KR20150073710A - Improved linearity of tool holder the FTS - Google Patents

Abstract

Disclosed is a micro-cutting device having improved linearity of a tool holder. The disclosed micro-cutting device having improved linearity of a tool holder comprises: a cylindrical body wherein a relative coupling unit is provided to be coupled to a coupling unit of a processing machine in the rear, and an installation chamber is arranged in the front; a spring holder consisting of a spring housing inserted into the installation chamber and a fixing plate provided in front of the spring housing to be fixated on the front of the body; a tool holder holding a tool while being arranged in an axially central portion of the spring holder; a plurality of leaf springs wherein an outer circumference is fixated on an inner circumferential surface of the spring housing, and an inner circumference is fixated on an outer circumferential surface of the tool holder so that the tool holder can be elastically supported in a diameter direction in the spring holder; and an actuator enabling the tool holder to proceed.

Description

[0001] The present invention relates to a tool holder having an improved straightness,

The present invention relates to a microcutting apparatus with improved straightness of a tool holder.

Particularly, the tool holder and the holder housing are connected in parallel by two or more leaf springs, and the leaf spring is arranged radially symmetrically with respect to the axial line so as to be able to perform an accurate linear movement without being deflected in the linear movement of the tool holder The tool holder can be firmly fixed by applying chucking of a shape memory alloy which shrinks at room temperature when chucking the tool to the tool holder and expands at room temperature when chucking the tool. To an improved micro-cutting apparatus.

Recently, as semiconductor, aerospace, image information, and precision machine industry have developed, the need for ultra-precision processing technology is increasing more and more. In ultra-precision machining, ultra-precision cutting technology using diamond tools has an infeed amount of several ㎛ to several tens of ㎛,

If controlled to submicrometers, there is a possibility that a surface without grain boundary step and an ideal surface without defect are obtained.

However, in the ultra-precision machining apparatus, the motion characteristics of the main parts such as the main shaft and the transfer device greatly affect the machining accuracy. Therefore, in order to realize higher machining accuracy, the motion precision of each element component is improved, .

Particularly, in recent super precision machining apparatuses, although the machining accuracy increases with the diameter of the machinable workpiece increases, although the stroke distance of each slide is relatively long by several hundreds of millimeters, a high resolution of ㎚ level and a high motion tablet

Density is required. However, in this case, since the inertia mass of the transfer part is very large, the response speed is absolutely slow to compensate for the motion error in real time, and real-time motion error compensation becomes very difficult.

In order to overcome such a problem, it is possible to precisely measure the motion precision of the main axis and the transfer system while finely driving only the relatively small mass of the cutting tool and the tool holder using the piezoelectric actuator, (FTS) is used as a cutting tool, and a vibration cutting device is used in which a fine pattern is processed by inducing a geometric movement at the tip of a tool by using a high-speed response of the piezoelectric actuator.

An example of a conventional micro-cutting device for machining a super-precision product described above is a movable part on which a micro-cutting tool of Korean Utility Model Registration No. 20-0145496 is mounted, a movable part provided on a lower part of the movable part, Side elastic supporting means for elastically supporting the upper and lower sides of at least one side of the movable portion and the upper and lower sides of the movable portion in a forward and a backward direction, And the rigidity with respect to all the lateral directions of the tool transfer device for transferring the tool by the piezoelectric material is improved by providing the side elastic support means.

However, in the above-mentioned conventional micro-cutting apparatus, the moving part is not symmetrically supported by the elastic supporting means, and the correction accuracy of the motion error is lowered. That is, in the conventional micro-cutting apparatus, the left and right sides and the lower side of the movable part are supported by the elastic supporting means, but since the upper side is not supported, the movable part may not be precisely rectilinearly moved.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a tool holder and a holder housing which are connected in parallel by two or more leaf springs, The present invention is to provide a micro-cutting apparatus in which the straightness of a tool holder is improved so as to enable accurate straight movement without being deflected during linear movement of the tool holder.

Another object of the present invention is to provide a tool holder that can firmly fix a tool by applying chucking with a chucking means at a normal temperature when chucking the tool to a tool holder and chucking with an expanding shape memory alloy at the time of cooling And a micro-cutting device with improved straightness.

According to an aspect of the present invention,

A cylindrical main body having a relative engaging portion for engaging with the engaging portion of the processing machine at the rear and provided with a mounting chamber at the front; A spring holder including a spring housing which is inserted into the installation chamber and a fixing plate which is fixed to a front surface of the main body while being provided in front of the spring housing; A tool holder disposed at an axial center of the spring holder and holding the tool; A plurality of leaf springs having an outer periphery fixed to an inner peripheral surface of the spring housing and an inner periphery fixed to an outer peripheral surface of the tool holder so that the tool holder is resiliently supported on the spring holder in a radial direction; And an actuator for advancing the tool holder, wherein the tool holder has improved linearity.

Further, an actuator insertion groove is formed in the rear of the tool holder of the present invention. The actuator insertion groove is in contact with the actuator, and the tip of the actuator is in point contact with the spherical surface having different diameters.

Further, the actuator of the present invention is characterized by being a piezo actuator.

In addition, the present invention is characterized in that the distal end of the relative coupling portion and the distal end of the coupling portion into which the distal end of the relative coupling portion is inserted are angular.

Further, the present invention is characterized in that a plurality of cooling holes are formed on the circumferential surface of the main body.

Further, the tool holder of the present invention includes: a tool insertion ring having a plurality of axial cuts formed therein and having a tool pocket into which a part of the tool is inserted; And a tightening ring made of a shape memory alloy material that is fitted to the surface of the tool insertion ring and contracts at a normal temperature to tighten the tool insertion ring and expands at the time of cooling to relax the tool insertion ring.

The leaf springs of the present invention are arranged symmetrically when viewed in the axial direction.

In addition, the leaf spring of the present invention is characterized by a rectangular cross section or a trapezoidal cross section.

Further, the present invention is characterized by including a notch portion formed at the distal end of each leaf spring.

Further, the present invention is characterized in that an assembling direction indicating portion is formed on the outer circumferential surface of the main body so that the main body can be positively assembled when the main body is assembled to the assembling portion of the processing machine.

According to the present invention as described above, the tool holder and the holder housing are connected in parallel by two or more leaf springs. By arranging the leaf springs symmetrically with respect to the axial line, the tool holder is not deflected to one side when the tool holder linearly moves, It is advantageous to reduce the machining error as the motion becomes possible.

In addition, the present invention utilizes the shape memory to chuck the tool on the tool holder, thereby firmly fixing the tool, thereby preventing the tool from falling off, thereby enhancing the reliability of the apparatus.

1 is a cross-sectional view of an installation state of a microcutting device according to the present invention;
Fig. 2 is a partially exploded perspective view of the microcutting device according to the present invention.
Fig. 3 is a perspective view of the micro-cutting device according to the present invention,
Fig. 4A is a perspective view of the microcutting device according to the present invention before tool chucking; Fig.
FIG. 4B is a perspective view of the tool of FIG.
5A shows a tool chucking structure of another embodiment of the micro-cutting apparatus according to the present invention,
FIG. 5B shows a tool chucking structure of another embodiment of the microcutting device according to the present invention,
FIGS. 6A to 6D are cross-sectional views showing a state in which various types of leaf springs are installed in a micro-cutting apparatus according to the present invention.
7 is a schematic view for explaining a leaf spring design element in a micro-cutting apparatus according to the present invention;
FIG. 8 is a graph showing the relationship between a reference graph for optimum designing of a leaf spring in a micro-

The advantages and features of the present invention and the techniques for achieving them will be apparent from the following detailed description taken in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. The present embodiments are provided so that the disclosure of the present invention is not only limited thereto, but also may enable others skilled in the art to fully understand the scope of the invention. Like reference numerals refer to like elements throughout the specification.

The terms used herein are intended to illustrate the embodiments and are not intended to limit the invention. In this specification, the singular forms include plural forms unless otherwise specified in the text. It is to be understood that the terms 'comprise', and / or 'comprising' as used herein may be used to refer to the presence or absence of one or more other components, steps, operations, and / Or additions.

FIG. 2 is a partially exploded perspective view of a micro-cutting apparatus according to the present invention, and FIG. 3 is a perspective view of a micro-cutting apparatus according to the present invention.

1 to 3, the FTS (Fast Tool Servo) 100 according to the present invention has a structure in which a tool holder is stably linearly moved, and includes a main body 110, a spring holder 120 A tool holder 130, a leaf spring 140, and an actuator 150. As shown in Fig.

The main body 110 is formed in a cylindrical shape and the rear part is provided with a relative coupling part 111 for coupling with the coupling part 1a of the processing machine 1 such as a lathe, The mounting chamber 112 is provided.

A plurality of cooling holes 113 are formed on the circumferential surface of the main body 110 along the circumferential direction. The cooling holes 113 are communicated with the outside, and the driving heat generated in the actuator 150 installed in the main body 110 is naturally cooled by the air, thereby preventing operational errors due to overheating.

It is preferable that the distal end of the relative coupling portion 111 and the distal end of the coupling portion 1a into which the distal end of the relative coupling portion 111 is inserted are angular. The relative coupling portion 111 and the engaging portion 1a have the same angular shape so that the main body 110 can be assembled without slipping in the circumferential direction at the time of coupling, .

In addition, an assembly direction indicator 114 may be formed on the outer circumferential surface of the main body 110. The assembly direction display portion 114 serves as a visual guide for enabling the body assembly 110 to be assembled when assembled to the coupling portion 1a of the processing machine 1. [

In other words, since the main body 110 is cylindrical, it is difficult to measure the assembly direction. However, if the assembly direction indicator 114 is marked as described above, it can visually recognize the assembly direction,

The spring holder 120 is for supporting the leaf spring 140 and includes a spring housing 121 in which the leaf spring 140 is installed when the leaf spring 140 is inserted into the installation chamber 112, And a fixing plate 122 fixed to the front surface of the main body 110 while being disposed in front of the main body 110.

The fixing plate 122 may be attached to the front surface of the main body 110 and then assembled as a screw from the outside. Alternatively, a thread may be formed on the outer circumferential surface of the spring housing 121, A method of forming a counterpart thread to be engaged with the thread and screwing it by a thread and a counter thread may be applied.

FIG. 4A is a perspective view of the minute cutting apparatus according to the present invention before tool chucking, and FIG. 4B is a perspective view after tool chucking of the minute cutting apparatus according to the present invention.

Referring to FIGS. 4A and 4B, the tool holder 130 is for holding a tool 2, and is disposed in the axial center portion of the spring holder 120.

The tool holder 130 is formed with a plurality of axial cutouts 131a so as to be able to contract and relax in the circumferential direction and includes a tool insertion ring 131b having a tool pocket 131b into which a part of the tool 2 is inserted. 131); And a tightening ring 132 for tightening the tool inserted into the tool insertion ring 131 by pressing the surface of the tool insertion ring 131.

Here, the tightening ring 132 is fitted on the surface of the tool insertion ring 131 and is contracted at room temperature to tighten the tool insertion ring 131. On the other hand, when the cooling ring 132 is cooled, the tool insertion ring 131 is relaxed And shape memory alloy (shape memory alloy) which is loosened. When the tightening ring 132 is made of a shape memory alloy, the entire circumference is enclosed and tightened, so that a firm fastening force is exerted, so that the tool 2 can be prevented from being detached even when used for a long time.

5A and 5B, the tool holder 130a is fixed to the axial center of the spring holder 120, and the tool tip 2a is fixed to the tip end of the tool holder 130a It is also possible to form a seating groove 130b for seating the tool tip 2a in the seating groove 130b and fastening and fixing the tool tip 2a with the fixing bolt 130c.

6A to 6D are cross-sectional views of various portions of the micro-cutting apparatus according to the present invention, in which various types of leaf springs are installed, FIG. 7 is a main part for explaining a leaf spring design element in the micro- 8 is a reference graph for the optimum design of the leaf spring in the micro-cutting apparatus according to the present invention.

The leaf spring 140 serves to elastically connect the spring housing 121 and the tool holder 130 and plays a key role in enabling the accurate movement of the tool holder 130 .

The outer circumference of the leaf spring 140 is fixed to the inner circumferential surface of the spring housing 121 and the inner circumference is fixed to the outer circumferential surface of the tool holder 130.

The leaf springs 140 are formed of a plurality of leaf springs 140 arranged radially with respect to the axis O and symmetrically arranged so as to receive uniform elasticity in the forward and backward movement of the tool holder 130 Respectively. This arrangement is an improvement over the conventional spring arrangement described above, and the improved structure allows for an accurate linear movement without deflecting to one side during the forward and backward movement of the tool holder 130 .

The leaf springs 140 include a main plate spring 141 located between the spring housing 121 and the tool holder 130 at a front side and a main plate spring 141 located at the rear side of the main plate spring 141 And a pair of sub-plate springs 142 that are positioned in the sub-springs.

6A and 6C, the leaf springs 140 may have a rectangular cross section and a trapezoidal cross section. In addition, as shown in FIGS. 6B and 6D, a notch 143 may be further formed at the end of the square or trapezoid. In the case of the shape without the notch 143, the plate spring can be easily machined, the stiffness is stronger than the shape with the notch, and the durability is good. However, There is a disadvantage in that the stress is concentrated on the notched portion 143 during long-time use and there is a risk of breakage. Therefore, in consideration of these advantages and disadvantages, appropriate forms should be selected and applied according to the situation.

7, the design parameters of the leaf spring 140 include a spring thickness T _S , a spring radius R _S , a distance L _MS from the end of the tool holder 130 to the main plate spring 141 , And the distance L _SS between the main plate spring 141 and the sub-plate spring 142.

For example, as shown in FIG. 8, when the radius of the leaf spring is 26 mm, the resonance frequency (flutter phenomenon of the leaf spring) becomes maximum when the resonance frequency region according to the ratio change of L _ms : L _SS is 1: 1.5 . Therefore, designing at a ratio of 1: 1.5 or less is an optimum design requirement for reducing the resonance frequency. However, this is only an example, and if the radius of the leaf spring is changed, the change of the ratio of L _ms : L _SS will also be changed.

Referring again to FIG. 1, the actuator 150 advances the tool holder 130. It is preferable that the actuator 150 is a piezo actuator capable of precisely controlling the actuator.

An actuator insertion groove 133 is formed in the rear of the tool holder 130 to insert the actuator 150 into the actuator insertion groove 133. The tip of the actuator in contact with the actuator insertion groove 133 has a spherical surface having a different diameter, Point contact. The reason for adopting such a point contact structure is that, in the case of surface contact or line contact, if the tilting occurs in one direction due to the tilting, the tool holder 130 does not perform a straight movement accurately but performs a deflection movement, , And point contact is not affected by the tilt, unlike the above case, so that it can exhibit precise straightness.

The micro-cutting apparatus 100 according to the present invention can form a fine-sized embossing pattern on the surface of a workpiece by repeated turning back and forth of the tool as well as general turning.

1: Processing machine 100: Micro-cutting device
110: main body 111:
112: installation chamber 113: cooling hole
114: assembly direction display part 120: spring holder
121: spring housing 122: fixed plate
130: Tool holder 131: Tool insertion ring
132: tightening ring 140: leaf spring
141: main plate spring 142: sub-plate spring
143: Notch 150: Actuator

Claims (11)

A cylindrical main body having a relative engaging portion for engaging with the engaging portion of the processing machine at the rear and provided with a mounting chamber at the front;
A spring holder including a spring housing which is inserted into the installation chamber and a fixing plate which is fixed to a front surface of the main body while being provided in front of the spring housing;
A tool holder disposed at an axial center of the spring holder and holding the tool;
A plurality of leaf springs having an outer periphery fixed to an inner peripheral surface of the spring housing and an inner periphery fixed to an outer peripheral surface of the tool holder so that the tool holder is resiliently supported on the spring holder in a radial direction; And
An actuator for advancing the tool holder;
Wherein the tool holder has a straightness improving function.
The method according to claim 1,
Wherein an actuator insertion groove is formed in the rear of the tool holder to insert a tip of the actuator and the tip end of the actuator in contact with the actuator insertion groove is in point contact with a spherical surface having a different diameter. Device.
3. The method according to claim 1 or 2,
Wherein the actuator is a piezo actuator. ≪ RTI ID = 0.0 > 8. < / RTI >
The method according to claim 1,
Wherein a distal end of the relative coupling portion and a distal end of a coupling portion into which the distal end of the relative coupling portion is inserted are angular.
The method according to claim 1,
Wherein a plurality of cooling holes are formed on a circumferential surface of the main body.
The method according to claim 1,
Wherein the tool holder comprises:
A tool insertion ring having a plurality of axial incisions formed therein and having a tool pocket into which a portion of the tool is inserted; And
And a tightening ring made of a shape memory alloy material which is fitted on the surface of the tool insertion ring and contracts at a normal temperature to tighten the tool insertion ring and expands at the time of cooling to relax the tool insertion ring. The micro-cutting device improved in the straightness of the workpiece.
The method according to claim 1,
Wherein the leaf springs are disposed symmetrically when viewed in the axial direction.
8. The method of claim 7,
Wherein the plate spring has a rectangular cross section or a trapezoid cross section.
9. The method of claim 8,
And a notch portion formed at a distal end portion of each of the leaf springs.
The method according to claim 1,
Wherein an assembling direction indicating portion is formed on an outer circumferential surface of the main body so that the main body can be positively assembled when assembling the main body to the assembling portion of the processing machine.
The method according to claim 1,
Wherein each of the leaf springs is composed of a pair of main plate springs located on the front side between the spring housing and the tool holder and sub plate springs located rearwardly at regular intervals from the main plate spring, This improved micro-cutting device.

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