CA3086808C - Method and device for predicting residual stress of metal plate based on measuring of residual stress release warpage - Google Patents
Method and device for predicting residual stress of metal plate based on measuring of residual stress release warpage Download PDFInfo
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- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
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Abstract
A method for predicting residual stress of a metal plate based on measuring of residual stress release warpage, adopting one of an X-ray method, a blind hole method, an ultrasonic method, a crack flexibility method or a finite element analysis method to measure residual stress of plates with different thicknesses; cutting a sample by a non-contact machining method, releasing residual stress to cause warpage of the plate, and measuring warpage by a displacement sensor to obtain a relationship between the residual stress and the warpage of the plates with different typical thicknesses; obtaining a quadratic equation: y=ax2+bx+c, wherein x is residual stress, y is warpage, and a, b and care fitting coefficients; measuring, on the basis of established functional relationship between the residual stress and the warpage, the warpage y under a specific linear cutting percentage, and calculating the residual stress according A device is also disclosed.
Description
Method and Device for Predicting Residual Stress of Metal Plate Based on Measuring of Residual Stress Release Warpage Technical Field The disclosure relates to a method for predicting residual stress of a metal plate based on measuring of residual stress release warpage and a device for measuring residual stress release warpage of the metal plate.
Background Art Aluminum alloy thick plates are widely used in aerospace and other large equipment.
In order to improve the mechanical properties of the plates during manufacture of aeronautical aluminum alloy plates, the processes of solution treatment, quenching and aging treatment are usually used. In the quenching process, due to the fact that the central portion is cooled slower than the surface, the surface of the aluminum alloy thick plate is subjected to compressive stress after quenching, and the central portion is subjected to tensile stress. The existence of residual stress makes the aluminum alloy thick plate deform in the process of machining aeronautical parts.
Although the residual stress can be reduced by pre-stretching treatment after quenching, the dimensional accuracy of aeronautical parts is required to be high, and the requirement for controlling the residual stress of the aluminum alloy thick plate is very strict.
Large residual stress easily causes the dimensional accuracy of parts to be unable to meet the requirements. Only by controlling the residual stress within a certain range of values, can the deformation in the machining process of aluminum alloy thick plate be reduced, and qualified parts can be obtained. The detection of residual stress of aluminum alloy thick plate is the premise to ensure the machining of aeronautical parts to meet the deformation requirements.
7050, 7075 and 7085 aluminum alloy thick plates are widely applied to large-scale equipment such as aerospace equipment due to high specific strength and excellent mechanical properties. In order to improve the mechanical properties of the plates Date Recue/Date Received 2020-06-23 during manufacturing of aluminum alloy thick plates, solution quenching and aging treatment are usually used. However, in the process of solution quenching, the surface and the central portion of the thick plate are not uniformly cooled, so that the aluminum alloy thick plate has very high residual stress. Since the central portion is cooled more slowly than the surface, the surface after final quenching is subjected to compressive stress, while the central portion is subjected tensile stress, and the residual stress exists. The aluminum alloy thick plate is deformed in the process of machining the aluminum alloy thick plate into aeronautical parts, so that deformation failure of the parts is caused. In order to reduce the residual stress of the aluminum alloy thick plate, the pre-stretching treatment is carried out after solution quenching.
The plastic stretching generated by the pre-stretching process will release the residual stress partially, and the residual stress is controlled within a certain value range, so that the deformation generated in the machining process of the aluminum alloy thick plates can be reduced, and qualified parts can be manufactured.
However, the existing residual stress testing equipment is expensive in manufacturing cost and harsh in testing environment requirements, and is not suitable for detecting the residual stress of aluminum alloy thick plates in industrial production, especially aluminum alloy thick plates such as 7050, 7075, 7085 and the like in a quenching state, a pre-stretching state and an aging state. Therefore, there is a need for a low-cost and high-precision testing method and special equipment for residual stress in the industrial production process of aluminum alloy thick plates.
Summary of the Disclosure In order to solve the above technical problems: the disclosure provides a method and a device for predicting residual stress of a metal plate based on measuring of residual stress release warpage, which are suitable for effective characterization of residual stress in industrial production of aeronautical aluminum alloy thick plates.
The device for measuring the residual stress release deformation amount of the thick metal plate is special equipment for detecting the linear cutting deformation measurement of
Background Art Aluminum alloy thick plates are widely used in aerospace and other large equipment.
In order to improve the mechanical properties of the plates during manufacture of aeronautical aluminum alloy plates, the processes of solution treatment, quenching and aging treatment are usually used. In the quenching process, due to the fact that the central portion is cooled slower than the surface, the surface of the aluminum alloy thick plate is subjected to compressive stress after quenching, and the central portion is subjected to tensile stress. The existence of residual stress makes the aluminum alloy thick plate deform in the process of machining aeronautical parts.
Although the residual stress can be reduced by pre-stretching treatment after quenching, the dimensional accuracy of aeronautical parts is required to be high, and the requirement for controlling the residual stress of the aluminum alloy thick plate is very strict.
Large residual stress easily causes the dimensional accuracy of parts to be unable to meet the requirements. Only by controlling the residual stress within a certain range of values, can the deformation in the machining process of aluminum alloy thick plate be reduced, and qualified parts can be obtained. The detection of residual stress of aluminum alloy thick plate is the premise to ensure the machining of aeronautical parts to meet the deformation requirements.
7050, 7075 and 7085 aluminum alloy thick plates are widely applied to large-scale equipment such as aerospace equipment due to high specific strength and excellent mechanical properties. In order to improve the mechanical properties of the plates Date Recue/Date Received 2020-06-23 during manufacturing of aluminum alloy thick plates, solution quenching and aging treatment are usually used. However, in the process of solution quenching, the surface and the central portion of the thick plate are not uniformly cooled, so that the aluminum alloy thick plate has very high residual stress. Since the central portion is cooled more slowly than the surface, the surface after final quenching is subjected to compressive stress, while the central portion is subjected tensile stress, and the residual stress exists. The aluminum alloy thick plate is deformed in the process of machining the aluminum alloy thick plate into aeronautical parts, so that deformation failure of the parts is caused. In order to reduce the residual stress of the aluminum alloy thick plate, the pre-stretching treatment is carried out after solution quenching.
The plastic stretching generated by the pre-stretching process will release the residual stress partially, and the residual stress is controlled within a certain value range, so that the deformation generated in the machining process of the aluminum alloy thick plates can be reduced, and qualified parts can be manufactured.
However, the existing residual stress testing equipment is expensive in manufacturing cost and harsh in testing environment requirements, and is not suitable for detecting the residual stress of aluminum alloy thick plates in industrial production, especially aluminum alloy thick plates such as 7050, 7075, 7085 and the like in a quenching state, a pre-stretching state and an aging state. Therefore, there is a need for a low-cost and high-precision testing method and special equipment for residual stress in the industrial production process of aluminum alloy thick plates.
Summary of the Disclosure In order to solve the above technical problems: the disclosure provides a method and a device for predicting residual stress of a metal plate based on measuring of residual stress release warpage, which are suitable for effective characterization of residual stress in industrial production of aeronautical aluminum alloy thick plates.
The device for measuring the residual stress release deformation amount of the thick metal plate is special equipment for detecting the linear cutting deformation measurement of
2 Date Recue/Date Received 2020-06-23 aluminum alloy thick plates such as 7050, 7075, 7085 and the like in a quenching state, a pre-stretching state and an aging state so as to obtain the residual stress level of the aluminum alloy plate.
The disclosure is realized by the following technical solution:
A method for predicting residual stress of a metal plate based on residual stress release warpage, comprising:
(1) adopting one of an X-ray method, a blind hole method, an ultrasonic method, a crack flexibility method or a finite element analysis method to test residual stress of plates with different thicknesses;
(2) cutting a sample by a machining method along a plate thickness direction, releasing residual stress to cause warpage of the plate, and testing warpage by a displacement sensor to obtain a relationship between the residual stress and the warpage of the plates with different thicknesses; obtaining, by fitting a curve, a quadratic equation: y=ax2+bx+c, wherein x is residual stress, y is warpage, and a, b and c are fitting coefficients;
The disclosure is realized by the following technical solution:
A method for predicting residual stress of a metal plate based on residual stress release warpage, comprising:
(1) adopting one of an X-ray method, a blind hole method, an ultrasonic method, a crack flexibility method or a finite element analysis method to test residual stress of plates with different thicknesses;
(2) cutting a sample by a machining method along a plate thickness direction, releasing residual stress to cause warpage of the plate, and testing warpage by a displacement sensor to obtain a relationship between the residual stress and the warpage of the plates with different thicknesses; obtaining, by fitting a curve, a quadratic equation: y=ax2+bx+c, wherein x is residual stress, y is warpage, and a, b and c are fitting coefficients;
(3) testing, upon cutting the metal plate on the basis of established functional relationship between the residual stress and the warpage, the warpage y under a specific linear cutting percentage, and calculating the residual stress according to a ¨b 4b2 ¨ 4a (c ¨ y) formula x ¨ ______________ .
2a According to the method, in step (2) the machining method is preferably a linear cutting method.
According to the method, in step (2), the sample is cut by fixing one end of the metal plate, a length of a fixed portion being less than 1/2 of a length of the sample, a cutting position being preferably selected at 1/2 of the length of the sample, and the Date Recue/Date Received 2020-06-23 cutting being performed along the plate thickness direction.
According to the method, in step (2) the warpage is measured at an end remote from a clamping position.
According to the method, in step (3) the specific linear cutting percentage is a linear cutting percentage controlled at a position where the warpage tends to be gentle.
According to the method, in step (3) a cutting depth is 62.5-75% of the plate thickness, then it is recommended that the cutting depth is 75-95% of the plate thickness, and then it is recommended that the cutting depth is 50-62.5% of the plate thickness, and finally it is recommended that the cutting depth is 30-50% of the plate thickness.
According to the method, predicted residual stress is the residual stress of the metal plate.
A device for measuring residual stress release deformation amount of a thick metal plate, comprising a clamping apparatus, wherein the clamping apparatus comprises a base, a fixing rod, a displacement testing seat and a displacement testing means; the base comprising a first base plate, two vertical baffles, a connecting plate and a pressing plate, both ends of the first base plate being fixedly connected with one vertical baffle respectively, bolt holes being formed in the two vertical baffles, one side edge of the first base plate being fixedly connected with one end of the connecting plate to form a T shape, and the pressing plate being positioned above the two vertical baffles, the pressing plate being provided with through holes corresponding to the bolt holes of the two vertical baffles in position, the pressing plate being connected with the two vertical baffles through bolts; a lower end of the fixing rod being fixedly connected with the other end of the connecting plate;
one end of the displacement testing seat being sleeved outside the fixing rod, and the other end of the displacement testing seat being connected with a lower end of a dial gauge.
According to the device, the device further comprises a deformation testing platform
2a According to the method, in step (2) the machining method is preferably a linear cutting method.
According to the method, in step (2), the sample is cut by fixing one end of the metal plate, a length of a fixed portion being less than 1/2 of a length of the sample, a cutting position being preferably selected at 1/2 of the length of the sample, and the Date Recue/Date Received 2020-06-23 cutting being performed along the plate thickness direction.
According to the method, in step (2) the warpage is measured at an end remote from a clamping position.
According to the method, in step (3) the specific linear cutting percentage is a linear cutting percentage controlled at a position where the warpage tends to be gentle.
According to the method, in step (3) a cutting depth is 62.5-75% of the plate thickness, then it is recommended that the cutting depth is 75-95% of the plate thickness, and then it is recommended that the cutting depth is 50-62.5% of the plate thickness, and finally it is recommended that the cutting depth is 30-50% of the plate thickness.
According to the method, predicted residual stress is the residual stress of the metal plate.
A device for measuring residual stress release deformation amount of a thick metal plate, comprising a clamping apparatus, wherein the clamping apparatus comprises a base, a fixing rod, a displacement testing seat and a displacement testing means; the base comprising a first base plate, two vertical baffles, a connecting plate and a pressing plate, both ends of the first base plate being fixedly connected with one vertical baffle respectively, bolt holes being formed in the two vertical baffles, one side edge of the first base plate being fixedly connected with one end of the connecting plate to form a T shape, and the pressing plate being positioned above the two vertical baffles, the pressing plate being provided with through holes corresponding to the bolt holes of the two vertical baffles in position, the pressing plate being connected with the two vertical baffles through bolts; a lower end of the fixing rod being fixedly connected with the other end of the connecting plate;
one end of the displacement testing seat being sleeved outside the fixing rod, and the other end of the displacement testing seat being connected with a lower end of a dial gauge.
According to the device, the device further comprises a deformation testing platform
4 Date Recue/Date Received 2020-06-23 including a second base plate, a fixing plate, a first clamping block and a second clamping block; a lower end of the fixing plate being fixedly connected with one end of the second base plate, a connecting hole being formed in a plate surface of the fixing plate; one end of the first clamping block being fixedly connected with one end of the plate surface of the fixing plate, a lower end of the first clamping block being fixedly connected with the second base plate; the second clamping block being opposite to the first clamping block, one end of the second clamping block being provided with a bolt hole corresponding to the connecting hole of the fixing plate in position, one end of the second clamping block provided with the bolt hole being connected with the plate surface of the fixing plate through a bolt, a lower end of the second clamping block being fixedly connected with the second base plate; the clamping apparatus being positioned on an upper surface of the second base plate, and one end of the base of the clamping apparatus being positioned between the first clamping block and the second clamping block.
According to the device, the displacement testing seat comprises a supporting plate, both ends of the supporting plate being provided with through holes, a lower end of the displacement testing means being inserted into the through hole at one end of the supporting plate; the fixing rod being inserted into the through hole at the other end of the supporting plate.
According to the device, the through holes at both ends of the supporting plate are bolt holes, a lower end of the displacement testing means being provided with a thread, the lower end of the displacement testing means being screwed into the bolt hole at one end of the supporting plate to be connected with the supporting plate;
the fixing rod being provided with a thread and being screwed into the bolt hole at the other end of the supporting plate to be connected with the supporting plate.
According to the device, the displacement testing seat comprises a first collet and a second collet connected to each other, the first collet being clamped to a lower portion Date Recue/Date Received 2020-06-23 of the displacement testing apparatus and the second collet being clamped to the fixing rod.
According to the device, the displacement testing means employs a dial gauge.
According to the device, the vertical baffle has two bolt holes formed therein.
According to the device, the connecting plate is an elongated plate, and an upper plate surface of the elongated plate is stepped.
Beneficial technical effects of the present disclosure, The disclosure has the beneficial technical effects that: the method establishes the relationship between residual stress and warpage by accumulating a large amount of experimental data, and can evaluate the residual stress level only by measuring the warpage of the sample. The method is simple and intuitive to operate, high in measurement efficiency and suitable for detection in an industrial production process.
The disclosure provides a device for measuring the residual stress release deformation amount of a thick metal plate. By means of the device, the magnitude of the internal residual stress of a material and the fluctuation of the residual stress among different batches of plates can be rapidly evaluated, so that the effective monitoring of the residual stress of the plates is realized. The establishment of a plate residual stress control standard is facilitated, and the uniformity of the residual stress of the plates is improved. The method and the equipment are not only suitable for testing the residual stress of plates, but also can be used for testing of structures such as profiles, pipes, bars and the like.
Brief Description of the Drawings FIG 1 is a schematic diagram of a linear cutting process of an aluminum alloy thick plate;
FIG 2 is a schematic diagram showing the residual stress distribution along the Date Recue/Date Received 2020-06-23 thickness of an aluminum alloy thick plate;
FIG 3 is a schematic diagram showing the warpage displacement for an aluminum alloy thick plate at different linear cutting depth percentages;
FIG 4 is a schematic diagram showing the residual stress prediction for an aluminum alloy thick plate at different plate thicknesses and warpages;
FIG 5 is a schematic diagram showing a structure of a device for measuring a residual stress release warpage of a thick metal plate according to an embodiment of the present disclosure;
FIG 6 is a side view showing the device for measuring residual stress release warpage of a thick metal plate according to an embodiment of the present disclosure;
FIG 7 is a schematic diagram showing a structure of a device for measuring residual stress release warpage of a thick metal plate according to an embodiment of the present disclosure when a sample to be tested is loaded;
FIG 8 is a schematic diagram showing another structure of a device for measuring the residual stress release warpage of a thick metal plate according to an embodiment of the present disclosure.
In the drawings: base -1; fixing rod -2; displacement testing seat -3;
displacement testing means -4; first base plate -5; two vertical baffles -6, 6'; connecting plate -7;
pressing plate -8; first collet -9; second collet -10; second base plate -11;
fixing plate -12; first clamping block -13; second clamping block -14; sample to be tested -15;
linear cutting machine -16; bolt-17; bolt-18.
Detailed Description of the Disclosure The present disclosure will now be described in further detail with reference to the accompanying drawings and detailed description.
Date Recue/Date Received 2020-06-23 The embodiment of the disclosure provides a method for measuring residual stress of a metal plate based on residual stress release warpage, which comprises the following steps:
(1) adoping one of an X-ray method, a blind hole method, an ultrasonic method, a crack flexibility method or a finite element analysis method to measure residual stress of aluminum alloy plates with different thicknesses, wherein the residual stress distribution of the aluminum alloy thick plate is shown in FIG 2.
(2) fixing one end of an aluminum alloy thick plate, such as a section line portion in FIG 1, wherein a length of the fixed portion is less than 1/2 of a length of a sample, then placing a displacement sensor such as a dial gauge or a laser sensor at a point a at a central portion of an edge at one end of the sample 15 to be tested, recording an initial value, and performing linear cutting along the thickness of the plate by using a linear cutting machine 16 at the position of 1/2 of the length of the sample.
According to the warpage displacement schematic diagram of the aluminum alloy thick plate under different linear cutting depth percentages, as shown in FIG 3, the percentage depth when the warpage tends to be gentle is taken as the linear cutting percentage.
Preferably, the cutting depth is selected as 62.5%-75% of the plate thickness.
The numerical value at point a after cutting is recorded, and the change amount of the value at the point a is obtained as the warpage of the plate.
(3) measuring the warpage of plates with different thicknesses to obtain a relationship between the residual stress and the warpage; obtaining, by fitting a curve, a quadratic equation: y=ax2+bx+c, where x is residual stress, y is warpage, and a, b, c are fitting coefficients.
(4) cutting the metal plate on the basis of established functional relationship between the residual stress and the warpage, measuring the warpage y under a specific linear cutting percentage, and calculating the residual stress according to a formula, wherein, as shown in FIG 4, the distribution of the residual stress under different plate Date Recue/Date Received 2020-06-23 thicknesses and warpages can be obtained.
As shown in FIGs 5-8, a device for measuring residual stress release deformation amount of a thick metal plate comprises a clamping apparatus, wherein the clamping apparatus comprises a base 1, a fixing rod 2, a displacement testing seat 3 and a displacement testing means 4. The base comprises a first base plate 5, two vertical baffles 6 and 6', a connecting plate 7 and a pressing plate 8, wherein the first base plate is a horizontally arranged rectangular plate, and the two vertical baffles are vertical rectangular plates, one end of the first base plate being fixedly connected with the vertical baffle 6, the other end of the first base plate being fixedly connected with the vertical baffle 6', and bolt holes being formed in the two vertical baffles, respectively, one side edge of the first base plate being fixedly connected with one end of the connecting plate, the first base plate and the connecting plate forming a T
structure, the connecting plate being an elongated plate, an upper plate surface of the elongated plate being stepped, the other end of the connecting plate being provided with a connecting hole, the pressing plate being a rectangular plate, the pressing plate being positioned on an upper surface of the two vertical baffles, the pressing plate being provided with a through hole corresponding to the bolt hole of the two vertical baffles in position, the pressing plate being connected with the two vertical baffles through bolts 17, and the bolts being preferably hexagon screws, wherein the connecting plate can also cushion the sample to be tested by adopting a cushion block and other methods, so that additional deformation of the sample to be tested caused by the pressing force of the pressing plate is avoided. The fixing rod is preferably a cylindrical rod, while a lower end of the fixing rod is inserted into the connecting hole of the connecting plate to be fixedly connected with the other end of the connecting plate. One end of the displacement testing seat is sleeved outside the fixing rod, and the other end of the displacement testing seat is connected with a lower end of the displacement testing means. In particular, the displacement testing seat has a structure which comprises a supporting plate, both ends of the supporting plate being provided with through holes, the lower end of the displacement testing means being inserted Date Recue/Date Received 2020-06-23 into the through hole at one end of the supporting plate, and the fixing rod being inserted into the through hole at the other end of the supporting plate.
Preferably, the through holes at both ends of the supporting plate are bolt holes, the lower end of the displacement testing means being provided with a thread, and the lower end of the displacement testing means being screwed into the bolt hole at one end of the supporting plate to be connected with the supporting plate. The fixing rod is provided with a thread, and is screwed into the bolt hole at the other end of the supporting plate to be connected with the supporting plate.
Another structure of the displacement testing seat is provided that: the displacement testing seat comprises a first collet 9 and a second collet 10 connected with each other, the clamping ends of the two collets facing outwards, the first collet being clamped to a lower portion of the displacement testing means, the second collet being clamped to the fixing rod, and the ends of the two collets being fastened through fastening bolts 18. The displacement testing means can adopt other contact and non-contact displacement testing means, preferably a dial gauge.
The device further comprises a deformation testing platform, wherein the deformation testing platform comprises a second base plate 11, a fixing plate 12, a first clamping block 13 and a second clamping block 14; the second base plate being a horizontal rectangular plate, the fixing plate being a vertical rectangular plate, a lower end of the fixing plate being fixedly connected with one end of an upper plate surface of the second base plate, and a plurality of connecting holes being formed in a plate surface of the fixing plate. The first clamping block and the second clamping block are vertical plates, one end of the first clamping block being fixedly connected with one end of a plate surface of the fixing plate, and a lower end of the first clamping block being fixedly connected with an upper plate surface of the second base plate.
The second clamping block is arranged opposite to the first clamping block, one end of the second clamping block being provided with a bolt hole corresponding to the connecting hole of the fixing plate in position, one end of the second clamping block Date Recue/Date Received 2020-06-23 provided with the bolt hole being connected with the plate surface of the fixing plate through a bolt, and a lower end of the second clamping block being fixedly connected with an upper plate surface of the second base plate. The clamping apparatus is positioned on the upper plate surface of the second base plate, and one end of the base of the clamping apparatus is positioned between the first clamping block and the second clamping block.
In use, the sample 15 to be tested is placed in the base of the clamping apparatus, and the connecting bolts of the pressing plate and the two vertical baffles are screwed tightly. The sample to be tested is fixed in the base of the clamping apparatus, and a position of the dial gauge is adjusted by adjusting a position of the displacement testing base, so that a measuring head of the dial gauge contacts a surface of the sample to be tested, and the measuring head is preferably slightly pressed down by 1-3 mm. Then the clamping apparatus is placed on the second base plate of the deformation testing platform horizontally, one end of the base of the clamping apparatus being positioned between the first clamping block and the second clamping block, and a position of the second clamping block being adjusted to clamp the device.
Then the sample to be tested is cut using a linear cutting machine 16, wherein the residual stress of the sample to be tested (in a quenching state, a pre-stretching state and an aging state) is a surface compressive stress and a central tensile stress state distribution, so that the sample to be tested is bent towards one side which is cut first.
The compression and bending deformation triggers the dial gauge, and the deformation amount of the sample to be tested at a specific linear cutting depth is obtained by calculating a reading difference of the dial gauge before and after linear cutting. An integral level of the residual stress inside the aluminum alloy thick plate is judged according to the deformation difference under the same linear cutting depth.
The materials which can be tested by the device are structures such as cutting plates, belts, extruded materials and pipes, and are not limited to specific sizes.
The tested materials are all materials that can be removed using low external forces and are not Date Recue/Date Received 2020-06-23 limited to specific metal material and non-metal material varieties. The method for releasing residual stress adopts a method for removing materials with low external force, and comprises linear cutting and electric spark.
The foregoing description is only one example of implementation of the present disclosure and is not intended to limit the disclosure. It should be noted that other equivalent modifications may be made by those skilled in the art in light of the technical teachings of this disclosure, or the present disclosure can be applied to other occasions without modification, which can also achieve the technical objects of the present disclosure and shall be covered by the protection scopes thereof.
Date Recue/Date Received 2020-06-23
According to the device, the displacement testing seat comprises a supporting plate, both ends of the supporting plate being provided with through holes, a lower end of the displacement testing means being inserted into the through hole at one end of the supporting plate; the fixing rod being inserted into the through hole at the other end of the supporting plate.
According to the device, the through holes at both ends of the supporting plate are bolt holes, a lower end of the displacement testing means being provided with a thread, the lower end of the displacement testing means being screwed into the bolt hole at one end of the supporting plate to be connected with the supporting plate;
the fixing rod being provided with a thread and being screwed into the bolt hole at the other end of the supporting plate to be connected with the supporting plate.
According to the device, the displacement testing seat comprises a first collet and a second collet connected to each other, the first collet being clamped to a lower portion Date Recue/Date Received 2020-06-23 of the displacement testing apparatus and the second collet being clamped to the fixing rod.
According to the device, the displacement testing means employs a dial gauge.
According to the device, the vertical baffle has two bolt holes formed therein.
According to the device, the connecting plate is an elongated plate, and an upper plate surface of the elongated plate is stepped.
Beneficial technical effects of the present disclosure, The disclosure has the beneficial technical effects that: the method establishes the relationship between residual stress and warpage by accumulating a large amount of experimental data, and can evaluate the residual stress level only by measuring the warpage of the sample. The method is simple and intuitive to operate, high in measurement efficiency and suitable for detection in an industrial production process.
The disclosure provides a device for measuring the residual stress release deformation amount of a thick metal plate. By means of the device, the magnitude of the internal residual stress of a material and the fluctuation of the residual stress among different batches of plates can be rapidly evaluated, so that the effective monitoring of the residual stress of the plates is realized. The establishment of a plate residual stress control standard is facilitated, and the uniformity of the residual stress of the plates is improved. The method and the equipment are not only suitable for testing the residual stress of plates, but also can be used for testing of structures such as profiles, pipes, bars and the like.
Brief Description of the Drawings FIG 1 is a schematic diagram of a linear cutting process of an aluminum alloy thick plate;
FIG 2 is a schematic diagram showing the residual stress distribution along the Date Recue/Date Received 2020-06-23 thickness of an aluminum alloy thick plate;
FIG 3 is a schematic diagram showing the warpage displacement for an aluminum alloy thick plate at different linear cutting depth percentages;
FIG 4 is a schematic diagram showing the residual stress prediction for an aluminum alloy thick plate at different plate thicknesses and warpages;
FIG 5 is a schematic diagram showing a structure of a device for measuring a residual stress release warpage of a thick metal plate according to an embodiment of the present disclosure;
FIG 6 is a side view showing the device for measuring residual stress release warpage of a thick metal plate according to an embodiment of the present disclosure;
FIG 7 is a schematic diagram showing a structure of a device for measuring residual stress release warpage of a thick metal plate according to an embodiment of the present disclosure when a sample to be tested is loaded;
FIG 8 is a schematic diagram showing another structure of a device for measuring the residual stress release warpage of a thick metal plate according to an embodiment of the present disclosure.
In the drawings: base -1; fixing rod -2; displacement testing seat -3;
displacement testing means -4; first base plate -5; two vertical baffles -6, 6'; connecting plate -7;
pressing plate -8; first collet -9; second collet -10; second base plate -11;
fixing plate -12; first clamping block -13; second clamping block -14; sample to be tested -15;
linear cutting machine -16; bolt-17; bolt-18.
Detailed Description of the Disclosure The present disclosure will now be described in further detail with reference to the accompanying drawings and detailed description.
Date Recue/Date Received 2020-06-23 The embodiment of the disclosure provides a method for measuring residual stress of a metal plate based on residual stress release warpage, which comprises the following steps:
(1) adoping one of an X-ray method, a blind hole method, an ultrasonic method, a crack flexibility method or a finite element analysis method to measure residual stress of aluminum alloy plates with different thicknesses, wherein the residual stress distribution of the aluminum alloy thick plate is shown in FIG 2.
(2) fixing one end of an aluminum alloy thick plate, such as a section line portion in FIG 1, wherein a length of the fixed portion is less than 1/2 of a length of a sample, then placing a displacement sensor such as a dial gauge or a laser sensor at a point a at a central portion of an edge at one end of the sample 15 to be tested, recording an initial value, and performing linear cutting along the thickness of the plate by using a linear cutting machine 16 at the position of 1/2 of the length of the sample.
According to the warpage displacement schematic diagram of the aluminum alloy thick plate under different linear cutting depth percentages, as shown in FIG 3, the percentage depth when the warpage tends to be gentle is taken as the linear cutting percentage.
Preferably, the cutting depth is selected as 62.5%-75% of the plate thickness.
The numerical value at point a after cutting is recorded, and the change amount of the value at the point a is obtained as the warpage of the plate.
(3) measuring the warpage of plates with different thicknesses to obtain a relationship between the residual stress and the warpage; obtaining, by fitting a curve, a quadratic equation: y=ax2+bx+c, where x is residual stress, y is warpage, and a, b, c are fitting coefficients.
(4) cutting the metal plate on the basis of established functional relationship between the residual stress and the warpage, measuring the warpage y under a specific linear cutting percentage, and calculating the residual stress according to a formula, wherein, as shown in FIG 4, the distribution of the residual stress under different plate Date Recue/Date Received 2020-06-23 thicknesses and warpages can be obtained.
As shown in FIGs 5-8, a device for measuring residual stress release deformation amount of a thick metal plate comprises a clamping apparatus, wherein the clamping apparatus comprises a base 1, a fixing rod 2, a displacement testing seat 3 and a displacement testing means 4. The base comprises a first base plate 5, two vertical baffles 6 and 6', a connecting plate 7 and a pressing plate 8, wherein the first base plate is a horizontally arranged rectangular plate, and the two vertical baffles are vertical rectangular plates, one end of the first base plate being fixedly connected with the vertical baffle 6, the other end of the first base plate being fixedly connected with the vertical baffle 6', and bolt holes being formed in the two vertical baffles, respectively, one side edge of the first base plate being fixedly connected with one end of the connecting plate, the first base plate and the connecting plate forming a T
structure, the connecting plate being an elongated plate, an upper plate surface of the elongated plate being stepped, the other end of the connecting plate being provided with a connecting hole, the pressing plate being a rectangular plate, the pressing plate being positioned on an upper surface of the two vertical baffles, the pressing plate being provided with a through hole corresponding to the bolt hole of the two vertical baffles in position, the pressing plate being connected with the two vertical baffles through bolts 17, and the bolts being preferably hexagon screws, wherein the connecting plate can also cushion the sample to be tested by adopting a cushion block and other methods, so that additional deformation of the sample to be tested caused by the pressing force of the pressing plate is avoided. The fixing rod is preferably a cylindrical rod, while a lower end of the fixing rod is inserted into the connecting hole of the connecting plate to be fixedly connected with the other end of the connecting plate. One end of the displacement testing seat is sleeved outside the fixing rod, and the other end of the displacement testing seat is connected with a lower end of the displacement testing means. In particular, the displacement testing seat has a structure which comprises a supporting plate, both ends of the supporting plate being provided with through holes, the lower end of the displacement testing means being inserted Date Recue/Date Received 2020-06-23 into the through hole at one end of the supporting plate, and the fixing rod being inserted into the through hole at the other end of the supporting plate.
Preferably, the through holes at both ends of the supporting plate are bolt holes, the lower end of the displacement testing means being provided with a thread, and the lower end of the displacement testing means being screwed into the bolt hole at one end of the supporting plate to be connected with the supporting plate. The fixing rod is provided with a thread, and is screwed into the bolt hole at the other end of the supporting plate to be connected with the supporting plate.
Another structure of the displacement testing seat is provided that: the displacement testing seat comprises a first collet 9 and a second collet 10 connected with each other, the clamping ends of the two collets facing outwards, the first collet being clamped to a lower portion of the displacement testing means, the second collet being clamped to the fixing rod, and the ends of the two collets being fastened through fastening bolts 18. The displacement testing means can adopt other contact and non-contact displacement testing means, preferably a dial gauge.
The device further comprises a deformation testing platform, wherein the deformation testing platform comprises a second base plate 11, a fixing plate 12, a first clamping block 13 and a second clamping block 14; the second base plate being a horizontal rectangular plate, the fixing plate being a vertical rectangular plate, a lower end of the fixing plate being fixedly connected with one end of an upper plate surface of the second base plate, and a plurality of connecting holes being formed in a plate surface of the fixing plate. The first clamping block and the second clamping block are vertical plates, one end of the first clamping block being fixedly connected with one end of a plate surface of the fixing plate, and a lower end of the first clamping block being fixedly connected with an upper plate surface of the second base plate.
The second clamping block is arranged opposite to the first clamping block, one end of the second clamping block being provided with a bolt hole corresponding to the connecting hole of the fixing plate in position, one end of the second clamping block Date Recue/Date Received 2020-06-23 provided with the bolt hole being connected with the plate surface of the fixing plate through a bolt, and a lower end of the second clamping block being fixedly connected with an upper plate surface of the second base plate. The clamping apparatus is positioned on the upper plate surface of the second base plate, and one end of the base of the clamping apparatus is positioned between the first clamping block and the second clamping block.
In use, the sample 15 to be tested is placed in the base of the clamping apparatus, and the connecting bolts of the pressing plate and the two vertical baffles are screwed tightly. The sample to be tested is fixed in the base of the clamping apparatus, and a position of the dial gauge is adjusted by adjusting a position of the displacement testing base, so that a measuring head of the dial gauge contacts a surface of the sample to be tested, and the measuring head is preferably slightly pressed down by 1-3 mm. Then the clamping apparatus is placed on the second base plate of the deformation testing platform horizontally, one end of the base of the clamping apparatus being positioned between the first clamping block and the second clamping block, and a position of the second clamping block being adjusted to clamp the device.
Then the sample to be tested is cut using a linear cutting machine 16, wherein the residual stress of the sample to be tested (in a quenching state, a pre-stretching state and an aging state) is a surface compressive stress and a central tensile stress state distribution, so that the sample to be tested is bent towards one side which is cut first.
The compression and bending deformation triggers the dial gauge, and the deformation amount of the sample to be tested at a specific linear cutting depth is obtained by calculating a reading difference of the dial gauge before and after linear cutting. An integral level of the residual stress inside the aluminum alloy thick plate is judged according to the deformation difference under the same linear cutting depth.
The materials which can be tested by the device are structures such as cutting plates, belts, extruded materials and pipes, and are not limited to specific sizes.
The tested materials are all materials that can be removed using low external forces and are not Date Recue/Date Received 2020-06-23 limited to specific metal material and non-metal material varieties. The method for releasing residual stress adopts a method for removing materials with low external force, and comprises linear cutting and electric spark.
The foregoing description is only one example of implementation of the present disclosure and is not intended to limit the disclosure. It should be noted that other equivalent modifications may be made by those skilled in the art in light of the technical teachings of this disclosure, or the present disclosure can be applied to other occasions without modification, which can also achieve the technical objects of the present disclosure and shall be covered by the protection scopes thereof.
Date Recue/Date Received 2020-06-23
Claims (9)
1. A method for predicting residual stress of a metal plate based on residual stress release warpage, comprising:
(1) adopting one of an X-ray method, a blind hole method, an ultrasonic method, a crack flexibility method and a finite element analysis method to test the residual stress of plates with different thicknesses;
(2) cutting a sample by a machining method along a plate thickness direction, releasing the residual stress to cause warpage of the plate, and testing the warpage of the plate by a displacement sensor to obtain a relationship between the residual stress and the warpage of the plates with different thicknesses; obtaining, by fitting a curve, a quadratic equation: y=ax2-Ebx+c, wherein x is residual stress, y is warpage, and a, b and c are fitting coefficients;
(3) testing, upon cutting the metal plate on the basis of established functional relationship between the residual stress and the warpage, the warpage y under a specific linear cutting percentage, and calculating the residual stress according to a formula
(1) adopting one of an X-ray method, a blind hole method, an ultrasonic method, a crack flexibility method and a finite element analysis method to test the residual stress of plates with different thicknesses;
(2) cutting a sample by a machining method along a plate thickness direction, releasing the residual stress to cause warpage of the plate, and testing the warpage of the plate by a displacement sensor to obtain a relationship between the residual stress and the warpage of the plates with different thicknesses; obtaining, by fitting a curve, a quadratic equation: y=ax2-Ebx+c, wherein x is residual stress, y is warpage, and a, b and c are fitting coefficients;
(3) testing, upon cutting the metal plate on the basis of established functional relationship between the residual stress and the warpage, the warpage y under a specific linear cutting percentage, and calculating the residual stress according to a formula
2. The method according to claim 1, wherein in step (2) the machining method is preferably a linear cutting method.
3. The method according to claim 1, wherein in step (2), the sample is cut by fixing one end of the metal plate, a length of a fixed portion being less than 1/2 of a length of the sample, a cutting position being preferably selected at 1/2 of the length of the sample, and the cutting being performed along the plate thickness direction.
4. The method according to claim 1, wherein in step (2) the warpage is measured at an end remote from a clamping position.
5. The method according to claim 1, wherein in step (3) the specific linear cutting percentage is controlled at a position where the warpage tends to be gentle.
6. The method according to claim 1, wherein in step (2) a cutting depth of the sample is 62.5-75% of a thickness of the sample.
7. The method according to claim 1, wherein in step (2) a cutting depth of the sample is 75-95% of a thickness of the sample.
8. The method according to claim 1, wherein in step (2) a cutting depth of the sample is 50-62.5% of a thickness of the sample.
9. The method according to claim 1, wherein in step (2) a cutting depth of the sample is 30-50% of a thickness of the sample.
Date Recue/Date Received 2022-04-29
Date Recue/Date Received 2022-04-29
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810132387.4A CN108225161A (en) | 2018-02-09 | 2018-02-09 | A kind of device for measuring metal thick plate residual stress release deflection |
| CN201810139760.9A CN108168761A (en) | 2018-02-11 | 2018-02-11 | A kind of method based on residual stress release amount of warpage prediction sheet metal residual stress |
| PCT/CN2019/070934 WO2019154000A1 (en) | 2018-02-09 | 2019-01-09 | Method and apparatus for predicting metal sheet residual stress based on measurement of warpage amount caused by residual stress release |
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| CA3086808A1 CA3086808A1 (en) | 2019-08-15 |
| CA3086808C true CA3086808C (en) | 2023-03-07 |
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| WO (1) | WO2019154000A1 (en) |
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| CN111062095A (en) * | 2019-11-07 | 2020-04-24 | 南京航空航天大学 | Machining deformation evaluation method based on condition number |
| CN113032908B (en) * | 2021-03-31 | 2022-05-06 | 武汉理工大学 | Prediction method for space envelope forming warping deformation of thin-wall component |
| CN113670810A (en) * | 2021-07-22 | 2021-11-19 | 包头钢铁（集团）有限责任公司 | Test method for testing residual stress of H-shaped steel by adopting linear cutting |
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| CN1082192A (en) * | 1993-05-04 | 1994-02-16 | 西安冶金建筑学院 | The measuring method of thin plate unrelieved stress |
| US7636151B2 (en) * | 2006-01-06 | 2009-12-22 | Qualcomm Mems Technologies, Inc. | System and method for providing residual stress test structures |
| CN104913866B (en) * | 2015-06-17 | 2018-03-06 | 上海大学 | The method, apparatus of secondary ray diffraction measurement thin plate residual stress and application |
| CN105509949B (en) * | 2015-12-01 | 2017-07-25 | 北京航空航天大学 | A kind of method for measuring the unidirectional residual stress of plate |
| CN105699158B (en) * | 2016-02-03 | 2018-08-03 | 清华大学 | Electrolyzing and corroding device and test system for cutting residual stress distribution test |
| CN108168761A (en) * | 2018-02-11 | 2018-06-15 | 中铝材料应用研究院有限公司 | A kind of method based on residual stress release amount of warpage prediction sheet metal residual stress |
| CN108225161A (en) * | 2018-02-09 | 2018-06-29 | 中铝材料应用研究院有限公司 | A kind of device for measuring metal thick plate residual stress release deflection |
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