Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2002-09-26
2004-04-13
Lam, Thanh (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S232000, C310S236000, C029S597000
Reexamination Certificate
active
06720701
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
Pursuant to 35 USC §119, this application claims the benefit of Japan Patent Application No. 2001-293063 filed Sep. 26, 2001.
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a commutator, an apparatus for manufacturing a commutator, and a commutator.
In general, a commutator has an approximately cylindrical insulator made of a resin and commutator pieces provided on the outer surface of the insulator. In a manufacturing method for a commutator, first, a cylinder is formed of a flat plate member and a molten resin is poured into the cavity of the cylinder. After the resin is cured, the cylinder is segmented at equiangular distances. The individual segments of the cylinder become commutator pieces and the cured resin becomes an insulator.
A plurality of projections (which correspond in number to the commutator pieces) extending in parallel to one another are formed, beforehand, at predetermined intervals on the surface of the flat plate member that is used to form the cylinder. Each projection has an extending portion which extends in a direction perpendicular to the lengthwise direction of the projection. When the cylinder is formed of the flat plate member, the individual extending portions are arranged on the inner surface of the cylinder. As each extending portion is engaged with the cured resin, each commutator piece obtained by segmenting the cylinder is prevented from being separated from the insulator.
In case of manufacturing a flat plate member for forming the aforementioned cylinder, as shown in
FIG. 13
, a plate member
52
which has projections
51
, equal in number to commutator pieces, formed at predetermined intervals in such a way as to extend in parallel to one another is prepared first. The length of the plate member
52
in a direction perpendicular to the surface of the sheet of
FIG. 13
is a predetermined integer multiple of the axial length of a single commutator in order to form a plurality of commutators (cylinders) from a single plate member
52
. Next, a punch
54
is pressed against the plate member
52
placed on a mold
53
and a portion
52
a
of the plate member
52
is punched out of the plate member
52
, as shown in FIG.
14
. Thereafter, the punched-out portion
52
a
is segmented into plural segments each of which becomes a plate member for forming a commutator (cylinder).
The above-described manufacturing method provides a plate member for forming a plurality of commutators from a single plate member
52
. This facilitates, for example, the handling of in the intermediate process (the stage before segmentation of the plate member
52
) and management of parts, and can permit processing of a plate member for forming a plurality of commutators at a time. This can lead to reduction in manufacturing cost. Such a commutator manufacturing method is disclosed in, for example, Japanese Unexamined Patent Publication No. 2001-245456.
In the manufacturing method, the shape of the punch
54
is flat (see FIGS.
13
and
14
), so that at the time of executing the punching step, the end portions of projections
51
on an end face
52
b
of the plate member
52
are smashed in the widthwise direction of the plate member
52
, yielding a plurality of burrs
55
or die wears
56
, as shown in FIG.
15
. As the burrs
55
enter between the plate member
52
and the mold at the time of processing, punching marks are left on the surface of each commutator piece, resulting in improper contact with the brush or generation of noise. The die wears
56
make the thickness of the plate member
52
uneven. Those would bring about improper working in later processing (e.g., improper formation of the extending portions), resulting in the improper outer shape of the commutator or the separation of the commutator pieces from the insulator.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the invention to provide a method of manufacturing a commutator, an apparatus for manufacturing a commutator, and a commutator, which can suppress the production of burrs or die wearing.
To achieve the object, according to one aspect of the invention, there is provided the following method of manufacturing a commutator. The method includes the steps of punching a commutator forming plate out of a plate member having a plurality of projections formed at predetermined intervals in such a way as to extend in parallel to one another, forming the commutator forming plate cylindrical and arranging the projections on an inner surface of the cylindrical commutator forming plate, filling an interior of the cylindrical commutator forming plate with a molten resin, segmenting the cylindrical commutator forming plate at predetermined angular distances after curing of the resin to thereby form commutator pieces, and positioning the plate member in a mold. The step of punching the commutator forming plate is carried out using a first punch having a plurality of recesses corresponding to the projections. Narrow portions are formed at those portions of each recess which correspond to both corner portions of the corresponding projection in such a way as to become narrower in a depth direction of that recess.
The invention further provides the following apparatus for manufacturing commutator. The apparatus punches a commutator forming plate of a predetermined length out of a plate member having a plurality of projections formed at predetermined intervals in such a way as to extend in parallel to one another by using a first punch. The first punch has a plurality of recesses corresponding to the projections. The commutator forming plate is formed cylindrical in such a way that the projections are arranged on an inner surface of the cylindrical commutator forming plate. The interior of the cylindrical commutator forming plate is filled with a molten resin. The cylindrical commutator forming plate is segmented at predetermined angular distances after curing of the resin to thereby form commutator pieces. The first punch has narrow portions each formed at those portions of each recess which correspond to both corner portions of the corresponding projection in such a way as to become narrower in a depth direction of that recess.
Furthermore, the invention provides the following method of manufacturing a commutator forming plate. The method comprises the steps of preparing a plate member having a plurality of projections formed at predetermined intervals in such a way as to extend in parallel to one another; and punching a commutator forming plate of a predetermined length out of the plate member using a first punch having a plurality of recesses corresponding to the projections and narrow portions each formed at those portions of each recess which correspond to both corner portions of the corresponding projection in such a way as to become narrower in a depth direction of that recess.
Moreover, the invention provides the following apparatus for manufacturing commutator forming plate. The apparatus punches a commutator forming plate out of a plate member having a plurality of projections formed at predetermined intervals in such a way as to extend in parallel to one another by using a first punch. The first punch has a plurality of recesses corresponding to the projections. Narrow portions are formed at those portions of each recess which correspond to both corner portions of the corresponding projection in such a way as to become narrower in a depth direction of that recess.
Further, the invention provides the following commutator forming plate. The commutator forming plate is used to form a commutator. The commutator forming plate has a plurality of projections formed at predetermined intervals in such a way as to extend in parallel to one another. Each projection has an extending portion extending in a direction perpendicular to a lengthwise direction of that projection. A plurality of commutator pieces are acquired by segmenting the commutator forming plate into a plurality of sections along the lengthwise direction of
Kanno Kazunobu
Terada Yuichi
Asmo Co. Ltd.
Lam Thanh
LandOfFree
Method of manufacturing commutator, apparatus for... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of manufacturing commutator, apparatus for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of manufacturing commutator, apparatus for... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3216390