JPH03125201A - Nc data generating system for cutting of curved surface - Google Patents

Abstract

PURPOSE:To secure the maximum dimensional accuracy within a range where no cut-in pnenomenon occurs by replacing the diameter of a concave circular arc with the cutter diameter and defining automatically again a concave circular arc of the least size where no cut-in phenomenon occurs when a cutter diameter is designated in a size larger than a concave circular arc defined by the curved surface cutting information which is obtained previously. CONSTITUTION:A designated working cutter diameter is inputted to an automatic programming device together with the curved surface cutting information obtained previously. The programming device detects a concave circular arc 30 defined by the curved surface cutting information and compares the size of the arc 30 with the working cutter diameter (r). When the former size is smaller than the latter one, the diameter of the arc 30 is replaced with the diameter (r) and the curved surface cutting information is defined again. Then the working path of the cutter is calculated based on the redefined cutting information. As a result, a cut-in phenomenon can be prevented regardless of the size of the diameter (r). Then the shape precision of a work is maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an NC data creation method for cutting a curved surface.

Conventional technology By specifying the cutter diameter for machining along with the curved surface cutting information created in advance and manually inputting it to the automatic programming device,
An NC data creation method that automatically calculates NC data for machining a curved surface defined by the curved surface cutting information, ie, NC data indicating a machining path of a cutter, is already known.

In order to calculate the machining path of the cutter based on the curved surface cutting information, it is necessary to consider the amount of offset between the cutter as a tool and the curved surface defined by the above curved surface cutting information. When cutting, the NC data of the machining path calculated by the automatic programming device is
Usually it will be something like this:

[When the cutter diameter is smaller than the diameter of the concave arc] Figures 3 and 6 show that the cutter radius r is 10.2 mm on a flat or curved surface.
This is an example showing the machining path P when the radius R of the concave arc 30 that connects the Let Rr be the portion of the machining path P that cuts the inside, that is, the radius of the concave arc 40, and
By aligning the center of curvature of the concave arc 40 with the center of curvature 0 of the concave arc 30, the locus of movement of the cutter tip completely matches the shape of the concave arc 30, and it is possible to precisely cut a flat or curved surface 10.20 and the concave arc 30. Can be processed.

Therefore, the automatic programming device uses the following information as NC data for machining the curved surface defined by the curved surface cutting information.
The machining path P of the cutter is calculated in consideration of the amount of offset.

[When the cutter diameter is equal to or larger than the diameter of the concave arc]

In this case, as is clear from FIG. 6, the concave arc 40
The radius of R-r (≦0) cannot be set, and it is impossible to process the concave arc 30 using the above method.

In such a case, the automatic programming device will
As shown in FIG. 4, as NC data for performing processing that approximates the shape of Move to a point Q1' whose normal distance is equal to the offset ff1r, and further move to a point Q whose normal distance from the definition end point Q2 of the concave arc 30 is equal to the offset amount r.
2', there is an offset i between the plane and the curved surface 20.
The machining path P of the cutter that moves while maintaining r is calculated, but if the cutter radius r is larger than the radius R of the concave arc 30, the cutter radius r is larger than the radius R of the concave arc 30.
There is a drawback that a cut-out 50 occurs in the connecting portion of the 0, making it impossible to maintain the shape accuracy of the workpiece.

Problems to be Solved by the Invention Therefore, the purpose of the present invention is to eliminate the drawbacks of the above-mentioned prior art, prevent the occurrence of gouges regardless of the specified cutter diameter, and improve the shape accuracy of the workpiece. The object of the present invention is to provide an NC data creation method that can maintain the following.

Means for Solving the Problems The NC data creation method of the present invention reads curved surface cutting information created in advance and a designated machining cutter diameter into an automatic programming device, and generates a concave arc defined by the curved surface cutting information. Detect and compare the size with the machining cutter diameter, and if the machining cutter diameter is larger, replace the diameter of the concave arc with the cutter diameter, redefine the curved surface cutting information, and redefine the curved surface cutting information. The above objective was achieved by calculating the machining path of the machining cutter based on the defined curved surface cutting information.

Operation: Specify the machining cutter diameter along with the curved surface cutting information created in advance and input it into the automatic programming device.

The automatic programming device detects the concave arc defined by the curved surface cutting information, compares the size with the machining cutter diameter, and if the machining cutter diameter is larger, sets the diameter of the concave arc to the cutter diameter. The curved surface cutting information is replaced and the curved surface cutting information is redefined, and the processing path of the processing cutter is calculated based on the redefined curved surface cutting information.

Example Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 2 is a block diagram showing the main parts of an automatic programming device according to an embodiment of the present invention, in which 1 is a processor (hereinafter referred to as CPU), and 2 is a control program for controlling the automatic programming device. Stored ROM,
3 is R for storing various system programs loaded from the floppy disk FL, CPU calculation results, etc.
A.M.

4 is an NC data storage memory for storing created NC data; 5 is a keyboard; 6 is a disk controller; 7
is a graphic display (hereinafter referred to as CRT), and each of these elements 1 to 7 are connected by a bus 8.

Note that the configuration of the automatic programming device is well known, and the details will be omitted.

The NC data creation method of this embodiment will be described below with reference to a flowchart (FIG. 1) showing a process for converting a part program for cutting a cubic surface into NC data.

The operator first specifies the machining cutter diameter r along with curved surface cutting information that defines the curved surface shape, and inputs this into the automatic programming device as a part program. This process is
As before, the program is executed by inputting the automatic programming language (FAPT) settings via the keyboard 5.

The CPU reads this part program and stores it in RAM3.
In step S1), the stored curved surface cutting information is analyzed to determine whether or not there is a concave arc defined by the curved surface cutting information.In step S2), if at least one concave arc exists, , the diameter of each concave arc is compared with the designated cutter diameter r; step S3); if the designated cutter diameter r is larger than the diameter of the concave arc, the diameter of each concave arc is compared with the designated cutter diameter r; By replacing it with the radius r, the curved surface cutting information in RAM3 is redefined (step S
4).

Note that if it is determined in step S2 that there is no concave arc, and even if there is a concave arc, in step S3, the diameter of each concave arc is set to the specified cutter diameter r.
If it is determined that the value is equal to or larger than , the process of step S4 is not executed.

Therefore, through the processing from step 82 to step S4, all the diameters of the concave arcs having a diameter smaller than the cutter diameter r are replaced by the cutter diameter r, and the diameters of the concave arcs having a diameter larger than the cutter diameter r are replaced with the cutter diameter r. It will be held at the value defined by the curved surface cutting information.

Next, the CPU moves to step S5, calculates the curved surface shape based on the curved surface cutting information redefined in the RAM 3, and automatically calculates the curved surface shape according to the specified cutter diameter r, as in the past. The NC data created by applying 3D offset to calculate the NC data that becomes the machining path of the cutter.
The data is output and stored in the NC data storage memory 4.

Therefore, for a concave arc whose diameter initially defined in the curved surface cutting information is larger than the cutter diameter r,
Similar to the conventional example shown in the figure, the movement locus of the cutter tip completely matches the shape of the concave arc defined by the curved surface cutting information.
NC data for accurately machining a flat or curved surface 10.20 and a concave arc 30 is created.

On the other hand, the diameter initially defined in the curved surface cutting information is the cutter diameter r
For concave arcs equal to or smaller than,
Since all of its diameters are redefined to be the same as the ivy diameter r, the redefined concave arc 30 as shown in FIG.
The normal line from the definition start point Qla of a and the normal line from the definition end point Q2a of the concave arc 30a substantially match at a point Q1'a (=Q2'a) located at a normal distance r,
Since the concave arc 30a is defined at a position substantially inscribed with the plane or curved surface 10.20, the concave arc 30a does not interfere with the plane or curved surface 10.20. Therefore, there is no occurrence of gouging as in the conventional example shown in FIG.
The shape accuracy of the workpiece is maintained.

Also, the diameter initially defined in the curved surface cutting information is the cutter diameter r
As for concave arcs smaller than , the diameter is replaced with the cutter diameter r without carelessly increasing the diameter, so maximum dimensional accuracy is guaranteed within the range where cutting does not occur.

Effects of the Invention According to the NC data creation method of the present invention, when a cutter diameter larger than a concave arc defined by curved surface cutting information created in advance is specified, the diameter of the concave arc is replaced with the cutter diameter. Since the concave arc of the minimum size at which no cutting occurs is automatically redefined, the shape accuracy will not be lost due to careless cutting due to input errors in the cutter diameter, etc. Maximum dimensional accuracy is guaranteed without causing any interference.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing an outline of NC data creation processing in an embodiment of the present invention, FIG. 2 is a block diagram showing main parts of an automatic programming device of an embodiment implementing the method of the present invention, and FIG. 3 and FIG. 6 is a conceptual diagram showing an example of the machining path when the cutter diameter is smaller than the diameter of the concave arc,
Figure 4 is a conceptual diagram showing an example of the machining path when the cutter diameter is larger than the diameter of the concave arc (conventional example), and Figure 5 shows the machining route when the cutter diameter is equal to or larger than the diameter of the concave arc. FIG. 2 is a conceptual diagram (present example) showing an example of a route. 1... Processor (CPU), 2... ROM. 3...RAM, 4...NC data storage memory, 5.
...Keyboard, 6...Disk controller, 7.
・Graphic display (CRT), 8...
Bus, 10.20...Flat or curved surface, 30...
Concave arc, 30a... Redefined concave arc, 50.
...Shaving.

Claims (1)

[Claims] Load the curved surface cutting information created in advance and the specified machining cutter diameter into an automatic programming device, detect the concave arc defined by the curved surface cutting information, compare the size with the machining cutter diameter, and start machining. If the cutter diameter for processing is larger, the diameter of the concave arc is replaced with the cutter diameter, the above curved surface cutting information is redefined, and the machining path of the processing cutter is determined based on the redefined curved surface cutting information. An NC data creation method for curved surface cutting characterized by calculation.