CN111531394A - Large-stroke fast cutter servo device - Google Patents

Abstract

The invention discloses a large-stroke fast knife servo device which comprises a mounting frame, a knife rest, a flexible guide assembly, a knife and two pieces of piezoelectric ceramics, wherein the knife rest is mounted on the mounting frame through the flexible guide assembly, so that the knife rest can reciprocate along a straight line, the knife is arranged on the knife rest, and the two pieces of piezoelectric ceramics are oppositely arranged on the mounting frame and used for pushing the knife rest to reciprocate. The large-stroke fast knife servo device is simple in structure, convenient to operate and capable of meeting requirements of large stroke and high frequency response.

Description

A large stroke fast knife servo device

technical field

The invention relates to the technical field of ultra-precision machining equipment, in particular to a large-stroke fast-tool servo device.

Background technique

With the rapid development of optics and optoelectronic technologies, rotationally symmetric optical components have long been unable to meet the needs of optical systems with more and more complex structures and more and more functions, and some optical components with special microstructured surfaces can achieve Special imaging functions such as integration, array, wavefront, etc., have been more and more widely used in the field of national defense and military industry, as well as in civil fields such as aerospace, optical fiber communication, and biomedicine, and have gradually become indispensable in optical systems. or missing important core components. Traditional mechanical manufacturing methods are difficult to perform the above-mentioned manufacturing tasks of microarray elements, and current processing technologies are mainly divided into two categories: micro-nano manufacturing methods and diamond cutting. Micro-nano manufacturing methods include photolithography, laser direct writing technology, etching method and holography method, etc. These methods still have certain defects in terms of processing range, processing accuracy and processing efficiency. High precision production. At present, the Fast Tool Servo (FTS, Fast Tool Servo) technology based on single-point diamond cutting has gradually become the mainstream method for realizing high-precision and high-efficiency machining of micro-nano-structured devices at home and abroad.

可知，柔性导向刚度的提高会造成压电陶瓷的位移损失，降低系统的最大输出位移，并且柔性导向的刚度越大，系统的最大输出位移就越小。The existing fast tool servo devices are basically based on the driving principle of a single piezoelectric ceramic to push the tool movement. The tool holder with flexible guide is used to transmit the power output of the piezoelectric ceramic. The flexible guide tool holder must be at a high level of the piezoelectric ceramic. While the frequency motion is accurately transmitted to the tool, it is also necessary to provide the force (return force) for the tool to follow the return of the piezoelectric ceramic. According to the research, increasing the rigidity of the flexible guide is beneficial to improve the tracking performance of the tool holder for complex surface shapes, and at the same time, it is also beneficial to improve the natural frequency of the entire fast tool system. However, the maximum output displacement of the piezoelectric ceramic is also affected by the stiffness of the flexible guide. Let ΔL ₀ be the maximum output displacement of the piezoelectric ceramic when it is not loaded, ΔL is the actual maximum output displacement of the piezoelectric ceramic, and k _p is the piezoelectric ceramic stiffness, k is the stiffness of the flexible guide, then the actual maximum output displacement and the maximum output displacement of the piezoelectric ceramic itself satisfy the relationship

It can be seen that the increase of the stiffness of the flexible guide will cause the displacement loss of the piezoelectric ceramics and reduce the maximum output displacement of the system, and the greater the stiffness of the flexible guide, the smaller the maximum output displacement of the system.

To sum up, the stiffness selection of the flexible guide has a great influence on the performance of the fast tool servo system. The greater the stiffness, the better the dynamic performance; the smaller the stiffness, the greater the maximum output displacement of the system. This results in the contradiction between the maximum output displacement and the system frequency response. It is difficult to overcome the inherent defects of the single piezoelectric ceramic fast knife servo system only by optimizing the structure and stiffness of the flexible guide. Therefore, how to overcome this inherent defect and at the same time take into account the requirements of the large stroke and high frequency response of the FTS processing technology is an urgent problem to be solved by those skilled in the art.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art, and to provide a large-stroke fast tool servo device with simple structure, convenient operation, and can meet the requirements of large-stroke and high-frequency response at the same time.

In order to solve the above-mentioned technical problems, the present invention adopts the following technical solutions:

A large-stroke fast knife servo device includes a mounting frame, a tool rest, a flexible guide assembly, a tool and two pieces of piezoelectric ceramics. The tool is arranged on the tool holder, and two pieces of the piezoelectric ceramics are arranged oppositely on the mounting frame to push the tool holder to move back and forth.

As a further improvement of the above technical solution:

The control signal of one piece of the piezoelectric ceramics is set to VA, the VA _{= 0.5asin} (2πt)+a, and the control signal of the other piece of the piezoelectric ceramics is set to _VB , and the _VB =0.5 asin(2πt-π)+a, where a is the voltage value corresponding to the maximum displacement of the pressure ceramic output, and t is the working time of the pressure ceramic.

The tool holder is a frame structure, two pieces of the piezoelectric ceramics are arranged in the tool holder, the telescopic end of one piece of the piezoelectric ceramic is abutted against one end of the tool holder, and the other The telescopic end abuts against the other end of the tool holder.

Each of the tool holders is provided with abutting screws at the contact points with each piezoelectric ceramic, and each of the abutting screws is abutted on the corresponding piezoelectric ceramic.

The pressing screw is provided with a pressing ball, the piezoelectric ceramic is provided with a circular hole at a position opposite to the pressing ball, and the pressing screw is pressed into the circular hole by the pressing ball.

The flexible guide assembly includes an even number of flexible parts, each of which is symmetrically distributed on both sides of the tool holder, the flexible parts include a mounting plate and flexible plates arranged on both sides of the mounting plate, the mounting plates are installed on the On the installation frame, the flexible board is connected between the installation plate and the tool holder.

The flexible board and the tool holder are integrally formed.

The mounting frame is provided with a capacitive sensor for measuring the displacement of the tool.

The tool is arranged at one end of the tool holder, and the capacitive sensor is arranged at the other end of the tool holder.

The mounting frame includes a base plate and a fixing base, the fixing base is detachably fixed on the base plate, and two pieces of the piezoelectric ceramics are relatively fixed on two sides of the fixing base.

Compared with the prior art, the advantages of the present invention are:

由于当压电陶瓷空载时的最大输出位移ΔL₀不变即两种装置采用同一款压电陶瓷时，本装置的柔性导向组件刚度k_p可选择更小，则压电陶瓷的实际输出位移ΔL可以得到明显的提升，从而有效提升快刀伺服装置的工作行程；1. This large stroke fast tool servo device uses the thrust of another piece of piezoelectric ceramics to replace the flexible guide components (such as flexible hinges) in the traditional fast tool servo device (only one piece of piezoelectric ceramics) to provide the restoring force of the tool return stroke, that is, to reduce The influence of the stiffness of the flexible guide assembly on the dynamic performance of the device is considered, which makes it possible to choose a smaller stiffness value when designing the flexible guide assembly. In this way, compared with the traditional single piezoelectric ceramic fast knife servo device, according to the relationship

Since the maximum output displacement ΔL ₀ of the piezoelectric ceramic remains unchanged when the piezoelectric ceramic is no-loaded, that is, when the two devices use the same piezoelectric ceramic, the rigidity k _p of the flexible guiding component of the device can be selected to be smaller, then the actual output displacement of the piezoelectric ceramic ΔL can be significantly improved, thereby effectively improving the working stroke of the fast tool servo device;

2. In the traditional single piezoelectric ceramic fast tool servo device, when the tool is fed, the tool holder that drives the tool movement is subjected to the combined force of the piezoelectric ceramic thrust in the opposite direction and the resistance caused by the elastic force of the flexible hinge. When the tool holder is only subjected to the restoring force provided by the elastic force of the flexible hinge, this will cause the displacement transfer function of the system to be inconsistent when the tool is advanced and retracted, which brings greater difficulty to the control. In the present invention, the fast tool servo In the device, whether it is feeding or retracting the tool, the tool holder that drives the tool movement is subjected to the combined force of the piezoelectric ceramic thrust in the opposite direction and the resistance caused by the elastic force of the flexible guide component. It brings a lot of convenience and is conducive to improving the control accuracy;

3. Both the flexible guide assembly and the tool holder are symmetrical structures with piezoelectric ceramics as the axis of symmetry. In this way, the flexible guide assembly can eliminate the influence factors other than the axial direction (tool feed direction) when transmitting thrust, and only retains the impact on the tool. The change of the axial direction improves the accuracy of the tool in motion.

Description of drawings

FIG. 1 is a schematic structural diagram of a large-stroke fast-tool servo device from a first perspective of the present invention.

FIG. 2 is a schematic structural diagram of the second viewing angle of the large-stroke fast-tool servo device of the present invention.

FIG. 3 is an enlarged view of A in FIG. 2 .

FIG. 4 is a combination diagram of the flexible guide assembly and the tool holder of the large-stroke fast-tool servo device of the present invention.

5 is a schematic structural diagram of the piezoelectric ceramic of the large-stroke fast-tool servo device of the present invention.

FIG. 6 is a schematic structural diagram of the bottom plate of the large-stroke fast-tool servo device of the present invention.

FIG. 7 is a schematic structural diagram of the fixed seat of the large-stroke fast-tool servo device of the present invention.

FIG. 8 is a schematic diagram of the structure of the large-stroke fast-tool servo device of the present invention in the middle position.

FIG. 9 is a schematic diagram of the structure of the large-stroke fast-tool servo device of the present invention in the state of tool feed.

Fig. 10 is a schematic diagram of the structure of the large-stroke fast-tool servo device of the present invention in a state of retracting the tool.

The symbols in the figure represent:

1. Mounting frame; 11. Bottom plate; 12. Fixed seat; 2. Tool holder; 3. Flexible guide assembly; 31. Flexible parts; 311. Mounting plate; 312, Flexible board; 4. Tool; 5. Piezoelectric ceramics; 51. Round hole; 6. Tighten the screw; 61. Tighten the ball; 7. Capacitive sensor.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

由于当压电陶瓷5空载时的最大输出位移ΔL₀不变即两种装置采用同一款压电陶瓷5时，本装置的柔性导向组件3刚度k可选择更小，则压电陶瓷5的实际输出位移ΔL可以得到明显的提升，从而有效提升快刀伺服装置的工作行程；在传统的单压电陶瓷快刀伺服装置中，在进刀时，带动刀具4运动的刀架2受到的是方向相反的压电陶瓷5推力和柔性铰链弹性力造成的阻力的合力，而在退刀时，刀架2仅受到柔性铰链弹性力提供的回复力，这就会造成进刀和退刀时系统的位移传递函数不一致，给控制上带来了较大的难度，而在本发明的快刀伺服装置中，无论是进刀还是退刀，带动刀具4运动的刀架2受到的均是方向相反的压电陶瓷5推力和柔性导向组件3弹性力造成的阻力的合力，系统的位移传递函数一致，给控制设计上带了很大的便利，有利于提高控制精度。该大行程快刀伺服装置结构简单、操作便捷以及能够同时满足大行程和高频响需求。FIGS. 1 to 7 show an embodiment of the large-travel fast-tool servo device of the present invention. The large-travel fast-tool servo device includes a mounting frame 1 , a tool holder 2 , a flexible guide assembly 3 , a tool 4 and two piezoelectric ceramics 5 . , the tool holder 2 is installed on the mounting frame 1 through the flexible guide assembly 3, so that the tool holder 2 can move back and forth in a straight line, the tool 4 is arranged on the tool holder 2, and the two pieces of piezoelectric ceramics 5 are arranged on the mounting frame 1 opposite to each other. To push the tool holder 2 to move back and forth. When in use, the mounting frame 1 is fixed on the Z-axis slide of the machine tool, and moves together with the Z-axis slide of the machine tool. This large stroke fast tool servo device uses the thrust of another piezoelectric ceramic 5 to replace the flexible guide component 3 (such as a flexible hinge) in the traditional fast tool servo device (only one piezoelectric ceramic 5) to provide the return force of the tool 4 for the return stroke, That is, the influence of the stiffness of the flexible guide assembly 3 on the dynamic performance of the device is reduced, which makes it possible to select a smaller stiffness value when designing the flexible guide assembly 3. In this way, compared with the traditional single piezoelectric ceramic fast knife servo device, according to the required relationship

Since the maximum output displacement ΔL ₀ of the piezoelectric ceramic 5 remains unchanged when the piezoelectric ceramic 5 is unloaded, that is, when the two devices use the same piezoelectric ceramic 5, the rigidity k of the flexible guide component 3 of the device can be selected to be smaller, then the piezoelectric ceramic 5 The actual output displacement ΔL can be significantly improved, thereby effectively improving the working stroke of the fast tool servo device; in the traditional single piezoelectric ceramic fast tool servo device, when the tool is fed, the tool holder 2 that drives the tool 4 to move is subjected to the opposite direction. The combined force of the push force of the piezoelectric ceramic 5 and the resistance caused by the elastic force of the flexible hinge, and when the tool is retracted, the tool holder 2 is only subjected to the restoring force provided by the elastic force of the flexible hinge, which will cause the system to move in and out of the tool. The transfer function is inconsistent, which brings great difficulty to the control. In the fast tool servo device of the present invention, whether it is advancing or retracting the tool, the tool holder 2 that drives the tool 4 to move is subjected to piezoelectricity in the opposite direction. The resultant force of the resistance caused by the thrust force of the ceramic 5 and the elastic force of the flexible guide assembly 3, the displacement transfer function of the system is the same, which brings great convenience to the control design and is conducive to improving the control accuracy. The large-travel quick-knife servo device is simple in structure, convenient in operation, and can meet the requirements of large-travel and high-frequency response at the same time.

In this embodiment, the control signal of one piece of piezoelectric ceramics 5 is set to V _A , V _A =0.5asin(2πt)+a, and the control signal of the other piece of piezoelectric ceramics 5 is set to V _B , V _B =0.5asin (2πt-π)+a, where a is the corresponding voltage value when the pressure ceramic 5 outputs the maximum displacement, and t is the working time of the pressure ceramic 5 . In this way, when one piezoelectric ceramic 5 extends the feeding process of the driving device, the other piezoelectric ceramic 5 is shortened by the same distance to complete the actions of feeding and retracting. The amplitudes of the control signals of the two piezoelectric ceramics 5 are the same, and the variation laws are just opposite.

In this embodiment, as shown in FIG. 4 , the tool holder 2 has a frame structure, two pieces of piezoelectric ceramics 5 are coaxially arranged in the tool holder 2 , and the telescopic end of one piece of piezoelectric ceramics 5 abuts against the edge of the tool holder 2 . At one end, the telescopic end of the other piezoelectric ceramic 5 is in contact with the other end of the tool holder 2 . The tool 4 is mounted on the tool holder 2 through the tool holder, and the two pieces of piezoelectric ceramics 5 are used to enable the tool holder 2 to drive the tool 4 to reciprocate in the feeding direction of the tool 4 .

In this embodiment, as shown in FIG. 1 to FIG. 3 , the tool holder 2 is provided with abutting screws 6 at the abutting positions with each piezoelectric ceramic 5 , and each pressing screw 6 abuts against the corresponding piezoelectric ceramic 5 . superior. By screwing the abutting screw 6, the pre-tightening force on the piezoelectric ceramic 5 can be adjusted, and even if the pre-tightening force of the piezoelectric ceramic 5 is adjusted, the disassembly and assembly of the tool holder 2 is also facilitated.

In this embodiment, as shown in FIG. 1 , FIG. 2 , FIG. 3 and FIG. 5 , a pressing ball 61 is provided on the pressing screw 6 , and a circular hole 51 is provided on the piezoelectric ceramic 5 at the position opposite to the pressing ball 61 . The abutting screw 6 abuts in the round hole 51 through the abutting ball 61 . Specifically, two side end faces of the tool holder 2 are provided with threaded holes, each abutting screw 6 passes through its respective threaded hole and is threadedly connected to the threaded hole, and the tail of the abutting screw 6 pushes the abutting ball 61 against the piezoelectric On the circular hole 51 at the end of the ceramic 5 , the pre-tightening force of the piezoelectric ceramic 5 is adjusted by adjusting the abutting screw 6 .

In this embodiment, as shown in FIG. 1 , FIG. 2 and FIG. 4 , the flexible guide assembly 3 includes an even number of flexible members 31 , each flexible member 31 is symmetrically distributed on both sides of the tool holder 2 , and the flexible member 31 includes a mounting plate 311 and the flexible boards 312 disposed on both sides of the mounting plate 311 , the mounting plate 311 is mounted on the mounting frame 1 , and the flexible boards 312 are connected between the mounting plate 311 and the tool rest 2 . Specifically, there are four flexible members 31 , and the four flexible members 31 are symmetrically distributed with the piezoelectric ceramic 5 as the axis. One end of the flexible plate 312 is integrally formed with the tool holder 2 , and the other end is hinged on the mounting plate 311 . The flexible plate 312 can be composed of a single leaf spring, and its function is to make the movement resistance of the tool holder 2 along the feeding direction of the tool 4 small enough and the displacement in other directions to be small enough, so as to ensure the high-precision straight line of the tool 4 Movement and high precision machining volumes. Both the flexible guide assembly 3 and the tool holder 2 are symmetrical structures with piezoelectric ceramics 5 as the axis of symmetry. In this way, the flexible guide assembly 3 can eliminate influence factors other than the axial direction (the feed direction of the tool 4) when transmitting thrust, and only Changes to the axial direction of the tool 4 are retained, which improves the accuracy of the tool 4 in motion.

In this embodiment, as shown in FIG. 1 to FIG. 3 , the mounting frame 1 is provided with a capacitive sensor 7 for measuring the displacement of the tool 4 . Specifically, the tool 4 is arranged at one end of the tool holder 2 , and the capacitive sensor 7 is arranged at the other end of the tool holder 2 . A mounting table is fixed on the mounting frame 1 by bolts. The mounting table is provided with a V-shaped groove. The capacitive sensor 7 is fixed in the V-shaped groove of the mounting table. Power supply and signal processing module connections.

In this embodiment, as shown in FIG. 1 , FIG. 2 , FIG. 6 and FIG. 7 , the mounting frame 1 includes a base plate 11 and a fixing base 12 , the fixing base 12 is detachably fixed on the base plate 11 by bolts, and two pieces of piezoelectric ceramics 5 is relatively fixed on both sides of the fixed seat 12 . The two ends of the piezoelectric ceramic 5 are respectively limited by the fixing seat 12 and the abutting screw 6 , and the pre-tightening force of the piezoelectric ceramic 5 is adjusted by adjusting the pressing screw 6 . The tail of the piezoelectric ceramic 5 (the end of the piezoelectric ceramic 5 abutting the tool holder 2 is the head) is provided with a central threaded hole. The tail of the piezoelectric ceramic 5 is fixed on the fixing base 12 .

The working principle of the long-travel fast-tool servo device is shown in Figures 8 to 10. Figure 8 is a schematic diagram of the structure of the large-travel fast-tool servo device of the present invention in the middle position; Figure 9 is the large-travel fast-tool servo device of the present invention in the feed state Schematic diagram of the structure; FIG. 10 is a schematic diagram of the structure of the large-stroke fast-tool servo device of the present invention in the retracted state. Among them, X is the feed direction. The principle is as follows:

1. The two pieces of piezoelectric ceramics 5 are simultaneously stretched from the initial length by a certain length to reach the middle position (as shown in Figure 8), and then the same preloading force is applied to the piezoelectric ceramics 5 by pressing the screws 6 to complete the preloading of the piezoelectric ceramics 5. ;

2. The piezoelectric ceramics 5 close to the tool 4 continue to stretch for a certain length. At the same time, the piezoelectric ceramics 5 away from the tool 4 shrink by the same length. Under the push of the piezoelectric ceramics 5 close to the tool 4, the tool holder 2 drives the Tool 4 completes the feeding action and reaches the feeding state as shown in Figure 9;

3. On the contrary, the piezoelectric ceramic 5 away from the cutter 4 is stretched for a certain length, and at the same time, the piezoelectric ceramic 5 close to the cutter 4 shrinks by the same length. Drive the tool 4 to complete the feeding action, and reach the retracting state as shown in Figure 10;

4. By repeatedly executing steps 2 and 3, the rapid servo motion of the tool 4 is realized to complete the cutting motion of the workpiece.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art, without departing from the scope of the technical solution of the present invention, can make many possible changes and modifications to the technical solution of the present invention by using the technical content disclosed above, or modify it into an equivalent implementation of equivalent changes. example. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solutions of the present invention should fall within the protection scope of the technical solutions of the present invention.

Claims (10)

1. A large-stroke fast knife servo device is characterized in that: comprising a mounting frame (1), a knife rest (2), a flexible guide assembly (3), a knife (4) and two piezoelectric ceramics (5), the The tool holder (2) is mounted on the mounting frame (1) through the flexible guide assembly (3), so that the tool holder (2) can reciprocate along a straight line, the tool (4) is arranged on the tool holder (2), and two pieces The piezoelectric ceramics (5) are relatively arranged on the mounting frame (1), and are used to push the tool holder (2) to move back and forth. 2. The large-stroke fast-tool servo device according to claim 1, characterized in that: the control signal of one piece of the piezoelectric ceramics (5) is set as V _A , the V _A =0.5asin(2πt)+a, The control signal of the other piece of the piezoelectric ceramic (5) is set as V _B , the V _B =0.5asin(2πt-π)+a, where a is the corresponding voltage when the piezoelectric ceramic (5) outputs the maximum displacement value, t is the working time of the pressure ceramic (5). 3. The large-stroke fast tool servo device according to claim 1, characterized in that: the tool holder (2) is a frame structure, and two pieces of the piezoelectric ceramics (5) are arranged in the tool holder (2) , the telescopic end of one piece of piezoelectric ceramics (5) abuts against one end of the tool holder (2), and the telescopic end of the other piece of piezoelectric ceramics (5) abuts against the other end of the tool holder (2) . 4. The large-stroke fast-tool servo device according to claim 3, characterized in that: the tool holder (2) is provided with a pressing screw (6) at the abutment position with each piezoelectric ceramic (5), and each The abutting screws (6) abut on the corresponding piezoelectric ceramics (5). 5. The large-stroke fast tool servo device according to claim 4, characterized in that: a pressing ball (61) is provided on the pressing screw (6), and the piezoelectric ceramic (5) is opposite to the pressing ball (61). 61) is provided with a round hole (51), and the abutting screw (6) is pressed against the round hole (51) by a pressing ball (61). 6 . The large-stroke fast-knife servo device according to claim 1 , wherein the flexible guide assembly ( 3 ) comprises an even number of flexible parts ( 31 ), and each of the flexible parts ( 31 ) is symmetrically distributed on the tool rest. 7 . On both sides of (2), the flexible member (31) includes a mounting plate (311) and flexible plates (312) arranged on both sides of the mounting plate (311), and the mounting plate (311) is mounted on the mounting frame (1). ), the flexible board (312) is connected between the mounting board (311) and the tool holder (2). 7. The large-stroke fast tool servo device according to claim 6, wherein the flexible plate (312) and the tool holder (2) are integrally formed. 8 . The large-stroke fast-tool servo device according to claim 1 , wherein a capacitive sensor ( 7 ) is provided on the mounting frame ( 1 ) for measuring the displacement of the tool ( 4 ). 9 . 9 . The large-stroke fast tool servo device according to claim 8 , wherein the tool ( 4 ) is arranged at one end of the tool holder ( 2 ), and the capacitive sensor ( 7 ) is arranged at the other side of the tool holder ( 2 ). 10 . one end. 10. The large-stroke fast-tool servo device according to any one of claims 1 to 9, wherein the mounting frame (1) comprises a bottom plate (11) and a fixing seat (12), and the fixing seat (12) ) is detachably fixed on the bottom plate (11), and two pieces of the piezoelectric ceramics (5) are relatively fixed on both sides of the fixing seat (12).

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