JPS5835829B2 - Tracing control method that performs index correction - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a scanning control method, and more particularly to a scanning control method that compensates for errors on the directional side due to friction between the star f-lass and the -middel.

In tracing control, the model is Laser Hetsu 2! The stylus is pressed against the stylus, the movement of the stylus and tool is controlled using the displacement received by the stylus as a control signal, the stylus is moved along the model surface, and the work piece is machined according to the model using the tool.

To further explain this point regarding the two-dimensional profiling shown in Fig. 1, C is the model surface, S is the tip of the stylus, 01 is the center point of the curved surface of the model C in the 6 parts where the stylus tip S contacts, 02 is the center point of the stylus tip S.

When one end of the stylus tip S with a circular cross section is pressed against a = -± del surface C at a point P1 on the surface, the stylus tip S receives a reaction force in the normal direction at the point P, causing a displacement indicated by ε. arise.

A displacement measuring means such as a differential transformer is attached to the squirrel along each of the X, y, and z coordinates.1. t, so the X component ε and the y component ε of the displacement ε are detected.

X and y components ε of displacement ε. When ε is detected, the polar coordinate angle θ of point P with respect to the .

However, the above is an ideal case in which the stylus S is stationary and there is no measurement error in the displacement measuring means, and generally results deviate from the above situation.

For example, if the stylus is not pressed against the model surface C but is moved along the steel surface, there will be friction between the two, so the stylus S will have a force F determined by the pressing force and the coefficient of friction.
is received in a direction opposite to the direction of movement, and as a result, the displacement of the stylus S becomes ε', which corresponds to ε10F.

Here, the mark indicates a vector combination.

When the displacement is detected as ε', the angle calculated from this is θ', and the tangential velocity is vT/.

The angle θ' is θ' = θ + Δθ, which is △ from the correct angle θ.
The error is θ, and the tangential velocity ■′T is the same angle △θ
deviates from the correct cutting line direction.

If the stylus S is sent at the speed VT/, the stylus S will move away from the model surface C, as is clear from the figure.

To prevent this, add an auxiliary signal vN to VT'+
What is necessary is to make VN=VT.

This correction signal VN has a certain constant value ε.

Finally, V N ocε−ε.

have a relationship. That is, when the stylus S is separated from the model surface C by being fed at the tangential velocity VT/, the displacement ε of the stylus S becomes the initial displacement ε according to the separation distance (denoted as Δd).

The displacement deviation △ε becomes smaller, that is, △docε−ε0−△. On the other hand, the auxiliary signal VN needs to be generated in accordance with the separation distance Δd, that is, V N QC △d. The signal VN has a displacement ε-ε as shown in FIG.

It will be proportional to.

Here, ε is also called a certain constant value or the initial displacement.

is the amount of displacement required to normally operate the stylus displacement measuring means, and when the stylus S is correctly displaced in the normal direction and the auxiliary signal vN is not required, the stylus S is ε.

produces a displacement ε equal to . That is, in this case, VN=K(ε
−ε.

)=O holds true. By adding the auxiliary signal VN, it is possible to send the stylus in the direction of the tangential line of the model surface, but this method always produces errors.

That is, the angle θ is detected as θ' which is θ+△θ, and the tangential velocity is determined as ■T', and the auxiliary signal VN is added to this to obtain the desired tangential velocity VT. Correction errors remain.

Therefore, the present inventor previously proposed a tracing control method in which the angle θ itself can be obtained by adding a correction signal to the displacement signal from the stylus (Japanese Patent Application No. 15081/1981).

However, in this method, the correction signal is calculated from the deviation signal Δε and the output of the displacement direction indexing circuit, and the indexing correction circuit that performs this calculation requires a complicated multiplication circuit.

The present invention aims to improve these points and to provide a tracing control system that can obtain the displacement direction angle θ itself using a relatively simple circuit and thereby perform extremely accurate tracing control.

The tracing control method of the present invention uses a constant deviation amount ε from the scalar amount ε of the stylus displacement detected by the tracer head.

An integral circuit generates a correction amount Aε' that gradually increases or decreases when the deviation Jε obtained by subtracting the value is equal to or greater than a certain positive or negative value, and an arithmetic circuit generates the product A of the correction amount and the x and y components of the displacement. =, (ε′・ε,, B=Jε′・ε.

Calculate the sum or difference between the nuclide and the X and y components of the displacement, A' = ε, 1 B, B' - ε, -A, and
B / 1°) 0 = J -) - B", &〒toi is calculated as D = , and Sθ of C = and D = sin θ are obtained to find the correct angle θ of the displacement direction with respect to the reference axis, and this angle The present invention is characterized in that the feed of the stylus and tool is controlled using θ, which will now be described in detail with reference to FIGS. 3 to 5.

Figure 3 shows the displacement ε of the stylus and the outputs εa, ε7 of the differential transformer on the X, y, and z axes when the model forms a three-dimensional curved surface.
．． The relationship with ε2 is shown.

As is clear from this figure, the angle of the displacement vector ε forming the XY plane is φ, and the projected component of the displacement vector ε onto the XY plane ε8. Letting θ be the angle formed between

FIG. 5 shows a tracing control circuit according to the present invention, in which the outputs ε8. ε7. ε2 is sent to a combining circuit 3 and a switching circuit 4 through amplifiers 2a, 2b, and 2c.

In synthesis circuit 3, the scalar quantity ε of vector ε = e”z
+ e”,, + e is calculated, and the adder 8 calculates a constant displacement amount ε from the displacement ε.

is subtracted to output the deviation Δε=ε−ε0.

The arithmetic circuit 6 receives the deviation signal Δε and calculates the tangential velocity VT and the correction auxiliary velocity vN.

As described above, the present invention corrects the scanning direction indexing signal to control Δε and VN to zero.

The index correction circuit 5 is provided for this purpose.

The switching circuit 4 provided in the indexing circuit and path system includes amplifiers 2a to 2.
It is connected to the output side of c and outputs a desired displacement component according to the scanning surface selection signal.

For example, when copying is performed on the X-Y plane, the displacement component ε8
．． ε.

are outputted and added to the indexing circuit 7 and the indexing correction circuit 5.

As shown in FIG. 4, the indexing correction circuit 5 includes a discrimination circuit 51 that produces an output when the deviation signal △ε is positive, and a dead zone that produces an output when the deviation signal △ε exceeds a certain range W centered on zero. Circuit 52, positive constant current source +■o and negative constant current source -I.

a switching circuit 53 comprising fixed contacts respectively connected to;
Switch 54, integrator 55, polarity switching circuit 56, multiplier 5
It consists of 7°58 mag.

Now, suppose that two-dimensional scanning of the X-Y coordinate plane is performed, and the angle in the displacement direction detected by the stylus S is θ + △θ with an error of Δθ, and in this case, the deviation signal is △ε. , differential transformer I for X and Y components of the stylus
The outputs of a and 1b are ε=εC05(θ+△θ) > 1:
y=E−X y Sln (θ+x xy Δθ), and these are applied to one input terminal of the multiplier 57.58.

Further, when the deviation signal Δε is Δε〉O, the switching circuit 53 is connected to the positive power supply +Eo side, and when the deviation signal Δε is Δε〉W/, the dead band same circuit 52 generates an output, closes the switch 54, and integrates The circuit 55 is supplied with a constant current from a positive constant current source +Io, and outputs a correction amount Δε' that gradually increases.

The correction amount △ε' is passed through the switching circuit 56 and then sent to the multipliers 57 and 58.
is input and multiplied by ε, and ε.

Therefore, the corrected outputs A and B of the multipliers 57 and 58 are A−△ε′
ε,.

B2△ε′ε.

The correction outputs A and B are the displacement direction signal ε8. from the switching circuit 4.
Inputs A/ and B/, which are added and subtracted from ε by adders 10a and 10b, are applied to the indexing circuit 7, and are expressed by the following equations.

A'=ε, +B B′=εy−A When these transform becomes.

The indexing circuit 5 receives the input and outputs displacement direction outputs C and D expressed by the following equations.

If △θ=jan '△ε' holds true in the above equation, the output C2D
is Sθ D=sinθ of C-, and it is possible to output a correct displacement direction angle θ that does not include errors Δθ and the like.

If the correct displacement direction angle θ is found, the tangential velocity vT can be obtained in this direction.
By applying this function, the stylus and tool can be correctly fed in the tangential direction of the model surface at the speed VT.

The output Δε' of the integrating circuit 55 is a constant current I.

Since it is an integral of , its value gradually increases.

Therefore, even after reaching the correct amount of correction that satisfies △θ=1△ε', the output △ε' continues to increase and deviate from this appropriate value, but the output of the indexing circuit 7 is in the correct tangential direction. When outputting the signal C-(2)θ, D=sinθ, which indicates the angle θ of

The integrating circuit 55 then stops the integration and maintains the output Δε' at the above-mentioned appropriate value.

When the deviation △ε appears again as the tracing progresses, the dead band circuit 5
2 generates an output again and closes the switch 54.

If the deviation Δε at this time is Δε<O, the discrimination circuit 51 switches the switching circuit 53 to a negative constant current source -■.

, and apply a current in the opposite direction to the integrating circuit 55 to adjust the correction amount △
Decrease ε′.

The same applies below. The switching circuit 56 switches the polarity of the correction amount Δε' as necessary, that is, when the scanning feed direction is reversed, the polarity is switched by the signal F and the displacement direction signal ε,
.

Match ε.

As is clear from the above explanation, in the present invention, the correction amount Δε' is stored in the integration circuit 55, which can also be called a memory circuit, and the displacement direction signals εξ, εr, etc. are corrected using this correction amount, and the indexing circuit 7 determines the correct displacement. The direction can now be output.

This correction amount △ε' is readjusted immediately if the deviation △ε exceeds W in the dead zone, and is always adjusted to be an appropriate correction amount.

As a result, according to the present invention, tracing can be performed with extremely high accuracy in a state where the deviation Δε is zero.

Further, in the previously proposed method, the correction outputs A and B are calculated from the outputs C and D of the indexing circuit 7 and the correction amount Δε' of the storage circuit 55.

Therefore, the correction outputs A and B are the scalar amount ε8 of the displacement direction signal.
．． It is necessary to make it proportional to the displacement direction signal and then add it to the displacement direction signal, and a multiplier for this purpose is required in addition to the multipliers corresponding to 57 and 58 in FIG.

In the present invention, the multiplier can be omitted and the circuit configuration can be simplified.

Of course, the present invention is not limited to the embodiments illustrated and described, and various modifications are possible.

For example, the deviation signal Δε can be mechanically synthesized and output inside the tracer head instead of being synthesized by a circuit.

Further, the constant current source used for charging the memory circuit may be a constant voltage source, or the output of the discrimination circuit 51 may be used as is.

[Brief explanation of the drawings] Figure 1 is a diagram explaining the stylus output in two-dimensional case, Figure 2 is a graph showing the relationship between deviation signal, tangential speed and auxiliary speed, and Figure 3 is in three-dimensional case. FIG. 4 is a block diagram of a correction signal calculation circuit, and FIG. 5 is a block diagram showing essential parts of the copying apparatus according to the present invention. In the drawing, S is the stylus tip of the tracer head, ε-ε
. −△ε is the deviation signal, △ε′ is the correction amount, ε,. ε is a displacement direction signal, A and B are correction signals, and 7 is a displacement direction indexing circuit.

Claims (1)

[Claims] 1. A constant deviation amount ε from a scalar amount ε of the displacement of the stylus detected by the tracer head. An integrator circuit generates a correction amount Aε′ that gradually increases or decreases when the deviation Jε obtained by subtracting the value is equal to or greater than a certain positive or negative value, and an arithmetic circuit generates a correction amount Aε′ that is the product A of the correction amount and the X and y components of the displacement. −Jε′・εx t B ”” Ac1・ε
, calculate the sum or difference between the nuclide and the x and y components of the displacement, A'=ε, +B, B'=εy−A, and from these, A
/ B1 0'''' A/2+B/2 , , /7 Calculate η4 - C = □□□θ, D = sin θ, find the correct angle θ of the displacement direction with respect to the reference axis, and calculate the angle θ A copying control method for performing index correction, characterized in that the feed of a stylus and tool is controlled using a stylus and a tool.