JP2001084019A - Numerical value controller, - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize efficient work without shocking a machine by synchronizing the block length of plural blocks and a direction vector pre-read so as to maximize the block length, and calculating a block finishing speed. SOLUTION: Position data and a tangent direction speed showing the moving quantity of each axis are commanded from an NC program 20, and a block pre-reading means 21 pre-reads position and speed information designated to each block of a working program by the portion of plural blocks. A block finishing speed arithmetic means 22 calculates a block finishing speed so as to meet an inter-block acceleration condition that a speed at each finishing point of pre-read plural blocks may not exceed designated inter-block acceleration α1. When the pre-read block meets a block synthesizing condition, a second block finishing speed arithmetic means 23 synthesizes the block length of the plural blocks and a direction vector pre-read so as to maximize the block length within the range of an upper limit value set in advance and calculates a block finishing speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a numerical controller for controlling the speed of a servo system so as to satisfy an acceleration condition.

[0002]

2. Description of the Related Art In a numerical controller, a workpiece is machined into a desired shape by moving a tool on a locus specified by a machining program at a specified speed.
In order to perform such machining efficiently and with high accuracy, the upper limit value of the acceleration generated during machining is taken into account in consideration of the machining shape and shock to the machine at the corner of the trajectory specified by the machining program. It is necessary to limit. Conventionally, a numerical control device described in Japanese Patent Application Laid-Open No. 8-147022 is as shown in FIG. That is,
FIG. 8 is a block diagram showing the principle of the conventional numerical controller. 81 is block information prefetch means for prefetching the position and speed information specified for each block of the machining program for a plurality of blocks, and 82 is the speed at each end point of the plurality of prefetched blocks is the upper limit of the specified inter-block acceleration. a block end speed calculating means for calculating a block end speed so as to satisfy an inter-block acceleration condition that the inter-block acceleration condition does not exceed α1, wherein the block end speed is a value of an intra-block acceleration specified separately from an upper limit value of the inter-block acceleration. A block end speed correction calculating means 84 for calculating a corrected block end speed so as to satisfy an intra-block acceleration condition not exceeding the upper limit value, 84 is a designated upper limit value of the intra-block acceleration, the corrected block end speed, and a command speed. An interpolation operation means for performing an interpolation operation so as to satisfy a condition; A servo system driving means for driving the servo system the based on the interpolation data. FIG. 9 is a block diagram showing the configuration of the numerical controller, showing an example of a two-axis specification for simplicity. In the figure, an NC program 91 instructs position data indicating the movement amount of each axis and a tangential speed. The block prefetch means 92 prefetches the information by a plurality of blocks. The block end speed calculating means 93 obtains the maximum speed at which the acceleration generated between the blocks due to the change of the feed direction generated between the blocks becomes equal to or less than the specified upper limit value α1 of the inter-block acceleration. And Assuming that the change in the feed direction between blocks takes only the sampling time Ts, the block end speed Fe due to the inter-block acceleration in the conventional technique can be obtained by equation (1). From α1 = (1−cos θ ₁ ) × Fe / Ts, Fe = (α1 × Ts) / (1−cos θ ₁ ) (1) where α1 is the upper limit of the inter-block acceleration, and Ts is the inter-block acceleration. feed direction of the change in sampling time, theta ₁ is an angle formed block i and block i + 1 adjacent as shown in FIG. Block end speed correction calculation means 94
Corrects the block end speed Fe calculated by the block end speed calculating means 93 so as to satisfy the intra-block acceleration condition. Here, the intra-block acceleration condition means that L [n] is the tangential movement distance of the n-th block, and α [2] is the upper limit of the intra-block acceleration specified separately from the inter-block acceleration upper limit, Fe [n -1] ² -Fe [n] ² ≤2 * α2 * L
[n]. This calculation process is performed on all blocks from the head block of the pre-read block information to the block immediately before the block currently being interpolated. If the m-th block does not satisfy the intra-block acceleration condition, Fe Correction is made so as to satisfy [m-1] = squart (2 * α2 * L [m] + Fe [m] ² ). Each corrected block end speed obtained by this correction operation spatially satisfies the intra-block acceleration condition. The interpolation calculation means 95 performs interpolation by sampling. The feed speed at the time of i sample is the current feed speed Fi, the remaining tangent distance Lrem for interpolation, the command feed speed F
c, when the block end speed is Fe, Fi ² −Fe ² ≧ 2 *
If α2 * Lrem, then Fi = squart (2 * α2
* Lrem + Fe ^2), to be. Also, Fi ² −Fe ² <2 * α
In the case of 2 * Lrem, if Fi ≧ Fc, then Fi = Fi−ΔFFi <Fc, then Fi = Fi + ΔF. At this time, ΔF is in the range of 0 ≦ ΔF ≦ α2 * Ts and Fi is Fc
Choose the value that is closest to. Then, an interpolation operation is performed at the determined feed speed Fi to create axis movement data. 96
Is a servo system driving means. Specifically, the axis control devices 97x and 97y are provided with servo motors 99x and 9y via servo amplifiers 98x and 98y based on axis movement data.
9y. With such a configuration, the upper limit of the inter-block acceleration can be separately specified as α1 and the upper limit of the intra-block acceleration can be specified as α2. The speed (inter-block acceleration) decreases, and the acceleration at the time of acceleration / deceleration in the block is reduced by specifying a small upper limit value of the acceleration in the block, so that the processing time and the shock to the machine can be reduced at the same time. Became.

[0003]

In FIG. 2, ~
Represents a minute linear block, and θ _{1 to} θ ₄ represent angles formed by adjacent blocks. When the corner portion is represented by a minute straight block as shown in FIG. 2, the angle (θ _{1 to} θ ₄ ) formed by the adjacent blocks is small, but the entire shape is a shape having a large curvature. If it does not decelerate, a large centrifugal force will be generated, and the processed shape will be disturbed and the machine will be shocked. In the related art, the block end speed is calculated only between the adjacent blocks.
In the case of such a shape, there is a problem that the deceleration becomes insufficient because the angle θ at the corner portion is small (see the speed pattern in FIG. 3). Therefore, the present invention does not perform useless deceleration when the minute value line block expresses a smooth shape, and sufficiently decelerates when the shape expresses a corner portion without giving a shock to the machine. It is an object to provide a numerical control device.

[0004]

In order to solve the above-mentioned problems, the present invention provides a numerical controller for controlling the speed of a servo system in accordance with a machining program. A block end speed calculating means for calculating a block end speed such that a speed at a point does not exceed a specified inter-block acceleration upper limit value α1, and the pre-read block satisfies a block synthesis condition. Determining means for determining whether or not the block length and the direction vector of the plurality of blocks are pre-read so that the block length is maximized within a range of a preset upper limit when the block satisfies a block combining condition. Storage means for synthesizing and storing, and a direction vector stored by the storage means A second block ending speed calculating means for calculating a block ending speed, wherein the block ending speed does not exceed an upper limit α2 of the intra-block acceleration specified separately from the upper limit of the inter-block acceleration. Block end speed correction calculating means for calculating a corrected block end speed so as to satisfy an acceleration condition; interpolation calculating means for performing an interpolation calculation based on an upper limit value of the intra-block acceleration, the corrected block end speed and a command value; Servo system driving means for driving the servo system based on the data subjected to the interpolation calculation. With the above configuration, the present numerical control device does not perform unnecessary deceleration when the minute value line block expresses a smooth shape, and sufficiently decelerates when the shape expresses a corner portion. So that no shock is given to the machine.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the principle of a numerical controller according to the present invention. Reference numeral 21 denotes block information prefetch means for prefetching the position and speed information specified for each block of the machining program for a plurality of blocks. 22
Is a block end speed calculating means, and the block end speed is set so that the speed at each end point of the plurality of blocks pre-read by the block information pre-reading means 21 does not exceed the specified inter-block acceleration α1. Is calculated. 23 is a second block end speed calculating means, which is a block length of the plurality of blocks prefetched so that the block length becomes the maximum within a range of a preset upper limit when the prefetched block satisfies the block synthesis condition. And the direction vector are synthesized to calculate the block end speed. Numeral 24 denotes a block end speed correction calculating means for calculating a corrected block end speed such that the calculated block end speed does not exceed the intra-block acceleration α2. Numeral 25 denotes an interpolation calculating means for performing an interpolation calculation so as to satisfy the conditions of the specified intra-block acceleration α2, the corrected block end speed, and the commanded speed. Reference numeral 26 denotes a servo system driving means for driving the servo system based on the interpolation data obtained by the interpolation.

FIG. 4 is a flowchart of the "second block end speed calculating means" shown at 23 in FIG. 1) When the second block end speed calculation is started, 2) First, it is determined whether or not to perform block synthesis. In the present embodiment, the block length is used for the determination of the block synthesis. However, the block synthesis determination may be performed by combining the number of blocks or the block length with a direction vector. Therefore, if the block length of the target block is greater than or equal to the upper limit (that is, the block combining condition is not satisfied), the block combining is not performed. Go to (Step 1). 3) If the target block satisfies the block synthesis condition, the block length and direction vector of the target block are stored as the block length and direction vector of the synthesis block (step 2). 4) A block immediately before the target block is set as a new target block (step 3). 5) The block length of the new target block and the block length of the composite block are added, and a block of the composite block is newly added. Length (step 4). 6) It is determined whether the block length of the combined block satisfies the block combining condition. When the combined block condition is not satisfied, the process proceeds to step 7, and when the combined block condition is satisfied, the process proceeds to step 6 (step 5). 7) When the combined block condition is satisfied, a vector sum of the direction vector of the new target block and the direction vector of the combined block is calculated, and the sum is newly set as the direction vector of the combined block (step 6). 8) Combine all pre-read blocks until the block composition condition is not satisfied. When the block synthesis condition is not satisfied, the block end speed is calculated using the stored direction vector. The arithmetic expression is (1)
An equation is used (step 7).

FIG. 5 shows a calculation example in the case of a shape expressing a corner by a minute straight line block. In FIG. 5, when the following conditions 1 and 2 are satisfied, step 3 is performed. That is, if 1) block length + block length + block length <upper limit value, 2) block length + block length + block length + block length> block length> upper limit value, 3) Synthesized. For this reason,
(1) of theta is theta _'4, and the order compared to angle and theta ₄ in the prior art that does not perform block synthesis is increased,
The block end speed becomes smaller (the speed pattern in such a case is determined to be a lower speed in the block as shown in FIG. 6). In FIG. 4, is a minute value line block, θ ₄ is an angle formed between blocks, 'is a block after the block is synthesized, θ'
₄ indicates the angle between the blocks.

FIG. 7 is a block diagram showing the configuration of this numerical controller, which is characterized in that the second block end speed calculating means 23 provided according to the present invention is provided. In FIG. 7, position data indicating the movement amount of each axis and tangential speed are commanded from the NC program 20, and the block prefetch means 21 prefetches the position and speed information specified for each block of the machining program by a plurality of blocks. The block end speed calculating means 22 calculates the block end speed so that the speed at each end point of the plurality of blocks pre-read by the block information pre-reading means 21 does not exceed the specified inter-block acceleration α1. In the case where the pre-read block satisfies the block synthesis condition, the second block end speed calculating means 23 pre-reads the plurality of blocks so that the block length becomes the maximum within a range of a preset upper limit value. The length and the direction vector are combined to calculate the block end speed. Subsequent steps are the same as in FIG. That is, the corrected block end speed is calculated by the block end speed correcting means 24 so as to satisfy the intra-block acceleration condition that the calculated block end speed does not exceed the intra-block acceleration α2.
Interpolation is performed so as to satisfy the conditions of the specified intra-block acceleration α2, the corrected block end speed, and the command speed. The servo system drive means 26 drives the servo system based on the interpolation data obtained by the interpolation calculation. The axis control devices 27x and 27y are controlled by the servo motors 29x and 28y via the servo amplifiers 28x and 28y based on the axis movement data.
29y is driven.

[0009]

As described above, according to the present invention, when the prefetched block satisfies the block synthesizing condition, the prefetching is performed such that the block length becomes the maximum within a preset upper limit value range. By combining the block lengths and direction vectors of a plurality of blocks and calculating the block end speed, an appropriate block end speed is calculated according to the program command shape, so that the minute value line block expresses a smooth shape. In such a case, useless deceleration is not performed, and sufficient deceleration is performed in a shape that expresses a corner portion, so that a shock can not be applied to the machine, and machining can be performed efficiently. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing the principle of a numerical control device according to the present invention.

FIG. 2 shows an example of a problem to be solved by the present invention.

FIG. 3 shows an example of a speed pattern in FIG. 2;

FIG. 4 shows a flowchart of a block end speed calculation process according to the present invention.

FIG. 5 shows a calculation example of the present invention.

FIG. 6 shows an example of a speed pattern in FIG.

FIG. 7 is a block diagram showing a configuration of a numerical control device for implementing the present invention.

FIG. 8 is a block diagram showing the principle of a conventional numerical controller.

FIG. 9 is a block diagram showing a configuration of a numerical control device for implementing the principle of FIG. 8;

[Explanation of Signs]: First linear block: Second linear block: Third linear block: Fourth linear block: Fifth linear block ': Combining third linear block and fourth linear block Straight line block θ ₄ : the angle between the fourth straight line block and the fifth straight line block θ ′ ₄ : the angle between the straight line block obtained by combining the third straight line block and the fourth straight line block and the fifth straight line block 21 : Block information pre-reading means 22: Block end speed calculating means 23: Second block end speed calculating means 24: Block end speed correcting calculating means 25: Interpolating calculating means 26: Servo system driving means

Claims (1)

[Claims] 1. A numerical control device for controlling the speed of a servo system according to a machining program, comprising: block information prefetch means for prefetching position and speed information specified for each block of the machining program for a plurality of blocks; Block end speed calculating means for calculating a block end speed such that a speed at each end point of the block does not exceed a specified inter-block acceleration upper limit value α1; Judging means for judging whether or not the synthesizing condition is satisfied; and when the block satisfies the block synthesizing condition, the block of the plurality of blocks which is pre-read so that the block length becomes the maximum within a range of a preset upper limit value. Storage means for combining and storing the length and the direction vector; Second block end speed calculating means for calculating a block end speed using the direction vector stored by the storage means, and an intra-block acceleration in which the block end speed is specified separately from an upper limit value of the inter-block acceleration. A block end speed correction calculating means for calculating a corrected block end speed so as to satisfy an intra-block acceleration condition that does not exceed the upper limit α2, and an interpolation based on an upper limit value of the intra-block acceleration, the corrected block end speed, and a command value. A numerical control device comprising: an interpolation operation means for performing an operation; and a servo system driving means for driving a servo system based on the data subjected to the interpolation operation.