Analysis of Hot Push Expansion Tube Production Technology: F

Analysis of Production Technology for Thermal Expansion Tube Boring Machines: The Whole Process from Raw Materials to Precision Large-Diameter Steel Tubes The innovative thinking in the industrial field is making pipeline connections stronger and more precise. In the modern industrial system, thermal expansion tube boring machines, as a crucial metal processing equipment, play an irreplaceable role in the production of pipeline connection components. Whether it is the winding pipelines in the petrochemical sector or the high-pressure pipelines in the energy and power sectors, none of them can do without the support of this technology. This article will start with the basic principles of thermal expansion tube boring machines and thoroughly analyze the entire production process, as well as discuss their technological innovations and development trends. 01 Overview and Industrial Applications of Thermal Expansion Tube Boring Machines A thermal expansion tube boring machine is a specialized equipment for metal plastic forming, mainly producing various pipeline components through the pushing processing method. According to the encyclopedia, the thermal expansion tube forming process is "using a dedicated tube boring machine, core mold (commonly known as a core rod) and heating device to make the workpiece on the mold move forward under the push of the tube boring machine, and during the movement, it is heated and expanded into a formed shape." This equipment is widely used in pipeline system connection components production in industries such as petroleum, chemical engineering, power, and construction. The diameter of the tube坯 used is usually smaller than the diameter of the desired pipe， and the deformation process of the workpiece is controlled by the core mold to compensate for the thinning in other areas due to the expansion， thereby obtaining uniform wall thickness thermal expanded steel tubes. Compared with traditional casting or welding elbows， the products produced by thermal expansion tube boring machines have higher strength， better flow performance， and longer service life. Their forming process has the characteristics of beautiful appearance， uniform wall thickness， and continuous operation， and is suitable for mass production， thus becoming the main forming method for carbon steel， alloy steel， and stainless steel tube boring. 02 The Whole Production Process of Thermal Expansion Tube Boring Machines Raw material preparation and feeding The first step in the production of thermal expansion tube boring machines is raw material preparation， that is， the preparation of "mother tubes". According to research， thermal expansion seamless steel tubes are "processed from qualified mother tubes using medium-frequency heating combined with hydraulic pushing technology to form variable-diameter steel tubes." At the beginning of production， appropriately cut steel pipes are placed on the feeding platform and the feeding mechanism is responsible for accurately transporting the steel pipes to the processing position. A complete tube boring machine system includes feeding mechanisms， conveying mechanisms， supporting mechanisms， and other components. In high-end applications， the selection of mother tubes is particularly strict， and raw material chemical composition， appearance， and size inspections are carried out to ensure that the raw materials meet quality requirements. The core positioning and heating The core of the production process of thermal expansion tube boring machines is core positioning and heating. The core is the key mold that determines the size and shape of the final product， and requires precise installation and alignment. Thermal expansion tube boring machines have a dedicated centering clamping mechanism to fix the core and ensure it is in the correct position. According to patent literature， in a seamless steel tube thermal expansion tube processing method， the core head of the thermal expansion machine includes "core rod connection flange， feeding zone， variable diameter zone， sizing zone， finishing zone， and guiding zone." At the same time， the equipment is equipped with a heating system， usually using medium-frequency induction heating equipment. According to technical standards， the thermal expansion process requires precise control of temperature (650-950℃)， pushing speed (200-400mm/min)， and variable expansion rate (≤25%). The heating plate and medium-frequency coil are wrapped around the core rod. When the steel pipe approaches the core rod， the heating system starts to work and heats the end of the steel pipe to the appropriate plastic deformation temperature. Pushing and forming Pushing and forming is the core环节 of the entire production process. After the steel pipe is heated to the appropriate temperature， the feeding mechanism starts to work， the hydraulic cylinder pushes the sliding seat， the clamping mechanism tightly clamps the steel pipe， and pushes the steel pipe towards the core rod at a constant speed. During the pushing process， the steel pipe undergoes plastic deformation under the heating condition， and as the steel pipe is continuously pushed， it gradually forms along the curve shape of the core rod. This process requires precise control of the pushing speed and temperature to ensure uniform deformation of the material and avoid wrinkles or cracks. According to specific application requirements, an open method for seamless pipe hot expansion processing uses the process parameters of "hot expansion temperature 800-830℃, hot expansion speed 50±10mm/min", which expands a Φ426mm×19.5mm mother pipe into a Φ1120×15mm large-diameter pipe. Cooling and shaping The formed steel pipe needs to undergo cooling and shaping treatment. Since the pipe is formed at high temperature, it needs to be cooled under controlled conditions to eliminate internal stress and stabilize the structure. The cooling process should not be too rapid, otherwise it may cause deformation or excessive internal stress; nor should it be too slow, otherwise it will affect production efficiency. Some advanced hot push expansion pipe machine systems are equipped with controllable cooling devices, which can achieve precise control of the cooling process by adjusting the flow rate and temperature of the cooling medium. Subsequent processing and treatment The hot push expanded steel pipe needs to undergo subsequent processing, including shaping, beveling, etc. Shaping is to ensure that the size and shape of the steel pipe meet the standard requirements; beveling is to prepare for welding, ensuring that the steel pipe can be perfectly connected with the pipeline system. In addition, according to application requirements, the steel pipe may also need to undergo heat treatment, surface treatment, marking printing, etc. For high-standard applications, the steel pipe must undergo overall heat treatment! Post-hot expansion normalizing (or normalizing + tempering) can further refine the grain structure and eliminate residual stress. Finally, after strict quality inspection, qualified products can be packaged and shipped out. 03 Technical advantages of hot push expansion pipe machine The hot push expansion pipe machine for producing steel pipes has obvious technical advantages: Firstly, the hot push expansion pipe machine production is continuous, which greatly improves efficiency compared to single-piece production. Through reasonable mechanism design, the hot push expansion pipe machine can achieve semi-automation or even full automation production, reducing manual intervention and improving product consistency. Modern numerical control expansion pipe machines use computer numerical control technology to achieve automation and precision of the pipe forming process. Its system consists of a numerical control unit, servo drive, and actuating mechanism, and supports G-code programming and CAD model import. Secondly, the products produced by the hot push expansion pipe machine have better mechanical properties. Due to the continuity of the metal fiber structure being maintained and without the potential risks of weld seams like welded elbows, the service life and safety of the pushed pipe are higher. Studies have shown that the hot expansion process can refine the grain structure (grain size increased by 0.5-1.0 levels) and eliminate the original defects of the mother pipe (such as pores, porosity), improving the compactness of the structure. In addition, the hot push expansion pipe machine production also has the advantages of high material utilization and low production costs. Compared with traditional processing methods, the pushed production reduces material waste and conforms to the green and environmentally friendly development concept of modern manufacturing. The short process and low energy consumption (<320kWh/ton) of the hot expansion process make it particularly suitable for small-batch and multi-specification customization, with the delivery cycle shortened to 30 days. 04 Development trends of hot push expansion pipe production technology With the advancement of industrial technology, the hot push expansion pipe machine technology is also constantly innovating and developing: Increasing automation level: Modern hot push expansion pipe machines increasingly adopt automatic control systems to achieve precise control of temperature, speed, and pushing force, reducing the impact of human factors on product quality. For example, advanced equipment integrates PLC or servo systems to control expansion speed, pressure, and stroke, and some equipment supports bidirectional expansion, improving processing efficiency. Multifunctional integration: New hot push expansion pipe machines integrate feeding, pushing, shaping, beveling, and other functions, greatly improving production efficiency. Shrink-expansion integrated forming machines integrate expansion and reduction functions, and can complete the treatment of different diameters at both ends of the pipe material by replacing molds. Energy conservation and environmental protection: Modern expansion pipe machines place greater emphasis on energy utilization efficiency and environmental protection. Driven by the "dual carbon" goals, the expansion pipe machine industry is achieving a green transformation through technological innovation. The new hydraulic system adopts load sensing technology, reducing idle energy consumption by 40%; servo motor drives replace traditional asynchronous motors, with noise controlled below 75 decibels. Intelligent control: Advanced control systems and sensor applications enable expansion pipe machines to automatically adjust parameters, adapt to different materials and specifications for product production, and improve product quality stability. With the deep advancement of Industry 4.0, expansion pipe machines will further integrate Internet of Things and AI technologies, using big data analysis to predict mold life and achieving fault warning and remote diagnosis. 05 Quality Control and Standard Specifications The quality control of expansion pipe tubes involves the entire process and requires strict standard specifications to follow. For medium-frequency heat expansion seamless tubes used in high-pressure boilers, the T/CISA 002-2017 standard specifies key technical requirements such as outer diameter range (273-1220mm), wall thickness deviation (≤±7.5%), and impact energy requirements (≥34J, -20℃ environment). One standard clearly defines key technical indicators such as the outer diameter range (273-1220mm), wall thickness deviation (≤±7.5%), and impact energy requirements (≥34J, -20℃ environment). Heat treatment is a critical link to ensure the performance of expansion pipe tubes. After heat expansion, overall heat treatment must be carried out, such as normalizing or normalizing plus tempering, which can further refine the grain structure (increasing by 0.5-1.0 levels) and eliminate residual stress, restoring the toughness lost due to expansion. The inspection process is also indispensable. Factory inspection items include dimensional tolerances, water pressure test (pressure formula: p = 2St/D, S is 50% of yield strength), ultrasonic/eddy current testing, etc. For high-standard products, type tests are also required, such as high-temperature endurance tests (e.g., TP316H tubes need to pass a 650℃/134MPa test for 9000 hours) and grain size rating (≥7 levels). 06 Conclusion Expansion pipe machines, as key equipment for pipeline connection component production, have undergone years of development and improvement in production technology. From raw material preparation to the final product, every stage of expansion pipe machine production embodies the technical achievements of multiple fields such as mechanical design, material science, and automation control. With the continuous improvement of manufacturing levels, expansion pipe machine technology will continue to develop towards efficiency, precision, and intelligence, providing higher-quality and more reliable pipeline connection components for various industries, contributing to the construction of a modern industrial system. Expansion pipe machines, this specialized equipment, although not widely known to the public, play an indispensable role in the pipeline engineering field, serving as the "backstage heroes" of industrial infrastructure construction. Through continuous optimization of the production process of expansion pipe machines and improvement of product quality and performance, it will inject new impetus into China's industrial development. The industrial world progresses silently, precisely in these unseen details. A steel pipe undergoes heating, extrusion, and shaping, transforming into a pipeline that transports energy and resources to where they are needed. With the continuous emergence of new materials and new technologies, expansion pipe technology will continue to evolve, writing a new chapter for human industrial civilization.