WO2016024338A1

WO2016024338A1 - Numerical control device

Info

Publication number: WO2016024338A1
Application number: PCT/JP2014/071328
Authority: WO
Inventors: 剛志津田; 賢治大熊
Original assignee: 三菱電機株式会社
Priority date: 2014-08-12
Filing date: 2014-08-12
Publication date: 2016-02-18
Also published as: CN106662860A; JP6410826B2; JPWO2016024338A1; CN106662860B

Abstract

This numerical control device (1) for a machine tool, which controls the positional relationship between a workpiece on a table and a tool by moving the table or the tool along a plurality of translation axes, is provided with the following: an analysis processing unit (21) that outputs a movement path and a feed speed along said movement path on the basis of a machining program that contains a plurality of command blocks; a speed-waveform calculation unit (23) that calculates a speed waveform between a stationary state and a state corresponding to the aforementioned feed speed on the basis of said feed speed and preset acceleration and jerk limits; a corner-curve calculation unit (24) that calculates curve equations for corner curves obtained by smoothing the abovementioned movement path at the boundaries between the abovementioned command blocks on the basis of a preset path-error limit, the movement path, and the aforementioned speed waveform; and a movement-command generation unit (22) that outputs a movement command for each translation axis on the basis of the movement path and the aforementioned curve equations.

Description

Numerical controller

The present invention relates to a numerical controller capable of smoothing a moving path during acceleration / deceleration control before interpolation.

In a machine tool equipped with a numerical control device, machining is performed while moving the movable part by controlling each drive shaft so as to move to the position commanded by the machining program. In the numerical control apparatus, there is acceleration / deceleration before interpolation as a technique for accurately moving a moving path described in a machining program at a commanded speed. The pre-interpolation acceleration / deceleration is a technique in which, after generating an acceleration / deceleration waveform in the direction along the movement path, that is, a tangential direction, interpolation is performed while associating the generated acceleration / deceleration waveform with the movement path. In general, when acceleration / deceleration before interpolation is used, excessive acceleration occurs in a path that changes sharply like the corner that is the connection part of each movement command, so decelerate until it reaches an appropriate speed for each corner. There was a problem that the moving time was prolonged because the speed was increased to the commanded feed speed after passing through the.

On the other hand, in Patent Document 1 shown below, when an allowable route error with respect to the movement route is designated, a route error that is a difference between the movement route described in the machining program and the movement route after smoothing is designated. A technique is disclosed in which a path is smoothed by inserting a clothoid curve at a corner within a range that is equal to or less than the allowable path error. Further, in Patent Document 1, the velocity on the clothoid curve that does not exceed the allowable acceleration is calculated based on the clothoid curve formula, and the velocity at the connecting portion between the path before the clothoid curve is inserted and the clothoid curve is continuously calculated. Techniques for changing are disclosed. As a result, the acceleration / deceleration performed for each corner becomes unnecessary, and the travel time can be shortened.

JP 7-64622 A

However, according to the technique described in Patent Document 1, even if it is possible to generate a movement path such that the path error with respect to the movement path described in the machining program is equal to or less than a predetermined value, the generated acceleration is reduced. It cannot be guaranteed that the allowable acceleration range is not exceeded. For example, when the allowable path error is a small value that is as close to 0 as possible, a clothoid curve is inserted in a very small range. In this case, even if a clothoid curve is inserted, the movement path when the allowable path error is 0, that is, a path that substantially matches the path described in the machining program, is passed through the clothoid curve at the calculated speed. But there was a problem of sudden acceleration and deceleration.

As described above, in Patent Document 1, it is described that the acceleration generated by inserting a clothoid curve can be made not to exceed the allowable acceleration range, but only when the allowable path error is a large value. If the allowable path error is small, an excessive speed change occurs. That is, there is a problem that if the path is smoothed within a given tolerance, the acceleration becomes excessive. In addition, in order to make it below the allowable acceleration when passing on the clothoid curve, it is necessary to adjust the allowable path error, which makes it difficult to manage the path error.

Further, although not within the scope of the technique described in Patent Document 1, by improving the technique of Patent Document 1, for example, a straight line part on the movement path described in the machining program until reaching the starting point of the clothoid curve part. It is conceivable that the above-mentioned problem can be solved by decelerating to a predetermined speed in step (b) and regarding the speed after deceleration as the command speed of the straight line portion and using the technique described in Patent Document 1.

In this case, since the speed waveform obtained by the deceleration method at the straight line portion is different from the speed waveform obtained by the clothoid curve equation, there is a problem that the speed waveform at the connecting portion between the straight line portion and the curved portion is distorted. This is especially the case when operating with an acceleration / deceleration waveform in which the acceleration is continuous, resulting in the acceleration / deceleration waveform being distorted like the two-stage deceleration waveform, which unnecessarily increases the travel time. It was a problem that excited vibration. That is, there has been a problem that a dead time is increased due to unnecessary acceleration / deceleration at the entrance / exit of the smoothed path.

The present invention has been made in view of the above, and when smoothing the connection portion of each movement command, in addition to the smoothness of the movement path, before and after the start and end points of the insertion curve at the connection portion of each movement command An object of the present invention is to obtain a numerical control device capable of smoothing a speed change.

In order to solve the above-described problems and achieve the object, the present invention provides a numerical value of a machine tool that controls the positional relationship between a work on the table and the tool by moving the table or tool by a plurality of translation axes. In the control device, based on a machining program including a plurality of command blocks, an analysis processing unit that outputs a movement path and a feed speed on the movement path, a preset allowable acceleration, allowable jerk, and the feed speed A speed waveform calculation unit for calculating a speed waveform between the stop state and the feed speed state, and at a joint of the command block based on a preset allowable path error, the movement path, and the speed waveform. A corner curve calculation unit that calculates a curve equation of a corner curve obtained by smoothing the movement route, and based on the movement route and the curve equation Characterized in that it and a movement command generating unit for outputting a movement command to the translation axis.

According to the numerical control device of the present invention, when smoothing the connection part of each movement command, in addition to the smoothness of the movement path, the speed change before and after the start and end points of the insertion curve at the connection part of each movement command is also obtained. There is an effect that it can be made smooth.

The block diagram which shows the structure of the numerical control apparatus concerning embodiment of this invention The figure which shows the time change of the acceleration concerning embodiment of this invention. The figure which shows the time change of the acceleration concerning embodiment of this invention. The figure which shows the time change of the acceleration concerning embodiment of this invention. The flowchart which shows the process of the corner curve calculation part concerning embodiment of this invention The figure which shows the corner curve path | route concerning embodiment of this invention. The figure which shows the velocity waveform of the X-axis in FIG. 6, and a Y-axis The block diagram which shows the structure of the movement command production | generation part in Embodiment 1 of this invention. The figure which shows the corner curve path | route concerning embodiment of this invention. The figure which shows the velocity waveform of the X-axis and Y-axis in FIG. The block diagram which shows the structure of the movement command production | generation part in Embodiment 2 of this invention. Flowchart explaining interpolation processing in Embodiment 2 of the present invention

Hereinafter, an embodiment of a numerical control device according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a numerical control apparatus 1 according to the first embodiment of the present invention. The numerical control device 1 is a device that performs numerical control (NC: Numerical Control) on a machine tool (not shown).

The numerical control device 1 includes an analysis processing unit 21, a movement command generation unit 22, a speed waveform calculation unit 23, a corner curve calculation unit 24, and a database holding unit 25. The machine tool on which the numerical control device 1 is mounted is a table or a movable part on which a workpiece can be mounted by controlling each translational axis so as to move to a position commanded by the machining program 2, that is, the NC machining program. By moving the tool, the processing of the workpiece is performed by controlling the positional relationship between the workpiece on the table and the tool.

The numerical control apparatus 1 performs machining on a workpiece by appropriately controlling each of a plurality of translation axes (not shown), that is, the X axis, the Y axis, and the Z axis so that the tool position becomes a desired tool position. Realized. Specifically, the movement command generator 22 of the numerical controller 1 outputs a movement command 220 to the servo amplifier 4. The servo amplifier 4 has an X-axis amplifier 4X, a Y-axis amplifier 4Y, and a Z-axis amplifier 4Z corresponding to the X, Y, and Z axes, respectively, and the movement command 220 is an X-axis amplifier 4X, a Y-axis amplifier 4Y. , And the Z-axis amplifier 4Z. Thereby, the X-axis amplifier 4X, the Y-axis amplifier 4Y, and the Z-axis amplifier 4Z output and drive voltage commands to an X-axis servo motor, a Y-axis servo motor, and a Z-axis servo motor (not shown), respectively.

The machining program 2 in FIG. 1 is an NC machining program described using a command code called a G code, and is described using a command code such as a positioning command “G00” and a cutting command “G01” as a movement command. NC machining program. In general, the feed speed 200 in the case of a cutting command is described in the machining program 2 and is described using an F address. In the following, each movement command described in the machining program 2 is expressed as a command block. Normally, each line of the machining program 2 corresponds to one command block, and the machining program 2 includes a plurality of command blocks. Have

The database holding unit 25 holds, as a database, an allowable acceleration 5 that is an allowable value of acceleration, an allowable jerk 6 that is an allowable value of a differential value of acceleration, and an allowable path error 7. The allowable acceleration 5 and the allowable jerk 6 are values set according to the capabilities of the drive shafts attached to the machine, and are values set in advance as a database. The allowable acceleration 5 must be set, but the allowable jerk 6 may not be set, and the allowable jerk 6 is set to be set to zero. You may consider it not.

The allowable acceleration 5 and the allowable jerk 6 may be expressed by a combination of speed and a plurality of moving average filter time constants, and the allowable acceleration 5 is a value obtained by dividing the maximum speed by the first moving average filter time constant. The allowable jerk 6 may be calculated by further dividing the value obtained by dividing the maximum speed by the first moving average filter time constant by the second moving average filter time constant. Here, the first moving average filter time constant is a linear acceleration / deceleration time constant, and the second moving average filter time constant is an S-shaped acceleration / deceleration time constant, that is, a soft acceleration / deceleration filter time constant.

Also, a mode in which the allowable acceleration 5 and the allowable jerk 6 common to all axes are calculated from the allowable acceleration and allowable jerk of each axis and used as an allowable value at the time of acceleration / deceleration may be used.

The tolerance path error 7 which is tolerance is a tolerance value of a path error between a movement path described in the machining program 2 and a movement command 220 which is an output of the numerical controller 1 described later, and is a database in the numerical controller 1 in advance. This is the distance stored in the holding unit 25. The allowable path error 7 may be instructed by the machining program 2 and may be changed in the middle of the machining program 2.

The numerical control device 1 analyzes the machining program 2 and controls, for example, a machine tool (not shown) via the servo amplifier 4 in accordance with the analysis result to determine the relative tool position with respect to the workpiece placed on the table. Machining the workpiece while controlling.

The analysis processing unit 21 reads the machining program 2 one command block at a time, analyzes the operation command described in the read command block, generates the movement data 210 for each command block, the movement command generation unit 22, the velocity waveform calculation To the unit 23 and the corner curve calculation unit 24. Based on the machining program 2, the analysis processing unit 21 obtains the feed speed 200 on the movement path included in the movement data 210.

The movement data 210 is data obtained as a result of interpreting the command of each command block, and includes a movement path described in the machining program 2, a movement position of each translation axis for each command block, a movement distance of each drive axis, This is information necessary for determining an interpolation point for each axis, such as the axis ratio, the moving speed, the interpolation mode, the angle formed by the front and rear command paths, that is, the amount of change in the axis ratio. Here, the movement position of each translation axis is, for example, the start point position and end point position of the command block, and the interpolation mode is, for example, straight line, circular arc, or non-interpolation.

The movement command generation unit 22 outputs a movement command 220 to each translation axis along the movement path described in the machining program 2 to the servo amplifier 4 based on the movement data 210 and the corner curve equation 240. The movement command generator 22 first calculates the post-acceleration / deceleration speed in the direction along the route based on the information such as the movement amount and the axial ratio, and then describes it in the machining program 2 according to the post-acceleration / deceleration speed. The movement command 220 is output by interpolating on the route. The post-acceleration / deceleration speed is a temporal change in speed smoothed so as to satisfy the limits of the allowable acceleration 5 and the allowable jerk 6.

When the movement command generation unit 22 interpolates a route defined by a corner curve equation 240 that is an output of a corner curve calculation unit 24 described later, the movement command generation unit 22 generates a movement command 220 that passes the route defined by the corner curve equation 240. When outputting and interpolating a route in which the corner curve formula 240 is not defined, a movement command 220 that passes the movement route described in the machining program 2 is output.

Further, the post-acceleration / deceleration speed generated by the movement command generation unit 22 is calculated using a process similar to that of the conventional known technology, and is calculated within a range not exceeding the allowable acceleration 5 and the allowable jerk 6. It may be obtained by filtering such as a moving average filter. The acceleration / deceleration speed may be determined based on the amount of change in the axial ratio between adjacent command blocks, or may be determined based on the angle between adjacent command blocks. It may be what performs.

The speed waveform calculation unit 23 is described in the machining program 2 from the state of the feed speed 0 which is a stop state based on the preset allowable acceleration 5 and allowable jerk 6 and the feed speed 200 described in the machining program 2. The speed equation 230 indicating the speed waveform until the feed speed F is reached is calculated. The velocity equation 230 calculated by the velocity waveform calculator 23 is output to the corner curve calculator 24. The speed waveform calculation unit 23 calculates the speed equation 230 from the feed speed 0 to the feed speed F by the same calculation method as the calculation method of the post-acceleration / deceleration speed of the movement command generation unit 22.

In the following, an example of speed equation calculation is shown, taking as an example the case where the allowable acceleration A, the feed speed F, and the acceleration start time are t = 0. In this case, the obtained velocity waveform is a velocity waveform that accelerates or decelerates at a constant acceleration, and the velocity equation V1 (t) is
V1 (t) = A × t (1)
The speed equation reaches the speed F at time t = F / A. At this time, the moving distance X1 (t) at time t can be calculated by integrating V1 (t) with t,
X1 (t) = A / 2 × t ^ 2 (2)
It becomes. The number after “^” indicates an exponent, and the expression (2) expresses the square of t. Hereinafter, the same notation is used.

Next, the speed equation when the allowable acceleration A, the allowable jerk J, the feed speed F, and the acceleration start time are set to t = 0 is shown. In this case, the speed equation V2 (t) differs depending on the relationship between the allowable acceleration A, the allowable jerk J, and the feed speed F.

For example, in the case of F> 1 / J × A ^ 2, the speed equation includes a state in which the acceleration matches the allowable acceleration A, and the acceleration changes as shown in FIG. Here, when T1 = F / A and T2 = A / J, the velocity equation V2 (t) is
V2 (t) = J / 2 × t ^ 2 (when 0 <t <T2) (3)
V2 (t) = J × T2 × t−J / 2 × (T2) ^ 2 (when T2 <t <T1) (4)
V2 (t) = F−J / 2 × (T1 + T2-t) ^ 2 (when T1 <t) (5)
And can be calculated.

In the above description, the example of the velocity equation V2 (t) in the case of F> 1 / J × A ^ 2 has been described. However, the acceleration change may not include a state in which the acceleration matches the allowable acceleration A, and the acceleration change As shown in FIG. 3, it may be triangular. In this case, if the condition of F <1 / J × A ^ 2 holds, and T3 = √ (F / J), the velocity equation V2 (t) is
V2 (t) = J / 2 × t ^ 2 (when 0 <t <T3) (6)
V2 (t) = F−J / 2 × (2 × T3-t) ^ 2 (when T3 <t) (7)
And can be calculated.

Further, even when the condition of F <1 / J × A ^ 2 is satisfied, it may include a section where the acceleration is constant, such as the section from the time T1 to the time T2 of the acceleration change shown in FIG. In this case, the velocity equation V2 (t) is
V2 (t) = J / 2 × t ^ 2 (when 0 <t <T1) (8)
V2 (t) = J × T1 × t−J / 2 × (T1) ^ 2 (when T1 <t <T2) (9)
V2 (t) = F−J / 2 × (T1 + T2−t) ^ 2 (when T2 <t) (10)
And can be calculated. At this time, the movement distance X2 (t) at time t can be calculated by integrating V2 (t).

As described above, the derivation example of the velocity equation in the case of the acceleration waveform when only the allowable acceleration 5 is taken into consideration as the waveform accelerating from the feed speed 0 to the feed speed F, and both the allowable acceleration 5 and the allowable jerk 6 are obtained. An example of derivation of the velocity equation for the case of the acceleration waveform when taking into account is shown. However, it may be a velocity waveform that changes more smoothly than the example of the velocity equation obtained above. In this case, an allowable value may be set for the amount of change in jerk over time, and a velocity waveform may be generated. Therefore, the velocity waveform obtained by the velocity waveform calculation unit 23 is not limited to the above-described example.

The corner curve calculation unit 24, based on the velocity equation 230 indicating the velocity waveform, the movement data 210, and the allowable route error 7, shows a corner curve equation indicating a smoothed route that is a route obtained by smoothing the moving route at the joint of the command block. 240 is calculated, and the corner curve equation 240 is output to the movement command generator 22. A route obtained by smoothing the movement route is a corner curve, and a curve equation of the corner curve is a corner curve equation 240.

FIG. 5 is a flowchart showing the processing of the corner curve calculation unit 24, and the corner curve formula 240 is calculated in the following procedure.

First, in step S110, the joint of the command block that curves the movement route is determined. More specifically, based on the movement data 210, the command block seam that exhibits vibrational behavior, that is, the change in the direction of the movement path is discontinuous or the movement path curvature is discontinuous. Extract command block seams that may cause vibrational behavior in machine operation. Here, whether or not the behavior is oscillating may be determined based on an angle formed by adjacent command blocks, or may be determined based on an axial ratio change amount. In addition, regardless of changes in the path, the movement path of all command block seams may be smoothed, and the command block seams to be smoothed are taken into account in consideration of the processing load when generating the smoothed path. You may make it restrict | limit. Thereafter, the process proceeds to step S111.

In step S111, the movement path before and after the joint of the command block selected in step S110 is expressed by a mathematical expression. Specifically, the distance s along the route is input, s = 0 is the joint of the command block selected in step S110, the range of s <0 is the route P1 (s) before the joint of the command block, A range of s> 0 is defined as a path P2 (s) after the command block joint. Here, P1 (s) and P2 (s) are expressed as position vectors having the positions of all the drive shafts as elements, and are mathematical expressions indicating positions according to s.

Next, in step S112, the path equation calculated in step S111 and the velocity waveform calculation unit 23 are respectively calculated for the path after the joint of the command block determined in step S110 and the path before the joint of the command block. The speed equation 230 calculated in step 1 is associated.

Specifically, for example, in the case of a route after the joint of the command block, the speed formula V1 (t) when the time at a distance s = 0 along the route is t2 = 0 and the allowable acceleration 5 is set. Is used to calculate the position X1 (t2) at time t2. Then, the position s2 along the route at time t2 is calculated by setting the position X1 (t2) to be s which is a parameter of the route P2 (s) after the joint of the command block. That is, the distance s2 is calculated by the following mathematical formula.
s2 = X1 (t2) (11)

Next, with respect to the path before the joint of the command block, the time at the distance s = 0 along the path is set to t1 = 0, and the position X1 (t1) at time −t1 is calculated using the velocity equation. Then, the position s1 along the route at time -t1 is calculated by setting the position X1 (t1) as s which is a parameter of the route P1 (s) before the joint of the command block. That is, the distance s1 is calculated by the following mathematical formula.
s1 = −X1 (t1) (12)

In step S113, the relationship between t1 and t2 is calculated based on the TOL that is the allowable path error 7 and the mathematical expressions indicating the previous path P1 (s) and the subsequent path P2 (s), and the corner curve formula at time t is calculated. 240 is derived. For example, FIG. 6 shows a path generation method that matches the allowable path error TOL when moving the Y axis after moving the X axis. FIG. 7 shows the time change of the velocity of the X axis and the Y axis in the path of FIG.

First, the relationship between the movement route and the route error ERR is expressed by the following equation using the route expressions P1 (s) and P2 (s) and the movement distance Δs around the command block seam.
ERR = | P1 (−Δs) −P1 (0) + P2 (Δs) −P2 (0) | (13)
From this relationship, Δs is calculated when the path error ERR matches the allowable path error TOL.

Next, the movement time Δt when moving by a distance Δs on the route from the joint of the command block is calculated from the following relational expression.
Δs = X1 (Δt) (14)

Using Δt obtained as described above, Δsa is calculated from the following equation.
Δsa = X1 (2 × Δt) (15)

The end point of the corner curve equation 240 is determined by Δsa obtained as described above, with s = Δsa as the end point position of the smoothing path and s = −Δsa as the start point position of the smoothing path.

Next, the corner curve formula Q (t) is derived. Q (t) is a function related to time, and the time at the corner curve start point is t = −Δt, the time at the corner curve end point is t = Δt, and the movement from s = −Δsa to s = 0 in the path P1 (s) And a route obtained by synthesizing the movement from s = 0 to s = Δsa in the route P2 (s).

The corner curve formula Q (t) is calculated by the following formula.
Q (t) = P1 (−X1 (−t + Δt)) + P2 (X1 (t + Δt)) − P2 (0) (16)
At time t = −Δt,
Q (−Δt) = P1 (−Δsa) (17)
And at time t = Δt,
Q (Δt) = P2 (Δsa) (18)
It becomes.

From the above, it was possible to derive the corner curve equation 240 when the allowable acceleration 5 was set. It should be noted that the same processing may be performed even when the allowable jerk 6 is set in addition to the allowable acceleration 5, and in this case, X2 (instead of X1 (s) is used as the velocity equation used in steps S112 and S113. Use s).

Hereinafter, the configuration of the movement command generation unit 22 in the first embodiment will be described in detail. FIG. 8 is a block diagram showing the configuration of the movement command generation unit in the first embodiment. The movement command generation unit 22 includes a corner curve insertion unit 22A, a corner curve speed calculation unit 22B, an acceleration / deceleration processing unit 22C, and an interpolation processing unit 22D.

The corner curve insertion unit 22A inserts the corner curve formula 240 obtained by the corner curve calculation unit 24 into the movement path included in the movement data 210, and performs processing to replace a rapidly changing path with a smooth path. Specifically, the corner curve starts at a position before the joint block of the command block by Δsa along the path, and the position advanced along the path by Δsa from the joint of the command block. A process is performed in which a point between the start point and the end point of the corner curve is replaced with a route having a corner curve formula Q (t) as an end point.

The corner curve speed calculation unit 22B calculates the moving speed that passes on the corner curve according to the corner curve formula 240. The moving speed passing on the corner curve is calculated by differentiating the corner curve formula Q (t) with time.

The acceleration / deceleration processing unit 22C follows the movement path so as to satisfy the limits of the allowable acceleration 5 and the allowable jerk 6 based on information such as a movement amount and an axial ratio along the movement path in which the corner curve is inserted. Calculate the speed after acceleration / deceleration in the direction.

The interpolation processing unit 22D performs interpolation on the moving path including the corner curve on the basis of the moving speed passing through the corner curve obtained by the corner curve speed calculating unit 22B and the speed after acceleration / deceleration, and sends the movement command 220 to the servo amplifier. 4 is output. Specifically, the interpolation processing unit 22D interpolates the travel path using the travel speed obtained by the corner curve speed calculation unit 22B on the corner curve, and uses the post-acceleration / deceleration speed other than the corner curve. Is interpolated.

By the above calculation, it is possible to calculate a smoothing range in which the path error due to path smoothing matches the allowable path error.

Hereinafter, the operation of the numerical control apparatus 1 according to the first embodiment will be specifically described using an example of a specific machining program 2.

For example, it is assumed that the machining program 2 is described as follows.

O100
N1 G54 G90
N2 G0 X0. Y0. ;
N10 G1 X100. F3000;
N20 Y100. ;

“O100” on the first line of the machining program 2 indicates the machining program number by the number following the “O address”, and indicates the machining program number 100. Hereinafter, the machining program 2 will be referred to as machining program 100.

In the command block of sequence number “N1” of machining program number 100, “G54” designates the coordinate system origin position, and indicates that the coordinate value commanded by “G90” is the absolute position of the coordinate system.

Next, in the command block of the sequence number “N2” of the machining program No. 100, “G0” moves from the current position to the position of the point (X, Y) = (0, 0) on the coordinate system, Move at the maximum speed of each axis.

And in the command block of sequence number “N10” of machining program No. 100, a command to move at a speed of 3000 mm / min from the position positioned by the command block of “N2” to (X, Y) = (100, 0). Do.

In the command block with the sequence number “N20” of the machining program No. 100, a command to move to the position of (X, Y) = (100, 100) from the end point of the command block of “N10” is issued.

The operation at the joint of the command blocks “N10” and “N20” of the machining program No. 100 will be described. For example, when the allowable acceleration is set to 1 m / s ^ 2 and the allowable path error is set to 0.1 mm, the path of the command block “N10”, that is, the path P1 (s) before the joint of the command block is It is expressed by a mathematical formula.
P1 (s) = (100 + s, 0) (19)
The path of the command block “N20”, that is, the path P2 (s) after the command block joint is expressed by the following mathematical formula.
P2 (s) = (100, s) (20)

From Equation (19) and Equation (20), from the relationship between the allowable route error 7 and the route error,
Δs = TOL / √2≈0.0707 mm (21)
Is obtained. And Δt is expressed by the relationship of Δs = X1 (Δt) in Equation (14).
Δt = √ (√2 × TOL) ≈11.89 ms (22)
It becomes. From this, the path equation Q (t) becomes
Q (t) = (100−1 / 2 × (−t + Δt) ^ 2, 1/2 × (t + Δt) ^ 2) (23)
Is calculated as

By differentiating this path formula Q (t) with respect to time, a passing speed formula on the corner curve is calculated,
dQ (t) / dt = (− t + Δt, t + Δt) (24)
From time −Δt to time Δt, the X axis decelerates from speed 2Δt to speed 0 with an acceleration of 1 m / s ^ 2, and the Y axis accelerates from speed 0 to speed 2Δt with an acceleration of 1 m / s ^ 2. It will be. Since the acceleration at the corner curve portion can be made the same acceleration as the acceleration other than the corner curve portion in this way, both the moving path and each axis velocity waveform can be smoothed, and the velocity waveform of FIG. 7 is obtained. Can do.

Next, a case where the allowable acceleration 5 is 1 m / s ^ 2, the allowable jerk 6 is 100 m / s ^ 3, the allowable path error 7 TOL is 0.1 mm, and the F indicating the feed rate 200 is 3000 mm / min. Show. In this case, the derivation of P1 (s), P2 (s), and Δs can be calculated using Equation (19), Equation (20), and Equation (21). In calculating Δt, Equation (22 ) Is different from). In this case, a time Δt that coincides with Δs is calculated using X2 (t) obtained by integrating the velocity equation V2 (t) of any one of Equations (3) to (10).

F> 1 / J × A ^ 2 = 1/100 × 1 ^ 2 = 0.01 m / s = 600 mm / min
Therefore, the speed equation to be used is expressed by Equations (3) to (5), and the moving distance X2 (t) can be calculated by time-integrating the velocity equation V2 (t).
In the case of 0 <t <T2, X2 (t) is expressed by the following mathematical formula.
X2 (t) = J / 6 × t ^ 3 (25)
In the case of T2 <t <T1, X2 (t) is expressed by the following mathematical formula.
X2 (t) = J * T2 / 6 * {3 * t ^ 2-3 * T2 * t + T2 ^ 2} (26)
In the case of T1 <t, X2 (t) is expressed by the following mathematical formula.
X2 (t) = J / 6 × {−t ^ 3 + 3 (T1 + T2) t ^ 2−3t (T1 ^ 2 + T2 ^ 2) + (T1 ^ 3 + T2 ^ 3)} (27)

From the above,
TOL / √2 = X2 (Δt) (28)
It can be seen that Δt satisfying the relationship is a case where the equation (26) is used, and by solving the equations (26) and (28) for Δt,
Δt ≒ 0.0165s
And can be calculated.

Next, a corner curve formula Q (t) is derived. The corner curve formula Q (t) is
Q (t) = P1 (−X2 (−t + Δt)) + P2 (X2 (t + Δt)) − P2 (0) (29)
However, X2 (t) is a curved line expression expressed by a piecewise different expression because the expression changes with time.

Accordingly, when −Δt ≦ t <−T2, the expression (26) is used for the variable X2 (t) of P1, and the expression (25) is used for the variable X2 (t) of P2, so that the corner curve formula Q (T) can be calculated.

Further, when −T2 ≦ t <T2, the expression (26) is used for the variable X2 (t) of P1, and the expression (26) is used for the variable X2 (t) of P2. ) Can be calculated.

Finally, when T2 ≦ t <Δt, the expression (25) is used for the variable X2 (t) of P1, and the expression (26) is used for the variable X2 (t) of P2, so that the corner curve formula Q (t ) Can be calculated.

The corner curve path when the above curve curve formula Q (t) is used is FIG. 9, and the velocity waveforms of the X axis and the Y axis in FIG. 9 are FIG.

As described above, in the first embodiment, a smoothing path that satisfies the allowable path error 7 is generated according to the speed equation 230 calculated by the speed waveform calculation unit 23, and the smoothing path is then generated. It is possible to move the doorway without causing distortion of the velocity waveform. That is, the path can be smoothed without distorting the velocity waveform at the entrance / exit of the smoothing path. Accordingly, it is possible to avoid the acceleration / deceleration waveform having a plurality of steps, and thus it is possible to shorten the movement time.

Embodiment 2. FIG.
Next, the numerical controller 1 according to the second embodiment will be described. The configuration of the numerical control apparatus 1 according to the second embodiment is the same as that shown in FIG. Below, it demonstrates focusing on a different part from Embodiment 1. FIG.

In the numerical control apparatus 1 according to the first embodiment, the movement command generation unit 22 uses a method of smoothing each axis speed by replacing the movement path described in the machining program 2 with a path including a corner curve. It was. On the other hand, the movement command generation unit 22 of the numerical control device 1 according to the second embodiment is different in configuration from the movement command generation unit 22 of the first embodiment. In the movement command generation unit 22 according to the second embodiment, a method of smoothing each axis velocity waveform by providing a plurality of components that execute interpolation processing is used.

FIG. 11 is a block diagram showing a configuration of the movement command generation unit 22 according to Embodiment 2 of the present invention. The movement command generation unit 22 includes an acceleration / deceleration processing unit 22C, a speed distribution unit 22E, a first interpolation processing unit 221F, a second interpolation processing unit 222F, and an addition unit 22G. That is, the movement command generation unit 22 has a plurality of interpolation processing units.

The acceleration / deceleration processing unit 22C performs the same processing as the acceleration / deceleration processing unit 22C of FIG. 8 described in the first embodiment, and uses a known technique to determine the movement amount, the axial ratio, and the like along the movement path. Based on the information, the post-acceleration / deceleration speed in the direction along the movement path is calculated so as to satisfy the limits of the allowable acceleration 5 and the allowable jerk 6.

The speed distribution unit 22E distributes the moving speed on the corner curve to the first interpolation processing unit 221F and the second interpolation processing unit 222F based on the post-acceleration / deceleration speed and the corner curve formula 240. Distributing the moving speed is the same as distributing the moving amount in terms of the interpolation period. The speed distribution unit 22E converts the movement speed into the first interpolation processing unit 221F and the second interpolation so that different interpolation processing units process a path before the joint of the command block and a path after the joint of the command block. A process of distributing to the processing unit 222F is executed.

The operations of the first interpolation processing unit 221F and the second interpolation processing unit 222F are the same as those of the interpolation processing unit 22D of the first embodiment, except that the moving speed distributed by the speed distribution unit 22E is used. Execute. However, as will be described below, the first interpolation processing unit 221F and the second interpolation processing unit 222F execute interpolation processing of different paths on the corner curve and the movement path in parallel.

For example, when the first interpolation processing unit 221F performs the interpolation of the path before the joint of the command block, the moving speed is such that the interpolation of the path after the joint of the command block is performed by the second interpolation processing unit 222F. Execute the process of distributing. On the contrary, when the interpolation of the path before the command block seam is performed by the second interpolation processing unit 222F, the first interpolation processing unit 221F moves so that the path after the command block seam is interpolated Execute processing to distribute speed.

In addition, when the speed distribution unit 22E interpolates the route in which the corner curve formula 240 is defined, the speed distribution unit 22E distributes the moving speed so that the first interpolation processing unit 221F and the second interpolation processing unit 222F perform the interpolation processing at the same time. I do. In addition, when the speed distribution unit 22E interpolates on a route where the corner curve formula 240 is not defined, among the interpolation processes of the first interpolation processing unit 221F or the second interpolation processing unit 222F, The moving speed is distributed so that only one process is performed.

In the following, when the corner curve equation is Q (t) and the velocity equation is V1 (t), the first interpolation processing unit 221F performs interpolation processing on the path before the command block joint, Interpolation processing when the second interpolation processing unit 222F performs interpolation processing on the path after the command block joint will be described with reference to the flowchart shown in FIG.

In step S210, the speed distribution unit 22E determines whether or not the movement route to be interpolated in the current interpolation cycle includes a route in which the corner curve equation 240 is defined, and the subsequent processing branches. When the movement path to be interpolated includes a path in which the corner curve formula 240 is defined (step S210: Yes), the process proceeds to step S220, and the movement path to be interpolated is a path in which the corner curve formula 240 is defined. When not including (step S210: No), it transfers to step S250.

Step S220 is a process of the speed distribution unit 22E in the case of interpolating a route in which the corner curve equation 240 is defined. From the distance (s + Δsa) from the corner curve starting point to the distance s on the moving route, the time at the command block joint is determined. A time t with t = 0 is calculated.

Specifically, the movement distance Δs10 from the time −Δt to the time t on the movement path P1 before the joint of the command block is the distance −X1 (2 × Δt) along the path at the time −Δt and the time It is calculated as the difference of the distance −X1 (−t + Δt) along the route at t, and is expressed by the following equation (30).
Δs10 = −X1 (−t + Δt) + X1 (2 × Δt) (30)

Further, the travel distance Δs20 from the time −Δt to the time t on the travel path P2 after the joint of the command block is the distance X1 (0) along the path at the time −Δt and the path at the time t. It is calculated as the difference of the distance X1 (t + Δt) and is expressed by the following mathematical formula (31).
Δs20 = X1 (t + Δt) −X1 (0) (31)

Then, t in which the sum of Δs10 and Δs20 matches s + Δsa is calculated. That is, from the relationship of Δs10 + Δs20 = s + Δsa, using equation (30) and equation (31), solve for t,
t = (s + Δsa) / (2 × A × Δt) −Δt (32)
Calculate

In step S230, the speed distribution unit 22E uses the speed equation 230 to calculate the movement distance s1 on the movement path P1 at time −t + Δt and the movement distance s2 on the movement path P2 at time t + Δt from the time t calculated in step S220. calculate.

In particular,
s1 = −X1 (−t + Δt) (33)
s2 = X1 (t + Δt) (34)
Calculate

In step S240, the first interpolation processing unit 221F calculates the difference between s1 in the previous interpolation cycle and s1 in the current interpolation cycle, and obtains and outputs the difference as the current moving distance on the route P1. The second interpolation processing unit 222F calculates the difference between s2 in the previous interpolation cycle and s2 in the current interpolation cycle, and calculates and outputs the difference as the current moving distance on the path P2. The first interpolation processing unit 221F and the second interpolation processing unit 222F execute the interpolation processing in step S240 in parallel.

Step S250 is a process for interpolating a route for which the corner curve equation 240 is not defined. When interpolating on the movement route P1, the speed distribution unit 22E sends all movement speeds to the first interpolation processing unit 221F. And the first interpolation processing unit 221F calculates the distance between the interpolation point and the end point of the movement path P1. Set as s1, the second interpolation processing unit 222F performs a process of setting s2 to zero. Further, when interpolating on the movement path P2, the speed distribution unit 22E sets the distribution amount of the movement speed to the first interpolation processing unit 221F to be zero, and distributes all the movement speeds to the second interpolation processing unit 222F. While performing the processing, the first interpolation processing unit 221F sets s1 to zero, and the second interpolation processing unit 222F performs processing to set the distance between the starting point of the movement path P2 and the interpolation point as s2. The first interpolation processing unit 221F and the second interpolation processing unit 222F execute the interpolation processing in step S250 in parallel.

The first interpolation processing unit 221F and the second interpolation processing unit 222F use the speed distributed by the speed distribution unit 22E as an input, perform the interpolation of the movement paths P1 and P2, and add the movement amount as a result of the interpolation by the addition unit 22G. Addition and output to the servo amplifier 4 as a movement command 220.

As described above, the first interpolation processing unit 221F performs the process of interpolating on the route P1, and the second interpolation processing unit 222F performs the process of interpolating on the route P2. That is, interpolation on each path is executed according to the speed distributed by the speed distribution unit 22E.

As described above, by distributing the moving speed to a plurality of interpolation processing units according to the corner curve equation, smoothing that matches the allowable path error 7 according to the velocity equation 230 calculated by the velocity waveform calculating unit 23. It is possible to move on the route without distortion of speed at the entrance / exit of the smoothing route. As a result, it is possible to avoid the acceleration / deceleration waveform from having a plurality of stages, so that the movement time can be shortened.

According to the numerical control device 1 according to the first and second embodiments, the connection portion of each movement command described in the machining program 2 is smoothed, and the movement path described in the machining program 2 is smoothed. The speed at the connection part of the path can be smoothed, and the dead time in acceleration / deceleration can be reduced. Furthermore, an unprecedented remarkable effect is obtained such that it is possible to reduce the vibration of the machine tool caused by the distortion of the velocity waveform.

Furthermore, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention in the implementation stage. Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent requirements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and is described in the column of the effect of the invention. When an effect is obtained, a configuration from which this configuration requirement is deleted can be extracted as an invention. Furthermore, the constituent elements over different embodiments may be appropriately combined.

1 numerical control device, 2 machining program, 4 servo amplifier, 4X X axis amplifier, 4Y Y axis amplifier, 4Z Z axis amplifier, 5 allowable acceleration, 6 allowable jerk, 7 allowable path error, 21 analysis processing unit, 22 movement command Generation unit, 22A corner curve insertion unit, 22B corner curve speed calculation unit, 22C acceleration / deceleration processing unit, 22D interpolation processing unit, 22E speed distribution unit, 22G addition unit, 23 speed waveform calculation unit, 24 corner curve calculation unit, 25 database Holding section, 200 feed speed, 210 movement data, 220 movement command, 230 speed formula, 240 corner curve formula, 221F first interpolation processing section, 222F second interpolation processing section.

Claims

In a numerical control device for a machine tool that controls the positional relationship between a work on the table and the tool by moving the table or the tool by a plurality of translation axes,
Based on a machining program including a plurality of command blocks, an analysis processing unit that outputs a movement path and a feed speed on the movement path;
A speed waveform calculation unit that calculates a speed waveform between a stop state and the feed speed state based on a preset allowable acceleration and allowable jerk and the feed speed;
A corner curve calculation unit that calculates a curve equation of a corner curve obtained by smoothing the movement path at a joint of the command block based on a preset allowable path error, the movement path, and the velocity waveform;
A movement command generator for outputting a movement command to each of the translation axes based on the movement path and the curve equation;
A numerical control device comprising:
The movement path generation unit
A corner curve insertion unit that inserts the corner curve into the movement path based on the curve formula;
A corner curve speed calculation unit for calculating a moving speed on the corner curve based on the curve formula;
Based on the movement amount and the axial ratio along the movement path in which the corner curve is inserted, the post-acceleration / deceleration speed along the movement path is calculated so as to satisfy the limits of the allowable acceleration and the allowable jerk. An acceleration / deceleration processing unit;
Based on the post-acceleration / deceleration speed and the travel speed, the travel path is interpolated using the travel speed on the corner curve, and the post-acceleration / deceleration speed is used for the travel path other than the corner curve. An interpolation processing unit for interpolating the movement path;
The numerical control device according to claim 1, comprising:
The movement path generation unit
An acceleration / deceleration processing unit that calculates a post-acceleration / deceleration speed along the movement path so as to satisfy the limits of the allowable acceleration and the allowable jerk based on the movement amount and the axial ratio along the movement path;
A speed distribution unit that distributes a moving speed on the corner curve based on the curve formula and the speed after acceleration / deceleration;
Based on the speed after acceleration / deceleration and the moving speed distributed by the speed distributing unit, the moving path is interpolated using the moving speed on the corner curve, and the moving path other than the corner curve is interpolated. A first interpolation processing unit for interpolating the movement path using the post-acceleration / deceleration speed;
Based on the speed after acceleration / deceleration and the moving speed distributed by the speed distributing unit, the moving path is interpolated using the moving speed on the corner curve, and the moving path other than the corner curve is interpolated. A second interpolation processing unit for interpolating the movement path using the post-acceleration / deceleration speed;
Have
2. The numerical control according to claim 1, wherein the first interpolation processing unit and the second interpolation processing unit execute interpolation processing of different paths on the corner curve and the moving path in parallel. apparatus.