Handling: hand and hoist-line implements – Utilizing fluid pressure – Venturi effect
Reexamination Certificate
1999-07-22
2001-10-23
Underwood, Donald W. (Department: 3652)
Handling: hand and hoist-line implements
Utilizing fluid pressure
Venturi effect
C414S752100, C901S040000
Reexamination Certificate
active
06305729
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Art
This invention relates generally to fabrication by press-molding of precision optical glass elements such as optical glass lenses or the like, and more particularly to a transfer mechanism for transferring work pieces of optical glass material each having curved surfaces on the opposite sides, accurately from a work container like a pallet to a predetermined position on a mold assembly unit to be used in press-molding.
2. Prior Art
For fabrication of precision optical glass elements like lenses, for example, press-molding processes are increasingly resorted to more than ever. Generally, an optical glass press-molding apparatus has a construction as shown in FIG.
12
. In that figure, indicated at
1
is a mold assembly unit, at
2
a
is an upper pressing member, and at
2
b
a lower pressing member. In this case, upper and lower pressing members
2
a
and
2
b
constitute a press means. The mold assembly unit
1
is largely composed of an upper mold member
3
, a lower mold member
4
and a girdler shell
5
. Normally, the lower mold member
4
is fixedly assembled into the girdler shell
5
, while the upper mold member
3
is movable toward and away from the lower mold member
4
under the guidance of the girdler shell
5
.
In a preparatory stage prior to press-molding, the upper mold member is
3
is once separated from the lower mold member
4
, and, after setting optical glass material
6
on a glass shaping surface
4
a
of the lower mold
4
, the upper mold member
3
is closed again on the lower mold
4
. Nextly, the mold assembly
1
as a whole is heated by the use of heating means
7
to soften the glass material
6
, and at the same time the upper and lower molds
3
and
4
are pressed toward each other by the upper and lower pressing members
2
a
and
2
b.
As a consequence, the optical glass material
6
in the mold
1
is pressed to shape to produce an optical glass element
6
which have predetermined surface characteristics copied from glass molding surfaces
3
a
and
4
a
of the upper and lower mold members
3
and
4
.
In order to carry out the lens molding operation automatically, for instance, a lens molding apparatus basically of the above-described construction can be incorporated into an automatic lens molding line in the manner as shown schematically in FIG.
13
. In that figure, indicated at
10
is a molding chamber which is equipped with a heating system
7
along with upper and lower pressing members
2
a
and
2
b.
Indicated at
11
is an entrance/exit way or station through which a mold assembly unit
1
with optical glass material
6
is loaded into the molding chamber
10
or to which a mold assembly unit
1
with a molded glass product is delivered from the molding chamber
10
after press-molding therein. Indicated at
12
is an upper mold assembling/dissembling station, at
13
a work loading/unloading station. At the work loading/unloading station, optical glass material
6
is placed on a lower mold member
4
, or an optical lens element which has been fabricated by press-molding is ejected from a lower mold. Accordingly, at the upper mold assembling/dissembling station
12
, an upper mold member
3
is removed from a mold assembly unit
1
on the way to the loading/unloading station
13
. Conversely, an upper mold member is set on a mold assembly unit
1
which arrives from the loading/unloading station
13
. The mold assembly unit
1
is supported on a suitable transfer jig and thereby transferred horizontally to and from the above-mentioned stations.
First of all, a work loading pallet in the form of a container which is arranged to hold a large number of pieces of the optical glass material
6
is located at the loading/unloading station
13
along with a work unloading pallet or a jig which is arranged to hold pieces of molded lens product thereon. Besides, for automatic loading and unloading operations, a robot with a suction arm is provided at the work loading/unloading station to transfer pieces of optical glass material
6
onto the loading pallet and to pick up a molded lens product
8
from a mold assembly unit
1
. This is the main reason why an upper mold member is put on or off at the upper mold assembling/dissembling station. An upper mold member
3
is picked up and retained on a holder member at the upper mold assembling/dissembling station
12
, and a lower mold assembly consisting of a lower mold member
4
and a girdler shell
5
is sent to the loading/unloading station
13
with a molding surface
4
a
faced upward in an open state. As soon as optical glass material
6
is placed in the lower mold
4
, the lower mold assembly is transferred to the upper mold assembling/dissembling station to receive an upper mold member
3
into the girdler shell
5
. Then, the mold assembly unit
1
is sent into the molding chamber
10
through the entrance/exit way
11
, and, while being softened under heating by the heating mechanism
7
, the optical glass material
6
is pressed to shape by the press means.
Upon finishing the press-molding of a lens element within the molding chamber
10
, the mold assembly unit
1
is transferred to the entrance/exit way
11
and then to the upper mold assembling/dissembling station
12
to remove the upper mold member
3
off the lower mold
4
and out of the girdler shell
5
. The lower mold assembly, with a molded lens element
8
on the opened molding surface
4
a
of the lower mold
4
, is further transferred to the work loading/unloading station where the molded optical lens product on the lower mold
4
is ejected therefrom and replaced by fresh optical glass material
6
. These operations are repeated to mold optical lens elements automatically and continuously.
In this connection, the shape of optical glass material is determined in relation with the shape of optical lens elements of the end product. For example, in the case of an optical lens product with a large radius of curvature, the optical glass material can be spherical or nearly spherical in shape. However, in the case of an optical lens product with a small radius of curvature, individual work pieces of optical glass material should be of a somewhat flattened shape having curved surfaces of a predetermined radius of curvature instead of surfaces of spherical shape. At the time of press-forming optical glass material having such flattened curved surfaces, a center O
1
of curvature on a front side
6
a
of glass material
6
as well as a center of curvature O
2
on a rear side
6
b
of the glass material should be positioned exactly on an axis A which connects the centers of curvature O
3
and O
4
of molding surfaces
3
a
and
4
a
of the upper and lower molds
3
and
4
as shown in FIG.
14
. If the centers of curvature O
1
and O
2
on the front and rear sides of the optical glass material is deviated from the axis A, pressure is non-uniformly applied to the glass material in the pressing stage to produce a lens element which is distorted in optical characteristics.
In the work loading stage, the optical glass material
6
is picked up from a pallet by a robot with a suction gripper means or the like and set on the shaping surface
4
a
of the lower mold
4
. At the time when the optical glass material
6
is released from the suction gripper, compressed air is usually blasted on the glass material in order to transfer same onto the lower mold
4
positively or in a forced way. Therefore, positional deviations may occur to the optical glass material
6
when it is transferred in this manner, more particularly, when it is picked up and also when it is set on the lower mold
4
. Especially, since the lower mold
4
is circumvented by the girdler shell
5
, the pressure of compressed air which is used to blow the optical glass material off the suction gripper means can find no way to escape and acts on the optical glass material directly and repeatedly to cause positional deviations to the latter, shifting the centers of curvatures O
1
and O
2
on the front and rear surfaces o
Fuji Photo Optical Co., Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Underwood Donald W.
LandOfFree
Apparatus for transferring pieces of optical glass 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 Apparatus for transferring pieces of optical glass material, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for transferring pieces of optical glass material will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2607524