KR20180134030A - Numerical controller for a machining tool - Google Patents

Abstract

Disclosed is a numerical controller for a machine tool. The numerical controller comprises: a temperature detecting unit detecting stop temperature of a machine tool and drive motors connected to the machine tool and driving an auxiliary device supplying a workpiece to be processed and a tool; an inverter individually connected to the drive motors and controlling rotation speed and output of the drive motors; and a central control unit setting one of a workpiece process mode performing process to the workpiece with the drive motors according to the stop temperature and a lubricant dissolving mode dissolving grease lubricant solidified at the low temperature. By automatically dissolving grease coagulated by the low temperature, the automation characteristics of a machining center by the numerical controller may be enhanced.

Description

{Numerical controller for a machining tool}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a numerical control apparatus for a machine tool, and more particularly, to a numerical control apparatus for a machine tool capable of automatically adjusting the rotational speed of a main shaft according to an atmospheric temperature to increase the fluidity of a coagulated lubricating grease before driving the machine tool And a control device.

2. Description of the Related Art [0002] In recent years, with the rapid development of the mechanical and electronic device industry, it has been required to produce a large quantity of workpieces having various shapes and sizes from large structures to fine parts with high precision, ) Machining tool has been increasing dramatically.

Numerical control machine tools are divided into consecutive detailed steps for machining the workpiece, and the shape and dimensions required in each machining step are prepared in advance as a program, and the machine tool and the ancillary equipment are controlled according to the programmed algorithm to automatically machine the workpiece do.

[0002] A general numerical control machine tool is a machine tool which is controlled in accordance with a machining program input to a numerical controller and automatically mounts a plurality of tools required for machining the workpiece, A tool magazine, an automatic tool changer (ATC) that automatically provides the appropriate tool for the machining step from the tool magazine, an attachment that reinforces the tool's characteristics and extends the machining range in response to the selected tool A machining center in which various auxiliary devices such as an automatic attachment changer (AAC) that automatically exchanges and an automatic pallet changer (APC) that automatically transfers workpieces to a fixed pallet are located / RTI >

Therefore, the driving of the auxiliary devices such as the tool magazine, ATC, AAC and APC as well as the driving of the table, the column structure and the spindle assembly constituting the machine tool are organically controlled by the numerical control device, .

At this time, most of the driving elements constituting the ancillary apparatus as well as the machine tool are driven by the drive shaft supported by the bearings, and lubricants are used to reduce the friction of motion during the driving process. Particularly in a machine tool, semi-solid grease lubrication is widely used rather than liquid oil lubrication due to the advantage of performing a lubrication function for a long time by charging once.

However, the grease lubricant is a semi-solid state property and does not flow unless an external force is applied to the yield point, which requires a large initial driving force as compared with oil lubrication. In particular, the apparent viscosity of the grease lubricant in a semi-solid state increases with lower temperature, so that a considerable initial driving force must be provided when the machining center starts driving at a low temperature.

Accordingly, when the machining center starts to operate after being exposed to a low temperature for a long time, in order to recover the fluidity of the hard grease lubricant due to the low temperature, the worker repeatedly operates the main shaft of the machine tool manually to change the solidification state of the grease lubricant And the numerical controller is operated after releasing it.

However, the initial manual operation for releasing the solidification of the grease from the lubricant every time it is started causes the life of the machining center to be reduced and the automation to be lowered. Accordingly, an oil lubrication system excellent in friction and noise characteristics without any restriction on the yield point or the apparent viscosity has been proposed as a drive shaft lubrication system of a machining center. However, the oil lubrication system has a complicated equipment configuration like a hydraulic circuit, requires a separate sealing means, and is not widely used due to its relatively short service life. Still, the grease lubrication system for a driving shaft of a machining center is widely used .

Accordingly, there is a demand for a new numerical control apparatus for a machine tool capable of automatically releasing the solidification state of the lubricant of grease at the time of initial operation at a low temperature.

An object of the present invention is to provide a numerical control apparatus for a machine tool capable of detecting an initial temperature of a machining center drive shaft of a drive shaft and automatically releasing a coagulation state of a low temperature grease to increase fluidity of a grease lubricant.

According to an aspect of the present invention, there is provided a numerical control apparatus for a machine tool, including a machine tool and at least one auxiliary A temperature detector for detecting a stop temperature of driving motors for driving the apparatus, an inverter connected to the driving motors individually for controlling a rotational speed and an output of the driving motor, A workpiece processing mode for performing machining on the workpiece, and a lubricant dissolving mode for dissolving the grease lubricant solidified at a low temperature.

In one embodiment, the central control unit includes a reference temperature storage unit that stores a reference temperature that is set by an operator and is compared with the stop temperature, and a reference temperature storage unit that compares the stop temperature and the reference temperature to set the drive motor to the workpiece machining mode And a motor control signal generator for selectively generating a lubricant control signal for setting the drive motor to the lubricant dissolving mode.

In one embodiment, the lubrication control signal is generated when the stop temperature is lower than the reference temperature to drive the drive motor at a frequency of 30 Hz to 60 Hz.

In one embodiment, the central control unit includes a timer for detecting the elapsed time from the application time point of the machining control signal to the drive motor, and the lubrication control signal is at least two hours from the application of the final machining control signal Is generated after elapsing.

In one embodiment, the inverter includes a single signal transfer unit connected to the motor control signal generator and transmitting either the machining control signal or the lubrication control signal, and a single signal transfer unit connected separately to the machine tool and the auxiliary equipment And a signal switch for selectively controlling a motor control signal applied to the machine tool and the auxiliary device.

According to the numerical control apparatus for machine tool according to the exemplary embodiments of the present invention as described above, when the operation signal to the machining center is applied, the coagulated grease is automatically released at low temperature before the machining operation is performed on the workpiece, It is possible to improve the grease lubrication characteristic automatically before the start of operation. Thus, it is possible to improve the inconvenience of manually operating the main shaft to dissolve the solidified grease at a low temperature.

In particular, by using a single inverter for a machine tool and a plurality of auxiliary devices, the rotation speed of the drive motor can be individually adjusted to dissolve the solidification grease of the drive shaft for each device. Thus, the driving of the machining center by the numerical controller can be automated independently of the atmospheric temperature.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a configuration diagram showing a machining center including a numerical control device for a machine tool according to an embodiment of the present invention; FIG.
2 is a flowchart showing a process of driving a machining center using the numerical controller shown in Fig.

For the embodiments of the invention disclosed herein, specific structural and functional descriptions are set forth for the purpose of describing an embodiment of the invention only, and it is to be understood that the embodiments of the invention may be practiced in various forms, The present invention should not be construed as limited to the embodiments described in Figs.

The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It is to be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but on the contrary, is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms may be used for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between. Other expressions that describe the relationship between components, such as "between" and "between" or "neighboring to" and "directly adjacent to" should be interpreted as well.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprise", "having", and the like are intended to specify the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, , Steps, operations, components, parts, or combinations thereof, as a matter of principle.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be construed as meaning consistent with meaning in the context of the relevant art and are not to be construed as ideal or overly formal in meaning unless expressly defined in the present application .

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a configuration diagram showing a machining center including a numerical control device for a machine tool according to an embodiment of the present invention; FIG.

Referring to FIG. 1, a numerical control apparatus 500 for a machine tool according to an embodiment of the present invention includes a machine tool MT and at least one A temperature detector 100 for detecting a stop temperature of driving motors for driving one auxiliary device PI; an inverter 200 connected to the driving motors individually to control a rotational speed and an output of the driving motor; And a central control unit (300) for setting the drive motor to either a workpiece processing mode for processing the workpiece according to the stop temperature and a lubricant dissolution mode for dissolving the grease lubricant solidified at a low temperature. The temperature detector 100 and the inverter 200 are connected to the single interface 400 with the machine tool MT and the auxiliary device PI.

Accordingly, the machine tool (MT), the peripheral device (PI), and the numerical control device (500) constitute a single machining center.

For example, the machine tool MT may include a table on which the workpiece is fixed, a tool for machining the workpiece and / or a spindle to which the attachment is attached, and a column structure for moving the spindle in a three-dimensional space, And performs machining on the control device 300 according to a predetermined algorithm. The auxiliary device PI is disposed adjacent to the machine tool MT and is organically driven by the numerical control device 500 according to the machining step of the machine tool to assist in the machining of the machine tool MT. For example, the auxiliary device PI may be an automatic tool changer (ATC) that automatically exchanges tools, an automatic attac- mnment changer (AAC) that automatically exchanges spindle attachments, MT), and an automatic pallet changer (APC), which automatically replaces the pallets that receive the workpieces.

At this time, the machine tool (MT) and the auxiliary device (PI) individually include a drive shaft and a drive motor that rotates the drive shaft, and the drive motor is connected to the numerical control device (500) through the interface (400). Accordingly, the machine tool (MT) and the auxiliary equipment (PI) are organically controlled by the numerical control device (500) to perform machining on the workpiece.

It is obvious that the configuration of the machine tool (MT) and the type of the auxiliary device (PI) can be variously changed according to the machining purpose of the machining center driven by the numerical control device.

The numerical controller 500 organically drives the machine tool MT and the auxiliary machine PI according to a predetermined algorithm to form a single machining center. Accordingly, the numerical control apparatus 500 controls the machine tool MT and the auxiliary apparatus PI through various driving means (not shown) and control means (not shown). The driving means and the control means are individually connected to the machine tool (MT) and the auxiliary device (PI) via the interface (400). In particular, the driving means may be connected to the machine tool (MT) and the auxiliary device (PI) through the inverter (200) to control the rotational speed and driving power of the driving motor separately.

The machine tool MT and the auxiliary device PI operate by applying a drive signal to a drive motor for rotating the drive shaft. In the normal driving environment, the numerical controller 500 can control the machine tool MT and the auxiliary device PI through the driving signals applied to the respective driving motors.

However, if the ambient temperature is so low as to interfere with the normal operation of the machining center as in the case of a single machine, smooth operation of the numerical control device 500 is prevented by the low temperature coagulation of the lubricant grease supplied to the drive shaft Receive.

The numerical controller 500 according to the present embodiment provides a lubricant dissolving mode capable of dissolving solidified grease according to the stop temperature of the drive motor at the time of initial drive for driving a smooth machining center even at a low temperature.

For example, the numerical controller 500 generates a drive check signal before transmitting a drive signal to the drive motor when a drive start signal is applied by an operator, and detects a stop temperature of each drive motor. (100).

The temperature detector 100 is individually connected to the machine tool MT and the peripheral device PI through the interface 400 to detect a stop temperature for each drive motor. For example, a thermistor is disposed on a rotor or a bush of the driving motor, and the surface temperature of the driving motor is detected according to the driving check signal generated by the central control unit 300, Lt; / RTI >

At this time, the stop temperature of the drive motor is detected as the surface temperature of the motor before start of operation after the device driven by the drive motor is stopped for a predetermined time or more and approximates the ambient temperature of the machining center.

After the machining center is driven, the drive temperature, which is the surface temperature, can be detected to be higher than the atmospheric temperature of the machining center by driving the drive motor and the drive shaft. Since the yield point may vary depending on the drive temperature, the grease that lubricates between the drive shaft and the drive bearing may not coagulate regardless of the atmospheric temperature before a certain period of time elapses from when the drive of the machining center is stopped. Therefore, the stop temperature is the surface temperature of the drive motor at a point of time after a certain time has elapsed from the last operating point of the machining center.

The stop temperature for each drive motor is transmitted to the central control unit 300 and used as a determination data for determining whether to switch the operation mode of the drive motor to the lubricant dissolving mode. For example, the stop temperature is transmitted to the motor control signal generation unit 310, and the reference temperature set in the reference temperature storage unit 320 is called up to be compared with each other to drive the drive motor in either the workpiece machining mode or the lubricant dissolution mode do.

For example, when the stop temperature of the drive motor is higher than the reference temperature, since the grease lubricant between the drive shaft and the bearing has a sufficient lubrication characteristic, it is not necessary to switch to a separate operation mode for dissolving the grease. Accordingly, the motor control signal generator 310 generates a machining control signal, which is a control signal for instructing machining on the workpiece, and the drive motor operates in the workpiece machining mode. That is, the central control unit 300 operates normally according to the conventional machining center driving procedure. In the case of the present embodiment, in the workpiece machining mode, the drive motor is controlled to operate at a frequency of about 70 Hz or more.

On the other hand, when the stop temperature of the drive motor is lower than the reference temperature, the grease lubricant of the drive shaft and the bearing shiras solidify due to the low temperature characteristic of the drive environment, so that the yield point of the grease becomes high and the lubrication characteristics are degraded. Accordingly, it is necessary to dissolve the solidified grease before driving the drive shaft to reinforce the lubricating property. In particular, since the grease solidified in comparison with the liquid grease has a relatively high yield point, the drive motor needs to be driven at a low speed and a high output in comparison with the workpiece machining mode.

Accordingly, when the stop temperature is lower than the reference temperature, the motor control signal generating unit 310 generates a lubrication control signal to operate the drive motor in the lubricant dissolving mode. In the lubricant dissolving mode, the rotation speed of the drive motor decreases and the output increases as compared with the workpiece machining mode. That is, when the drive shaft and the bearing are coupled by the coagulated grease, the drive shaft is driven at a low speed and high output to automatically dissolve the grease interposed between the drive shaft and the bearing.

In this embodiment, the driving motor uses an AC motor, and the machining control signal and the lubrication control signal are applied to the inverter 300 to control the frequency of the AC motor to control the rotational speed of the driving motor.

For example, in the lubricant dissolving mode, the drive motor is driven at a low frequency of about 30 Hz to 60 Hz, and after a certain period of operation, the rotational direction is reversed and then driven for the same time to dissolve the solidified grease between the drive shaft and the bearing . The grease dissolving operation in the clockwise direction and the counterclockwise direction is repeatedly performed to dissolve the solidified grease.

In the case of this embodiment, the lubricant dissolving mode can be set so that the low frequency operation of rotating clockwise and counterclockwise is repeated 2 to 4 times for 30 minutes.

At this time, the reference temperature may be variously set according to the properties of the grease supplied as the lubricant and the surrounding environment. For example, the operator can preset the reference temperature in consideration of the driving environment of the machining center through a control panel (not shown) connected to the central control unit 300. Therefore, when the surface temperature of the drive motor is equal to or lower than the set reference temperature, it is possible to dissolve the solidified grease automatically by operating the drive motor in the lubricant dissolving mode. For example, the reference temperature may be set to have a range of about 3 to 5.

The surface temperature of the driving motor is lower than the reference temperature depending on the driving mode of the machining center or the driving environment, but the grease between the driving shaft and the driving bearing may not be sufficiently solidified. In this case, even if the stop temperature is lower than the reference temperature, it is not necessary to operate the drive motor in the lubricant dissolving mode.

Therefore, when the machining control signal is applied to the driving motors of the machine tool (MT) and the auxiliary equipment (PI), a machining control signal timer for detecting the elapsed time from the application time point can be further arranged to be used for switching to the lubricant dissolving mode have.

Once the machining control signal is applied, the elapsed time for that drive motor from the point in time of application is measured by the timer 330. The timer operates separately for each driving motor of the machine tool (MT) and the additional apparatus (PI), and is reset again when a new machining control signal is applied to each driving motor. Therefore, the timer informs the elapsed time from the machining control signal finally applied to the drive motor.

If the stop temperature of the specific drive motor is lower than the reference temperature, the motor control signal generator 310 calls the elapsed time of the last machining control signal boot of the drive motor from the timer to switch the drive motor to the lubricant dissolving mode It can be used as a material to judge.

In the case of this embodiment, even when the stop temperature is lower than the reference temperature, the motor control signal generation unit 310 only performs the lubrication And generates a control signal. It is obvious that the elapsed time from the application of the final machining control signal capable of generating the lubrication control signal can be different depending on the properties of the grease used and the driving environment of the machining center.

The machining control signal and the lubrication control signal generated by the motor control signal generating unit 310 are transmitted to the drive motors of the machine tool MT and the auxiliary machine PI through the inverter 200. [

In one embodiment, the inverter 200 includes a single signal transmitter 210 connected to the motor control signal generator 310 and transmitting either the machining control signal or the lubrication control signal, And a signal switch 220 selectively connected to the auxiliary device PI to selectively control a motor control signal applied to the machine tool MT and the auxiliary device PI.

The stop temperature of the drive motor is transmitted to the motor control signal generation unit 310 together with information on the drive motor. For example, a serial number is given to the spindle spindle drive motor of the machine tool (MT) and the spindle spindle drive motor of each auxiliary device (PI), and the temperature detector (100) stops the drive motor of each machine tool and auxiliary device Temperature is individually detected and transmitted to the motor control signal generator 310 together with the serial number of the drive motor.

The motor control signal generator 310 selectively generates a machining control signal or a lubrication control signal for the drive motor by comparing the stop temperature of the drive motor and the reference temperature. Therefore, the machining control signal and the lubrication control signal generated by the motor control signal generating section 310 are applied to the signal transfer section 210 together with the serial number of the drive motor.

The switch 220 analyzes the motor serial number added to the motor control signal transmitted to the signal transmitting unit 210, connects the switch of the drive motor corresponding to the serial number, and cuts off the remaining switches. Therefore, the motor control signal is transmitted to the drive motor corresponding to the added serial number. Accordingly, the driving motors for the machine tool MT and the plurality of auxiliary devices PI can be individually controlled through the single inverter 200. [

2 is a flowchart showing a process of driving a machining center using the numerical controller shown in Fig.

First, when the operator operates the operation switch to apply a system operation signal for operating the machining center to the numerical control device 500 (step S100), the numerical control device 500 generates a machining control signal for machining the workpiece A drive check signal is generated first (step 200).

The stop temperature which is the surface temperature of the driving motor of the machine tool (MT) and the auxiliary device (PI) is detected through the temperature detector (100) by the drive check signal (step S300). The stop temperature is assigned to each drive motor of the machine tool and the auxiliary device, and is detected for each drive motor.

The detected temperature is transmitted to the motor control signal generation unit 310 of the central control unit 300 and the reference temperature stored in the reference temperature storage unit 320 is also called to the motor control signal generation unit 310. The reference temperature is directly set by the user considering the driving environment of the machining center individually. Can be manually entered through a user interface such as a control panel.

If the detected stop temperature of the drive motor is compared with the reference temperature (step S400) and the stop temperature is higher than the reference temperature (N), the liquid level of the grease is sufficient and the lubrication characteristics are good. Generates a machining control signal. Accordingly, the drive motor is operated in the workpiece machining mode (step S700), and the drive shaft connected to the drive motor is driven for the purpose of machining the workpiece to be machined. In the case of the present embodiment, the drive motor is provided with an alternating current motor and operates in a workpiece processing mode at a frequency of about 70 Hz or more.

On the other hand, when the detected stop temperature of the drive motor is compared with the reference temperature (step S400) and the stop temperature is lower than the reference temperature (Y), the grease solidifies due to the low atmospheric temperature, The signal generator 310 generates a lubrication control signal. Accordingly, the driving motor is operated in the lubricant dissolving mode (step S600), and the driving shaft connected to the driving motor is driven at low speed and high output to dissolve the solidified grease.

In the case of this embodiment, in the lubricant dissolving mode, the drive motor performs a grease dissolving operation that rotates at low frequencies of about 30 Hz to 60 Hz and alternately rotates in the time and counterclockwise directions for a certain period of time. The time and frequency of the grease dissolving operation are appropriately adjusted according to the characteristics of the drive shaft and the driving environment of the machining center.

In particular, when the stop temperature is lower than the reference temperature (Y), the motor control signal generating unit 310 calculates the elapsed time from the machining control signal finally applied to the drive motor to the point at which the stop temperature is compared with the reference temperature, (Step S500), and the lubrication control signal can be selectively generated even when the stop temperature is lower than the reference temperature.

For example, when the elapsed time from the last drive point of the drive motor to the comparison point of the stop temperature and the reference temperature is equal to or shorter than the reference time, although the stop temperature is lower than the reference temperature, The motor control signal generation unit 310 can operate the drive motor in the workpiece operation mode in consideration of the working efficiency.

Particularly, when a part of the additional device PI is detached from the machining center and then incorporated into the machining center as necessary, the driving efficiency of the machining center can be enhanced if the PI is newly incorporated into the equipment configuration of the numerical control device 500.

According to the numerical control apparatus for a machine tool as described above, when the operation signal to the machining center is applied, the coagulated grease is automatically loosened before the workpiece is machined so that the grease lubrication characteristic Can be improved. Thus, it is possible to improve the inconvenience of manually operating the main shaft to dissolve the solidified grease at a low temperature.

In particular, by using a single inverter for a machine tool and a plurality of auxiliary devices, the rotation speed of the drive motor can be individually adjusted to dissolve the solidification grease of the drive shaft for each device. Thus, the driving of the machining center by the numerical controller can be automated independently of the atmospheric temperature.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the following claims. It can be understood that it is possible.

Claims (5)

A temperature detection unit connected to the machine tool and the machine tool in accordance with the drive check signal to detect a stop temperature of the drive motors for driving the at least one auxiliary apparatus for supplying the workpiece and the tool to be machined;
An inverter connected to the drive motors individually to control a rotational speed and an output of the drive motor; And
And a central control unit for setting the drive motor to one of a workpiece machining mode for machining the workpiece according to the stop temperature and a lubricant dissolution mode for dissolving the grease lubricant solidified at a low temperature. The apparatus according to claim 1, wherein the central control unit comprises: a reference temperature storage unit that stores a reference temperature that is set by an operator and is compared with the stop temperature; and a reference temperature storage unit that compares the stop temperature and the reference temperature, And a motor control signal generator for selectively generating a machining control signal to be set and a lubrication control signal for setting the drive motor to the lubricant dissolving mode. The numerical controller for a machine tool according to claim 2, wherein the lubricating control signal is generated when the stop temperature is lower than the reference temperature to drive the drive motor at a frequency of 30 Hz to 60 Hz. 4. The apparatus according to claim 3, wherein the central control unit includes a timer for detecting an elapsed time from an application time point of the machining control signal to the drive motor, and the lubrication control signal includes at least two hours A numerical control device for a machine tool, which is generated after elapsed time. 3. The apparatus of claim 2, wherein the inverter includes a single signal transfer unit connected to the motor control signal generator and transmitting either the machining control signal or the lubrication control signal, And a signal switch for selectively controlling a motor control signal applied to the machine tool and the auxiliary device.

Images