JP2505382B2 - Feed rate control method and device in numerical control - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a feed rate control method and apparatus in numerical control, and particularly, when the movement trajectory of a machining tool includes a partial arc portion and a circular circle portion, machining is performed with high precision and high speed. The present invention relates to a feed rate control method and device in numerical control.

[0002]

2. Description of the Related Art Advances in machining based on numerical control using a computer have made remarkable progress with the development of computer technology and numerical control methods. This development responds to the recent increase in the complexity of processing shapes of work pieces (in the fields of aircraft and automobiles) and the increase in speed. When a complicated curved surface shape is machined at a high speed, in addition to the increase in the arcuate portion of the machined shape, the arcuate machining is often used also in the straight corner portion. In linear machining, the machining tool only needs to move in a straight line, so it is possible to increase the machining tool speed up to the permissible feed rate of the machining device itself.However, in curved surface machining, the acceleration changes sharply in the arc of the curved surface. I can't speed up. This sudden change in acceleration is most noticeable at the point of change to arc machining-linear machining in the process of linear machining-arc machining-linear machining. Due to this change in acceleration, the movement of the machining tool, that is, the movement of the machine, fluctuates (hereinafter referred to as mechanical shock), and the machining accuracy decreases. Becomes

Conventionally, in order to perform such curved surface machining, when the machining tool moves from the linear machining section to the arc machining section, the feed speed is reduced to some extent as compared with the linear machining. When the radius of curvature of the circular arc portion (hereinafter referred to as the radius) is large, the change in deceleration of the feed speed is small, but the mechanical shock increases as the radius decreases, so the feed speed must be significantly reduced. . The deceleration change of the feed rate in the arc portion is designated by the numerical control program and is preset by the programmer.
Such deceleration machining is not limited to arc portion (partial arc portion) machining,
The same is done in the case of circular processing.

[0004]

As described above, in the conventional numerical control device, when a curved surface such as a partial circular arc or a circle is machined, fluctuations due to mechanical shock occur,
The feed rate is reduced to prevent a decrease in processing accuracy. However, during high-speed machining operation, when the motion trajectory shape of the machining tool is a straight circle and a partial arc, and when it is a circular circle, the difference in the shape has no effect on the machining accuracy due to the fluctuation phenomenon of the machine due to a sudden change in acceleration. On the other hand, the decrease in accuracy in the case of the partial arc is larger than that in the circle. Nevertheless, in the past, the feed rate was uniformly reduced by the constant of the automatic speed control function as in partial arc machining. Therefore, there is a problem that if the circular circle is machined with the constant of the automatic speed control function of the partial arc, the machining accuracy will be reduced, but the machining speed will be reduced, so that the overall machining speed cannot be increased.

Therefore, an object of the present invention is to provide a feed rate control method and apparatus in numerical control for machining a circular portion at an optimum speed while maintaining a predetermined accuracy and increasing the overall machining speed. It is in.

[0006]

In order to solve the above-mentioned problems, a feed speed control method in numerical control according to the present invention is a numerical control machining in which a motion trajectory of a machining tool includes a partial circular arc portion and a circular circle portion. In the feed rate control method in the numerical control performed while controlling the speed, it is determined whether the target motion locus of the machining tool is the partial circular arc portion or the circular circle portion, and the partial circular arc portion and the circular circle portion respectively according to the determination result. It is configured to obtain an appropriate allowable feed rate and control the actual feed rate based on the obtained allowable feed rate.
Further, the feed rate control device in the numerical control according to the present invention is a feed rate control device in the numerical control in which the motion trajectory of the processing tool performs the numerical control machining including the partial arc portion and the one-circle portion while controlling the feed speed, Based on the movement locus shape data of the machining tool, first means for determining whether the machining target portion is the partial circular arc portion or the one-round circle portion, and based on the determination result by the first means, A second means for obtaining an appropriate permissible feed speed for each of the partial arc portion and the one-circle portion, and a third means for controlling the actual feed speed based on the permissible speed obtained by the second means are provided. It is equipped with.

[0007]

According to the present invention, it is determined whether the shape of the target motion locus of the machining tool is a partial arc or a circle, and the optimum feed rate is determined for each of the partial arc and the circle according to the determination result. By setting the feed rate for one circle to be higher than the feed rate for a partial arc, high-speed and highly accurate curved surface shape machining is possible.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a flow chart showing an operation procedure of a feed rate control method and apparatus in numerical control according to the present invention, and FIG. 2 is a configuration diagram therefor. In the present invention, it is determined whether the curved surface portion to be processed is a partial circular arc portion or a circular circle portion, and an appropriate allowable feed rate is set corresponding to each. That is, as described above, during partial arc machining, fluctuations in the machining tool trajectory due to mechanical shock occur due to sudden acceleration changes at the arc end point, such as the trajectory change portion from arc machining to linear machining, and machining accuracy. Will decrease. Therefore, deceleration is required to maintain accuracy. On the other hand, in the case of machining a circle, fluctuations due to a mechanical shock occur after the necessary machining of a circle. Therefore, there is almost no deterioration in the machining accuracy of the circle, and there is no need to decelerate as in the case of a partial arc. Therefore, in the present invention, the speed is reduced during the machining of the partial arc portion, and the deceleration is minimized during the machining of the circular portion, thereby enabling high-speed machining exhibiting the maximum efficiency.

In FIG. 3, for example, in the processing block N1, for example, the feed speed F in the block N2 for machining the partial arc portion whose command feed speed Fc for linear machining is the radius Rc.
The value a is set based on the allowable feed rate that suppresses the mechanical shock of the motion of the machine tool, which is determined according to the radius Rc of the partial arc portion. Then, in block N3, the command feed speed Fc is set.

In FIG. 4, the command feed speed Fc is set in the block N1, and the feed speed Fb of the circle portion of the radius Rc is set in the block N2 based on the allowable feed speed higher than the speed of the partial arc portion. To be done. After that, in the block N3 where the linear processing is performed, the command feed speed Fc is set.

FIG. 5 shows changes in time and feed rate in the processing shown in FIGS. 3 and 4. As shown in FIG. 2, the configuration is such that a data receiving / decoding unit 2 for receiving and decoding data such as processing target data and command feed speed data from a medium 1 such as an NC tape, and shape data thus decoded. A determination unit 3 that determines whether the processing target portion is a partial circular arc portion or a circular circle portion based on the above, and an appropriate allowable feed speed is calculated for each of the partial circular arc portion and the circular circle portion based on the determination result of the determination unit An allowable feed speed setting unit 4 and an actual feed speed setting unit 5 that sets an actual feed speed based on the obtained allowable feed speed are provided.

Now, the operation processing of this embodiment will be described with reference to FIG. 1. Whether or not the processing target portion commands a circle based on the shape data in the NC program data supplied from the NC tape 1. Alternatively, it is determined whether a partial arc is commanded (step S1). When it is determined that the partial arc is commanded, the allowable feed speed F1 at the partial arc radius R1 is set to an optimum value in consideration of the processing accuracy and the processing speed (step S2). On the other hand, step S1
When it is determined to be a circular circle portion, the allowable feed speed F2 at the circular circle radius R2 is similarly set to an optimum value (step S3). However, as described above, in the case of circular circle machining, partial arc machining is compared. Then, since the degree of consideration in terms of accuracy may be small, the feed rate can be set higher.
Thus, the actual feed speed is set by the automatic speed control function in the circular interpolation based on the set allowable feed speed F1 or F2 (step S4).

The setting of the permissible feed rates for the partial arc and the circle in steps S2 and S3 is performed based on a curve as shown in FIG. 6, for example. FIG. 6 shows an arc radius R
And the actual feed speed F obtained from the allowable feed speed are shown. As mentioned above, the allowable feed speed in the case of one circle is set to be higher than the allowable feed speed in the case of partial arcs in the same arc radius. Has been done. As the allowable feed rate in the partial arc, it is possible to set a feed rate corresponding to the arc radius so that the allowable acceleration minimizes deterioration of the machining accuracy. That is, assuming that the maximum feed speed that is equal to or less than the allowable acceleration in the arc radius Ro is the allowable feed speed Fo, the allowable feed speed Fc in the arc radius Rc is obtained by Fc = Fo√ (Rc / Ro). The actual feed rate is set based on this allowable feed rate. In FIG. 6, during the partial arc machining, Fa is set as the feed rate when the arc radius is Rc.

On the other hand, when machining a circle, the radius of the arc Rc
At this time, the feed rate is set to a feed rate Fb that provides an allowable acceleration that allows the mechanical shock to be within an allowable range, thereby achieving higher-speed machining. The feed rate setting such as the curve shown in FIG. 6 for one-round machining can be experimentally obtained for each device based on the allowable acceleration determined by each processing device.

[0015]

As described above, the method and apparatus for controlling the feed rate in the numerical control according to the present invention discriminates whether the motion trajectory shape of the target machining tool is a partial arc or a circle. According to the result, the optimum feed rate is set for each partial arc and circle.
By setting the feed rate of a circle to be higher than the feed rate of a partial arc, it is possible to efficiently and quickly process curved surface shapes with high accuracy.

[Brief description of drawings]

FIG. 1 is a flowchart showing an operation procedure of a feed rate control method and apparatus in numerical control according to the present invention.

FIG. 2 is a configuration block diagram of a feed rate control device in numerical control according to the present invention.

FIG. 3 is a diagram showing a trajectory and a feed rate of a machining tool in machining blocks when machining a partial arc shape.

FIG. 4 is a diagram showing a locus and a feed rate of a machining tool in a machining block unit during circular circle machining.

FIG. 5 is a diagram showing changes in the feed rate for each machining block in the machining process of a partial arc shape and a circular circle shape.

FIG. 6 is a diagram showing a relationship between an arc radius and a feed rate in a partial arc shape and circular shape machining process.

[Explanation of symbols]

1 NC tape 2 Data receiving / decoding unit 3 Partial arc / circular circle determination unit 4 Allowable speed setting unit 5 Actual feed speed setting unit

Continuation of front page (56) Reference JP-A-62-154112 (JP, A) Actually open 2-46207 (JP, U) Actually open 61-201105 (JP, U)

Claims (2)

(57) [Claims] 1. A feed rate control method in numerical control in which a motion trajectory of a machining tool includes numerically controlled machining including a partial circular arc portion and a circular circle portion while controlling a feed velocity, wherein a target motion trajectory of the machining tool is Judgment whether it is a partial circular arc part or a full circle part, determine an appropriate allowable feed speed for each of the partial circular arc part and the full circle part according to the judgment result, and control the actual feed speed based on the obtained allowable feed speed. A feed rate control method in numerical control characterized by: 2. A feed speed control device in numerical control for performing numerical control machining in which a motion trajectory of a machining tool includes a partial arc portion and a circular circle portion while controlling a feed speed, wherein motion trajectory shape data of the machining tool is obtained. First means for receiving and processing whether the target portion is the partial circular arc portion or the circular circumference portion, and based on the determination result by the first means, the partial circular arc portion and the circular circumference portion respectively. Numerical value, characterized in that it comprises a second means for obtaining an appropriate permissible feed rate, and a third means for controlling the actual feed rate based on the permissible rate obtained by the second means. Feed rate control device in control.