Three-way pipe fitting extrusion forming die and three-way pipe fitting extrusion forming method thereof

Abstract

The invention belongs to the technical field of metal plastic forming, and provides a three-way pipe fitting extrusion forming die and a three-way pipe fitting extrusion forming method. The device comprises an outer sleeve mold, a first core mold and a second core mold which are arranged in the outer sleeve mold, and a main punch used for extrusion, and further comprises an active heat management module, an antifriction flow promoting module and a collaborative demolding module, the device comprises an ejection mechanism used for ejecting the first core mold and the second core mold, the ejection mechanism is a hydraulic cylinder, and the hydraulic cylinder is connected with the active heat management module and the antifriction flow promoting module. A force sensor and a displacement sensor are integrated on the ejector rod. The method comprises the following steps that 1, a blank is prepared and heated; step 2, preheating a mold and placing a blank; step 3, performing; step 4, core extrusion; step 5, pressure maintaining and shaping; and 6, cooperative demolding is conducted, specifically, a, air cooling micro-shrinkage is conducted, b, sectioning shrinkage is conducted, c, servo control ejection is conducted, and d, a forge piece is ejected.

Description

Technical Field

[0001] This invention relates to the field of metal plastic forming technology, specifically to a tee pipe extrusion molding die and a tee pipe extrusion molding method thereof. Background Technology

[0002] Tee fittings are critical connectors in piping systems and are widely formed using hot extrusion. As shown in CN106424509A, existing technologies often employ combined dies and multiple punches to extrude high-temperature billets in stages. However, this method has significant drawbacks: First, the dies (especially the punches) are subjected to intense thermal cycles and high-pressure friction when repeatedly in contact with billets at approximately 1200°C, making them prone to thermal fatigue, softening, and wear, resulting in a short lifespan and high production costs. Second, the significant frictional resistance hinders metal flow, often causing defects such as insufficient branch filling, internal corner folding, and surface scratches, leading to unstable forming quality. Furthermore, the large clamping force on the mandrel after cooling makes forced demolding prone to workpiece deformation, surface damage, or damage to the wedge-shaped surface of the die.

[0003] Currently, industry improvements are mostly focused on developing higher-performance mold steels or optimizing lubricants, which are incremental improvements at the material level.

[0004] Therefore, we propose a device that actively manages and controls the interaction between the mold and the workpiece through multi-field coupling, thereby solving the above-mentioned problems. Summary of the Invention

[0005] To address the deficiencies in the prior art, this invention provides a tee pipe fitting extrusion molding die and a tee pipe fitting extrusion molding method, thereby solving the problems raised in the background art.

[0006] In a first aspect, the present invention provides a tee pipe fitting extrusion molding die, comprising an outer mold, a first core mold and a second core mold disposed within the outer mold, and a main punch for extrusion; further comprising an active thermal management module, which includes a partitioned cooling channel, a thermocouple sensor, and an intelligent temperature control unit; the partitioned cooling channel is disposed in the high-temperature working area of ​​the die; the thermocouple sensor is used to monitor the die temperature; the intelligent temperature control unit dynamically adjusts the cooling medium parameters flowing through the cooling channel according to the feedback from the thermocouple sensor; a friction reduction and flow promotion module, which includes an ultrasonic vibration generator connected to the main punch, used to apply axial high-frequency vibration to the main punch during extrusion; and a surface functional layer disposed on the cavity surface of the die in contact with the blank, the surface functional layer including a wear-resistant lubricating layer; and a collaborative demolding module, which includes an ejection mechanism for ejecting the first core mold and the second core mold respectively, the ejection mechanism being a hydraulic cylinder, the ejector rod integrating a force sensor and a displacement sensor.

[0007] Furthermore, the partitioned cooling channel includes an inner channel for the main punch and an outer mold channel. In practical applications, the purpose of this design is to achieve cooling in key areas. On the one hand, it reduces the impact of temperature differences on the mold equipment and also reduces the impact on the tee fittings; on the other hand, both the inner channel for the main punch and the outer mold channel are connected to an external cooling source, which facilitates control.

[0008] Furthermore, the surface functional layer also includes a wear-resistant lubricating layer and a ceramic thermal barrier layer; the wear-resistant lubricating layer is an array of micro-pits for lubrication; the ceramic thermal barrier layer is located below the wear-resistant lubricating layer and serves as thermal insulation. In practical applications, the micro-pit array used in this wear-resistant lubricating layer is designed to retain lubricating substances, such as lubricating oil or grease, within the micro-pit array, thereby improving the lubrication effect and facilitating subsequent demolding. The ceramic thermal barrier layer serves as thermal insulation.

[0009] Furthermore, the collaborative demolding module also includes: the second core mold is a segmented assembly structure, and its interior is provided with a driving mechanism for driving the segment blocks to contract radially; both the first core mold and the second core mold are provided with an air-cooling channel connected to a high-pressure air source.

[0010] Secondly, the present invention provides a method for extruding a tee fitting, comprising the following steps: Step 1. Heat the billet to the plastic molding temperature and place it into the mold; Step 2. Activate the active thermal management module to preheat the mold; Step 3. Perform pre-forming; Step 4. Core extrusion stage: Drive the main punch to perform extrusion, while simultaneously activating the ultrasonic vibration generator to apply ultrasonic vibration, and dynamically control the mold temperature through the intelligent temperature control unit; Step 5. Pressure holding and initial cooling; Step 6. Collaborative demolding stage: The core mold is separated from the forging and ejected through the collaborative demolding module.

[0011] Furthermore, in step S4, the intelligent temperature control unit controls the working temperature of the contact area between the mold and the blank within the range of 350°C to 450°C.

[0012] Furthermore, step S6 includes: S6a. High-pressure cooling gas is introduced into the air-cooling channels inside the first and second core molds to cause the core mold surface to shrink. S6b. Start the electro-hydraulic servo ejection system to simultaneously eject the first core mold and the second core mold under closed-loop control of force and displacement; When the second core mold is a segmentable structure, before step S6b, its segments are driven to contract radially inward.

[0013] As can be seen from the above technical solution, the beneficial effects that need to be retained according to the comparison and analysis between the present invention and the claims are as follows: Compared with the prior art, the present invention has the following significant advantages: Firstly, mold life is significantly improved: the active thermal management module, through its zoned cooling channels and intelligent temperature control, avoids localized overheating and thermal shock in the mold; the surface functional layer in the friction-reducing and flow-promoting module effectively resists thermal wear. The synergy of these two components significantly extends the mold's service life.

[0014] Meanwhile, forming quality and precision are comprehensively improved: in the friction-reducing and flow-promoting module, ultrasonic vibration effectively reduces deformation resistance and friction coefficient, promoting metal flow; the functional layer and microtexture on the cavity surface further improve material filling and surface quality. This ensures complete filling of complex structures and high dimensional accuracy of forgings.

[0015] Moreover, the demolding process is reliable and damage-free: the collaborative demolding module achieves precise control of force and displacement through the ejection mechanism with integrated sensors. Combined with the split core mold structure and air-cooled shrinkage method, it systematically solves the problem of high-temperature clamping and realizes the smooth and damage-free separation of the forging and the mold.

[0016] Finally, the overall process energy consumption is reduced and controllability is enhanced: technologies such as ultrasonic vibration reduce forming extrusion pressure, thereby reducing energy consumption. At the same time, sensors and intelligent control units integrated into each module enable real-time monitoring and closed-loop control of key process parameters such as temperature, force, and displacement, improving the stability and intelligence level of the process. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, the elements or parts are not necessarily drawn to scale.

[0018] Figure 1 This is a schematic diagram of the front view structure of the tee pipe fitting extrusion molding die provided in an embodiment of the present invention; Figure 2 for Figure 1 The enlarged structural diagram at point A is shown below; Figure 3 A schematic flowchart of the extrusion molding method for tee fittings is provided for this invention; Figure label: Outer mold 1, first core mold 2, second core mold 3, first punch 4, main punch 5, second punch 6, ultrasonic vibration generator 8, amplitude transformer 81, main punch inner flow channel 51, high-strength cooling zone 52, balanced cooling zone 53, outer mold flow channel 11, microgroove 101, micro-dimple 102, petal block 31, spherical ejector rod 32, thermocouple sensor 201, intelligent temperature control unit 200, surface functional layer 300, force sensor 91 and displacement sensor 92, air cooling channel 400. Detailed Implementation

[0019] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solution of the present invention and are therefore intended to limit the scope of protection of the present invention.

[0020] The basic implementation examples are as follows: Figures 1 to 3 As shown: Example 1: Extrusion molding die and method for tee pipe fittings like Figures 1 to 3 As shown, this embodiment provides a tee pipe fitting extrusion molding die and its corresponding molding method. This die aims to solve the problems of short die life, poor forming quality, and significant demolding damage in traditional processes by systematically managing the thermal field, friction field, and demolding force field.

[0021] I. Mold Structure The mold mainly consists of basic forming components and three integrated functional modules.

[0022] 1. Basic forming components Reference Figure 1 The basic forming components include: Outer mold 1: As the main body of the mold, its inner cavity constitutes the outer cavity of the tee fitting.

[0023] First core mold 2 and second core mold 3: They are coaxially arranged in the inner cavity of outer mold 1, together forming the core for molding the inner hole of the main pipe of the tee fitting. The outer walls of the first core mold 2 and the second core mold 3 form the main pipe molding cavity between the inner wall of the outer mold 1.

[0024] Main punch 5: Used for the final extrusion to form the main pipe of the tee fitting.

[0025] First punch 4 and second punch 6: used to pre-form (such as upsetting) and pre-pierce the blank, in preparation for extrusion by the main punch 5.

[0026] The outer mold 1 has a cavity that communicates with the main cavity, into which the main punch 5 extends.

[0027] 2. Active thermal management module This module is used for active and precise closed-loop control of the mold's operating temperature.

[0028] Partitioned cooling channels: such as Figure 1 and Figure 2 As shown, internal cooling channels are machined in the areas of the mold most severely affected by heat—namely, the working end of the main punch 5 and the branch cavity area of ​​the outer mold 1. Specifically, an internal main punch channel 51 is provided inside the main punch 5, which is designed in a spiral shape and can be divided into zones according to finite element thermal analysis. For example, it can be divided into a high-intensity cooling zone 52 near the end face, with denser channels and higher cooling intensity; and a more distant, balanced cooling zone 53, with relatively sparse channels for uniform heat dissipation. An outer mold channel 11 is provided at the corresponding position on the outer mold 1.

[0029] Temperature monitoring unit: A thermocouple sensor 200 is embedded at key temperature measurement points, such as the center of the end face of the main punch 5, to monitor the actual working temperature of the mold surface in real time and in situ.

[0030] Intelligent temperature control unit 200: The external intelligent temperature control unit 200 is connected to all cooling channels via pipelines. This unit receives temperature feedback signals from thermocouple sensors 201, and its internal controller (such as a PLC) dynamically adjusts the flow rate and / or temperature of the medium flowing through the cooling channels by regulating the speed of the external cooling circulation pump and the opening of the external proportional valve or switching the cooling medium at different temperatures (e.g., hot oil in the preheating stage, cooling water or atomized liquid in the extrusion stage), thereby achieving stable control of the mold's working temperature.

[0031] 3. Friction Reduction and Flow Promotion Module This module is designed to significantly reduce friction and metal deformation resistance during the extrusion process.

[0032] Ultrasonic Vibration Assist System: This module includes an ultrasonic vibration generator 8. The generator 8 is rigidly connected to the tail end of the main punch 5 via an amplitude transformer 81. During operation, the generator 8 generates a high-frequency electrical signal, which is amplified by the amplitude transformer 81 and converted into mechanical vibration, which is then transmitted axially to the main punch 5. The vibration parameters can be, for example, a frequency of 20kHz and an amplitude of 10μm.

[0033] Multifunctional cavity surface: Surface functional layer 300: A composite coating is prepared on all mold cavity surfaces in contact with the high-temperature blank. This includes at least the outermost wear-resistant lubricating layer, such as a CrN coating doped with WS2 solid lubricant prepared using physical vapor deposition (PVD). To further improve thermal insulation performance, a ceramic thermal barrier layer, such as a zirconium oxide (ZrO2) coating prepared by thermal spraying, can be added between the mold substrate and the wear-resistant lubricating layer.

[0034] Microtexture: such as Figure 3As shown, micro-patterns are fabricated in specific areas of the cavity surface. For example, an array of micro-dimples 102 is fabricated in the forming area, such as areas with complex metal flow. These textures can store lubricant and generate a micro-hydrodynamic effect during extrusion, further reducing friction. Simultaneously, a ceramic thermal barrier layer 101 is provided for heat insulation.

[0035] 4. Collaborative demolding module This module is used to achieve smooth and non-destructive separation of forgings from the core components of the mold.

[0036] Sensor-integrated ejection mechanism: The mechanism for ejecting the first core mold 2 and the second core mold 3 is a hydraulically driven ejection cylinder (i.e., a hydraulic cylinder). Its innovation lies in the fact that a force sensor 91 and a displacement sensor 92 are integrated on each ejector rod, which can provide real-time feedback on the force and displacement information during the ejection process.

[0037] Segmentable core mold structure: such as Figure 1 and Figure 2 As shown, the second core mold 3 can be designed as a combination structure composed of multiple segments 31 (e.g., two segments) joined together by wedge-shaped surfaces. A spherical ejector rod 32 is provided at the center as a driving mechanism. When demolding is required, the spherical ejector rod 32 is pulled upward or pushed downward, using its spherical surface to force all segments 31 to contract radially inward synchronously, thereby disengaging from the inner wall of the forging. At the same time, the segments 31 are located at the joint surface of the main pipe and branch pipe of the tee pipe, thus reducing the impact on the joint surface of the main pipe and branch pipe during demolding, especially avoiding stress concentration.

[0038] Air-cooled shrinkage channel: An air-cooled channel 400 is machined inside the first core mold 2 and the second core mold 3. This channel is connected to an external high-pressure gas source (such as a nitrogen cylinder). Before demolding, high-pressure, low-temperature gas can be instantaneously introduced into the channel.

[0039] II. Molding Method The process method for forming tee pipe fittings using molds according to this embodiment mainly includes the following steps: 1. Blank preparation and heating: Heat the tubular blank to the plastic forming temperature range of the material (e.g., about 1150-1200°C for stainless steel).

[0040] 2. Mold preheating and billet placement: Activate the active thermal management module to pump heat medium into the cooling channel, preheating the mold to 200-300℃ to reduce thermal shock. Then place the high-temperature billet in.

[0041] 3. Pre-forming: Drive the first punch 4 and the second punch 6 to move in sequence to complete the initial upsetting and center piercing of the billet.

[0042] 4. Core Extrusion: The main punch 5 is driven downwards to begin extrusion and form the branch tube. Simultaneously: Start the ultrasonic vibration generator 8 to make the main punch 5 work in a vibrating state.

[0043] The intelligent temperature control unit dynamically adjusts the cooling system based on thermocouple feedback, precisely maintaining the temperature of key areas such as the main punch end face within the optimal window of 350℃ to 450℃.

[0044] 5. Holding pressure and shaping: Hold pressure with the main punch for 5 seconds (e.g., 10-30 seconds), stop ultrasonic vibration, and appropriately enhance cooling to quickly solidify and shape the surface of the forging.

[0045] 6. Collaborative demolding: a. Gas-cooled micro-shrinkage: High-pressure nitrogen gas (e.g., 5-10 MPa, for 1-3 seconds) is instantaneously introduced into the gas-cooling channel 400 of the first core mold 2 and the second core mold 3. The gas absorbs heat through adiabatic expansion, causing the core mold surface to shrink at the micron level, thus reducing the clamping force.

[0046] b. Split retraction (if applicable): If the second core mold 3 is a split structure, drive its spherical push rod 32 to cause the segments 31 to retract radially inward and disengage from the forging.

[0047] c. Servo-controlled ejection: The ejection cylinder is activated. Based on real-time feedback from the force and displacement sensors on each ejector rod, the control system performs force-displacement closed-loop control to eject the first core mold 2 and the second core mold 3 smoothly and synchronously, avoiding off-center loading.

[0048] d. Ejecting the forging: Finally, eject the formed tee fitting from the outer mold 1.

[0049] Example 2: Specific composition of composite surface functional layer The difference between this embodiment and Embodiment 1 is that a more specific and multi-layered implementation scheme is provided for the surface functional layer in the friction reduction and flow promotion module.

[0050] The surface functional layer is a three-layer composite structure formed sequentially from the mold substrate outwards: 1. Heat-resistant alloy transition layer: First, a NiCrAlY alloy layer is prepared on the surface of the mold steel substrate (such as H13 steel) using a high-speed oxy-fuel spraying (HVOF) process. The main function of this layer is to enhance the bonding strength between the subsequent coating and the substrate, and to alleviate the stress caused by the difference in thermal expansion coefficients.

[0051] 2. Ceramic Thermal Barrier Layer: An 8% yttrium-stabilized zirconia (8YSZ) coating is prepared on top of the transition layer using atmospheric plasma spraying (APS). This layer has extremely low thermal conductivity, effectively blocking heat transfer from the high-temperature blank to the mold substrate, thus providing significant thermal insulation protection.

[0052] 3. Wear-resistant and lubricating layer: The outermost layer is a MoS2 co-doped TiAlN coating prepared by physical vapor deposition (PVD). This layer has high hardness and good wear resistance, and the introduction of MoS2 provides a continuous self-lubricating effect, maintaining a low coefficient of friction even at high temperatures.

[0053] This three-layer composite structure provides excellent bonding strength, thermal insulation, and friction reduction and wear resistance, making it an effective means to improve mold life and molding quality.

[0054] The beneficial effects of the present invention are demonstrated through the above embodiments: 1. Significantly extended mold life: The active thermal management module in Example 1 effectively suppresses thermal fatigue and softening of the mold through zoned cooling and intelligent temperature control; the composite surface functional layer in Example 2 greatly enhances the wear resistance of the mold surface. The synergistic effect of the two increases the overall mold life several times over.

[0055] 2. Improved forming quality and precision: In Example 1, the application of ultrasonic vibration (20kHz, 10μm) significantly reduced the metal flow resistance (acoustic softening effect). Combined with the microtexture of the cavity surface, it ensured complete filling of difficult-to-fill areas such as the end of the branch pipe and the inner corner, resulting in forgings with accurate dimensions and smooth surface.

[0056] 3. Reliable and damage-free demolding process: The collaborative demolding strategy described in Example 1—combining air-cooled miniaturization, a segmented structure, and servo ejection based on force-displacement closed-loop control—systematically resolves the clamping force problem of high-temperature forgings. Actual measurements show that this strategy reduces demolding force, completely avoiding forging scratches, deformation, and damage to the die wedge surface.

[0057] 4. Energy-saving and controllable process: Ultrasonic vibration assistance significantly reduces extrusion pressure, decreasing equipment tonnage requirements and energy consumption. Simultaneously, temperature, force, and displacement sensors and intelligent control units distributed throughout the mold enable real-time monitoring and feedback control of all process parameters, greatly improving the stability and intelligence of the production process and laying a solid foundation for process optimization and digital production.

[0058] It should be noted that: The "high-temperature working area of ​​the mold" can be expanded according to the specific product shape and thermal analysis results, and is not limited to the aforementioned location.

[0059] The "hydraulic cylinder" and the "electro-hydraulic servo ejection system" described herein are examples; any linear drive mechanism capable of achieving precise force and displacement control is within the scope of this invention.

[0060] The "high-pressure cooling gas" is not limited to nitrogen, but can also be other inert or semi-inert gases such as argon and carbon dioxide.

[0061] The coating materials, structural parameters, and process parameters mentioned are all examples, and those skilled in the art can make reasonable adjustments based on the core concept of this invention.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0063] Numerous specific details are set forth in this specification. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification. The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A tee pipe fitting extrusion die, comprising an outer die, a first core die and a second core die disposed within the outer die, and a main punch for extrusion, characterized in that, Also includes: An active thermal management module includes a partitioned cooling channel, thermocouple sensors, and an intelligent temperature control unit; the partitioned cooling channel is located in the high-temperature working area of ​​the mold; the thermocouple sensors are used to monitor the mold temperature; and the intelligent temperature control unit dynamically adjusts the cooling medium parameters flowing through the cooling channel based on the feedback from the thermocouple sensors. The friction-reducing and flow-promoting module includes an ultrasonic vibration generator connected to the main punch, used to apply axial high-frequency vibration to the main punch during the extrusion process; And a surface functional layer disposed on the cavity surface in contact with the blank, the surface functional layer including a wear-resistant lubricating layer; The collaborative demolding module includes an ejection mechanism for ejecting the first core mold and the second core mold respectively. The ejection mechanism is a hydraulic cylinder, and a force sensor and a displacement sensor are integrated on its ejector rod.

2. The tee pipe fitting extrusion die according to claim 1, characterized in that, The partitioned cooling channel includes an inner channel in the main punch and an outer mold channel.

3. The tee pipe fitting extrusion die according to claim 1, characterized in that, The surface functional layer also includes a wear-resistant lubricating layer and a ceramic thermal barrier layer; The wear-resistant lubricating layer is an array of micro-pits for lubrication; The ceramic thermal barrier layer is located below the wear-resistant lubricating layer and is used for heat insulation.

4. The extrusion die for a tee pipe fitting according to claim 1, characterized in that, The collaborative demolding module further includes: the second core mold is a segmentable combination structure, and its interior is provided with a drive mechanism for driving the segment blocks to retract radially; Both the first and second core molds have air-cooling channels connected to a high-pressure gas source inside.

5. A method for extruding a tee fitting using an extrusion die according to any one of claims 1 to 4, characterized in that, Includes the following steps: Step 1. Heat the billet to the plastic molding temperature and place it into the mold; Step 2. Activate the active thermal management module to preheat the mold; Step 3. Perform pre-forming; Step 4. Core extrusion stage: Drive the main punch to perform extrusion, while simultaneously activating the ultrasonic vibration generator to apply ultrasonic vibration, and dynamically control the mold temperature through the intelligent temperature control unit; Step 5. Pressure holding and initial cooling; Step 6. Collaborative demolding stage: The core mold is separated from the forging and ejected through the collaborative demolding module.

6. The extrusion molding method for tee fittings according to claim 5, characterized in that, In step S4, the intelligent temperature control unit controls the working temperature of the contact area between the mold and the blank within the range of 350°C to 450°C.

7. The extrusion molding method for tee fittings according to claim 6, characterized in that, Step S6 includes: S6a. High-pressure cooling gas is introduced into the air-cooling channels inside the first and second core molds to cause the core mold surface to shrink. S6b. Start the electro-hydraulic servo ejection system and simultaneously eject the first core mold and the second core mold under closed-loop control of force and displacement; When the second core mold is a segmentable structure, before step S6b, its segments are driven to contract radially inward.

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