Complex structure casting resin sand gravity casting liquid weight calculation method

Abstract

The invention discloses a complex structure casting resin sand gravity casting liquid weight calculation method, and relates to the technical field of equipment manufacturing, and the method comprises the following steps: building a casting part finished product three-dimensional model; the machining allowance grade is determined according to the nominal size of the part finished product three-dimensional model, and the part finished product three-dimensional model is adjusted based on the machining allowance grade to obtain a process blank model; designing a pouring pipeline model and a riser model; obtaining the volume of each model based on three-dimensional design software; selecting a reasonable volume shrinkage rate epsilon v according to the element content in the raw material molten steel; obtaining a resin sand box expansion rate fv based on measured data; correcting the volume of the process blank model based on the volume shrinkage rate epsilon v and the resin sand box expansion rate fv; and the mass of molten iron needed for pouring is calculated based on the volume of each model. According to the method, the residual molten steel is smaller than or equal to 4%, the yield is 50% or above, the material utilization rate is synchronously increased by 3-10%, cost reduction, energy conservation and zero test are achieved, and the problem that molten steel raw materials are wasted during gravity casting of complex-structure casting resin sand is solved.

Description

Technical Field

[0001] This invention relates to the field of equipment manufacturing technology, and in particular to a method for calculating the weight of resin sand gravity casting liquid for complex structural castings. Background Technology

[0002] In the resin sand gravity casting process for large and complex structural steel castings, accurate calculation of the liquid weight (pouring weight) is a key parameter to ensure casting quality. Current mainstream methods estimate the weight of the gating system and risers by superimposing empirical coefficients on the weight of the casting blank (see Equation 1), where the blank weight is obtained by multiplying the volume of the three-dimensional model by its density and the expansion coefficient. However, this method has the following drawbacks:

[0003] 1. The empirical coefficient has a wide range (15%-30% for gating systems and 10%-25% for risers), and the reliance on manual selection leads to significant calculation errors. In actual production, there are frequent cases where the residual amount of molten steel exceeds 3%, resulting in waste of raw materials and energy.

[0004] 2. The calculation of cavity volume is not accurate enough because it does not take into account the differences in linear shrinkage rates in complex structures. This is especially true for castings with variable cross-sections, such as marine stern shaft supports and thermal power cylinder blocks, where the error is further amplified.

[0005] The aforementioned defects have become more prominent under the trend of large-scale high-end equipment, and there is an urgent need for a high-precision liquid weight calculation method and calculation model that is adapted to the characteristics of resin sand process in order to solve the problem of difficulty in controlling the residual molten steel in resin sand gravity casting process. Summary of the Invention

[0006] In view of the above analysis and in view of the shortcomings of the prior art, the present invention aims to provide a method for calculating the liquid weight of resin sand gravity casting of complex structure castings, and to solve at least one of the following problems in the existing resin sand gravity casting process: large errors in the conversion of casting blank weight and liquid weight due to the use of empirical values ​​and manual values ​​for expansion rate and volume shrinkage rate, respectively, and a lot of waste of molten steel raw materials during pouring.

[0007] The objective of this invention is mainly achieved through the following technical solutions:

[0008] This invention discloses a method for calculating the weight of resin sand gravity casting liquid for complex structure castings, including:

[0009] S1: Create a 3D model of the finished casting part;

[0010] S2: Determine the machining allowance level based on the nominal dimensions of the finished part's 3D model, and adjust the finished part's 3D model based on the machining allowance level to obtain the process blank model;

[0011] S3: Design the gating piping model and riser model based on the process blank model;

[0012] S4: Obtain the volume of the process blank model, the volume of the gating pipeline, and the volume of the riser based on 3D design software;

[0013] S5: Select a reasonable shrinkage rate ε based on the element content in the raw molten steel. v The expansion rate f of the resin sand chamber was obtained based on measured data. v ;

[0014] S6: Based on body shrinkage rate ε v , resin sand expansion rate f v Correct the volume of the process blank model;

[0015] S7: Calculate the required molten iron mass for pouring based on the corrected process blank model volume, pouring pipe volume, and riser volume.

[0016] Preferably, step S1 includes:

[0017] S101. Importing Engineering Drawings:

[0018] Import the 2D engineering drawing or CAD outline of the part into the 3D design software as the modeling benchmark.

[0019] S102, Parametric Modeling:

[0020] Driven by the dimensions of the engineering drawings, and combined with the casting material and structural features, a parametric three-dimensional solid including wall thickness, length and local transition fillets is established;

[0021] S103, Model Validation:

[0022] Check wall thickness, dimensions and engineering Figure 1 Consistency was verified, confirming that the model could be used for subsequent matching of shrinkage rate and expansion rate parameters, and the three-dimensional solid output of the casting was completed.

[0023] Preferably, step S2 includes: measuring the wall thickness and length of the casting on the three-dimensional model and determining the machining allowance level.

[0024] Preferably, step S2 includes:

[0025] S201: First measure the maximum nominal size of the casting, and classify it according to the size range;

[0026] S202: Determine the machining allowance level and specific machining allowance based on the forming method and deformation risk.

[0027] Preferably, step S3 includes:

[0028] S301: Arrange the straight runner, horizontal runner, and inner runner on the blank according to the single or multiple package, bottom injection / top injection scheme to obtain the casting pipeline model;

[0029] S302: Determine the feeding position corresponding to the process blank model according to the modular method or the hot spot circle method, call the standard riser series, automatically generate the light and dark riser entities, and obtain the riser model;

[0030] S303: Software Boolean operations merge the blank, gating system, and riser into a closed volume package, confirming no interference or gaps, and forming an overall three-dimensional process model of the process blank model, gating system, and riser model.

[0031] Preferably, step S4 includes: selecting the model to be tested and obtaining the volume of the model to be tested by measuring the volume segment under the quality attribute of the three-dimensional software.

[0032] Preferably, step S5 includes:

[0033] S501: Obtain the corresponding volumetric shrinkage rate ε in molten steel based on the element content in the molten steel. v ;

[0034] S502: Retrieve the actual resin sand expansion rate table based on the casting weight range, and read f. v .

[0035] Preferably, step S502 includes:

[0036] S5021: Calculate the weight (G) of the casting by weighing or volume × density. c ;

[0037] S5022: Based on weight G c Preliminary classification of expansion rate based on molding sand type;

[0038] S5023: Further refine the initial graded expansion rate of resin sand based on the measured expansion rate data of resin sand.

[0039] Preferably, step S501 includes:

[0040] S5011: Preliminary determination of the shrinkage rate ε of the corresponding cast steel part based on the carbon content in the molten steel. v ;

[0041] S5012: ε is determined based on the content of W, Ni, Mn, Cr, Si, and Al in the molten steel. v The final body contraction rate ε is obtained by correction. v .

[0042] Preferably, step S6 includes:

[0043] S601: ε obtained based on step S5 v f v Calculate the correction factor k = (1 + f v ) / (1+ε v );

[0044] S602: Perform volume correction on the process blank model based on the correction coefficient k. The corrected process blank model V1 satisfies:

[0045] V1 = V0 × k, where V0 is the volume of the process blank model.

[0046] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0047] (1) This invention obtains ε through a standardized method. v f v This technology enables the extraction of measured volume, allowing for precise calculation of molten iron quality with a single click, achieving "one-click precise casting." Data from the 3D model to the total molten iron volume is sourced uniformly, eliminating empirical coefficients and the differences in manual coefficient selection. This results in improved process design efficiency and reduced steel consumption; residual molten steel is ≤4%, preferably below 3%, with a yield of over 50%, saving 0.7t to 5.6t of molten steel per piece, and simultaneously increasing material utilization by 3 to 10 percentage points, achieving cost reduction, energy saving, and zero trial casting.

[0048] (2) The present invention uses the measured expansion rate of resin sand, which avoids the problem of excessive difference between the expansion rates of silica sand and resin sand, reduces the deviation of the expansion rate of the upper casting, improves the calculation accuracy, and avoids the problems of excessive deviation and excessive liquid weight caused by the use of general manual values ​​and silica sand expansion rates in the existing technology.

[0049] (3) The present invention confirms the shrinkage rate of complex parts by the element content in molten steel, thereby achieving accurate determination of the shrinkage rate of complex parts and improving the shortcomings of the prior art in accurately evaluating the shrinkage rate of complex parts. Attached Figure Description

[0050] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0051] Figure 1 This is a schematic diagram of the casting blank of Embodiment 1 of the present invention.

[0052] Figure 2 This is a schematic diagram of the casting blank of Embodiment 2 of the present invention.

[0053] Figure 3 This is a schematic diagram of the casting blank of Embodiment 3 of the present invention.

[0054] Figure 4 This is a schematic diagram of the casting blank of Embodiment 4 of the present invention. Detailed Implementation

[0055] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0056] Definition of large and complex cast steel components:

[0057] Size Specifications

[0058] Maximum outline dimension ≥ 1000mm;

[0059] Structural Indicators

[0060] Multi-directional wall thickness difference > 40 mm or variable cross section exists.

[0061] This invention discloses a method for calculating the weight of resin sand gravity casting liquid for complex structure castings, including:

[0062] S1: Create a 3D model of the finished casting part;

[0063] S2: Determine the machining allowance level based on the nominal dimensions of the finished part's 3D model, and adjust the finished part's 3D model based on the machining allowance level to obtain the process blank model;

[0064] S3: Design the gating piping model and riser model based on the process blank model;

[0065] S4: Obtain the volume of the process blank model, the volume of the gating pipeline, and the volume of the riser based on 3D design software;

[0066] S5: Select a reasonable shrinkage rate ε based on the element content in the raw molten steel. v The expansion rate f of the resin sand chamber was obtained based on measured data. v ;

[0067] S6: Based on body shrinkage rate ε v , resin sand expansion rate f v Correct the volume of the process blank model;

[0068] S7: Calculate the required molten iron mass for pouring based on the corrected process blank model volume, pouring pipe volume, and riser volume.

[0069] During implementation, the three-dimensional solid of the casting output in step S1 provides accurate wall thickness, length, and local structural data, enabling step S2 to quickly match the process blank model. The process blank model output in step S2 provides the basis for the gating and riser models in step S3, forming a complete and closed three-dimensional volume package. This provides step S4 with one-click extraction of the volumes of each part, eliminating the need for additional surface patching or estimation, ensuring consistent volume data without manual intervention. The three sets of measured volumes output in step S4 can be used as direct variables in the formula of step S5, with a volume accuracy of ≤1%, reducing the final molten iron calculation error to ±1.5% and completely eliminating the "coefficient reversal" step. The precise total molten iron output in step S5 allows for casting with a single batching, achieving a residual steel content of ≤1.6%, increasing the yield by 3–8 percentage points, and achieving comprehensive benefits of cost reduction, energy saving, and shortened cycle time. Step S5 outputs ε v f v The quantitative value is used to correct the volume of the solid process blank model in step S6 to the volume of the actual molten steel state model, eliminating the need for traditional repeated trial molding.

[0070] It should be noted that the actual size of the process blank obtained during casting is not equal to the theoretical size. This is because, firstly, the molten metal shrinks after solidification, resulting in a smaller volume of the casting compared to the theoretical value; secondly, after the high-temperature molten iron is poured into the resin sand mold, the heat strength of the mold wall decreases, and the cavity expands outward under the static pressure of the molten metal, leading to an increase in the actual weight of the casting compared to the theoretical weight. This introduces the volume shrinkage rate ε. v , resin sand expansion rate f v The above two factors represent the effects mentioned above, indicating that the actual dimensions of the process blank are affected by these two factors.

[0071] Compared with existing technologies, this invention obtains ε through a standardized method. v f v This technology enables the extraction of measured volume, allowing for precise calculation of molten iron quality with a single click, achieving "one-click precise casting." Data from the 3D model to the total molten iron volume is sourced uniformly, eliminating empirical coefficients and the differences in manual coefficient selection. This results in improved process design efficiency and reduced steel consumption; residual molten steel is ≤4%, preferably below 3%, with a yield of over 50%, saving 0.7t to 5.6t of molten steel per piece, and simultaneously increasing material utilization by 3 to 10 percentage points, achieving cost reduction, energy saving, and zero trial casting.

[0072] Specifically, step S1 includes:

[0073] S101. Importing Engineering Drawings:

[0074] Import the 2D engineering drawing or CAD outline of the part into the 3D design software as the modeling benchmark.

[0075] S102, Parametric Modeling:

[0076] Driven by the dimensions of the engineering drawings, and combined with the casting material and structural features, a parametric three-dimensional solid including wall thickness, length and local transition fillets is established;

[0077] S103, Model Validation:

[0078] Check wall thickness, dimensions and engineering Figure 1 Consistency was verified, confirming that the model could be used for subsequent matching of shrinkage rate and expansion rate parameters, and the three-dimensional solid output of the casting was completed.

[0079] Specifically, step S2 includes: measuring the wall thickness and length of the casting on the three-dimensional model and determining the machining allowance level.

[0080] Specifically, step S2 includes:

[0081] S201: First measure the maximum nominal size of the casting, and classify it according to the size range;

[0082] S202: Determine the machining allowance level and specific machining allowance based on the forming method and deformation risk.

[0083] During implementation, as shown in Table 1 below: First, measure the maximum nominal size of the casting and classify it into multiple grades according to size range, such as 1000mm-1600mm, 1600mm-2500mm, 2500mm-4000mm, 4000mm-6300mm and 6300mm-10000mm; For resin sand hand molding, large, complex or easily deformable parts → directly select J (maximum allowance); For simple structure and rigid parts of the same specification, it can be reduced to H or G.

[0084] Table 1 Machining Allowance Grades for Castings (RMAG, unit: mm)

[0085]

[0086]

[0087] Specifically, step S3 includes:

[0088] S301: Arrange the straight runner, horizontal runner, and inner runner on the blank according to the single or multiple package, bottom injection / top injection scheme to obtain the casting pipeline model;

[0089] S302: Determine the feeding position corresponding to the process blank model according to the modular method or the hot spot circle method, call the standard riser series, automatically generate the light and dark riser entities, and obtain the riser model;

[0090] S303: Software Boolean operations merge the blank, gating system, and riser into a closed volume package, confirming no interference or gaps, and forming an overall three-dimensional process model of the process blank model, gating system, and riser model.

[0091] Compared with existing technologies, this invention designs the casting pipeline model and riser model based on the process blank model, which enables the riser to be optimized according to the actual shrinkage amount, reduces the riser weight by 5-15%, and reduces the amount of subsequent cutting and welding repair work.

[0092] Specifically, step S4 includes: selecting the model to be tested and obtaining the volume of the model to be tested by measuring the volume segment under the quality attribute of the 3D software.

[0093] Specifically, step S5 includes:

[0094] S501: Obtain the corresponding volumetric shrinkage rate ε in molten steel based on the element content in the molten steel. v ;

[0095] S502: Retrieve the actual resin sand expansion rate table based on the casting weight range, and read f. v .

[0096] Specifically, step S502 includes:

[0097] S5021: Calculate the weight (G) of the casting by weighing or volume × density. c ;

[0098] S5022: Based on weight G c Preliminary classification of expansion rate based on molding sand type;

[0099] S5023: Further refine the initial graded expansion rate of resin sand based on the measured expansion rate data of resin sand.

[0100] During implementation, the measured data of the resin sand expansion rate of this invention are shown in Table 2:

[0101] Table 2. Measured Increase Rate of Casting Weight Due to Expansion

[0102] <![CDATA[Calculated weight G of the casting C / t]]> Handmade 10-20 2.0 20-50 1.5 50-100 1.0 ﹥100 0.8

[0103] It should be noted that the existing technology for measuring the increase in box weight based on silica sand differs significantly from the measured increase in box weight based on resin sand in this invention.

[0104] Table 3 Casting Handbook: Casting Expansion Weight Increase Rate

[0105]

[0106] Compared with the prior art, the present invention uses the measured expansion rate of resin sand, which avoids the problem of excessive difference between the expansion rates of silica sand and resin sand, reduces the deviation of the expansion rate of the upper casting, improves the calculation accuracy, and avoids the problems of excessive deviation and excessive liquid weight caused by the prior art using general manual values ​​and silica sand expansion rates for expansion rate.

[0107] It should also be noted that for large and complex cast steel parts with a maximum outline dimension ≥1000mm and a multi-directional wall thickness difference >40mm or with variable cross-sections, it is difficult to obtain the volume shrinkage rate from the linear shrinkage rate; this invention obtains the volume shrinkage rate ε based on the element content in the liquid. v .

[0108] Specifically, the shrinkage rate εv of cast steel parts is related to the carbon content and pouring temperature, as well as the alloying elements and their contents.

[0109] Step S501 includes:

[0110] S5011: Preliminary determination of the shrinkage rate ε of the corresponding cast steel part based on the carbon content in the molten steel. v ;

[0111] S5012: ε is determined based on the content of W, Ni, Mn, Cr, Si, and Al in the molten steel. v The final body contraction rate ε is obtained by correction. v .

[0112] During implementation, the pouring temperature range for most cast steel parts is 1540-1580℃. The effect of carbon content on the shrinkage rate of cast steel parts at 1560℃ is determined according to Table 4 below:

[0113] Table 4. Carbon Content Corresponding Shrinkage Rate of Cast Steel Parts at 1560℃

[0114] W(C)% 0.0 0.1 0.2 0.4 0.8 1.0 1.5 <![CDATA[ε v %]]> 1.75 3.3 4.2 5.1 6.25 6.5 7

[0115] The effect of alloying elements on the shrinkage rate of cast steel is shown in Table 5 below:

[0116] Table 5. Effects of alloying elements on the shrinkage rate of cast steel bodies

[0117] Alloy elements W Ni Mn Cr Si Al Body shrinkage coefficient / % -0.53 -0.0354 0.0585 0.12 1.03 1.7

[0118] Compared with the prior art, the present invention confirms the shrinkage rate of complex parts by determining the element content in molten steel, thereby achieving accurate determination of the shrinkage rate of complex parts and improving the shortcomings of the prior art in accurately evaluating the shrinkage rate of complex parts.

[0119] Specifically, step S6 includes:

[0120] S601: ε obtained based on step S5 v f v Calculate the correction factor k = (1 + f v ) / (1+ε v );

[0121] S602: Perform volume correction on the process blank model based on the correction coefficient k. The corrected process blank model V1 satisfies:

[0122] V1 = V0 × k, where V0 is the volume of the process blank model.

[0123] Specifically, step S7 includes: detecting and correcting the density of the molten steel raw material at the casting temperature; the detection and correction can be performed using the weighing-volume method (Archimedes' method).

[0124] As an example, the corrected liquid densities of several types of steel at 1500℃ according to the present invention are shown in Table 6 below:

[0125] Table 6 Common Chemical Compositions and Liquid Density ρ of Commonly Used Castings L calculate

[0126]

[0127] Specifically, the total mass of molten steel required for casting, G L ,satisfy:

[0128]

[0129] Where, ρ L ρ is the density of molten steel. g solid state

[0130] steel density, ε v f is the body shrinkage rate. v V represents the expansion rate of the resin sand chamber. v V is the volume of the process blank model. A V is the volume of the casting pipe model. R This represents the volume of the riser model.

[0131] The following embodiments are provided to better illustrate the present invention:

[0132] Example 1

[0133] This embodiment discloses a method for calculating the weight of resin sand gravity casting liquid in complex structure castings, used for preparation... Figure 1 The blade shown measures 4870×3300×1060mm, weighs 22.0 tons, and is made of ZG04Cr13Ni5Mo material, including:

[0134] S1: Create a 3D model of the finished casting part;

[0135] S101. Importing Engineering Drawings:

[0136] Import the 2D engineering drawing or CAD outline of the part into the 3D design software as the modeling benchmark.

[0137] S102, Parametric Modeling:

[0138] Driven by the dimensions of the engineering drawings, and combined with the casting material and structural features, a parametric three-dimensional solid including wall thickness, length and local transition fillets is established;

[0139] S103, Model Validation:

[0140] Check wall thickness, dimensions and engineering Figure 1 Consistency was verified, confirming that the model could be used for subsequent matching of shrinkage rate and expansion rate parameters, and the three-dimensional solid output of the casting was completed.

[0141] S2: Determine the machining allowance level based on the wall thickness and length of the casting in the finished part's 3D model, and adjust the finished part's 3D model based on the machining allowance level to obtain the process blank model;

[0142] S201: First measure the maximum nominal size of the casting, and classify it according to the size range;

[0143] S202: Determine the machining allowance level and specific machining allowance based on the forming method and deformation risk. Add 4mm compensation to sharp corners, 40mm machining allowance to both sides, and 20mm machining allowance to other machined surfaces. Because the blade structure is prone to deformation, a gradual process compensation of 0-17mm is set on the pressure side of the blade.

[0144] S3: Design the gating piping model and riser model based on the process blank model;

[0145] S301: Arrange the sprue, gating runner, and ingate on the adjusted blank according to single or multiple packages and bottom / top injection schemes to obtain the gating pipe model; the total volume VA of the gating system is 2.622 × 10⁻⁶. 8 mm 3 ;

[0146] S302: Determine the feeding position corresponding to the process blank model based on the modular method or the hot spot circle method, call the standard riser series, automatically generate the visible and hidden riser entities, and obtain the riser model; such as Figure 1 As shown, red represents the riser and yellow represents the casting. This blade casting is designed with one riser, with dimensions of [missing information]. (Pouring height) mm; Riser volume V R 2.428×10 9 mm3.

[0147] S303: Software Boolean operations merge the blank, gating system, and riser into a closed volume package, confirming no interference or gaps, and forming an overall three-dimensional process model of the process blank model, gating system, and riser model.

[0148] S4: Obtain the volume of the process blank model, the volume of the gating pipeline, and the volume of the riser based on 3D design software;

[0149] S5: Select a reasonable shrinkage rate ε based on the element content in the raw molten steel. v The expansion rate f of the resin sand chamber was obtained based on measured data. v ;

[0150] S501: Obtain the corresponding volumetric shrinkage rate ε in molten steel based on the element content in the molten steel. v ;

[0151] S5011: Preliminary determination of the shrinkage rate ε of the corresponding cast steel part based on the carbon content in the molten steel. v ;

[0152] S5012: ε is determined based on the content of W, Ni, Mn, Cr, Si, and Al in the molten steel. v The final body contraction rate ε is obtained by correction. v ; Refer to Tables 4 and 5 to find ε v =5%;

[0153] S502: Retrieve the actual resin sand expansion rate table based on the casting weight range, and read f. v ;

[0154] S5021: Calculate the weight (G) of the casting by weighing or volume × density. c ;

[0155] S5022: Based on weight G c Preliminary classification of expansion rate based on molding sand type;

[0156] S5023: Further refine the initial graded expansion rate of resin sand based on the measured expansion rate data of resin sand.

[0157] S6: Based on body shrinkage rate ε v , resin sand expansion rate f v Correct the volume of the process blank model;

[0158] S601: ε obtained based on step S5 v f v Calculate the correction factor k = (1 + f v ) / (1+ε v );

[0159] S402: Perform volume correction on the process blank model based on the correction coefficient k. The volume V1 of the corrected process blank model satisfies:

[0160] V1 = V0 × k. The volume of the casting, V0, is 3.771 × 10⁻⁶. 9 mm3.

[0161] Query Table 2 to determine f v The value is 1.5, and the body shrinkage rate is 5.0%.

[0162] S7: Calculate the required molten iron mass for casting based on the adjusted process blank model volume, gating pipe volume, and riser volume; check and correct the density of the casting raw material molten steel at the casting temperature; the check and correction can be performed using the weighing-volume method (Archimedes' method).

[0163] Total mass of molten steel required for casting (G) L ,satisfy:

[0164]

[0165] Where, ρ L The liquid density is 7025 kg / m³ (from Table 6). 3 , ε v f is the body shrinkage rate. v V represents the expansion rate of the resin sand chamber. v V is the volume of the process blank model. A V is the volume of the casting pipe model. R Let G be the volume of the riser model; calculated G L =49822kg, rounded liquid weight 50t, gross weight 29.5t, casting yield 59%, material utilization rate 44%; the actual amount of molten steel poured from the ladle was 52t, and 4.3t remained after pouring. The calculated liquid weight was 2.1t more than the actual required weight, accounting for 4.2% of the total liquid weight.

[0166] Calculation of molten steel using existing typical methods:

[0167] G 总 =G 铸件 +G 浇注管路 +G 冒口 G 铸件 =G V ×(1+f V ), f V Refer to Table 3 and get 5.0;

[0168] G 浇注系统 =G 铸件 ×k1 (k1 = 0.15);

[0169] G 冒口 =G 铸件 ×k2 (k2=0.15); density of molten steel 7.830kg / m3

[0170] Calculations show that existing technologies require approximately 50.7 tons of molten steel, while this embodiment saves 0.7 tons of molten steel compared to traditional methods; the material utilization rate is increased from 44% to 47%.

[0171] Example 2

[0172] This embodiment discloses a method for calculating the liquid weight of resin sand gravity casting for complex structural castings, used to prepare a fore-stern shaft support with dimensions of 3900×1782×1700mm, a net weight of 11.9 tons, and material CZ370A. A 3D model was created, a detailed drawing of the fore-stern shaft support was drawn, and casting process parameters were determined. Machining allowances of 25mm and 15mm were added to the end face and side face of the bearing plate, respectively; an internal allowance was added to the shaft hole; and a machining allowance of 26mm was added to both end faces. Due to the complex structure of the aft shaft support, a grinding allowance of 10mm was added to all non-machined surfaces. The linear shrinkage rate of the fore-stern shaft support is 1.8%. A blank drawing of the fore-stern shaft support was drawn based on the above casting process parameters, as shown below. Figure 2 As shown, the casting process is designed as follows:

[0173] In the design, red represents risers, yellow represents castings, and blue represents chills. This stern shaft support casting has two risers: one open riser and one concealed riser. One riser is a waist-shaped open riser with a center distance of 300mm and dimensions of 1400*550*850 (pouring height) mm. The other riser is a concealed riser with dimensions of 1310*1100*800 mm. This fore-stern shaft support is cast using a single-ladle system, with separate sprues and runners. Ceramic tile pipes, with four internal gating channels. The sprue is 2.7m long, the runner is 8.8m long, and the ingate is 2.6m long. The total volume of the pouring piping is V. A 1.252×10 8 mm 3 After the process design is completed, the volume V of the casting is measured. v 2.238×10 9 mm3; riser volume V R 1.38×10 9 mm3, liquid density is 7226 kg / m3 (from Table 6). f is determined from Table 2. v The value is 2.0. The liquid weight is calculated using the following formula, and the rest is the same as in Example 1:

[0174]

[0175] The solidified liquid weighed 35t, the gross weight was 17.5t, the casting yield was 50%, and the material utilization rate was 34%.

[0176] The overall plan is to pour 35t of molten steel in a single ladle. To ensure clean filling, external drainage is adopted and no slag is introduced at the end of the pouring. The actual steel output from the ladle is 39t, and 5.5t remains after pouring. The calculated liquid weight exceeds the actual required weight by 1.3t, accounting for 3.7% of the total liquid weight.

[0177] Calculation of molten steel using existing typical methods:

[0178] G 总 =G 铸件+G 浇注管路 +G 冒口 G 铸件 =G V ×(1+f V ), f V Refer to Table 3 and get 6.0;

[0179] G 浇注系统 =G 铸件 ×k1 (k1 = 0.15);

[0180] G 冒口 =G 铸件 ×k2 (k2=0.15); density of molten steel 7.830kg / m3

[0181] Calculations show that existing technologies require approximately 35.8 tons of molten steel, while this embodiment saves 0.8 tons of molten steel compared to traditional methods; the material utilization rate is increased from 30% to 34%.

[0182] Example 3

[0183] This embodiment discloses a method for calculating the liquid weight of resin sand gravity casting for complex structural castings, used to prepare a stern shaft support with dimensions of 7500×7100×4000mm, a net weight of 67.5 tons, and material CZ370A. A 3D model was created, a detailed drawing of the stern shaft support was drawn, and casting process parameters were determined. A 25mm machining allowance was added to the palm plate, a 40mm machining allowance was added to one side of the shaft hole, a 30mm machining allowance was added to the shaft hub end face, and a 30mm machining allowance was added to the top surface. Due to the excessive length of the stern shaft support, it is prone to deformation, and a 10mm grinding allowance was added to all non-machined surfaces. The linear shrinkage rate in the length direction of the long arm and broken arm of the stern shaft support is 1.8%, the linear shrinkage rate between the palm plates is 0.5%, the linear shrinkage rate in the height direction of the palm plates is 1.6%, the linear shrinkage rate of the outer diameter of the shaft hub is 2.0%, and the linear shrinkage rate in the height direction of the shaft hub is 2.4%. Based on the above casting process parameters, a blank drawing of the stern shaft support was drawn, as shown below. Figure 3 As shown, the casting process is designed as follows:

[0184] The red areas represent risers, and the gray areas represent castings. This stern shaft support casting is designed with 5 risers: 2 exposed risers and 3 concealed risers. The two exposed risers are waist-shaped, with center distances of 375mm and 790mm respectively, and dimensions of 1245*870*1200 (pouring height) mm and 1740*950*1200 (pouring height) mm respectively. The two concealed risers have dimensions of 1200*800*1000 (pouring height) mm and 1000*800*1000 (pouring height) mm respectively. The last riser is a waist-shaped concealed riser with a center distance of 560mm and dimensions of 1560*1000*1400 (pouring height) mm. This stern shaft support uses a 2-bundle, 4-hole combined casting method, with both the sprue and runner employing [missing information - likely a specific design element]. Ceramic tile pipes, with 19 internal gating channels. The sprue is 17.6m long, the gating runner is 22.8m long, and the ingate is 11.4m long. The total volume of the pouring piping is V. A It is 7.11×10 8 mm3, after the process design is completed, the casting volume V is measured. v 1.067×10 10 mm3; riser volume V R It is 7.74×10 9 mm3, liquid density is taken as 7226 kg / m³ from Table 6. 3 Query Table 2 to determine f v ε is 1.0 v The value is 3.6%. The liquid weight is calculated using the following formula, and the rest is the same as in Example 1:

[0185]

[0186] The solidified liquid weighed 143t, the gross weight was 83.5t, the casting yield was 58.3%, and the material utilization rate was 47.2%.

[0187] The overall plan involved pouring 143 tons of molten steel in two ladles, each containing 71.5 tons. To ensure clean filling, external drainage was used, and no slag was introduced at the end of the pouring process. The actual steel output from the two ladles was 75.5 tons and 77 tons, respectively. After pouring, 6.3 tons and 5.7 tons of molten steel remained in the two ladles, totaling 12 tons. The calculated liquid weight exceeded the actual required weight by 2.5 tons, accounting for 1.6% of the total liquid weight.

[0188] Calculation of molten steel using existing typical methods:

[0189] G 总 =G 铸件 +G 浇注管路 +G 冒口 G 铸件 =G V ×(1+f V ), f V Refer to Table 3 and get 4.0;

[0190] G 浇注系统 =G 铸件 ×k1 (k1 = 0.15);

[0191] G 冒口 =G 铸件 ×k2 (k2=0.15); density of molten steel 7.830kg / m3

[0192] Calculations show that existing technologies require approximately 148.6 tons of molten steel, while this embodiment saves 5.6 tons of molten steel compared to traditional methods; the material utilization rate is increased from 47.2% to 50%.

[0193] Example 4

[0194] This embodiment discloses a method for calculating the liquid weight of resin sand gravity casting for complex structure castings. The method is used to prepare a rotor with dimensions of 4558×4558×955mm, a net weight of 17.1 tons, and material ZG04Cr13Ni5Mo. A 3D model was created, a detailed drawing of the integrated rotor was drawn, and casting process parameters were determined. A 30mm machining allowance was added to the inner cavity, a 26mm machining allowance to the upper surface, and a 20mm machining allowance to the blade surface. Due to the complex structure and easy deformation of this integrated rotor, a 22mm machining allowance was added to other parts. The shrinkage rate of the integrated rotor in all directions is 1.8%. Figure 4 As shown, the casting process is designed as follows:

[0195] The red areas represent risers, and the orange areas represent castings. This integrated turbine casting features six risers. Riser No. 1 is an annular open riser with a diameter of 2250mm, a pouring height of 700mm, and a riser fillet radius of R50. Riser No. 2 is a waist-shaped concealed riser with a center distance of 790mm, a pouring height of 550mm, and a riser fillet radius of R150. The machine uses a single-bundle, double-hole combined casting system, with both the sprue and runner employing [missing information - likely referring to a specific design or process]. Ceramic tile pipes, with 18 internal gating channels. The straight runner is 12m long, the horizontal runner is 20m long, and the ingate is 10m long. The total volume of the pouring piping is V. A It is 5.209×10 8 mm 3 After the process design is completed, the volume V of the casting is measured. v 3.824×10 9 mm3; riser volume V R It is 3.41×10 9 mm3, liquid density is 7226 kg / m3 (from Table 6). f is determined from Table 2. v The value is 2.0. The liquid weight is calculated using the following formula, and the rest is the same as in Example 1:

[0196]

[0197] The solidified liquid weighed 57t, the gross weight was 29.9t, the casting yield was 52.5%, and the material utilization rate was 30.0%.

[0198] In actual production, single-ladle casting is used. To ensure that no slag enters at the end of casting, the actual steel output of the ladle is 60.9t. After casting, there is 5.5t of molten steel remaining. The calculated liquid weight exceeds the actual required weight by 1.6t, accounting for 2.8% of the total liquid weight of the casting.

[0199] Calculation of molten steel using existing typical methods:

[0200] G 总 =G 铸件 +G浇注管路 +G 冒口 G 铸件 =G V ×(1+f V ), f V Refer to Table 3 and get 6.0;

[0201] G 浇注系统 =G 铸件 ×k1 (k1 = 0.15);

[0202] G 冒口 =G 铸件 ×k2 (k2=0.15); density of molten steel 7.830kg / m3

[0203] Calculations show that existing technologies require approximately 60.5 tons of molten steel, while this embodiment saves 3.5 tons of molten steel compared to traditional methods; the material utilization rate is increased from 48.2% to 52.5%.

[0204] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for calculating the weight of resin sand gravity casting liquid in complex structure castings, characterized in that, include: S1: Create a 3D model of the finished casting part; S2: Determine the machining allowance level based on the nominal dimensions of the finished part's 3D model, and adjust the finished part's 3D model based on the machining allowance level to obtain the process blank model; S3: Design the gating piping model and riser model based on the process blank model; S4: Obtain the volume of the process blank model, the volume of the gating pipeline, and the volume of the riser based on 3D design software; S5: Select a reasonable shrinkage rate ε based on the element content in the raw molten steel. v The expansion rate f of the resin sand chamber was obtained based on measured data. v ; S6: Based on body shrinkage rate ε v , resin sand expansion rate f v Correct the volume of the process blank model; S7: Calculate the required molten iron mass for pouring based on the corrected process blank model volume, pouring pipe volume, and riser volume.

2. The method for calculating the weight of resin sand gravity casting liquid for complex structure castings according to claim 1, characterized in that, Step S1 includes: S101. Importing Engineering Drawings: Import the 2D engineering drawing or CAD outline of the part into the 3D design software as the modeling reference; S102, Parametric Modeling: Driven by the dimensions of the engineering drawings, and combined with the casting material and structural features, a parametric three-dimensional solid including wall thickness, length and local transition fillets is established; S103, Model Validation: Check the wall thickness and dimensions to ensure consistency with the engineering drawings, confirm that the model can be used for subsequent matching of shrinkage rate and expansion rate parameters, and complete the output of the three-dimensional solid casting.

3. The method for calculating the weight of resin sand gravity casting liquid for complex structure castings according to claim 1, characterized in that, Step S2 includes: measuring the wall thickness and length of the casting on the three-dimensional model and determining the machining allowance level.

4. The method for calculating the weight of resin sand gravity casting liquid for complex structure castings according to claim 3, characterized in that, Step S2 includes: S201: First measure the maximum nominal size of the casting, and classify it according to the size range; S202: Determine the machining allowance level and specific machining allowance based on the forming method and deformation risk.

5. The method for calculating the weight of resin sand gravity casting liquid for complex structure castings according to claim 1, characterized in that, Step S3 includes: S301: Arrange the straight runner, horizontal runner, and inner runner on the blank according to the single or multiple package, bottom injection / top injection scheme to obtain the casting pipeline model; S302: Determine the feeding position corresponding to the process blank model according to the modular method or the hot spot circle method, call the standard riser series, automatically generate the light and dark riser entities, and obtain the riser model; S303: Software Boolean operations merge the blank, gating system, and riser into a closed volume package, confirming no interference or gaps, and forming an overall three-dimensional process model of the process blank model, gating system, and riser model.

6. The method for calculating the weight of resin sand gravity casting liquid for complex structure castings according to claim 1, characterized in that, Step S4 includes: selecting the model to be inspected and obtaining the volume of the model to be inspected by measuring the volume segment under the quality attribute of the 3D software.

7. The method for calculating the weight of resin sand gravity casting liquid for complex structure castings according to claim 1, characterized in that, Step S5 includes: S501: Obtain the corresponding volumetric shrinkage rate ε in molten steel based on the element content in the molten steel. v ; S502: Retrieve the actual resin sand expansion rate table based on the casting weight range, and read f. v .

8. The method for calculating the weight of resin sand gravity casting liquid for complex structure castings according to claim 7, characterized in that, Step S502 includes: S5021: Calculate the weight (G) of the casting by weighing or volume × density. c ; S5022: Based on weight G c Preliminary classification of expansion rate based on molding sand type; S5023: Further refine the initial graded expansion rate of resin sand based on the measured expansion rate data of resin sand.

9. The method for calculating the weight of resin sand gravity casting liquid for complex structure castings according to claim 7, characterized in that, Step S501 includes: S5011: Preliminary determination of the shrinkage rate ε of the corresponding cast steel part based on the carbon content in the molten steel. v ; S5012: ε is determined based on the content of W, Ni, Mn, Cr, Si, and Al in the molten steel. v The final volume shrinkage rate ε is obtained by correction. v .

10. The method for calculating the weight of resin sand gravity casting liquid for complex structure castings according to any one of claims 1-9, characterized in that, Step S6 includes: S601: ε obtained based on step S5 v f v Calculate the correction factor k = (1 + f v ) / (1+ε v ); S602: Perform volume correction on the process blank model based on the correction coefficient k. The corrected process blank model V1 satisfies: V1 = V0 × k, where V0 is the volume of the process blank model.

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