JPH106181A - Control method for main spindle rotation speed in nc machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent abrasion of an edge by damage and a slip of a rotary tool by an overload by controlling main spindle feed speed and main spindle rotation speed so that a notch quantity per a single blade of the rotary tool becomes constant. SOLUTION: When feed speed is V1, rotation speed is set to N1. When speed reduction in the feed speed is started in time (t1), the rotating speed also reduces according to the feed speed. When a feed is stopped in time (t2) when a rotary tool reaches the work end, main spindle rotation speed becomes the preset lowest rotating speed N2. The rotary tool is pulled up from a groove in this condition. In this way, when the main spindle rotation speed is controlled according to main spindle feed speed, a notch quantity per a single blade of the rotary tool can be set constant. Therefore, a load of the rotary tool becomes constant, and abrasion of an edge by damage and a slip of the rotary tool by an overload can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a spindle speed in an NC machine tool such as a machining center.

[0002]

2. Description of the Related Art For example, as shown in FIG. 2, when a groove 3 is machined in a workpiece 2 using a rotary tool 1, as shown in FIG. Groove 3
In order to prevent a collision with the side surface of the rotary tool 1, the relative moving speed (hereinafter, referred to as a main shaft feed speed or simply, a feed speed) between the rotary tool 1 and the workpiece 2 is rapidly reduced. .

[0003]

However, as shown in FIG. 3, even when the feed speed is reduced, the rotation speed of the rotary tool (hereinafter, referred to as the main shaft rotation speed, or simply, the rotation speed) is constant. Therefore, the amount of cutting in the feed direction per one blade of the rotary tool 1 is reduced, causing a slip between the rotary tool 1 and the workpiece 2 and increasing the wear of the rotary tool 1.

[0004] Further, in order to prevent the wear of the rotary tool 1, if the rotation speed of the rotary tool 1 is set to a small value and machining is performed at the same feed speed as described above, the cutting amount per one blade of the rotary tool 1 becomes large. If the load exceeds the strength of the blade itself, the rotary tool 1 will be damaged such as chipping.

[0005] In view of the above circumstances, an object of the present invention is to provide a method of controlling the spindle speed in an NC machine tool that prevents breakage and wear of a rotary tool.

[0006]

In order to achieve the above object, according to the present invention, the feed rate and the spindle speed are controlled so that the cutting depth per blade of the rotary tool is constant. The rotating tool is prevented from being damaged by load, and the wear of the cutting edge due to slippage is prevented.

[0007]

FIG. 1 is a block diagram showing an embodiment of the present invention.
It will be described based on. FIG. 1 is a characteristic diagram showing a relationship between a spindle feed speed and a spindle rotation speed in an NC machine tool.

As shown in FIG. 1, when the feed speed is V1,
The rotation speed is set to N1. When the feed speed starts decreasing at time t1, the number of revolutions also decreases in accordance with the feed speed. When the feed is stopped at time t2 when the rotary tool reaches the processing end, the spindle rotation speed becomes the preset minimum rotation speed N2. In this state, the rotary tool is pulled up from the groove.

A program can be registered in the NC unit so that when the type of tool to be used (the number of teeth) and the feed rate are set, the rotation speed of the rotary tool is automatically set.

As described above, by controlling the spindle rotation speed in accordance with the spindle feed speed, it is possible to make the cutting amount per one blade of the rotary tool constant. Therefore, the load on the rotary tool is constant, and damage to the rotary tool due to overload and wear of the cutting edge due to slippage can be prevented. Further, the life of the rotary tool can be extended.

In addition, since the cutting force of the rotary tool is constant, the processing accuracy of the workpiece can be improved.

[0012]

As described above, according to the present invention, the cutting amount per blade of the rotary tool is set to be constant.
Since the moving speed and the spindle speed are controlled, it is possible to prevent damage to the rotating tool due to overload and wear of the cutting edge due to slippage.

[Brief description of the drawings]

FIG. 1 is a characteristic diagram showing a relationship between a spindle feed speed and a spindle rotation speed in an NC machine tool.

FIG. 2 is a plan view showing an example of a processing unit in the NC machine tool.

FIG. 3 is a characteristic diagram showing a relationship between a spindle speed and a spindle speed in a conventional NC machine tool.

[Explanation of symbols]

 1 rotary tool 2 workpiece

Claims (1)

[Claims] 1. A method of controlling the number of revolutions of a spindle in an NC machine tool for cutting a workpiece using a rotary tool having a plurality of blades, such that a cutting amount per blade of the rotary tool is constant. A method for controlling a spindle speed in an NC machine tool, comprising controlling a spindle feed speed and a spindle speed.