JPH0732980B2 - Three-dimensional shape processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is based on three-dimensional shape data obtained by following the surface of a model work with a tracing stylus. The present invention relates to the processing method.

(Prior Art) Conventionally, in order to easily and accurately machine a workpiece having the same shape as a model workpiece having a complicated shape, the measuring apparatus obtains the three-dimensional coordinates of the surface shape of the model workpiece, and the three-dimensional coordinate data is obtained. Based on this, processing data of a work is created (for example, Japanese Patent Laid-Open No. 60-135162).
(See the official gazette).

In this conventional device, since the feed rate of the tool for normally machining the workpiece is configured to be kept constant, it is necessary to set the feed rate of this tool according to the inclined surface portion with a large cutting resistance, There is a problem that workability is poor when processing a horizontal surface portion having a small cutting resistance.

(Object of the Invention) The present invention has been made to solve the above problems, and provides a three-dimensional processing method capable of efficiently and precisely surface-working a workpiece with a simple configuration. It is a thing.

(Structure of the Invention) The present invention obtains the displacement vector of the probe by copying the surface of the model work installed on the reference plane with the probe,
The tilt angle of the model work surface with respect to the reference plane is calculated based on this displacement vector, and the tool feed speed during machining of the work is changed according to the tilt angle.

According to the above configuration, while the feed rate of the tool is controlled so as to be the optimum speed according to the inclination angle of the model work surface with respect to the reference plane on which the model work is installed, the surface processing of the work is performed. Become.

(Example) FIG. 1 shows an example of a measuring apparatus used for carrying out the present invention. This measuring device includes a table 2 which constitutes a reference plane on which a work 1 is installed, guide rails 3 and 3 arranged on both left and right sides of the table 2, and front and rear along the guide rails 3 and 3. In the direction (Y-axis direction), a slider 5 that moves in the horizontal direction (X-axis direction) along the horizontal beam 4a of the gate-shaped column 4, and a vertical direction (longitudinal direction) along the slider 5. The tracer head 6 supported movably in the Z-axis direction, and the tracer head 6
And a stylus 7 as a probe provided at the lower end of the.

As shown in FIG. 2, the stylus 7 is supported so as to be displaceable in three-dimensional directions (X, Y, Z axis directions), and when contacted with the surface of the model work 1, the stylus 7 is displaced in the normal direction thereof. At the same time, the displacement component vectors εx, εy, εz of the stylus 7 are converted into electric signals by a differential transformer (not shown) provided in the tracer head 6. Then, when the surface of the model work 1 is imitated by the stylus 7, the slider 5, the gate column 4, the tracer head are arranged so that the combined vector ε of the displacement component vectors εx, εy, εz becomes constant. By controlling the moving speed of 6, the three-dimensional coordinates P (x, y, z) of the model work 1 are obtained, and the inclination angle θ of the surface of the model work 1 with respect to the reference plane is obtained. .

That is, the three-dimensional coordinate P is represented by the following equation, the installation position P ′ (X ′, Y ′, Z ′) of the slider 5, the gate column 4, and the tracer head 6 and the displacement vector ε of the stylus 7. It is calculated by the sum of (εx, εy, εz).

P (x, y, z) = P '(x', y ', z') + ε (εx, εy, ε
z) Further, as shown in FIG. 3, the inclination angle θ of the work surface at the coordinate P is similar to the triangle P′OP and the triangle POR, so the displacement vector εx of the stylus 7 in the X and Y directions. , εy synthetic component And the displacement vector in the Z direction | εz |, and can be calculated based on the following equation.

Next, the three-dimensional shape of the model work is measured by the above measuring device, and the method of processing the work surface by the NC machine or the like according to the measurement result will be described based on the process chart shown in FIG. First, the model work 1 is measured by the above measuring device.
Model work 1 based on the measurement result
The three-dimensional coordinates P and the inclination angle θ of the work surface are calculated. Then, the correction coefficient (appropriate feed rate / maximum feed rate) for controlling the feed rate of the tool in accordance with the tilt angle θ is read.

That is, the optimum feed rate of the tool for machining the work changes according to the inclination angle θ of the work surface with respect to the reference plane, and the relationship between the inclination angle θ and the optimum feed rate is obtained in advance based on experimental results. be able to. For example, when a ball end mill is used as the tool, as shown in FIG. 5, the smaller the inclination angle θ is, the more the optimum feed rate of the tool increases and the maximum feed rate approaches 2000 mm / min. In Fig. 5, curve A shows the characteristics of a tool with a diameter of 40 mm,
Curve B shows the characteristics of a tool with a diameter of 20 mm and curve C shows the characteristics of a tool with a diameter of 10 mm.

Then, based on the characteristic curve B, the relationship between the correction coefficient and the inclination angle θ when a tool having a diameter of 20 mm is used is obtained in advance as shown in the table below, and the correction according to the inclination angle θ is performed. The coefficient can be read.

Next, the optimum feed rate of the tool at each coordinate P is calculated based on the product of the above correction coefficient and the maximum feed rate, and this value is calculated.
It is output to the tool feed speed control unit such as an NC machine, and the surface of the work is machined by the tool while controlling the tool feed speed accordingly.

As described above, the inclination angle θ of the work surface at each coordinate P is calculated by copying the surface of the model work 1 by the measuring device, and the optimum feed rate of the tool is calculated based on the calculation result. Since the surface of the work is machined while controlling the feed speed of the tool, when machining the horizontal surface part of the work with a small inclination angle θ and a small cutting resistance, the feed speed of the tool is accelerated to perform the work efficiently. When processing the inclined surface part of the work that can be advanced and has a large inclination angle θ and large cutting resistance,
It is possible to precisely machine the work surface by reducing the feed rate of the tool.

Since the correction coefficient changes variously according to the type of tool, machining allowance, etc., it is possible to deal with each change by obtaining a value corresponding to each condition in advance. Further, in the above embodiment, the inclination angle θ is divided every 10 ° and the value of the correction coefficient is set, but the division angle can be variously changed as necessary. Further, based on the characteristic curve shown in FIG. 5, a correspondence table between the inclination angle θ and the tool feed rate may be created in advance, and the optimum tool feed rate at each coordinate P may be directly read.

Further, in the above-mentioned embodiment, an example in which a ball end mill capable of setting the feed speed of the tool to the maximum speed when processing the horizontal surface portion is used as the cutting tool has been described.
Not limited to this, various tools can be used, and in the tool configured so that the feed speed of the tool can be set to the maximum speed when processing the inclined surface portion at a predetermined angle, the above correction is performed accordingly. It may be configured to set the coefficient and the like.

(Effect of the invention) As described above, the present invention obtains the displacement vector of the tracing stylus by tracing the surface of the model work installed on the reference plane with the tracing stylus, and based on this displacement vector, with respect to the reference plane. Since the inclination angle of the model work surface is calculated and the tool feed rate during machining of the workpiece is changed according to this inclination angle, the cutting resistance decreases as the inclination angle decreases, such as with a ball end mill. For those that can increase the feed rate of the work surface, the tool feed rate can be increased when processing the horizontal surface part of the work surface to facilitate the work efficiently, and the tool can be used when processing the inclined surface part of the work surface. It is possible to perform control such that the feeding speed of the workpiece is reduced to enable precise machining on the surface of the workpiece.

Further, the feed rate can be controlled on the basis of the detected value of the probe for measuring the three-dimensional shape of the work without providing a separate control means or the like, so that the work can be efficiently performed with a simple configuration. Surface processing can be performed precisely.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a measuring apparatus used for carrying out the present invention, FIG. 2 is an enlarged perspective view showing a main part of the measuring apparatus, and FIG. 3 is an arrow line III-III in FIG. FIG. 4 is a process diagram showing the schematic structure of the present invention, and FIG. 5 is a characteristic diagram showing the relationship between the work surface inclination angle and the tool feed rate. 1 ... Model work, 7 ... Stylus (stylus), ε ... Displacement vector, θ ... Inclination angle.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G05B 19/416

Claims (1)

[Claims] 1. A displacement vector of a tracing stylus is obtained by tracing the surface of a model work set on a reference plane with a tracing stylus, and an inclination angle of the model work surface with respect to the reference plane is calculated based on the displacement vector. A method for machining a three-dimensional shape, characterized in that the tool feed speed during machining of the work is changed according to the inclination angle.