CN101169647A - Mini line segment curve five-axis linkage machining speed smoothing method - Google Patents

Abstract

The invention discloses a forsimultaneous five-axis movement processing speed smoothing method of a small curve, which relates to the computer numerical control processing technical field. The forsimultaneous five-axis movement processing speed smoothing method, through adjusting the feed rates of some interpolation cycles V i < j >, adjusts the feed rate which is greater than Va of an interpolation cycle to a V a adjustment method, so that t is equal to (Na + nc + nd +1) T, thereby ensuring that the whole interpolation process meets the characteristic of acceleration and deceleration of machine tools, while the total time of the interpolation is also completed in an integral cycle; by selecting a set of fixed-feed rate, the length of a straight-line in the procedures is segmented under the speed of the group, to achieve the interpolation to five forsimultaneous axis, thereby meeting the accuracy requirement when the speed smoothing. The forsimultaneous five-axis movement processing speed smoothing method of the invention has the characteristics of improving the processing speed, meeting the acceleration and deceleration of the machine tools, and avoiding the impact for the machine tools.

Description

The five-axis linkage machining speed smoothing method of mini line segment curve

Technical field

The present invention relates to the computer numerical control process technology, particularly relate to a kind of five-axis linkage machining speed smoothing method technology that is used for mini line segment curve of computer numerical control (CNC).

Background technology

The cutter path of five-axle linkage generally is made up of the cutter location of series of discrete, and each cutter location comprises three translation coordinate X, Y, and Z reaches two rotational coordinatess such as B, and C, machine tool controller are then according to cutter location, to each control that links.Will be to obtaining desirable suface processing quality and process velocity faster, the speed of feed in the time of should as far as possible making interpolation as far as possible steadily reaches seamlessly transitting of speed between program segment.And traditional method is when carrying out interpolation to certain section program segment, do not take into full account the information of down-stream section, and each program segment is carried out independent control, will cause the speed of feed of program segment turning point to fall very lowly like this, even be zero, start and stop that motor is frequent and acceleration and deceleration make speed of feed steady inadequately, influence suface processing quality, simultaneously, process velocity also is difficult to improve.At present, addressing this problem mainly is rate smoothing optimization process method.This method takes into full account each acceleration and deceleration ability of lathe, and the machining code to continuous multi-stage carries out pre-service, analyze its geometrical property, comprise the corner that adjacent programs is intersegmental, the length of single hop program segment on this basis, obtains the interior maximum speed of feed of program segment and maximum to speed, simultaneously the linking speed between program segment is optimized, makes speed of feed level and smooth as far as possible.In patent of having delivered and document, after rate smoothing is optimized, a spot speed of a program segment and terminal velocity no longer are zero, so often can not program segment be segmented in an integer interpolation cycle by the speed of feed of expectation, can cause the too fast of speed of feed rising and decline like this, the acceleration and deceleration ability that has exceeded lathe causes that lathe impacts.For avoiding this kind situation, there is document to adopt speed controlling after interpolating to solve this problem, but can causes certain site error, perhaps, fall linking speed very lowly in order to satisfy positional precision, influenced process velocity so again.

Summary of the invention

At the defective that exists in the above-mentioned prior art, technical matters to be solved by this invention provides and a kind ofly can improve process velocity, satisfies the acceleration and deceleration characteristic of lathe, can avoid the five-axis linkage machining speed smoothing method of the mini line segment curve that lathe impacts.

In order to solve the problems of the technologies described above, the five-axis linkage machining speed smoothing method of a kind of mini line segment curve provided by the present invention is characterized in that, on the basis of satisfying the lathe acceleration and deceleration characteristic, one section program segment is carried out interpolation, promptly selects one group of V _{I Λ} ^j, make

$\underset{i=1}{\overset{n_i}{\mathrm{\&Sigma;}}}{V_i^j}_{\mathrm{\&Lambda;}}T={\mathrm{\&Delta;}}_{\mathrm{i\&Lambda;}}---\left(1\right)$

Following formula can be write as:

$\underset{i=1}{\overset{n_i}{\mathrm{\&Sigma;}}}{V}_i^{j}T=l_i---\left(2\right)$

Promptly only need to select one group of translation speed of feed, the straight length in the program segment is cut apart according to this group speed, just can realize interpolation five universal driving shafts;

For (2) formula, when a spot speed is non-vanishing, promptly ${\mathrm{<figure-callout\; id="1"\; label="V\; i"\; filenames="A20061011766000101.png,A20061011766000102.png"\; state="\{\{state\}\}">V</figure-callout>}}_i^{}>0$ The time, must use restraint just so-called section first constraint condition to the first speed of section; Method of adjustment one is by adjusting the speed of feed V of some interpolation cycle _i ^j, those speed of feed greater than V _aInterpolation cycle, be adjusted into V _a, that is:

$V_i^j{=V}_a,$ When $V_i^j>V_a$

By adjusting the V of described interpolation cycle _i ^j, (n before making _a+ n _c+ n _d) length of individual cycle interpolation gained diminishes, this length that reduces is designated as S _aAs long as find suitable V _a, make

S _a(V _a)＝S _e

S _e＝V _i+1(1-f)T

Just can make t=(na+nc+nd+1) T; Thereby make whole interpolation process promptly satisfy the acceleration and deceleration characteristic of lathe, also finish in the cycle interpolation T.T. simultaneously at integer.

But when making V _a=V _i, suppose V _i＜V _I+1, still have:

S _a(V _a)＜S _e

S _e＝V _i(1-f)T

Can adjust V by following method of adjustment two _i ^j:

$V_i^j=V_i,$ As j＜n _c'

$V_i^j=V_a,$ And V _i-a _ImT＜V _a≤ V _i, work as j=n _c'

$V_i^j=V_a-(j-n^{\&prime;})a_{\mathrm{im}}T,$ As j＞n _c'

Make

S _a(V _a)＝S _e

S _e＝[Va-(n-n _c′)a _imT](1-f)T

As long as satisfy S by two kinds of above-mentioned methods of adjustment _Am〉=S _e(S _AmFor for given l _i, V _i, V _I+1, obtainable S _aHigher limit), the accuracy requirement in the time of just can satisfying rate smoothing.

Further, described constraint condition comprises:

1) physical constraint of each axis drive motor of lathe comprises the constraint of power, speed and acceleration.The present invention characterizes this constraint by peak power, maximal rate and the peak acceleration of specifying motor;

2) geometrical constraint of movement locus comprises the maximum speed of feed constraint to adjacent straight intersection point of line segments place of the position vector of adjacent cutter location and direction vector.This constraint has guaranteed each straight-line segment when starting point and terminal velocity are non-vanishing, the seamlessly transitting of servomotor acceleration.

Utilize the five-axis linkage machining speed smoothing method of mini line segment curve provided by the invention, owing to adopt two kinds of above-mentioned methods of adjustment, accuracy requirement when satisfying rate smoothing, thereby make whole interpolation process promptly satisfy the acceleration and deceleration characteristic of lathe, also finish in the cycle interpolation T.T. simultaneously, avoided the lathe impact at integer.

Description of drawings

Fig. 1 is the principle schematic of method of adjustment one of the five-axis linkage machining speed smoothing method of embodiment of the invention mini line segment curve;

Fig. 2 is the principle schematic of method of adjustment two of the five-axis linkage machining speed smoothing method of embodiment of the invention mini line segment curve.

Embodiment

Below in conjunction with description of drawings embodiments of the invention are described in further detail, but present embodiment is not limited to the present invention, every employing analog structure of the present invention and similar variation thereof all should be listed protection scope of the present invention in.

The five-axis linkage machining speed smoothing method of a kind of mini line segment curve that the embodiment of the invention provided has proposed the constraint condition of following two aspects at the design feature of five-axis linkage machine tools:

1) physical constraint of each axis drive motor of lathe comprises the constraint of power, speed and acceleration.If the inertia of lathe, cutting force and friction force have exceeded these constraints, and motor properties will descend.The present invention characterizes this constraint by peak power, maximal rate and the peak acceleration of specifying motor;

2) geometrical constraint of movement locus comprises the maximum speed of feed constraint to adjacent straight intersection point of line segments place of the position vector of adjacent cutter location and direction vector.This constraint has guaranteed each straight-line segment when starting point and terminal velocity are non-vanishing, the seamlessly transitting of servomotor acceleration.

More than having set up, on the basis of two classes constraint, the present invention proposes five little straight-line segment speed-optimization algorithms, under the prerequisite that satisfies each spindle motor constraint, realized that the speed of feed between straight-line segment is connected based on prediction.Experimental result has shown the validity of algorithm of the present invention.It below is main implementation method.

On the basis of satisfying the lathe acceleration and deceleration characteristic, one section program segment is carried out interpolation, to find such one group of V in fact exactly _{I Λ} ^j, make

$\underset{i=1}{\overset{n_i}{\mathrm{\&Sigma;}}}{V_i^j}_{\mathrm{\&Lambda;}}T={\mathrm{\&Delta;}}_{\mathrm{i\&Lambda;}}---\left(1\right)$

Following formula can be write as:

$\underset{i=1}{\overset{n_i}{\mathrm{\&Sigma;}}}{V}_i^{j}T=l_i---\left(2\right)$

That is to say and only need find one group of translation speed of feed, the straight length in the program segment is cut apart according to this group speed, just can realize interpolation five universal driving shafts.

For (2) formula, when the spot speed that rises of program segment is zero, promptly $V_i^1=0$ The time, one group of such V _i ^jCertainly can find, that is to say, program segment certainly can be at (the n of integer exactly _i) finish interpolation in the cycle.But, when a spot speed is non-vanishing, promptly $V_i^1>0$ The time (and this adopts the situation behind the rate smoothing just), according to the interpolating method of routine, just often can not realize, therefore, must use restraint just so-called section first constraint condition to the first speed of section.As shown in Figure 1, V _iFor program segment plays spot speed, i.e. the speed of first interpolation cycle, V _I+1Be terminal velocity, i.e. the speed of last interpolation cycle, Vc is the order speed of feed of this program segment, the just speed of constant-speed section.Whole interpolation lasts t=(na+nc+nd+f) T, and fT is the part of last not enough one-period, wherein 0≤f＜1.As seen, in the end an interpolation cycle has a less surplus, and its length is S _f=V _I+1FT is if will arrive suitable speed of feed, i.e. V _I+1, it is with regard to not enough one-period, i.e. fT, if will cover in one-period, then speed of feed is V ' _I+1=fV _I+1, when f hour, this speed of feed exceeds the scope of permission, causes the impact of lathe.In fact, can change conventional interpolating method, make whole interpolation process promptly satisfy the acceleration and deceleration characteristic of lathe, also finish in the cycle interpolation T.T. simultaneously, i.e. t=(na+nc+nd+1) T at integer.As shown in Figure 1, by adjusting the speed of feed V of some interpolation cycle _i ^j, just those speed of feed greater than V _aInterpolation cycle, be adjusted into V _a, that is:

$V_i^j=V_a,$ When $V_i^j>V_a$

Like this, by adjusting the V in these cycles _i ^j, (n before making _a+ n _c+ n _d) length of individual cycle interpolation gained can diminish, this length that reduces is designated as S _aClearly, as long as find suitable V _a, make

S _a(V _a)＝S _e

S _e＝V _i+1(1-f)T

Just can be so that t=(na+nc+nd+1) is T.

But when making V _a=V _i, as shown in Figure 2, suppose V _i＜V _I+1, still have:

S _a(V _a)＜S _e

S _e＝V _i(1-f)T

At this moment, adjust V by the following method _i ^j:

$V_i^j=V_i,$ As j＜n _c'

$V_i^j=V_a,$ And V _i-a _ImT＜V _a≤ V _i, work as j=n _c'

$V_i^j=V_a-(j-n^{\&prime;})a_{\mathrm{im}}T,$ As j＞n _c'

Make

S _a(V _a)＝S _e

S _e＝[Va-(n-n _c′)a _imT](1-f)T

From above-described two kinds of methods of adjustment as can be known, for given l _i, V _i, V _I+1, obtainable S _aHave higher limit, be designated as S _AmWork as S _Am＜S _eThe time, by above-mentioned two kinds of methods of adjustment, can't meet the demands.

Below, we will study and how to guarantee:

S _am≥S _e(3)

As long as satisfy (3) accuracy requirement in the time of just can satisfying rate smoothing by two kinds of above-mentioned methods of adjustment.

Claims (4)

1. the five-axis linkage machining speed smoothing method of a mini line segment curve is characterized in that, on the basis of satisfying the lathe acceleration and deceleration characteristic, one section program segment is carried out interpolation, promptly selects one group of V _{I Λ} ^j, make

$\underset{i=1}{\overset{n_i}{\mathrm{\&Sigma;}}}{V}_{\mathrm{i\&Lambda;}}^{j}T={\mathrm{\&Delta;}}_{\mathrm{i\&Lambda;}}---\left(1\right)$

Following formula can be write as:

$\underset{i=1}{\overset{n_i}{\mathrm{\&Sigma;}}}{V}_i^{j}T=l_i---\left(2\right)$

Promptly only need to select one group of translation speed of feed, the straight length in the program segment is cut apart according to this group speed, just can realize interpolation five universal driving shafts;

For (2) formula, V _i ¹, must use restraint just so-called section first constraint condition at＞0 o'clock to the first speed of section;

By adjusting the speed of feed V of some interpolation cycle _i ^j, those speed of feed greater than V _aInterpolation cycle, be adjusted into V _a, that is:

$V_i^j=V_a,$ When $V_i^j>V_a$

By adjusting the V of described interpolation cycle _i ^j, (n before making _a+ n _c+ n _d) length of individual cycle interpolation gained diminishes, this length that reduces is designated as S _aAs long as find suitable V _a, make

S _a(V _a)＝S _e

S _e＝V _i+1(1-f)T

Just can make t=(na+nc+nd+1) T; Thereby make whole interpolation process promptly satisfy the acceleration and deceleration characteristic of lathe, also finish in the cycle interpolation T.T. simultaneously at integer.

2. five-axis linkage machining speed smoothing method according to claim 1 is characterized in that, described constraint condition comprises:

1) physical constraint of each axis drive motor of lathe comprises the constraint of power, speed and acceleration;

2) geometrical constraint of movement locus comprises the maximum speed of feed constraint to adjacent straight intersection point of line segments place of the position vector of adjacent cutter location and direction vector.

3. the five-axis linkage machining speed smoothing method of a mini line segment curve is characterized in that, on the basis of satisfying the lathe acceleration and deceleration characteristic, one section program segment is carried out interpolation, promptly selects one group of V _{I Λ} ^j, make

$\underset{i=1}{\overset{n_i}{\mathrm{\&Sigma;}}}{V}_{\mathrm{i\&Lambda;}}^{j}T={\mathrm{\&Delta;}}_{\mathrm{i\&Lambda;}}---\left(1\right)$

Following formula can be write as:

$\underset{i=1}{\overset{n_i}{\mathrm{\&Sigma;}}}{V}_i^{j}T=l_i---\left(2\right)$

Promptly only need to select one group of translation speed of feed, the straight length in the program segment is cut apart according to this group speed, just can realize interpolation five universal driving shafts;

When making V _a=V _i, suppose V _i＜V _I+1, adjust V by the following method _i ^j:

$V_i^j=V_i,$ As j＜n _c'

$V_i^j=V_a,$ And V _i-a _ImT＜V _a≤ V _i, work as j=n _c'

$V_i^j=V_a-(j-n^{\&prime;})a_{\mathrm{im}}T,$ As j＞n _c'

Make

S _a(V _a)＝S _e

S _e＝[Va-(n-n _c′)a _imT](1-f)T；

As long as satisfy S by above-mentioned method of adjustment _Am〉=S _eAccuracy requirement in the time of just satisfying rate smoothing.

4. five-axis linkage machining speed smoothing method according to claim 3 is characterized in that, the constraint condition of described method of adjustment comprises:

1) physical constraint of each axis drive motor of lathe comprises the constraint of power, speed and acceleration;

2) geometrical constraint of movement locus comprises the maximum speed of feed constraint to adjacent straight intersection point of line segments place of the position vector of adjacent cutter location and direction vector.

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