JP2654228B2 - Numerical control unit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION (Field of Industrial Application) The present invention relates to a numerical control device, in particular, a numerical control machine having a plurality of spindles and holding a workpiece by one or two spindles. The present invention relates to a numerical control device suitable for application to a machine.

(Prior art) In recent years, in order to improve the productivity of machining, various functions that were conventionally realized by multiple numerically controlled (hereinafter referred to as NC) machine tools are provided in one NC machine tool. It has become. For example, a CNC lathe, which is a kind of NC machine tool, has a lathe C-axis control function as shown in FIG. 3 (A) and a two-spindle perfect synchronous control function as shown in FIG. 3 (B). To realize the lathe C-axis control function, high-precision position control technology of the main spindle is required. To realize the two-spindle perfect synchronous control function, an advanced synchronous control technology between two main spindles and at least one A drive mechanism for linearly moving the headstock is required.

FIG. 4 is a schematic view showing an example of a CNC lathe having the driving mechanism, in which a sub spindle 12 is a main spindle 11
A guide is attached to a headstock 18 on which the sub-spindle 12 is mounted so as to be movable with respect to
The spindle ball screw 16 is driven by the W-axis drive motor 17 to
Is positioned at an arbitrary position within the movable range on the W axis,
There are 15 deliveries.

The transition of the operation mode of the CNC lathe having the lathe C-axis control function having such a W-axis drive mechanism and the two-spindle perfect synchronous control function will be described below. For example, a workpiece having two main shafts, a main spindle 11 and a sub-spindle 12, as shown in FIG. A process for continuously processing an object (hereinafter referred to as a work) 15 is generally set as shown below.

A workpiece turret A held by the main spindle 11
Work with 13 and B tool post 14. At this time, the lathe C-axis control processing (hereinafter referred to as “generating processing”) shown in FIG. 3A may be performed (this operation mode is hereinafter referred to as “C-axis mode”), and the main spindle 11 is switched to the position control mode. It is often driven.

The sub-spindle 12 is moved closer to the main spindle 11 on the W axis,
Alternatively, the work 15 is cut off and divided by the B tool post 14 (see FIG. 6). At this time, two-spindle perfect synchronization control shown in FIG. 3B is performed by the main spindle 11 and the sub-spindle 12 (this operation mode is hereinafter referred to as a big-off mode), and both the main spindle 11 and the sub-spindle 12 have high precision. It is operated with a simple position control.

The sub-spindle 12 is returned in the direction opposite to the main spindle 11 on the W axis while holding the divided work, and the work (hereinafter, referred to as a sub-spindle work) 52 held by the sub-spindle 12 is moved to the A tool post 13 (or B tool post 1
4) Back processing is performed in the main spindle 11
(Hereinafter, referred to as a main spindle work) 51 is held by the B tool post 14 (or A
Processing is performed by the tool post 13) (see FIG. 7). At this time, the position of both the main spindle 11 and the sub-spindle 12 is controlled as needed.

After the machining of the sub spindle work 52 is completed, the main spindle work 51 is machined by the A tool post 13 (or the B tool post 14) or the double tool post 13 and 14. At this time, the position of the main spindle 11 is controlled as needed.

When the process is completed, the process is repeated from the second process, whereby the bar is continuously processed by one CNC lathe. Table 1 summarizes the above repetitive steps.

Fig. 8 shows a conventional NC that controls the drive of the above-mentioned CNC lathe.
FIG. 2 is a block diagram showing an example of the device. For example, servo parameters (speed lube gain, position lube gain, and position lube gain) for each axis set in advance in servo adjustment are stored in a servo parameter storage unit 3 composed of a nonvolatile storage element such as a bubble memory.
Data such as acceleration / deceleration time constants are stored collectively for each axis. When the power is turned on, the servo parameters for the main spindle are read from the servo parameter storage section 3 by the NC command section 2 and transferred to the main spindle operation servo parameter storage section 4M connected to the main spindle control section 5M. After the transfer of the main spindle servo parameters to the main spindle operation servo parameter storage unit 4M, the NC command unit 2 reads the servo parameters for the next control axis, the sub spindle, from the servo parameter storage unit 3 and Control unit 5S
Is transferred to the sub-spindle operation servo parameter storage unit 4S connected to. W axis, XA axis, ..., ZB
The servo parameters corresponding to the axis are read from the servo parameter storage unit 3 by the NC command unit 2, and the servo parameter storage units 4W, 4XA,..., Connected to the control units 5W, 5XA,. Each is transferred to 4ZB. These servo parameters are set to levels that do not hinder the control of each axis due to servo control conditions, load conditions, and the like assumed for each axis, and the same servo parameters are applied to each operation mode.

In such a configuration, the operation of each unit when the transfer of the servo parameters to each axis control unit at the time of power-on and the normal NC operation is performed will be described.

The NC command unit 2 reads the NC program 1 and interprets it, and sends movement commands such as speed commands and position commands to each control unit.
Sends to 5M-5ZB and monitors control status data (current position, speed, abnormality detection signal, etc. of each axis) from each control unit 5M-5ZB to check whether the normal control status is maintained And
An operation command issued by the NC program 1 is realized.

The main spindle control section 5M responds to a movement command from the NC command section 2 to drive the main spindle driving induction motor 6M.
The current position and speed of the induction motor 6 are calculated from the detection values of the pulse generator 7 connected to the control unit 2 and sent to the NC command unit 2 and the feedback control of the induction motor 6 is performed. When the abnormality of the induction motor 6 or the pulse generator 7 is detected, the induction motor 6 is stopped and an abnormality detection signal is sent to the NC command unit 2.

Hereinafter, each of the control units 5S to 5ZB is a main spindle control unit 5
Similarly to M, feedback control is performed on the synchronous motors 8S to 8ZB for driving the respective axes, and abnormality detection of the synchronous motors 8S to 8ZB for driving the respective axes and the resolvers 9S to 9ZB coupled thereto is performed.

According to the method described above, the NC command unit 2 controls the two spindle control units 5M and 5S and the feed axis control units 5W to 5ZB, and controls the C-axis mode or the two spindles in the main spindle 11 or the sub spindle 12. It operates to realize the pick-off mode by 11,12.

(Problems to be Solved by the Invention) Generally, in order to control the position of the motor stably, it is necessary from experience to set the load inertia within a range of about 1 to 3 times the rotor inertia of the motor. In the above-mentioned two-spindle CNC lathe, the sub-spindle is usually driven by a motor whose output is smaller than that of the main spindle. The load inertia of the sub-spindle shaft converted to load is wider than that of the main spindle shaft converted to load of the sub-spindle, and the rotor inertia of the main spindle motor is also often larger than that of the sub-spindle motor. . In the pick-off mode, each rotor inertia adds to the load inertia of the opposing spindle.

Normally, during servo adjustment, appropriate servo parameters are determined and set by the operation of each spindle alone. However, when both spindles are connected by a work as in the pick-off mode, the sub-spindle having a narrow control range of the load inertia may resonate violently. The reason for this is that the servo parameters such as the speed loop gain set in the individual operation of each spindle have an excessive gain with respect to the load inertia in the pick-off mode that far exceeds the allowable load inertia of each spindle alone. Therefore, processing quality in the pick-off mode is definitely damaged. In order to avoid this, the servo parameters may be reset to a value that does not cause a problem.However, it is necessary to perform processing of the sub-spindle alone with the reset servo parameters, for example, creation of the back side of the sub-spindle side Since the gain is too small, there is a problem that a tracking delay occurs or processing takes longer than necessary.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an NC machine tool that has a plurality of spindles and operates while gripping a workpiece with one or two spindles.
An object of the present invention is to provide an NC device capable of appropriately switching servo parameters corresponding to a plurality of operation modes.

(Means for Solving the Problems) The present invention relates to an NC device that generates a movement command for each axis by interpreting an NC program and controls each axis drive motor according to the movement command. The above objects of the present invention correspond to a servo parameter corresponding to a mode in which both ends of a workpiece are simultaneously gripped by two main spindles and a mode in which one end of the workpiece is gripped by one of the two spindles to operate. A storage unit that stores servo parameters to be stored in advance, a command unit that interprets the NC program to determine a current operation mode, and a generation unit that generates a servo parameter switching signal corresponding to the determined operation mode. And controlling the shaft drive motor with the servo parameters automatically selected by the switching signal.

(Operation) In the present invention, the servo parameters of each axis corresponding to the number of spindles gripping the workpiece are stored in advance in correspondence with the operation mode, and correspond to the operation mode determined by interpreting the NC program. Drive control of the relevant axis by switching to the servo parameter to be performed, so that unnecessary vibration is not generated even in an operation mode in which servo control conditions are greatly different, such as a C-axis mode and a pick-off mode of a sub spindle in a CNC lathe, for example. Productivity can be easily realized.

(Embodiment) FIG. 1 is a block diagram showing an example of an NC apparatus according to the present invention in correspondence with FIG. 8, and the same components are denoted by the same reference numerals and description thereof is omitted. Servo parameters for the C-axis mode and the pick-off mode are stored as servo parameters for the sub spindle in the servo parameter storage unit 3. When the power is turned on, the sub-spindle servo parameters in the C-axis mode are read from the servo parameter storage unit 3 by the NC command unit 2, and the sub-spindle operation servo parameter storage unit 4S connected to the sub-spindle control unit 5S.
The sub-spindle servo parameters in the pick-off mode are read out from the servo parameter storage unit 3 and are subsequently read from the servo parameter storage unit 3, and are connected to the sub-spindle control unit 5S.
Transferred to 4Sb. The sub-spindle servo parameter in the C-axis mode or the sub-spindle servo parameter in the pick-off mode stored in each sub-spindle operation servo parameter storage unit 4Sa or 4Sb is a switching signal transmitted from the parameter switching signal generation unit 10. The data is transferred to the sub-spindle control unit 5S via the changeover switch 10A switched by the PS.

In such a configuration, an operation example will be described.
The parameter switching signal generation unit 10 generates a parameter switching signal PS so as to use the sub-spindle servo parameter in the C-axis mode as an initial value, and sends it to the switch 10A. The sub-spindle control unit 5S controls the position or speed of the sub-spindle using the sub-spindle servo parameters in the C-axis mode.

Next, when the NC command unit 2 detects a code (“M151” in the example of the NC program in the big off mode shown in FIG. 2) for starting synchronous rotation control of two spindles from the NC program being interpreted, the pickoff mode starts. Then, the switching of the operation mode is transmitted to the parameter switching signal generator 10. In response to this, the parameter switching signal generator 10
Generates a parameter switching signal PS to use the sub-spindle servo parameter in the pick-off mode and sends it to the changeover switch 10A. The sub spindle control unit 5S
The sub-spindle is controlled by the sub-spindle servo parameter in the pick-off mode.

Then, the NC command unit 2 uses the NC program under interpretation to
When a code for ending the synchronous rotation control of the spindle ("M150" in the example of the NC program in the pick-off mode shown in FIG. 2) is detected, it is determined that the pick-off mode has ended, and the parameter switching signal generation unit 10 switches the operation mode. Communicate the change. Hereinafter, the sub-spindle control unit 5S controls the subsequent sub-spindle using the servo parameters for the sub-spindle in the C-axis mode in the same procedure as when detecting “M151”.

(Effects of the Invention) As described above, according to the NC apparatus of the present invention, in an NC machine tool having a plurality of spindles and operating while holding a workpiece by one or two spindles, the servo control conditions are NC suitable servo parameters corresponding to multiple different operation modes
Since the axis is controlled by switching automatically in accordance with the interpretation of the program, high-speed and high-accuracy motor control can be realized according to a plurality of operation modes without impairing the servo performance.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of an NC device according to the present invention.
The figure shows an example of NC program in pick-off mode,
FIG. 3A is a diagram for explaining a lathe C-axis control function,
FIG. 4B is a view for explaining a two-spindle perfect synchronization control function, FIG. 4 is a schematic view showing an example of a CNC lathe having a sub spindle drive mechanism, and FIG. 5 is a view showing a two-spindle, two turret. FIG. 6 is a diagram for explaining a pick-off mode in the CNC lathe shown in FIG. 5, and FIG. 7 is a diagram showing a C-axis mode of two spindles alone in the CNC lathe shown in FIG. FIG. 8 is a block diagram showing an example of a conventional NC device. 1: NC program, 2: NC command unit, 3: Servo parameter storage unit, 4M, 4S, 4Sa, 4Sb, 4W, 4XA, 4ZB: Servo parameter storage unit, 5M: Main spindle control unit, 5S: Sub spindle control unit , 5W ... W axis control unit, 5XA ... XA axis control unit, 5ZB
... ZB axis control unit, 6 ... Induction motor, 7 ... Pulse generator, 8S, 8W, 8XA, 8ZB ... Synchronous motor, 9S, 9W, 9XA, 9ZB ... Resolver, 10 ... Parameter switching signal generator, 10A ... Switch , 11… Main spindle, 12… Sub spindle, 13
... A tool post, 14 ... B tool post, 15 ... Workpiece, 16 ... W-axis ball screw, 17 ... W-axis drive motor, 18 ... Spindle stand, 51 ... Main spindle work, 52 ... Sub spindle work.

Claims (1)

(57) [Claims] 1. A numerical control device for generating a movement command for each axis by interpreting a numerical control program and controlling each axis drive motor in accordance with the movement command. A storage unit for storing in advance servo parameters corresponding to a mode in which the operation is performed by holding the workpiece and servo parameters corresponding to a mode in which one end of the workpiece is gripped by one of the two main spindles. A command unit that interprets a control program to determine a current operation mode; and a generation unit that generates a switching signal of a servo parameter corresponding to the determined operation mode, and a servo automatically selected by the switching signal. A numerical control device wherein the shaft drive motor is controlled by a parameter.