KR20210106042A - Vibration control method for workpiece polishing of NC machine tools - Google Patents

Abstract

The present invention relates to a vibration control method for grinding a workpiece of an NC machine tool. According to the present invention, a machining program code is analyzed in the NC machine tool to generate and store grinding process path information. An amplitude, a vibration speed, and a vibration distance are set according to the grinding process path information, and a vibration mode is changed according to a shape of X, Y, and Z axes of the polishing surface to grind the workpiece. Therefore, it is possible to complete polishing with one transfer despite a width of the polishing surface and a shape of the X, Y, and Z axes. The vibration control method for grinding the workpiece of the NC machine tool of the present invention comprises: a processing program analysis step (S100); a vibration condition setting step (S200); a vibration mode selection step (S400); and a transport path interpolation step (S500).

Description

Vibration control method for workpiece polishing of NC machine tools

The present invention relates to control of an NC machine tool, and more particularly, to a method of controlling vibration for grinding.

In general, numerical control (NC) machine tools perform machining operations such as cutting, drilling, milling, tapping, and grinding while transporting workpieces and tools on the X, Y, and Z axes.

This NC machine tool is provided with a control unit including the NC device (20).

1 is a prior art, a control conceptual diagram of a general NC machine tool.

As shown in FIG. 1 , the control unit transmits the machining program to the NC device 20 using a Human Machine Interface (HMI) device, and the NC device 20 interprets the machining program and then feeds for an axis feed command. Interpolation is performed for the section, and a control command is issued to the servo driver 30 that controls the servo motor 31 in charge of each feed axis according to the result.

In addition, the NC device 20 interprets the machining program and then sends a control command to the spindle driver for controlling the spindle motor, which is a kind of the servo motor 31 .

Meanwhile, the NC device 20 and the HMI device 10 communicate information or signals necessary for control with the control target machine unit through a programmable logic controller (PLC 40 ), and support the control of the NC device 20 .

Figure 2 is a prior art, a conceptual diagram of abrasive machining using an NC machine tool.

As shown in FIG. 2 , in the grinding of a workpiece using an NC machine tool, the workpiece moves in the X-axis and Y-axis directions on a plane by a servomotor 31 on the table of the machine tool, and the main shaft 50 moves up and down The workpiece is polished by operating the grinding wheel 51 mounted on the tip of the main shaft 50 while moving in the Z-axis direction.

Figure 3 is a prior art, a conceptual diagram of the vibration operation of the abrasive tool in the NC machine tool.

As shown in FIG. 3, in the conventional grinding process of the NC machine tool, the vibration axis (Z-axis) repeatedly operates with a constant amplitude between the maximum point and the minimum point, and at the same time, the X-axis on a plane The work piece is polished while the Y axis and the Y axis are transferred to the position commanded by the program.

At this time, the amplitude of the oscillation axis and the amplitude center point 60 do not change. That is, in the conventional NC machine tool for polishing, it is impossible to feed in the Z-axis direction while the abrasive tool vibrates in the Z-axis direction. Therefore, if you want to change the abrasive part of the workpiece by feeding it in the Z-axis direction, stop the vibration of the grinding wheel 51 and then move the grinding wheel 51 in the Z-axis direction with a constant amplitude after the Z-axis feed is repeated. It is processed by changing the abrasive part of the workpiece through X-axis and Y-axis feed.

As described above, in the grinding using the conventional NC machine tool, the amplitude of the grinding stone 51 does not change, and when the surface area of the workpiece is not constant because it is impossible to transfer it in the Z-axis direction during the grinding operation, through repeated axial transfer. There is a problem that the working time becomes longer by grinding.

In addition, even when the area to be polished is narrower than the amplitude of the grinding stone 51, it is necessary to grind with an unnecessarily wide amplitude, thereby causing a decrease in productivity.

In addition, if there is a protruding structure that should not be polished at the boundary of the surface of the workpiece to be polished, polishing becomes impossible, or it is difficult to polish even the main surface parts that should not be polished.

On the other hand, as a prior art, Patent Document 1 introduces a technique for generating natural vibration by an electromagnet, and using this to vibrate a table on which a workpiece is mounted and then grind it. However, when the shape of the workpiece to be polished is varied, this vibration grinding method cannot be applied to polishing workpieces of various shapes because the axis feed and vibration of the X, Y, and Z axes cannot be simultaneously performed.

KR 101791939 B

The present invention is to solve the conventional problems as described above, and an object of the present invention is to control the amplitude of the vibration axis equipped with a grinding wheel in an NC machine tool, and at the same time change the path of the amplitude center point on the X, Y, and Z axes. It is to provide a polishing control method for an NC machine tool that can be polished regardless of the width of the polishing surface of the workpiece to be polished and the shape on the X, Y, and Z axes by enabling the control.

A vibration control method for grinding a workpiece of an NC machine tool of the present invention for achieving the above object,

A machining program analysis step (S100) of interpreting a machining program code in the NC device to determine a work mode, and generating and storing abrasive machining path information according to the determined work mode (S100);

Setting the maximum and minimum points of the amplitude based on the central point of the amplitude according to the abrasive processing path information analyzed in the processing program analysis step (S100), and setting the vibration condition for determining the operating speed of the vibration axis (S200) and

A vibration mode selection step (S400) of classifying vibration modes according to the abrasive processing path information generated in the processing program analysis step (S100) (S400);

A transfer path for controlling the grinding operation to be performed in the vibration mode selected in the vibration mode selection step (S400) while the grinding wheel is transported along the X, Y, and Z axes according to the polishing processing path information stored in the processing program analysis step (S100). An interpolation step (S500) is performed.

In addition, in the vibration mode selection step (S400), the amplitude does not change from the amplitude set in the vibration condition setting step (S200) according to the abrasive machining path information generated in the machining program analysis step (S100), and the amplitude of the A first vibration mode (S410) for controlling the center point to be transferred while changing between the maximum point and the minimum point,

According to the grinding processing path information generated in the machining program analysis step (S100), the amplitude is controlled to be changed in the vibration condition setting step (S200), and the central point of the amplitude does not change between the maximum point and the minimum point, but in a straight direction a second vibration mode (S420) for controlling the transfer to

Control to change to the amplitude set in the vibration condition setting step (S200) according to the abrasive machining path information generated in the machining program analysis step (S100), and change the center point of the amplitude between the maximum point and the minimum point to be transferred It consists of a third vibration mode (S430) to control.

In addition, the transport path interpolation step (S500) reads the abrasive machining path information stored in the machining program analysis step (S100), and the vibration axis sets the travel distance set in the vibration condition setting step (S200) at the set amplitude and speed. The basic operation step of the vibration axis (S510) for instructing to transfer to

After the operation command of the vibration axis (Z axis) is executed in the basic operation step of the vibration axis ( S510 ), the X and Y axes command to transfer the X and Y axes to the values set in the vibration condition setting step ( S200 ). A transfer step (S520) and

In addition to the basic operation step of the vibration axis (S510), the current position of the vibration axis is checked in real time, and the vibration axis transfer step of instructing the vibration axis to be transferred in addition to the value of the vibration axis transfer path set in the vibration condition setting step (S200) (S530).

In addition, in the X, Y axis transfer step (S520), when the value of the transfer path of the X axis and the Y axis except for the vibration axis (Z axis) is linear transfer, it is controlled to be transferred in a straight line to a designated corresponding position, and the transfer path If the value is a curve, it controls to be transferred to the curve through circular interpolation.

In addition, the vibration shaft transfer step (S530),

When the current vibration mode is the first vibration mode (S410) and the movement of the center point of the amplitude before and after the movement of the movement path of the vibration axis is a straight line, the movement of the center point of the amplitude is controlled to be transferred in a straight line, and the transfer path of the vibration axis is If the movement of the center point of the amplitude before and after movement is a circular arc, it controls the transfer path with the changed center point of the amplitude to be transferred through circular interpolation,

When the current vibration mode is the second vibration mode (S420), the amplitude commanded in the vibration axis basic operation step (S510) is the maximum point of the amplitude according to the vibration axis transport path set in the vibration condition setting step (S200) and The minimum point is recalculated to control the changed amplitude,

When the current vibration mode is the third vibration mode (S430), the center point and the amplitude of the amplitude commanded in the basic operation step (S510) of the vibration axis are amplitudes according to the vibration axis transport path set in the vibration condition setting step (S200). The change of the center point is recalculated, and the maximum and minimum points of the amplitude are recalculated for the change of the amplitude, and the center point and the amplitude of the changed amplitude are controlled.

In addition, after the vibration condition setting step (S200), the vibration processing operation is performed by determining whether the condition set in the vibration condition setting step (S200) is a condition for executing a vibration processing operation or a general operation condition other than vibration processing. If the condition to be executed, it further includes a vibration processing determination step (S300) to perform the next step.

According to the present invention, even if the surface area of the workpiece to be polished is irregular and the position of the X, Y, and Z axes on the polishing path changes, the amplitude and the center point of the amplitude of the oscillation axis equipped with the grinding stone are simultaneously controlled, within the maximum amplitude range at once. can be polished

Therefore, when the area to be polished is large, the amplitude of the vibration shaft is maximized and the polishing time is shortened with one feed.

In addition, even when there is a protruding-shaped structure that should not be polished at the boundary of the surface of the workpiece to be polished, it is possible to increase the polishing precision by avoiding the polishing.

In addition, while cutting on the X, Y, Z axes in a general NC machine tool, the tool mounted on the main shaft is replaced with a grinding stone to realize the X, Y, and Z axis feed control at the same time as the Z axis vibration. As no equipment is required, economic benefits and reduction of working time can be achieved.

1 is a prior art, a control conceptual diagram of a general numerical control machine tool.
Figure 2 is a prior art, a conceptual diagram of abrasive machining using an NC machine tool.
Figure 3 is a prior art, a conceptual diagram of the vibration operation of the abrasive tool in the NC machine tool.
4 is a control flowchart for grinding a workpiece according to an embodiment of the present invention.
5 is a conceptual diagram of an operation of the first vibration mode in which only the central point of the amplitude is changed without changing the amplitude as an embodiment of the present invention.
6 is a conceptual diagram of the operation of the second vibration mode in which the amplitude is changed and the center point of the amplitude is not changed according to an embodiment of the present invention.
7 is a conceptual diagram illustrating an operation of a third vibration mode in which an amplitude and a center point of the amplitude are simultaneously changed according to an embodiment of the present invention.
8 is a flowchart of interpolation of a polishing transport path according to vibration mode analysis as an embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

Before describing the embodiment of the present invention, terms commonly applied to the present embodiment will be described. In this embodiment, the conveying axis refers to the X, Y, and Z axes meaning left, right, front and rear, up and down directions, or any one axis corresponding to the operation or control of the embodiment. Each axis is operated by a servomotor 31 . In this embodiment, the meaning of controlling the axis or the transfer axis means controlling the servomotor 31 .

In addition, in this embodiment, the vibration axis is also expressed as the Z-axis, and also means the main shaft 50 and the grinding stone 51 mounted on the tip of the main shaft 50 . The transfer of the oscillation axis refers to movement of the amplitude center point 60 in the Z-axis direction, not the oscillation motion having an amplitude.

In addition, in this embodiment, oscillation refers to the repeated movement of the grinding stone 51 in a sine waveform between the maximum and minimum points based on the amplitude center point 60 .

4 is a control flowchart for grinding a workpiece according to an embodiment of the present invention.

First, the processing program analysis step (S100) is executed.

In this step, when the operator inputs a machining program to the NC device 20 through the HMI device 10 for grinding the workpiece, the NC device 20 interprets the machining program code to determine the working mode, It creates and stores the grinding process path information according to the working mode.

As a next step, the vibration condition setting step (S200) is executed.

In this step, according to the abrasive machining path information analyzed in the machining program analysis step (S100), as shown in FIG. 3, the maximum and minimum points of the amplitude are set based on the amplitude center point 60, and the operating speed of the vibration axis is set. decide

As a next step, the vibration processing determination step (S300) is executed.

In this step, it is determined whether the condition set in the vibration condition setting step (S200) is a condition for performing vibration processing or a general processing execution condition other than vibration processing, and if it is a condition for executing vibration processing, the next step is performed. .

As a next step, the vibration mode selection step (S400) is executed.

In this step, when the vibration processing is determined in the vibration processing determination step (S300), the vibration mode is changed to the first vibration mode (S410), the second vibration mode according to the abrasive processing path information generated in the processing program analysis step (S100). It is divided into a vibration mode (S420) and a third vibration mode (S430).

First, the first vibration mode ( S410 ) will be described.

5, in the first vibration mode (S410), the amplitude varies from the amplitude set in the vibration condition setting step (S200) according to the abrasive machining path information generated in the machining program analysis step (S100). Without it, the amplitude center point 60 is controlled to be transferred by changing between the maximum and minimum points.

Therefore, in the first vibration mode (S410), the width of the polishing surface of the workpiece is constant, but the polishing surface can grind the workpiece having various shapes on the X, Y, and Z axes.

That is, when the width of the polishing surface is constant and the shapes on the X, Y, and Z axes are varied, the shapes on the X, Y, and Z axes with the same amplitude can be polished with one feed within the maximum amplitude range. Here, the maximum amplitude refers to the maximum feed range of the Z-axis of the machine tool.

Therefore, in the first vibration mode (S410), there is no need to increase the amplitude unnecessarily in grinding a workpiece having a singular shape on the X, Y, and Z axes as in the prior art, and if the displacement on the Z axis is changed, the X and Y axes are repeated. There is no need to grind while transporting, so that the productivity of the grinding process of the workpiece can be increased.

In addition, when polishing in the first vibration mode (S410), even if there is a structure that causes interference adjacent to the polishing surface, it is possible to avoid this and proceed with the polishing operation.

The second vibration mode S420 will be described.

As shown in FIG. 6 , in the second vibration mode ( S420 ), the amplitude changes in the amplitude set in the vibration condition setting step ( S200 ) according to the abrasive machining path information generated in the machining program analysis step ( S100 ). It is controlled so that the amplitude center point 60 is not changed between the maximum point and the minimum point and is controlled to be transferred in a linear direction.

In this way, in the second vibration mode (S420), even if the width of the polishing surface of the workpiece is different, the workpiece having a straight transport path can be polished with one feed. That is, even if the shape of the X and Y axes on the transfer path of the polishing surface is varied, when the vibration axis (Z axis) is straight, the amplitude is different and polishing can be performed at once in response to the change in the width of the polishing surface.

Therefore, even in the second vibration mode (S420), there is no need to increase the amplitude unnecessarily as in the prior art, and if the displacement on the Z-axis is changed, there is no need to grind while repeatedly feeding the X and Y axes, thereby increasing the abrasive machining productivity of the workpiece. can be raised

Similarly, when polishing in the second vibration mode (S420), even if there is a structure that causes interference adjacent to the polishing surface, it is possible to avoid this and proceed with the polishing operation.

The third vibration mode ( S430 ) will be described.

7, the third vibration mode (S430) is controlled to change to the amplitude set in the vibration condition setting step (S200) according to the abrasive machining path information generated in the machining program analysis step (S100), and , the amplitude center point 60 is also changed between the maximum point and the minimum point to control the transfer.

As such, in the third vibration mode (S430), the width of the workpiece polishing surface on the vibration axis (Z axis) is irregular, and the amplitude center point 60 of the vibration axis (Z axis) is not a straight line. can do. That is, even if the transport path of the oscillation axis (Z axis) is not a straight line and the width of the polishing surface is varied, polishing can be performed at once along the shape on the X and Y axes in response to the change in the width of the polishing surface.

Therefore, even in the third vibration mode (S430), there is no need to increase the amplitude unnecessarily as in the prior art, and if the displacement on the Z-axis is changed, there is no need to grind while repeatedly feeding the X and Y axes, thereby increasing the grinding productivity of the workpiece. have.

Similarly, even in the third vibration mode ( S430 ), even if there is a structure that causes interference adjacent to the polishing surface, it is possible to avoid this and proceed with the polishing operation.

Next, the transport path interpolation step (S500) is executed.

In this step, the polishing operation is performed in the vibration mode selected in the vibration mode selection step (S400) while the grinding wheel 51 moves the X, Y, and Z axes according to the polishing processing path information stored in the processing program analysis step (S100). This is the step that controls the execution.

8 is an embodiment of the present invention, a flow chart for interpolation of the grinding transport path according to the vibration mode analysis.

First, the vibration axis basic operation step (S510) is performed.

In this step, the grinding processing path information stored in the machining program analysis step (S100) is read, and the vibration axis (Z axis) is instructed to feed the travel distance set in the vibration condition setting step (S200) at the set amplitude and speed. do.

Next, the X, Y axis transfer step (S520) is performed.

In this step, after the operation command of the vibration axis (Z axis) is executed in the basic operation step (S510) of the vibration axis (Z axis), the X and Y axes are transferred to the value set in the vibration condition setting step (S200). command as much as possible.

At this time, if the values of the X-axis and Y-axis, except for the vibration axis (Z-axis), are linear feed, control is performed so that the feed path value is straight up to the designated position. Controlled to be transported in a curve.

Next, the vibration shaft transfer step (S530) is performed.

This step is a step of commanding additional feed of the vibration axis (Z axis) in addition to the basic operation step (S510) of the vibration axis, confirming the current position of the vibration axis (Z axis) in real time, and setting the vibration condition ( S200) commands the oscillation axis (Z axis) to be transferred according to the value of the oscillation axis (Z axis) transport path value.

At this time, if the current vibration mode is the first vibration mode (S410) and the transfer path before and after the movement of the vibration axis (Z axis) is a straight line, the vibration axis (Z axis) is the amplitude center point 60 of the changed transfer path. Controlled to be transferred in a straight line. However, when the transfer path before and after the movement of the vibration axis (Z axis) is a circular arc, the vibration axis (Z axis) controls the changed transfer path so that the amplitude center point 60 is transferred through circular interpolation.

On the other hand, when the current vibration mode is the second vibration mode (S420) in which the amplitude is irregular and the transfer path of the vibration axis (Z axis) is a straight line in the vibration axis transfer step (S530), the vibration axis basic operation step (S510) The amplitude commanded in ) is controlled to the changed amplitude by recalculating the maximum and minimum points of the amplitude according to the vibration axis (Z axis) transport path set in the vibration condition setting step (S200).

On the other hand, when the current vibration mode is the third vibration mode (S430) in which the amplitude and the amplitude center point 60 are changed in the present vibration axis transfer step (S530), the amplitude commanded in the vibration axis basic operation step (S510) The center point 60 and the amplitude recalculate the change of the amplitude center point 60 according to the oscillation axis (Z axis) transport path set in the vibration condition setting step (S200), and the maximum and minimum amplitudes for the change in amplitude as well. Controlled by the amplitude center point 60 and amplitude changed by recalculating the point.

As in the above embodiment, in the present invention, even if the surface area of the workpiece to be polished is irregular and the position of the X, Y, and Z axes on the polishing path changes, the amplitude and the amplitude center point (60) of the vibration axis mounted with the grinding stone (51) By simultaneously controlling the

Therefore, when the area to be polished is large, the amplitude of the vibration shaft is maximized and the polishing time is shortened with one feed.

In addition, even when there is a protruding-shaped structure that should not be polished on the surface boundary of the workpiece to be polished, it is possible to increase the polishing precision by avoiding the polishing.

In addition, while cutting on the X, Y, Z axes in a general NC machine tool, the tool mounted on the main shaft 50 is replaced with a grinding stone 51 to realize the X, Y, and Z axis feed control at the same time as the Z axis vibration. By doing so, a separate dedicated polishing equipment is not required, thereby achieving economic benefits and shortening of working time.

10: HMI device
20: NC device
30: servo driver
31: servo motor
40: PLC
50: main shaft
51: grinding stone
60: amplitude center point
S100: part program analysis stage
S200: vibration condition setting step
S300: Vibration processing determination step
S400: vibration mode selection step
S410: first vibration mode
S420: second vibration mode
S430: 3rd vibration mode
S500: Interpolation step of transport path
S510: Basic operation stage of the vibration axis
S520: X, Y axis feed step
S530: Vibration axis transfer step

Claims (6)

A machining program analysis step (S100) of analyzing a machining program code in an NC device to determine a work mode, and generating and storing abrasive machining path information according to the determined work mode;
A vibration condition setting step (S200) of setting the maximum and minimum points of the amplitude based on the central point of the amplitude according to the abrasive machining path information analyzed in the machining program analysis step (S100), and determining the operating speed of the vibration axis;
a vibration mode selection step (S400) of classifying vibration modes according to the abrasive machining path information generated in the machining program analysis step (S100);
A transfer path for controlling the grinding operation to be performed in the vibration mode selected in the vibration mode selection step (S400) while the grinding wheel is transported along the X, Y, and Z axes according to the polishing processing path information stored in the processing program analysis step (S100). A vibration control method for grinding a workpiece of an NC machine tool comprising an interpolation step (S500). According to claim 1, wherein in the vibration mode selection step (S400), the amplitude does not change from the amplitude set in the vibration condition setting step (S200) according to the abrasive machining path information generated in the machining program analysis step (S100). a first vibration mode (S410) for controlling the transfer while changing the center point of the amplitude between the maximum point and the minimum point;
According to the grinding processing path information generated in the machining program analysis step (S100), the amplitude is controlled to be changed in the vibration condition setting step (S200), and the central point of the amplitude does not change between the maximum point and the minimum point, but in a straight direction a second vibration mode (S420) for controlling the transfer to
Control to change to the amplitude set in the vibration condition setting step (S200) according to the abrasive machining path information generated in the machining program analysis step (S100), and change the center point of the amplitude between the maximum point and the minimum point to be transferred A vibration control method for grinding a workpiece of an NC machine tool, characterized in that it consists of a third vibration mode (S430) to control. According to claim 1, wherein the interpolation of the transport path (S500) reads the abrasive machining path information stored in the processing program analysis step (S100), and the vibration axis determines the transport distance set in the vibration condition setting step (S200). The basic operation step of the vibration axis (S510) for instructing to feed at the set amplitude and speed;
After the operation command of the vibration axis (Z axis) is executed in the basic operation step of the vibration axis ( S510 ), the X and Y axes command to transfer the X and Y axes to the values set in the vibration condition setting step ( S200 ). A transfer step (S520) and
In addition to the basic operation step of the vibration axis (S510), the current position of the vibration axis is checked in real time, and the vibration axis transfer step of instructing the vibration axis to be transferred in addition to the value of the vibration axis transfer path set in the vibration condition setting step (S200) (S530) Vibration control method for grinding a workpiece of an NC machine tool, characterized in that it consists of. The method according to claim 3, wherein in the X and Y axis transfer step (S520), when the value of the transfer path of the X axis and the Y axis except for the vibration axis (Z axis) is linear transfer, the control is performed so as to be transferred in a straight line to a designated corresponding position, , Vibration control method for grinding a work piece of an NC machine tool, characterized in that when the value of the feed path is a curve, control to be transferred in a curve through circular interpolation. The method of claim 3, wherein the oscillating shaft transfer step (S530),
When the current vibration mode is the first vibration mode (S410) and the transfer path before and after the movement of the vibration axis is a straight line, the transfer path with the changed center point of the amplitude is controlled to be transferred in a straight line, and the transfer path before and after the movement of the vibration axis is a circular arc In the case of , the center point of the amplitude is controlled so that the changed transport path is transported through circular interpolation,
When the current vibration mode is the second vibration mode (S420), the amplitude commanded in the vibration axis basic operation step (S510) is the maximum point of the amplitude according to the vibration axis transport path set in the vibration condition setting step (S200) and The minimum point is recalculated to control the changed amplitude,
When the current vibration mode is the third vibration mode (S430), the center point and the amplitude of the amplitude commanded in the basic operation step (S510) of the vibration axis are amplitudes according to the vibration axis transport path set in the vibration condition setting step (S200). A vibration control method for grinding a workpiece of an NC machine tool, characterized in that the change of the center point is recalculated, and the maximum and minimum points of the amplitude are recalculated for the change of the amplitude, and the center point and the amplitude of the changed amplitude are controlled. The method according to claim 1, wherein after the vibration condition setting step (S200), it is determined whether the condition set in the vibration condition setting step (S200) is a condition for executing a vibration processing operation or a general operation condition other than vibration processing, Vibration control method for grinding a workpiece of an NC machine tool, characterized in that it further comprises a vibration processing determination step (S300) to perform the next step if the condition for executing the vibration processing operation.

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