JP7143025B2 - Grinding device and its control method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grinding apparatus and its control method, and more particularly to a jig grinder equipped with a mechanism for reciprocating a grindstone in the axial direction at high speed, such as chopping operation, and its control method.

In general, a grinding apparatus such as a jig grinder is equipped with a mechanism for reciprocating a grindstone in the axial direction at high speed, such as chopping operation, and can perform grinding. In terms of chopping, either the grinding wheel shaft is not eccentric, or the grinding wheel is eccentric in the opposite direction (negative direction) to the cutting described above by an amount corresponding to the radius of the grinding wheel so that the center of rotation of the spindle and the outer circumference of the grinding wheel are aligned. First, the movement of the workpiece to the machining position (grinding point) is performed by X- and Y-axis feeding. After that, the grindstone is automatically decentered by the amount of net cutting, that is, chopping is performed while automatic cutting is performed. At this time, the angle of the spindle is controlled (indexed) so that the normal line at the machining point with which the workpiece abuts always coincides with the cutting direction of the grindstone when the grindstone cuts into the machining surface of the workpiece whose curvature is not constant. Patent Documents 1 to 3 disclose the main configuration of such jig grinders. However, Patent Literature 3 omits the configuration for moving the whetstone up and down.

JP-A-62-140763 JP-A-9-155676 JP 2006-102891 A

Position feedback is also performed when performing such chopping operation, but the position sensor (linear scale, etc.) used for feedback has a certain amount of size and mass attached to the tip. This can lead to overshoot. Ordinary, less demanding wheels have a set direction in which they can be used for grinding, so a wheel that grinds the side cannot grind the surface that is ahead of the reciprocation, and it is generally possible that it will burst. potential and dangerous. However, since unshaving is also disliked, the reciprocating range of the grindstone is often set so as to come close to the surface at the end of the reciprocating motion. Further, conventionally, since the reciprocating range is generally set while stopped (without chopping operation), there is a possibility that contact may occur during actual chopping operation.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a technology capable of appropriately setting the reciprocating range of a grindstone when performing a reciprocating motion such as a chopping motion in a grinding apparatus and its control method.

The inventor of the present invention provides a grinding apparatus and a control method thereof, firstly, a head, a position detector provided on the head, a grindstone shaft rotatably extending from the head, and a tip end side of the grindstone shaft. A grindstone mounted via a grindstone arbor and a mechanism for reciprocating the grindstone at a predetermined speed while rotating the grindstone are provided, and the work is ground by rotating the grindstone while reciprocating the grindstone by the mechanism . In a grinding apparatus that performs a first control of a grinding position of a workpiece by a grindstone using a signal from the position detector, the predetermined and the amount of overshoot with respect to the range of the reciprocating motion is investigated, and the machine coordinates are adjusted so that the range of the reciprocating motion is narrowed by the amount of overshoot only from the tip side of the grindstone arbor according to the predetermined speed. By performing the second shift control, secondly, a head, a position detector provided on the head, a grindstone shaft rotatably extending from the head, and a grindstone arbor on the tip side of the grindstone shaft. and a mechanism for reciprocating the grindstone at a predetermined speed while rotating the grindstone . In the grinding apparatus for performing the first control of the grinding position of the workpiece by the grindstone using the signal from the position detector, the predetermined speed and the The relationship between the range of reciprocating motion and the amount of overshoot is examined, and second control is performed to shift the entire range of reciprocating motion toward the base end side of the grindstone arbor by the amount of overshoot in accordance with the predetermined speed. Thirdly, the second control amount for shifting is defined by using a function in addition to the arguments of the coordinates of the axes other than the grinding wheel axis and the state relationship of the speed, so that the reciprocating motion such as chopping can be performed. It was found that the reciprocating range of the grindstone can be appropriately set when performing.

That is, according to the first aspect of the present invention, there is provided a head, a position detector provided on the head, a grindstone shaft rotatably extending from the head, and a grindstone arbor on the tip side of the grindstone shaft. and a mechanism for reciprocating the grindstone at a predetermined speed while rotating the grindstone . In a grinding apparatus that performs a first control of a grinding position of a workpiece by a grindstone using a signal from the position detector, the predetermined velocity and the A second method in which the relationship between the range of reciprocating motion and the amount of overshoot is investigated, and the machine coordinates are shifted so as to narrow the range of reciprocating motion only from the tip side of the grinding stone arbor by the amount of overshoot in accordance with the predetermined speed. It is characterized by performing control.

Further, according to a second aspect of the present invention, there is provided a head, a position detector provided on the head, a grindstone shaft rotatably extending from the head, and a grindstone arbor on the tip side of the grindstone shaft. and a mechanism for reciprocating the grindstone at a predetermined speed while rotating the grindstone . In a grinding apparatus that performs a first control of a grinding position of a workpiece by a grindstone using a signal from the position detector, the predetermined velocity and the A relationship between the range of reciprocating motion and the amount of overshoot is examined, and second control is performed to shift the entire range of reciprocating motion toward the base end side of the grindstone arbor by the amount of overshoot in accordance with the predetermined speed. It is characterized by

Furthermore, according to a third aspect of the present invention, the second control amount for shifting is defined by using a function in addition to the arguments of the coordinates of axes other than the grinding wheel axis and the state relationship of speed. do.

ADVANTAGE OF THE INVENTION According to this invention, in a grinding apparatus and its control method, when performing reciprocating motions, such as a chopping motion, the reciprocating range of a grindstone can be set appropriately.

1 is a perspective view showing a jig grinder as an example of a grinding apparatus to which the present invention is applied; FIG. 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 block diagram showing an outline of a control system of the grinding device (jig grinding machine) shown in FIG. 1; FIG. FIG. 2 is a first diagram for explaining problems of a conventional example; FIG. 10 is a second diagram for explaining problems of the conventional example; FIG. 3 is a third diagram for explaining problems of the conventional example; FIG. 4 is a fourth diagram for explaining problems of the conventional example; FIG. 11 is a fifth diagram for explaining problems of the conventional example; It is a figure for explaining the main composition of the 1st and 2nd embodiments of the present invention. 4 is a flow chart of processing for setting the reciprocating range of the grindstone in the first embodiment of the present invention. 9 is a flow chart of processing for setting the reciprocating range of the grindstone in the second embodiment of the present invention. FIG. 10 is a flow chart of processing for setting the reciprocating range of the grindstone in the third embodiment of the present invention. FIG. FIG. 11 is a flow chart of processing for setting a reciprocating range of a grindstone in a modified example of the third embodiment of the present invention; FIG. It is a functional block diagram which sets the reciprocation range of the grindstone in the 2nd Embodiment of this invention. It is a functional block diagram which sets the reciprocating range of the grindstone in the modification of the 2nd Embodiment of this invention.

FIG. 1 is a perspective view showing an example of a grinding device to which the present invention is applied, and FIG. 2 is an enlarged view of the U-axis feeding device and the periphery of the grindstone shaft. As shown in FIG. 1, a grinding apparatus 10 to which the present invention is applied has a table feeding device 36 and a table 30 supported on a bed 12 via rails 16 so as to be movable in the Y-axis direction (back and forth direction). . The column 14 is fixed to the bed 12, but is capable of relative movement along the rails 16 with the feeder 36, as described above. 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 (for rotation) motor 24 (see FIG. 2) is disposed at the rear of the head 18, and the grindstone shaft 20 is rotated by this motor. The head lifting motor is provided with an encoder constituting measuring means (not shown). 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 (not shown) are calculated based on the data output from this 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 mentioned above, the X-axis feeder 36 rests on the bed 12 via the rails 16 . The X-axis feeder 36 is configured to move linearly back and forth in the Y direction along the direction of the rail 16 . The table 30 is supported on the X-axis feeder 36 via rails (not shown). The table 30 is configured to be linearly movable in the horizontal direction with respect to the X-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 X-axis feeder 36, and this motor moves the X-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 X-axis feeder 36 via a motor, ball screw and the like (not shown). Then, while the grindstone shaft 20 is being rotated by the grindstone shaft rotation motor 24, the head 18 (grindstone shaft 20) is lowered by the head lifting motor, and the grindstone 100 attached to the tip of the grindstone shaft 20 is moved. It is brought into contact with the surface of the work on the table 30 . 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 has an AE (acoustic emission) sensor (not shown) on the work side as contact detection means between the grindstone 100 and the work. When the AE sensor detects the contact between the workpiece and the grindstone 100, the skip signal is used to stop the feed of the grindstone 100. FIG.

The machine tool (grinding machine) 10 shown in FIG. 20 has a drive shaft (rotary shaft or linear drive shaft) axially parallel to the rotary shaft. 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). It rotates together with the center of the grindstone shaft according to the rotation command of the C-axis. In addition, this C-axis device can be translated vertically with a Z-axis device.

FIG. 3 is a block diagram showing an outline of the control system of the jig grinder shown in FIG. The jig grinder according to this embodiment 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 this embodiment also has a keyboard, various switches, a temperature sensor, etc., a tool setter related to a skip signal, an AE sensor, etc. as the input/output device 310 .

Here, with reference to FIGS. 4 to 8, the problems of the conventional example will be described in an easy-to-understand manner. For example, a jig grinder grinds a workpiece while performing chopping operations. FIG. 4 shows the grindstone arbor 42 and the grindstone 100 attached to its tip. That is, as shown in FIG. 4, the side surface 100a of the whetstone 100 is formed as a grindable surface, while the bottom surface 100b is formed as a non-grindable surface. In this way, the direction in which the grindstone 100 can be used for grinding is determined such that only the side surface 100a side (direction) of the grindstone 100 can be used. Therefore, as shown in FIG. The whetstone 100 cannot grind the surface Wb ahead of the reciprocating motion, and generally there is a possibility of an explosion or the like, which is dangerous. However, since uncut parts are also disliked, the reciprocating range R of the grindstone 100 is often set so as to come close to the surface Wb at the destination of the reciprocating motion. Therefore, as shown in FIG. 5, when cutting a workpiece W having a shape as shown, an upper limit U and a lower limit L of the reciprocating range R of the chopping motion in the Z-axis direction are set. A void (uncut portion) S is generated on the bottom surface 100b side.

Therefore, as shown in FIG. 6, for example, if the uncut corners become an obstacle when assembling parts machined from the workpiece, a grinding relief E may be provided to relieve the corners during preliminary machining. However, for example, as shown in FIG. 7, Z-axis control is performed using signals from a position detector (not shown) in the upper part of head 18, so that changes in length of the object beyond it are not taken into account. Therefore, as shown in FIG. 8, when the reciprocating speed increases, the lower limit L and the upper limit U of the reciprocating range R of the chopping operation slightly move downward and upward due to inertia.

Therefore, as a grinding apparatus and its control method that can solve the above problems and can appropriately set the reciprocating range of the grindstone when performing the chopping operation, first to third methods will be described with reference to FIGS. 9 to 14. An embodiment of is described. That is, as shown in FIG. 9, in the first embodiment, a non-contact displacement gauge is used in advance to examine the relationship between the chopping reciprocating speed and the amount of overshoot. Evaluate range differences. Then, according to the chopping speed, only the limit (setting) of approaching the surface Wb of the workpiece W is shifted inward, that is, the machine coordinates are shifted so that the chopping range is separated from the previous surface. As a result, the reciprocating range of the grindstone can be appropriately set when the chopping operation is performed.

Further, as shown in FIG. 9, in the second embodiment, a non-contact displacement gauge is used in advance to examine the relationship between the chopping reciprocating speed and the amount of overshoot. Evaluate range differences. Then, the entire reciprocating range of the Z-axis is shifted in the opposite direction from the side approaching the surface Wb of the workpiece W according to the chopping speed. That is, control is performed to shift the end of the chopping range from the direction in which the surface lies ahead of the chopping. As a result, the reciprocating range of the grindstone can be appropriately set when the chopping operation is performed.

Furthermore, in the third embodiment, the above two control amounts are defined using functions in addition to the arguments of the coordinates of the other axes and the state relationship of the speed, so that the reciprocating range of the grindstone when performing the chopping operation is defined as can be set properly.

That is, in estimating the amount of overshoot in the first and second embodiments, the relationship between the speed Z and the amount of overshoot ε is expressed by univariate polynomial approximation. That is, the relationship between the speed Z and the amount of overshoot ε is defined by the following formula (1).

数式（２）において、ａiは、定数であり、使わない項に対する係数として０の値をとる場合もあり得る。 For example, it is represented by the univariate polynomial approximation of the following formula (2).

In equation (2), ai is a constant and may take the value of 0 as a coefficient for unused terms.

If the need for computer calculations is not desirable due to the load on the control device, etc., the relationship between the speed and the overshoot amount may be expressed as shown in Table 1 below for estimation.

上記の数式（３）で、下記の数（４）をそれぞれ下記の数（５）と置き換えて、下記の数式（６）が得られる。

上記の数式（６）で、下線部は定数であり、使わない項に対する係数として０の値をとる場合もあり得る。 Strictly speaking, in the third embodiment, the overshoot amount changes according to the positions and velocities of Z, U, W, and C. Therefore, the coordinates and velocities of Z, U, W, and C and the overshoot amount ε By expressing the relationship by multivariable polynomial approximation as in the following formula (3), the control of the above-described first or second embodiment is performed.

In the above equation (3), the following equation (6) is obtained by replacing each of the following equations (4) with the following equations (5).

In the above equation (6), the underlined parts are constants, and the coefficients for unused terms may take the value of 0 in some cases.

上記の数式（７）で、下記の数（８）をそれぞれ下記の数（９）と置き換えて、下記の数式（１０）が得られるので、この数式（１０）のように定義して行き過ぎ量を推定する。

上記の数式（１０）で、下線部、即ち、数（１１）は、それぞれの項の係数（定数）であり、使わない項に対する係数として０の値をとる場合もあり得る。

一方、数（１２）は、Ｗ,Ｃ, Ｕ軸が無い研削装置の場合には、０の値として扱うようにする。

Here, in the above third embodiment, the Z direction is only an example. That is, the present invention can also be applied when the direction of reciprocating motion is set by a combination of X, Y, and Z. That is, in the modification of the third embodiment, the reciprocating direction is not necessarily the Z direction, but the reciprocating direction of the grinding wheel can be freely selected according to the object to be processed by synchronous control of X, Y, and Z. ), the relationship between the coordinates of X, Y, Z, U, W, and C, the velocity, and the amount of overshoot ε is represented by multivariable polynomial approximation as shown in the following equation (7). Alternatively, the control of the second embodiment is performed.

In the above formula (7), the following formula (8) is replaced with the following formula (9) to obtain the following formula (10). to estimate

In the above equation (10), the underlined parts, ie, number (11), are the coefficients (constants) of the respective terms, and the coefficients for unused terms may take the value of 0 in some cases.

On the other hand, the number (12) is treated as a value of 0 in the case of a grinding machine without W, C and U axes.

FIG. 10 is a flowchart of processing for setting the reciprocating range of the grindstone in the first embodiment of the present invention. When the process starts (S101), the reciprocating speed is acquired (S102), it is determined whether or not there is a change in speed (S103), and if there is a change in speed (YES in S103), the amount of overshoot is calculated. (S104). Restriction processing of the reciprocating range is performed in consideration of the amount of overshoot (S105). Then, monitoring is continued until the reciprocating motion is completed (S106), and when the reciprocating motion is completed (YES in S106), the process is terminated (S107). If the reciprocating motion has not ended (NO in S106), the process returns to S102 for acquiring the reciprocating speed.

FIG. 11 is a flow chart of processing for setting the reciprocating range of the grindstone in the second embodiment of the present invention. When the process starts (S111), the reciprocating speed is obtained (S112), it is determined whether or not there is a change in speed (S113), and if there is a change in speed (YES in S113), the amount of overshoot is calculated. (S114). Moving processing of the reciprocating range is performed in consideration of the amount of overshoot (S115). Then, monitoring is continued until the reciprocating motion ends (S116), and when the reciprocating motion ends (YES in S116), the process ends (S117). If the reciprocating motion has not ended (NO in S116), the process returns to S112 for acquiring the reciprocating speed.

FIG. 12 is a flow chart of processing for setting the reciprocating range of the grindstone in the third embodiment of the present invention. When the process is started (S121), the above number (4) is acquired (S122) and the overshoot amount is estimated (S123). It is determined whether or not there is a change in the estimated amount of overshoot (S124), and if there is a change in the estimated amount of overshoot (YES in S124), processing for moving the reciprocating range is performed in consideration of this change (S125). Then, monitoring is continued until the reciprocating motion is completed (S126), and when the reciprocating motion is completed (YES in S126), the process is terminated (S127). If the reciprocating motion has not ended (NO in S126), the process returns to S122 for acquiring the above number (4).

FIG. 13 is a flowchart of processing for setting the reciprocating range of the grindstone in the modification of the third embodiment of the present invention. When the process is started (S131), the above number (8) is acquired (S132) and the overshoot amount is estimated (S133). It is determined whether or not there is a change in the estimated amount of overshoot (S134), and if there is a change in the estimated amount of overshoot (YES in S134), processing for moving the reciprocating range is performed in consideration of this change (S135). Then, monitoring is continued until the reciprocating motion is completed (S136), and when the reciprocating motion is completed (YES in S136), the process is terminated (S137). If the reciprocating motion has not ended (NO in S136), the process returns to S132 for acquiring the above number (8).

FIG. 14 is a functional block diagram for setting the reciprocating range of the grindstone in the first and second embodiments of the present invention. That is, a reciprocating speed range adjustment function (core part of the present invention) 131 sets a range 132, and a reciprocating control function (chopping/oscillation function) 133 is activated within the set range. This reciprocating control function (chopping/oscillation function) 133 performs control/superimposition 134, and axis control function 135 is activated. When the axis control function 135 feeds back the coordinate information/speed information 136, the range adjustment function (core part of the present invention) 131 based on the reciprocating speed uses the obtained coordinate information/speed information 136 for range adjustment. All of these function groups may be provided in the software of the CNC 302, or some functions may be provided in a peripheral device such as the programmable controller 304 or the like.

FIG. 15 is a functional block diagram for setting the reciprocating range of the grindstone in the modified example of the second embodiment of the present invention. That is, the reciprocating speed range adjustment function (the core part of the present invention) 141 performs a superposition function 147 to superimpose 148 on the control value of the axis control function 145 . A reciprocating control function (chopping/oscillation function) 143 performs control/superimposition 144, and an axis control function 145 is activated. The axis control function 145 feeds back the coordinate information/speed information 146 so that the range adjustment function (core part of the present invention) 141 based on the reciprocating speed uses the obtained coordinate information/speed information 146 for the superimposition function 147. . All of these function groups may be provided in the software of the CNC 302, or some functions may be provided in a peripheral device such as the programmable controller 304 or the like. As described above, in the modification of the second embodiment of the present invention, the range setting of the reciprocating control function (chopping/oscillation function) 143 is not used, but superimposed 148 on the control numerical value of the axis control function 145. can be

ADVANTAGE OF THE INVENTION According to this invention, in a grinding apparatus and its control method, when performing reciprocating motion operation|movements, such as chopping, the reciprocating range of a grindstone can be set appropriately.

In the above-described first to third embodiments, chopping processing or oscillation processing was exemplified as an example of the reciprocating motion of the grindstone, but it is not limited to these, and other within the scope described in the claims. It is also applicable to setting the range of reciprocating motion.

10 jig grinder, 100 whetstone, W work,

Claims (3)

a head, a position detector provided on the head, a grindstone shaft rotatably extending from the head, a grindstone attached to the tip side of the grindstone shaft via a grindstone arbor, and rotating the grindstone. A grinding apparatus comprising a mechanism for reciprocating at a predetermined speed , wherein the mechanism reciprocates the grindstone while rotating the grindstone to grind a workpiece , wherein the grindstone uses a signal from the position detector. In the grinding apparatus for performing the first control of the grinding position of the workpiece, the relationship between the predetermined speed and the range of reciprocating motion is investigated in advance using a non-contact displacement gauge as an external sensor. 2. A grinding apparatus characterized by performing a second control for shifting the machine coordinates so as to narrow the range of said reciprocating motion only from the front end side of said grinding wheel arbor by said overshoot amount in accordance with said predetermined speed. a head, a position detector provided on the head, a grindstone shaft rotatably extending from the head, a grindstone attached to the tip side of the grindstone shaft via a grindstone arbor, and rotating the grindstone. A grinding apparatus comprising a mechanism for reciprocating at a predetermined speed , wherein the mechanism reciprocates the grindstone while rotating the grindstone to grind a workpiece , wherein the grindstone uses a signal from the position detector. In the grinding apparatus for performing the first control of the grinding position of the workpiece, the relationship between the predetermined speed and the range of reciprocating motion is investigated in advance using a non-contact displacement gauge as an external sensor. a second control for shifting the entire range of the reciprocating motion toward the base end of the grindstone arbor by the amount of overshoot in accordance with the predetermined speed; 3. The method of controlling a grinding apparatus according to claim 1, wherein the second control amount for shifting is defined by using a function in addition to arguments of a state relationship of coordinates and speed of an axis other than the grinding wheel axis .

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