CN100585522C - Ultra-precise turning method with diamond knife tool hook angle compensation - Google Patents

Abstract

The invention belongs to ultra precise machining, complex parts fabrication technique field, relates to a ultra precise turning process with diamond knife tool anterior angle compensating for three axis diamond ultra precise machine tool. The method adapts above tool orthogonal rake compensating to search lathe coordinate of knife for many coordinate on the mould, and generates machining paths according to certain paths to realize the machining for surface model tool orthogonal rake compensating. In the paths generation method, the knife with anterior angle is compensated on the anterior angle to realize tool bit accurate control in case of machining brittleness material and ultra precise turning with high shape accuracy.

Description

A kind of ultra-precise turning method that has diamond knife tool hook angle compensation

Technical field

The invention belongs to ultraprecise processing, complex parts manufacturing technology field, relate to a kind of ultra-precise turning method.

Background technology

At present, hard brittle material (as silicon, BK7 glass, ZnS and ZnSe etc.) is applied in the application of ultraprecise product more and more.No matter be in micro-optic consumption markets such as mobile phone cam, DVD reading head, microminaturization camera lenss, still new type healths such as the endoscope in biologic medical field, chip lab, Wicresoft's analysis of biological information are examined survey means aspect, and the hard brittle material product all begins to form the increasing market demand.

But hard brittle material is because of characteristic such as the height that enbrittles, fracture toughness be low, and processibility is relatively poor, just produces rupture failure when material bears the cutting force of overload, has a strong impact on the crudy of workpiece.Technologies such as grinding, grinding, polishing are mainly adopted in processing to hard brittle material, and production efficiency is lower.Development along with Ultraprecision Machining, in the last few years, directly become possibility by the diamond cutting brittle material surface, obtain nanoscale roughness surface by ultra precision cutting to the hard brittle material plastic region, that has greatly improved working (machining) efficiency and process can be handling, is easy to simultaneously hard brittle material is carried out complex-curved processing.

Prove that by a large amount of scientific experiments in the hard brittle material working angles, material is removed by the plastic yield mode of the compressive stress generation of point of a knife front end, the generation of processing the plastic yield zone by the lathe tool that uses different anterior angles is highly profitable.Therefore, in order to improve the machining shape precision of this mode, be necessary the mismachining tolerance that tool orthogonal rake in the processing causes is carried out reasonable compensation.

Summary of the invention

The objective of the invention is at three (X, Z, C) diamond super precision turning modes, the compensation method of Design and Machining tool orthogonal rake, adopt the method for turning with hook angle compensation provided by the invention, can realize the ultraprecise processing of complex-curved higher form accuracy.

The present invention adopts following technical scheme for this reason:

A kind of ultra-precise turning method that has diamond knife tool hook angle compensation, be used on three diamond super precision lathes, the main shaft of described lathe can be done gyration and along X-motion, be equipped with on the main shaft its rotational angle is controlled or fed back the scrambler that it is rotated along the C axle, diamond cutter is Z to motion, and this method comprises the following steps:

(1) workpiece machining surface is set up FREEFORM SURFACE MODEL;

(2) with the coordinate p of processing stand on the FREEFORM SURFACE MODEL ₀(x ₀, y ₀, z ₀) change into the coordinate under the lathe coordinate system

And find the solution the normal vector of this point by the vector expression of parametric equation $\stackrel{\→}{n}=(a_0,b_0,c_0);$

(3) be the motion simulation of process the forever vertical xoy plane of edged surface and around the motion of lathe z axle before the cutter zero, and, find the solution processing p according to this motion model ₀(x ₀, y ₀, z ₀) when putting, the normal vector of face of tool

(4) with the normal vector of processing stand $\stackrel{\→}{n}=(a_0,b_0,c_0)$ Project on the face of tool, and carry out cutter radius compensation, obtain the o (x of face of tool center of arc along projection vector _t, y _t, z _t) the model coordinate;

(5) by the normal vector of face of tool

Ask for the o ' of face of tool center of arc sensing point of a knife p ₁Unit vector

And, try to achieve point of a knife p according to the distance of 2 of this vector sums ₁The model coordinate;

(6) point of a knife p ₁O (the x of edged surface center of arc before pointing to zero _t, y _t, z _t) vector

Be parallel to the z axle, and length is r ₀, can find the solution o (x _t, y _t, z _t) the point model coordinate;

(7) the model coordinate o (x of edged surface center of arc before the general zero _t, y _t, z _t) transfer the coordinate under the lathe coordinate system to

(8) machine coordinates of locating according to face of tool center of arc through hook angle compensation

Travel through the processing stand on the free form surface, obtain the face of tool center of arc coordinate of each point correspondence, generate machining path;

(9) according to the machining path that is generated, the rotational angle of control machine tool chief axis and the amount of feeding, the cutting-in of cutter are carried out turning processing.

The above-mentioned ultra-precise turning method that has diamond knife tool hook angle compensation is characterized in that, in the step (3) to processing p ₀(x ₀, y ₀, z ₀) when putting, the normal vector of face of tool

Solution procedure can carry out according to following steps:

(a) face of tool can be regarded before zero edged surface as and walks around the point of a knife axis rotation parallel with the x axle and form anterior angle α ₀, try to achieve the normal vector of point of a knife face of tool when being in x axle forward position according to this

(b) p on the processing model ₀(x ₀, y ₀, z ₀) when putting, the normal vector of face of tool Be by vector

Rotate around the z axle

Angle gets, thereby tries to achieve the normal vector of face of tool

The present invention has following significant advantage:

When the cutter rake face had non-zero degree hook, along with the variation of the contact point of the cutting edge of cutter and work piece, the curvature at contact point place was also changing.This variable quantity has a strong impact on the form accuracy of surface to be machined.For example, adopt the cutter of-25 ° of anterior angles,, will bring surface shape error, thereby make processed non-spherical lens can not satisfy application requirements greater than 3 μ m as no tool orthogonal rake compensation at the non-spherical lens of processing one diameter 10mm.And after adopting the method for turning with tool orthogonal rake compensation of the present invention's proposition, then surface shape error has dropped in the 0.1 μ m at an easy rate, has greatly improved the quality and the practicality of optics processing.

Description of drawings

Fig. 1: tool orthogonal rake compensation model.

Embodiment

The cutter model of consideration anterior angle as shown in Figure 1.Among the figure, 1 is the face of tool, and 2 is zero preceding edged surface.The corner radius of face of tool is r ₀Set up tool coordinate system o ' x ' y ' z ' shown in Figure 1 with the circular arc circle centre position of face of tool, the angle of face of tool and z axle negative sense is anterior angle α ₀, current face of tool can be regarded zero preceding edged surface as and walk around the point of a knife axis rotation formation parallel with the x axle.The normal vector of face of tool is,

${\stackrel{\→}{n}}_t=(0,\cos {\mathrm{\α}}_0,\sin {\mathrm{\α}}_0)---\left(1\right)$

The general expression formula of supposing any processing curve be z=f (x, y).By three diamond super precision turning modes as can be known, any point p on to curved surface ₀(x ₀, y ₀, z ₀) add man-hour, do not consider that the tool orthogonal rake compensation adds man-hour, the location point of cutter is in face of tool center of arc

And the tool position of actual Machine-Tool Control is that face of tool center of arc is corresponding on the zero preceding edged surface

These 2 for the bigger deviation of big negative rake cutter processing existence.In the actual processing, try to achieve the compensation that coordinate that o orders has just realized adding tool setting in man-hour tool anterior angle.O (x _t, y _t, z _t) be

Coordinate in the corresponding model coordinate systems, both can be changed mutually by the polar coordinates formula,

By formula (2) also can computation model on p ₀(x ₀, y ₀, z ₀) coordinate under lathe coordinate system

The normal vector of current point $\stackrel{\→}{n}=(a_0,b_0,c_0)$ Find the solution below can being undertaken by the vector mode of surface parameter equation: the expression formula by processing curve can get its parametric description formula

$\left\{\begin{array}{c}x=x(u,v)\\ y=y(u,v)\\ z=z(u,v)\end{array}\right.---\left(3\right)$

Its vector mode is: $\stackrel{\→}{r}=\stackrel{\→}{r}(u,v)=x(u,v)\stackrel{\→}{i}+y(u,v)\stackrel{\→}{j}+z(u,v)\stackrel{\→}{k},$ Following two vectors that the section of this point is passed through: ${\stackrel{\→}{r}}_u=\frac{\∂\stackrel{\→}{r}}{\∂u};$ ${\stackrel{\→}{r}}_v=\frac{\∂\stackrel{\→}{r}}{\∂v},$ Then the normal vector of certain point can be found the solution by two vector cross product on the curved surface $\stackrel{\→}{n}={\stackrel{\→}{r}}_u\×{\stackrel{\→}{r}}_v;$

2. consider the relative motion of cutter and workpiece, it is motionless suppose to add the man-hour workpiece, so cutter is the relative motion model of actual working motion around the motion of lathe z axle, and edged surface vertical xoy plane forever before zero.P on the processing model ₀(x ₀, y ₀, z ₀) when putting, the normal vector of face of tool

Can regard vector as

Rotate around the z axle

Angle, promptly

Simultaneously, obtain the o ' of face of tool center of arc sensing point of a knife p ₁Vector of unit length

3. vectorial

It is the normal vector of model $\stackrel{\→}{n}=(a_0,b_0,c_0)$ Projection on the face of tool, and length is r ₀, can get by the vector projection formula and to its unitization,

By the vector subtraction computing, can get the model coordinate of o '

$\left\{\begin{array}{c}{x}_t^{\′}=x_0+r_0{a}_p\\ y_t^{\′}=y_0+r_0{b}_p\\ z_t^{\′}=z_0+r_0{c}_p\end{array}\right.---\left(7\right)$

4. by vector of unit length

And the model coordinate of o ' can be tried to achieve the p of point of a knife place ₁The model coordinate,

Therefore

5. because of the forever vertical xoy plane of zero preceding edged surface, so vector

Be parallel to the z axle, and length is r ₀, promptly $\stackrel{\→}{p_{1}o}=(\mathrm{0,0},r_0),$ Therefore:

$o(x_t,y_t,z_t)=\stackrel{\→}{p_{1}o}+p_1(x_1,y_1,z_1)$

Utilize formula (2) that the model coordinate is transferred to machine coordinates

Realized compensation to tool orthogonal rake.

In reality processing, adopt the method for above tool orthogonal rake compensation, the enough points of model epipodium are asked the lathe coordinate points of cutter; And, realize processing to the compensation of surface model tool orthogonal rake according to certain path generation machining path.

This invention is suitable for three diamond super precision lathes and adds man-hour, and the cutter with anterior angle is carried out hook angle compensation, and the cutter when realizing the work brittleness material is accurately controlled, thereby realizes the high ultra-precise cutting of form accuracy.Based on the thinking and the analytical approach of hook angle compensation, also can be applied to other processing modes in conjunction with concrete process principle, realize high-precision ultraprecise processing.

Claims (2)

1. ultra-precise turning method that has diamond knife tool hook angle compensation, be used on three diamond super precision lathes, the main shaft of described lathe can be done gyration and along X-motion, be equipped with on the main shaft its rotational angle is controlled or fed back the scrambler that it is rotated along the C axle, diamond cutter is Z to motion, and this method comprises the following steps:

(1) workpiece machining surface is set up FREEFORM SURFACE MODEL;

(2) with the coordinate p of processing stand on the FREEFORM SURFACE MODEL ₀(x ₀, y ₀, z ₀) change into the coordinate under the lathe coordinate system

And find the solution the normal vector of this point by the vector expression of parametric equation $\stackrel{\→}{n}=(a_0,b_0,c_0);$

(3) be the motion simulation of process the forever vertical xoy plane of edged surface and around the motion of lathe z axle before the cutter zero, and, find the solution processing p according to this motion model ₀(x ₀, y ₀, z ₀) when putting, the normal vector of face of tool

(4) with the normal vector of processing stand $\stackrel{\→}{n}=(a_0,b_0,c_0)$ Project on the face of tool, and carry out cutter radius compensation along projection vector, obtain the o ' of face of tool center of arc (x ' _t, y ' _t, z ' _t) the model coordinate;

(5) by the normal vector of face of tool

Ask for the o ' of face of tool center of arc (x ' _t, y ' _t, z ' _t) sensing point of a knife p ₁Unit vector And, try to achieve point of a knife p according to the distance of 2 of this vector sums ₁The model coordinate;

(6) point of a knife p ₁O (the x of edged surface center of arc before pointing to zero _t, y _t, z _t) vector Be parallel to the z axle, and length is r ₀, find the solution o (x _t, y _t, z _t) the point model coordinate;

(7) will the zero preceding o (x of edged surface center of arc _t, y _t, z _t) the model coordinate transfer coordinate under the lathe coordinate system to

(8) machine coordinates of locating according to face of tool center of arc through hook angle compensation

Travel through the processing stand on the free form surface, obtain the face of tool center of arc coordinate of each point correspondence, generate machining path;

(9) according to the machining path that is generated, the rotational angle of control machine tool chief axis and the amount of feeding, the cutting-in of cutter are carried out turning processing.

2. the ultra-precise turning method that has diamond knife tool hook angle compensation according to claim 1 is characterized in that, in the described step (3) to processing p ₀(x ₀, y ₀, z ₀) when putting, the normal vector of face of tool

Solution procedure may further comprise the steps:

(a) face of tool can be regarded before zero edged surface as and walks around the point of a knife axis rotation parallel with the x axle and form anterior angle α ₀, try to achieve the normal vector of point of a knife face of tool when being in x axle forward position according to this

(b) p on the processing model ₀(x ₀, y ₀, z ₀) when putting, the normal vector of face of tool

Be by vector

Rotate around the z axle Angle gets, thereby tries to achieve the normal vector of face of tool

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