JPS6042482B2 - Numerical control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a numerically controlled machining method in which numerical information is obtained through a copying operation and numerically controlled machining is performed in accordance with the information.

The tracer head is made to follow the model shape to perform a copying motion, the required points on the trajectory of the copying motion are sampled to obtain numerical information, and numerical control processing is performed according to the obtained numerical information. Controlled machining methods have the advantage of being able to process complex shapes that are difficult to quantify by calculation using ordinary numerical control equipment, so they have recently been applied to various fields and have been awarded prizes. has been done.

By the way, in this type of method, if the diameter of the stylus used to obtain numerical information through tracing operations is different from the diameter of the cutter during numerically controlled machining, errors may occur if machining is performed according to the obtained numerical information. Therefore, it is necessary to correct the tool diameter by the difference between the cutter diameter and the stylus diameter.
Conventionally, such tool diameter correction is performed by detecting the normal direction of the model shape from the displaced position of the tracer head, and recording the detected normal direction on a command tape as components Δx, Δy, and Δz of each axis. This was done by positioning the cutter at a position shifted in that direction by the difference between the cutter diameter and the stylus diameter during machining. However, in this conventional method, the detected normal direction contains errors due to the influence of the detection accuracy of the tracer head and the frictional force between the stylus and the model, so it is not necessary to actually correct the tool diameter. is performed correctly in the normal direction. Therefore, correction accuracy can only be guaranteed within a narrow range of tool diameter differences of about 1 to 27 dollars. Therefore, there are disadvantages and inconveniences such as having to obtain new numerical information when the tool diameter difference is larger than that, and there is a drawback that versatility is lacking. The present invention has improved the conventional drawbacks, and its purpose is to significantly expand the range in which tool diameter correction can be performed with high precision and to increase versatility.

Examples will be described in detail below. FIGS. 1 to 5 are diagrams showing the trajectory of a copying operation, etc., used to explain a method according to an embodiment of the present invention.

In this embodiment method, first, as shown in Fig. 1, a known diameter ψ
Trace the shape of the model MDL with the tracer head equipped with the stylus STl of No. 1.

The center locus of the stylus STl at this time is as shown by the curve C1. The first digitizing is this trajectory C
1, and store them in memory. The data is captured at intervals that allow the shape of the trajectory C1 to be recognized within the tolerance range, and this can be done by sampling at predetermined distances, or by, for example, the method shown in Figure 2. As shown, the straight line connecting the starting point P1 and the current position and the trajectory C1
Point P2 where the maximum distance from the point reaches a preset error amount Δ
It is possible to adopt a method in which point P2 is set as a data import point, and then this point P2 is used as a starting point, and data is subsequently imported in the same process. Next, as shown in Figure 3,
The shape of the same model ■le as before is now set to a known diameter ψ2 (in the illustration, ψ2〉ψ1 is shown, but it may be ψ2〈ψ1)
Copying is performed using a tracer head equipped with a stylus ST2. The center locus of the stylus ST2 at this time is shown by a curve C2. The second digitizing
For example, as shown in FIG. The current position on C2 and the point P on the trajectory C1 stored in the previous digitizing
Constantly detect the distance r from
In the case of 1, the mechanical positions of the illustrated points Ql, Q2, Q3, . . . Qn are stored in the memory as data. Further, the value of the vector q from point Qn to point Pn is calculated online or offline, and the value is stored in the memory in correspondence with point Qn. When the above processing is performed on the required surface of the model shape, the memory stores a trajectory C2 located at the minimum distance or a constant distance from the required point Pn on the trajectory C1.
The machine position of the upper point Qn and each value of the vector o are stored, and this becomes numerical information.

Note that actual storage in memory is performed at point Q as shown below.
n and each component of the machine coordinate system axis (for example, X, Y, Z axis) of the vector X. ．． ,yn,zn)ΔXn9ΔYn9Δ
Remember Zn. Next, when numerically controlled machining is performed using a cutter having a diameter of ψ8 in accordance with the above numerical information, the numerical control device positions the machine at the machine position Rn obtained by performing a gate calculation.

That is, position the center of the cutter from point R1 to point R2,
Next, point Pn-1 is positioned from point R2 to point R3.
Machining is continued while continuously issuing positioning commands from point Rn to point Rn. Note that the mechanical position of Rn is actually calculated by the following formula.The locus formed by Rl, R2,... As is clear, the tool radius correction is performed correctly because the curve C3 in the figure is located ψ8 away from the surface of the model MDL in the normal direction thereof.

However, in the method of the present invention, since there is no need to detect the normal direction of the model shape, there is no vector error associated with this, and the range in which tool diameter correction can be performed with high accuracy is greatly expanded.
FIG. 6 is a diagram used to explain another embodiment method of the present invention. In this embodiment method, the second digitizing is memorized by the first digitizing as shown in the figure. The machine position of the required point Qn is taken in as data to the extent that the shape of the trajectory C2 can be recognized within the tolerance, regardless of the machine position Pn, and this is temporarily stored in the memory.

Then, from this memorized point Qn and the point Pn memorized in the first digitizing, the point Pn closest to the point Qn,
For example, in the example shown in the sixth figure, for point Q, point P1 and point Q2
, find the point P2, etc., and find the vector λ? and both are recorded as numerical information on the numerical information recording medium as in the previous embodiment. In addition,
The other operations are the same as the method of the previous embodiment, and
By sequentially positioning the tool at points Rl, R2, . . . Rn given by the formula, the tool diameter is corrected and numerically controlled machining is performed. Although this embodiment method is relatively simple, in the process of obtaining numerical information, all points Pn and Q
A memory capacity sufficient to temporarily store n is required.
On the other hand, in the method of the previous embodiment, the obtained point Qn is the point Pn
can be written to the area in which it was stored, which has the advantage of requiring less memory capacity. FIG. 7 is a configuration diagram of main parts showing an example of an apparatus for carrying out the method of the present invention, in which MAC is a copying machine, CT is a cutter, TR is a tracer head, EX9εY9EZ is a displacement signal that is its output, ST is a stylus, 0L is the model, MX, MY, M
Z is the servo motor, PCX, PCY, PCZ are the position detectors, CONT is the copying control circuit, CNTX, CN'RY,
CNTZ is a reversible counter, DI is a data input device, ME
M is memory, MDI is manual data input device, FP is floppy disk storage device, ■ is tape puncher, CP
U is the processor, BUS is its bus, and T is the command tape.

The tracing control circuit CONT processes the displacement signals εX, εt, and ε2 from the tracer head TR and controls the servo motor MX so that their combined displacement position is equal to the reference displacement position.
, MY, and MZ to perform the well-known tracing operation, and the current position of the center coordinates of the stylus ST is determined by a reversible sensor corresponding to each axis that counts pulses from position detectors PCX, PCY, and PCZ. Counter CNTX, CNT
Displayed on Y, CNTZ.

Data is captured using reversible counters CNTX, CNTY,
This is done by the processor CPU reading the contents of CNTZ via the data input device DI, and these data are stored in the memory MEM.

Then, the machine position of point Qn-) and the value of vector QnPn obtained by a predetermined calculation are stored in a numerical information recording medium such as a floppy disk recording medium in the floppy disk storage device FP or a paper tape in the paper tape puncher TP. Ru.

It should be noted that an ordinary numerical control device can be used as the device that performs the calculation of equation (1) from the stored numerical information and performs numerically controlled machining. As explained above, in the present invention, the shape of the same model is scanned using the stylus of diameter ψ1 and ψ2, and the machine position of the required point Qn on the locus of one of the scanning operations and the point Qn is used to trace the shape of the other scanning operation. Vector Q to point Pn on the trajectory
Obtain the value of rlPn as numerical information, and based on this, ψ8
When numerically controlled machining is performed using a cutter with a diameter of
) Machining is performed while sequentially positioning the machine to the machine position Rn that satisfies the equation.Although it requires two copies, it does not include vector errors like the conventional method, so it is within the range where the tool diameter can be corrected with high precision. has the effect of significantly expanding the Therefore, if the present invention is applied to a numerically controlled machining method in which numerical information is obtained through a copying operation and numerically controlled machining is performed in accordance with that information, its versatility can be improved and it is very effective.
It should be noted that the present invention is not limited to the above embodiments, and can be modified in various ways. For example, in the above embodiments, Rn is determined by interpolation, but the diameter of the cutter used, etc. Rn may be determined by extrapolation based on the following relationship.

[Brief explanation of the drawing]

Figures 1 to 5 are diagrams showing the trajectory of the copying operation used to explain and explain a method according to one embodiment of the present invention, and Figure 6 is used to explain a method according to another embodiment of the present invention. Diagram, 7th
The figure is a diagram showing the configuration of essential parts of an example of an apparatus for carrying out the method of the present invention. ST, STl, ST2 are stylus, MDL is model, CONT is copying control circuit, MAC is copying machine, T
R is a tracer head, PCX, PCY, PCZ are position detectors, CNTX, CNTY, CN'Y7. is a reversible counter, MEM is a memory, TP is a tape puncher, FP is a floppy disk storage device, and CPU is a processor.

Claims (1)

[Claims] 1 Trace the model shape with a tracer head equipped with a stylus of known diameter ψ_1 and find a point P on the trajectory of the tracing movement.
The mechanical position of n is stored in the memory as data, and then the model shape is traced again with a tracer head equipped with a stylus of known diameter ψ_2, and a point on the locus of the tracing operation has a predetermined positional relationship with the Pn. Find the mechanical position of Qn and the vector from the point Qn to the above Pn ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ and record these as numerical information on a numerical information recording medium, and use a cutter with a diameter of ψ_8. When numerically controlled machining is performed according to the numerical information recorded on the numerical information recording medium, the center position of the cutter having a diameter of ψ_3 is determined by interpolating or extrapolating the vector ▲ which includes mathematical formulas, chemical formulas, tables, etc. A numerically controlled machining method characterized by determining the machine position through which the machine should pass and proceeding with machining while sequentially positioning at the machine position.