JPS6089201A - Numerical controller - Google Patents

Abstract

PURPOSE:To feed a cutter with high accuracy and furthermore to change easily the feeding speed of the cutter by feeding the cutter from its initial position to its end position at a speed proportional to and synchronous with the revolving speed of a main shaft. CONSTITUTION:A main shaft driver 52 drives a main shaft motor 54 and therefore revolves a main shaft 73. Both X and Y axis motors 56 and 60 are controlled X and Y axis motor controller 61 and 71 via a pulse distributor 64, a frequency multiplier 59 and a revolving position detector 51. Thus a cutter 59 is fed with cutting to its end position from its initial position by a positioning data signal 65 and a feeding speed data signal 68 delivered from a part program interpreter 66 and proportionally to and synchronously with the revolving speed of the shaft 73. The feed amount of the cutter 59 is changed per revolution of a main shaft 73 by varying the signal 68. Furthermore the relative error between the cutter 59 and an object 72 to be processed is corrected since the shift of the cutter 59 is synchronous with the rotary replacement of the shaft 73. In this way, the feed of the cutter 59 is attained with high accuracy.

Description

[Detailed description of the invention] This invention relates to a numerical control device.

In numerically controlled machine tools such as lathes and milling machines, there are cases where the speed of the cutting edge must be synchronized with the rotational speed of the spindle, and the amount of movement of the cutting edge per rotation of the spindle must be kept constant during machining. Especially when cutting threads or taps,
The accuracy of the amount of movement of the cutting edge per rotation of the spindle and the cumulative error in the overall length of the threaded portion are issues.

To address these problems, conventional numerical I11 control devices have had to, for example, have limited thread cutting capabilities or have complex control equipment.

Such a conventional example will be explained below.

FIG. 1 shows a configuration diagram of a first conventional numerical control device. In FIG. 1, a spindle motor 1 is for rotating a workpiece 14 fixed to a spindle 15. It also includes a transmission to change the rotation speed by 140 rpm.

The main shaft side clutch 4 transmits the rotational force of the feed screw side gear 3 that meshes with the main shaft side gear 2 which is axially coupled to the main shaft 15 to the cutter feed lead screw 5, and
transmits the rotational force of the blade feed motor 7 to the blade feed lead screw 5. The tool rest 12 to which the cutter 13 is fixed is linearly moved by 50 rotations of the cutter feed lead screw.

The blade feed motor controller 8 is connected to a part program interpreter 9.
A motor control signal 11 is output based on a device-determining control signal 10 consisting of the following, and the blade feed motor 7 is controlled thereby.

This numerical control device first connects the blade feed motor side clutch 6 and disengages the main shaft side clutch 4, and in response to the positioning control signal from the part program interpreter 9, the blade feed motor control circuit 8 issues a motor control signal to feed the blade. The motor 7 is rotated, thereby rotating the knife feed lead screw 5 to rapidly advance the knife 13 attached to the tool rest 12, and positioning the knife 13 at the initial thread cutting position.

Next, the blade feed motor side clutch 6 is disengaged and the main shaft side clutch 4 is connected, and the rotation of the main shaft 15 of the main shaft motor 1, which constantly rotates the workpiece 14, is controlled via the main shaft side gear 2 and the feed screw side gear 3. This is transmitted to the blade feed lead screw 5, and the blade 13 of the tool rest 12 is fed for cutting in synchronization with the rotation of the workpiece 14. The amount of movement per rotation of the main shaft 15 of this cutter 13 is determined by the main shaft side gear 2 and the feed screw side gear 3.
It is determined by the gear ratio.

In such a numerical control device, in order to change the amount of blade movement per rotation of the main shaft 15, the trap must be prepared with a large number of combinations of gear ratios between the main shaft side gear 2 and the feed screw side gear 3.
In addition, a control device for switching these many gear ratios is also required, which inevitably results in complexity. In addition, since the blade feed control is only on one axis, the taper screw)
I couldn't do JH.

FIG. 2 shows a purchasing diagram of a second conventional numerical control device. In FIG. 2, the cutter 24 fixed to the tool rest 26 is moved in the X-axis direction and the Y-axis direction by an X-transport lead screw 25 and a Y-transport lead screw 28, which are rotated by an X-axis motor 27 and a Y-axis motor 39. sent to. The X-axis motor controller 30 outputs an X-axis motor control signal 29 based on the X-axis feed pulse signal 31 applied from the pulse distributor 32, controls the rotational speed of the X-axis motor 27, and similarly controls the Y-axis motor control signal 29. The axis motor controller 37 outputs a Y-axis motor control signal 38 based on the Y-axis transport pulse signal 36 applied from the pulse distributor 32, and controls the rotational speed of the Y-axis motor 39.

The feed rate controller 42 outputs a feed rate control signal 35 at a pulse rate corresponding to the feed rate data signal 44 output from the part program interpreter 34. The pulse distributor 32 interpolates a straight line or curve based on the positioning data signal 33 outputted from the part program interpreter 34, and distributes pulses in the X-axis direction and Y-axis direction based on the result. One distributed pulse corresponds to the feed rate. It is output at a pulse rate proportional to the pulse rate of the control signal 35. The spindle motor 22 rotates a workpiece 40 fixed to the spindle 23, and the spindle rotation speed controller 46 outputs the spindle rotation speed command signal 43 output from the part program interpreter 34 and the spindle speed detector 21. Based on the spindle rotation speed detection signal 45, a spindle motor control signal 41 is output, and the spindle motor 22 is controlled to the speed commanded by the spindle rotation speed command signal 43. During cutting feed, the part program interpreter 34
The feed rate of the cutter 24 per unit time is calculated from the cutter movement 1: per rotation of the spindle 23 specified in the part program and the spindle rotation speed, and is output as a feed rate data signal.

With the above configuration, this numerical control device uses the spindle rotation speed controller 46 and the spindle rotation speed detector 2 so that the spindle 23 rotates at the spindle rotation speed specified by the ζ-doprogram.
The speed of the spindle motor 22 is controlled by 1, and the cutter 2 is moved from the initial position at a feed rate corresponding to the amount of cutter movement per spindle rotation and the spindle rotation speed specified in the par-dove and program.
4 to the final position.
．． Feed speed controller 42. X-axis motor controller 30 and Y
The axis motor controller 37 controls the X-axis motor p27 and the Y-axis motor 39.

This numerical control device maintains the spindle 23 at a constant rotation speed specified in the part program, and calculates the feed speed of the cutter 24 per unit time from the spindle rotation speed and the feed speed per spindle rotation. In the case of a screwdriver in which thread cutting is performed by feeding the blade 24 at a feed rate, if the rotation speed of the main spindle 23 fluctuates due to an increase or decrease in the cutting load, the rotation speed of the main spindle 23 changes to the feed speed control side of the cutter 24. This is because there is no feedback and a constant trap is maintained.

As a result, the amount of feed per rotation of the main shaft varies. Further, since the rotational position of the main shaft 23 is not controlled, relative errors between the position of the cutter 24 and the rotational position of the main shaft 23 caused by fluctuations in one rotational speed are not corrected and accumulate.

In order to prevent these problems, a method of accurately controlling the rotational speed of the main shaft 23 or a method of controlling the rotational position of the main shaft 23 can be considered. However, since the main shaft motor 22 generally has a large capacity, a complicated control device is required to perform these controls accurately.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a numerical control device that has a simple configuration, can accurately feed a cutter in synchronization with the rotation of a spindle, and can easily change the feed rate.

FIG. 3 shows a configuration diagram of a numerical control device according to an embodiment of 1151 of the present invention. In FIG. 3, a cutter 59 fixed to a tool rest 55 is rotated by an X-axis motor 56.
It is sent in the X-axis direction by the transport lead screw 54,
Furthermore, the X-axis motor 56 is rotated by the Y-axis motor 60 and the Y-transport lead IJ:L-57 is rotated by the Y-axis motor 60. By feeding the X-axis feed lead screw 54 in the Y-axis direction, it is fed in the Y@ direction.

The X-axis motor controller 61 outputs an X-axis motor control signal 58 based on the X-axis feed pulse signal 63 input from the pulse distributor 64, controls the rotational speed of the X-axis motor 56, and similarly controls the rotational speed of the X-axis motor 56. The shaft motor controller 71 is connected to the pulse distributor 6
A Y-axis motor control signal 62 is output based on the Y-transport pulse signal 70 of 1+ input from 4, and the rotation speed of the Y-axis motor 60 is controlled. Pulse distributor 64 is typically DD
A (digital differential analyzer) or an algebraic calculator performs interpolation calculations on curves based on the device-defined data signal 65 from the heart program interpreter 66, and from the results pulses are generated in the X- and Y-axis directions. The divided pulses are output in proportion to the pulse rate of the feed rate control signal 67 from the frequency multiplier 69. At this time, the interpolation calculation is performed once per pulse of the feed speed control signal 67.
I try to do it only once.

The spindle motor 54 is driven by a spindle drive signal 53 applied from a spindle driver (no particular speed control is required) 52, and rotates a workpiece 72 fixed to a spindle 73. The rotational position detector 51 is a device that detects the rotation of the main shaft 730, and is generally equipped with a pulse generator, rotary encoder, etc., and is directly connected to the main shaft 73 to detect rotational displacement that generates one pulse for each detected rotation angle. A signal 75 is output.

The frequency multiplier 69 multiplies the frequency of the manually input signal by a commanded value, and is generally called a rate multiplier. The signal is multiplied and a feed rate control signal 67 is generated.

This feed speed control signal 67Ji is a pulse train signal synchronized with the rotational displacement of the main shaft 73, and furthermore, the number of pulses per rotation of the main shaft can be changed by the feed speed data signal 68.

The part program interpreter 66 reads out the total travel distance of the cutter 59 and the feed amount per spindle rotation from the part program, and outputs a positioning data signal 65 and a feed speed data signal 6.
Outputs 8.

This numerical control device rotates a spindle 73 by driving a spindle motor 54 with a spindle driver 52, and also uses a device determination data signal 65 and a feed rate data signal 68 constituted by a part program interpreter 66 to initialize the spindle 73. The X-axis motor controller 61 and Y-axis motor controller 7
1 controls the X-axis motor 56 and the Y-axis motor 60. The reason why the cutter 59 moves at a speed proportional to and synchronized with the rotational speed of the main shaft 73 is because the cutter 59 receives the feed rate control signal 67.
The feed rate control signal 67 is proportional to the pulse rate of the main shaft 7.
This is because the pulse rate is proportional to the rotation of 3, and the pulses are synchronized with the rotational displacement.

Furthermore, by changing the feed rate data signal 68, the amount of movement (feed rate) of the cutter 59 per rotation of the main spindle also changes. pulse/rotation], and the amount of tool movement per pulse of the feed speed control signal 67 is bcm/pulse.1 If the magnification of the frequency multiplier 69 is m, then the pulse rate of the feed speed control signal 67 is a×m [pulse/rotation]. rotate),
! : Further, the feed speed of the cutter 59 is a X b X
m (m/rotation).The values of a and b are fixed by the configuration of the device, but the value of m is determined by the part program interpreter 66.
to vary according to the feedrate data signal from.

The feed speed of the cutter 59 can be easily changed.

Since the movement of the cutter 59 is synchronized with the rotational displacement of the main shaft 73, the relative error between the cutter 59 and the workpiece 72 due to fluctuations in the rotational speed of the main shaft 73 is corrected, and the movement of the cutter 59 is synchronized with the rotation of the main shaft 73. can be sent with high precision and is not affected by load fluctuations. Furthermore, it is no longer necessary to keep the rotational speed of the main shaft 73 constant, and the main shaft rotational speed controller 46 as shown in FIG. 2 is no longer necessary.

The values commanded by the part program interpreter 66 during thread cutting are the amount of blade movement per rotation of the main shaft and the amount of blade movement to the end point. Since all these values are written in the part program, there is no need to calculate the amount of tool movement per hour from the spindle rotation speed and the amount of tool movement per revolution as shown in Figure 2. Furthermore, there is no need to change the latch or change the gear ratio as shown in FIG. 1, and the internal structure of the heart program interpreter 66 can be simplified.

In addition, the rotational position detector 51 and frequency multiplier 69 can be easily digitized, and by digitizing them, signal connections with the part program interpreter 66 and pulse distributor 64, which have already been digitized, can be made. It is easy to use, and the structure of the entire device is also simplified.

FIG. 4 shows a configuration diagram of main parts of a numerical control device according to a second embodiment of the present invention. This numerical control device uses a 1 frequency divider 76 in place of the frequency multiplier 69 shown in FIG. 3, and is otherwise the same as that shown in FIG. The frequency divider 76 is 1
The frequency of the rotational displacement signal 750 is divided by the value of the feed rate data signal 68 and is output as the feed rate control signal 67. In this case as well, it is easy to digitize the 0 frequency divider 76, and by digitizing it, the signal connection with the part program interpreter 66 and the pulse distributor 64 becomes easy, and the structure of the entire device can be simplified.

The effects of this embodiment other than those described above are the same as those of FIG.

FIG. 5 shows a configuration diagram of main parts of a numerical control device according to a third embodiment of the present invention. This numerical control device includes a per second feed rate control signal generator 77 and a signal selector 7 as shown in FIG.
8 is added, and the part program interpreter 66 gives a transfer rate data signal 68A (same as the feed rate data signal 68 in FIG. The feed rate data signal (same as the feed rate data signal 44 in FIG. The control signal 67B is switched by a signal selector 78, and the feed speed control signal 67' switched and outputted by the signal level selector 78 is inputted to the pulse distributor 64. In this case, the every-time transfer speed control signal 67A is used to keep the amount of blade movement per rotation of the main shaft 73 constant, and the per-second feed rate control signal 67I3 is used to make the amount of blade movement per unit time constant. These two signals are switched by the instructions of the part program. For example, when cutting a thread, the transfer speed control signal 67A is selected every time, and when fast forwarding, the transfer speed control signal 67A is selected every second.
By selecting B, the cutter 59 can be moved even if the main shaft 73 is not rotating. Other configurations and effects are the same as in the first embodiment.

FIG. 6 shows a configuration diagram of main parts of a numerical control device according to a fourth embodiment of the present invention. This numerical control device is composed of a spindle speed detector 79 such as a tacho generator and an integrator in place of the rotational position detector 51 shown in FIG. This embodiment uses a speed/position converter 80 that converts rotational displacement into a rotational displacement signal (pulse train signal) 75 corresponding to rotational displacement, and other configurations and effects are the same as those of the first embodiment.

As described above, the numerical control device of the present invention includes a spindle motor that rotates a spindle to which a workpiece is fixed.

a rotational position detection means that outputs one pulse as a rotational displacement signal for each detected rotational angle of the main spindle; and a rotational position detection means that reads out the total travel distance of the cutter and the feed amount per rotation of the main spindle from the input part program. a part program interpreter that outputs a positioning data signal and a feed rate data signal; and a frequency multiplier or divider that multiplies or divides the frequency of the rotational displacement signal according to the feed rate data signal and outputs the frequency as a feed rate control signal. an X-axis motor that sends the blade in the X-axis direction, a Y-axis motor that sends the blade in the Y-axis direction, and a number of blades that perform interpolation calculations based on the positioning data signal and correspond to the results. The pulse is distributed and output as an X-axis feed pulse signal and an X-axis feed pulse signal at a pulse rate proportional to the pulse rate of the feed speed control signal. Since it is equipped with an X-axis motor controller that rotates the axis motor and a Y-axis motor controller that rotates the Y-axis motor in accordance with the X-axis feed pulse signal, it can be synchronized with the rotation of the main axis with a simple configuration. This has the effect of allowing the blade to be fed with high precision, and also allowing the feeding speed to be easily changed.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a first conventional numerical control device. FIG. 2 is a block diagram of a second conventional numerical control device, FIG. 3 is a block diagram of a first embodiment of the present invention, and FIG. 4 is a block diagram of a main part of a second embodiment of the present invention. FIG. 5 is a block diagram of the main part of the third embodiment of the present invention, and FIG. 6 is a block diagram of the main part of the fourth embodiment of the invention. 51...Rotational position detector, 52...Main shaft driver, 54
...Main shaft motor, 55...Turret, 56...X-axis motor, 57...X-axis feed lead screw, 59...
...Knives. 60...Y-axis motor, 61...X-axis motor control @%
, 64° pulse distributor, 66 . . ζ-dobragram interpreter. 69...Frequency multiplier, 71...X-axis feed motor, 7
2...Workpiece, 73...Spindle

Claims (1)

[Claims] A spindle motor that rotates a spindle to which a workpiece is fixed;
a rotational position detection means that outputs one pulse as a rotational displacement signal for each detected rotational angle of the main spindle; and a rotational position detection means that reads out the total travel distance of the cutter and the feed amount per rotation of the main spindle from the input part program. a part program interpreter that outputs a positioning data signal and a feed speed data signal; and a frequency multiplier that multiplies or divides the frequency of the rotational displacement signal according to the feed speed data signal and outputs the frequency as a feed speed control signal. an X-axis motor that sends the cutter in the X-axis direction, a Y-axis motor that sends the cutter in the Y-axis direction, and a number corresponding to the result of performing an interpolation calculation based on the positioning data signal. a pulse distributor that distributes and outputs the pulses as an X-axis feed pulse signal and a Y-transport pulse signal at a pulse rate proportional to the pulse rate of the feed speed control signal; A numerical control device comprising: an X-axis motor controller that rotates an axis motor; and a Y-axis motor controller that rotates the Y-axis motor in response to the Y-transport pulse signal.