Double-wall corrugated pipe fixed-length device, fixed-length cutting equipment and fixed-length method

Abstract

The invention relates to the technical field of plastic pipe machining equipment, in particular to a double-wall corrugated pipe length fixing device, fixed-length cutting equipment and a length fixing method. The length control device comprises a mounting frame, a mounting seat, a top block, a laser transmitter and a laser receiver; the top block is used for applying downward pressure to the passing corrugated pipe so as to establish a stable detection reference; the optical axes of the laser transmitter and the laser receiver are located on the same horizontal line, and the horizontal line is arranged on the horizontal plane tangent to the wave trough of the outer wall of the corrugated pipe. According to the length fixing method, length accumulation calculation is carried out by acquiring pulse signals generated by wave crests and wave troughs alternately passing through an optical path; and when the accumulated length reaches the preset cutting length, the system enters a to-be-cut locking state, and the edge of the light passing signal of the next trough is monitored so as to immediately trigger the cutting mechanism. Measurement errors caused by pipe conveying shaking can be eliminated, the cutting position is accurately controlled to be located in the center of the trough all the time, and the product percent of pass is increased.

Description

Technical Field

[0001] This application relates to the technical field of plastic pipe processing equipment, and in particular to a double-wall corrugated pipe length-fixing device, length-fixing cutting equipment and length-fixing method. Background Technology

[0002] Double-wall corrugated pipes, with their alternating crests and troughs on the outer wall, possess excellent ring stiffness, light weight, and low cost, and are widely used in municipal engineering for drainage and sewage, communication cable sheathing, and farmland irrigation. A key step in their continuous extrusion production process is the online fixed-length cutting of long pipes to standard lengths (e.g., 6 meters, 9 meters).

[0003] However, the unique geometry of the bellows presents two long-standing technical challenges for precise cutting: Inaccurate length measurement: For smooth, solid-walled pipes, the industry commonly uses an encoder roller pressed against the pipe wall, calculating the pipe's travel length by measuring the roller's circumference. This method is simple and effective. However, when applied to corrugated pipes, the encoder roller bounces rhythmically up and down with the crests and troughs of the pipe wall, causing the roller's rolling path to be longer than the actual axial movement of the pipe. This results in significant cumulative measurement errors, leading to inconsistent final product lengths and a low pass rate.

[0004] Strict requirements apply to the cutting location: To ensure the structural integrity and strength of the pipe end after cutting, and to facilitate subsequent connections using sockets, sealing rings, etc., industry standards and construction specifications require that the cutting point must be precisely located at the center of the trough between two corrugations. If the cutting location deviates from the trough, especially when cutting on a corrugation, it will damage the pipe's annular reinforcing structure, causing stress concentration and severely affecting the pipe's pressure-bearing capacity and connection sealing performance, constituting a serious quality defect.

[0005] To address the above problems, the existing technologies mainly include the following solutions: Option 1: Mechanical Induction Plate Type. This option involves placing a metal induction plate or linkage mechanism above the pipe that floats up and down with the wave crest. A photoelectric switch or proximity switch detects when the mechanism reaches its highest point (corresponding to the wave crest). This method is an indirect measurement, complex to install and debug, and the mechanical contact parts are prone to wear and loosening during long-term high-frequency movement, leading to drift of the detection reference point and poor long-term stability and accuracy. Furthermore, it primarily senses wave crests and lacks the ability to directly locate wave troughs.

[0006] Option 2: Single-point laser displacement sensor. This option uses a single laser displacement sensor vertically mounted on the top of the pipe. It determines the peaks (closest) and troughs (farthest) by measuring the real-time distance from the laser to the pipe surface. However, in actual production, the corrugated pipe inevitably experiences overall vertical or horizontal movement on the conveyor belt or traction machine. This overall pipe positional shift is superimposed on the height changes caused by the peaks and troughs, severely interfering with the measurement signal and making the controller prone to incorrect judgments. The reliability of this option is significantly reduced, especially when the pipe position fluctuates.

[0007] Therefore, developing a device that can directly and accurately identify the trough position of a corrugated pipe regardless of the overall positional fluctuation of the pipe, and based on this, achieve high-precision fixed-length cutting, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a double-wall corrugated pipe length-fixing device, length-fixing cutting equipment and length-fixing method, aiming to solve the technical problems of inaccurate length measurement and difficulty in accurately controlling the cutting position at the trough in the double-wall corrugated pipe cutting in the prior art.

[0009] In a first aspect, this application provides a double-walled corrugated pipe length-fixing device, which adopts the following technical solution: A double-walled corrugated pipe length-fixing device, comprising: Mounting bracket for connection to cutting equipment; The mounting base is vertically slidably connected to the mounting frame and can move vertically; the mounting base has two oppositely arranged mounting plates; a corrugated pipe can pass through between the two mounting plates; The top block, positioned between the two mounting plates and fixed to the mounting base, is used to apply downward pressure to the bellows; The laser emitter and laser receiver are fixed on different mounting plates, and the optical axes of the laser emitter and laser receiver are on the same horizontal line; and this horizontal line is set on a horizontal plane that is tangent to the trough of the outer wall of the corrugated pipe; when the corrugated pipe moves forward horizontally at a constant speed, its peaks and troughs will alternately pass through the optical path of the laser beam.

[0010] By adopting the above technical solution, the top block can be used to apply downward pressure to the corrugated pipe, effectively suppressing the vertical jump of the corrugated pipe during the transmission process and establishing a stable detection benchmark. At the same time, by using the through-beam optical path composed of a laser emitter and receiver, and precisely setting the optical axis at the height of the trough section, the peaks and troughs of the corrugated pipe can produce clear physical obstruction and light transmission changes when passing through, thereby realizing non-contact trough identification. This solves the problems of easy slippage and wear of traditional mechanical rollers leading to inaccurate length measurement, as well as the problem of single-point laser being greatly interfered with by pipe vibration.

[0011] Secondly, this application provides a fixed-length cutting device for double-wall corrugated pipes, which adopts the following technical solution: A double-walled corrugated pipe fixed-length cutting device includes a cutting control unit electrically connected to a laser emitter and a laser receiver, used to receive and count laser pulse signals, and control the cutting actuator to cut the corrugated pipe.

[0012] By adopting the above technical solution, the high-precision detection device is integrated with the control unit and the cutting mechanism, realizing automated processing from signal acquisition and logic operation to cutting execution, ensuring precise synchronization between the cutting action and the position of the bellows.

[0013] Thirdly, this application provides a method for fixing the length of a double-walled corrugated pipe, which adopts the following technical solution: A method for determining the length of a double-walled corrugated pipe, applied to a corrugated pipe cutting device equipped with a through-beam laser detection component and a cutting mechanism, includes the following steps: S1. Detection signal acquisition: Acquire the pulse signal output by the through-beam laser detection component; the optical axis height of the through-beam laser detection component is preset at the cross-section of the trough diameter of the bellows, so that when the peak passes through, an obstruction signal is output, and when the trough passes through, a light transmission signal is output. S2. Length Accumulation Calculation: Identify the effective signal edge representing the valley in the pulse signal, count the number of valleys N, and calculate the current cumulative length L of the bellows in real time according to the formula L=N×P, where P is the preset bellows pitch. S3, Cutting Timing Control: When the cumulative length L is less than the preset cutting length, the system maintains the counting state; When the cumulative length L reaches or exceeds the preset cutting length, the system enters the waiting-to-cut lock state; In the waiting-to-cut locked state, the system monitors the next incoming trough light signal. Once the rising edge of the trough light signal is detected, a trigger command is immediately sent to the cutting mechanism to complete the fixed-point cutting.

[0014] By adopting the above technical solution, the traditional method of triggering cutting solely based on length values ​​is abandoned. Instead, a control logic of "count accumulation + waiting-to-cut lock + signal edge triggering" is used. After the length is reached, the system does not cut immediately but remains locked, waiting for the next defined trough signal edge. This ensures that the cutting tool's movement is always directly triggered by the physical location of the trough, fundamentally eliminating the possibility of cutting on the crest and guaranteeing the process requirement that the cut is located in the center of the trough. By transferring the triggering power of the cutting command from the "length value" to the "trough signal edge," the influence of accumulated errors and mechanical delays on the cutting phase is eliminated.

[0015] Preferably, the time interval T between two adjacent valley optical signals is calculated; Obtain the traction speed V of the corrugated pipe by the corrugated pipe cutting equipment, and calculate the theoretical corrugation period Tn=P / V; Set the allowable deviation range coefficient k, and determine whether (1-k)T≦Tn≦(1+k)T; If the conditions are met, the current signal is determined to be a valid counting signal; If the condition is not met and Tn≦(1-k)T, then it is determined to be a jitter interference signal, and the signal is filtered out without increasing the number of valleys N.

[0016] By adopting the above technical solution, a dynamic filtering algorithm based on speed and period is introduced, which can effectively identify and filter out false pulse signals caused by burrs, stains or sudden violent vibrations on the pipe surface, prevent counter malfunction, and further improve the anti-interference ability and accuracy of length measurement.

[0017] Preferably, in step S3, the cut-to-lock state further includes a cut fault tolerance mechanism: While the system enters the waiting-to-be-locked state, a monitoring window with a duration of Ta is opened; If a light transmission signal is detected in the valley within Ta, then normal cutting is performed; If no wave trough light signal is detected after exceeding Ta, the corrugated pipe cutting equipment will execute the following strategy depending on the situation: a) If the pipe stops moving, wait; b) If the signal is abnormal, alarm and pause; c) If it is determined to be a single signal missed, trigger cutting at the next confirmed wave trough signal to ensure that the final cutting position is still in the wave trough.

[0018] By adopting the above technical solutions, the robustness of the system is increased, preventing the equipment from waiting indefinitely or producing excessively long scrap products due to sensor failure, foreign object obstruction, or signal loss in the "waiting to cut locked" state, thus ensuring the safety and continuity of the production process.

[0019] Preferably, the duration Tb of the laser pulse signal remaining in the same state is monitored in real time; Set an abnormal threshold time Tx, where the abnormal threshold time is greater than a single theoretical ripple period; If the Tb of the obstruction signal is greater than Tx, it is determined that the pipe is blocked or the laser is malfunctioning, triggering a shutdown alarm; If the Tb of the light transmission signal is greater than Tx, it is determined that the pipe is broken or the transmission has stopped, the pause length is accumulated and an alarm is triggered.

[0020] By adopting the above technical solution, real-time diagnosis of the production line status is achieved by utilizing the time domain characteristics of the signal. This enables timely detection of serious faults such as "pipe blockage", "pipe breakage" or sensor failure, thus preventing equipment damage or causing greater production accidents.

[0021] Preferably, before step S1, a height calibration step for the through-beam laser detection component is included to ensure that the optical axis height of the laser detection component is located at the trough diameter section of the bellows.

[0022] By adopting the above technical solution, it is ensured that the hardware installation position meets the requirements of the detection principle, which is a prerequisite for obtaining high-quality peak and valley signals.

[0023] Preferably, the height calibration step adopts the parameter table method, which records the standard specification code of the bellows and the corresponding trough diameter parameter; and calculates the theoretical laser beam height value H = trough diameter / 2 + installation reference offset of the through-beam laser detection component.

[0024] By adopting the above technical solutions, rapid model changeover and parameter setting can be achieved in standardized production scenarios, reducing manual debugging time and improving production efficiency.

[0025] Preferably, the height calibration step employs an adaptive calibration method, including: Manually pull the bellows to move; Control the raising and lowering of the through-beam laser detection component within a certain range; The waveform characteristics of the laser pulse signal are monitored. When the amplitude of the pulse signal switching on and off is at its maximum, the height of the through-beam laser detection component is set as the working height.

[0026] By adopting the above technical solution, for non-standard pipes or situations lacking standard parameters, the system can automatically find the optimal detection position through signal feedback, making the system more adaptable.

[0027] Preferably, the adaptive calibration method also includes low-speed trial cutting to observe whether the cut is located at the center of the trough; and adjusting the height of the through-beam laser detection component according to whether the cut is positioned too high or too low.

[0028] By adopting the above technical solution, mechanical installation errors and signal delays of the electronic control system can be compensated, and the detection height can be finely adjusted in reverse based on the actual cutting effect, thereby further improving the cutting accuracy to the optimal state.

[0029] In summary, the present invention has at least one of the following beneficial technical effects: 1. This invention solves the problems of inaccurate length measurement caused by mechanical encoder fluctuations in traditional corrugated pipe cutting, and the problem of cut deviation from the center of the corrugation trough due to the lack of precise sensing of the trough position. This application achieves high signal-to-noise ratio non-contact detection by stabilizing the physical position of the pipe with a top block and using a laser beam oriented along the optical axis of the trough. 2. An innovative control method of "length counting + waiting to be cut + trough edge triggering" is proposed to ensure that the moment the cutting command is issued is strictly anchored at the instant the trough passes through the optical axis. Logically, this ensures that the cutting position is necessarily located in the trough, which greatly improves the cutting quality and connection sealing of the finished pipe. 3. It possesses a comprehensive signal anti-interference and fault diagnosis mechanism. By eliminating jitter interference through a filtering algorithm based on theoretical cycles, and identifying pipe blockage, pipe breakage, and sensor faults through monitoring windows and duration thresholds, it significantly improves the long-term reliability and intelligence level of the equipment. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the overall structure of the double-walled corrugated pipe length-fixing device in the embodiments of this application; Figure 2 This is a schematic diagram of the partial structure of the fixed-length cutting device and the assembly structure of the fixed-length device in the embodiments of this application.

[0031] The following labels are used in the attached diagram: 1. Mounting bracket; 11. Sleeve; 2. Mounting base; 21. Bracket; 22. Support; 221. Mounting plate; 3. Top block; 4. Laser emitter; 5. Laser receiver; 6. Frame; 7. Support platform; 8. Corrugated pipe. Detailed Implementation

[0032] The following is in conjunction with the appendix Figures 1-2 The present invention will be described in further detail below.

[0033] To address the insufficient cutting accuracy caused by the lateral and vertical bending fluctuations of the corrugated pipe 8 during movement, this application discloses a double-wall corrugated pipe length-fixing device, length-fixing cutting equipment, and length-fixing method.

[0034] In the first aspect, this application discloses a double-walled corrugated pipe length-fixing device, which is mainly installed after the cooling and shaping section and before the cutting machine in the corrugated pipe 8 extrusion production line, and is used to detect the travel length and trough position of the corrugated pipe 8 in real time.

[0035] The device includes a mounting frame 1 and a mounting base 2. The mounting frame 1 is fixed to the ground or a production line machine. In this embodiment, the mounting frame 1 is specifically mounted on a cutting device such as a pipe cutter. The mounting frame 1 has a sleeve 11, and the mounting base 2 has a vertical support 21 that is inserted into the sleeve 11. A locking bolt handle is provided on the sleeve 11 to fix and adjust the vertical support 21.

[0036] Mounting base 2 also includes a support 22 with an inverted U-shaped or portal frame structure, which has two opposing mounting plates 221. The distance between the two mounting plates 221 is greater than the outer diameter of the corrugated pipe 8 to be cut, allowing the corrugated pipe 8 to pass through. The bottom of the corrugated pipe 8 is supported by a support platform 7 (or conveyor belt, rollers, etc.) on the production line.

[0037] To address the issue of vertical bouncing of the corrugated pipe 8 during transport due to uneven elasticity or traction, this device is specially equipped with a top block 3. The top block 3 is positioned between two mounting plates 221 and fixed to the mounting frame 1. When the corrugated pipe 8 passes through, the top block 3 contacts the top (crown tip) of the corrugated pipe 8 and applies a certain downward pressure, causing the bottom of the corrugated pipe 8 to adhere tightly to the support platform 7. This forcibly regulates the vertical position of the corrugated pipe 8 and establishes a stable detection benchmark.

[0038] Specifically, the mounting base 2 is provided with a vertical guide shaft, which is inserted into the top block 3 from above and slides into the top block 3, so that the top block 3 can move freely vertically within a certain range and press against the bellows 8 by its own weight.

[0039] The top block 3 can be made of polytetrafluoroethylene plastic, which can provide a smoother contact surface, reduce the friction between the top block 3 and the bellows 8, and thus reduce the elastic bounce of the bellows 8 caused by friction. The core detection component in this embodiment is a through-beam laser detection assembly, including a laser emitter 4 and a laser receiver 5, which are fixed on mounting plates 221 on both sides. The height of the mounting base 2 is adjusted so that the optical axis (optical path) formed by the laser emitter 4 and the laser receiver 5 is on the same horizontal line. The height of the mounting base 2 can be adjusted up and down to precisely set the optical axis height between the laser emitter 4 and the laser receiver 5 to a horizontal plane tangent to the trough of the outer wall of the corrugated pipe 8.

[0040] Because the outer wall of the double-walled corrugated pipe 8 is composed of alternating crests and troughs, the outer diameter of the crest is larger than the outer diameter of the trough 42. When the optical axis is located at the height of the trough diameter section: When the wave crest passes the optical axis, the solid part of the wave crest will block the laser beam, and the laser receiver 5 will not receive a signal (or will receive a low level), and will output a "blocking signal". When the trough passes through the optical axis, since this height is exactly the gap between the wave crests, the laser beam can be received by the laser receiver 5 through this gap (or received with a high level), and output a "light-transmitting signal".

[0041] Therefore, when the bellows 8 moves forward horizontally at a constant speed, its crests and troughs alternately pass through the laser beam path, and the laser receiver outputs a continuous pulse signal perfectly synchronized with the corrugation cycle. Each complete pulse cycle (i.e., from one trough to the next) represents the pitch of one corrugation. The controller multiplies the corrugation count by the known corrugation pitch. For a specific model of bellows 8, the corrugation pitch is a fixed value, thus accurately calculating the length of the pipe's advance. This method is a direct measurement and is unaffected by the vertical movement of the pipe. Secondly, this application discloses a fixed-length cutting device for double-wall corrugated pipes 8. The mechanical structure includes a frame 6, a support platform 7, and the aforementioned double-wall corrugated pipe length-fixing device. For automated control, it includes a cutting control unit. The cutting control unit is electrically connected to a laser emitter 4 and a laser receiver 5, and is used to receive and count laser pulse signals, and control the cutting actuator (e.g., a rotary cutter head, a flying saw, etc.) to cut the corrugated pipe 8. The cutting control unit can be a PLC or a dedicated controller.

[0042] The cutting control unit counts by receiving pulse signals and calculates the length of the bellows 8. When the length of the bellows 8 reaches the set cutting length, the cutting control unit sends a control signal to control the cutting actuator to cut the bellows 8. Thirdly, this embodiment also discloses a method for fixing the length of a double-walled corrugated pipe 8 based on the above-mentioned device, which is executed by a cutting control unit (such as a PLC or a dedicated controller), and mainly includes the following steps: S1. Signal Acquisition The cutting equipment is powered on and running, and the traction machine drives the bellows 8 to move at a constant speed. The through-beam laser detection component continuously outputs pulse signals with varying high and low levels.

[0043] During this process, the cutting control unit monitors in real time. Because dust or mechanical vibration may exist in the production environment, the system employs "de-jitter filtering logic" to prevent misjudgments. The cutting control unit reads the production line traction speed V in real time (e.g., obtained through the traction machine encoder, or a preset fixed value) and knows the current pipe corrugation pitch P.

[0044] Calculate the theoretical ripple period Tn = P / V.

[0045] Record the time interval T between the rising edges of two adjacent trough optical signals in real time. Set the deviation coefficient k (e.g., k=0.2).

[0046] Judgment condition: If (1-k)Tn≦T≦(1+k)Tn, then it is determined to be a valid trough signal and enters the counting process. For example, when k=0.2 and 0.8T≦Tn≦1.2T, it means that it is a valid trough signal and the counting is valid.

[0047] If T < (1-k)Tn, it indicates that a signal jump occurred in a very short time, usually caused by burrs on the pipe surface or instantaneous vibration of the optical path. The system judges this as an interference signal, filters it out, and the counter does not increase.

[0048] If all signals are valid trough signals, the cutting control unit will generate a pulse waveform that strictly corresponds to the physical period of the ripple.

[0049] S2, Length Cumulative Calculation The system identifies valid valley light-transmitting signals after filtering. Each time a rising edge of a valley signal is detected (i.e., the instant the optical path changes from being blocked to being open), the valley counter N is incremented by 1.

[0050] The cumulative length L of the current bellows 8 is calculated in real time according to the formula L=N×P. For example, if the wave pitch P=50mm and the target length is 6000mm, then N=120 wave troughs need to be accumulated.

[0051] S3, Cutting Timing Control (Core Logic) To ensure cutting accuracy, the system does not blindly cut the moment the length is reached, but instead employs a "wait-to-cut lock" strategy: Hold state: When the cumulative length L < preset cutting length (e.g., L < 6000 mm), the system only counts and displays, and does not output action signals.

[0052] Waiting-to-cut lock: When the cumulative length L reaches or just exceeds the preset cutting length (e.g., the count reaches 120), the system enters the "waiting-to-cut lock state". At this time, although the length is sufficient, the cutting tool may not be aligned with the center of the trough.

[0053] Precise Triggering: In the "waiting-to-cut locked state," the system focuses on the detection signal, waiting for the next trough light-transmitting signal. Once the rising edge of this signal is detected (meaning a new trough has just entered the optical path), the cutting control unit immediately sends a trigger command to the cutting actuator. By transferring the triggering authority of the cutting command from the "length value" to the "trough signal edge," the influence of accumulated errors and mechanical delays on the cutting phase is eliminated.

[0054] Since there is usually a fixed physical distance between the optical axis detection point and the cutting blade landing point, the control unit will add a delay compensation Tn based on this fixed distance and the traction speed V, so that the blade accurately hits the center of the trough when it falls. Furthermore, to prevent indefinite cutting due to a malfunction in the through-beam laser detection component (leading to excessively long waste tubes), the system activates a monitoring window timer and defines a monitoring window with a duration of Ta. The duration Ta is set to 1.5 to 2.0 times the theoretical cycle Tn.

[0055] When the length of the bellows reaches the set cutting length and enters the "waiting to cut locked state", if the cutting control unit detects the valley light signal in Ta, it will cut normally and reset the timer.

[0056] If the cutting control unit fails to detect the trough light signal after the specified time (Ta), the corrugated pipe cutting equipment will execute the following strategy: a) If the pipe stops moving, wait. For example, if the trough light signal is not triggered for 10 or 20 consecutive seconds, it indicates that the pipe has stopped moving, and an alarm will be output immediately. If the laser pulse signal is retried during this period, it is considered that the pipe is still moving, and no alarm will be output; b) If the signal is abnormal, an alarm will be triggered and the process will pause, such as when the pipe is damaged, or when the laser transmitter 4 and laser receiver 5 are covered with dust and cannot receive signals normally; c) If it is determined that a single signal is missed, cutting will be triggered on the next confirmed trough signal to ensure that the final cutting position is still in the trough. In addition, the cutting control unit detects the laser pulse signal and monitors the time Tb during which the laser pulse signal remains in the same state. A threshold Tx is set (e.g., 3 times the theoretical ripple period).

[0057] If the signal is blocked for more than Tx, it indicates that there may be a "pipe blockage" or laser damage, and the machine should be stopped and an alarm should be triggered immediately.

[0058] If the duration of the light transmission signal exceeds Tx, it indicates a possible "tube breakage" or material shortage, and the counting should be paused. Furthermore, in order to accurately align the optical axis with the trough, this method provides calibration steps: Method 1: Parameter table method, suitable for standardized production.

[0059] The cutting control unit 6 has a pre-stored parameter table recording the standard trough diameter D for different specifications of corrugated pipes (such as DN200, DN300, DN400). The mounting base 2 is equipped with a scale or displacement sensor. When changing pipe specifications, the operator enters the pipe model number in the system interface. The system prompts or automatically adjusts the height of the mounting base 2, ensuring that the theoretical laser beam height H = trough diameter / 2 + the fixed installation height deviation from the mounting base to the support platform.

[0060] Method 2: Adaptive calibration method, suitable for non-standard pipes or fine-tuning.

[0061] The bellows sample is introduced into the device, and the bellows is moved at a low speed by traction or manual traction, enabling the through-beam laser detection component to detect the peaks and troughs of the wave and output pulse signals normally. The mounting base is controlled to slowly descend from the highest point, or finely adjusted up and down at a preset position.

[0062] The cutting control unit analyzes the received pulse signal waveform: When the optical axis is too high, the light always passes through without pulses; When the optical axis is too low (cutting into the root of the wave crest), the transmission time is extremely short and the pulse duty cycle is extremely small; The pulse signal is clearest and the amplitude of the on / off changes is stable when the optical axis is exactly at the trough of the wave. This height is then locked. A test cut is then performed, and the operator observes the cut position. If the cut is biased to the left of the wave peak, the triggering is too early; if it is biased to the right, the triggering is too late. Final calibration is performed by fine-tuning the physical height of the through-beam optical axis or by adjusting the software parameters of the cutting control unit and the delay compensation Tn. The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A device for fixing the length of a double-walled corrugated pipe, characterized in that, include: Mounting bracket (1); The mounting base (2) is vertically slidably connected to the mounting frame (1) and can move vertically; the mounting base (2) has two oppositely arranged mounting plates (221); the corrugated pipe (8) passes between the two mounting plates (221); The top block (3) is positioned between the two mounting plates (221) and fixed to the mounting base (2), and is used to apply downward pressure to the bellows (8); The laser emitter (4) and the laser receiver (5) are fixed on different mounting plates (221), and the optical axes of the laser emitter (4) and the laser receiver (5) are on the same horizontal line; and the horizontal line is set on a horizontal plane that is tangent to the trough of the outer wall of the corrugated pipe (8); when the corrugated pipe (8) moves forward horizontally at a constant speed, its peaks and troughs will alternately pass through the optical path of the laser beam.

2. A fixed-length cutting device for double-wall corrugated pipes, characterized in that, The device includes a cutting control unit and the double-walled corrugated pipe length-fixing device as described in claim 1. The cutting control unit is electrically connected to the laser emitter (4) and the laser receiver (5) to receive and count laser pulse signals and control the cutting actuator to cut the corrugated pipe (8).

3. A method for fixing the length of a double-walled corrugated pipe, characterized in that, Applied to a bellows (8) cutting device equipped with a through-beam laser detection assembly and a cutting mechanism, the following steps are included: S1. Detection signal acquisition: Acquire the pulse signal output by the through-beam laser detection component; The optical axis height of the through-beam laser detection component is preset at the trough diameter section of the bellows (8), so that when the peak passes through, an obstruction signal is output, and when the trough passes through, a light transmission signal is output; S2, Length cumulative calculation: Identify the effective signal edge representing the valley in the pulse signal, count the number of valleys N, and calculate the cumulative length L of the current bellows (8) in real time according to the formula L=N×P, where P is the preset bellows pitch; S3, Cutting Timing Control: When the cumulative length L is less than the preset cutting length, the system maintains the counting state; When the cumulative length L reaches or exceeds the preset cutting length, the system enters the waiting-to-cut lock state; In the waiting-to-cut locked state, the system monitors the next incoming trough light signal. Once the rising edge of the trough light signal is detected, a trigger command is immediately sent to the cutting mechanism to complete the fixed-point cutting.

4. The method for fixing the length of a double-walled corrugated pipe according to claim 3, characterized in that, Calculate the time interval T between two adjacent valley optical signals; Obtain the traction speed V of the corrugated pipe (8) by the corrugated pipe (8) cutting equipment, and calculate the theoretical corrugation period Tn=P / V; Set the allowable deviation range coefficient k, and determine whether (1-k)Tn≦T≦(1+k)Tn is satisfied; If the conditions are met, the current signal is determined to be a valid counting signal; If the condition is not met and Tn≦(1-k)T, then it is determined to be a jitter interference signal, and the signal is filtered out without increasing the number of valleys N.

5. The method for fixing the length of a double-walled corrugated pipe according to claim 3, characterized in that, In step S3, the cut-to-lock state also includes a cut fault tolerance mechanism: While the system enters the waiting-to-be-locked state, a monitoring window with a duration of Ta is opened; If a light transmission signal is detected in the valley within Ta, then normal cutting is performed; If no wave valley light signal is detected after exceeding Ta, the corrugated pipe (8) cutting equipment will execute the following strategy depending on the situation: a) If the pipe stops moving, wait; b) If the signal is abnormal, alarm and pause; c) If it is determined that a single signal is missed, the cutting will be triggered on the next confirmed wave valley signal to ensure that the final cutting position is still in the wave valley.

6. The method for fixing the length of a double-walled corrugated pipe according to claim 3, characterized in that, Real-time monitoring of the duration Tb during which the laser pulse signal remains in the same state; Set an abnormal threshold time Tx, where the abnormal threshold time is greater than a single theoretical ripple period; If the Tb of the obstruction signal is greater than Tx, it is determined that the pipe is blocked or the laser is malfunctioning, triggering a shutdown alarm; If the Tb of the light transmission signal is greater than Tx, it is determined that the pipe is broken or the transmission has stopped, the pause length is accumulated and an alarm is triggered.

7. The method for fixing the length of a double-walled corrugated pipe according to claim 3, characterized in that, Before step S1, a height calibration step for the through-beam laser detection component is also included, so that the optical axis height of the laser detection component is located at the trough diameter section of the bellows (8).

8. The method for fixing the length of a double-walled corrugated pipe according to claim 7, characterized in that, The height calibration step adopts the parameter table method, which records the standard specification code of the bellows (8) and the corresponding trough diameter parameter; and calculates the theoretical laser beam height value H = trough diameter / 2 + installation reference offset of the through-beam laser detection component.

9. The method for fixing the length of a double-walled corrugated pipe according to claim 7, characterized in that, The altitude calibration step employs an adaptive calibration method, including: Manually pull the bellows (8) to move; Control the raising and lowering of the through-beam laser detection component within a certain range; The waveform characteristics of the laser pulse signal are monitored. When the amplitude of the pulse signal switching on and off is at its maximum, the height of the through-beam laser detection component is set as the working height.

10. The method for fixing the length of a double-walled corrugated pipe according to claim 9, characterized in that, The adaptive calibration method also includes low-speed trial cutting to observe whether the cut is located at the center of the trough; and adjusting the height of the through-beam laser detection component according to whether the cut position is too high or too low.

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