A process for producing polyurethane foam jacketed pipe

Abstract

The application provides a polyurethane foam jacket heat preservation pipe production process, and belongs to the technical field of polyurethane foam jacket heat preservation pipe production.The polyurethane foam jacket heat preservation pipe production process has a hardware architecture comprising an electromagnetic induction detection unit, a stable voltage regulation power supply unit, an induction signal processing and voltage comparison control unit, a relay linkage execution control unit and an identification execution unit.In the scheme, the polyurethane foam jacket heat preservation pipe production process is based on an online joint automatic identification and laser marking linkage device based on the electromagnetic induction principle, and through electromagnetic induction detection, voltage comparison identification, relay linkage control and laser precise marking integration, full-automatic precise positioning and automatic identification of the heat preservation pipe joint are realized, the traditional manual line marking mode is replaced, and the automation level of the production line, the product qualification rate and the production stability are comprehensively improved.

Description

Technical Field

[0001] This invention relates to the field of polyurethane foam jacket insulation pipe production technology, and in particular to a polyurethane foam jacket insulation pipe production process. Background Technology

[0002] Polyurethane foam jacket insulated pipe (yellow jacket pipe) is the mainstream buried insulation pipe material for urban centralized heating and oil and gas transportation. Currently, the main production process is a one-step continuous extrusion foaming molding process, which has the advantages of high production efficiency and good sealing performance of one-piece molding. The one-step yellow jacket polyurethane insulation pipe production process is a three-in-one continuous molding process of continuous steel pipe feeding, simultaneous extrusion of HDPE outer protective layer, and continuous injection and curing of polyurethane foam. The production line operation process is as follows: seamless steel pipe is continuously conveyed at a uniform speed, the extruder simultaneously extrudes polyethylene outer protective shell, and the black and white material foaming system mixes the raw materials according to a precise ratio and continuously injects them into the annular cavity between the steel pipe and the outer protective layer. After curing and molding, a polyurethane insulation pipe with complete insulation layer structure and strong adhesion is formed.

[0003] The production line uses seamless industrial steel pipes as raw materials, with standard single-piece lengths ranging from 10 to 12 meters. The thickness of the finished insulation layer is generally controlled between 30 and 50 mm. During the production process, each steel pipe must be continuously fed and joined together. The joints are completely covered by an outer polyethylene sheath and polyurethane foam, making them completely concealed and indistinguishable to the naked eye after forming. Once all the pipes are formed, they must be precisely cut at the joint and fitted with waterproof end caps before they can be shipped as finished products. If the cut position deviates from the joint, the waterproof and insulation structure of the pipe will fail; if the deviation is too large, proper separation will be impossible, directly leading to a disruption in continuous production.

[0004] Traditional production relies on manual pre-judgment marking, manual alignment and marking, and manual pipe cutting and separation. It is highly dependent on manual intervention and suffers from large marking deviations, high labor intensity, frequent omissions in marking, and high scrap rates, which seriously restricts the level of continuous, standardized and automated production lines.

[0005] To address the drawbacks of manual joint finding and avoid issues such as joint positioning deviations, missing markings, waste pipe production, and losses from downtime and restart, this application proposes a production process for polyurethane foam jacket insulated pipes. Summary of the Invention

[0006] This invention provides a production process for polyurethane foam jacket insulation pipes to solve the technical problems of the drawbacks of manual jointing in existing polyurethane foam jacket insulation pipes.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A manufacturing process for polyurethane foam jacket insulation pipes. Including the overall system hardware architecture: The electromagnetic induction detection unit consists of a voltage regulating transformer, a voltage stabilizing power supply, a main coil assembly, a secondary coil assembly, and an insulating box. Two sets of insulating boxes are symmetrically fixed on both sides of the center line of the conveyor roller, and the center height of the coil can be adjusted by lifting. The voltage stabilizing and regulating power supply unit adopts a two-stage series power supply structure consisting of an AC voltage stabilizer and a single-phase voltage regulator. The inductive signal processing and voltage comparison control unit includes: 3300 rectifier module: converts the alternating induced voltage collected by the secondary coil assembly into a stable DC voltage; LM358 Adjustable Signal Amplifier: Supports continuous adjustment of amplification factor; YYV-1 Voltage Comparison Relay Module: Presets a voltage threshold, compares the measured DC voltage with the threshold in real time, and outputs an on / off switch signal based on the comparison result; The relay linkage execution control unit includes an intermediate relay and a multi-channel signal branch terminal block, which is used to receive the switching signal output by the voltage comparison module and control the laser marking machine to turn on and off; The marking execution unit is a laser marking machine.

[0008] Optionally, in the electromagnetic induction detection unit: The core parameters are: 50mm×48mm×240mm silicon steel sheet laminated core; The coil specifications are as follows: the main coil assembly uses Φ2mm glass-insulated copper wire with a total of 400 turns and is installed inside the inlet side insulation box; the auxiliary coil assembly uses Φ1mm enameled wire with a total of 1000 turns and is symmetrically arranged inside the outlet side insulation box. The identification basis is: the steel pipe butt joint uses non-magnetic connectors, and a 10-20mm gap is reserved after the ends of the two steel pipes are butted together to form a local magnetic reluctance change area, which serves as the basis for triggering electromagnetic induction signals.

[0009] Optionally, in the voltage stabilization and regulation power supply unit, the input terminal is connected to 220V industrial mains power, specifically: AC voltage stabilizer: Eliminates voltage fluctuations and instantaneous voltage drop interference in the workshop power grid, and stabilizes the output of alternating power supply; Single-phase voltage regulator: Steplessly adjusts the input alternating voltage of the main coil assembly.

[0010] Optionally, the signal processing link between the induction signal processing and voltage comparison control unit is as follows: The secondary coil assembly senses AC voltage → 3300 rectifier module converts DC to DC → LM358 amplifier provides adjustable amplification → YYV-1 voltage comparison module compares threshold values ​​→ switch relay signal output.

[0011] Optionally, in the identification execution unit, The laser marking machine uses a carbon dioxide laser flying marking system. The laser head is positioned directly above the center line of the transmission line connector detection device, horizontally aligned with the centers of the main and auxiliary coil assemblies, and vertically aligned with the axis of the transmission line. The laser marking machine's start switch is controlled by a relay from the detection output module, enabling simultaneous online marking of the connector position and product information, including: Online marking of joint positioning lines: Longitudinal centerline reference lines are marked on the outer wall of the pipe, with the center point of the marking line corresponding to the centerline of the steel pipe joint; Laser marking: Simultaneous etching of a unique traceability code for the pipe, which includes information such as production batch, nominal diameter of the pipe, wall thickness, production time, and production line number.

[0012] The manufacturing process of this polyurethane foam jacket insulation pipe also includes control logic, which includes the following steps: Step 1, System power-on debugging and parameter preset: When the equipment is powered on, the 220V mains power is connected to the voltage regulator unit. The AC voltage regulator automatically regulates the output of stable AC power, which is then regulated by a single-phase voltage regulator and supplied to the main coil assembly. The preset working voltage is 150V. When an alternating current is applied to the main coil assembly, the iron core generates a constant alternating magnetic field, and the secondary coil assembly generates a basic induced voltage through electromagnetic induction, the system enters standby detection mode. Reference parameter calibration: The conveying steel pipe passes through the central area of ​​the induction coil at a constant speed. The real-time DC voltage of the voltage comparison module digital tube is read. The amplification factor of the LM358 amplifier is adjusted to keep the detection voltage of the jointless steel pipe section stable at 8-9V. Trigger threshold setting: Operate the control panel of the YYV-1 voltage comparison module and fix the relay activation threshold voltage to 10V; Fixed logic rule: If the detection voltage is >10V, the relay is activated and turned on; if the detection voltage is <10V, the relay is deactivated and reset. Step 2: Inspection and marking of steel pipe sections: Seamless steel pipes pass through the central induction areas of the main coil assembly and the auxiliary coil assembly at a uniform speed via conveyor rollers. Signal link processing: The AC induced voltage of the secondary coil component is converted to DC by the 3300 rectifier module, and then amplified by the LM358 amplifier to output a stable 8-9V detection voltage; The YYV-1 voltage comparison module compares the measured voltage of 8-9V with the preset threshold of 10V in real time. If the measured voltage is lower than the threshold, the module will not output a switching signal. The intermediate relay coil is not powered and the contacts remain open, indicating that the equipment control circuit is open. The laser marking machine remains in standby mode when there is no trigger signal and does not perform etching marking operations; The steel pipe is continuously transported, and the system continuously collects the induced voltage, determines the magnetic resistance state of the medium, and continuously waits for the joint trigger signal. Step 3: The steel pipe joint enters the sensing area, triggering the identification and control process. The aluminum and plastic non-magnetic joint between the two steel pipes enters the coil induction area as the pipes move. There is no continuous magnetic metal medium within 10-20mm of the joint, the overall magnetic resistance of the circuit increases, and the induced voltage of the secondary coil rises synchronously. After amplification, the detected voltage exceeds the preset 10V threshold. The YYV-1 voltage comparison module recognizes the voltage exceeding the limit, outputs a high-level conduction signal, and drives the intermediate relay coil to be energized and engaged. When the normally open contact of the relay closes, a control signal is output to the trigger terminal of the laser marking machine, the laser marking machine starts, and begins to engrave the connector marking line; All connectors pass through the coil induction area, the induction medium is restored to a complete and continuous steel pipe, the circuit magnetic resistance drops back to the standard stable value, and the amplified detection voltage drops back to 8-9V. The YYV-1 voltage comparison module determines that the measured voltage is lower than the 10V threshold, cuts off the conduction output signal, de-energizes the intermediate relay coil, opens the normally open contact, disconnects the laser marking machine's start-up circuit, and stops the laser marking machine from marking the lines. Step 4: Once the connector is completely removed from the sensing area, the system will automatically reset. The laser marking machine's trigger signal synchronization was interrupted, stopping the laser etching operation. The signal processing circuit automatically resets, and the real-time voltage acquisition and threshold comparison logic continuously loops, waiting for the next group of steel pipe joints to enter the detection area. The single identification and marking control loop is completed. Step 5: Shutdown and Pipe Material Replacement Adjustment Procedure: When the production line stops, the voltage regulation power supply to the main coil assembly is cut off, and the induction detection unit stops outputting the magnetic field; the control module remains powered on and in standby mode, and all preset parameters are automatically saved and not lost when power is off.

[0013] The beneficial effects of the above-described technical solution of the present invention are as follows: This application establishes five functional units: an electromagnetic induction detection unit, a voltage regulation and control unit, an induction signal processing and voltage comparison control unit, a relay linkage execution control unit, and a marking execution unit. It collects induced voltage surge signals by measuring the magnetic reluctance difference between the steel pipe and the non-magnetic joint. After multi-level signal processing, it synchronously links with laser marking and laser traceability marking equipment to automatically mark the joint. The entire system is based on the principle of electromagnetic induction, creating an online automatic joint identification and laser marking linkage device. Through integrated technological upgrades of electromagnetic induction detection, voltage comparison identification, relay linkage control, and precise laser marking, it achieves fully automatic and precise positioning and marking of insulation pipe joints, replacing the traditional manual marking mode. It is unaffected by human eye or manual operation errors, eliminates the need for manual supervision of the marking process, and avoids problems such as human fatigue, obstructed vision, and missed marking due to inattention. This prevents emergency shutdowns and restart debugging processes caused by missed or incorrect marking, ensuring continuous and stable mass production on the production line, a smooth and orderly production rhythm, and significantly improving the effective production time and overall capacity of the production line. Attached Figure Description

[0014] Figure 1 The diagram shows the process structure of an existing one-step foam jacket tube production line. Figure 2 This is a schematic diagram of the electromagnetic induction circuit of the present invention; Figure 3 This is a structural diagram of an insulation pipe joint.

[0015] 1. Steel pipe; 2. Polyurethane mixing spray gun; 3. Polyethylene protective layer extrusion die; 4. Polyethylene protective layer; 5. Steel pipe continuous production joint; 6. Insulation layer; 7. Voltage regulating transformer; 8. Main coil assembly; 9. Secondary coil assembly; 10. Rectifier module; 11. Boost module; 12. Voltage detection output module. Detailed Implementation

[0016] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0017] like Figures 1 to 3 As shown, the embodiments of the present invention provide a production process for polyurethane foam jacket insulation pipes, which does not require modification of the original extrusion, foaming, and conveying host main structure. Only five functional units are added in the middle section of the conveying roller conveyor, with complete electrical control logic and a matching steel pipe joint structure. It is divided into two parts: the overall system hardware architecture and the control logic.

[0018] The overall hardware architecture of the system includes: an electromagnetic induction detection unit, a voltage regulation and control unit, an induction signal processing and voltage comparison control unit, a relay linkage execution control unit, and an identification execution unit.

[0019] In this embodiment, the electromagnetic induction detection unit serves as the detection unit: It consists of a voltage regulating transformer, a regulated power supply, a main coil assembly, a secondary coil assembly, and an insulation box. The core parameters are: 50mm×48mm×240mm silicon steel sheet laminated core; The coil specifications are as follows: the main coil assembly uses Φ2mm glass-insulated copper wire with a total of 400 turns and is installed inside the inlet side insulation box; the auxiliary coil assembly uses Φ1mm enameled wire with a total of 1000 turns and is symmetrically arranged inside the outlet side insulation box. The installation structure is as follows: two sets of insulating boxes are symmetrically fixed on both sides of the center line of the conveyor roller. The center height of the coil can be adjusted by lifting and lowering, and the adjustment range covers all specifications of steel pipes from DN40 to DN1200. The identification basis is: the steel pipe butt joint uses non-magnetic connectors, made of materials such as aluminum or plastic. After the ends of the two steel pipes are butted together, a gap of 10-20mm is reserved to form a local magnetic reluctance change area, which serves as the basis for triggering electromagnetic induction signals.

[0020] In this embodiment, the voltage stabilizing and regulating power supply unit: The input terminal is connected to 220V industrial mains power, and adopts a two-stage series power supply structure of AC voltage stabilizer and single-phase voltage regulator; AC voltage stabilizer: Eliminates voltage fluctuations and instantaneous voltage drop interference in the workshop power grid, and stabilizes the output of alternating power supply; Single-phase voltage regulator: Steplessly adjusts the input alternating voltage of the main coil assembly, adapts to steel pipes of different wall thicknesses and outer diameters, stabilizes the output strength of the induced magnetic field, and can quickly calibrate the detection reference voltage when changing pipe specifications.

[0021] In this embodiment, the sensing signal processing and voltage comparison control unit serves as the main electronic control module: The complete signal processing chain is as follows: AC voltage induced by the secondary coil component → DC-DC conversion by the 3300 rectifier module → adjustable amplification by the LM358 amplifier → threshold comparison by the YYV-1 voltage comparison module → output of the switch relay signal.

[0022] The functions of each module are as follows: 3300 rectifier module: converts the alternating induced voltage collected by the secondary coil assembly into a stable DC voltage; LM358 Adjustable Signal Amplifier: Supports continuous adjustment of amplification factor, adapts to steel pipes of different diameters and wall thicknesses, and provides a unified reference voltage for seamless pipe materials; YYV-1 Voltage Comparison Relay Module: It presets a voltage threshold, compares the measured DC voltage with the threshold in real time, and outputs an on / off switch signal based on the comparison result.

[0023] In this embodiment, the relay linkage execution control unit: The components are: intermediate relay, multi-channel signal branch terminal block; (the multi-channel terminal block is not used here. The original design was to link a sound and light alarm and an inkjet marking device. However, it was found in production that a laser marking machine could be used to mark the center line, so the inkjet marking was later cancelled.) The signal processing logic is as follows: receive the switch signal output from the voltage comparison module to control the laser marking machine to turn on and off; In this embodiment, the marking execution unit is a laser marking machine; Specifically, the laser marking machine uses a carbon dioxide laser flying marking machine. The laser head of the marking machine is positioned directly above the center line of the transmission line connector detection device, horizontally aligned with the centers of the main coil assembly and the auxiliary coil assembly, and vertically aligned with the axis of the transmission line. The laser marking machine start switch is controlled by the detection output module relay, enabling online simultaneous marking of the connector position and product information. Online marking of joint positioning lines: Longitudinal centerline reference lines are marked on the outer wall of the pipe. The center point of the marking line corresponds to the centerline of the steel pipe joint, providing a visual dividing reference for the subsequent cutting process. Laser marking: Simultaneous etching of a unique traceability code for the pipe, containing information such as production batch, nominal pipe diameter, wall thickness, production time, and production line number. The marking is wear-resistant, waterproof, and weather-resistant, and can be retained long-term for full-cycle traceability.

[0024] In this embodiment, the control logic includes the following steps: Step 1, System power-on debugging and parameter preset: When the entire equipment is powered on, the 220V mains power is connected to the voltage regulator unit. The AC voltage regulator automatically regulates the output of stable AC power, which is then regulated by a single-phase voltage regulator and supplied to the main coil assembly. The preset working voltage is 150V. When an alternating current is applied to the main coil assembly, the silicon steel core generates a constant alternating magnetic field, and the secondary coil assembly generates a basic induced voltage through electromagnetic induction, the system enters standby detection mode. Reference parameter calibration: The conveying steel pipe passes through the central area of ​​the induction coil at a constant speed. Read the real-time DC voltage of the digital tube of the voltage comparison module. Adjust the amplification factor of the LM358 amplifier to keep the detection voltage of the jointless steel pipe section stable at 8-9V. This calibration step does not need to be repeated when changing the pipe material specifications. Trigger threshold setting: Operate the control panel of the YYV-1 voltage comparison module and fix the relay activation threshold voltage to 10V; Fixed logic rule: If the detection voltage is >10V, the relay is activated and turned on; if the detection voltage is <10V, the relay is deactivated and reset.

[0025] Step 2: Inspection and marking of steel pipe sections, joint-free normal operation: The seamless steel pipe passes through the central induction area of ​​the main coil assembly and the auxiliary coil assembly at a constant speed via the conveyor rollers. The steel pipe is a high-permeability magnetic medium, the overall magnetic reluctance of the circuit is stable, and the induced voltage of the auxiliary coil assembly remains constant. Signal link processing: The AC induced voltage of the secondary coil component is converted to DC by the 3300 rectifier module, and then amplified by the LM358 amplifier to output a stable 8-9V detection voltage; The YYV-1 voltage comparison module compares the measured voltage (8-9V) with the preset threshold (10V) in real time. If the measured voltage is lower than the threshold, the module will not output a switching signal. The intermediate relay coil is not powered and the contacts remain open, indicating that the equipment control circuit is open. The laser marking machine remains in standby mode when there is no trigger signal and does not perform etching marking operations; The steel pipe is continuously transported, and the system continuously collects the induced voltage, determines the magnetic resistance state of the medium, and continuously waits for the joint trigger signal. Step 3: The steel pipe joint enters the sensing area, triggering the identification and control process. The aluminum / plastic non-magnetic joint between the two steel pipes enters the coil induction area as the pipes travel. There is no continuous magnetic metal medium within 10-20mm of the joint, and the overall magnetic resistance of the circuit increases significantly, causing the induced voltage of the secondary coil to rise synchronously. After amplification, the detected voltage exceeds the preset 10V threshold. The YYV-1 voltage comparison module recognizes the voltage exceeding the limit and immediately outputs a high-level conduction signal to drive the intermediate relay coil to be energized and engaged. When the normally open contact of the relay closes, the control signal is output to the trigger terminal of the laser marking machine, the laser marking machine starts, and begins to mark the connector marking line.

[0026] All connectors pass through the coil induction area, the induction medium is restored to a complete and continuous steel pipe, the circuit magnetic resistance drops back to the standard stable value, and the amplified detection voltage drops back to 8-9V. When the YYV-1 voltage comparison module determines that the measured voltage is below the 10V threshold, it immediately cuts off the output signal, the intermediate relay coil is de-energized, and the normally open contact opens; the laser marking machine's start-up circuit is disconnected, and the laser marking machine stops marking lines. Step 4: Once the connector is completely removed from the sensing area, the system will automatically reset. The laser marking machine's trigger signal synchronization was interrupted, stopping the laser etching operation. The signal processing circuit automatically resets, and the voltage acquisition and threshold comparison logic continuously cycle, waiting for the next group of steel pipe joints to enter the detection area. The single identification and marking control cycle is completed.

[0027] Step 5: Shutdown and Pipe Material Replacement Adjustment Procedure: When the production line stops, the voltage regulation power supply to the main coil assembly is cut off, and the induction detection unit stops outputting the magnetic field; the control module remains powered on and in standby mode, and all preset parameters are automatically saved and not lost when power is off. Complete adaptation steps for replacing steel pipes with different outer diameters / wall thicknesses: The center height of the lifting coil insulation box should match the outer diameter of the new tubing. Adjust the height of the laser marking machine to match the current pipe height.

[0028] In this embodiment, the automatic identification and synchronization job control process is as follows: The marking is achieved by the built-in software function of the laser marking machine. The machine is controlled by external IO signals to start and stop automatically marking the joint marking line on the outer layer of plastic. This is based on the built-in delay marking function of the software. Program sequence: External trigger ON → Draw line → Trigger OFF → Stop drawing line → Delay → Encode → End and wait for the next trigger; wiring: Connect the output wire of the YYV-1 voltage comparator module to the marking machine control card (this machine uses EzCad): IN0: One end of the switch GND: The other end of the switch Switch closed = triggers line drawing; switch open = stops line drawing. Software settings; Program sequence: External trigger ON → Draw line → Trigger OFF → Stop drawing line → Delay → Mark and mask → End and wait for the next trigger Software settings: Draw a "thin straight line" (0.3–3mm, adjust according to actual needs); Create a new file → Draw a horizontal line (length = effective width of the pipe); Parameters: Speed ​​3000–5000 mm / s, power 50–75%, frequency 50 kHz; Set to FlyingMarking mode → Draw continuous lines as the pipe moves; Add a "delay" (after the switch is turned off): Insert a Timer (delay unit) → Set the delay time (e.g., 1500ms = 1.5 seconds); Add "Identification Code / Product Information": After a delay, insert text / QR code / serial number; Contents: batch number, time, specifications, traceability code, etc.; Location: Downstream of the straight line (direction of pipe travel); Configure "external trigger, stop logic"; Triggering method: Starts on rising edge, stops on falling edge; When the pipeline joint passes the detection position, the external control I / O of the laser marking machine is activated, and the laser marking machine begins to engrave the joint marking line. When the joint leaves the detection position, the external control I / O of the laser marking machine is deactivated, and the marking machine stops marking. Because the marking is in flight mode and the laser marking head is located directly above the detection device, the center of the marked line is the joint position.

[0029] After the connector leaves the detection position, the laser marking machine's IO control disconnects, triggering the marking machine's delay control mode. After a delay of 1.5 seconds, the marking program starts. Once the marking is completed, the entire program ends and waits for the next trigger. This setting can be adjusted according to the pipeline production speed and printing position. For example, with a pipeline speed of 6 meters per minute, the printing position is set to 300mm behind the connector, with a delay of 1.5 seconds.

[0030] In a further embodiment, the existing one-step foam jacket tube production line lacks an automated joint identification and marking device; joint positioning relies entirely on manual completion of the entire marking process. The process structure is as follows: Figure 1 As shown, the complete process is as follows: Pre-treatment marking: Before steel pipe 1 enters the foaming molding feeding station, workers manually draw scale markings at a position 1000mm from the end of each steel pipe; Online real-time manual observation and marking: When the steel pipe joint is delivered to the extruder head, the operator keeps a close eye on the high-speed moving pipe. When the pre-marked scale line on the steel pipe enters the extruder head, a black marking line is manually drawn on the surface of the HDPE outer sheath 1000mm behind the head. Back-end cutting and matching: Operators at the cutting station rely on manual marking of the pipe's outer wall to complete the pipe cutting, sorting, and end sealing operations.

[0031] Meanwhile, to prevent polyurethane foam from seeping into the gaps between steel pipes during the molding process, a sealing plastic film needs to be wrapped around the outside of the joint. The film will further obscure the outline of the joint, increasing the difficulty of manual identification.

[0032] This invention provides a production process for polyurethane foam jacketed insulated pipes, which employs non-contact electromagnetic induction automatic identification and marking linkage control. By leveraging the difference in magnetic permeability between the steel pipe and the non-magnetic material joint, non-contact fully automatic identification of steel pipe joints is achieved. Concealed steel pipe joints can be automatically identified without manual supervision, and intuitive cutting benchmark markings and permanent laser traceability codes are output simultaneously, realizing full automation of joint identification and marking processes. This eliminates human error and downtime due to missed inspections, reduces labor and raw material costs, improves the automation level of the production line, and establishes a full-cycle traceability system for pipe materials.

[0033] In this embodiment: Electromagnetic induction circuit schematic diagram (refer to) Figure 2 As shown: Voltage regulating transformer 7 is the core of the voltage stabilization and regulation power supply unit; Main coil assembly 8 is the alternating magnetic field emitting end; Sub-coil assembly 9 is the induced voltage acquisition terminal; Rectifier module 10, type 3300, is used for AC to DC conversion; The boost amplifier module 11 is an LM358 adjustable signal amplifier; Voltage detection output module 12 is a YYV-1 voltage comparison relay module; Steel pipe 1 is a high-permeability magnetic metal medium; Steel pipe splice joint 5 is located in the low magnetic resistance abrupt change region.

[0034] Refer to the structural diagram of the insulation pipe joint Figure 3 As shown: Connector material: The entire connector is made of non-magnetic aluminum or engineering plastic in one piece. External dimensions: The maximum outer diameter of the joint is exactly the same as the outer diameter of the steel pipe, and the axial width of the joint in the middle is 10-20mm; End structure: The two ends of the connector are machined with an inward tapered shape, which can be inserted into the steel pipe to facilitate the connection of two steel pipes. The diameter of the middle part is the same as the outer diameter of the pipe, so as to avoid scraping the extrusion die during pipe transportation. Connection gap: After the ends of the two steel pipes are joined, a uniform gap of 10-20mm is reserved to form a stable local magnetic reluctance change zone, which provides a clear and interference-free voltage change trigger signal for the electromagnetic induction system, ensuring 100% accuracy of joint identification; Installation method: The steel pipes are connected end to end and then sleeved and fixed, and transported synchronously with the steel pipes; after the pipes are cut, the joints are removed and can be sent to the previous process for reuse.

[0035] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A manufacturing process for a polyurethane foam jacket insulation pipe, characterized in that, Including the overall system hardware architecture: The electromagnetic induction detection unit consists of a voltage regulating transformer, a voltage stabilizing power supply, a main coil assembly, a secondary coil assembly, and an insulating box. Two sets of insulating boxes are symmetrically fixed on both sides of the center line of the conveyor roller, and the center height of the coil can be adjusted by lifting. The voltage stabilizing and regulating power supply unit adopts a two-stage series power supply structure consisting of an AC voltage stabilizer and a single-phase voltage regulator. The inductive signal processing and voltage comparison control unit includes: 3300 rectifier module: converts the alternating induced voltage collected by the secondary coil assembly into a stable DC voltage; LM358 Adjustable Signal Amplifier: Supports continuous adjustment of amplification factor; YYV-1 Voltage Comparison Relay Module: Presets a voltage threshold, compares the measured DC voltage with the threshold in real time, and outputs an on / off switch signal based on the comparison result; The relay linkage execution control unit includes an intermediate relay and a multi-channel signal branch terminal block, which is used to receive the switching signal output by the voltage comparison module and control the laser marking machine to turn on and off; The marking execution unit is a laser marking machine.

2. The production process of the polyurethane foam jacket insulation pipe according to claim 1, characterized in that, In the electromagnetic induction detection unit: The core parameters are: 50mm×48mm×240mm silicon steel sheet laminated core; The coil specifications are as follows: the main coil assembly uses Φ2mm glass-insulated copper wire with a total of 400 turns and is installed inside the inlet-side insulation box; The secondary coil assembly uses Φ1mm enameled wire with a total of 1000 turns, symmetrically arranged inside the discharge side insulation box; The identification basis is: the steel pipe butt joint uses non-magnetic connectors, and a 10-20mm gap is reserved after the ends of the two steel pipes are butted together to form a local magnetic reluctance change area, which serves as the basis for triggering electromagnetic induction signals.

3. The production process of the polyurethane foam jacket insulation pipe according to claim 2, characterized in that, In the voltage stabilization and regulation power supply unit, the input terminal is connected to 220V industrial mains power, specifically: AC voltage stabilizer: Eliminates voltage fluctuations and instantaneous voltage drop interference in the workshop power grid, and stabilizes the output of alternating power supply; Single-phase voltage regulator: Steplessly adjusts the input alternating voltage of the main coil assembly.

4. The production process of the polyurethane foam jacket insulation pipe according to claim 3, characterized in that, The signal processing link for the inductive signal processing and voltage comparison control unit is as follows: The secondary coil assembly senses AC voltage → 3300 rectifier module converts DC to DC → LM358 amplifier provides adjustable amplification → YYV-1 voltage comparison module compares threshold values ​​→ switch relay signal output.

5. The production process of the polyurethane foam jacket insulation pipe according to claim 4, characterized in that, In the identification execution unit, The laser marking machine uses a carbon dioxide laser flying marking system. The laser head is positioned directly above the center line of the transmission line connector detection device, horizontally aligned with the centers of the main and auxiliary coil assemblies, and vertically aligned with the axis of the transmission line. The laser marking machine's start switch is controlled by a relay from the detection output module, enabling simultaneous online marking of the connector position and product information, including: Online marking of joint positioning lines: Longitudinal centerline reference lines are marked on the outer wall of the pipe, with the center point of the marking line corresponding to the centerline of the steel pipe joint; Laser marking: Simultaneous etching of a unique traceability code for the pipe, which includes information such as production batch, nominal diameter of the pipe, wall thickness, production time, and production line number.

6. The manufacturing process of the polyurethane foam jacket insulation pipe according to claim 1, characterized in that, The manufacturing process of this polyurethane foam jacket insulation pipe also includes control logic, which includes the following steps: Step 1, System power-on debugging and parameter preset: When the equipment is powered on, the 220V mains power is connected to the voltage regulator unit. The AC voltage regulator automatically regulates the output of stable AC power, which is then regulated by a single-phase voltage regulator and supplied to the main coil assembly. The preset working voltage is 150V. When an alternating current is applied to the main coil assembly, the iron core generates a constant alternating magnetic field, and the secondary coil assembly generates a basic induced voltage through electromagnetic induction, the system enters standby detection mode. Reference parameter calibration: The conveying steel pipe passes through the central area of ​​the induction coil at a constant speed. The real-time DC voltage of the voltage comparison module digital tube is read. The amplification factor of the LM358 amplifier is adjusted to keep the detection voltage of the jointless steel pipe section stable at 8-9V. Trigger threshold setting: Operate the control panel of the YYV-1 voltage comparison module and fix the relay activation threshold voltage to 10V; Fixed logic rule: If the detection voltage is >10V, the relay is activated and turned on; if the detection voltage is <10V, the relay is deactivated and reset. Step 2: Inspection and marking of steel pipe sections: Seamless steel pipes pass through the central induction areas of the main coil assembly and the auxiliary coil assembly at a uniform speed via conveyor rollers. Signal link processing: The AC induced voltage of the secondary coil component is converted to DC by the 3300 rectifier module, and then amplified by the LM358 amplifier to output a stable 8-9V detection voltage; The YYV-1 voltage comparison module compares the measured voltage of 8-9V with the preset threshold of 10V in real time. If the measured voltage is lower than the threshold, the module will not output a switching signal. The intermediate relay coil is not powered and the contacts remain open, indicating that the equipment control circuit is open. The laser marking machine remains in standby mode when there is no trigger signal and does not perform etching marking operations; The steel pipe is continuously transported, and the system continuously collects the induced voltage, determines the magnetic resistance state of the medium, and continuously waits for the joint trigger signal. Step 3: The steel pipe joint enters the sensing area, triggering the identification and control process. The aluminum and plastic non-magnetic joint between the two steel pipes enters the coil induction area as the pipes move. There is no continuous magnetic metal medium within 10-20mm of the joint, the overall magnetic resistance of the circuit increases, and the induced voltage of the secondary coil rises synchronously. After amplification, the detected voltage exceeds the preset 10V threshold. The YYV-1 voltage comparison module recognizes the voltage exceeding the limit, outputs a high-level conduction signal, and drives the intermediate relay coil to be energized and engaged. When the normally open contact of the relay closes, a control signal is output to the trigger terminal of the laser marking machine, the laser marking machine starts, and begins to engrave the connector marking line; All connectors pass through the coil induction area, the induction medium is restored to a complete and continuous steel pipe, the circuit magnetic resistance drops back to the standard stable value, and the amplified detection voltage drops back to 8-9V. The YYV-1 voltage comparison module determines that the measured voltage is lower than the 10V threshold, cuts off the conduction output signal, de-energizes the intermediate relay coil, opens the normally open contact, disconnects the laser marking machine's start-up circuit, and stops the laser marking machine from marking the lines. Step 4: Once the connector is completely removed from the sensing area, the system will automatically reset. The laser marking machine's trigger signal synchronization was interrupted, stopping the laser etching operation. The signal processing circuit automatically resets, and the real-time voltage acquisition and threshold comparison logic continuously loops, waiting for the next group of steel pipe joints to enter the detection area. The single identification and marking control loop is completed. Step 5: Shutdown and Pipe Material Replacement Adjustment Procedure: When the production line stops, the voltage regulation power supply to the main coil assembly is cut off, and the induction detection unit stops outputting the magnetic field; the control module remains powered on and in standby mode, and all preset parameters are automatically saved and not lost when power is off.

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