CN1745965A - Elliptical ultrasonic vibration inhibition - Google Patents

Abstract

A method for suppressing the flutter of cutting tool by ultrasonic elliptical vibration includes such steps as sticking the piezoelectric ceramic onto two vertically intersected surfaces of an elliptical vibration amplitude varying rod, applying sine voltage to them for generating bending vibration, fixing cutting tool to the end of said elliptical vibration amplitude varying rod, where the vibration amplitude is maximal, synthesizing the bending vibrations in horizontal and vertical directions to obtain an elliptical vibration trace on cutting tool, and fixing said amplitude varying rod to fixture.

Description

The method of elliptical ultrasonic vibration inhibition

Technical field

What the present invention relates to is the method in a kind of metal cutting technology field, specifically, is a kind of method of elliptical ultrasonic vibration inhibition.

Background technology

Flutter is one of major issue in the machining, and flutter not only influences machining accuracy and surface light knot degree, but also influences the lathe life-span, and particularly to machine parts'precise machining a little less than the rigidity and ultra precision cutting processing, the flutter problem is more outstanding.Therefore, the inhibition of flutter is a urgent problem in the production reality.

Find by prior art documents, people such as Bao Shanfei write articles " time become theory analysis and the experimental verification that feeding suppresses cutting-vibration " on " vibration engineering journal " the 4th phase of nineteen ninety-five, when being, this method becomes the method that feeding suppresses cutting-vibration, theoretical and the analysis of experiments of this article become the effect of feeding inhibition cutting-vibration when adopting, analysis result shows: in time, becomes feed energy and effectively suppresses cutting-vibration, time spent become effect that feeding method suppresses cutting-vibration with the time change amount of feeding amplitude of variation and change frequency closely related, the amplitude of variation and the change frequency that become the amount of feeding are close big more, the effect that suppresses cutting-vibration is good more, in the optimum condition scope, the effect of the rectangle variation waveform inhibition cutting-vibration of the change amount of feeding is best.But, the time become the amount of feeding amplitude of variation select improper will the generation to reduce processed surface smoothness even reduce unfavorable cutting effects such as machining accuracy.

Summary of the invention

The objective of the invention is to overcome the deficiencies in the prior art, propose a kind of method of elliptical ultrasonic vibration inhibition, its machining system stability is obviously improved, eliminate the flutter in the machining, significantly improve machining accuracy and surface smoothness, satisfy the requirement in the production reality.

The present invention is achieved by the following technical solutions, the present invention includes following steps:

(1) on elliptical vibration luffing bar body orthogonal two sides, sticks piezoelectric ceramic piece;

(2) add 200 volts of sine voltages on these two piezoelectric ceramic pieces, these two piezoelectric ceramics take place flexible, the elliptical vibration luffing bar body vibration that bends like this;

(3) by elliptical vibration luffing bar, make the flexural vibrations of generation, further increase, reach major axis: 11 μ m, minor axis: 5 μ m, angle: 120 °, the elliptical vibration of resonant frequency: 18.6kHz;

(4) cutter is fixed on elliptical vibration luffing boom end, and it is maximum that elliptical vibration reaches at this place;

(5) after the flexural vibrations of level and vertical this both direction are synthetic, on cutting blade, can obtain the elliptical vibration track;

(6) elliptical vibration luffing bar body is fixed on the knife rest by the elliptical vibration node, the cutter that is fixed on elliptical vibration luffing boom end is so not only made elliptical vibration, but also carry out axially and the radial feed motion with slide plate, realize the ultrasonic elliptically vibrating machining.

Cutting blade of the present invention elliptical vibration maximal rate in the horizontal direction is during greater than cutting speed, separate between cutter and smear metal and the workpiece, usually will set processing conditions and satisfy this condition, therefore, the ultrasonic elliptically vibrating cutting is the interrupted cutting process of a kind of periodicity; After each cutting cycle had just begun, elliptical vibration cutter vibration velocity in vertical direction was less than the smear metal rate of outflow, and it is opposite that direction is flowed out in the frictional force direction between cutter rake face and the smear metal and smear metal, hinders smear metal and flow out; After this, elliptical vibration cutter vibration velocity in vertical direction increases gradually; The vibration velocity of this direction is during greater than the smear metal rate of outflow, frictional force direction counter-rotating between cutter rake face and the smear metal, different during with common cutting and ultrasonic wave straight-line oscillation cutting, at this moment the direction of frictional force is identical with smear metal outflow direction, promote smear metal to flow out, caused dorsad cutting force negative value occurs in a cutting cycle, making on average dorsad, cutting force reduces significantly, cause cutting precision and cutting processing system stability obviously to improve, can eliminate the flutter in the machining effectively, surface smoothness be improved significantly, can realize the workpiece precision cutting processing that rigidity is weak.

The present invention characterizes divergence type ultrasonic elliptically vibrating working angles by a positive negative pulse stuffing function:

$h\left(t\right)=\left\{\begin{array}{cc}1& (t_b+\mathrm{nT})\&le;t<(t_i+\mathrm{nT})\\ -1& (t_i+\mathrm{nT})\&le;t<(t_e+\mathrm{nT})\\ 0& (t_e+\mathrm{nT})\&le;t<(t_b+(n+1)T)\end{array}-\left(1\right)\right.$

In the formula:

t _b-in a vibrocutting cycle, cut the zero hour;

t _iCounter-rotating zero hour takes place in-frictional force direction in each cutting cycle between cutter rake face and the smear metal;

t _o--cutting is at the end carved in a vibrocutting cycle;

The T-Elliptical circular vibration cycle;

n＝0，1，2……。

When h (t)=1, identical when the frictional force direction between cutter rake face and the smear metal and common cutting and common supersonic vibration cutting, promptly to flow out direction opposite with smear metal, hinders smear metal and flow out; When h (t)=-1, the frictional force direction between cutter rake face and the smear metal is reversed, and is different during with common cutting and common supersonic vibration cutting, and promptly to flow out direction identical with smear metal, promotes smear metal to flow out; H (t)=0 o'clock, cutter separated with workpiece with smear metal, and cutter is in non-cutting state.

H (t) is pressed the Fourier series expansion,

$\begin{array}{c}h\left(t\right)=\frac{t_{c1}}{T}+\frac{2}{\mathrm{\&pi;}}\underset{n=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\frac{1}{n}\sin \left(\frac{t_{c1}n}{T}\mathrm{\&pi;}\right)\cos \left({\mathrm{n\&omega;}}_{u}t\right)\\ -\frac{t_{c2}}{T}-\frac{2}{\mathrm{\&pi;}}\underset{n=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\frac{1}{n}\sin \left(\frac{t_{c2}n}{T}\mathrm{\&pi;}\right)\cos \left({\mathrm{n\&omega;}}_{u}t\right)\end{array}---\left(2\right)$

In the formula: t _C1=t _i-t _b

t _c2＝t _e-t _i；

ω _u-2πf；

F-elliptical vibration frequency.

Stalling characteristic in the ultrasonic elliptically vibrating working angles and frictional direction reverse speed characterisstic will have significant effects to suppressing flutter.

The invention has the beneficial effects as follows: it is attached to ultrasonic elliptically vibrating on the cutting tool, the ultrasonic elliptically vibrating cutting working method is the same with ultrasonic wave straight-line oscillation cutting working method all to have stalling characteristic, different is that ultrasonic wave straight-line oscillation cutting working method only is that the cutter rake face separates with smear metal, and knife face is not separate with workpiece behind the cutter, but, the ultrasonic elliptically vibrating cutting is not only the cutter rake face and is separated with smear metal, and knife face also separates with workpiece behind the cutter, opened " cutting forbidden zone " so up hill and dale, can make cutting fluid enter cutting region, sufficient lubrication and cooling cutter cause cutter life to improve.In addition, the ultrasonic elliptically vibrating cutting working method also has another key property, be that frictional force direction between cutting tool rake face and the smear metal has reverse speed characterisstic, this causes radial cutting force negative value to occur in a cutting cycle, average radial cutting force is reduced significantly, and particularly the mean value of radial cutting force approaches 0.This obviously improves cutting processing system stability, can eliminate the flutter in the machining effectively, can realize the workpiece precision cutting processing that rigidity is weak.

The specific embodiment

Embodiment

Provide the workpiece material of machining: steel (45#), cutter material: carbide alloy.

The tool orthogonal rake of machining :-5 °, tool clearance: 12 °, tool cutting edge angle: 25 °, corner radius: 0.1mm.

Vibration condition of the present invention: track: oval (major axis: 11 μ m, minor axis: 5 μ m, angle: 120 °), resonant frequency: 18.6kHz.

(1) add sine voltage to two piezoelectric ceramic pieces on the luffing bar body, these two piezoelectric ceramics take place flexible, and cutter is elliptical vibration luffing boom end fixedly, and by elliptical vibration luffing bar, the cutter blade place reaches maximum elliptical vibration track.The setting cutting speed is 14.95m/min, cutting depth is 0.0375mm, when the amount of feeding is 0.025mm/rev, cutting experiment test and analysis result are: workpiece radial vibration displacement is not about 80 μ m when not adding the common cutting of ultrasonic elliptically vibrating, and after appending to ultrasonic elliptically vibrating on the cutting tool, the radial vibration displacement of workpiece becomes about 8 μ m at once, workpiece radial vibration displacement is about 1/10 of common cutting when being the elliptical vibration cutting, by actual observation and fft analysis, learn: flutter takes place during common cutting, surface of the work has tangible chatter mark, but behind affix elliptical vibration on the cutter, flutter disappears immediately, and surface of the work does not have chatter mark, and the surface light knot significantly improves.

(2) equally on luffing bar body two piezoelectric ceramic pieces add sine voltage, these two piezoelectric ceramics take place flexible, cutter is elliptical vibration luffing boom end fixedly, by elliptical vibration luffing bar, the cutter blade place reaches the elliptical vibration track of maximum.The setting cutting speed is 20.25m/min, cutting depth is 0.0125mm, when the amount of feeding is 0.025mm/rev, machining experiment test and analysis result are: workpiece radial vibration displacement is not about 110 μ m when not adding the common cutting of ultrasonic elliptically vibrating, and after appending to ultrasonic elliptically vibrating on the cutting tool, the radial vibration displacement of workpiece becomes about 10 μ m at once, workpiece radial vibration displacement is about 1/11 of common cutting when being the elliptical vibration cutting, by actual observation and fft analysis, learn: flutter takes place during common cutting, but behind affix elliptical vibration on the cutter, flutter disappears immediately.

(3) two piezoelectric ceramic pieces add sine voltage on luffing bar body, these two piezoelectric ceramics take place flexible, cutter is elliptical vibration luffing boom end fixedly, by elliptical vibration luffing bar, the cutter blade place reaches maximum elliptical vibration track. and the setting cutting speed is 20.25m/min, cutting depth is 0.0375mm, when the amount of feeding is 0.025mm/rev, machining experiment test and analysis result are: workpiece radial vibration displacement is not about 105 μ m when not adding the common cutting of ultrasonic elliptically vibrating, and after appending to ultrasonic elliptically vibrating on the cutting tool, the radial vibration displacement of workpiece becomes about 9 μ m at once, workpiece radial vibration displacement is about 1/12 of common cutting when being the elliptical vibration cutting, by actual observation and fft analysis, learn: flutter takes place during common cutting, and surface of the work has tangible chatter mark, but behind affix elliptical vibration on the cutter, flutter disappears immediately, and the surface of the work chatter mark also disappears, and the surface light knot significantly improves.

Above result shows: the method for elliptical ultrasonic vibration inhibition of the present invention significantly reduces workpiece radial vibration displacement, and its value size is about 1/11 of common cutting.By actual observation and fft analysis, learn: flutter takes place during common cutting, surface of the work has tangible chatter mark, but behind affix elliptical vibration on the cutter, flutter disappears immediately, the surface of the work chatter mark also disappears, and the surface light knot significantly improves, and shows that the elliptical vibration cutting energy suppresses the flutter that produces in the machining effectively.

Claims (4)

1. the method for an elliptical ultrasonic vibration inhibition is characterized in that, concrete steps are as follows:

(1) on elliptical vibration luffing bar body orthogonal two sides, sticks piezoelectric ceramic piece;

(2) add sine voltage on these two piezoelectric ceramic pieces, these two piezoelectric ceramics take place flexible, the elliptical vibration luffing bar body vibration that bends like this;

(3) by elliptical vibration luffing bar, the flexural vibrations of generation are further increased;

(4) cutter is fixed on elliptical vibration luffing boom end, and it is maximum that elliptical vibration reaches at this place;

(5) after the flexural vibrations of level and vertical this both direction are synthetic, on cutting blade, obtain the elliptical vibration track;

(6) elliptical vibration luffing bar body is fixed on the knife rest by the elliptical vibration node.

2. the method for elliptical ultrasonic vibration inhibition according to claim 1, it is characterized in that, blade elliptical vibration maximal rate in the horizontal direction is during greater than cutting speed, separate between cutter and smear metal and the workpiece, after each cutting cycle has just begun, elliptical vibration cutter vibration velocity in vertical direction is less than the smear metal rate of outflow, and it is opposite that direction is flowed out in the frictional force direction between cutter rake face and the smear metal and smear metal; The vibration velocity of this direction is during greater than the smear metal rate of outflow, and the frictional force direction counter-rotating between cutter rake face and the smear metal promotes smear metal to flow out.

3. the method for elliptical ultrasonic vibration inhibition according to claim 1 is characterized in that, described sine voltage is 200 volts.

4. the method for elliptical ultrasonic vibration inhibition according to claim 1 is characterized in that, the flexural vibrations in the described step (3) are meant: major axis is 11 μ m, and minor axis is 5 μ m, and angle is 120 °, and resonant frequency is the elliptical vibration track of 18.6kHz.