JPS60177844A - Main shaft speed control of numerically controlled device - Google Patents

Abstract

PURPOSE:To control the rotating speed of a main shaft to within the allowable maximum rotating speed and prevent the accident of a work getting out of place by making the main shaft speed control of a numerically controlled device automatically set the allowable maximum rotating speed in accordance with the size of a chuck. CONSTITUTION:The main shaft speed contol of a numerically controlled device controls the speed of a main shaft motor 12 so that the rotating speed of a main shaft 14 will agree with the directed value. In this main shaft speed control, a memory is set to store the allowable maximum rotating speed corresponding to the discrimination result of a chuck discriminator 23 which functions to detect the size of a chuck 19 for fixing a work 18 on a head stock 17 of the main shaft 14. In addition, it is equipped with a device which clamps the speed value directed to the main shaft motor 12 at the allowable maximum rotating speed or issues an alarm when the direction is given over the allowable maximum rotating speed according to the discrimination result of the chuck discriminator 23.

Description

[Detailed Description of the Invention] Technical Field of the Invention The present invention relates to a spindle speed controller of a numerical control device, and in particular, to a spindle speed controller for a numerical control device, and particularly to a spindle speed controller that takes some protective measures when the speed command value for the spindle motor exceeds the allowable maximum rotation speed. The present invention relates to a spindle speed controller.

Conventional technology and problems In conventional spindle speed controllers of this type, the maximum allowable rotation speed of the spindle must be manually set as a parameter from a keyboard, etc., or commanded using an NC command program. If a command is forgotten, there is a risk that the spindle will rotate at a speed higher than its original allowable maximum rotation speed, resulting in mechanical damage or an accident in which the workpiece separates from the chuck. Additionally, the maximum allowable rotation speed of the spindle generally varies depending on the size of the chuck and workpiece. That is, a chuck grips a workpiece by tightening the workpiece using hydraulic pressure, and its strength is constant. On the other hand, the larger the diameter of the chuck and the higher the rotational speed, the larger the centrifugal force and the smaller the tightening force. Therefore, if a chuck with a large diameter is used, the maximum rotational speed must be kept low in order to guarantee the tightening force beyond a certain level. For this reason, in the past, the operator had to reset the allowable maximum rotation speed each time a chuck of a different size was used, which required a relatively troublesome operation.

Purpose of the Invention The present invention improves these conventional drawbacks, and
The purpose is to automatically set the maximum allowable rotation speed according to the size of the chuck, thereby eliminating the need for operator intervention and controlling the spindle rotation speed so that it does not exceed the maximum allowable rotation speed. It is in.

Embodiment of the Invention' FIG. 1 is a block diagram of an embodiment of the invention, showing an example in which the invention is applied to an NC lathe. In the figure, reference numeral 1 denotes a microprocessor, which is connected to peripheral circuits via a bus 2. 3 is RO that stores system programs etc.
M, 4 is an area for temporarily storing the contents of the NC command program on the NC tape 5 read by the tape reader 6, the NC command program stored in the magnetic bubble memory 7, various parameters, etc., and a work area for other calculations, etc. RA with
M, 8 is a display panel having a warning lamp 8a, 9 is a launch circuit in which a digital rotation command value for the spindle is set, 10 is a D/A converter that converts the contents of register 10 into an analog quantity, 11 is D A speed amplifier that rotates the main shaft motor 12 at a speed according to the output of the /A converter 10, and a tachogenerator 1 attached to the main shaft motor 12.
The output of 3 is taken in as a feed bank signal.

Further, 13a and 13b are gears attached to the shaft 12a of the main shaft motor 12, and 13c and 13d are gears attached to the main shaft 14, 13Q.

13 f is an auxiliary gear, and 15.16 is a clutch, which constitute a variable speed reducer. When the clutch 15 is turned on by the output of the latch circuit 21 and the clutch 16 is turned off, the gears 13a and 13C are activated to drive the main shaft motor 12. The rotation transmission ratio (gear ratio) between the shaft 12a and the main shaft 14 is 1:1, and when the clutch 15 is turned off and the clutch 16 is turned on, the gear 13
b, 13e to 13f work, and the gear ratio is 1:2.

A headstock 17 is connected to the main shaft 14, and a workpiece 18 is gripped by a hydraulic chuck 19 and fixed to the headstock 17. Further, a rotation speed detector 20 is attached to the other end of the main shaft 14, and the rotation speed of the main shaft detected here is read by the microprocessor 1 via a register 21.

The yoke is a chuck discriminator that detects the size of the chuck 19, and the discrimination result is read by the microprocessor 1 via the latch circuit 24. Further, an X-axis control circuit 5 and an X-axis motor circuit are provided.

When the NC command program is given in the form of an NC tape 5, it is sent to the magnetic bubble memory 7 via the tape reader 6.
When the data is stored in the RAM 4 and given, the data is directly read from the data and stored in the RAM 4. This NC command program includes the spindle rotation command value (if constant peripheral speed control is performed, the command circumferential speed value is stored; if not, the command rotation value is stored), gear selection command value, etc. , these pieces of information are stored in the RAM 4, as shown in FIG. Furthermore, when the power is turned on, the microprocessor 1-1 performs initialization processing, during which it reads the identification signal of the chuck discriminator command via the latch circuit 24, and reads this as shown in FIG. is stored in RAM4. Note that the identification signal may be stored at times other than initialization processing. On the other hand, as shown in FIG. 3, in the parameter setting area of the RAM 4, a maximum allowable rotation speed, for example 11000 rpm, is stored in response to the identification result of a large chuck, and a maximum allowable rotation speed, e.g. 3000 rpm is stored. Although not shown, parameter values corresponding to gear ratios of 1:1 and 1:2 are set in a gear ratio parameter setting area of the RAM 4. Setting of these parameters is performed by the operator.

FIG. 4 is a flowchart showing an example of spindle speed control processing performed by the microprocessor 1.

In the figure, in step S1, the command rotation speed is set to so-called S
If it is performed with a 4-digit direct command and the constant circumferential speed control is off, the commanded value of the S4 digit is determined as the target rotation speed P, and if the constant circumferential speed control is on, the commanded value of the S4 digit is determined. The value of is recognized as the target circumferential speed value, and the target rotational speed P is calculated from this and the current value of the X axis sequentially stored in the RAM 4. Next, the maximum allowable rotation speed LP corresponding to the chuck identification result stored in the RAM 4 is selected from the parameters previously stored in the RAM 4 corresponding to large and small chucks, and the selected maximum allowable rotation speed LP and the Compare the set target rotation speed P with the target rotation speed P (S2), and if the target rotation speed P is smaller than the allowable maximum rotation speed LP, proceed to step S3, and set the allowable maximum rotation speed L.
If it is greater than or equal to P, the maximum allowable rotation speed LP is determined as the target rotation speed P, and the process moves to step S3 (S4). That is, when a rotation command higher than the allowable maximum rotation speed LP is about to be issued, the command is clamped to the allowable maximum rotation speed LP. Step S3 is to calculate a command value to be actually output to the speed amplifier 11 from the gear selection signal and gear ratio parameter stored in the RAM 4.

In addition, instead of clamping the command value at the maximum allowable rotation speed as described above, the target rotation speed P is unconditionally given to the speed amplifier 11, and the rotation speed detector 20 detects rotation exceeding the maximum allowable rotation speed LP. When this occurs, the microprocessor 1 may detect this and issue an alarm externally, such as by lighting up a warning lamp 8a on the display panel 8.

5 to 7 are explanatory diagrams of an embodiment of the chuck discriminator command, in which switches 50 to 52 are provided at predetermined intervals in the radial direction of the surface of the headstock 17 facing the chunk 19, and these switches 52 are connected as shown in FIG. 7, and slip rings 53 to 55 (
) is provided, and the mating member of the slip ring 53 is +24
Connect slip ring 54゜55 to terminal 56.57 to V power supply.
It is connected to the latch circuit 24 via.

Note that the switches 50 and 52 are A contacts, and the switch 51 is B contacts.
It is a point of contact. In this way, when the large chuck 19 is mounted, as shown in FIG. As shown in the figure, when the small chuck 19 is attached, the switch 50 is open and the switches 51, 52 are closed, so the terminal 56
is at a low level, and the terminal 57 is at a high level.

FIG. 8 is an explanatory diagram of another embodiment of the chuck discriminator order, in which a light emitting element 90.91 is provided on one side of the position where the chuck 19 is mounted, and a light emitting element 90.9 is provided on the other side.
1. When a small chuck is attached, only the light emitted from the lower light emitting element 90 is blocked by the chuck, and when a large chuck is attached, Both light emitting elements 90.9
The size of the chuck can be identified by the fact that the emitted light of No. 1 is blocked by the chuck.

Note that in the above embodiments, the size of the chuck is large.

Although the classification is divided into two types (small and small), the classification may be made more finely.

As described in detail, according to the present invention, when a chuck is replaced, the maximum allowable rotation speed corresponding to the chuck is automatically selected, and a command is issued to exceed the selected maximum allowable rotation speed. In this case, the speed command value for the spindle motor is clamped to the maximum allowable rotation speed or an alarm is issued, so there is no need to reset the maximum allowable rotation speed every time the chuck is replaced, This has the advantage of being able to prevent accidents such as the workpiece coming off from the chuck.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 and FIG.
The figure is an explanatory diagram of the storage contents of the RAM 4, and FIG. 4 is a flowchart showing an example of processing performed by the microprocessor 1.
5 to 7 are explanatory diagrams of embodiments of the chuck discriminator order,
FIG. 8 is an explanatory diagram of another embodiment of the chuck discriminator command. 1 is a microprocessor, 2 is a bus, 11 is a speed amplifier, 12 is a main shaft motor, 14 is a main shaft, 15 and 16 are clutches, and 1 is a chuck discriminator. Patent Applicant Fanasoku Co., Ltd. Representative Patent Attorney Gogo Tamamushi 2 people from outside the department Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] In a spindle speed controller of a numerical control device that controls the speed of a spindle motor so that the rotational speed of the spindle matches a commanded value, the size of a chuck for fixing a workpiece to the headstock of the spindle is detected. storage means for storing a maximum allowable rotation speed corresponding to the identification result of the chuck identification means; and a speed command value for the spindle morph when a command exceeding the allowable maximum rotation speed corresponding to the identification result of the chuck identification means is issued. 1. A spindle speed controller for a numerical control device, comprising means for clamping the rotation speed to the maximum allowable rotation speed or emitting an alarm.