Hob cutter shaft three-way force measuring and decoupling method

Abstract

The invention discloses a hobbing cutter shaft three-way force measuring and decoupling method, which belongs to the technical field of intelligent shield tunneling, and comprises the following steps: S1, cutter shaft structure processing and pretreatment; s2, strain gauges are installed, the strain gauges are pasted in the strain grooves according to the Wheatstone bridge principle, and the strain gauges are welded and connected according to a bridge structure; s3, rolling force, vertical force and lateral force are measured, the rolling force is measured independently, decoupling measurement is conducted on the vertical force and the lateral force, and measurement data are obtained; and S4, applying a standard load to the cutter shaft, collecting strain data, establishing a calibration curve, correcting a non-linear error of the sensor, and predicting the wear condition of the cutter based on the measurement data in the step S3 to guarantee the construction safety. According to the hobbing cutter shaft three-way force measuring and decoupling method, precise decoupling is achieved through combination of a mechanical model and the least square method, cutter abrasion can be predicted, construction safety is guaranteed, and environmental adaptability is high.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of intelligent shield, and particularly relates to a method for measuring and decoupling three-directional forces of a cutter shaft of a disc cutter. BACKGROUND

[0002] In a tunneling project, a disc cutter system of a shield machine / TBM is a core component for breaking rock and soil layers, and its force state (including vertical force, rolling force and lateral force) directly affects tunneling efficiency, cutter life and construction safety.

[0003] However, the prior art has the following disadvantages: in the traditional technology, sensors are installed on a disc cutter support structure (such as a C-shaped block), the force transmission path is long and is easily affected by eccentric load, resulting in a large deviation between the measured value and the actual force. In addition, temperature changes and differences in the position of the strain gauges can further amplify the error, making it difficult to accurately reflect the real-time force state of the disc cutter; in the construction environment, dust, vibration and alternating loads frequently act on the external sensors, which are prone to signal drift or failure, especially when tunneling in complex rock layers, the durability of the sensors faces severe challenges; the sensors on the support structure need to be wired across regions, the cables are easily damaged by mechanical wear or mud erosion, and when multiple sensors are used for collaborative measurement, the wiring logic is complex and the maintenance cost is high; the existing method cannot independently decouple the three-directional forces, and the measurement of the vertical force and the lateral force is severely coupled, which requires complex algorithms for compensation, increasing the uncertainty of data processing.

[0004] Therefore, there is an urgent need for a new method. SUMMARY

[0005] The purpose of the application is to provide a method for measuring and decoupling three-directional forces of a cutter shaft of a disc cutter, which can accurately decouple through a mechanical model combined with the least square method, predict cutter wear, ensure construction safety, and has strong environmental adaptability.

[0006] To achieve the above purpose, the application provides a method for measuring and decoupling three-directional forces of a cutter shaft of a disc cutter, comprising the following steps:

[0007] S1, cutter shaft structure processing and pretreatment;

[0008] S2, installing strain gauges, according to the Wheatstone bridge principle, pasting strain gauges in the strain grooves, and welding the strain gauges according to the bridge structure;

[0009] S3, measuring rolling force, vertical force and lateral force, separately measuring the rolling force, and decoupling and measuring the vertical force and the lateral force to obtain measurement data;

[0010] S4, applying a standard load to the cutter shaft, collecting strain data and establishing a calibration curve to correct the non-linear error of the sensor, predicting the cutter wear condition based on the measurement data in S3 to ensure construction safety.

[0011] Preferably, in S1, four strain grooves are machined at the two ends of the hob shaft where they contact the inner ring of the bearing. The inner wall of the strain grooves and the patch position are ground and cleaned. Through holes pointing to the axis are machined in the four strain grooves respectively. An axial through groove is opened along the axis of the hob shaft, passing through both ends of the hob shaft.

[0012] Preferably, in S2, the cable is led out through the through hole in the strain gauge and the wire groove of the shaft core, and the end of the cable is connected to the signal conditioning module.

[0013] Preferably, in S3, the rolling force is measured separately by attaching strain gauges at four points before and after the four patch positions to form a Wheatstone full-bridge circuit, directly measuring the strain caused by the rolling force, and obtaining the rolling force value after signal conversion.

[0014] Preferably, in S3, the vertical force and lateral force are decoupled and measured. The cutter shaft is simplified into a beam structure. Based on the principles of force balance and bending moment balance, the reaction force and bending moment of the cutter shaft under the action of vertical force and lateral force are analyzed. The strain values ​​of four strain gauges are collected through a four-way full-bridge circuit, and a linear matrix equation of strain and force is established. The overdetermined equation system is solved by the least squares method to achieve decoupling of vertical force and lateral force.

[0015] Preferably, in S3, the calculation formulas for the force balance and moment balance principles are as follows:

[0016]

[0017] Among them, F N1 F is the vertical reaction force at point A of the tool axis. N2 is the vertical reaction force at point D of the tool axis; l is the distance between the support points A and D at both ends of the tool axis; r is the radius of the lateral force; F z For vertical force; F x This is a lateral force.

[0018] Preferably, in S3, the process of establishing the linear matrix equations of strain and force is as follows:

[0019] Based on the stress conditions of the beam, the bending moment at any point can be expressed as:

[0020]

[0021] Where M(x) is the bending moment of the cutter shaft at position x; x is the position coordinate on the cutter shaft;

[0022] The deflection of the beam is solved using the bending moment differential equation, and the calculation formula is as follows:

[0023]

[0024] Where E is the elastic modulus of the cutter shaft material; I is the moment of inertia of the cutter shaft cross section; after two integrations, we get:

[0025]

[0026] Wherein, y(x) is the deflection of the tool shaft at position x; C1, C2 are the first segment integral constant; C3, C4 are the second segment integral constant; Since the deflection and the rotation angle of points A and D are both 0, it is simplified as:

[0027]

[0028] The calculation formula of the deflection of points B and C is:

[0029]

[0030] Wherein, y B is the deflection of the tool shaft at point B; y c is the deflection of the tool shaft at point C; a is the distance from point B to point A of the tool shaft; b is the distance from point C to point D of the tool shaft; taking the tool shaft as a whole, the calculation formula of the deflection of points Bload and Cload is:

[0031]

[0032] Wherein, y Bload is the deflection of point Bload; r Cload is the deflection of point Cload; P load1 is the load 1 acting on the tool shaft; P load2 is the load 2 acting on the tool shaft; the deflection of points Bload and Cload of the tool shaft is equal to the deflection of points B and C, and P load1 and P load2 are obtained.

[0033] According to the force balance and the bending moment balance, the counterforce of points Aload and Dload, i.e. F loadN1 and F loadN2 , are calculated, and the calculation formula is:

[0034]

[0035] Wherein, l load is the distance between the support points Aload and Dload of the tool shaft; after simplification, it is:

[0036]

[0037] The calculation formula of the bending moment of each point is:

[0038]

[0039] Wherein, M load(x) is the bending moment of the tool shaft at position x caused by the load; the relationship between the curvature κ(x) and the bending moment of the beam is expressed as:

[0040]

[0041] The strain values (ε1, ε2, ε3, ε4) of the four strain grooves are collected by a four-way full-bridge circuit as the basic data for decoupling calculation; for any point strain ε, it is expressed as:

[0042] ε(x) = ± y·κ(x);

[0043] Wherein, y is the vertical distance from the neutral axis to the measurement point; for a cylindrical section, y is equal to the cylindrical radius R; ε(x) is the strain of the tool shaft surface at position x. When only P load1 exists, the calculation formula of the strain value is:

[0044]

[0045] Wherein, ε1(x), ε2(x), ε3(x), ε4(x) are the strain values of the four measurement points on the tool shaft surface, in turn, points 1 to 4; x1, x2, x3, x4 are the position coordinates of the four measurement points on the tool shaft; when only P load2 exists, the calculation formula of the strain value is:

[0046]

[0047] According to the superposition principle of elastic small deformation, the vertical force and the lateral force are decomposed into P load1 and P load2 , and a linear matrix equation of strain and force is established:

[0048] ε i = f i1 (P load1 )+ f i2 (P load2 )(i = 1, 2, 3, 4);

[0049] ε = A·P;

[0050] Wherein, ε = [ε1, ε2, ε3, ε4] T ; A is a 4×2 coefficient matrix composed of the contribution coefficients of each force to the strain; ε i is the strain value of the i-th measurement point on the tool shaft surface; f i1 is the contribution coefficient of load 1 to the strain of the i-th measurement point; f i2 is the contribution coefficient of load 2 to the strain of the i-th measurement point; A is composed of f i1 and f i2 , and is expressed as:

[0051]

[0052] Preferably, in S3, the least squares method is used to solve the overdetermined system of equations, and the calculation formula is as follows:

[0053]

[0054] in, This is the predicted strain value for the first measurement point; This is the predicted strain value for the second measurement point; This is the predicted strain value for the third measurement point; This is the predicted strain value for the 4th measurement point;

[0055] P=(A T A) -1 A T ε;

[0056] Where P is the unknown load vector.

[0057] Therefore, the present invention employs the above-mentioned method for measuring and decoupling the three-dimensional force of a hobbing cutter shaft. Compared with the prior art, the present invention has the following significant advantages:

[0058] (1) The present invention achieves direct contact with the force-bearing part by embedding a sensor in the slot of the cutter shaft, shortens the force transmission path, avoids the deviation of indirect measurement by the support structure, and improves the measurement accuracy;

[0059] (2) The built-in sensor of the present invention is protected by the cutter shaft structure, which reduces the impact of dust, mud and mechanical impact, and improves the service life of the equipment.

[0060] (3) The present invention has an axial routing hole in the center of the cutter shaft, and the cable is led out in a concentrated manner through the internal channel, which reduces the wiring length and reduces the risk of external wear;

[0061] (4) This invention utilizes the principles of force balance and moment balance to construct a mechanical model, and combines the least squares method to solve the overdetermined equations, thereby achieving precise decoupling of vertical force and lateral force.

[0062] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0063] Figure 1 This is a cross-sectional view of a hob according to the present invention, which describes a method for measuring and decoupling the three-dimensional force on a hob shaft.

[0064] Figure 2 This is a schematic diagram of the patch position of the support mechanism for a hobbing cutter shaft triaxial force measurement and decoupling method according to the present invention;

[0065] Figure 3 This is a diagram showing the internal wiring structure of the telescopic mechanism of the hob shaft in the present invention, which is a method for measuring and decoupling three-dimensional force on a hob shaft.

[0066] Figure 4 This is a schematic diagram of the force on the hob in the telescopic mechanism of the hob shaft triaxial force measurement and decoupling method of the present invention.

[0067] Figure 5 This is a simplified mechanical model of the telescopic mechanism of the hob shaft in the present invention, which is a method for measuring and decoupling three-dimensional force on the hob shaft.

[0068] Figure 6 This is a schematic diagram of the force on the cutter shaft of the telescopic mechanism of the hob shaft in the present invention, which is a method for measuring and decoupling three-dimensional force on the cutter shaft.

[0069] Figure 7 This is a simplified mechanical model of the load sensor of the telescopic mechanism in the hobbing cutter shaft three-dimensional force measurement and decoupling method of the present invention.

[0070] Figure Labels

[0071] 1. Hob cutter shaft; 21. First strain groove; 22. Second strain groove; 23. Third strain groove; 24. Fourth strain groove; 3. Wire guide groove. Detailed Implementation

[0072] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used in the present invention should have the ordinary meaning understood by those skilled in the art.

[0073] Example 1

[0074] like Figures 1-7 As shown, the present invention provides a method for measuring and decoupling the three-dimensional force of a hob shaft, comprising the following steps:

[0075] S1. Four strain grooves are machined at both ends of the hob shaft 1 (the part that contacts the inner ring of the bearing), namely the first strain groove 21, the second strain groove 22, the third strain groove 23 and the fourth strain groove 24. The position of the strain grooves should correspond to the area of ​​maximum deformation of the hob shaft under stress to ensure that the strain gauge can capture significant deformation. The inner wall of the strain groove and the patching position are ground and cleaned to remove burrs and oil stains, ensuring that the strain gauge is firmly attached and avoiding measurement errors caused by surface roughness.

[0076] Through holes pointing towards the axis are machined in the first strain groove 21, the second strain groove 22, the third strain groove 23 and the fourth strain groove 24 respectively, to facilitate subsequent sensor wiring; an axial through groove 3 is opened along the axis of the hob shaft 1, passing through both ends of the hob shaft 1, for signal cable wiring of the integrated strain gauge, simplifying external wiring.

[0077] S2. Select high-precision, wear-resistant strain gauges. Based on the Wheatstone bridge principle, attach strain gauges at the points of maximum strain within the strain groove (such as the upper and lower ends of the groove). The placement of the strain gauges must correspond to the compression or tensile strain regions. Use full-bridge or half-bridge placement methods to ensure that the strains on each bridge are opposite. For example, attach one strain gauge to the upper or lower end of each of the four strain grooves, for a total of four gauges, forming a four-way Wheatstone full-bridge circuit for measuring vertical and lateral forces; attach strain gauges at four points at the front and rear to form a full-bridge circuit for separately measuring rolling forces.

[0078] The strain gauges are welded together in a bridge structure (e.g., a full bridge circuit requires 4 strain gauges, and a half bridge requires 2). The cables are led out through the through holes in the strain gauge and the shaft core through the wire groove 3 to avoid interference from the external construction environment. Shielded cables are used to reduce electromagnetic interference. The cable ends are connected to signal conditioning modules (such as amplifiers and filters) to ensure signal stability.

[0079] S3. For the measurement of rolling force, since rolling force is not coupled with vertical force and lateral force, strain gauges can be attached to four points before and after the four patch positions to form a Wheatstone full-bridge circuit, and the strain caused by rolling force can be directly measured. After signal conversion, the rolling force value can be obtained.

[0080] To decouple the measurement of vertical and lateral forces, the cutter shaft is simplified as a beam structure. Based on the principles of force and moment balance, the vertical force F of the cutter shaft is analyzed. z and lateral force F x The reaction force and bending moment under action. Figure 5 For example, by calculating the reaction forces at points A and D through moment equilibrium at point A, and then solving for the deflection and strain at each point using the beam's moment differential equation, the calculation formula is as follows:

[0081]

[0082] Among them, F N1 F is the vertical reaction force at point A (left end) of the cutter shaft; N2 is the vertical reaction force at point D (right end) of the tool axis; l is the distance between the support points A and D at both ends of the tool axis; r is the radius of the lateral force; F z For vertical force; F x It is a lateral force;

[0083] Based on the stress conditions of the beam, the bending moment at any point can be expressed as:

[0084]

[0085] Where M(x) is the bending moment of the cutter shaft at position x; x is the position coordinate on the cutter shaft;

[0086] The deflection of the beam is solved using the bending moment differential equation, and the calculation formula is as follows:

[0087]

[0088] Where E is the elastic modulus of the cutter shaft material; I is the moment of inertia of the cutter shaft cross section; after two integrations, we get:

[0089]

[0090] Where y(x) is the deflection (vertical deformation) of the cutter shaft at position x; C1 and C2 are the first integration constants; C3 and C4 are the second integration constants; since the deflection and rotation angle at points A and D are both 0, the result simplifies to:

[0091]

[0092] The formulas for calculating the deflection at points B and C are:

[0093]

[0094] Among them, y B y is the deflection of the cutter shaft at point B; c Let be the deflection of the cutter shaft at point C; be the distance from point B to the left end of the cutter shaft (point A); and be the distance from point C to the right end of the cutter shaft (point D). Analyzing the cutter shaft as a whole, the force diagram and mechanical model of the cutter shaft are as follows: Figure 6 and Figure 7 As shown; the deflection calculation formulas at points Bload and Cload are as follows:

[0095]

[0096] Among them, y Bload y is the deflection at the load point; Cload P is the deflection at point Cload; load1 The load acting on the tool shaft is 1; P load2 Given the load 2 acting on the tool shaft; the deflection at points Bload and Cload is equal to the deflection at points B and C, P can be calculated. load1 and P load2 ;

[0097] The reaction forces at points Aload and Dload, i.e., F, are calculated based on force balance and moment balance. loadN1 and F loadN2 The calculation formula is:

[0098]

[0099] Among them, l load Let Aload and Dload be the distance between the support points Aload and Dload at both ends of the tool shaft; after simplification, we get:

[0100]

[0101] The formulas for calculating the bending moment at each point are:

[0102]

[0103] Among them, M load (x) represents the bending moment caused by the load on the cutter shaft at position x; the relationship between the curvature κ(x) and the bending moment of the beam is expressed as:

[0104]

[0105] The strain values ​​(ε1, ε2, ε3, ε4) of four strain gauges are acquired using a four-channel full-bridge circuit as the basis for decoupling calculations; the strain ε at any point is expressed as:

[0106] ε(x)=±y·κ(x);

[0107] Where y is the perpendicular distance from the neutral axis to the measurement point; for a cylindrical section, y is equal to the cylinder radius R; ε(x) is the strain on the tool axis surface at position x. When only P exists... load1 When the strain value is calculated, the formula is:

[0108]

[0109] Where ε1(x), ε2(x), ε3(x), and ε4(x) are the strain values ​​at four measurement points on the tool shaft surface (points 1 to 4 in sequence); x1, x2, x3, and x4 are the position coordinates of the four measurement points on the tool shaft; when only P exists... load2 When the strain value is calculated, the formula is:

[0110]

[0111] Based on the principle of superposition of small elastic deformations, the vertical force and lateral force are decomposed into P. load1 and P load2 Establish the linear matrix equations of strain and force:

[0112] ε i =f i1 (P load1 )+f i2 (P load2 (i = 1, 2, 3, 4);

[0113] ε = A·P;

[0114] Among them, ε = [ε1, ε2, ε3, ε4] T A is a 4×2 coefficient matrix, consisting of the contribution coefficients of each force to the strain; ε i f is the strain value at the i-th measurement point on the tool shaft surface; i1 f is the contribution coefficient of load 1 to the strain at the i-th measurement point; i2 Let A be the contribution coefficient of load 2 to the strain at the i-th measurement point; A is determined by f i1 and f i2 Composition, represented as:

[0115]

[0116] Since the equations are an overdetermined system of equations (4 strain equations, 2 unknown forces), the least squares method is used to minimize the sum of squared errors to solve for P. load1 and P load2 Then, the vertical force F is derived in reverse. z and lateral force F x The calculation formula is:

[0117]

[0118] in, This is the predicted strain value for the first measurement point; This is the predicted strain value for the second measurement point; This is the predicted strain value for the third measurement point; This is the predicted strain value for the 4th measurement point;

[0119] P=(A T A) -1 A T ε;

[0120] Where P is the unknown load vector.

[0121] S4. Before formal use, apply a standard load (known triaxial force) to the cutter shaft, collect strain data and establish a calibration curve to correct the nonlinear error of the sensor and improve measurement accuracy; and record the triaxial force data in real time through the data acquisition system, and analyze the force state of the cutter head by combining it with the tunneling parameters of the tunnel boring machine (such as thrust speed and rotation speed); optimize the construction parameters (such as adjusting thrust and rotation speed) based on the measurement data, predict the wear of the cutter head, extend the life of the cutter head, and ensure construction safety.

[0122] Therefore, the present invention adopts the above-mentioned method for measuring and decoupling the three-dimensional force of the hobbing cutter shaft. This method achieves accurate decoupling by combining a mechanical model with the least squares method, which can predict tool wear, ensure construction safety, and has strong environmental adaptability.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for measuring and decoupling the three-dimensional force on a hob shaft, characterized in that, Includes the following steps: S1. Machining and pretreatment of the cutter shaft structure; S2. Install strain gauges. According to the Wheatstone bridge principle, paste the strain gauges into the strain groove and weld the strain gauges together according to the bridge structure. S3. Measure rolling force, vertical force and lateral force. Measure rolling force separately and decouple vertical force and lateral force to obtain measurement data. S4. Apply a standard load to the tool shaft, collect strain data and establish a calibration curve, correct the nonlinear error of the sensor, and predict the tool wear based on the measurement data in S3 to ensure construction safety.

2. The method for measuring and decoupling the three-dimensional force of a hobbing cutter shaft according to claim 1, characterized in that, In S1, four strain grooves are machined at the two ends of the hob shaft where they contact the inner ring of the bearing. The inner wall of the strain grooves and the patch position are ground and cleaned. Through holes pointing to the axis are machined in the four strain grooves respectively. An axial through groove is opened along the axis of the hob shaft, passing through both ends of the hob shaft.

3. The method for measuring and decoupling the three-dimensional force of a hobbing cutter shaft according to claim 2, characterized in that, In S2, the cable is led out through the through hole in the strain gauge and the wire groove of the shaft core, and the end of the cable is connected to the signal conditioning module.

4. The method for measuring and decoupling the three-dimensional force of a hobbing cutter shaft according to claim 3, characterized in that, In S3, the rolling force is measured separately. By attaching strain gauges at four points before and after the four patch positions, a Wheatstone full-bridge circuit is formed to directly measure the strain caused by the rolling force. The rolling force value is obtained after signal conversion.

5. The method for measuring and decoupling the three-dimensional force of a hobbing cutter shaft according to claim 4, characterized in that, In S3, the vertical force and lateral force are decoupled and measured. The cutter shaft is simplified into a beam structure. Based on the principles of force balance and bending moment balance, the reaction force and bending moment of the cutter shaft under the action of vertical force and lateral force are analyzed. The strain values ​​of four strain gauges are collected through a four-way full-bridge circuit. A linear matrix equation of strain and force is established. The overdetermined equation system is solved by the least squares method to achieve decoupling of vertical force and lateral force.

6. The method for measuring and decoupling the three-dimensional force of a hobbing cutter shaft according to claim 5, characterized in that, In S3, the calculation formulas for the principles of force balance and moment balance are as follows: Among them, F N1 F is the vertical reaction force at point A of the tool axis. N2 is the vertical reaction force at point D of the tool axis; l is the distance between the support points A and D at both ends of the tool axis; r is the radius of the lateral force; F z For vertical force; F x This is a lateral force.

7. The method for measuring and decoupling the three-dimensional force of a hobbing cutter shaft according to claim 6, characterized in that, In S3, the process of establishing the linear matrix equations of strain and force is as follows: Based on the stress conditions of the beam, the bending moment at any point can be expressed as: Where M(x) is the bending moment of the cutter shaft at position x; x is the position coordinate on the cutter shaft; The deflection of the beam is solved using the bending moment differential equation, and the calculation formula is as follows: Where E is the elastic modulus of the cutter shaft material; I is the moment of inertia of the cutter shaft cross section; after two integrations, we get: Where y(x) is the deflection (vertical deformation) of the cutter shaft at position x; C1 and C2 are the first integration constants; C3 and C4 are the second integration constants; since the deflection and rotation angle at points A and D are both 0, the result simplifies to: The formulas for calculating the deflection at points B and C are: Among them, y B y is the deflection of the cutter shaft at point B; c Let be the deflection of the tool axis at point C; be ; a is the distance from point B to point A on the tool axis; b is the distance from point C to point D on the tool axis; considering the tool axis as a whole, the formulas for calculating the deflection at points Bload and Cload are: Among them, y Bload y is the deflection at the load point; Cload P is the deflection at point Cload; load1 The load acting on the tool shaft is 1; P load2 The load 2 acting on the cutter shaft; The reaction forces at points Aload and Dload, i.e., F, are calculated based on force balance and moment balance. loadN1 and F loadN2 The calculation formula is: Among them, l load Let Aload and Dload be the distance between the support points Aload and Dload at both ends of the tool shaft; after simplification, we get: The formulas for calculating the bending moment at each point are: Among them, M load (x) represents the bending moment caused by the load on the cutter shaft at position x; the relationship between the curvature κ(x) and the bending moment of the beam is expressed as: The strain values ​​(ε1, ε2, ε3, ε4) of four strain gauges are acquired using a four-channel full-bridge circuit as the basis for decoupling calculations; the strain ε at any point is expressed as: ε(x)=±y·κ(x); Where y is the perpendicular distance from the neutral axis to the measurement point; for a cylindrical section, y is equal to the cylinder radius R; ε(x) is the strain on the tool axis surface at position x; when only P exists... load1 When the strain value is calculated, the formula is: Where ε1(x), ε2(x), ε3(x), and ε4(x) are the strain values ​​at four measurement points on the tool shaft surface, respectively, from point 1 to point 4; x1, x2, x3, and x4 are the position coordinates of the four measurement points on the tool shaft; when only P exists... load2 When the strain value is calculated, the formula is: Based on the principle of superposition of small elastic deformations, the vertical force and lateral force are decomposed into P. load1 and P load2 Establish the linear matrix equations of strain and force: ε i =f i1 (P load1 )+f i2 (P load2 )(i=1,2,3,4); ε = A·P; Among them, ε = [ε1, ε2, ε3, ε4] T A is a 4×2 coefficient matrix, consisting of the contribution coefficients of each force to the strain; ε i f is the strain value at the i-th measurement point on the tool shaft surface; i1 f is the contribution coefficient of load 1 to the strain at the i-th measurement point; i2 Let A be the contribution coefficient of load 2 to the strain at the i-th measurement point; A is determined by f i1 and f i2 Composition, represented as:

8. The method for measuring and decoupling the three-dimensional force of a hobbing cutter shaft according to claim 7, characterized in that, In S3, the least squares method is used to solve the overdetermined system of equations. The calculation formula is as follows: in, This is the predicted strain value for the first measurement point; This is the predicted strain value for the second measurement point; This is the predicted strain value for the third measurement point; This is the predicted strain value for the 4th measurement point; P=(A T A) -1 A T e; Where P is the unknown load vector.

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