CN110923438A - Circular torsion machining process for improving mechanical property of metal material - Google Patents
Circular torsion machining process for improving mechanical property of metal material Download PDFInfo
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Abstract
The invention discloses a circular torsion processing technology for improving mechanical properties of a metal material, and belongs to the technical field of metal material reinforcement. Specifically, small-angle cyclic reciprocating torsional deformation is applied to a metal bar, pipe or plate sample, and gradient-distributed shear plastic strain is generated from the surface to the inside of a metal material, so that gradient-distributed deformation microstructures such as dislocation and nanometer twin crystal are introduced, and an original coarse crystal structure is retained. Wherein the torsion angle amplitude is between 2 degrees and 30 degrees, and the cycle torsion frequency is between 2 and 200. Compared with a uniform coarse-grain structure with the same components, the yield strength of the metal material treated by the cyclic reciprocating torsion process is improved by more than 1.5 times, and the metal material has uniform plasticity equivalent to that of coarse grains. The microstructure with gradient distribution obtained in the original coarse crystal by the method has high strength and good plasticity matching.
Description
Technical Field
The invention relates to the technical field of metal material reinforcement, in particular to a cyclic torsion processing technology for improving the mechanical property of a metal material.
Background
The metal material has comprehensive mechanical and physical and chemical properties such as strength, plasticity, toughness and the like, is widely applied to almost all industrial fields such as aerospace, petrochemical industry, transportation and the like, and is an indispensable important material for human society. In recent years, with the development of society, resources are increasingly in shortage, energy consumption and environmental pollution are increasingly aggravated, which forces metal components and equipment to be continuously developed towards high performance, light weight, energy conservation and environmental protection, so that the service environment is more and more complicated, and the traditional structural metal materials with lower micro-strength and hardness are difficult to be applied under the harsh working conditions.
Over the last century, the core problem of material research has been how to improve the strength of materials. To date, a series of techniques for reinforcing a metal material by regulating the composition, microstructure, and internal defects of the material have been developed, including solid solution reinforcement, deformation reinforcement, dispersion reinforcement, and the like. Although these strengthening techniques can improve the strength of the material to some extent, they tend to deteriorate the plasticity and toughness and reduce the work hardening capacity, thereby severely restricting the development of high-strength metal materials.
In the last 80 s, the german scientist Gleiter taught the concept of nanostructured materials, i.e., the reduction of structural units of materials (e.g., grain size in polycrystalline materials) to the nanometer scale, which were characterized by a significant structural feature containing a large number of grain boundaries or other interfaces. A large number of research results show that the micron grain size of the metal material can be uniformly refined to the nanometer scale (namely the nanometer structure material) by utilizing severe plastic deformation technologies such as equal channel angular extrusion, high-pressure torsion and the like. The strength of the obtained homogeneous nanostructured material is several times or even 10 times that of the coarse crystalline structure, but its homogeneous plasticity is almost 0. This is mainly due to the fact that the high density of defects in the homogeneous nanostructured material itself severely inhibits the propagation of dislocations and the occurrence of strain localization, resulting in a loss of work hardening capability. Therefore, how to achieve work hardening of high-strength metal materials has become an important scientific problem to be solved urgently in the current development of high-performance metal materials.
In recent years, the concept of microstructure gradient is gradually applied to engineering material design, wherein a gradient nanocrystalline structure (i.e. a continuous increase of the grain size from nanometer scale to micrometer scale, GNG) is a typical construction structure for optimizing the comprehensive performance of metal materials. For example, GNG Cu prepared using surface mechanical milling techniques not only has higher strength, but also tensile plasticity comparable to core macrocrystals, mainly due to the limitations of the macrocrystalline matrix on strain localization of the GNG surface layer and the unique mechanically driven grain growth mechanism. However, due to the limited thickness of the surface nanocrystalline layer in the gradient nanocrystalline structure obtained by the prior art and its intrinsic mechanical instability, further improvement of the strength thereof is limited. More importantly, several surface deformation processes developed at present, such as surface mechanical milling and surface rolling, use complicated equipment, require milling or rolling of metal surfaces with cemented carbide tips having specific geometric dimensions, are demanding in process technology, have low treatment efficiency, and severely limit their wide application in industry.
Disclosure of Invention
The invention aims to provide a cyclic torsion processing technology for improving the mechanical property of a metal material, which has simple and efficient process, can obviously improve the strength of the metal material and does not obviously reduce the uniform plasticity and the fracture elongation of the metal material.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a cyclic torsion processing technology for improving the mechanical property of a metal material is characterized in that a metal material sample is subjected to small-angle cyclic reciprocating torsion deformation processing, so that dislocation and nanometer twin deformation microstructures in gradient distribution are introduced into an original coarse crystal structure of the metal material, and the mechanical property of the metal material is improved.
The metal material is a bar or a pipe; the axial length is more than 10mm, and the diameter is more than 1 mm.
The small-angle cyclic torsional deformation treatment is as follows: one end of the bar or the pipe is fixed, force is applied to enable the other end of the bar or the pipe to rotate around the central axis in a reciprocating mode, and the cycle of the reciprocating rotation is one cycle of the twisting.
The one-time reciprocating rotation means that the other end of the bar or the pipe rotates around the central axis, the bar or the pipe rotates clockwise by a rotation angle theta from the initial position and then returns to the initial position by a counterclockwise rotation angle theta, and the bar or the pipe completes one-time reciprocating rotation, namely one cycle of twisting; and then the bar or the pipe is subjected to the next reciprocating rotation process from the initial position, and the process is repeatedly circulated until the required cycle twisting cycle is reached. And theta is taken as a fixed value in the process of each cycle of reciprocating torsional deformation.
The angle theta of each rotation of the bar or the pipe is the amplitude of the torsion angle, the amplitude of the torsion angle is 2-30 degrees, the torsion rate is 100-10000 degrees/min, and the cycle torsion frequency is 2-500.
The deformation microstructures such as dislocation, nanometer twin crystal and the like in gradient distribution are introduced from the surface to the inside of the metal material through the cyclic reciprocating torsional deformation process, and the crude crystal structure of the original state is reserved. In the direction vertical to the surface of the metal material, the microhardness shows continuous gradient change from high to low from outside to inside; compared with the uniform coarse-grain structure (with the same components) of the original metal material before processing, the yield strength of the metal material after the cyclic reciprocating torsion process treatment is improved by more than 1.5 times, uniform plasticity and fracture elongation which are equivalent to the original structure are maintained, and the metal material has good strength and plasticity matching.
The invention has the following advantages:
1. the process scheme of the invention is that the characteristics of the traditional fatigue test cyclic deformation are fully used for reference, the cyclic torsional deformation treatment is carried out on the metal bar and the pipe under a smaller torsional angle (less than 30 degrees) by utilizing the torsional equipment, and the shearing plastic strain with gradient distribution can be generated from the surface to the inside of the metal material. Compared with large-angle (>30 ℃) torsional deformation, the single small-angle cyclic torsional strain and stress are small, and the macroscopic shape and the surface appearance of the sample are not obviously changed; but by increasing the twisting frequency, the twisting strain can be increased, so that high-density dislocation, nanometer twin crystal and other microstructures are introduced, the gradient distribution deformation microstructure is introduced, and the original state structure is reserved by regulating and controlling the twisting frequency.
2. Different from the tiny nanocrystalline or nano twin crystal structure obtained on the surface of a sample by the traditional surface mechanical deformation process, the invention introduces deformation microstructures such as dislocation, nano twin crystal and the like distributed in a gradient manner from the surface to the inside of a metal material through the cyclic reciprocating torsional plastic deformation, but retains the original coarse crystal structure, so that the metal material treated by the cyclic reciprocating torsional process has uniform plasticity and fracture elongation which are equivalent to the original structure, and simultaneously has higher yield strength and tensile strength and good strength and plastic matching.
3. The traditional severe plastic deformation and surface mechanical deformation process uses complicated equipment, for example, the surface mechanical grinding technology needs to use a cemented carbide tool bit with special geometric dimensions to grind or roll the metal surface, the process technology is harsh, the treatment efficiency is low, and the treatment time of one sample is about 2 hours or more. In addition, since the surface plastic deformation technology mainly refines the structure by grinding or rolling the sample surface through the tool bit to generate plastic deformation, the sample diameter is often required to be large (at least larger than 4mm) in order to prevent the sample from bending deformation during the processing. The invention has simple process, low requirement on equipment and high treatment efficiency, and the time for treating one sample is about tens of seconds to several minutes. Due to the process characteristics, the technology has small size limitation on the processed samples, can process bar and pipe samples with different sizes to meet the service requirements of workpieces, has important significance on light weight of mechanical equipment, energy conservation and emission reduction, and has wide application prospect in industry.
Drawings
FIG. 1 is a schematic view of the cyclic torsion process of the present invention.
FIG. 2 is a scanning electron micrograph of a surface microstructure obtained after a 304 stainless steel bar sample is twisted for 200 weeks under a condition of a twist angle amplitude of 5 ° in example 1; wherein: the lower three figures (a), (b) and (c) are enlarged views of the three positions a, b and c in the upper figure, respectively.
FIG. 3 is a scanning electron micrograph of a surface microstructure obtained after a 304 stainless steel bar sample is twisted for 200 weeks under a condition of a twist angle amplitude of 15 ° in example 2; wherein: the lower three figures (a), (b) and (c) are enlarged views of the three positions a, b and c in the upper figure, respectively.
Fig. 4 is a phase distribution diagram of a surface microstructure obtained after twisting a 304 stainless steel rod sample for 200 cycles under a torsion angle amplitude of 15 ° in example 2.
FIG. 5 is the XRD results of the skin, subsurface and core portions after twisting a 304 stainless steel bar sample for 200 weeks under the conditions of twisting angle amplitudes of 5 ° and 15 ° in examples 1 and 2; wherein: (a) comparative example 1; (b) example 1.
FIG. 6 is a transmission electron micrograph and a microstructure size statistical chart of a surface microstructure obtained after a 304 stainless steel bar sample is twisted for 200 weeks under a condition of a torsion angle amplitude of 15 degrees in example 2; wherein: (a) a core microstructure; (b) mean dislocation wall and dislocation cell size; (c) twinning in the crystal grains; (d) average twin slice thickness.
Fig. 7 is a graph of the microhardness as a function of depth from the surface of 304 stainless steel samples treated by the cyclic torsional deformation process in examples 1 and 2.
Fig. 8 is a uniaxial tensile engineering stress-strain curve of a 304 stainless steel sample treated by a cyclic torsional deformation process in example 1 and example 2.
FIG. 9 is the distribution of the micro-hardness of the Al0.1CoCrFeNi high-entropy alloy sample after the treatment of the cyclic torsional deformation process along with the depth from the surface in example 3.
FIG. 10 is the uniaxial tensile engineering stress-strain curve of the Al0.1CoCrFeNi high-entropy alloy sample after being treated by the cyclic torsional deformation process in comparative examples 1-2 and example 3.
Detailed Description
The present invention is described in detail below by way of examples.
The invention provides a cyclic torsion processing technology for improving mechanical properties of a metal material, which is characterized in that small-angle cyclic reciprocating torsion deformation processing is applied to a metal sample, so that deformation microstructures such as dislocation, nanometer twin crystal and the like in gradient distribution are introduced into the metal material, and a coarse crystal structure in an original state is reserved. Wherein the torsional amplitude is between 2 and 30 degrees and the cycle torsional frequency is between 2 and 200.
In the following embodiments, the device for applying a torsional force to a metal material sample (a bar or a pipe) is only required to be capable of fixing one end of the sample and applying a force to the other end of the sample to rotate around the central axis of the device, and is not limited to a specific structure (e.g., a fatigue testing machine, a pipe torsional testing machine, etc.).
The small-angle circulating torsional deformation treatment in the invention is as follows: one end of the bar or the pipe is fixed, force is applied to enable the other end of the bar or the pipe to rotate around the central axis in a reciprocating mode, and the cycle of the reciprocating rotation is one cycle of the twisting.
The one-time reciprocating rotation means that the other end of the bar or the pipe rotates around a central axis, the bar or the pipe rotates clockwise by a rotation angle theta (torsion angle amplitude) from an initial position and then returns to the initial position by the counterclockwise rotation angle theta, and the bar or the pipe completes one-time reciprocating rotation, namely one-cycle torsion cycle; and then the bar or the pipe is subjected to the next reciprocating rotation process from the initial position, and the process is repeatedly circulated until the required cycle twisting cycle is reached. And theta is taken as a fixed value in the process of each cycle of reciprocating torsional deformation.
Example 1:
in this embodiment, a small-angle cyclic reciprocating torsional deformation process is performed on a 304 austenitic stainless steel bar.
The coarse grain 304 austenitic stainless steel sample was fixed at one end and subjected to cyclic torsional deformation treatment (as shown in fig. 1) at the other end to obtain a gradient structure 304#1 sample.
The process parameters for the gradient structure 304#1 sample were selected as: the diameter of the 304 austenitic stainless steel is 6mm, the amplitude of the torsion angle is 5 degrees, the torsion rate is 5000 degrees/min, the torsion frequency is 200 weeks, the torsion time is about 14 seconds, and the torsion temperature is 25 degrees at room temperature.
The degree of deformation in the material shows a monotonically decreasing trend with increasing depth from the surface, resulting in a graded distribution of deformed microstructures (fig. 2). But the microstructure is still austenitic with no martensite phase formed (fig. 5 (a)). The microhardness of the 304#1 sample of the gradient structure is gradually reduced from 3.2GPa to 2.0GPa along with the increase of the depth from the surface of the material, and the sample has the characteristic of gradient change and is obviously higher than that of a coarse-grained 304 austenitic stainless steel sample (1.8GPa), as shown in FIG. 7.
In this example, a surface gradient structure 304#1 sample was subjected to a uniaxial tensile test at room temperature, and the engineering stress-strain curve is shown in fig. 8, where the yield strength in uniaxial tension is 306MPa, the tensile strength is 606MPa, and the yield strength is about 1.5 and 1.05 times of the original coarse-grained structure; the uniform elongation is 66.8%, and the fracture elongation is 87.6%, which is equivalent to the coarse-grain structure.
Example 2:
in this example, a coarse grain 304 austenitic stainless steel # 2 sample was subjected to a cyclic torsional deformation treatment to obtain a gradient structure 304#2 sample.
The difference from example 1 is that the process parameters of the 304#2 sample of the gradient structure are selected such that the diameter of the 304 austenitic stainless steel is 6mm, the amplitude of the torsion angle is 15 degrees, the torsion rate is 5000 DEG/min, the number of the torsion cycles is 200 cycles, the torsion time is about 6min, and the torsion temperature is 25 degrees at room temperature.
The degree of deformation in the material shows a monotonically decreasing trend with increasing depth from the surface, resulting in a graded distribution of deformed microstructures (fig. 2). The outermost surface is still a coarse crystal structure (figure 4), high-density dislocation, a large number of dislocation cells and dislocation walls are distributed in the coarse crystal (figure 6(a)), and the average dislocation wall and cell size is 250nm (figure 6 (b)); in addition, a high density of nano-scale twin bundles was found inside some of the grains (fig. 3 and 6(c)), and the average twin lamella thickness was about 16nm (fig. 6 (d)). At the core of the sample, a large number of dislocation cells and dislocation wall structures were also seen, with the average dislocation wall and cell size being 850 nm. The EBSD results show that the microstructure of the sample is still predominantly austenitic with very little martensite phase formed only at the very surface (fig. 5(b)), and calculations show that the volume fraction of martensite is about 7%.
The microhardness of the sample 304#2 with the gradient structure is still characterized by the gradient change along with the increase of the depth from the surface, and the hardness of the outermost layer is about 4.2GPa, which is obviously higher than that of the coarse-grained 304 austenitic stainless steel sample (1.8GPa), as shown in FIG. 7.
In this example, a surface gradient structure 304#2 sample was subjected to a uniaxial tensile test at room temperature, and the engineering stress-strain curve is shown in fig. 8, where the yield strength in uniaxial tension is 442MPa, the tensile strength is 661MPa, and is about 2.1 and 1.1 times of the coarse-grained structure; the uniform elongation was 53.7% and the elongation at break was 78.5%.
Comparative example 1:
this example is for coarseCrystalline Al0.1And applying cyclic torsional deformation treatment to the CoCrFeNi high-entropy alloy sample.
The technological parameter of the high-entropy alloy # 1 sample with the gradient structure is selected from Al0.1The diameter of a CoCrFeNi high-entropy alloy sample is 4.5mm, the amplitude of a torsion angle is 4 degrees, the torsion rate is 120 degrees/s, the torsion frequency is 200 weeks, the torsion time is 14 seconds, and the torsion temperature is 25 degrees at room temperature.
In this example, the gradient structure high entropy alloy # 1 was subjected to uniaxial tensile test at room temperature, and the engineering stress-strain curve is shown in fig. 10, and its uniaxial tensile yield strength is 291MPa, tensile strength is 488MPa, which is about 2.1 and 1.1 times of that of the coarse grain structure, uniform elongation is 50.5%, and elongation at break is 70.6%, which is equivalent to that of the coarse grain structure.
Example 3:
this example is for coarse-grained Al0.1And applying cyclic torsional deformation treatment to the CoCrFeNi high-entropy alloy sample.
The technological parameter of the high-entropy alloy # 2 sample with the gradient structure is selected from Al0.1The diameter of a CoCrFeNi high-entropy alloy sample is 4.5mm, the amplitude of a torsion angle is 15 degrees, the torsion rate is 1800 degrees/min, the torsion frequency is 200 weeks, the torsion time is about 3 minutes, and the torsion temperature is 25 degrees at room temperature.
Along with the increase of the depth from the surface of the material, the microhardness of the high-entropy alloy # 2 sample with the gradient structure is gradually reduced from 4.0GPa to 2.4GPa, and the characteristic of gradient change is obviously higher than that of a coarse-grain high-entropy alloy sample (1.7GPa), as shown in FIG. 9.
In this example, a unidirectional tensile test was performed on a gradient-structure high-entropy alloy # 2 sample at room temperature, and an engineering stress-strain curve is shown in fig. 10, in which the unidirectional tensile yield strength was 427MPa, the tensile strength was 556MPa, which was about 3.1 and 1.2 times that of the coarse-grain structure, the uniform elongation was 42.8%, and the elongation at break was 57.5%, which was slightly lower than that of the coarse-grain structure.
Comparative example 2:
the ordinary annealed coarse grain 304 austenitic stainless steel (grain size about 100 μm) was stretched at room temperature, and had a yield strength of 210MPa, a tensile strength of 581MPa, a uniform elongation of 70.3%, and an elongation at break of 97.1%, as indicated by the dotted line in FIG. 8. Coarse in annealed stateCrystalline Al0.1The CoCrFeNi high-entropy alloy sample (the grain size is about 600 mu m) is stretched at room temperature, and has the yield strength of 138MPa, the tensile strength of 545MPa, the uniform elongation of 63.0 percent and the elongation at break of 80.5 percent, as shown by a dotted line in FIG. 10. Therefore, the macrocrystalline structure has low yield strength and tensile strength, although it has good tensile plasticity.
Comparative example 3:
mallick et al, an indian scientist, produced a sample of a severely deformed structure 304 using a low temperature (-196 degrees) rolling technique and having a volume fraction of martensite of 44%. Tensile testing indicated that the 304 stainless steel sample had a yield strength as high as 1400MPa, but a uniform elongation of only 9%.
Comparative example 4:
the CG 304 austenitic stainless steel sample is subjected to dynamic plastic deformation treatment by the aid of liquid nitrogen temperature by Haohyu et al, a metal research institute of Chinese academy of sciences, and the 304 stainless steel with the mixed structure consisting of martensite and residual austenite is obtained. Wherein the volume fraction of martensite is 87%, and the retained austenite is mainly composed of nanocrystals with grain size less than 100 nm. The yield strength of this sample was as high as 1250MPa but there was almost no tensile plasticity (< 1%). In order to inhibit the generation of martensite in the deformation process, a nano-twin mixed structure 304 austenitic stainless steel with nano-twin mixed structure samples containing nano-twin crystal austenite grains with different volume fractions is prepared by a temperature rise (150 ℃) dynamic plastic deformation technology. Wherein the average twin lamella thickness of the nano twin crystal is 10nm, the volume fraction is about 58%, and the dislocation structure size is about several hundred nanometers. The sample strength was as high as 1135MPa but again there was no uniform tensile plasticity (< 1%). Therefore, poor plasticity of homogeneous nanostructured metals severely limits their practical applications.
Comparative example 5:
the Weiyujie (see application No. 201310206344.3) of the mechanics research institute of Chinese academy of sciences applies single large-angle (270 ℃) torsional deformation to a cold-rolled 304 austenitic stainless steel sample to obtain a structure with high-density martensite and deformation twin crystals distributed in a gradient manner from the surface to the core of the sample. The tensile test shows that the yield strength of the sample after large-angle torsional deformation is 660MPa, which is 2 times of that of the untreated cold-rolled 304 austenitic stainless steel sample (310 MPa), the uniform strain is about 30 percent, and the plasticity of the sample after the treatment by the process is obviously lower.
The result shows that the invention introduces the deformation microstructures such as dislocation, nanometer twin crystal and the like in gradient distribution by applying small-angle cyclic reciprocating torsional deformation to the metal sample, and retains the crude crystal structure in the original state. The yield strength of the metal material treated by the cyclic reciprocating torsion process is improved by more than 1.5 times, the uniform plasticity and the fracture elongation rate which are equivalent to those of the original structure are kept, and the metal material has good strength and plasticity matching.
Claims (8)
1. A circular torsion processing technology for improving mechanical properties of metal materials is characterized in that: the process introduces dislocation and nanometer twin crystal deformation microstructures in gradient distribution into the original coarse crystal structure of the metal material by carrying out small-angle circular reciprocating torsional deformation treatment on a metal material sample, thereby improving the mechanical property of the metal material.
2. The cyclic torsion processing technology for improving the mechanical property of the metal material according to claim 1, wherein: the metal material is a bar or a pipe; the axial length is more than 10mm, and the diameter is more than 1 mm.
3. The cyclic torsion processing technology for improving the mechanical property of the metal material according to claim 2, wherein: the small-angle cyclic torsional deformation treatment is as follows: one end of the bar or the pipe is fixed, force is applied to enable the other end of the bar or the pipe to rotate around the central axis in a reciprocating mode, and the cycle of the reciprocating rotation is one cycle of the twisting.
4. The cyclic torsion processing technology for improving the mechanical property of the metal material according to claim 3, wherein: the one-time reciprocating rotation means that the other end of the bar or the pipe rotates around the central axis, the bar or the pipe rotates clockwise by a rotation angle theta from the initial position and then returns to the initial position by a counterclockwise rotation angle theta, and the bar or the pipe completes one-time reciprocating rotation, namely one cycle of twisting; and then the bar or the pipe is subjected to the next reciprocating rotation process from the initial position, and the process is repeatedly circulated until the required cycle twisting cycle is reached.
5. The cyclic torsion processing technology for improving the mechanical property of the metal material according to claim 4, wherein: the angle theta of each rotation of the bar or the pipe is the amplitude of the torsion angle, the amplitude of the torsion angle is 2-30 degrees, the torsion rate is 100-10000 degrees/min, and the cycle torsion frequency is 2-500.
6. The cyclic torsion processing technology for improving the mechanical property of the metal material according to claim 4, wherein: and theta is taken as a fixed value in the process of each cycle of reciprocating torsional deformation.
7. The cyclic torsion processing technology for improving the mechanical property of the metal material according to claim 4, wherein: the deformation microstructures such as dislocation, nanometer twin crystal and the like in gradient distribution are introduced from the surface to the inside of the metal material through the cyclic reciprocating torsional deformation process, and the crude crystal structure of the original state is reserved.
8. The cyclic torsion processing technology for improving the mechanical property of the metal material according to claim 7, wherein: in the direction vertical to the surface of the metal material, the microhardness shows continuous gradient change from high to low from outside to inside; compared with the uniform coarse-grain structure of the original metal material before processing, the yield strength of the metal material after the treatment of the cyclic reciprocating torsion process is improved by more than 1.5 times, the uniform plasticity and the fracture elongation rate equivalent to the original structure are kept, and the metal material has good strength and plasticity matching.
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| CN114411072A (en) * | 2021-12-28 | 2022-04-29 | 中南大学 | Aluminum alloy material with gradient structure and preparation method thereof |
| CN114749506A (en) * | 2022-03-23 | 2022-07-15 | 南京理工大学 | Gradient structure bar and preparation device and method thereof |
| CN114749506B (en) * | 2022-03-23 | 2024-02-13 | 南京理工大学 | Gradient structure bar and preparation device and method thereof |
| CN117058220A (en) * | 2023-10-11 | 2023-11-14 | 天津施格自动化科技有限公司 | Fitting algorithm for measuring diameter and central point of metal rod by using distance sensor |
| CN117058220B (en) * | 2023-10-11 | 2024-01-26 | 天津施格自动化科技有限公司 | Fitting algorithm for measuring diameter and central point of metal rod by using distance sensor |
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