JPS6294248A - Numerical control device - Google Patents

Abstract

PURPOSE:To carry out machining without breakage of a tool or a workpiece by relatively operating the load detected value and the load set value of a main spindle, and controlling the feed speed of a workpiece so that a main- spindle load becomes constant in accordance with the operated result. CONSTITUTION:When a numerical control device 4 is in a control operating condition by throwing a power source into it, its arithmetic unit 4B selects a load set value corresponding to the number of the tool to be used in machining, from a memory 4A and, then, issues a command for sending it to a control unit 4C. Thereby, the control unit 4C gives a command of feeding at certain speed to a main spindle 1a and a table driving servomotor 5. At this time, a load detected value which is read by a main-spindle load detecting means 3 is fed back to the control unit 4C, and the arithmetic unit 4B compares the load set value read from the memory 4A with the fed-back load detected value and, if the fed-back load detected value is the larger, it gives a command to decelerate a feed speed to the control unit 4C. Accordingly, a tool or a workpiece can be prevented from being subjected to an unnatural force.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a numerical control device for controlling a machine tool according to a machining program.

[Conventional technology]

Fig. 2 is a block connection diagram schematically showing a conventional numerical control device (hereinafter referred to as an NC device) and a machine tool. workpiece to be processed, 3 is the main spindle 1
Spindle load detection means for detecting the load applied to a, 4 is an NC
4a is a memory provided in the NC device 4 and stores a machining program; 4b is an arithmetic unit; 4C is a control unit for feeding and controlling the workpiece 2 attached to a table; 5 is a control unit for controlling the feed of the workpiece 2; Mounting table 6'f: servo motor for movement; 7 is a load meter that displays the magnitude of the load detected by the spindle load detection means 3;

Next, the operation will be explained.

First, when the numerical control device 4 is started and the workpiece 2 is to be machined, the arithmetic unit 4b reads the machining program stored in the memory 4a and sends a machining command to the control unit 4c. This control unit 4C inputs a pulse signal according to the machining program to the main shaft 1a and the servo motor 5, and thereby drives the servo motor 5 to control the table 6.
is moved, and the workpiece 2 is processed by the tool 1.

Meanwhile, during machining, the load applied to the spindle 1a is detected by the spindle load detection means 3, and this is detected by the control unit 4C.
will be given feedback. When the load data fed back reaches an abnormal level, the arithmetic unit 4b
will generate an alarm.

By the way, when machining the workpiece 2 from the machining start point to the machining end point using the tool 1, when the tool 1 advances to an inflection point halfway between these points, the relationship between the tool 1 and the workpiece The overlap with the workpiece 2 increases, and the load on the spindle temporarily increases, which may result in uneven machining or damage to the tool. In order to avoid this, conventionally, the angle of the machining inflection point and the length of the deceleration region are set as parameters, and the machining at the inflection point is performed at the commanded feed rate. A method has been proposed in which the load applied to the motor is kept approximately constant.

[Problem that the invention seeks to solve]

Conventional NC devices are configured as described above, so tasks such as setting the length and angle of the deceleration region in the parameters as described above, and adjusting these set values according to the material of the workpiece, etc. Problems such as the complicated process and extremely difficult machining program design were encountered.

This invention changes the feed rate of the workpiece to the tool so as to maintain a preset load value.
The object of the present invention is to obtain a numerical control device that enables machining without damage to the tool 1 or the workpiece 2.

[Means for solving problems]

The numerical control device according to the present invention detects the load on the spindle of a machine tool using a spindle load detection means, stores load setting values set in advance for each tool in a memory, and uses these detected load detection values and the load. The set value is compared with the set value by the calculation means, and the control unit controls the feed speed of the workpiece to the tool according to the calculation result so that the magnitude of the load applied to the spindle is constant. It is composed of

[Effect]

The memory in this invention outputs the load setting value for each tool to the calculation means, and maintains the load setting value constant.
The control unit automatically controls the speed of the servo motor so that the tool and workpiece are brought into contact with each other under non-destructive loads, so that the machining is carried out safely and smoothly.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

In the figure, 4A is a memory that stores a tool number and a load setting value set in advance corresponding to the tool number, and 4B is a calculation means for comparing and calculating this load setting value and the load detection value of the spindle load detection means 3. It is. Other components that are the same as those shown in FIG. 2 are denoted by the same reference numerals.
Omit that duplicate explanation.

Next, the operation will be explained.

First, when the power is turned on to the numerical control device 4 and it enters the side tilt starting state, the calculation device 4B selects the load setting value corresponding to the tool number used for machining from the memo IJ4A, and then starts the control. Issue a feed command to Units h4c.

As a result, the control unit 4c instructs the main 41+la and the table drive servo motor 5 to feed at a certain speed. At this time, the load detection value read by the spindle load detection means 3 is returned to the control unit 4C. The calculation means 4B compares the load setting value read from the memo 1J4A with the returned load ejection value, and if the returned detected load value is larger, sends a command to the control unit 4C to slow down the feed speed.

For example, when the tool number TIO is selected and used for machining, the calculation means 4B reads the load setting value corresponding to the tool number TIO, in this case 70chi, from the memory 4A. When the cutting feed is executed, the load on the spindle 1a is detected by the spindle load detection means 3, and this is fed back to the control unit 4C.

The calculation means 4b calculates that if this load detection value is greater than 70%,
A command is sent to the control unit 4C to slow down the feed speed. Conversely, if the number of inches is less than 70, a command is sent to increase the feed speed.

-t, the control unit 4C receives these commands and controls the feed speed of the table 6.

Therefore, when the condition of the workpiece 2 is not uniform, the feeding speed of the table 6 is controlled so that it is fast in areas where the load is small and slow in areas where the load is large.

In the above embodiment, a load setting value of a certain size is stored in the memo IJ4A, but T2O and T2O in FIG.
By setting the load setting value to 0Llj as in 21,
The tool 1 can be controlled at a constant speed.

Further, in the above embodiment, when the load detection value is smaller than the load setting value, the feed speed is increased, but the feed speed may be set at an arbitrary commanded speed.

〔Effect of the invention〕

As mentioned above, according to this invention, the feed rate of the workpiece is changed so that the magnitude of the load on the spindle is constant, so that no unreasonable force is applied to the tool or the workpiece. It is possible to prevent accidents that would have caused damage to these parts, and it is also possible to easily create a machining program regardless of the feed speed of the workpiece.

[Brief explanation of drawings]

FIG. 1 is a block connection diagram of an NC device and a machine tool according to an embodiment of the present invention, and FIG. 2 is a similar block connection diagram of a conventional device. 1 is a tool, 1a is a spindle, 2 is a workpiece, 3 is a spindle load detection means, 4 is a numerical controller, 4A is a memory, and 4B is a calculation means. In addition, in the figures, the same reference numerals are the same, and the front indicates corresponding parts.

Claims (1)

[Claims] a spindle load detection means for detecting the load applied to the spindle of a machine tool controlled according to a machining program; a memory for storing a load setting value set for each tool attached to the spindle; and a load setting value in this memory. A calculation means for comparing and calculating the load detection value by the spindle load detection means, and based on the calculation result of the calculation means, controls the feed rate of the workpiece so as to keep the magnitude of the load on the spindle constant. A numerical control device equipped with a control unit.