Metal working – Method of mechanical manufacture – Assembling or joining
Reexamination Certificate
2001-09-26
2002-08-27
Bryant, David P. (Department: 3726)
Metal working
Method of mechanical manufacture
Assembling or joining
C264S219000
Reexamination Certificate
active
06438816
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates generally to a mold for molding resinous domed articles which may be employed as a cover for monitor cameras, and more particularly to a production method of the same.
2 Background Art
Typical monitor cameras employed in stores, banks, etc. are designed to monitor a preselected range across a fixed direction. Cameras of this type have a dead angle so great as not to cover a wide range. In order to avoid this problem, there have been developed monitor devices which turns or pans a single camera horizontally and tilts it vertically for monitoring a wider range. Such prior art monitor cameras are usually suspended from the ceiling and present an appearance persons perceive to be a camera easily, thus giving an unpleasant feeling to customers in the store. Recently, small-sized monitor cameras are, thus, proposed whose major part of the camera and tilt and pan mechanisms are covered with a resinous dome.
FIG. 4
shows such a dome-shaped monitor camera which includes a camera body
1
, a mount ring
2
, a transparent domed cover
3
, an inner cover
4
, a camera lens
5
, a power supply cable
6
, and an output coaxial cable
7
. The inner cover
4
is disposed within the domed cover
3
and made from an opaque or a translucent material. The inner cover
4
has formed therein an opening
4
a
through which the camera lens
5
faces the outside. The power supply cable
6
supplied the power to the camera body
1
, a tilt mechanism, and a pan mechanism. The output cable
7
outputs image signals and receives control signals. The domed cover
3
is made from acrylate resin in injection molding and required to have smooth surfaces and a constant thickness for ensuring a given degree of quality of captured images. The domed cover
3
is also required to have substantially a hemispherical surface for vertical and horizontal movements of the camera body
5
over 90° and 360° ranges, respectively.
FIG. 5
shows a conventional mold for forming the domed cover
3
shown in FIG.
4
. The mold consists of an upper block
8
(i.e., a female molding block) and a lower block
9
(i.e., a male molding block). The upper block
8
has formed therein a cavity
10
which consists of a hemispherical wall
10
a
and an annular wall
10
b
extending straight from an end of the hemispherical wall
10
a.
The formation of the cavity
10
of the upper block
8
is achieved by rotating the upper block
8
about a vertical axis V passing through the center O of a semicircle having the same radius of curvature as that of the hemispherical wall
10
and rotating and moving a grindstone, which has a surface curved outward with the same radius of curvature as that of the hemispherical wall
10
a,
from the top to an end of the semicircle. The annular wall
10
b
of the upper block
8
is grounded by moving the grindstone parallel to the vertical axis V. A hemispherical portion
9
a
of the lower block
9
may be grounded in substantially the same manner as that of forming the cavity
10
, but formation of an annular wall
9
b
extending straight from an end of the hemispherical portion
9
a
requires interruption of the grinding and replacement of the grindstone used in forming the hemispherical portion
9
a
with another one having a flat grinding surface. This is because a corner between the annular wall
9
b
and a flat upper wall
9
c
needs to be formed at right angles. The replacement of the grindstone may result in an error in forming a curved outer surface near an end of the hemispherical portion
9
a
, thereby causing irregularities to be formed on an interface between the hemispherical portion
9
a
and the annular wall
9
b
, which will lead to formation of similar irregularities on an inner surface of the domed cover
3
near its end, thereby contributing to distortion of part of images captured by the monitor camera.
SUMMARY OF THE INVENTION
It is therefore a principal object of the present invention to avoid the disadvantages of the prior art.
It is another object of the present invention to provide a resinous dome-forming mold having smooth surfaces which do not form irregularities on the surfaces of molded articles.
According to one aspect of the invention, there is provided a mold for forming a resinous domed article including a hollow hemispherical portion and a hollow cylindrical portion continuing from an end of the hollow hemispherical portion. The mold comprises: (a) a female block having formed therein a domed mold cavity which includes a hemispherical wall that is just half a sphere and an annular wall extending from an end of the hemispherical wall; and (b) a male block having a domed protrusion mating with the domed mold cavity of the female block. The domed protrusion includes a hemispherical portion and a cylindrical portion which is joined to the hemispherical portion.
According to the second aspect of the invention, there is provided a method of producing a male block of a resinous dome-forming mold. The male block has a dome-shaped protrusion which includes a hemispherical section that is just half a sphere and a cylindrical section continuing from an end of the hemispherical section. The method comprises the steps of: (a) preparing a spherical block having a spherical surface ranging over at least more than half a sphere; (b) rotating the spherical block around an axis passing through the center of the spherical block; (c) grinding an area of the spherical surface of the spherical block ranging over more than 180° from a top of the spherical surface through which the axis of rotation passes to a circumference thereof using a grindstone with a curved surface having substantially the same radius of curvature as that the hemispherical section of the male block; (d) cutting off a grounded portion of the spherical block to complete the hemispherical section of the male block; (e) preparing a block on which the cylindrical section of the male block is formed; and (f) joining the cylindrical section to the hemispherical section to complete the male block.
According to the third aspect of the invention, there is provided a method of producing a male block of a resinous dome-forming mold. The male block has a dome-shaped protrusion which includes a hemispherical section that is just half a sphere and a cylindrical section continuing from an end of the hemispherical section. The method comprises the steps of: (a) preparing a spherical block including a hemispherical portion that is just half a sphere and a base portion connected to the hemispherical portion to form a spherical surface ranging over more than 180° of the sphere; (b) rotating the spherical block around an axis passing through the center of the spherical block; (c) grinding an area of the spherical surface of the spherical block ranging over more than 180° from a top of the spherical surface through which the axis of rotation passes to a circumference thereof using a grindstone with a curved surface having substantially the same radius of curvature as that the hemispherical section of the male block; (d) separating the hemispherical portion from the spherical block to complete the hemispherical section of the male block; (e) preparing a block on which the cylindrical section of the male block is formed; and (f) joining the cylindrical section to the hemispherical section to complete the male block.
REFERENCES:
patent: 1294486 (1919-02-01), Kuen
patent: 1588435 (1926-06-01), Adams
patent: 1994529 (1935-03-01), Meyer
patent: 2151233 (1939-03-01), Rowe
patent: 2388776 (1945-11-01), Wallace
patent: 2836939 (1958-06-01), White
patent: 2985057 (1961-05-01), Stanhope
patent: 3079739 (1963-03-01), Rawstron
patent: 3167884 (1965-02-01), Thompson
patent: 3543380 (1970-12-01), Hagopian
patent: 3590448 (1971-07-01), Bryant
patent: 3830021 (1974-08-01), Blum et al.
patent: 3835528 (1974-09-01), Garrett
patent: 3867078 (1975-02-01), Porter
patent: 3871813 (1975-03-01), Cappeli
patent: 3877184 (1975-04-01), Billault et al.
patent: 4077576 (1978-03-
Tamura Kazushige
Wada Jyoji
Bryant David P.
Jimenez Marc
Matsushita Electric - Industrial Co., Ltd.
Woo Louis
LandOfFree
Mold for forming resinous domed article and method of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Mold for forming resinous domed article and method of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Mold for forming resinous domed article and method of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2955948