JPS6364112A - Pulse distributing method - Google Patents

Abstract

PURPOSE:To minimize a response delay without generating an overshooting by pulse-distributing the speed faster than a target speed, thereafter, pulse- distributing a slow speed and thereafter, pulse-distributing at a target speed. CONSTITUTION:In a memory 22, necessary data when a pulse distributing processing inputted from a data input device 10 is executed are written together with numerical control data to command the moving of a byte. When the distribution of a command pulse is started at a target speed commanded by the numerical control data, a CPU12 pulse-distributes a pulse generating circuit 13 at a speed V1 faster than a target speed V0 only by a time t1 with memory data, next, pulse-distributes it at a speed V2 slower than the speed V0 by a time t2 and thereafter, controls so as to pulse-distribute it at the speed V0. By the control, a servo motor 16 is driven by a driving circuit 15 like a curved line 3 and a response comes to be faster without overshooting.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a pulse distribution method for distributing command pulses for rotating a servo motor according to numerical control data.

<Conventional technology> Conventionally, to control a servo motor, pulses are distributed at a target speed indicated by numerical control data, and the distributed pulses and pulses fed back from a displacement detection circuit are input into a deviation counter. The servo motor is driven by amplifying a signal corresponding to the deviation between the two using an amplifier. The response time delay of the servo motor is reduced by increasing the gain of the amplifier.

<Problems to be solved by the invention> However, in order to reduce the response time delay of the servo motor, increasing the gain of the amplifier reduces the response time delay, but overshoot occurs. Therefore, there is a problem that there is a limit to increasing the gain.

Means for Solving the Problems> The method of the invention for solving the above problems is as follows. In FIG. 1, curve 2 represents the change in the command rotation speed of the servo motor, and curve 3 represents the actual rotation speed of the servo motor. vO is the target speed of the servo motor commanded by numerical control data. At the start of pulse distribution, pulses are distributed for a time t1 at a speed ■2 faster than the command speed ■0, and then pulses are distributed for a time t2 at a speed ■l slower than the command speed ■0. After this, the pulse is distributed at a command speed of 0.

Effect> When distributing pulses with the target speed set as 0, the pulses are distributed at a speed faster than the target speed VO by time B, and as a result, the speed of the servo motor increases rapidly. and,
In order to distribute pulses at speed 1 which is slower than target speed VO for time t2, pulse distribution is performed at speed 20 after preventing the servo system from overshooting.

In the conventional method, by increasing the gain of the amplifier,
Since the response time delay of the servo motor was made small, there was a limit to reducing the response time delay of the servo motor without overshooting.However, in the present invention, the response time can be reduced without increasing the gain of the amplifier. Since the delay is small, overshoot does not occur and the response time delay can be made smaller than before. Figure 7 shows experimental data when pulse distribution is performed at the target speed VO using the conventional method, and the gain of the amplifier is set thick within a range that does not cause overshoot. As shown in curve 1, there is a response time delay of 18.6 ms after pulse distribution.On the other hand, in the present invention, when the target speed is 0, the target speed is 75 ms from 0. The speed increased by % is taken as speed V2, the speed decreased by 15% from the target speed VO is taken as speed ■1, and the speed ■
2, the pulse distribution time tl is 4 ms, and the speed is
When the time t2 for pulse distribution in 1 is 4 ms,
It takes a response time of 12 m5 for the servo motor speed to reach speed 0 as shown by curve 3 in FIG. 1, and it can be seen that the response time delay of the present invention is smaller than that of the conventional method.

<Example> Embodiments of the present invention will be described below based on the drawings.

FIG. 2 shows the feeding mechanism of the cutting tool during cutting. The numerical control device consists of a data input device 10, an interface 1), a CPU 12, a pulse generation circuit 13, and a memory 22, and the byte feed control device includes a deviation counter 14 and a D/A converter for the output of the deviation counter 14. The drive circuit 15 includes a drive circuit 15 that drives a servo motor 16, and a servo motor 16 that rotates a feed screw 2o.

The feed screw 20 controls the feed of the cutting tool 21. Part-time job 21
The movement of is detected by the linear scale 18 and the detection head 19, and is input to the displacement detection circuit 17 and converted into a pulse. The signal output from the displacement detection circuit 17 is input to the subtraction terminal of the deviation counter 14. Figures 3 and 4
The figure is a flowchart showing pulse distribution processing by the CPU 12. FIG. 5 shows a numerical control data table (I
PD) and is written to the memo IJ22 by the CPU 12. Further, data necessary for pulse distribution processing, Δ■1, ΔV2, tl, and t2, are also inputted and written into the memory 22 by the data input device 10. ΔV
1 is the increasing speed ratio between the target speed VQ and the speed ■2 in FIG. 1, and Δ■2 is the increase speed ratio between the target speed ■0 and the speed V1
is the decreasing speed ratio. tl is the pulse distribution time for the increasing speed ratio ΔVl, and t2 is the pulse distribution time for the decreasing speed ratio ΔV2. The increasing speed ratio Δ■1, the decreasing speed ratio Δ■2, and the pulse distribution times t1 and t2 vary depending on the characteristics of the feeding mechanism, and optimum values are determined and set through experiments.

Next, the operation of the apparatus having the above configuration will be explained. Prior to processing, when an NC data creation command is given, the CPU 12 performs the process shown in FIG.
A parameter J indicating the data writing number of the D table is set to an initial value O, and a parameter m indicating a processing step is set to an initial value 1. In step 101, data Fn and Yn indicated by parameter n in the IPD table, increasing speed ratio Δv1, g decreasing speed ratio Δ■2, and pulse distribution times tl and t2 are read out.

Here, Fn is the moving speed of the cutting tool, and Yn is the moving amount.

In step 102, it is determined whether the parameter m is 1. Since the parameter m is 1, step 104
Proceed to. At step 104, the moving speed Fn is multiplied by the increasing speed ratio Δv1 to obtain the distribution speed cJ. In step 105, a constant determined by the distribution speed CJ, the pulse distribution time t1, the pitch of the feed screw of the feed mechanism, etc. is multiplied by and to obtain the distribution number DJ. Step 1) At 0, the distribution speed CJ and the distribution number DJ are set in the pulse distribution table (
PCD). Step 1) It is determined by step 1 whether the parameter m is greater than 3. Since the parameter m is 1, in step 1) 2, 1 is added to the parameter m and the parameter J, and the process returns to step 102. Although the parameter m is 2 in step 102, the process proceeds to step 103, where it is determined whether the parameter m is 2. Although the parameter m is 2, the process proceeds to step 106, and in step 106, the moving speed Fn is multiplied by the deceleration speed ratio Δ■2, and the distribution speed CJ is changed to the step 1.
At step 07, the distribution number is calculated and the process proceeds to step 1) 0, where it is written to the PCD table. Step 1) In step 1, it is determined whether the parameter m is greater than 3. Since the parameter m is 2, 1 is added to the parameter m and the parameter J again in steps 1) and 2, and the process returns to step 102. This time, since the parameter m is 3, the process proceeds to step 104 via steps 102 and 103, and in step 108, the moving speed Fn is set as the distribution speed CV, and in step 109
Calculate the distribution number DJ and proceed to step 1)1. In step 1) 1, the parameter m is greater than 3, so proceed to step 1) 3, determine whether it is the final data, and if it is the final data, finish creating the PDC table, and if it is not the final data, step 1) 4 sets the parameter m to the initial value 1
and set 1 to parameter n and parameter J.
is added, and the process returns to step 101, where the IPD data, increasing speed ratio Δ■1, decreasing speed ratio Δ■2, and pulse distribution time data t1. t2 is updated and the process proceeds to step 102, where the above cycle is sequentially repeated until the final node. As a result, a PCD table as shown in FIG. 6 is completed. When the control table for pulse distribution is completed in this way, the program shown in FIG. 4 is executed. Step 2
00, the parameter J is set to an initial value of zero.

Next, in step 201, the parameter J in the PCD table is
The distribution speed CJ and the distribution number DJ indicated by are read out, and in step 202, the distribution number D
(In step 203, the data instructing the distribution of the Sha Rokuo pulse to the pulse generation circuit 13 is sent to generate a pulse. Next, in step 203, if the data is not the final data, 1 is added to the parameter J and the pulse is generated again. Returning to step 201, the distribution speed CJ and distribution number DJ are updated from the PCD table, and the above cycle is sequentially repeated until the final data.

Through the above processing, the pulse generation circuit 13 outputs a pulse based on the PCD table, which is input to the deviation counter 14 together with the signal fed back from the displacement detection circuit 17, and a signal corresponding to the deviation between the two is output, driving the The circuit 15 performs D/A conversion and drives the servo motor as shown by curve 3 in FIG. As a result, byte sending is performed with a reduced response time delay.

<Effects of the Invention> As explained above, the present invention provides a pulse distribution method for distributing pulses for rotating a servo motor according to numerical control data, in which distribution of command pulses is started at a target speed commanded by numerical control data. When a command pulse is applied at a speed higher than the target speed for a certain period of time, a command pulse at a speed slower than the target speed is applied for a certain period of time, and then the command pulses are distributed at the target speed. This is a pulse distribution method.

Therefore, the rise time can be shortened without increasing the gain of the servo system, and the response delay can be reduced without overshooting.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the pulse distribution method of the present invention, FIG. 2 is a diagram showing a cutting tool feeding mechanism for carrying out the method of the present invention, and FIGS. 3 and 4 are diagrams for explaining the pulse distribution method of the present invention. A flowchart showing the operation, Figure 5 is a numerical control data table for the tool feed mechanism, Figure 6 is a control data table for pulse distribution, and Figure 7 is a diagram showing the response time delay of the servo motor due to the conventional pulse distribution method. Figure shown. 10...Data input device, 12...CPU. 13... Pulse generation circuit, 16... Servo motor,
22...Memory.

Claims (1)

[Claims] (1) In a pulse distribution method for distributing pulses for rotating a servo motor according to numerical control data, when distributing command pulses is started at a target speed commanded by the numerical control data, a command for a speed faster than the target speed is issued. 1. A pulse distribution method comprising distributing pulses for a certain period of time, then distributing command pulses at a speed slower than the target speed for a certain period of time, and then distributing command pulses at the target speed.