A method for preparing sand molds with performance differentiation

Abstract

The present invention discloses a method for preparing a sand mold with performance differentiation, belonging to the technical field of additive manufacturing. The method includes establishing a first sand mold model; s first yield stresses are distributed in the first sand mold; the s first yield stresses form a first yield stress distribution data set of the first sand mold model; the first sand mold is divided into n preset modules according to the first yield stress distribution data set; among the n preset modules, at least one preset module is distributed with f second yield stresses; the number of target modules formed into the target sand mold is obtained according to the number of preset modules; a single target module is formed according to a single preset module; according to the second yield stresses between the n preset modules, the target addition amount of the single-layer binder required for each of the n target modules is obtained and the number of die pieces cut from each of the n preset modules is obtained; the target sand mold is formed according to the n target modules. The sand mold forming invention of the present invention meets the different performance requirements of the sand mold and reduces the binder consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing, and more particularly to a method for preparing a sand mold with performance differentiation. Background Art

[0002] The emergence of 3D printing technology has certain advantages in additive manufacturing. At present, the application of 3D technology in the field of sand casting has a very good application prospect. First of all, molding and core making are considered to be one of the links with high labor intensity and poor production environment in the casting industry. The application of 3D technology in the production of sand molds replaces the manual operation link. Due to the particularity of the raw materials of 3D printed sand molds, there will be no dust flying phenomenon during the printing process, and the binder added for sand mold hardening is also carried out in a relatively closed box, reducing environmental emissions and greatly improving the working environment. Secondly, the application of 3D printing technology in the field of sand casting omits the link of making molds, not only saving production costs, but also improving the speed and flexibility of product trial production. Foundry enterprises no longer need to spend a large amount of money to build a mold storage workshop and professional mold maintenance personnel. Thirdly, the application of 3D printing technology in sand casting greatly improves the dimensional accuracy of products and enhances the control ability of sand mold dimensions, becoming a precisely controlled link. 3D printing simplifies complex product sand molds, and the precise dimensional control system can finely control the processing amount of products, ensuring that a small amount of machining allowance can be left when the product machining surface is designed, improving the efficiency of subsequent product processing. Finally, the application of 3D printing technology in the field of sand casting provides sufficient guarantee for the flexibility of product design. Since 3D printed sand molds are not restricted by the size and shape of products, parameters can be changed at any time during the product production process for local or overall correction, improving the efficiency of product R & D verification.

[0003] At present, the 3D printing of casting sand molds adopts the method of completely solid printing the sand molds. The casting sand molds produced by this method generally have the following problems:

[0004] (1) Since there is no compaction method, the strength can only be increased by adding a binder. The large amount of binder added leads to a large amount of gas evolution in the sand mold.

[0005] (2) The 3D printed sand mold has poor air permeability and is prone to defects such as pores and inclusions.

[0006] (3) For large sand molds, a large amount of binder is used and a long drying time is required, resulting in high usage costs.

[0007] (4) The performance of 3D printed sand molds is consistent and cannot meet the different requirements for sand mold performance put forward by different structures and positions of castings. Summary of the Invention

[0008] To solve the problem that the existing sand mold forming method cannot meet the different performance requirements of different parts of the sand mold, and to address the issue of how to reduce the amount of binder used, the present invention provides a method for preparing a sand mold with performance differentiation, which includes:

[0009] Establish a first sand mold model;

[0010] The first sand mold is distributed with s first yield stresses, and at least one of the s first yield stresses is inconsistent, where s is a natural number and s≥1;

[0011] Form a first yield stress distribution data set of the first sand mold model with the s first yield stresses;

[0012] Divide the first sand mold into n preset modules according to the first yield stress distribution data set, and at least one of the n preset modules has a first yield stress, where n is a natural number and 1≤n≤s;

[0013] Among the n preset modules, at least one of the preset modules is distributed with f second yield stresses, the second yield stresses are within the range of the first yield stress, and at least one of the f second yield stresses is inconsistent, where f is a natural number and f≥1;

[0014] Obtain the number of target modules for forming the target sand mold according to the number of the preset modules, and the number of the preset modules is the same as the number of the target modules;

[0015] Form a single target module according to a single preset module, and the method for forming a single target module includes:

[0016] Obtain target casting sand materials according to at least one of the second yield stresses in a single preset module;

[0017] Obtain the target yield strength of the target module according to the maximum second yield stress among the second yield stresses of a single preset module and the first yield strength of the target casting sand materials;

[0018] Cut a single preset module into m die pieces according to the distribution of the second yield stresses of the single preset module, where m is a natural number and m≥1;

[0019] Obtain the target addition amount of single-layer binder required for forming the target module with the m die pieces according to the target yield strength;

[0020] Form a single target module by adding the target casting sand materials layer by layer and adding the target addition amount of single-layer binder layer by layer;

[0021] According to whether the second yield stress among the n preset modules is consistent or not, obtain whether the target addition amounts of the single-layer binder required for the n target modules are consistent or not, and obtain whether the numbers of the die pieces cut from the n preset modules are consistent or not;

[0022] Form the target sand mold from the n target modules.

[0023] According to an embodiment of the present invention, among the m die pieces, obtain the thickness of a single die piece according to the third yield stress of the single die piece and the first yield strength of the target casting sand material, and the third yield stress is within the range of the second yield stress.

[0024] According to an embodiment of the present invention, the first yield stress distribution data set includes a first yield stress I, a first yield stress II, and a first yield stress III, and the first yield stress I ≤ the first yield stress II ≤ the first yield stress III. Divide the first sand mold into a first preset module, a second preset module, and a third preset module according to the first yield stress I, the first yield stress II, and the first yield stress III.

[0025] According to an embodiment of the present invention, the first yield stress I is 0 - 400 Mpa, the first yield stress II is 400 - 800 Mpa, and the first yield stress III is 800 - 1200 Mpa.

[0026] According to an embodiment of the present invention, obtain the target yield strength of the target module according to the maximum second yield stress of the preset module, the first yield strength of the target casting sand material, and the standard yield strength of the sand mold.

[0027] According to an embodiment of the present invention, the calculation formula for the target yield strength of the target module is as follows:

[0028] ;

[0029] wherein, X is the target yield strength of the target module, σ m is the maximum second yield stress within the preset module, σ Q is the yield strength of the target casting sand material, and Q s is the standard yield strength of the sand mold.

[0030] According to an embodiment of the present invention, obtain the target addition amount of the single-layer binder required for forming the m die pieces into the target module according to the target yield strength of the target module, the yield strength of the target casting sand material, and the standard addition amount of the single-layer binder of the sand mold.

[0031] According to an embodiment of the present invention, the calculation formula for the target addition amount of the single-layer binder required by the preset module is as follows:

[0032] ;

[0033] where Y is the target addition amount of the single-layer binder required by the preset module, X is the target yield strength of the target module, Q s is the standard yield strength of the sand mold, K is a constant, K = 1.32 - 1.58, and P s is the standard addition amount of the single-layer binder of the sand mold.

[0034] According to an embodiment of the present invention, the target addition amount of the single-layer binder is the addition amount of the binder between two adjacent layers of the m wafers, and the target addition amount of the single-layer binder required for forming a single target module is the same.

[0035] According to an embodiment of the present invention, according to whether the second yield stress between the n preset modules is the same or different, the target addition amounts of the single-layer binder required for the n target modules are the same, and the number of wafers cut from the n preset modules is the same or different.

[0036] The present invention has the following beneficial effects:

[0037] 1. In the present invention, during the 3D printing and forming process of the target sand mold, based on the forming stress of the overall structure characteristics of the first sand mold of the model, different stress distribution areas are divided into preset modules, and different target yield strengths required for different target modules are designed; according to the specific yield strength requirements of each target module, the addition amount of each layer of binder required for different target modules is designed; by adding sand layer by layer and spraying the budgeted amount of binder layer by layer, the 3D printing of the target sand mold with overall differentiated performance is realized, meeting the requirements of each structural feature, improving the quality of the sand mold, and on the basis of meeting the performance requirements of the sand mold, a method of using less single-layer binder is selected to reduce the use of binder, save costs, and be environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Shows a flowchart of a method for preparing a sand mold with performance differentiation according to the present invention. DETAILED DESCRIPTION

[0039] Now the content of the present disclosure will be discussed with reference to several exemplary embodiments. It should be understood that these embodiments are discussed only to enable those of ordinary skill in the art to better understand and thus implement the content of the present disclosure, rather than implying any limitation on the scope of the present disclosure.

[0040] As used herein, the term "comprising" and its variants are to be construed as open-ended terms meaning "including but not limited to". The term "based on" is to be construed as "at least partially based on". The terms "an embodiment" and "a kind of embodiment" are to be construed as "at least one embodiment". The term "another embodiment" is to be construed as "at least one other embodiment". The terms "first", "second", etc. are mainly used to distinguish different devices, elements or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance and quantity of the indicated devices, elements or components.

[0041] This embodiment discloses a method for preparing a sand mold with performance differentiation. As Figure 1 shown, it includes the following steps:

[0042] Establish a first sand mold model;

[0043] There are s first yield stresses distributed in the first sand mold, and at least one of the s first yield stresses is inconsistent, where s is a natural number and s≥1;

[0044] Form a first yield stress distribution data set of the first sand mold model with the s first yield stresses;

[0045] Divide the first sand mold into n preset modules according to the first yield stress distribution data set, and at least one of the n preset modules has a first yield stress, where n is a natural number and 1≤n≤s;

[0046] Among the n preset modules, at least one of the preset modules is distributed with f second yield stresses, the second yield stresses are within the range of the first yield stress, and at least one of the f second yield stresses is inconsistent, where f is a natural number and f≥1;

[0047] Obtain the number of target modules formed into the target sand mold according to the number of the preset modules, and the number of the preset modules is the same as the number of the target modules;

[0048] Form a single target module according to a single preset module. The method for forming a single target module includes:

[0049] Obtain target casting sand materials according to at least one of the second yield stresses in a single preset module;

[0050] Obtain the target yield strength of the target module according to the maximum second yield stress among the second yield stresses of a single preset module and the first yield strength of the target casting sand materials;

[0051] Cut a single said preset module into m die pieces according to the second yield stress distribution of the single said preset module, where m is a natural number and m≥1;

[0052] Obtain the target addition amount of the single-layer binder required for forming the m die pieces into the target module according to the target yield strength;

[0053] Form a single said target module by successively adding the target casting sand material layer by layer and successively adding the target addition amount of the single-layer binder;

[0054] According to whether the second yield stresses between the n said preset modules are the same or different, obtain whether the target addition amounts of the single-layer binder required for the n said target modules are the same or different, and obtain whether the number of die pieces cut from the n said preset modules are the same or different;

[0055] Form the target sand mold from the n said target modules.

[0056] When performing this embodiment, establish a first sand mold model to obtain the target sand mold through the first sand mold. Use the casting simulation software Procast to simulate and calculate the forming process of the first sand mold to obtain the overall yield stress distribution of the first sand mold. Take the yield stress of the overall distribution of the first sand mold as the first yield stress. There are s first yield stresses. There may be cases where the yield stresses are the same among the s first yield stresses, but at least one first yield stress value is different from other first yield stress values. Form a first yield stress distribution data set with the first yield stresses. Divide the first sand mold into n preset modules through the first yield stress distribution data set, that is, the n preset modules form the first sand mold. There is at least one first yield stress in the n preset modules, that is, in the n preset modules, each preset module has at least one first yield stress or more, that is, a preset module may only include one first yield stress and two or more first yield stresses. In each preset module, different yield stresses are also distributed in a single preset module. Count the yield stress distributed in a single preset module as the second yield stress. A single preset module has f second yield stresses. The second yield stresses are within the range of the first yield stresses. There may also be cases where the second yield stress is equal to the first yield stress. There is at least one second yield stress in the n preset modules. There may also be cases where the yield stresses are the same in the n preset modules, but at least one second yield stress value is different from other second yield stress values. By selecting the number of target modules according to the number of preset modules, it is possible to select that the number of preset modules is the same as the number of target modules, so there are also n target modules. Then, form a single target module according to a single module. Thus, n target modules can be formed according to the n preset modules. The method for forming a single target module includes the following steps:

[0057] By selecting the target casting sand material according to at least one second yield stress in a single preset module, that is, the yield stress of the selected target casting sand material can meet the second yield stress;

[0058] By obtaining the target yield strength of the target module according to the maximum first yield stress of the single preset module and the first yield strength of the target casting sand material;

[0059] By slicing the single preset module into m die pieces according to the second yield stress of the single preset module;

[0060] By the target yield strength of the target module, the target addition amount of the single-layer binder required for forming the m die pieces into the target module is obtained, that is, the target module is formed by the m die pieces of the preset module;

[0061] Through computer discretization layering processing, the three-dimensional entity of the single target module is sliced, and the target addition amount of the single-layer binder required for the target module is formed into the data of the layer-by-layer injection amount of the binder. Using a 3DP sand mold printing device, by adding the casting sand material layer by layer and injecting the target addition amount of the single-layer binder required for the budget target module layer by layer, the required single target module is formed;

[0062] According to whether the second yield stresses between the n preset modules are consistent or not, it is obtained whether the target addition amounts of the single-layer binder required for the n target modules are consistent or not, and whether the numbers of die pieces cut from the n preset modules are consistent or not;

[0063] The target addition amounts of the single-layer binder required for the n target modules respectively are carried out according to the above method, so that the n target modules are combined to obtain a target sand mold with diverse properties;

[0064] The n target modules form a target sand mold.

[0065] In this embodiment, during the 3D printing and forming process of the target sand mold, based on the forming stress of the overall structure feature of the first sand mold of the model, the preset module division of different stress distribution regions is carried out, and the differential yield strengths required for different target modules are designed; according to the specific yield strength requirements of each target module, the addition amount of each layer of binder required for different target modules is designed; by adding sand layer by layer and injecting the budgeted amount of binder layer by layer, the 3D printing of the overall differential performance of the target sand mold is realized, meeting the requirements of each structural feature, improving the quality of the sand mold, reducing the use of binder, saving costs, and being environmentally friendly.

[0066] In this embodiment, by obtaining whether the target addition amounts of the single-layer binder required for the n target modules are the same or different according to whether the second yield stresses among the n preset modules are the same or different, it is possible to select the appropriate target addition amounts of the single-layer binder required for the target modules while meeting the performance requirements of the sand mold. And by obtaining whether the number of die pieces cut from the n preset modules is the same or different according to whether the second yield stresses among the n preset modules are the same or different, it is further possible to ensure the selection of appropriate target addition amounts of the single-layer binder by controlling the number of die pieces, so as to meet the performance requirements of different parts of the sand mold.

[0067] In some embodiments, specifically, the target addition amount of the single-layer binder is the addition amount of the binder required between two adjacent die pieces among the m die pieces. Since there is at least one target yield strength that is different among the n target modules, based on the obtaining method of the target addition amount of the single-layer binder, it is obtained that there may be at least one target addition amount of the single-layer binder required that is different among the n target modules. The target addition amounts of the single-layer binder required for the n target modules are calculated separately, and n times of obtaining the target addition amount of the single-layer binder for each target module are required for the n target modules.

[0068] In some embodiments, a single target casting sand material is selected by the yield stress range corresponding to a single preset module, that is, when the yield stress of the casting sand material belongs to the yield stress range corresponding to the preset module, the casting sand material can be used as a single target casting sand material. After ensuring that the target casting sand material is formed into a target sand mold, the yield stress of the target sand mold can reach the required yield stress.

[0069] In some embodiments, when the first sand mold model is divided into n preset modules along the horizontal direction and the n preset modules are in a state of stacking to form the first sand mold model, the amount of binder used for bonding two adjacent preset modules is the target addition amount of the single-layer binder used by the preset module with a smaller target addition amount of the single-layer binder among the two adjacent preset modules. Preferably, the target addition amount of the single-layer binder used by the preset module with a smaller target addition amount of the single-layer binder is the largest addition amount of the single-layer binder among the addition amounts of the single-layer binder used for the m die pieces in the single preset module. This can not only ensure the performance of the formed sand mold but also reduce the amount of binder used.

[0070] According to an embodiment of the present invention, among the m die pieces, the thickness of a single die piece is obtained according to the third yield stress of the single die piece and the first yield strength of the target casting sand material, and the third yield stress is within the second yield stress range.

[0071] In this embodiment, the method of obtaining the thickness of a single die based on the third yield stress of the single die and the first yield strength of the target casting sand ensures that the prepared target sand mold meets the required performance requirements.

[0072] In some embodiments, the target addition amount of the single-layer target casting sand is obtained according to the thickness of the single die, so as to facilitate the selection of an appropriate addition amount of the single-layer target casting sand, thereby ensuring the performance of the target sand mold.

[0073] In this article, the first yield stress, the second yield stress, and the third yield stress are single-point values and / or range values. Preferably, the first yield stress, the second yield stress, and the third yield stress are range values.

[0074] According to an embodiment of the present invention, the first yield stress distribution dataset includes first yield stress I, first yield stress II, and first yield stress III, where first yield stress I ≤ first yield stress II ≤ first yield stress III. According to the first yield stress I, first yield stress II, and the first yield stress III, the first sand mold is divided into a first preset module, a second preset module, and a third preset module.

[0075] In this embodiment, the yield stress of the first sand mold distribution is divided into three grades, and the first sand mold can be divided into three preset modules according to the three grades. Then, the first preset module is the first yield stress I, the second preset module is the first yield stress II, and the third preset module is the first yield stress III. By reasonably setting the yield stress grades of the preset modules, the working efficiency is improved while ensuring that the yield strength of different parts of the target sand mold is satisfied.

[0076] According to an embodiment of the present invention, the first yield stress I is 0 - 400 Mpa, the first yield stress II is 400 - 800 Mpa, and the first yield stress III is 800 - 1200 Mpa.

[0077] In this embodiment, by reasonably setting the yield stress ranges of different grades, the yield strength of different parts of the target sand mold is further satisfied, and the working rate is increased.

[0078] According to an embodiment of the present invention, the target yield strength of the target module is obtained according to the maximum second yield stress of the preset module, the first yield strength of the target casting sand, and the standard yield strength of the sand mold.

[0079] In this embodiment, a method for obtaining the target yield strength of the target module is provided to improve the accuracy of obtaining the target yield strength of the target module.

[0080] According to an embodiment of the present invention, the calculation formula for the target yield strength of the target module is as follows:

[0081] ;

[0082] Among them, X is the target yield strength of the target module, σ m is the maximum secondary yield stress within the preset module, σ Q is the yield strength of the target casting sand material, Q s is the standard yield strength of the sand mold.

[0083] In this embodiment, the target yield strength of the specific target module is obtained through the above formula. Among them, the standard yield strength of the sand mold is the strength that the mold should have as required by relevant national, industrial, group or enterprise standards for different classified castings according to the sand mold material, use, etc.

[0084] According to an embodiment of the present invention, the target addition amount of the single-layer binder required for forming the target module is obtained based on the target yield strength of the target module, the yield strength of the target casting sand material, and the standard addition amount of the single-layer binder of the sand mold.

[0085] In this embodiment, a method for obtaining the target addition amount of the single-layer binder required for the target module is provided to improve the accuracy of obtaining the target addition amount of the single-layer binder required for the target module.

[0086] According to an embodiment of the present invention, the calculation formula for the target addition amount of the single-layer binder required for the preset module is as follows:

[0087] ;

[0088] Among them, Y is the target addition amount of the single-layer binder required for the preset module, X is the target yield strength of the target module, Q s is the standard yield strength of the sand mold, K is a constant, K = 1.32 - 1.58, P s is the standard addition amount of the single-layer binder of the sand mold.

[0089] In this embodiment, the specific target addition amount of the single-layer binder required for the target module is obtained through the above formula. Specifically, K is a quantization constant for the reduction of the sand mold strength and the reduction of the binder amount. Among them, the standard addition amount of the single-layer binder of the sand mold is the binder addition amount that the mold should have as required by relevant national, industrial, group or enterprise standards for different classified castings according to the sand mold material, use, etc.

[0090] According to an embodiment of the present invention, the target addition amount of the single-layer binder is the addition amount of the binder between two adjacent layers of the m mold pieces, and the target addition amount of the single-layer binder required for forming a single target module is the same.

[0091] In this embodiment, the target addition amount of the single-layer binder required for the target module is the addition amount of the binder between two adjacent wafers among m wafers, so as to further accurately determine the target addition amount of the single-layer binder. The method of making the target addition amount of the single-layer binder required for forming a single target module consistent simplifies the preparation method and reduces the working steps while ensuring the properties of the sand mold and reducing the target addition amount of the binder.

[0092] According to an embodiment of the present invention, according to whether the second yield stress between the n preset modules is consistent or not, the target addition amount of the single-layer binder required for each of the n target modules is made consistent, and the number of wafers obtained by cutting each of the n preset modules is made consistent or not.

[0093] In this embodiment, by setting the target addition amount of the single-layer binder required for each of the n target modules to be consistent regardless of whether the second yield stress between the n preset modules is consistent or not, and then by adjusting the number of wafers obtained by cutting each of the preset modules to be consistent or not, it is ensured that the target addition amount of the single-layer binder required for each of the n target modules is consistent. Therefore, when preparing the same sand mold, compared with the prior art, the method of this embodiment reduces the target addition amount of the single-layer binder, reduces the usage requirement of the target addition amount of the single-layer binder, and reduces the production cost.

[0094] Preferably, adjusting the number of wafers is to adjust the thickness of the wafers. That is, when slicing a single preset module, according to the distribution of the second yield stress of the preset module, when slicing a single preset module, some wafers have a large thickness and some wafers have a small thickness, and there are wafers with different thicknesses among the m wafers of a single preset module, so as to reduce the usage amount of the single-layer binder while ensuring the properties of the sand mold.

[0095] In some embodiments, according to the fact that the second yield stress between the n preset modules is inconsistent, the target addition amount of the single-layer binder required for each of the n target modules is made consistent, and the number of wafers obtained by cutting each of the n preset modules is made consistent or not. In this embodiment, by adjusting the number of wafers obtained by cutting each of the n preset modules to be consistent or not, the target addition amount of the single-layer binder required for each of the n target modules is made consistent, so that the target addition amount of the single-layer binder is minimized.

[0096] In some embodiments, according to whether the second yield stress between the n preset modules is consistent or not, the target addition amount of the single-layer binder required for each of the n target modules is made consistent, and the number of wafers obtained by cutting each of the n preset modules is made consistent. It is ensured that when forming a large target sand mold, the total target addition amount of the single-layer binder used is minimized.

[0097] Embodiment 1

[0098] A method for preparing a roll-compacted near-net-shaped sand mold, including the following steps:

[0099] (1) Use the casting simulation software Procast to simulate and calculate the casting forming and solidification process, obtain the overall yield stress distribution, and divide the preset modules according to three yield stress levels: the first yield stress: 0 - 400 Mpa, the second yield stress: 400 - 800 Mpa, and the third yield stress: 800 - 1200 Mpa;

[0100] (2) According to the yield stress conditions of each preset module, within the stress preset module range where the yield strength of the casting sand material is located, use Formula 1: Calculate the required yield strength of each part of the sand mold / core, where X is the target yield strength of the target module, σ m is the maximum yield stress within the preset module, σ Q is the yield strength of the target casting sand material, Q s is the standard yield strength of the sand mold;

[0101] (3) According to the specific required yield strength requirements of each part of the sand mold / core, use Formula 2: Calculate the amount of binder added per layer required for different target modules, where Y is the target amount of binder added per layer required for the preset module, X is the target yield strength of the target module, Q s is the standard yield strength of the sand mold, K is a constant, K = 1.32 - 1.58, P s is the standard amount of binder added per layer of the sand mold;

[0102] (4) Use computer discrete layering processing to slice the three-dimensional entities of each target module and form the data of the amount of binder sprayed layer by layer;

[0103] (5) Use a 3DP sand mold printing device to add sand layer by layer and spray the budgeted amount of binder layer by layer to obtain the required sand mold / core.

[0104] Through the method of the present invention, the 3D printing of the sand mold / core with overall differential performance forming is realized.

[0105] Those of ordinary skill in the art can understand that the above embodiments are specific cases for implementing the present disclosure, and in practical applications, various changes can be made in form and details without departing from the scope of the present disclosure.

Claims

1. A method for preparing a sand mold with performance differentiation, characterized in that, Including the following steps: Establish a first sand mold model; There are s first yield stresses distributed in the first sand mold, and at least one of the s first yield stresses is inconsistent, where s is a natural number and s≥1; Form a first yield stress distribution data set of the first sand mold model with the s first yield stresses; Divide the first sand mold into n preset modules according to the first yield stress distribution data set, and at least one of the n preset modules has the first yield stress, where n is a natural number and 1≤n≤s; Among the n preset modules, at least one of the preset modules is distributed with f second yield stresses, the second yield stresses are within the range of the first yield stress, and at least one of the f second yield stresses is inconsistent, where f is a natural number and f≥1; Obtain the number of target modules formed into the target sand mold according to the number of the preset modules, and the number of the preset modules is the same as the number of the target modules; Form a single target module according to a single preset module, and the method for forming a single target module includes: Obtain target casting sand according to at least one of the second yield stresses in a single preset module; Obtain the target yield strength of the target module according to the maximum second yield stress among the second yield stresses of a single preset module and the first yield strength of the target casting sand; Cut a single preset module into m die pieces according to the distribution of the second yield stresses of the single preset module, where m is a natural number and m≥1; Obtain the target addition amount of the single-layer binder required for forming the m die pieces into the target module according to the target yield strength; Form a single target module by adding the target casting sand layer by layer and adding the target addition amount of the single-layer binder layer by layer; According to whether the second yield stresses among the n preset modules are consistent or inconsistent, obtain whether the target addition amounts of the single-layer binder required for the n target modules are consistent or inconsistent, and obtain whether the numbers of the die pieces cut from the n preset modules are consistent or inconsistent; Form the target sand mold according to the n target modules.

2. The method for preparing a sand mold with performance differentiation according to claim 1, characterized in that, Among the m die pieces, obtain the thickness of a single die piece according to the third yield stress of the single die piece and the first yield strength of the target casting sand, and the third yield stress is within the range of the second yield stress.

3. A method for preparing a sand mold with performance differentiation according to claim 1, characterized in that The first yield stress distribution data set includes a first yield stress I, a first yield stress II, and a first yield stress III, and the first yield stress I≤the first yield stress II≤the first yield stress III. Divide the first sand mold into a first preset module, a second preset module, and a third preset module according to the first yield stress I, the first yield stress II, and the first yield stress III.

4. The method for preparing a sand mold with performance differentiation according to claim 3, characterized in that The first yield stress I is 0-400 Mpa, the first yield stress II is 400-800 Mpa, and the first yield stress III is 800-1200 Mpa.

5. A method for preparing a sand mold with performance differentiation according to claim 1, characterized in that, Obtain the target yield strength of the target module based on the maximum second yield stress of the preset module, the first yield strength of the target casting sand material, and the standard yield strength of the sand mold.

6. The method for preparing a sand mold with performance differentiation according to claim 5, characterized in that, The calculation formula for the target yield strength of the target module is as follows: ； Among them, X is the target yield strength of the target module, σ m is the maximum secondary yield stress within the preset module, σ Q is the yield strength of the target casting sand material, Q s is the standard yield strength of the sand mold.

7. A method for preparing a sand mold with performance differentiation according to claim 1, characterized in that, Obtain the target addition amount of the single-layer binder required for forming the m die pieces into the target module based on the target yield strength of the target module, the yield strength of the target casting sand material, and the standard addition amount of the single-layer binder of the sand mold.

8. A method for preparing a sand mold with performance differentiation according to claim 7, characterized in that, The calculation formula for the target addition amount of the single-layer binder required for the preset module is as follows: ； Among them, Y is the target addition amount of the single-layer binder required by the preset module, X is the target yield strength of the target module, Q s is the standard yield strength of the sand mold, K is a constant, K = 1.32 - 1.58, P s is the standard addition amount of the single-layer binder of the sand mold.

9. A method for preparing a sand mold with performance differentiation according to claim 1, characterized in that, The target addition amount of the single-layer binder is the addition amount of the binder between two adjacent layers of the m die pieces, and the target addition amount of the single-layer binder required for forming a single target module is the same.

10. A method for preparing a sand mold with performance differentiation according to claim 1, characterized in that, Based on whether the second yield stresses between the n preset modules are the same or different, obtain that the target addition amounts of the single-layer binder required for the n target modules are the same respectively, and obtain whether the numbers of die pieces cut from the n preset modules are the same or different.

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