A method and system for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways

Abstract

The present invention discloses a method and system for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways. This method obtains the cutting force, ultrasonic vibration amplitude, and cutting force coefficient at various cutting depths in the ultrasonic-assisted precision machining device; calculates the unit cutting force amplitude based on the cutting force and ultrasonic vibration amplitude, and calculates the tool angle change value and displacement change value based on the cutting force and the length of the tool for machining the gear keyway; calculates the workpiece cutting depth value based on the displacement change value, cutting force coefficient, and unit cutting force amplitude; calculates the actual rake angle and actual clearance angle of the tool based on the tool angle change value, and constrains the actual rake angle and actual clearance angle of the tool to obtain the rake angle constraint and clearance angle constraint; and machines the gear keyway according to the rake angle constraint, clearance angle constraint, and workpiece cutting depth value. The present invention can improve machining accuracy, machining efficiency, workpiece quality, and tool life.

Description

Technical Field

[0001] The present invention relates to the technical field of gear machining, and in particular, to a method and system for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways. Background Art

[0002] High-strength gears are widely used in the transmission systems of aero-engines. To meet the requirements of high rotational speed, high load-bearing capacity, and high temperature, the hardness and strength of high-strength gears are getting higher and higher. Such high-strength gears are connected to the transmission shaft through the inner hole. During the gear meshing process, the dynamic high-frequency force generated continuously impacts the surface where the inner hole is connected to the shaft, posing higher requirements for the shape accuracy, dimensional accuracy, micro-topography, and contact performance of the joint surface. The high hardness, high strength, and low toughness of high-strength gear materials result in large cutting force coefficients, high chip fracture frequencies, and large high-frequency amplitude fluctuations of cutting forces during traditional machining processes. This causes engineering problems such as easy tool wear, low machining quality, and easy workpiece scrapping. For the latest high-strength gear steel CH1900, with a yield strength exceeding 1700 MPa and a hardness exceeding 68 HRC, its cutting force coefficient, cutting force oscillation frequency, and oscillation amplitude are even larger. When machining an inner diameter less than 20 mm, the above engineering problems are more obvious. In addition, when heat treatment quenching is used to increase the hardness of the contact surface, the hardness after heat treatment quenching also reaches 68 HRC, and the connecting shaft surface will also deform, requiring finish machining, and the same problems will be encountered during finish machining. Therefore, the current machining of heat-treated quenched gears and subsequent high-strength and super-hard gears will have the same problems. In addition, when machining gear keyways by existing processes, due to the high hardness of the contact surface, the cutting depth during finish machining is small, and the unit cutting force is large. Although ultrasonic cutting can significantly reduce the cutting force, it is difficult for the ultrasonic vibration device to generate the set amplitude under load, which also causes radial offset. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. For this purpose, the present invention provides a method and system for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways, which can improve machining accuracy, machining efficiency, workpiece quality, and tool life.

[0004] In a first aspect, an embodiment of the present invention provides a method for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways, and the method for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways includes:

[0005] Obtain the cutting force, ultrasonic vibration amplitude, and cutting force coefficient at various cutting depths;

[0006] Calculate the unit cutting force according to the cutting force and the ultrasonic vibration amplitude;

[0007] Obtain the length of the tool for machining the gear keyway, and calculate the tool angle change value and the displacement change value according to the cutting force and the length;

[0008] Calculate the workpiece cutting depth value according to the displacement change value, the cutting force coefficient and the unit cutting force;

[0009] Calculate the actual rake angle and the actual clearance angle of the tool according to the tool angle change value;

[0010] Constrain the actual rake angle and the actual clearance angle of the tool to obtain the rake angle constraint and the clearance angle constraint;

[0011] Machine the gear keyway according to the rake angle constraint, the clearance angle constraint and the workpiece cutting depth value.

[0012] Compared with the prior art, the first aspect of the present invention has the following beneficial effects:

[0013] By obtaining the cutting force, the ultrasonic vibration amplitude and the cutting force coefficient at various cutting depths in the ultrasonic-assisted precision machining device, calculating the unit cutting force amplitude according to the cutting force and the ultrasonic vibration amplitude, and calculating the tool angle change value and the displacement change value according to the cutting force and the length of the tool for machining the gear keyway, this method takes into account the tool angle change and displacement change caused by the cutting force, and can reduce the machining error and tool wear caused by deviating from the design parameters during the subsequent machining of the gear keyway; calculate the workpiece cutting depth value according to the displacement change value, the cutting force coefficient and the unit cutting force amplitude, calculate the actual rake angle and the actual clearance angle of the tool according to the tool angle change value, and constrain the actual rake angle and the actual clearance angle of the tool to obtain the rake angle constraint and the clearance angle constraint, machine the gear keyway according to the rake angle constraint, the clearance angle constraint and the workpiece cutting depth value, and by constraining the rake angle and the clearance angle, the cutting path can be optimized, thereby improving the machining accuracy, and improving the machining efficiency, workpiece quality and tool life.

[0014] According to some embodiments of the present invention, the tool angle change value and the displacement change value are calculated in the following manner:

[0015] The calculation of the tool angle change value is:

[0016]

[0017] The calculation of the displacement change value is:

[0018]

[0019] where α c represents the tool angle change value, F xDenote the cutting force component in the x - direction of the cutting force as \(F_x\), \(l\) denote the length of the tool for machining the gear keyway, \(E\) denote the elastic modulus, \(I\) denote the polar moment of inertia, \(L\) c Denote the displacement change value.

[0020] According to some embodiments of the present invention, the cutting depth value of the workpiece is calculated in the following way:

[0021]

[0022] where \(h\) denote the cutting depth value of the workpiece, \(b\) denote the cutting width, \(k\) f denote the cutting force coefficient, \(h\) d denote the ideal cutting depth, \(\varepsilon\) i denote the unit cutting force amplitude.

[0023] According to some embodiments of the present invention, the ideal cutting depth is calculated in the following way:

[0024] \(h\) d \(=\ h\) v \(+\ h - L\) c

[0025] where \(h\) v denote the ultrasonic vibration amplitude.

[0026] According to some embodiments of the present invention, the actual rake angle and the actual clearance angle of the tool are calculated in the following way:

[0027] The actual rake angle of the tool is calculated as:

[0028] \(\alpha\) s \(=\ \alpha\) c \(+\ \alpha\) t \(+\ \alpha\) v

[0029] The actual clearance angle of the tool is calculated as:

[0030] \(\beta\) s \(=\ \alpha\) c \(+\ \beta\) t \(+\ \alpha\) v

[0031] where \(\alpha\) s denote the actual rake angle of the tool, \(\alpha\) c denote the tool angle change value, \(\alpha\) t denote the theoretical rake angle of the tool, \(\alpha\) v denote the tool angle change amount caused by ultrasonic vibration, \(\beta\) s denote the actual clearance angle of the tool, \(\beta\) t denote the theoretical clearance angle of the tool.

[0032] According to some embodiments of the present invention, the change in the tool angle caused by the ultrasonic vibration is calculated as follows:

[0033]

[0034] where v represents the cutting speed controlled by the gear shaper, and v v represents the cutting speed caused by the ultrasonic vibration, and v v = 2πf v h v and f v represents the ultrasonic vibration frequency, and h v represents the ultrasonic vibration amplitude.

[0035] According to some embodiments of the present invention, the actual rake angle and the actual clearance angle of the tool are constrained to obtain the rake angle constraint and the clearance angle constraint, including:

[0036] Constraining the actual rake angle of the tool to obtain the rake angle constraint:

[0037]

[0038] Constraining the actual clearance angle of the tool to obtain the clearance angle constraint:

[0039]

[0040] where F i represents the cutting force, l represents the length of the tool for machining the gear keyway, E represents the modulus of elasticity, I represents the polar moment of inertia, and f v represents the ultrasonic vibration frequency, h v represents the ultrasonic vibration amplitude, and v represents the cutting speed controlled by the gear shaper.

[0041] In a second aspect, an embodiment of the present invention further provides a system for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways. The system for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways includes:

[0042] A data acquisition unit for acquiring the cutting force, the ultrasonic vibration amplitude, and the cutting force coefficient at various cutting depths in the ultrasonic-assisted precision machining device;

[0043] A first calculation unit for calculating the unit cutting force amplitude according to the cutting force and the ultrasonic vibration amplitude, and calculating the tool angle change value and the displacement change value according to the cutting force and the length of the tool for machining the gear keyway;

[0044] A second calculation unit for calculating the workpiece cutting depth value according to the displacement change value, the cutting force coefficient, and the unit cutting force amplitude;

[0045] A third calculation unit, configured to calculate an actual rake angle and an actual clearance angle of the cutting tool according to the cutting tool angle change value, and perform constraints on the actual rake angle and the actual clearance angle of the cutting tool to obtain a rake angle constraint and a clearance angle constraint;

[0046] A gear machining unit, configured to machine the gear keyway according to the rake angle constraint, the clearance angle constraint, and the workpiece cutting depth value.

[0047] In a third aspect, an embodiment of the present invention further provides a device for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways, including at least one control processor and a memory communicatively connected to the at least one control processor; the memory stores instructions executable by the at least one control processor, and the instructions are executed by the at least one control processor to enable the at least one control processor to execute a method for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways as described above.

[0048] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium storing computer-executable instructions for causing a computer to execute a method for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways as described above.

[0049] It can be understood that the beneficial effects of the above second aspect to the fourth aspect compared with the related art are the same as those of the above first aspect compared with the related art. For the relevant descriptions, reference can be made to the relevant descriptions in the above first aspect, and details will not be repeated here. Description of the Drawings

[0050] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the following description of the embodiments in conjunction with the accompanying drawings, where:

[0051] Figure 1 is a flowchart of a method for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways according to an embodiment of the present invention;

[0052] Figure 2 is a schematic diagram of an ultrasonic-assisted precision machining device according to an embodiment of the present invention;

[0053] Figure 3 is a schematic diagram of multiple machining paths according to an embodiment of the present invention;

[0054] Figure 4 is a structural diagram of a system for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways according to an embodiment of the present invention. Detailed Embodiments

[0055] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where like or similar reference numerals denote like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

[0056] In the description of the present invention, if the first, second, etc. are described, it is only for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence of the indicated technical features.

[0057] In the description of the present invention, it should be understood that with respect to the orientation description, such as up, down, etc., the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

[0058] In the description of the present invention, it should be noted that unless otherwise clearly defined, terms such as "set", "installed", "connected", etc. should be understood in a broad sense. Those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific content of the technical solution.

[0059] High-strength gears are widely used in the transmission system of aero-engines. To meet the requirements of high rotational speed, high load-carrying capacity, and high temperature, the hardness and strength of high-strength gears are getting higher and higher. These high-strength gears are connected to the transmission shaft through the inner hole. During the gear meshing process, the dynamic high-frequency force formed continuously impacts the surface where the inner hole is connected to the shaft, posing higher requirements for the shape accuracy, dimensional accuracy, micro-topography, and contact performance of the joint surface of the shaft. The high hardness, high strength, and low toughness of high-strength gear materials result in a large cutting force coefficient, a high chip fracture frequency, and a large high-frequency amplitude fluctuation of the cutting force during traditional machining, which causes engineering problems such as easy tool wear, low machining quality, and easy workpiece scrapping. The latest high-strength gear steel CH1900 has a yield strength exceeding 1700 MPa and a hardness exceeding 68 HRC. Its cutting force coefficient, cutting force oscillation frequency, and oscillation amplitude are even larger. When machining an inner diameter less than 20 mm, the above engineering problems are more obvious. In addition, when the hardness of the contact surface is increased by heat treatment quenching, the hardness after heat treatment quenching also reaches 68 HRC, and the connecting shaft surface will also be deformed and requires finish machining, and the same problems will be encountered during finish machining. Therefore, there are the same problems in the current machining of heat-treated quenched gears and subsequent high-strength super-hard gears. In addition, when machining the gear keyway by the existing process, due to the high hardness of the contact surface, the cutting depth is small during finish machining, and the unit cutting force is large. Although ultrasonic cutting can significantly reduce the cutting force, it is difficult for the ultrasonic vibration device to generate the set amplitude under load, which also causes radial deviation.

[0060] To solve the above problems, the present invention obtains the cutting force, ultrasonic vibration amplitude, and cutting force coefficient at various cutting depths in an ultrasonic-assisted precision machining device, calculates the unit cutting force amplitude according to the cutting force and ultrasonic vibration amplitude, and calculates the tool angle change value and displacement change value according to the cutting force and the length of the tool for machining the gear keyway. The present invention takes into account the tool angle change and displacement change caused by the cutting force, and can reduce the machining error and tool wear caused by deviating from the design parameters during the subsequent machining of the gear keyway; according to the displacement change value, cutting force coefficient, and unit cutting force amplitude, calculates the workpiece cutting depth value, calculates the actual rake angle and actual clearance angle of the tool according to the tool angle change value, and constrains the actual rake angle and actual clearance angle of the tool to obtain the rake angle constraint and clearance angle constraint. The gear keyway is machined according to the rake angle constraint, clearance angle constraint, and workpiece cutting depth value. By constraining the rake angle and clearance angle, the cutting path can be optimized, thereby improving the machining accuracy, machining efficiency, workpiece quality, and tool life.

[0061] Refer to Figure 1 , the embodiment of the present invention provides a method for ultrasonic-assisted precision machining of high-strength super-hard gear keyways. The method for ultrasonic-assisted precision machining of high-strength super-hard gear keyways includes but is not limited to steps S100 to S500, where:

[0062] Step S100: Obtain the cutting force, ultrasonic vibration amplitude, and cutting force coefficient at various cutting depths in the ultrasonic-assisted precision machining device;

[0063] Step S200: Calculate the unit cutting force amplitude based on the cutting force and ultrasonic vibration amplitude, and calculate the tool angle change value and displacement change value based on the cutting force and the length of the tool for machining the gear keyway;

[0064] Step S300: Calculate the workpiece cutting depth value based on the displacement change value, cutting force coefficient, and unit cutting force amplitude;

[0065] Step S400: Calculate the actual rake angle and actual clearance angle of the tool based on the tool angle change value, and constrain the actual rake angle and actual clearance angle of the tool to obtain the rake angle constraint and clearance angle constraint;

[0066] Step S500: Machine the gear keyway based on the rake angle constraint, clearance angle constraint, and workpiece cutting depth value.

[0067] In steps S100 to S500 of some embodiments, in order to consider the tool angle change and displacement change caused by the cutting force, so as to reduce the machining error and tool wear caused by deviating from the design parameters during subsequent machining of the gear keyway, in this embodiment, the cutting force, ultrasonic vibration amplitude, and cutting force coefficient at various cutting depths in the ultrasonic-assisted precision machining device are obtained, the unit cutting force amplitude is calculated based on the cutting force and ultrasonic vibration amplitude, and the tool angle change value and displacement change value are calculated based on the cutting force and the length of the tool for machining the gear keyway; in order to optimize the cutting path, thereby improving the machining accuracy, and improving the machining efficiency, workpiece quality, and tool life, in this embodiment, the workpiece cutting depth value is calculated based on the displacement change value, cutting force coefficient, and unit cutting force amplitude, the actual rake angle and actual clearance angle of the tool are calculated based on the tool angle change value, and the actual rake angle and actual clearance angle of the tool are constrained to obtain the rake angle constraint and clearance angle constraint, and the gear keyway is machined based on the rake angle constraint, clearance angle constraint, and workpiece cutting depth value.

[0068] In some embodiments, the tool angle change value and displacement change value are calculated in the following manner:

[0069] The calculation formula for the tool angle change value is:

[0070]

[0071] The calculation formula for the displacement change value is:

[0072]

[0073] where, α c represents the tool angle change value, F xThe cutting force component in the x - direction of the cutting force is denoted as \(F_x\), \(l\) represents the length of the tool for machining the gear keyway, \(E\) represents the modulus of elasticity, \(I\) represents the polar moment of inertia, and \(L\) c represents the displacement change value.

[0074] In this embodiment, the tool angle change and displacement change caused by the cutting force are considered to reduce the machining error and tool wear caused by deviation from the design parameters during subsequent machining of the gear keyway, and lay a foundation for improving machining accuracy and reducing tool wear.

[0075] In some embodiments, the workpiece cutting depth value is calculated in the following manner:

[0076]

[0077] where \(h\) represents the workpiece cutting depth value, \(b\) represents the cutting width, and \(k\) f represents the cutting force coefficient, and \(h\) d represents the ideal cutting depth, and \(\varepsilon\) i represents the unit cutting force amplitude.

[0078] In this embodiment, in ultrasonic vibration cutting, as the cutting depth and cutting force load increase, the cutting depth no longer continuously increases according to the previous law and reaches a stable value. Therefore, the workpiece cutting depth value is calculated in this embodiment to obtain the actual cutting depth.

[0079] In some embodiments, the ideal cutting depth is calculated in the following manner:

[0080] \(h\) d \(=\ h\) v \(+\ h - L\) c

[0081] where \(h\) v represents the ultrasonic vibration amplitude.

[0082] In some embodiments, the actual rake angle and actual clearance angle of the tool are calculated in the following manner:

[0083] The calculation of the actual rake angle of the tool is:

[0084] \(\alpha\) s \(=\ \alpha\) c \(+\ \alpha\) t \(+\ \alpha\) v

[0085] The calculation of the actual clearance angle of the tool is:

[0086] \(\beta\) s \(=\ \alpha\) c \(+\ \beta\) t \(+\ \alpha\) v

[0087] where \(\alpha\)s Denotes the actual rake angle of the cutting tool, α c Denotes the change value of the cutting tool angle, α t Denotes the theoretical rake angle of the cutting tool, α v Denotes the change amount of the cutting tool angle caused by ultrasonic vibration, β s Denotes the actual clearance angle of the cutting tool, β t Denotes the theoretical clearance angle of the cutting tool.

[0088] In some embodiments, the change amount of the cutting tool angle caused by ultrasonic vibration is calculated as follows:

[0089]

[0090] Wherein, v denotes the cutting speed controlled by the gear shaper, v v Denotes the cutting speed caused by ultrasonic vibration, v v = 2πf v h v f v Denotes the ultrasonic vibration frequency, h v Denotes the ultrasonic vibration amplitude.

[0091] In some embodiments, the actual rake angle and the actual clearance angle of the cutting tool are constrained to obtain the rake angle constraint and the clearance angle constraint, including:

[0092] Constraining the actual rake angle of the cutting tool to obtain the rake angle constraint:

[0093]

[0094] Constraining the actual clearance angle of the cutting tool to obtain the clearance angle constraint:

[0095]

[0096] Wherein, F i Denotes the cutting force, l denotes the length of the cutting tool for machining the gear keyway, E denotes the elastic modulus, I denotes the polar moment of inertia, f v Denotes the ultrasonic vibration frequency, h v Denotes the ultrasonic vibration amplitude, v denotes the cutting speed controlled by the gear shaper.

[0097] In this embodiment, by constraining the rake angle and the clearance angle, the cutting path can be optimized, thereby improving the machining accuracy, and improving the machining efficiency, workpiece quality and tool life.

[0098] For the convenience of those skilled in the art to understand, the following provides a set of best embodiments:

[0099] Referring to Figure 2 , Figure 2Schematic diagram of an ultrasonic-assisted precision machining device. The ultrasonic-assisted precision machining device is fixed on the workbench of a gear shaper. The workpiece is fixed on the ultrasonic-assisted precision machining device, and the ultrasonic-assisted precision machining device excites the workpiece to vibrate. In the figure, 1 is an ultrasonic vibration horn, 2 is a cutting tool, 3 is the workpiece, and 4 is a piezoelectric actuator. The control system controls the excitation power of the piezoelectric actuator to control the ultrasonic vibration amplitudes of the ultrasonic vibration device in the x and y directions. The machine tool control system controls the feed motion of the machine tool spindle, and the feed rate is set to f z . Among them, the ultrasonic vibration horn 1 is fixed on the workbench of the gear shaper through a clamping device, and the fixing position of the fixing device and the ultrasonic vibration horn is the vibration node of the ultrasonic vibration horn. The control implementation process is as follows:

[0100] 1) During the test, when the workpiece is under the cutting force load and the ultrasonic vibration device turns on 50% of its maximum power, the ultrasonic vibration amplitudes of the workpiece in the x and y directions are f x and f y respectively, and the ultrasonic vibration amplitudes are obtained through a laser vibrometer.

[0101] 2) Conduct a cutting force coefficient identification test, where the ultrasonic vibration amplitude is 50% of the maximum power of the ultrasonic machining device, and collect the cutting forces F 1 , F 2 , …, F i , …, F n under the condition that the feed rate or cutting depth increases sequentially. The laser vibrometer collects the ultrasonic vibration amplitudes h 1 , h 2 , …, h i , …, h n corresponding to the cutting forces. The cutting force coefficient, denoted as k f , is obtained through linear regression. According to the cutting force F i and the ultrasonic vibration amplitude h i , the unit cutting force amplitude ε i under the unit cutting force is calculated, where Then the unit cutting force amplitudes under the condition that the feed rate or cutting depth increases sequentially are ε 1 , ε 2 , …, ε i , …, ε n .

[0102] 3) According to the force exerted by the cutting force on the cutting tool, it can be decomposed into cutting forces in three directions, denoted as F x , F y and F z respectively, where the z direction is the normal direction perpendicular to the plane formed by x and y. Under the action of the cutting force, the displacement and deflection of the machining tool system end change, and the rake angle of the tool also changes.

[0103] The length of the tool system for machining the gear keyway is set as l, and according to the cantilever beam theory, the cutting force component F in the x-direction of the cutting force is obtained. x Under the action, the change value α of the tool angle is calculated. c It is:

[0104]

[0105] The change value L of the displacement is calculated. c It is:

[0106]

[0107] Among them, α c represents the change value of the tool angle, F x represents the cutting force component in the x-direction of the cutting force, l represents the length of the tool for machining the gear keyway, E represents the elastic modulus, which is a material parameter, I represents the polar moment of inertia, which is determined by the tool geometry and is obtained by calculation according to the material mechanics formula, and all are known. L c represents the change value of the displacement.

[0108] Under the condition that the displacement change caused by the cutting force F x is relatively small compared with the length l of the tool system, the change in displacement and deflection caused by this displacement under the concentrated load of the cutting force F z is ignored. This is because the displacement change caused by F x will cause changes in displacement and deflection, but the displacement change caused by the cutting force F z is relatively small compared with the length l of the tool system, so this influence is ignored. Therefore, the influence of the cutting force F x on the change in displacement and deflection caused by the displacement change caused by the cutting force F z is ignored. x on the change in displacement and deflection caused by the displacement change caused by the cutting force F

[0109] According to the above situation, the actual rake angle of the tool in ultrasonic cutting machining is calculated as:

[0110] α s =α c +α t +α v

[0111] The actual clearance angle of the tool in ultrasonic cutting machining is calculated as:

[0112] β s =α c +β t +α v

[0113] Among them, α s represents the actual rake angle of the tool, αc Denote the tool angle change value, α t Denote the theoretical rake angle of the tool, α v Denote the tool angle change amount caused by ultrasonic vibration v represents the cutting speed controlled by the gear shaper, v v Denote the cutting speed caused by ultrasonic vibration, v v = 2πf v h v , f v Denote the ultrasonic vibration frequency, h v Denote the ultrasonic vibration amplitude, β s Denote the actual clearance angle of the tool, β t Denote the theoretical clearance angle of the tool

[0114] In actual cutting, the change of cutting force load causes the change of the rake angle and cutting depth of the tool cutting edge, resulting in abnormal tool wear and machining error

[0115] When the displacement and deflection change, the cutting force changes accordingly. This is a cutting dynamic coupling process. The cutting force causes the change of displacement and deflection, and the change of displacement and deflection changes the cutting parameters and tool angles, and also changes the machining amount, resulting in machining error and tool wear. Among them, the tool wear is caused by deviating from the designed cutting parameters, and the changing cutting parameters and tool angles change the cutting force again

[0116] 4) In ultrasonic vibration cutting, with the increase of cutting depth and cutting force load, the cutting depth no longer increases continuously according to the previous law and reaches a stable value. Let the ideal cutting depth be h d , and this value is usually the workpiece allowance. Then the calculation formula is as follows

[0117] h d = h v + h - L c

[0118] h v = ε i F i

[0119] F i = (h - L c )bk f

[0120]

[0121] Combining the above formulas, we can get

[0122]

[0123]

[0124]

[0125]

[0126] Subsequently

[0127]

[0128]

[0129]

[0130] Then

[0131]

[0132]

[0133]

[0134] The cutting depth value h of the workpiece is obtained.

[0135] 5) Calculation of the actual cutting angles of the tool

[0136] When cutting high-hardness and high-strength materials, if the tool is not sharp enough and the cutting-in angle is not small enough, that is, the rake angle of the tool is not large enough, it will be difficult to form shear deformation, resulting in abnormal wear of the tool and low workpiece quality.

[0137] First, cutting experiments on high-strength gear steel with different tool angles are carried out. Based on the wear amount of the tool and the fluctuation of the cutting force, by comparing the cutting experiments with different cutting-in angles, the effective rake angle and clearance angle of the tool are obtained when the tool life is the longest and the cutting force fluctuation is the smallest. In this embodiment, based on the cutting experiment data, it is found that when the rake angle of the tool is generally 15° to 30° and the clearance angle of the tool is 10° to 20°, the tool wear amount is small and the cutting force fluctuation is small. Then the constraint conditions for the actual rake angle of the tool are:

[0138] 15° ≤ α s = α c + α t + α v ≤ 30°

[0139] The constraint conditions for the actual clearance angle of the tool are:

[0140] 10° ≤ β s = α c + β t + α v ≤ 20°.

[0141] Since it is obtained from the above formula:

[0142]

[0143]

[0144] v v = 2πf v h v 。

[0145] Then the obtained α c and α v are substituted into the constraint conditions of the actual rake angle of the cutting tool, and the rake angle constraint is obtained as:

[0146]

[0147] The obtained α c and α v are substituted into the constraint conditions of the actual clearance angle of the cutting tool, and the clearance angle constraint is obtained as:

[0148]

[0149] In this embodiment, by considering the actual vibration amplitude of the ultrasonic-assisted precision machining device under the cutting force load, the pre-tightening cutting force is optimized, the cutting parameters are matched with the ultrasonic vibration amplitude, and the precision machining of the gear keyway is realized. Multiple machining paths of the ultrasonic-assisted precision machining device refer to Figure 3 , where L 1 is the initial machining path without considering the force load, L 2 is the cutting path under the cutting force load, L 3 is the optimized cutting path of the ultrasonic-assisted precision machining device in this embodiment. It can be seen that the machining path of the ultrasonic-assisted precision machining device in this embodiment can significantly improve the machining accuracy. h 1 is the cutting depth difference between L 1 and L 2 , and h 2 is the cutting depth of L 2 .

[0150] In this embodiment, if the rake angle constraint, clearance angle constraint, and workpiece cutting depth value are not considered, the parameters in the actual cutting deviate from the set machining parameters, that is, deviate from the set machining allowance, resulting in machining errors. In addition, after deviating from the set angle (the set machining angle of the cutting tool is the optimal machining angle of the cutting tool), the cutting-in angle of the cutting tool is too large, and the tool wear is aggravated. By considering the constraint conditions of the actual rake angle of the cutting tool and the actual clearance angle of the cutting tool, Figure 3The middle L3 path improves the machining accuracy, can precisely machine high-strength and super-hard tooth surfaces, and improves the machining efficiency, workpiece quality and tool life. In the ultrasonic-assisted precision machining device of this embodiment, the electrical terminal impedance decreases as the cutting force load impedance increases, and this characteristic can be used for the automatic adjustment of the output power in ultrasonic plastic welding equipment.

[0151] Referring Figure 4 , an embodiment of the present invention also provides a system for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways. This ultrasonic-assisted precision machining system for high-strength and super-hard gear keyways includes a data acquisition unit 100, a first calculation unit 200, a second calculation unit 300, a third calculation unit 400, and a gear machining unit 500, where:

[0152] The data acquisition unit 100 is used to acquire the cutting force, ultrasonic vibration amplitude, and cutting force coefficient at various cutting depths in the ultrasonic-assisted precision machining device;

[0153] The first calculation unit 200 is used to calculate the unit cutting force amplitude according to the cutting force and the ultrasonic vibration amplitude, and calculate the tool angle change value and displacement change value according to the cutting force and the length of the tool for machining the gear keyway;

[0154] The second calculation unit 300 is used to calculate the workpiece cutting depth value according to the displacement change value, the cutting force coefficient, and the unit cutting force amplitude;

[0155] The third calculation unit 400 is used to calculate the actual rake angle and actual clearance angle of the tool according to the tool angle change value, and constrain the actual rake angle and actual clearance angle of the tool to obtain the rake angle constraint and clearance angle constraint;

[0156] The gear machining unit 500 is used to machine the gear keyway according to the rake angle constraint, the clearance angle constraint, and the workpiece cutting depth value.

[0157] It should be noted that since the system for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways in this embodiment and the above-mentioned method for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways are based on the same inventive concept, the corresponding content in the method embodiment also applies to this system embodiment, and will not be elaborated here.

[0158] An embodiment of the present invention also provides a device for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways, including: at least one control processor and a memory for communicating with at least one control processor.

[0159] The memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs and non-transitory computer-executable programs. In addition, the memory may include high-speed random access memory, and may also include non-transitory memory, such as at least one magnetic disk storage device, a flash memory device, or other non-transitory solid-state storage devices. In some embodiments, the memory optionally includes a memory remotely disposed relative to the processor, and these remote memories can be connected to the processor through a network. Examples of the above-mentioned network include but are not limited to the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0160] The non-transitory software programs and instructions required to implement the method for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways in the above embodiments are stored in the memory. When executed by a processor, the method for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways in the above embodiments is executed. For example, the method steps S100 to S500 described above are executed. Figure 1 in the method steps S100 to S500.

[0161] The system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, that is, they may be located in one place, or may be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0162] The embodiments of the present invention also provide a computer-readable storage medium. The computer-readable storage medium stores computer-executable instructions. When the computer-executable instructions are executed by one or more control processors, the one or more control processors can execute the method for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways in the above method embodiments. For example, the functions of the method steps S100 to S500 described above are executed. Figure 1 in the method steps S100 to S500.

[0163] Those of ordinary skill in the art will understand that all or some of the steps and systems disclosed in the above methods can be implemented as software, firmware, hardware, and appropriate combinations thereof. Some or all of the physical components can be implemented as software executed by a processor, such as a central processing unit, a digital signal processor, or a microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include a computer storage medium (or non-transitory medium) and a communication medium (or transitory medium). As is well known to those of ordinary skill in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information, such as computer-readable instructions, data structures, program modules, or other data. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disk (DVD) or other optical disk storage, magnetic cassettes, tapes, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information and can be accessed by a computer. In addition, it is well known to those of ordinary skill in the art that communication media typically contains computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transmission mechanism, and can include any information delivery medium.

[0164] The above is a specific description of the preferred implementation of the embodiments of the present application. However, the embodiments of the present application are not limited to the above embodiments. Those skilled in the art can also make various equivalent deformations or substitutions without departing from the spirit of the embodiments of the present application. These equivalent deformations or substitutions are all included within the scope defined by the claims of the embodiments of the present application.

Claims

1. A method for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways, characterized in that, the method for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways includes: Obtaining the cutting force, ultrasonic vibration amplitude, and cutting force coefficient at various cutting depths in the ultrasonic-assisted precision machining device; Calculating the unit cutting force amplitude according to the cutting force and the ultrasonic vibration amplitude, and calculating the tool angle change value and displacement change value according to the cutting force and the length of the tool for machining the gear keyway; Calculating the workpiece cutting depth value according to the displacement change value, the cutting force coefficient, and the unit cutting force amplitude; Calculating the actual rake angle and actual clearance angle of the tool according to the tool angle change value, and constraining the actual rake angle and actual clearance angle of the tool to obtain the rake angle constraint and clearance angle constraint; Machining the gear keyway according to the rake angle constraint, the clearance angle constraint, and the workpiece cutting depth value.

2. The method for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways according to claim 1, characterized in that, the tool angle change value and the displacement change value are calculated in the following manner: Calculating the tool angle change value as: Calculating the displacement change value as: Among them, α c represents the change value of the tool angle, F x represents the component cutting force in the x - direction of the cutting force, l represents the length of the tool for machining the gear keyway, E represents the elastic modulus, I represents the polar moment of inertia, L c represents the change value of the displacement.

3. The method for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways according to claim 2, characterized in that, the workpiece cutting depth value is calculated in the following manner: Among them, h represents the cutting depth value of the workpiece, b represents the cutting width, and k f represents the cutting force coefficient, and h d represents the ideal cutting depth, and ε i represents the unit cutting force amplitude.

4. The method for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways according to claim 3, characterized in that, the ideal cutting depth is calculated in the following manner: h d = h v + h - L c Among them, h v represents the ultrasonic vibration amplitude.

5. The method for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways according to claim 2, characterized in that, the actual rake angle and actual clearance angle of the tool are calculated in the following manner: Calculating the actual rake angle of the tool as: α s ＝α c +α t +α v Calculating the actual clearance angle of the tool as: β s ＝α c +β t +α v Among them, α s represents the actual rake angle of the tool, α c represents the tool angle change value, α t represents the theoretical rake angle of the tool, α v represents the tool angle change amount caused by ultrasonic vibration, β s represents the actual clearance angle of the tool, β t represents the theoretical clearance angle of the tool, v represents the cutting speed controlled by the gear shaper, v v represents the cutting speed caused by ultrasonic vibration, v v = 2πf v h v , f v represents the ultrasonic vibration frequency, h v represents the ultrasonic vibration amplitude.

6. The method for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways according to claim 5, characterized in that, constraining the actual rake angle and actual clearance angle of the tool to obtain the rake angle constraint and clearance angle constraint includes: Constraining the actual rake angle of the tool to obtain the rake angle constraint: Constraining the actual clearance angle of the tool to obtain the clearance angle constraint: Among them, F i represents the cutting force, l represents the length of the tool for machining the gear keyway, E represents the elastic modulus, I represents the polar moment of inertia, f v represents the ultrasonic vibration frequency, h v represents the ultrasonic vibration amplitude, and v represents the cutting speed controlled by the gear shaper.

7. A system for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways, characterized in that, the system for ultrasonic-assisted precision machining of high-strength and super-hard gear keyways includes: A data acquisition unit for obtaining the cutting force, ultrasonic vibration amplitude, and cutting force coefficient at various cutting depths in the ultrasonic-assisted precision machining device; A first calculation unit for calculating the unit cutting force amplitude according to the cutting force and the ultrasonic vibration amplitude, and calculating the tool angle change value and displacement change value according to the cutting force and the length of the tool for machining the gear keyway; A second calculation unit for calculating the workpiece cutting depth value according to the displacement change value, the cutting force coefficient, and the unit cutting force amplitude; A third calculation unit, configured to calculate an actual rake angle and an actual clearance angle of the cutting tool according to the cutting tool angle change value, and perform constraints on the actual rake angle and the actual clearance angle of the cutting tool to obtain a rake angle constraint and a clearance angle constraint; A gear machining unit, configured to machine the gear keyway according to the rake angle constraint, the clearance angle constraint, and the workpiece cutting depth value.

8. An apparatus for ultrasonically assisted precision machining of high-strength superhard gear keyways, characterized in that, it includes at least one control processor and a memory communicatively connected to the at least one control processor; the memory stores instructions executable by the at least one control processor, and the instructions are executed by the at least one control processor to enable the at least one control processor to execute the method for ultrasonically assisted precision machining of high-strength superhard gear keyways according to any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, the computer-readable storage medium stores computer-executable instructions for causing a computer to execute the method for ultrasonically assisted precision machining of high-strength superhard gear keyways according to any one of claims 1 to 6.

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