Test specimens for testing properties of die castings and test methods for die castings

Abstract

The present disclosure relates to a test piece for testing the performance of a die casting and a test method for the die casting, wherein the test piece comprises a plurality of splines arranged adjacent to each other in a vertical direction, wherein the plurality of splines are configured as a folded shape extending in a horizontal direction and at least two of the plurality of splines have different thicknesses. The test piece provided by the present disclosure can reduce the mold size to the greatest extent, reduce the dependence on large casting equipment, and can accurately simulate the casting molding process of an actual large high-pressure die casting in an ultra-long process, thereby realizing multi-faceted verification of material properties and casting processability.

Description

Technical Field

[0001] The present invention relates to a test piece for testing the performance of a die casting and a method for testing the die casting. Background Art

[0002] Large-scale high-pressure die-cast aluminum alloy structural parts can be produced by integrated molding through high-pressure casting process. The surface of the casting is smooth and flat, with the advantages of high integration, strong load-bearing capacity and light weight. It is suitable for the manufacture of large thin-walled structures such as automobile body parts. When verifying and studying the microstructure and performance of large-scale high-pressure die-cast aluminum alloy structural parts, it is usually necessary to design special large molds and matching high-pressure casting equipment. The testing process is time-consuming, labor-intensive and costly. Since the test conditions and actual production conditions may differ, the reliability of the verification results is also affected. Summary of the invention

[0003] In order to overcome the problems existing in the related art, the present disclosure provides a test piece for testing the performance of a die casting and a test method for the die casting.

[0004] According to a first aspect of an embodiment of the present disclosure, a test piece for testing the performance of a die casting is provided, the test piece comprising a plurality of splines arranged adjacent to each other in a vertical direction, the plurality of splines being configured as folded shapes extending in a horizontal direction, and at least two of the plurality of splines having different thicknesses.

[0005] Optionally, along the vertical direction, the thicknesses of the plurality of splines increase or decrease in sequence.

[0006] Optionally, the spline includes a plurality of straight line portions and a plurality of first curved portions extending in a horizontal direction, the plurality of straight line portions are arranged in parallel and two adjacent straight line portions are connected by the first curved portions, and the first curved portions are configured as a semicircular structure.

[0007] Optionally, the length of the straight portion is 250-350 mm, the distance between two adjacent straight portions is 88-110 mm, and the number of the straight portions is 7-9.

[0008] Optionally, the total length of the sample is 3500~4500mm.

[0009] Optionally, the spline further includes a transition portion, and the straight portion located at one end of the plurality of straight portions is connected to the transition portion via a second curved portion, the second curved portion is configured as an arc structure, and the transition portion is configured as a straight line or a curved structure.

[0010] According to a second aspect of an embodiment of the present disclosure, a method for testing a die casting is provided, the method comprising:

[0011] Acquiring property parameters of the die-casting material and performing mold flow analysis according to the property parameters to obtain a simulated filling result;

[0012] Die-casting the die-casting material to obtain a sample piece as described in the first aspect of the present disclosure and an actual filling result of the sample piece, and comparing the actual filling result with the simulated filling result;

[0013] Sampling at least one preset sampling point on at least one sample strip of the sample piece to obtain at least one group of samples to be tested, wherein the samples to be tested include a first sample and a second sample from the same sample strip at the same preset sampling point;

[0014] Performing a performance test on the first sample to obtain a performance index of the first sample;

[0015] Perform metallographic testing on the second sample to obtain a microstructure index of the second sample, and compare the microstructure index with the performance index.

[0016] Optionally, the property parameter includes at least one of viscosity, thermal conductivity, specific heat and solidus temperature.

[0017] Optionally, the die-casting molding conditions include: a filling time of the die-casting material of 80-160 ms, a mold temperature of 50-250° C., a die-casting vacuum of 60-100 bar, and a die-casting pressure of 20-70 MPa.

[0018] Optionally, the performance test includes at least one of a tensile mechanical property test, a bending property test and a fatigue property test.

[0019] Optionally, the sample to be tested further includes a third sample from the same sample strip at the same preset sampling point, and the method further includes performing a self-riveting test on the third sample and recording a cracking condition of the third sample.

[0020] Through the above-mentioned technical scheme, the test piece provided by the present invention can minimize the mold size and reduce the dependence on large-scale casting equipment. At the same time, it can accurately simulate the casting molding process of actual large-scale high-pressure die-casting parts in an ultra-long process, and realize multi-faceted verification of material properties and casting processability. The testing process is time-saving, labor-saving, and low-cost, and the verification results are highly reliable, which is conducive to a comprehensive evaluation of the performance of die-casting materials under different process conditions and / or different processes, and has important guiding significance for process optimization and material selection in the actual production process of large-scale die-casting parts.

[0021] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0023] Figure 1 It is a schematic structural diagram of a test piece for testing die-casting performance according to an exemplary embodiment.

[0024] Figure 2 is a cross-sectional view of a test piece for testing die-casting performance according to an exemplary embodiment.

[0025] Figure 3 The figure is a flow chart of a method for testing a die casting part, shown in an exemplary embodiment.

[0026] Description of Reference Numerals

[0027] 1-spline, 11-straight portion, 12-first curved portion, 13-transition portion, 14-second curved portion. DETAILED DESCRIPTION

[0028] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0029] In a first aspect, the present invention provides a test piece for testing die casting performance, referring to Figure 1 and Figure 2 As shown, the sample comprises a plurality of splines 1 arranged adjacent to each other in the vertical direction, the plurality of splines 1 are configured as folded shapes extending in the horizontal direction, and at least two of the plurality of splines 1 have different thicknesses. Figure 1 , "horizontal direction" refers to the horizontal plane (i.e. Figure 1 The direction parallel to the plane defined by the x-axis and y-axis in the figure is usually along the ground or desktop in practical applications, and the vertical direction is the direction perpendicular to the horizontal plane (i.e. Figure 1 The thickness of spline 1 refers to the size of spline 1 in the horizontal direction (i.e., the x-axis or y-axis direction).

[0030] In the present disclosure, along the vertical direction, the thickness of the plurality of splines 1 may be increased or decreased in sequence. The widths of the plurality of splines 1 (ie, the dimensions in the vertical direction) may be the same or different, which may be achieved by designing the mold. Figure 2, which is a cross section of the sample along the vertical direction, it can be seen that in the vertical direction, the sample can have two splines 1 with different thicknesses, wherein the thickness of the upper spline 1 is smaller, and the thickness of the lower spline 1 is larger, and the two splines 1 have the same width. In other embodiments, there is no specific limitation on the number of splines 1, and the specific dimensions in the width and thickness directions.

[0031] In such Figure 1 In the specific embodiment shown, the spline 1 includes multiple straight sections 11 and multiple first curved sections 12 extending in the horizontal direction. The multiple straight sections 11 are arranged in parallel, and two adjacent straight sections 11 are connected by the first curved section 12, and the first curved section 12 is configured as a semicircular structure. The design of the multiple straight sections 11 and the multiple first curved sections 12 forms a folded spline 1. The lengths of the multiple straight sections 11 can be equal, and the distances between the multiple parallel straight sections 11 can also be equal. The multiple first curved sections 12 are semicircular structures with the same radius of curvature. Specifically, the length of the straight section 11 can be 250-350 mm, the distance between the two adjacent straight sections 11 can be 88-110 mm (i.e., the radius of curvature of the first curved section 12 is 44-55 mm), the number of the straight sections 11 can be 7-9, and the total length of the sample (i.e., the total extension distance from the starting point to the end point) can be 3500-4500 mm. In this way, the horizontal dimensions of the sample and the mold can be minimized, the cost can be reduced, and the casting molding process of the actual large high-pressure die casting in the ultra-long process can be accurately simulated. In other embodiments, any two adjacent straight portions 11 can be arranged at an angle, and the shape and specific turning angle of the first curved portion 12 can be designed as needed to simulate the flow performance of the die-casting material after flowing through the turning radius, and fully verify the flow filling property of the large high-pressure cast thin-walled parts.

[0032] like Figure 1 As shown, the sample has two free ends, one free end is the starting point A (i.e., the starting point) corresponding to the casting port, and the other free end is the end point B of the casting. The spline 1 may also include a transition portion 13, and the straight portion 11 located at one end (i.e., the starting point A) of the multiple straight portions 11 is connected to the transition portion 13 through a second curved portion 14. The second curved portion 13 may be constructed as an arc structure with a certain curvature, and the transition portion 13 may be constructed as a straight structure or a curved structure with a certain angle to the straight portion 11. By setting the transition portion 13 and the second curved portion 14, it is beneficial to maintain good fluidity of the die-casting material in the initial stage of casting, ensure that the flow and solidification characteristics of the die-casting material in the ultra-long process can be truly reflected in the simulation process of casting molding, and obtain highly reliable verification results.

[0033] The sample provided by the present disclosure can be a heat-treatment-free high-pressure die-cast aluminum alloy material, which can be used in the fields of automobile body hardware, battery pack thin-walled shell, etc. Using this sample for verification can minimize the mold size and reduce the dependence on large-scale casting equipment. At the same time, it can accurately simulate the casting molding process of actual large-scale high-pressure die-casting parts in an ultra-long process, and realize multi-faceted verification of material properties and casting processability.

[0034] In a second aspect of the present disclosure, a method for testing a die casting is provided, in which a die casting material is made into a test piece as described above for testing, and a reference is made to Figure 3 The method comprises the following steps S501-S505:

[0035] S501, obtaining property parameters of the die-casting material and performing mold flow analysis according to the property parameters to obtain a simulated filling result;

[0036] S502, performing die-casting molding on the die-casting material to obtain the sample piece as described above and the actual filling result of the sample piece, and comparing the actual filling result with the simulated filling result;

[0037] S503, sampling at least one preset sampling point on at least one sample strip of the sample piece to obtain at least one group of samples to be tested, wherein the samples to be tested include a first sample and a second sample from the same sample strip at the same preset sampling point;

[0038] S504, performing a performance test on the first sample to obtain a performance index of the first sample; and

[0039] S505 , performing metallographic testing on the second sample to obtain a microstructure index of the second sample, and comparing the microstructure index with the performance index.

[0040] In step S501, the property parameters of the die-casting material may include at least one of viscosity, thermal conductivity, specific heat and solidus temperature. The above property parameters can be obtained by detection using common methods and equipment in the art. For example, viscosity can be detected using a rheometer, and the viscosity values ​​at different temperatures and different shear rates can be obtained by multiple detections to improve the reliability of the verification results. Mold flow analysis based on property parameters can be performed using common analysis software in the art. In addition to the above property parameters, the input items of mold flow analysis can also include the structure of the mold and its material properties, die casting molding conditions and environmental conditions, etc. The obtained simulation filling results can include filling time and filling quality evaluation, shear rate distribution, pressure and temperature distribution and defect prediction, etc. In addition, when performing mold flow analysis, different filling speeds and mold temperatures can be set to track the temperature value and shear rate value of the die-casting material melt during the filling process, and then the corresponding viscosity value is calculated to achieve performance verification and optimization design of the material.

[0041] In step S502, the die-casting molding conditions may include: the filling time of the die-casting material is 80-160ms, the mold temperature is 50-250°C, the die-casting vacuum is 60-100bar, and the die-casting pressure is 20-70MPa. By comparing the actual filling result with the simulated filling result in step S501, the verification relationship between the property parameters (such as viscosity) of the die-casting material and the filling property can be obtained, which is helpful to optimize the process parameters to improve the quality of the die-casting product.

[0042] In step S503, the position of the preset sampling point can be designed as needed, for example, it can be set at the same position at a predetermined distance from the starting point A on at least one spline, specifically, it can be set at the straight portion 11 or the first curved portion 12. Further, the preset sampling points can be multiple and equally spaced and respectively set on multiple straight portions 11, for example, they can be at 500mm, 1000mm, 1500mm, 2000mm, 2500mm, 3000mm, 3500mm from the starting point A, so as to explore the flow performance and performance of the die-casting material after the same flow turning radius. The preset sampling point can have a certain area range, and a group of samples to be tested is obtained from the same preset sampling point of the same spline, and the group of samples to be tested is considered to have the same performance. Therefore, when sampling is performed on multiple splines at multiple preset sampling points, multiple groups of samples to be tested can be obtained to verify the performance of samples taken at the same position or different positions of splines with different thicknesses, and explore the influence of thickness and / or flow distance on the performance of the samples. In addition, multiple sampling can be performed at the same preset sampling point and the test result can be calculated by averaging to improve the reliability of the test result.

[0043] The size of the samples in each group of samples to be tested is consistent, and there is no special restriction on the specific size. The size of each sample can be calculated and designed according to the size of the spline and the number of samples to be intercepted. Specifically, each group of samples to be tested includes a first sample and a second sample, the first sample is used for the performance test in step S504, and the second sample is used for the metallographic test in step S505. In addition, each group of samples to be tested may also include a third sample, and the method may also include performing a self-riveting test on the third sample and recording the cracking condition of the third sample.

[0044] In step S504, the performance test may include at least one of a tensile mechanical performance test, a bending performance test, and a fatigue performance test. Among them, the tensile mechanical performance test can obtain the mechanical performance related indicators of the sample, such as yield strength, tensile strength, elongation, etc.; the bending performance test can obtain the indicators of the sample such as bending angle; the fatigue performance test can obtain the indicators of the sample such as SN curve. Thus, by comprehensively considering different performance indicators, multi-faceted verification of material properties and casting processability is achieved, providing data support for determining the optimal die-casting process parameters.

[0045] Furthermore, the tensile mechanical properties test can be a unidirectional tensile test. After the first sample is subjected to the tensile mechanical properties test, the method can also include: performing a fracture analysis on the first sample after it is broken in the unidirectional tensile test through a scanning electron microscope, focusing on analyzing the fracture where mechanical fluctuations occur, determining the defect type, and providing a basis for optimizing process parameters.

[0046] In step S505, by comparing the microstructure indicators with the performance indicators, it is helpful to deeply understand the influence of the microstructure of the material on the macroscopic performance, and then through corresponding data analysis, the verification relationship between performance and microstructure can be obtained, such as the relationship between strength and phase composition, the relationship between grain structure and fatigue life, the relationship between plasticity and grain size, etc., to achieve testing and verification of large-scale heat-treatment-free high-pressure die-casting aluminum alloy materials, and it is helpful to obtain possible paths to improve material performance.

[0047] The method provided by the present invention can accurately simulate the casting molding process of actual large-scale high-pressure die castings in an ultra-long process, realize multi-faceted verification of material properties and casting processability, and the testing process is time-saving, labor-saving, low-cost, and the verification results are highly reliable, which is conducive to a comprehensive evaluation of the performance of die-casting materials under different process conditions, and has important guiding significance for process optimization and material selection in the actual production process.

[0048] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0049] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0050] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A test piece for testing the performance of die-cast thin-walled parts, characterized in that: The sample piece includes a plurality of splines arranged adjacent to each other in a vertical direction, at least two of the plurality of splines have different thicknesses, and the thicknesses of the plurality of splines decrease in sequence from bottom to top in the vertical direction; The spline includes multiple straight sections and multiple first curved sections extending in the horizontal direction, the multiple straight sections are arranged in parallel and two adjacent straight sections are connected by the first curved section, the first curved section is configured as a semicircular structure, the distance between two adjacent straight sections is 88-110 mm, the length of the straight section is 250-350 mm, the number of the straight sections is 7-9, and the total length of the sample is 3500-4500 mm; The horizontal direction is a direction parallel to the horizontal plane, the vertical direction is a direction perpendicular to the horizontal plane, and the thickness is a dimension of the spline in the horizontal direction.

2. The sample according to claim 1, wherein: The spline also includes a transition portion, and the straight portion located at one end of the plurality of straight portions is connected to the transition portion through a second curved portion, the second curved portion is configured as an arc structure, and the transition portion is configured as a straight line or a curved structure.

3. A method for testing die castings, characterized in that: The method includes: Acquiring property parameters of the die-casting material and performing mold flow analysis according to the property parameters to obtain a simulated filling result; Die-casting the die-casting material to obtain the sample piece as claimed in claim 1 or 2 and the actual filling result of the sample piece, and comparing the actual filling result with the simulated filling result; Sampling at least one preset sampling point on at least one sample strip of the sample piece to obtain at least one group of samples to be tested, wherein the samples to be tested include a first sample and a second sample from the same sample strip at the same preset sampling point; Performing a performance test on the first sample to obtain a performance index of the first sample; Perform metallographic testing on the second sample to obtain a microstructure index of the second sample, and compare the microstructure index with the performance index.

4. The method according to claim 3, wherein: The property parameter includes at least one of viscosity, thermal conductivity, specific heat and solidus temperature.

5. The method according to claim 3, wherein: The die-casting molding conditions include: a filling time of the die-casting material of 80-160 ms, a mold temperature of 50-250° C., a die-casting vacuum of 60-100 bar, and a die-casting pressure of 20-70 MPa.

6. The method according to claim 3, wherein: The performance test includes at least one of a tensile mechanical performance test, a bending performance test and a fatigue performance test.

7. The method according to claim 3, wherein: The sample to be tested also includes a third sample from the same sample strip at the same preset sampling point. The method also includes performing a self-riveting test on the third sample and recording the cracking condition of the third sample.

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