A double stroke quick tool servo device

Abstract

The utility model relates to fast knife servo device technical field, especially, it relates to a double stroke fast knife servo device. Including: in target displacement direction, series connection setting first displacement component and second displacement component, first displacement component and second displacement component are used for superimposed formation total target displacement amount, wherein, second displacement component is used for compensating the displacement error that first displacement component generates. The utility model series connection sets two displacement components to superimposed realization total expected displacement, namely total target displacement amount. Among them, first displacement component is used to reduce the error between the actual displacement of output and the expected displacement signal of input, second displacement component is used for further compensating and eliminating the error that first displacement component generates, and then the tracking error of fast knife servo device whole keeps at low level, to improve the machining precision.

Description

Technical Field

[0001] This utility model relates to the field of fast knife servo device technology, and in particular to a dual-stroke fast knife servo device. Background Technology

[0002] Fast-tool servo devices are a key technology for precision and ultra-precision machining of curved and micro-structured surfaces, and have become a crucial component of ultra-precision machine tools. Due to their high precision and other characteristics, fast-tool servo devices are widely used to achieve high-precision machining surfaces (such as some macro-micro combined surfaces) and contour accuracy, thus improving manufacturing levels in industrial and high-precision fields. They have been widely applied in laser fusion, aerospace, optics, instrumentation, and many other fields.

[0003] Existing servo-driven high-speed cutting tools control the movement of the cutting head using only a set of flexible hinges for axial displacement control. However, this drive structure has inherent, unavoidable systematic errors, which in turn affect the overall machining accuracy. Utility Model Content

[0004] To address one of the aforementioned technical problems, the technical solution adopted by this utility model is as follows:

[0005] According to one aspect of the present invention, a dual-stroke fast cutter servo device is provided, comprising: a primary displacement component and a secondary displacement component arranged in series in the target displacement direction, wherein the primary displacement component and the secondary displacement component are used to superimpose to form a total target displacement; wherein the secondary displacement component is used to compensate for the displacement error generated by the primary displacement component;

[0006] The primary displacement assembly includes a displacement base, a first piezoelectric ceramic, and a first flexible hinge;

[0007] The first flexible hinge includes a first hinge body and a plurality of first hinge arms disposed on the side wall of the first hinge body;

[0008] The outer end of the first hinge arm is fixedly connected to the displacement base; the displacement base is provided with a first driving chamber.

[0009] The first piezoelectric ceramic is disposed in the first driving chamber. The two opposite ends of the first piezoelectric ceramic abut against the inner wall of the displacement base and the bottom of the first hinge body, respectively. The first piezoelectric ceramic is used to control the two opposite ends to deform in the target displacement direction according to the input voltage control signal.

[0010] The secondary displacement assembly includes a second piezoelectric ceramic and a second flexible hinge;

[0011] The second flexible hinge includes a second hinge body and a plurality of second hinge arms disposed on the side wall of the second hinge body;

[0012] The second hinge arm is fixedly connected to the first hinge body; the first hinge body has a second drive chamber inside;

[0013] The second piezoelectric ceramic is disposed in the second driving chamber. The two opposite ends of the second piezoelectric ceramic abut against the inner wall of the first hinge body and the bottom of the second hinge body, respectively. The second piezoelectric ceramic is used to control the two opposite ends to deform in the target displacement direction according to the input voltage control signal.

[0014] This utility model has at least one of the following beneficial effects:

[0015] In this invention, two stages of displacement components are connected in series to achieve the total desired displacement, i.e., the total target displacement. The first-stage displacement component reduces the error between the actual output displacement and the input desired displacement signal, while the second-stage displacement component further compensates for and eliminates the error generated by the first-stage component. This keeps the overall tracking error of the fast-tool servo device at a low level, thereby improving machining accuracy. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A schematic diagram of a dual-stroke fast tool servo control system provided in this embodiment of the utility model;

[0018] Figure 2 A schematic diagram of the structure of the dual-stroke fast cutter servo device provided in this embodiment of the utility model;

[0019] Figure 3 This is an exploded view of the dual-stroke fast cutter servo device provided in an embodiment of the present invention;

[0020] Figure 4 A schematic diagram of the internal cutting structure of the dual-stroke fast cutter servo device provided in this embodiment of the utility model;

[0021] Figure 5 This is a schematic diagram showing the output signal trends of the PI control module (blue) and the error compensation module (red) in a dual-stroke fast-tool servo control system provided in an embodiment of this utility model, during the process of error convergence to near zero.

[0022] Figure Labels

[0023] 1. Primary displacement assembly; 10. First hinge body; 11. First hinge arm; 12. First piezoelectric ceramic; 13. Displacement base; 14. Sensor mounting slot; 15. Weight reduction through hole; 2. Secondary displacement assembly; 20. Second hinge body; 21. Second hinge arm; 22. Second piezoelectric ceramic; 3. Cutting head; 4. Displacement sensor bracket; 50. PI control module; 51. Inverse function module; 52. Time delay module; 53. Second signal addition / subtraction module; 54. Low-pass filter; 55. First signal addition / subtraction module; 56. Limiting module; 57. Third signal addition / subtraction module. Detailed Implementation

[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0025] As one possible embodiment of this utility model, such as Figure 1 As shown, a dual-stroke fast tool servo control system is provided, which is applied to a dual-stroke fast tool servo device, such as... Figures 2 to 4 As shown, the fast-tool servo device includes components in the target displacement direction (e.g., ... Figure 2 In the X direction, a primary displacement component 1 and a secondary displacement component 2 are connected in series. The primary displacement component 1 and the secondary displacement component 2 are used to superimpose to form the total target displacement. Among them, the secondary displacement component 2 is used to compensate for the displacement error generated by the primary displacement component 1.

[0026] Specifically, such as Figures 2 to 4 As shown, the dual-stroke fast-tool servo device in this embodiment includes the following structure:

[0027] The primary displacement component 1 includes a displacement base 13, a first piezoelectric ceramic 12, and a first flexible hinge.

[0028] The first flexible hinge includes a first hinge body 10 and a plurality of first hinge arms 11 disposed on the side wall of the first hinge body 10.

[0029] The outer end of the first hinge arm 11 is fixedly connected to the displacement base 13. The displacement base 13 has a first driving chamber inside.

[0030] The first piezoelectric ceramic 12 is disposed in the first driving chamber. The two opposite ends of the first piezoelectric ceramic 12 abut against the inner wall of the displacement base 13 and the bottom of the first hinge body 10, respectively. The first piezoelectric ceramic 12 is used to control the two opposite ends to undergo corresponding deformation in the target displacement direction according to the input voltage control signal.

[0031] In the fast servo tool post (i.e., the dual-stroke fast tool servo device of this embodiment), the flexible hinge is mainly used to enhance the dynamic performance and machining accuracy of the tool post. A flexible hinge is a mechanical component that uses the elastic deformation of a material to achieve motion transmission. Specifically, in this embodiment, the first hinge body 10 has an external cuboid shape, with corresponding first hinge arms 11 fixedly mounted on its four sides. Furthermore, the first hinge arms 11 have weight-reducing through holes 15 to reduce the stiffness of the first hinge arms 11 in the desired direction, allowing the first hinge arms 11 to move more easily in that direction. Simultaneously, it maintains the corresponding stiffness in directions where deformation is not desired (such as the hinge torsion direction caused by cutting force). This ensures that when the first flexible hinge executes the corresponding displacement command, the first hinge arms 11 can more accurately undergo the corresponding stroke deformation while maintaining the corresponding stiffness. In this embodiment, the flexible hinge can be made of aluminum.

[0032] In fast-actuator servo mechanisms, piezoelectric ceramics are primarily used to achieve high-precision position control and rapid response. Based on the piezoelectric effect, piezoelectric ceramics generate a corresponding degree of displacement in the desired direction by receiving a corresponding voltage drive signal.

[0033] like Figures 2 to 4 As shown, the secondary displacement component 2 includes a second piezoelectric ceramic 22 and a second flexible hinge.

[0034] The second flexible hinge includes a second hinge body 20 and a plurality of second hinge arms 21 disposed on the side wall of the second hinge body 20. A cutting head 3 is fixedly disposed on the second hinge body 20.

[0035] The second hinge arm 21 is fixedly connected to the first hinge body 10. The first hinge body 10 has a second drive chamber inside.

[0036] The second piezoelectric ceramic 22 is disposed in the second driving chamber. The two opposite ends of the second piezoelectric ceramic 22 abut against the inner wall of the first hinge body 10 and the bottom of the second hinge body 20, respectively. The second piezoelectric ceramic 22 is used to control the two opposite ends to undergo corresponding deformation in the target displacement direction according to the input voltage control signal.

[0037] Correspondingly, the structure of the secondary displacement component 2 is basically the same as that of the primary displacement component 1. The secondary displacement component 2 is installed on the movable part (first hinge body 10) of the primary displacement component 1, and is used to continue displacement based on the movement of the primary displacement component 1. In this embodiment, the motion structures between the two displacement components are independent and decoupled from each other, so that they can be controlled separately by two controllers. The control strategies do not affect each other, making it simpler.

[0038] Specifically, the displacement base 13, the first piezoelectric ceramic 12, the second piezoelectric ceramic 22, and the first hinge body 10 are all hollow structures.

[0039] like Figures 2 to 4 As shown, the fast-blade servo device also includes: a displacement sensor bracket 4, a first displacement sensor, and a second displacement sensor.

[0040] The displacement sensor bracket 4 is inserted into the clamping channel formed by the displacement base 13, the first piezoelectric ceramic 12, the second piezoelectric ceramic 22, and the internal cavity of the first hinge body 10. The displacement sensor bracket 4 has a hollow structure.

[0041] The first displacement sensor is fixedly installed inside the displacement sensor bracket 4 to obtain displacement information L1 between the second hinge body 20 and the displacement base 13, that is, the total displacement of the two-stage displacement components.

[0042] The second displacement sensor is installed in the sensor mounting groove 14 on the displacement base 13 to obtain the displacement information L2 between the first hinge body 10 and the displacement base 13, that is, the displacement of the first-stage displacement component 1.

[0043] In the dual-stroke fast-tool servo device of this embodiment, since the space between the first hinge body 10 and the second hinge body 20 is small, it is not convenient to install corresponding displacement sensors to measure the relative displacement between them. Therefore, in this embodiment, corresponding displacement sensors are installed on the inner and outer sides of the displacement base 13, where displacement sensors can be easily installed, to obtain L1 and L2. The relative displacement between the first hinge body 10 and the second hinge body 20, that is, the displacement L3 of the secondary displacement component 2, can be obtained by L1-L2. Thus, while obtaining L2 and L3, the compactness of the dual-stroke fast-tool servo device structure is also ensured.

[0044] like Figure 1 As shown, the control system in this embodiment includes:

[0045] Two displacement controllers are used to generate displacement drive signals for the primary displacement component 1 and the secondary displacement component 2, respectively. Specifically, in this embodiment, the drive components for both the primary displacement component 1 and the secondary displacement component 2 are piezoelectric ceramics, and the displacement drive signals are voltage signals.

[0046] The input signal of the displacement controller corresponding to the first-level displacement component 1 is the tracking error signal between the desired displacement signal input by the fast-blade control system and the actual displacement signal output by the first-level displacement component 1.

[0047] The input signal of the displacement controller corresponding to the secondary displacement component 2 is: the tracking error signal of the primary displacement component 1 and the tracking error signal between the actual displacement signal output by the secondary displacement component 2 when the tracking error signal is the input signal.

[0048] Specifically, this system also includes: a third signal addition / subtraction module 57.

[0049] The third signal addition / subtraction module 57 is used to generate a corresponding tracking error signal based on the desired displacement signal input to the corresponding displacement component and the actual displacement signal output. In this embodiment, different error signals input to the displacement controller can be generated by setting the corresponding third signal addition / subtraction module 57.

[0050] In this embodiment, the primary displacement component 1 is used to achieve the main tracking of the desired displacement. Therefore, when its corresponding displacement controller performs control, the error signal it targets is the tracking error signal between the desired displacement signal input by the fast-sweep control system and the actual displacement signal output by the primary displacement component 1. Thus, by minimizing the error, the displacement output by the primary displacement component 1 can basically reach the desired displacement amount. However, in actual use, the displacement output by the primary displacement component 1 often does not completely match the desired displacement, meaning there will still be some error. Therefore, the secondary displacement component 2 in this embodiment is used to further optimize and compensate for the error generated by the primary displacement component 1, further reducing the error value between the final generated total displacement and the desired displacement. Therefore, the error value generated by the primary displacement component 1 is directly introduced into the displacement controller corresponding to the secondary displacement component 2, so that the displacement controller uses the error feedback from this error value to make the secondary displacement component 2 as close as possible to the displacement amount represented by the error value generated by the primary displacement component 1.

[0051] The displacement controller includes a PI control module 50, an error compensation module, and a first signal addition / subtraction module 55. The PI control module 50 and the error compensation module are connected in parallel, and the first signal addition / subtraction module 55 is communicatively connected to the output terminals of both the PI control module 50 and the error compensation module.

[0052] The PI control module 50 is used to generate a corresponding primary adjustment control signal based on the corresponding tracking error signal using a PI control strategy.

[0053] Specifically, taking the displacement error obtained at the current time t as an example, the primary adjustment control signal E(t) generated by the PI control strategy satisfies the following condition:

[0054] ;

[0055] Among them, K p It is the proportional gain, which determines the strength of the proportional term's response to error. K i The integral gain determines the rate at which the integral term accumulates error.

[0056] The error compensation module includes: inverse function module 51 and time delay module 52.

[0057] The inverse function module 51 is used to restore the tracking error signal to the error displacement drive signal input to the corresponding displacement component. The displacement component is either a first-level displacement component 1 or a second-level displacement component 2. The tracking error signal and the error displacement drive signal have different signal types. Specifically, the primary adjustment control signal, the error displacement drive signal, and the historical displacement drive signal are all voltage signals.

[0058] The delay module 52 is used to acquire the historical displacement drive signal input to the corresponding displacement component when generating the tracking error signal.

[0059] Since both the system's input and output are displacement signals, the resulting tracking error is also a displacement signal. The displacement controller ultimately outputs a drive signal, i.e., a voltage signal, to move the piezoelectric ceramic. Therefore, an inverse function module 51 is needed to convert the error signal into a corresponding voltage signal.

[0060] In this embodiment, existing technology can be used to establish transfer function models P corresponding to the first-stage displacement component 1 and the second-stage displacement component 2, respectively, to simulate the relationship between the inputs and outputs of the first-stage displacement component 1 and the second-stage displacement component 2. Then, the corresponding inverse function model P is obtained based on the transfer function model P. -1 That is, the inverse function module 51.

[0061] Theoretically P×P -1 =1, but in actual construction, the theoretically perfect state cannot be achieved. Usually, P and P -1 There is a delay term Z. -dTherefore, the error value of the voltage form after conversion by the inverse function module 51 also has a certain time delay. That is, the voltage error may be the error value generated by the previous one or several control signals. Therefore, in order to obtain the historical displacement drive signal corresponding to the time when the error value of the voltage form is greater than that, it is necessary to set the time delay module 52 to obtain the corresponding drive signal from the historical control data to ensure the consistency between the error and the drive signal and avoid the misalignment of the error and the drive signal, which would lead to the adjustment misalignment problem.

[0062] Specifically, taking the displacement error obtained at the current time t as an example, the error displacement driving signal V generated by the inverse function module 51 is explained. e(t) It simply converts the displacement signal into a voltage signal. The time delay module 52 acquires the signal related to V. e(t) The corresponding historical displacement driving signal u(t).

[0063] The first signal addition / subtraction module 55 is used to superimpose the primary adjustment control signal, the error displacement drive signal, and the historical displacement drive signal input by the corresponding displacement component when generating the tracking error signal to generate a new displacement drive signal input by the corresponding displacement component.

[0064] That is, the new displacement driving signal W=u(t)+V e(t) +E(t).

[0065] Furthermore, the displacement controller also includes a limiting module 56.

[0066] The amplitude limiting module 56 is communicatively connected to the first signal addition / subtraction module 55 and is used to limit the amplitude of the new displacement driving signal within a preset amplitude range.

[0067] The limiting module 56 can be a bandpass filter. By setting the corresponding cutoff frequency, it can ensure that the final output displacement drive signal conforms to the amplitude setting of the corresponding input signal of the piezoelectric ceramic.

[0068] During the process of the displacement controller converging the error to near zero (typically within tens of milliseconds), it actually works by adjusting the V in the error compensation module. e(t) The error is jointly adjusted by the E(t) generated by the PI control strategy. Specifically, as the error value e(t) gradually decreases to zero, the control signal (K) output by the PI control module 50... p e(t) approaches zero. The value gradually approaches a constant value. Correspondingly, the control signal output by the error compensation module (i.e., u(t) + V) gradually approaches a constant value. e(t) Then it gradually approaches the desired signal.

[0069] like Figure 5As shown, as the error gradually decreases, the error compensation module gradually learns and approximates the desired control signal based on the currently generated displacement error and historical displacement drive signals. Its adjustment effect on the signal gradually increases from weak to strong. Because it does not introduce delay, it ensures higher tracking capability for high-frequency signals in the later stages. Correspondingly, since the PI control module 50 generates an adjustment signal based on the error, its adjustment effect on the signal gradually decreases from strong to weak during this process. This ensures good tracking accuracy based on the error signal in the initial stage, while playing virtually no adjustment role in the later stages, avoiding delay introduced by the integral term. Therefore, the error compensation module and the PI module in this system controller compensate and cooperate with each other, preventing a significant decrease in the system's tracking performance as processing time continues, thus ensuring the processing accuracy of high-frequency periodic signals.

[0070] In one possible embodiment of this utility model, the error compensation module further includes:

[0071] The second signal addition / subtraction module 53 and the low-pass filter 54.

[0072] The second signal addition / subtraction module 53 is used to superimpose the error displacement drive signal and the historical displacement drive signal to generate a hybrid adjustment control signal.

[0073] The low-pass filter 54 is used to remove signals with frequencies greater than the preset cutoff frequency from the mixed adjustment control signal and generate the primary and secondary adjustment control signals.

[0074] Since the primary displacement component 1 and the secondary displacement component 2 are inevitably affected by environmental noise during actual motion execution, such as resonance of other components, the actual displacement signal of the displacement component obtained in this embodiment inevitably contains some environmental noise information. Therefore, the final generated e(t) and Ve(t) will contain this environmental noise. Since this noise is usually high-frequency noise, it can be removed by setting a low-pass filter 54 in the error compensation module to improve the accuracy of the signal.

[0075] Correspondingly, in this embodiment, the function of the first signal addition / subtraction module 55 is replaced by: superimposing the primary adjustment control signal and the secondary adjustment control signal to generate a new displacement drive signal input to the corresponding displacement component.

[0076] In another possible embodiment of this utility model, the control system further includes: a trajectory analysis module, which is used to perform the following steps:

[0077] S100: Performs a Fast Fourier Transform on the tool path to be machined, generating a spectrum diagram corresponding to the tool path. The spectrum diagram includes all frequency components contained in the tool path.

[0078] S200: If there is only one frequency component in the spectrum with an amplitude greater than the preset amplitude threshold and a signal frequency greater than the preset frequency threshold, then the displacement signal corresponding to the tool trajectory to be processed will be used as the desired displacement signal input to the fast tool control system.

[0079] The preset amplitude threshold and preset frequency threshold in this embodiment can be set according to the actual usage scenario.

[0080] S300: If there are at least two frequency components in the spectrum with amplitudes greater than the preset amplitude threshold, an alarm signal is generated.

[0081] For a true single-frequency periodic signal, the peak in the spectrum should be very prominent and concentrated, with almost no other significant energy distribution around it. Therefore, a preset amplitude threshold can be used to filter and determine whether the tool path to be processed is a single-frequency periodic signal. Simultaneously, the signal frequency can be determined using a preset frequency threshold. Thus, the trajectory analysis module can determine in advance whether the current tool path to be processed is a high-frequency single-frequency periodic signal more suitable for the machining process of this system.

[0082] Furthermore, the above figures are merely illustrative of the processes included in the control system according to exemplary embodiments of the present invention, and are not intended to be limiting. It is readily understood that the processes shown in the above figures do not indicate or limit the temporal order of these processes. Additionally, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.

[0083] It should be noted that although several modules or units for the device used to perform actions have been mentioned in the detailed description above, this division is not mandatory. In fact, according to embodiments of this disclosure, the features and functions of two or more modules or units described above can be embodied in one module or unit. Conversely, the features and functions of one module or unit described above can be further divided and embodied by multiple modules or units.

[0084] The above are merely specific embodiments of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. A dual-stroke quick tool servo apparatus, characterized by comprising: include: In the target displacement direction, a primary displacement component and a secondary displacement component are connected in series. The primary displacement component and the secondary displacement component are used to superimpose to form the total target displacement. The secondary displacement component is used to compensate for the displacement error generated by the primary displacement component. The primary displacement assembly includes a displacement base, a first piezoelectric ceramic, and a first flexible hinge. The first flexible hinge includes a first hinge body and a plurality of first hinge arms disposed on the side wall of the first hinge body; The outer end of the first hinge arm is fixedly connected to the displacement base; the displacement base is provided with a first driving chamber. The first piezoelectric ceramic is disposed in the first driving chamber, and the two opposite ends of the first piezoelectric ceramic abut against the inner wall of the displacement base and the bottom of the first hinge body, respectively. The first piezoelectric ceramic is used to control the two opposite ends to deform in the target displacement direction according to the input voltage control signal. The secondary displacement component includes a second piezoelectric ceramic and a second flexible hinge; The second flexible hinge includes a second hinge body and a plurality of second hinge arms disposed on the side wall of the second hinge body; The second hinge arm is fixedly connected to the first hinge body; the first hinge body has a second drive chamber inside; The second piezoelectric ceramic is disposed in the second driving chamber. The two opposite ends of the second piezoelectric ceramic abut against the inner wall of the first hinge body and the bottom of the second hinge body, respectively. The second piezoelectric ceramic is used to control the two opposite ends to undergo corresponding deformation in the target displacement direction according to the input voltage control signal.

2. A dual-stroke quick tool servo device according to claim 1, wherein The displacement base, the first piezoelectric ceramic, the second piezoelectric ceramic, and the main body of the first hinge are all hollow structures.

3. A dual-stroke quick tool servo device according to claim 2, wherein The fast-blade servo device also includes: a displacement sensor bracket, a first displacement sensor, and a second displacement sensor; The displacement sensor bracket is inserted into a clamping channel formed by the displacement base, the first piezoelectric ceramic, the second piezoelectric ceramic, and the internal cavity of the first hinge body; the displacement sensor bracket has a hollow structure. The first displacement sensor is fixedly installed in the displacement sensor bracket and is used to obtain displacement information between the second hinge body and the displacement base; The second displacement sensor is mounted on the displacement base to obtain displacement information between the first hinge body and the displacement base.

4. A dual-stroke quick tool servo device according to claim 3, wherein The driving signals for both the first and second piezoelectric ceramics are voltage signals.

5. A dual-stroke fast-tool servo device according to claim 1, characterized in that, The first hinge arm and the second hinge arm are provided with weight-reducing through holes.

6. The dual-stroke fast-tool servo device according to claim 1, characterized in that, The first flexible hinge and the second flexible hinge are made of aluminum.

7. A dual-stroke fast-tool servo device according to claim 1, characterized in that, The displacement of the first flexible hinge is greater than the displacement of the second flexible hinge.

8. A dual-stroke fast-tool servo device according to claim 1, characterized in that, A cutting head is fixedly mounted on the second hinge body.

9. A dual-stroke fast-tool servo device according to claim 1, characterized in that, It also includes the knife holder; The tool holder is used to connect the displacement base to the machine tool.

10. A dual-stroke fast-tool servo device according to claim 1, characterized in that, The first hinge body and the first hinge support arm are integrally formed; the second hinge body and the second hinge support arm are integrally formed.

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