Can mouth trimming device and trimming process for metal cans

Abstract

This invention discloses a can-mouth trimming device and its trimming process for metal cans. The device includes a knife holder assembly, an outer knife assembly, a cam assembly, an inner knife drive assembly, and an inner knife assembly. The cam assembly is rotatably mounted in a first mounting cavity of the knife holder assembly, and the cam assembly has a second mounting cavity with a radially protruding cam surface segment on its circumference. The inner knife drive assembly extends coaxially into the second mounting cavity. The inner knife assembly is eccentrically mounted in the inner knife drive assembly and is driven by the inner knife drive assembly to rotate in the second mounting cavity. The inner knife assembly includes an inner knife, and the outer knife assembly includes an outer knife. During trimming, the inner knife is positioned on the inner side corresponding to the trimming edge of the can mouth, and the outer knife is positioned on the outer side corresponding to the trimming edge. The radial movement and rotation of the inner knife, together with the outer knife, generate a cutting force to trim the can mouth. This invention can achieve burr-free, high-efficiency trimming of thick materials with very little force, resolving the contradiction between processing cycle time and processing accuracy. Moreover, it has a compact structure and greatly reduces space occupation.

Description

Technical Field

[0001] This invention relates to the field of metal can processing, specifically to a can mouth trimming device and its trimming process for metal cans, including beverage cans, battery cases, etc. Background Technology

[0002] Metal cans have a wide range of applications, including beverage cans and food cans in the packaging field, as well as battery casings in the container field, and their importance is self-evident. These metal shells, open at one end, meet the needs of various application scenarios thanks to their unique structure and function.

[0003] However, the edge trimming process is a crucial and indispensable issue in the production of metal cans. Metal cans are typically made from steel or aluminum through die stamping, and the stamped edges often leave excess material or burrs. These burrs not only affect the aesthetics of the metal can but may also threaten its sealing performance and safety. Therefore, after the shell is stretched and formed, the can opening must be trimmed along its height.

[0004] Traditional edge trimming is achieved through rotary cutting on a punch press. This method relies on a special die structure and the coordinated motion of the punch press. The die structure consists of a fixed part and a moving part, connected by guide rails or connecting structures, and can move relative to each other within a certain range. The moving part moves along a preset trajectory, such as downward, then right, then upward, then left, completing one revolution of rotary cutting motion, and finally returning to its original position. The punch press's control system is responsible for controlling the slide's stroke, speed, and the timing of the engagement between the moving and fixed parts to ensure the accuracy and stability of the rotary cutting process.

[0005] However, this traditional rotary cutting method has several shortcomings. First, the force required for edge trimming is directly proportional to the cutting length, and the force required is even greater when the inner and outer dies overlap significantly, a force only a punch press can provide. Second, the rotary cutting motion is complex, requiring the inner and outer dies to move precisely along the designed trajectory. However, due to limitations in punch press motion accuracy and the clearance between the inner and outer dies (typically above 0.06mm), large burrs often remain after cutting. In actual production, these burrs often need to be removed manually, increasing production costs. Furthermore, punch press solutions are bulky, and due to the complexity of the rotary cutting motion and the limitations of punch press speed, the rotary cutting speed is low, and the edge trimming accuracy is not satisfactory.

[0006] In summary, the present invention aims to address the numerous shortcomings of traditional punching and rotary cutting methods in the edge cutting process of metal cans, and to provide a more efficient and accurate edge cutting method. Summary of the Invention

[0007] The purpose of this invention is to provide a device for trimming the mouth of a metal can and the trimming process thereof.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A can mouth trimming device for metal cans includes a knife holder assembly, an outer knife assembly, a cam assembly, an inner knife drive assembly, and an inner knife assembly;

[0010] The tool holder assembly has a first assembly cavity;

[0011] The cam assembly is coaxially rotatably assembled in the first assembly cavity of the tool holder assembly. The cam assembly has a second assembly cavity, which is coaxially arranged with the first assembly cavity and the metal can. The circumferential surface of the second assembly cavity has a radially protruding cam surface segment.

[0012] The inner blade drive assembly extends into the second assembly cavity and is coaxially arranged with the second assembly cavity; the inner blade assembly is eccentrically mounted in the inner blade drive assembly and is driven by the inner blade drive assembly to rotate in the second assembly cavity; the inner blade assembly includes an inner blade, and the outer blade assembly includes an outer blade. When cutting the edge of the metal can opening, the inner blade is positioned on the inner side corresponding to the cutting edge, and the outer blade is positioned on the outer side corresponding to the cutting edge; the cutting edge of the outer blade is axially offset from the cutting edge of the inner blade, and a cutting force is formed with the outer blade through the radial movement and rotation of the inner blade to cut the edge of the metal can opening;

[0013] The inner knife drive assembly and the cam assembly are driven to rotate in the same direction around the axis, and when the mouth of a single metal can is cut, the inner knife drive assembly rotates one more revolution than the cam assembly.

[0014] In a further technical solution, the outer blade assembly includes a blade holder plate, which is axially spaced and slidably disposed at the front end of the blade holder assembly along the first assembly cavity; the blade holder plate has a circular through hole for positioning the mouth of the metal can, the circular through hole is coaxially disposed with the first assembly cavity, and the outer blade is formed at the bottom edge of the circular through hole.

[0015] In a further technical solution, the angle between the first line connecting the starting end of the cam surface segment to the axis and the second line connecting the ending end of the cam surface segment to the axis is less than or equal to 180°.

[0016] In a further technical solution, the inner knife drive assembly includes a slide groove located at the front end and a slide plate fixed to the front end of the slide groove; the slide 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.

[0017] The inner blade assembly is radially floatingly mounted between the slide groove and the slide plate of the inner blade drive assembly; the inner blade assembly also includes a cam follower and a follower bearing radially symmetrically arranged on both sides of the inner blade; the inner blade extends out of the front end of the slide plate through the U-shaped opening and is eccentrically arranged with respect to the axis of the inner blade drive assembly; the cam follower and the follower bearing extend out of both sides of the slide groove and roll against the circumferential surface of the second assembly cavity.

[0018] A further technical solution is that when completing the edge trimming of a single metal can opening, the cam assembly rotates at least two times.

[0019] In a further technical solution, the angle between the first line connecting the starting end of the cam surface segment to the axis and the second line connecting the ending end of the cam surface segment to the axis is 90°; when completing the can mouth trimming of a single metal can, the cam assembly rotates four times and the inner knife drive assembly rotates five times.

[0020] In a further technical solution, a first gear is coaxially fixed at the rear end of the cam assembly, serving as the driven part of the cam assembly; a second gear is coaxially fixed at the rear end of the inner blade drive assembly, serving as the driven part of the inner blade drive assembly.

[0021] In a further technical solution, the inner blade assembly includes a main body and an inner blade rod, with the cam follower and the follower bearing respectively disposed on both sides of the main body; the inner blade is fixed to the front end of the inner blade rod;

[0022] The inner cutter bar is rotatably assembled in the main body via multiple needle roller bearings, and also includes multiple thrust bearings arranged axially on the contact surface between the inner cutter bar and the main body.

[0023] A further technical solution also includes a spring, one end of which acts on the side of the inner blade assembly and the other end of which acts on the follower bearing, so that the follower bearing maintains elastic contact with the circumferential surface of the second assembly cavity.

[0024] In a further technical solution, the cam follower is provided as a pair, with the two cam followers symmetrically arranged one in front of the other in the axial direction.

[0025] Furthermore, the present invention also discloses a can-mouth trimming process for metal cans, including:

[0026] Step 1: Position the metal can to be cut into the cutter holder plate of the outer cutter assembly; at this time, the radial distance between the inner and outer cutters is greater than the wall thickness of the metal can.

[0027] Step 2: Drive the inner blade drive assembly to rotate, which in turn drives the inner blade assembly to rotate together. When the inner blade assembly rotates to the point where the follower bearing abuts against the cam surface section in the cam assembly, the inner blade assembly moves radially in the opposite direction to the abutment point of the follower bearing. This drives the inner blade to move radially toward the inner side of the metal can cutting edge, which, together with the outer blade on the outer side of the cutting edge, forms a cutting force to cut the edge of the metal can opening.

[0028] During the trimming process, the inner blade assembly and the cam assembly rotate in the same direction. By rotating the two a set number of times, the cam surface segments of the inner blade assembly and the cam assembly form a cumulative 360° engagement, thereby achieving the trimming of one circumference of the metal can opening.

[0029] A further technical solution is to drive the cutter plate away from the cutter assembly along the axial direction after the edge trimming is completed, thereby exposing the waste ring cut off from the mouth of the metal can, and removing the waste ring by high-pressure air blowing, and then removing the can to complete the edge trimming of the mouth;

[0030] The process involves the inner knife moving radially from inside the can to outside, piercing the can body, and simultaneously rotating to turn the can opening outwards.

[0031] The terms "first," "second," etc., used in this article do not specifically refer to order or sequence, nor are they intended to limit this case; they are merely used to distinguish components or operations described using the same technical terms.

[0032] The terms "connection" or "positioning" as used in this article can refer to two or more components or devices making direct physical contact with each other, or making indirect physical contact with each other, or to two or more components or devices operating or moving with each other.

[0033] The terms “include,” “including,” and “have” used in this article are all open-ended, meaning they include but are not limited to.

[0034] Unless otherwise specified, the terms used herein generally have their ordinary meaning in the context of the art, the subject matter, and the specific context. Certain 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 in describing the case.

[0035] The terms “front,” “back,” “up,” “down,” “left,” and “right” used in this article are directional terms. In this case, they are only used to describe the positional relationship between the structures and are not intended to limit the specific direction of the protection scheme or its actual implementation.

[0036] The working principle and advantages of this invention are as follows:

[0037] This invention utilizes an eccentrically positioned inner blade assembly and a cam assembly with a cam curved surface section. By controlling the relationship between the rotational speed of the inner blade assembly, the rotational speed of the cam assembly, and the length of the cam curved surface section, it achieves efficient, powerful, and reliable edge trimming of metal can mouths. Compared to existing technologies, this invention can trim materials with a wall thickness of up to 1.5 mm (materials may include steel, etc.), thus having a wider range of applications.

[0038] This invention, through a unique internal blade assembly structure design, allows for control of the internal blade diameter within a small range. During the process of the internal blade piercing the material to achieve edge cutting, the overlap area between the internal and external blades is small, resulting in a shorter cutting length. Therefore, the required force is one-tenth or even less than that of traditional punch press rotary cutting schemes, contributing to equipment miniaturization and thus improving the utilization of internal space. Furthermore, the diameter of the internal blade is inversely proportional to the blade strength; that is, while ensuring sufficient strength, the internal blade size can be further miniaturized.

[0039] This invention overcomes the axial dimension limitations of traditional punch press rotary cutting schemes through the unique structural design of the inner and outer blade assemblies. This allows the inner blade to be as close as possible to the outer blade, thereby controlling the gap between the inner and outer blades to 0.01mm or even smaller. The cut can opening has small or no burrs, thus meeting the customer's requirements for edge quality. At the same time, it eliminates the need for manual burr removal, which helps to reduce production costs.

[0040] Furthermore, this invention uses an inner blade to move radially from inside the can to outside the can, piercing the can while rotating, thus achieving the function of turning the rough edge of the can opening outward. Compared to the prior art where the rough edge is turned inward after cutting, the rough edge is more likely to fall into the can, causing scratches or defects or safety hazards inside the can. This invention will cut the rough edge directly outside the can.

[0041] In summary, this invention possesses outstanding substantive features and significant advancements. It not only achieves burr-free, high-efficiency edge cutting of thick materials with minimal force, resolving the contradiction between processing cycle time and processing accuracy, but also boasts a compact structure and small size, greatly reducing space occupancy. The cutting action of the equipment is simple, requiring only continuous rotational power to drive the inner blade to complete radial and rotary movements, thus demonstrating significant advantages over existing technologies while improving cutting efficiency and quality. Attached Figure Description

[0042] Appendix Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention;

[0043] Appendix Figure 2 for Figure 1 Enlarged view of point A in the middle;

[0044] Appendix Figure 3This is an assembly diagram of the tool holder assembly and the outer tool assembly according to an embodiment of the present invention;

[0045] Appendix Figure 4 This is a schematic diagram of the cam assembly according to an embodiment of the present invention;

[0046] Appendix Figure 5 This is a rear view of the cam assembly according to an embodiment of the present invention;

[0047] Appendix Figure 6 This is a top view of the cam assembly according to an embodiment of the present invention;

[0048] Appendix Figure 7 This is a schematic diagram of the internal blade driving assembly according to an embodiment of the present invention;

[0049] Appendix Figure 8 This is a schematic diagram of the internal blade assembly in an embodiment of the present invention;

[0050] Appendix Figure 9 This is a cross-sectional schematic diagram of the internal blade assembly according to an embodiment of the present invention;

[0051] Appendix Figure 10 This is an assembly diagram of the inner blade assembly and the inner blade drive assembly according to an embodiment of the present invention;

[0052] Appendix Figure 11 This is a cross-sectional view of an embodiment of the present invention. Figure 1 ;

[0053] Appendix Figure 12 for Figure 11 Enlarged view of point B in the middle;

[0054] Appendix Figure 13 This is a cross-sectional view of an embodiment of the present invention. Figure 2 ;

[0055] Appendix Figure 14 This is a cross-sectional view of an embodiment of the present invention. Figure 3 ;

[0056] Appendix Figure 15 This is a cross-sectional view of the can opening during the trimming process according to an embodiment of the present invention;

[0057] Appendix Figure 16 for Figure 15 Enlarged view of point C in the middle;

[0058] Appendix Figure 17 This is an exploded view of an embodiment of the present invention;

[0059] Appendix Figure 18 This is a schematic diagram of the separate external blade assembly and blade holder assembly in an embodiment of the present invention. Figure 1 ;

[0060] Appendix Figure 19This is a schematic diagram of the separate external blade assembly and blade holder assembly in an embodiment of the present invention. Figure 2 .

[0061] 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. Slide groove; 13. Slide plate; 14. U-shaped opening; 15. Inner tool; 16. Cam follower; 17. Follower bearing; 18. Spring; 19. Bearing; 20. First gear; 21. Second gear; 22. Main body; 23. Inner tool holder; 24. Needle roller bearing; 25. Thrust bearing; 26. Axis; 27. Scrap ring; 28. Metal can; L1. First connecting line; L2. Second connecting line; L3. Center line of the length direction of the U-shaped opening. Detailed Implementation

[0062] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0063] Example: The present invention will be clearly described below with illustrations and detailed description. Any person skilled in the art who understands the examples of the present invention can make changes and modifications based on the technology taught in the present invention without departing from the spirit and scope of the present invention.

[0064] The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the scope of this work. Singular forms such as “a,” “this,” “this,” “the,” and “the” as used herein also include plural forms.

[0065] See appendix Figure 1 , Figure 17 As shown, a can mouth trimming device and its trimming process for metal cans are disclosed. The device includes a knife holder assembly 1, an outer knife assembly 2, a cam assembly 3, an inner knife drive assembly 4, and an inner knife assembly 5.

[0066] like Figure 3 As shown, the tool holder assembly 1 is fixedly disposed 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.

[0067] The outer blade assembly 2 includes a blade holder plate 7, which is slidably disposed at the front end of the blade holder assembly 1 along the axial distance of the first assembly cavity 6; the blade 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 disposed with the first assembly cavity 6, and a circular outer blade 9 is formed at the bottom edge of the circular through hole 8; when cutting the edge of the mouth of the metal can 28, the outer blade 9 is disposed on the outer side of the cutting edge.

[0068] Preferred, such as Figure 12As shown, the circular through hole 8 has a taper, which is used to guide the metal can 28 when it enters the circular through hole 8 before the cutting begins, thereby ensuring the cutting accuracy.

[0069] The cam assembly 3 is coaxially rotatably assembled in the first assembly cavity 6 of the tool holder assembly 1, such as Figure 4 As shown, the cam assembly 3 has a second assembly cavity 10, which 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 surface segment 11, and the angle α between the first line L1 connecting the starting end of the cam surface segment 11 to the axis of the cam assembly 3 and the second line L2 connecting the ending end of the cam surface segment 11 to the axis is less than or equal to 180°. That is, the length of the cam surface segment 11 occupies at most a semicircle of the circumferential surface.

[0070] Preferred, such as Figure 6 As shown, the angle between the first line L1 connecting the starting end of the cam surface segment 11 to the axis and the second line L2 connecting the ending end of the cam surface segment 11 to the axis is 90°. That is, the length of the cam surface segment 11 occupies 1 / 4 of the circumference.

[0071] Specifically, such as Figure 5 As shown, the cam assembly 3 is rotatably assembled with the tool holder assembly 1 via the bearing 19.

[0072] The inner blade drive assembly 4 extends into the second assembly cavity 10 and is coaxially arranged with the second assembly cavity 10; for example Figure 7 As shown, the internal blade drive assembly 4 includes 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 center line L3 of the length direction of the U-shaped opening 14 corresponds to the radial direction of the metal can 28.

[0073] like Figure 10 As shown, the inner blade assembly 5 is radially floatingly mounted between the slide groove 12 and the slide plate 13 of the inner blade drive assembly 4, and is driven by the inner blade drive assembly 4 to rotate in the second assembly cavity 10, with the rotation axis parallel to the axis 26 of the second assembly cavity 10. The inner blade assembly 5 includes a circular inner blade 15 located at the front end, and cam followers 16 and follower bearings 17 radially symmetrically arranged on both sides of the inner blade 15; the inner blade 15 extends out from 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 blade drive assembly 4; the cam followers 16 and the follower bearings 17 extend out from both sides of the slide groove 12, and both roll against the circumferential surface of the second assembly cavity 10 (see...). Figure 13 Since the cam follower 16 is existing technology, it will not be described in detail here.

[0074] Preferred, such as Figure 8 , Figure 9 As shown, the inner cutter assembly 5 includes a main body 22 and an inner cutter bar 23. The cam follower 16 and the follower bearing 17 are respectively disposed on both sides of the main body 22. The inner cutter 15 is fixed to the front end of the inner cutter bar 23. The inner cutter bar 23 is rotatably assembled in the main body 22 through multiple needle roller bearings 24, and also includes multiple thrust needle roller bearings 25, which are axially disposed on the contact surface between the inner cutter bar 23 and the main body 22.

[0075] Preferred, such as Figure 14 As shown, the follower bearing 17 elastically abuts against the circumferential surface of the second assembly cavity 10. Specifically, it also includes a spring 18, one end of which acts on the side of the inner blade assembly 5, and the other end acts on the follower bearing 17, so that the follower bearing 17 maintains its abutment against the circumferential surface of the second assembly cavity 10.

[0076] Preferably, the cam follower 16 is provided in pairs, and the two cam followers 16 are symmetrically arranged one in front of the other in the axial direction, thereby improving the stability of the inner knife assembly 5 when rotating.

[0077] like Figure 2 , Figure 11 , Figure 12 As shown, the inner blade 15 is located behind the circular through hole 8 of the blade holder plate 7. When cutting the edge of the metal can 28, the inner blade 15 is positioned inside the cutting edge. The cutting edge of the outer blade 9 is axially offset from the cutting edge of the inner blade 15, and the radial movement and rotation of the inner blade 15 generate a cutting force with the outer blade 9 to cut the edge of the metal can 28 (see...). Figure 15 , Figure 16 ).

[0078] The inner knife drive assembly 4 and the cam assembly 3 are driven to rotate in the same direction around the axis 26. When the can mouth of a single metal can 28 is cut, the cam assembly 3 rotates at least two times, and the inner knife drive assembly 4 rotates one more time than the cam assembly 3.

[0079] Preferably, when completing the can opening trimming of a single metal can 28, the cam assembly 3 rotates four times and the inner knife drive assembly 4 rotates five times.

[0080] Preferably, a first gear 20 is coaxially fixed at the rear end of the cam assembly 3, serving as the driven part of the cam assembly 3. The first gear 20 can be driven to rotate by the torque output of a motor (not shown in the figure), thereby driving the cam assembly 3 to rotate around the axis.

[0081] Preferably, a second gear 21 is coaxially fixed at the rear end of the inner blade drive assembly 4, serving as the driven part of the inner blade drive assembly 4. The second gear 21 can be driven to rotate by the torque output of a motor (not shown in the figure), thereby driving the inner blade drive assembly 4 to rotate around the axis.

[0082] The edge trimming process of this invention is described below:

[0083] First, the metal can 28 to be cut is fed into the circular through hole 8 in the blade holder plate 7 of the outer blade assembly 2 and positioned. At this time, the inner blade 15 of the inner blade assembly 5 has not yet been driven radially by the inner blade drive assembly 4 to the inner side of the metal can 28 at the cutting edge, that is, at this time the radial distance between the inner blade 15 and the outer blade 9 is greater than the wall thickness of the metal can 28.

[0084] Then, the inner blade drive assembly 4 is driven to rotate, which in turn drives the inner blade assembly 5 to rotate together. When the inner blade assembly 5 rotates to the point where the follower bearing 17 abuts against the cam curved surface section 11 in the cam assembly 3, the inner blade assembly 5 moves radially in the opposite direction to the abutment point of the follower bearing 17, which in turn drives the inner blade 15 to move radially toward the inner side of the metal can 28 cutting edge, and together with the outer blade 9 on the outer side of the cutting edge, forms a cutting force to cut the edge of the metal can 28.

[0085] During the cutting process, the inner blade assembly 5 and the cam assembly 3 rotate in the same direction. By rotating the two a sufficient number of times, the inner blade assembly 5 and the cam surface segment 11 of the cam assembly 3 form a cumulative 360° engagement, thereby achieving the cutting of one circumference of the mouth of the metal can 28.

[0086] like Figure 6 As shown, in this embodiment, the α angle corresponding to the length of the cam curved surface segment 11 is 90°. Therefore, to complete the cutting of one circle of the mouth of the metal can 28, the cam assembly 3 needs to rotate four times, and the inner blade assembly 5 needs to rotate five times.

[0087] After the cutting is completed, the tool holder plate 7 can be driven axially away from the tool holder assembly 1 (see...). Figure 18 , Figure 19 This exposes the waste ring 27 cut from the mouth of the metal can 28. At this point, the waste ring 27 can be removed by means of high-pressure air blowing, and then the can is removed to complete the can mouth trimming.

[0088] The inner knife 15 moves radially from inside the can to outside the can, piercing the can and rotating simultaneously, thus achieving the function of turning the can opening outward.

[0089] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A device for trimming the mouth of a metal can, characterized in that: It 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); The tool holder assembly (1) has a first assembly cavity (6); The cam assembly (3) is coaxially rotatably assembled in the first assembly cavity (6) of the tool holder assembly (1). The cam assembly (3) has a second assembly cavity (10), which 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 surface segment (11). The inner blade drive assembly (4) extends into the second assembly cavity (10) and is coaxially arranged with the second assembly cavity (10); the inner blade assembly (5) is eccentrically assembled in the inner blade drive assembly (4) and is driven by the inner blade drive assembly (4) to rotate in the second assembly cavity (10); the inner blade assembly (5) includes an inner blade (15), and the outer blade assembly (2) includes an outer blade (9). When cutting the edge of the metal can (28), the inner blade (15) is arranged on the inner side of the cutting edge, and the outer blade (9) is arranged on the outer side of the cutting edge; the cutting edge of the outer blade (9) is axially offset from the cutting edge of the inner blade (15), and the radial movement and rotation of the inner blade (15) form a cutting force with the outer blade (9) to cut the edge of the metal can (28); The inner knife drive assembly (4) and the cam assembly (3) are driven to rotate in the same direction around the axis (26) of the second assembly cavity (10), and when the can mouth of a single metal can (28) is cut, 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 metal cans according to claim 1, characterized in that: The outer blade assembly (2) includes a blade holder plate (7), which is axially spaced and slidably disposed at the front end of the blade holder assembly (1) along the first assembly cavity (6); the blade 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 disposed with the first assembly cavity (6), and the outer blade (9) is formed at the bottom edge of the circular through hole (8).

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

4. The can mouth trimming device for metal cans according to claim 1, characterized in that: The inner knife drive assembly (4) includes a slide (12) located at the front end and a slide plate (13) fixed at the front end of the slide (12); the slide 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); The inner blade assembly (5) is radially floating and mounted between the slide groove (12) and the slide plate (13) of the inner blade drive assembly (4); the inner blade assembly (5) also includes a cam follower (16) and a follower bearing (17) radially symmetrically arranged on both sides of the inner blade (15); the inner blade (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 blade drive assembly (4); the cam follower (16) and the follower bearing (17) extend out of both sides of the slide groove (12) respectively and roll against the circumferential surface of the second assembly cavity (10).

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

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

7. The can mouth trimming device for metal cans according to claim 1, characterized in that: 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); a second gear (21) is coaxially fixed at the rear end of the inner blade drive assembly (4) as the driven part of the inner blade drive assembly (4).

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

9. The can mouth trimming device for metal cans according to claim 4, characterized in that: It also includes a spring (18), one end of which acts on the side of the inner blade 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 circumferential surface of the second assembly cavity (10).

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

11. A can-mouth trimming process for metal cans, characterized in that: This is achieved by the can-mouth trimming device for metal cans according to any one of claims 1 to 10, wherein the trimming process includes: Step 1: Place the metal can (28) to be cut into the blade holder plate (7) of the outer blade assembly (2) for positioning; at this time, the radial distance between the inner blade (15) and the outer blade (9) is greater than the wall thickness of the metal can (28); Step 2: Drive the inner blade drive assembly (4) to rotate, which in turn drives the inner blade assembly (5) to rotate together. When the inner blade assembly (5) rotates to the point where the follower bearing (17) abuts against the cam surface section (11) in the cam assembly (3), the inner blade assembly (5) moves radially in the opposite direction to the abutment of the follower bearing (17), which in turn drives the inner blade (15) to move radially toward the inner side of the metal can (28) cutting edge, and together with the outer blade (9) on the outer side of the cutting edge, forms a cutting force to cut the can mouth of the metal can (28). During the cutting process, the inner blade assembly (5) and the cam assembly (3) rotate in the same direction. By rotating the two a set number of times, the inner blade assembly (5) and the cam surface segment (11) of the cam assembly (3) form a cumulative 360° fit, thereby achieving the cutting of one 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 edge trimming is completed, the drive blade plate (7) is driven away from the blade assembly (1) along the axial direction, thereby exposing the scrap ring (27) cut from the mouth of the metal can (28), and the scrap ring (27) is removed by high-pressure air blowing, and then the can is removed to complete the edge trimming of the mouth; In this process, the inner knife (15) moves radially from inside the can to outside the can, piercing the can and rotating at the same time to achieve the outward flipping of the can opening.

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