Battery cell pole piece circular knife slitting dust removal device

Abstract

The utility model relates to the technical field of pole piece slitting, and discloses a battery cell pole piece circular knife slitting dust removal device which comprises a dust removal cover, a first dust suction pipe, a second dust suction pipe and a circular knife cleaning mechanism, an annular cutting cavity is formed in the dust removal cover, and a circular knife is sleeved on a roller shaft and arranged in the middle of the annular cutting cavity. A cutting opening is formed in the bottom of the annular cutting cavity, and the outer edge of the bottom end of the circular knife penetrates through the cutting opening and extends out of the dust hood. Part of dust and foreign matter are thrown to the dust suction port through centrifugal force of the circular knife, the dust and the foreign matter are cleaned by means of suction force of the first dust suction pipe and the second dust suction pipe, and the dust and the foreign matter remaining on the circular knife are wiped and cleaned when passing through the circular knife cleaning mechanism, so that cleaning of the dust and the foreign matter for pole piece slitting is achieved, and working efficiency is improved. And dust and foreign matter residues on the pole piece in the slitting process are reduced, and the production qualification rate of the battery cell is improved, so that the energy and the safety of the battery cell are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of pole piece cutting, in particular to a circular knife cutting and dust removal device for electric core pole pieces. Background Art

[0002] Battery production is divided into cell manufacturing and PACK assembly. Cell manufacturing is an important link inside the cell, and the preliminary preparation work is very important, because different materials need to be mixed, dried, coated, rolled, slid and other tedious processes according to the process ratio. The important factors affecting each process are dust and foreign matter. Once the dust or foreign matter in the environment exceeds the standard, it will seriously affect the manufacturing standards of the cell. No matter how strict and accurate it is, it will eventually lead to cell short circuit, reduced capacity, and even fire and explosion and other serious problems. Therefore, in the manufacture of battery cells, it is necessary to strictly control the dust and foreign matter in each process, especially the cutter of roller pressing and slitting, and the dust generated during the rotating friction. It is necessary to take corresponding tooling and process measures to reduce the presence of dust and foreign matter, thereby improving the energy and safety of the battery cell. Utility Model Content

[0003] In order to solve the technical problems existing in the background technology, the utility model provides a device for separating and removing dust from a circular knife of a battery cell pole piece.

[0004] The utility model discloses a dust removing device for circular knife cutting of battery cell pole pieces, which is mainly used for cleaning dust and foreign matters in the process of pole piece cutting, and specifically comprises a dust removal hood, a first dust suction pipe, a second dust suction pipe and a circular knife cleaning mechanism, wherein the interior of the dust removal hood is provided with an annular cutting cavity, the circular knife is mounted on a roller shaft and centrally arranged in the annular cutting cavity, the bottom of the annular cutting cavity is provided with a cutting opening, the outer edge of the bottom end of the circular knife passes through the cutting opening and extends to the outside of the dust removal hood, the first dust suction pipe and the second dust suction pipe are respectively mounted at two ends of the dust removal hood and are communicated with the inner cavity of the dust removal hood, the circular knife cleaning mechanism is mounted on the dust removal hood, and the dust and foreign matters adhered to the circular knife in the dust removal hood are cleaned by the circular knife cleaning mechanism.

[0005] As a further optimized solution of the utility model, the dust removal hood includes a first hood body, a second hood body, and a third hood body. The second hood body and the third hood body are respectively installed at both ends of the first hood body to form an annular cutting cavity. The opening of the second hood body and the opening of the third hood body are relatively arranged to form a cutting opening. The second hood body and the third hood body are respectively connected to the first dust suction pipe and the second dust suction pipe. The first hood body is provided with a third dust suction pipe connected to its inner cavity.

[0006] As a further optimized solution of the utility model, the circular knife cleaning mechanism includes a mounting frame and a felt pad. A mounting opening adapted to the mounting frame is opened on the dust hood, the mounting opening is communicated with the annular cutting chamber, the mounting frame can be removably installed in the mounting opening, the felt pad is installed at one end of the mounting frame located inside the dust hood, and is used to wipe dust and foreign matter adhered to the blade of the circular knife.

[0007] As a further optimized solution of the utility model, one end of the mounting frame located inside the dust cover has a groove adapted to the felt pad, the felt pad is snap-fitted and installed in the groove, a wiping groove is provided on the side of the felt pad close to the circular knife, the outer edge of the blade of the circular knife is plugged into the wiping groove, and the circular knife is driven to rotate by the roller shaft, so that the outer edge of the blade of the circular knife rubs against the inner wall of the wiping groove to remove dust and foreign matter adhering to the blade.

[0008] As a further optimized solution of the utility model, the circular knife cleaning mechanism also includes a liquid injection tube, which is installed at one end of the mounting frame located outside the dust cover, and one end of the liquid injection tube extends downward into the mounting frame and contacts the felt pad.

[0009] As a further optimized solution of the utility model, it also includes an auxiliary dust suction mechanism. The pole piece is cut into multiple pole piece strips by a circular knife. The multiple pole piece strips are guided by guide rollers and tilted downward at different angles. There are multiple auxiliary dust suction mechanisms and they are respectively arranged on the upper surfaces of the multiple pole piece strips.

[0010] As a further optimized solution of the utility model, the auxiliary dust suction mechanism includes a dust suction hood, a fourth dust suction pipe and a bracket. The bottom opening of the dust suction hood is opposite to the upper surface of the pole strip and has a gap. The fourth dust suction pipe is installed at the top opening of the dust suction hood, and the dust suction hood is installed on the frame through the bracket.

[0011] As a further optimized solution of the utility model, the device also includes a forked pipe, a dust blowing pipe, a connecting pipe, and an air intake valve. The forked pipe is installed on the frame through fasteners and is located on the side of the pole piece that has not been cut. The top of the forked pipe has an air inlet, and the air inlet is connected to the air intake valve through a connecting pipe. Both sides of the bottom end of the forked pipe have forked openings, and each forked opening is equipped with a dust blowing pipe. The dust blowing pipes are symmetrically distributed on both sides of the dust removal hood, and the other end of the dust blowing pipe extends downward to the cutting line of the pole piece.

[0012] As a further optimized solution of the utility model, one end of the dust blowing tube away from the bifurcated tube is bent toward the circular knife, and the opening of the bent section is opposite to the blade of the circular knife.

[0013] The battery cell pole piece circular knife separation and dust removal device proposed in the utility model has the following beneficial effects:

[0014] The utility model wraps the periphery of the circular knife with a dust removal cover, utilizes the roller to drive the circular knife to rotate, thereby drives the dust and foreign matter to rotate, relies on the centrifugal force of the circular knife to throw part of the dust and foreign matter to the dust suction port, relies on the suction force of the first dust suction pipe and the second dust suction pipe to clean the dust and foreign matter, and the dust and foreign matter remaining on the circular knife are wiped and cleaned when passing through the circular knife cleaning mechanism, thereby realizing the cleaning of the dust and foreign matter of the electrode piece cutting, reducing the dust and foreign matter remaining on the electrode piece during the cutting process, which is beneficial to improving the production qualification rate of the battery cell, thereby improving the energy and safety of the battery cell.

[0015] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will become apparent from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the utility model;

[0017] Figure 2 It is a schematic diagram of the structure of the dust removal cover of the utility model;

[0018] Figure 3 It is a structural schematic diagram of the auxiliary dust removal mechanism of the utility model.

[0019] Description of the drawings: 1. Dust hood; 101. First hood body; 102. Second hood body; 103. Third hood body; 2. First dust suction pipe; 3. Second dust suction pipe; 4. Circular knife cleaning mechanism; 41. Mounting frame; 42. Felt pad; 43. Liquid injection pipe; 5. Circular knife; 6. Roller; 7. Bifurcated pipe; 8. Dust blowing pipe; 9. Connecting pipe; 10. Inlet valve; 11. Third dust suction pipe; 12. Mounting port; 13. Pole piece; 14. Auxiliary dust suction mechanism; 141. Dust hood; 142. Fourth dust suction pipe; 143. Bracket. DETAILED DESCRIPTION

[0020] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar symbols throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0021] It should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0022] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0023] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0025] See also Figure 1-Figure 3, a device for removing dust from a circular knife for cutting a cell pole piece, mainly used for cleaning dust and foreign matter in the process of cutting a pole piece, specifically comprising a dust removal hood 1, a first dust suction pipe 2, a second dust suction pipe 3, and a circular knife cleaning mechanism 4, wherein the interior of the dust removal hood 1 is provided with an annular cutting cavity, a circular knife 5 is sleeved on a roller shaft 6 and centrally arranged in the annular cutting cavity, the bottom of the annular cutting cavity is provided with a cutting opening, the outer edge of the bottom end of the circular knife 5 passes through the cutting opening and extends to the outside of the dust removal hood 1, the first dust suction pipe 2 and the second dust suction pipe 3 are respectively installed at both ends of the dust removal hood 1 and are connected to the inner cavity of the dust removal hood 1, the circular knife cleaning mechanism 4 is installed on the dust removal hood 1, and the dust and foreign matter adhered to the circular knife 5 in the dust removal hood 1 are cleaned by the circular knife cleaning mechanism 4;

[0026] Furthermore, the roller 6 coincides with the axis of the annular cutting chamber, while the axes of the first dust suction pipe 2 and the second dust suction pipe 3 coincide with and are perpendicular to the axis of the roller 6, and the tangent line of the circular knife 5 and the axis of the first dust suction pipe 2 are in the same vertical plane. When the roller 6 drives the circular knife 5 to rotate in the annular cutting chamber, the centrifugal force of the rotation of the circular knife 5 can throw part of the dust and foreign matter to the suction ports of the first dust suction pipe 2 and the second dust suction pipe 3, and then the dust and foreign matter are sucked and cleaned by the first dust suction pipe 2 and the second dust suction pipe 3, and the dust and foreign matter remaining on the blade of the circular knife 5 will be cleaned by the circular knife cleaning mechanism 4 when passing through the circular knife cleaning mechanism 4;

[0027] The outer periphery of the circular knife 5 is wrapped by the dust removal cover 1, and the circular knife 5 is driven to rotate by the roller 6, thereby driving the dust and foreign matter to rotate, and relying on the centrifugal force of the circular knife 5, part of the dust and foreign matter are thrown to the dust suction port, and the dust and foreign matter are cleaned by the suction force of the first dust suction pipe 2 and the second dust suction pipe 3, and the dust and foreign matter remaining on the circular knife 5 are wiped and cleaned when passing through the circular knife cleaning mechanism 4, so as to realize the cleaning of the dust and foreign matter of the electrode sheet slitting, reduce the dust and foreign matter residue on the electrode sheet during the slitting process, and help to improve the production qualification rate of the battery cell, thereby improving the energy and safety of the battery cell;

[0028] Specifically, Figure 2 As shown, the dust cover 1 includes a first cover body 101, a second cover body 102, and a third cover body 103. The second cover body 102 and the third cover body 103 are respectively installed at both ends of the first cover body 101 to form an annular cutting cavity. The opening of the second cover body 102 and the opening of the third cover body 103 are arranged opposite to each other to form a cutting opening. The second cover body 102 and the third cover body 103 are respectively connected to the first dust suction pipe 2 and the second dust suction pipe 3. The first cover body 101 is installed with a third dust suction pipe 11 connected to its inner cavity;

[0029] Further, the first cover body 101 is an arc-shaped shell, the first cover body 101 is installed on the frame through a fixing frame, the second cover body 102 is installed on one end of the first cover body 101 through a fastener, and the third cover body 103 is installed on the other end of the air inlet valve 10 through a fastener, thereby forming an annular cutting cavity, and the first dust suction pipe 2, the second dust suction pipe 3 and the third dust suction pipe 11 are all connected to the external negative pressure dust suction equipment;

[0030] Specifically, the circular knife cleaning mechanism 4 includes a mounting frame 41 and a felt pad 42. The dust cover 1 is provided with a mounting opening 12 adapted to the mounting frame 41, the mounting opening 12 is communicated with the annular cutting chamber, the mounting frame 41 is detachably mounted in the mounting opening 12, and the felt pad 42 is mounted on one end of the mounting frame 41 located inside the dust cover 1, and is used to wipe the dust and foreign matter adhered to the blade of the circular knife 5;

[0031] Furthermore, one end of the mounting frame 41 located inside the dust cover 1 has a groove adapted to the felt pad 42, and the felt pad 42 is snap-fitted and installed in the groove. A wiping groove is provided on one side of the felt pad 42 close to the circular knife 5, and the outer edge of the blade of the circular knife 5 is plugged into the wiping groove. The circular knife 5 is driven to rotate by the roller shaft 6, so that the outer edge of the blade of the circular knife 5 rubs against the inner wall of the wiping groove to remove dust and foreign matter adhering to the blade.

[0032] Furthermore, the circular knife cleaning mechanism 4 also includes a liquid injection pipe 43, which is installed at one end of the mounting frame 41 located outside the dust cover 1, and one end of the liquid injection pipe 43 extends downward into the mounting frame 41 and contacts the felt pad 42. The liquid injection pipe 43 is connected to an external liquid supply device, and a coolant is poured into the liquid injection pipe 43 through the liquid supply device, and the coolant is used to soak the felt pad 42, thereby cooling the high-speed rotating circular knife 5. The coolant can be a highly volatile cooling liquid, preferably alcohol.

[0033] It should be noted that as the amount of foreign matter and dust adhering to the felt pad 42 gradually increases, some of the dust and foreign matter may fall downward into the third cover body 103 and be sucked and cleaned by the second dust suction pipe 3. Alternatively, the mounting frame 41 may be removed from the mounting opening 12, and the felt pad 42 may be taken out for manual cleaning or replacement.

[0034] In this embodiment, if Figure 3 As shown, the device also includes an auxiliary dust suction mechanism 14, a plurality of guide rollers are installed on the frame, and the pole piece 13 is arranged between the plurality of guide rollers for guiding and auxiliary traction of the pole piece 13. The pole piece 13 is cut into a plurality of pole piece strips by the circular knife 5, and the plurality of pole piece strips are guided by the guide rollers and tilted downward at different angles. The number of the auxiliary dust suction mechanisms 14 is plural and they are respectively arranged on the upper surfaces of the plurality of pole piece strips.

[0035] Specifically, Figure 3As shown, the pole piece 13 is cut into two pole piece strips by a circular knife 5, and two auxiliary dust suction mechanisms 14 are required to be provided to respectively suction the two pole piece strips;

[0036] Furthermore, the auxiliary dust collection mechanism 14 includes a dust collection hood 141, a fourth dust collection pipe 142 and a bracket 143. The bottom opening of the dust collection hood 141 is opposite to the upper surface of the pole piece strip and has a gap of 1-5 mm. The fourth dust collection pipe 142 is installed at the top opening of the dust collection hood 141. The top opening of the fourth dust collection pipe 142 is connected to the negative pressure port of the dust collection device. The dust collection hood 141 is installed on the frame through the bracket 143, and can absorb and clean the residual dust and foreign matter sliding down the pole piece strip.

[0037] In this embodiment, if Figure 1 and Figure 3 As shown, the device also includes a bifurcated pipe 7, a dust blowing pipe 8, a connecting pipe 9, and an air inlet valve 10. The bifurcated pipe 7 is installed on the frame by fasteners and is located on the side of the pole piece 13 that is not cut. The top of the bifurcated pipe 7 has an air inlet, and the air inlet is connected to the air inlet valve 10 through the connecting pipe 9. Both sides of the bottom of the bifurcated pipe 7 have bifurcated openings, and each bifurcated opening is installed with a dust blowing pipe 8. The dust blowing pipes 8 are symmetrically distributed on both sides of the dust removal cover 1, and the other end of the dust blowing pipe 8 extends downward to the cutting line of the pole piece 13.

[0038] It should be noted that the bifurcated tube 7 may have a plurality of bifurcated openings, depending on actual use requirements;

[0039] Furthermore, one end of the dust blowing pipe 8 away from the bifurcated pipe 7 is bent toward the circular knife 5, and the opening of the bent section is opposite to the blade of the circular knife 5;

[0040] The air inlet valve 10 is connected to an external air supply device. By supplying air to the air inlet valve 10, the gas is ejected downward through the bifurcated pipe 7 and the dust blowing pipe 8, so that the foreign matter and the generated dust at the cutting line are blown to the dust removal cover 1, and then the dust and foreign matter are brought into the annular cutting chamber by the rotating centrifugal force of the circular knife 5;

[0041] Working principle:

[0042] When in use, the circular knife 5 is driven by the roller 6 to rotate clockwise and cut the pole piece 13, and at the same time, the negative pressure dust suction device and the air supply device are started. The air supply device supplies air to the air inlet valve 10, so that the dust blowing pipe 8 discharges air downward, and the foreign matter at the cutting line and the generated dust are blown to the dust removal hood 1, and the circular knife 5 drives the dust and foreign matter to rotate into the annular cutting chamber, and relies on the centrifugal force of the circular knife 5 to throw part of the dust and foreign matter to the dust suction port, and relies on the suction force of the first dust suction pipe 2 and the second dust suction pipe 3 to clean the dust and foreign matter, and the dust and foreign matter remaining on the circular knife 5 are wiped and cleaned by the felt pad 42 when passing through the circular knife cleaning mechanism 4, so as to clean the dust and foreign matter in the pole piece cutting process.

[0043] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes within the technical scope disclosed by the present invention according to the technical scheme and the utility model concept of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A device for separating and removing dust from a battery cell pole piece with a circular knife, characterized in that: The utility model comprises a dust removal hood (1), a first dust suction pipe (2), a second dust suction pipe (3), and a circular knife cleaning mechanism (4); the interior of the dust removal hood (1) is provided with an annular cutting cavity; the circular knife (5) is sleeved on a roller shaft (6) and is centrally arranged in the annular cutting cavity; the bottom of the annular cutting cavity is provided with a cutting opening; the outer edge of the bottom end of the circular knife (5) passes through the cutting opening and extends to the outside of the dust removal hood (1); the first dust suction pipe (2) and the second dust suction pipe (3) are respectively installed at two ends of the dust removal hood (1) and are connected to the inner cavity of the dust removal hood (1); the circular knife cleaning mechanism (4) is installed on the dust removal hood (1); and dust and foreign matter adhered to the circular knife (5) in the dust removal hood (1) are cleaned by the circular knife cleaning mechanism (4).

2. A cell electrode circular knife separation and dust removal device according to claim 1, characterized in that: The dust removal hood (1) comprises a first hood body (101), a second hood body (102), and a third hood body (103); the second hood body (102) and the third hood body (103) are respectively mounted at two ends of the first hood body (101) to form an annular cutting cavity; an opening of the second hood body (102) and an opening of the third hood body (103) are arranged opposite to each other to form a cutting opening; the second hood body (102) and the third hood body (103) are respectively connected to a first dust suction pipe (2) and a second dust suction pipe (3); and a third dust suction pipe (11) connected to its inner cavity is mounted on the first hood body (101).

3. The device for separating and removing dust from a battery cell electrode piece by a circular knife according to claim 1, characterized in that: The circular knife cleaning mechanism (4) comprises a mounting frame (41) and a felt pad (42); a mounting opening (12) adapted to the mounting frame (41) is provided on the dust removal cover (1); the mounting opening (12) is communicated with the annular cutting chamber; the mounting frame (41) is detachably mounted in the mounting opening (12); the felt pad (42) is mounted on one end of the mounting frame (41) located inside the dust removal cover (1) and is used to wipe dust and foreign matter adhered to the blade of the circular knife (5).

4. The device for separating and removing dust from a battery cell pole piece by a circular knife according to claim 3, characterized in that: One end of the mounting frame (41) located inside the dust cover (1) has a groove matched with the felt pad (42), and the felt pad (42) is mounted in the groove in a snap-fit ​​manner. A wiping groove is provided on one side of the felt pad (42) close to the circular knife (5), and the outer edge of the blade of the circular knife (5) is plugged into the wiping groove. The circular knife (5) is driven to rotate by the roller shaft (6), so that the outer edge of the blade of the circular knife (5) rubs against the inner wall of the wiping groove to remove dust and foreign matter adhering to the blade.

5. The device for separating and removing dust from a battery cell pole piece by a circular knife according to claim 3, characterized in that: The circular knife cleaning mechanism (4) also includes a liquid injection pipe (43), which is mounted on one end of the mounting frame (41) located outside the dust removal cover (1), and one end of the liquid injection pipe (43) extends downward into the mounting frame (41) and contacts the felt pad (42).

6. The device for separating and removing dust from a battery cell pole piece by a circular knife according to claim 1, characterized in that: It also includes an auxiliary dust suction mechanism (14); the pole piece (13) is cut into a plurality of pole piece strips by a circular knife (5); the plurality of pole piece strips are guided by guide rollers and tilted downward at different angles; and the number of the auxiliary dust suction mechanisms (14) is plural and they are respectively arranged on the upper surfaces of the plurality of pole piece strips.

7. A cell electrode piece circular knife separation and dust removal device according to claim 6, characterized in that: The auxiliary dust suction mechanism (14) comprises a dust suction hood (141), a fourth dust suction pipe (142) and a bracket (143); the bottom opening of the dust suction hood (141) is opposite to the upper surface of the pole piece strip and has a gap therebetween; the fourth dust suction pipe (142) is installed at the top opening of the dust suction hood (141); and the dust suction hood (141) is installed on the frame via the bracket (143).

8. A cell electrode piece circular knife separation and dust removal device according to any one of claims 1 to 7, characterized in that: It also comprises a bifurcated pipe (7), a dust blowing pipe (8), a connecting pipe (9), and an air intake valve (10); the bifurcated pipe (7) is mounted on the frame by means of a fastener and is located on the uncut side of the pole piece (13); the top end of the bifurcated pipe (7) is provided with an air intake port, and the air intake port is connected to the air intake valve (10) via the connecting pipe (9); both sides of the bottom end of the bifurcated pipe (7) are provided with bifurcated openings, and each bifurcated opening is provided with a dust blowing pipe (8); the dust blowing pipes (8) are symmetrically distributed on both sides of the dust removal cover (1); and the other end of the dust blowing pipe (8) extends downward to the cutting line of the pole piece (13).

9. The device for separating and removing dust from a battery cell pole piece by a circular knife according to claim 8, characterized in that: One end of the dust blowing pipe (8) away from the bifurcated pipe (7) is bent toward the circular knife (5), and the opening of the bent section is opposite to the blade of the circular knife (5).

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