JPH1170471A - Glass chamfering method and machine therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lessen chippings in chamfering glass with constant pressure. SOLUTION: A constant-pressure glass chamfering method controls the revolving speed of a grinding wheel 2 according to the relative feed rate and depth of cut of the wheel 2 to a glass plate 1. A glass chambering machine employing this method comprises a grinding wheel 2 pressed by preset force against the edge of a glass plate 1 fixed to a glass holder 3 to chamfer the glass 1, a scanner mechanism 7 for displacing the wheel 2 along the glass edge relatively, and a motor 5 for revolving the wheel 2. The motor is provided with a revolving-speed controller mechanism 9 for varying the wheel revolving speed in accordance with the relative feed rate and depth of cut of the wheel 2 to the glass 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chamfering process for a peripheral portion of a glass having a complicated shape such as a window glass for an automobile and a panel / funnel for a CRT.

[0002]

2. Description of the Related Art Generally, a glass edge is chamfered by a grinding process in which a cup-shaped grindstone or a full-shaped grindstone is rotated at a high speed. The grinding process is classified into a fixed size method in which a glass is machined by cutting a grindstone to a predetermined size, and a constant pressure method in which the grindstone is cut by a constant pressing load.

[0003] The sizing method usually uses a highly rigid device and can perform high-precision processing, but requires high dimensional accuracy of the glass before processing and high positional accuracy for holding the glass. On the other hand, in the constant pressure method, a relatively inexpensive device with low rigidity can be used, and processing is performed according to the shape of the glass, so even if the dimensional accuracy and the holding position accuracy of the glass before processing are somewhat poor, the chamfered portion can be used. There is an advantage that dimensions and shapes can be secured.

[0004] However, the constant pressure method has a drawback that the cutting amount is reduced as the sharpness of the grinding wheel is reduced. As a method of compensating for this disadvantage, since the deterioration of the sharpness of the grinding wheel is accompanied by an increase in the current value of the motor for driving the grinding wheel, a method of increasing or decreasing the pressing force of the grinding wheel according to the current value, or a method of reducing the cutting amount of the grinding wheel by one sheet A method is adopted in which the glass is actually measured and the pressing force of the grindstone is increased or decreased in accordance with a deviation from a predetermined cutting amount.

Furthermore, in order to make chamfering efficiently while making the cut amount as uniform as possible, the pressing force of the grindstone is adjusted depending on the shape of the glass, or the relative feed speed of the grindstone is increased, for example, the straight portion is fast and the corner portion is not. There is also known a method of adjusting so as to make it slow. However, in the conventional pressing force control chamfering apparatus, the feed speed of the grindstone is reduced and the pressing force is reduced in order to suppress a chamfer margin at a corner portion. However, if the pressing force of the whetstone is reduced, centrifugal force will be applied at the corners, so the whetstone will be easily separated from the glass, and as a result, the whetstone will not sufficiently contact the glass immediately due to slight misalignment of the glass position, resulting in poor chamfering Was easy to occur.

[0006]

However, in the constant pressure type chamfering, the rigidity of the device is generally low and the grindstone is liable to vibrate. Therefore, if the feed speed of the grindstone is simply increased or the pressing force is increased, the glass at the chamfered end portion is simply increased. Chipping (chipped)
Therefore, the feed speed of the grinding wheel must be kept low.

[0007] According to experience, even if the feed speed of the grindstone is set in advance in accordance with the shape of the glass, and if the feed rate is adjusted based on the feed speed to make the cutting amount uniform, the sharpness of the grindstone may vary. Is added, it is difficult to continue uniform chamfering in an efficient state.

An object of the present invention is to solve the above-mentioned disadvantages of the prior art and to provide a glass chamfering method and apparatus in which occurrence of chipping due to vibration of the apparatus is small.

[0009]

SUMMARY OF THE INVENTION According to the present invention, in a glass chamfering in which the cutting amount changes according to the magnitude of the pressing force, the number of revolutions of the grinding wheel is adjusted according to the relative feed speed of the grinding stone to the glass or the cutting amount. A glass chamfering method characterized by controlling. The present invention also provides a grindstone that comes into contact with the periphery of the glass fixed to the glass holder with a predetermined pressing force and chamfers, a scanning mechanism that relatively moves the grindstone along the periphery of the glass, and rotationally drives the grindstone. A motor for adjusting the rotation speed of the grinding wheel according to the relative feed speed of the grinding wheel and the glass or the amount of cutting of the grinding wheel. A glass chamfering device is provided.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The chamfering apparatus of the present invention is of a so-called constant pressure type, and has a mechanism for pressing a grindstone with a preset load, and the load is increased or decreased by a hydraulic cylinder, a pneumatic cylinder, a torque motor, or the like. Preferably it is possible. In particular, it is suitable for pressing force control grinding (chamfering) in which chamfering is performed while adjusting the pressing force in accordance with the sharpness variation of the grindstone. As a constant pressure type chamfering device, a mold is prepared in advance in accordance with the shape of the glass to be chamfered, and while receiving the pressing force of the grindstone with this mold, a chamfering device for chamfering so as not to cut excessively is used. In addition, chamfering devices having extremely low rigidity are included.

As the grindstone in the present invention, a grindstone in which diamond abrasive grains are fixed on a disk with a metal, a polymer resin or the like, or a grindstone obtained by firing alumina, carborundum, or the like can be used. The abrasive grains and types of these grindstones are appropriately selected in consideration of the type of glass to be chamfered and the required surface roughness of the chamfered surface. The size of the grindstone may be selected mainly according to the size and shape of the glass.

The present invention is characterized in that the number of revolutions (rpm) of the grindstone can be changed as appropriate, and the number of revolutions is controlled in accordance with the relative feed speed of the grindstone to the glass or the cutting amount of the grindstone. Here, controlling the number of revolutions of the grindstone in accordance with the feed speed or the cutting amount means that the number of revolutions is adjusted by at least one of them, and naturally includes controlling the number of revolutions by both of them.

In a preferred embodiment of the present invention, the number of revolutions of the grindstone is controlled in accordance with a preset feed speed. In this case, if the shape of the glass to be chamfered is determined, the feed speed can be empirically or theoretically determined in accordance with the shape. This feed speed is set in the control device of the scanning mechanism of the grindstone or the glass scanning mechanism, and the grindstone is relatively moved along the periphery of the glass according to the set value. Therefore, the number of rotations is adjusted by automatically controlling the driving motor for the grindstone based on the feed speed information.

In the chamfering of glass, chipping is particularly likely to occur at the start of chamfering in which the grindstone first strikes the glass end face. Therefore, in the conventional chamfering method, the generation of the chipping is suppressed by finely adjusting the pressing force of the grindstone, but a satisfactory result is often not obtained. According to the present invention, the occurrence of chipping can be effectively suppressed by reducing the rotation speed of the grindstone at the start of chamfering in addition to the adjustment of the pressing force.
Therefore, it is preferable that the number of revolutions of the grindstone be the lowest during glass contact, and thereafter, the number of revolutions be controlled in accordance with the feed speed of the grindstone. Further, in this case, it is more effective to reduce the feed speed of the grindstone at the start as much as possible.

Since the cutting amount of the grindstone has at least a close relationship with the feed speed, in order to perform uniform chamfering under a constant pressing force, the number of revolutions of the grindstone must be adjusted according to the feed speed. Is an effective means. The present invention aims at optimizing the number of revolutions with respect to the feed speed by controlling the number of revolutions corresponding to the feed speed under the condition that the grinding stone does not generate vibration, and performs chamfering under the condition that the grindstone does not generate vibration. To Optimization of the feed rate and the number of revolutions also enables a reduction in the chamfering time of one piece of glass.

When the cut amount of one glass differs depending on the chamfered position, that is, when it is desired to change the cut amount positively depending on the chamfered position, the number of revolutions is adjusted according to the cut amount. Actually, when relatively moving the grindstone at a preset feed speed, the rotation speed may be increased at the point where the cutting depth is desired to be increased. To optimize. Then, if necessary, both are optimized, including the feed speed.

In the present invention, the maximum value of the rotation speed of the grinding wheel is:
During the chamfering of one glass sheet, it is preferable that the value be 1.2 times or more the minimum value of the number of revolutions of the grindstone. The reason is as follows. In an apparatus system with low rigidity, the grindstone easily vibrates during chamfering, and the amplitude increases as the eccentricity of the attached grindstone increases and as the sharpness decreases. When the rotational speed of the grindstone is constant, irregularities corresponding to the vibration of the grindstone are gradually formed on the grindstone surface, and this is emphasized as the number of processed workpieces increases, and the roundness of the grindstone is significantly reduced.

The main cause of the occurrence of chipping in the constant pressure type chamfering apparatus is the deterioration of roundness. In order to suppress the deterioration of the roundness of the grindstone, the rotation speed of the grindstone is constantly changed so as not to vibrate at a specific frequency, or the frequency is set to an integral multiple of the rotation speed of the grindstone. What should be done is not to. However, the frequency generated during the chamfering is the resonance frequency of the device system and varies depending on the load applied to the grindstone and cannot be uniquely determined. The frequency of the grinding wheel per rotation does not change even if the grinding wheel rotation speed is slightly changed. However, if the maximum value of the number of revolutions of the grindstone during chamfering one glass is 1.2 times or more of the minimum value, the frequency per revolution of the grindstone can be changed, and the roundness of the grindstone deteriorates. It can be greatly reduced.

When the rotation speed of the grindstone is constant, the cut amount increases when the feed speed is reduced. Therefore, when the feed speed is reduced near the corner of the glass, the rotation speed is reduced so that the cut amount is not excessive. If the rotation speed control of the grindstone is incorporated into the chamfering of the corner portion, the cutting amount can be adjusted by reducing the rotation speed while keeping the pressing force of the whetstone unchanged. As a result, even if centrifugal force acts on the whetstone at the corner, the whetstone is always pressed against the glass end face because the whetstone is sufficiently pressed. Defects can be eliminated.

At the same time, the work speed can be shortened because the feed speed of the grindstone at the corner can be increased compared to the conventional method of adjusting only by the pressing force. In addition, in order to round a corner portion cut into a square shape, it is necessary to make a deeper cut than other portions. Therefore, such a portion is dealt with by increasing the number of revolutions.

The pressing force of the grindstone is adjusted based on the value of electric power, current or voltage supplied to the grindstone rotating motor during chamfering, and is a measured value of the cut amount of a predetermined portion of the glass chamfered by the grindstone. The pressing force can be corrected. In this cut amount measurement, the actual cut amount is obtained by actually measuring the size of the glass before and after chamfering using a contact type or non-contact type sensor.

Hereinafter, a chamfering apparatus and a chamfering method according to the present invention will be described with reference to the drawings. 1 and 2 are a plan view and a front view of the chamfering device of the present invention. The glass 1 is fixed by the holder 3 and chamfered by the grindstone 2. The grindstone 2 is moved along the periphery of the glass 1 by the scanning mechanism 7 and makes one round of the glass. A method of chamfering the glass 1 by rotating and linearly moving it without scanning the grindstone 2 can also be adopted, and the grindstone and the glass may be relatively moved.

The grinding wheel 2 is rotated at high speed by a motor 5,
A load is applied by the pressing force adjusting mechanism 6 via the grindstone support 4. The motor 5 is a variable speed motor, and its rotation speed is controlled by a rotation speed adjustment mechanism 9. It should be noted that the speed change function of the motor 5 may be replaced by a continuously variable transmission.

The sharpness of the grindstone is determined by the current value of the load ammeter 10 of the motor 5. The sharpness of the whetstone is
The correction can also be made by obtaining the ratio of the actual cut amount to the planned cut amount for the glass one or several sheets before the glass to be chamfered. For the actual measurement of the cut amount, a method of obtaining an end position of a specific portion of the glass by, for example, the grinding amount control device 12 is effective. The pressing force of the grindstone is calculated by multiplying the value obtained from the load current value by a correction based on the actually measured cutting amount. The dotted line in FIG. 2 shows a system for adjusting the pressing force of the grindstone according to the fluctuation of the sharpness of the grindstone.

The relative feed of the grindstone 2 to the glass 1 is set at a high speed in the straight portion of the glass in order to secure productivity, and the speed is reduced in front of the corner to secure the followability, and is usually set to be relatively large. The speed is increased again after passing through the corner, in accordance with the amount of cut at the corner.

The pressing force of the grindstone 2 is the same for one piece of glass, and the adjustment of the cutting depth due to a change in the feed speed or the like is performed by increasing or decreasing the number of revolutions. That is, the rotation speed is set to be high in the high-speed feeding linear portion, and the rotation speed is reduced near the corner where the feeding speed is low, and the rotation speed is increased again in the corner portion where it is necessary to take a large cutting amount.
Coolant for cooling the grindstone 2 is supplied from the nozzle 11.

In the present invention, the number of revolutions of the grindstone is controlled mainly in accordance with the chamfering speed as described above, and various control patterns can be set for the feed speed of the grindstone. FIG. 3 is a preferred example showing the relationship between the feed speed and the number of revolutions of the grindstone. As shown in the figure,
Until the feed speed reaches the predetermined value S, a pattern that increases in accordance with the feed speed is desirable. Here, the feed rate S can be set according to the rigidity of the apparatus, the weight of the grindstone, the shape and size of the glass to be chamfered, and experience shows that the effect of the rigidity of the apparatus is particularly large. can do. That is, S is determined as a value unique to the chamfering device and the chamfering condition.

For example, in the case of an apparatus having a relatively low rigidity, S is about 18 m / min, and the rotation speed of the grindstone at this time is about 3000 rpm. If the rigidity of the device is increased, S can be increased to 18 m / min or more,
Naturally, the rotation speed at that time can be increased to 3000 rpm or more, and chamfering at high speed rotation can be obtained.

When the feed speed of the grindstone is equal to or higher than the above S,
If the number of revolutions is changed, the quality of chamfering tends to deteriorate. Specifically, when the rotation speed is increased in accordance with the feed speed at a feed speed equal to or higher than S, the incidence of small chips increases, resulting in poor chamfering. Therefore, as an ideal rotation speed pattern that can withstand production, it is desirable that the setting be made between the feed speeds 0 to S of the grindstone, and that the rotation speed not be changed at a feed speed higher than this. The relationship between the feed speed and the rotational speed at the feed speeds 0 to S is such that the rotational speed is increased toward the rotational speed permitted by the feed speed S as described above, while the pressing force of the grindstone is substantially constant. Increase according to the feed rate.

FIG. 3 shows how to increase the rotation speed of the grinding wheel at this time.
Although it may be proportional to the feed speed as in (A), usually, where the feed speed is low as in (B), the rotation speed is increased at a large ratio with respect to the feed speed. Thus, a pattern in which the change in the number of rotations is reduced is desirable. If the number of revolutions is set to a certain number of revolutions, for example, 300 rpm or less in the case of a 6-inch grindstone, the chamfering quality tends to deteriorate regardless of the feed speed of the grindstone. It is desirable.

[0031]

EXAMPLE On a glass holding table movable in the XYθ directions in a horizontal plane, a 700 × 450 × 3.5 mm plate glass is horizontally held by vacuum suction while applying a coolant,
Chamfering was performed by making the periphery of the glass penetrate a rotating grindstone provided with a pressing force adjusting mechanism and a rotating speed adjusting mechanism and making a round. The grindstone is a 150 mm diameter metal bond diamond grindstone. The set value of the glass feed speed is a maximum of 21 m / glass.
Min, minimum 9m / min, whetstone rotation speed up to 4200rpm
m and a minimum of 3000 rpm.

The pressing force of the whetstone is 1 for the first glass.
8kg weight, gradually increased with the number of chamfers, 1
The 000th sheet weighed 25 kg. The cut amount of the chamfered glass is 0.1 mm at the vertex of the chamfer, excluding the corners.
~ 0.2mm, 0.3mm for any glass
No greater chipping was observed. No deterioration in the roundness of the whetstone was observed.

[0033]

[Comparative Example] A glass plate of 700 × 450 × 3.5 mm is horizontally vacuum-adsorbed and held on a glass holding table movable in the XYθ directions in a horizontal plane, and while applying a coolant,
Chamfering was performed by making the periphery of the glass penetrate a rotating grindstone provided with a pressing force adjusting mechanism and making a round. The grindstone is a full-form metal-bonded diamond grindstone having a diameter of 150 mm, which is the same as in the example. The set value of the feed rate of the glass is 21 m / min at the maximum, 9 m / min at the minimum, the rotation speed of the whetstone is constant at 4200 rpm, and the pressing force of the whetstone is the pressing force at the maximum feeding speed. It was set to be 1.4 times that of small time.

The pressing force of the grinding wheel at the maximum feed speed is 1
The second glass weighed 18 kg. The cut amount of the chamfered glass is 0.
1 to 0.2 mm. 0.5mm width from the 314th sheet
The above-described chipping occurred, and the grindstone dressing process was performed on the 320th sheet, and the chipping temporarily decreased. However, since the chipping having a width of 0.5 mm or more occurred again from the 563rd sheet, the operation was stopped. The pressing force of the whetstone at this time was 27 kg weight. In addition, the roundness of the grindstone was 30 μm before use, but deteriorated to 75 μm, and changed to a shape having four peaks and valleys in one circumference.

[0035]

As described in detail above, according to the present invention,
Since the occurrence of chipping due to the vibration of the grindstone during the chamfering process is small, the chamfering quality is stable, the yield is improved, and the chamfering speed can be improved. Further, since the roundness of the grindstone is less deteriorated, there is an effect that the shape of the grindstone can be corrected in a short time.

[Brief description of the drawings]

FIG. 1 is a plan view of an embodiment of the present invention.

FIG. 2 is a front view of the embodiment of the present invention.

FIG. 3 is a graph schematically showing a preferred relationship between a feed speed and a rotation speed of a grindstone in the present invention.

[Explanation of symbols]

 1: Glass plate 2: Whetstone 3: Holder 4: Whetstone support 5: Motor 6: Pressing force adjustment mechanism 7: Scanning mechanism 9: Rotation speed adjustment mechanism 10: Load ammeter 11: Nozzle 12: Grinding amount control device

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akinori Matsumoto 1 Asahi, Taketoyo-cho, Chita-gun, Aichi Prefecture Inside Asahi Glass Co., Ltd. (72) Inventor Isao Saito 426-1 Ozawa Uehara, Kakuda Aikawa-cho, Aiko-gun, Kanagawa Prefecture Asahi Glass Co., Ltd.

Claims (5)

[Claims] In a glass chamfer in which the cutting amount changes according to the magnitude of the pressing force, the number of revolutions of the grinding wheel is controlled according to the relative feed speed of the grinding stone to the glass or the cutting amount of the grinding stone. Glass chamfering method. 2. The glass chamfering method according to claim 1, wherein the maximum value of the number of revolutions of the grinding wheel during chamfering one glass sheet is 1.2 times or more the minimum value. 3. The glass chamfering method according to claim 1, wherein the pressing force of the whetstone is adjusted according to the change in sharpness of the glass. 4. The method according to claim 1, wherein the rotation speed of the grinding wheel is controlled to increase with an increase in the feeding speed only in a range where the feeding speed of the grinding wheel is equal to or less than a predetermined value.
The glass chamfering method described. 5. A grindstone which comes into contact with the periphery of the glass fixed to the glass holder with a predetermined pressing force and chamfers, a scanning mechanism for relatively moving the grindstone along the periphery of the glass, and for rotating the grindstone. A motor having a rotation speed adjusting mechanism for changing the rotation speed of the grinding wheel according to the relative feed speed of the grinding wheel and the glass or the cutting amount of the grinding wheel. Glass chamfering device.