JPH05200648A - Main spindle speed control device for numerically controlled machine tool - Google Patents

Abstract

PURPOSE:To enable highly accurate machining to be done without entailing any vibration at a time when a work corner part is machined in succession. CONSTITUTION:The travel speed of a spindle 12 is monitored in a spindle travel monitoring part 36, and when this travel speed of the spindle 12 is lowered to some extent, a spindle travel decelerating signal A is fed to a select means 27, and then a spindle decelerating speed is outputted to a command voltage calculating part 24 from a spindle decelerating speed setting part 26. In succession, a spindle motor 14 is driven on the basis of the obtained command voltage, thereby decelerating the spindle 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle speed control system for NC machine tools, and more particularly, when a machining direction is changed.
The present invention relates to a spindle speed control method for an NC machine tool that controls acceleration / deceleration of a spindle rotation speed corresponding to acceleration / deceleration of a spindle movement speed.

[0002]

2. Description of the Related Art Conventionally, an NC machine tool that drives a spindle equipped with a tool to perform desired machining on a work has been used in various fields. In such a conventional NC machine tool, the rotation control of the spindle is controlled by a rotation speed command given to a spindle drive unit (spindle drive unit) and start signals such as forward rotation and reverse rotation.

The means for changing the rotation speed of the started spindle has been constituted by a spindle override or by changing a command code to change the above-mentioned rotation speed command value.

[0004]

In the above-mentioned conventional NC machine tool, the control of the spindle rotational speed corresponding to the acceleration / deceleration of the spindle movement in the cutting feed and the like described below has not been performed at all.

That is, conventionally, when cutting a corner of a work in cutting feed or the like, the moving speed (feeding speed) of the spindle is automatically controlled to be decelerated, and when the machining of the corner is completed, the moving speed of the spindle is finished. Is accelerated again. During this corner machining, the rotation speed of the spindle, that is, the rotation speed of the tool is kept constant.

Therefore, in cutting feed or the like, when the corner portion of the work is continuously machined at a high speed, vibration occurs in the corner portion and the machining accuracy is deteriorated.

This is because the moving speed of the spindle is automatically accelerated and decelerated at the corners of the work, while the rotational speed of the spindle remains constant. For example,
Taking the processing when using a tool such as an end mill as an example, this is because the cutting amount per blade changes.

[0008] This tendency appears remarkably when machining at a high speed, but in a high-speed machining, both the spindle moving (cutting feed) speed and the spindle rotating speed become high, and the spindle moving occurs. This is because the amount of change due to acceleration / deceleration of the speed increases.

Therefore, the present invention solves the above-mentioned inconvenience, and controls the spindle rotation speed in accordance with the acceleration / deceleration of the spindle movement speed (spindle feed speed) to change the machining direction. An object of the present invention is to provide a spindle speed control system for an NC machine tool that can perform highly accurate machining without generating vibration even when continuously machining at high speed.

[0010]

In order to achieve the above object, the present invention relates to a NC machine tool for driving a spindle equipped with a tool to perform a desired machining on a work, and moving the spindle. A spindle movement monitoring unit that monitors a speed acceleration / deceleration state and generates a spindle movement gear shifting signal when the movement speed is accelerated / decelerated is provided, and the spindle rotation speed is responsive to the spindle movement gear shifting signal. Is configured to accelerate or decelerate.

[0011]

According to the present invention, when the corner portion of the work is machined in cutting feed or the like, when the moving speed of the spindle is accelerated or decelerated, the spindle movement monitoring section detects this and generates a spindle moving speed change signal. .. When the spindle moving / shifting signal is generated, the rotation speed of the spindle is switched to the acceleration speed or the deceleration speed preset by a program or the like, and the rotation speed of the spindle is accelerated / decelerated. Therefore, in cutting feed, etc., when continuously machining the corners of the work, the spindle rotation speed is also accelerated / decelerated in response to the acceleration / deceleration of the spindle movement speed. For example, a tool such as an end mill is used. In the case of machining, the cutting amount per blade does not change, and vibration is prevented from occurring.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A spindle speed control system for an NC machine tool according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows an NC machine tool 10 according to this embodiment.
It is a figure which shows the structure of. In the figure, reference numeral 12 is a spindle on which a tool is mounted, which is driven by a spindle motor 14,
The position coder 16 monitors the speed of the spindle 12. The spindle 12, that is, the spindle motor 14, is controlled by a control unit including an NC controller (CNC) 18 and a sequencer (PMC) 20.

M command given from outside for machining,
The S command is given to the control unit 22 of the sequencer (PMC) 20, and spindle override and gear selection are performed. The command spindle speed based on the S command is also given to the control unit 22,
The command voltage calculator 24 calculates a voltage value according to the command speed and sends it to the spindle voltage output unit 30 of the NC controller (CNC) 18.

The voltage output from the spindle voltage output section 30 is D
It is converted into an analog voltage by the / A converter 32 and is supplied to the spindle motor 14 to drive the spindle 12. Based on the operation of the spindle motor 14, the position coder 16 sends a position signal to the spindle actual speed monitoring unit 34 to monitor the speed of the spindle 12.

Reference numeral 36 is a spindle movement monitor,
The acceleration / deceleration state of the movement of the spindle 12 is monitored, and when the spindle movement speed is decelerated, the spindle movement deceleration signal A is generated. When the spindle movement deceleration signal A is given to the switching means 27, the signal from the control unit 22 is switched to the signal from the spindle deceleration speed setting unit 26 and is supplied to the command voltage calculation unit 24.

The spindle deceleration speed setting unit 26 sets a speed command by a program or the like corresponding to the moving speed of the spindle 12, and decelerates the rotation speed thereof in response to the deceleration of the spindle 12. It is for.

Reference numeral 38 is an operation panel, and the input / output unit 2
It is possible to perform an orientation operation on the spindle 12 and the like via the 8, and operate and set the sequencer (PMC) 20.

The NC machine tool of this embodiment is basically constructed as described above, and its operation and effect will be described below.

In a normal straight line cutting process, etc.,
The M command and the S command given from the outside for machining are given to the control unit 22 of the sequencer (PMC) 20 to perform spindle override and gear selection.

The command spindle speed based on the S command is also given to the control unit 22, and the command voltage calculation unit 24 calculates a voltage value according to the command speed, and the NC controller (CNC) 18
Of the spindle voltage output unit 30, the voltage output from the spindle voltage output unit 30 is converted into an analog voltage by the D / A converter 32, supplied to the spindle motor 14, and the spindle 12 is driven to perform a predetermined cutting. Processing etc. are performed. During this period, the position coder 16 sends a position signal to the spindle actual speed monitoring unit 34 based on the operation of the spindle motor 14 to monitor the speed of the spindle 12.

Next, when the corner portion is cut, the axis movement of the spindle 12 is automatically decelerated. In this case, the spindle movement speed is monitored by the spindle movement monitoring unit 36, and the spindle movement speed is determined. Is decelerated, a signal A during deceleration of the spindle movement is generated. The spindle movement deceleration signal A is given to the switching means 27 to switch the speed command to the deceleration speed from the spindle deceleration speed setting unit 26 and supply it to the command voltage calculation unit 24.

Therefore, a speed command corresponding to the spindle deceleration speed is supplied to the command voltage calculation section 24, the voltage value is calculated, and N
It is sent to the spindle voltage output unit 30 of the C controller (CNC) 18. The voltage output from the spindle voltage output unit 30 is
It is converted into an analog voltage by the D / A converter 32 and is supplied to the spindle motor 14 to drive the spindle 12,
The spindle rotation speed is decelerated in response to the deceleration of the shaft movement speed of. In this case, the tool performs the machining at the optimum machining speed according to the machining direction of the workpiece, so that the problem of vibration does not occur and the machining can be performed with high accuracy.

[0024]

According to the spindle speed control system for NC machine tools of the present invention, the following effects can be obtained. That is, when a spindle movement speed change signal is generated during continuous machining of a corner portion of a work, the spindle rotation speed is switched to a preset acceleration speed or deceleration speed to accelerate or decelerate the spindle rotation speed. For example, the spindle rotation speed is also reduced in response to the spindle movement speed being reduced at the corners, and the cutting depth per blade changes during machining when a tool such as an end mill is used. There is no problem, vibration is prevented from occurring, and highly accurate processing can be performed.

[Brief description of drawings]

FIG. 1 is a configuration block diagram of an NC machine tool according to an embodiment.

[Explanation of symbols]

 10 ... NC machine tool 12 ... Spindle 14 ... Spindle motor 16 ... Position coder 18 ... NC controller (CNC) 20 ... Sequencer (PMC) 22 ... Control unit 24 ... Command voltage calculation unit 26 ... Spindle deceleration speed setting unit 27 ... Switching Means 28 ... Input / output unit 30 ... Spindle voltage output unit 32 ... D / A converter 34 ... Spindle actual speed monitoring unit 36 ... Spindle movement monitoring unit 38 ... Operation panel

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Keisuke Yamanaka 2068-3 Ooka, Numazu City, Shizuoka Prefecture Toshiba Machine Co., Ltd. Numazu Office

Claims (1)

[Claims] 1. An NC machine tool that drives a spindle equipped with a tool to perform desired machining on a workpiece, monitors the acceleration / deceleration state of the traveling speed of the spindle, and accelerates / decelerates the traveling speed. At this time, a spindle movement monitor unit for generating a spindle movement shifting signal is provided, and in response to the spindle movement shifting signal, the rotation speed of the spindle is accelerated or decelerated. Spindle speed control method.