JPH0144469B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to an improvement of a scanning control device, and more particularly, to a scanning control device that can maintain machining accuracy at a desired level and improve machining accuracy. It is something.

Conventional technology and problems The tracing control device moves the tracer head and cutter together based on a displacement signal corresponding to the displacement of the stylus output from the tracer head that tracks the model surface, so that the workpiece and model have the same shape. However, the machining accuracy differs between the part machined by down-cutting and the part machined by up-cutting. In the case of up-cutting, the workpiece 2 is cut by the side surface of cutter 1 as shown in Figure 1A, but in the case of down-cutting, the workpiece 2 is cut as shown in Figure 1B.
The workpiece 2 will be cut at the bottom surface RO. Since the circumferential speed of the bottom surface (B) is slower than that of the side surface (A), the cutting amount of the cutter 1 is smaller in the case of down cutting than in the case of up cutting. The machining accuracy of the area becomes worse than the machining accuracy of the up-cut part.

In this way, the machining accuracy of the down cut part is worse than the machining accuracy of the up cut part, so in order to make the machining accuracy of the entire workpiece more than the predetermined accuracy, the feed rate of cutter 1 should be changed to the lower cut part of the down cut part. In order for the machining accuracy to reach a predetermined level, the machining accuracy must be set slowly, which has the disadvantage of slowing down the machining speed.

OBJECTS OF THE INVENTION The present invention has been made to improve the above-mentioned drawbacks, and its purpose is to improve the machining speed and maintain the machining accuracy at a desired level. Examples will be described in detail below.

Embodiment of the Invention FIG. 2 is a block diagram of an embodiment of the present invention, in which 3 is a tracer head, 4 is a stylus, 5 is a displacement synthesis circuit, 6 is an indexing circuit, 7 is an adder, 8,
9 is a speed calculation circuit, 10 is a distribution circuit, 11 is a gate circuit, 12X to 12Z are amplifiers, 13X to 13
Z is a motor, 14 is a tangential speed setting circuit, 15 is a clamp speed setting circuit, 16 and 18 are arithmetic circuits, 1
7 is a comparator, and 19 is a gate circuit.

The tracer head 3 outputs displacement signals ε _x , ε _y , ε _z corresponding to the displacement of the stylus 4, and the displacement synthesis circuit 5 outputs a composite displacement signal ε=√ _x ² + _y ² + _z ² .
The adder 7 calculates the difference Δε=ε−ε ₀ between the composite displacement signal ε and the reference displacement signal ε ₀ , and the speed calculation circuits 8 and 9 calculate the normal direction velocity signal based on the difference Δε.
V _N 'Tangential velocity V _T is determined and applied to the distribution circuit 10. Further, when the scanning plane is the XZ plane, the indexing circuit 6 performs calculations shown in the following equations (1) and (2) to create displacement direction signals sinα and cosα.

sinα=ε _z /√ _x ² + _z ² ...(1) cosα=ε _z /√ _x ² + _z ² ...(2) The distribution circuit 10 receives the displacement direction signal from the indexing circuit 6
Command speed signals V x ', _{V z} in the X and Z axis directions are created based on sin α, cos α and speed signals V _N ', V _T from the speed calculation circuits 8, 9. This command speed signal V _x ′,
_Vz is connected to the amplifier 12X, 1 via the gate circuit 11.
The motors 13X, 13Z are driven by the outputs of the amplifiers 12X, 12Z, and the tracer head 3 and the cutter (not shown) are fed together. Incidentally, since the above-mentioned operation is well known, further detailed explanation will be omitted.

The tangential speed setting circuit 14 sets the tangential speed V, and the clamp speed setting circuit 15
is used to set the upper limit value _Vzc of the velocity component in the −Z-axis direction. Arithmetic circuit 16 is tangential speed setting circuit 1
Based on the tangential speed V set by 4 and the upper limit value _Vzc set by the clamp speed setting circuit 15, the calculation shown in the following equation (3) is performed.

cosθ=V _zc /V (3) Note that θ is the angle set as shown in FIG. 3, and in the same figure, the radius of the circle is the tangential speed set by the tangential speed setting circuit 14. This corresponds to V.

The comparator 17 compares the output signal cosθ of the arithmetic circuit 16 with the displacement direction signal cosα output from the indexing circuit 6, and sets the output signal a to “1” if cosα is larger. Here, the displacement direction signal cosα is negative in the case of an up cut,
In the case of a down cut, the value is positive as shown in FIG. In the case of a down cut, the larger the angle formed with the X-axis model plane and the steeper the inclination of the model, the larger the displacement direction signal cosα becomes.
That is, the comparator 17 receives the output signal cosθ of the arithmetic circuit 16.
By comparing the displacement direction signal cosα from the indexing circuit 6, it is determined whether the speed of the cutter in the −Z axis direction has reached the upper limit value _Vzc , and it is determined that it has reached the upper limit value _Vzc . In this case, the output signal a is “1”
That is.

The arithmetic circuit 18 also includes the clamp speed setting circuit 1
The calculation shown in the following equation (4) is performed based on the upper limit value V _zc outputted from the gate circuit 5 and the calculation result cos θ of the calculation circuit 16 , and the calculation result V ₀ is added to the gate circuit 19 .

V ₀ =V _zc /cosθ (4) When the output signal a of the comparator 17 is “1”, the gate circuit 19 applies the calculation result of the calculation circuit 18 to the speed calculation circuit 9, and the signal a becomes “1”. 0'', the output signal V of the tangential speed setting circuit 18 is applied to the speed calculation circuit 9. That is, if the speed of the stylus 4 in the -Z axis direction is less than the upper limit value _Vzc ,
The speed in the tangential direction is the speed V set by the tangential speed setting circuit 14, and even if the speed of the stylus 4 in the -Z axis direction exceeds the upper limit value _Vzc as shown in FIG. Speed determined by equation (4)
Since it is clamped at V ₀ , the speed in the -Z axis direction becomes the upper limit value V _zc .

In this way, in this embodiment, when the speed of the stylus 4 in the -Z axis direction is less than _or equal to the upper limit value Vzc, the tangential speed is set to the speed V set by the tangential speed setting circuit 14, and the upper limit value _Vzc When attempting to exceed , the velocity in the tangential direction is set to the velocity V ₀ obtained by equation (4), and −
Since the speed in the Z-axis direction is prevented from exceeding the upper limit value V _zc , the machining speed can be improved compared to the conventional example, and the machining accuracy can be maintained at a desired level.

Effects of the Invention As explained above, the present invention provides the following effects based on the output signal of the tracer head, the upper limit value _Vzc set by the clamp speed setting circuit, and the tangential speed V set by the tangential speed setting circuit. Judgment means (comprised of an arithmetic circuit 16 and a comparator 17 in the embodiment) for judging whether the velocity component of the tracer head in the -Z axis direction has reached the upper limit value set by the clamp speed setting circuit; , if the velocity component of the tracer head in the -Z axis direction is less than the upper limit value V _zc based on the determination result of the determination means, move the tracer head in the tangential direction at a speed set by the tangential speed setting circuit; A signal is output, and the velocity component of the tracer head in the -Z axis direction is the upper limit value V _zc
In this case, a control means (in the embodiment, arithmetic circuit 18, gate A moving means for moving the tracer head and the cutter based on the output signal of the control means (in the embodiment, it consists of a speed calculation circuit 9, etc.), If the velocity component of the tracer head in the -Z axis direction is less than the upper limit, the tangential velocity of the tracer head is set as the predetermined velocity, and if it attempts to exceed the upper limit, the velocity component of the tracer head in the -Z axis direction becomes the upper limit. Since the tracer head is sent in the tangential direction at such a speed as to obtain the desired value, the processing speed can be improved compared to conventional devices, and the processing accuracy can be maintained at a desired level.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the drawbacks of the conventional device, FIG. 2 is a block diagram of the embodiment of the present invention, FIG. 3 is a diagram for explaining the calculation contents of the calculation circuit 16, and FIG. It is a figure explaining the operation|movement of a figure. 1 is a cutter, 2 is a workpiece, 3 is a tracer head, 4 is a stylus, 5 is a displacement synthesis circuit, 6 is an indexing circuit, 7 is an adder, 8 and 9 are speed calculation circuits, 1
0 is a distribution circuit, 11 and 19 are gate circuits, 12
X, 12Z are amplifiers, 13X to 13Z are motors,
14 is a tangential speed setting circuit, 15 is a clamp speed setting circuit, 16 and 18 are arithmetic circuits, and 17 is a comparator.

Claims (1)

[Claims] 1. In a tracing control device that integrally moves the tracer head and cutter based on the output signal of the tracer head that tracks the model surface, an upper limit value of the speed component of the tracer head in the -Z axis direction is set. a clamp speed setting circuit, a tangential speed setting circuit for setting the tangential speed of the tracer head, and an upper limit value set by the output signal of the tracer head and the clamp speed setting circuit; and determining means for determining whether or not the velocity component of the tracer head in the −Z-axis direction has reached the upper limit set by the clamp speed setting circuit based on the tangential direction velocity; Based on this, if the velocity component of the tracer head in the -Z axis direction is less than the upper limit value, a signal is output to move the tracer head in the tangential direction at a speed set by the tangential speed setting circuit, and the tracer head is -Z of head
control means for outputting a signal to move the tracer head in the tangential direction at a speed that brings the -Z-axis velocity component of the tracer head to the upper limit when the velocity component in the axial direction reaches the upper limit; A copying control device comprising a moving means for moving the tracer head and the cutter based on an output signal of the control means.