Cutting method for plate glass mother material

Details Cutting method for plate glass mother material Cutting method for plate glass mother material

1999-09-14

2002-06-11

Ashley, Boyer (Department: 3724)

Severing by tearing or breaking

Methods

With preliminary weakening

C225S094000, C225S096500, C225S104000

Reexamination Certificate

active

06402004

ABSTRACT:

This application claims the Paris convention priority of Japanese patent application Hei 10-261347 filed on Sep. 16, 1998, the entire disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of cutting a plate glass member as a mother material of materials to be pressed for use on a reheat press method, and to a plate glass mother material cutting device, particularly to a method of cutting a plate glass mother material in which a plurality of grooves are scribed/processed beforehand on one main surface, and to a plate glass mother material cutting device.
2. Description of the Related Art
When optical elements such as an optical lens and a prism are formed, press molding is used. Examples of a press molding method mainly include a precision press molding method, a direct press method, and a reheat press method.
The precision press molding method is a molding method of transferring the shape and surface precision of a molding die to a softened glass, and the pressed material. requires no grinding or polishing.
On the other hand, the direct press method, and he reheat press method are molding methods based on the premise that after the press molding the grinding for bringing the shape of the pressed material close to a final product shape, and the polishing for polishing the surface of the pressed material are performed.
Since the precision press molding method is free of the polishing, it is suitable for manufacturing lenses having shapes difficult to polish, such as a non-spherical lens. However, in order to reproduce the shape precision of the molding die, pressing has to be performed when the viscosity during pressing is in a relatively high range of 10
8
to 10
12
dPa·S, and only the glass material satisfying the condition that it fails to be devitrified at the pressing viscosity can be used. Moreover, problems are that a manufacture device is large-scaled and expensive, and that manufacture cost is raised.
Therefore, in order to manufacture a large amount of glass products while the production cost is suppressed, the direct press method and the reheat press method are suitable.
The direct press method comprises injecting a predetermined amount of molten glass flowing out of a discharge pipe into lower and upper dies of the molding die, and performing pressing at a relatively low viscosity of around 10
3
dPa·S. According to this method, the pressed material has a high weight precision, but the method is not suitable for the production of a small amount of a wide variety of products.
On the other hand, the reheat press method comprises preparing a material to be pressed having a predetermined weight, reheating the material to be pressed from a normal temperature, softening the material, and performing press molding by the molding die at the viscosity of around 10
5
dPa·S. This method is not suitable for the production of a large amount of a small variety of products, but is suitable for the production of the small amount of the wide variety of products. In the reheat press method, when the weight of the material to be pressed is insufficient as compared with a cavity in the press molding die, the cavity of the molding die is insufficiently filled with the material to be pressed, which causes an elongation defect. Moreover, when the material to be pressed has an excessive weight, another problem occurs that the material overflows the molding die. Therefore, in the reheat press method, the weight adjustment of the material to be pressed is a big problem.
For example, glass materials to be pressed have been heretofore prepared by a method of using a cutting blade to cut the materials out of a plate-like glass mother material (hereinafter referred to as “the blade dicing method”). The blade dicing method lacks economical property because a part of the glass mother material is necessarily lost as a cutting margin. Moreover, since wear on a blade (cutting blade) is relatively excessive, the blade needs to be frequently replaced. Furthermore, since the blade is deflected during cutting, it is difficult to cut a large number of materials to be pressed having the same size out of one glass mother material, and weight dispersion among the obtained materials to be pressed relatively becomes large.
To solve the above-described problem in the blade dicing method, in recent years, the same applicant as that of the present application has proposed a method, which comprises: processing a plate-like glass mother material in a predetermined manner; applying a local compression to the glass mother material; and cutting the glass mother material by a generated tensile stress to obtain materials to be pressed having predetermined shapes (hereinafter referred to as “the local compression cutting method”) (see the publication of Japanese Patent Application Laid-Open No. 189424/1998).
When the materials to be pressed are obtained by the local compression cutting method described in the publication, first the plate (flat) glass mother material is prepared in which one main surface is processed to enlarge the local compression (specifically, a groove is formed), and on the other main surface, a notch is formed opposite to the place processed to enlarge the local compression. Subsequently, the glass mother material is laid on a positioning member (corresponding to “the auxiliary cutting member” in the present specification) so that the main surface with the notch formed therein faces inward (downward). Under this state the local compression is applied to the place processed to enlarge the local compression, and the glass mother material is cut by tensile stresses generated on both sides of the notched portion when the local compression is applied, to obtain the materials to be pressed having desired shapes.
When the materials to be pressed are prepared by the local compression cutting method described in the Japanese Patent Application Laid-Open No. 189424/1998, the above-described problem in the blade dicing method can be eliminated or improved. When the glass mother material is obtained, however, the processing to enlarge the local compression has to be applied. Therefore, the number of manufacture processes to obtain the glass mother material is increased, and additionally a metal die (molding die) for applying the processing is required. As a result, manufacture cost is relatively raised.
Moreover in general, the materials to be pressed for use in the reheat press method are obtained by cutting the plate glass mother material, and as one cutting method, there is a method of using an ultra-hard wheel cutter to scribe the main surface of the plate glass mother material beforehand.
FIG. 1
is a side sectional view showing a method of scribing the plate glass mother material. Moreover,
FIG. 2
is a view as seen from the front side of the cutter of the scribing method. Furthermore,
FIG. 3
is a view showing a concrete shape of a groove formed in the plate glass mother material. In this method, an ultra-hard wheel cutter
51
having a blade tip angle &thgr;
1
advances on a main surface
50
a
of a plate glass mother material
50
in an arrow direction of
FIG. 10
, to form a linear groove
52
. When the groove
52
is formed, cracks are generated. The cracks include a vertical crack
53
vertical to the main surface
50
a,
and horizontal cracks
54
,
55
substantially parallel with the main surface
50
a.
Moreover, a surface crack
56
is also generated as shown in FIG.
3
.
After the groove
52
is formed, the plate glass mother material
50
is laid on a mounting base so that the main surface
50
a
with the vertical crack
53
formed therein faces downward, and a predetermined load is applied to a position opposite to the vertical crack
53
on the side of an opposite main surface
50
b.
Thereby, the vertical crack
53
grows, and tensile stresses F
1
of the vertical crack
53
also help to cut the plate glass mother material
50
.
Additionally, when the glass type and shape of the plate glas

Affiliated with

Also associated with

Rating

Cutting method for plate glass mother material does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Cutting method for plate glass mother material, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cutting method for plate glass mother material will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2919524