JP2023048942A - Grinding device - Google Patents

Abstract

To provide a technique for realizing a function for mitigating excessive cutting when changing override commands, in a grinding device and a control method thereof.SOLUTION: When operating an override switch, a function is prepared for automatically conducting an operation in which a grindstone rotary device is fed once in a radial direction at a linear axis in a direction of distancing from a grinding object in applying override so as to gradually return to original coordinates, thus the switch shall not be applied as it is to a control device. In addition, a mechanism is comprised for automatically determining whether an exterior side is ground or an interior side is ground in order to move the grindstone rotary device, by combining operation of a previous automatic cutting device and a type of command in a rotational direction of circular interpolation.SELECTED DRAWING: Figure 8

Description

The present invention relates to a grinding apparatus (and its control method), and more particularly to a grinding wheel rotating apparatus with a grinding wheel, such as a jig grinder, which can be radially advanced and fixed on a linear axis called an incision apparatus, and which can be A grinding device that can grind the inner or outer surface of a circle by rotating it with a separate rotating device.In addition, the coordinate space of the X-Y-Z three axes can be controlled simultaneously by a feeding device for each rotating device. Apparatus (and its control method).

Grinding of an object to be processed (hereinafter referred to as a "workpiece") by a jig grinder is performed by, for example, a so-called single-column type machine. This is realized by vertically moving (in the Z-axis direction) a so-called quill having a grindstone and a high-frequency motor for rotating it attached to the lower end thereof while moving (in the X-axis direction). In the case of a so-called double-column type jig grinder (gantry machine), the workpiece is moved only in the X-axis direction, and the grindstone side (spindle main body) is moved in the Y-axis direction. It goes without saying that the naming of the axes, such as the X-axis, the Y-axis, and the Z-axis, can be interchanged by the manufacturer of the machine.

In more detail, there are roughly two types of grinding as follows. One is to eccentrically (cut into) the rotation axis of the grindstone (grindstone shaft) with respect to the main spindle so that the grindstone rotates about the grindstone axis and the grindstone is turned by the continuous rotation of the main spindle, that is, the grindstone rotates in a planetary fashion. At the same time, by moving the quill up and down, the grindstone is helically turned, and the inner wall is evenly ground to achieve perfect circle boring. In this case, the diameter of the hole is basically determined according to the size of the outer diameter of the grindstone and the degree of eccentricity of the grindstone shaft (the depth of cut (for example, maximum 50 mm)). It is a grinding process that performs uneven non-perfect circle drilling and processing of edges with uneven curvature.In this case, so-called chopping processing is performed.Specifically, the grinding wheel shaft is not eccentric, or the center of rotation of the main shaft The grindstone is eccentric in the opposite direction (negative direction) to the above-described cut by an amount corresponding to the radius of the grindstone so that the outer circumference of the grindstone coincides with the outer circumference of the grindstone. Perform by Y-axis feeding.After that, the grindstone is automatically eccentric by the amount of net cutting processing, that is, chopping is performed while performing automatic cutting.At this time, when cutting into the processing surface of the workpiece with an uneven curvature with the grindstone, the workpiece The angle control (indexing) of the spindle is performed so that the normal line at the processing point where the contact is always aligned with the cutting direction of the grindstone.Patent Document 1 discloses the main configuration of such a jig grinder.However, , Patent Document 1 omits the configuration for moving the grinding wheel up and down.Here, the rectilinear reciprocating motion is called chopping, and restrictions are set on the reciprocating speed used in general chopping processing. do not define

JP 2006-102891 A

In the jig grinder described above, depending on the selection of CNC functions and the creation of control software, for example, immediately after operating the override switch or immediately after changing the settings of the oscillation range, speed, and center position, the surface may come close to Therefore, when changing the setting of the oscillation range, speed, and center position including the override switch during chopping and oscillation grinding, a command to separate the edge of the reciprocating range of the grinding wheel and the front surface of the grinding surface is superimposed for a moment. Development of software or mechanical devices that later apply an override switch or the aforementioned setting changes to gradually return to normal position with number of strokes, thereby preventing the grinding wheel from striking the surface beyond the range of strokes. Therefore, the present inventors have filed Japanese Patent Application No. 2018-160030 and Japanese Patent Application No. 2019-107534 for a grinding apparatus and a control method thereof that meet such a demand.

The above-described feeding device is processed so as to face the cutting device in the normal direction, outward or inward, using another rotating device while performing circular interpolation in the (XY) plane, for example, two axes, Processing of sizes exceeding the range of feed of the cutting device is also possible. In addition, there are many cases in which the speed of circular interpolation can be freely changed by the operator by means of an override switch.
However, if the speed of circular interpolation is changed, a deviation may occur depending on the order of the servo system and the presence or absence of feedforward control, and overcutting may occur due to centrifugal force or the like. Also, immediately after the override switch is operated, there is a possibility that the operator may feel that the steering wheel is being cut too much, especially during sudden changes.
Here, for example, the radius decrease ΔR in a servo control system for a typical machine tool, even if only the servo is used, is given by It is approximated as shown in Equation (2) below.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a technique for realizing a function of reducing excessive cutting when an override command is changed in a grinding apparatus and a control method thereof.

As a result of intensive research on the configuration of the grinding apparatus and its control method that realizes the overcutting mitigation function when the override command is changed, the present inventor found that instead of applying it to the control device as it is when the override switch is operated, Once I came up with the idea of applying a feed override to the grinding wheel rotating device in the direction far from the grinding object with the cutting device. Alternatively, when the override switch is operated, instead of applying it to the control device as it is, feed the grinding wheel rotating device once in a direction away from the grinding object in the radial direction on the linear axis, apply the override, and gradually return to the original coordinates. I came up with the idea of providing an automatic function.

Furthermore, it was found that it would be preferable if the direction of release can be changed when grinding the outer side and when grinding the inner side.

Furthermore, in order to operate the above-mentioned device, it is possible to automatically judge whether the outer side is being ground or the inner side is being ground by combining the operation of the previous automatic cutting device and the type of command for the rotation direction of circular interpolation. may be provided.

Incidentally, in the escape, it is preferable to send the operation history of the automatic cutting device in a retroactive direction.

According to the present invention, in a grinding apparatus and a control method thereof, it is possible to realize a function of reducing excessive cutting when an override command is changed.

1 is a perspective view showing a jig grinder as an example of a grinding apparatus to which the present invention is applied; FIG. It is a figure for demonstrating the grinding device (jig grinder) shown in FIG. 1 with the movement or rotation direction of each axis|shaft. 2 is an enlarged view of a U-axis feeder and a grindstone shaft in the grinding device (jig grinder) shown in FIG. 1; FIG. 2 is a diagram showing the relationship between machining of a workpiece by a rotating grindstone in the grinding apparatus (jig grinder) shown in FIG. 1 and axial movement of each of the U-axis and Z-axis; FIG. 2 is a block diagram showing an outline of a control system of the grinding device (jig grinding machine) shown in FIG. 1; FIG. 4 is a graph showing the relationship between an override command, an actual rotational speed, and an automatic cutting position in the grinding apparatus and its control method of the first embodiment of the present invention; 4 is a flow chart of control processing from the start to the end of a machining process in the grinding apparatus of the first embodiment of the present invention; 2 is a functional block diagram showing an outline of a control system for circular interpolation of the grinding device (jig grinding machine) shown in FIG. 1; FIG. 1 is a functional block diagram showing an outline of a control system for general circular interpolation; FIG.

First, in order to facilitate understanding of the present invention, a grinding apparatus to which the present invention is applied will be described with reference to the drawings. FIG. 1 is a perspective view showing an example of a grinding apparatus to which the present invention is applied, and FIG. 2 is a diagram for explaining the grinding apparatus together with the movement or turning direction of each axis. The device can be pivoted in the Z-axis translation and pivoting around the Z-axis (referred to as the C-axis). The U-axis feeder can linearly move the grindstone shaft in the U-axis direction. Each axis may be a combination of multiple parallel axes. FIG. 3 is an enlarged view of the U-axis feeding device and the grinding wheel shaft in the grinding device (jig grinder), and FIG. It is a figure which shows the relationship of the axial movement of each Z-axis. As shown in FIG. 1, in a grinding apparatus (jig grinding machine) 10 to which the present invention is applied, a table feeding device 36 and a table 30 are movable on a bed 12 in the Y-axis direction (back and forth direction) via rails 16. supported by The column 14 is fixed to the bed 12 but is capable of relative motion along the rails 16 with the feeder 36 . A motor (not shown) for moving the feeder 36 is provided at the rear of the bed 12, and this motor moves the table feeder 36 back and forth along the rail 16 via a ball screw (not shown) or the like. A head 18 is supported on the column 14 so as to be movable (up and down) in the W-axis direction. ) are installed. A head lifting motor (not shown) is provided above the column 14, and the head 18 is lifted/lowered by this motor via a ball screw or the like (not shown). A grindstone shaft rotating motor (motor C of 302 in FIG. 5) is disposed inside or behind the head 18, and the grindstone shaft 20 is rotated by this motor. An encoder constituting measuring means (not shown) is attached to the head lifting motor. Other linear axes and rotary axes, excluding the grindstone axis, are provided with encoders and motors, even if they are not shown, so that the amount of feed or the amount of rotation can be calculated and controlled. The amount of elevation of the head 18 and the amount of cutting into a work (see FIG. 4), which will be described later, are calculated based on the data output from the encoder. A Z-axis is provided parallel to the W-axis direction, and Z-axis motion can be provided without interfering with W-axis head motion, C-axis rotation, and U-axis linear motion.

As previously mentioned, the Y-axis feeder 36 rests on the bed 12 via the rails 16 . The Y-axis feeder 36 is configured so as to be able to linearly move back and forth in the Y-axis direction along the direction of the rail 16 . The table 30 is supported on the Y-axis feeder 36 via rails (not shown). The table 30 is configured to be linearly movable in the horizontal direction (X-axis direction) with respect to the Y-axis feeder 36 . A workpiece (not shown) is detachably installed and fixed on the upper surface thereof. Of course, the bed 12 is provided with a motor for moving the Y-axis feeder 36, and this motor moves the Y-axis feeder 36 along the rail 16 via a ball screw or the like (not shown). there is Similarly, the table 30 is moved on the Y-axis feeder 36 via a motor and ball screws (not shown). Then, while the grindstone shaft 20 is being rotated by the grindstone shaft rotation motor, the head 18 (grindstone shaft 20) is lowered by the head elevation motor, and the grindstone 100 attached to the tip of the grindstone shaft 20 is placed on the table. 30 is brought into contact with the surface of the workpiece. The table 30 is freely movable in the XY directions by the two motors mentioned above. Thereby, the surface of the work is ground by the grindstone 100 . The grinding apparatus 10 is equipped with various operation switches or similar input devices, and is configured so that its state can be changed by the operator's operation during operation. AE (acoustic emission) sensor (not shown) is provided on the work side. When the AE sensor detects the contact between the workpiece and the grindstone 100, it is configured to be displayed to the operator or to stop the feed of the grindstone 100 by a skip signal.

The machine tool (grinding machine) 10 shown in FIG. It has a drive shaft (rotational axis [C-axis] or linear drive shaft) that is axially parallel to the rotational axis 20 . That is, the machine tool (grinding device) 10 has a U-axis feeder 40 below the head 18, and this U-axis feeder 40 linearly feeds the grindstone shaft 20 and the disk body 27 above it. It is a device that linearly moves the grinding wheel shaft 20 and the disk body 27 above it within a predetermined stroke range according to the angular position of the C-axis at that time, and the direction of this linear movement is the U-axis (direction). defined as That is, in the machine tool (grinding machine) 10 shown in FIG. 1, the head 18 can move linearly (up and down) in the Z-axis direction. It is called a W-axis feeder to distinguish it from the Z-axis. In addition, the U-axis feeder 40 can be swiveled relative to the head 18 in Z-axis linear movement and swivel around the Z-axis (referred to as C-axis). The U-axis feed device 40 can linearly move the grindstone shaft 20 in the U-axis direction. Referring to FIGS. 2 and 3, more specifically describing the drive shaft control of the machine tool (grinding machine) 10, in the machine tool (grinding machine) 10, the U-axis linear feed mechanism It's on. The U-axis feed device 40 can be linearly moved along the direction of the U-axis by a feed command for the grindstone shaft (U-axis). The center of the grindstone shaft 20 rotates according to a rotation command for the C-axis. In addition, this C-axis device can be translated vertically with a Z-axis device.

FIG. 5 is a block diagram showing an outline of the control system of the jig grinder shown in FIG. The jig grinder according to the present invention has, as a control system, a control device 300, an input/output device 310, each axis motor 320 and each motor driver 330, a grindstone rotation motor 102A and a grindstone motor inverter 102inv. Controller 300 includes a computer numerical control (CNC) 302 , a programmable controller 304 and an I/O (input/output) module 306 . The control system of the jig grinder according to the present invention also has a keyboard, various switches, a temperature sensor, etc. as an input/output device 310, a tool setter related to a skip signal, an AE sensor, and the like.

Here, the problems of the conventional example will be explained again. In the grinding apparatus (jig grinder) 10 shown in FIGS. 1 to 5, the above-described feeding device is, for example, two-axis, for example, another rotating device (C-axis rotating device) while performing circular interpolation in the (X-Y) plane. is used to orient the automatic cutting device 104 (corresponding to the U-axis feeding device 40, hereinafter the same) in the normal direction, outward or inward, so that the range of feeding of the automatic cutting device 104 can be changed. It is also possible to process larger sizes. In addition, there are many cases in which the speed of circular interpolation can be freely changed by the operator by means of an override switch. However, if the speed of circular interpolation is changed, a deviation may occur depending on the order of the servo system and the presence or absence of feedforward control, and overcutting may occur due to centrifugal force or the like. Also, immediately after the override switch is operated, there is a possibility that the operator may feel that the steering wheel is being cut too sharply, especially during abrupt changes.

Therefore, in the grinding apparatus and its control method of the embodiment of the present invention, when the override switch is operated, it is not directly applied to the control device 300 (see FIG. 5), but the grindstone rotating device 102 is temporarily changed to the automatic cutting device. At 104, a feed override is applied in a direction away from the object to be ground. Alternatively, when the override switch is operated, instead of applying it to the control device 300 (see FIG. 5) as it is, the grindstone rotating device 102 is once fed in the direction away from the grinding object in the linear axis (U-axis) in the radial direction and the override is applied. We decided to prepare a function to automatically perform the operation of gradually returning to the original coordinates. Furthermore, it is preferable to be able to change the escaping direction when grinding the outer side and when grinding the inner side. Furthermore, in order to operate the above-mentioned device, it is automatically determined whether the outer side is being ground or the inner side is being ground by combining the operation of the automatic cutting device 104 immediately before and the type of command for the rotation direction of circular interpolation. You may make it provide the mechanism which carries out. It is preferable to send the operation history of the automatic cutting device 104 in the retroactive direction.

That is, the grinding machine 10 of the embodiment of the present invention has an automatic cutting device 104 capable of radially feeding and fixing a grindstone rotating device 102 with a grindstone 100 attached thereto on a linear axis (U-axis). A grinding machine that can be rotated by a rotating device (C-axis rotating device) 106 together with the grinding wheel rotating device 102 and the automatic cutting device 104. The circle (thickness A grinding device that can grind the inner or outer surface of a cylindrical shape) during this grinding process. 102 can be aligned with the normal direction of the circular arc, and the operator can freely change the feeding speed of the circular interpolation with an override switch. Instead of immediately applying the override command to the control device 300 when the override switch is operated, the automatic cutting device 104 once feeds the grinding wheel rotating device 102 away from the object to be ground by the automatic cutting device 104, and then overrides. is characterized by applying

It also has an automatic cutting device 104 that can radially feed and fix a grinding wheel rotating device 102 with a grinding wheel 100 attached thereto on a linear axis (U-axis). It is a grinding device that can be rotated by a rotating device (C-axis rotating device) 106 together with the device, and can grind the inner surface or outer surface of a circle by circular interpolation using synchronous control of two or more axes. The grinding machine is configured so that the direction in which the automatic infeed device 104 feeds the grindstone rotating device 102 linearly using the rotating device (C-axis rotating device) 106 during processing can be aligned with the normal direction of the arc, In a grinding apparatus configured so that an operator can freely change the feed speed of circular interpolation with an override switch, when the override switch is operated, instead of immediately applying the override command to the control device 300, automatic cutting is performed once. By means of the device 104, the grindstone rotating device 102 is moved radially along the linear axis in the direction away from the object to be ground, and the feed override is applied, and the operation of gradually returning to the original coordinates (target coordinates of CNC control) over time is automatically performed. It is characterized by the provision of functions.

In the grinding apparatus 10, when the outer side of the object to be ground (during processing of the outer peripheral surface, etc.) and the inner side (during processing of the inner peripheral surface, etc.) of the object to be ground are ground, the releasing direction is changed. You can do it. In addition, in the grinding device 10, whether the outer side is ground or the inner side is ground is determined automatically by combining the operation of the automatic cutting device 104 immediately before and the type of command for the rotation direction of circular interpolation. You may make it provide the mechanism which judges. Furthermore, in the grinding apparatus 10, the operation history of the automatic cutting device 104 may be sent in a retroactive direction for relief.

FIG. 6 is a graph showing the relationship among (a) override command, (b) automatic cutting position, and (c) actual rotational speed in the grinding apparatus and control method thereof according to the embodiment of the present invention. In the grinding apparatus and its control method of the embodiment of the present invention, as shown in FIG. 6(a), when the override switch is operated, immediately (control device 300 (See FIG. 5)), but once the automatic cutting position by the automatic cutting device 104 is sent in the radial direction away from the grinding object, and then gradually returned to the original (coordinate) command position. By doing so, as shown in FIG. 6(c), the actual rotation speed also catches up with a corresponding delay.

FIG. 7 is a flow chart of control processing from the start to the end of the machining process in the grinding apparatus of this embodiment. That is, the machining process is started in the grinding apparatus of the present embodiment (S701), it is checked whether an override switch is operated during machining and an override change occurs (S702), and it is determined whether or not a speed change occurs ( S703). If the speed change occurs (YES in S703), the relief addition amount for the relief amount remaining at that time is calculated (S704), the relief direction is determined (S705), the relief addition operation is executed (S706), The speed is changed (S707). Cutting is performed at this changed speed, and it is determined whether the rotation of the C-axis has ended (S708). If the rotation of the C-axis has ended (YES in S708), the machining process ends ( S709). On the other hand, if the rotation of the C-axis has not ended (NO in S708), the process returns to S702. If it is determined in S703 that there is no speed change (NO in S703), the escape damping operation is executed (S710), and the process proceeds to S708.

FIG. 8(a) shows the main flow of control processing from the start to the end of the machining process shown in FIG. is automatically determined by combining the operation of the previous automatic cutting device 104 and the type of command for the rotation direction of circular interpolation. is a diagram showing a control process for sending in a backward direction. The main flow of FIG. 8(a) is as described with reference to FIG. In the grinding machine of this embodiment, in order to determine the relief direction in S705 of FIG. 7, an automatic cutting record is further created as shown in FIG. 8(b). That is, when an automatic cutting command is started (S801), every time an automatic cutting direction command is generated (S802), the cutting direction is recorded (S803), and this cutting direction is recorded (history ) to determine the escape direction in S705 of FIG. Then, when the automatic cutting operation is executed (S804), the automatic cutting command ends (S805). In order to determine the release direction, the NC modal information is also referred to as shown in FIG. 8(c). That is, in S806, as mode information, the direction of the arc/straight line/normal direction (right/left of the route?) is referred to, and in the judgment of the escape direction, the direction to return the last automatic cut is mainly determined. refer. If the previous action was to move to the start position, treat the correction amount as 0. If the direction is unknown due to the progress of the process, check the mode of normal direction control and circular interpolation, for example, U negative direction when G41.1 and G02, U positive direction when G42.1 and G02, G41 .1 and G03 use U positive direction, G42.1 and G03 U negative direction, etc. Use presets per machining.

It should be noted that the overcut amount (radius change Δr) according to the change in rotational speed is generally defined by the following formula (1).

In a typical machine tool servo control system, the radius decrease ΔR during constant speed rotation with an arc command is as follows if the response of the speed control unit and current control unit is sufficiently fast and the acceleration/deceleration after interpolation is sufficiently fast. is approximated by Equation (2).

In general, a circular interpolation control system as shown in FIG. 9 is used.

10 jig grinder (grinding device), 100 grindstone, 102 grindstone rotating device, 104 automatic cutting device, 106 another rotating device (C-axis rotating device), 300 control device, W work,

Claims (5)

It has an automatic cutting device that can radially feed and fix a grinding wheel rotating device with a grinding wheel on a linear axis, and the device including the grinding wheel rotating device and the automatic cutting device can be rotated by a separate rotating device. A grinding machine capable of grinding the inner surface or the outer surface of a circle by circular interpolation using synchronous control of two or more axes, wherein during this grinding process, the automatic A grinding device in which the direction in which the cutting device feeds the grinding wheel rotating device in a straight line can be aligned with the normal direction of the arc, and the operator can freely change the feeding speed of circular interpolation with an override switch. In the grinding apparatus configured as above, when the override switch is operated, the override command is not immediately applied to the control device, but the automatic cutting device temporarily moves the grinding wheel rotating device from the grinding object by the automatic cutting device. Grinding device characterized by feeding in a far direction and then applying an override. It has an automatic cutting device that can radially feed and fix a grinding wheel rotating device with a grinding wheel on a linear axis, and the device including the grinding wheel rotating device and the automatic cutting device can be rotated by a separate rotating device. A grinding device capable of grinding the inner surface or outer surface of a circle by circular interpolation using synchronous control of two or more axes, and during this grinding process, the automatic cutting using the separate rotating device A grinding apparatus configured so that the direction in which the apparatus feeds the grindstone rotating device in a straight line can be aligned with the normal direction of the arc, and the operator can freely change the feed speed of circular interpolation with an override switch. When the override switch is operated, instead of immediately applying the override command to the control device, the automatic infeed device temporarily moves the grinding wheel rotating device along the linear axis in the radial direction away from the object to be ground. A grinding apparatus characterized by having a function of automatically performing an operation of sending in a distant direction, then applying an override, and gradually returning to the original coordinates over time. 3. The grinding apparatus according to claim 1, wherein the grinding apparatus is further configured such that the releasing direction can be changed between when grinding the outer side and when grinding the inner side. 4. The grinding apparatus according to claim 1, further comprising: determining whether the outer side or the inner side is being ground; A grinding apparatus characterized by comprising a mechanism for automatically judging a crowded state. 5. A grinding apparatus according to claim 1, wherein the relief feeds the operation history of said automatic cutting device in a retroactive direction.

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