JP2640467B2 - Numerical control unit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention controls the feed rate of a cutting tool, and more particularly, the feed rate of a numerical controller that controls the feed rate of a cutting tool when the end point of a machining block forms a corner. Control (hereinafter referred to as automatic corner override).

FIG. 3 is a block diagram of a conventional numerical controller. In FIG. 3, (1) is a central processing unit (hereinafter, referred to as a CPU), (2) is a memory composed of a ROM / RAM, etc.
Here, a control program, a machining program for machining a workpiece, and the like are stored. (3) a keyboard for inputting a machining program or the like into the memory (2) or operating a machine tool described later; (4) displaying a machining program and machining shape of a workpiece created by the machining program; A CRT display device for graphically displaying the input figure of the CRT; (5) a servo mechanism for converting the movement data corresponding to the machining program sent from the CPU (1) into the number of pulses for actually moving the servo motor; (6) Is a machine tool including a servomotor.

Next, the operation of a conventional numerical controller having an automatic corner override function will be described.

First, the operator inputs the coordinate values of, for example, the corners A, B, C, and D of the quadrangle shown in FIG. 4 from the keyboard (3) as the final machining shape Prf. Of the workpiece. Then, various conditions such as tools used for cutting are input. At this time, an override distance considering the sharpest corner A is also input. This distance is usually determined by guesswork rather than calculated.

Next, a data group including tool path data and various data necessary for machine operation is created for each processing block based on the data input as described above. In the processing block, the override distance is entered in the data group. Then, the CPU (1) operates according to the control program stored in the memory (2) to create a tool path corresponding to the final machining shape.

Therefore, according to the tool path, the machine tool (6)
Controlled by (1), the cutting tool (7) is moved by the servo mechanism (5) to cut the workpiece. In this cutting process, during the cutting of the working block, the feed speed of the cutting tool starts to be reduced when the remaining movement distance matches the override distance, and the cutting is performed until the block ends.
When this is completed, the process moves to the next processing block. In this way, the workpiece is cut to the final processed shape Prf.

[Problems to be Solved by the Invention] In the numerical controller as described above, when creating a tool path corresponding to the final machining shape Prf. Of the workpiece, each corner of the final machining shape Prf. Coordinates A, B,
Inputting C and D, inputting various conditions such as tools to be used for cutting, and inputting the override distance at the corner of the machining block having the sharpest corner. Is determined by guesswork, and even if the override distance is optimal for the machining block having the sharpest corner, the override distance is not appropriate for the corners of all other machining blocks. There is a problem that a meaningless override is applied depending on the corner portion of the block, which unnecessarily increases the processing time.

The present invention has been made to solve the above problems, and automatically calculates an optimum override distance for each corner portion of each processing block, and adjusts a processing tool to an appropriate feed speed at a corner portion of each processing block. An object is to obtain a numerical control device that can be controlled.

[Means for Solving the Problems] A numerical control device according to the present invention includes a tool path output unit that outputs a tool path created according to a machining shape and a tool diameter of a workpiece, and an end point of a machining block. A condition output means for outputting various conditions such as a corner shape, a tool diameter, and an allowance, a deceleration start point calculating means for calculating a deceleration start point from output data of the tool path output means and the condition output means, and a tool path. An override distance calculation means for calculating an override distance from output data of the output means and the deceleration start point calculation means, and a deceleration signal generation means for generating a deceleration signal when the deceleration start position is reached from the override distance and the remaining travel distance. It is what was constituted.

[Operation] In the present invention, when executing the tool path created corresponding to the machining shape and the tool diameter of the workpiece, the deceleration start point calculating means calculates the tool path output means and the condition output means from the data of the tool path output means and the condition output means. The position at which the cutting load increases due to the shape of the corner at the end point of the machining block, the tool diameter, and the machining allowance is calculated as the deceleration start point, and the override distance calculation means calculates the override distance from the output data of the tool path output means and the deceleration start point calculation means. Is calculated by the deceleration signal generating means, and the override distance and the remaining travel distance are compared. If the override distance and the remaining travel distance match, it is determined that the deceleration start position has been reached, and a deceleration signal is generated.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram of a numerical control device according to the present invention. In FIG. 1, (10) is a tool path output means for outputting a tool path of a cutting tool created in correspondence with a final machining shape and a tool diameter of a workpiece, and (11) is a corner portion at an end point of a machining block. (13) is a deceleration start point calculation for calculating a deceleration start point from output data of the tool path output means (10) and the condition output means (11). Means, (12) an override distance calculating means for calculating an override distance from output data of the tool path output means (10) and deceleration start point calculating means (13), and (14) a cutting tool feed distance during the machining of the machining block. A deceleration signal generating means for generating a deceleration signal when the remaining movement distance of X coincides with the override distance e calculated by the override distance calculating means (12), and (5) is a servo mechanism for driving the machine tool.

Next, the operation of the numerical control device according to the present invention will be described.

First, a keyboard not shown by the operator (FIG. 3 (3)
) To input various conditions such as the final machining shape of the workpiece and the tools used for cutting into a data input unit (not shown). The data input unit uses these input data to output contour data such as straight lines and circular arcs that constitute the final machining shape and tool diameter to the tool path output means (10), and sets a data group including various data necessary for machine control. Output to output means (11).

The tool path output means (10) forms an offset shape forming a tool path by performing a tool diameter correction on a contour data group such as a straight line or an arc forming the final machining shape input from the data input unit, and forms one block. Output each time. In addition, the condition output means (11), in addition to the tool diameter and the stock allowance of the tools used for cutting, input from the data input unit,
Outputs various conditions of the shape of the corner formed by the current block and the next block.

Next, the deceleration start point calculating means (13) calculates the deceleration start point P1 from the output data of the tool path output means and the condition output means as follows.

In FIG. 2, the broken line is the path (tool path) at the center of the tool, and when cutting is performed toward the corner A, the cutting tool (7) collides with the workpiece material at P1. The point P1 is a straight line obtained by applying a tool diameter / 2 offset to the inside of a straight line passing through the points A and D, that is, a straight line having an offset shape corresponding to the machining shapes A and D and a straight line passing through the points A and B. A straight line that is offset by adding the allowance and tool diameter / 2 (a straight line parallel to the offset shape straight line corresponding to machining shapes A and B)
Can be calculated by finding the intersection with.

If the deceleration start point P1 is obtained in this way, the block end point P2 of the tool path is obtained as the end point of the offset shape.
The optimum override distance can be obtained by obtaining the distance between the two points P1 and P2.

After the override distance calculating means (12) calculates the override distance e at the corner of each machining block, the deceleration signal output means (14) compares the remaining distance of the cutting tool feed distance with the override distance e.
When the workpiece is cut in accordance with the tool path under such control, the remaining travel distance is the output of the override distance calculating means (12) e (= P2−) during the cutting of the processing block in this cutting process. The deceleration signal output means (14) outputs a deceleration signal to the servo mechanism (5) when it coincides with P1). The servo mechanism (5) starts deceleration of the feed speed of the cutting tool, performs cutting while maintaining the overridden deceleration speed until the end of the processing block, and performs the next processing block according to a program command from which the override has been released from the start point. Processing at speed. When the cutting of one processing block is completed in this way, the processing moves to the next processing block, and the cutting is performed by the same operation as described above, and the workpiece is cut to its final processed shape.

As is well known, the override means that an external dial /
The speed is changed by multiplying by a magnification specified by a switch or a programmable controller. Here, the operation applied to the present invention will be described. When a deceleration start point and an override distance are obtained by calculation and a deceleration signal is output by a deceleration signal output means, an external dial provided on a machine operation panel or the like of a machine tool. The override value specified by the / switch or the programmable controller becomes valid, the specified magnification is multiplied by the speed specified on the machining program to change the speed, and the servo mechanism is controlled. Therefore, for example, the speed is reduced from the speed of 100% override (according to the machining program command) to the speed of 80%, and the machining is performed to the end point while maintaining this speed.

[Effects of the Invention] As described above, the present invention uses the data of the tool path output means and the condition output means by the deceleration start point calculating means when executing the tool path corresponding to the machining shape of the workpiece and the tool diameter. The position at which the cutting load increases due to the shape of the corner at the end point of the machining block, the tool diameter, and the machining allowance is calculated as the deceleration start point, and the override distance calculation means overrides the output from the tool path output means and the output data of the deceleration start point calculation means. Calculate the distance, and compare the override distance and the remaining travel distance with the deceleration signal generation means. When the override distance and the remaining travel distance match, determine that the deceleration start position has been reached and output the deceleration signal, and output the deceleration signal. Since the feed speed of the machining tool is controlled to be reduced at the corner, a high-speed cutting feed can be set during normal cutting, reducing machining time. , Work efficiency is increased. Also, where there is a large cutting load at the corner, the override distance is appropriate and the required distance is reliably decelerated, so no meaningless override is applied.
The processing time does not become unnecessarily long, and there is an effect that abnormal wear, breakage and the like of the tool are reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of a numerical control device according to the present invention, FIG. 2 is an explanatory diagram of a processing shape of a workpiece and an override distance calculation at a corner portion of a processing block, and FIG. 3 is a block diagram of a conventional numerical control device. FIG. 4 is an explanatory view showing the processing shape of the workpiece and the offset shape of the cutting tool. In the figure, (10) is tool path output means, (11) is condition output means, (12) is override distance calculation means, (1)
3) is a deceleration start point calculating means, and (14) is a deceleration signal generating means. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] 1. A tool path output means for outputting a tool path created in accordance with a machining shape and a tool diameter of a workpiece, and a shape of a corner formed by a current machining block and a next machining block in the tool path. Output means for outputting various conditions such as tool diameter and tool allowance, and deceleration start to calculate the deceleration start point of the corner part from the tool path of the tool path output means and the shape of the corner part of the condition output means, tool diameter and machining conditions Point calculation means, Override distance calculation means for calculating an override distance at a corner from the end point of the current machining block of the tool path of the tool path output means and the deceleration start point from the deceleration start point calculation means, And deceleration signal output means for outputting a deceleration signal when the remaining travel distance of the vehicle coincides with the override distance of the override distance calculation means. Numerical control apparatus according to symptoms.