JPH03213253A - Pick feed control method - Google Patents

Abstract

PURPOSE:To make copying work so accurate by finding an incline of a model surface at time of pick feed starting, and when it is more than the specified value, executing the pick feed with a first plane and when it is less than the specified value, with a second plane, respectively. CONSTITUTION:Setting a horizontal axis to an X-axis, a vertical axis to a Z-axis and a paper surface vertical axis to a Y-axis, respectively, when a tilt angle with both XY planes of a model 41 is set down to thetaa, this angle is found out of a vector of composite displacement epsilon a to be detected by a stylus 21. When the tilt angle thetaa is smaller than the specified value, a pick feed plane should be set to Y-Z plane. It means that an X-axis is fixed, the Y-axis is set to the copying direction and the Z-axis to a copying axis, respectively. A model 42 is the case where a tilt angle thetab is larger than the specified value, the pick feed surface should be set to the X-Y plane. It means that the Z-axis is fixed thereto, the Y-axis to the copying direction and the X-axis to the copying axis, respectively. With this constitution, even in the case of such a model as altering the surface tilt angle so largely, stable pick feed operation can be performed, thus such copying operation as excellent in accuracy is made possible.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a pick feed control method in tracing machining in which a workpiece is machined by tracing a model, and in particular, a method for automatically determining and changing the pick feed plane. This invention relates to a pick feed control method.

[Conventional technology]

In surface tracing machining, etc., trace machining is performed in a fixed direction, a pick-feed operation is performed for a certain distance in a direction almost perpendicular to this, a trace machining is performed again, and this operation is repeated to trace the model surface and perform tracing machining. . The pick feed plane at this time is generally fixed.

[Problem to be solved by the invention]

However, when tracing a corner part of a box-shaped model, such as the inside or outside, in a direction perpendicular to the ridgeline, one pick feed cannot be performed normally if the pick feed surface is fixed. However, on the other side, the pick feed plane and the surface of the model become nearly parallel, making the tracing operation unstable in some cases, making accurate tracing processing difficult.

The present invention has been made in view of these points, and an object of the present invention is to provide a pick feed control method that automatically determines the pick feed plane from the inclination angle of the surface of the model and changes it. do.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a pick feed control method in profiling machining in which a workpiece is machined by tracing a model, in which the inclination angle of the surface of the model is determined at the start of the pick feed, and the inclination angle is greater than or equal to a predetermined value. There is provided a pickfeed control method characterized in that when the angle of inclination is less than a predetermined value, the pickfeed is executed on a first plane, and when the inclination angle is less than a predetermined value, the pickfeed is executed on a second plane.

[Effect]

Find the slope angle of the model surface at the start of pickfeed.

Select a pick feed plane for this inclination angle, and make sure that the pick feed plane and the model surface are not parallel. This allows stable pickfeed operation.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIGS. 2(a) and 2(b) are diagrams showing the relationship between the inclination angle of the surface of the model and the displacement vector. In FIG. 2(a), the horizontal axis is the X axis, the vertical axis is the Z axis, and the axis perpendicular to the plane of the paper is the Y axis. Let θa be the inclination angle of the model 41 with respect to the XY plane. This inclination angle θa can be determined from the vector of the composite displacement εa detected by the stylus 21 by the profile control device. When this inclination angle θa is smaller than a predetermined value, the pick feed plane is set to the YZ plane.

Here, the pick feed surface being in the Y-Z plane means that the X axis is fixed, the Y axis is the tracing direction, and the Z axis is the tracing axis.

Similarly, FIG. 2(b) shows a case where the inclination angle θb of the model 42 is larger than a predetermined value, and this inclination angle θb is determined from the vector of the composite displacement εb detected by the stylus 21. The pick feed plane at this time is the XY plane. Here, the pick feed plane being in the x-Y plane means that the Z axis is fixed, the Y axis is the tracing direction, and the X axis is the tracing axis.

For example, if the pick feed plane is fixed, in the case of Fig. 2(a), the pick feed plane becomes the XY plane, the X axis becomes the tracing axis, and the amount of displacement in the X axis direction is large.
Pick feed operation becomes unstable. Therefore, the present invention attempts to automatically change the pick feed plane according to the inclination angle of the surface of the model.

The value of the inclination angle for switching the pick-feed plane was determined experimentally, and it was found that a predetermined value is the angle that allows the most stable pick-feed operation. but,
Needless to say, this value varies depending on the tracing control loop, tracing gain, tracing speed, etc.

FIG. 3 is a diagram showing a pick feed plane when tracing the inner surface of a box-shaped workpiece. The workpiece 43 is box-shaped, and its inner surface is traced in both directions perpendicular to the ridgeline. Point P1
At the start of the pick feed, the vector of the resultant displacement εC, that is, the inclination angle, is approximately 90 degrees, and the pick feed plane is the XY plane as shown by diagonal lines.

A pick feed is performed at point P1, a tracing operation is performed along the line indicated by Ll, and point P2 is reached.

At the start of the pick feed at point P2, the vector of the resultant displacement εd, that is, the inclination angle, is approximately 0 degrees, and the pick feed plane is the Y-Z plane as shown by diagonal lines.

In this way, by switching the pick feed plane in accordance with the slope, a stable pick feed operation can be performed as explained in FIGS. 2(a) and 2(b).

FIG. 1 is a flowchart of an embodiment of the pick feed control method of the present invention. In the figure, the number following S indicates the step number.

[S1] Start stock feed.

[S2] Obtain the inclination angle θ of the surface of the model. This can be determined from the resultant displacement vector.

[S3] Check whether θ is greater than a predetermined value, and if so, proceed to S4.

If not, proceed to S5.

[S4] Since the inclination angle is larger than the predetermined value, the pick feed operation is performed with the pick feed plane set as the X-Y plane.

[S5] Since the inclination angle is not larger than the predetermined value, the pick feed operation is performed with the pick feed plane set as the YZ plane.

[S6] Following the bit field operation, a tracing operation is executed.

[S7] Check whether the tracing is completed and if it is not completed,
Return to Sl and continue machining.

In the above description, the pick feed plane is switched between the XY plane and the YZ plane, but it goes without saying that these planes can be selected depending on the type of tracing.

FIG. 4 is a block diagram showing the configuration of a profiling control device according to an embodiment of the present invention. In the figure, a tracer head 20 installed in a profiling machine tool has X-axis, Y-axis, and
The displacement amounts εX, εy, and S2 in the axial and Z-axis directions are detected and input to the switching circuit 1 and the combining circuit 3. The switching circuit 1 selects the biaxial displacements ε1 and S2 of the tracing plane commanded via the operation panel 30 from among these displacements and inputs them to the indexing circuit 2. The indexing circuit 2 uses the displacement amounts ε1 and S2 to calculate the following equation, Ec-ε1/(ε1
2+ε22)1/2=cose Es2ε2/(ε12+ε22)l/2=sine to obtain index signals Ec and Es.

In addition, in the synthesis circuit 3, a composite displacement amount ε (ε−(εx2+εy2 +εz2M/
2) is determined and input to the calculator 4. The calculator 4 calculates the difference Δε(Δ
ε=ε-60) is calculated and input to the speed signal generation circuits 5 and 6. The speed signal generation circuit 5 generates a feed speed signal (tangential speed signal) Vt in a direction perpendicular to the stylus displacement direction based on the difference Δε. Further, the speed signal generation circuit 6 generates a feed speed signal (normal direction speed signal) Vn in the stylus displacement direction in proportion to the difference Δε.

The distribution circuit 7 uses the ratio signals Ec and Es, the tangential velocity signal Vt, and the normal velocity signal Vn to form the following equation, V1=VtXsinθ−VnXcoseV2−−VtX
cose-Vnxsine is calculated to obtain the velocity components V1 and VZ of the two axes of the tracing plane, and these are sent to the X-axis, Y-axis, and Z-axis velocity signals Vx, V through the output axis selection circuit 8.
y and VZ, and amplified by servo amplifiers 9x, 9y, and 9z.

Then, the servo motors 22x and 22y are driven by the outputs of the servo amplifiers 9x and 9y, and a table (not shown) is moved. Further, the servo motor 222 is driven by the output of the servo amplifier 9z, and a cutter (not shown) moves in the Z-axis direction together with the tracer head 20.

Switching of the pick feed plane mentioned above is performed by switching circuit 1.
carried out by. Further, the inclination angle is obtained from the resultant displacement amount ε.

〔Effect of the invention〕

As explained above, in the present invention, the pickfeed plane is switched according to the inclination angle of the surface of the model, so stable pickfeed operation can be performed even for models whose surface inclination angle changes greatly. , it becomes possible to perform highly accurate tracing machining.

[Brief explanation of drawings]

Fig. 1 is a flowchart of an embodiment of the pick feed control method of the present invention, Fig. 2 (a>, (b) is a diagram showing the relationship between the inclination angle of the model surface and the displacement vector, and Fig. 3 is a box Figure 4 is a block diagram showing the configuration of a tracing control device according to an embodiment of the present invention. Composite circuit - Speed signal generation circuit Speed signal generation circuit Tracer head stylus model Model Composite displacement amount Figure 2 (a) Figure 2 (b)

Claims (3)

[Claims] (1) In a pick feed control method in profiling machining in which a workpiece is machined by following a model, the inclination angle of the surface of the model is determined at the start of the pick feed, and when the inclination angle is greater than a predetermined value, the first plane is A pick-feed control method, comprising: performing pick-feeding on a second plane when the inclination angle is less than a predetermined value. (2) The pick feed control method according to claim 1, wherein the predetermined value of the inclination angle can be changed by setting. (3) The pick feed control method according to claim 1, wherein the first plane is an X-Y plane, and the second plane is a Y-Z plane.