WO2024108609A1 - 异形件加工模具及设计、装配方法 - Google Patents

异形件加工模具及设计、装配方法 Download PDF

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WO2024108609A1
WO2024108609A1 PCT/CN2022/134532 CN2022134532W WO2024108609A1 WO 2024108609 A1 WO2024108609 A1 WO 2024108609A1 CN 2022134532 W CN2022134532 W CN 2022134532W WO 2024108609 A1 WO2024108609 A1 WO 2024108609A1
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mold
special
sleeve
shaped parts
stress distribution
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PCT/CN2022/134532
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English (en)
French (fr)
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徐潇
王欣
龚攀
刘钊
胡金华
刘鹏
刘加亮
张晓峰
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上海电机学院
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Publication of WO2024108609A1 publication Critical patent/WO2024108609A1/zh

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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • G06F30/23—Design optimisation, verification or simulation using finite element methods [FEM] or finite difference methods [FDM]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
    • B21J13/00—Details of machines for forging, pressing, or hammering
    • B21J13/02—Dies or mountings therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
    • B23P21/00—Machines for assembling a multiplicity of different parts to compose units, with or without preceding or subsequent working of such parts, e.g. with programme control

Definitions

  • the present application relates to the field of mold design, and in particular to a mold for processing special-shaped parts and a design and assembly method thereof.
  • Cold forging technology is a common method for producing special-shaped products.
  • the plastic forming process of the product is completed under three-way compressive stress conditions, so that the shape of the forging is close to the molded shape of the part, with no burrs or very few burrs.
  • the material utilization rate of some products can reach more than 95%, which greatly reduces the material cost and can even be used directly without subsequent machining.
  • This forging method can not only save raw materials, but also greatly improve the internal quality and forming accuracy of the product, and the formed parts have stable dimensions and good consistency.
  • multi-layer nested extrusion dies are generally used for special-shaped parts.
  • the shape of the die is generally a perfect circle.
  • due to the large and asymmetric forming force there is often an uneven stress distribution or even local stress concentration problem in the circumferential direction of the extrusion die, which causes serious wear and even local cracking between the dies, thereby greatly reducing the service life of the die.
  • the stress concentration and tangential tensile stress inside the special-shaped die cavity are large, making the die very prone to local wear and longitudinal cracking.
  • the present application provides a method for designing a mold for processing special-shaped parts, the method comprising:
  • the mold design is completed.
  • the parameters required for processing the special-shaped parts include:
  • the analyzing the equivalent stress distribution after the mold is assembled also includes:
  • the axial compression ratios at the mating surfaces of the mold are adjusted so that the compression ratio at one mold mating surface gradually increases or decreases along the axial direction, and the axial compression ratios at adjacent mold mating surfaces change in the opposite direction.
  • the selecting of some of the equivalent stress evaluation points includes:
  • the non-uniform selection of evaluation points method is adopted to select points densely at stress concentration points and select points sparsely and symmetrically at other locations.
  • the performing isointensity simulation includes:
  • the mold diameter at each evaluation point is fine-tuned to change the compression ratio at the mold mating surface, thereby adjusting the equivalent stress distribution at the mold mating surface.
  • the step of obtaining a circumferentially distributed compression sleeve ratio variation curve at the mold mating surface further includes:
  • the new mold is designed, including:
  • the outer contour of the mold core is slightly modified locally to obtain a mold core that is not completely a regular circle.
  • the present application provides a special-shaped parts processing mold, which is obtained by applying the above-mentioned design method, and the mold includes:
  • a mold core having a mold cavity inside that matches the contour of the special-shaped part to be processed
  • the middle sleeve is sleeved on the outer ring of the mold core, and the contour of the matching surface between the middle sleeve and the mold core is not completely a regular circle;
  • the outer sleeve is sleeved on the outer ring of the intermediate sleeve, and the equivalent stress at the matching surfaces among the outer sleeve, the intermediate sleeve and the mold core is evenly distributed.
  • the compression ratio at one matching surface between the mold core, the intermediate sleeve and the outer sleeve gradually increases or decreases in the axial direction, and the axial compression ratio at the other matching surface changes in the opposite direction.
  • the present application provides a method for assembling a mold for processing special-shaped parts, which is applied to the above-mentioned mold, and is characterized in that the method comprises:
  • the mold core, the middle sleeve and the outer sleeve are assembled from the inside to the outside or from the outside to the inside by means of heat sleeve or cold sleeve.
  • the above-mentioned special-shaped parts processing die and design and assembly method analyzes the equivalent stress distribution after the die is assembled, and fine-tunes the contour of the mating surface according to the equivalent stress distribution, thereby changing the equivalent stress distribution at the die mating surface.
  • This method is highly operable, low-cost, and highly efficient, and is suitable for the local stress adjustment of all special-shaped cold forging dies and the optimized design and production of any precision forging extrusion die. It can effectively reduce the local stress concentration during the subsequent use of the die, and to a certain extent offset the shear stress on the die during the cold forging deformation process, avoid stress concentration and fracture, improve the problem of uneven circumferential stress distribution at the die mating surface, and make the die service life longer.
  • FIG1 is a step diagram of a method for designing a mold for processing special-shaped parts in one embodiment
  • FIG2 is a step diagram of a method for designing a mold for processing special-shaped parts in another embodiment
  • FIG3 is an equivalent stress distribution diagram of a special-shaped part processing mold before numerical simulation analysis in one embodiment
  • FIG4 is an equivalent stress distribution diagram after numerical simulation analysis of a special-shaped part processing mold in one embodiment
  • FIG5 is a schematic structural diagram of a fork-shaped part in one embodiment
  • FIG6 is a schematic structural diagram of a mold for processing special-shaped parts in one embodiment
  • FIG. 7 is a schematic structural diagram of a special-shaped part processing mold for obtaining an approximate circular curve after matching surface compensation in one embodiment.
  • first and second are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as “first” and “second” may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality” is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.
  • a first feature being “above” or “below” a second feature may mean that the first feature is directly in contact with the second feature, or the first feature and the second feature are indirectly in contact through an intermediate medium.
  • a first feature being “above”, “above” or “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature.
  • a first feature being “below”, “below” or “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.
  • a method for designing a mold for processing a special-shaped part includes the following steps:
  • Step S110 constructing a multi-layer combined mold according to the parameters required for processing the special-shaped part.
  • the parameters required for the processing of special-shaped parts include the shape, material and required forming force of the special-shaped parts.
  • the part is formed by cold extrusion, and the forming force is huge and uneven. Stress concentration is easily generated at the inner corner edge of the mold, causing the mold to crack during cold extrusion and a low life.
  • the material used for the fork-shaped part is 20Cr (low hardenability carburizing steel).
  • the blank model is imported into the forming software for numerical simulation analysis, and the maximum load of the material during the deformation process is about 2.06*106N.
  • a forming equipment with a tonnage of 300T is selected.
  • a multi-layer combined mold is constructed, including a mold core, an intermediate sleeve and an outer sleeve.
  • the mold core of the mold is made of Japan's Daijie super-hard NC16/NC14 tungsten steel plate material, and the intermediate sleeve and outer sleeve are made of H13 mold steel or SKD61 material.
  • Step S120 analyzing the equivalent stress distribution after the mold is assembled, and selecting some equivalent stress evaluation points therein to perform equal strength simulation to obtain a circumferentially distributed compression sleeve ratio variation curve at the mold mating surface.
  • a finite element analysis model is established to analyze the preload distribution after mold assembly.
  • the stress and strain distribution between each layer of the mold is obtained by numerical simulation software such as deform/ANSYS/forge.
  • deform/ANSYS/forge As shown in Figure 3, the stress distribution inside the mold core and the matching surface between the outer sleeve and the intermediate sleeve under the condition of 0.6% interference fit between conventional circles and circles. It can be seen from the figure that at this time, a more obvious stress concentration appears at the corner position of the mold (corresponding to the outer edge position of the fork-shaped part), and the maximum equivalent stress is about 2075MPa.
  • the dotted line in the figure represents the mold core
  • the solid line represents the contour shape of the intermediate sleeve.
  • the shape and size of the dotted line are appropriately “enlarged” and “exaggerated”.
  • the actual core contour curve is based on a regular circle with a few modifications and deletions.
  • Step S130 according to the compression sleeve ratio variation curve distributed circumferentially at the mold mating surface, the curve variation at different circumferential positions of the mold is obtained, so as to design a new mold.
  • the curve change in the circumferential direction of the mold is calculated based on the sleeve ratio change curve, and the core model is reconstructed based on this. At this time, the circular core shape is no longer so regular.
  • Step S140 determining whether the new mold has uneven stress distribution, if so, repeating step S120, if not, the mold design is completed.
  • a finite element analysis model is established to analyze the preload distribution after mold assembly.
  • the mold stress distribution is re-simulated according to the approximate circular curve design after the above-mentioned matching surface compensation.
  • the inner corner of the mold core is still a stress concentration position, and its equivalent stress is about 1155MPa, which is 44.3% lower than 2075MPa. Therefore, if the uneven local stress distribution is not significantly improved, repeat the analysis of the equivalent stress distribution after mold assembly and perform subsequent steps.
  • the above-mentioned special-shaped parts processing die design method analyzes the equivalent stress distribution after the die is assembled, and fine-tunes the contour of the mating surface according to the equivalent stress distribution, thereby changing the equivalent stress distribution at the die mating surface.
  • This method is highly operable, low-cost, and highly efficient, and is suitable for the local stress adjustment of all special-shaped cold forging dies and the optimized design and production of any precision forging extrusion dies. It can effectively reduce the local stress concentration during the subsequent use of the die, and to a certain extent offset the shear stress on the die during the cold forging deformation process, avoid stress concentration and fracture, improve the problem of uneven circumferential stress distribution at the die mating surface, and make the die service life longer.
  • a method for designing a mold for processing a special-shaped part includes the following steps:
  • Step S210 constructing a multi-layer combined mold according to the parameters required for processing the special-shaped part.
  • the parameters required for the processing of special-shaped parts include the shape, material and required forming force of the special-shaped parts.
  • the part is formed by cold extrusion, and the forming force is huge and uneven. Stress concentration is easily generated at the inner corner edge of the mold, causing the mold to crack during cold extrusion and a low life.
  • the material used for the fork-shaped part is 20Cr (low hardenability carburizing steel).
  • the blank model is imported into the forming software for numerical simulation analysis, and the maximum load of the material during the deformation process is about 2.06*106N.
  • a forming equipment with a tonnage of 300T is selected.
  • a multi-layer combined mold is constructed, including a mold core, an intermediate sleeve and an outer sleeve.
  • the mold core of the mold is made of Japan's Daijie super-hard NC16/NC14 tungsten steel plate material, and the intermediate sleeve and outer sleeve are made of H13 mold steel or SKD61 material.
  • the assembly method of prestressed molds has a great impact on the life of the mold, and the distribution of the preload force of the mold along the axial direction is uneven.
  • the preload force is the largest in the middle of the axial direction and gradually decreases toward both ends. If the traditional heat-shrink method with the same upper and lower compression ratio is used during assembly, the mold itself will produce a certain bending stress, and the shear stress on the mold during the extrusion process is also likely to cause mold cracking.
  • the complementary principle is adopted here to fine-tune the axial transformer sleeve ratio between each layer of the mold, that is, to axially fine-tune the interference fit at the mold mating surface, one option is “loose on top and tight on bottom", and the other option is “tight on top and loose on bottom”.
  • Step S230 analyzing the equivalent stress distribution after the mold is assembled.
  • a finite element analysis model is established to analyze the preload distribution after mold assembly.
  • the stress and strain distribution between each layer of the mold is obtained by using numerical simulation software such as deform/ANSYS/forge.
  • Figure 3 the stress distribution inside the mold core and the mating surface between the outer sleeve and the middle sleeve under the condition of 0.6% interference fit between conventional circles and circles is shown. It can be seen from the figure that at this time, a more obvious stress concentration appears at the corner position of the mold (corresponding to the outer edge position of the fork-shaped part), and the maximum equivalent stress is about 2075MPa.
  • Step S240 adopting a non-uniform selection method for evaluation points, densely selecting points at stress concentration locations, and sparsely and symmetrically selecting points at other locations.
  • evaluation point selection methods are used according to the stress distribution, such as dense point selection at the stress concentration point and sparse and symmetrical point selection at other positions.
  • evaluation points A, B, C, D, and E in FIG. 7 are finally obtained.
  • Step S250 fine-tuning the mold diameter at each evaluation point, changing the compression ratio at the mold mating surface, and thus adjusting the equivalent stress distribution at the mold mating surface.
  • the pressing sleeve ratio at each location is adjusted to change the equivalent stress distribution in the circumferential direction of the mold, thereby improving the mold usage consumption.
  • Step S260 repeatedly iterating the equivalent stress distribution analysis, evaluation point selection and equivalent stress distribution adjustment process to obtain a circumferentially distributed pressing sleeve ratio variation curve at the mold mating surface.
  • the contour of the mold mating surface is continuously adjusted, thereby continuously improving the stress concentration at the mold mating surface, and finally obtaining the compression sleeve ratio change curve along the circumference of the mating surface under the ideal state, as shown in Figure 7.
  • the dotted line in the figure represents the mold core
  • the solid line represents the contour shape of the intermediate sleeve.
  • the shape and size of the dotted line are moderately "enlarged” and “exaggerated”.
  • the actual mold core contour curve is a small modification and deletion based on the regular circle.
  • Step S270 obtaining curve changes at different circumferential positions of the mold according to the circumferentially distributed compression sleeve ratio change curve at the mold mating surface.
  • the original matching surface contour of the mold is used as a reference to calculate the curve change in the circumferential direction of the mold. According to the curve change combined with the original matching surface contour of the mold, the mold with the matching surface compensated can be obtained.
  • Step S280 locally modify the outer contour of the mold core to obtain a mold core that is not completely a regular circle.
  • the combination of the middle sleeve and the outer sleeve is a new mold after the matching surface is compensated.
  • the shape of the curve at different positions of the die and the "addition and subtraction" of the die shape fine-tuning are reversely designed according to the sleeve ratio curve to determine the outer dimensions of the extrusion die that is not completely a regular circle.
  • Step S290 determine whether the new mold has uneven stress distribution. If so, repeat step S230. If not, the mold design is completed.
  • a finite element analysis model is established to analyze the preload distribution after mold assembly.
  • the mold stress distribution is re-simulated according to the approximate circular curve design after the above-mentioned matching surface compensation.
  • the inner corner of the mold core is still a stress concentration position, and its equivalent stress is about 1155MPa, which is 44.3% lower than 2075MPa. Therefore, if the uneven local stress distribution is not significantly improved, repeat the analysis of the equivalent stress distribution after mold assembly and perform subsequent steps.
  • the above-mentioned special-shaped parts processing die design method changes the axial compression sleeve ratio at the die mating surface so that the axial compression sleeve ratios at two adjacent die mating surfaces are set in opposite directions, which can reduce or even eliminate the bending stress generated inside the die itself, and can also offset the shear stress on the die during the extrusion process to a certain extent, avoid stress concentration and fracture of the die, and greatly reduce the possibility of cracking of the die.
  • the equivalent stress distribution at the die mating surface is changed.
  • This method has strong operability, low cost and high efficiency, and is suitable for local stress adjustment of all special-shaped parts cold forging dies and the optimized design and production of any precision forging extrusion die. It can effectively reduce the local stress concentration in the subsequent use of the die, and to a certain extent offset the shear stress on the die during the cold forging deformation process, avoid stress concentration and fracture, improve the problem of uneven circumferential stress distribution at the die mating surface, and make the die service life longer.
  • a special-shaped part processing mold is obtained by applying the above-mentioned special-shaped part processing mold design method, comprising a mold core 110, an intermediate sleeve 120 and an outer sleeve 130; the mold core 110 has a mold cavity matching the contour of the special-shaped part to be processed; the intermediate sleeve 120 is sleeved on the outer ring of the mold core 110, and the contour of the matching surface between the intermediate sleeve 120 and the mold core 110 is not completely a regular circle; the outer sleeve 130 is sleeved on the outer ring of the intermediate sleeve 120, and the equivalent stress distribution at the matching surface between the outer sleeve 130, the intermediate sleeve 120 and the mold core 110 is uniform.
  • the equivalent stress distribution at the matching surface between the mold core 110, the intermediate sleeve 120 and the outer sleeve 130 is uniform
  • the compression ratio at one mating surface between the mold core 110, the middle sleeve 120 and the outer sleeve 130 gradually increases or decreases in the axial direction, and the axial compression ratio at the other mating surface changes in the opposite direction.
  • the assembly method of prestressed molds has a great impact on the life of the mold, and the distribution of the preload force of the mold along the axial direction is uneven.
  • the preload force is the largest in the middle of the axial direction and gradually decreases toward both ends. If the traditional heat-shrink method with the same upper and lower compression ratio is used during assembly, the mold itself will produce a certain bending stress, and the shear stress on the mold during the extrusion process is also likely to cause mold cracking.
  • the complementary principle is adopted here to fine-tune the axial transformer sleeve ratio between each layer of the mold, that is, to axially fine-tune the interference fit at the mold mating surface, one option is “loose on top and tight on bottom", and the other option is “tight on top and loose on bottom”.
  • a conventional circular core 110 regular mold is designed here, and the overall circumferential and axial transformer sleeve ratios of the mold are consistent with the above embodiment, and the circumferential transformer sleeve ratio of the mold is changed without numerical analysis, that is, the interference fit between the core 110 and the intermediate sleeve 120 is set to 0.6%.
  • the life of a conventional mold is about 20,000 times, while the life of the mold in this embodiment is about 50,000 times, and the mold life is increased by about 150%, which effectively increases the mold life and reduces production costs.
  • a method for assembling a mold for processing a special-shaped part uses a heat-shrink sleeve or a cold-shrink sleeve method to assemble a mold core, an intermediate sleeve, and an outer sleeve from the inside to the outside or from the outside to the inside.
  • the order of pressing is generally as follows: the extrusion molds are named from the outermost layer to the innermost layer, namely the outermost mold, the second-to-last mold, the third-to-last mold... until the innermost mold.
  • the second-to-last mold is pressed into the outermost layer
  • the third-to-last mold is pressed into the second-to-last layer
  • the fourth-to-last mold is pressed into the third-to-last layer... and so on
  • the hot-pressing method is used for assembly.
  • the cold-pressing method is the opposite.

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Abstract

本申请涉及一种异形件加工模具及设计、装配方法，其中设计方法包括：根据异形件加工所需参数，构建一个多层组合式模具；分析模具装配后的等效应力分布，并选取其中部分等效应力评价点，进行等强度模拟，获得模具配合面处周向分布的压套比变化曲线；根据模具配合面处周向分布的压套比变化曲线，获得模具周向不同位置处曲线变化，以此设计出新模具；判断新模具是否具有应力分布不均匀的情况，若是，则重复分析模具装配后的等效应力分布；若否，则模具设计完成。上述异形件加工模具及设计、装配方法，避免了模具发生应力集中和断裂，改善了模具配合面处的周向应力分布不均匀的问题，使得模具使用寿命更长。

Description

异形件加工模具及设计、装配方法 技术领域
本申请涉及模具设计领域，特别是涉及一种异形件加工模具及设计、装配方法。
背景技术
目前市场上对于结构复杂的异形件产品需求越来越多，尤其是在航空航天器件、汽车覆盖件、家用电器部件等领域的应用颇为广泛。
冷锻技术是生产异形件产品的常用方法，在三向压应力条件下完成产品的塑性成形过程，使得到的锻件形状接近于零件成型形状，且没有毛边或很少毛边，有些产品的材料利用率能达到95％以上，大幅降低了材料成本，甚至后序可不进行机加工直接使用，该种锻造方式不仅能够节约原材料，还可以大幅度提高产品内部质量和成形精度，且成形的零件尺寸稳定，一致性好。
异形件在精密冷锻实际生产中一般采用多层嵌套式挤压模具，模具外形一般为正圆形，但由于成形力大且不对称，在挤压模具圆周方向常常存在应力分布不均匀甚至是局部应力集中问题，造成模具之间磨损严重乃至局部开裂，从而大大降低模具使用寿命。例如在黑色金属异形件的挤压过程中，由于单位挤压力相当大，导致异形模具型腔内部的应力集中和切向拉应力较大，使得模具极易出现局部磨损和纵向开裂。
发明内容
基于此，有必要针对上述技术问题，提供一种异形件加工模具及设计、装配方法，能够有效改善模具周向应力分布不均匀的问题，使得模具使用寿命更长。
第一方面，本申请提供了一种异形件加工模具设计方法，所述方法包括：
根据异形件加工所需参数，构建一个多层组合式模具；
分析模具装配后的等效应力分布，并选取其中部分等效应力评价点，进行等强度模拟，获得模具配合面处周向分布的压套比变化曲线；
根据模具配合面处周向分布的压套比变化曲线，获得模具周向不同位置处曲线变化，以此设计出新模具；
判断新模具是否具有应力分布不均匀的情况，若是，则重复
分析模具装配后的等效应力分布；若否，则
模具设计完成。
在其中一个实施例中，所述异形件加工所需参数，包括：
异形件的形状、材料及所需成型力的大小。
在其中一个实施例中，所述分析模具装配后的等效应力分布，之前还包括：
对模具各配合面处的轴向压套比进行调整，使一个模具配合面处的压套比沿轴向渐增或渐缩，使相邻的模具配合面处的轴向压套比变化方向与之相反。
在其中一个实施例中，所述选取其中部分等效应力评价点，包括：
采用非均匀选取评价点方法，对应力集中处进行密集选点，对其他位置进行稀疏、对称选点。
在其中一个实施例中，所述进行等强度模拟，包括：
对各评价点处的模具直径进行微调，改变模具配合面处的压套比，从而调整模具配合面处的等效应力分布。
在其中一个实施例中，所述获得模具配合面处周向分布的压套比变化曲线，之前还包括：
反复迭代等效应力分布分析、评价点选取及等效应力分布调整过程。
在其中一个实施例中，所述以此设计出新模具，包括：
对模芯外周轮廓进行局部的微量修改，获得不完全为规整圆形的模芯。
第二方面，本申请提供了一种异形件加工模具，应用上述设计方法获得，所述模具包括：
模芯，内部具有与待加工异形件轮廓相匹配的模腔；
中间套，套设在所述模芯外圈，且与所述模芯之间的配合面的轮廓不完全为规 整圆形；
外套，套设在所述中间套外圈，且所述外套、所述中间套和所述模芯之间的配合面处的等效应力分布均匀。
在其中一个实施例中，所述模芯、所述中间套和所述外套之间的一个配合面处的压套比沿轴向渐增或渐缩，另一个配合面处的轴向压套比变化方向与之相反。
第三方面，本申请提供了一种异形件加工模具装配方法，应用于上述模具，其特征在于，所述方法包括：
采用热套或冷压套法的方式，由内向外或由外向内对模芯、中间套和外套进行装配。
上述异形件加工模具及设计、装配方法，通过分析模具装配后的等效应力分布，并根据等效应力分布情况对配合面处的轮廓进行微调，从而改变模具配合面处的等效应力分布情况，该方法可操作性强、成本低、效率高，适用于所有异形件冷锻模具的局部应力调整及任何精锻挤压模具的优化设计生产。可以有效减小模具后续使用过程中的局部应力集中，并在一定程度上抵消冷锻变形过程中模具上的剪切应力，避免发生应力集中和断裂，改善了模具配合面处的周向应力分布不均匀的问题，使得模具使用寿命更长。
附图说明
图1为一个实施例中的异形件加工模具设计方法的步骤图；
图2为另一个实施例中的异形件加工模具设计方法的步骤图；
图3为一个实施例中的异形件加工模具数值模拟分析前的等效应力分布图；
图4为一个实施例中的异形件加工模具数值模拟分析后的等效应力分布图；
图5为一个实施例中的叉形零件的结构示意图；
图6为一个实施例中的异形件加工模具的结构示意图；
图7为一个实施例中的得到配合面补偿后的近似圆周曲线的异形件加工模具的结构示意图。
图中：110、模芯；120、中间套；130、外套。
具体实施方式
为使本申请实施例的目的、技术方案和优点更加清楚，下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地说明，显然，所描述的实施例是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
需要说明的是，当组件被称为“固定于”或“设置于”另一个组件，它可以直接在另一个组件上或者也可以存在居中的组件。当一个组件被认为是“连接”另一个组件，它可以是直接连接到另一个组件或者可能同时存在居中组件。本申请的说明书所使用的术语“垂直的”、“水平的”、“上”、“下”、“左”、“右”以及类似的表述只是为了说明的目的，并不表示是唯一的实施方式。
此外，术语“第一”、“第二”仅用于描述目的，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”的特征可以明示或者隐含地包括至少一个该特征。在本申请的描述中，“多个”的含义是至少两个，例如两个，三个等，除非另有明确具体的限定。
在本申请中，除非另有明确的规定和限定，第一特征在第二特征“上”、“下”可以是第一特征直接和第二特征接触，或第一特征和第二特征间接地通过中间媒介接触。而且，第一特征在第二特征“之上”、“上方”和“上面”可是第一特征在第二特征正上方或斜上方，或仅表示第一特征水平高度高于第二特征。第一特征在第二特征“之下”、“下方”和“下面”可以是第一特征在第二特征正下方或斜下方，或仅表示第一特征水平高度小于第二特征。
除非另有定义，本申请的说明书所使用的所有的技术和科学术语与属于本申请的技术领域的技术人员通常理解的含义相同。在本申请的说明书中所 使用的术语只是为了描述具体的实施方式的目的，不是旨在于限制本申请。本申请的说明书所使用的术语“及/或”包括一个或多个相关的所列项目的任意的和所有的组合。
如图1所示，在一个实施例中，一种异形件加工模具设计方法，包括以下步骤：
步骤S110，根据异形件加工所需参数，构建一个多层组合式模具。
具体的，异形件加工所需参数包括异形件的形状、材料及所需成型力的大小。以图5所示的一种目前已存在的叉形零件为例，在实际生产中，该零件采用冷挤压成形，成形力巨大且不均匀，模具内侧角部边缘处极易产生应力集中，造成模具在冷挤压中开裂，寿命较低，该叉形零件选用的材料为20Cr(低淬透性渗碳钢)，将胚料模型导入到成型软件中进行数值模拟分析，即可得到变形过程中材料的最大载荷约为2.06*106N。根据该叉形零件成型力的大小，选用吨位为300T的成型设备。根据该叉形零件的材料，构建一个多层组合式模具，包括模芯、中间套和外套三层，该模具的模芯选用日本黛杰超硬NC16/NC14钨钢板材料，中间套和外套选用H13模具钢或者SKD61材料。
步骤S120，分析模具装配后的等效应力分布，并选取其中部分等效应力评价点，进行等强度模拟，获得模具配合面处周向分布的压套比变化曲线。
具体的，根据加工模具尺寸和装配顺序原则，建立有限元分析模型，分析模具装配后的预紧力分布，例如采用deform/ANSYS/forge等数值模拟软件分析得到各层模具间应力应变分布。如图3所示，该图为常规圆与圆0.6％过盈配合组合条件下的模芯内部以及外套与中间套之间配合面处的应力分布，从图中可以看出此时模具角部位置(对应叉形零件外侧棱边位置)出现较为明显的应力集，最大的等效应力约为2075MPa。此时选取其中几处应力评价点，并对选取点处的圆形直径进行微调，从而调整各处的压套比以改变模具周向上的等效应力分布，最后得到理想状态下的配合面上沿圆周分布的压套比(压套比＝过盈量/配合直径)变化曲线，如图7所示。需要说明的是，图中虚线代表模芯，实线代表中间套轮廓形状，为凸出变压套比曲线的设计，虚线形状 尺寸进行了适度的“放大”与“夸张”。实际的模芯轮廓曲线是在规整圆形的基础上做了少量的修改与删减。
步骤S130，根据模具配合面处周向分布的压套比变化曲线，获得模具周向不同位置处曲线变化，以此设计出新模具。
具体的，根据压套比变化曲线计算得到模具周向的曲线变化，并以此重新构建模芯模型，此时圆形的模芯外形不再那么规整。
步骤S140，判断新模具是否具有应力分布不均匀的情况，若是，则重复执行步骤S120，若否，则模具设计完成。
具体的，根据新模具尺寸和装配顺序，建立有限元分析模型，分析模具装配后的预紧力分布。如图4所示，该图为按照上述配合面补偿后的近似圆周曲线设计重新模拟得到的模具应力分布，此时模芯内角部位置仍为应力集中位置，其等效应力大小约为1155MPa，较2075MPa降低了月44.3％。因此，若局部应力分布不均的情况改善不明显，则重复分析模具装配后的等效应力分布，并执行后续步骤。
上述异形件加工模具设计方法，通过分析模具装配后的等效应力分布，并根据等效应力分布情况对配合面处的轮廓进行微调，从而改变模具配合面处的等效应力分布情况，该方法可操作性强、成本低、效率高，适用于所有异形件冷锻模具的局部应力调整及任何精锻挤压模具的优化设计生产。可以有效减小模具后续使用过程中的局部应力集中，并在一定程度上抵消冷锻变形过程中模具上的剪切应力，避免发生应力集中和断裂，改善了模具配合面处的周向应力分布不均匀的问题，使得模具使用寿命更长。
如图2所示，在一个实施例中，一种异形件加工模具设计方法，包括以下步骤：
步骤S210，根据异形件加工所需参数，构建一个多层组合式模具。
具体的，异形件加工所需参数包括异形件的形状、材料及所需成型力的大小。以图5所示的一种目前已存在的叉形零件为例，在实际生产中，该零件采用冷挤压成形，成形力巨大且不均匀，模具内侧角部边缘处极易产生应力集中， 造成模具在冷挤压中开裂，寿命较低，该叉形零件选用的材料为20Cr(低淬透性渗碳钢)，将胚料模型导入到成型软件中进行数值模拟分析，即可得到变形过程中材料的最大载荷约为2.06*106N。根据该叉形零件成型力的大小，选用吨位为300T的成型设备。根据该叉形零件的材料，构建一个多层组合式模具，包括模芯、中间套和外套三层，该模具的模芯选用日本黛杰超硬NC16/NC14钨钢板材料，中间套和外套选用H13模具钢或者SKD61材料。
步骤S220，对模具各配合面处的轴向压套比(压套比＝过盈量/配合直径)进行调整，使一个模具配合面处的压套比沿轴向渐增或渐缩，使相邻的模具配合面处的轴向压套比变化方向与之相反。
具体的，在近几年的研究和生产实践中发现，预应力模具的装配方法对模具寿命的影响较大，且模具沿轴向的预紧力的分布是不均匀的。通常来说，多层嵌套式挤压模具存在端部效应，即预紧力在轴向中间最大并向两端逐渐减小，装配时若采用上下压套比一致的传统热套方法，模具本身会产生一定的弯曲应力，挤压过程中模具上的剪切应力也较大概率会造成模具开裂现象。
因此，此处采用互补原则微调各层模具之间的轴向变压套比，即对模具配合面处的过盈配合量进行轴向微调，一个选择“上松下紧”，另一个选择“上紧下松”。通过这种改变轴向变压套比的方法来调整模具预应力，能够减少甚至消除模具本身内部产生的弯曲应力，也可在一定程度上抵消挤压过程中模具上的剪切应力，避免模具发生应力集中和断裂，大大减小了模具发生开裂的可能性。
步骤S230，分析模具装配后的等效应力分布。
具体的，根据加工模具尺寸和装配顺序原则，建立有限元分析模型，分析模具装配后的预紧力分布，例如采用deform/ANSYS/forge等数值模拟软件分析得到各层模具间应力应变分布。如图3所示，该图为常规圆与圆0.6％过盈配合组合条件下的模芯内部以及外套与中间套之间配合面处的应力分布，从图中可以看出此时模具角部位置(对应叉形零件外侧棱边位置)出现较为明显的应力集，最大的等效应力约为2075MPa。
步骤S240，采用非均匀选取评价点方法，对应力集中处进行密集选点，对其他位置进行稀疏、对称选点。
具体的，根据应力分布情况采用不同的评价点选取方式，如对应力集中处进行密集选点，对其他位置进行稀疏、对称选点，根据该评价点选取方式最终得到如图7中的A、B、C、D、E等评价点。
步骤S250，对各评价点处的模具直径进行微调，改变模具配合面处的压套比，从而调整模具配合面处的等效应力分布。
具体的，通过对选取点处的圆形直径进行微调，从而调整各处的压套比以改变模具周向上的等效应力分布，从而改善模具使用消耗情况。
步骤S260，反复迭代等效应力分布分析、评价点选取及等效应力分布调整过程，获得模具配合面处周向分布的压套比变化曲线。
具体的，通过反复迭代等效应力分布分析、评价点选取及等效应力分布调整过程，以不断调整模具配合面处轮廓，从而不断的改善模具配合面处的应力集中情况，最后得到理想状态下的配合面上沿圆周分布的压套比变化曲线，如图7所示。需要说明的是，图中虚线代表模芯，实线代表中间套轮廓形状，为凸出变压套比曲线的设计，虚线形状尺寸进行了适度的“放大”与“夸张”。实际的模芯轮廓曲线是在规整圆形的基础上做了少量的修改与删减。
步骤S270，根据模具配合面处周向分布的压套比变化曲线，获得模具周向不同位置处曲线变化。
具体的，根据压套比变化曲线情况，以模具原配合面轮廓为基准，能够计算得到模具周向上的曲线变化，根据该曲线变化结合模具原配合面轮廓即可得到配合面经过补偿后的模具。
步骤S280，对模芯外周轮廓进行局部的微量修改，获得不完全为规整圆形的模芯。结合中间套和外套即是配合面经过补偿后的新模具。
具体的，根据压套比曲线逆推设计模具不同位置处的曲线形状和模具形状微调的“加减量”，确定上述不完全为规整圆形的挤压模具外形尺寸。
步骤S290，判断新模具是否具有应力分布不均匀的情况，若是，则重复 执行步骤S230，若否，则模具设计完成。
具体的，根据新模具尺寸和装配顺序，建立有限元分析模型，分析模具装配后的预紧力分布。如图4所示，该图为按照上述配合面补偿后的近似圆周曲线设计重新模拟得到的模具应力分布，此时模芯内角部位置仍为应力集中位置，其等效应力大小约为1155MPa，较2075MPa降低了月44.3％。因此，若局部应力分布不均的情况改善不明显，则重复分析模具装配后的等效应力分布，并执行后续步骤。
上述异形件加工模具设计方法，通过对模具配合面处的轴向压套比进行改变，使得模具相邻两个配合面处的轴向压套比呈相反方向设置，能够减少甚至消除模具本身内部产生的弯曲应力，也可在一定程度上抵消挤压过程中模具上的剪切应力，避免模具发生应力集中和断裂，大大减小了模具发生开裂的可能性。通过分析模具装配后的等效应力分布，并根据等效应力分布情况对配合面处的轮廓进行微调，从而改变模具配合面处的等效应力分布情况，该方法可操作性强、成本低、效率高，适用于所有异形件冷锻模具的局部应力调整及任何精锻挤压模具的优化设计生产。可以有效减小模具后续使用过程中的局部应力集中，并在一定程度上抵消冷锻变形过程中模具上的剪切应力，避免发生应力集中和断裂，改善了模具配合面处的周向应力分布不均匀的问题，使得模具使用寿命更长。
如图6所示，在一个实施例中，一种异形件加工模具，应用上述异形件加工模具设计方法获得，包括模芯110、中间套120和外套130；模芯110内部具有与待加工异形件轮廓相匹配的模腔；中间套120套设在所述模芯110外圈，且与所述模芯110之间的配合面的轮廓不完全为规整圆形；外套130套设在所述中间套120外圈，且所述外套130、所述中间套120和所述模芯110之间的配合面处的等效应力分布均匀。上述异形件加工模具，模芯110、中间套120以及外套130相互之间的配合面处的等效应力分布均匀，使用寿命更长。
在一个实施例中，所述模芯110、所述中间套120和所述外套130之间的一个配合面处的压套比沿轴向渐增或渐缩，另一个配合面处的轴向压套比变 化方向与之相反。
具体的，在近几年的研究和生产实践中发现，预应力模具的装配方法对模具寿命的影响较大，且模具沿轴向的预紧力的分布是不均匀的。通常来说，多层嵌套式挤压模具存在端部效应，即预紧力在轴向中间最大并向两端逐渐减小，装配时若采用上下压套比一致的传统热套方法，模具本身会产生一定的弯曲应力，挤压过程中模具上的剪切应力也较大概率会造成模具开裂现象。
因此，此处采用互补原则微调各层模具之间的轴向变压套比，即对模具配合面处的过盈配合量进行轴向微调，一个选择“上松下紧”，另一个选择“上紧下松”。通过这种改变轴向变压套比的方法来调整模具预应力，能够减少甚至消除模具本身内部产生的弯曲应力，也可在一定程度上抵消挤压过程中模具上的剪切应力，避免模具发生应力集中和断裂，大大减小了模具发生开裂的可能性。
仍然针对于上述图5中的叉形零件，此处设计了常规的圆形模芯110规整模具，该模具整体周向和轴向变压套比与上述实施例内容一致，不做数值分析改变模具的周向变压套比，即模芯110与中间套120之间的过盈配合量均设置为0.6％。经实际生产测试得知，常规模具寿命约为2万次，而本实施例中的模具寿命约为5万次，模具寿命提升约150％，有效提高了模具寿命，降低了生产成本。
在一个实施例中，一种异形件加工模具装配方法，采用热套或冷压套法的方式，由内向外或由外向内对模芯、中间套和外套进行装配。
具体的，首先根据成形设备吨位型号确定最外层模具尺寸，后根据每层模具强度要求依次确定其他模具直径尺寸。且压套顺序一般如下，规定挤压模具从最外层到最内层依次命名为最外层模具，倒数第二层模具，倒数第三层模具…...直到最内层模具。装配时具体的将倒数第二层模具压入最外层，倒数第三层模具压入倒数第二层，倒数第四层模具压入倒数第三层……..依次类推，最后采用热套法装配。冷压套法则相反。
以上所述实施例的各技术特征可以进行任意的组合，为使描述简洁，未对 上述实施例中的各个技术特征所有可能的组合都进行描述，然而，只要这些技术特征的组合不存在矛盾，都应当认为是本说明书记载的范围。
以上所述实施例仅表达了本申请的几种实施方式，其描述较为具体和详细，但并不能因此而理解为对本申请专利范围的限制。应当指出的是，对于本领域的普通技术人员来说，在不脱离本申请构思的前提下，还可以做出若干变形和改进，这些都属于本申请的保护范围。因此，本申请专利的保护范围应以所附权利要求为准。

Claims (10)

  1. 一种异形件加工模具设计方法，其特征在于，所述方法包括：
    根据异形件加工所需参数，构建一个多层组合式模具；
    分析模具装配后的等效应力分布，并选取其中部分等效应力评价点，进行等强度模拟，获得模具配合面处周向分布的压套比变化曲线；
    根据模具配合面处周向分布的压套比变化曲线，获得模具周向不同位置处曲线变化，以此设计出新模具；
    判断新模具是否具有应力分布不均匀的情况，若是，则重复
    分析模具装配后的等效应力分布；若否，则
    模具设计完成。
  2. 根据权利要求1所述的异形件加工模具设计方法，其特征在于，所述异形件加工所需参数，包括：
    异形件的形状、材料及所需成型力的大小。
  3. 根据权利要求1所述的异形件加工模具设计方法，其特征在于，所述分析模具装配后的等效应力分布，之前还包括：
    对模具各配合面处的轴向压套比进行调整，使一个模具配合面处的压套比沿轴向渐增或渐缩，使相邻的模具配合面处的轴向压套比变化方向与之相反。
  4. 根据权利要求3所述的异形件加工模具设计方法，其特征在于，所述选取其中部分等效应力评价点，包括：
    采用非均匀选取评价点方法，对应力集中处进行密集选点，对其他位置进行稀疏、对称选点。
  5. 根据权利要求4所述的异形件加工模具设计方法，其特征在于，所述进行等强度模拟，包括：
    对各评价点处的模具直径进行微调，改变模具配合面处的压套比，从而调整模具配合面处的等效应力分布。
  6. 根据权利要求5所述的异形件加工模具设计方法，其特征在于，所述获得模具配合面处周向分布的压套比变化曲线，之前还包括：
    反复迭代等效应力分布分析、评价点选取及等效应力分布调整过程。
  7. 根据权利要求6所述的异形件加工模具设计方法，其特征在于，所述以此设计出新模具，包括：
    对模芯外周轮廓进行局部的微量修改，获得不完全为规整圆形的模芯。
  8. 一种异形件加工模具，应用如权利要求1-7任一项所述的设计方法获得，其特征在于，所述模具包括：
    模芯，内部具有与待加工异形件轮廓相匹配的模腔；
    中间套，套设在所述模芯外圈，且与所述模芯之间的配合面的轮廓不完全为规整圆形；
    外套，套设在所述中间套外圈，且所述外套、所述中间套和所述模芯之间的配合面处的等效应力分布均匀。
  9. 根据权利要求8所述的异形件加工模具，其特征在于，所述模芯、所述中间套和所述外套之间的一个配合面处的压套比沿轴向渐增或渐缩，另一个配合面处的轴向压套比变化方向与之相反。
  10. 一种异形件加工模具装配方法，应用于如权利要求8和9任一项所述的模具，其特征在于，所述方法包括：
    采用热套或冷压套法的方式，由内向外或由外向内对模芯、中间套和外套进行装配。
PCT/CN2022/134532 2022-11-22 2022-11-26 异形件加工模具及设计、装配方法 WO2024108609A1 (zh)

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JP2001191336A (ja) * 2000-01-07 2001-07-17 Canon Inc 金型設計装置と金型形状の設計方法
CN101944143A (zh) * 2010-08-25 2011-01-12 一重集团大连设计研究院有限公司 双层圆挤压筒过盈量参数化设计方法
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