CN203973264U - A kind of fast tool servo of two decoupler shafts - Google Patents

Abstract

The utility model relates to a two-axis decoupling fast tool servo device, which belongs to the technical field of cutting optical curved surface parts and ultra-precision parts. The diamond tool is fixedly connected to the tool seat on the flexible hinge base through fixing screws, and the two ends of the X-axis piezoelectric stack are respectively connected to the flexible hinge base and the X-axis driving end. The X-axis piezoelectric stack is connected by a pre-tightening bolt Connected with the flexible hinge base, Z-axis piezoelectric stack 1 and Z-axis piezoelectric stack 2 are respectively connected to the flexible hinge base and the Z-axis driving end, and a displacement detection block is installed behind the flexible hinge base tool holder, and It is fixedly connected with the base body of the flexible hinge through fixing screws. The advantages are that the structure is novel, and the piezoelectric driver is used to drive the flexible mechanism in parallel, which reduces the inertial mass of the moving part of the flexible hinge mechanism, is beneficial to increase the working bandwidth of the FTS device, and improves the processing efficiency of the FTS device.

Description

A Two-Axis Decoupled Fast Tool Servo Device

technical field

The utility model belongs to the technical field of cutting and processing of optical curved surface parts and ultra-precision parts, and relates to a two-axis decoupling fast tool servo device for free-form surface diamond turning.

Background technique

Free-form optical components are not only widely used in optoelectronic products and optical communication products, but also widely used in military fields such as infrared detection equipment and helmet-mounted displays. In addition, in view of the fact that many non-free-form optical elements can be obtained by using fewer free-form optical elements to realize the function, simplify the structure of the optical system and reduce the quality and volume of the optical system, which is very important for the integration and miniaturization of the optical system. is of great significance. Although the optical free-form surface has many excellent properties and uses mentioned above, the complexity and uncertainty of the processing process seriously restrict its practical application, so it is necessary to develop a high-precision, high-efficiency and low-cost optical free-form surface processing device or method very important.

At present, diamond turning based on Fast Tool Servo (hereinafter referred to as FTS) is an optical free-form surface processing method that can meet the above requirements, and it is also recognized as one of the most promising processing methods. The key point is how to realize the high precision, multiple degrees of freedom, low coupling, high bandwidth and large stroke of the FTS device. However, most of the existing FTS devices are still mainly single-axis linear FTS and swing FTS, which are difficult to meet the requirements of processing high-quality optical free-form surfaces. The reasons are: (1) The processing of free-form optical elements The process requires that the tool can simultaneously realize high-frequency reciprocating motion or swing along multiple motion axes relative to the workpiece, but most of the existing single-degree-of-freedom FTS can only reciprocate along the Z axis or reciprocate around the Y axis; (2) for To ensure that the contact point between the blade and the machined surface can move evenly on the machined surface and reduce the fluctuation of cutting force during the machining process, it is also required that the FTS device can realize reciprocating linear motion along the X-axis. Obviously, the single-degree-of-freedom FTS can no longer meet the above requirements. Require.

For the existing multi-axis linear FTS device, although it can provide reciprocating motion along the X-axis and Z-axis, the shortcomings of high coupling and low bandwidth limit its application in optical free-form surface processing. The research group of Zou Qing of Jilin University has developed multi-axis FTS devices with different mechanisms (public numbers: 103357894A, 102615542A). Bandwidth is the price, and ideal decoupling motion cannot be obtained; in addition, Zhou Xiaoqin’s research group at Jilin University has developed a variety of fast servo devices for The vibration cutting process does not need the characteristics of large stroke and low coupling. Although these devices can obtain high working bandwidth, the defects of small stroke and high coupling restrict their application in optical free-form surface turning. So far, the high-frequency multi-axis FTS device that can achieve two-axis decoupling is rarely mentioned, but the parallel two-axis FTS device proposed by the utility model can meet the requirements of the FTS device during the processing of free-form surface optical elements. Many performance requirements, so it has a wide range of application prospects.

Contents of the invention

The utility model proposes a two-axis decoupling fast tool servo device, which is used for processing optical free-form surfaces with high precision and high uniformity.

The technical solution adopted by the utility model is: the diamond tool is fixedly connected with the knife seat on the flexible hinge base through a set of fixing screws, and the flexible hinge base is fixedly connected with the U-shaped groove on the base through a set of fixing bolts, and a The cover plate and the front end of the base are equipped with a front baffle, and the two ends of the X-axis piezoelectric stack are respectively connected with the flexible hinge base and the X-axis driving end. The X-axis piezoelectric stack is connected to the flexible The hinge base is connected, the Z-axis piezoelectric stack 1 and the Z-axis piezoelectric stack 2 are respectively connected to the flexible hinge base and the Z-axis driving end, and are respectively connected to the flexible hinge base by pre-tightening bolt 2 and pre-tightening bolt 3; A displacement detection block is installed on the back of the flexible hinge base body tool holder, and is fixedly connected to the flexible hinge base body by fixing screws. One end of the X-direction capacitive sensor and the Z-direction capacitive sensor are respectively in contact with the two sides of the displacement detection block, and the other end is in contact with the two sides of the displacement detection block. Pass through the positioning holes of the mounting block 1 and the mounting block 2 respectively and use the fixing bolt 1 and the fixing bolt 2 to be fixedly connected, and the two mounting blocks are fixedly connected to the two U-shaped grooves of the base through the fixing bolts respectively.

Each pre-tightening bolt of the utility model is respectively coaxial with the corresponding piezoelectric stack, so that the pre-tightening bolt generates a pre-tightening force along the axial direction on the piezoelectric stack, thereby realizing the pre-tightening of the three piezoelectric stacks.

The flexible hinge base of the utility model includes: a group of symmetrical parallel X-axis guide hinges connected to the X-axis input end, the X-axis input end is connected to the diamond tool seat through a group of parallel Z-axis decoupling hinges; a group of symmetrical parallel connection The Z-axis guide hinge is connected to the Z-axis input end, and the Z-axis input end is connected to the diamond tool holder through a set of parallel X-axis decoupling hinges.

The utility model utilizes the characteristic of high stiffness difference ratio in the width direction (Z axis) and the thickness direction (Y axis) of the straight plate flexible hinge for decoupling, and is respectively arranged in the width direction (Z axis) and the thickness direction (Y axis). The stiffness is k _t and k _w , then according to the relevant knowledge of material mechanics, the following relationship can be obtained:

$\frac{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; EI</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}{\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; EI</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; wt</span>}}^{\mathrm{<span\; class="notranslate">\; 3</span>}}}{{\mathrm{<span\; class="notranslate">\; w</span>}}^{\mathrm{<span\; class="notranslate">\; 3</span>}}\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; t</span>}}{\mathrm{<span\; class="notranslate">\; w</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Among them, F is the applied force, E is the elastic modulus of the flexible hinge material, I _t is the moment of inertia of the section relative to the neutral axis t, I _w is the moment of inertia of the section relative to the neutral axis w, and t is the flexible hinge The thickness, w is the width of the flexible hinge.

It can be seen from the above formula that the ratio of stiffness in two directions is equal to the square of the ratio of width to thickness, and in most cases, the ratio of width to thickness of straight flexible hinges is generally less than 1/10, then the X axis and Z The kinematic coupling of the axes should be less than 1%, which realizes the decoupling of knives in two directions in the FTS device. In addition, the ratio of the width and thickness of the flexible hinge can be reasonably determined according to the restrictions on the coupling amount under different usage conditions. Usually, an appropriate thickness can be selected first, and then the width and length of the flexible hinge can be determined according to the determined ratio and stiffness requirements.

The main advantages of the utility model are: the structure is novel, and the flexible mechanism is driven in parallel by piezoelectric drivers, which reduces the inertial mass of the moving part of the flexible hinge mechanism, which is beneficial to increase the working bandwidth of the FTS device and improve the processing efficiency of the FTS device; The stiffness of the straight flexible hinge in the thickness direction is much greater than that in the width direction, as shown in formula (1), in order to realize the decoupling of the input and output of the flexible hinge mechanism, improve the motion accuracy of the FTS device, and reduce the processing error.

Description of drawings

Fig. 1 is the structural representation of the front view of the utility model;

Fig. 2 is the structural representation of rear view of the utility model;

Fig. 3 is a structural schematic diagram of removing the base of the utility model;

Fig. 4 is a structural schematic diagram of the flexible hinge base of the present invention;

Fig. 5 is a partial cross-sectional view of the flexible hinge base of the utility model;

Fig. 6 is a schematic structural view of the utility model base;

Fig. 7 is a schematic diagram of a straight-type flexible hinge unit of the present invention.

Detailed ways

The diamond tool 5 is fixedly connected to the tool seat on the flexible hinge base 6 through fixing screws, and the flexible hinge base 6 is fixedly connected to the U-shaped groove on the base 2 through a set of fixing bolts. A cover plate 1 is installed above the base, and the base A front baffle 7 is installed on the front end of the X-axis piezoelectric stack 801, and the two ends of the X-axis piezoelectric stack 801 are respectively connected to the flexible hinge base 6 and the X-axis driving end 606. The X-axis piezoelectric stack 801 is connected to the The flexible hinge substrate is connected, and the Z-axis piezoelectric stack 1 802 and the Z-axis piezoelectric stack 2 803 are respectively connected with the flexible hinge substrate 6 and the Z-axis driving end 607, and are connected with the pre-tightening bolt 2 1002 and the pre-tightening bolt respectively. Three 1003 is connected with the flexible hinge substrate; the displacement detection block 9 is installed on the back of the flexible hinge substrate tool seat, and is fixedly connected with the flexible hinge substrate by fixing screws, and one end of the X-direction capacitive sensor 401 and the Z-direction capacitive sensor 402 are respectively connected with the flexible hinge substrate. The two sides of the displacement detection block 9 are in contact with each other, and the other end passes through the positioning holes of the first mounting block 301 and the second mounting block 302 and is fixedly connected with the fixing bolt 1101 and the fixing bolt 2 1102 respectively. It is fixedly connected with the two U-shaped grooves of the base.

Each pre-tightening bolt of the utility model is respectively coaxial with the corresponding piezoelectric stack, so that the pre-tightening bolt generates a pre-tightening force along the axial direction on the piezoelectric stack, thereby realizing the pre-tightening of the three piezoelectric stacks.

The flexible hinge base of the utility model includes: a group of symmetrical parallel X-axis guide hinges 601 connected to the X-axis input end 606, and the X-axis input end 606 is connected to the diamond tool holder 605 through a group of parallel Z-axis decoupling hinges 604; A set of symmetrical parallel Z-axis guide hinges 603 is connected to the Z-axis input end 607 , and the Z-axis input end 607 is connected to the diamond tool holder 605 through a set of parallel X-axis decoupling hinges 602 .

Below, according to Figures 1 to 6, further explanations are as follows:

The diamond tool 5 is fixedly connected with the tool seat 605 on the flexible hinge base through fixing screws, and the tool is indirectly driven by three piezoelectric stacks through the flexible hinge base, and the three piezoelectric stacks can be driven by a signal generator or an industrial controller , and finally realize the high-frequency decoupling movement of the diamond tool along the X-axis and Z-axis.

The flexible hinge base 6 is mainly composed of straight hinges arranged perpendicular to each other: X-axis guide hinge 601, X-axis decoupling hinge 602, Z-axis guide hinge 603, and Z-axis decoupling hinge 604, as shown in Figures 4 and 5. shown, and decoupling is performed by using the high stiffness ratio of the straight hinge in the width direction and the thickness direction; the X-axis piezoelectric stack 801 indirectly drives the diamond tool 5 through the Z-axis decoupling hinge 604, and the two Z-axis piezoelectric stacks The stack indirectly drives the diamond tool 5 through the X-axis decoupling hinge 602, and finally realizes the decoupling of the input and output of the device of the present invention in the directions of the X-axis and the Z-axis; The stack adopts a synchronous driving method, which can solve the parasitic error of the tool along the Y direction caused by manufacturing errors.

The flexible hinge base 6 is installed on the base 2 through a set of fixing bolts, and can realize the fine adjustment of the position of the diamond tool 5 in the Y-axis direction to complete the tool setting. Two capacitive displacement sensors are respectively fixed on the base 2 with sensor mounting blocks, and the displacement The displacement detected by the sensor can be used as the feedback signal of the closed-loop control system to improve the accuracy of the servo motion of the FTS system.

The three pre-tightening bolts are respectively threaded with the flexible hinge base 6 through threads, and the three piezoelectric stacks can be pre-tightened respectively by adjusting the tightening degree of the threaded connections. coaxial, so that the pre-tightening bolts generate an axial pre-tightening force on the piezoelectric stack, thereby realizing the pre-tightening of the three piezoelectric stacks.

The utility model utilizes the characteristic of high stiffness difference ratio in the width direction (Z axis) and the thickness direction (Y axis) of the straight plate flexible hinge for decoupling, and is respectively arranged in the width direction (Z axis) and the thickness direction (Y axis). The stiffness is k _t and k _w , then according to the relevant knowledge of material mechanics, the following relationship can be obtained:

$\frac{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; EI</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}{\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; EI</span>}}_{\mathrm{<span\; class="notranslate">\; w</span>}}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; wt</span>}}^{\mathrm{<span\; class="notranslate">\; 3</span>}}}{{\mathrm{<span\; class="notranslate">\; w</span>}}^{\mathrm{<span\; class="notranslate">\; 3</span>}}\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; t</span>}}{\mathrm{<span\; class="notranslate">\; w</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Among them, F is the applied force, E is the elastic modulus of the flexible hinge material, I _t is the moment of inertia of the section relative to the neutral axis t, I _w is the moment of inertia of the section relative to the neutral axis w, and t is the flexible hinge The thickness, w is the width of the flexible hinge.

It can be seen from the above formula that the ratio of stiffness in two directions is equal to the square of the ratio of width to thickness, and in most cases, the ratio of width to thickness of straight flexible hinges is generally less than 1/10, then the X axis and Z The kinematic coupling of the axes should be less than 1%, which realizes the decoupling of knives in two directions in the FTS device. In addition, the ratio of the width and thickness of the flexible hinge can be reasonably determined according to the restrictions on the coupling amount under different usage conditions. Usually, an appropriate thickness can be selected first, and then the width and length of the flexible hinge can be determined according to the determined ratio and stiffness requirements.

Claims (3)

1. A two-axis decoupling fast tool servo device, characterized in that: the diamond tool is fixedly connected to the tool holder on the flexible hinge base through fixing screws, and the flexible hinge base is fixed to the U-shaped groove on the base through a set of fixing bolts A cover plate is installed above the base, and a front baffle is installed on the front end of the base. The two ends of the X-axis piezoelectric stack are respectively connected with the flexible hinge base and the X-axis driving end. The X-axis piezoelectric stack The stack is connected to the flexible hinge base through pre-tightening bolt 1, Z-axis piezoelectric stack 1 and Z-axis piezoelectric stack 2 are respectively connected to the flexible hinge base and the Z-axis driving end, and are respectively connected with pre-tightening bolt 2 and pre-tightening bolt 2. Tightening bolt three is connected with the base of the flexible hinge; a displacement detection block is installed behind the knife seat of the base of the flexible hinge, and is fixedly connected with the base of the flexible hinge through fixing screws, and one end of the X-direction capacitive sensor and one end of the Z-direction capacitive sensor are respectively connected to the displacement detection block. The two sides of the block are in contact, and the other end passes through the positioning holes of the first mounting block and the second mounting block respectively and is fixedly connected with the fixing bolts 1 and 2. Groove fixed connection. 2. The two-axis decoupled fast tool servo device according to claim 1, characterized in that: each of the pre-tightening bolts is coaxial with the corresponding piezoelectric stack, so that the pre-tightening bolts are on the piezoelectric stack An axial preload is generated, thereby preloading the three piezo stacks. 3. The two-axis decoupled fast tool servo device according to claim 1 or 2, characterized in that: the flexible hinge base comprises: a group of symmetrical parallel X-axis guide hinges connected to the X-axis input end, the X-axis The axis input end is connected to the diamond tool holder through a set of parallel Z-axis decoupling hinges; a set of symmetrical parallel Z-axis guide hinges is connected to the Z-axis input end, and the Z-axis input end is connected to the Z-axis input end through a set of parallel X-axis decoupling hinges. The diamond tool holders are connected.