A safety protection device and bypass control method for a bending machine

Abstract

This application relates to a safety protection device and bypass control method for a bending machine, comprising: a transmitter, a receiver, a mechanical adjustment bracket, and an adaptive bypass control unit independent of the existing CNC system and electrically connected to the transmitter and receiver. The adaptive bypass control unit includes an external signal acquisition module configured to acquire the downward movement status of the bending machine without accessing the internal communication of the existing CNC system, and output an independent slow-down signal to the receiver accordingly. This ensures that the receiver remains in a protected state during the rapid downward stroke of the bending machine and disables the current protected state when entering the slow downward stroke. This application, through a non-intrusive bypass design, enables the receiver to maintain an anti-pinch protection state during the rapid downward stroke of the machine tool and disables this state when entering the slow downward stroke. Thus, without requiring significant modifications to the underlying electrical circuitry, it achieves both extremely high operational safety and processing efficiency for complex workpieces.

Description

Technical Field

[0001] This application relates to the field of bending machine equipment technology, specifically to a bending machine safety protection device and bypass control method. Background Technology

[0002] The operating stroke of a bending machine is typically divided into a fast downward stroke and a slow downward stroke. Currently, the industry widely uses photoelectric protection devices (such as laser safety barriers) installed on both sides of the cutting edge, which move synchronously with the cutting tool for protection. Its standard operating logic is as follows: if an obstacle such as a finger is detected obstructing the flow during the fast downward stroke, the machine is immediately stopped; while when the slow downward stroke is reached (i.e., the cutting tip is about to contact the sheet metal), the device needs to obtain the machine tool's "slow downward signal" to shield the protective state, thereby allowing the machine tool to complete complex processes such as folding boxes normally.

[0003] However, existing safety protection systems heavily rely on the bending machine's native CNC system to provide this "slow-down signal." In actual industrial settings, a vast number of older or simple bending machines (even some models without foot pedals) do not have this signal interface pre-installed. Forcibly installing existing safety protection devices would require deep and disruptive reverse engineering of the machine tool's underlying electrical control cabinet and solenoid valve logic. This modification is not only highly complex and costly, but it also easily disrupts the original electrical balance of older machine tools, leading to equipment crashes or frequent malfunctions.

[0004] Therefore, there is an urgent need in this field for a bending machine safety protection device that can independently acquire the machine tool's downward state and adaptively execute safety shielding without destructively altering the machine tool's underlying CNC system. Summary of the Invention

[0005] This application provides a safety protection device and bypass control method for a bending machine to solve the technical problems of existing safety protection devices having poor compatibility, difficulty in electrical modification, and easy damage to the original machine tool control logic due to over-reliance on the machine tool's native slow-down signal.

[0006] In a first aspect, this application provides a safety protection device for a bending machine, comprising: The transmitter and receiver are respectively installed on both sides of the blade of the bending machine to emit and receive a light beam below the blade to form a protective area; A mechanical adjustment bracket is used to support and adjust the position of the transmitter and receiver; and An adaptive bypass control unit, independent of the original CNC system of the bending machine and electrically connected to the transmitter and receiver; The adaptive bypass control unit includes an external signal acquisition module. The external signal acquisition module is configured to acquire the downward movement status of the bending machine without accessing the internal communication of the original CNC system, and output an independent slow downward signal to the receiver accordingly, so that the receiver maintains a protection state during the fast downward stroke of the bending machine, and shields the current protection state when entering the slow downward stroke.

[0007] By adopting the above technical solution, the external signal acquisition module in the adaptive bypass control unit can independently acquire the downward movement status of the bending machine without connecting to the original CNC system internal communication of the machine tool, and output a slow-down signal to perform the shielding of the protection status. Unlike the existing technology where safety protection devices are highly dependent on the machine tool's native communication interface and the defects of forcibly adding them can easily damage the underlying electrical logic of the machine tool, this solution effectively overcomes the technical difficulties of "not being able to install or modify" old bending machines, and significantly improves the efficiency of equipment safety upgrades.

[0008] In one alternative implementation, the adaptive bypass control unit is configured to adapt to a bending machine with a foot pedal control loop, and the external signal acquisition module is an optical fiber amplifier. The fiber optic amplifier is connected in series in the foot pedal control circuit of the bending machine, and the signal output terminal of the fiber optic amplifier is electrically connected to the receiver to send the slow-down signal to the receiver.

[0009] By adopting the above technical solution, for conventional machine tools with foot pedals, a fiber optic amplifier is used to connect the foot pedal circuit in series, and the electrical state change of the operator stepping on the pedal is used as a signal source; low-cost state monitoring signal extraction is achieved, the on-site wiring is simplified, and the success rate and stability of implementation are improved.

[0010] In one alternative implementation, the adaptive bypass control unit is configured to adapt to a bending machine without a foot pedal control loop or where position information cannot be obtained by foot pedal, and the external signal acquisition module includes a position detection sensor installed on the side wall of the bending machine or the upper die guide rail. The position detection sensor is configured to be triggered when the upper mold descends rapidly to a safe critical height, so as to send the slow descent signal to the S1 terminal of the receiver.

[0011] By adopting the above technical solution, for old machine tools where electrical signals cannot be extracted, the actual mechanical height of the mold can be sensed by an external sensor, making up for the blind spots of electrical monitoring and broadening the applicability of the protection device on various simple bending machines.

[0012] In one alternative implementation, the adaptive bypass control unit further includes an external relay; The transmitter and the receiver are powered by the same switching power supply in parallel, and their positive terminals are physically short-circuited. The coil of the external relay is controlled by the output terminal of the external signal acquisition module and the output terminal of the receiver. The normally open contact of the external relay is connected in series to the power supply circuit of the front end of the solenoid valve that controls the downward movement inside the bending machine. It is configured to forcibly cut off the power supply circuit of the solenoid valve by disconnecting its own contact if the beam is blocked during the rapid downward stroke.

[0013] By adopting the above technical solution, once the beam is blocked, the system bypasses the intermediate control layer that is prone to jamming and aging in the machine tool, and cuts off the power of the solenoid valve at the highest voltage fire wire end; through the coordination of photoelectric sensing and the underlying physical power cut-off, the safety hazards of brake failure are reduced and the safety defense is improved.

[0014] In one alternative implementation, the transmitter is connected to a 3-core shielded cable, and the receiver is connected to a 7-core shielded cable. The 7-core shielded cable includes an independently configured S1 terminal, which is configured to receive the slow-down signal. The transmitter uses a Class I laser source with a divergence angle of no more than 1.5 mrad, and the overall response time of the safety protection device is no more than 15 ms.

[0015] By adopting the above technical solutions, a response time of no more than 15ms ensures immediate braking in the event of danger, and the high-specification laser light source and multi-core shielded wire further improve the system's anti-interference capability in harsh industrial high-voltage electromagnetic environments.

[0016] In one optional embodiment, the mechanical adjustment bracket is installed on the upper die of the bending machine and moves up and down synchronously with the upper die; The vertical adjustment dimension of the mechanical adjustment bracket is 500mm to 600mm, and the horizontal extension dimension is 100mm to 150mm. The mechanical adjustment bracket is equipped with a dual adjustable handle configured for stepless adjustment, so that at the critical position of switching from fast downward stroke to slow downward stroke, the transmitter and the receiver can be locked at a safe threshold height that ensures the minimum distance between the tip of the upper die and the lower die of the bending machine is no more than 5mm.

[0017] By adopting the above technical solution, using a follow-up mechanism and an adjustable support in three-dimensional space, the beam is always locked onto the dangerous area; the safety blind zone is compressed to no more than 5mm, providing anti-pinch protection while maximizing the production flexibility of the machine in processing complex deep cavity folding boxes.

[0018] Secondly, this application also provides a bypass control method for a safety protection device of a bending machine, comprising the following steps: Step S1: A light beam is emitted below the blade of the bending machine through the transmitter, and the light beam is received by the receiver to form a protective area; Step S2: Independently acquire the downward movement status of the bending machine through the external signal acquisition module in the adaptive bypass control unit; Step S3: Based on the obtained downward movement status, determine whether the bending machine is currently in a fast downward stroke or a slow downward stroke; Step S4: If it is determined that the bending machine is in the fast downward stroke, the receiver remains in the protection state and outputs a stop signal when the beam is blocked; If it is determined that the bending machine has entered the slow downward stroke, the external signal acquisition module outputs a slow downward signal to the receiver so that the receiver can shield the protection state.

[0019] In an optional implementation, the external signal acquisition module is an optical fiber amplifier. When the optical fiber amplifier is connected in series to the foot pedal control circuit of the bending machine, the specific processes of steps S2 and S3 are as follows: The fiber optic amplifier detects changes in the circuit state caused by the foot pedal action in real time. When the state change is detected to reach the preset slow-down travel trigger condition, the fiber amplifier generates the slow-down signal and sends it to the S1 terminal of the receiver.

[0020] In an optional embodiment, the external signal acquisition module includes a position detection sensor installed on the side wall of the bending machine or the upper die guide rail. When the position detection sensor is configured to acquire position information, the specific processes of steps S2 and S3 are as follows: The position detection sensor detects the change in the height position of the upper mold as it moves downwards in real time. When the upper mold is detected to be rapidly descending to a safe critical height, the position detection sensor is triggered, generating the slow descent signal and sending it to the S1 terminal of the receiver.

[0021] In an optional implementation, the adaptive bypass control unit further includes an external relay. When the normally open contact of the external relay is connected in series in the power supply circuit of the solenoid valve controlling the downward movement of the bending machine, the specific process of outputting the stop signal is as follows: The receiver and the external signal acquisition module work together to de-energize the coil of the external relay, so that the normally open contact opens instantaneously, thereby forcibly cutting off the power supply circuit of the solenoid valve.

[0022] In summary, this application includes at least one of the following beneficial technical effects: 1. An adaptive bypass control architecture independent of the original CNC system is adopted, providing a dual-rail parallel solution of "fiber optic amplifier monitoring foot pedal electrical status" and "sensor monitoring guide rail physical displacement", which solves the problem of "inability to perform safety upgrades" for a large number of old, interface-less, closed-source bending machines; 2. A bottom-level hard cutoff mechanism based on the normally open contacts of an external relay directly connected in series with the high-voltage solenoid valve power supply wire was constructed, bypassing the intermediate control unit that is prone to aging and jamming in machine tools, ensuring instantaneous physical isolation of the power source in the event of danger, and improving human and machine safety. 3. A three-dimensional precise positioning mechanism for the mechanical support and a two-dimensional collaborative mechanism for the bypass control unit were established, and a safety threshold locking of no more than 5mm was introduced into the process mode to achieve a balance between personnel safety and equipment production efficiency. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the overall architecture of the bending machine safety protection device provided in the embodiments of this application; Figure 2 This is a general flowchart of the bending machine bypass control method provided in the embodiments of this application; Figure 3 A flowchart of the normal bending mode control method provided in the embodiments of this application; Figure 4 A flowchart of the folding box mode control method provided in the embodiments of this application; Figure 5 A flowchart illustrating the safe mode forcibly stopping at a shielding point, provided in an embodiment of this application; Figure 6 A flowchart of the security threshold height locking method provided in this application embodiment; Figure 7 The electrical wiring diagram provided in this embodiment is used to illustrate the electrical wiring method for a bending machine with a foot pedal control circuit; Figure 8 The electrical wiring diagram provided in this embodiment is used to illustrate the electrical wiring method for old machine tools with risks of aging relay components or control lag, and old machine tools without foot control circuits.

[0025] Explanation of reference numerals in the attached figures: 1. Transmitter; 2. Receiver; 3. Mechanical adjustment bracket; 4. Adaptive bypass control unit; 5. Fiber optic amplifier; 6. External relay. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “” used herein may also mean including the plural forms. The terms “comprising,” “including,” and “having” are inclusive and therefore indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof.

[0028] Although terms such as first, second, third, and fourth may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," "third," and "fourth," as well as other numerical terms, do not imply order or sequence when used in this document. Furthermore, in the description of this application, unless otherwise expressly specified and limited, the terms "set up" and "connected" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art will understand the specific meaning of the above terms in this application based on the specific circumstances.

[0029] For ease of description, spatial relative terms can be used in the text to describe the relationship of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "end," "inner," and "outer." Such spatial relative terms are intended to include different orientations of the mechanism in use or operation, in addition to the orientations depicted in the figure.

[0030] Existing bending machine safety protection devices typically rely heavily on the machine tool's native CNC system to provide a "slow-down signal" to shield the protection state of the grating when bending complex workpieces. However, a large number of old or simple bending machines do not have this signal interface pre-installed. Forcibly adding this device would require destructive modifications to the machine tool's underlying structure, resulting in poor compatibility and frequent crashes.

[0031] To solve the above problems, such as Figures 1 to 8 As shown, this application provides a safety protection device for a bending machine, which mainly includes a transmitter 1, a receiver 2, a mechanical adjustment bracket 3, and an adaptive bypass control unit 4. The transmitter 1 and the receiver 2 are respectively installed on both sides of the cutting edge of the bending machine. The transmitter 1 is used to emit a light beam below the cutting edge, and the receiver 2 is used to receive the light beam emitted by the transmitter 1, thereby forming an invisible light beam protection area (i.e., a safety barrier) in three-dimensional space.

[0032] The mechanical adjustment bracket 3, acting as a load-bearing component, is used to support and precisely adjust the absolute position and relative attitude of the transmitter 1 and receiver 2. In the high-intensity vibration working environment of the bending machine, the alignment accuracy of the transmitter 1 and receiver 2 determines the reliability of the protection system. If the mechanical adjustment bracket 3 experiences even a slight deformation or displacement, the beam will not be captured by the receiver 2, causing the machine tool to stop prematurely and severely affecting production efficiency. In this application, the mechanical adjustment bracket 3 is rigidly fixed to the upper die (slider) of the bending machine using high-strength internal hexagonal bolts and is configured to move up and down synchronously with the upper die. This follow-up design ensures that regardless of the height of the upper die's stroke, the protection beam is always parallel to the tip of the upper cutter and located at a preset safe distance directly below the tip. Furthermore, the mechanical adjustment bracket 3 adopts a "cross slide" type dual-axis stepless adjustment structure, which can adapt to sheet metal materials of different thicknesses and dies with different cross-sectional shapes (such as straight sword dies, curved dies, and bending dies).

[0033] In existing technological applications, safety light curtains typically communicate with the machine tool motherboard at a low level to obtain the machine tool's current travel status (e.g., fast descent, slow descent, return stroke). In this application, however, the adaptive bypass control unit 4 is independent of the bending machine's original CNC system and is electrically connected to the transmitter 1 and receiver 2. The adaptive bypass control unit 4 includes an external signal acquisition module, which only needs to be located outside the machine tool (e.g., at the foot pedal or slide rail). This allows it to independently acquire the bending machine's downward movement status without connecting to the internal communication bus of the bending machine's original CNC system, and accordingly outputs an independent slow descent signal to the receiver 2. This controls the receiver 2 to maintain anti-pinch protection during the bending machine's fast descent stroke and automatically disables the current protection when entering the slow descent stroke (when the cutter tip is about to contact the sheet metal, within the safe bending zone). This allows the machine to continue descent even when the beam is blocked by the sheet metal, completing complex processes (e.g., box bending). This simplifies the machine tool's safety upgrade process, avoids deep reverse engineering of the underlying system, and effectively improves the system's electrical stability.

[0034] The transmitter 1 uses a Class I laser source with a divergence angle of no more than 1.5 mrad. The transmitter 1 is connected to a 3-core shielded cable, and the receiver 2 is connected to a 7-core shielded cable. The 7-core shielded cable includes an independently configured S1 terminal, specifically designed to receive slow-descent signals from an external signal acquisition module. Furthermore, the vertical adjustment range of the mechanical adjustment bracket 3 is 500 mm to 600 mm, preferably 550 mm; this vertical adjustment stroke is sufficient to cover the upper die height range of most hydraulic and purely mechanical bending machines currently on the market. Simultaneously, the horizontal extension range of the mechanical adjustment bracket 3 (i.e., perpendicular to the machine tool cutting edge) is designed to be 100 mm to 150 mm, preferably 120 mm. This horizontal extension ensures that the transmitter 1 / receiver 2 will not interfere with the side plate of the machine tool, and also ensures that the starting point of the beam emission can completely cover the working area. It is also equipped with dual adjustable handles: one adjustable handle is used to lock the vertical sliding module, and the other adjustable handle is used to lock the horizontal sliding module. The operator simply needs to release the handle to smoothly and steplessly adjust the position of transmitter 1 and receiver 2 relative to the blade edge in three-dimensional space using the precision scale built into the bracket. After adjustment, tightening the adjustable handle locks the bracket in place via mechanical friction self-locking. This ensures that at the critical position where the fast-down stroke transitions to the slow-down stroke, transmitter 1 and receiver 2 are locked at a safe threshold height—that is, the minimum distance between the blade tip and the mold is no more than 5mm (usually between 5mm and 8mm). Since the thickness of a finger is typically greater than 10mm, compressing the protection blind zone to below 5mm physically reduces the possibility of a finger being pinched.

[0035] It should be noted that although the above describes the general functions of the external signal acquisition module, this is not limiting. Figure 7 As shown, for a bending machine with a foot pedal control circuit, the external signal acquisition module is preferably an optical fiber amplifier 5. The optical fiber amplifier 5 is connected in series in the foot pedal control circuit, and its signal output terminal (PNP output terminal) is electrically connected to the S1 terminal of the receiver 2. This is not the only connection method; those skilled in the art can also add an external relay 6 (or a small AC contactor) with high breaking capacity and arc extinguishing function for bending machines without a foot pedal control circuit, as needed. This adjustment does not deviate from the basic principles of the present invention and therefore will also fall within the protection scope of the present invention.

[0036] For older machine tools with risks of aging relay components or control lag, and for older machine tools without foot control circuits, the adaptive bypass control unit 4 also features a low-level hard cutoff function. For example... Figure 8 As shown, this mechanism physically isolates the low-voltage control circuit (typically 24V DC) from the high-voltage power circuit (typically 220V / 110V AC): In the low-voltage control circuit, the positive terminals of the power supplies of transmitter 1 and receiver 2 are physically short-circuited and powered in parallel by the same industrial switching power supply. Regardless of cable aging or external power fluctuations, both devices will either operate normally simultaneously or fail simultaneously due to power failure, eliminating the possibility of a "transmitter losing power and producing no light, but the receiver misinterpreting the beam as not being blocked due to residual capacitance," thus achieving forced synchronous failure safety. Simultaneously, the control signal output of fiber optic amplifier 5 and the output of receiver 2 are electrically connected to and control the low-voltage coil of the external relay 6.

[0037] In the high-voltage circuit, the normally open high-voltage contact of the external relay 6 is directly connected in series to the power supply live wire (L) circuit at the front end of the downward control solenoid valve inside the bending machine, and the other end of the solenoid valve is connected to the neutral wire (N). When the beam is blocked during the rapid downward stroke, causing the safety protection device to be triggered, the coil of the external relay 6 instantly loses its magnetism, and the armature is springed away by the spring force. At this time, through the built-in arc-extinguishing grid (in conjunction with the RC absorption network and other anti-arc circuits connected in parallel at both ends of the contact), the arc is lengthened, cut off, and cooled and extinguished in less than 3ms, thereby achieving a strong cut-off of the power supply live wire to the solenoid valve. After the power is cut off, the solenoid valve core resets, the upper die loses its downward power and is locked by the hydraulic circuit, preventing the possibility of old machine tools operating with defects, and ensuring that the solenoid valve and subsequent circuits achieve electrical isolation and a zero-potential safety state.

[0038] Phase 1 (0-5ms): When the operator's finger cuts off the laser protection beam during the rapid downward stroke, the digital signal processor (DSP) chip inside receiver 2 detects a precipitous drop in the number of photons within less than 2ms. Since the fiber amplifier 5 has not yet issued the "slow-down shielding" signal indicating that a safe gap has been reached, receiver 2 immediately determines that an "illegal obstruction" has occurred. The miniature pilot relay inside receiver 2 disconnects, cutting off the control current supplied to the coil of the external relay 6.

[0039] Second stage (5~10ms): The control coil of the external relay 6 loses its sustaining current (demagnetization). According to the law of electromagnetic induction, the magnetic flux inside the coil core decays rapidly, and the electromagnetic attraction force originally used to attract the armature decreases exponentially. When the electromagnetic attraction force is less than the tension of the reset spring inside the external relay 6, the armature is instantly snapped away, causing the normally open high-voltage contact connected in series on the power supply line of the solenoid valve to physically separate.

[0040] The third stage (10-15ms): At the instant the high-voltage contacts separate, because the solenoid valve coil is a highly inductive load, an extremely high-voltage arc will be generated in the contact gap in an attempt to maintain the current flow. The external relay 6, with its built-in arc-extinguishing grid or magnetic blowout device, elongates, cuts, and cools the arc to extinguish it in less than 3ms. At this point, the 220V AC live wire is cut off.

[0041] To ensure that the external relay 6 can hard disconnect without contact sticking under high voltage (220V / 110V AC) and highly inductive load (downward solenoid valve) conditions, a hardware anti-arc protection circuit (not shown) is connected in parallel across the normally open contacts of the external relay 6. An RC absorption network (preferably a 0.1μF / 630V high-voltage film capacitor connected in series with a 100Ω / 2W non-inductive resistor) or a metal oxide varistor (MOV) is used. At the instant of physical separation of the high-voltage contacts in the third stage (10~15ms), the extremely high back electromotive force and high voltage spike induced by the solenoid valve coil are instantly absorbed by the parallel RC absorption network (or clamped by the varistor). Through the external absorption circuit's discharge of transient high energy, combined with the mechanical reaction spring and arc-extinguishing grid built into the external relay 6, double physical protection ensures that the arc generated by the contact gap is reliably elongated, cooled, and completely extinguished within a time of no more than 3ms.

[0042] Phase 4 (after 15ms): The coil of the downward solenoid valve loses power, and its internal magnetic field collapses. The valve core returns to the neutral position under the action of the strong return spring. High-pressure hydraulic oil is released or bypassed back to the oil tank, and the main cylinder loses its downward thrust. Due to gravity, it will be locked by the machine tool balance valve or hydraulic locking circuit, and the upper die is pinned in mid-air within a few millimeters of sliding distance, thus ensuring the safety of the operator.

[0043] For bending machines with multi-stage foot pedal control circuits, an external signal acquisition module (fiber optic amplifier 5 or current detection module) is connected in series into the foot pedal control circuit of the bending machine. When the upper die is about to reach the safety critical height during rapid descent, the operator presses the foot pedal to the second stage (deep press). The fiber optic amplifier 5 detects the specific circuit current / voltage state change caused by the physical action of the foot pedal in real time and immediately outputs an independent slow-down signal to the S1 terminal of the receiver 2. By utilizing the operator's foot movement as the signal source, no additional sensors are required.

[0044] The specific physical judgment logic of the preset slow-down stroke trigger condition is as follows: Fiber optic amplifier 5 is connected to the second stage micro switch circuit of the foot pedal through the signal sampling terminal. When the bending machine foot pedal is in the first stage of stroke (lightly pressed), the machine tool performs a fast-down action, and the circuit maintains the basic operating current; when the operator presses the foot pedal deeply to the second stage of stroke, the second stage micro switch closes. This action generates a characteristic step voltage signal or current change in the circuit (for example, by connecting a fixed matching resistor in series in the second stage circuit, the circuit current jumps at the moment of closure).

[0045] The threshold comparator inside the fiber optic amplifier 5 acquires the electrical characteristics of the circuit in real time. Only when a specific rising edge is accurately captured and the level change exceeds the preset threshold is it determined that "the state change has reached the preset slow down travel trigger condition", and then an independent slow down signal is output. From an electrical and physical perspective, the only legal trigger source for fast / slow down switching is clearly defined, eliminating the risk of false triggering caused by noise from strong environmental vibrations, as well as the inability of a single pedal to distinguish the travel state.

[0046] For machine tools where precise position information cannot be obtained via a foot pedal, an external signal acquisition module includes a position detection sensor (not shown) (such as a limit switch, proximity switch, or photoelectric sensor) mounted on the side wall of the bending machine or the upper die guide rail. The position detection sensor (not shown) is configured to be mechanically triggered when the upper die descends rapidly to a safe critical height no more than 5 mm from the lower die, and sends a slow-down signal to the S1 terminal of receiver 2 to shield the protection state.

[0047] The following is combined Figures 2 to 6 This describes possible implementations of the bending machine bypass control method of the present invention.

[0048] like Figure 2 As shown, in one possible implementation, the bypass control method of this application includes the following steps: S101: A beam of light is emitted below the blade of the bending machine by transmitter 1 and received by receiver 2 to form a protective area; S102: The downward movement status of the bending machine is independently acquired through the external signal acquisition module in the adaptive bypass control unit 4; S103: Based on the obtained downward movement status, determine whether the bending machine is currently in the fast downward stroke or the slow downward stroke.

[0049] At any stage of the bending machine's operation, the external signal acquisition module continuously or intermittently acquires the machine tool's physical downward movement status. Based on this status change, the control logic decides whether intervention is needed for protection. If the bending machine is determined to be in the fast downward stroke, receiver 2 maintains a global anti-pinch protection state; if the bending machine is determined to be entering the slow downward stroke (the blade tip is about to contact the sheet metal), a high-level slow downward signal is output to receiver 2, triggering the shielding subroutine.

[0050] like Figure 3 As shown, in one possible implementation, for the processing of conventional flat sheet metal (i.e., sidewall structures without upward curling at the bent edges), the control method of this application includes the following steps: S201: If it is determined that the bending machine is in the fast downward stroke, the receiver 2 remains in the protection state; S202: When the beam within the protected area is detected to be blocked, the receiver 2 cuts off the signal of the external relay 6 in the output circuit within a response time of no more than 15ms, triggering the emergency stop of the bending machine; S203: If there is no obstruction during the fast descent process, when the slow descent switching point is reached, the external signal acquisition module sends a slow descent signal to the receiver 2.

[0051] The operator holds the flat sheet metal part with both hands and pushes it horizontally into the V-groove of the lower die of the bending machine, close to the back gauge finger. The operator then presses the foot pedal to start the rapid downward stroke. The beam emitted by transmitter 1 below the cutting edge forms a protective zone. At this time, if the operator's fingers are not withdrawn from the lower die area in time and block the beam, the digital signal processor chip inside receiver 2 determines that the number of photons has sharply decreased within 15ms and directly cuts off the control signal to the machine tool. The 15ms response reduces the mechanical inertial damage caused by the slow issuance of system commands.

[0052] like Figure 4 As shown, in one possible implementation, for machining deep-cavity box-shaped workpieces with raised sidewalls (folded box mode), when machining such workpieces, the sidewalls that have already been bent into shape will inevitably be raised high. Before the cutting edge even contacts the bottom of the workpiece, these raised sidewalls will prematurely cut off the light beam. A conventional grating would then interpret this as "finger intrusion" and force a shutdown, rendering the machine unable to work. The control method in this embodiment includes: S301: The operator initiates the rapid descent stroke; the beam is not blocked by the side wall, and the system provides protection. S302: When the blade tip beam is about to contact the highest point of the raised side wall of the box-shaped workpiece, the operator presses the foot pedal deeply or triggers the position detection sensor (not indicated) to cause the fiber amplifier 5 to generate a slow-down signal in advance and send it to the S1 terminal. S303: Receiver 2 enters a legal shielding protection state, allowing the beam to be completely cut off by the cold, hard sidewall without the hydraulic valve losing power, and the machine successfully completes the slow pressurization.

[0053] The operator places the semi-finished box-shaped workpiece into the lower mold. Its raised sidewalls are now higher than the upper plane of the lower mold. The operator initiates the rapid descent. In the initial stage of the blade's descent (high-risk zone), the beam is not blocked by the sidewalls, and the system provides anti-pinch protection. Due to the three-dimensional stepless adjustment function of the mechanical adjustment bracket 3, the optical axes of transmitter 1 and receiver 2 are pre-locked at a safe height of no more than 5mm directly below the blade tip. As the blade tip descends with the beam, and the beam is about to contact the highest point of the raised sidewalls of the box-shaped workpiece, the operator must depress the foot pedal to the second position (or the external signal acquisition module detects a specific position marker). At this time, the slow-descent signal is pre-triggered and sent to receiver 2, and receiver 2 enters a legal shielding protection state. Subsequently, the blade continues to descend, and the beam is completely cut off by the high-raised, cold, hard sidewalls of the workpiece. However, since the bending machine system has been legally shielded by the externally acquired signal at this time, the hydraulic valve of the bending machine will not lose power, and the upper die continues to press down smoothly until the final bending and pressurization of the bottom of the box is completed. Through the synergy of "spatial threshold locking" and "time advance shielding", the structural interference contradiction in the box folding process is resolved.

[0054] like Figure 5 As shown, in an optional implementation, for trial bending of high-precision aerospace sheet metal parts, or in operational scenarios with extremely high requirements of European CE standards, the control method of this application also provides a safety mode that forcibly stops at the shielding point. The specific implementation steps are as follows: S401: At the critical position of switching from fast to slow downward stroke (i.e., the shielding intervention point no more than 5mm away from the die), the external signal acquisition module generates a slow downward signal and sends it to receiver 2. However, at this time, the microprocessor inside receiver 2 does not immediately execute the shielding release command, but first outputs an "intermediate stop" signal, forcing the bending machine to pause in mid-air. At this time, the tip of the bending machine is suspended less than 5mm away from the sheet metal.

[0055] S402: During this physical pause, the operator visually checks whether the bending line of the sheet metal part coincides with the blade tip and whether the fingers are away from the danger zone.

[0056] S403: After confirmation, the operator performs a "secondary confirmation" action (such as releasing and pressing the foot pedal again, or pressing the dedicated reset release button) before the system is released from interlock, enters the shielded state, and allows the machine to complete slow pressing.

[0057] By breaking down the bending action into three independent stages—"rapid lowering warning—manual verification—slow lowering processing"—the safety margin for human-machine interaction during the processing of special high-risk workpieces is improved.

[0058] like Figure 6 As shown, in one possible implementation, since the bending machine needs to change the upper die (tool) and lower die of different heights when processing different workpieces, the change in die height will cause the originally aligned beam to shift. Therefore, in order to ensure the accuracy of the slow-down switching point and avoid the technical problem of "accidentally stopping the machine when bending a small part", this implementation also includes a method for locking the safety threshold height: S501: After the bending machine is stationary and the die is changed, place a 5mm thick test block flat on the upper surface of the V-groove of the lower die. S502: The bending machine is moved downwards in a jog motion, so that the tip of the upper die is pressed against the top of the test block. At this time, the physical distance between the tip of the upper die and the lower die is locked at 5mm. S503: Release the dual adjustable handle, move the mechanical adjustment bracket 3 downwards until the beam is blocked by the test block, and then fine-tune it upwards until the beam just brushes past the top of the test block; S504: Tighten the dual adjustable handle to completely lock the mechanical adjustment bracket 3 in this three-dimensional spatial coordinate, thereby precisely limiting the critical height of the slow stroke shielding intervention to a safe threshold of no more than 5mm.

[0059] After replacing the upper and lower dies, the operator places the bending machine in a static standby state with the slider at the top dead center. The operator then removes a metal or hard plastic test block with a precision thickness of 5mm. This 5mm test block is placed flat on the upper surface of the V-groove of the lower die. The operator then slowly lowers the bending machine by jogging until the tip of the upper die presses against the top of the 5mm test block. At this point, the actual physical distance between the tip and the lower die is locked at 5mm. Subsequently, the operator releases the vertical and horizontal adjustable handles on the mechanical adjustment bracket 3, allowing the transmitter 1 and receiver 2 to move freely. The operator then manually moves the mechanical adjustment bracket 3 downwards and observes the status indicator light on the receiver 2. When the beam emitted by transmitter 1 is just blocked by the 5mm test block (the indicator light changes from green to red), the bracket is then finely adjusted and raised by even 0.1mm, so that the beam just brushes past the top of the test block (the indicator light changes from red to green). At the exact moment, the operator immediately tightens the double adjustable handle to completely lock the mechanical adjustment bracket 3 in this three-dimensional spatial coordinate. The 5mm test block is then removed, and the machine tool is started to perform a no-load full-stroke test. This ensures that the beam always moves up and down with the cutting tip, and that the optical path remains unobstructed until it reaches the slow-down switching point 5mm away from the lower die, guaranteeing that the protection accuracy of the equipment does not drift throughout its entire lifespan.

[0060] Although embodiments of this application have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and all such modifications and variations fall within the scope defined by the appended claims.

Claims

1. A safety protection device for a bending machine, characterized in that, include: The transmitter (1) and receiver (2) are respectively installed on both sides of the blade of the bending machine to emit and receive a beam of light below the blade to form a protective area; A mechanical adjustment bracket (3) is used to support and adjust the position of the transmitter (1) and the receiver (2); as well as An adaptive bypass control unit (4) is independent of the original CNC system of the bending machine and is electrically connected to the transmitter (1) and receiver (2); The adaptive bypass control unit (4) includes an external signal acquisition module. The external signal acquisition module is configured to acquire the downward movement status of the bending machine without accessing the internal communication of the original CNC system, and output an independent slow downward signal to the receiver (2) accordingly, so that the receiver (2) maintains the protection status during the fast downward stroke of the bending machine and shields the current protection status when entering the slow downward stroke.

2. The safety protection device for a bending machine according to claim 1, characterized in that, The adaptive bypass control unit (4) is configured to adapt to a bending machine with a foot pedal control circuit, and the external signal acquisition module is an optical fiber amplifier (5). The fiber optic amplifier (5) is connected in series to the foot pedal control circuit of the bending machine. The signal output terminal of the fiber optic amplifier (5) is electrically connected to the receiver (2) to send the slow-down signal to the receiver (2).

3. The safety protection device for a bending machine according to claim 1, characterized in that, The adaptive bypass control unit (4) is configured to adapt to a bending machine without a foot pedal control loop or unable to obtain position information by foot pedal. The external signal acquisition module includes a position detection sensor installed on the side wall of the bending machine or the upper mold guide rail. The position detection sensor is configured to be triggered when the upper mold descends rapidly to a safe critical height, so as to send the slow descent signal to the S1 terminal of the receiver (2).

4. The bending machine safety protection device according to claim 2 or 3, characterized in that, The adaptive bypass control unit (4) also includes an external relay (6); The transmitter (1) and the receiver (2) are powered by the same switching power supply in parallel, and their positive power terminals are physically short-circuited. The coil of the external relay (6) is controlled by the output terminal of the external signal acquisition module and the output terminal of the receiver (2). The normally open contact of the external relay (6) is connected in series to the power supply circuit of the front end of the solenoid valve that controls the downward movement inside the bending machine. It is configured to forcibly cut off the power supply circuit of the solenoid valve by disconnecting its own contact if the beam is blocked during the rapid downward stroke.

5. The bending machine safety protection device according to any one of claims 1 to 4, characterized in that, The transmitter (1) is connected to a 3-core shielded cable, and the receiver (2) is connected to a 7-core shielded cable; The 7-core shielded cable includes an independently configured S1 terminal, which is configured to receive the slow-down signal. The transmitter (1) uses a Class I laser source with a divergence angle of no more than 1.5 mrad, and the overall response time of the safety protection device is no more than 15 ms.

6. The safety protection device for a bending machine according to claim 1, characterized in that, The mechanical adjustment bracket (3) is installed on the upper die of the bending machine and moves up and down synchronously with the upper die; The vertical adjustment dimension of the mechanical adjustment bracket (3) is 500mm to 600mm, and the horizontal extension dimension is 100mm to 150mm. The mechanical adjustment bracket (3) is equipped with a dual adjustable handle configured for stepless adjustment, so that at the critical position of switching from fast downward stroke to slow downward stroke, the transmitter (1) and the receiver (2) can be locked at a safe threshold height so that the minimum distance between the tip of the upper die and the lower die of the bending machine is no more than 5mm.

7. A bypass control method for a bending machine safety protection device based on any one of claims 1 to 6, characterized in that, Includes the following steps: Step S1: A light beam is emitted below the blade of the bending machine through the transmitter (1), and the light beam is received by the receiver (2) to form a protective area; Step S2: The downward movement status of the bending machine is independently acquired through the external signal acquisition module in the adaptive bypass control unit (4); Step S3: Based on the obtained downward movement status, determine whether the bending machine is currently in a fast downward stroke or a slow downward stroke; Step S4: If it is determined that the bending machine is in the fast downward stroke, the receiver (2) remains in a protective state and outputs a stop signal when the beam is blocked; If it is determined that the bending machine has entered the slow downward stroke, the external signal acquisition module outputs a slow downward signal to the receiver (2) so that the receiver (2) shields the protection state.

8. The bypass control method according to claim 7, characterized in that, The external signal acquisition module is an optical fiber amplifier (5). When the optical fiber amplifier (5) is connected in series to the foot pedal control circuit of the bending machine, the specific processes of steps S2 and S3 are as follows: The fiber amplifier (5) detects the changes in the circuit state caused by the foot pedal action in real time. When the state change is detected to reach the preset slow-down travel trigger condition, the fiber amplifier (5) generates the slow-down signal and sends it to the S1 terminal of the receiver (2).

9. The bypass control method according to claim 7, characterized in that, The external signal acquisition module includes a position detection sensor installed on the side wall of the bending machine or the upper die guide rail. When the position detection sensor is configured to acquire position information, the specific processes of steps S2 and S3 are as follows: The position detection sensor detects the change in the height position of the upper mold as it moves downwards in real time. When the upper mold is detected to have reached a safe critical height during rapid descent, the position detection sensor is triggered, generating the slow descent signal and sending it to the S1 terminal of the receiver (2).

10. The bypass control method according to any one of claims 7 to 9, characterized in that, The adaptive bypass control unit (4) also includes an external relay (6). When the normally open contact of the external relay (6) is connected in series in the power supply circuit of the solenoid valve that controls the downward movement inside the bending machine, the specific process of outputting the stop signal is as follows: The receiver (2) and the external signal acquisition module work together to de-energize the coil of the external relay (6) so that the normally open contact opens instantly, thereby forcibly cutting off the power supply circuit of the solenoid valve.

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