JPH01234132A - Main spindle driving device of machine tool - Google Patents

Abstract

PURPOSE:To reduce operation time required for switching an operating mode by providing a main spindle drive control device having both a function of driving a main spindle according to a lathe turning operating mode and a func tion of making a position loop control for the main spindle in the case of C-axis operating mode. CONSTITUTION:A position detector 11 having high resolving power is installed on a main spindle 8, thereby detecting the position of the main spindle 8 with good accuracy to the feedbacked to a main spindle drive control device 2. The main spindle drive control device 2 is adapted to drive the main spindle 8 in a lathe turning operating mode and control the position of the main spindle 8 in a C-axis operating mode. The lathe turning operating mode is as conven tional. In the case of selecting the C-axis operating mode, a command of a numerical control device 1 is changed from a speed command Wr to thetar of the C-axis operating mode thetar. According to the command thetar, the main spindle drive control device 2 drives an electric motor 4 to control the position of the main spindle 8. Information exchange between the numerical control device 1 and the main spindle drive control device 2 is conducted by digital bus connec tion.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of a main shaft drive device for a machine tool.

[Conventional technology]

Figure 4 is a configuration diagram of a conventional main spindle and C-axis drive system of a machine tool equipped with a numerical control device. is an induction motor, and 5 is a synchronous motor.

6 is a speed detector, 7 is a position detection key, 8 is a main shaft, 9 is a connecting gear of the induction motor 4, and 10 is a speed reducer of the synchronous motor a5.

In the figure, the speed command W output from the numerical control device 1
r@ is output to the induction motor 4 as a three-phase alternating current command via the spindle drive control device 2, and the motor a4 rotates following Wr*. The rotation of the electric motor 4 is transmitted to the main shaft 8 via the connecting gear 9 to drive it. The gear ratio of the connecting gear 9 is determined depending on the application. Further, the position command θ of the numerical control device 1 is outputted to the synchronous motor 5 as a three-phase alternating current command via the axis servo device 3, and the motor 5 rotates following the θ. The rotation of the electric motor 5 is decelerated by the deceleration &10 and transmitted to the main shaft 8, improving the servo characteristics seen from the main shaft 8. Note that the speed detector 6 detects and outputs the speed wr of the electric motor 4, and the position detector 7 outputs a signal θr corresponding to the position of the electric motor 5.

Also, A and B are connecting gears 9. The reducer 10 is connected to the main shaft 8, respectively.
It is a connecting machine that connects to the

Next, we will discuss the operation. First, when performing normal turning operation with the main shaft 8, the coupling machine A is connected and the induction motor 4 is connected to the main shaft 8 via the connecting gear 9. At this time, the coupling machine B is disconnected, and the synchronous motor 5 is disconnected from the main shaft 8. Next, the numerical control device 1 outputs a speed command Wr'' corresponding to the target rotational speed of the main shaft 8, and the main shaft drive control device 2 performs control to make the speed wr of the electric motor 4 follow Wr''.

That is, in the turning operation mode, the spindle drive control device 2 performs speed loop control of the spindle 8.

Next, when performing C-axis operation (contour operation), the connection iA is disconnected and the main shaft 8 is disconnected from the induction motor 4. Further, the main shaft 8 is connected to the synchronous motor 5 by connecting the connection 3B. Then, the numerical control device 1 outputs a position command θr* corresponding to the target position of the main shaft 8, and the shaft servo device 3 performs control to cause the position θ of the synchronous motor 5 to follow the position θ. That is, in the C-axis operation mode, the servo device 3 performs position loop control (C-axis control) of the main shaft 8. In this case, simply improving the positioning accuracy is not enough;
High servo rigidity is required to withstand axial cutting.

[Problem to be solved by the invention]

By the way, as mentioned above, when performing C-axis operation in a machine tool, the controller and electric motor for controlling it are the axis servo device 3 and the synchronous electric motor 5, which are suitable for 9-positioning.
It is common to use .

However, in the combination of a normal axis servo device and a single synchronous motor, the output torque is not large enough to withstand C-axis cutting. A reduction gear 10 having a reduction ratio is arranged to dramatically increase servo rigidity. In this case, the final axis to be controlled is the same main axis both in the turning M rotation mode and in the C-axis operation mode.

(1) In the turning operation mode, the main shaft 8 is
The connecting gear 9 is connected and the reducer 10 is disconnected to drive the .

(2) In the C-axis operation mode, the main shaft 8 is driven by the synchronous motor 5, so the reducer 10 is connected and the connecting gear 9 is disconnected.

Operation is required. Therefore, switching from turning operation mode to C-axis operation mode or from C-axis operation mode to turning operation mode requires a sequence of connecting and disconnecting the connecting gear 9 and reducer 10, which requires a considerable amount of time. become. Also, since two systems are required: one system consisting of the main shaft drive control device 2, induction motor 4, and connecting gear 9, and the other system consisting of the shaft servo device 3, synchronous motor 5, and reduction gear 10, the structure of the machine However, the problem is that the system becomes complicated, leading to an increase in equipment costs.

The present invention has been made to solve the above-mentioned problems of conventional devices, and aims to provide a main shaft drive device for a machine tool that shortens the operation time associated with switching the operation mode and simplifies the machine structure. It is something.

[Means to solve the problem]

In order to achieve the above objects, the main spindle drive device of the machine tool according to the present invention has the function of driving the main spindle in the turning operation mode and the position loop control of the main spindle in the C-axis operation mode. It is configured to have multiple functions.

[For production]

Since the main shaft drive device of the machine tool is configured as above,
It has become possible to shorten the switching time from turning operation mode to C-axis operation mode and simplify the structure of the nine machines.

[Embodiment] Fig. 1 is a configuration diagram of a main shaft drive device of a machine tool showing an embodiment of the present invention. In Fig. 1, 1 to 9 are the same parts as the conventional device,
is a position detector.

As shown in the figure, a position detector 11 having a high resolution capable of detecting 9, for example, 1/1000' is attached to the main shaft, and the main shaft 8
The position of is detected with high precision and fed back to the spindle drive control device 2. Further, the main spindle drive control device 2 is configured to drive the main spindle 8 in the turning operation mode and also to control the position of the main spindle 8 in the C-axis operation mode.

Next, the operation will be explained. First, the turning operation mode is the same as the conventional device. When the C-axis operation mode is selected, the command of the numerical control device 1 switches from the speed command Wr'' to θ of the C-axis operation mode. Based on the command θr1, the main shaft drive device 2 drives the electric motor 4 and changes the position of the main shaft 8. Information exchange between the numerical control device 1 and the spindle drive control device 2 is performed by digital bus connection.As a result, synchronized operation with other axes becomes possible.

It is possible to eliminate the influence of noise and lack of resolution caused by analog.

Figure 2 is a diagram explaining each operation when switching from the turning operation mode to the C-axis operation mode, where (a) is the conventional device;
bl is based on the device shown in this example.

As shown in the figure, the present invention greatly reduces the amount of operation required when switching the operation mode, and as a result, the time t required for switching (the time from turning on the C-axis operation mode to completing the home return) is shorter than that of the conventional device. It was decided to reduce the time from 10 to 15 seconds to about 5 seconds.

Note that although this embodiment describes the operation when switching from the turning operation mode to the C-axis operation mode, the interval for switching from the C-axis operation mode to the turning operation mode is also the same.

Further, in the above embodiment, the reducer 10 for C-axis control
is no longer necessary, but a connecting gear 9 for connecting the induction motor 4 and the main shaft 8 is still required.

Therefore, as shown in FIG. 3, if the main shaft 12 is configured with an induction motor built-in, the connecting gear 9 can also be omitted.

〔Effect of the invention〕

The present invention is a machine tool in which the spindle drive control device is configured to control not only the turning operation mode but also the C-axis operation mode, so that the switching time between operation modes can be greatly shortened, and the spindle drive control device can also control the C-axis operation mode. Only one system is required, resulting in a low-cost spindle drive device with high efficiency and high reliability.

Further, according to the present invention, since the main shaft has a built-in induction motor, a connecting gear between the induction motor and the main shaft is not required, and a lower cost main shaft driving device can be obtained.

[Brief Explanation of the Drawings] Fig. 1 is a configuration diagram of a main shaft drive device showing an embodiment of the present invention, and Fig. 2 is a diagram showing the operation when switching operation modes (a
) is a diagram showing the operation of the conventional device, (b) is a diagram showing the operation of the device according to the present invention, FIG. 3 is a configuration diagram of a main shaft drive device showing another embodiment of the present invention, and FIG. 4 is a diagram showing the configuration of the conventional device It is a diagram. In the figure, 1 is a numerical control device, and 2 is a spindle drive control device. 4 is an induction motor, 6 is a speed detector, 8 is a main shaft, 9 is a connecting gear, 11 is a position detector, and 12 is an induction motor built-in main shaft. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (2)

[Claims] (1) A spindle drive device for a machine tool that includes a numerical control device, a spindle drive control device, and an induction motor, and controls the speed of the spindle by following a speed command from the numerical control device, wherein the spindle drive control device is A spindle drive device for a machine tool, characterized in that it is configured to control the position of a spindle by following a C-axis position command of the numerical control device as well as a speed command of the numerical control device. (2) A main shaft drive device for a machine tool according to claim 1, characterized in that the main shaft is built-in and integrated with an induction motor.