JPS6359601A - Numerical control working method - Google Patents

Abstract

PURPOSE:To work even parts, which are conventionally left unground, with numerical control by generating a circular arc whose radius is controlled and obtaining both end point positions and the center position of this circular arc to generate a fillet curved surface and performing the numerical control based on both end point positions and the center position of the curved surface. CONSTITUTION:If the unit direction vector going from a fillet circular arc center 7 to a fillet circular arc end point 8 is defined as C and that going from the fillet arc center 7 to a fillet circular arc end point 9 is defined as A, a unit direction vector B perpendicular to the vector A on the plane including vectors A and C is given in accordance with an equation 1. If the fillet circular arc center vector is defined so O and the fillet circular arc radius is defined as (r) and the angle to the line connecting the fillet circular arc center 7 and the fillet circular arc end point 9 is defined as theta, an optional point R(theta) on a fillet circular arc 10 is given with theta as the parameter in accordance with an equation 2. If the diameter of a grinding tool to working of the fillet circular arc 10 is defined as (t), a center position T(theta) of the grinding tool for working of the optical point on the fillet circular arc 10 is given in accordance with an equation 3.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a numerically controlled machining method, particularly when there are two free-form surfaces and the boundary of one free-form surface is limited.
The present invention relates to a numerically controlled machining method that enables machining of a fillet curved surface created between two free-form surfaces with a specified diameter.

[Conventional technology]

Conventionally, numerically controlled machining methods for fillet curved surfaces with constant or variable radii that occur between two free-form surfaces generate circular arcs that are in contact with both of the two free-form surfaces, as described in JP-A-58-160041. In this method, a fillet curved surface is generated by sequentially and smoothly connecting arc ends on one curved surface, and then numerical control commands are calculated.

If the boundary of the curved surface 1 is limited, an extended curved surface 26 is created on the curved surface that is an extension of the free-formed surface 1, and a fillet arc 24 with a radius r that touches both the extended curved surface 26 and the free-formed surface 1 is created.
was generated, the fillet arc center 21 and fillet arc end points 22 and 23 were calculated, and a fillet curved surface was generated. However, with this method, unerased portions 30 were generated, making it impossible to perform numerically controlled machining of the fillet curved surface, which is the object of the present invention.

The purpose of the present invention is to provide numerically controlled processing that can process a fitted curved surface with a specified radius that is generated between the two free-formed surfaces when there are two free-formed surfaces and the boundary of the free-formed surface on one side is limited. The purpose is to provide a method.

[Means for solving problems]

The present invention, which has achieved the above object, generates a fillet curved surface with a specified radius between two specified free-form surface shapes, and based on this, obtains a numerical command to drive a numerically controlled machine tool. In a numerically controlled machining method, a circular arc whose radius is controlled by a generation position that is perpendicular to a boundary line of a free-form surface shape with a limited boundary, is in contact with another free-form surface shape, and is an intersection with the boundary line, and A fillet curved surface is generated by determining the positions of both end points and the center position of the circular arc, a numerical control command is calculated based on the center position of both end points of the curved surface, and a numerically controlled machine tool is driven by the calculation result. This is a characteristic feature.

[Effect]

The circular arc is perpendicular to the boundary line of the free-form surface with a limited boundary, and touches the other free-form surface. As a result, the center position and both end point positions of the circular arc of the fillet curved surface are determined, so the center position coordinates of the tool for machining the fillet curved surface can be calculated based on these position coordinates, and the numerical control command can be calculated.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows the overall configuration, and two curved surface data 1 and 2 to which two curved surfaces to which a fillet curved surface is added are given as input data to the CPU 50. In the case of an analytical surface, this surface data is 5t(x, :/+ z)=Og 52(
x p V r z ) = O, and in the case of a free-form surface, the surface parameters U and V take integer values U,
It is given by the tangent vector of the grid point of V.

The CPU 50 obtains fillet curved surface data through the processing flow shown in the first round based on the first curved surface data and 2. The fillet surface data takes the same format as described above. Next, in order to drive the numerically controlled machine tool (hereinafter abbreviated as NG) 51 based on this fillet curved surface data, the CPU 50
Inside, the data 52 that controls the movement of the NG cutter is NC.
Sweep it out.

FIG. 1 is a flowchart shown to explain the overall operation of the present invention. @The first two specified “free-form surface data S (U, V)J” and “free-form surface boundary line data P
(U) and'' are calculated (step 200).

For the free-form surface data S (U, V), a vector system is calculated using the C00NS formula based on the position vectors of the four corner points of the curved surface and the tangent vectors at each of the four corner points.
It is given by the following equation using U and V as parameters.

S (U, V) = (A t tJ ” + A 2 U 2+ A
s U + A 4 ) V'+ (B I U'
+B2U2+BsU+B4)
V ”+ (CIU 8+ C2U ” + Cs
U + C4) V+ (DzU”+DzU”+Da
U+I) a) - (1) where A1 to D4: vector series 0≦U≦1, 0≦v≦1 On the other hand, boundary line data P (U) is the starting point of the boundary line.

A vector system is calculated based on the position vector of the end point and the tangent vector at each point, and is given by the following equation with U as a parameter.

P (U)=AUδ+BU"+CU+D...(
2) Here, A-D: Vector system 0≦U≦1 Next, based on the free-form surface data S (U, V)J, “boundary line data P (U)J” and “fillet arc radius data”, Calculate fillet surface data (step 20
1). Finally, a numerical control command for machining the bouillet curved surface is created based on the fillet curved surface data (step 2o2).

Next, the calculation method of fillet surface data is shown in Figures 3 and 4.
This will be explained using the flowchart shown in the figure.

First, fillet arc 10 according to curved surface machining accuracy.
The calculation score is calculated (step 300).

Next, a point at which a fillet arc is calculated on the boundary vAa of the free-form surface 1 is found, and the end point 8 of the fillet circle fi is determined, and an equation of a plane 4 perpendicular to the free-form surface 1 is found at the fillet arc end point 8 (step 301).

Next, the arc end point 8 of the fillet is
Calculate the curved surface offset by the fillet arc radius r at , find the intersection line 5 between this curved surface and the plane 4 (step 302), and calculate the intersection a6 on the free-form surface 2 corresponding to the intersection 5 (step 303) , then the intersection line 5
In the above, the point 7 whose distance from the fillet arc end point 8 is r is determined by convergence calculation, and the point 7 is set as the fillet arc center (step 304). Next, the fillet arc center 7 is
Calculate the foot point 9 of the perpendicular line drawn to the intersection line 6 from .

Set point 9 as fillet arc end point 9 (step 305)
,! & After, fillet arc center 7. Find the equation of the fillet arc 1°, which is the fillet arc end points 8 and 9 (
Step 306). If all the fillet arcs have not been calculated by applying the above calculation method to each point on the boundary m3 of the free-form surface 1, the process moves to step 301, but if the equations of all the fillet arcs have been calculated, the process ends. Then, the fitted surface can be calculated.

Next, a convergence calculation method for determining the fillet arc center 7 will be explained using FIG. 5 and with reference to FIG. 3. For the intersection RIA5 of the offset curved surface, a vector system is calculated based on the position vectors of the starting point 31 and the ending point 32 and the tangent vector at each point, and is given by the following equation with U as a parameter.

Q (U)=AU"+BU"+CU+D where A, B
, C, D: Vector system 0≦U≦1 First, set the value of U arbitrarily, and the intersection line 5 of the offset curved surface
Calculate the upper point Q (U) using the above formula.

Next, the distance between Q (U) and the fillet arc end point 8 is calculated. Compare whether 1Q-rl is less than or equal to the allowable tolerance ε. Here, r is the fillet arc radius. If it is within the allowable tolerance, Q (U) is set as the fillet arc center 7. If 1. If the allowable tolerance is exceeded, calculate a new U using the approximation formula uzu(12-r)/w,
Find the intersection of the new fillet surfaces, point Q(u) on i&5. Here, W is the distance between the starting point 31 and the ending point 326
Next, calculate the distance Ω between Q (u) and the fillet arc end point 8, and repeat the above comparison process.
-Repeat until rl is below the allowable tolerance.

A method of calculating numerical control commands for machining the fillet curved surface obtained by the above calculation method will be explained using the flowcharts of FIGS. 6 and 7.

In FIG. 6, if the unit direction vector from the fillet arc center 7 to the fillet arc end point 8 is C, and the unit direction vector from the fillet arc center 7 to the fillet arc end point 9 is A, then A on the plane containing A and C. The vertical unit directions B1 to B are given by the following equation.

(AXC)XA Here, 11 is the absolute value of the vector.

× represents a vector value.

If the fillet arc center vector is 0, the fillet arc radius is r, and the angle with respect to the straight line connecting the fillet arc center 7 and the fillet arc end point 9 is θ, then any point R(θ) on the fillet arc 10 can be calculated using θ as a parameter. It is given by the following formula.

R(0) =O+ rcosθA+r+inθB where R(θ) is the fillet arc equation.

When the diameter of the cutting tool for machining the fillet arc 10 is t, the center position [T (θ) of the cutting tool for machining any point on the fillet arc 10 is similarly given by the following equation.

T(θ) =O+(r-t) cosθA+(r-t
) sin θB Here, T(θ) is the equation of the center position of the cutting tool for fillet arc machining.

In FIG. 6, 41 is the center position of the cutting tool for machining the fillet arc end point 9, 43 is the center position of the cutting tool for machining the fillet arc end point 8, and fi42 is the angle θ
This is the center position of the cutting tool for machining the point. FIG. 7 is a flowchart for calculating numerically controlled machine commands for moving the cutting tool along the fillet arc 10 in the longitudinal direction in FIG. 3, that is, in the direction along the boundary line 3. FIG.

A movement command from point Pij to point Pij+1 changes the machine coordinates of the numerically controlled machine corresponding to point P1j to Mij(Xx.

Yl, Zl), the machine coordinates of the numerically controlled machine corresponding to point Pij+1 are M1j+1 (Xz, Yx, Zz
), it is given by the amount of movement in the X direction (Xs-Xt), the amount of movement in the Y direction (Y2°Yl), and the amount of movement in the Z direction CZx-Zs).

By calculating the numerical control command using the above procedure, 1
Processing becomes possible through numerical control of the fillet curved surface, which is the object of the present invention.

〔Effect of the invention〕

As described above, according to the present invention, even when there are two free-form surfaces and the boundary of the free-form surface on one side is limited, the fillet curved surface generated between the two free-form surfaces continuously changes the radius. can be calculated, which has the effect of allowing cylindrical areas, which previously had to be hand-finished due to the generation of uncut parts, to be machined by numerical control. Furthermore, according to the present invention, processing can be performed by numerical control, which has the effect of shortening processing time and improving processing accuracy. Further, when the present invention is applied to machining turbine blades and water turbine runner blades, there is an effect that performance and effects are improved as machining accuracy is improved.

[Brief explanation of drawings]

Fig. 1 is a flowchart shown to explain the overall operation of the present invention, Fig. 2 is a block diagram showing an example of the configuration of an apparatus for realizing the embodiment, and Fig. 3 is an outline of the calculation method of the embodiment of the present invention. FIG. 4 is a flowchart to explain the calculation procedure in FIG. 3, FIG. 5 is an explanatory diagram to explain the same, and FIG. Principle diagram showing the cutting tool-centered calculation method, No. 7
This figure is a flowchart showing the operation of obtaining a numerical control command based on the values obtained according to the principle of FIG. 6, and FIG. 8 is an explanatory diagram showing a comparison between the present invention and the conventional method. 1.2... Free-form surface, 3... Boundary line, 7... Fillet arc center, 8, 9... Fillet arc end point, 1
0...Fillet arc, 50...cpu, 51...
・Numerically controlled machine tools.

Claims (1)

[Claims] 1. In a numerical control machining method in which a fillet surface with a specified radius is generated between two specified free-form surface shapes, and a numerical command is determined based on this to drive a numerically controlled machine tool, boundary generates an arc whose radius is controlled by the generation position that is orthogonal to the boundary line of the limited free-form surface shape, touches the other free-form surface shape, and is the point of intersection with the boundary line, and determines the positions of both end points and the center of the arc. A numerical control machining method characterized in that a fillet curved surface is generated by determining the position, a numerical control command is calculated based on the positions of both end points and the center position of the curved surface, and a numerically controlled machine tool is driven by the calculation result.