Additive manufacturing method for a weakly rigid complex thin-walled valve seat

Abstract

The application belongs to the technical field of additive manufacturing, and particularly relates to a weak-rigidity complex thin-wall valve seat additive manufacturing method. The method comprises the following steps: step 1, model optimization and support design; step 2, regional process parameter regulation; step 3, additive manufacturing and online monitoring; and step 4, post-processing and quality verification. The application has the beneficial effects that: firstly, the topology sandwich and reinforcing rib design are adopted, the honeycomb / dot matrix porous structure is filled between the inner and outer walls, and the radial reinforcing rib layout is combined with the overhanging area, so that the thermal stress is effectively dispersed and the local deformation is inhibited.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology, specifically relating to an additive manufacturing method for a weakly rigid complex thin-walled valve seat. Background Technology

[0002] In the field of manufacturing thin-walled components of high-temperature alloys, patent CN 119282148 A proposes an electron beam additive manufacturing device. This device uses an electromagnetic stirrer to apply an alternating magnetic field to the molten pool, refining grains and reducing microstructure segregation, thereby improving fatigue life and high-temperature creep performance. Its core structure includes an electron gun, a pressure plate, and an electromagnetic stirrer (such as a three-phase electromagnetic stirring coil) surrounding a central hole. Large-sized components are printed via a horizontally moving platform. However, this technology is primarily designed for high-temperature alloy materials and lacks adaptability to the complex, irregular structures of thin-walled valve seats. Furthermore, the electromagnetic stirrer needs to be integrated with the pressure plate, limiting the device's size and making it difficult to flexibly adjust the magnetic field parameters to suit the local characteristics of the valve seat.

[0003] Patent CN117001010A proposes an additive manufacturing process for thin-walled structures, employing dual laser heads to execute additive and subtractive processes respectively, layer by layer to form the structure. This method reduces material waste by cutting the support structure layer and the part forming layer, but the process is complex, requiring frequent switching of laser heads, resulting in low efficiency, and it is difficult to guarantee the surface finish of the high-precision sealing surface of the thin-walled valve seat.

[0004] Patent CN117001275A proposes a method for manufacturing complex thin-walled metal components using a combination of local additive manufacturing and hot gas expansion. While this method solves the problem of preparing large-sized blanks, the gas expansion process can easily lead to uneven thickness in thin-walled areas, affecting the sealing performance of valve seats.

[0005] Patent CN 111974998 A discloses an additive manufacturing method for thin-walled titanium alloy parts, which suppresses deformation by adding ribs or lattice support structures and improves mechanical properties by combining heat treatment. However, after the support structure is removed, holes or microcracks are easily left on the valve seat surface, requiring additional grinding and increasing process costs.

[0006] Patent CN114273675B discloses a non-contact, shape-based additive manufacturing method. It employs a conformal support model with a gap design around the thin-walled part, reducing the difficulty of support removal. This method ensures the support contour does not coincide with the part through slicing and combines stress-relieving heat treatment to reduce deformation. However, its control of the gap between the support and the part relies on precise modeling, limiting its applicability to thin-walled valve seats with multi-channel cavities and preventing the simultaneous deposition of functionally graded materials.

[0007] Existing additive manufacturing methods suffer from insufficient structural adaptability, limited material properties, and post-processing damage to the matrix in the manufacture of valve seats with weak rigidity and complex thin-walled structures. These problems lead to poor sealing performance, low forming efficiency, and high overall cost. Specifically: Low forming accuracy of irregular structures: Traditional electron beam / laser additive manufacturing technology (such as CN 119282148 A) is limited by fixed magnetic field parameters or scanning path planning, making it difficult to match complex geometric features such as multi-channel inner cavity of valve seat and irregular sealing surface. It requires post-processing correction, which increases costs.

[0008] Material performance mismatch with operating conditions: Existing technologies (such as CN 111974998 A) mostly use single materials or general alloys, lacking a gradient performance synergistic design for the valve seat sealing surface (wear resistance) and the matrix (corrosion resistance), resulting in a high risk of sealing failure under high temperature and high pressure environments.

[0009] Damaged substrate removal by support structure: Mechanical / chemical support removal processes (such as CN111974998A, CN114273675B) are prone to leaving pores or microcracks on thin-walled surfaces, requiring secondary polishing and affecting the integrity of the sealing surface.

[0010] The contradiction between process efficiency and forming quality: Composite processes (such as CN117001010A dual laser head switching, CN117001275A air expansion forming) lead to process complexity, reduced efficiency, and difficulty in balancing the thickness uniformity and surface finish of thin-walled areas. Summary of the Invention

[0011] The purpose of this invention is to provide an additive manufacturing method for weakly rigid complex thin-walled valve seats, which can solve the problems of low forming accuracy of thin-walled structures and deformation and cracking caused by thermal stress concentration in the prior art. High-precision forming is achieved through a closed-loop technology chain of model optimization, parameter control and process monitoring.

[0012] The technical solution of the present invention is as follows: An additive manufacturing method for a weakly rigid complex thin-walled valve seat, comprising the following steps: Step 1: Model optimization and support design; Step 2: Adjustment of process parameters in different regions; Step 3: Additive manufacturing and online monitoring; Step 4: Post-processing and quality verification.

[0013] In step 1, topological interlayer filling is performed between the model optimization steps: a honeycomb or lattice porous structure is used to fill the space between the inner and outer walls of the valve seat. The model optimization includes determining the optimal interlayer density and structural form through simulation analysis, with the interlayer density controlled at 5-10 g / cm³. 3 With a porosity of 30%-50%, it ensures a 20%-30% increase in thermal conductivity.

[0014] The support design in step 1 includes local reinforcing rib design, which involves designing and adding radial reinforcing ribs to the overhanging area and thin-walled part of the valve seat. The reinforcing ribs are 0.5-1mm wide, 4-8mm high, and 2-3mm apart, ensuring that the bending strength is increased by 15%-20%.

[0015] The support design in step 1 includes pre-deformation compensation: based on the thermo-mechanical coupling simulation model, the thermal shrinkage of the valve seat during the additive manufacturing process is predicted. According to the prediction results, the wall thickness of the original model is compensated in reverse. The calculation process of the compensation amount Δ is: Δ = 0.05 × wall thickness + 0.1 mm. After compensation, the dimensional error is controlled within ±0.1 mm to ensure that the forming accuracy reaches IT7 level.

[0016] Step 2 includes matching laser power with scanning speed: based on the relationship between wall thickness and laser power D= In the formula: D is the wall thickness; n is the number of scanning passes; P is the laser power; V is the scanning speed; k is the material thermal property coefficient; and the process parameters are set differently, where: For thick-walled regions D > 2 mm: laser power 250-350 W, scanning speed 700-1200 mm / s; Thin-walled regions D≤2mm: laser power 150-250W, scanning speed 900-1500mm / s; Control the energy input at 50-100J / mm 3 .

[0017] Step 2 includes layer thickness and contour control: during the additive manufacturing process, the layer thickness is controlled between 40-60μm, the contour scanning number is 2-3 times, and the substrate preheating temperature is controlled within the range of 150-200℃.

[0018] Step 3 includes monitoring the forming process using selective laser melting equipment for additive manufacturing of the valve seat; and includes dynamic parameter adjustment: when abnormal powder spreading in the thin-walled area is detected, the process parameters are adjusted, including reducing the laser power by 10-15% or increasing the scanning speed by 20%.

[0019] Step 4 includes powder removal and support removal. After additive manufacturing is completed, a powder removal device is used to remove residual powder from the surface of the valve seat.

[0020] Step 4 includes forming quality inspection, visually observing the formed valve seat to check for obvious defects on the surface, cutting samples from thin-walled and thick-walled areas respectively, and observing the internal forming quality of the cut samples using an optical electron microscope.

[0021] The beneficial effects of this invention are as follows: First, by adopting a topological sandwich and reinforcing rib design, the thermal stress is effectively dispersed and local deformation is suppressed by filling the space between the inner and outer walls with a honeycomb / lattice porous structure and combining it with a radial reinforcing rib layout in the overhanging area. Second, a pre-deformation compensation technology is introduced, which performs reverse compensation on the original wall thickness based on a thermo-mechanical coupling model (Δ=0.05×wall thickness+0.1mm). Furthermore, by adjusting the parameters in different regions, the process parameters of the thick-walled and thin-walled regions are set differently, reducing the heat input in the thin-walled region by 30-40%. Finally, an integrated online monitoring and closed-loop correction system is used to control the laser power and scanning speed in real time, effectively suppressing excessive heat input in the thin-walled region, and systematically solving the problems of deformation, cracking and dimensional accuracy in the additive manufacturing of weakly rigid thin-walled valve seats. Attached Figure Description

[0022] Figure 1 A flowchart illustrating an additive manufacturing method for a weakly rigid, complex, thin-walled valve seat provided by this invention. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] The present invention provides an additive manufacturing method for a weakly rigid complex thin-walled valve seat, comprising the following steps: Step 1: Model Optimization and Support Design Topological sandwich filling: A honeycomb or lattice porous structure is used to fill the space between the inner and outer walls of the valve seat. This filling method significantly improves the lightweight nature of the valve seat, and simulation technology can precisely optimize the sandwich density distribution. During optimization, structural rigidity and heat dissipation requirements need to be comprehensively considered to ensure sufficient stability of the valve seat under external loads while avoiding performance degradation due to heat accumulation. Through simulation analysis, the optimal sandwich density and structural form can be determined, thereby achieving optimal valve seat performance. The sandwich density is controlled at 5-10 g / cm³. 3 With a porosity of 30%-50%, it ensures a 20%-30% increase in thermal conductivity.

[0025] Localized reinforcing rib design: Radial reinforcing ribs are designed and added to the overhanging areas and thin-walled sections of the valve seat. These ribs effectively improve the valve seat's resistance to deformation, preventing deformation or cracking caused by stress concentration during manufacturing and use. Through reasonable layout and dimensional design, the reinforcing ribs can significantly improve the mechanical properties of the valve seat without adding excessive weight. The reinforcing ribs are 0.5-1mm wide, 4-8mm high, and spaced 2-3mm apart, ensuring a 15%-20% increase in bending strength.

[0026] Pre-deformation compensation: Based on a thermo-mechanical coupling simulation model, the thermal shrinkage of the valve seat during additive manufacturing is predicted. According to the prediction results, the wall thickness of the original model is compensated in reverse. The calculation formula for the compensation amount Δ is: Δ = 0.05 × wall thickness + 0.1 mm. This pre-deformation compensation measure effectively counteracts the thermal shrinkage during additive manufacturing, ensuring the accuracy of the final formed dimensions of the valve seat. After compensation, the dimensional error is controlled within ±0.1 mm, ensuring forming accuracy reaches IT7 level.

[0027] Step 2: Adjustment of process parameters in different regions Laser power and scanning speed matching: based on the relationship between wall thickness and laser power D= (Where: D is the wall thickness; n is the number of scan passes; P is the laser power; V is the scanning speed) k For the material's thermal properties, process parameters are set differently, where: Thick-walled areas (D > 2mm): Laser power 250-350W, scanning speed 700-1200mm / s; Thin-walled areas (D≤2mm): Laser power 150-250W, scanning speed 900-1500mm / s.

[0028] The energy input (VED = laser power / (scanning speed × spot diameter × layer thickness)) is controlled at 50-100 J / mm. 3 To avoid defects such as incomplete fusion or overheating.

[0029] Layer thickness and contour control: During additive manufacturing, the layer thickness is controlled between 40-60 μm, and the contour scanning number is 2-3 times. Reasonable layer thickness and contour control ensures the fusion quality of the inner and outer walls of the valve seat, avoiding structural defects caused by poor interlayer bonding. Simultaneously, the substrate preheating temperature is controlled within the range of 150-200℃ to reduce the temperature gradient and minimize deformation and cracking caused by thermal stress.

[0030] Step 3: Additive Manufacturing and Online Monitoring Forming process monitoring: The valve seat is manufactured using additive manufacturing with a selective laser melting (model FS811M-U-6). This equipment has a built-in camera system that monitors the printing process in real time. Combined with a powder spreading status recognition system, it can detect defects on the powder-spread surface (such as scratches, protrusions, etc.). Through real-time monitoring, problems in the manufacturing process can be identified and addressed promptly, ensuring the forming quality of the valve seat.

[0031] Dynamic parameter adjustment: When abnormal powder spreading is detected in thin-walled areas, process parameters are adjusted promptly. Specific measures include reducing laser power by 10-15% or increasing scanning speed by 20% to suppress excessive heat input. This dynamic parameter adjustment effectively avoids thermal deformation or cracks caused by excessive heat input, ensuring the forming accuracy and mechanical properties of the valve seat.

[0032] Step 4: Post-processing and quality verification Powder Removal and Support Removal: After additive manufacturing, residual powder is removed from the valve seat surface using a powder removal device. Simultaneously, surface supports are removed using tools such as pliers and files to ensure a smooth, residue-free valve seat surface.

[0033] Forming quality inspection: The formed valve seat is visually inspected to check for obvious defects on the surface (such as cracks, abnormal holes, and foreign matter). In addition, samples are cut from both thin-walled and thick-walled areas, and the internal forming quality of the cut samples is observed using an optical electron microscope. Through visual and microscopic observation, the forming quality of the valve seat can be comprehensively evaluated, providing a basis for subsequent process optimization.

Claims

1. An additive manufacturing method for a weakly rigid complex thin-walled valve seat, characterized in that, Includes the following steps: Step 1: Model optimization and support design; In step 1, topological interlayer filling is performed between the model optimization steps: a honeycomb or lattice porous structure is used to fill the space between the inner and outer walls of the valve seat. The model optimization includes determining the optimal interlayer density and structural form through simulation analysis, with the interlayer density controlled at 5-10 g / cm³. 3 Porosity of 30%-50% ensures a 20%-30% increase in thermal conductivity; Step 2: Adjustment of process parameters in different regions; Step 3: Additive manufacturing and online monitoring; Step 4: Post-processing and quality verification.

2. The additive manufacturing method for a weakly rigid complex thin-walled valve seat as described in claim 1, characterized in that: The support design in step 1 includes local reinforcing rib design, which involves designing and adding radial reinforcing ribs to the overhanging area and thin-walled part of the valve seat. The reinforcing ribs are 0.5-1mm wide, 4-8mm high, and 2-3mm apart, ensuring that the bending strength is increased by 15%-20%.

3. The additive manufacturing method for a weakly rigid complex thin-walled valve seat as described in claim 2, characterized in that: The support design in step 1 includes pre-deformation compensation: based on the thermo-mechanical coupling simulation model, the thermal shrinkage of the valve seat during the additive manufacturing process is predicted. According to the prediction results, the wall thickness of the original model is compensated in reverse. The calculation process of the compensation amount Δ is: Δ = 0.05 × wall thickness + 0.1 mm. After compensation, the dimensional error is controlled within ±0.1 mm to ensure that the forming accuracy reaches IT7 level.

4. The additive manufacturing method for a weakly rigid complex thin-walled valve seat as described in claim 1, characterized in that: Step 2 includes matching laser power with scanning speed: based on the relationship between wall thickness and laser power D= In the formula: D is the wall thickness; n is the number of scanning passes; P is the laser power; V is the scanning speed; k is the material thermal property coefficient; and the process parameters are set differently, where: For thick-walled regions D > 2 mm: laser power 250-350 W, scanning speed 700-1200 mm / s; Thin-walled regions D≤2mm: laser power 150-250W, scanning speed 900-1500mm / s; Control the energy input at 50-100J / mm 3 .

5. The additive manufacturing method for a weakly rigid complex thin-walled valve seat as described in claim 1, characterized in that: Step 2 includes layer thickness and contour control: during the additive manufacturing process, the layer thickness is controlled between 40-60μm, the contour scanning number is 2-3 times, and the substrate preheating temperature is controlled within the range of 150-200℃.

6. The additive manufacturing method for a weakly rigid complex thin-walled valve seat as described in claim 1, characterized in that: Step 3 includes monitoring the forming process using selective laser melting equipment for additive manufacturing of the valve seat; and includes dynamic parameter adjustment: when abnormal powder spreading in the thin-walled area is detected, the process parameters are adjusted, including reducing the laser power by 10-15% or increasing the scanning speed by 20%.

7. The additive manufacturing method for a weakly rigid complex thin-walled valve seat as described in claim 1, characterized in that: Step 4 includes powder removal and support removal. After additive manufacturing is completed, a powder removal device is used to remove residual powder from the surface of the valve seat.

8. The additive manufacturing method for a weakly rigid complex thin-walled valve seat as described in claim 1, characterized in that: Step 4 includes forming quality inspection, visually observing the formed valve seat to check for obvious defects on the surface, cutting samples from thin-walled and thick-walled areas respectively, and observing the internal forming quality of the cut samples using an optical electron microscope.

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