans and a trimming process thereof. The metal cans include cans, battery shells and the like. Background Art

[0002] Metal cans have a wide range of applications, including beverage cans and food cans in the packaging field, as well as battery shells in the container field. Their importance is self-evident. This metal shell with an opening at one end meets the needs of various application scenarios with its unique structure and function.

[0003] However, in the production process of metal cans, the trimming process is a crucial issue that cannot be ignored. Metal cans are usually made of steel or aluminum through die stamping, and the edges after stamping often leave excess or burrs. These burrs not only affect the appearance of the metal can, but may also pose a threat to its sealing and safety of use. Therefore, after the shell is stretched and formed, the can mouth must be trimmed in the height direction.

[0004] The traditional trimming method is to perform rotary cutting on a punch press. This method relies on the special mold structure and the cooperation of the punch press's motion. The mold structure consists of a fixed part and a movable part, which are connected by a guide rail or a connecting structure and can move relative to each other within a certain range. The movable part moves along a preset trajectory, such as down and then to the right, then up and then to the left, completing a circle of rotary cutting and finally resetting. The punch press's control system is responsible for controlling the stroke of the slider, the speed of movement, and the timing of the cooperation between the movable part and the fixed part to ensure the accuracy and stability of the rotary cutting process.

[0005] However, this traditional punching and peeling method has many shortcomings. First, the force required for trimming is positively correlated with the cutting length, and when the overlapping area of ​​the inner and outer molds is large, more force is required, which can only be provided by the punching machine. Secondly, the peeling action is complicated, and the inner and outer molds need to move precisely according to the designed trajectory, but due to the limitations of the punching machine's movement accuracy and the gap between the inner and outer molds (usually above 0.06mm), large burrs often remain after cutting. In actual production, these burrs often need to be removed manually, which increases production costs. In addition, the punching machine solution is bulky, and due to the complexity of the peeling action and the limitation of the punching machine speed, the peeling speed is low and the trimming accuracy is not satisfactory.

[0006] In summary, how to solve the many shortcomings of the above-mentioned traditional punching and peeling solution in the metal can trimming process and provide a more efficient and accurate trimming method has become the subject to be studied and solved by the present invention. Summary of the invention

[0007] The object of the present invention is to provide a can mouth trimming device for metal cans and its trimming process.

[0008] To achieve the above object, the technical solution adopted by the present invention is: A can mouth trimming device for metal cans, comprising a tool holder assembly, an outer knife assembly, a cam assembly, an inner knife driving assembly and an inner knife assembly; A first assembly cavity is provided in the tool holder assembly; The cam assembly is coaxially rotatably assembled in the first assembly cavity of the tool holder assembly. A second assembly cavity is provided in the cam assembly, and the second assembly cavity is coaxially arranged with the first assembly cavity and the metal can; a cam curved surface section protruding radially is provided on the circumferential surface of the second assembly cavity; The inner knife driving assembly extends into the second assembly cavity and is coaxially arranged with the second assembly cavity; the inner knife assembly is eccentrically assembled in the inner knife driving assembly and is driven by the inner knife driving assembly to rotate in the second assembly cavity; the inner knife assembly includes an inner knife, and the outer knife assembly includes an outer knife. When trimming the can mouth of the metal can, the inner knife is arranged corresponding to the inner side of the trimming position, and the outer knife is arranged corresponding to the outer side of the trimming position; the cutting edge of the outer knife is axially offset from the cutting edge of the inner knife, and a cutting force is formed with the outer knife through the radial movement and rotation of the inner knife to trim the can mouth of the metal can; The inner knife driving assembly and the cam assembly are respectively driven to rotate in the same direction around the axis, and when trimming the can mouth of a single metal can is completed, the number of rotation turns of the inner knife driving assembly is one more than the number of rotation turns of the cam assembly.

[0009] A further technical solution is that the outer knife assembly includes a tool holder plate, and the tool holder plate is arranged at the front end of the tool holder assembly at intervals along the axis of the first assembly cavity and is slidable; a circular through hole for positioning the can mouth of the metal can is provided in the tool holder plate, the circular through hole is coaxially arranged with the first assembly cavity, and the bottom edge of the circular through hole forms the outer knife.

[0010] A further technical solution is that the included angle between the first connection line from the starting end of the cam curved surface section to the axis and the second connection line from the terminating end of the cam curved surface section to the axis is less than or equal to 180°.

[0011] A further technical solution is that the inner knife driving assembly includes a chute at the front end and a sliding plate fixed to the front end of the chute; the sliding plate has a U-shaped opening, and the center line of the length direction of the U-shaped opening corresponds to the radial direction of the metal can. The inner knife assembly is radially floatingly assembled between the chute and the sliding plate of the inner knife drive assembly; the inner knife assembly further includes cam followers and follower bearings that are radially symmetrically arranged on both sides of the inner knife; the inner knife extends out of the front end of the sliding plate through the U-shaped opening and is eccentrically arranged with the axis of the inner knife drive assembly; the cam followers and the follower bearings respectively extend out of both sides of the chute and both roll and abut against the circumferential surface of the second assembly cavity.

[0012] In a further technical solution, when trimming the edge of the can mouth of a single metal can, the number of rotation turns of the cam assembly is at least two turns.

[0013] In a further technical solution, the included angle between the first connection line from the starting end of the cam curved surface section to the axis and the second connection line from the terminating end of the cam curved surface section to the axis is 90°; when trimming the edge of the can mouth of a single metal can, the number of rotation turns of the cam assembly is four turns, and the number of rotation turns of the inner knife drive assembly is five turns.

[0014] In a further technical solution, a first gear is coaxially fixed to the rear end of the cam assembly as the driven part of the cam assembly; a second gear is coaxially fixed to the rear end of the inner knife drive assembly as the driven part of the inner knife drive assembly.

[0015] In a further technical solution, the inner knife assembly includes a main body and an inner knife rod, and the cam followers and the follower bearings are respectively arranged on both sides of the main body; the inner knife is fixed to the front end of the inner knife rod; The inner knife rod is rotationally assembled in the main body through a plurality of needle bearings, and further includes a plurality of thrust bearings axially arranged on the contact surface between the inner knife rod and the main body.

[0016] In a further technical solution, a spring is further included. One end of the spring acts on the side part of the inner knife assembly, and the other end acts on the follower bearing so that the follower bearing maintains an elastic abutment against the circumferential surface of the second assembly cavity.

[0017] In a further technical solution, a pair of cam followers are provided, and the two cam followers are symmetrically arranged front and back in the axial direction.

[0018] Furthermore, the present invention also discloses a process for trimming the edge of the can mouth of a metal can, including: Step 1: Feed the metal can to be trimmed into the tool seat plate of the outer knife assembly for positioning; at this time, the radial distance between the inner knife and the outer knife is greater than the wall thickness of the metal can; Step 2: Drive the inner knife drive assembly to rotate, thereby driving the inner knife assembly to rotate together. When the inner knife assembly rotates to the point where the follower bearing abuts against the cam surface section of the cam assembly, the inner knife assembly undergoes a radial movement in the direction opposite to the abutting position with the follower bearing, thereby driving the inner knife to move radially and towards the inside of the metal can's edge trimming area, and cooperating with the outer knife on the outside of the edge trimming area to jointly form a cutting force for trimming the edge of the metal can's mouth; During edge trimming, the inner knife assembly and the cam assembly rotate in the same direction. By rotating both by a set number of turns, the inner knife assembly and the cam surface section of the cam assembly form a cumulative 360° fit, thereby achieving trimming of one full circle of the metal can's mouth.

[0019] In a further technical solution, after edge trimming is completed, drive the tool holder plate to move axially away from the tool holder assembly, thereby exposing the waste ring cut from the metal can's mouth, and remove the waste ring by high-pressure air blowing, and then retract the can to complete the edge trimming of the can's mouth; Among them, through the radial movement of the inner knife from inside the can body to outside the can body, the can body is punctured, and at the same time, it rotates to achieve the outward turning of the can's mouth.

[0020] Regarding the use of "first", "second", etc. in this article, it does not particularly refer to the meaning of order or sequence, nor is it used to limit this case. It is only used to distinguish components or operations described with the same technical terms.

[0021] Regarding the use of "connection" or "positioning" in this article, it can refer to two or more components or devices making direct physical contact with each other, or making indirect physical contact with each other, and can also refer to two or more components or devices operating or acting on each other.

[0022] Regarding the use of "comprising", "including", "having", etc. in this article, they are all open-ended terms, that is, they mean including but not limited to.

[0023] Regarding the terms used in this article, unless otherwise specifically noted, they generally have their ordinary meanings in this field, in the context of this case, and in the context of special content. Some terms used to describe this case will be discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art regarding the description of this case.

[0024] Regarding the use of "front", "rear", "upper", "lower", "left", "right", etc. in this article, they are all directional terms. In this case, they are only used to illustrate the positional relationship between various structures, and are not used to limit the protection scope of this case and the specific directions during actual implementation.

[0025] The working principle and advantages of the present invention are as follows: Through the eccentrically arranged inner knife assembly and the cam assembly with a cam curved surface section, by controlling the relationship among the rotational speed of the inner knife assembly, the rotational speed of the cam assembly, and the length of the cam curved surface section, efficient, powerful, and reliable trimming of the can mouth of metal cans can be achieved. Compared with the prior art, the present invention can trim thick materials with a wall thickness of up to 1.5 mm (the material can include steel materials, etc.), and has a wider application range.

[0026] Through the unique structural design of the inner knife assembly of the present invention, the diameter of the inner knife can be controlled within a relatively small range. During the process of the inner knife piercing the material to achieve trimming, the overlapping area between the inner knife and the outer knife is small, and the cutting length is short. Therefore, the required force is one-tenth or even less than that of the traditional punching rotary cutting solution, which helps to miniaturize the equipment, thereby reducing the utilization rate of the internal space of the lifting equipment. Among them, the diameter size of the inner knife is inversely proportional to the strength of the blade, that is, on the premise that the strength can be guaranteed, the size of the inner knife can be further miniaturized.

[0027] Through the unique structural design of the inner knife assembly and the outer knife assembly of the present invention, the axis dimension limitation of the traditional punching rotary cutting solution is overcome, so that the inner knife can be made as close as possible to the outer knife, and then the gap between the inner and outer knives can be controlled to 0.01 mm or even smaller, and the burrs on the cut can mouth are small or there are no burrs, thus meeting the customer's requirements for trimming quality, and at the same time eliminating the process of manually removing burrs, which helps to reduce production costs.

[0028] Furthermore, through the radial movement of the inner knife from inside the can body to outside the can body, piercing the can body and rotating at the same time, the function of turning the rough edge of the can mouth outward can be realized. Compared with the prior art where the rough edge turns inward after cutting, the rough edge is likely to fall into the can body, causing scratches or defects or safety hazards inside the can body. In the present invention, the rough edge will be directly cut outside the can body.

[0029] In summary, the present invention has outstanding substantive features and remarkable progress. It can not only achieve burr-free and high-efficiency trimming of thick materials with very small force, solve the contradiction between processing cycle and processing accuracy, but also has a compact structure and small volume, greatly reducing the space occupation. The trimming action of the equipment is simple, and only continuous rotational power is required to drive the inner knife to complete the radial and rotational actions, thereby improving the trimming efficiency and quality, and showing obvious advantages compared with the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Attached Figure 1 is a schematic structural diagram of an embodiment of the present invention; Attached Figure 2 is Figure 1 an enlarged view of part A in Attached Figure 3 is an assembly schematic diagram of the tool holder assembly and the outer knife assembly of an embodiment of the present invention; AttachedFigure 4 Schematic structural diagram of the cam assembly according to an embodiment of the present invention; Appendix Figure 5 Rear view of the cam assembly according to an embodiment of the present invention; Appendix Figure 6 Top view of the cam assembly according to an embodiment of the present invention; Appendix Figure 7 Schematic structural diagram of the inner knife drive assembly according to an embodiment of the present invention; Appendix Figure 8 Schematic structural diagram of the inner knife assembly according to an embodiment of the present invention; Appendix Figure 9 Cross-sectional schematic diagram of the inner knife assembly according to an embodiment of the present invention; Appendix Figure 10 Assembly schematic diagram of the inner knife assembly and the inner knife drive assembly according to an embodiment of the present invention; Appendix Figure 11 Cross-sectional schematic of an embodiment of the present invention Figure 1 ; Appendix Figure 12 Is Figure 11 Enlarged view at B in; Appendix Figure 13 Cross-sectional schematic of an embodiment of the present invention Figure 2 ; Appendix Figure 14 Cross-sectional schematic of an embodiment of the present invention Figure 3 ; Appendix Figure 15 Cross-sectional schematic diagram when trimming the can mouth according to an embodiment of the present invention; Appendix Figure 16 Is Figure 15 Enlarged view at C in; Appendix Figure 17 Exploded view of the present invention; Appendix Figure 18 Schematic of the detachable outer knife assembly and knife seat assembly according to an embodiment of the present invention Figure 1 ; Appendix Figure 19 Schematic of the detachable outer knife assembly and knife seat assembly according to an embodiment of the present invention Figure 2 .

[0031] In the above figures: 1. Tool holder assembly; 2. Outer tool assembly; 3. Cam assembly; 4. Inner tool drive assembly; 5. Inner tool assembly; 6. First assembly cavity; 7. Tool holder plate; 8. Circular through hole; 9. Outer tool; 10. Second assembly cavity; 11. Cam curved surface section; 12. Chute; 13. Slide plate; 14. U-shaped opening; 15. Inner tool; 16. Cam follower; 17. Follow-up bearing; 18. Spring; 19. Bearing; 20. First gear; 21. Second gear; 22. Main body; 23. Inner tool rod; 24. Needle bearing; 25. Thrust bearing; 26. Axis; 27. Scrap ring; 28. Metal can; L1. First connection line; L2. Second connection line; L3. Center line in the length direction of the U-shaped opening. Detailed implementation mode

[0032] The present invention will be further described below in conjunction with the drawings and embodiments: Embodiment: The present case will be clearly described below with diagrams and detailed descriptions. After any person skilled in the art understands the embodiments of the present case, they can make changes and modifications based on the technology taught by the present case, which does not deviate from the spirit and scope of the present case.

[0033] The terms used in this article are only for describing specific embodiments and are not intended to limit the present case. Singular forms such as "a", "this", "this", "the present", and "the" also include plural forms as used in this article.

[0034] Refer to the attached Figure 1 、 Figure 17 As shown, a can mouth trimming device for a metal can and its trimming process. The device includes a tool holder assembly 1, an outer tool assembly 2, a cam assembly 3, an inner tool drive assembly 4, and an inner tool assembly 5.

[0035] As Figure 3 shown, the tool holder assembly 1 is fixedly arranged relative to the clamping mechanism (not shown in the figure) of the metal can 28, and the tool holder assembly 1 has a cylindrical first assembly cavity 6.

[0036] The outer tool assembly 2 includes a tool holder plate 7, and the tool holder plate 7 is arranged at the front end of the tool holder assembly 1 at intervals along the axial direction of the first assembly cavity 6 and slides; the tool holder plate 7 has a circular through hole 8 for positioning the mouth of the metal can 28, the circular through hole 8 is coaxially arranged with the first assembly cavity 6, and a circular outer tool 9 is formed at the bottom edge of the circular through hole 8; when trimming the mouth of the metal can 28, the outer tool 9 is arranged outside the corresponding trimming position.

[0037] Preferably, as Figure 12 shown, the circular through hole 8 has a taper for guiding the mouth of the metal can 28 into the circular through hole 8 before the trimming starts, so as to ensure the trimming accuracy.

[0038] The cam assembly 3 is coaxially and rotatably assembled in the first assembly cavity 6 of the tool holder assembly 1. As shown in Figure 4 , a second assembly cavity 10 is provided in the cam assembly 3. The second assembly cavity 10 is coaxially arranged with the first assembly cavity 6 and the metal can 28. A cam curved surface section 11 protruding radially is provided on the circumferential surface of the second assembly cavity 10. The included angle α between the first connection line L1 from the starting end of the cam curved surface section 11 to the axis of the cam assembly 3 and the second connection line L2 from the terminating end of the cam curved surface section 11 to the axis is less than or equal to 180°. That is, the length of the cam curved surface section 11 occupies at most a semi-circle of the circumferential surface.

[0039] Preferably, as shown in Figure 6 , the included angle between the first connection line L1 from the starting end of the cam curved surface section 11 to the axis and the second connection line L2 from the terminating end of the cam curved surface section 11 to the axis is 90°. That is, the length of the cam curved surface section 11 occupies a quarter circle of the circumferential surface.

[0040] Specifically, as shown in Figure 5 , the cam assembly 3 is rotatably assembled with the tool holder assembly 1 through a bearing 19.

[0041] The inner tool driving assembly 4 extends into the second assembly cavity 10 and is coaxially arranged with the second assembly cavity 10. As shown in Figure 7 , the inner tool driving assembly 4 includes a chute 12 at the front end and a sliding plate 13 fixed to the front end of the chute 12. The sliding plate 13 has a U-shaped opening 14. The center line L3 of the length direction of the U-shaped opening 14 corresponds to the radial direction of the metal can 28.

[0042] As shown in Figure 10 , the inner tool assembly 5 is floatingly assembled between the chute 12 and the sliding plate 13 of the inner tool driving assembly 4 along the radial direction and is driven by the inner tool driving assembly 4 to rotate in the second assembly cavity 10. The rotation axis is parallel to the axis 26 of the second assembly cavity 10. The inner tool assembly 5 includes a circular inner tool 15 at the front end, and cam followers 16 and follower bearings 17 symmetrically arranged radially on both sides of the inner tool 15. The inner tool 15 extends out of the front end of the sliding plate 13 through the U-shaped opening 14 and is eccentrically arranged with the axis of the inner tool driving assembly 4. The cam followers 16 and the follower bearings 17 respectively extend out of both sides of the chute 12 and both roll and abut against the circumferential surface of the second assembly cavity 10 (see Figure 13 ). Since the cam follower 16 is a prior art, it will not be elaborated in this case.

[0043] Preferably, as shown in Figure 8 、 Figure 9As shown, the inner knife assembly 5 includes a main body 22 and an inner knife rod 23. The cam follower 16 and the follower bearing 17 are respectively arranged on both sides of the main body 22. The inner knife 15 is fixedly arranged at the front end of the inner knife rod 23. The inner knife rod 23 is rotationally assembled in the main body 22 through a plurality of needle bearings 24, and further includes a plurality of thrust needle bearings 25 which are axially arranged on the contact surface between the inner knife rod 23 and the main body 22.

[0044] Preferably, as Figure 14 shown, the follower bearing 17 elastically abuts against the circumferential surface of the second assembly cavity 10. Specifically, it further includes a spring 18. One end of the spring 18 acts on the side of the inner knife assembly 5, and the other end acts on the follower bearing 17 to make the follower bearing 17 keep abutting against the circumferential surface of the second assembly cavity 10.

[0045] Preferably, there are a pair of cam followers 16, and the two cam followers 16 are symmetrically arranged one in front of the other axially, so as to improve the stability of the inner knife assembly 5 during rotation.

[0046] As Figure 2 、 Figure 11 、 Figure 12 shown, the inner knife 15 is located behind the circular through hole 8 of the knife seat plate 7. When trimming the edge of the mouth of the metal can 28, the inner knife 15 is arranged corresponding to the inner side of the trimming edge. The cutting edge of the outer knife 9 is axially offset from the cutting edge of the inner knife 15, and a cutting force is formed with the outer knife 9 through the radial movement and rotation of the inner knife 15 to trim the edge of the mouth of the metal can 28 (see Figure 15 、 Figure 16 ).

[0047] The inner knife driving assembly 4 and the cam assembly 3 are respectively driven to rotate in the same direction around the axis 26. When trimming the edge of the mouth of a single metal can 28, the number of rotation turns of the cam assembly 3 is at least two turns, and the number of rotation turns of the inner knife driving assembly 4 is one turn more than that of the cam assembly 3.

[0048] Preferably, when trimming the edge of the mouth of a single metal can 28, the number of rotation turns of the cam assembly 3 is four turns, and the number of rotation turns of the inner knife driving assembly 4 is five turns.

[0049] Preferably, a first gear 20 is coaxially fixed at the rear end of the cam assembly 3 as the driven part of the cam assembly 3. The first gear 20 can be driven to rotate by the output torque of a motor (not shown in the figure), and then drive the cam assembly 3 to rotate around the axis.

[0050] Preferably, a second gear 21 is coaxially fixed to the rear end of the inner knife driving assembly 4 as the driven part of the inner knife driving assembly 4. The torque output by a motor (not shown in the figure) can be used to drive the second gear 21 to rotate, and then drive the inner knife driving assembly 4 to rotate around the axis. The trimming process of the present invention will be described as follows: First, the metal can 28 to be trimmed is fed into the circular through hole 8 in the tool holder plate 7 of the outer knife assembly 2 and positioned. At this time, the inner knife 15 of the inner knife assembly 5 has not been radially moved to the inner side of the trimming position of the metal can 28 by the driving of the inner knife driving assembly 4, that is, the radial distance between the inner knife 15 and the outer knife 9 is greater than the wall thickness of the metal can 28 at this time.

[0051] Then, drive the inner knife driving assembly 4 to rotate, and then drive the inner knife assembly 5 to rotate together. When the inner knife assembly 5 rotates to the position where the follower bearing 17 abuts against the cam surface section 11 in the cam assembly 3, the inner knife assembly 5 moves radially in the direction opposite to the abutting position of the follower bearing 17, and then drives the inner knife 15 to move radially towards the inner side of the trimming position of the metal can 28, and cooperates with the outer knife 9 on the outer side of the trimming position to jointly form a cutting force to trim the can mouth of the metal can 28.

[0052] During trimming, the inner knife assembly 5 and the cam assembly 3 rotate in the same direction. By rotating enough turns for both of them, the inner knife assembly 5 and the cam surface section 11 of the cam assembly 3 form a cumulative 360° fit, so as to realize the trimming of one circle of the can mouth of the metal can 28.

[0053] As Figure 6 shown, in this embodiment, the α angle corresponding to the length of the cam surface section 11 is 90°, so it takes four turns for the cam assembly 3 to complete one circle of trimming of the can mouth of the metal can 28, and at the same time, the inner knife assembly 5 needs to rotate five turns.

[0054] After trimming, the tool holder plate 7 can be driven to move axially away from the tool holder assembly 1 (see Figure 18 , Figure 19 ), so as to expose the waste ring 27 cut from the can mouth of the metal can 28. At this time, the waste ring 27 can be removed by means of high-pressure air blowing, etc., and then the can is withdrawn to complete the trimming of the can mouth.

[0055] Among them, by the radial movement of the inner knife 15 from the inside of the can to the outside of the can, piercing the can body and rotating at the same time, the function of turning the can mouth outwards can be realized.

[0056] The above embodiments are only used to illustrate the technical concept and characteristics of the present invention, and their purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it accordingly, and cannot be used to limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A can mouth trimming device for a metal can, characterized in that: It comprises a knife seat assembly (1), an outer knife assembly (2), a cam assembly (3), an inner knife drive assembly (4) and an inner knife assembly (5); The knife seat assembly (1) has a first assembly cavity (6); The cam assembly (3) is coaxially rotatably assembled in the first assembly cavity (6) of the knife seat assembly (1); the cam assembly (3) has a second assembly cavity (10), and the second assembly cavity (10) is coaxially arranged with the first assembly cavity (6) and the metal can (28); the circumferential surface of the second assembly cavity (10) has a radially protruding cam curved surface segment (11); The inner knife drive assembly (4) extends into the second assembly cavity (10) and is coaxially arranged with the second assembly cavity (10); the inner knife assembly (5) is eccentrically assembled in the inner knife drive assembly (4) and driven by the inner knife drive assembly (4) to rotate in the second assembly cavity (10); the inner knife assembly (5) comprises an inner knife (15), and the outer knife assembly (2) comprises an outer knife (9); when trimming the mouth of a metal can (28), the inner knife (15) is arranged corresponding to the inner side of the trimming location, and the outer knife (9) is arranged corresponding to the outer side of the trimming location; the cutting edge of the outer knife (9) is staggered with the cutting edge of the inner knife (15) in the axial direction, and the inner knife (15) forms a cutting force with the outer knife (9) through radial movement and rotation of the inner knife (15), thereby trimming the mouth of the metal can (28); The inner knife drive assembly (4) and the cam assembly (3) are respectively driven to rotate in the same direction around the axis, and when the can mouth trimming of a single metal can (28) is completed, the number of rotations of the inner knife drive assembly (4) is one more than the number of rotations of the cam assembly (3).

2. The can mouth trimming device for a metal can according to claim 1, characterized in that: The outer knife assembly (2) comprises a knife seat plate (7) which is slidably arranged at the front end of the knife seat assembly (1) along the axial spacing of the first assembly cavity (6); the knife seat plate (7) has a circular through hole (8) for positioning the mouth of the metal can (28); the circular through hole (8) is coaxially arranged with the first assembly cavity (6), and the outer knife (9) is formed on the bottom edge of the circular through hole (8).

3. The can mouth trimming device for a metal can according to claim 1, characterized in that: The included angle between a first connecting line (L1) from the starting end of the cam curved surface segment (11) to the axis and a second connecting line (L2) from the ending end of the cam curved surface segment (11) to the axis is less than or equal to 180°.

4. The can mouth trimming device for a metal can according to claim 1, characterized in that: The inner knife drive assembly (4) comprises a slide groove (12) located at the front end and a slide plate (13) fixed to the front end of the slide groove (12); the slide plate (13) has a U-shaped opening (14), and the lengthwise center line (L3) of the U-shaped opening (14) corresponds to the radial direction of the metal can (28); The inner knife assembly (5) is assembled in a floating manner along the radial direction between the slide groove (12) and the slide plate (13) of the inner knife drive assembly (4); the inner knife assembly (5) further comprises a cam follower (16) and a follower bearing (17) which are radially symmetrically arranged on both sides of the inner knife (15); the inner knife (15) extends out of the front end of the slide plate (13) through the U-shaped opening (14) and is eccentrically arranged with respect to the axis of the inner knife drive assembly (4); the cam follower (16) and the follower bearing (17) respectively extend out of both sides of the slide groove (12) and both roll against the peripheral surface of the second assembly cavity (10).

5. The can mouth trimming device for a metal can according to claim 3, characterized in that: When the can mouth trimming of a single metal can (28) is completed, the cam assembly (3) rotates at least two times.

6. The can mouth trimming device for a metal can according to claim 5, characterized in that: The angle between a first connecting line (L1) from the starting end of the cam curved surface segment (11) to the axis and a second connecting line (L2) from the ending end of the cam curved surface segment (11) to the axis is 90°; when the can mouth trimming of a single metal can (28) is completed, the number of rotations of the cam assembly (3) is four, and the number of rotations of the inner knife drive assembly (4) is five.

7. The can mouth trimming device for a metal can according to claim 1, characterized in that: A first gear (20) is coaxially fixedly provided at the rear end of the cam assembly (3) as a driven part of the cam assembly (3); and a second gear (21) is coaxially fixedly provided at the rear end of the inner knife drive assembly (4) as a driven part of the inner knife drive assembly (4).

8. The can mouth trimming device for a metal can according to claim 4, characterized in that: The inner knife assembly (5) comprises a main body (22) and an inner knife rod (23); the cam follower (16) and the follower bearing (17) are respectively arranged on both sides of the main body (22); the inner knife (15) is fixedly arranged at the front end of the inner knife rod (23); The inner cutter rod (23) is rotatably assembled in the main body (22) via a plurality of needle bearings (24), and also includes a plurality of thrust bearings (25) which are axially arranged on the contact surface between the inner cutter rod (23) and the main body (22).

9. The can mouth trimming device for a metal can according to claim 4, characterized in that: It also includes a spring (18), one end of which acts on the side of the inner knife assembly (5), and the other end of which acts on the follower bearing (17) so that the follower bearing (17) maintains elastic contact with the peripheral surface of the second assembly cavity (10).

10. The can mouth trimming device for a metal can according to claim 4, characterized in that: A pair of cam followers (16) are provided, and the two cam followers (16) are symmetrically arranged one in front and one behind in the axial direction.

11. A can mouth trimming process for metal cans, characterized in that: The method is realized by the can mouth trimming device for metal cans according to any one of claims 1 to 10, wherein the trimming process comprises: Step 1: Place the metal can (28) to be trimmed into the knife seat plate (7) of the outer knife assembly (2) for positioning; at this time, the radial distance between the inner knife (15) and the outer knife (9) is greater than the wall thickness of the metal can (28); Step 2: driving the inner knife driving assembly (4) to rotate, thereby driving the inner knife assembly (5) to rotate together; when the inner knife assembly (5) rotates until the follower bearing (17) abuts against the cam curved surface segment (11) in the cam assembly (3), the inner knife assembly (5) moves radially in the opposite direction to the abutment point of the follower bearing (17), thereby driving the inner knife (15) to move radially and toward the inner side of the trimming point of the metal can (28), and cooperate with the outer knife (9) outside the trimming point to form a cutting force, thereby trimming the mouth of the metal can (28); When trimming, the inner knife assembly (5) and the cam assembly (3) rotate in the same direction, and the inner knife assembly (5) and the cam surface segment (11) of the cam assembly (3) form a cumulative 360° fit by rotating the two for a set number of turns, thereby achieving trimming of a circle of the mouth of the metal can (28).

12. The can mouth trimming process for metal cans according to claim 11, characterized in that: After the trimming is completed, the knife seat plate (7) is driven to move away from the knife seat assembly (1) in the axial direction, thereby exposing the waste ring (27) cut from the mouth of the metal can (28), and the waste ring (27) is removed by high-pressure blowing, and then the can is withdrawn to complete the can mouth trimming; The inner knife (15) moves radially from the inside of the can body to the outside of the can body, puncturing the can body and rotating at the same time to realize the outward turning of the can mouth.

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