CN101028702A - Microfeeding system for precisive grinding - Google Patents

Abstract

A microadvance system for accurate grinding machine is composed of a drive unit consisting of piezoelectric drive power supply, piezoelectric ceramics, man-machine interface type input device, and displacement-voltage table, an executing unit consisting of flexible hinge mechanism and microadvance bench, a detecting unit consisting of inductance-type position sensor or raster rule, detection signal acquiring module, displacement-voltage compensation data table, and signal processing-outputting module, and a control system consisting of microprocessor, D/A and A/D converters, data I/O display, signal amplifier, information integrating interface, and signal processing reference model and algorithm.

Description

Micro Feed System for Precision Grinding

Technical field

The invention relates to a micro-feed system for precision machine tools, in particular to a micro-feed system for precision grinding with large rigidity and high-precision piezoelectrically driven flexible hinges.

Background technique

In recent years, with the development of microelectronics, materials, biology and aerospace and other disciplines, especially the development of large-scale and ultra-large-scale integrated circuits, and the development needs of micro-electromechanical products, micro-displacement technology with sub-micron and nanometer positioning accuracy has achieved rapid development And widely used ^[1] .

Micro-displacement mechanism refers to a mechanism that uses micro-displacement technology to achieve small travel, high precision, and high sensitivity, such as travel less than millimeters, sub-micron and nano-level precision, and nano-level displacement/Newton force sensitivity.

At present, common micro-displacement mechanisms include: mechanical transmission type, torsion wheel friction transmission type, electrothermal deformation actuation type, magnetostrictive type, piezoelectric ceramic drive type, elastic deformation transmission type, flexible hinge type, linear motor type, etc.

Piezoelectric ceramics have been widely used in micro-displacement due to their advantages such as fast response, easy miniaturization, good repeatability, high resolution, good stiffness, and no magnetic field interference.

However, in the field of precision machinery manufacturing, the piezoelectric ceramic micro-displacement mechanism is only used in the application research of turning and boring with small cutting force. Its main technical features are that the stroke is about 0.05-0.5mm, the precision is 0.05μm, and the stiffness is less than 50N/μm.

However, when grinding brittle, hard and thin workpieces such as optical glass and ceramic radome, the feed rate of the grinding wheel frame can reach the sub-micron level, which can make the abrasive chips become curled when cutting plastic materials, thereby improving the grinding conditions and improving the workpiece’s grinding ability. The accuracy and surface quality of the grinding surface, such as processing optical glass into optical glass, that is, grinding into a lens with a surface roughness value of nanometer level, so that no micro-cracks will be generated when grinding the ceramic radome and the ideal shape line accuracy will be guaranteed. wait. Therefore, the micro-feed system for grinding machines is becoming a basic process device or machine tool accessory for grinding special materials such as brittle and hard, and achieving precision and ultra-precision machining accuracy and surface quality.

At present, when most precision grinding machines solve the above two problems, there are the following main problems:

1. The mechanical transmission feed accuracy of traditional grinding machines is limited. At present, the minimum feed resolution of the grinding wheel frame of the grinding machine directly driven by the servo motor and the ball screw pair is 0.5 μm, and it is very difficult to be further accurate to 0.2-0.1 μm. It's not even possible.

2. The response frequency during dynamic compensation is low, which is due to the large mass of the grinding wheel frame and its moving parts, and the crawling of the mechanical transmission mechanism. At present, the performance indicators of the grinding machine do not involve the response frequency of the feed movement.

3. The linear motor feed device has many advantages such as arbitrary working stroke, feed acceleration above 9.8m/s2, and simple system structure, but it also has high cost, serious heat generation, complex control system, and unsatisfactory magnetic isolation and antimagnetic effects, etc. The main disadvantage affects the overall performance of the feed system.

Contents of Invention

The technical problem to be solved by the present invention is to provide a micro-feed system suitable for large rigidity and high-precision piezoelectrically driven flexible hinges suitable for precision grinding machines. The precision is ±0.01～0.005μm, and the system stiffness is 200-400N/μm.

In order to achieve the above object, the present invention adopts the following technical solutions:

A micro-feeding system for precise grinding includes four parts: a driving device, an executing mechanism, a detecting device and a control system.

The driving device is composed of piezoelectric driving power supply, piezoelectric ceramics, human-machine interface input device, and displacement-voltage data structure table. The ratio of the output stiffness of the driving device to the stiffness of the micro-feeding system is 1/3 to 1/5;

The actuator is composed of a flexible hinge mechanism and a micro-feed workbench. The flexible hinge mechanism is deformed under the voltage excitation of the drive device and transmits the corresponding micro-displacement to the micro-feed workbench;

The flexible hinge mechanism integrates the flexible hinge deformation part and the piezoelectric ceramic support part, changes the output position of the flexible hinge deformation, increases the output displacement resolution of the system by 3 to 5 times, and increases the output stiffness by 3 to 5 times;

The detection device includes an inductive or capacitive position sensor or a grating ruler for detecting the actual output displacement of the micro-feeding system, a detection signal acquisition module, a voltage-displacement compensation data construction table, a signal processing and output module, and is used to identify the actual displacement through the output voltage. To realize the displacement detection of the micro-feed table;

The control system includes microprocessor, D/A and A/D converter, data input/output display, signal amplifier, information integration interface, signal processing reference model and algorithm, etc., to realize the driving device and actuator of the micro-feeding system , Data input/output, information processing and collaborative control of detection devices.

The micro-feed workbench is a workbench driven by a flexible hinge mechanism that deforms under the excitation of the driving device voltage between the traditional grinder wheel frame and the wheel frame table, that is, the secondary workbench.

The structure of the deformable part of the flexible hinge is a straight circle and a parallelogram structure composed of double levers.

The signal processing reference model of the control system is composed of the displacement-voltage data structure table and the feed-forward data model of the voltage-displacement compensation data structure table. , Confucian variable effect and executive agency crawling and other issues.

Owing to adopting above-mentioned technical scheme, the present invention has following advantage and positive effect compared with prior art:

1. Through the optimized design and configuration of the piezoelectric ceramic driver and the flexible hinge mechanism, and with the support of the corresponding precision displacement detection device, the micro-feed accuracy requirements of the precision grinding machine are realized and guaranteed, such as the minimum feed of 0.1μm With a positioning accuracy of ±0.01μm, it can meet the precision feeding requirements of ultra-precision grinding of brittle, hard and thin workpieces such as optical glass and ceramic radomes.

2. Through the optimized design of the relevant technical parameters of the piezoelectric ceramic driver and the hinge mechanism, a micro-feeding system with a relatively large stiffness is obtained, such as a micro-feeding system with a stiffness ≥ 300N/μm, which can meet the requirements of grinding processing for micro-feeding. A basic requirement for the stiffness of the system.

3. The micro-feed system has the characteristics of small size, standardized appearance, and can be flexibly configured according to needs, and can be flexibly configured as a machine tool accessory.

4. Due to the reference and utilization of the technical advantages of existing mature precision grinding machines, the success rate of research and development of precision grinding machines is improved, the cycle is shortened, and the cost is reduced.

5. By setting the minimum gap between the flexible hinge mechanism in the micro-feed system and the micro-feed table, the grinding force generated during ordinary grinding has nothing to do with the flexible hinge mechanism and the piezoelectric drive device, that is, in ordinary grinding Under the requirements of grinding feed accuracy (such as rough grinding, semi-fine grinding and fine grinding), the original machine tool function and grinding efficiency can be directly used and brought into play without affecting the accuracy of the micro-feeding system or being affected by the stiffness of the micro-feeding system etc.; when the micro-feeding system is required to achieve precision feeding, the piezoelectric drive device eliminates the minimum gap and deforms the flexible hinge to drive the micro-feeding table. With the support of the micro-feeding system, generally It can improve the grinding precision by 2 grades or above.

Description of drawings

Fig. 1 is the basic composition diagram of the micro-feeding system of the present invention;

Figure 2 is a schematic diagram of a two-stage feed mechanism for a precision grinder using a micro-feed system;

Figure 3 is a schematic diagram of the piezoelectric ceramic hysteresis effect involved in the micro-feed system;

Fig. 4 is a schematic diagram of the restriction relationship between the working capacity of piezoelectric ceramics and its main working parameters in the micro-feeding system;

Fig. 5 is a schematic diagram of the assembly relationship of the flexible hinge structure and related components;

Fig. 6 is the schematic diagram of the control system of the micro-feed system;

Fig. 7 is a control principle and basic configuration diagram of the micro-feeding system in the embodiment.

Detailed ways

The present invention will be further described below in conjunction with the embodiments and accompanying drawings.

A high-rigidity, high-precision micro-feed system for precision grinding consists of four parts: a drive device, an actuator, a detection device and a control system (see Figure 1). The main technical parameters realized are: the minimum feed rate is 0.1-0.05μm, the feed positioning accuracy is ±0.01-0.005μm, and the system stiffness is 200-400N/μm. in:

1. The driving device is a piezoelectric ceramic driving device, which is composed of a piezoelectric driving power supply, piezoelectric ceramics, a man-machine interface input device, and a displacement-voltage data structure table to provide a driving voltage for realizing micro-displacement.

2. The main technical characteristics of the piezoelectric drive device

(1) Linear thrust piezoelectric drive method. Since the total weight of the grinding wheel frame 5 of the grinding machine is generally 2000N, a linear thrust piezoelectric ceramic drive method is adopted, that is, a level of work is added between the traditional grinding wheel frame 5 and the grinding wheel frame workbench (called the primary workbench 3). Table (referred to as secondary workbench, i.e. micro-feed workbench 4) (see Figure 2). In the grinding process of the workpiece 1, generally, the primary feed can be adopted first, that is, the primary worktable 3 drives the micro-feed table 4, including the flexible hinge mechanism 8, the displacement detection device 7, etc., as well as the grinding wheel frame 5 and the grinding wheel. 2 complete the grinding feed movement (also known as macro feed movement) together to complete rough grinding, semi-fine grinding and fine grinding; The system 10 starts the piezoelectric drive device 9, and then excites the flexible hinge mechanism 8 to generate deformation, and transmits the corresponding micro-displacement to the micro-feed table 4 through the steel ball 6, and then drives the grinding wheel frame 5 and the grinding wheel 2 to complete the precision grinding process. Feed motion (also known as micro feed motion).

(2) Positive working voltage. In order to ensure and improve the working life of piezoelectric ceramics, avoid using alternating positive and negative working voltages. However, due to the hysteresis effect of piezoelectric ceramics, that is, under the same electric field, the displacement curves of piezoelectric ceramics during boosting and stepping down are inconsistent, that is, when the operating voltage is gradually increased to complete the micro-feeding requirements, the voltage is gradually restored When the micro-feeding system cannot return to the original position corresponding to the corresponding voltage, as shown in Figure 3, when the voltage is 0, the displacement is 0, but when the voltage rises and then drops to 0, the displacement cannot return to 0; when the voltage rises to 50V The corresponding voltage is 43μm, but when the voltage drops to 50V, the corresponding voltage is 55μm. To this end, the solution adopted is as follows:

1) The operating voltage of the configured driving device is 0-150V, but in actual work, the operating voltage for driving the micro-displacement starts from an initial voltage greater than 0 (such as 2-3V), even if the micro-feeding system is under the action of the initial voltage and With the support of the displacement detection device, it can be reset accurately. The initial voltage is the repair voltage at which the micro-feed table cannot be reset (returned to zero) due to the hysteresis effect of piezoelectric ceramics.

2) There is a minimum gap ΔX between the flexible hinge mechanism and the micro-feeding table, that is, when there is no working voltage (shutdown) or the working voltage is 0 (starting), the micro-feeding system and the grinding wheel frame of the grinding machine are fed in two stages The workbench is in a non-contact state. Its purpose is to: ①Use the first-stage feed table to drive the grinding wheel for rough, semi-finish, and fine grinding processes, so as to avoid any direct impact of the grinding force on the piezoelectric ceramics and flexible hinge mechanism; ②Use the micro-feed system for grinding. During fine grinding, first eliminate ΔX through the initial voltage, so that the micro-feeding workbench can be reset or in an accurate micro-feeding initial position (see Figure 2).

3) In the process of micro-feeding, the input value of the driving voltage is corrected through the piezoelectric ceramic hysteresis effect reference model, the feedback information of the displacement detection device, the voltage-displacement compensation data construction table, etc. Among them, the piezoelectric ceramic hysteresis effect reference model is established based on the theoretical model and the corresponding piezoelectric ceramic experimental data, which is used to compensate the displacement error caused by the piezoelectric ceramic hysteresis.

(3) Design of technical parameters of piezoelectric ceramics. The main technical parameters of piezoelectric ceramics are the maximum output force Fmax and the maximum output displacement Lmax. The output displacement and output force of piezoelectric ceramics are mutually restricted. When the output force reaches the maximum value (Fmax), the output displacement is the minimum value (0). Conversely, when the output displacement reaches the maximum value (Lmax), the output force is the minimum value. value (0). Therefore, the working area of piezoelectric ceramics (the shaded part in Figure 4) can be determined according to the output force range (0-Fmax) and output displacement range (0-Lmax) of piezoelectric ceramics. The actual output force and output displacement functions are as follows: (1) shown.

$\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; x</span>}\frac{\mathrm{<span\; class="notranslate">\; L</span>}\mathrm{<span\; class="notranslate">\; max</span>}}{\mathrm{<span\; class="notranslate">\; f</span>}\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}\mathrm{<span\; class="notranslate">\; max</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

In the formula, y is the actual displacement of piezoelectric ceramics (μm)

x is the actual output force of piezoelectric ceramics (N)

3. The main technical characteristics of the actuator

(1) The basic composition of the executive body. The actuator is a micro-displacement actuator, which is characterized in that it consists of a flexible hinge mechanism and a micro-feed workbench. The function of the flexible hinge mechanism is to deform under the voltage excitation of the driving device, and transmit the corresponding micro-displacement of the deformation to the micro-feed workbench.

(2) The basic features of the flexible hinge (see Figure 5). The flexible hinge is an integral structure integrating the flexible hinge deformation part and the piezoelectric ceramic support part. Through the steel ball 11, the piezoceramic driver 12 and the flexible hinge 8 are connected in point contact without gap, so as to reduce and avoid the influence of the contact bending moment on the piezoceramic. Through the steel ball 6, the flexible hinge 8 and the micro-feeding table 4 driving the grinding wheel frame are connected without gaps in point contact. The structure of the deformation part of the flexible hinge is a straight circle and a parallelogram structure formed by double levers.

(3) Flexible hinge stiffness. According to the output target of the micro-feeding system, the characteristics of key components, and the scaling principle of the mechanism, the relationship between the output displacement and the output force of the flexible hinge and the piezoelectric ceramic can be determined. The related functions are shown in formulas (2) and (3).

S=T _f y (2)

$\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

In the formula, S and P are the output displacement and output force of the flexible hinge, respectively, and T _f is the scaling coefficient of the flexible hinge and piezoelectric ceramics. If T _f <1, it indicates that the output displacement of the flexible hinge decreases and the stiffness increases; otherwise, the output The displacement is enlarged and the stiffness is reduced. In order to improve the displacement resolution of the micro-feeding system, T _f < 1 is usually used. The value of T _f is related to the performance index requirements of the micro-feeding system, the performance index design of piezoelectric ceramics, and the performance index design of flexible hinge mechanisms .

Changing the deformation output position of the flexible hinge, that is, the distance between the center coordinates of the steel ball 11 and the axis coordinates of the piezoelectric ceramic driver 12 in the Y-axis direction (see Figure 5), can make the micro-feed workbench obtain different The output displacement of , and the output stiffness of the flexible hinge under the action of the piezoelectric actuator.

From the formulas (2) and (3), the stiffness of the micro-feeding system can be calculated, or the relevant technical parameters of the flexible hinge and piezoelectric ceramics can be assigned and configured according to the stiffness of the micro-feeding system.

Substitute formula (1) into formulas (2) and (3) respectively to get formulas (4) and (5).

$\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; x</span>}\frac{\mathrm{<span\; class="notranslate">\; L</span>}\mathrm{<span\; class="notranslate">\; max</span>}}{\mathrm{<span\; class="notranslate">\; f</span>}\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; L</span>}\mathrm{<span\; class="notranslate">\; max</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

$\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

When x=0, it can be obtained from formula (4): Smax=T _f ×Lmax

When x=Fmax, obtained by formula (2): $P\max =\frac{f\max }{T_f}$

Then the stiffness K _S of the micro-feed system is shown in formula (6):

$\mathrm{<span\; class="notranslate">\; Ks</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; max</span>}}{\mathrm{<span\; class="notranslate">\; S</span>}\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="T\; f"\; filenames="A20071003643900142.png"\; state="\{\{state\}\}">T</figure-callout></span><figure-callout\; id="2"\; label="T\; f"\; filenames="A20071003643900142.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{\mathrm{<span\; class="notranslate">\; f</span>}\mathrm{<span\; class="notranslate">\; max</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

When the micro-feeding system is actually working, it is necessary to apply a pre-tightening force P _P to ensure that the movement between the micro-feeding table and the grinding machine table can be realized without gaps. The output force and output displacement functions after increasing the pretightening force are shown in formulas (7) and (8).

$\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; \&le;</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

$\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; \&le;</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$

When x=0, there are:

${\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; )</span>$

When x=F _max , then:

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}}$

The stiffness K _S of the system is:

${\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}{{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="T\; f"\; filenames="A20071003643900142.png"\; state="\{\{state\}\}">T</figure-callout></span><figure-callout\; id="2"\; label="T\; f"\; filenames="A20071003643900142.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; \&CenterDot;</span>\frac{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}}{<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; L</span>}\mathrm{<span\; class="notranslate">\; max</span>}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}<span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&Center\; Dot;</span>\frac{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 9</span>}<span\; class="notranslate">\; )</span>$

4. Main technical characteristics of the detection device

The detection device is a device used to detect the actual output displacement of the micro-feeding system, and it is characterized in that it includes a displacement signal detector, a detection signal acquisition module, a voltage-displacement compensation data construction table, a signal processing and output module, etc. The actual displacement of the micro-feed workbench is detected, data processed and compensated for voltage output. Usually, the displacement signal detector includes an inductive (capacitive) sensor or a grating ruler, etc., which can be selected and configured according to the working stroke and positioning accuracy of the micro-feeding system. For example, the working stroke of the micro-feeding system is 50 μm, and the positioning accuracy is ±0.3μm, you can choose the inductive position sensor 7 (see Figure 2).

5. Main technical characteristics of the control system

The control system is the control system of the micro-feeding system, which is characterized in that it includes a microprocessor, D/A and A/D converters, a data input/output display, a drive amplifier power supply, an information integration interface, and a signal processing reference model And algorithms, related circuits, etc. (see Figure 6), to realize the data input/output, information processing and cooperative control of the drive device, actuator, detection device, etc. of the micro-feeding system.

The signal processing reference model is composed of displacement-voltage data structure table, voltage-displacement compensation data structure table and other feed-forward data models. Confucianism effect and actuator crawling and other issues.

Example 1

Ceramic radome grinding machine, its technical index requirements are: grinding diameter ≤ Φ500mm, the minimum setting unit of the grinding wheel frame is 0.1μm, the actual grinding allowance is <10μm, but the grinding machine including the micro-feeding system is required to have good rigidity and work stability. Based on the MG1520 precision grinding machine, the minimum setting unit of the grinding wheel frame of the grinding machine is 1 μm.

The basic configuration of the micro-feeding system is given as follows:

(1) The main technical characteristics and related parameters of the driving device: the driving power supply voltage is 0-150V, the maximum output force of piezoelectric ceramics is 3600N, and the maximum output displacement is 60μm;

(2) The main technical characteristics and related parameters of the actuator are that the flexible hinge adopts a parallelogram structure composed of straight circles and double levers, and the scaling factor T _f = 1/3 of the flexible hinge and piezoelectric ceramics is taken, and the pre-tightening force P _P = 150N. According to formula (9), it can be known that:

${\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}{{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}\frac{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 60</span>}}\frac{\mathrm{<span\; class="notranslate">\; 3600</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 150</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 150</span>}}{\mathrm{<span\; class="notranslate">\; 3600</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 540</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; \&mu;m</span>}<span\; class="notranslate">\; )</span>$

(3) The main technical characteristics and relevant parameters of the detection device: an inductive position detection instrument is adopted, and its relevant technical parameters are that the detection resolution is 0.01 μm.

(4) Main technical features of the control system: carry out the control system configuration of this embodiment according to the requirements and the control principle shown in Figure 6, such as adopting 32-bit microprocessors, 16-bit D/A and A/D converters, high precision position detection sensor (see Figure 7).

According to the basic requirements of the ceramic radome grinding process, the solution adopted is to configure a micro-feeding system based on the MG1500 grinder. The micro-feeding system is developed according to the above-mentioned main technical features and related parameters, and the measured stiffness of the micro-feeding workbench of the ceramic radome grinding machine is 360N/μm. Other technical indicators of the grinding machine are: the minimum grinding wheel frame The setting unit is 0.1μm, the feed positioning accuracy is ±0.02, and the roundness error is less than 10μm.

Example 2

The technical index requirements of the precision grinding machine for the spindle rod bearing gear are: the grinding diameter is less than or equal to Φ300mm, the minimum setting unit of the grinding wheel frame is 0.5μm, and the grinding accuracy of the spindle rod bearing gear is IT5 (the tolerance corresponding to the maximum size of the bearing gear The value is 0.023μm), and the consistency of the bearing stall diameter during batch grinding is less than 10μm. However, the minimum setting unit of the grinding wheel frame of the existing MG1320E precision grinding machine is 1 μm. For this reason, based on the MG1320E precision grinding machine, the micro-feeding system of the present invention is added.

The basic configuration of the micro-feeding system is:

(1) The main technical characteristics and related parameters of the driving device: the driving power supply voltage is 0-150V, the maximum output force of piezoelectric ceramics is 3500N, and the maximum output displacement is 100μm (see Figure 4);

(2) The main technical characteristics and related parameters of the actuator are that the flexible hinge adopts a parallelogram structure composed of straight circles and double levers, the pre-tightening force P _P = 150N, and the scaling factor T _f of the flexible hinge and piezoelectric ceramics = 1/3.5, that is, by reducing the working stroke (to 28μm), the feed resolution and output stiffness of the micro-feed system are improved. According to formula (9), it can be known that:

${\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}{{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}\frac{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 100</span>}}\frac{\mathrm{<span\; class="notranslate">\; 3500</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 150</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 150</span>}}{\mathrm{<span\; class="notranslate">\; 3500</span>}}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 428</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; \&mu;m</span>}<span\; class="notranslate">\; )</span>$

(3) Main technical features and relevant parameters of the detection device: an inductive position detection instrument is adopted, and its relevant technical parameters are that the detection resolution is 0.1 μm (100 μm detection range).

(4) The main technical characteristics of the control system: carry out the control system configuration of the present embodiment according to the control principle shown in Fig. Precision position detection sensor.

According to the technical index requirements of the precision grinding machine for spindle bar bearing gear, the solution adopted is to configure a micro-feeding system based on the MG1320E grinding machine. The main technical features and relevant parameters involved in the micro-feed system are as above, and the technical indicators of the precision grinding machine for the spindle bearing gear are obtained from this: the minimum setting unit of the grinding wheel frame is 0.5 μm, the feed positioning accuracy is ±0.2, When using fixed-range grinding for batch processing, the diameter consistency of the workpiece to be processed can be controlled within 10 μm.

Claims (4)

1. A micro-feed system for precision grinding, comprising four parts of a drive unit, an actuator, a detection device and a control system; it is characterized in that: Described driving device (9) is made up of piezoelectric driving power supply, piezoelectric ceramics, man-machine interface input device, displacement-voltage data structure table, and the ratio of the output stiffness of driving device (9) and the stiffness of micro-feeding system is 1/ 3-1/5; The actuator is composed of a flexible hinge mechanism (8) and a micro-feed table (4). The flexible hinge mechanism (8) is deformed under the voltage excitation of the driving device (9), and the corresponding The micro-displacement is passed to the micro-feed workbench (4); The flexible hinge mechanism (8) integrates the flexible hinge deformation part and the piezoelectric ceramic support part, changes the output position of the flexible hinge deformation, increases the output displacement resolution of the system by 3 to 5 times, and increases the output stiffness by 3 to 5 times. times; The detection device includes an inductive or capacitive position sensor or a grating ruler for detecting the actual output displacement of the micro-feeding system, a detection signal acquisition module, a voltage-displacement compensation data construction table, a signal processing and output module, and identifies the actual displacement through the output voltage. The displacement is used to realize the displacement detection of the micro-feed workbench; The control system includes microprocessor, D/A and A/D converter, data input/output display, signal amplifier, information integration interface, signal processing reference model and algorithm, so as to realize the driving device of the micro-feeding system, execute Data input/output, information processing and collaborative control of institutions and detection devices. 2. The micro-feed system for precision grinding according to claim 1, characterized in that, the micro-feed workbench (4) is a traditional grinding machine grinding wheel frame (5) and wheel frame workbench (3 ) is added between a stage driven by a flexible hinge mechanism (8) that deforms under the voltage excitation of the driving device (9), that is, a secondary stage. 3. The micro-feed system for a precision grinding machine according to claim 1, wherein the structure of the deformable part of the flexible hinge is a parallelogram structure consisting of straight circles and double levers. 4. the micro-feed system that is used for precision grinding according to claim 1, is characterized in that, described control system signal processing reference model is by the feed-forward of displacement-voltage data construction table, voltage-displacement compensation data construction table The main data is the processing results of the support vector machine and computational intelligence algorithm to solve the problems of piezoelectric ceramic hysteresis, variable effect and actuator crawling.

Images