High-precision lathe bed casting process based on gradient alloy

Abstract

This invention relates to the field of alloy casting technology and discloses a high-precision lathe bed casting process based on gradient alloys. The process involves coating the bottom and sides of the guideway cavity of the lost foam pattern with a breathable, anti-adhesion sand coating containing sawdust. Chills are attached to the uncoated working surface area, and two independently controlled gating systems are established for the substrate and guideways. Under negative pressure, the substrate alloy liquid is poured first, and after the liquid level rises above a predetermined height above the lower edge of the cavity, the guideway alloy liquid is poured. Subsequently, the process undergoes overall stress-relief annealing and local vibration aging treatment of the substrate. This invention, through the synergistic effect of step-by-step pouring and chiller cooling, forms an element diffusion transition zone at the interface, achieving a bonding strength of over 410 MPa. The substrate exhibits excellent vibration absorption, with guideway wear of 14-20 mg, achieving integrated manufacturing of a high-wear-resistant guideway and a high-vibration-absorbing substrate, significantly improving the precision retention of the lathe bed.

Description

Technical Field

[0001] This invention relates to the field of alloy casting technology, specifically to a high-precision lathe bed casting process based on gradient alloys. Background Technology

[0002] As a core component of machine tools, the lathe bed's guideway working surface wear resistance, dimensional accuracy retention, and overall vibration absorption directly determine the machine tool's machining accuracy and service life. Traditional lathe beds are mostly cast from a single piece of gray cast iron. While this offers good vibration damping and casting processability, the guideway surface hardness is limited, and its wear resistance still fails to meet the long-term demands of modern high-precision, heavy-cutting operations. To address this issue, the industry has attempted to embed high-alloy wear-resistant inserts into the guideway surface, bonding the wear-resistant material to the substrate via mechanical connection or brazing. However, beds prepared using this method suffer from low interfacial bonding strength, significant internal stress between the inserts and the substrate due to differences in thermal expansion coefficients, and a tendency to loosen or even peel off during long-term service. These defects severely restrict the long-term maintenance of machine tool accuracy. If the residual stress generated after casting solidification is not effectively eliminated, the bed will continue to deform during subsequent machining and service, resulting in a loss of accuracy. Therefore, there is an urgent need to develop a high-precision lathe bed casting process based on gradient alloys. Summary of the Invention

[0003] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a high-precision lathe bed casting process based on gradient alloys.

[0004] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: The high-precision lathe bed casting process based on gradient alloys includes the following steps: S1. Make a lost foam pattern of the lathe bed, and machine the guide rail cavity in the area corresponding to the working surface of the bed guide rail on the pattern surface; apply a breathable anti-sticking sand coating to the bottom and side surfaces of the guide rail cavity and dry it; connect the independent base casting system and guide rail casting system on the pattern, and control the on / off of the two casting systems independently. S2. Place the pattern in a sand box, fill it with dry sand and compact it, and pre-place a chill in the sand box so that the chill fits against the uncoated area of ​​the guide rail cavity on the pattern; connect the vacuum device and evacuate the sand box to negative pressure. S3. Under negative pressure conditions, the guide rail gating system is kept closed. First, the base alloy liquid is poured through the base gating system until the liquid surface submerges the lower edge of the guide rail cavity and is higher than the predetermined height, then the guide rail alloy liquid is poured through the guide rail gating system. S4. After pouring, maintain negative pressure until the casting is completely solidified, open the box and clean it, then perform overall low-temperature stress relief annealing, rough machining, and then perform local vibration aging treatment on the bed base area. Finally, perform fine machining on the guide rail working surface.

[0005] Furthermore, in step S1, the depth of the guide rail cavity is 12-18mm.

[0006] Furthermore, in step S1, the breathable anti-sticking sand coating is composed of zircon powder, silica sol, and sawdust powder accounting for 2-3% of the total mass of the coating, and the coating thickness is 0.2-0.3 mm.

[0007] Furthermore, in step S1, the base casting system is a bottom-pouring stepped gating system, the guide rail casting system is a top-pouring slotted gating system, and the total cross-sectional area of ​​the guide rail casting system is 1 / 3 to 1 / 4 of the total cross-sectional area of ​​the base casting system.

[0008] Furthermore, in step S2, the chill is a copper-chromium alloy chill with a thickness of 1.5-2 times the depth of the guide rail alloy cavity, and the working surface of the chill is coated with a high-temperature refractory coating.

[0009] Further, in step S3, the base alloy liquid comprises, by mass percentage: 3.1-3.4% carbon, 1.7-2.0% silicon, 0.9-1.2% manganese, 0.6-0.9% copper, 0.05-0.08% tin, ≤0.07% phosphorus, ≤0.06% sulfur, with the balance being iron; during smelting, after removing slag at 1530-1550℃, 0.3-0.5% of 75% ferrosilicon inoculant by mass of the base alloy liquid is added, the casting temperature is 1490-1510℃, and the casting speed is 0.4-0.5m / s.

[0010] Further, in step S3, the guide rail alloy liquid comprises, by mass percentage: 2.8-3.5% carbon, 15-18% chromium, 1.0-2.0% molybdenum, 0.5-1.2% vanadium, 0.5-1.0% manganese, 0.8-1.2% silicon, ≤0.05% phosphorus, ≤0.03% sulfur, with the balance being iron; the temperature is raised to 1550-1580℃ during smelting, and 0.05-0.1% silicon-calcium-barium by mass of the guide rail alloy liquid is added before tapping; the pouring temperature is 1500-1520℃, and the pouring speed is 0.3-0.4 m / s.

[0011] Furthermore, in step S3, the base alloy liquid is poured to a predetermined height that is 5-10mm above the lower edge of the guide rail cavity, and the guide rail alloy liquid is poured 8-12 seconds after the pouring is completed.

[0012] Furthermore, in step S4, the overall low-temperature stress-relief annealing temperature is 450-480℃, the holding time is 8-10h, and then the furnace is cooled to below 200℃ before being removed from the furnace.

[0013] Furthermore, in step S4, the local vibration aging treatment involves applying a rotational speed of 3000-5000 rpm to the bed base area using a multi-point vibrator, with a treatment time of 20-30 minutes.

[0014] (iii) Beneficial technical effects This invention provides a high-precision lathe bed casting process based on gradient alloys. It employs independent matrix gating and guideway gating systems, precisely controlling the pouring sequence, liquid level, and delay time to create an element diffusion transition zone at the interface, achieving a gentle gradient distribution of alloying elements and avoiding stress concentration caused by abrupt compositional changes. The bottom and sides of the guideway cavity are coated with a breathable, anti-sticking sand coating containing sawdust, while the guideway working surface area where chills are attached remains uncoated. This allows the guideway alloy liquid to solidify rapidly under quenching conditions, while the breathable coating ensures smooth gas escape from the cavity sides and bottom, preventing porosity defects. The matrix alloy liquid balances load-bearing stiffness and vibration absorption performance, reducing the matrix's thermal expansion coefficient and matching the guideway alloy layer to minimize interfacial thermal stress. Overall low-temperature stress-relief annealing, combined with local vibration aging treatment after rough machining, applies vibration at specific frequencies and times to the matrix area to release residual stress. Finally, finish machining yields a dimensionally stable and durable guideway working surface. Detailed Implementation

[0015] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0016] Copper-chromium alloy chill: 1% chromium content, thickness is twice the depth of the guide rail cavity; High-temperature refractory coating: Alcohol-based zircon powder coating, purchased from Suzhou Xingye Materials Technology Co., Ltd.; Example 1

[0017] A high-precision lathe bed casting process based on gradient alloys includes the following steps: S1. Create a lost foam pattern of the lathe bed, and machine a guide rail cavity on the surface of the pattern corresponding to the working surface of the bed guide rail. The depth of the guide rail cavity is 12mm. Apply a breathable anti-sticking sand coating to the bottom and sides of the guide rail cavity and dry it. The breathable anti-sticking sand coating is a mixture of zircon powder, silica sol and sawdust powder accounting for 2% of the total mass of the coating, and the coating thickness is 0.2mm. Connect the independent base casting system and the guide rail casting system on the pattern. The two casting systems are independently controlled. The base casting system is a bottom-pouring stepped gating system, and the guide rail casting system is a top-pouring slotted gating system. The total cross-sectional area of ​​the gating system of the guide rail casting system is 1 / 3 of the total cross-sectional area of ​​the gating system of the base casting system. S2. Place the pattern in a sand box, fill it with dry sand and compact it. Place a copper-chromium alloy chill in the sand box. The thickness of the chill is 1.5 times the depth of the guide rail cavity. The working surface of the chill is coated with a high-temperature refractory coating so that the chill fits into the uncoated area of ​​the guide rail cavity on the pattern. Connect a vacuum device and evacuate the sand box to a negative pressure of -0.04MPa. S3. Under negative pressure conditions, the guide rail casting system remains closed. First, the base alloy liquid is poured through the base casting system. The base alloy liquid, by mass percentage, comprises: 3.1% carbon, 1.7% silicon, 0.9% manganese, 0.6% copper, 0.05% tin, ≤0.07% phosphorus, ≤0.06% sulfur, with the balance being iron. During smelting, the temperature is raised to 1530℃, slag is removed, and then 0.3% (by mass) of 75% ferrosilicon inoculant is added to the base alloy liquid. The pouring temperature is 1490℃, and the pouring speed is 0.4 m / s. The liquid is poured to the surface... The process is stopped after submerging the lower edge of the guide rail cavity and extending 5mm above it. After a delay of 8 seconds, the guide rail alloy liquid is poured through the guide rail casting system. The guide rail alloy liquid, by mass percentage, comprises: 2.8% carbon, 15% chromium, 1.0% molybdenum, 0.5% vanadium, 0.5% manganese, 0.8% silicon, ≤0.05% phosphorus, ≤0.03% sulfur, with the balance being iron. The melting temperature is raised to 1550℃, and 0.05% by mass of silicon-calcium-barium is added before tapping. The pouring temperature is 1500℃, and the pouring speed is 0.3m / s. S4. After pouring, maintain negative pressure until the casting is completely solidified, open the box and clean it, then perform overall low-temperature stress-relief annealing at 450℃ for 8 hours, and then cool it in the furnace to below 200℃ before removing it from the furnace; after rough machining, perform local vibration aging treatment on the bed base area, using a multi-point vibrator to apply a rotation speed of 3000 rpm to the bed base area for 20 minutes; finally, perform fine machining on the guide rail working surface.

[0018] Example 2

[0019] A high-precision lathe bed casting process based on gradient alloys includes the following steps: S1. Create a lost foam pattern of the lathe bed, and machine guide rail cavities in the area corresponding to the working surface of the bed guide rail on the pattern surface. The depth of the guide rail cavity is 15mm. Apply a breathable anti-adhesion sand coating to the bottom and sides of the guide rail cavity and dry it. The breathable anti-adhesion sand coating is composed of zircon powder, silica sol, and sawdust powder accounting for 2.5% of the total mass of the coating. The coating thickness is 0.2mm. Connect the independent base casting system and guide rail casting system on the pattern. The two casting systems are independently controlled. The base casting system is a bottom-pouring stepped gating system, and the guide rail casting system is a top-pouring slotted gating system. The total cross-sectional area of ​​the guide rail gating system is 1 / 3 of the total cross-sectional area of ​​the base casting system gating system. S2. Place the pattern in a sand box, fill it with dry sand and compact it. Place a copper-chromium alloy chill in the sand box. The thickness of the chill is twice the depth of the guide rail cavity. The working surface of the chill is coated with a high-temperature refractory coating so that the chill fits into the uncoated area of ​​the guide rail cavity on the pattern. Connect a vacuum device and evacuate the sand box to a negative pressure of -0.05MPa. S3. Under negative pressure conditions, the guide rail casting system remains closed. First, the base alloy liquid is poured through the base casting system. The base alloy liquid, by mass percentage, comprises: 3.2% carbon, 1.7% silicon, 1.0% manganese, 0.7% copper, 0.06% tin, ≤0.07% phosphorus, ≤0.06% sulfur, with the balance being iron. During smelting, the temperature is raised to 1540℃, slag is removed, and then 0.4% (by mass) of 75% ferrosilicon inoculant is added to the base alloy liquid. The pouring temperature is 1500℃, and the pouring speed is 0.4 m / s. The liquid is poured to the surface... The process is stopped after submerging the lower edge of the guide rail cavity and extending 10mm above it. After a 9s delay, the guide rail alloy liquid is poured through the guide rail casting system. The guide rail alloy liquid, by mass percentage, comprises: 2.9% carbon, 16% chromium, 1.5% molybdenum, 0.5% vanadium, 1.0% manganese, 0.9% silicon, ≤0.05% phosphorus, ≤0.03% sulfur, with the balance being iron. The melting temperature is raised to 1560℃, and 0.08% by mass of silicon-calcium-barium is added before tapping. The pouring temperature is 1500℃, and the pouring speed is 0.3m / s. S4. After pouring, maintain negative pressure until the casting is completely solidified, open the box and clean it, then perform overall low-temperature stress-relief annealing at 460℃ for 10 hours, and then cool it in the furnace to below 200℃ before removing it from the furnace; after rough machining, perform local vibration aging treatment on the bed base area, using a multi-point vibrator to apply a rotation speed of 4000 rpm to the bed base area for 25 minutes; finally, perform fine machining on the guide rail working surface.

[0020] Example 3

[0021] A high-precision lathe bed casting process based on gradient alloys includes the following steps: S1. Create a lost foam pattern of the lathe bed, and machine a guide rail cavity on the surface of the pattern corresponding to the working surface of the bed guide rail. The depth of the guide rail cavity is 15mm. Apply a breathable anti-adhesion sand coating to the bottom and sides of the guide rail cavity and dry it. The breathable anti-adhesion sand coating is composed of zircon powder, silica sol and sawdust powder accounting for 3% of the total mass of the coating, and the coating thickness is 0.3mm. Connect the independent base casting system and the guide rail casting system on the pattern. The two casting systems are independently controlled. The base casting system is a bottom-pouring stepped gating system, and the guide rail casting system is a top-pouring slotted gating system. The total cross-sectional area of ​​the gating system of the guide rail casting system is 1 / 4 of the total cross-sectional area of ​​the gating system of the base casting system. S2. Place the pattern in a sand box, fill it with dry sand and compact it. Place a copper-chromium alloy chill in the sand box. The thickness of the chill is 1.5 times the depth of the guide rail cavity. The working surface of the chill is coated with a high-temperature refractory coating so that the chill fits into the uncoated area of ​​the guide rail cavity on the pattern. Connect a vacuum device and evacuate the sand box to a negative pressure of -0.04MPa. S3. Under negative pressure conditions, the guide rail casting system remains closed. First, the base alloy liquid is poured through the base casting system. The base alloy liquid, by mass percentage, comprises: 3.3% carbon, 1.9% silicon, 1.2% manganese, 0.8% copper, 0.08% tin, ≤0.07% phosphorus, ≤0.06% sulfur, with the balance being iron. During smelting, the temperature is raised to 1530℃, slag is removed, and then 0.5% (by mass) of 75% ferrosilicon inoculant is added to the base alloy liquid. The pouring temperature is 1510℃, and the pouring speed is 0.4 m / s. The liquid is poured to the surface... The process is stopped after submerging the lower edge of the guide rail cavity and extending 5mm above it. After a 10-second delay, the guide rail alloy liquid is poured through the guide rail casting system. The guide rail alloy liquid, by mass percentage, comprises: 3.2% carbon, 18% chromium, 1.5% molybdenum, 1.0% vanadium, 0.6% manganese, 1.2% silicon, ≤0.05% phosphorus, ≤0.03% sulfur, with the balance being iron. The melting temperature is raised to 1550℃, and 0.1% by mass of silicon-calcium-barium is added before tapping. The pouring temperature is 1520℃, and the pouring speed is 0.4m / s. S4. After pouring, maintain negative pressure until the casting is completely solidified, open the box and clean it, then perform overall low-temperature stress-relieving annealing at 460℃ for 8 hours, and then cool it in the furnace to below 200℃ before removing it from the furnace; after rough machining, perform local vibration aging treatment on the bed base area, using a multi-point vibrator to apply a rotation speed of 3000 rpm to the bed base area for 25 minutes; finally, perform fine machining on the guide rail working surface.

[0022] Example 4

[0023] A high-precision lathe bed casting process based on gradient alloys includes the following steps: S1. Create a lost foam pattern of the lathe bed, and machine a guide rail cavity on the surface of the pattern corresponding to the working surface of the bed guide rail. The depth of the guide rail cavity is 18mm. Apply a breathable anti-adhesion sand coating to the bottom and sides of the guide rail cavity and dry it. The breathable anti-adhesion sand coating is composed of zircon powder, silica sol and sawdust powder accounting for 2.2% of the total mass of the coating, and the coating thickness is 0.2mm. Connect the independent base casting system and guide rail casting system on the pattern. The two casting systems are independently controlled. The base casting system is a bottom-pouring stepped gating system, and the guide rail casting system is a top-pouring slotted gating system. The total cross-sectional area of ​​the gating system of the guide rail casting system is 1 / 4 of the total cross-sectional area of ​​the gating system of the base casting system. S2. Place the pattern in a sand box, fill it with dry sand and compact it, and pre-place a copper-chromium alloy chill in the sand box. The thickness of the chill is twice the depth of the guide rail cavity. The working surface of the chill is coated with a high-temperature refractory coating so that the chill fits into the uncoated area of ​​the guide rail cavity on the pattern. Connect a vacuum device and evacuate the sand box to a negative pressure of -0.06MPa. S3. Under negative pressure conditions, the guide rail casting system remains closed. First, the base alloy liquid is poured through the base casting system. The base alloy liquid, by mass percentage, comprises: 3.2% carbon, 2.0% silicon, 0.9% manganese, 0.6% copper, 0.06% tin, ≤0.07% phosphorus, ≤0.06% sulfur, with the balance being iron. During smelting, the temperature is raised to 1550℃, slag is removed, and then 0.4% (by mass) of 75% ferrosilicon inoculant is added to the base alloy liquid. The pouring temperature is 1500℃, and the pouring speed is 0.4 m / s. The liquid is poured until it submerges... The process stops after the guide rail cavity is 10mm above the lower edge and then continues for 12 seconds before pouring the guide rail alloy liquid through the guide rail casting system. The guide rail alloy liquid, by mass percentage, comprises: 2.8% carbon, 15% chromium, 1.5% molybdenum, 1.2% vanadium, 0.5% manganese, 1.0% silicon, ≤0.05% phosphorus, ≤0.03% sulfur, with the balance being iron. The melting temperature is raised to 1560℃, and 0.05% by mass of silicon-calcium-barium is added before tapping. The pouring temperature is 1520℃, and the pouring speed is 0.4m / s. S4. After pouring, maintain negative pressure until the casting is completely solidified, open the box and clean it, then perform overall low-temperature stress-relieving annealing at 450℃ for 8 hours, and then cool it in the furnace to below 200℃ before removing it from the furnace; after rough machining, perform local vibration aging treatment on the bed base area, using a multi-point vibrator to apply a rotation speed of 4000 rpm to the bed base area for 20 minutes; finally, perform fine machining on the guide rail working surface.

[0024] Example 5

[0025] A high-precision lathe bed casting process based on gradient alloys includes the following steps: S1. Create a lost foam pattern of the lathe bed, and machine a guide rail cavity on the surface of the pattern corresponding to the working surface of the bed guide rail. The depth of the guide rail cavity is 18mm. Apply a breathable anti-adhesion sand coating to the bottom and sides of the guide rail cavity and dry it. The breathable anti-adhesion sand coating is composed of zircon powder, silica sol and sawdust powder accounting for 3% of the total mass of the coating, and the coating thickness is 0.3mm. Connect the independent base casting system and the guide rail casting system on the pattern. The two casting systems are independently controlled. The base casting system is a bottom-pouring stepped gating system, and the guide rail casting system is a top-pouring slotted gating system. The total cross-sectional area of ​​the gating system of the guide rail casting system is 1 / 4 of the total cross-sectional area of ​​the gating system of the base casting system. S2. Place the pattern in a sand box, fill it with dry sand and compact it, and pre-place a copper-chromium alloy chill in the sand box. The thickness of the chill is twice the depth of the guide rail cavity. The working surface of the chill is coated with a high-temperature refractory coating so that the chill fits into the uncoated area of ​​the guide rail cavity on the pattern. Connect a vacuum device and evacuate the sand box to a negative pressure of -0.06MPa. S3. Under negative pressure conditions, the guide rail casting system remains closed. First, the base alloy liquid is poured through the base casting system. The base alloy liquid, by mass percentage, comprises: 3.4% carbon, 2.0% silicon, 1.2% manganese, 0.9% copper, 0.08% tin, ≤0.07% phosphorus, ≤0.06% sulfur, with the balance being iron. During smelting, the temperature is raised to 1550℃, slag is removed, and then 0.5% (by mass) of 75% ferrosilicon inoculant is added to the base alloy liquid. The pouring temperature is 1510℃, and the pouring speed is 0.5 m / s. The liquid is poured to the surface... The process is stopped after submerging the lower edge of the guide rail cavity and extending 10mm above it. After a 12-second delay, the guide rail alloy liquid is poured through the guide rail casting system. The guide rail alloy liquid, by mass percentage, comprises: 3.5% carbon, 18% chromium, 2.0% molybdenum, 1.2% vanadium, 1.0% manganese, 1.2% silicon, ≤0.05% phosphorus, ≤0.03% sulfur, with the balance being iron. The melting temperature is raised to 1580℃, and 0.1% by mass of silicon-calcium-barium is added before tapping. The pouring temperature is 1520℃, and the pouring speed is 0.4m / s. S4. After pouring, maintain negative pressure until the casting is completely solidified, open the box and clean it, then perform overall low-temperature stress-relief annealing at 480℃ for 10 hours, and then cool it in the furnace to below 200℃ before removing it from the furnace; after rough machining, perform local vibration aging treatment on the bed base area, using a multi-point vibrator to apply a rotation speed of 5000 rpm to the bed base area for 30 minutes; finally, perform fine machining on the guide rail working surface.

[0026] Comparative Example 1: The step-by-step casting and guide rail alloy liquid were cancelled, and only the base alloy liquid was used for overall casting. There were no chills, and the rest of the process was the same as in Example 3.

[0027] Comparative Example 2: Instead of pouring in stages during the casting process, cast iron inserts are pre-placed in the guide rail cavity. The composition is the same as the guide rail alloy in Example 3. The inserts are pre-cast and annealed, and the rest of the process is the same as in Example 3.

[0028] Comparative Example 3: The composition of the base alloy liquid by mass percentage is: carbon 3.2%, silicon 1.9%, manganese 1.0%, phosphorus ≤0.07%, sulfur ≤0.06%, with the balance being iron. The remaining processes are the same as in Example 3.

[0029] Comparative Example 4: The composition of the guide rail alloy liquid by mass percentage is: carbon 3.2%, chromium 18%, manganese 0.6%, silicon 1.2%, phosphorus ≤0.05%, sulfur ≤0.03%, with the balance being iron. The remaining processes are the same as in Example 3.

[0030] Comparative Example 5: After the base alloy liquid is poured to the predetermined height in step S3, the guide rail alloy liquid is poured immediately, and the remaining processes are the same as in Example 3.

[0031] Test items: 1. Microstructure of the interface: A cross-sectional sample of the interface between the guide rail and the substrate was taken, polished, and then etched with 4% nitric acid alcohol. The interface fusion state, defects, and the width of the element diffusion zone were observed by optical microscope and scanning electron microscope.

[0032] 2. Interface bond strength: According to GB / T 228.1-2021, take a transverse tensile specimen (10 mm in diameter) at the interface and determine the tensile strength and fracture location.

[0033] 3. Shock absorption test: The cantilever beam resonance attenuation method was adopted. A strip sample of 120mm×20mm×10mm was cut from the matrix area (20mm below the joint surface). The sample was removed after the initial vibration was applied by the exciter. The amplitude attenuation curve was recorded by the acceleration sensor and the logarithmic attenuation rate δ was calculated.

[0034] 4. Residual stress in the substrate area: The residual stress on the surface is measured using the blind hole method in the mounting area of ​​the substrate guide rail (20mm from the mating surface).

[0035] 5. Guide rail wear resistance: MM-200 wear testing machine, with a grinding ring made of quenched GCr15 (HRC62), load 200N, sliding speed 0.5m / s, dry friction for 2h, and weighing to measure the wear amount.

[0036] Table 1. Results of Interface Adhesion Test Example 1 good 85 410 Example 2 good 90 410 Example 3 good 88 425 Example 4 good 90 428 Example 5 good 92 430 Comparative Example 1 No interface - 315 Comparative Example 2 Gaps + Oxide Inclusions 15 175 Comparative Example 3 good 55 345 Comparative Example 4 good 80 380 Comparative Example 5 Fusion but localized scouring 25 265 Table 2 Physical Performance Test Results Example 1 0.048 45 18 Example 2 0.046 45 16 Example 3 0.045 48 14 Example 4 0.045 52 20 Example 5 0.043 53 14 Comparative Example 1 0.042 35 125 Comparative Example 2 0.044 68 28 Comparative Example 3 0.049 88 17 Comparative Example 4 0.045 42 32 Comparative Example 5 0.042 85 17 As shown in the table above, Examples 1-5 exhibit good interface fusion, with a diffusion zone width of 85-92 μm, a bonding strength of 410-430 MPa, a logarithmic decay rate of 0.043-0.048, residual stress of 45-53 MPa, and guide rail wear of 14-20 mg, demonstrating excellent overall performance. Comparative Example 1 shows guide rail wear as high as 125 mg, failing to meet wear resistance requirements. Comparative Example 2 has gaps and inclusions at the interface of the pre-placed insert, resulting in a bonding strength of only 175 MPa and a risk of peeling. Comparative Example 3 has a substrate lacking copper and tin, with residual stress rising to 88 MPa, indicating inferior substrate performance compared to the examples. Comparative Example 4 has a guide rail lacking molybdenum and vanadium, resulting in wear of 82 mg and significantly insufficient wear resistance. Comparative Example 5, without delayed casting, shows interface erosion and melting, a diffusion zone of only 25 μm, a bonding strength reduced to 265 MPa, and residual stress increased to 85 MPa.

[0037] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-precision lathe bed casting process based on gradient alloys, characterized in that, Includes the following steps: S1. Make a lost foam pattern of the lathe bed, and machine the guide rail cavity in the area corresponding to the working surface of the bed guide rail on the pattern surface; apply a breathable anti-sticking sand coating to the bottom and side surfaces of the guide rail cavity and dry it; connect the independent base casting system and guide rail casting system on the pattern, and control the on / off of the two casting systems independently. S2. Place the pattern in a sand box, fill it with dry sand and compact it, and pre-place a chill in the sand box so that the chill fits against the uncoated area of ​​the guide rail cavity on the pattern; connect the vacuum device and evacuate the sand box to negative pressure. S3. Under negative pressure conditions, the guide rail gating system is kept closed. First, the base alloy liquid is poured through the base gating system until the liquid surface submerges the lower edge of the guide rail cavity and is higher than the predetermined height, then the guide rail alloy liquid is poured through the guide rail gating system. S4. After pouring, maintain negative pressure until the casting is completely solidified, open the box and clean it, then perform overall low-temperature stress relief annealing, rough machining, and then perform local vibration aging treatment on the bed base area. Finally, perform fine machining on the guide rail working surface.

2. The high-precision lathe bed casting process based on gradient alloys according to claim 1, characterized in that, The depth of the guide cavity in step S1 is 12-18mm.

3. The high-precision lathe bed casting process based on gradient alloys according to claim 1, characterized in that, In step S1, the breathable anti-sticking sand coating is made of zircon powder, silica sol and sawdust powder accounting for 2-3% of the total mass of the coating, and the coating thickness is 0.2-0.3 mm.

4. The high-precision lathe bed casting process based on gradient alloys according to claim 1, characterized in that, In step S1, the base casting system is a bottom-pouring stepped gating system, and the guide rail casting system is a top-pouring slotted gating system. The total cross-sectional area of ​​the guide rail casting system is 1 / 3 to 1 / 4 of the total cross-sectional area of ​​the base casting system.

5. The high-precision lathe bed casting process based on gradient alloys according to claim 1, characterized in that, In step S2, the chill is a copper-chromium alloy chill with a thickness of 1.5-2 times the depth of the guide rail alloy cavity. The working surface of the chill is coated with a high-temperature refractory coating.

6. The high-precision lathe bed casting process based on gradient alloys according to claim 1, characterized in that, In step S3, the base alloy liquid comprises, by mass percentage: 3.1-3.4% carbon, 1.7-2.0% silicon, 0.9-1.2% manganese, 0.6-0.9% copper, 0.05-0.08% tin, ≤0.07% phosphorus, ≤0.06% sulfur, with the balance being iron. During smelting, the temperature is raised to 1530-1550℃, and after slag removal, 0.3-0.5% of 75% ferrosilicon inoculant by mass of the base alloy liquid is added. The casting temperature is 1490-1510℃, and the casting speed is 0.4-0.5 m / s.

7. The high-precision lathe bed casting process based on gradient alloys according to claim 1, characterized in that, In step S3, the guide rail alloy liquid comprises, by mass percentage: 2.8-3.5% carbon, 15-18% chromium, 1.0-2.0% molybdenum, 0.5-1.2% vanadium, 0.5-1.0% manganese, 0.8-1.2% silicon, ≤0.05% phosphorus, ≤0.03% sulfur, with the balance being iron; the temperature is raised to 1550-1580℃ during smelting, and 0.05-0.1% silicon-calcium-barium by mass of the guide rail alloy liquid is added before tapping; the pouring temperature is 1500-1520℃, and the pouring speed is 0.3-0.4 m / s.

8. The high-precision lathe bed casting process based on gradient alloys according to claim 1, characterized in that, In step S3, the base alloy liquid is poured to a predetermined height that is 5-10mm above the lower edge of the guide rail cavity. After pouring, the guide rail alloy liquid is poured for 8-12 seconds.

9. The high-precision lathe bed casting process based on gradient alloys according to claim 1, characterized in that, In step S4, the overall low-temperature stress-relief annealing temperature is 450-480℃, the holding time is 8-10h, and then it is cooled in the furnace to below 200℃ before being taken out of the furnace.

10. The high-precision lathe bed casting process based on gradient alloys according to claim 1, characterized in that, In step S4, the local vibration aging treatment involves applying a rotational speed of 3000-5000 rpm to the bed base area using a multi-point vibrator, with a treatment time of 20-30 minutes.