An electric circular saw

Abstract

This invention relates to the field of circular saw technology and discloses a circular saw. The top of the base plate is connected to a power mechanism via a hinge mechanism. The output end of the power mechanism is connected to a saw blade. A negative pressure dust collection assembly, rotating synchronously with the saw blade, is mounted on the output shaft of the power mechanism. A protective cover is installed above the saw blade. A segmented dust collection hood assembly corresponding to the saw blade's cutting area is connected to the negative pressure dust collection assembly. This invention overcomes the bottlenecks of existing technologies from two core dimensions: power utilization and dynamic dust collection structure. It achieves efficient dust collection across the entire cutting depth range without adding extra power, while also possessing the advantages of simple structure, low cost, and high reliability. It exhibits outstanding substantive features and significant progress.

Description

Technical Field

[0001] This invention relates to the field of electric circular saw technology, and particularly to an electric circular saw. Background Technology

[0002] In the existing technology, when using an electric circular saw, if the dust-free chip removal mode is adopted, the dust removal component and a matching vacuum cleaner need to be installed; if the dust removal mode is adopted, the dust removal component needs to be removed. Otherwise, poor dust removal will occur, and the machine performance and user experience will be reduced. The dust removal component is usually a dust removal pipe. For users, the dust removal component must be installed or removed every time the chip removal mode is switched, which is quite cumbersome.

[0003] In a circular saw with quick-switching dust removal mode according to application number CN202410255895.7, the circular saw blade is covered with a protective cover, the protective cover is provided with a dust removal component, the dust removal component is provided with an inlet communicating with a dust outlet, and a first outlet and a second outlet separated from each other; the dust removal component is also provided with a connecting component that can move relative to the dust removal component, the connecting component has a first position for putting the first outlet into a working state and a second position for putting the second outlet into a working state.

[0004] However, in actual use, the traditional fixed dust hood opening covers the entire lower half of the saw blade, but dust is only generated in a very small area where the saw blade contacts the workpiece during actual cutting. Most of the openings are idle, resulting in severe diversion of negative pressure. Especially during shallow cutting, the dust-generating area accounts for only about 1 / 3 of the total opening, and more than 70% of the effective suction power is wasted. The sawdust collection rate is generally insufficient. To compensate for the insufficient suction power, most products are equipped with independent dust collection motors, which increases the weight of the whole machine by 1-2 kg. Long-term operation can easily cause operator fatigue.

[0005] Therefore, the present invention proposes an electric circular saw to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide an electric circular saw to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: an electric circular saw, including a base plate, a power mechanism connected to the top of the base plate via a hinge mechanism, a saw blade being driven to the output end of the power mechanism, a negative pressure dust collection assembly that rotates synchronously with the saw blade being mounted on the output shaft of the power mechanism, a protective cover being installed above the saw blade, and a segmented dust collection cover assembly corresponding to the cutting area of ​​the saw blade being connected to the negative pressure dust collection assembly; The segmented dust hood assembly includes a first dust hood, a second dust hood slidably mounted on the outer wall of the first dust hood, and a third dust hood slidably mounted on the outer wall of the second dust hood. The first, second, and third dust hoods have the same structure and are all arc-shaped guide hoods. The covering angle range of the first dust hood is 0-12°, the covering angle range of the second dust hood is 10-20°, and the covering angle range of the third dust hood is 18-30°.

[0008] Preferably, the hinge mechanism includes a hinge seat fixed on the base plate, the hinge seat is rotatably connected to the protective cover via a hinge shaft, the protective cover is fixedly connected to the power mechanism, and an arc-shaped slide rail is fixedly provided on the surface of the protective cover. A positioning pin that is assembled with the arc-shaped slide rail is fixed on the base plate, and a fastener for locking the arc-shaped slide rail is installed on the positioning pin.

[0009] Preferably, the protective cover is installed on the upper half of the saw blade, the segmented dust collection hood assembly is installed at the bottom of the protective cover, and the bottom plate is provided with a channel for storing the segmented dust collection hood assembly and allowing it to pass through vertically. The protective cover is integrally formed with a dust outlet pipe.

[0010] Preferably, the first, second, and third dust hoods are all provided with negative pressure grooves inside, and the lower inner sidewalls of the first, second, and third dust hoods are all provided with dust guide opening grooves. A guide cone that spatially divides the negative pressure groove is fixed inside the negative pressure groove.

[0011] Preferably, the first dust hood is slidably mounted on the inner wall of the protective cover, and the inner walls of the second and third dust hoods are both fixed with sliding strips. The outer walls of the first and second dust hoods are both provided with sliding grooves that match the sliding strips. The sliding strips are arc-shaped strips, and the sliding grooves are arc-shaped grooves. The central axes of the arc-shaped grooves, the first dust hood, the second dust hood, the third dust hood, and the protective cover are the same.

[0012] Preferably, the segmented vacuum hood assembly further includes a main negative pressure pipe, which is connected to the first vacuum hood via a first negative pressure air pipe, the main negative pressure pipe and the second vacuum hood via a second negative pressure air pipe, and the main negative pressure pipe and the third vacuum hood via a third negative pressure air pipe. A first control valve is installed on the first negative pressure air pipe, a second control valve is installed on the second negative pressure air pipe, and a third control valve is installed on the third negative pressure air pipe. The negative pressure air pipe and the negative pressure groove on each set of vacuum hoods are connected.

[0013] Preferably, the output shaft of the power mechanism is coaxially connected to a drive shaft, the saw blade is fixedly mounted on the outer side wall of the drive shaft, and a protective seat fixed to the power mechanism is sleeved on the outer side of the drive shaft. A sealing ring is fixedly sleeved on the outer side wall of the drive shaft, and the sealing ring and the drive shaft rotate synchronously.

[0014] Preferably, the negative pressure dust collection assembly includes a drive ring fixedly sleeved on the outer wall of the drive shaft, impellers are evenly arranged along the circumferential direction on the outer wall of the drive ring, and a sealing cover covering the outside of the impellers is fixed on the side wall of the protective seat, and the sealing ring is embedded in the sealing cover and the two are rotatably assembled.

[0015] Preferably, the outer wall of the sealing cover is fitted with an arc-shaped exhaust pipe along the tangential direction, and the exhaust pipe and the dust outlet pipe are connected. The main negative pressure pipe is connected to the inside of the sealing cover through a flexible corrugated pipe, and the main negative pressure pipe is fixedly installed on the protective base by a bracket.

[0016] Preferably, a leveling ruler is installed on the base plate, and a handle is installed on the power mechanism.

[0017] The technical effects and advantages of this invention are as follows: This invention addresses the industry pain points of severe dust pollution during electric circular saw operations and the inherent defects of existing dust collection solutions. The core idea is to maximize the use of the electric circular saw's own power source without adding an additional independent dust collection motor. At the same time, through a dynamically adjustable dust collection structure, the negative pressure suction can be precisely matched to the actual dust-generating area at different cutting depths. This fundamentally solves the problem of low efficiency caused by fixed openings and full-area diversion in traditional dust collection systems, and overcomes the problem of efficiency being affected by changes in the distance between the dust collection port and the cutting point due to changes in the opening angle of the protective cover at different cutting depths. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall first-view structure of the present invention; Figure 2 This is a schematic diagram of the overall second-view structure of the present invention; Figure 3 This is a schematic diagram of a partial assembly structure of the present invention; Figure 4 For the present invention Figure 3 First-person view structural diagram of the explosion; Figure 5 For the present invention Figure 3 Schematic diagram of the structure from a second-person perspective of the explosion; Figure 6 This is a schematic diagram of the assembly structure of the negative pressure dust collection component and the segmented dust collection hood component of the present invention; Figure 7 This is a partial structural diagram of the negative pressure dust collection component of the present invention; Figure 8 This is a schematic diagram of the segmented dust collection hood assembly structure of the present invention; Figure 9 This is a schematic diagram of the third dust hood structure of the present invention.

[0019] In the diagram: 10. Base plate; 20. Hinge mechanism; 21. Hinge seat; 22. Hinge shaft; 23. Arc-shaped slide rail; 30. Power mechanism; 31. Drive shaft; 32. Protective seat; 33. Sealing ring; 40. Saw blade; 50. Protective cover; 51. Dust outlet pipe; 60. Negative pressure dust collection assembly; 61. Drive ring; 62. Impeller; 63. Dust collection groove; 64. Sealing cover; 65. Exhaust pipe; 70. Segmented dust collection hood assembly 71. First dust hood; 72. Second dust hood; 73. Third dust hood; 74. First negative pressure air pipe; 75. Second negative pressure air pipe; 76. Third negative pressure air pipe; 77. First control valve; 78. Second control valve; 79. Third control valve; 710. Main negative pressure pipe; 711. Negative pressure groove; 712. Dust guide opening groove; 713. Guide cone; 714. Slide bar; 80. Leveling ruler; 90. Handle. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] like Figures 1 to 7 As shown, this embodiment discloses an electric circular saw, including a base plate 10. The base plate 10 is made of hard alloy sheet metal through stamping to ensure the support stability and structural strength of the electric circular saw during the cutting operation. The top of the base plate 10 is connected to a power mechanism 30 through a hinge mechanism 20. The output end of the power mechanism 30 is connected to a saw blade 40. A negative pressure dust collection component 60, which rotates synchronously with the saw blade 40, is installed on the output shaft of the power mechanism 30. The negative pressure dust collection component 60 can directly utilize the rotational driving force of the power mechanism 30 to generate a negative pressure adsorption effect, without the need for an additional independent dust collection motor. A protective cover 50 is installed above the saw blade 40. The negative pressure dust collection component 60 is connected to a part corresponding to the cutting area of ​​the saw blade 40. The segmented dust hood assembly 70 can adaptively adjust the dust collection coverage according to changes in cutting depth, thus maintaining a highly efficient and stable dust collection effect at different cutting depths. In actual use, by setting the negative pressure dust collection assembly 60 and the output shaft of the power mechanism 30 coaxially, the saw blade 40 and the dust collection mechanism are driven synchronously, which effectively simplifies the overall structure of the electric circular saw, reduces the weight and manufacturing cost of the whole machine, and avoids the increased energy consumption and failure rate caused by an additional motor. The segmented dust collection assembly 70 is arranged directly opposite the cutting area, which can accurately adsorb the sawdust and dust generated during cutting, suppressing the spread of dust from the source and solving the technical problems of poor dust collection effect and pollution of the working environment of traditional electric circular saws.

[0022] Please see Figures 3-9 The segmented dust hood assembly 70 includes a first dust hood 71, a second dust hood 72 slidably mounted on the outer wall of the first dust hood 71, and a third dust hood 73 slidably mounted on the outer wall of the second dust hood 72. The first dust hood 71, the second dust hood 72, and the third dust hood 73 have the same structure and are all arc-shaped guide hoods. It should be noted that the covering angle range of the first dust hood 71 is 0-12°, the covering angle range of the second dust hood 72 is 10-20°, and the covering angle range of the third dust hood 73 is 18-30°. There is an overlapping area between adjacent dust hoods to eliminate blind spots in dust collection.

[0023] Please see Figure 9 The first dust collection hood 71, the second dust collection hood 72, and the third dust collection hood 73 are all provided with negative pressure grooves 711, and the lower inner sidewalls of the first dust collection hood 71, the second dust collection hood 72, and the third dust collection hood 73 are all provided with dust guide opening grooves 712. A guide cone 713 is fixed in the negative pressure groove 711 to divide the negative pressure groove 711 spatially. The guide cone 713 can guide the airflow, so that the negative pressure is evenly distributed and the efficiency of wood chip suction is improved.

[0024] Please see Figure 9 The first dust suction hood 71 is slidably installed on the inner wall of the protective cover 50, and the inner walls of the second dust suction hood 72 and the third dust suction hood 73 are both fixed with sliding strips 714. The outer walls of the first dust suction hood 71 and the second dust suction hood 72 are all provided with sliding grooves that match the sliding strips 714. The sliding strips 714 are arc-shaped strips, and the sliding grooves are arc-shaped grooves. The central axes of the arc-shaped grooves, the first dust suction hood 71, the second dust suction hood 72, the third dust suction hood 73 and the protective cover 50 are the same, ensuring that each dust suction hood is always arranged coaxially with the saw blade 40 during the sliding process.

[0025] In actual use, the first dust hood 71, the second dust hood 72, and the third dust hood 73 form a progressively extending sliding engagement with the slide groove via the slide bar 714. During the process of the electric circular saw cutting into the workpiece, the workpiece surface will sequentially push the third dust hood 73 and the second dust hood 72 to expand outward relative to the first dust hood 71, so that the coverage angle of the segmented dust hood assembly 70 increases synchronously with the cutting depth, realizing dynamic adaptive adjustment of the dust collection range. The guide cone 713 can regulate the negative pressure airflow and avoid suction loss caused by airflow turbulence. The overlapping angle setting between adjacent dust hoods can effectively avoid the occurrence of dust collection dead angles, significantly improving the dust collection stability and collection rate at different cutting depths.

[0026] Please see Figure 3 and Figure 4The hinge mechanism 20 includes a hinge seat 21 fixed on the base plate 10. The hinge seat 21 is rotatably connected to the protective cover 50 via a hinge shaft 22. The protective cover 50 is fixedly connected to the power mechanism 30. An arc-shaped slide rail 23 is fixedly provided on the surface of the protective cover 50. A positioning pin that is assembled with the arc-shaped slide rail 23 is fixed on the base plate 10. Fasteners that lock the arc-shaped slide rail 23 are installed on the positioning pin.

[0027] Please see Figure 3 and Figure 4 The protective cover 50 is installed on the upper half of the saw blade 40, the segmented dust collection hood assembly 70 is installed at the bottom of the protective cover 50, and the bottom plate 10 is provided with a channel for storing the segmented dust collection hood assembly 70 and allowing it to pass through vertically. The protective cover 50 is integrally formed with a dust outlet pipe 51.

[0028] The hinge mechanism 20 enables an adjustable connection between the power mechanism 30, the protective cover 50, and the base plate 10. In conjunction with the arc-shaped slide rail 23 and the positioning pin, the cutting depth can be adjusted and locked. The through channel on the base plate 10 can store and protect the segmented dust collection hood assembly 70 in the non-operating state, preventing the dust collection hood from being damaged by external impact. The dust outlet pipe 51 and the protective cover 50 are integrally molded, with high structural strength and good sealing performance, preventing wood chips from leaking during transportation and further optimizing the working environment.

[0029] Please see Figure 8 The segmented vacuum hood assembly 70 also includes a main negative pressure pipe 710. The main negative pressure pipe 710 and the first vacuum hood 71 are connected through a first negative pressure air pipe 74. The main negative pressure pipe 710 and the second vacuum hood 72 are connected through a second negative pressure air pipe 75. The main negative pressure pipe 710 and the third vacuum hood 73 are connected through a third negative pressure air pipe 76. A first control valve 77 is installed on the first negative pressure air pipe 74, a second control valve 78 is installed on the second negative pressure air pipe 75, and a third control valve 79 is installed on the third negative pressure air pipe 76. Each vacuum hood assembly... The negative pressure air pipe and negative pressure groove 711 are connected. Through the independent on / off control of the first control valve 77, the second control valve 78, and the third control valve 79, the negative pressure supply of the first dust hood 71, the second dust hood 72, and the third dust hood 73 can be individually controlled. When a dust hood is not unfolded, the corresponding control valve remains closed, cutting off the negative pressure supply, so that the limited negative pressure suction is concentrated in the effective dust collection area, greatly improving the adsorption force per unit area, and solving the technical defects of traditional fixed dust hoods such as dispersed suction and low dust collection efficiency.

[0030] Please see Figure 5 and Figure 6The output shaft of the power mechanism 30 is coaxially connected to the drive shaft 31. The saw blade 40 is fixedly installed on the outer wall of the drive shaft 31, and a protective seat 32 fixed on the power mechanism 30 is sleeved on the outer side of the drive shaft 31. A sealing ring 33 is fixedly sleeved on the outer wall of the drive shaft 31. The sealing ring 33 and the drive shaft 31 rotate synchronously. The negative pressure dust collection assembly 60 includes a drive ring 61 fixedly sleeved on the outer wall of the drive shaft 31. Impellers 62 are evenly arranged along the circumferential direction on the outer wall of the drive ring 61. Each set of impellers 62 has a dust collection groove 63 on its outer surface, so that when the impellers 62 rotate, the dust collection groove 63 can generate a greater negative pressure, and it is also convenient for debris to be temporarily collected in the dust collection groove 63, thereby improving the dust removal effect. A sealing cover 64 covering the outside of the impellers 62 is fixed on the side wall of the protective seat 32, and the sealing ring 33 is embedded in the sealing cover 64 and the two are rotatably assembled.

[0031] Please see Figures 4-6 An arc-shaped exhaust pipe 65 is fitted on the outer wall of the sealing cover 64 along the tangential direction, and the exhaust pipe 65 is connected to the dust outlet pipe 51. The main negative pressure pipe 710 is connected to the inside of the sealing cover 64 through a flexible corrugated pipe, and the main negative pressure pipe 710 is fixedly installed on the protective seat 32 by a bracket.

[0032] Please see Figure 1 A horizontal adjustment ruler 80 is installed on the base plate 10, and a handle 90 is installed on the power mechanism 30.

[0033] When the power mechanism 30 is running, the drive shaft 31 drives the saw blade 40 and drive ring 61 to rotate synchronously. The impeller 62 rotates at high speed inside the sealing cover 64 to form a negative pressure airflow. The negative pressure is transmitted to the segmented dust collection hood assembly 70 through the main negative pressure pipe 710 and various negative pressure air pipes, sucking in the sawdust and dust generated during cutting and discharging them through the exhaust pipe 65 and dust outlet pipe 51. The sealing ring 33 effectively ensures the sealing performance between the drive shaft 31 and the sealing cover 64, maintaining stable negative pressure. The level adjustment ruler 80 allows operators to quickly calibrate the horizontal position of the electric circular saw, improving the straightness and accuracy of the cut. The handle 90 allows operators to hold the equipment stably, improving operating comfort and safety. Specifically: An angle sensor is installed on the power mechanism 30, which can constantly detect its rotation angle around the hinge axis 22, thereby providing input control signals for the opening and closing of the first control valve 77, the second control valve 78, and the third control valve 79. The rotation angle of the power mechanism 30 is matched with the height of the saw blade 40 extending out of the base plate 10. That is, when the rotation angle of the power mechanism 30 around the hinge axis increases, the height of the saw blade 40 extending out of the base plate 10 decreases, and the cutting depth decreases. When the power mechanism 30 drives the saw blade 40 to rotate, it synchronously drives the drive ring 61 and the impeller 62 to rotate at high speed inside the sealing cover 64, so that a stable -1500Pa pressure is formed inside the sealing cover 64. In a negative pressure environment, negative pressure is transmitted to each negative pressure air pipe through the main negative pressure pipe 710. When the electric circular saw is not cutting into the workpiece, the second dust hood 72 and the third dust hood 73 are both retracted outside the first dust hood 71. At this time, the first control valve 77, the second control valve 78, and the third control valve 79 are all in the closed state. When the electric circular saw begins to cut into the workpiece and the cutting depth is less than 10mm, the third dust hood 73 and the second dust hood 72 are retracted and fitted outside the first dust hood 71 under the squeezing force of the workpiece. At this time, only the first dust hood 71 is facing the saw blade 40. At this time, the first control valve 77 is opened, and the second control valve 78 and the third control valve 79 remain closed. The pressure acts only on the first dust suction hood 71 through the first negative pressure air pipe 74. When the cutting depth increases to 10-20mm, the upward rotation angle of the power mechanism 30 around the hinge axis 22 decreases. At this time, the second dust suction hood 72 and the third dust suction hood 73 simultaneously slide out from the outside of the first dust suction hood 71 and cover the workpiece surface. Thus, both the second dust suction hood 72 and the first dust suction hood 71 cover the contact area between the saw blade 40 and the workpiece. At this time, the first control valve 77 and the second control valve 78 open simultaneously, while the third control valve 79 closes. The negative pressure acts simultaneously on the first dust suction hood 71 and the second dust suction hood 72. When the cutting depth further increases to 20-30mm, the power... The rotation angle of mechanism 30 is further reduced, and the third dust suction hood 73 slides out from the surface of the second dust suction hood 72 and then covers the surface of the workpiece. At this time, all three control valves are opened, and negative pressure acts on the three dust suction hoods at the same time, realizing the synchronous adaptive adjustment of the dust suction area and negative pressure supply with the cutting depth. Moreover, each dust suction hood is provided with a dust guide opening groove 712 corresponding to the saw blade 40, which can make the debris brought out by the saw blade 40 enter the negative pressure groove 711 along the dust guide opening groove 712. Furthermore, the dust guide opening groove 712 is set in the circumferential tangential direction of the saw blade 40, which greatly increases the smoothness of debris entering the negative pressure groove 711.

[0034] By working in close coordination between the segmented dust hood assembly 70 and the negative pressure dust collection assembly 60, the core technical problems of fixed dust collection areas, drastic drop in dust collection efficiency when the cutting depth changes, and low collection rate due to dispersed negative pressure suction in existing technologies are systematically solved. The negative pressure dust collection assembly 60 directly utilizes the rotational power of the power mechanism 30 to generate negative pressure, eliminating the need for an additional independent dust collection motor, thus reducing the overall weight by 1.2 kg and lowering manufacturing costs and energy consumption. Through the precise clearance fit between the impeller 62 and the sealing cover 64, a stable high negative pressure can be generated, providing a continuous and sufficient power source for the dust collection system. The segmented dust hood assembly 70 adopts a progressively extending arc-shaped sliding structure, which can automatically adjust the dust collection coverage area according to the cutting depth. The overlapping area between adjacent dust hoods effectively eliminates dust collection blind spots, and the trapezoidal cross-section negative pressure groove 711 ensures that the negative pressure is evenly distributed within the groove. The distribution and flow guide cone 713 can regulate the airflow, avoiding suction loss caused by airflow turbulence and improving the efficiency of wood chip suction. The purely mechanical linkage design of the mechanical stroke valve and the dust hood requires no electronic control components, realizing automatic and precise matching of negative pressure supply to the dust hood's unfolded state. When a dust hood is not unfolded, the corresponding control valve remains closed, cutting off the negative pressure supply, so that the limited negative pressure suction is concentrated on the currently working dust hood, increasing the adsorption force per unit area by more than 60%. The electric circular saw using the collaborative working structure of this invention can achieve a wood chip collection rate of more than 96% in the full cutting depth range of 0-30mm, while the existing electric circular saw with a fixed dust hood has a wood chip collection rate of only about 35% at shallow cutting depths and only about 65% at deep cutting depths. It has outstanding substantial features and significant progress.

[0035] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An electric circular saw, comprising a base plate (10), characterized in that: The top of the base plate (10) is connected to a power mechanism (30) via a hinge mechanism (20). The output end of the power mechanism (30) is connected to a saw blade (40). A negative pressure dust collection assembly (60) that rotates synchronously with the saw blade (40) is installed on the output shaft of the power mechanism (30). A protective cover (50) is installed above the saw blade (40). A segmented dust collection cover assembly (70) that corresponds to the cutting area of ​​the saw blade (40) is connected to the negative pressure dust collection assembly (60). The segmented dust hood assembly (70) includes a first dust hood (71), a second dust hood (72) is slidably mounted on the outer wall of the first dust hood (71), and a third dust hood (73) is slidably mounted on the outer wall of the second dust hood (72). The first dust hood (71), the second dust hood (72), and the third dust hood (73) have the same structure and are all arc-shaped guide hoods. The covering angle range of the first dust hood (71) is 0-12°, the covering angle range of the second dust hood (72) is 10-20°, and the covering angle range of the third dust hood (73) is 18-30°.

2. The electric circular saw according to claim 1, characterized in that: The hinge mechanism (20) includes a hinge seat (21) fixed on the base plate (10). The hinge seat (21) is rotatably connected to the protective cover (50) via a hinge shaft (22). The protective cover (50) is fixedly connected to the power mechanism (30). An arc-shaped slide rail (23) is fixedly provided on the surface of the protective cover (50). A positioning pin that is assembled with the arc-shaped slide rail (23) is fixed on the base plate (10). Fasteners for locking the arc-shaped slide rail (23) are installed on the positioning pin.

3. The electric circular saw according to claim 1, characterized in that: The protective cover (50) is placed over the upper half of the saw blade (40), the segmented dust collection hood assembly (70) is placed at the bottom of the protective cover (50), and the bottom plate (10) is provided with a channel for the segmented dust collection hood assembly (70) to be stored and pass through vertically. The protective cover (50) is integrally formed with a dust outlet pipe (51).

4. The electric circular saw according to claim 3, characterized in that: The first dust hood (71), the second dust hood (72), and the third dust hood (73) are all provided with negative pressure grooves (711), and the lower inner sidewalls of the first dust hood (71), the second dust hood (72), and the third dust hood (73) are all provided with dust guide opening grooves (712). A guide cone (713) that divides the negative pressure groove (711) into spaces is fixed inside the negative pressure groove (711).

5. The electric circular saw according to claim 4, characterized in that: The first dust cover (71) is slidably installed on the inner wall of the protective cover (50), and the inner walls of the second dust cover (72) and the third dust cover (73) are both fixed with slide strips (714). The outer walls of the first dust cover (71) and the second dust cover (72) are provided with slide grooves that match the slide strips (714). The slide strips (714) are arc-shaped strips, the slide grooves are arc-shaped grooves, and the central axes of the arc-shaped grooves, the first dust cover (71), the second dust cover (72), the third dust cover (73) and the protective cover (50) are the same.

6. The electric circular saw according to claim 3, characterized in that: The segmented vacuum hood assembly (70) also includes a main negative pressure pipe (710), which is connected to the first vacuum hood (71) via a first negative pressure air pipe (74), and the main negative pressure pipe (710) is connected to the second vacuum hood (72) via a second negative pressure air pipe (75). The main negative pressure pipe (710) is connected to the third vacuum hood (73) via a third negative pressure air pipe (76). A first control valve (77) is installed on the first negative pressure air pipe (74), a second control valve (78) is installed on the second negative pressure air pipe (75), and a third control valve (79) is installed on the third negative pressure air pipe (76). The negative pressure air pipe and the negative pressure groove (711) on each vacuum hood are connected.

7. The electric circular saw according to claim 6, characterized in that: The output shaft of the power mechanism (30) is coaxially connected to the drive shaft (31). The saw blade (40) is fixedly installed on the outer side wall of the drive shaft (31). The outer side of the drive shaft (31) is fitted with a protective seat (32) fixed on the power mechanism (30). A sealing ring (33) is fixedly fitted on the outer side wall of the drive shaft (31). The sealing ring (33) and the drive shaft (31) rotate synchronously.

8. The electric circular saw according to claim 7, characterized in that: The negative pressure dust collection assembly (60) includes a drive ring (61) fixedly sleeved on the outer wall of the drive shaft (31). Impellers (62) are evenly arranged along the circumferential direction on the outer wall of the drive ring (61). A sealing cover (64) covering the outside of the impeller (62) is fixed on the side wall of the protective seat (32). The sealing ring (33) is embedded in the sealing cover (64) and the two are rotatably assembled.

9. The electric circular saw according to claim 8, characterized in that: The outer wall of the sealing cover (64) is fitted with an arc-shaped exhaust pipe (65) along the tangential direction, and the exhaust pipe (65) and the dust outlet pipe (51) are connected. The main negative pressure pipe (710) is connected to the inside of the sealing cover (64) through a flexible corrugated pipe, and the main negative pressure pipe (710) is fixedly installed on the protective seat (32) by a bracket.

10. The electric circular saw according to claim 1, characterized in that: A leveling ruler (80) is installed on the base plate (10), and a handle (90) is installed on the power mechanism (30).

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