JPH1177500A - Working method for end part of glass plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance strength of the end part of a glass plate by grinding only the ridge parts on both end sides of the end face without grinding the cut end face of the glass plate left, in cut condition, after cutting the glass plate into a fixed size. SOLUTION: A glass plate 1 is cut into a fixed size, and the end face 1a is not ground, and left in cut condition. The ridge parts positioned on both ends of the end face of the glass plate 1 are ground so as to form ridge part polished faces 1d. The ridge part polished face 1d is slanted against the end face 1a, and the angle β formed by the ridge part polished face 1d and the end face 1a is desirable to be 120 deg.<=β<=150 deg.. The size of the projecting width H on the end face 1a side of the ridge part polished face 1d is properly decided according to the thikness of the glass plate 1 and H>=1 mm is desirable, considering a crack generated by carving a cutting line at cutting off the glass plate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for polishing a glass plate end.

[0002]

2. Description of the Related Art In a state where a cut edge is not ground after cutting a glass plate, when a stress is applied to a glass edge, a ridge (a corner at a boundary between a glass plane and an edge), particularly a cut of the edge is cut. At this time, stress concentrates on a portion where a cutting line (cut groove) is formed by a wheel cutter or a diamond cutter, which causes a destruction. In addition, a thick plate glass exceeding 10 mm may be cut obliquely when the cut end face is not perpendicular to the glass flat portion at the time of cutting.

In particular, in the case of architectural glass sheets used for glass doors and the like whose end faces are exposed, it is necessary to ensure that the end faces have a sufficiently good finish and have a sufficient strength.

[0004] Conventionally, especially in the case of manufacturing a glass sheet for construction, in order to sufficiently improve the strength and the appearance quality, the end of the glass sheet is polished by using a plurality of whetstones having different abrasive grain sizes. I was

FIG. 4 is an explanatory view of a conventional method for polishing an end portion of a glass plate. A glass plate 1 to be polished is conveyed as indicated by an arrow A, and a plurality of (six in the example in the figure) end-face polishing cup-type grindstones 2 and two ridges 2 for edge polishing on both sides of the end surface are conveyed along the conveyance path. The cup-shaped grindstones 2a and 2b are continuously arranged on a straight line. A plurality of grinding stones for polishing the end face 2
First, in order to make the end surface perpendicular to the glass surface, a # 80 (average abrasive particle diameter 230 μm) grindstone with a large average abrasive particle diameter and high grinding efficiency is provided, and then the grinding wheels are sequentially arranged. By reducing the particle size, for example, # 100 (average abrasive particle size 19
0 μm), # 120 (average abrasive grain diameter 160 μm), # 1
No. 40 (average abrasive particle diameter 140 μm), # 170 (average abrasive particle diameter 120 μm), and the number of abrasive particles according to the required finishing surface (rough finishing, polishing, polishing, etc.) Is provided. The figure uses a grindstone of # 200 (average abrasive particle diameter 100 μm) for rough finishing. A grindstone of # 500 (average abrasive particle size 45 μm) is generally used for polishing, and a # 800 (average abrasive particle size of 30 μm) is generally used for polishing.

After such a plurality of grindstones 2 for polishing the end face, two grindstones 2a and 2b for grinding the ridge are arranged with their rotation axes inclined so as to grind the ridges. As the grindstones 2a and 2b for polishing these ridges, a grindstone of # 270 (average abrasive particle diameter 65 μm) was used.

[0007]

However, in the above-mentioned conventional method for processing an end portion of a glass plate, as shown in FIG.
First, since the end face 1a of the glass plate is polished with a grindstone (# 80, # 100, etc.) 2 having a large average abrasive grain size, the end face 1a is larger than that of the grindstone 2 having a small average abrasive grain size. Cracks (polishing flaws) occur. A part of the cracks, when polished by the subsequent grinding wheel 2 having a small average abrasive grain diameter, collide with the abrasive grains, so that the cracks caused by the small abrasive grains are superimposed on each other. 1
It remains inside a. These deep cracks reduce the strength quality of the glass edge.

Further, among the cracks caused by such edge polishing, cracks in the vicinity of the ridge 1b are particularly large.
The cracks are further developed deeply by the collision of the abrasive grains during polishing, and the strength quality is further reduced. When such a deep crack is present, when a large stress acts on the glass sheet 1, the glass sheet 1 is broken starting from the crack.

On the other hand, for the purpose of increasing the edge strength of the glass sheet 1, there has been proposed a heat-strengthened glass in which the end face of the glass sheet is polished into a curved shape (Japanese Patent Laid-Open No. 9-714).
No. 29). However, in the method for polishing an end portion of a glass plate described in this publication, a specially shaped polishing wheel must be used, and the production of a new wheel becomes troublesome, and the processing cost of the edge and the quality control cost increase.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the prior art, and has a simple structure which reduces the area of grinding and polishing of the end portion of a glass plate to generate cracks which cause glass breakage. It is an object of the present invention to provide a method for processing an end portion of a glass plate in which the strength of the end portion of the glass plate is increased.

[0011]

In order to achieve the above object, according to the present invention, after cutting a glass plate to a predetermined size,
Without grinding while cutting the glass plate cutting end,
There is provided a method for processing an end portion of a glass sheet, wherein only a ridge portion on both end sides of the end surface is ground.

According to this method, only the ridge is polished without polishing the end surface of the glass plate, and the area of the grinding / polishing processing of the end portion of the glass plate is reduced, so that the occurrence of cracks causing glass breakage is reduced. It is possible to increase the strength of the edge of the glass plate.

[0013] In this case, the ridge of the glass plate has a maximum surface irregularity of 0.
It is preferable to finish to 003 mm or less.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for processing an end portion of a glass plate according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing a polishing state of a glass plate end portion according to an embodiment of the present invention by a processing method using a cup-shaped grindstone. FIG. 2 is a schematic cross-sectional view of a polished state by a processing method using a cylindrical grindstone at an end portion of a glass plate according to another embodiment of the present invention. FIG. 3 is a schematic cross-sectional view of a polished state by a processing method using buff polishing of an end portion of a glass plate according to still another embodiment of the present invention.

In FIG. 1, a glass plate 1 is cut to a predetermined size, and the end surface 1a is not ground while being cut. In the present invention, the state of the above-mentioned as-cut state means that the grinding processing has not been performed, and a processing not directly related to the grinding, for example, a bonding step for constructing a glass sheet. And the like to be applied to the end face 1a as necessary are included in the above state.

The ridge polishing surface 1d is formed by grinding ridges located at both ends of the end surface of the glass sheet before grinding. The edge polishing surface 1d is inclined with respect to the end surface 1a, and the angle β formed between the edge polishing surface 1d and the end surface 1a is 120 ° ≦ β ≦ 1.
Preferably it is 50 °. Therefore, the angle α between the glass plate surface 1c and the ridge polishing surface 1d is 120 ° ≦ α ≦
Preferably it is 150 °.

The projection width H of the polished ridge surface 1d toward the end surface 1a.
Is appropriately determined according to the thickness of the glass plate, but preferably H ≧ 1 mm in consideration of a crack generated by a step of making a cutting line when cutting the glass plate.

In the present invention, it is preferable to omit the six grindstones 2 for edge polishing in the prior art of FIG. 4 and to use only two grindstones 2a and 2b for edge polishing.

That is, as shown in FIG. 1, the glass plate 1
Cut the glass plane 1c with a wheel cutter or the like (cut groove)
, Only the glass ridge, which is the weakest part in strength (the part where the crack is left by the wheel cutter) when cut, is polished by the grindstone. Specifically, the average abrasive particle size is 50 μm or less, preferably 45 μm or less, and when expressed by a grinding wheel number, # 400 or more, preferably # 500.
No. 1 or more abrasive layer 3 is mounted on a disk 4 and a cup-shaped grindstone 2 having a rotating shaft 5 at its center is used. The rotating shaft 5 is inclined with respect to the end surface 1a to form a ridge 1b (glass plate). Surface 1
Only the corner of the boundary between c and the end face 1a (see FIG. 5) is polished. The ridge-polished surface 1d that has undergone this polishing step is finished with a maximum surface unevenness of 0.003 mm or less, so that cracks that occur on the polished surface are also small, and stress concentration when a load is applied to the glass edge is reduced. be able to. Since the processing is not performed, the end face 1a has no crack due to grinding, and has a higher strength than the ridge polishing surface 1d.

In this polishing step, the above-mentioned cup-shaped grindstone 2 is used.
It is not limited to the polishing method using, for example,
As shown in FIG. 2, a cylindrical abrasive wheel 3 is provided with conical abrasive layers 3 at both ends of a cylinder, and the abrasive layer 3 is brought into contact with a ridge 1b of a glass plate 1 as a workpiece to perform polishing. 3, a buff polishing method in which the outer peripheral surface of the polishing belt 7 is brought into contact with the ridge 1b of the glass plate 1 as a workpiece, as shown in FIG. 3, or a combination thereof. The polishing may be performed by a polishing method. In any case, the ridge 1b according to the above-described embodiment of the present invention is polished to finish the maximum value of the surface unevenness of the ridge polished surface 1d to 0.003 mm or less,
The end face 1a need not be processed at all.

[0022]

EXAMPLES Hereinafter, more specific examples of the present invention will be described. For a float glass with a nominal thickness of 8 mm, at a feed rate of 0.7 m / min and a grindstone rotation speed of 1000 rpm,
One example sample and two comparative example samples for strength comparison were processed as follows. In addition, each sample prepared 60 sheets of the same specification, and these were used for the strength evaluation shown below.

Example: Average abrasive particle size is 45 μm (# 500
No.), only the glass ridge was polished using the cup-shaped whetstone.

Comparative Example 1: Average abrasive grain size was 230 μm (# 8
No. 0) and gradually refined to 45 μm
The end face was polished using a (# 500) cup-shaped grindstone, and then only the ridges were polished and finished using a cup-shaped grindstone having an average abrasive grain size of 45 μm (# 500).

Comparative Example 2: A cut-off product in which the glass edge is not polished and ground.

After polishing, 60 pieces of float glass having a length of 100 cm and a height of 10 cm were prepared for each condition for evaluation of strength. The strength experiment
Under the conditions of room temperature of 16 to 21 ° C. and relative humidity of 45 to 55%, a load span of 30 cm and a support span of 90 cm capable of loading a uniform tensile stress on a central portion of 30 cm of a processing side of the sample.
Was performed by a four-point bending test. The maximum height of each sample was measured according to JIS B0601. Table 1 shows the results. Table 2 shows the ratio of the fracture starting point under each condition in the strength test.

[0027]

[Table 1]

[0028]

[Table 2]

As can be seen from Table 1, only the ridge portion # 500
In the case of the embodiment in which the polishing was performed in number, the average fracture stress value was 160 kgf / cm compared with the glass cut product (Comparative Example 2).
² (1.34 times), and increased by 76 kgf / cm ² (1.19 times) even at the lower limit of the breaking stress 3σ _n-1 .

The lower limit of 3σ _n-1 means a failure probability of 1/1000, and when a stress indicated by the lower limit of 3σ _n-1 is applied to a glass plate, 1 out of about 1000 sheets is obtained.
This means that cracks occur in one glass plate.

Further, in the case of Comparative Example 1 in which the end face by the conventional processing method was finished by # 500 after stepwise polishing and the ridge was finished by # 500, the average fracture stress was lower than that of the glass cut product (Comparative Example 2). Is an increase of 51 kgf / cm ² (1.11 times)
And the lower limit of breaking stress 3σ _n-1 is 47kgf /
A decrease in strength of cm ² (0.88 times) was confirmed.

Also, as can be seen from Table 2, in the case of Comparative Example 1, which is a conventional example in which the end face is finished with # 500 after stepwise polishing and the ridge is finished with # 500, 92% of the fracture starting point is the end face. However, in the case of the embodiment in which only the ridge was polished with # 500, the polished surface of the ridge was broken 100%. In the case of the glass cut product (Comparative Example 2), the place where the crack was formed by the wheel cutter at the time of cutting was the fracture starting point.

That is, it can be seen that the glass is broken due to cracks generated by the processing, and moreover, the breakage from the end face where a rough grindstone is first used is larger than the breakage from the ridge. When the end face according to the prior art is polished, a large crack is generated on the end face, which results in a decrease in edge strength. On the other hand, when only the ridge according to the present invention is polished, the end face is not polished, so that a large crack does not occur. Is polished with a fine grindstone, so that only small cracks are generated and the edge strength can be drastically increased.

Regarding the processing apparatus, when only the ridge is polished, a grinding wheel for polishing the ridge on the front surface and the back surface and a driving motor may be provided. Since no motor is required, the size of the apparatus can be reduced and the operating cost of the equipment can be reduced.

The angle α between the surface of the glass plate on both sides of the end face and the polished edge and the angle β between the end face and the polished edge (see FIG. 1) are both 120.
It is preferable from the viewpoint of strength that the angle is in the range of 150 ° to 150 ° (if one of α and β is 120 to 150 °, the other is necessarily 150 to 120 °). The projection width H of the polished ridge surface toward the end face is 1 mm or more. Thereby, the end portion can be satisfactorily finished without performing the end surface polishing accompanied by a decrease in strength, and the strength of the glass edge can be increased and the appearance can be improved.

[0036]

As described above, according to the present invention,
By polishing only the ridge without polishing the end face of the glass plate, it is possible to improve the edge strength. In addition, since it is not necessary to process the end face, the processing device may be only the polishing equipment for the ridge, and it is possible to reduce the size of the device and the operating cost of the equipment.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a polished state by a method for processing an end portion of a glass plate according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of a polished state of a glass plate edge processing method according to another embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view of a polished state by a method for processing an end portion of a glass plate according to still another embodiment of the present invention.

FIG. 4 is a view showing the arrangement of grindstones in a conventional glass plate edge polishing method.

FIG. 5 is a schematic sectional view of a polished state by the polishing method of FIG. 4;

[Explanation of Signs] 1: Glass plate 1a: End face 1b: Edge 1c: Surface 1d: Edge polishing surface 2: Cup type grinding stone 3: Abrasive grain layer 4: Disk 5: Rotating shaft 6: Cylindrical grinding stone 7: Polishing Belt

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tsuyoshi Tanaka 1-1-1 Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Inside the Keihin Plant of Asahi Glass Co., Ltd.

Claims (2)

[Claims] 1. A glass sheet edge, wherein after cutting a glass sheet to a predetermined size, only the ridges at both ends of the glass sheet are ground without cutting the glass sheet cut end face. How to process the part. 2. The ridge of the glass plate has an average abrasive grain size of 50.
Surface roughness of up to 0.003mm using a whetstone of μm or less
The method for processing an edge of a glass sheet according to claim 1, wherein the finishing is performed as follows.