Active withdrawing type bench saw based on pre-contact multi-induction and control method thereof

Abstract

The invention discloses an active retraction type bench saw based on pre-contact multi-induction and a control method thereof, and relates to the technical field of electric tools. An active retraction type bench saw based on pre-contact multiple induction comprises a saw blade, a bench saw body and a bench saw working table top, and a microwave / radar pre-contact early warning module, a human body distance induction switch and a field effect transistor induction module are installed on the back face of the bench saw working table top on the front side of the saw blade. A metal dust collection / protection cover touch sensing module is arranged on a dust collection cover on the upper portion of the saw blade, and a stepping motor of the bench saw is provided with an electromagnetic power-off brake. Through multiple guarantees of early warning and physical isolation, major damage is completely eradicated from the source, the millisecond-level response speed is high, higher safety is achieved, zero-consumable maintenance cost is achieved, the use threshold is remarkably reduced, humanized operation logic is achieved, safety and efficiency are both considered, universality is high, and the system is suitable for various industrial scenes.

Description

Technical Field

[0001] This invention relates to the field of power tool technology, specifically to an active retraction table saw based on pre-contact multi-sensoring and its control method. Background Technology

[0002] As a core piece of equipment in industries such as wood processing and furniture manufacturing, the table saw, with its high-speed rotating blade (typically with a linear speed exceeding 50 m / s), while improving processing efficiency, also brings extremely high safety risks. According to statistics from the U.S. Consumer Product Safety Commission (CPSC), in the United States alone, there are more than 36,000 serious injuries such as finger amputations and limb amputations caused by table saw operation each year, of which about 70% are due to operators' fingers accidentally entering the dangerous area of ​​the saw blade.

[0003] Traditional table saws have significant limitations in their safety features, specifically:

[0004] 1. Mechanical protective devices

[0005] Passive protective tools such as protective covers and push rods rely on the active cooperation of operators. In actual operation, they are often removed because they affect the line of sight or the flexibility of operation, and the protective effect is greatly reduced.

[0006] 2. Contact-based safety system

[0007] Represented by SawStop's "skin-sensing braking technology," braking is triggered by changes in capacitance when the saw blade contacts the human body, but it has the following drawbacks:

[0008] Response delay: It takes 0.08-0.1 seconds from contact to the saw blade coming to a complete stop, which may still cause deep cuts;

[0009] High consumable costs: After triggering, the saw blade and brake assembly need to be replaced as a whole, with a single maintenance cost exceeding $200;

[0010] Risk of accidental triggering: Damp wood and metal impurities can easily cause non-contact malfunctions.

[0011] 3. Infrared / Laser Area Protection

[0012] Infrared beam or laser scanning is used to delineate dangerous areas, but it is severely affected by dust and sawdust, with a failure rate of over 15% in woodworking environments. Furthermore, it cannot distinguish between human bodies and workpieces, and frequent accidental shutdowns affect production efficiency.

[0013] 4. PLC Centralized Control Solution

[0014] Traditional industrial safety systems often rely on PLCs as the control core, but the scanning cycle of PLCs (usually 10-20ms) is difficult to meet the millisecond-level safety response requirements of table saws, and a single point of failure may paralyze the entire system, which does not conform to the industrial design trend of "minimal maintenance".

[0015] Summary of industry pain points

[0016] The current market lacks a table saw safety solution that combines ultra-fast response, zero-contact triggering, low-cost maintenance, and multiple redundancy protections. Existing technologies either sacrifice response speed for reliability, rely on expensive disposable consumables, or suffer from maintenance difficulties due to complex structures, failing to meet the core demand of small and medium-sized processing enterprises for a balance between safety and economy. Summary of the Invention

[0017] The purpose of this invention is to provide an active retraction table saw based on pre-contact multi-sensor and its control method, solving the problem that the current market lacks a table saw safety solution that combines ultra-fast response, zero-contact triggering, low-cost maintenance, and multiple redundant protections.

[0018] To achieve the above objectives, the present invention provides the following technical solution:

[0019] An active retractable table saw based on pre-contact multi-sensor includes a saw blade, a table saw, and a table surface. A microwave / radar pre-contact warning module, a human body contactless sensor switch, and a field-effect transistor sensor module are installed on the back of the table surface in front of the saw blade. A metal dust collection / protective cover touch sensor module is installed on the dust collection cover above the saw blade. The stepper motor of the table saw has an electromagnetic power-off brake. The microwave / radar pre-contact warning module is electrically connected to a PLC control unit. The PLC control unit is electrically connected to the human body contactless sensor switch, the field-effect transistor sensor module, the metal dust collection / protective cover touch sensor module, and the table saw.

[0020] Furthermore, a high-speed electric push rod is screwed to the lower part of the table saw. The lower part of the high-speed electric push rod is screwed to the lower frame of the table saw's worktable. The upward push height of the high-speed electric push rod is greater than the height of the saw blade protruding from the table saw's worktable.

[0021] Furthermore, a red emergency stop button is provided on the back side of the table saw's work surface, and the red emergency stop button is connected in series with the main power circuit.

[0022] Furthermore, the left side of the table saw's work surface is equipped with an audible and visual alarm and LED indicator module, which is electrically connected to the PLC control unit.

[0023] Furthermore, an IoT current monitoring module is installed on the back of the table saw's work surface, and an audible and visual alarm and remote notification module is installed on the right side of the table saw's work surface. The IoT current monitoring module is connected to the stepper motor, high-speed electric push rod, audible and visual alarm, and remote notification module through an independent fault shutdown control circuit.

[0024] Furthermore, the metal dust collection / protective cover touch sensing module is connected to the metal cover via an extension line.

[0025] This invention also provides the following technical solutions:

[0026] A control method for an active retraction table saw based on pre-contact multi-sensor technology includes the following processes: System A: Human safety protection process; System B: Equipment fault protection process.

[0027] S1 and A System Human Safety Protection Procedures:

[0028] Level 1 Microwave / Radar Pre-Contact Warning: When a human body enters a pre-defined danger zone at a predetermined distance in front of the saw blade, the microwave / radar pre-contact warning module on the back of the table saw detects the approaching human tissue and emits an electrical signal; after receiving the signal from the microwave / radar pre-contact warning module, the PLC control unit performs the following actions:

[0029] Connect the power supply to the human body contactless sensor switch, the field effect transistor sensor module, the sound and light alarm and LED indicator module, and the sound and light warning device; turn on the corresponding LED indicator of the microwave / radar pre-contact warning module. This stage is only for warning and does not trigger shutdown or saw blade retraction.

[0030] Level 2 Triple Independent Human Danger Detection: When a human continues to approach the near-danger area at a predetermined distance in front of the saw blade, any one of the human body air-sensing switch, field-effect transistor sensing module, or metal dust collection / protective cover touch sensing module will detect the approach of the human body and independently output a danger signal, directly cutting off the power supply to the table saw motor.

[0031] Human safety protection action procedure: When any one of the human body induction switches, MOSFET sensing modules, or metal dust collector / protective cover touch sensing modules is triggered, the solid-state relay inside the table saw immediately cuts off the power to the table saw; simultaneously, the electromagnetic power-off brake built into the stepper motor is activated, stopping the saw blade; the high-speed electric push rod is activated, retracting the synchronized table saw and saw blade into the table saw's inner chamber; the corresponding LED indicator light of the trigger source of the human body induction switch, MOSFET sensing module, or metal dust collector / protective cover touch sensing module is illuminated, activating the on-site audible and visual alarm; the IoT module records the event type as "human safety protection triggered" and sends alarm information to the factory safety management department;

[0032] Human body protection recovery process: After the protection action is completed, the system will not automatically recover. It must be manually confirmed. After the human body leaves the danger area, the operator manually presses the independently set recovery button. The PLC control unit starts the recovery process. The high-speed electric push rod slowly raises the saw blade back to the working position. After a delay of about 5 seconds, the soft starter starts the motor of the table saw, which gradually accelerates from low speed to the rated speed. The system returns to normal working state. The manual recovery mechanism can prevent the operator from unintentionally approaching the saw blade due to a sudden health condition.

[0033] S2 and B system equipment fault protection procedures:

[0034] IoT Current Monitoring: The IoT current monitoring module monitors the motor's operating current in real time through a current sensor. The monitoring content includes: abnormal current increase, abnormal current fluctuation, sudden current drop, and current imbalance. This monitoring process is completely independent of the human body protection system and runs continuously.

[0035] Fault Judgment and Independent Shutdown: When the IoT current monitoring module detects any of the above abnormalities, it immediately outputs an independent fault shutdown signal, directly cuts off the motor power, activates the electromagnetic power-off brake to stop the saw blade, activates the high-speed electric push rod to retract the saw blade into the inner chamber, and simultaneously connects the audible and visual alarm and LED indicator module to light up the fault LED indicator and activate the on-site audible and visual alarm. Based on the logic of independent testing and verification, the IoT current monitoring module records the event as "fault shutdown" and connects the audible and visual alarm and remote notification module to send the fault alarm information to the factory equipment management department. This process is completely separated from the human body protection process, and does not share trigger conditions or logical judgments.

[0036] Fault recovery process: Equipment management personnel investigate and eliminate the fault; manually press the recovery button; the high-speed electric push rod slowly raises the saw blade back to the working position; the soft starter starts the motor of the table saw, gradually accelerating it to the rated speed; the system returns to normal working state.

[0037] Furthermore, in the second-level triple independent human hazard confirmation, the three modules—human body air-sensing switch, field-effect transistor sensing module, and metal dust collection / protective cover touch sensing module—are independent of each other and do not depend on each other. Once a hazard is detected, the power supply to the table saw motor can be cut off independently.

[0038] The beneficial effects of this invention are as follows:

[0039] 1. The two systems are completely independent, resulting in higher security;

[0040] 2. Triple independent human body sensors, any one of which can cut off the power supply to avoid leakage protection;

[0041] 3. Pre-contact rejection protection, offering significantly higher safety than contact-based systems;

[0042] 4. The IoT current monitoring operates independently and can automatically shut down when no one is near it;

[0043] 5. All parameters are derived from mature products on the market; the solution is verifiable, reproducible, and mass-producible.

[0044] 6. The improved IoT fault identification solution has been independently tested and demonstrates high reliability;

[0045] 7. A manual recovery mechanism prevents secondary injuries caused by abnormal physical conditions or failure to check equipment;

[0046] 8. Low cost, high reliability, and easy to industrialize.

[0047] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the overall front structure of an embodiment of the present invention.

[0049] Figure 2 This is a schematic diagram of the overall side structure of an embodiment of the present invention.

[0050] Figure 3 This is a logic diagram of a table saw control system according to an embodiment of the present invention.

[0051] Figure 4 This is a flowchart illustrating the operation of a table saw according to an embodiment of the present invention.

[0052] Figure 5 This is a PLC wiring diagram shown in one embodiment of the present invention.

[0053] Figure 6 This is a schematic diagram illustrating the operating principle of an embodiment of the present invention.

[0054] Explanation of reference numerals in the attached diagram: 1. Microwave / radar pre-contact warning module; 2. Human body contactless sensor switch; 3. Field effect transistor sensor module; 4. Metal dust collector / protective cover touch sensor module; 5. Electromagnetic power-off brake; 6. PLC control unit; 7. High-speed electric actuator; 8. Red emergency stop button; 9. Audible and visual alarm and LED indicator module; 10. Internet of Things current monitoring module; 11. Audible and visual alarm and remote notification module. Detailed Implementation

[0055] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0057] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. Furthermore, the technical features involved in the different embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0058] Please see Figure 1 A preferred embodiment of this application shows an active retraction table saw based on pre-contact multi-sensor technology, including a saw blade, a table saw, and a table saw work surface. A microwave / radar pre-contact warning module 1, a human body contactless sensor switch 2, and a field-effect transistor sensor module 3 are installed on the back of the table saw work surface in front of the saw blade. A metal dust collection / protective cover touch sensor module 4 is provided on the dust collection cover above the saw blade. The stepper motor of the table saw has an electromagnetic power-off brake 5. The microwave / radar pre-contact warning module 1 is electrically connected to a PLC control unit 6. The PLC control unit 6 is electrically connected to the human body contactless sensor switch 2, the field-effect transistor sensor module 3, the metal dust collection / protective cover touch sensor module 4, and the table saw.

[0059] The lower part of the table saw is screwed with a high-speed electric push rod 7. The lower part of the high-speed electric push rod 7 is screwed to the lower frame of the table saw worktable. The upward push height of the high-speed electric push rod 7 is greater than the height of the saw blade protruding from the table saw worktable.

[0060] A red emergency stop button 8 is located on the back side of the table saw's work surface, and the red emergency stop button 8 is connected in series with the main power circuit.

[0061] The left side of the table saw workbench is equipped with an audible and visual alarm and LED indicator module 9, which is electrically connected to the PLC control unit 6.

[0062] The back of the table saw workbench is equipped with an IoT current monitoring module 10, and the right side of the table saw workbench is equipped with an audible and visual alarm and remote notification module 11. The IoT current monitoring module 10 is connected to the stepper motor, high-speed electric push rod 7, and audible and visual alarm and remote notification module 11 through an independent fault shutdown control circuit.

[0063] The metal dust collection / protective cover touch sensing module 4 is connected to the metal cover via an extension line.

[0064] A control method for an active retraction table saw based on pre-contact multi-sensor technology includes the following processes: System A: Human safety protection process; System B: Equipment fault protection process.

[0065] S1 and A System Human Safety Protection Procedures:

[0066] Level 1 Microwave / Radar Pre-Contact Warning: When a human body enters a preset danger zone at a predetermined distance in front of the saw blade, the microwave / radar pre-contact warning module 1 on the back of the table saw detects the approaching human tissue and emits an electrical signal; after receiving the signal from the microwave / radar pre-contact warning module 1, the PLC control unit 6 performs the following actions:

[0067] Turn on the power supply of the human body air-sensing switch 2, the field effect transistor sensing module 3, the sound and light alarm and LED indicator module 9, and the sound and light warning device; turn on the corresponding LED indicator of the microwave / radar pre-contact warning module 1. This stage is only for warning and does not trigger shutdown or saw blade retraction.

[0068] Level 2 Triple Independent Human Danger Detection: When a human continues to approach the near-danger area at a predetermined distance in front of the saw blade, any one of the human body air-sensing switch 2, field-effect transistor sensing module 3, or metal dust collector / protective cover touch sensing module 4 will detect the approach of the human body and independently output a danger signal, directly cutting off the power supply to the table saw motor.

[0069] Human safety protection operation procedure: When any one of the human body induction modules 2, MOSFET induction module 3, or metal dust collector / protective cover touch induction module 4 is triggered, the solid-state relay inside the table saw immediately cuts off the power to the table saw; at the same time, the electromagnetic power-off brake 5 of the stepper motor is activated, stopping the saw blade; the high-speed electric push rod 7 is activated, retracting the synchronized table saw and saw blade into the table saw's inner chamber; the LED indicator light corresponding to the trigger source of the human body induction switch 2, MOSFET induction module 3, or metal dust collector / protective cover touch induction module 4 is lit, activating the on-site audible and visual alarm; the IoT module records the event type as "human safety protection triggered" and sends alarm information to the factory safety management department;

[0070] Human body protection recovery process: After the protection action is completed, the system will not automatically recover. It must be manually confirmed. After the human body leaves the danger area, the operator manually presses the independently set recovery button. The PLC control unit 6 starts the recovery process. The high-speed electric push rod 7 slowly raises the saw blade back to the working position. After a delay of about 5 seconds, the soft starter starts the motor of the table saw, which gradually accelerates from low speed to the rated speed. The system returns to normal working state. The manual recovery mechanism can prevent the operator from unintentionally approaching the saw blade due to a sudden health condition.

[0071] S2 and B system equipment fault protection procedures:

[0072] IoT Current Monitoring: The IoT current monitoring module 10 monitors the motor operating current in real time through a current sensor. The monitoring content includes: abnormal current increase, abnormal current fluctuation, sudden current drop, and current imbalance. This monitoring process is completely independent of the human body protection system and runs continuously.

[0073] Fault Judgment and Independent Shutdown: When the IoT current monitoring module 10 detects any of the above abnormalities, it immediately outputs an independent fault shutdown signal, directly cuts off the motor power, activates the electromagnetic power-off brake 5 to stop the saw blade, activates the high-speed electric push rod 7 to retract the saw blade into the inner chamber, and simultaneously connects the audible and visual alarm and LED indicator module 9 to light up the fault LED indicator and activate the on-site audible and visual alarm. Based on the logic of independent testing and verification, the IoT current monitoring module 10 records the event as "fault shutdown" and connects the audible and visual alarm and remote notification module 11 to send the fault alarm information to the factory equipment management department. This process is completely separated from the human body protection process, and does not share trigger conditions or logical judgments.

[0074] Fault recovery process: Equipment management personnel investigate and eliminate the fault; manually press the recovery button; high-speed electric push rod 7 slowly raises the saw blade back to the working position; soft starter starts the motor of the table saw, gradually accelerating it to the rated speed; the system returns to normal working state.

[0075] The second-level triple independent human hazard confirmation system consists of three independent modules: human body air-sensing switch 2, field-effect transistor sensing module 3, and metal dust collector / protective cover touch sensing module 4. Each module is independent and self-reliant, and can independently cut off the power supply to the table saw motor upon detecting a hazard.

[0076] System Principle Explanation

[0077] (I) Principles of Human Safety Protection System

[0078] 1. The microwave / radar pre-contact early warning module is responsible for long-range early warning and activates subsequent sensing modules in advance.

[0079] 2. Three independent human body sensing modules are responsible for close-range hazard confirmation.

[0080] 3. Any module can be independently disconnected from the power supply, achieving redundant protection.

[0081] 4. The braking and saw blade retraction actions are based on mature product parameters, ensuring speed and reliability.

[0082] 5. A manual recovery mechanism prevents secondary damage.

[0083] (II) Principles of Equipment Fault Protection System (Independent)

[0084] 1. The IoT module continuously diagnoses the motor status through current monitoring.

[0085] 2. The fault determination logic is based on mature current sensors and independently tested and verified algorithms.

[0086] 3. The fault shutdown process operates independently and is not affected by the human body sensing system.

[0087] 4. It can prevent accidents such as equipment damage, fire, and motor burnout.

[0088] 5. It can remotely notify the equipment management department to achieve digital management.

[0089] (III) Dual-system parallel mechanism

[0090] The two architectures are independent in structure, logic, and triggering, but they share the same actuators (brake, saw blade retraction) to achieve maximum safety.

[0091] In summary, this invention provides an active retraction table saw based on pre-contact multi-sensoring and its control method. This device features a completely independent dual-system design for enhanced safety, triple independent human body sensors (any one of which can cut off the power to prevent leakage protection), and pre-contact rejection protection, making it far safer than contact-based systems. The IoT current monitoring operates independently and automatically shuts down when no one is near. All parameters are derived from mature market products, ensuring the solution is verifiable, reproducible, and mass-producible. The improved IoT fault identification solution has been independently tested and demonstrates high reliability. A manual recovery mechanism prevents secondary injuries due to abnormal physical conditions or unchecked equipment. It boasts low cost, high reliability, and ease of industrialization. Multiple layers of physical isolation prevent major injuries at the source. Millisecond-level response speed enhances safety, zero consumable maintenance costs significantly lower the barrier to entry, user-friendly operating logic balances safety and efficiency, a simplified control architecture improves system reliability, and high versatility adapts to various industrial scenarios.

[0092] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0093] The above embodiments merely illustrate implementation methods of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An active retraction table saw based on pre-contact multi-sensor technology, comprising a saw blade, a table saw, and a table saw work surface, characterized in that, The back of the table saw work surface on the front side of the saw blade is equipped with a microwave / radar pre-contact warning module (1), a human body air-sensing switch (2), and a field-effect transistor sensing module (3). The dust collection cover on the upper part of the saw blade is equipped with a metal dust collection / protective cover touch sensing module (4). The stepper motor of the table saw has an electromagnetic power-off brake (5). The microwave / radar pre-contact warning module (1) is electrically connected to the PLC control unit (6). The PLC control unit (6) is electrically connected to the human body air-sensing switch (2), the field-effect transistor sensing module (3), the metal dust collection / protective cover touch sensing module (4), and the table saw.

2. The active retraction table saw based on pre-contact multi-sensoring as described in claim 1, characterized in that, The lower part of the table saw is screwed with a high-speed electric push rod (7). The lower part of the high-speed electric push rod (7) is screwed on the lower frame of the table saw worktable. The upward push height of the high-speed electric push rod (7) is greater than the height of the saw blade protruding from the table saw worktable.

3. The active retraction table saw based on pre-contact multi-sensoring as described in claim 1, characterized in that, A red emergency stop button (8) is provided on the back side of the table saw work surface, and the red emergency stop button (8) is connected in series with the main power circuit.

4. The active retraction table saw based on pre-contact multi-sensoring as described in claim 1, characterized in that, The left side of the table saw workbench is equipped with an audible and visual alarm and LED indicator module (9), which is electrically connected to the PLC control unit (6).

5. A table saw based on pre-contact multi-sensor active retraction as described in claim 1, characterized in that, The back of the table saw workbench is equipped with an IoT current monitoring module (10), and the right side of the table saw workbench is equipped with an audible and visual alarm and remote notification module (11). The IoT current monitoring module (10) is connected to the stepper motor, high-speed electric push rod (7), audible and visual alarm and remote notification module (11) through an independent fault shutdown control circuit.

6. A table saw based on pre-contact multi-sensor active retraction as described in claim 1, characterized in that, The metal dust collection / protective cover touch sensing module (4) is connected to the metal cover via an extension line.

7. The control method for an active retraction table saw based on pre-contact multi-sensoring as described in claim 1, characterized in that, This includes the following processes: System A: Human safety protection process; System B: Equipment failure protection process. S1 and A System Human Safety Protection Procedures: Level 1 Microwave / Radar Pre-Contact Warning: When a human body enters a pre-defined danger zone at a predetermined distance in front of the saw blade, the microwave / radar pre-contact warning module (1) on the back of the table saw detects the approach of human tissue and emits an electrical signal; after receiving the signal from the microwave / radar pre-contact warning module (1), the PLC control unit (6) performs the following actions: Connect the human body air-sensing switch (2), field effect transistor sensing module (3), sound and light alarm and LED indicator module (9), sound and light alarm device power supply; light up the corresponding LED indicator of microwave / radar pre-contact warning module (1). This stage is only for warning and does not trigger shutdown or saw blade retraction. Level 2 Triple Independent Human Danger Detection: When a human continues to approach the near-danger area at a predetermined distance in front of the saw blade, any one of the human air-sensing switch (2), field-effect transistor sensing module (3), or metal dust collector / protective cover touch sensing module (4) will detect the approach of the human and independently output a danger signal to directly cut off the power supply to the table saw motor. Human body protection action process: When any one of the human body induction modules (2), field effect transistor induction module (3), or metal dust collector / protective cover touch induction module (4) is triggered, the solid-state relay inside the table saw immediately cuts off the power supply to the table saw; at the same time, the electromagnetic power-off brake (5) of the stepper motor is activated, causing the saw blade to stop; the high-speed electric push rod (7) is activated, retracting the synchronized table saw and saw blade into the inner chamber of the table saw; the LED indicator lights corresponding to the trigger sources of the human body induction switch (2), field effect transistor induction module (3), and metal dust collector / protective cover touch induction module (4) are lit, and the on-site sound and light alarm is activated; the Internet of Things module records the event type as "human body safety protection trigger" and sends alarm information to the factory safety management department; Human body protection recovery process: After the protection action is completed, the system will not automatically recover. It must be manually confirmed. When the human body leaves the danger area, the operator manually presses the independently set recovery button. The PLC control unit (6) starts the recovery process. The high-speed electric push rod (7) slowly raises the saw blade back to the working position. After a delay of about 5 seconds, the soft starter starts the motor of the table saw, which gradually accelerates from low speed to rated speed. The system returns to normal working state. The manual recovery mechanism can prevent the operator from unintentionally approaching the saw blade due to a sudden health condition. S2 and B system equipment fault protection procedures: IoT current monitoring: The IoT current monitoring module (10) monitors the motor operating current in real time through the current sensor. The monitoring content includes: abnormal current increase, abnormal current fluctuation, sudden current drop, and current imbalance. This monitoring process is completely independent of the human body protection system and runs continuously. Fault Judgment and Independent Shutdown: When the IoT current monitoring module (10) detects any of the above abnormalities, it immediately outputs an independent fault shutdown signal, directly cuts off the motor power supply, starts the electromagnetic power-off brake (5) to stop the saw blade, starts the high-speed electric push rod (7) to retract the saw blade into the inner chamber, and simultaneously connects the sound and light alarm and LED indicator module (9) to light up the fault LED indicator and start the on-site sound and light alarm. The IoT current monitoring module (10) records the event as "fault shutdown" based on the logic of independent testing and verification, and connects the sound and light alarm and remote notification module (11) to send fault alarm information to the factory equipment management department. This process is completely separated from the human body protection process, does not share trigger conditions, and does not share logical judgment. Fault recovery process: Equipment management personnel investigate and eliminate faults; manually press the recovery button; the high-speed electric push rod (7) slowly raises the saw blade back to the working position; the soft starter starts the motor of the table saw, gradually accelerating it to the rated speed; the system returns to normal working state.

8. A control method for an active retraction table saw based on pre-contact multi-sensoring as described in claim 7, characterized in that, In the second-level triple independent human danger confirmation, the three modules of human air-sensing switch (2), field effect transistor sensing module (3), and metal dust collector / protective cover touch sensing module (4) are independent of each other and do not depend on each other. When a danger is detected, the power supply of the table saw motor can be cut off independently.

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