CN1270870C - Cam machining process - Google Patents

Abstract

The present invention discloses a numerical control method for machining cams. According to the method of the present invention, a coordinate array which presents a cam design curve is firstly obtained on the basis of the roller measurement method; the coordinate value of a corresponding point in the rotation center of a circular cutting tool is calculated by using the geometric method according to the coordinate values of a plurality of adjacent points on the cam design curve, and the process is repeated so a to obtain a relative motion curve of the rotation center of the cutting tool corresponding to the whole design curve; thereby, the cam and the cutting tool move relatively according to the relative motion curve so as to machine cams on cam machining equipment.

Description

The processing method of cam

Technical field

The present invention relates to a kind of processing method of cam, specifically, relate to a kind of total control processing method of plane cam of dynamo-electric combination.

Background technology

The design data of cam can draw based on three kinds of measuring methods, and these three kinds of methods are edge of a knife mensuration, flat mensuration and roller mensuration.Except that the measurement data based on edge of a knife mensuration, the design data that other two kinds of mensurations draw is not the TP data of cam, so can't directly process with these design datas.

In the prior art,, cam is processed according to cam design The data pattern method for cam based on above-mentioned three kinds of mensurations design.Adopt pattern method machining cam, needing to make a mold earlier is pattern, leans on out satisfactory suitable workpiece with pattern again.

The shortcoming of pattern processing method is, machining accuracy is subjected to the restriction of the precision of pattern own, and pattern itself is wearing and tearing constantly, and the machine error of the cam that processes like this can be increasing.Usually, the design data of workpiece is called profile errors with the difference of the measured data of the product that processes, and it is adjacent poor that the difference of adjacent 2 profile errors value is called.Usually the adjacent difference of pattern method is 30 to 50 microns.

Cam is processed, need be determined the cutting position of milling cutter or emery wheel, just feed the position of axle according to the curve form of final cam.A key problem of numerical control method machining cam promptly is to determine corresponding to the milling of complicated cam curved surface or the position of grinding and feeding axle.

Summary of the invention

The present invention aims to provide a kind of method of total control and comes machining cam, it has saved the process of making pattern, as long as there are the cam design data just can process cam, mismachining tolerance only is subjected to the influence of factors such as machining equipment and mechanical rigid, driving error, control accuracy, and adjacent difference generally only is 1 to 3 micron.

To achieve these goals,, provide a kind of numerical-control processing method of cam, comprised the steps: according to one aspect of the invention

(1) obtains coordinate array based on the sign cam design curve of roller mensuration;

(2) extrapolate the coordinate figure of circular cutting tool pivot with respect to a respective point of the cam rotating shaft heart according to the coordinate figure of three consecutive points on the cam design curve with geometric method, specific practice is:

Make to be positioned in above-mentioned adjacent 3 the line in 2 in the outside, point in the middle of being positioned at from above-mentioned adjacent 3 is outwards made the vertical line perpendicular to above-mentioned line, the stretch out distance of the difference that equals tool radius and radius of roller of the point that intersects from this vertical line and design curve, the coordinate of that obtains are the coordinate figure corresponding to a respective point of the cutting tool pivot of the intermediate point in the above adjacent 3 of the design curves;

(3) process of repetition (2) obtains the relative motion curve corresponding to the cutting tool pivot of whole design curve;

(4) making cam and cutting tool produce relative motion according to above-mentioned relative motion curve processes cam on the cam process equipment.

According to a further aspect of the invention, provide a kind of numerical-control processing method of cam, comprised the steps:

(1) obtains coordinate array based on the sign cam design curve of roller mensuration;

(2) be that the coordinate figure of the consecutive points of n is extrapolated the coordinate figure of circular cutting tool pivot with respect to a respective point of the cam rotating shaft heart with geometric method according to the number more than three on the cam design curve, method is for determining an intermediate computations point on the described relative motion curve with per three adjacent points, can obtain n-2 intermediate computations point corresponding to a maximal end point on the described relative motion curve, according to importance this n-2 intermediate computations point applied weight, locus to this n-2 intermediate computations point is weighted on average then, obtain corresponding to the maximal end point on the relative motion curve of this n on the design curve point

Per three the adjacent points of wherein said usefulness determine that the specific practice of an intermediate computations point on the described relative motion curve is:

Make to be positioned in above-mentioned adjacent 3 the line in 2 in the outside, point in the middle of being positioned at from above-mentioned adjacent 3 is outwards made the vertical line perpendicular to above-mentioned line, the stretch out distance of the difference that equals tool radius and radius of roller of the point that intersects from this vertical line and design curve, that obtains is an intermediate computations point on the described relative motion curve;

(3) process of repetition (2) obtains the relative motion curve corresponding to the cutting tool pivot of whole design curve;

(4) making cam and cutting tool produce relative motion according to above-mentioned relative motion curve processes cam on the cam process equipment.

Preferably, the difference of the angular coordinate of the consecutive points on the design curve is little constants.

Preferably, approach do local nonlinear curve by the above-mentioned relative motion curve that obtains.

Preferably, the described cam process equipment cam grainder that is swinging structure.

The present invention has developed a kind of new numerical-control processing method, can adopt design data, calculate required lifting curve, and then draw the position of feed shaft and the table of cam curved surface relation based on the roller mensuration, thereby mechanical processing process is finished in the action of control feed shaft.The core of this method is to have developed a kind of Mathematical Modeling, this model under polar coordinates according to cam design lift corresponding to each point of each angle coordinate, calculate the process data curve (the corresponding curve of the utmost point under polar coordinates footpath and polar angle) of cam, realize mechanical processing process according to a kind of procedure of this curve setting again cam.

Description of drawings

The invention will be further described below in conjunction with drawings and Examples, wherein

Fig. 1 is the schematic diagram that shows how basis calculates required Processing Curve based on the resulting design curve of the design data of roller mensuration;

Fig. 2 carries out the schematic diagram of cam processing for adopt the cam grainder of swinging structure according to the present invention.

The specific embodiment

Provide the present invention with mode for example below and determine the method for feed shaft in polar coordinates upper/lower positions array.It may be noted that method of the present invention is not limited to the pointed method of these examples.

When adopting the roller mensuration, the angle certain according to the every interval of curvature situation of wanting processing curve (the step value δ of polar angle α) determined the external diameter r (lift) of cam design curve, and (α 1 to obtain the array of a plurality of α and r, r1), (α 2, r2), (α 3, r3), Can set α 2=α 1+ δ, α 3=α 2+ δ=α 1+2 δ,

According to this array, can extrapolate the array of representing the feed shaft position with mathematical method according to desired precision and the mechanical processing tools of being taked.

For example, if the number of the array of sign design curve is abundant, then can get adjacent line at 2, outwards make vertical line from this line mid point, along the stretch out distance of cutting tool radius of this vertical line, the coordinate of that obtains promptly can be used as the coordinate corresponding to the point of the cutting tool Processing Curve of those two consecutive points on the design curve from this mid point.

For example, can also be according to three on the design curve of desired cam the polar coordinates of adjacent point release position corresponding to the feed shaft of the intermediate point in these 3.

A kind of processing method is: cam is along self axis rotation, and emery wheel is feeding radially, can calculate the curve movement of emery wheel in this case according to the design curve of cam.

Illustrate below emery wheel center when obtaining with the emery wheel processing work with the roller mensuration the process of curve (curve movement that also is called emery wheel) of process.Emery wheel is along the curvilinear motion that calculates, continuous grinding work piece, and when grinding wheel movement after one week, workpiece has also been answered grinding forming.Desired promptly is coordinate corresponding to the emery wheel central point of every bit on the design curve.

Referring to Fig. 1, how it show according to the polar coordinates of three on the cam design curve adjacent points and release position corresponding to the feed shaft of the intermediate point in these 3.A, B, C place curve are the track (design data) of roller centre when using the roller mensuration, the i.e. design curve of cam among the figure.S is for measuring starting point, and O is the origin of coordinates, and A, B, C are three consecutive points on the curve; The curve that its outer with dashed lines is represented is the track at the emery wheel center that calculates, and the D point on it is the position, emery wheel center of ordering corresponding to B among three consecutive points A, B, the C on the cam design curve.Here provide a kind of method, calculate required Processing Curve according to design curve.(α 1, and r1), (α 2, and r2), (α 3, r3) by array for design curve ..., express, wherein α is a polar angle, r is utmost point footpath; The number of array can be decided according to the complexity of desired machining accuracy and curve.If the polar coordinates that D is ordered be (p, q), wherein p is a polar angle, q is utmost point footpath, the polar curve of each D point formation is Processing Curve.As can be seen from Figure, if the polar angle that B is ordered is α, then when α spends less than 18O, p=α-τ, and when α spends greater than 180, p=α+τ, wherein τ is the angle between straight line OB and the straight line OD.

Have the physical significance of related parameter as follows in the computing formula:

R1: grinding wheel radius

R0: cam generating circle radius

R2: the radius of roller during the roller mensuration

α A, α B ...: design data A, B ... corresponding respectively cam angle

1 _A, 1 _B...: design data A, B ... corresponding respectively cam lift

Hence one can see that

OA＝R0+1 _A，OB＝R0+1 _B，OC＝R0+1 _C (1)

Because on the cam certain a bit, the emery wheel center during measurement when roller centre and grinding all is positioned on the normal of this point.For continuous 3 A, B, the C in the design data, can get the B point perpendicular to the straight line of AC as the normal of the point on the pairing cam contour of B point (among Fig. 1, point F is the intersection point of straight line OB and straight line AC, and some E is the extension line of straight line BD and the intersection point of straight line AC).

Then have: BD=R1-R2 (2)

Grind the cam that meets design data, then need calculate the corner ∠ SOD apart from OD and emery wheel center of cam center to the emery wheel center.

As can be seen from Figure:

Work as α _BIn the time of＜180 °, ∠ SOD=α _B-∠ BOD (3)

Work as α _BIn the time of＞180 °, ∠ SOD=α _B+ ∠ BOD (4)

1. in Δ OAC, can derive

$\mathrm{AC}=\sqrt{{\mathrm{OA}}^2+{\mathrm{OC}}^2-2\·\mathrm{OA}\·\mathrm{OC}\·\cos \∠\mathrm{AOC}}---\left(5\right)$

When the step value δ of polar angle was steady state value, straight line OB was the angular bisector of angle AOC, can derive thus

$\frac{\mathrm{FC}}{\mathrm{FA}}=\frac{\mathrm{OC}}{\mathrm{OA}}\⇒\mathrm{FA}=\frac{\mathrm{OA}\·\mathrm{AC}}{\mathrm{OA}+\mathrm{OC}}---\left(6\right)$

$\∠\mathrm{OAC}=\arccos \frac{{\mathrm{OA}}^2+{\mathrm{AC}}^2-{\mathrm{OC}}^2}{2\·\mathrm{OA}\·\mathrm{AC}}---\left(7\right)$

2. in Δ OFA

$\mathrm{OF}=\sqrt{{\mathrm{OA}}^2+{\mathrm{FA}}^2-2\·\mathrm{OA}\·\mathrm{FA}\·\cos \∠\mathrm{OAC}}---\left(8\right)$

$S_{\mathrm{\ΔOAF}}=\frac{1}{2}\mathrm{FA}\·\mathrm{OG}=\frac{1}{2}\mathrm{OA}\·\mathrm{OF}\·\sin \∠\mathrm{AOF}\⇒\mathrm{OG}=\frac{\mathrm{OA}\·\mathrm{OF}\·\sin ({\mathrm{\α}}_B-{\mathrm{\α}}_A)}{\mathrm{FA}}---\left(9\right)$

3.ΔOGF∝ΔBEF

FB＝OB-OF (10)

$\mathrm{BE}=\frac{\mathrm{FB}\·\mathrm{OG}}{\mathrm{OF}}---\left(11\right)$

Have: DE=DB+BE=R1-R2+BE (12)

AG＝OA·cos∠OAC (13)

α _BIn the time of＜180 °

FG＝FA-AG (14)

α _BIn the time of＞180 °

FG＝AG-FA (15)

FE＝FB*FG/OF (16)

4. among the Δ OAE

α _BIn the time of＜180 °

AE＝FA+FE (17)

α _BIn the time of＞180 °

AE＝FA-FE (18)

$\∠\mathrm{OEA}=\arccos \frac{{\mathrm{OE}}^2+{\mathrm{AE}}^2-{\mathrm{OA}}^2}{2\·\mathrm{OE}\·\mathrm{AE}}---\left(19\right)$

$0E=\sqrt{{\mathrm{OA}}^2+{\mathrm{AE}}^2-2\·\mathrm{OA}\·\mathrm{AE}\·\cos \∠\mathrm{OAC}}---\left(20\right)$

5. in Δ OED

α _BIn the time of＜180 °

∠OED＝∠OEA+90° (21)

α _BIn the time of＞180 °

∠OED＝270°-∠OEA° (22)

$0D=\sqrt{{\mathrm{OE}}^2+{\mathrm{DE}}^2-2\·\mathrm{OE}\·\mathrm{DE}\·\cos \∠\mathrm{OED}}---\left(23\right)$

6. in Δ OBD

$\∠\mathrm{BOD}=\arccos \frac{{\mathrm{OB}}^2+{\mathrm{OD}}^2-{\mathrm{BD}}^2}{2\·\mathrm{OB}\·\mathrm{OD}}---\left(24\right)$

Thereby can draw

α _BIn the time of＜180 °

∠SOD＝∠SOB-∠BOD (25)

α _BIn the time of＞180 °

∠SOD＝∠SOB+∠BOD (26)

The utmost point footpath OD and the polar angle ∠ SOD at the emery wheel center of ordering have so just been obtained corresponding to the B on the design curve by three consecutive points A, B, C on the design curve.

Repeat above process, just can obtain representing the coordinate array of whole Processing Curve.

In addition, can also be that the adjacent successively point of n is determined a corresponding maximal end point on the Processing Curve based on the number more than three on the design curve.Method is for determining an intermediate computations point on the Processing Curve with per three adjacent points, can obtain n-2 intermediate computations point corresponding to a maximal end point on the Processing Curve, according to importance this n-2 intermediate computations point applied weight, locus to this n-2 intermediate computations point is weighted on average then, finally obtains corresponding to the final calculation level on the Processing Curve of this n on the design curve point.

Can also approach do local nonlinear curve by the above-mentioned Processing Curve that obtains, so that this curve is more level and smooth.

Clearly, for a person skilled in the art,, also can extrapolate coordinate on the Processing Curve with geometric method according to actual conditions even the polar angle step value on the design curve between each consecutive points is not a constant τ value.

The processing method of another kind of swinging structure lathe is: emery wheel is not except that doing moving or rotation of other modes along himself axis rotation is, and cam member is supported rotationally by a fork and contacts with emery wheel.Cam rotates along the direction opposite with the emery wheel direction of rotation, and fork swings back and forth, and cam turns around, and one of fork rotation back and forth.Can calculate the swing mode of fork in this case equally according to the design curve of cam.Fork is promptly swung according to the pattern that this calculates, and realizes the machining to cam member.

For the cam grainder of swinging structure, its schematic diagram as shown in Figure 2.

M is the emery wheel center, and N is the fork pivot, and W is the cam pivot.

Process cam, then need the OD and the ∠ SOD of previous calculations are converted into fork anglec of rotation γ and cam anglec of rotation θ.

The implication of each physical quantity is as follows in Fig. 2:

R3: fork length

B: the angle of fork when cam is in initial position

$\mathrm{MN}=\sqrt{{(\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="C0112537100131.png"\; state="\{\{state\}\}">R</figure-callout>}1+\mathrm{<figure-callout\; id="0"\; label="R"\; filenames="C0112537100131.png"\; state="\{\{state\}\}">R</figure-callout>}0+R3\&CenterDot;\cos \mathrm{\&beta;})}^2+{(R3\&CenterDot;\sin \mathrm{\&beta;})}^2}---\left(27\right)$

${\mathrm{\&beta;}}_1=\arccos \frac{{\mathrm{MN}}^2+R_3^2-{({\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="C0112537100131.png"\; state="\{\{state\}\}">R</figure-callout>}}_1+R_0)}^2}{2\&CenterDot;\mathrm{MN}\&CenterDot;R_3}---\left(28\right)$

When fork is put dotted line position shown in Figure 2:

MW ＇=OD (OD is the previous calculations result)

$\cos ({\mathrm{\&beta;}}_1+\mathrm{\&gamma;})=\frac{{\mathrm{MN}}^2+R_2^3-{\mathrm{OD}}^2}{2\&CenterDot;\mathrm{MN}\&CenterDot;R_3}\&DoubleRightArrow;$

$\mathrm{\&gamma;}=\arccos \frac{{\mathrm{MN}}^2+R_2^3-{\mathrm{OD}}^2}{2\&CenterDot;\mathrm{MN}\&CenterDot;R_3}-{\mathrm{\&beta;}}_1---\left(29\right)$

${\mathrm{<figure-callout\; id="1"\; label="X"\; filenames="C0112537100131.png"\; state="\{\{state\}\}">X</figure-callout>}}_1=\arccos \frac{{({\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="C0112537100131.png"\; state="\{\{state\}\}">R</figure-callout>}}_1+R_0)}^2+{\mathrm{OD}}^2-{(2\&CenterDot;R_3\&CenterDot;\sin \frac{\mathrm{\&gamma;}}{2})}^2}{2\&CenterDot;({\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="C0112537100131.png"\; state="\{\{state\}\}">R</figure-callout>}}_1+R_0)\&CenterDot;\mathrm{OD}}---\left(30\right)$

Thereby can draw, when cam counterclockwise rotates

θ=∠ SOD+X ₁+ γ, wherein ∠ SOD is previous calculations result (31)

When the cam clockwise direction rotates

θ＝∠SOD-X ₁-γ (32)

It will be appreciated by those skilled in the art that, the part that relates to the locus in the technology of the present invention content adopts polar coordinates to explain, but adopts rectangular co-ordinate or other to well known to a person skilled in the art coordinate, can achieve the above object too, therefore, description of the invention is not limited to polar coordinates.

Can come the grinding cam with emery wheel, also can be with other grinding tool, for example metal-cutting machine tool.

The method of the corresponding cutting tool centre of gyration of design data (design curve) the calculating position according to cam only has been described above by way of example, but the insider be it is evident that, the computational methods of cutting tool centre of gyration position are not limited to above-described method, but can be according to complexity, machining accuracy and the selected many indexs such as manufacturing process of cam to be processed, adopt multiple different predication method, to reach desired designing requirement.In other words, the cited method of the foregoing description only is exemplary and nonrestrictive, under the condition that does not deviate from spirit and scope of the invention, can adopt multiple different computational methods, and these computational methods is all within category of the present invention

Those skilled in the art know that easily the present invention also is not limited only to simple convex surface object, in conjunction with other method, can be used for the convex portions of the object of partial-band concave surface.

The present invention also is not limited only to metalwork, also can be used for the machining of non-metallic workpiece.

Claims (8)

1. the numerical-control processing method of a cam is characterized in that, comprises the steps:

(1) obtains coordinate array based on the sign cam design curve of roller mensuration;

(2) extrapolate the coordinate figure of circular cutting tool pivot with respect to a respective point of the cam rotating shaft heart according to the coordinate figure of three consecutive points on the cam design curve with geometric method, specific practice is:

Make to be positioned in above-mentioned adjacent 3 the line in 2 in the outside, point in the middle of being positioned at from above-mentioned adjacent 3 is outwards made the vertical line perpendicular to above-mentioned line, the stretch out distance of the difference that equals tool radius and radius of roller of the point that intersects from this vertical line and design curve, the coordinate of that obtains are the coordinate figure corresponding to a respective point of the cutting tool pivot of the intermediate point in the above adjacent 3 of the design curves;

(3) process of repetition (2) obtains the relative motion curve corresponding to the cutting tool pivot of whole design curve;

(4) making cam and cutting tool produce relative motion according to above-mentioned relative motion curve processes cam on the cam process equipment.

2. the method for claim 1 is characterized in that, the difference of the angular coordinate of the consecutive points on the design curve is little constants.

3. the method for claim 1 is characterized in that, approaches so that curve smoothingization done local nonlinear curve by the above-mentioned relative motion curve that obtains.

4. as each described method among the claim 1-3, it is characterized in that described cam process equipment is the cam grainder of swinging structure.

5. the numerical-control processing method of a cam is characterized in that, comprises the steps:

(1) obtains coordinate array based on the sign cam design curve of roller mensuration;

(2) be that the coordinate figure of the consecutive points of n is extrapolated the coordinate figure of circular cutting tool pivot with respect to a respective point of the cam rotating shaft heart with geometric method according to the number more than three on the cam design curve, method is for determining an intermediate computations point on the described relative motion curve with per three adjacent points, can obtain n-2 intermediate computations point corresponding to a maximal end point on the described relative motion curve, according to importance this n-2 intermediate computations point applied weight, locus to this n-2 intermediate computations point is weighted on average then, obtain corresponding to the maximal end point on the relative motion curve of this n on the design curve point

Per three the adjacent points of wherein said usefulness determine that the specific practice of an intermediate computations point on the described relative motion curve is:

Make to be positioned in above-mentioned adjacent 3 the line in 2 in the outside, point in the middle of being positioned at from above-mentioned adjacent 3 is outwards made the vertical line perpendicular to above-mentioned line, the stretch out distance of the difference that equals tool radius and radius of roller of the point that intersects from this vertical line and design curve, that obtains is an intermediate computations point on the described relative motion curve;

(3) process of repetition (2) obtains the relative motion curve corresponding to the cutting tool pivot of whole design curve;

(4) making cam and cutting tool produce relative motion according to above-mentioned relative motion curve processes cam on the cam process equipment.

6. method as claimed in claim 5 is characterized in that, the difference of the angular coordinate of the consecutive points on the design curve is little constants.

7. method as claimed in claim 5 is characterized in that, approaches done local nonlinear curve by the above-mentioned relative motion curve that obtains.

8. as each described method among the claim 5-7, it is characterized in that described cam process equipment is the cam grainder of swinging structure.

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