JPH0561516A - Numerical controller - Google Patents

Abstract

PURPOSE:To provide a numeral control NC device capable of the machining at a high speed and with high accuracy. CONSTITUTION:The NC device which interpolates the straight lines and curves and performs the machining control is provided with a tool locus production means which products the tool locus data from an NC program including the maching conditions and the parameter data, a shift command production means 17 which produces the shift command data from the tool locus data per each minute segment length, a shift command data storage means 18, and a position coordinate production means 19 which reads the shift command data out of the means 18 and produces the position coordinate data at every minute unit time to output these data to a servo control part 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a numerical control device (hereinafter referred to as NC device) for numerically controlling a processing machine.

[0002]

2. Description of the Related Art FIG. 14 is a schematic block diagram showing a conventional NC device. In FIG. 14, the NC device 30 inputs an NC program for processing a workpiece (hereinafter referred to as a work) from the host computer 31 via the communication line 40 to the NC program input section 32, and the NC program is input to the NC program input section 32.
The program is stored in the program storage unit 33.

When the NC device 30 starts to execute, the NC program analysis unit 34 reads the N program from the NC program storage unit 33.
The C program is read, converted into movement command data, and output to the pulse distributor 35. When I / O control is required, the NC program analysis unit 34 issues a command to the I / O control unit 37 to perform I / O control. On the other hand, the pulse distributing unit 35 creates a speed command pulse by distributing the movement command data based on the designated machining speed, and outputs the command pulse to the servo control unit 36.

The servo control unit 36 controls the processing machine 38 by the command pulse to move the work (not shown).
NC processing is performed on. Further, the position information 39 from the processing machine 38 is fed back to the servo control unit 36 and used for servo control. A large-capacity NC program that cannot be stored in the NC program storage unit 33 is
After being input from the external host computer 31 to the NC program input unit 32, it is directly input to the program analysis unit 34, and the subsequent processing is performed in the same manner as described above.

Next, the process of creating an NC program when a workpiece is machined by the NC device will be described by taking a case of machining a curved surface as an example. In the host computer 31, FIG.
The curved surface to be processed as shown in FIG.
1, the locus 151 is divided at an arbitrary pitch p,
The position of each point sequence q at the division point is calculated based on the expression representing the curved surface and the division pitch p. Then, each point sequence q is shown in FIG.
An NC program for instructing a linear movement or an arc movement as shown in FIG. 18 is created by connecting the minute line segments t approximated by the straight line or the arc shown in FIG. At this time, as shown in FIG. 16, the divided pitch is small (divided pitch p ₁ ).
In the case of the ideal curved surface 161 and the minute line segment error 16
2 is smaller than the trajectory error 163 when the pitch is large (divided pitch p ₂ ). Therefore, in order to improve the machining accuracy in the NC device, it has been required to create the NC program by making the division pitch of the ideal curved surface locus as small as possible.

[0006]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the C device, in the case of processing a curved surface with high accuracy, a method of finely dividing the ideal curved surface locus has been adopted. However, when this method is used, the pitch is increased, so that the data amount of the NC program continuously interpolated by the minute line segment becomes large.

On the other hand, since there is a limit to the amount of data that can be analyzed in a fixed time, the time required for analyzing the NC program increases as the pitch becomes finer and the amount of data increases as described above. Further, the processing speed by the NC program input from the host computer is limited by the communication speed of the communication line, but there is also a problem that using a high-speed communication line results in cost.

For the above reasons, there is a problem that the processing speed becomes slow and it takes a long time when processing with high accuracy.
It is an object of the present invention to provide an NC device capable of high-speed machining with high accuracy in consideration of the above problems.

[0009]

To achieve the above object, in the present invention, in a numerical controller for performing machining control by interpolating a straight line and a curve, a tool locus is calculated from an NC program including machining conditions of a workpiece and parameter data. Tool locus creating means for creating data, move command creating means for creating move command data per minute line segment length from the tool locus data, and storage means for storing the move command data,
Position coordinate creating means for reading the movement command data from the storage means to create position coordinate data for each minute unit time and for outputting the position coordinate data to the servo control section. I did it.

[0010]

In the present invention, the movement command data consisting of the component (parameter) having the relationship between the tool speed and the unit time for moving the length of the minute line segment from the tool trajectory data is given before the machining. Created by the creating means and stored in the storage means. Then, during processing, the position coordinate creating means sequentially reads the movement command data to calculate the components, creates position coordinate data for each minute unit time, and outputs the position coordinate data to the servo controller.

At this time, since the movement command data is premised on the calculation processing by the position coordinate creating means, the data amount can be small. In addition, since the position coordinate data is sequentially created during processing, the amount of data to be stored becomes small. Since the time required for the calculation process is short, the machining speed does not slow down even if the position coordinate data is sequentially created during machining. Further, since the minute unit time can be shortened, the position control characteristic is improved and the processing accuracy is improved.

Since the position coordinate data is created according to a minute unit time, it contains a component for controlling the processing speed.
Therefore, according to the present invention, the conventional process of converting the NC program into movement command data by the program analysis unit and then creating the speed command pulse based on the designated machining speed of the movement command data by the pulse distribution unit is not performed in the present invention. It becomes unnecessary. As a result, the time required for data processing can be shortened.

[0013]

1 is a schematic block diagram showing an embodiment of the present invention. In this embodiment, a parameter data creating means (not shown) for creating parameter data from an expression representing a shape of a work surface, a coefficient of the expression, a radius of a tool to be used, an NC device 1, A processing machine 22 for processing a work (not shown) in response to a signal from the NC device 1.

The processing process in this embodiment will be described below. The NC device 1 uses the parameter data input unit 1 in advance to interactively enter the parameter data before machining the workpiece.
It is input from 1 and stored in the parameter data storage unit 12. The NC program creating unit 13 reads the parameter data from the parameter data storage unit 12, creates an NC program including the curved surface portion based on the data as shown in FIG. 2, and stores it in the NC program storage unit 14. ..

In the creation of the NC program, the NC program part for machining curved surface parts other than straight lines and circular arcs is
As shown in the figure, an AS code T as a code similar to the G code and parameter data W including the processing conditions shown in FIG.
And is stored in the NC program storage unit 14. Therefore, the curved surface portion is not calculated and is stored as the shape data with the code T and the parameter data W.

The tool locus creation unit 15 forms tool locus data from the NC program stored in the NC program storage unit 14 and the parameter data stored in the parameter data storage unit 12, and the tool locus data storage unit 16 stores the tool locus data. Remember. FIG. 4 shows a part of the process of calculating the tool trajectory in the tool trajectory generator 15. In FIG. 4, an NC program locus 41 included in the NC program indicates a locus of a work reference, and the locus is drawn from the starting point A in the order of B, C, D, E, F, and A. The section from B to E shows the locus of the part that is processing the work. In the locus, A to B, E to F to A indicate linear movements, B to C and D to E indicate circular arc movements, and C to D indicate curved surface movements other than linear and circular arcs.

From the NC program locus 41 and the parameter data, the tool locus creating unit 15 determines the machining portions A to B and E to F by linear movement and the machining portions B to C and D to E by circular movement. A tool locus 42, which is a movement locus based on the tool (a locus in which the tool radius offset is taken into consideration), is calculated to create tool locus data. The passing points G to J of the tool locus 42 correspond to B to E of the NC program locus 41, respectively.

On the other hand, the HI section of the tool locus 42 corresponding to the machining portions C to D caused by the movement of the curved surface is represented by the tool locus code U and the parameter V of the curved surface as shown in FIG. At this time, the code U and the parameter V
Uses the code T and the parameter data W in the NC program without calculating the tool path for the section from H to I. In this way, the tool trajectory data 42 corresponding to the NC program trajectory 41 is created.

If there are adjacent straight line portions P ₁ -P ₂ and P ₂ -P ₃ in the tool path as shown in FIG. 6, connection arcs P ₄ -P ₅ are formed as shown in FIG. Then, the two straight line portions are connected to create tool trajectory data.
The tool locus data created as described above is stored in the tool locus data storage unit 16.

The movement command creating section 17 reads out the tool trajectory data from the tool trajectory data storage section 16, divides the tool trajectory into minute line segment lengths u as shown in FIG. Create move command data. At this time, for the curved surface portion of the tool trajectory data, a tool trajectory in which the tool radius offset is considered from the tool trajectory data including the curved surface code and the parameter as shown in FIG. Divide by to create movement command data for this minute line segment. In this case, the movement command creating unit 17
As shown in FIG. 10, a perpendicular is drawn from the NC program locus 101 to find a point offset by the tool radius r. Then, by connecting these points, a tool locus 102 is created, and at the same time, the tool locus corresponds to S _n , S _{n + 1} , and S _{n + 2 obtained} by dividing the tool locus by the length of the minute line segment.
The movement command data as shown in is created.

As described above, for the curved surface portion, the movement command generation unit 1 is used for both the tool locus generation and the division into minute line segment lengths.
7, the amount of NC program and tool trajectory data can be reduced, and the error is reduced. Therefore, data can be created accurately. Further, the length of the minute line segment is set to be a line segment length shorter than the minimum radius in the connecting arc as shown in FIG. 8 so that the vector change of the moving speed becomes small. Further, as shown in FIG. 12, the tool path 121 is divided at a predetermined pitch to divide the minute line segment S1.
When S1 to S6 are created, the directions are within a predetermined range and can be regarded as the same direction.
The compressed movement command data corresponding to one line segment L1 is converted to reduce the data amount. The movement command data thus obtained has a component (parameter) having a relationship between the tool speed and the unit time.

The movement command data storage unit 18 stores the movement command data created as described above. At the time of processing, the position coordinate creation unit 19 sequentially reads the move command data from the move command data storage unit 18 at the time of processing, creates the position coordinate data for each minute unit time, and the servo control unit 20.
Output to. At this time, when the position coordinate creating unit 19 reads the compression movement command data, it is developed as a plurality of line segments of the tool trajectory data to create the position coordinate data.
The position coordinate data is created by calculating the component having the relationship between the tool speed and the unit time.

The position coordinate creating section 19 also controls the processing machine 22 by issuing an input / output command to the I / O control section 21 if necessary. As described above, since the movement command data is premised on the calculation processing by the position coordinate creating means, the data amount can be small. Further, since the position coordinate data is created according to a minute unit time, it includes a component for controlling the processing speed, and therefore, the process of creating a speed command pulse based on the specified processing speed is unnecessary. As a result, the time required for data processing can be shortened.

The system of this embodiment is shown in FIG.
Although it is configured as an NC device including all functional blocks as shown in FIG. 13, the NC device and the host computer may be configured with different functions as shown in FIG.

[0025]

As described above, according to the present invention, the data processing time for numerical control can be shortened. Therefore, even if the amount of data increases for higher accuracy, high-speed processing becomes possible.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing an example of an NC program.

FIG. 3 is a diagram showing an example of parameter data used in the examples.

FIG. 4 is a diagram showing a part of a process of calculating a tool path.

FIG. 5 is a diagram showing a tool locus code and parameters created by a tool locus creating means.

FIG. 6 is a diagram showing two adjacent straight lines in a tool path.

FIG. 7 is a diagram showing a state in which two straight lines of a tool path are connected to each other via a connecting arc.

FIG. 8 is a diagram showing a state in which the tool path is divided into line segment lengths shorter than the minimum radius in the connecting arc.

FIG. 9 is a diagram showing a state in which the tool locus is divided into minute line segment lengths.

FIG. 10 is a diagram showing a tool radius offset method performed when the movement command creating unit gives an instruction for curved surface machining.

FIG. 11 is a diagram showing an example of movement command data.

FIG. 12 is a diagram showing a state in which a tool path is divided by minute line segments.

FIG. 13 is a schematic block diagram showing another embodiment of the present invention.

FIG. 14 is a schematic block diagram showing a conventional NC device.

FIG. 15 is a diagram showing a relationship between an ideal curved surface trajectory and a minute line segment.

FIG. 16 is a diagram showing a relationship between a trajectory pitch error generated between an ideal curved surface trajectory and a minute line segment and a division pitch.

FIG. 17 is a diagram showing an example of a conventional NC program for instructing the processing of a curved surface portion.

[Explanation of symbols]

 1 NC device 22 processing machine 30 NC device 38 processing machine

Claims (1)

[Claims] 1. A numerical controller for performing machining control by interpolating a straight line and a curve, a tool locus creating means for creating tool locus data from an NC program including machining conditions of a workpiece and parameter data, and the tool locus. Movement command creating means for creating movement command data per minute line segment length from data, storage means for storing the movement command data, and reading the movement command data from the storage means A numerical control device comprising: position coordinate creating means for creating position coordinate data for each unit time and outputting the position coordinate data to a servo control unit.