Glass manufacturing – Processes – Reshaping or surface deformation of glass preform
Reexamination Certificate
2001-07-19
2004-04-27
Walls, Dionne A. (Department: 1731)
Glass manufacturing
Processes
Reshaping or surface deformation of glass preform
C065S102000
Reexamination Certificate
active
06725689
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus and method for bend-shaping a glass sheet into a bi-directionally curved shape.
2. Description of the Prior Art
Many glass sheets for use as automobile side windows are bent in only one direction (hereinafter referred to as “single-curved glass sheet”). Such glass sheets are known from, for example, Japanese Patent Publication No. SHO-43-11768 entitled “METHOD OF TRANSFERRING HEAT BETWEEN A GLASS SHEET AND GASES FLOWING IN CONTACT WITH THE SHEET” (corresponding to U.S. Pat. No. 3,332,759 and U.S. Pat. No. 3,332,760).
For design reasons, such side window glass sheets are often required to be bent in two directions, namely, a first direction and a second direction normal to the first direction (hereinafter referred to as dual-curved glass sheet and often as “complexly-curved glass sheet”). An apparatus for bend-shaping such a complexly-curved glass sheet is proposed in, for example, Japanese Patent Laid-Open Publication No. HEI-5-009037 “METHOD AND APPARATUS FOR BEND-SHAPING A GLASS SHEET” (corresponding to U.S. Pat. No. 6,014,873). An overall arrangement of the proposed apparatus is schematically illustrated in
FIG. 15
hereof.
As shown in
FIG. 15
, the proposed apparatus includes a heating furnace
150
having an array of beds
151
(only one shown) positioned therein. Air is jetted from upper surfaces
151
a
of the beds
151
to floatingly support a glass sheet
153
for successively transferring, via a transfer means not shown, the glass sheet
153
over the upper surfaces
151
a
of the beds
151
in an arrowed direction.
Toward an outlet
150
a
of the heating furnace
150
, the upper surfaces
151
a
of the beds
151
gradually become curved in a transverse direction (normal to a direction of transfer of the glass sheet
153
) so that they have an upwardly convex shape. Thus, as the glass sheet
153
is transferred over the upper surfaces
151
a
in the arrowed direction, the glass sheet is gradually bent by its own weight (self-sagging) into a shape complementary with the shape of the beds
151
to thereby provide a single-curved glass sheet.
After arrival at a position proximate to the outlet
150
a
of the heating furnace
150
, the single-curved glass sheet
153
advances inclinedly upwardly over beds
155
,
156
disposed within the heating furnace (hereinafter called “in-furnace beds”) in an upwardly inclined fashion. These beds
155
,
156
have respective upper surfaces
155
a
,
156
a
curved not only in a transverse direction but also in the direction of transfer of the glass sheet. Thus, transfer of the single-curved glass sheet
153
over those beds
155
,
156
causes the glass sheet
153
to become a complexly-curved glass sheet which is bent in both transverse and transfer directions of the glass sheet
153
.
Continuously, the complexly-curved glass sheet
153
is transferred to a cooling bed
160
positioned proximately to and externally of the outlet
150
a
of the heating furnace
150
(hereinafter called “out-furnace bed”), where, while being supported by air jetted from an upper surface
160
a
of the out-furnace bed
160
in a floated fashion, the complexly-curved glass sheet
153
is cooled by cooling air jetted from cooling means
162
positioned upwardly of the glass sheet
153
.
Reference is made next to
FIG. 16
illustrating a conventional in-furnace bed on an enlarged scale.
Upper surface
156
a
of the in-furnace bed
156
is curved both in a direction of its width W and in a direction of its length L. The upper surface
156
a
of the in-furnace bed
156
has a multiplicity of air jet holes
157
. Air is jetted from the air jet holes
157
to floatingly support the single-curved glass sheet
153
over the upper surface
156
a
, whereupon the glass sheet
153
is bent also in the direction of transfer of the glass sheet to thereby provide the desired dual-curved glass sheet.
Similarly to the upper surface
156
a
of the in-furnace bed
156
, the upper surface
160
a
of the out-furnace bed
160
shown in
FIG. 15
is curved both in a transverse direction and in a direction of transfer of the glass sheet.
Apart from the publication just described, an apparatus for bend-shaping a glass sheet into a dual-curved shape is also disclosed in Japanese Patent Laid-Open Publication No. HEI-6-191867 (U.S. Pat. No. 5,522,912). In the apparatus of this publication, a final bed disposed in heating furnace is curved in a transverse direction but is linear in a direction of transfer of a glass sheet. The final bed has an upper surface of uphill shape, that is, uprising toward an outlet of the heating furnace. In contrast, a quenching bed disposed externally of the heating furnace has an upper surface of downhill shape. Upon transfer from the final bed onto the quenching bed, the glass sheet is formed into a dual-curved glass sheet.
Another method and apparatus for bend-shaping a glass sheet is disclosed in Japanese Patent Laid-Open Publication No. HEI-9-202633. This publication teaches jetting hot air downwardly and combining a downward force produced by the jetted hot air with the weight of a glass sheet being bent to thereby facilitate bending of the glass sheet. As a result, the time required for bending a glass sheet can be shortened. Further, the hot air is jetted downwardly through a gap between an inclined bed and a cooling bed to provide an air curtain which keeps cooling air away from the glass sheet to thereby maintain the glass sheet at its softening temperature.
It is costly to install two lines of manufacture, namely, one for manufacturing the single-curved glass sheet, as described above, and the other for manufacturing the dual-curved glass sheet, as also described above. If a single line of manufacture is made available for use in producing both the single-curved glass sheet and dual-curved glass sheet, this will achieve substantial cost reduction.
For example, the in-furnace beds
155
,
156
of the bend-shaping apparatus disclosed in Japanese Patent Laid-Open Publication No. HEI-5-009037, discussed with reference to
FIG. 15
, may be replaced with new beds
151
,
151
curved only in a transverse direction, while the out-furnace bed
160
may be replaced with a bed curved only in a transverse direction. This makes the bend-shaping apparatus available for use in manufacturing a single-curved glass sheet.
Thus, only the bend-shaping apparatus as shown in
FIG. 15
may be installed for manufacturing a single-curved glass sheet. When desired, relevant parts of the apparatus may be substituted by other parts to manufacture a dual-curved glass sheet. However, this involves tedious operations to switch the apparatus from one mode of operation to another by replacing the beds for manufacturing a single-curved glass sheet with the beds
155
,
156
for manufacturing a dual-curved glass sheet.
Further, upon changing the beds for manufacturing the single-curved glass sheet to the beds
155
,
156
for manufacturing the dual-curved glass sheet, it is necessary to lower the temperature of the heating furnace from about 700° C., (glass softening temperature) to an atmospheric temperature. In addition, after the beds for manufacturing the single-curved glass sheet to the beds
155
,
156
for manufacturing the dual-curved glass sheet, the temperature within the furnace
150
must be risen to about 700° C. again. Consequently, bed changing takes a relatively long time, thereby deteriorating productivity. Moreover, it is necessary to provide two different types of beds, namely, beds
155
,
156
,
160
for manufacturing the dual-curved glass sheet and beds for bending the glass sheet, thereby increasing the cost of glass sheet production.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an apparatus and a method for bend-shaping a glass sheet, which is capable of increasing productivity and reducing installation costs.
According to one aspect of the present invention, there is provided an apparatus for bend-shaping a gl
Honjo Seiichiro
Nagai Yasuyuki
Yabuno Takeshi
Merchant & Gould P.C.
Nippon Sheet Glass Co. Ltd.
Walls Dionne A.
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