A molding die and molding process suitable for multi-nozzle pipe

Abstract

The application provides a forming die and forming process suitable for a multi-nozzle pipeline, and the forming die comprises an inner liner, a upsetting upper die, a punching upper die, a pressurizing lower die and an outer sleeve. The inner liner comprises a surrounding side wall, the upper end of the side wall is provided with a first opening, and the lower end is provided with a second opening; the upsetting upper die is located on the upper side of the inner liner; the punching upper die is located on the upper side of the inner liner and performs a punching process from the first opening; the pressurizing lower die is located on the lower side of the inner liner and performs a pressurizing process from the second opening during the upsetting and punching processes; wherein the inner liner is split in the circumferential direction of the side wall, the split inner liner jointly forms a die cavity for forming the multi-nozzle pipeline after being combined, and the forming die further comprises the outer sleeve which is used for being sleeved on the outer side of the split inner liner to apply radial constraint. The forming die and forming process suitable for the multi-nozzle pipeline of the application are specially designed for the multi-nozzle pipeline, and can improve the technical problems of low manufacturing quality and efficiency of the multi-nozzle pipeline.

Description

Technical Field

[0001] This invention relates to the field of multi-nozzle pipe forming mold technology, and in particular to a forming mold and forming process suitable for multi-nozzle pipes. Background Technology

[0002] As high-end equipment such as nuclear power, chemical engineering, and supercritical thermal power plants develop towards higher parameters and larger scale, the performance requirements for key components—large-diameter pipes with multiple nozzles—are becoming increasingly stringent. These pipes are typically used in core loops such as main steam systems and feedwater systems, bearing the heavy responsibility of transporting fluids in high-temperature, high-pressure, and even irradiated environments. Their reliability directly affects the safety and lifespan of the entire system. This requires the pipe body and nozzles to not only possess excellent mechanical properties at both room and high temperatures and good resistance to fatigue and stress corrosion, but also to impose extremely high control standards on their internal microstructure, especially the uniformity and miniaturization of grain size.

[0003] Currently, multi-nozzle pipes generally rely on traditional free forging forming processes. This process involves multiple heating and forging operations to gradually forge large steel ingots into a near-tube blank shape with multiple protruding nozzles. However, research has revealed that the traditional free forging forming process is highly dependent on manual operation and experience, making it difficult to accurately guarantee the geometric dimensions, positional precision, and consistency of the transition fillets between the nozzles and the main pipe. This results in huge machining allowances, low material utilization, and significantly increased raw material costs. Furthermore, to achieve complex shapes, dozens or even more heating cycles are typically required. Each high-temperature heating (especially exceeding the recrystallization temperature) and subsequent cooling causes repeated grain growth in the nozzle area (where deformation is complex and heat dissipation conditions vary). The cumulative effect of multiple thermal cycles easily leads to coarse or even abnormally large grain structures in this critical area, severely deteriorating the material's toughness and fatigue strength. Moreover, the lengthy process (including multiple heating, forging, cooling, and cleaning) results in long production cycles, high energy consumption, and low efficiency, making it difficult to meet the demands of modern industry for short delivery cycles and low-cost manufacturing.

[0004] Therefore, there is an urgent need to develop a molding die and molding process specifically for multi-nozzle pipes, which can solve the above-mentioned technical problems, improve the manufacturing quality and efficiency of multi-nozzle pipes, and thus meet the needs of short delivery cycle and low-cost manufacturing. Summary of the Invention

[0005] This invention provides a molding die and molding process for multi-nozzle pipes, specifically designed to improve the technical problems of low manufacturing quality and efficiency of multi-nozzle pipes.

[0006] This invention provides a forming mold suitable for multi-nozzle pipes. The forming mold includes: an inner liner, an upsetting upper die, a punching upper die, a pressure lower die, and an outer sleeve.

[0007] The liner includes surrounding sidewalls, with a first opening at the upper end and a second opening at the lower end; an upsetting upper die is located on the upper side of the liner for upsetting from the first opening; a punching upper die is located on the upper side of the liner for punching from the first opening after upsetting; a pressure lower die is located on the lower side of the liner for applying pressure from the second opening during upsetting and punching; wherein, the liner is split in the circumferential direction of the sidewalls, and the split liners together form a mold cavity for forming a multi-nozzle pipe after being molded together, and the forming mold also includes an outer sleeve, which is fitted onto the outside of the split liner to apply radial constraint.

[0008] In one embodiment of the present invention, the lining is at least two separate pieces along the circumferential direction of the sidewall.

[0009] In one embodiment of the present invention, the inner lining is a four-part split type along the circumferential direction of the sidewall.

[0010] In one embodiment of the present invention, the outer jacket and the inner lining are clearance fit, and the radial gap between them is 1 mm to 5 mm.

[0011] In one embodiment of the present invention, the cross-section of both the inner lining and the outer lining is circular.

[0012] In one embodiment of the present invention, the multi-nozzle pipe includes a main body and a plurality of nozzles located on the main body. The mold cavity includes a first sub-mold cavity for molding the main body and a second sub-mold cavity for molding the nozzles. A flow diversion and guiding surface is provided at the connection between the first sub-mold cavity and the second sub-mold cavity. The flow diversion and guiding surface is an arc-shaped transition surface.

[0013] In one embodiment of the present invention, the multi-nozzle pipe includes a main body and a plurality of nozzles located on the main body. The mold cavity includes a first sub-mold cavity for forming the main body and a second sub-mold cavity for forming the nozzles. The second sub-mold cavity is provided with an inner hole punch extending along the axial direction of the second sub-mold cavity in the middle. The inner hole punch is used to form the inner hole of the nozzle.

[0014] In one embodiment of the present invention, the lower end face of the liner is provided with a positioning post for cooperating with a positioning hole on the lower die seat of the press, and the positioning post extends along the length direction of the side wall.

[0015] In one embodiment of the present invention, the materials of the inner liner, the upsetting upper die, the punching upper die, the pressure lower die, and the outer jacket are all 5CrNiMo.

[0016] The present invention also provides a forming process for forming a multi-nozzle pipe using the above-mentioned forming mold, comprising: Place the pressure die on the lower die holder of the press; Separate the split inner liner, evenly spray or brush high-temperature lubricant onto the inner wall of the mold cavity of the inner liner, then put the outer sleeve on the outside of the assembled inner liner, and place the inner liner and outer sleeve on the pressure lower mold on the lower mold base, so that the pressure lower mold is aligned with the second opening; Prepare the initial blank and heat it to a suitable temperature. Then, place the initial blank into the mold cavity of the split liner through the first opening. The upsetting upper die is connected to the upper die seat of the press, and the press is driven to move the upsetting upper die and the pressure lower die in opposite directions along the first opening and the second opening, respectively. After the upsetting upper die and the pressure lower die come into contact with the initial blank, axial pressure is applied, and the blank undergoes upsetting deformation in the die cavity to form a solid tube blank. After the upsetting process is completed, the press is driven to move the upsetting upper die upward to separate it from the workpiece. The upper punching die is connected to the upper die base of the press. The press is driven to move the upper punching die and the lower pressure die in opposite directions along the first opening and the second opening, respectively, to punch a hole from the central axis of the upset solid tube blank to form a hollow tube blank. After the punching process is completed, the press is driven to separate the upper punching die and the lower pressure die from the workpiece. Separate the outer jacket from the inner liner, then separate the split inner liner along the parting line to remove the formed multi-nozzle pipe workpiece, thus completing the forming of the multi-nozzle pipe workpiece.

[0017] The beneficial effects of this invention are: This invention relates to a molding die and molding process for multi-nozzle pipes. By designing a dedicated molding die for multi-nozzle pipes, compared to existing technologies, this invention features a split-type liner. This allows for the uniform spraying or brushing of a high-temperature lubricant onto the fully open mold cavity wall before assembling the split liner. This all-around, dead-angle-free lubrication eliminates the lubrication blind spots inherent in traditional closed molds, significantly reducing the friction coefficient between the blank and the mold during deformation, improving metal flow uniformity, and effectively extending the mold's service life. The split liner is further encased in an outer sleeve, which provides strong radial constraint during multi-nozzle pipe molding, ensuring the overall strength and stability of the mold, preventing mold cracking, and ensuring smooth molding. After completion, the inner liner can be easily separated simply by removing the outer jacket, perfectly solving the demolding problem of complex multi-nozzle pipe fittings. At the same time, the combined use of the upsetting upper die and the punching upper die can achieve continuous upsetting, compaction and punching cavity making in a single forging cycle, avoiding the problem of coarse grains caused by multiple heating in traditional free forging, significantly improving the mechanical properties of materials and production efficiency. Furthermore, the pressure lower die applies pressure from the second opening during the upsetting and punching process, that is, bidirectional synchronous extrusion is carried out during both upsetting and punching processes. Compared with unidirectional extrusion, it can make the workpiece undergo significant plastic deformation and more uniform deformation, effectively refining the grains, improving the internal structure of the workpiece, further improving the quality of die forging, and meeting the high reliability requirements of pipelines in nuclear power, chemical and other fields. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0019] In the attached diagram: Figure 1 This is a schematic diagram of a multi-nozzle pipe manufactured using the molding die and molding process provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of a segmented structure along the circumferential direction in a molding die provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of another segment of the split inner liner in the circumferential direction in a molding die provided according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of a split inner liner in a molding die provided in an embodiment of the present invention, which is further divided into segments along the circumferential direction. Figure 5This is a schematic diagram of the structure of a split inner liner in a molding die provided in an embodiment of the present invention, which is further divided into segments along the circumferential direction. Figure 6 This is a schematic diagram of the outer sleeve in a molding die provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of the molding die in use according to an embodiment of the present invention, which shows the upsetting upper die and the pressure lower die starting the upsetting process; Figure 8 This is a schematic diagram of the molding die in use according to an embodiment of the present invention, which is a schematic diagram of the upsetting upper die and the pressure lower die after the upsetting process; Figure 9 This is a schematic diagram of the molding die in use according to an embodiment of the present invention, which shows the upper punching die and the lower pressurizing die starting the punching process; Figure 10 This is a schematic diagram of the molding die in use according to an embodiment of the present invention, which is a schematic diagram of the upper punching die and the lower pressure die after the punching process.

[0020] The attached figures are labeled as follows: 1. Liner; 11. Sidewall; 12. First opening; 13. Second opening; 14. Mold cavity; 15. First sub-mold cavity; 16. Second sub-mold cavity; 17. Flow diversion and guiding surface; 18. Positioning post; 2. Upsetting upper die; 3. Punching upper die; 4. Pressurizing lower die; 5. Outer casing; 6. Multi-nozzle pipe; 61. Main pipe body; 62. Nozzle; 7. Inner hole punch. Detailed Implementation

[0021] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0022] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0023] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the invention. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the invention.

[0024] Please see Figures 1 to 10 This invention provides a forming mold suitable for a multi-nozzle pipe 6. The forming mold includes an inner liner 1, an upsetting upper die 2, a punching upper die 3, a pressurizing lower die 4, and an outer sleeve 5. The specific models and dimensions of the inner liner 1, the upsetting upper die 2, the punching upper die 3, the pressurizing lower die 4, and the outer sleeve 5 can be flexibly designed according to the model of the target multi-nozzle pipe 6.

[0025] Please see Figure 7 The inner lining 1 includes a surrounding side wall 11. The upper end of the side wall 11 is provided with a first opening 12 and the lower end is provided with a second opening 13. That is, the side wall 11 is barrel-shaped and has openings at both ends.

[0026] Please see Figures 7 to 10The upsetting upper die 2 is located on the upper side of the inner liner 1 and is used for upsetting from the first opening 12; the punching upper die 3 is located on the upper side of the inner liner 1 and is used for punching from the first opening 12 after the upsetting process; the pressure lower die 4 is located on the lower side of the inner liner 1 and is used for pressure application from the second opening 13 during the upsetting and punching processes; wherein, the inner liner 1 is split along the circumferential direction of the side wall 11, and the split inner liner 1, after being closed, together form a mold cavity 14 for forming the multi-nozzle pipe 6, the specific shape of which can be customized. The design is flexible and adaptable to the model and shape of the target multi-nozzle pipe 6, including but not limited to straight, curved, and irregular shapes. The forming mold also includes an outer sleeve 5, which is fitted onto the outside of the split inner liner 1 to apply radial constraint. This design of the inner liner 1 as a split structure allows for the uniform spraying or brushing of high-temperature lubricant onto the inner wall of the fully open mold cavity 14 before assembling the split inner liner 1. This all-around, dead-angle-free lubrication method eliminates the lubrication blind spots inside traditional closed molds, greatly reducing the friction between the blank and the mold during deformation. The friction coefficient between the two is reduced, improving the uniformity of metal flow and effectively extending the service life of the mold. The outer sleeve 5 is fitted around the split inner liner 1, providing strong radial constraint force during the forming of the multi-nozzle pipe 6, ensuring the overall strength and stability of the mold, preventing mold cracking, and allowing the inner liner 1 to be easily separated by simply removing the outer sleeve 5 after forming, perfectly solving the demolding problem of complex multi-nozzle pipe fittings. At the same time, the combined use of the upsetting upper die 2 and the punching upper die 3 can realize continuous upsetting pressing in a single firing cycle. The solid punching cavity avoids the problem of coarse grains caused by multiple heating in traditional free forging, significantly improving the mechanical properties of materials and production efficiency. Furthermore, the pressure die 4 applies pressure from the second opening 13 during the upsetting and punching processes, meaning that both upsetting and punching processes involve bidirectional synchronous extrusion. Compared to unidirectional extrusion, this allows for greater plastic deformation of the workpiece and more uniform deformation, effectively refining the grains, improving the internal structure of the workpiece, further enhancing the forging quality, and meeting the high reliability requirements of pipelines in fields such as nuclear power and chemical engineering.

[0027] Please see Figures 2 to 5 In one embodiment of the present invention, the inner liner 1 can be at least two-lobed in the circumferential direction along the side wall 11, such as two-lobed, three-lobed, five-lobed, multi-lobed, etc. In one embodiment of the present invention, the inner liner 1 is preferably four-lobed in the circumferential direction along the side wall 11. Compared with two-lobed or three-lobed types, by appropriately increasing the number of lobes, the circumferential span of a single lobe is effectively reduced, significantly reducing the demolding difficulty and improving demolding efficiency and yield. Compared with five-lobed or multi-lobed types, the number of assembly components is reasonably controlled under the premise of smooth demolding, which avoids the installation process being too cumbersome and ensures the overall rigidity and sealing of the mold when it is closed.

[0028] In one embodiment of the present invention, the outer jacket 5 and the inner liner 1 can be clearance fit, with a radial gap between them ranging from 1mm to 5mm, such as 1mm, 2mm, 3mm, 4mm, 5mm, etc., which can be flexibly set according to actual usage requirements. This avoids the difficulties in assembling the inner liner 1 and the outer jacket 5 and the problem of thermal expansion interference caused by too small a gap, and also prevents the risk of structural loosening, decreased positioning accuracy and abnormal leakage of molten metal caused by too large a gap.

[0029] The cross-sections of the inner liner 1 and the outer liner 5 can take various shapes that are easy for those skilled in the art to conceive of, such as triangles, quadrilaterals, pentagons, irregular shapes, etc. In one embodiment of the present invention, the cross-sections of the inner liner 1 and the outer liner 5 can both be circular. Compared with polygonal or irregular structures, circular cross-sections have natural structural symmetry and uniform stress distribution, and can uniformly bear the high pressure from the internal melt during the die casting process, effectively avoiding stress concentration at the corners, thereby significantly improving the overall structural strength and fatigue resistance of the mold.

[0030] Please see Figures 1 to 5 In one embodiment of the present invention, the multi-nozzle pipe 6 may include a main body 61 and a plurality of nozzles 62 located on the main body 61. The mold cavity 14 includes a first sub-mold cavity 15 for molding the main body 61 and a second sub-mold cavity 16 for molding the nozzles 62. A flow diversion and guiding surface 17 is provided at the connection between the first sub-mold cavity 15 and the second sub-mold cavity 16. The flow diversion and guiding surface 17 is an arc-shaped transition surface. When the metal billet enters the branch channel of the second sub-mold cavity 16 from the main channel of the first sub-mold cavity 15, if a right angle transition is used, the metal will undergo strong shear slip at the corner, which not only increases the forming resistance, but also easily rolls the oxide scale on the metal surface into the interior to form folding defects. Therefore, in this embodiment, the flow diversion and guiding surface 17 is set as an arc-shaped transition surface, so that the streamlined channel structure meets the boundary conditions of metal viscoplastic flow, reduces the forming friction resistance, ensures the compactness of the structure when multiple metal flows converge, and optimizes the metal filling resistance.

[0031] Please see Figures 1 to 5In one embodiment of the present invention, the multi-nozzle pipe 6 may include a main body 61 and a plurality of nozzles 62 located on the main body 61. The mold cavity 14 includes a first sub-mold cavity 15 for forming the main body 61 and a second sub-mold cavity 16 for forming the nozzles 62. The second sub-mold cavity 16 has an inner hole punch 7 extending along the axial direction of the second sub-mold cavity 16 in the middle. The inner hole punch 7 is used to form the inner hole of the nozzles 62. Since the present invention uses a pressure lower die 4 to apply pressure bidirectionally from the second opening 13 during both upsetting and punching processes, bidirectional synchronous extrusion is achieved. Compared to unidirectional extrusion, bidirectional synchronous extrusion can apply greater forming force. In conjunction with the inner hole punch 7 in the middle of the second sub-mold cavity 16, it can directly and efficiently form the inner hole of the nozzle 62. This eliminates the need for additional hole opening operations on the tube blank at the nozzle 62, improving the forming accuracy and efficiency of the inner hole of the nozzle 62 and optimizing the overall forming process. In contrast, even with the inner hole punch 7, uneven force or insufficient forming force makes it difficult to guarantee the forming quality of the inner hole of the nozzle 62, which can easily lead to problems such as incomplete inner holes or dimensional deviations.

[0032] Please see Figure 7 In one embodiment of the present invention, the lower end face of the liner 1 is provided with a positioning post 18 for cooperating with the positioning hole on the lower mold base of the press. The positioning post 18 extends along the length direction of the side wall 11. In this way, the cooperation between the positioning post 18 and the positioning hole can provide a precise positioning reference for the installation of the liner 1 in the mold, prevent the liner 1 from being displaced under high pressure, and ensure the stability and reliability of the molding quality.

[0033] In one embodiment of the present invention, the materials of the inner liner 1, the upsetting upper die 2, the punching upper die 3, the pressure lower die 4, and the outer jacket 5 can all be 5CrNiMo. Compared with other materials, 5CrNiMo has excellent comprehensive mechanical properties, which can not only ensure that each component has good thermal strength, wear resistance, and thermal fatigue resistance under high temperature and high pressure conditions, but also ensure that the mold system has good matching during thermal expansion, reduce internal stress and deformation caused by the difference in thermal expansion coefficients of different materials, thereby improving the dimensional stability and service life of the mold, and ensuring the consistency and reliability of the forming quality of the multi-nozzle pipe 6.

[0034] The present invention also provides a molding process for molding a multi-nozzle pipe 6 using the above-mentioned molding die, comprising: Step S1: Place the pressure die 4 on the lower die holder of the press; Step S2: Separate the split inner liner 1, evenly spray or brush high-temperature lubricant on the inner wall of the mold cavity 14 of the inner liner 1, then put the outer sleeve 5 on the outside of the assembled inner liner 1, and place the inner liner 1 and the outer sleeve 5 on the pressure lower mold 4 on the lower mold base, so that the pressure lower mold 4 is aligned with the second opening 13. In this step, because traditional closed molds have difficulty applying lubricant to the blind ends of deep holes, resulting in an excessively high coefficient of friction during forming, this step utilizes the split open characteristics of the inner liner 1 to achieve all-round, dead-angle-free lubrication. The high-temperature lubricant used can be water-based graphite lubricant or glass lubricant, which can form a high-temperature resistant isolation lubricating film between the mold and the metal blank.

[0035] Step S3: Prepare the initial blank and heat it to a suitable temperature. Then, place the initial blank into the mold cavity 14 of the split inner liner 1 through the first opening 12. In this step, a solid cylindrical steel billet that meets the requirements of chemical composition and metallurgical quality needs to be prepared as the initial billet. The billet needs to be sawed, cleaned (to remove oxide scale and defects), and heated to a suitable temperature. Specifically, the heating temperature of the billet can be controlled within the range of 1180℃ to 1220℃. If the temperature is lower than 1180℃, the deformation resistance of the metal will increase significantly, which may easily lead to equipment overload or incomplete filling. If the temperature is higher than 1220℃, it will cause serious coarsening of austenite grains or even overheating and burning. The heated billet can be taken out of the furnace with clamps, and the billet can be centered and adjusted by manipulator or multi-functional robot. Then, it is placed vertically and stably into the inner liner 1 mold cavity 14, ensuring that the axis of the billet coincides with the axis of the inner liner 1 mold cavity 14.

[0036] Step S4: Connect the upsetting upper die 2 to the upper die seat of the press, and drive the press to move the upsetting upper die 2 and the pressure lower die 4 in opposite directions along the first opening 12 and the second opening 13 respectively. After the upsetting upper die 2 and the pressure lower die 4 come into contact with the initial blank, axial pressure is continued to be applied. The blank undergoes upsetting deformation in the die cavity 14 to form a solid tube blank. After the upsetting process is completed, drive the press to move the upsetting upper die 2 upward to separate it from the workpiece. In this step, the lower end face of the upsetting upper die 2 and the upper end face of the pressure lower die 4 can be designed as planes adapted to the upper end face of the solid tube blank. Their edges can have optimized transition radii to guide metal flow and avoid shear bands or folding defects. In this step, during the upsetting process, the upsetting upper die 2 and the pressure lower die 4 need to be activated simultaneously, so that the upsetting upper die 2 moves downward and the pressure lower die 4 moves upward, applying axial pressure to the blank in the die cavity 14 for upsetting. Under the constraint of the inner liner 1, after the upsetting upper die 2 and the pressure lower die 4 come into contact with the high-temperature blank, a huge bidirectional axial pressure is applied. The blank undergoes upsetting deformation within the closed inner liner 1. Compared with unilateral pressure, bidirectional pressure upsetting in the forward and reverse directions is carried out synchronously and continuously, which makes the metal flow path more... The filling of the nozzle 62 cavity is no longer dependent on the difficult unidirectional extrusion of metal, but rather on the combined action driven by bidirectional main deformation. This achieves simultaneous forming of multiple nozzles 62, making the rounded corner area at the root of the nozzle 62 fully filled. It avoids the root of the nozzle 62 being subjected to shear due to the sequential forming of the nozzles 62, greatly reducing the tendency to tear. Furthermore, the double-sided pressure plastic deformation amplitude is larger, which can more effectively refine the grains and improve the internal structure of the workpiece. In addition, in conjunction with the inner hole punch 7 in the middle of the second sub-mold cavity 16, the inner hole of the nozzle 62 can be formed directly and efficiently, with high forming accuracy and good surface quality. This replaces the inefficient method of repeatedly forging the nozzle 62 one forging and one part at a time in traditional forging. The bidirectional synchronous upsetting in one forging realizes the forming of multi-nozzle pipes.

[0037] Step S5: Connect the punching upper die 3 to the upper die base of the press, drive the press to move the punching upper die 3 and the pressure lower die 4 in opposite directions along the first opening 12 and the second opening 13 respectively, punching holes from the central axis position of the upset solid tube blank to form a hollow tube blank. After the punching process is completed, drive the press to separate the punching upper die 3 and the pressure lower die 4 from the workpiece. In this step, the transformation from solid to hollow is completed, providing an internal cavity space for further deformation of the hollow tube blank. The upper punching die 3 can be a cylindrical punch made of high-strength heat-resistant alloy, with a diameter slightly smaller than the designed inner diameter of the target pipe, leaving room for possible subsequent reaming or machining. The front end of the upper punching die 3 can be designed with a guide cone or rounded corner to facilitate centering and forming. After the upper punching die 3 and the lower pressure die 4 come into contact with the high-temperature blank, a huge bidirectional axial pressure is applied, forcing the metal blank to flow upward and in the opposite direction to form the inner hole of the pipe. Compared with single-sided pressure punching, double-sided pressure punching can more conveniently carry out the punching process, improve the forming quality and forming efficiency of the inner hole, and supplement the filling effect of each nozzle 62.

[0038] Step S6: Separate the outer jacket 5 from the inner liner 1, then separate the split inner liner 1 along the parting line, and take out the formed multi-nozzle pipe 6 workpiece to complete the forming of the multi-nozzle pipe 6 workpiece.

[0039] In this step, after all forming steps are completed, the split inner liner is opened. The integral pipe blank with multiple nozzles that has been formed can be smoothly and completely ejected from the inner liner cavity using the ejection mechanism built into the mold or external auxiliary device. Since there is lubricant on the inner wall of the mold, the demolding process is usually smooth. The removed pipe blank is transferred to an insulation pit or slow cooling device for controlled cooling to control its cooling rate and avoid generating excessive thermal stress or adverse microstructure transformation, thus providing a stable intermediate blank for subsequent heat treatment and machining.

[0040] In summary, the molding die and molding process for multi-nozzle pipes of the present invention have the following significant advantages: 1. Achieve overall demolding of complex structures, reducing mold costs and manufacturing difficulty; This invention, through a split-type concave mold design, can achieve overall demolding of complex irregular tube blanks with multi-nozzle structures without damaging the mold, effectively solving the dilemma of difficult demolding of traditional integral molds, significantly reducing the manufacturing difficulty and cost of molds, and improving production efficiency.

[0041] 2. Extends mold life and improves forging surface quality; the split design makes mold manufacturing, maintenance, and replacement more convenient. When damaged, only the corresponding parts need to be replaced, without replacing the entire mold. Combined with an optimized lubrication design, it effectively solves the problem of sticking to the mold in high-temperature stainless steel and eliminates lubrication dead zones. This not only significantly reduces mold surface wear and thermal shock, greatly extending mold life, but also ensures smooth metal flow, resulting in a high-gloss surface finish on the billet, free from scratches and cold shuts, providing a high-quality billet base for subsequent precision machining.

[0042] 3. The process is simple and the production efficiency is improved. This invention integrates and simplifies the traditional process that requires multiple heating and multiple passes (such as blanking, upsetting, punching, multiple drawing and nozzle forming) into three core continuous steps: "loading-upsetting / pre-forming-punching". These steps are completed in a single heating cycle and formed simultaneously in one go. This eliminates the tedious process of forging each piece individually, greatly shortens the overall billet production cycle, effectively reduces energy consumption, material loss and production cycle, and significantly reduces the overall manufacturing cost.

[0043] 4. Both upsetting and punching processes involve bidirectional synchronous extrusion. Compared to unidirectional extrusion, this allows for greater and more uniform plastic deformation of the workpiece, effectively refining the grains and improving the internal structure of the workpiece. Furthermore, bidirectional synchronous extrusion subjects the metal to force simultaneously in both the vertical and horizontal directions, optimizing the metal flow path and stress distribution. This effectively solves the problem of shearing and tearing of the root of the nozzle formed earlier due to different nozzle forming sequences in unidirectional extrusion forging. At the same time, the metal is more likely to fully fill the die cavity, achieving synchronous and full forming of each nozzle, avoiding defects such as insufficient filling and folding, further improving the forging quality and meeting the high reliability requirements of pipelines in fields such as nuclear power and chemical engineering.

[0044] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A molding die suitable for multi-nozzle pipes, characterized in that, The molding die includes: Liner (1), the lining (1) includes a surrounding sidewall (11), the upper end of the sidewall (11) is provided with a first opening (12) and the lower end is provided with a second opening (13); Upsetting upper die (2), located on the upper side of the inner liner (1), is used to perform the upsetting process from the first opening (12); The punching die (3) is located on the upper side of the liner (1) and is used to perform the punching process from the first opening (12) after the upsetting process is completed. The pressure die (4), located on the lower side of the liner (1), is used to apply pressure from the second opening (13) during the upsetting and punching process; The inner liner (1) is a split type along the circumferential direction of the side wall (11). After the split inner liner (1) is molded together, it forms a mold cavity (14) for molding the multi-nozzle pipe (6). The molding mold also includes an outer sleeve (5), which is used to be fitted on the outside of the split inner liner (1) to apply radial constraint.

2. The forming mold for multi-nozzle pipes according to claim 1, characterized in that, The lining (1) is at least two separate pieces along the circumferential direction of the sidewall (11).

3. The forming mold for multi-nozzle pipes according to claim 2, characterized in that, The lining (1) is a four-lobed split type along the circumferential direction of the sidewall (11).

4. The forming mold for multi-nozzle pipes according to claim 1, characterized in that, The outer jacket (5) and the inner lining (1) are clearance fit, with a radial gap of 1 mm to 5 mm between them.

5. The forming mold for multi-nozzle pipes according to claim 1, characterized in that, The cross-section of the inner lining (1) and the cross-section of the outer lining (5) are both circular.

6. The forming mold for multi-nozzle pipes according to any one of claims 1 to 5, characterized in that, The multi-nozzle pipe (6) includes a main body (61) and a plurality of nozzles (62) located on the main body (61). The mold cavity (14) includes a first sub-mold cavity (15) for forming the main body (61) and a second sub-mold cavity (16) for forming the nozzles (62). A flow diversion and guiding surface (17) is provided at the connection between the first sub-mold cavity (15) and the second sub-mold cavity (16). The flow diversion and guiding surface (17) is an arc-shaped transition surface.

7. The forming mold for multi-nozzle pipes according to any one of claims 1 to 5, characterized in that, The multi-nozzle pipe (6) includes a main body (61) and a plurality of nozzles (62) located on the main body (61). The mold cavity (14) includes a first sub-mold cavity (15) for forming the main body (61) and a second sub-mold cavity (16) for forming the nozzles (62). The second sub-mold cavity (16) has an inner hole punch (7) extending along the axial direction of the second sub-mold cavity (16) in the middle. The inner hole punch (7) is used to form the inner hole of the nozzles (62).

8. The forming mold for multi-nozzle pipes according to claim 7, characterized in that, The lower end face of the liner (1) is provided with a positioning post (18) for cooperating with the positioning hole on the lower die seat of the press, and the positioning post (18) extends along the length direction of the side wall (11).

9. The forming mold for multi-nozzle pipes according to claim 7, characterized in that, The inner liner (1), the upsetting upper die (2), the punching upper die (3), the pressure lower die (4), and the outer jacket (5) are all made of 5CrNiMo.

10. A forming process for forming multi-nozzle pipes using any one of the forming molds described in claims 1-9, characterized in that, include: Place the pressure die (4) on the lower die holder of the press; Separate the split inner liner (1), spray or brush high-temperature lubricant evenly on the inner wall of the mold cavity (14) of the inner liner (1), then put the outer sleeve (5) on the outside of the assembled inner liner (1), and place the inner liner (1) and the outer sleeve (5) on the pressure lower mold (4) on the lower mold base, so that the pressure lower mold (4) is aligned with the second opening (13); Prepare the initial blank and heat it to a suitable temperature. Then, place the initial blank into the mold cavity (14) of the split liner (1) along the first opening (12). The upsetting upper die (2) is connected to the upper die seat of the press, and the press is driven to move the upsetting upper die (2) and the pressure lower die (4) in opposite directions along the first opening (12) and the second opening (13) respectively. After the upsetting upper die (2) and the pressure lower die (4) come into contact with the initial blank, axial pressure is applied, and the blank undergoes upsetting deformation in the die cavity (14) to form a solid tube blank. After the upsetting process is completed, the press is driven to move the upsetting upper die (2) upward and separate it from the workpiece. Connect the punching upper die (3) to the upper die seat of the press, drive the press to drive the punching upper die (3) and the pressure lower die (4) to move towards each other along the first opening (12) and the second opening (13) respectively, punching holes from the central axis position of the upset solid tube blank to form a hollow tube blank. After the punching process is completed, drive the press to separate the punching upper die (3) and the pressure lower die (4) from the workpiece. Separate the outer jacket (5) from the inner liner (1), then separate the split inner liner (1) along the parting line, and take out the formed multi-nozzle pipe (6) workpiece to complete the forming of the multi-nozzle pipe (6) workpiece.

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