JP2995812B2 - Tool path generation method by numerical controller - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a tool trajectory generation method using a numerical controller, and more particularly, to a tool trajectory defined on an arbitrary plane on a three-dimensional surface defined by two two-dimensional curves. The present invention relates to a tool trajectory generation method by a numerical control device when processing a curve on a three-dimensional curved surface designated by projecting a plane curve onto a three-dimensional curved surface using a tool such as a ball end mill.

[Conventional technology]

Generally, in numerical control (hereinafter referred to as NC) machining, rough machining,
Finishing and multiple NC machining on the same curved surface, and use tools with different tool diameters due to problems such as machining time and surface accuracy. Therefore, it is necessary to define a curved surface according to the size of the tool.

Conventionally, with this type of NC device tool path generation method,
Define the curved surface to be machined in consideration of the correction of the tool diameter,
A tool trajectory is generated using position data and a tangent vector at each point obtained by dividing a path to be machined on this curved surface.

[Problems to be solved by the invention]

The above-described conventional tool path generation method using a numerical controller has a drawback that it is extremely difficult to define a curved surface in consideration of an offset because a curved surface must be specified in advance in consideration of a tool diameter correction amount. Was.

The object of the present invention is to define 3 by two two-dimensional curves.
When performing machining using a tool such as a ball end mill while controlling the curve on the specified three-dimensional surface by projecting a plane curve defined on an arbitrary plane onto the three-dimensional surface on the three-dimensional surface Another object of the present invention is to provide a tool trajectory generation method using an NC device including tool diameter correction.

[Means for solving the problem]

The tool path generation method by the numerical controller according to the present invention is based on 2
On a three-dimensional surface defined by the two two-dimensional curves, a plane curve defined on an arbitrary plane is projected on the three-dimensional surface to calculate a curve on the specified three-dimensional surface by a numerical controller. In a tool trajectory generation method based on a numerical control device that performs machining by controlling a tool based on a plurality of plane curve division points by dividing the plane curve for projecting onto the three-dimensional curved surface by a predetermined pitch amount. Means for calculating a three-dimensional curve division point by projecting the plane curve division point onto the three-dimensional surface; means for obtaining a normal vector to the three-dimensional surface at the three-dimensional curve division point; Means for determining an offset point on a three-dimensional curved surface based on the three-dimensional curve division point, the normal vector, and the diameter of a predetermined tool; and a connection vector between the normal vector and the plane curve at the plane curve division point. Means for determining a tangent vector of the three-dimensional curve at the three-dimensional curve division point, and sequentially determining the offset point and the point of the adjacent three-dimensional surface from the offset point on the three-dimensional curve and the tangent vector of the three-dimensional curve. Means for interpolating between them.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention, and FIGS. 2 (a), (b) and (c) are schematic views showing the principle of a tool trajectory generation method.

The embodiment of FIG. 1 comprises an input device 100, a tool path calculator 200, and an output device.
It comprises a data distributor 201, a normal vector calculator 202, an offset calculator 203, a tangent vector calculator 204, and an interpolator 205.

Next, a tool path generation method will be described with reference to FIGS. 2 (a), (b) and (c). First, in FIG. 2A, the two-dimensional curves l ₁ and l ₂ and the three-dimensional surface s ₁ determined by changing the two two-dimensional curves l ₁ and l ₂ and the figure on the projected plane s ₂ are shown. when tangent vector 'are given in the' p and 'point p on the closed curve l _3, the normal vector shown in the tangent vector and the second view (b) in the p and the point p points shapes on s _1, Point p _{1 where} p is offset according to the tool diameter
The following describes how to obtain the value. The two two-dimensional curves l ₁ ′ and l ₂ ′ forming the three-dimensional surface at the point p are shown in FIG.
Are obtained by changing the two two-dimensional curves l ₁ and l _2, and the position of the point p on s ₁ is obtained from the relationship of l ₁ ′ l ₂ ′. The tangent vector of the two-dimensional curve l ₁ ′ at the point p shown in FIG. 2B is defined as the tangent vector of l ₂ ′. As an example, consider the case plane s ₂ is the XY plane. 2 (a) and 2 (b), point positions p, p ', p ₁
And the vectors ,,, 'can be expressed as follows.

_{p = (p x, p y} , p z), p '= (p x, p y, 0), p 1 = (p 1x, p 1y, p 1t), = s x · u x + s y · u _y + s _z · u _z = t _x · u _x + t _y · u _y + t _z · u _x = n _x · u _x + n _y · u _y + n _z · u _z = qx · ux + qy · uy + qz · uz '= q _{x · u x + q y · u} y where p _x, p _y, p _z and s _x, s _y, s _z and t _x, t _y, t _z and
q _x and q _y are known constants. U _x , u _y , u _z are the x-axis, y-axis,
This is a unit vector in the z-axis direction. _{Further, p 1x, p 1y, p} 1z and _{n x, n y, n z} , q z is the unknown constants.

Here, the normal vector at point p on the 3-dimensional curved surface s ₁ is represented by equation (1).

= × (1) The distance on the coordinates in the x-axis, y-axis, and z-axis directions is expressed as follows.

n _x = s _y t _z −s _z t _y , n _y = s _z t _x −s _x t _z , nz = s _x ty _y −s
_{y ty} , and then the point p ₁ (x, y, z) where p is offset by the tool diameter using the normal vector, where r is the tool diameter (2)
It is expressed by an equation.

p ₁ (x, y, z) = p (x, y, z) + r · (2) The distance of this point p ₁ on the coordinates in the x-axis, y-axis, and z-axis directions is expressed as follows. You.

_{p 1x = P x + r ·} n x, p 1y = p y + r · n y, p 1z = p z + r · n
_z, the way the normal vector and the tangent vector at the point p on the 3-dimensional curved surface S ₁ is (3) relations equation holds.

_{· = N x q x + n} y q y + n z q z = 0 ... (3) Therefore qz is represented as (4).

_{q z = -1 / n z (} n x q x + n y q y) ... (4) (1) with - (4), it is an unknown constant, p ₁
(X, y, z) and are required. The p ₁ and calculation for obtaining the a three-dimensional curve on a curved surface at a specified pitch done for each point obtained by dividing, as p _1-i shown in FIG. 2 (c), q _1-i (I = 1,..., N), and these are connected by curve interpolation to obtain a tool path.

Next, the calculation function of each unit in FIG. 1 will be described. The tool trajectory calculator 200 divides the position of each point of the three-dimensional curve and the vector of the corresponding plane curve, and performs p _i , s _i , t _i , q
a data distributor 201 for _i output vector s _i of two curves constituting a curved surface, the normal direction vector n of the three-dimensional curved surface from t _i
a normal vector calculator 202 for calculating _i , tool diameters r and 3
An offset calculator 203 that calculates the dimension positions p _i and the normal vector n _i and a point on the curved surface offset p _1-i,
A tangent vector calculator 204 for obtaining a tangent vector direction q _i from the normal vector _ni and the projected tangent vector q ′ _i of the closed curve l ₃ ; an offset position p _1-i and a normal vector direction q
_The tool locus is calculated by the interpolator 205 from _i .

〔The invention's effect〕

As described above, in the present invention, by projecting a plane curve defined on an arbitrary plane onto a three-dimensional surface on a three-dimensional surface defined by two two-dimensional curves, the specified three-dimensional surface The curve can be calculated by a numerical controller to control a tool such as a ball end mill to perform machining. In addition, since the tool trajectory including the tool diameter correction amount is generated by designating the tool diameter, it is not necessary to redefine the curved surface every time the tool diameter is changed, so that there is an effect that the input relating to machining is simplified.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIGS. 2 (a), 2 (b) and 2 (c) are schematic diagrams for explaining a tool trajectory generating method of the embodiment. 100 input device, 200 tool path calculator, 201 data distributor, 202 normal vector calculator, 203 offset calculator, 204 tangent vector calculator, 205 interpolator , 300 …… Output device.

Claims (1)

(57) [Claims] 1. A plane curve defined on an arbitrary plane is projected onto a three-dimensional curved surface defined by two two-dimensional curves and a predetermined curve is formed along a three-dimensional curve which is a curve obtained on the three-dimensional curved surface. When performing machining with a tool, the three-dimensional curve is calculated by a numerical controller to generate a tool trajectory of the tool required for the machining, and machining is performed by controlling the tool based on the tool trajectory. In a tool path generation method by a numerical controller, means for dividing the plane curve by a predetermined pitch amount to obtain a plurality of plane curve division points on the plane curve, and projecting the plane curve on the three-dimensional curved surface And said 3
Means for obtaining a plurality of three-dimensional curve division points at positions corresponding to the positions of the plurality of plane curve division points on a three-dimensional curve obtained on a three-dimensional curved surface, and corresponding to the positions of the three-dimensional curve division points Means for determining the direction of the normal vector to the three-dimensional curved surface at each of the three-dimensional curve dividing points from the respective tangent vectors at the positions of the two two-dimensional curves, The positions of the plurality of offset points on the three-dimensional curved surface for correcting the tool diameter by the direction of the normal vector at the position of the three-dimensional curve division point and the diameter of the tool. And a direction of the normal vector of the three-dimensional curve division point and a direction of a tangent vector of the plane curve at the plane curve division point corresponding to the three-dimensional curve division point. Means for determining a direction of a tangent vector of the three-dimensional curve at a three-dimensional curve division point; and determining the tool trajectory from a position of the offset point on the three-dimensional curve and a direction of the tangent vector of the three-dimensional curve. Sequentially 3
Means for interpolating between adjacent ones of the plurality of offset points on the three-dimensional curved surface.