Ultrasonic amplitude calculation and internal thread precision machining method in strong-constraint small space

Abstract

The invention discloses a strong-constraint small-space ultrasonic amplitude calculation and internal thread precision machining method, which comprises the following steps of: setting a plurality of different sets of process parameter preset values; determining the radial cutting force of the tool and the surface roughness value of the workpiece corresponding to each group of process parameter preset values, and determining the surface roughness value of the workpiece on the basis of the ultrasonic vibration amplitude function of the tail end of the tool constructed on the basis of the cutting force; determining an ultrasonic vibration amplitude corresponding to each group of process parameter preset values through a finite element simulation method; determining an optimal process parameter value based on the cutting force, the surface roughness value and the ultrasonic vibration amplitude corresponding to each group of process parameter preset values; and on the basis of the optimal process parameter value, the internal thread is machined, and the machining efficiency and precision of the internal thread are improved.

Description

Technical Field

[0001] This application relates to the technical fields of ultrasonic amplitude calculation and precision machining of internal threads in strongly constrained small spaces, and in particular to methods for ultrasonic amplitude calculation and precision machining of internal threads in strongly constrained small spaces. Background Technology

[0002] Small-diameter internal threads are key components in the transmission systems of high-end equipment, requiring high machining accuracy. Internally threaded tubes are typically difficult-to-machine materials with high heat generation per unit cutting step. Their length-to-diameter ratio exceeds 10:1, and their diameter is limited to 15mm, constraining tool rigidity and making them highly susceptible to deformation during machining. While ultrasonic assistance can significantly improve machining performance, researchers have proposed and designed ultrasonic tool holders. However, during internal thread machining, the significant eccentric load under gravity causes bending vibrations and static deformation of the ultrasonic tool holder to interfere with the relative motion path between the tool and the internally threaded tube, resulting in low machining accuracy and making it unsuitable for the precision machining requirements of small-diameter internal threads. Summary of the Invention

[0003] This application aims to at least address the technical problems existing in the prior art. To this end, this application proposes a method for calculating ultrasonic amplitude in a strongly constrained small space and for precision machining of internal threads, which can compensate for machining deformation and improve the machining efficiency and accuracy of internal threads.

[0004] The first aspect of this application provides a method for calculating ultrasonic amplitude and precision machining of internal threads in a strongly constrained small space, comprising the following steps: With several different preset values ​​of process parameters set, the cutting force of the tool radial direction and the surface roughness value of the workpiece corresponding to each preset value of process parameters are determined. The preset values ​​of each set of process parameters include the depth of cut, feed rate and the rotation speed of the threaded pipe. In the case of constructing the ultrasonic vibration amplitude function of the tool tip based on the cutting force, and based on the ultrasonic vibration amplitude function, the ultrasonic vibration amplitude corresponding to the preset value of each set of process parameters is determined by the finite element simulation method. Based on the cutting force, surface roughness value, and ultrasonic vibration amplitude corresponding to the preset values ​​of each set of process parameters, the optimal process parameter values ​​are determined. Based on the optimal process parameter values, the internal thread is machined.

[0005] The method for calculating ultrasonic amplitude in a strongly constrained small space and for precision machining of internal threads according to the embodiments of this application has at least the following beneficial effects: This method determines the radial cutting force of the tool and the surface roughness of the workpiece corresponding to each of several preset sets of process parameters. It then constructs an ultrasonic vibration amplitude function at the tool tip based on the cutting force and uses finite element simulation to determine the ultrasonic vibration amplitude corresponding to each preset set of process parameters. Based on the cutting force, surface roughness, and ultrasonic vibration amplitude corresponding to each preset set of process parameters, the optimal process parameter values ​​are determined. Finally, the internal thread is machined based on the optimal process parameter values. By constructing an ultrasonic vibration amplitude function at the tool tip, this application incorporates ultrasonic vibration amplitude into the process parameter optimization, compensating for machining deformation and improving the machining efficiency and accuracy of the internal thread.

[0006] According to some embodiments of this application, determining the optimal process parameter values ​​based on the cutting force, the surface roughness value, and the ultrasonic vibration amplitude corresponding to the preset values ​​of each set of process parameters includes: Based on the cutting force, the correlation between the process parameters, the surface roughness value, and the ultrasonic vibration amplitude is determined by a fitting method, wherein the correlation is used to characterize the numerical correlation between the process parameters, the surface roughness value, and the ultrasonic vibration amplitude; Based on the preset processing target, the correlation law, and the surface roughness value, the range of process parameter values ​​is determined; Select the group of preset process parameter values ​​from all groups of process parameter preset values ​​where the feed rate and the rotational speed of the threaded pipe are within the range of process parameter values, and the cutting depth is the largest, as the process parameter values ​​to be optimized; Determine the first deformation value and the corresponding first ultrasonic vibration amplitude of the process parameter to be optimized; If the sum of the first deformation value and the first ultrasonic vibration amplitude is less than a preset deviation threshold, and the value of the process parameter to be optimized is within the range of the process parameter values, then the value of the process parameter to be optimized is taken as the optimal process parameter value.

[0007] According to some embodiments of this application, after determining the first deformation value and the corresponding first ultrasonic vibration amplitude of the process parameter to be optimized, the method further includes: If the sum of the first deformation value and the first ultrasonic vibration amplitude is greater than or equal to the preset deviation threshold, the cutting depth of the process parameter to be optimized is reduced by a preset ratio to obtain the first modified cutting depth. Determine the second deformation value and the second ultrasonic vibration amplitude of the first modified cutting depth. If the sum of the second deformation value and the second ultrasonic vibration amplitude is greater than or equal to the preset deviation threshold, reduce the first modified cutting depth by the preset ratio to obtain the second modified cutting depth. Repeat this process until the sum of the (K-1)th deformation value and the (K-1)th ultrasonic vibration amplitude corresponding to the Kth modified cutting depth is less than the preset deviation threshold. Then determine whether the Kth modified cutting depth is within the range of the process parameters, where K is the iteration number. When the Kth modified cutting depth is within the range of the process parameter values, the Kth modified cutting depth, the feed rate of the process parameter to be optimized, and the threaded pipe rotation speed of the process parameter to be optimized are taken as the optimal process parameter values.

[0008] According to some embodiments of this application, determining the range of process parameters based on the preset processing target, the correlation rule, and the surface roughness value includes: A range of surface roughness values ​​is determined, wherein all surface roughness values ​​within the range are less than the preset processing target. Based on the surface roughness value range and the correlation rule, the value range of the process parameters is determined.

[0009] According to some embodiments of this application, the formula for calculating the ultrasonic vibration amplitude function is as follows:

[0010] in, The steady-state vibration amplitude, It is a constant related to parameters such as modal quality. Let be the mode shape function value of the m-th mode at position L along the length of the grinding tool, where L is the length of the grinding tool. To input the excitation amplitude, The angular frequency of ultrasonic vibration. Let m be the damping ratio of the m-th mode. Let be the natural angular frequency of the m-th mode. In order to be in The amplitude of ultrasonic vibration at time 10:00. The phase angle relative to the driving signal. In order to be in The amplitude of the transient vibration at time t. The phase angle of the transient vibration. The natural frequency is when damped.

[0011] According to some embodiments of this application, determining the deformation value of the process parameter to be optimized includes: Obtain the length, inner diameter, outer diameter, density, and elastic modulus of the grinding tool; Based on the length, inner diameter, outer diameter, and density of the grinding tool, the self-weight deformation force is calculated using the following formula:

[0012] in, The deformation force is due to its own weight. For the density of grinding tools, The gravitational coefficient, The length of the grinding tool. The outer diameter of the grinding tool. The inner diameter of the grinding tool; The total force is determined based on the self-weight deformation force and the cutting force corresponding to the values ​​of the process parameters to be optimized. Based on the total force and the elastic modulus of the grinding tool, the deformation value of the process parameter to be optimized is calculated using the following formula:

[0013] in, This is the deformation value. Let E be the total force, E be the elastic modulus of the grinding tool, and I be the interfacial polar moment of inertia.

[0014] According to some embodiments of this application, before setting several different preset values ​​for process parameters, the following steps are included: With the grinding point of the grinding wheel set at the vertical diameter of the internally threaded pipe, the initial rotational speed of the threaded pipe and the axial feed of the grinding wheel tool are determined so that the grinding point of the grinding wheel is always located at the vertical diameter of the internally threaded pipe. The setting of several different preset values ​​for process parameters includes: Based on the axial feed rate of the grinding wheel tool, the feed rate value in the preset values ​​of each set of process parameters is set; based on the initial rotational speed of the threaded pipe, the rotational speed value of the threaded pipe in the preset values ​​of each set of process parameters is set.

[0015] A second aspect of this application provides a system for calculating ultrasonic amplitude and precision machining of internal threads in a strongly constrained small space. The system includes: The surface roughness value determination module is used to determine the cutting force of the tool radial direction and the surface roughness value of the workpiece corresponding to each set of preset process parameter values, when several different sets of preset process parameter values ​​are set. The preset process parameter values ​​include the cutting depth, feed rate and the rotation speed of the threaded pipe. The ultrasonic vibration amplitude determination module is used to determine the ultrasonic vibration amplitude corresponding to the preset values ​​of each set of process parameters by means of finite element simulation, based on the ultrasonic vibration amplitude function of the tool end constructed based on the cutting force. The optimal process parameter value determination module is used to determine the optimal process parameter value based on the cutting force, the surface roughness value, and the ultrasonic vibration amplitude corresponding to the preset values ​​of each set of process parameters; The machining module is used to perform machining operations on the internal thread based on the optimal process parameter values.

[0016] This system determines the radial cutting force of the tool and the surface roughness of the workpiece corresponding to each of several preset sets of process parameters. It then constructs an ultrasonic vibration amplitude function at the tool tip based on the cutting force and uses finite element simulation to determine the ultrasonic vibration amplitude corresponding to each preset set of process parameters. Based on the cutting force, surface roughness, and ultrasonic vibration amplitude corresponding to each preset set of process parameters, the optimal process parameter values ​​are determined. Finally, based on the optimal process parameter values, internal threads are machined. This application incorporates ultrasonic vibration amplitude into the process parameter optimization by constructing an ultrasonic vibration amplitude function at the tool tip, compensating for machining deformation and improving the machining efficiency and accuracy of internal threads.

[0017] A third aspect of this application provides an electronic device for ultrasonic amplitude calculation and precision machining of internal threads in a tightly constrained small space, including at least one control processor and a memory for communicatively connecting to the at least one control processor; the memory stores instructions executable by the at least one control processor, which are executed by the at least one control processor to enable the at least one control processor to perform the above-described method for ultrasonic amplitude calculation and precision machining of internal threads in a tightly constrained small space.

[0018] In a fourth aspect, this application provides a computer-readable storage medium storing computer-executable instructions for causing a computer to perform the aforementioned method for calculating ultrasonic amplitude and precision machining of internal threads in a tightly constrained small space.

[0019] It should be noted that the beneficial effects of the second to fourth aspects of this application compared with the prior art are the same as the beneficial effects of the above-mentioned ultrasonic amplitude calculation and internal thread precision machining system in a strongly constrained small space compared with the prior art, and will not be described in detail here.

[0020] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0021] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a flowchart illustrating an embodiment of the ultrasonic amplitude calculation and internal thread precision machining method provided in this application within a strongly constrained small space. Figure 2 This is a schematic diagram of an embodiment of the ultrasonic amplitude calculation and internal thread precision machining system in a strongly constrained small space provided in this application; Figure 3 This is a schematic diagram of the structure of an embodiment of the electronic device provided in this application. Detailed Implementation

[0022] The embodiments of this application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0023] In the description of this application, the use of terms such as "first," "second," etc., is for the purpose of distinguishing technical features only and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or the order of the technical features indicated.

[0024] In the description of this application, it should be understood that the orientation descriptions, such as up, down, etc., are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0025] In the description of this application, it should be noted that, unless otherwise explicitly defined, terms such as "setup," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in conjunction with the specific content of the technical solution.

[0026] Small-diameter internal threads are key components in the transmission systems of high-end equipment, requiring high machining accuracy. Internally threaded tubes are typically difficult-to-machine materials with high heat generation per unit cutting step. Their length-to-diameter ratio exceeds 10:1, and their diameter is limited to 15mm, constraining tool rigidity and making them highly susceptible to deformation during machining. While ultrasonic assistance can significantly improve machining performance, researchers have proposed and designed ultrasonic tool holders. However, during internal thread machining, the significant eccentric load under gravity causes bending vibrations and static deformation of the ultrasonic tool holder to interfere with the relative motion path between the tool and the internally threaded tube, resulting in low machining accuracy and making it unsuitable for the precision machining requirements of small-diameter internal threads.

[0027] To address the aforementioned technical deficiencies, this application provides a method for calculating ultrasonic amplitude and precision machining of internal threads in a tightly constrained small space.

[0028] Please see Figure 1 This is a flowchart illustrating a method for calculating ultrasonic amplitude and precision machining of internal threads in a strongly constrained small space, as provided in an embodiment of this application. This method is applied to electronic devices, such as servers. Figure 1 As shown, the method for calculating ultrasonic amplitude and precision machining of internal threads in a strongly constrained small space includes: Step S101: Under the condition of setting several different preset values ​​of process parameters, determine the cutting force of the tool radial direction and the surface roughness value of the workpiece corresponding to each preset value of process parameters. The preset values ​​of each set of process parameters include the cutting depth, feed rate and the rotation speed of the threaded pipe. Step S102: Based on the ultrasonic vibration amplitude function of the tool tip constructed by the cutting force, and based on the ultrasonic vibration amplitude function, the ultrasonic vibration amplitude corresponding to the preset value of each set of process parameters is determined by the finite element simulation method. Step S103: Determine the optimal process parameter values ​​based on the cutting force, surface roughness value, and ultrasonic vibration amplitude corresponding to the preset values ​​of each set of process parameters; Step S104: Based on the optimal process parameter values, perform machining operations on the internal thread.

[0029] The preset values ​​of the above-mentioned sets of process parameters are all different. The different preset values ​​of the process parameters can be different cutting depths, different feed rates, and / or different rotation speeds of the threaded pipe.

[0030] In step S101 above, determining the cutting force of the tool radial direction and the surface roughness value of the workpiece corresponding to the preset values ​​of each set of process parameters can be achieved by conducting ultrasonic cutting tests and collecting the cutting force of the tool radial direction and the surface roughness value of the workpiece corresponding to the preset values ​​of each set of process parameters.

[0031] In step S102 above, the ultrasonic vibration amplitude corresponding to the preset values ​​of each set of process parameters is determined by the finite element simulation method based on the ultrasonic vibration amplitude function. This can be achieved by accurately determining the natural angular frequency ω of the tool based on the ultrasonic vibration amplitude function and the finite element simulation method. m , mode shape function value φ m (x) and damping ratio This allows us to determine the ultrasonic vibration amplitude corresponding to the preset values ​​of each set of process parameters.

[0032] In step S104 above, the internal thread can be machined based on the optimal process parameter values ​​by setting the optimal process parameter values ​​as the process parameter values ​​of the internal thread precision machining device, and then machining the internal thread using the internal thread precision machining device.

[0033] This method determines the radial cutting force of the tool and the surface roughness of the workpiece corresponding to each of several preset sets of process parameters. It then constructs an ultrasonic vibration amplitude function at the tool tip based on the cutting force and uses finite element simulation to determine the ultrasonic vibration amplitude corresponding to each preset set of process parameters. Based on the cutting force, surface roughness, and ultrasonic vibration amplitude corresponding to each preset set of process parameters, the optimal process parameter values ​​are determined. Finally, the internal thread is machined based on the optimal process parameter values. By constructing an ultrasonic vibration amplitude function at the tool tip, this application incorporates ultrasonic vibration amplitude into the process parameter optimization, compensating for machining deformation and improving the machining efficiency and accuracy of the internal thread.

[0034] In some embodiments, the optimal process parameter values ​​are determined based on the cutting force, surface roughness value, and ultrasonic vibration amplitude corresponding to the preset values ​​of each set of process parameters, including: Step S201: Based on the cutting force, the correlation between process parameters, surface roughness value and ultrasonic vibration amplitude is determined by fitting method. The correlation is used to characterize the numerical correlation between process parameters, surface roughness value and ultrasonic vibration amplitude. Step S202: Based on the preset processing target, correlation rules and surface roughness value, determine the range of process parameter values; Step S203: Select the set of preset process parameter values ​​from all sets of preset process parameter values ​​where the feed rate and the rotational speed of the threaded pipe are within the range of process parameter values ​​and the cutting depth is the largest, and use it as the set of process parameter values ​​to be optimized. Step S204: Determine the first deformation value and the corresponding first ultrasonic vibration amplitude of the process parameter to be optimized; Step S205: If the sum of the first deformation value and the first ultrasonic vibration amplitude is less than a preset deviation threshold, and the value of the process parameter to be optimized is within the range of process parameter values, then the value of the process parameter to be optimized is taken as the optimal process parameter value.

[0035] The aforementioned preset processing target can be a value pre-set according to actual needs, used to characterize the minimum process requirements for the surface roughness value of the internal thread.

[0036] In step S201 above, the correlation between process parameters, surface roughness value and ultrasonic vibration amplitude is determined by fitting method based on cutting force. Alternatively, the correlation between process parameters, surface roughness value and ultrasonic vibration amplitude can be determined by linear fitting method based on cutting force.

[0037] This application improves the machining efficiency and accuracy of internal threads by incorporating ultrasonic vibration amplitude into the optimization of process parameters to compensate for machining deformation.

[0038] In some embodiments, after determining the first deformation value and the corresponding first ultrasonic vibration amplitude of the process parameter to be optimized, the method further includes: Step S301: When the sum of the first deformation value and the first ultrasonic vibration amplitude is greater than or equal to a preset deviation threshold, the cutting depth of the process parameter to be optimized is reduced by a preset ratio to obtain the first modified cutting depth. Step S302: Determine the second deformation value and the second ultrasonic vibration amplitude of the first modified cutting depth. If the sum of the second deformation value and the second ultrasonic vibration amplitude is greater than or equal to a preset deviation threshold, reduce the first modified cutting depth by a preset ratio to obtain the second modified cutting depth. Continue in this manner until the sum of the (K-1)th deformation value and the (K-1)th ultrasonic vibration amplitude corresponding to the Kth modified cutting depth is less than the preset deviation threshold. Determine whether the Kth modified cutting depth is within the range of process parameter values, where K is the iteration number. Step S303: When the Kth modified cutting depth is within the range of process parameter values, the Kth modified cutting depth, the feed rate of the process parameter to be optimized, and the rotational speed of the threaded pipe of the process parameter to be optimized are taken as the optimal process parameter values.

[0039] The above preset ratio can be a value set in advance according to actual needs, and can be set to five percent.

[0040] Specifically, it may also include: when the Kth modified cutting depth is not within the range of process parameter values, the Kth modified cutting depth is reduced by a preset ratio to obtain the Kth plus 1 modified cutting depth, and so on, until the obtained modified cutting depth is within the range of process parameter values, and the obtained modified cutting depth within the range of process parameter values, the feed rate of the process parameter value to be optimized, and the threaded pipe rotation speed of the process parameter value to be optimized are taken as the optimal process parameter values.

[0041] This application optimizes the cutting depth through multiple iterations, providing more accurate process parameters for subsequent internal thread machining, thereby improving the machining accuracy of internal threads.

[0042] In some embodiments, the range of process parameter values ​​is determined based on preset processing targets, correlation rules, and surface roughness values, including: Step S401: Determine the surface roughness value range, wherein all surface roughness values ​​in the surface roughness value range are less than the preset processing target. Step S402: Determine the range of process parameters based on the range of surface roughness values ​​and the correlation rules.

[0043] In step S402 above, determining the range of process parameters based on the range of surface roughness values ​​and the correlation rules can be achieved by calculating the range of process parameters through the range of surface roughness values ​​and the correlation rules.

[0044] This application determines the range of process parameters based on the range of surface roughness values ​​and their correlation patterns, thereby ensuring that the range of process parameters can at least meet the minimum process requirements for the surface roughness value of internal threads, thus improving the machining accuracy of internal threads.

[0045] In some embodiments, the formula for calculating the ultrasonic vibration amplitude function is:

[0046] in, The steady-state vibration amplitude, It is a constant related to parameters such as modal quality. Let be the mode shape function value of the m-th mode at position L along the length of the grinding tool, where L is the length of the grinding tool. To input the excitation amplitude, The angular frequency of ultrasonic vibration. Let m be the damping ratio of the m-th mode. Let be the natural angular frequency of the m-th mode. In order to be in The amplitude of ultrasonic vibration at time 10:00. The phase angle relative to the driving signal. In order to be in The amplitude of the transient vibration at time t. The phase angle of the transient vibration. The natural frequency is when damped.

[0047] This application constructs an ultrasonic vibration amplitude function, determines the ultrasonic vibration amplitude based on the ultrasonic vibration amplitude function, and uses it to determine the optimal process parameter values, thus providing a more accurate data basis for subsequent internal gear machining.

[0048] In some embodiments, determining the deformation value of the process parameter to be optimized includes: Step S501: Obtain the length, inner diameter, outer diameter, density, and elastic modulus of the grinding tool. In step S501, the above-mentioned acquisition of the length, inner diameter, outer diameter, density, and elastic modulus of the grinding tool can be obtained by measuring the length, inner diameter, outer diameter, density, and elastic modulus of the grinding tool.

[0049] Step S502: Based on the length, inner diameter, outer diameter, and density of the grinding tool, calculate the self-weight deformation force using the following formula:

[0050] in, The deformation force is due to its own weight. For the density of grinding tools, The gravitational coefficient, The length of the grinding tool. The outer diameter of the grinding tool. The inner diameter of the grinding tool. Pi can be represented by a value of 3.14. Specifically, the maximum deformation of the free end is calculated using the following formula:

[0051] in, For the maximum deformation at the free end, It is a uniformly distributed load; The formula for calculating the total weight of the grinding tool is:

[0052]

[0053]

[0054] in, Let be the cross-sectional area of ​​the grinding tool. This is the total weight of the grinding tool. The total weight of the grinding tool; The formula for calculating uniformly distributed load is: ; In summary, the formula for calculating the deformation force under self-weight, which is equivalent to deformation under its own weight, can be obtained: .

[0055] Step S503: Determine the total force based on the self-weight deformation force and the cutting force corresponding to the values ​​of the process parameters to be optimized; Step S504: Based on the total force and the elastic modulus of the grinding tool, calculate the deformation value of the process parameter to be optimized using the following formula:

[0056] in, This is the deformation value. Let E be the total force, E be the elastic modulus of the grinding tool, and I be the interfacial polar moment of inertia.

[0057] This application calculates deformation values ​​and uses them to determine the optimal process parameters, providing more accurate data for subsequent internal gear machining.

[0058] In step S503 above, based on the self-weight deformation force and the cutting force corresponding to the values ​​of the process parameters to be optimized, the total force can be determined as follows: The grinding tool is simplified as an Euler-Bernoulli beam with a constant cross section, fixed at one end (clamping end) and free at the other end (machining end), and the bending resonance mode of a certain order of the tool (also referred to as mode in this application) is solved.

[0059] The governing equation for the transverse bending vibration of the beam is: , Where w(x,t) is the lateral displacement (deflection) of the beam at position x and time t. The governing equation for the transverse bending vibration of the beam described above is a partial differential equation, which is solved using the method of separation of variables.

[0060] Solve for the mode shapes and natural frequencies under free vibration: The assumed function is in the form of:

[0061] in, For the first function, For the second function; Substituting this into the governing equation for the transverse bending vibration of the beam, we obtain two ordinary differential equations, which are as follows: Time equation: The equation for a simple harmonic oscillator is given by: ,in ω is the angular frequency of the vibration.

[0062] Spatial equations (modal equations): ,in, The general solution to this equation is: ,in, For wavenumber parameters, As the first parameter, For the second parameter, As the third parameter, The fourth parameter, Now, let's use a boundary condition consisting of one fixed segment and one free segment, as follows: Fixed end: That is, the displacement is 0. ; Angle is 0:

[0063] Free end: x=L; that is, the bending moment is 0. The shear force is 0.

[0064] After applying these boundary conditions, the characteristic equation can be obtained: The equation has infinitely many solutions. This corresponds to an infinite number of modes.

[0065] The solution for the first bending mode is: The solution for the second bending mode is The solution for the third bending mode is The natural angular frequency of each mode can be calculated using this formula: ,in, For the first The natural angular frequencies of the first bending mode. For the first The solution for the first bending mode can also be obtained. , , and ratio

[0066] In practical ultrasonic vibration systems, a high-frequency vibration is typically applied at the stationary end. This can be modeled as the fundamental excitation. Assume there is a displacement excitation at the bearing end. In this case, the total displacement of the system can be expressed as ,in, Let be the displacement relative to the basic excitation. Through derivation, the relative displacement... The governing equations contain a term related to the base acceleration. Using modal superposition, the solution can be expressed as a superposition of modes, i.e. , For the first The first function of the first bending mode, For the first The second function of the bending mode is then substituted into the established forced vibration control equation. Utilizing the orthogonality of the modes, a series of decoupled modal coordinates are obtained. The second-order ordinary differential equation: ,in, For the first Generalized forces in bending modes.

[0067] Based on the above forced vibration control equations, the modal superposition method is applied, and modal orthogonality is utilized to obtain the modal coordinate equations. Comparison with the standard forced vibration equations for a single-degree-of-freedom system yields the expression for the generalized force: ,in , For the parameter factor of the nth mode, Let n be the mode shape function of the nth mode. , Let be the modal mass of the nth order.

[0068] To reduce the influence of cutting force and gravity on the ultrasonic vibration amplitude, the grinding point of the grinding wheel is set at the vertical diameter of the internally threaded pipe, so that part of the radial force at the grinding point is balanced with gravity. This allows us to solve for the vibration response under the influence of the difference between radial force and gravity, F3, and then calculate the total force using the following formula:

[0069] in, For total force, For the first Generalized force of order.

[0070] Specifically, in step S102, the ultrasonic vibration amplitude function at the tool tip is constructed based on the cutting force, which can be: Once the system stabilizes, the stable solution of the above second-order ordinary differential equation is obtained: When the excitation frequency approaches a certain natural angular frequency of the tool, resonance occurs. The modal response of this order is much larger than that of other modes. In ultrasonic vibration machining, the tool is operated at the first-order bending resonance frequency. Under resonance conditions, i.e. And the damping is very small The steady-state solution of order m is ,in, This represents the phase difference.

[0071] Since it is in a resonant state, and the response is mainly dominated by a certain mode (let's say the m-th mode), the relative displacement of the tool tip can be approximated as: ,Will Substituting the steady-state solution, we obtain the following expression:

[0072] Because the basic incentive is And the generalized force is proportional to Therefore, the amplitude of the end vibration for: .

[0073] Therefore, the expression for the ultrasonic vibration amplitude function can be: .

[0074] In some embodiments, before setting several different preset values ​​for process parameters, the following is included: Step S601: With the grinding point of the grinding wheel set at the vertical diameter of the internally threaded pipe, determine the initial rotational speed of the threaded pipe and the axial feed of the grinding wheel tool so that the grinding point of the grinding wheel is always at the vertical diameter of the internally threaded pipe. Several different preset values ​​for process parameters are set, including: Step S602: Based on the axial feed rate of the grinding wheel tool, set the feed rate value in the preset values ​​of each set of process parameters; based on the initial rotational speed of the threaded pipe, set the rotational speed value of the threaded pipe in the preset values ​​of each set of process parameters.

[0075] In step S601 above, when the grinding point of the grinding wheel is set at the vertical diameter of the internally threaded pipe, the initial rotational speed of the threaded pipe and the axial feed of the grinding wheel tool are determined so that the machining point of the grinding wheel is always at the vertical diameter of the internally threaded pipe. This can be achieved by determining the initial rotational speed of the threaded pipe and the axial feed of the grinding wheel tool that ensure the machining point of the grinding wheel is always at the vertical diameter of the internally threaded pipe when the grinding point of the grinding wheel is set at the vertical diameter of the internally threaded pipe.

[0076] In step S602 above, based on the axial feed of the grinding wheel tool, the feed value in the preset values ​​of each set of process parameters is set; based on the initial rotational speed of the threaded pipe, the value of the rotational speed of the threaded pipe in the preset values ​​of each set of process parameters can be set by taking the axial feed of the grinding wheel tool and the corresponding initial rotational speed of the threaded pipe, and setting the feed value and the rotational speed of the threaded pipe in the preset values ​​of each set of process parameters, wherein the axial feed of the grinding wheel tool and the corresponding initial rotational speed of the threaded pipe are used as the feed value and the rotational speed of the threaded pipe in the same set of process parameter preset values.

[0077] This application, by setting the grinding point of the grinding wheel at the vertical diameter of the internally threaded pipe, determines the initial rotational speed of the threaded pipe and the axial feed of the grinding wheel tool, so that the grinding point of the grinding wheel is always at the vertical diameter of the internally threaded pipe, thus ensuring accurate machining position and improving the machining accuracy of the internal thread.

[0078] Additionally, refer to Figure 2 One embodiment of this application provides a system for calculating ultrasonic amplitude and precision machining of internal threads in a tightly constrained small space, including a surface roughness value determination module 1100, an ultrasonic vibration amplitude determination module 1200, an optimal process parameter value determination module 1300, and a machining module 1400, wherein: The surface roughness value determination module 1100 is used to determine the cutting force of the tool radial direction and the surface roughness value of the workpiece corresponding to each set of preset process parameter values, when several different sets of preset process parameter values ​​are set. Each set of preset process parameter values ​​includes the cutting depth, feed rate and the rotation speed of the threaded pipe. The ultrasonic vibration amplitude determination module 1200 is used to determine the ultrasonic vibration amplitude corresponding to the preset values ​​of each set of process parameters by means of finite element simulation, based on the ultrasonic vibration amplitude function of the tool end constructed based on the cutting force. The optimal process parameter value determination module 1300 is used to determine the optimal process parameter value based on the cutting force, surface roughness value and ultrasonic vibration amplitude corresponding to the preset values ​​of each set of process parameters; The machining module 1400 is used to perform machining operations on internal threads based on the optimal process parameters.

[0079] This system determines the radial cutting force of the tool and the surface roughness of the workpiece corresponding to each of several preset sets of process parameters. It then constructs an ultrasonic vibration amplitude function at the tool tip based on the cutting force and uses finite element simulation to determine the ultrasonic vibration amplitude corresponding to each preset set of process parameters. Based on the cutting force, surface roughness, and ultrasonic vibration amplitude corresponding to each preset set of process parameters, the optimal process parameter values ​​are determined. Finally, based on the optimal process parameter values, internal threads are machined. This application incorporates ultrasonic vibration amplitude into the process parameter optimization by constructing an ultrasonic vibration amplitude function at the tool tip, compensating for machining deformation and improving the machining efficiency and accuracy of internal threads.

[0080] It should be noted that the system embodiments described above are based on the same inventive concept as the method embodiments described above. Therefore, the relevant content of the method embodiments described above is also applicable to the system embodiments described above, and will not be repeated here.

[0081] Figure 3This paper presents a schematic diagram of the hardware structure for ultrasonic amplitude calculation and precision machining of internal threads in a strongly constrained small space, as provided in an embodiment of this application.

[0082] An ultrasonic amplitude calculation and internal thread precision machining device in a strongly constrained small space may include a processor 301 and a memory 302 storing computer program instructions.

[0083] Specifically, the processor 301 may include a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits that can be configured to implement the embodiments of this application.

[0084] Memory 302 may include mass storage for data or instructions. For example, and not limitingly, memory 302 may include a hard disk drive (HDD), floppy disk drive, flash memory, optical disk, magneto-optical disk, magnetic tape, or Universal Serial Bus (USB) drive, or a combination of two or more of these. Where appropriate, memory 302 may include removable or non-removable (or fixed) media. Where appropriate, memory 302 may be internal or external to the integrated gateway disaster recovery device. In a particular embodiment, memory 302 is non-volatile solid-state memory.

[0085] In some embodiments, memory 302 may include read-only memory (ROM), random access memory (RAM), disk storage media device, optical storage media device, flash memory device, electrical, optical, or other physical / tangible memory storage device. Thus, generally, memory includes one or more tangible (non-transitory) computer-readable storage media (e.g., memory devices) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors), it is operable to perform the operations described with reference to the method according to one aspect of this disclosure.

[0086] The processor 301 reads and executes the computer program instructions stored in the memory 302 to implement any of the ultrasonic amplitude calculation and internal thread precision machining methods in the strongly constrained small space described in the above embodiments.

[0087] In one example, the ultrasonic amplitude calculation and internal thread precision machining equipment in a strongly constrained small space may also include a communication interface 303 and a bus 310. For example, Figure 3 As shown, the processor 301, memory 302, and communication interface 303 are connected through bus 310 and complete communication with each other.

[0088] The communication interface 303 is mainly used to realize communication between various modules, devices, units and / or equipment in the embodiments of this application.

[0089] Bus 310 includes hardware, software, or both, that couples together components of an ultrasonic amplitude calculation and internal thread precision machining device within a tightly constrained, small space. For example, and not limitingly, the bus may include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), HyperTransport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an Infinite Bandwidth Interconnect, a Low Pin Count (LPC) bus, a memory bus, a Microchannel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local (VLB) bus, or other suitable buses, or combinations of two or more of these. Where appropriate, bus 310 may include one or more buses. Although specific buses are described and illustrated in embodiments of this application, this application contemplates any suitable bus or interconnect.

[0090] This equipment for calculating ultrasonic amplitude and precision machining internal threads in a tightly constrained small space can execute the method for calculating ultrasonic amplitude and precision machining internal threads in a tightly constrained small space as described in this application's embodiments based on a three-dimensional design model, thereby achieving a combination of... Figure 1 and Figure 2 The method and system for calculating ultrasonic amplitude and precision machining of internal threads in a strongly constrained small space are described.

[0091] Furthermore, in conjunction with the ultrasonic amplitude calculation and internal thread precision machining method in a strongly constrained small space described in the above embodiments, this application embodiment can provide a computer storage medium for implementation. This computer storage medium stores computer program instructions; when these computer program instructions are executed by a processor, they implement any one of the ultrasonic amplitude calculation and internal thread precision machining methods in a strongly constrained small space described in the above embodiments.

[0092] It should be clarified that this application is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of this application is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of this application.

[0093] The functional blocks shown in the above block diagram can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this application are programs or code segments used to perform the required tasks. Programs or code segments can be stored on a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried on a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, radio frequency (RF) links, etc. Code segments can be downloaded via computer networks such as the Internet, intranets, etc.

[0094] It should also be noted that the exemplary embodiments mentioned in this application describe methods or systems based on a series of steps or apparatus. However, this application is not limited to the order of the above steps; that is, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

[0095] The aspects of this disclosure have been described above with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It should be understood that each block in the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine such that these instructions, executable via the processor of the computer or other programmable data processing apparatus, enable the implementation of the functions / actions specified in one or more blocks of the flowchart illustrations and / or block diagrams. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor, or a field-programmable logic circuit. It is also understood that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can also be implemented by special-purpose hardware performing the specified functions or actions, or can be implemented by a combination of special-purpose hardware and computer instructions.

[0096] The above description is merely a specific implementation of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. A method for calculating ultrasonic amplitude and precision machining of internal threads in a strongly constrained small space, characterized in that, The method for calculating ultrasonic amplitude and precision machining of internal threads in a strongly constrained small space includes: With several different preset values ​​of process parameters set, the cutting force of the tool radial direction and the surface roughness value of the workpiece corresponding to each preset value of process parameters are determined. The preset values ​​of each set of process parameters include the depth of cut, feed rate and the rotation speed of the threaded pipe. In the case of constructing the ultrasonic vibration amplitude function of the tool tip based on the cutting force, and based on the ultrasonic vibration amplitude function, the ultrasonic vibration amplitude corresponding to the preset value of each set of process parameters is determined by the finite element simulation method. Based on the cutting force, surface roughness value, and ultrasonic vibration amplitude corresponding to the preset values ​​of each set of process parameters, the optimal process parameter values ​​are determined. Based on the optimal process parameter values, the internal thread is machined.

2. The method for calculating ultrasonic amplitude and precision machining of internal threads in a strongly constrained small space according to claim 1, characterized in that, The process of determining the optimal process parameter values ​​based on the preset values ​​of the cutting force, the surface roughness value, and the ultrasonic vibration amplitude corresponding to each set of process parameters includes: Based on the cutting force, the correlation between the process parameters, the surface roughness value, and the ultrasonic vibration amplitude is determined by a fitting method, wherein the correlation is used to characterize the numerical correlation between the process parameters, the surface roughness value, and the ultrasonic vibration amplitude; Based on the preset processing target, the correlation law, and the surface roughness value, the range of process parameter values ​​is determined; Select the group of preset process parameter values ​​from all groups of process parameter preset values ​​where the feed rate and the rotational speed of the threaded pipe are within the range of process parameter values, and the cutting depth is the largest, as the process parameter values ​​to be optimized; Determine the first deformation value and the corresponding first ultrasonic vibration amplitude of the process parameter to be optimized; If the sum of the first deformation value and the first ultrasonic vibration amplitude is less than a preset deviation threshold, and the value of the process parameter to be optimized is within the range of the process parameter values, then the value of the process parameter to be optimized is taken as the optimal process parameter value.

3. The method for calculating ultrasonic amplitude and precision machining of internal threads in a strongly constrained small space according to claim 2, characterized in that, After determining the first deformation value and the corresponding first ultrasonic vibration amplitude of the process parameter to be optimized, the method further includes: If the sum of the first deformation value and the first ultrasonic vibration amplitude is greater than or equal to the preset deviation threshold, the cutting depth of the process parameter to be optimized is reduced by a preset ratio to obtain the first modified cutting depth. Determine the second deformation value and the second ultrasonic vibration amplitude of the first modified cutting depth. If the sum of the second deformation value and the second ultrasonic vibration amplitude is greater than or equal to the preset deviation threshold, reduce the first modified cutting depth by the preset ratio to obtain the second modified cutting depth. Repeat this process until the sum of the (K-1)th deformation value and the (K-1)th ultrasonic vibration amplitude corresponding to the Kth modified cutting depth is less than the preset deviation threshold. Then determine whether the Kth modified cutting depth is within the range of the process parameters, where K is the iteration number. When the Kth modified cutting depth is within the range of the process parameter values, the Kth modified cutting depth, the feed rate of the process parameter to be optimized, and the threaded pipe rotation speed of the process parameter to be optimized are taken as the optimal process parameter values.

4. The method for calculating ultrasonic amplitude and precision machining of internal threads in a strongly constrained small space according to claim 2, characterized in that, The process parameter value range is determined based on the preset processing target, the correlation law, and the surface roughness value, including: A range of surface roughness values ​​is determined, wherein all surface roughness values ​​within the range are less than the preset processing target. Based on the surface roughness value range and the correlation rule, the value range of the process parameters is determined.

5. The method for calculating ultrasonic amplitude and precision machining of internal threads in a strongly constrained small space according to claim 4, characterized in that, The formula for calculating the ultrasonic vibration amplitude function is as follows: in, The steady-state vibration amplitude, It is a constant related to parameters such as modal quality. Let be the mode shape function value of the m-th mode at position L along the length of the grinding tool, where L is the length of the grinding tool. To input the excitation amplitude, The angular frequency of ultrasonic vibration. Let m be the damping ratio of the m-th mode. Let be the natural angular frequency of the m-th mode. In order to be in The amplitude of ultrasonic vibration at time 10:

00. The phase angle relative to the driving signal. In order to be in The amplitude of the transient vibration at time t. The phase angle of the transient vibration. The natural frequency is when damped.

6. The method for calculating ultrasonic amplitude and precision machining of internal threads in a strongly constrained small space according to claim 5, characterized in that, The deformation value for determining the value of the process parameter to be optimized includes: Obtain the length, inner diameter, outer diameter, density, and elastic modulus of the grinding tool; Based on the length, inner diameter, outer diameter, and density of the grinding tool, the self-weight deformation force is calculated using the following formula: in, The deformation force is due to its own weight. For the density of grinding tools, The gravitational coefficient, The length of the grinding tool. The outer diameter of the grinding tool. The inner diameter of the grinding tool; The total force is determined based on the self-weight deformation force and the cutting force corresponding to the values ​​of the process parameters to be optimized. Based on the total force and the elastic modulus of the grinding tool, the deformation value of the process parameter to be optimized is calculated using the following formula: in, This is the deformation value. Let E be the total force, E be the elastic modulus of the grinding tool, and I be the interfacial polar moment of inertia.

7. The method for calculating ultrasonic amplitude and precision machining of internal threads in a strongly constrained small space according to claim 1, characterized in that, Before setting several different preset values ​​for process parameters, the following is included: With the grinding point of the grinding wheel set at the vertical diameter of the internally threaded pipe, the initial rotational speed of the threaded pipe and the axial feed of the grinding wheel tool are determined so that the grinding point of the grinding wheel is always located at the vertical diameter of the internally threaded pipe. The setting of several different preset values ​​for process parameters includes: Based on the axial feed rate of the grinding wheel tool, the feed rate value in the preset values ​​of each set of process parameters is set; based on the initial rotational speed of the threaded pipe, the rotational speed value of the threaded pipe in the preset values ​​of each set of process parameters is set.

8. A system for calculating ultrasonic amplitude and precision machining of internal threads in a strongly constrained small space, characterized in that, The system for calculating ultrasonic amplitude and precision machining of internal threads in a tightly constrained small space includes: The surface roughness value determination module is used to determine the cutting force of the tool radial direction and the surface roughness value of the workpiece corresponding to each set of preset process parameter values, when several different sets of preset process parameter values ​​are set. The preset process parameter values ​​include the cutting depth, feed rate and the rotation speed of the threaded pipe. The ultrasonic vibration amplitude determination module is used to determine the ultrasonic vibration amplitude corresponding to the preset values ​​of each set of process parameters by means of finite element simulation, based on the ultrasonic vibration amplitude function of the tool end constructed based on the cutting force. The optimal process parameter value determination module is used to determine the optimal process parameter value based on the cutting force, the surface roughness value, and the ultrasonic vibration amplitude corresponding to the preset values ​​of each set of process parameters; The machining module is used to perform machining operations on the internal thread based on the optimal process parameter values.

9. A device for calculating ultrasonic amplitude and precision machining of internal threads in a tightly constrained small space, characterized in that, It includes at least one control processor and a memory for communicatively connecting to the at least one control processor; the memory stores instructions executable by the at least one control processor, which, when executed by the at least one control processor, enable the at least one control processor to perform a method for calculating ultrasonic amplitude and precision machining of internal threads in a strongly constrained small space as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer-executable instructions for causing a computer to perform a method for calculating ultrasonic amplitude and precision machining of internal threads in a strongly constrained small space as described in any one of claims 1 to 7.

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