JPH0276664A - Method and device for c-axis control of spindle drive motor - Google Patents

Abstract

PURPOSE:To vary the servo gain of a spindle drive motor according to the type of controlling and thereby provide practicability of processing by furnishing a controlling means for a spindle motor 2 such as a motor control part, which decides the servo gain in accordance with the contents of processing to be executed and drives the spindle drive motor 2 under control on the basis of the servo gain decided. CONSTITUTION:A spindle drive motor 2 is furnished, which is coupled with a work main shaft 4 to grasp a work 13, and a servo gain table memory 12 is furnished accommodating a servo gain table (TBL) indicating the servo gain of the spindle drive motor 2 classified by control types at the time of work processing in C-axis control. The servo gain table (TBL) the servo gain table memory 12 is referenced in conformity to the control code indicated in a processing program(PRO), and the servo gain is decided in accordance with the contents of processing to be executed, and a control means 6 is provided to drive the spindle drive motor 2 under control on the basis of the servo gain decided.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a C-axis control device and control method for a spindle drive motor directly connected to a workpiece spindle of a machine tool.

(b), Prior Art Recently, machine tools of this type that can perform machining such as turning and milling using C-axis control have become commercially available and are becoming popular. In addition, in order to keep up with the recent trend toward miniaturization, in these machines, the workpiece spindle and spindle drive motor are directly connected, and a single motor is used to perform turning operations and rotational operations that involve C-axis control. Attempts are being made.

(C) 0 Problems to be Solved by the Invention However, when the workpiece spindle and the spindle drive motor are directly connected, the load applied to the spindle is directly applied to the motor. Since the motor is operated under very severe conditions, it is not possible to operate the motor with sufficient margin in all machining operations such as rapid traverse, positioning, standard, finishing, and heavy cutting. For example, if the servo gain of the C-axis motor is set low to ensure smooth positioning and vibration after positioning during rapid traverse and positioning, the C-axis rigidity will not be sufficient to withstand cutting. In addition, if the servo gain of the C-axis motor is set high to withstand heavy cutting, there is the problem that vibration during positioning becomes intense and the cutting surface deteriorates due to vibration of the motor during cutting. .

SUMMARY OF THE INVENTION An object of the present invention is to provide a C-axis control device and control method for a spindle drive motor that can eliminate the above-mentioned drawbacks (i.e., control the servo gain by switching it depending on the cutting content).

(d) Means for solving the zero problem, that is, the present invention has a workpiece spindle (4) that grips a workpiece (13), and a spindle drive motor (2) directly connected to the workpiece spindle (4). ), and a servo gain table memory (12) storing a servo gain table (TBL) indicating the servo gain of the spindle drive motor (2) according to the control type during workpiece machining in C-axis control is provided, and the machining program ( According to the control code instructed in PROJ, the servo gain table (TBL) in the servo gain cheap memory (12) is referred to, and the servo gain corresponding to the machining content to be executed is determined and the spindle drive motor ( 2) is provided with a main shaft drive motor control means (6) for controlling drive based on the determined servo gain.

The present invention also provides a machine tool (1) that has a workpiece spindle (4) that grips a workpiece (13) and is provided with a spindle drive motor (2) that is directly connected to the workpiece spindle (4). The servo gain of the drive motor (2) can be controlled during workpiece machining using C-axis control. [A servo gain table memory (12) that stores the servo gain table (TBL) shown separately is provided, and the servo gain is specified in the machining program (PRO). The servo gain table (TBL) in the servo gain table memory (12)
With reference to the servo gain table (TBLI,
The servo gain is determined according to the processing content to be executed, and the spindle drive motor (2) is drive-controlled based on the determined servo gain.

Note that the numbers in parentheses are for convenience and indicate corresponding elements in the drawings, and therefore, this description should not be limited to the descriptions in the drawings. The following r (el
The same applies to the column ``, action''.

(e) 4 effects With the above-described configuration, the present invention provides a main shaft drive motor (2)
The servo gain table (TBL) indicates that the drive control is performed using the servo gain according to the control content.

(f), Example Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a control block diagram showing an example of a machine tool to which an embodiment of the present invention is applied, and FIG. 2 is a schematic diagram showing an example of a servo gain table.

As shown in FIG. 1, the multitasking machine tool 1 has a spindle drive motor 2, and an output shaft 2a of the spindle drive motor 2.
That is, the chuck 3 is attached to the workpiece spindle 4 in a directly connected manner. A rotation angle detector 5 is attached to the main shaft drive motor 2, and a motor control section 6 is further connected to the main shaft drive motor 2. A main control section 9 is connected to the motor control section 6 via a bus line 7, and a keyboard 10 and a machining program memory 11 are connected to the main control section 9 via the bus line 7.
and a servo gain table memory 12 etc. are connected.

Since the multi-tasking machine tool 1 has the above configuration,
When performing machining that involves C-axis control using the multi-tasking machine tool 1, as shown in FIG. 2 to rotate. Then, the workpiece 13 rotates at a predetermined rotational angular velocity via the chuck 3, so that the rotary tool 16, such as a milling cutter, mounted on the tool post 15
is rotated, and the rotary tool 16 performs key groove and other machining on the workpiece 13.

This machining is performed based on the machining program PRO stored in the machining program memory 11, and the machining program PRO stores control codes such as G code and M code indicating feed and type of machining. Therefore, the motor control unit 6 refers to these control codes and determines the servo gain for driving the spindle drive motor 2 from the servo gain table TBL stored in the servo gain table memory 12.

That is, as shown in FIG. 2, the servo gain table TBL stores position loop gains and velocity loop gains for each control code as parameters, and their values are, for example, based on standard cutting control. In the case of GOO rapid traverse/positioning control, the position loop gain and velocity loop gain are values lower than those of standard cutting control (for example, if the gain of standard cutting is 1.0, 0.5, etc.). The numbers in parentheses in each loop gain column are reference values (assuming the gain in standard cutting control is 1.0). This prevents the output shaft 2a, and hence the workpiece spindle 4 on which the chuck 3 is mounted, from swinging due to overgain. In addition, in the case of finish cutting control of GQI-M23B, lower the position loop gain and control the other axes (
By matching the position loop gain with the
For heavy cutting control of I-M239, leave the position loop gain as standard cutting, increase only the speed loop gain,
Improves shaft rigidity compared to standard cutting to increase heavy cutting ability.

As described above, the motor control unit 6 refers to the servo gain table TBL based on the control code commanded in the machining program, determines the servo gain according to the control operation to be performed, and based on the result, The main shaft drive motor 2 is driven. Then, the chuck 3 directly connected to the spindle drive motor 2 is rotated together with the workpiece 13, and the turret 1
Appropriate machining is performed using the rotary tool 16 above 5. The spindle drive motor 2 is controlled so that its servo gain changes depending on the machining content, so there is no possibility of insufficient shaft rigidity during heavy cutting or hunting of the workpiece spindle 4 during positioning. .

(g) 0 Effects of the Invention As described above, according to the present invention, the workpiece spindle 4 that grips the workpiece 13 is provided, the spindle drive motor 2 directly connected to the workpiece spindle 4 is provided, and the spindle drive motor 2 is provided. A servo gain table memory 12 is provided that stores a servo gain table TBL indicating the servo gain of the motor 2 according to the control type during workpiece machining in C-axis control, and the machining program P
The servo gain table T in the servo gain table memory 12 is changed according to the control code instructed in the rtO.
The main spindle drive motor 2, such as a motor control unit 6, refers to the BL, determines a servo gain according to the processing content to be executed, and controls the spindle drive motor 2 based on the determined servo gain. Since it is configured with a control means,
It is now possible to perform machining by changing the servo gain of the spindle drive motor 2 according to the control type, such as finish cutting, heavy cutting, rapid traverse/positioning, etc., allowing high precision machining without increasing the size of the spindle drive motor 2. It becomes possible to do this.

In addition, in a machine tool that has a workpiece spindle 4 that grips a workpiece 13 and is provided with a spindle drive motor 2 directly connected to the workpiece spindle 4, the servo gain of the spindle drive motor 2 is adjusted during workpiece machining in C-axis control. A servo gain table memory 12 storing a servo gain table TBL indicated in the control type is provided, and the servo gain table TBL in the servo gain table memory 12 is referred to according to the control code instructed in the machining program PRO. If the table TBL is configured to determine a servo gain according to the machining content to be executed, and drive control of the spindle drive motor 2 based on the determined servo gain, the servo gain according to the machining control content is determined. It is possible to drive the spindle drive motor 2 with 9, and it is possible to perform appropriate C-axis control machining according to the machining content without increasing the size of the spindle drive motor 2.

[Brief explanation of the drawing]

FIG. 1 is a control block diagram showing an example of a machine tool to which an embodiment of the present invention is applied, and FIG. 2 is a schematic diagram showing an example of a servo gain table. 1... Machine tool 2... Spindle drive motor 4... Workpiece spindle 6... Control means (motor control section) 12... Servo gain table memory 13... Work TBL... Servo gain table Applicant Yamazaki Mazak Co., Ltd. Agent Patent attorney Phase 1) Shinji (and 2 others) Figure 1 141 Goka Ee 4 ￥ He Tachibana

Claims (4)

[Claims] (1) A workpiece spindle that grips a workpiece, a spindle drive motor that is directly connected to the workpiece spindle, and a servo gain of the spindle drive motor that is indicated by the control type during workpiece machining in C-axis control. A servo gain table memory storing a table is provided, and the servo gain table in the servo gain table memory is referred to according to the control code instructed in the machining program to determine the servo gain according to the machining content to be executed. A C-axis control device for a spindle drive motor, comprising a control means for driving and controlling the spindle drive motor based on the determined servo gain. (2) If the control type of the servo gain table is fast forward or
The C-axis control device for a spindle drive motor according to claim 1, characterized in that the C-axis control device is classified into positioning, standard cutting, finishing cutting, and heavy cutting. (3) In a machine tool that has a workpiece spindle that grips a workpiece and is provided with a spindle drive motor directly connected to the workpiece spindle, the servo gain of the spindle drive motor is set to the control type during workpiece machining in C-axis control. A servo gain table memory that stores the indicated servo gain table is provided, the servo gain table in the servo gain table memory is referred to according to the control code instructed in the machining program, and the machining content to be executed is determined based on the servo gain table. A C-axis control method for a spindle drive motor, comprising: determining a servo gain according to the servo gain, and controlling drive of the spindle drive motor based on the determined servo gain. (4) If the control type of the servo gain table is fast forward or
4. The C-axis control method for a spindle drive motor according to claim 3, wherein the C-axis control method is classified into positioning, standard cutting, finishing cutting, and heavy cutting.