Wafer slitting device based on semiconductor processing

Abstract

The invention relates to the technical field of wafer processing, in particular to a wafer slitting device based on semiconductor processing, which comprises an operation table, a notch is formed in the upper surface of the operation table, an automatic feeding mechanism is mounted at the position, corresponding to the notch, in the operation table, and a mounting plate is fixed at the rear end of the operation table. The front end of the mounting plate is slidably connected with a lifter, and a slitting assembly is mounted at the bottom of the lifter. The automatic feeding mechanism drives the wafers to form stable and continuous feeding, continuous operation of workers is not needed, the overall feeding effect is stable, accidents possibly caused by manual feeding are avoided, the wafers are positioned and centered in cooperation with the positioning assembly, the wafers are prevented from deviating or falling off, and the production efficiency is improved. And finally, the distance between the cutting knives is adjusted through the slitting assembly, and therefore the cutting requirements of different wafers are met.

Description

Technical Field

[0001] The present invention relates to the technical field of wafer processing, and particularly to a wafer slitting device based on semiconductor processing. Background Art

[0002] A wafer refers to a silicon wafer used to fabricate silicon semiconductor circuits. Its raw material is silicon. High-purity polysilicon is dissolved and doped with a silicon crystal seed, and then slowly pulled out to form a cylindrical single-crystalline silicon. After the silicon ingot is ground, polished, and sliced, a silicon wafer is formed, that is, a wafer. The main processing methods of wafers are sheet processing and batch processing, that is, processing 1 wafer or multiple wafers simultaneously. As the semiconductor feature size becomes smaller and the processing and measurement equipment becomes more advanced, new data characteristics have emerged in wafer processing. During the production process, a dicing saw is required to cut the wafer to facilitate the subsequent production and manufacturing of components; For example, a wafer cutting device with the publication number CN215414481A in the prior art. This device uses a fixing mechanism to firmly install the cutting mechanism and the dicing saw, and is convenient for subsequent disassembly and maintenance, making the operation more convenient. The cleaning mechanism is beneficial for heat dissipation and cleaning during cutting, and collects and stores some debris. The locking mechanism facilitates the cleaning and recycling of the cleaning mechanism. The placement mechanism is beneficial for firmly placing the wafer and preventing moisture from being sucked into the vacuum pump and causing damage. However, during the cutting process, it is impossible to maintain the overall continuity and automation of the cutting work, and manual assistance is required for loading, which is rather inconvenient. Moreover, it is difficult to adjust the distance between the cutting blades according to the situation during the cutting process, and the applicability is relatively low; In view of the above technical defects, a solution is proposed herein. Summary of the Invention

[0003] To overcome the above-mentioned defects of the prior art, the present invention provides a wafer slitting device based on semiconductor processing, which has a continuous and automatic feeding effect on the wafer through an automatic feeding mechanism, without excessive manual intervention. At the same time, the distance between the cutting blades is adjusted by using a slitting component to adapt to more slitting requirements, so as to solve the problems raised in the above background art.

[0004] To achieve the above object, the present invention adopts the following technical scheme: A wafer slitting device based on semiconductor processing, including an operating table. A notch is opened on the upper surface of the operating table, and an automatic feeding mechanism is installed inside the operating table corresponding to the position of the notch. An installation plate is fixed at the rear end of the operating table, a lifter is slidably connected to the front end of the installation plate, and a slitting component is installed at the bottom of the lifter.

[0005] Further, the automatic feeding mechanism includes a turntable rotatably connected to the inside of the operating table. A number of fixing blocks are equidistantly fixed on the outer layer of the turntable. A number of vacuum suction cups are equidistantly fixed on the upper surface of the fixing blocks. A ratchet is fixed at the front end of the turntable. One side of the ratchet is provided with a rotating block rotatably connected to the inside of the operating table. One end of the rotating block is fixed with a dial rod, and the front end of the rotating block passes through and extends to the outside of the operating table and is fixed with a first motor.

[0006] Further, a transmission track is arranged at the position below the lead screw inside the operating table. A number of positioning components are equidistantly installed on the surface of the transmission track. Two rotating rollers are symmetrically and rotatably connected to both sides inside the transmission track. The front ends of the rotating rollers and the ratchet both pass through and extend to the outside of the operating table and are fixed with synchronous wheels. Each adjacent pair of synchronous wheels is rotationally connected by a synchronous belt.

[0007] Further, the positioning component includes fixing seats equidistantly fixed on the surface of the transmission track. Two guiding grooves are symmetrically opened on both sides inside the fixing seat. A guiding slide bar is fixed inside the guiding groove. A guiding slider is sleeved on the outer layer of the guiding slide bar. A spring sleeved on the outer layer of the guiding slide bar is fixed on one side of the guiding slider. Two connecting rods are symmetrically and rotatably connected to the front and rear ends of the guiding slider. The tops of the four connecting rods are jointly rotatably connected with a lifting block.

[0008] Further, two gears are symmetrically and rotatably connected to both sides inside the fixing seat. A first toothed plate and a second toothed plate are respectively meshed and connected to the upper and lower ends of the gear. The second toothed plate is fixed to the upper surface of the guiding slider. The top end of the first toothed plate passes through and extends to the outside of the fixing seat and is fixed with a clamping plate. A slot is opened on the upper surface of the fixing seat corresponding to the connection position between the clamping plate and the fixing seat.

[0009] Further, the slitting component includes a mounting frame fixed to the bottom of the elevator. A sleeve is rotatably connected inside the mounting frame. One side of the sleeve passes through and extends to the outside of the mounting frame and is fixed with a third motor. A rotating shaft is rotatably connected inside the sleeve. One side of the rotating shaft passes through the sleeve and extends to the outside of the mounting frame and is fixed with a second motor.

[0010] Further, a number of cutting knives are equidistantly sleeved on the outer layer of the sleeve. The middle cutting knife is fixedly connected to the sleeve. The cutting knives on both sides are slidably connected to the sleeve. A lead screw is arranged at the position of the cutting knife corresponding to the rotating shaft. The thread directions of the lead screws on both sides are opposite.

[0011] Further, a nut sleeve is sleeved on the outer layer of the lead screw. The lead screw pitch difference between the nut sleeves on the same side is one time. Two connecting rods are symmetrically fixed to the front and rear ends of the nut sleeve. One end of the connecting rod passes through and extends to the outside of the sleeve and is fixed to the cutting knife. A through slot is opened on the outer layer of the sleeve corresponding to the position of the cutting knife.

[0012] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows: 1. In the present invention, a continuous feeding effect is formed by the automatic feeding mechanism. The first motor cooperates with the ratchet and the rotating block to drive the turntable to move intermittently, and at the same time, the synchronous pulley is used to synchronously drive the transmission track to move intermittently, so as to steadily carry out continuous feeding of the wafer. There is no need for continuous operation by the staff, and the overall feeding effect is stable, avoiding accidents that may be caused by manual feeding. 2. In the present invention, a positioning component is installed on the transmission track. During the feeding process, only need to place the wafer on the upper surface of the fixing seat. The self-weight of the wafer presses the lifting block to descend, thereby driving the guiding slider to move. The movement of the guiding slider drives the second toothed plate to move, and the gear cooperates with the first toothed plate to drive the two clamping plates to move towards the center position, so as to position and center the wafer, avoiding the wafer from shifting or falling, and facilitating the subsequent vacuum chuck to center and adsorb the wafer.

[0013] 3. In the present invention, a slitting component is provided. The second motor drives the rotating shaft to rotate, and the different pitches between the lead screws drive the cutting knives to move synchronously and keep the distance between them the same, so as to meet the slitting requirements of different wafers, thereby improving the overall slitting adaptability.

[0014] In summary, the present invention drives the wafer to form stable and continuous feeding through the automatic feeding mechanism, without the need for continuous operation by the staff, and the overall feeding effect is stable, avoiding accidents that may be caused by manual feeding. The positioning component is used to position and center the wafer, avoiding the wafer from shifting or falling, and facilitating the subsequent vacuum chuck to center and adsorb the wafer. Finally, the slitting component is used to adjust the distance between the cutting knives, so as to adapt to the cutting requirements of different wafers. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is the overall structural schematic diagram of the present invention; Figure 2 is the structural schematic diagram of the automatic feeding mechanism of the present invention; Figure 3 is the structural schematic diagram of the fixing seat of the present invention; Figure 4 is the structural schematic diagram of the positioning component of the present invention; Figure 5 is the internal structural schematic diagram of the fixing seat of the present invention; Figure 6 is the structural schematic diagram of the mounting bracket of the present invention; Figure 7 is the combined view of the rotating shaft and the cutting knife of the present invention.

[0016] Reference numerals: 1, operating table; 2, first motor; 3, automatic feeding mechanism; 4, slitting assembly; 5, lift; 6, mounting plate; 7, notch; 8, rotating block; 9, turntable; 10, fixed block; 11, vacuum chuck; 12, lever; 13, ratchet; 14, positioning assembly; 15, synchronous belt; 16, conveyor track; 17, rotating roller; 18, synchronous pulley; 19, lead screw; 20, clamping plate; 21, fixed seat; 22, slotted opening; 23, lifting block; 24, first toothed plate; 25, gear; 26, connecting rod; 27, second toothed plate; 28, guiding slide bar; 29, guiding slider; 30, spring; 31, guiding groove; 32, second motor; 33, mounting bracket; 34, sleeve; 35, cutting knife; 36, through slot; 37, third motor; 38, threaded sleeve; 39, rotating shaft; 40, connecting rod. Detailed implementation mode

[0017] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the protection scope of the present invention. Embodiment

[0018] In order to solve the problem that in the prior art, during the cutting process of a wafer cutting device, the continuity and automation of the overall cutting work cannot be maintained, manual assistance is required for feeding, which is rather inconvenient.

[0019] As Figure 1-2 shown, a wafer slitting device based on semiconductor processing includes an operating table 1. A notch 7 is opened on the upper surface of the operating table 1, and an automatic feeding mechanism 3 is installed inside the operating table 1 corresponding to the position of the notch 7. The automatic feeding mechanism 3 includes a turntable 9 rotatably connected inside the operating table 1. A plurality of fixed blocks 10 are equidistantly fixed on the outer layer of the turntable 9. A plurality of vacuum chucks 11 are equidistantly fixed on the upper surface of the fixed blocks 10. A ratchet 13 is fixed at the front end of the turntable 9. A rotating block 8 rotatably connected inside the operating table 1 is arranged on one side of the ratchet 13. A lever 12 is fixed at one end of the rotating block 8, and the front end of the rotating block 8 penetrates and extends outside the operating table 1 and is fixed with a first motor 2; Inside the operating table 1, a transmission track 16 is arranged at a position corresponding to the lower part of the lead screw 19. A number of positioning components 14 are equidistantly installed on the surface of the transmission track 16. On both sides inside the transmission track 16, two rotating rollers 17 are symmetrically and rotatably connected. By rotating the rotating rollers 17, the transmission track 16 is driven to rotate, thereby driving the positioning components 14 to move. The front ends of the rotating rollers 17 and the ratchet wheel 13 both penetrate and extend to the outside of the operating table 1 and are fixed with synchronous wheels 18. Each adjacent pair of synchronous wheels 18 is rotationally connected by a synchronous belt 15.

[0020] When performing wafer slicing, the wafer is placed inside the positioning component 14 to position the wafer. The first motor 2 is started to drive the rotating block 8 to rotate. The rotating block 8 rotates and cooperates with the lever 12 and the ratchet wheel 13 to drive the turntable 9 to rotate intermittently. At the same time, during the intermittent rotation of the ratchet wheel 13, the transmission track 16 is driven to rotate intermittently through the synchronous wheel 18 and the synchronous belt 15. The movement of the transmission track 16 drives the positioning components 14 to move intermittently. When the positioning component 14 moves to the position of the notch 7, the vacuum chuck 11 is exactly located on the upper surface of the positioning component 14. The vacuum chuck 11 adsorbs the wafer and continues to rotate to the position of the notch 7, forming a cyclic feeding effect, avoiding excessive manual intervention, facilitating continuous processing, and having higher automation. Embodiment

[0021] This embodiment aims at the problem that in the existing wafer cutting device during the cutting process, it is impossible to maintain the continuity and automation of the overall cutting work, and manual assistance is required for feeding, which is rather inconvenient.

[0022] As Figures 3-5 shown, the embodiment is a wafer slicing device based on semiconductor processing. The positioning component 14 further includes fixing seats 21 that are equidistantly fixed on the surface of the transmission track 16. On both sides inside the fixing seats 21, two guiding grooves 31 are symmetrically opened. A guiding slide bar 28 is fixed inside the guiding grooves 31. A guiding slider 29 is sleeved on the outer layer of the guiding slide bar 28. One side of the guiding slider 29 is fixed with a spring 30 sleeved on the outer layer of the guiding slide bar 28 to form a reset effect by using the spring 30. The front and rear ends of the guiding slider 29 are symmetrically and rotatably connected with two connecting rods 26. The tops of the four connecting rods 26 are jointly and rotatably connected with a lifting block 23. The movement of the clamping plate 20 is controlled by the lifting of the lifting block 23; On both sides inside the fixing seats 21, two gears 25 are symmetrically and rotatably connected. The upper and lower ends of the gears 25 are respectively meshed with a first toothed plate 24 and a second toothed plate 27. The second toothed plate 27 is fixed to the upper surface of the guiding slider 29. The top of the first toothed plate 24 penetrates and extends to the outside of the fixing seat 21 and is fixed with a clamping plate 20. A slot 22 is opened on the upper surface of the fixing seat 21 corresponding to the connection between the clamping plate 20 and the fixing seat 21.

[0023] During the feeding process, the wafer is placed on the upper surface of the fixing base 21. The lifting block 23 descends under the weight of the wafer. During the descending process, the guiding slider 29 is driven to move. The movement of the guiding slider 29 drives the movement of the second toothed plate 27. During the movement of the second toothed plate 27, the gear 25 is driven to rotate. Subsequently, the rotation of the gear 25 drives the movement of the first toothed plate 24. The movement of the first toothed plate 24 drives the clamping plate 20 to move towards the center position of the fixing base 21, thereby centering and positioning the wafer to avoid deviation and dropping during the movement process. Embodiment

[0024] This embodiment aims at the problem that in the existing wafer cutting device, it is difficult to adjust the distance between the cutting knives according to the situation during the cutting process, and the applicability is relatively low.

[0025] As Figures 6-7 shown, the embodiment is a wafer slitting device based on semiconductor processing. There is also a mounting plate 6 fixed to the rear end of the operating table 1. The front end of the mounting plate 6 is slidably connected with a lifter 5. The bottom of the lifter 5 is provided with a slitting assembly 4. The slitting assembly 4 includes a mounting frame 33 fixed to the bottom of the lifter 5. A sleeve 34 is rotatably connected inside the mounting frame 33. One side of the sleeve 34 penetrates and extends outside the mounting frame 33 and is fixed with a third motor 37. And a rotating shaft 39 is rotatably connected inside the sleeve 34. One side of the rotating shaft 39 penetrates the sleeve 34 and extends outside the mounting frame 33 and is fixed with a second motor 32; A number of cutting knives 35 are equidistantly sleeved on the outer layer of the sleeve 34. The middle cutting knife 35 is fixedly connected with the sleeve 34. The cutting knives 35 on both sides are slidably connected with the sleeve 34. A lead screw 19 is arranged at the position corresponding to the cutting knife 35 on the rotating shaft 39. The thread directions of the lead screws 19 on both sides are opposite. A nut 38 is sleeved on the outer layer of the lead screw 19. The lead difference between the nuts 38 on the same side is one time. Through the lead difference design, it is ensured that the distances between the cutting knives 35 after movement are the same. Two connecting rods 40 are symmetrically fixed at the front and rear ends of the nut 38. One end of the connecting rod 40 penetrates and extends outside the sleeve 34 and is fixed with the cutting knife 35. Through grooves 36 are opened at the positions corresponding to the cutting knives 35 on the outer layer of the sleeve 34.

[0026] When the wafer moves to the position of the notch 7, the slitting assembly 4 is driven by the elevator 5 to move to a proper position. Then, the second motor 32 is started to drive the rotating shaft 39 to rotate. During the rotation of the rotating shaft 39, the cutting knives 35 on both sides are driven to move to both sides in cooperation with the lead screw 19 and the nut sleeve 38. During the movement, since the lead difference of the adjacent nut sleeves 38 is one time, for example, the lead of the leftmost nut sleeve is 2p and the lead of the second left nut sleeve is p. When moving, the moving distances of the two nut sleeves are as follows: the left 1: ΔL1 = 2p·n, the left 2: ΔL2 = p·n. The initial position of the left 1 nut sleeve is -2d, and the initial position of the left 2 nut sleeve is -d. Then when moving, the distance between them is (−d−pn)−(−2d−2pn)=d+pn, that is, the distance is always kept as d+pn. Thus, the distance between the cutting knives 35 is adjusted to meet different slitting requirements and improve the overall applicable range. After the adjustment is completed, the third motor 37 is started to drive the sleeve 34 and the cutting knives 35 to rotate at a high speed to slit the wafer.

[0027] The working process and principle of the present invention: Step 1: When slitting the wafer, the wafer is placed inside the positioning assembly 14 to position the wafer. The first motor 2 is started to drive the rotating block 8 to rotate. The rotation of the rotating block 8 cooperates with the dial rod 12 and the ratchet 13 to drive the turntable 9 to rotate intermittently. At the same time, during the intermittent rotation of the ratchet 13, the transmission track 16 is driven to rotate intermittently through the synchronous pulley 18 and the synchronous belt 15. The movement of the transmission track 16 drives the positioning assembly 14 to move intermittently. When the positioning assembly 14 moves to the position of the notch 7, the vacuum chuck 11 is exactly located on the upper surface of the positioning assembly 14. The vacuum chuck 11 adsorbs the wafer and continuously rotates to the position of the notch 7, forming a cyclic feeding effect, avoiding excessive manual intervention, facilitating continuous processing, and having higher automation. Step 2: During the feeding process, the wafer is placed on the upper surface of the fixed seat 21. The lifting block 23 descends due to the self-weight of the wafer. During the descent, the guiding slider 29 is driven to move. The movement of the guiding slider 29 drives the second toothed plate 27 to move. During the movement of the second toothed plate 27, the gear 25 is driven to rotate. Subsequently, the first toothed plate 24 is driven to move by the rotation of the gear 25. The movement of the first toothed plate 24 drives the clamping plate 20 to move towards the center position of the fixed seat 21, thereby centering and positioning the wafer to avoid deviation and dropping during the movement. Step 3: When the wafer moves to the notch 7 position, drive the slitting assembly 4 to move to a suitable position through the elevator 5. Start the second motor 32 to drive the rotating shaft 39 to rotate. During the rotation of the rotating shaft 39, cooperate with the lead screw 19 and the nut sleeve 38 to drive the cutting knives 35 on both sides to move towards both sides. During the movement, due to the lead difference between adjacent nut sleeves 38 being one time, for example, the lead of the leftmost nut sleeve is 2p, and the lead of the second left nut sleeve is p. When moving, the moving distances of the two nut sleeves are: Left 1: ΔL1 = 2p·n, Left 2: ΔL2 = p·n. The initial position of the left 1 nut sleeve is -2d, and the initial position of the left 2 nut sleeve is -d. Then when moving, the distance between them is (−d−pn)−(−2d−2pn)=d + pn, that is, the distance is always maintained at d + pn. Thus, the distance between the cutting knives 35 is adjusted to meet different slitting requirements, improving the overall scope of application. After the adjustment is completed, start the third motor 37 to drive the sleeve 34 and the cutting knives 35 to rotate at high speed to slit the wafer. In summary, use the first motor 2 as the power source to drive the automatic feeding mechanism 3 to operate, thereby driving the wafer to form an orderly and continuous feeding effect, and cooperate with the positioning assembly 14 to ensure the stability and safety of the wafer during the movement, avoiding accidental dropping or deviation. Finally, cooperate with the slitting assembly 4 to slit the wafer, and during the cutting process, the distance between the cutting knives 35 can be adjusted according to the slitting requirements of the wafer to meet more slitting requirements.

[0028] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A wafer slitting device based on semiconductor processing, comprising an operating table (1), characterized in that: The upper surface of the operating table (1) is provided with a notch (7), and an automatic feeding mechanism (3) is installed at a position inside the operating table (1) corresponding to the notch (7). A mounting plate (6) is fixed to the rear end of the operating table (1), and a lift (5) is slidably connected to the front end of the mounting plate (6). A slitting assembly (4) is installed at the bottom of the lift (5).

2. The semiconductor processing-based wafer slitting device according to claim 1, characterized in that: The automatic feeding mechanism (3) comprises a turntable (9) rotatably connected to the inside of the operating table (1), a plurality of fixed blocks (10) are equidistantly fixed to the outer layer of the turntable (9), a plurality of vacuum suction cups (11) are equidistantly fixed to the upper surface of the fixed block (10), a ratchet (13) is fixed to the front end of the turntable (9), a rotating block (8) rotatably connected to the inside of the operating table (1) is provided on one side of the ratchet (13), a lever (12) is fixed to one end of the rotating block (8), and a first motor (2) is fixed to the front end of the rotating block (8) which passes through and extends to the outside of the operating table (1).

3. The semiconductor processing-based wafer slitting device according to claim 2, characterized in that: A transmission crawler (16) is arranged at a position below the screw rod (19) inside the operating table (1), and a plurality of positioning components (14) are equidistantly installed on the surface of the transmission crawler (16). Two rotating rollers (17) are symmetrically rotatably connected on both sides of the transmission crawler (16). The front ends of the rotating rollers (17) and the ratchet (13) penetrate and extend to the outside of the operating table (1), where a synchronous wheel (18) is fixed. Each adjacent synchronous wheel (18) is rotationally connected via a synchronous belt (15).

4. The semiconductor processing-based wafer slitting device according to claim 3, characterized in that: The positioning assembly (14) comprises a fixed seat (21) fixed to the surface of the transmission crawler (16) at equal intervals, two guide grooves (31) are symmetrically provided on both sides of the interior of the fixed seat (21), a guide slide bar (28) is fixed inside the guide groove (31), the outer layer of the guide slide bar (28) is sleeved with a guide slider (29), one side of the guide slider (29) is fixed with a spring (30) sleeved with the outer layer of the guide slide bar (28), and the front and rear ends of the guide slider (29) are symmetrically rotatably connected to two connecting rods (26), and the top ends of the four connecting rods (26) are rotatably connected to a lifting block (23).

5. The semiconductor processing-based wafer slitting device according to claim 4, characterized in that: Two gears (25) are symmetrically rotatably connected to the inner sides of the fixed seat (21); the upper and lower ends of the gear (25) are respectively meshed with a first tooth plate (24) and a second tooth plate (27); the second tooth plate (27) is fixed to the upper surface of the guide slider (29); the top end of the first tooth plate (24) passes through and extends to the outside of the fixed seat (21) where a clamping plate (20) is fixed; and a groove (22) is provided on the upper surface of the fixed seat (21) corresponding to the connection between the clamping plate (20) and the fixed seat (21).

6. The semiconductor processing-based wafer slitting device according to claim 1, characterized in that: The slitting assembly (4) comprises a mounting frame (33) fixed to the bottom of the elevator (5), a sleeve (34) being rotatably connected inside the mounting frame (33), one side of the sleeve (34) passing through and extending to the outside of the mounting frame (33) where a third motor (37) is fixed, and a rotating shaft (39) is rotatably connected inside the sleeve (34), one side of the rotating shaft (39) passing through the sleeve (34) and extending to the outside of the mounting frame (33) where a second motor (32) is fixed.

7. The semiconductor processing-based wafer slitting device according to claim 6, characterized in that: The outer layer of the sleeve (34) is equidistantly sleeved with a plurality of cutting knives (35); the middle cutting knives (35) are fixedly connected to the sleeve (34); the cutting knives (35) on both sides are slidably connected to the sleeve (34); a screw rod (19) is arranged at a position of the rotating shaft (39) corresponding to the cutting knives (35); and the screw threads of the screw rods (19) on both sides are in opposite directions.

8. The semiconductor processing-based wafer slitting device according to claim 7, characterized in that: The outer layer of the screw rod (19) is sleeved with a screw sleeve (38), and the lead difference between the screw sleeves (38) on the same side is one time. Two connecting rods (40) are symmetrically fixed at the front and rear ends of the screw sleeve (38), and one end of the connecting rod (40) penetrates and extends to the outside of the sleeve (34) to be fixed to the cutting knife (35). The outer layer of the sleeve (34) is provided with a through groove (36) at the position corresponding to the cutting knife (35).

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