JPS61114312A - Curved surface processing device - Google Patents

Abstract

PURPOSE:To attain the partial cutting of a curved surface and to avoid easily the cutter interference by forming a closed curve showing the boundary of the cut area on a 3-dimensional curved surface. CONSTITUTION:A conversational 3-dimensional graphic processing system contains a curve data memory 1 which stores a 3-dimensional closed curve showing the boundary of a given cut area and a curved surface data memory 2 which stores the curved surface data underwent the cutter offset and displays the curve and the curved surface at a display part 3. while the data of the memory 1 is converted 4 into the 2-dimensional curve data and stored to a curve data memory 5. The intersecting point calculation is carried out for a position read by a tablet, etc. at an intersecting point calculating part 7 via a spot conversion part 6. Then it is decided 8 whether said intersecting point is set inside or outside of the closed curve stored in the memory 5. The result of this decision is stored to a memory 9 and it is decided whether the result of the decision 8 and a middle point obtained by a middle point calculating part 14 is set inside or outside of said closed curve of the memory 5 to have comparison with a obtained series. Then a numerical control command is produced at a numerical control command producing part 16.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a numerically controlled processing device for three-dimensional curved surfaces, and in particular to a curved surface processing device suitable for processing partial regions of curved surfaces to avoid cutter interference with other curved surfaces. Regarding.

[Background of the invention]

A known method for cutting a partial region of a curved surface is to create a closed curve on the XY screen and cut the inside or outside of the closed curve. However, in order to accurately avoid cutter interference, it is necessary to set the intersection line of the cutter offset surfaces as the cutting range, so accurate machining could not be expected with the above-mentioned method.

[Purpose of the invention]

When it is necessary to process a partial area of a curved surface to avoid cutter interference or for other processing reasons, the present invention can
To provide a means for creating a closed curve 4I on a curved surface subjected to cutter offset processing and easily and precisely processing a partial region of the curved surface by simply specifying one side thereof.

[Summary of the invention]

Cutter interference is a serious problem when numerically controlling curved surfaces. What is cutter interference?When cutting a certain curved surface,
This refers to the phenomenon in which the cutter interferes with other curved surfaces, or in other words cuts into other curved surfaces. To avoid this, K must stop the movement of the cutter when it comes into contact with a curved surface other than the cutting surface.

The point that defines the position of the cutter is called the cutter drive point. The driving point P of a cutter commonly used for towing is shown in FIG. The coordinates of this driving point are output to the numerical control tape. In many cases, the driving point is set at the tip P' of the cutter, but p
/ is P (#) There is no essential difference because the Z value is only at a lower position by Rz. When the cutter moves in contact with a curved surface, the curved surface created by the drive point of the cutter is the cutter offset surface. The equation of the surface is S (u, v) = (5x
(u, v).

Sy (u, v), St (u, v)), the formula of cutter offset surface Sm (n, v
) is given by the following equation.

5t(u,v)=S(u,v)+&N(u,V)++
(R+-&)Nxy (u, y)N(u,v)
: Unit normal vector of the curved surface Nxy (u, v) :
Project N (u, v) onto the XY plane and unitize it into a vector R1: Cutter radius R3: Cutter radius R (see Fig. 1) The cutting surface is 8
+1% Curved surface that causes cutter interference when cutting this (
(hereinafter referred to as an interference surface) is designated as Sl. As shown in Figure 2, the cutter offset surface 5eat Sk of sow8t
When the drive point of the cutter is on the intersection line of m, the cutter touches both surfaces.

Therefore, by stopping the cutter on this intersection line, cutter interference can be avoided. Generally, when a plurality of interference surfaces exist, intersection lines are determined for all the interference surfaces as shown in FIG. 3(A). Then, by interactively cutting the intersection line and extending it on the curved surface, a closed curve surrounding the area where no interference occurs is created as shown in FIG. 3(B). If it does not become a closed curve (partial figure), add a part of the curved surface boundary line to create a closed curve C(t) (part B) (Figure 3 (person).

(See (B)). The above is the method for creating the closed curve C(t) when cutter interference is avoided. There are other cases where partial area cutting is required for processing reasons, but the procedure for creating a closed curve is the same as the above method. Next, processing after the closed curve is created will be explained. First, the closed curve C(ri) is converted into a two-dimensional curve that takes values in the u, v parameter space of the curved surface.

That is, a curve is expressed by functions C,(t) and C,(t) such that u and v are determined when a curve parameter t is given.

For this reason, K finely samples the point P+ from the three-dimensional closed curve, f(u= v)= l P + Son (u, v
) p (11 represents the vector length, S・01 represents the cutter offset surface of the cutting surface)
Find it using the n method. These u and v are written as vF+vl. (u+
+Vj) is a two-dimensional spline closed curve, C'(t
) If you make t-this is what you want. Next, a method of specifying the cutting area will be explained. Stylus pen/,
Points specified with a coordinate input device such as a tablet correspond to points on the graphic screen. Since the graphic screen is two-dimensional, a point on it corresponds to an infinite straight line when viewed in the three-dimensional world coordinate system.

Therefore, by calculating the intersection between this infinite straight line and the cutter offset surface, the curved surface parameter u of the specified point
, v value can be determined. These u and v values are Po =
It is written as (uo + VQ). Po is a two-dimensional curve C'
It can be easily determined whether it is inside or outside (t). Specifically, it is known to draw an infinite half-line from PO and check the number of intersections, or to check the rotation angle of a straight line connecting points on P"0 and c'(g. It is determined whether the inside is to be the cutting area or the outside is to be the cutting area.

Next, a method of extracting only the portion existing inside the cutting area from the cutter path made on the curved surface will be explained. Like C'(t), the cutter path is also represented by a curve that takes values in the u and v spaces. The intersection between the cutter path and the closed curve c'(t) is calculated, and the cutter path is divided at the intersection. For each divided cutter path, it is determined whether or not it is inside the cutting area.

Numerical control commands are then created only for the portions that exist inside the cutting area. The above is an overview of the present invention.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. A curve data storage memory 1 stores a three-dimensional closed curve representing the boundary of a given cutting area.

Here, the curve stored in memory 1 is C+(t)=(
CIll (t), c+y(t), C+-(t)
) (+ = 1, n). 2 is a curved surface data storage memory that stores curved surface data subjected to cutter offset. Here, the curved surface stored in memory 2 is expressed as S(u, V)=(S, (u, vL s, (u,
v), s, (u, v)). 3 is a portion for displaying one surface of the memory 1 and 20 curves. Reference numeral 4 denotes a curve conversion portion that converts the three-dimensional curve data in the memory 1 into two-dimensional curve data that takes values for u and v. For the point (Pl) that is a finely sampled value of C+(t), f (u, v) = l PH-5(u, v) l
”(11 represents the vector length) uI, vj that minimizes Newton −1(op
The hson method is used to generate a spline curve passing through (uj, Vs). Reference numeral 5 denotes a curve data storage memory for storing the two-dimensional curve generated in the conversion section 4. The curve stored in the memory 5 is C'+ (t)=
It is expressed as (C+, (t), C+v (t)).

6 is a point conversion part that converts the position on the graphic screen read by the tablet or stylus pen into linear data in the three-dimensional world coordinate system. Since the screen is two-dimensional, a point on the screen corresponds to an infinite straight line in the three-dimensional world coordinate system. 7 is the intersection point of the straight line data sent from the conversion part 6 and the curved surface data stored in the memory 1, as u of the curved surface.
, This is the intersection calculation part that performs the process of calculating by the v value.

S(u, v) = p, +(Pl-P, )
Solving t using the Newton-Raphson method, u,
get v.

If you find multiple intersections, select the one closest to you on the screen. 8 is u obtained in intersection calculation part 7
, v is an inside/outside determination part that determines whether the point of the representation is inside or outside the closed curve stored in the memory 5.

The determination is made using the point Q obtained in the intersection calculation section 7 as shown in Figure 5.
Figure 5 (A) shows the case where the point Qo is inside the closed curve. Figure 5 (B) shows the case where the point Qo is outside the closed curve. The case is shown.If θ is 180°, Po is outside the closed curve, θ
>180°, it is determined that the object is inside. Reference numeral 9 denotes a memory that stores the judgment results of the judgment section 8. When it is inside the closed curve, n pieces of ``0@'' are stored, and when it is outside, it is @1'', corresponding to the number iK of the closed curve. Reference numeral 10 denotes a cutting data storage memory that stores cutting data necessary to generate a cutter path. In this embodiment, cutting data is input using a keyboard 1, and it is assumed that the distinction between whether the cutter path is created in the u or v direction of the curved surface and the pitch of the cutter path are memorized. . , 11 is a cutter path generation section that generates cutter paths one by one according to the conditions stored in the memory 1o. 12 is a two-dimensional closed curve stored in the memory 5;
This is the intersection calculation part for finding the intersection of the cutter paths. 13
is the cutter path dividing portion that divides the cutter path at the intersection point.

Reference numeral 14 denotes a midpoint calculation part for calculating the midpoint of the divided cutter path. 15 is a sequence of n numbers obtained as a result of determining whether the midpoint obtained in the midpoint calculation part 14 is inside or outside the closed curve C'+ (t) stored in the memory lJ5, This is a comparison section that compares n number sequences already stored in the memory 9. Reference numeral 16 denotes an NC command generating section that generates a numerical control command from the curved surface data in the memory 2 and the cutter path divided by the cutter path dividing section 13.

Here, it is assumed that the NC command generation section 16 operates only when the comparison section 15 compares the numerical sequences and they match.

The above is a detailed description of the present invention.

〔Effect of the invention〕

According to the present invention, it is possible to cut a partial area of the curved surface by creating a closed curve representing the boundary of the cutting area on the cubic surface. Therefore, it is possible to easily avoid cutter interference, and to reach the limit point where interference occurs. Since it can be cut, it has the characteristic of being able to cut accurately without leaving any marks.

[Brief explanation of drawings]

Figure 1 shows the drive point of the cutter, Figure 2 shows the cutter stop position to avoid cutter interference, Figure 3 shows the procedure for creating a closed curve on a curved surface, and Figure 4. 5 is a diagram showing the configuration of an embodiment of the present invention, and FIG. 5 is a diagram for explaining the function of the fourth prisoner 9. 1...Memory for storing closed curves created on a three-dimensional curved surface, 2...Memory for storing three-dimensional curved surface data, 3.
... A part that performs display processing of the curved surface 9 curves, 4... A part that converts the three-dimensional curve on the curved surface into a two-dimensional curve that takes values for the surface parameters u and v space function, 5... Two-dimensional curve Data storage memory, 6... Portion for converting points into infinite straight lines, 7
... An intersection calculation section between a three-dimensional curved surface and an infinite straight line, 8... A section that determines whether a point on a plane is inside or outside a closed curve, 9 ... 80 judgment results are 10" ,1
1" memory for storing cutting data; 10... memory for storing cutting data; 11... cutter path main component; 12... intersection calculation section between two-dimensional curve and two-dimensional straight line; 13... cutter path. Part to divide at the intersection, 14... Part to calculate the midpoint of two points, 15... Comparison of numbers. θεkey 36PO' I+lIl 2θC book O 11F

Claims (1)

[Claims] In an interactive 3D figure processing system equipped with a graphics display device, a coordinate input device is used to determine which side of the curved surface area to be the cutting area for a closed curve created on a 3D curved surface subjected to cutter offset processing. A curved surface machining device comprising a means for instructing, and a means for cutting a cutter path made on a curved surface by the closed curve, extracting only a portion belonging to the cutting area, and generating a numerical control command.