Vertical ultrasonic broaching machine and assembling and debugging method thereof

Abstract

The invention belongs to the technical field of machining, and particularly relates to a vertical ultrasonic broaching machine and an assembling and debugging method thereof.The broaching machine comprises an ultrasonic auxiliary device, and the ultrasonic auxiliary device comprises an ultrasonic vibration mechanism; the ultrasonic vibration mechanism comprises an ultrasonic vibration amplitude-change pole, a cylinder, a limiting block, a gasket, a gasket, a piezoelectric actuator and an ultrasonic power supply; a circle of step protrusion is arranged in the middle of the ultrasonic vibration amplitude-change pole. A limiting block is arranged at the joint of the step bulge and the cylinder; a gasket is arranged between the input end of the ultrasonic vibration amplitude-change pole and the fixing plate; and a gasket is arranged between the piezoelectric actuator and the gasket. By comprehensively adjusting the thicknesses of the gasket and the gasket and the position of the limiting block, the phenomenon that the piezoelectric actuator is burnt out due to the fact that the pretightening force of the piezoelectric actuator is too large is avoided, and the problem that the excitation amplitude and frequency of the piezoelectric actuator are small due to the fact that the pressure at the joint of the ultrasonic vibration amplitude-change pole and the piezoelectric actuator is too large is solved.

Description

Technical Field

[0001] The invention relates to the technical field of machining, and in particular to a vertical ultrasonic broaching machine and an assembly and debugging method thereof. Background Art

[0002] As a common metal cutting machine tool, broaching machines can be used to process the inner surface (such as generating round holes, square holes, spline holes, etc.) and outer surface (such as planes, forming surfaces, grooves, etc.) of workpieces. The basic working principle of a broaching machine is that the broaching tool performs linear motion to cut (broach) the surface of the workpiece to be processed to achieve subtractive processing; and the tools of some broaching machines can perform multi-layer and multiple cutting of the workpiece in one stroke. Therefore, broaching machines generally have high processing efficiency and processing accuracy, and are especially suitable for large-scale parts production. However, the broaching machine has insufficient thermal management energy during the broaching process, which can easily lead to problems such as excessive tool wear and cutting deformation, greatly limiting the processing performance of the broaching machine.

[0003] With the development of technology, ultrasonic-assisted technology has been widely used in the field of machine tool processing, and special ultrasonic machine tools have emerged. As the name suggests, ultrasonic machine tools are equipment that can use ultrasonic vibration energy for precision processing. They are particularly suitable for processing hard and brittle materials and difficult-to-process metal materials. For example, they have shown significant advantages in processing titanium alloys, high-temperature alloys, engineering ceramics, ceramic-based composite materials, etc. Ultrasonic machine tools use high-frequency vibrations to generate a slight impact between the tool and the workpiece, effectively reducing the cutting force and cutting temperature, reducing tool wear and burrs, thereby improving the overall processing accuracy of the machine tool and the processing quality of the workpiece surface.

[0004] Although the combination of ultrasonic-assisted technology has brought many advantages to machine tool processing, the high load during the broaching process has also brought adverse effects to related devices. The core components of the ultrasonic-assisted vibration system mainly include ultrasonic amplitude transformers and piezoelectric actuators. When high-load broaching actions are performed, the performance of the piezoelectric actuator and the amplitude transformer will be significantly limited, and the piezoelectric actuator may even be burned, thereby reducing the processing accuracy and stability of the broaching machine. Therefore, the present application is to provide a vertical ultrasonic broaching machine and a debugging method thereof, which can meet the requirements of stable amplitude under high load, avoid damage to piezoelectric ceramics, and ensure the processing accuracy and efficiency of the entire ultrasonic broaching machine. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art and provide a vertical ultrasonic broaching machine and an assembly and debugging method thereof, which can ensure that the piezoelectric ceramics are not damaged, while providing a stable output amplitude and significantly improving the processing accuracy and efficiency.

[0006] The technical solution of the present invention is:

[0007] The present invention first provides a vertical ultrasonic broaching machine, comprising a machine tool body and an ultrasonic auxiliary device, wherein the ultrasonic auxiliary device comprises a fixed plate, on which an ultrasonic vibration mechanism is arranged; the ultrasonic vibration mechanism comprises an ultrasonic vibration amplitude transformer, a cylinder, a limit block, a washer, a gasket, a piezoelectric actuator and an ultrasonic power supply;

[0008] A circle of stepped protrusions is provided in the middle of the ultrasonic vibration horn, and the two sides of the stepped protrusions are the input end and the output end respectively. The input end of the ultrasonic vibration horn extends into the cylinder, and the fixing bolt passes through the stepped protrusions and the cylinder and is fixedly connected with the fixing plate;

[0009] A limit block is provided at the connection between the step protrusion and the cylinder, and the limit block is used to adjust the contact pressure between the step protrusion and the end surface of the cylinder;

[0010] A gasket is arranged between the input end of the ultrasonic vibration amplitude transformer and the fixed plate; a piezoelectric actuator is arranged inside the cylinder, the piezoelectric actuator is connected to the ultrasonic power supply, and the piezoelectric actuator is annular and is sleeved on the outside of the input end of the ultrasonic vibration amplitude transformer; a gasket is arranged between the piezoelectric actuator and the gasket.

[0011] Furthermore, the machine tool body includes a base, a bed, a screw rod, a workbench, a tool clamping system, a broach and a clamping device. The bed is arranged on the base, the lower end of the screw rod is connected to the base, one end of the screw rod is connected to the motor arranged in the bed, and a workbench is arranged on the screw rod. When the motor drives the screw rod to rotate, the workbench can be driven to move up and down; the workbench is used to fix and install the workpiece to be processed.

[0012] Furthermore, a bracket is provided on the bed, and a tool clamping system is installed on the bracket; the upper end of the broach is movably connected to the tool clamping system, and the lower end of the broach passes through the workbench and is connected to the clamping device below, one end of the ultrasonic auxiliary device is connected to the clamping device, and the other end of the ultrasonic auxiliary device is connected to the base.

[0013] Furthermore, three sets of ultrasonic auxiliary devices are arranged on the base, and the three sets of ultrasonic auxiliary devices are arranged in an equilateral triangle on the base.

[0014] Furthermore, the axes of the ultrasonic vibration horns in the three sets of ultrasonic auxiliary devices are all located at the vertices of an equilateral triangle.

[0015] Furthermore, the output end of the ultrasonic vibration horn is connected to a vibration plate, and the vibration plate is connected to a resonance plate. The vibration plate transmits the vibration of the ultrasonic vibration horn to the resonance plate, so that the resonance plate generates stable axial vibration.

[0016] Furthermore, the gasket is cylindrical and can be made of brass. The contact pressure between the ultrasonic vibration amplitude transformer and the fixing plate can be adjusted by installing gaskets of different thicknesses.

[0017] Furthermore, the inner diameter of the gasket is adapted to the diameter of the input end of the ultrasonic vibration horn, and the outer diameter is the same as the outer diameter of the gasket. The gasket can adopt a laminated structure of rubber and high manganese steel.

[0018] Furthermore, the sum of the lengths of the gasket, the washer and the input end of the ultrasonic vibration transformer is adapted to the length of the cylinder; preferably, during the initial assembly, the sum of the lengths of the gasket, the gasket and the input end of the ultrasonic vibration transformer is kept equal to the length of the cylinder to facilitate subsequent adjustment of the thickness of the gasket and the gasket.

[0019] Furthermore, the limit block can be a nut, and mounting holes matching the fixing bolts are arranged on the step protrusions of the cylinder and the ultrasonic vibration transformer. The fixing bolts pass through the mounting holes on the step protrusions, the limit block and the mounting holes on the cylinder in sequence and are connected to the fixing plate. The limit block can rotate on the fixing bolt to change its position. When the limit block moves away from the fixing plate, the limit block can bear more pressure from the ultrasonic vibration transformer, thereby reducing the pressure exerted on the cylinder by the step protrusion of the ultrasonic vibration transformer.

[0020] Furthermore, the ultrasonic vibration transformer is a one-dimensional axial vibration transformer, and the output end is the vibration mode peak position of the ultrasonic vibration transformer. The output end adopts a cone shape to meet the high bending moment stiffness requirements and is used to amplify the ultrasonic vibration amplitude and vibration speed. The step protrusion of the ultrasonic vibration transformer is the vibration mode node of the ultrasonic vibration transformer, and its vibration amplitude is 0, so as to avoid the transmission of ultrasonic vibration to the machine tool and reduce the loss of ultrasonic energy.

[0021] Furthermore, the piezoelectric actuator uses piezoelectric ceramics, and the ultrasonic power supply can convert industrial electricity (220V) into ultrasonic frequency power. Under the action of the ultrasonic power supply, the piezoelectric actuator will generate reciprocating periodic vibrations, thereby exciting the ultrasonic vibration amplitude transformer to generate vibrations.

[0022] The present invention also provides a special debugging method for the aforementioned vertical ultrasonic broaching machine, which specifically includes the following steps:

[0023] S1. Calculate the critical strain value of the piezoelectric actuator

[0024] A strain monitoring system is set at the input end of the ultrasonic vibration horn. The strain monitoring system includes a strain gauge, a charge amplifier, data acquisition and analysis software, and a computer. The strain collected by the strain monitoring system is recorded as ε x , then calculate according to the following formula:

[0025] σ x =Eεx , (1)

[0026] where σ x is the stress of the vertical section, E is the elastic modulus, which is determined by the physical properties of the material (can be directly queried or obtained through measurement experiments, such as the elastic modulus of stainless steel is 200GPa);

[0027] F x =σ x A, (2)

[0028] Among them, F x is the preload force of the piezoelectric actuator, A is the cross-sectional area of ​​the piezoelectric actuator, and the preload force of the piezoelectric actuator is adjusted by successively increasing the thickness of the gasket, so that the preload force increases successively until the critical strain value when the piezoelectric actuator burns out is obtained, which is recorded as ε max , and the critical preload value is also obtained.

[0029] S2. Preliminary assembly and debugging

[0030] First, install the ultrasonic vibration mechanism according to the standard size, that is, the sum of the lengths of the gasket, washer and the input end of the ultrasonic vibration horn is the same as the length of the cylinder. Apply a specific pressure load to the output end of the ultrasonic vibration horn, and arrange strain gauges at the center of the gasket, washer and the input end of the ultrasonic vibration horn. The measured strains are recorded as ε 1 , ε 2 , ε 3 To avoid excessive preload of the piezoelectric actuator, it is necessary to ensure that ε 1 , ε 2 , ε 3 The values ​​of are all smaller than the ε obtained in step S1. max The value of .

[0031] ε 1 , ε 2 , ε 3 The value of can be adjusted in one or more of the following ways:

[0032] 1) Adjust the position of the limit block. Adjust the limit block upward to transfer the pressure load to the fixing bolt; reduce the preload at the input end of the ultrasonic vibration horn, thereby reducing the corresponding strain value; otherwise, the corresponding strain value will increase;

[0033] 2) When the thickness of the gasket is reduced, the preload force between the piezoelectric actuator, the amplitude rod, and the gasket will be reduced, thereby reducing the corresponding strain value; conversely, the preload force will be increased, thereby increasing the corresponding strain value;

[0034] 3) Reducing the thickness of the gasket will reduce the preload force between the piezoelectric actuator, the amplitude rod, and the gasket, thereby reducing the corresponding strain value; conversely, it will increase the preload force, thereby increasing the corresponding strain value.

[0035] S3. Testing

[0036] Start the ultrasonic vibration mechanism, use the Doppler laser vibrometer to measure the vibration amplitude and frequency at the output end of the ultrasonic vibration transformer, and make adjustments based on the measurement results:

[0037] 1) If the vibration amplitude meets the pre-designed parameter requirements, no adjustment is required;

[0038] 2) If the vibration amplitude does not meet the pre-designed parameter requirements, the position of the limit block or the thickness of the gasket is adjusted to make the vibration amplitude meet the design requirements.

[0039] Furthermore, in step S3, if the vibration amplitude does not meet the pre-designed parameter requirements and the vibration amplitude is lower than 20% of the target vibration amplitude, the limit block is first moved upward so that the load is transferred to the fixing bolt so that the ultrasonic vibration amplitude is not lower than 80% of the design value; then the thickness of the gasket is adjusted so that the vibration amplitude meets the design requirements.

[0040] The principle of debugging in the present invention is: since the step protrusion of the ultrasonic vibration horn is located at the node of the ultrasonic vibration horn vibration type, under the excitation of the piezoelectric actuator, its vibration amplitude is very small; adjusting the position of the limit block between the step protrusion and the cylinder can adjust the contact pressure between the step protrusion of the ultrasonic vibration horn and the cylinder, specifically: adjusting the limit block upward (away from the direction of the cylinder) can transfer the pressure load to the fixing bolt, so that the ultrasonic vibration horn reduces the squeezing force of the gasket, washer and piezoelectric actuator in the cylinder. Reducing the thickness of the gasket will reduce the preload between the piezoelectric actuator, the ultrasonic vibration horn and the washer, and vice versa, it will increase the preload. Reducing the thickness of the washer will also reduce the preload between the piezoelectric actuator, the horn and the washer; vice versa, it will increase the preload.

[0041] Compared with the prior art, the present invention has the following beneficial effects: the vertical ultrasonic broaching machine in the present invention can prevent the piezoelectric actuator from being burned out due to excessive pre-tightening force by comprehensively adjusting the thickness of the gasket and the gasket and the position of the limit block, thereby solving the problem that the pressure at the connection between the ultrasonic vibration amplitude transformer and the piezoelectric actuator is too high, resulting in a small amplitude and frequency of the piezoelectric actuator excitation. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is a three-dimensional schematic diagram of the ultrasound-assisted device in Example 1 of the present invention;

[0043] Figure 2is a side view of the ultrasound-assisted device in Example 1 of the present invention;

[0044] Figure 3 is a cross-sectional view of the ultrasound-assisted device in Example 1 of the present invention;

[0045] Figure 4 is a three-dimensional schematic diagram of the ultrasonic vibration horn in Example 1 of the present invention;

[0046] Figure 5 is a cross-sectional view of the ultrasonic vibration horn in Example 1 of the present invention;

[0047] Figure 6 is an overall exploded schematic diagram of the ultrasound-assisted device in Example 1 of the present invention;

[0048] Figure 7 is a schematic diagram of assembling the ultrasonic auxiliary device on the broaching machine in Example 1 of the present invention;

[0049] In the figure: 1-fixed plate, 2-ultrasonic vibration amplitude transformer, 21-step protrusion, 22-input end, 23-output end, 24-mounting hole, 3-cylinder, 4-gasket, 5-washer, 6-piezoelectric actuator, 7-limit block, 8-fixing bolt, 9-base, 10-vibration plate. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is described below in conjunction with the accompanying drawings and specific embodiments. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions that the present invention can implement, so they have no technical substantive significance. Any structural modification, change in proportional relationship or adjustment of size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope of the technical content disclosed by the present invention. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of concepts in the present invention.

[0051] Example 1

[0052] like Figure 1-7As shown, the vertical ultrasonic broaching machine in this embodiment includes a machine tool body and an ultrasonic auxiliary device, wherein the ultrasonic auxiliary device includes a fixed plate 1, on which an ultrasonic vibration mechanism is arranged; the ultrasonic vibration mechanism includes an ultrasonic vibration horn 2, a cylinder 3, a limit block 7, a washer 5, a gasket 4, a piezoelectric actuator 6 and an ultrasonic power supply; a circle of step protrusions 21 are arranged in the middle of the ultrasonic vibration horn 2, and the two sides of the step protrusion 21 are respectively an input end 22 and an output end 23, the input end 22 of the ultrasonic vibration horn 2 extends into the interior of the cylinder 3, and the fixing bolt 8 passes through the step protrusion 21. The protrusion 21 and the cylinder 3 are fixedly connected to the fixed plate 1; a limit block 7 is provided at the connection between the step protrusion 21 and the cylinder 3, and the limit block 7 is used to adjust the contact pressure between the step protrusion 21 and the end face of the cylinder 3; a gasket 4 is provided between the input end 22 of the ultrasonic vibration amplitude transformer 2 and the fixed plate 1; a piezoelectric actuator 6 is provided inside the cylinder 3, the piezoelectric actuator 6 is connected to the ultrasonic power supply, and the piezoelectric actuator 6 is annular and is sleeved on the outside of the input end 22 of the ultrasonic vibration amplitude transformer 2; a gasket 5 is provided between the piezoelectric actuator 6 and the gasket 4.

[0053] In this embodiment, the machine tool body includes a base 9, a bed, a screw rod, a workbench, a tool clamping system, a broach and a clamping device. The bed is arranged on the base 9, the lower end of the screw rod is connected to the base 9, and one end of the screw rod is connected to a motor arranged in the bed. A workbench is arranged on the screw rod. When the motor drives the screw rod to rotate, it can drive the workbench to move up and down; the workbench is used to fix the workpiece to be processed, and a bracket is arranged on the bed, and a tool clamping system is installed on the bracket; the upper end of the broach is movably connected to the tool clamping system, and the lower end of the broach is connected to the clamping device below after passing through the workbench, one end of the ultrasonic auxiliary device is connected to the clamping device, and the other end of the ultrasonic auxiliary device is connected to the base 9.

[0054] In this embodiment, three sets of ultrasonic auxiliary devices are arranged on the base 9 in an equilateral triangle. The axes of the ultrasonic vibration horn 2 in the three sets of ultrasonic auxiliary devices are all located at the vertices of the equilateral triangle. The output end 23 of the ultrasonic vibration horn 2 is connected to a vibration plate, which is connected to a resonance plate. The vibration plate transmits the vibration of the ultrasonic vibration horn 2 to the resonance plate, so that the resonance plate generates stable axial vibration.

[0055] In this embodiment, the limit block 7 can be a nut, and a mounting hole 24 matching with the fixing bolt 8 is provided on the step protrusion 21 of the cylinder 3 and the ultrasonic vibration horn 2. The fixing bolt 8 passes through the mounting hole 24 on the step protrusion 21, the limit block 7 and the mounting hole 24 on the cylinder 3 in sequence and is connected to the fixing plate 1. The limit block 7 can rotate on the fixing bolt 8 to change its position. When the limit block 7 moves away from the fixing plate 1, the limit block 7 can bear more pressure from the ultrasonic vibration horn 2, thereby reducing the pressure of the step protrusion 21 of the ultrasonic vibration horn 2 on the cylinder 3.

[0056] In this embodiment, the gasket 4 is cylindrical and made of brass. The contact pressure between the ultrasonic vibration amplitude transformer 2 and the fixed plate 1 can be adjusted by installing gaskets 4 of different thicknesses. The washer 5 is a laminated structure of rubber and high manganese steel. The inner diameter of the washer 5 is adapted to the diameter of the input end 22 of the ultrasonic vibration amplitude transformer 2, and the outer diameter is the same as the outer diameter of the gasket 4.

[0057] In this embodiment, the sum of the lengths of the gasket 5, the washer 4 and the input end 22 of the ultrasonic vibration transformer 2 is adapted to the length of the cylinder 3; specifically, during the initial assembly, the sum of the lengths of the gasket 5, the gasket 4 and the input end 22 of the ultrasonic vibration transformer 2 is selected to be equal to the length of the cylinder 3, so as to facilitate the subsequent adjustment of the thickness of the gasket 5 and the gasket 4 according to actual conditions.

[0058] In this embodiment, the ultrasonic vibration transformer 2 is a one-dimensional axial vibration transformer, and the output end 23 is the vibration mode peak position of the ultrasonic vibration transformer 2. The output end 23 adopts a cone shape to meet the high bending moment stiffness requirements and is used to amplify the ultrasonic vibration amplitude and vibration speed. The step protrusion 21 of the ultrasonic vibration transformer 2 is the vibration mode node of the ultrasonic vibration transformer 2, and its vibration amplitude is 0 to avoid the ultrasonic vibration from being transmitted to the machine tool and reduce the loss of ultrasonic energy.

[0059] In this embodiment, the piezoelectric actuator 6 uses piezoelectric ceramics, and the ultrasonic power supply can convert industrial electricity (220V) into ultrasonic frequency power. Under the action of the ultrasonic power supply, the piezoelectric actuator 6 will generate reciprocating periodic vibrations, thereby exciting the ultrasonic vibration transformer 2 to generate vibrations.

[0060] The debugging method of the present invention is described in detail below.

[0061] The principle of debugging is: since the step protrusion of the ultrasonic vibration horn is located at the node of the ultrasonic vibration horn vibration type, its vibration amplitude is very small under the excitation of the piezoelectric actuator; adjusting the position of the limit block between the step protrusion and the cylinder can adjust the contact pressure between the step protrusion of the ultrasonic vibration horn and the cylinder, specifically: adjusting the limit block upward (away from the cylinder) can transfer the pressure load to the fixing bolt, so that the ultrasonic vibration horn reduces the squeezing force of the gasket, washer and piezoelectric actuator in the cylinder. Reducing the thickness of the gasket will reduce the preload between the piezoelectric actuator, ultrasonic vibration horn and washer, and vice versa, it will increase the preload. Reducing the thickness of the washer will also reduce the preload between the piezoelectric actuator, horn and washer; vice versa, it will increase the preload.

[0062] Assuming that the target broaching machine has a cutting (pressure) load of 20 tons, the pressure load received by each of the three ultrasonic-assisted devices is one-third of 20 tons, that is, 6.67 tons.

[0063] S1. First calculate the critical strain value when the piezoelectric actuator (piezoelectric ceramic) burns out, which can be obtained through the preload test of the piezoelectric actuator, that is, to conduct ultrasonic power supply excitation piezoelectric actuator experiments under different preloads. Assume that the piezoelectric actuator installed on the ultrasonic vibration horn has an inner diameter of 30mm, an outer diameter of 60mm, and a thickness of 10mm.

[0064] Considering the impact of the broaching process, the pressure load at the output end of the ultrasonic vibration transformer will be greater than 6.67 tons. Therefore, a pressure load of 7 tons, i.e. 70KN, can be input at the output end of the ultrasonic vibration transformer, and then the thickness of the gasket can be adjusted to change the preload. The preload is identified by the strain monitoring system bonded to the input end of the ultrasonic vibration transformer. The strain monitoring system can be composed of a strain gauge, a charge amplifier, Donghua data acquisition and analysis software, and a computer. The strain collected by the strain monitoring system is recorded as ε x , then calculate according to the following formula:

[0065] σ x =Eε x , (1)

[0066] where σ x is the stress of the vertical section, and E is the elastic modulus, which is determined by the physical properties of the material (can be directly queried or measured, for example, the elastic modulus of stainless steel is 200 GPa, i.e. 2×10 11 Pa);

[0067] F x =σ x A, (2)

[0068] F xis the preload force of the piezoelectric actuator, and A is the annular cross-sectional area of ​​the piezoelectric actuator, which is calculated to be 0.00212 square meters, i.e. 2.12×10 -3 m 2 .

[0069] The thickness of the gasket can be increased in sequence to change the preload force of the piezoelectric actuator. For example, through the strain monitoring system, experiments can be carried out when the preload force is 0.5KN, 1KN, 2KN, 4KN, 8KN, 16KN, 32KN and 64KN, and finally the critical strain value when the piezoelectric actuator burns out can be obtained, which is recorded as ε max , of course, the critical preload value will also be obtained at the same time.

[0070] S2. Install the ultrasonic vibration mechanism according to the standard size, so that the sum of the lengths of the gasket, the washer and the input end of the ultrasonic vibration horn is the same as the length of the cylinder. For example, set the gasket length (thickness) to L. 1 , the length (thickness) of the gasket is l 2 , the length of the ultrasonic vibration amplitude transformer input end is l 3 , the length (height) of the cylinder is L 4 , then: L 4 =L 1 +L 2 +L 3 .

[0071] At the output end of the ultrasonic vibration horn, a load of 6.67 tons, i.e. 66KN, is applied. Strain gauges are arranged at the center of the gasket, washer, and input end of the ultrasonic vibration horn. The measured strains are recorded as ε 1 , ε 2 , ε 3 ; To avoid excessive preload of the piezoelectric actuator, it is necessary to ensure that ε 1 , ε 2 , ε 3 The value of max Therefore, the relevant preload can be reduced by reducing the length (thickness) of the gasket, thereby reducing ε 1 , ε 2 , ε 3 The value of is reduced;

[0072] S3. Start the ultrasonic vibration mechanism, measure the vibration amplitude and frequency of the output end of the ultrasonic vibration horn by using a Doppler laser vibrometer, and make adjustments based on the measurement results:

[0073] 1) If the vibration amplitude meets the pre-designed parameter requirements, no adjustment is required;

[0074] 2) If the vibration amplitude does not meet the pre-designed parameter requirements, the position of the limit block or the thickness of the gasket is adjusted to make the vibration amplitude meet the design requirements; more specifically, if the vibration amplitude is lower than 20% of the target vibration amplitude, the limit block can be first moved upward to transfer the load to the fixing bolt so that the ultrasonic vibration amplitude is not lower than 80% of the design value; then the thickness of the gasket is adjusted to make the vibration amplitude meet the design requirements.

[0075] The above are only some embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have combinations and modifications of the aforementioned various technical features. Without departing from the spirit and scope of the present invention, those skilled in the art may improve, modify, or replace the present invention with equivalents, or apply the structure or method of the present invention to other fields to achieve the same effect, which all fall within the scope of protection included in the present invention.

Claims

1. A vertical ultrasonic broaching machine, comprising a machine tool body, It is characterized in that It also includes an ultrasonic auxiliary device, which includes a fixing plate on which an ultrasonic vibration mechanism is arranged; The ultrasonic vibration mechanism includes an ultrasonic vibration horn, a cylinder, a limit block, a washer, a gasket, a piezoelectric actuator and an ultrasonic power supply; A circle of stepped protrusions is provided in the middle of the ultrasonic vibration horn, and the two sides of the stepped protrusions are the input end and the output end respectively. The input end of the ultrasonic vibration horn extends into the cylinder, and the fixing bolt passes through the stepped protrusions and the cylinder and is fixedly connected with the fixing plate; A limit block is provided at the connection between the step protrusion and the cylinder, and the limit block is used to adjust the contact pressure between the step protrusion and the end surface of the cylinder; A gasket is provided between the input end of the ultrasonic vibration horn and the fixing plate; A piezoelectric actuator is arranged inside the cylinder, the piezoelectric actuator is connected to the ultrasonic power supply, and the piezoelectric actuator is annular and sleeved on the outside of the input end of the ultrasonic vibration horn; A gasket is arranged between the piezoelectric actuator and the gasket.

2. The vertical ultrasonic broaching machine according to claim 1, Features: The machine tool body includes a base, a bed, a screw, a workbench, a tool clamping system, a broach and a clamping device. The base is provided with a bed, the lower end of the screw is connected to the base and to a motor arranged in the bed, and a workbench is provided on the screw, the motor drives the screw to rotate and thus drives the workbench to move up and down; a bracket is provided on the bed, and a tool clamping system is installed on the bracket; the upper end of the broach is movably connected to the tool clamping system, and the lower end of the broach is connected to the clamping device after passing through the workbench, one end of the ultrasonic auxiliary device is connected to the clamping device, and the other end of the ultrasonic auxiliary device is connected to the base.

3. The vertical ultrasonic broaching machine according to claim 2, Features: Three sets of ultrasonic auxiliary devices are arranged on the base, and the three sets of ultrasonic auxiliary devices are arranged in an equilateral triangle on the base.

4. The vertical ultrasonic broaching machine according to claim 3, Features: The axes of the ultrasonic vibration horn in the ultrasonic auxiliary device are all located at the vertices of an equilateral triangle.

5. The vertical ultrasonic broaching machine according to claim 2, Features: The output end of the ultrasonic vibration horn is connected to a vibration plate, and the vibration plate is connected to a resonance plate. The vibration plate transmits the vibration of the ultrasonic vibration horn to the resonance plate, so that the resonance plate generates stable axial vibration.

6. The vertical ultrasonic broaching machine according to claim 1, Features: The gasket is cylindrical, and the contact pressure between the ultrasonic vibration transformer and the fixed plate is adjusted by selecting and installing gaskets of different thicknesses; the inner diameter of the gasket is adapted to the diameter of the input end of the ultrasonic vibration transformer, and the outer diameter is the same as the outer diameter of the gasket; the sum of the lengths of the gasket, the gasket and the input end of the ultrasonic vibration transformer is adapted to the length of the cylinder.

7. The vertical ultrasonic broaching machine according to claim 1, Features: The ultrasonic vibration horn is a one-dimensional axial vibration horn, and the output end is the vibration type wave peak position of the ultrasonic vibration horn. The output end adopts a cone shape to meet the high bending moment stiffness requirement and is used to amplify the ultrasonic vibration amplitude and vibration speed. The step protrusion of the ultrasonic vibration horn is the vibration type node of the ultrasonic vibration horn, and its vibration amplitude is 0, so as to avoid the ultrasonic vibration from being transmitted to the machine tool and reduce the ultrasonic energy loss.

8. The vertical ultrasonic broaching machine according to claim 1, Features: The piezoelectric actuator adopts piezoelectric ceramics. Under the action of the ultrasonic power supply, the piezoelectric actuator generates high-frequency vibration, which stimulates the ultrasonic vibration amplitude transformer to generate high-frequency vibration.

9. An assembly and debugging method for a vertical ultrasonic broaching machine, wherein the vertical ultrasonic broaching machine is the broaching machine according to any one of claims 1 to 8, It is characterized in that The following steps are involved: S1. Calculate the critical strain value of the piezoelectric actuator A strain monitoring system is set at the input end of the ultrasonic vibration horn. The strain monitoring system includes a strain gauge, a charge amplifier, data acquisition and analysis software, and a computer. The strain collected by the strain monitoring system is recorded as ε x , then calculate according to the following formula: s x =Ee x , (1) Where σ x is the stress in the vertical section, E is the elastic modulus, which is determined by the physical properties of the material; F x =s x A, (2) Where F x is the preload force of the piezoelectric actuator, A is the annular cross-sectional area of ​​the piezoelectric actuator, and the thickness of the gasket is increased successively to adjust the preload force of the piezoelectric actuator, and the critical strain value when the piezoelectric actuator burns out is obtained, which is recorded as ε max , and the critical preload value is also obtained; S2. Preliminary assembly and debugging The ultrasonic vibration mechanism is installed according to the standard size, that is, the sum of the lengths of the gasket, washer and the input end of the ultrasonic vibration horn is the same as the length of the cylinder. A pressure load is applied to the output end of the ultrasonic vibration horn, and strain gauges are arranged at the center of the gasket, washer and the input end of the ultrasonic vibration horn. The measured strains are recorded as ε 1 , ε 2 , ε 3 To avoid excessive preload of the piezoelectric actuator, it is necessary to ensure that ε 1 , ε 2 , ε 3 The values ​​of are all smaller than the ε obtained in step S1. max The value of Use one or more of the following methods to adjust: 1) Adjust the position of the limit block, adjust the limit block upward, transfer the pressure load to the fixing bolt; reduce the preload at the input end of the ultrasonic vibration horn, thereby reducing the corresponding strain value; otherwise, the corresponding strain value will be increased; 2) When the thickness of the gasket is reduced, the preload force between the piezoelectric actuator, the amplitude rod, and the gasket will be reduced, thereby reducing the corresponding strain value; conversely, the preload force will be increased, thereby increasing the corresponding strain value; 3) Reducing the thickness of the gasket will reduce the preload between the piezoelectric actuator, the amplitude rod, and the gasket, thereby reducing the corresponding strain value; conversely, it will increase the preload, thereby increasing the corresponding strain value; S3. Testing Start the ultrasonic vibration mechanism, measure the vibration amplitude at the output end of the ultrasonic vibration transformer by using a Doppler laser vibrometer, and perform processing based on the measurement results: 1) If the vibration amplitude meets the pre-designed parameter requirements, no adjustment is required; 2) If the vibration amplitude does not meet the pre-designed parameter requirements, the position of the limit block or the thickness of the gasket is adjusted to make the vibration amplitude meet the design requirements.

10. The debugging method of the vertical ultrasonic broaching machine according to claim 9, Features: In step S3, if the measured vibration amplitude is lower than 20% of the target vibration amplitude, first move the limit block upward so that the pressure load is transferred to the fixing bolt, so that the ultrasonic vibration amplitude is not lower than 80% of the design value; then adjust the thickness of the gasket so that the vibration amplitude meets the design requirements.

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