JP2021502267A - How to machine a glass plate - Google Patents

Abstract

A method of machining a glass plate (1'), the edge of the glass plate (1a') is machined using at least one grinding tool (10) and by a glass plate and a motor (11). The grinding tools set to rotate are moved relative to each other, and the method is at least the edge where the variable, which is a function of the power consumption of the motor (11) used to drive the grinding tool, is machined. Along part of the portion (1a'), it is detected and evaluated to determine the offset of the glass plate (1') with respect to the target position (1).

Description

The present invention relates to a method of machining a glass plate, the edge of the glass plate is machined using at least one grinding tool, and the glass plate and the grinding tool are moved relative to each other.

Such a method is known, for example, from Patent Document 1 by the applicant. In the manufacture of glass plates with a given shape, grinding the edges is used to obtain the exact desired final dimensions and / or to give the edges the desired profile (such as corners or roundness). .. Correspondingly accurate information is needed with respect to the position of the glass plate or its edges relative to the position of the grinding tool to allow accurate grinding so that the edges are machined uniformly. For example, if the device is used to grind the shape of a new glass plate, this information may be too inaccurate and needs to be reconfigured. In addition, the length of the device may change due to temperature fluctuations after the configuration, and the glass plate may not be accurately placed at the position assumed by the device during machining.

Patent Document 2 describes a method in which the parallel longitudinal side surfaces of a glass plate are ground by two grinding wheels. The current flowing through the drive motor is displayed on the display device in two waveforms. Since the position information of the glass plate is not accurate, there is no means to correct the above-mentioned inaccurate processing problem.

European Patent Application Publication No. 0 255 476 JP-A-2007-136632

An object of the present invention is to provide a method that enables accurate machining of the edges of a glass plate.

A method of achieving this object is defined in claim 1. Further claims describe preferred embodiments of methods, devices capable of performing the methods, computer programs, and data carriers.

The offset of the glass plate with respect to the target position, i.e. the desired position, can be determined by detecting and evaluating a variable that is a function of the power consumption of the motor used to drive the grinding tool. This allows the possible offsets and accurate grinding of the glass plate to be corrected. For example, the current of the motor can be used as such a variable. In addition, the configuration of the device for processing new glass plate shapes is simplified and continuous production can be monitored to ensure that the grinding edges are of the desired quality.

The method according to the invention allows accurate machining of any shape of a glass plate having any shape, i.e. a contour composed of straight and / or curved portions, as well as a rectangular shape.

The machined glass plate is placed on the support, for example, to define the actual position. The actual position may deviate from the target position due to the offset. The offset can be regarded as the displacement of the plane P defined on the back side of the glass plate. The displacement can be linear and / or rotational displacement. During machining, the glass plate and at least one grinding tool can move relative to each other in plane P.

The glass plate offset can be defined by one or more of the following parameters:
・ Deviation along the first linear axis ・ Deviation along the second linear axis ・ Rotation around the rotation axis.
Preferably, at least one of the following conditions is met:
The first linear axis extends in the plane P.
The second linear axis extends in the plane P.
The first and second linear axes are arranged at an angle to each other, preferably they are arranged laterally to each other, and most preferably they are perpendicular to each other.
-The axis of rotation extends perpendicular to the plane P.

Preferably, at least one of the above three parameters (movement along a first / second linear axis, rotation around a rotation axis) is a function of the power consumption of the motor used to drive the grinding tool. Determined by the method of detecting and evaluating variables. It is not necessary to determine all the above parameters in order to improve the machining accuracy of the glass plate. This can be the case, for example, when one or more parameters are less dominant than the other parameters. For example, the rotation between the actual position and the target position is negligible and / or the deviation between the actual position and the target position is greater along one particular axis than along the other. Tend.

Preferably, the offset is determined in units of length and / or angle. This can be achieved, for example, by calibration measurements.

Preferably, the offset is determined by a calculation performed by the controller. The controller may be provided with a program configured to calculate the offset. Calculations include fitting the mathematical model to the detected curve values of the variable, averaging at least some of the detected values of the variable, and taking into account the values obtained from calibration measurements. included.

Preferably, the determined offset is taken into account in subsequent machining cycles. In such subsequent cycles, the same glass plate may be machined at least once again, and / or another glass plate may be machined.

Preferably, based on the determined offset, a correction is determined to adjust the actual position of the glass plate to the target position. This correction may be taken into account in subsequent machining cycles.

Preferably, the complete perimeter of the glass plate is machined using one or more grinding tools.

The present invention will be described below based on exemplary embodiments with reference to the drawings showing:

A device for machining a glass plate is shown schematically. An exemplary embodiment of an apparatus for machining a glass plate is shown in perspective view. An example of the value of the current required by the motor to drive the grinding tool is shown as a function of the position of the grinding tool along the edge of the glass plate. The grinding speed corresponding to the curve of FIG. 3 and its differential coefficient are shown. An example of a weighting function of a rectangular glass plate shape in the x direction (FIG. 5 (a)), the y direction (FIG. 5 (b)), and the rotation direction (FIG. 5 (c)) is shown. An example of the current value in the x direction (FIG. 6 (a)), the y direction (FIG. 6 (b)), and the rotation direction (FIG. 6 (c)) to which the weighting function of FIG. 5 is applied is shown. The method sequence for constructing the apparatus for continuous production is shown schematically.

FIG. 1 schematically shows a device used for machining the edges of a glass plate. (The edge is the outer peripheral area between the top and bottom surfaces of the glass plate.) The device is set to a rotating state by a support 9, an electric motor, eg, a spindle motor, on which the glass plate is placed during machining. The grinding tool 10 and the controller 15 which can be used are included. As the electric motor, for example, an asynchronous motor or a synchronous motor is suitable. The grinding tool 10 is designed, for example, as a one-part or multi-part grinding disc.

The support 9 and the grinding tool 10 are movable relative to each other so that the edges of the glass plate are ground. This can be achieved in a variety of ways, for example:
The support 9 is stationary, and the grinding tool 10 can move around the edge of the glass plate.
The grinding tool 10 is stationary, and the support 9 is movable so that the edge of the glass plate can move through the grinding tool.
The support 9 and the grinding tool 10 are movable, for example, the support 9 is rotatable around the center of rotation, the grinding tool 10 is movable back and forth along a linear axis, or the support 9 is movable. Movable back and forth along a linear axis, the grinding tool 10 is movable back and forth along a second linear axis, and the two axes are arranged, for example, at right angles and laterally to each other. Axle.

Corresponding appropriate drives and optionally guides are provided to move the support 9 and / or the grinding tool 10. The grinding tool 10 is sent by a drive device, for example, a path control device. Then, the grinding tool 10 follows a fixed predetermined path. It is also conceivable to feed the grinding tool in other ways, for example by force control or path control and force control.

As an example, FIG. 2 shows a rotary table 8 that is rotatable around the center of rotation, as indicated by the double arrow 8a, and is movable back and forth along a linear axis as indicated by the double arrow 10a. An apparatus having a grinding tool 10 is shown. The turntable 8 includes a support 9 in the form of one or more suction units on which the glass plate is placed during machining, whereby the glass plate is firmly held. FIG. 2 also shows a controller 15 and an electric motor 11 for driving the grinding tool 10. The grinding tool, along with the electric motor 11, is arranged on the carriage 12 that can move along the track 13 as a guide.

Returning to FIG. 1, the glass plate 1'at the actual position is also shown. During the configuration of the device for machining a new glass plate shape, the controller 15 has information about the desired shape of the glass plate 1', but does not necessarily know the exact position of the glass plate. The glass plate 1 of FIG. 1 represents the target position, based on which the controller 15 determines the movement of the support 9 and / or the grinding tool 10, whereby the glass plate edge 1a grinds at the target position. Will be done. From FIG. 1, it can be seen that the actual position and the target position are offset. The offset may be due to displacement in the plane and / or rotation in the plane. In FIG. 1, for example, the x-axis and the y-axis define a coordinate system in which the glass plate edge portion 1a at the target position is specified, and the x'axis and the y'axis are the glass plate edge portion 1a'at the actual position. Defines the coordinate system in which is specified. The x'-y'coordinate system is displaced by a vector a and rotated by an angle α with respect to the xy coordinate system.

In the ideal case, that is, if the actual position and the target position are the same, the power consumption of the electric motor 11 while driving the grinding tool 10 is defined by predefined process parameters such as glass plate shape, grinding speed, feed. Is a function of only. For example, power consumption is essentially constant while grinding along an essentially straight path. The inventor has found that offsets result in corresponding fluctuations in power consumption. By detecting and evaluating the variables corresponding to the power consumption, it is possible to draw conclusions about the offset. For example, as a variable that reflects the power consumption, the current required by the electric motor 11 to drive the grinding tool 10 may be used. The controller 15 is used to control the movement of the support 9 and / or the grinding tool 10, and the electric motor 11. The controller 15 is provided with an appropriate program for evaluating the detected variables. During operation, the current value of the electric motor 11 and / or some other variables are detected as a function of power consumption for a particular position of the support 9 and / or the grinding tool 10. In the modified example of FIG. 2, in addition to the current, for example, the rotational position (in degrees) of the rotary table 8, the position on the linear axis of the grinding tool 10, and other parameters, such as selectively, for example, force-controlled feed. -Is recorded.

In the following description, as an example, current is used as the detected variable. It is conceivable to use some other electrical variable, such as voltage or a combination of current and voltage.

An example of the detected current curve I is shown in FIG. The vertical axis represents the current in ampere units, for example, and the value on the horizontal axis corresponds to the position on the circumference of the glass plate 1a. During operation, the current value is repeatedly detected when the position is displaced. As a result, N measured values can be obtained. (In the example of FIG. 3, this corresponds to about 450 measurements. Of course, N can be different.)

The measurements are processed in the first step to evaluate the current curve I. As is clear from FIG. 3, a drop in current may occur. In this case, the drop in current at the beginning and end of the measurement is caused by the path plan of the grinding operation. The measurement begins by recording the value towards or while the grinding tool 10 is towards or away from the glass plate 1'. For the start and end points of the actual grinding operation, for example, the first N1 measurement value and the last N2 measurement value (for example, N1 = N2 = 50 or other values) are acquired, and the support 9 and the grinding tool 10 are used. It can be determined by determining the corresponding x and y coordinates based on the position values and comparing them with each other. The specified start and end points of the measurement are between the two values with the smallest spacing. All previous and next measurements are not used in the next step to determine the offset. However, the value of the current required by the grinding tool 10 in idle mode, i.e. not in contact with the glass plate 1', can be determined from the omitted measurements.

Between the first and last current drops, the four additional current drops shown in FIG. 3 result from the selected shape of the glass plate 1'. In this case, the glass plate has the shape shown in FIG. 1, that is, it has four rounded corners defined by the external radius. At the angle, the direction in which the edge extends as seen in the top view of the glass plate 1'changes beyond a predetermined angle value, for example, by exceeding 45 degrees. When the grinding tool 10 is grinding in any of the cases during such a change of direction, since the support surface is small, the glass is hardly removed and the current is significantly reduced. In contrast, the calculated grinding rate acts complementarily during the specified change of direction as the difference between the two position values during the defined period. That is, it increases significantly during the drop in current. In FIG. 4, the grinding speed v corresponding to the current curve I in FIG. 3 is shown in units of length per unit time (in this case, millimeters per 20 milliseconds). The lower curve of FIG. 4 shows the differential coefficient v'of the grinding speed v.

The program uses, for example, the ratio of spindle current I to grinding speed v to eliminate the aforementioned current drop. As is clear from FIG. 4, the derivative v'at the position of the specified change in direction has positive and negative outliers. Measured values of current where the value of the derivative v'exceeds a predefined limit (eg ± 0.25 in the example of FIG. 4) are declared as a drop in current and omitted for further evaluation. Or adjusted, for example, by setting the average value of the detected currents.

The offset can be determined after the current measurements have been processed. As described above with respect to FIG. 1, the offset is defined by three parameters, two parameters of linear displacement in the plane (eg, the values of x and y of the displacement vector a) and one parameter of rotation α in the plane. be able to. Various methods are conceivable for determining the offset from multiple current measurements. For example, fitting a mathematical model to a measurement curve, iterating, and so on.

In the case of the device according to FIG. 2, for example, the following procedure can be considered: As a result of geometry, the greater the distance of a point from the center of rotation of the turntable 8, the farther this point moves. The course of the glass plate edge portion 1a at the target position can be defined by the values of the x-coordinate and the y-coordinate. Based on these values, the derivative is created and normalized to ± 1 to determine the weighting function in each case. 5 (a) and 5 (b) show an example of this weighting function with respect to the x and y directions in the case of the rectangular glass plate 1. Here, in each case, one side of the rectangle has no effect, but the other side has the greatest effect.

FIG. 5C shows an angle weighting function obtained by forming a derivative of the absolute value of the vector based on the values defined for the x and y coordinates of the glass plate edge 1a. In the example of FIG. 5C, the effect is greatest at the corners of the rectangle. At the center of the side of the rectangle, the effect is zero in all cases because the vector points 90 degrees to the side.

The measured value I of the current is reduced by the current value averaged over the entire measurement and multiplied by a weighting function in the x and y directions. In the example of FIGS. 5 (a) and 5 (b), the curves of FIGS. 6 (a) and 6 (b) are obtained. Offsets in the x and y directions are obtained in units of amperes per measured value by averaging the values. In the examples of FIGS. 6 (a) and 6 (b), the offset in the x direction is zero, and the offset in the y direction corresponds to about 0.13 A per measured value.

To prevent a distorted calculation of the angular offset, the measured value of the current subtracted by the mean is corrected according to the determined x-offset and y-offset and multiplied by the angular weighting function. In the example of FIG. 5 (c), this procedure gives the curve of FIG. 6 (c). The angular offset is obtained by averaging the values. In the example of FIG. 6 (c), this angular offset corresponds to about 0.025 amperes per measurement.

Converting the offset value to a unit of length or a unit of angle is possible, for example, by calibration measurements where the current of the electric motor 11 is detected at a given glass thickness and grinding speed, and at a given offset value. is there. The calibration measurement can be performed by grinding a single glass plate multiple times or by grinding a plurality of glass plates. The glass plate is selectively discarded and the value determined for the offset is used for the subsequent machined glass plate.

In one embodiment, the glass plate 1'is ground twice: in the first grinding, the glass plate 1'is not the final dimension, but rather a predetermined width b, eg b = 0.25 mm or some other suitable value. Grinded to a size with a residual edge. The residual edge is removed in the second grinding. Therefore, based on the second grinding, the current consumed to remove the width b is known. The calibration value (eg, linear offset amperes / mm) is obtained by averaging the current values of the second grinding and subtracting the current values in idle mode, according to FIGS. 5 (a) and 5 (b). The normalization in is from -1 to +1 and can be determined by dividing the result by 2.

Based on the current curve of the first grinding, the offset can be determined in amperes and the calibration values can be converted to mm or degrees.

The two grinding procedures described here have the advantage, in particular, that the program can calibrate to a given glass plate shape without the need for information about glass plate thickness or grinding speed.

In addition, we used the current curve of the second grinding to see if the glass plate was completely ground, i.e., unmachined and / or partially machined. I found that I could decide whether or not. For glass plates that are not completely ground, the offset current value is relatively large. Beyond the predefined thresholds, the glass plate is not recognized as fully ground and is reworked or discarded.

FIG. 7 summarizes the steps of the various methods described above.
Step 100: Grinding is started to configure the device so that the glass plate is continuously ground without offset.
Step 101: The glass plate is ground to the residual edge in the first grinding.
Step 102: The residual edge having a predetermined width is removed in the second grinding.
Step 103: The program determines the offset of the physical units and the corresponding correction value to compensate for the displacement and / or rotation between the x'-y'coordinate system and the xy coordinate system of FIG.
Step 104: The program checks if the glass plate is completely ground. If not, the following is done:
Step 105: The glass plate is disposed of and a new glass plate is ground to the final dimensions according to step 102 using the determined correction value.
Step 106: The user further checks whether the glass plate has been completely ground. This step is optional and may be omitted.
Step 107: The device is configured and a series of production in which a plurality of glass plates are ground is started.

Current I detection and evaluation can be used not only for equipment configuration, but also for continuous production monitoring and continuous adjustment. In continuous production, for example, the offset of each glass plate can be determined, for example half of the offset can be used as the correction value for the next glass plate.

It is also conceivable to monitor the fluctuation of the current I over time. This should essentially correspond to the aging that occurs after the device is configured, that is, in the absence of offsets. If this is not the case during grinding of the glass plate, the facility is no longer properly calibrated and can be reconstructed, for example, by the procedure of FIG.

The measurements described herein can be used in a variety of ways to grind the edges of glass plates, especially glass plates for automobile windows and monitors and displays. Any edge profile to be ground can be considered, such as rectangular, chamfered, C-shaped, rounded edges, stepped cuts, etc. The detection and evaluation of variables, which are a function of the power consumption of the motor, has the advantage, in particular, that no additional sensors need to be provided to determine the offset.

The device may be configured to display information about the detected value of the variable, such as the detected current, the determined offset, the calculated correction value, and / or other parameters.

It is not necessary to detect or evaluate all the values of the variable along the edge of the glass plate to determine the offset. In addition, the values of the variables of only part of the grinding path represent sufficient measurement points to determine the offset with up to three parameters.

This method is also applicable to devices in which multiple grinding tools are used for grinding, such as two or more grinding tools with motors offset from each other. Each grinding tool can optionally machine only part of the edge. The method described here can be used, for example, to determine a correction value for each grinding tool and set an average correction value.

1 Glass plate 1a Glass plate edge 8 Rotating table 9 Support 10 Grinding tool 11 Electric motor 12 Carriage 13 Track 15 Controller

Claims (12)

A method for machining a glass plate (1'), the edge portion (1a') of the glass plate is machined using at least one grinding tool (10), and the glass plate and the motor (1a') are machined. The grinding tools set to rotate by 11) move relative to each other, and the variable (I), which is a function of the power consumption of the motor (11) used to drive the grinding tool, is a machine. The variable (I) is evaluated to be detected along at least a portion of the machined edge (1a') and to determine the offset of the glass plate (1') with respect to the target position (1). A method characterized by that. The edge (1a') is machined by two grindings and the value of the variable detected in the second grinding is used to calibrate the offset determined in the first grinding. Item 1. The method according to item 1. A step in which the value of the variable is determined with respect to a state in which the rotating grinding tool (10) is not in contact with the edge portion (1a').
The value of the variable generated at the portion where the direction in which the edge extends when viewed from the upper surface of the glass plate (1') changes beyond the value of a predetermined angle is omitted for the evaluation. Steps to be adjusted,
A step in which the offset in the first linear axis (x) direction, the second linear axis (y) direction and / or the rotational direction is determined.
A step in which at least one weighting function is defined that applies to the value of said variable detected, based on the shape of a given glass plate, in order to obtain at least one offset.
The method of claim 1 or 2, wherein at least one evaluation step is performed. The actual positions of the target position (1) and the glass plate (1') are adjusted to each other (103), and the correction value to be considered during the machining of the next glass plate is determined, and the detected variable The method of any one of claims 1-3, wherein this procedure is performed until the value is within a predetermined tolerance. The method according to any one of claims 1 to 4, wherein a plurality of glass plates are subsequently machined, and in each case, it is confirmed that the value of the detected variable is within a predetermined allowable range. .. Relative movement of the glass plate (1') and the grinding tool (10) is performed, and only the glass plate or only the grinding tool moves, or both move, and the grinding tool moves along a linear axis. The method according to any one of claims 1 to 5, wherein the glass plate preferably rotates and / or moves along a linear axis when moving. By determining whether the value of the detected variable is less than a predetermined threshold, the place where the glass plate (1') is not machined and / or the place where it is only partially machined is determined. The method of any one of claims 1-6, wherein the information that the glass plate is not completely ground is associated with the glass plate if it is confirmed and not applicable. The variable according to any one of claims 1 to 7, wherein the detected variable is preferably an electrical variable corresponding to the current consumed by the motor (11) used to drive the grinding tool. the method of. An apparatus for machining a glass plate (1'), wherein the method according to any one of claims 1 to 8 can be carried out, and the apparatus is a support for the glass plate (1'). 9) and at least one grinding tool (10) used to machine the edge (1a') of the glass plate and set to rotate by a motor (11) and drive the grinding tool. It has a controller (15) for detecting and evaluating a variable that is a function of the power consumption of the motor used for machining, and the support and the grinding tool machine the edges. A device that is configured to be movable relative to each other and the controller is provided with a program that, when executed, can perform the method. 9. A monitor in which information about the detected value of the variable, the calculated offset, and / or the correction value calculated to adjust the target position and the actual position to each other is displayed during operation. The device described in. A computer program according to claim 9, wherein when the computer program is executed in the apparatus according to claim 9, the method according to any one of claims 1 to 8 is executed. A data carrier in which the computer program according to claim 11 is stored.

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