Special two-dimensional force square sensor for force-controlled polishing

Abstract

The invention discloses a two-dimensional force square sensor specially used for force control polishing, the two-dimensional force square sensor comprises an overall square elastic body, an upper cover plate, a lower cover plate and a main plate, the elastic body comprises an elastic body hub, a stress table and four strain beams, the elastic body hub is square, a round hole is formed in the center of the elastic body hub, and the stress table is arranged in the round hole; the four strain beams are uniformly distributed between the stress table and the elastomer hub; the upper cover plate and the lower cover plate are arranged at the upper and lower ends of the elastomer, and the stress table protrudes out of the upper cover plate; the main plate is arranged below the upper cover plate and is detachably connected with the elastomer hub; pasting a plurality of strain gauges on the four strain beams to form two Wheatstone bridges, and respectively measuring the tangential force Fy and the normal force Fz; the two Wheatstone bridges are connected to the mainboard, the mainboard supplies power to the bridge circuit and collects data, and an EtherCat communication line and a power cable comprising a power line and a 485 communication line are connected to the mainboard. The sensor has the advantages of high rigidity, good dynamic performance and high measurement precision.

Description

Technical Field

[0001] The invention belongs to the field of sensor measurement, is based on the principle of resistive strain, and is specifically a two-dimensional force square sensor specially used for force-controlled polishing, and is used in the humanoid robot industry. Background Art

[0002] With the rapid development of science and technology, sensors have penetrated into various fields of industrial production, and force-controlled grinding has developed rapidly. At present, in the industry, square two-dimensional sensors or one-dimensional sensors are often installed on grinding machines. According to relevant reports, the range of grinding products is also relatively wide, mainly 3C shells, glass, etc., especially glass grinding is leading in the industry. Adapting two-dimensional force sensors on grinding equipment can effectively improve the accuracy and efficiency of grinding. This two-dimensional force sensor currently has the following shortcomings: ①, the bending moment resistance is poor, and the strain beam of the sensor often breaks when subjected to impact force. ②, currently this two-dimensional force sensor is analog output and connected to a transmitter. The two-dimensional force sensor of the present invention directly outputs digital quantities and directly outputs force values. It provides two communication methods, 485 and EtherCat, and can realize sensor networking. Therefore, it is of far-reaching significance to invent a two-dimensional force square sensor specifically used for force-controlled grinding. Summary of the invention

[0003] The technical problem to be solved by the present invention is that the two-dimensional force sensor used in the known grinding industry has poor overload resistance and weak rigidity, and the sensor is often damaged when subjected to impact force during the grinding process.

[0004] The present invention proposes a two-dimensional force square sensor specifically used for force-controlled polishing, and the technical method adopted is as follows: A two-dimensional force square sensor specially used for force-controlled polishing, comprising an elastic body (1) which is in the shape of a square as a whole, an upper cover plate (2), a lower cover plate (3) and a main board (4), wherein the elastic body (1) comprises an elastic body hub, a force-bearing platform and four strain beams, the elastic body hub is in the shape of a square, a circular hole is arranged at the center, the force-bearing platform is placed in the circular hole, and the four strain beams are evenly distributed between the force-bearing platform and the elastic body hub; the upper cover plate (2) and the lower cover plate (3) are arranged at the upper and lower ends of the elastic body (1), and the force-bearing platform protrudes An upper cover plate (2); a main board (4) is placed below the upper cover plate (2) and is detachably connected to the elastic body hub; a plurality of strain gauges are attached to four strain beams to form two Wheatstone bridges for respectively measuring forces in two directions, namely, a tangential force Fy and a normal force Fz; the two Wheatstone bridges are connected to the main board (4), the main board (4) supplies power to the bridge circuit and collects data, and an EtherCat communication line and a power cable including a power line and a 485 communication line are connected to the main board (4).

[0005] The two-dimensional force square sensor of the present invention is a digital output, and is provided with two communication modes, 485 and EtherCat, to support the networking of multiple sensors and meet the needs of polishing equipment networking. At present, two-dimensional force sensors generally have analog output and are connected to transmitters. The invention is a digital output, directly outputs the force value, provides two communication modes, 485 and EtherCat, and can realize sensor networking.

[0006] In a further preferred embodiment of the technical solution of the present invention, a stress isolation groove (9) is provided on the lower end surface of the elastic body (1). This has two purposes: first, to reduce the hysteresis of the sensor, and second, to solve the problem of the sensor's zero return capability.

[0007] In a further preferred embodiment of the technical solution of the present invention, the depth of the stress isolation groove (9) is 1 mm. The provision of the stress isolation groove reduces the contact area, reduces the hysteresis of the sensor, and improves the zero return capability of the sensor.

[0008] Further optimization of the technical solution of the present invention is that in the actual grinding process, the loading of the tangential force Fy cannot be over-centered, and is generally 200 to 300 mm away from the surface of the sensor. In this way, there will be additional bending moment during the grinding process. Therefore, the coupling of the bending moment to the tangential force Fy is reduced during design. The four strain beams of the present invention are respectively located in the middle of the four sides of the square elastomer hub. The purpose of the symmetrical arrangement of the four strain beams is to reduce the measurement error during eccentric loading, and at the same time reduce the coupling of the bending moment to the tangential force Fy and the normal force Fz.

[0009] In a further optimization of the technical solution of the present invention, special-shaped holes are provided on the four strain beams. According to the principle of stress concentration in material mechanics, special-shaped holes of a certain shape are provided on the strain beams. This has three purposes: first, to ensure that the patch area has a sufficiently large strain as much as possible, to improve the sensitivity of the sensor; second, to ensure that the strain change in the area covered by the strain gauge wire grid is as small as possible; and third, to improve the overload capacity.

[0010] In a further optimization of the technical solution of the present invention, 16 strain gauges are pasted on the four strain beams, and the strain gauges are bonded to the surfaces of the four strain beams and the inner walls of the special-shaped holes; the 16 strain gauges are R1~R16, among which R1~R8 constitute a full-bridge measurement of Fy, and R9~R16 constitute a full-bridge measurement of Fz. The reason why 8 gauges are used for Fz is to reduce the force measurement error of bending moment on Fz. If 4 strain gauges are used, it will inevitably lead to a large measurement error of Tx or Ty on Fz.

[0011] In a further embodiment of the technical solution of the present invention, an elliptical center hole is opened on the force-bearing platform. This is because in the actual grinding process, a soft air tube needs to be passed through. During grinding, the soft air tube may be displaced to a certain extent. In order to prevent the soft air tube from hitting the sensor and affecting the measurement error and to reduce the possible measurement error, an elliptical center hole is opened to give the soft air tube a certain displacement space.

[0012] In a further preferred embodiment of the technical solution of the present invention, a recessed groove for receiving the main board (4) is provided on the elastic body (2), and the upper cover plate (1) and the lower cover plate (3) are respectively embedded in the grooves on the upper and lower end surfaces of the elastic body (2) and glued together. The upper cover plate and the lower cover plate play a role in sealing and protecting the main board, and are sealed with 704 sealant.

[0013] In a further preferred embodiment of the technical solution of the present invention, the material of the elastic body (1) is stainless steel, which effectively prevents the sensor from being corroded by the corrosive liquid during the force-controlled grinding process.

[0014] In a further preferred embodiment of the technical solution of the present invention, the EtherCat communication cable and the power cable are both passed through the waterproof connector and connected to the two threaded holes on the elastic body (1). The waterproof connector is arranged in the threaded hole. The waterproof connector is threaded. A corresponding threaded hole is opened on the elastic body, and the waterproof connector is directly screwed onto the elastic body.

[0015] Further optimization of the technical solution of the present invention.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The two-dimensional force square sensor of the present invention is specially used for force-controlled grinding. The shape of the sensor is 130mm*130mm*22mm (height), and it is specially used in the force-controlled grinding industry; 2. The square sensor of the present invention is specially used for force-controlled polishing. It is a two-dimensional sensor that measures tangential force and normal force, and the measuring range is 1000N. 3. The square sensor of the present invention is specially used for force-controlled grinding of two-dimensional forces. The elastic body is used as the sensitive component of the sensor. A four-beam structure is adopted. According to the principle of stress concentration in material mechanics, certain special-shaped holes are provided on the strain beam, which can effectively improve the sensitivity of the sensor and also improve the overload capacity of the sensor. The elastic body is also designed with the strain gauge pasting process in mind to ensure sufficient space for pasting. 4. The two-dimensional force square sensor of the present invention is specially used for force-controlled grinding. Considering the special needs of the force-controlled grinding industry, the two-dimensional force sensor involved in the present invention has higher rigidity and higher natural vibration frequency; 5. The new type of square sensor specially used for force-controlled grinding of two-dimensional force has digital output, is equipped with two communication modes of 485 and EtherCat, and supports the networking of multiple sensors; 6. The novel square sensor of the present invention is specially used for force-controlled grinding of two-dimensional forces. A stress isolation groove is provided to reduce the hysteresis of the sensor and solve the zero return problem of the sensor; 7. The new type of square sensor specially used for force-controlled grinding of two-dimensional forces of the present invention has an overload capacity of more than 200%; 8. The novel square sensor of the present invention is specially used for force-controlled grinding. The sensor is made of stainless steel, which effectively prevents the corrosion of the sensor by the corrosive liquid during the force-controlled grinding process; 9. The novel square sensor of the present invention is specially used for force-controlled grinding of two-dimensional forces, and has high rigidity, good dynamic performance and high measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a front three-dimensional schematic diagram of a square sensor specially used for force-controlled polishing of two-dimensional force in this embodiment; Figure 2 It is a three-dimensional schematic diagram of the back side of a square sensor of the present embodiment which is specially used for force-controlled polishing of two-dimensional force; Figure 3 yes Figure 1 3D schematic diagram without the upper cover; Figure 4 is a three-dimensional schematic diagram of the front side of the elastic body; Figure 5 A three-dimensional schematic diagram of the back side of the elastomer; Figure 6 This is a schematic diagram of the bridge assembly of the square sensor for force-controlled grinding of two-dimensional forces in this embodiment; Figure 7 is a top view of the elastic body of this embodiment after the front patch is attached; Figure 8 yes Figure 7 AA cut view; Fig. 9 yes Figure 7 BB cutaway view; Fig.10 is a top view of the back side of the elastic body of this embodiment after the patch is attached; Fig.11 This is the equivalent stress cloud diagram calculated by ANSYS Workbench when the load Fy=1000N is applied to the square sensor for force-controlled grinding of two-dimensional force in this embodiment; Fig.12 This is the displacement cloud diagram calculated by ANSYS Workbench when the load Fy=1000N is applied to the square sensor of the two-dimensional force controlled grinding in this embodiment; Fig.13This is the equivalent stress cloud diagram calculated by ANSYS Workbench when the load Fz=1000N is applied to the square sensor for force-controlled grinding of two-dimensional force in this embodiment; Fig.14 This is the displacement cloud diagram calculated by ANSYS Workbench when the load Fz=1000N is applied to the square sensor of the two-dimensional force controlled grinding in this embodiment; Fig.15 It is a schematic diagram of the structure of the strain gauge; Among them, 1 is an elastic body, 2 is an upper cover plate, 3 is a lower cover plate, 4 is a main board, 5 is a first strain beam, 6 is a second strain beam, 7 is a third strain beam, 8 is a fourth strain beam, 9 is a stress isolation groove, and R1~R16 are strain gauges. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the following Figure 1 -Attached Fig.15 The present invention is further described in detail with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0019] like Figure 1 and 2 As shown, this embodiment is a two-dimensional force square sensor specially used for force-controlled grinding, and is specially used in the force-controlled grinding industry. This two-dimensional force square sensor is based on the resistance strain principle.

[0020] A two-dimensional force square sensor specially used for force-controlled polishing comprises an elastic body 1, an upper cover plate 2, a lower cover plate 3, a main board 4, an EtherCat communication line, a power cable and two waterproof connectors.

[0021] like Figure 3 and 4 As shown, the elastic body 1 includes an elastic body hub, a force-bearing platform and four strain beams. The elastic body hub is square with a circular hole in the center. The force-bearing platform is placed in the circular hole. The four strain beams are evenly distributed between the force-bearing platform and the elastic body hub. The upper cover plate 2 and the lower cover plate 3 are arranged at the upper and lower ends of the elastic body 1, and the force-bearing platform protrudes from the upper cover plate 2; the main board 4 is placed below the upper cover plate 2 and is detachably connected to the elastic body hub; specifically: a sink groove for loading the main board 4 is provided on the elastic body 2, and the upper cover plate 1 and the lower cover plate 3 are respectively embedded in the grooves on the upper and lower end surfaces of the elastic body 2; the upper cover plate 2 and the elastic body 1 are sealed with 704 sealant, and the lower cover plate 3 and the elastic body 1 are sealed with 704 sealant, and the main board 4 is fixed inside the elastic body 1 with 4 M2 screws.

[0022] The EtherCat communication line and the power cable are welded to the mainboard 4 and fixed to the elastomer 1 through a waterproof connector. Specifically, two threaded holes 11 are set on the elastomer 1. First, the EtherCat communication line and the power cable are passed through the waterproof connector respectively, and then through the two threaded holes 11 on the elastomer 1. The waterproof connector is tightened, and finally the EtherCat communication line and the power cable are welded to the mainboard 4 according to the line color definition.

[0023] In this embodiment, the power cable is a 4-core wire with a shielding layer, a group of power supplies, namely: power positive (power supply is DC24V) and power negative (GND), and a group of 485 communication lines, namely RS485 A and RS485 B.

[0024] In this embodiment, the main board 4 is fixed inside the elastic body 1. The main function of the main board 4 is data acquisition. It has two communication modes: EtherCat and 485. The main board 4 is powered by DC 24V, the bridge circuit is powered by DC 12V, and the signal amplification factor is 500 times.

[0025] like Figure 4 As shown, four strain beams are symmetrically arranged between the force-bearing platform on the elastic body 2 and the elastic body hub, namely the first strain beam 5, the second strain beam 6, the third strain beam 7 and the fourth strain beam 8, wherein the first strain beam 5 and the second strain beam 6 are collinear, and the third strain beam 7 and the fourth strain beam 8 are collinear.

[0026] like Figure 5 As shown, the material of the elastic body 1 is stainless steel, 17-4 PH. A stress isolation groove 9 is provided on the lower end surface of the elastic body 1. This has two purposes: one is to reduce the hysteresis of the sensor, and the other is to solve the zero return capability of the sensor; the depth of the stress isolation groove 9 is 1 mm.

[0027] like Figure 4 and 5 As shown, in this embodiment, according to the stress concentration principle in material mechanics, a special-shaped hole of a certain shape is set on the strain beam. The purposes of doing so are three: first, to ensure that the patch area has a sufficiently large strain as much as possible, thereby increasing the sensitivity of the sensor; second, to ensure that the strain change in the area covered by the strain gauge wire grid is as small as possible; and third, to improve the overload capacity.

[0028] Multiple strain gauges are pasted on the four strain beams to form two Wheatstone bridges to measure the forces in the two directions of Fy and Fz respectively; the two Wheatstone bridges are connected to the main board 4, which supplies power to the bridge circuit and collects data. The main board 4 is connected to the EtherCat communication line and the power cable including the power line and the 485 communication line.

[0029] The two-dimensional force square sensor of this embodiment is specially used in the grinding industry to measure the tangential force Fy and the normal force Fz. Specifically, it is a two-dimensional force square sensor specially used for force-controlled grinding.

[0030] like Figure 6 As shown, in this embodiment, 16 strain gauges are pasted on the four strain beams, and the strain gauges are bonded to the surfaces of the four strain beams and the inner walls of the special-shaped holes; the 16 strain gauges are R1~R16, among which R1~R8 form a full-bridge measurement Fy, and R9~R16 form a full-bridge measurement Fz.

[0031] like Figure 7 , 8 , 9 and 10, 16 strain gauges are pasted on the elastic body 1, as shown in Figure 6 As shown, two independent Wheatstone bridges are formed to measure the tangential force Fy and the normal force Fz respectively. Figure 7 , 8 , patch sum in 9 and 10 Figure 6 R1-R16 in it represent strain gauges, and R—— represents a fixed resistance of 350Ω.

[0032] When the elastic body 1 is subjected to the tangential force Fy, the third strain beam 7 is subjected to tensile stress, the fourth strain beam 8 is subjected to compressive stress, R1, R4, R5 and R8 are subjected to tensile strain, and R2, R3, R6 and R7 are subjected to compressive strain. Figure 6 The first Wheatstone bridge in the figure measures the lateral force Fy.

[0033] When the elastic body 1 is subjected to the normal force Fz, the four strain beams are bent, R9, R12, R13 and R16 are subjected to tensile strain, and R10, R11, R13 and R15 are subjected to compressive strain, forming Figure 6 The second Wheatstone bridge in , measures the normal force Fz.

[0034] like Fig.15 As shown, in this embodiment, the strain gauge is a purchased part, and two center line point marks a and b, two wire grid positioning marks c and d, and two welding points e and f are marked on the strain gauge.

[0035] The square sensor for two-dimensional force control grinding in this embodiment has 16 strain gauges attached at the following locations: Strain gauges R1 and R5 are pasted on the left inner wall (the side close to the first strain beam 5) of the special-shaped hole on the fourth strain beam 8, and strain gauges R4 and R8 are pasted on the right inner wall (the side close to the second strain beam 6). Strain gauges R2 and R6 are pasted on the left inner wall (the side close to the first strain beam 5) of the third strain beam 7, and strain gauges R3 and R7 are pasted on the right inner wall (the side close to the second strain beam 6). Among them, strain gauges R1 and R4 are symmetrical about the Y axis, strain gauges R5 and R8 are symmetrical about the Y axis, strain gauges R2 and R3 are symmetrical about the Y axis, strain gauges R6 and R7 are symmetrical about the Y axis, strain gauges R1 and R2 are symmetrical about the X axis, strain gauges R5 and R6 are symmetrical about the X axis, strain gauges R4 and R3 are symmetrical about the X axis, strain gauges R8 and R7 are symmetrical about the X axis, and the welding points of strain gauges R1, R5, R4, and R8 are symmetrical about the Y axis. In the Y direction, the welding points of strain gauges R2, R6, R3, and R7 are facing the +Y direction. The distance L1 between the center line positioning mark of strain gauge R5 and the force-bearing platform is 14.35mm, and the distance L2 between the center line positioning mark of strain gauge R5 and the center line positioning mark of strain gauge R1 is 1.9mm. Similarly, the distance between the center line positioning mark of strain gauge R8 and the force-bearing platform is 14.35mm, and the distance between the center line positioning mark of strain gauge R8 and the center line positioning mark of strain gauge R4 is 1.9mm; the distance between the center line positioning mark of strain gauge R6 and the force-bearing platform is 14.35mm, and the distance between the center line positioning mark of strain gauge R6 and the center line positioning mark of strain gauge R2 is 1.9mm; the distance between the center line positioning mark of strain gauge R7 and the force-bearing platform is 14.35mm, and the distance between the center line positioning mark of strain gauge R7 and the center line positioning mark of strain gauge R3 is 1.9mm. The distance L3 between the wire grid positioning mark of strain gauge R5 and the wire grid positioning mark of strain gauge R6 is 102.8mm. Similarly, the distance between the wire grid positioning mark of strain gauge R1 and the wire grid positioning mark of strain gauge R2 is 102.8mm. The distance between the wire grid positioning mark of strain gauge R4 and the wire grid positioning mark of strain gauge R3 is 102.8mm. The distance between the wire grid positioning mark of strain gauge R8 and the wire grid positioning mark of strain gauge R7 is 102.8mm. Figure 7 , 8 and 9.

[0036] A strain gauge R13 is pasted on the back of the left beam of the fourth strain beam 8 (the fourth strain beam 8 is divided by the setting of the special-shaped hole, and the left beam here is the beam close to the first strain beam 5), and a strain gauge R14 is pasted on the front of the right beam of the fourth strain beam 8 (the beam close to the second strain beam 6). A strain gauge R15 is pasted on the front of the left beam of the third strain beam 7 (the side close to the first strain beam 5), and a strain gauge R16 is pasted on the back of the right beam of the third strain beam 7 (the side close to the second strain beam 6). Paste the strain gauge R16, paste the strain gauge R10 on the front of the upper beam of the first strain beam 5 (the side close to the fourth strain beam 8), paste the strain gauge R9 on the back of the lower beam of the first strain beam 5 (the side close to the third strain beam 7), paste the strain gauge R11 on the front of the lower beam of the second strain beam 6 (the side close to the strain beam 7), paste the strain gauge R12 on the back of the upper beam of the second strain beam 6 (the side close to the fourth strain beam 8), where the strain gauges R13 and R16 are antisymmetric about the Y axis , the wire grid positioning mark distance L4 is 95.2mm, strain gauges R14 and R15 are antisymmetric about the Y axis, the wire grid positioning mark distance is 95.2mm, strain gauges R10 and R11 are antisymmetric about the X axis, the wire grid positioning mark distance is 95.2mm, strain gauges R12 and R9 are antisymmetric about the X axis, the wire grid positioning mark distance is 95.2mm, strain gauges R14 and R13 solder points are facing the -Y direction, strain gauges R15 and R16 solder points are facing the +Y direction, strain gauges R11 and R12 solder points are facing the + In the X direction, the welding points of strain gauges R10 and R9 face the -X direction, the center line positioning mark of strain gauge R13 is L5=5mm away from the Y axis, and the center line positioning mark of R14 is 5mm away from the Y axis, the center line positioning mark of R15 is 5mm away from the Y axis, the center line positioning mark of R16 is 5mm away from the Y axis, the center line positioning mark of R10 is 5mm away from the X axis, the center line positioning mark of R9 is 5mm away from the X axis, the center line positioning mark of R11 is 5mm away from the X axis, and the center line positioning mark of R12 is 5mm away from the X axis; Figure 7 , 8 , 9 and 10.

[0037] The square sensor in this embodiment is specially used for force-controlled grinding of two-dimensional forces, and its measuring range is: Fy=1000N; Fz=1000N.

[0038] The square sensor for two-dimensional force in this embodiment is specially used for force-controlled grinding, and its shape is 130mm*130mm*22mm (height). It is specially used in the force-controlled grinding industry to measure tangential force and normal force, and the measuring range is 1000N. After the modal analysis of the elastic body by ANSYSWorkbench, the natural frequency of the elastic body is 1759Hz, which has good dynamic performance.

[0039] The specific process of modal analysis of elastic body using ANSYS Workbench is as follows: As mentioned above, Fy and Fz adopt the full-bridge solution and perform simulation calculations in ANSYS Workbench. Full-scale loading is performed in each direction separately, and the strength of each direction when fully loaded is calculated. Because the selected material is stainless steel 17-4PH, after a certain heat treatment process, the yield strength is not less than 1300MPa, so the equivalent stress value obtained by simulation calculation must be less than the yield strength of 1300MPa, and the output sensitivity of each bridge is calculated separately. When calculating the sensitivity of each bridge, the motherboard 4 supplies 12V to the bridge.

[0040] When loading Fy=1000N, Fig.11 and 12 As shown: When the elastic body 1 is subjected to the lateral force Fy, the fourth strain beam 8 is subjected to tensile stress, the third strain beam 7 is subjected to compressive stress, R1, R4, R5 and R8 are subjected to tensile strain, R2, R3, R6 and R7 are subjected to compressive strain, and the components Figure 6 The first Huishitong bridge in the calculation is calculated by ANSYS Workbench. The equivalent stress is 88.653Mpa, the deformation is 0.0055393mm, and the strain measured by R1 is , the strain measured by R2 is , the strain measured by R3 is , the strain measured by R4 is , the strain measured by R5 is , the strain measured by R6 is , the strain measured by R7 is , the strain measured by R8 is ,but:

[0041] ——Indicates the output voltage value in the Fy direction when Fy is fully loaded; ——Indicates the sensitivity coefficient of the strain gauge. The average value is usually taken when calculating, and k=2; ——Indicates the strain measured in the patch area of ​​strain gauge R1; ——Indicates the strain measured in the patch area of ​​strain gauge R2; ——Indicates the strain measured in the patch area of ​​strain gauge R3; ——Indicates the strain measured in the patch area of ​​strain gauge R4; ——Indicates the strain measured in the patch area of ​​strain gauge R5; ——Indicates the strain measured in the patch area of ​​strain gauge R6; ——Indicates the strain measured in the patch area of ​​strain gauge R7; ——Indicates the strain measured in the patch area of ​​strain gauge R8; ——represents the excitation voltage of the bridge circuit, here we take ; Then the output sensitivity in the Fy direction is:

[0042] When loading Fz=1000N, Fig.13 and 14 As shown: All four strain beams are bent, R9, R12, R13 and R16 are tensile strained, R10, R11, R13 and R15 are compressive strained, and the composition Figure 6 The second Wheatstone bridge in the circuit is calculated by ANSYS Workbench. The equivalent stress is 105.48Mpa, the deformation is 0.010273mm, and the strain measured by R9 is , the strain measured by R10 is , the strain measured by R11 is , the strain measured by R12 is , the strain measured by R13 is , the strain measured by R14 is , the strain measured by R15 is , the strain measured by R16 is ,but:

[0043] ——Indicates the output voltage value in the Fz direction when Fz is fully loaded; ——Indicates the sensitivity coefficient of the strain gauge. The average value is usually taken when calculating, and k=2; ——Indicates the strain measured in the patch area of ​​strain gauge R9; ——Indicates the strain measured in the patch area of ​​strain gauge R10; ——Indicates the strain measured in the patch area of ​​strain gauge R11; ——Indicates the strain measured in the patch area of ​​strain gauge R12; ——Indicates the strain measured in the patch area of ​​strain gauge R13; ——Indicates the strain measured in the patch area of ​​strain gauge R14; ——Indicates the strain measured in the patch area of ​​strain gauge R15; ——Indicates the strain measured in the patch area of ​​strain gauge R16; ——represents the excitation voltage of the bridge circuit, here we take ; Then the output sensitivity in the Fz direction is:

[0044] The square sensor specially used for force-controlled grinding of two-dimensional force in this embodiment adopts 485 communication during calibration. The sensor is calibrated according to the "Calibration Specification for Multi-Component Force Sensors" (Standard No.: JJF 1560-2016). The calibration calculation results are shown in Table 1 below.

[0045] Table 1

[0046] In summary, according to the calibration data in Table 1, it is shown that the two-dimensional force square sensor specially used for force-controlled grinding in this embodiment has high precision and excellent performance, and is suitable for use in the force-controlled grinding industry.

[0047] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A two-dimensional force square sensor specially used for force-controlled polishing, characterized in that: It comprises an elastic body (1) which is in the shape of a square as a whole, an upper cover plate (2), a lower cover plate (3) and a main plate (4), The elastic body (1) comprises an elastic body hub, a force-bearing platform and four strain beams; the elastic body hub is square and has a circular hole at the center; the force-bearing platform is placed in the circular hole; and the four strain beams are evenly distributed between the force-bearing platform and the elastic body hub; an upper cover plate (2) and a lower cover plate (3) are arranged at the upper and lower ends of the elastic body (1), and the force-bearing platform protrudes from the upper cover plate (2); a main board (4) is placed below the upper cover plate (2) and is detachably connected to the elastic body hub; A plurality of strain gauges are attached to the four strain beams to form two Wheatstone bridges, which respectively measure the forces in the two directions of the tangential force Fy and the normal force Fz; the two Wheatstone bridges are connected to a main board (4), the main board (4) supplies power to the bridge circuit and collects data, and an EtherCat communication line and a power cable including a power line and a 485 communication line are connected to the main board (4).

2. The two-dimensional force square sensor specially used for force-controlled polishing according to claim 1 is characterized in that: A stress isolation groove (9) is provided on the lower end surface of the elastic body (1).

3. The two-dimensional force square sensor specially used for force-controlled polishing according to claim 2 is characterized in that: The depth of the stress isolation groove (9) is 1 mm.

4. The two-dimensional force square sensor specially used for force-controlled polishing according to claim 1 is characterized in that: The four strain beams are respectively located at the middle positions of the four sides of the square elastic hub.

5. The two-dimensional force square sensor specially used for force-controlled grinding according to claim 1 is characterized in that: Special-shaped holes are provided on the four strain beams.

6. The two-dimensional force square sensor specially used for force-controlled grinding according to claim 5 is characterized in that: 16 strain gauges are pasted on the four strain beams, and the strain gauges are bonded to the surface of the four strain beams and the inner wall of the special-shaped hole; the 16 strain gauges are R1~R16 respectively, among which R1~R8 form a full-bridge measurement Fy, and R9~R16 form a full-bridge measurement Fz.

7. The two-dimensional force square sensor specially used for force-controlled grinding according to claim 1 is characterized in that: An elliptical center hole is provided on the force-bearing platform.

8. The two-dimensional force square sensor specially used for force-controlled grinding according to claim 1 is characterized in that: The elastic body (2) is provided with a recessed groove for receiving the main board (4), and the upper cover plate (1) and the lower cover plate (3) are respectively embedded in the grooves on the upper and lower end surfaces of the elastic body (2) and glued together.

9. The two-dimensional force square sensor specially used for force-controlled grinding according to claim 1, characterized in that: The material of the elastic body (1) is stainless steel.

10. The two-dimensional force square sensor specially used for force-controlled grinding according to claim 1, characterized in that: The EtherCat communication cable and the power cable are both passed through the waterproof connector and connected to the two threaded holes on the elastic body (1). The waterproof connector is set in the threaded holes.

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