JPH05346814A - Three-dimensional machining method - Google Patents

Abstract

PURPOSE:To provide a machining method for setting an arbitrary one axis based on three-dimensional graphic data, and operating a two-dimensional cutting by moving a cutting tool along the pertinent one axis. CONSTITUTION:A curved surface #S<r> is prepared by correcting a cut curved surface #S by the radius (r) of the cutting tool. Then, an intersected line between the pertinent corrected curved surface #S<r> and a plane (gamma) on which the center of the cutting tool is positioned is computed. The cutting tool is moved by using the computed intersected line as the center of the cutting tool. That is, one axis is fixed based on the three-dimensional data, a central traveling to the other two axes is decided, and cutting data are prepared.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a machining method for performing three-dimensional machining with a machine tool such as a milling machine, and more particularly to arithmetic control of a cutting movement center locus of a tool.

[0002]

2. Description of the Related Art In recent years, various attempts have been made to use a computer to perform three-dimensional processing on a metal material, which have been put to practical use. The main method is the X axis, Y
This is a method in which the computer stores the information for each point of the axis and Z axis, and the control device reads this information to perform machining while moving the blade and / or the workpiece (Technical Review Co., Ltd .: NC machine tool utilization See handbook).

However, this method requires a large amount of information to be stored in the computer, complicates the input work, and requires a large-capacity computer.
A 16-bit or 36-bit processor, which can be handled relatively easily, cannot be used.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to set an arbitrary one axis on a workpiece with a relatively small amount of information and perform two-dimensional cutting on the other two axes. It is to provide a three-dimensional processing method that can be performed. In order to achieve the above object, the three-dimensional processing method according to the present invention inputs three-dimensional graphic data to a computer in advance, sets an arbitrary one axis for the input graphic data, and cuts a curved surface. A correction curved surface in which the center of movement of the tool exists is generated. Next, an intersection line between the correction curved surface and a constant plane where the movement center of the cutting tool exists is calculated, and the cutting tool is moved along this intersection line.

The fixed plane is a plane on which the movement center locus (center running) of the cutting tool is located, and this plane is X.
It may be set on any of the Y, XZ, and YZ planes, in other words, on any of them, and at this time, the center running is a two-dimensional curve defined by two axes. In the present invention, since the three-dimensional graphic information is treated as two-dimensional information of other two axes with respect to an arbitrary one axis, the amount of information is smaller than that of the conventional processing method of directly processing the three-dimensional information, and the cutting speed is high. Is improved. Further, one axis serving as a reference can be arbitrarily converted, and even if it is cut in any direction, it can be processed into a fixed curved surface.

[0006]

Embodiments of the processing method according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a schematic configuration of the apparatus, in which a machine tool main body 1 is provided with a table 3 on a base 2 and a machining head 5 having a cutting tool 6 mounted on a column 4. Table 3 is an X-axis DC motor 10
And the Y-axis DC motor 11 moves in the X-axis direction and the Y-axis direction, and the machining head 5 is driven in the Z-axis direction by the Z-axis DC motor 12. Speed control is for each motor 10, 11, 12
This is performed by outputting a control signal from each of the control units 15, 16 and 17.

On the other hand, the input / control system is composed of a 16-bit computer 20, a tape reader 21, and a control panel 22. The tape reader 21 reads NC data defined by JIS (Japanese Industrial Standard), particularly G code as a program format. The control panel 22 includes a machine operation panel 23 and a CPU 24, and NC data from the computer 20 and the tape reader 21 is input to an input port a of the CPU 24. Also, C
Control signals are output to the control units 15, 16 and 17 from the output ports b, c and d of the PU 24.

In the computer 20, as shown in the flow chart of FIG. 2, graphic definition input (step S1) and motion definition input (step S2) are performed to create NC data (step S3). Input is performed using the keyboard, mouse, and tablet attached to the computer 20.
In the figure definition input, as shown in FIG. 4, the dimension data of the workpiece 35 is inputted as three plane figures (adding other data if necessary) based on the trigonometric projection method. As the motion definition input, a three-dimensional perspective view of the workpiece 35 obtained by the graphic definition input captured from an arbitrary angle is created, and the computer 20
Displayed on the screen. In this step S2, by inputting the rotation center axis, rotation angle, etc. to the computer 20,
The three-dimensional perspective view shown in FIG. 5 is obtained. And any one
Along the axis, for example, the Z-axis, it is divided into a number of cross-sections shown by thin lines in FIG. The division plane is represented as two-dimensional information having the X axis and the Y axis as coordinate axes. The density of division can be set arbitrarily. Considering a certain divided surface, the grinding point can be specified by the two-dimensional information of the starting point a, the intermediate points b and c, and the ending point d (in this case, the ending point d is not necessary). In the conventional method of processing with three-dimensional information, each point on all trajectories passing through each point of a-b-c-d is represented by a three-dimensional coordinate system of X, Y and Z axes, and the memory capacity is Also needed a big one. However, according to the present invention, a very small number of two-dimensional information is required. Further, as shown in FIG. 6, a curve is plotted at a contact point or an intersection if it is a circular arc, and at a node if it is a free curve. Specifically, arcs e, f having the same curvature,
Organize as two-dimensional information including a start point and an end point for each g.
Of course, if it is composed of one circular arc, the two-dimensional information of the divided surface is defined by one expression representing the starting point, the end point and the circular arc.

The above two-dimensional information is combined with the G code read by the tape reader 21 to obtain C data as NC data.
It is input to the PU 24. As shown in FIG. 3, the CPU 24 has a language processor 25, a route determination processor 26, a geometric calculation processor 27, and a servo processor 28,
A control signal for moving the table 3 and the processing head 5 in the X-axis, Y-axis, and Z-axis directions is output to each of the control units 15, 16 and 17 based on the input NC data. The output from the servo processor 28 is an FM (feed magnet) signal, a BM (before magnet) signal, a PS
(Pulse start) signal and data signal. These signals drive the DC motors 10, 11, 12 via the control units 15, 16, 17 to move the table 3 and the cutting tool 6 in the X-axis, Y-axis, and Z-axis directions. The fixed work piece is cut into a predetermined shape.

Next, the generation of cutting data by the CPU 24 will be described in detail. Usually, a curved surface cut by the traveling of the cutting tool, that is, a trajectory of a contact point where the cutting tool contacts the curved surface is referred to as cutting traveling, and a movement center (curvature center of a tool tip portion) trajectory of the cutting tool is referred to as center traveling. Cutting is performed with reference to either cutting traveling or center traveling, and is roughly classified into three-axis cutting and 2.5-axis cutting.

Triaxial cutting refers to the case where the cutting run is on a constant plane. On the other hand, the 2.5-axis cutting refers to the case where the center travel is on a constant plane γ. As shown in FIG. 7, in the 2.5-axis cutting, first, a curved surface #S ^r corrected by the radius r of the cutting tool is generated for the cutting curved surface #S, and the curved surface #S ^r and the running center exist. The basis is to determine the line of intersection (centering) with a constant plane γ. In this embodiment, such 2.5 axis cutting is performed.

[0012] Specifically, curved #S ^r corrected by the radius r with respect to the cutting curved #S, relative to an arbitrary point P on the curved surface #S, points represented by the following formula (1) It becomes a curved surface stretched by P ^r . P ^r = P + rN (1) N is a normal vector of the curved surface #S at P In this case, the correction point P ^r for the point P satisfies the following expression (2).

| P−P ^r | = r (2) By the way, for one curved surface, which is also a smooth curved surface with few undulations, the correction curved surface is determined as described above. However, when one shape is generated by combining a curved surface having a lot of undulations or a plurality of curved surfaces, the corrected curved surface cannot be determined by the above equation (1).

As shown in FIG. 8, in the curved surface #S having a lot of undulations, the correction point P ^r may not be able to keep the distance of the radius r with respect to the point P ′ on the curved surface #S. | P′−P ^r | <r (3) Therefore, regarding the curved surface #S having many undulations, it is necessary to determine whether or not the state shown in the above equation (3) has occurred in the entire surface of the curved surface #S. is there. That is, in this embodiment, the corrected curved surface #S ^r is generated by satisfying the following expression (4) for all the points P on the curved surface #S.

| P−P ^r | ≧ r (4) Next, continuous cutting of the compound curved surface will be described. Two curved surfaces # I, when performing continuous cutting against # J, respective correction curved #I ^r by the radius r of the cutting tool, # J ^r is obtained. As shown in FIG. 9, these correction surface #
There are two sides when I ^r and #J ^r intersect, and which side to cut becomes a problem. That is, whether the curved surfaces #I and #J, which are divided into and at the intersection point C, are to be cut with − or −. In this embodiment, the curved # I, giving judgment side to be cut with respect to # J, correction curved #I ^r, also determines the side against # J ^r.

By the way, as shown in FIG. 10, when the two cutting curved # I, # J are crossed, their correction curved #I ^r, the # J ^r in some cases the line of intersection does not exist. In this case, the correction curved #I ^r, intersection line between # J ^r and center path plane γ does not become continuous curve, thus divided into two curves. In such a case, the correction curved surfaces #I ^r and #J ^r are connected to perform cutting. However, if the connecting method is wrong, excessive cutting or uncutting occurs near the intersection of the curved surfaces #I and #J. Considering only the intersection line of the curved surfaces #I and #J, a method is conceivable in which the two curves are connected by the intersection of their extension and the central traveling plane γ. However, in this case, there must be an intersection line between the two curved surfaces #I ^r and #J ^r and the central traveling plane γ. Therefore, the center traveling plane γ is the corrected curved surface #
This method is not effective when passing through the gap between I ^r and #J ^r .

In this embodiment, the cut curved surfaces #I and #J are used.
The fully extended, corrected curved #I ^r, so that intersection # J ^r. That is, the cutting curved surfaces are not bounded, and they are sufficiently extended. Specifically, the curved surface is regarded as the correspondence S from (0,1) × (0,1) to the point P. That is, 0 ≦ λ, μ ≦ 1
On the other hand, (λ, μ) is regarded as a correspondence to P = (x, y, z) (5).

Here, the curved surface S may be differentiable (continuous). For a curved surface S with 0 ≦ λ and μ ≦ 1,
S '(λ, μ) = S (λ, μ) (6) S'is differentiable by satisfying the following formula (6). S'is extended to a range satisfying the following formulas (7) and (8).

Λ ₀ ≦ λ ≦ λ ₁ (7) μ ₀ ≦ μ ≦ μ ₁ (8) By the way, if the central traveling plane γ is set to any of the XY, XZ, and YZ planes, the central traveling is performed. Is a two-dimensional curve defined by two axes. That is, one of the X, Y, and Z axes is fixed. The cutting at this time can be treated as two-dimensional cutting. By handling in this way, it becomes possible to represent the center running not only by a straight line but also by a circular arc.

In this embodiment, if point P ₂ exists on the straight line determined by points P ₀ and P ₁ , P ₁ is deleted, and on the arc determined by points P ₀ , P ₁ and P _2. If there is a point P _{3 at} , the cutting data can be reduced by repeatedly deleting the points P ₁ and P _2, and the cutting speed can be improved. Next, the axis conversion will be described.

In the present embodiment, a workpiece is input as a three-dimensional figure as shown in FIG. 4, an arbitrary axis is set, and two-dimensional cutting is performed with the center running along this axis.
Then, the reference one axis can be set in any direction, and the figure data may be input by any method as long as it is three-dimensional data.

That is, in the embodiment, one axis is fixed with respect to the obtained graphic data, the center running with respect to the other two axes is determined, and cutting data is generated. Generation of cutting data is 2.5
It is as explained in the axis cutting, and in the following it will be the reference 1
The arbitrary transformation of the axis will be described in detail. As shown in FIG. 11, the curved surface can be represented by parameters in the λ direction and the μ direction. The cutting data (center running) becomes a curve on the correction curved surface for this curved surface. The obtained cutting data is taken as a λ-curve with bi = bi (λ) (9) 0 ≦ λ ≦ 1. At this time, for λ,

[0023]

[Equation 1]

A μ-curve can be defined as As a result, the corrected curved surface for the specific curved surface is defined by the λ-curve and the μ-curve. The correction curved surface defined here is a curved surface on which the center of the cutting tool exists, and the intersection line between this correction curved surface and the plane γ may be the center travel of the cutting tool. Since the correction curved surface is defined in the λ direction and the μ direction, the line of intersection between the correction curved surface and the plane γ is determined. Moreover, the correction curved surface in this embodiment is the same as the above-mentioned 2.
As described in the 5-axis cutting, it is generated so as to satisfy the above expression (4), and if the cutting tool moves around a curve on such a corrected curved surface as a center running, interference (overcutting) will occur. There is no fear, and it can be cut as a continuous one-axis fixed two-dimensional curve. Also, it goes without saying that one axis to be fixed can be arbitrarily converted.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a cutting device for carrying out a processing method according to the present invention.

FIG. 2 is a flow chart of a processing process by the cutting device.

FIG. 3 is a block diagram showing a circuit of a CPU.

FIG. 4 is a trihedral view showing a cut figure.

FIG. 5 is a perspective view showing the cutting figure of FIG. 4.

FIG. 6 is an explanatory view of curved surface processing.

FIG. 7 is an explanatory diagram of correction curved surface generation in 2.5-axis cutting.

FIG. 8 is an explanatory diagram of generation of a corrected curved surface for a curved surface with many undulations.

FIG. 9 is an explanatory diagram of correction curved surface generation for a compound curved surface.

FIG. 10 is an explanatory diagram of correction curved surface generation for a compound curved surface.

FIG. 11 is an explanatory diagram of curved surface representation.

[Explanation of symbols]

 1 ... Machine tool main body 3 ... Table 5 ... Machining head 6 ... Cutting tool 20 ... Computer 24 ... CPU

Claims (1)

[Claims] 1. An X-axis and a Y that are orthogonal to each other with respect to a workpiece.
In the machining method that performs 3D machining including axis and Z axis, there is a movement center of a tool that inputs 3D graphic data, sets an arbitrary 1 axis for the input graphic data, and cuts a curved surface. A three-dimensional machining characterized in that a corrected curved surface is generated, an intersecting line between the corrected curved surface and a constant plane where the moving center of the cutting tool exists, and the cutting tool is moved along the intersecting line. Method.