Metal deforming – By deflecting successively-presented portions of work during... – To form spiral coil
Reexamination Certificate
1999-01-27
2001-04-17
Hall, Carl E. (Department: 3729)
Metal deforming
By deflecting successively-presented portions of work during...
To form spiral coil
C029S605000, C072S224000
Reexamination Certificate
active
06216513
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the invention
The present invention generally relates to an apparatus and process for manufacturing a rectangular-wire coil, and more particularly to an apparatus and simple process for manufacturing a rectangular-wire coil simply at a low cost.
2. Description of the Related Art
Development of electric and hybrid cars has been emphasized as one way to address the need to reduce particle and noise pollution. Development of high-performance motor to be mounted on such a car mentioned above has also proceeded. As coils for such motors, those using circular cross-section enameled wire and those using rectangular enameled wire are both well known.
The circular cross-section enameled wire provides an advantage of that a raw material of wire is low-cost on one hand but has a disadvantage of that the fill factor of a motor is limited, the fill factor of a motor being the ratio of “a sum total of cross-sectional areas of all the coil wire in a slot” to “a cross-sectional area of a slot in a motor body”. Motor performance should increase as is increased motor fill factor.
Rectangular enameled wire is enameled wire which has a rectangular cross sectional shape. Using the rectangular enameled wire reduces the clearance between enameled wire in a slot of a motor, so that it becomes possible to increase fill factor of a motor and improve motor performance. From a practical point of view, fill factor of the rectangular enameled wire is generally 70-80%, in contrast to that of the circular cross-section enameled wire which is 30-50%.
For example, an apparatus for manufacturing a coil, shown in Japanese Patent Laid-Open Publication No. Hei 7-183152, is comprised of a bobbin on which rectangular wire is wound, a reduction roll to correct torsion set of the rectangular wire, and a winding form to take up the corrected rectangular wire, wherein a coil is formed by winding the rectangular wire on the winding form.
By using a rectangular-wire coil as mentioned above, it becomes possible to improve the fill factor of a motor. However, this presents a problem that the cost of a motor becomes high since the cost of rectangular enameled wire that is a raw material of the rectangular-wire coil is high. The high cost of such wire mainly derives from factors such as its manufacturing process being more complicated than that of circular cross-section enameled wire, uniform coating of resin around wire shaped rectangular in cross section is difficult, or the like. The cost of rectangular enameled wire is now actually two or more times that of circular cross-section enameled wire.
Attempts have been made to prepare a bobbin wound by the rectangular wire and form a coil using the rectangular wire pulled out of the bobbin as shown in above-mentioned Japanese Patent Laid-Open Publication No. Hei 7-183152. Torsion set, however, appears when the rectangular wire is wound on the bobbin. The remaining torsion set causes the shape of the completed coil to be less accurate, sets torsion on the rectangular wire, and creates clearance between the rectangular wire. It is therefore necessary to provide a reduction roll for removing the torsion set in the art described above. Such construction complicates the manufacturing process and apparatus and causes to motor cost to increase.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a simple and low-cost method and apparatus for manufacturing a rectangular-wire coil which does not require correcting torsion set of the rectangular wire.
It is a further object of the invention to provide an apparatus capable of manufacturing coils of one or more types, differing in cross-sectional shapes of the rectangular wire to be wound, through a single apparatus and thereby further improve productivity.
(1) An apparatus for manufacturing a rectangular-wire coil of this invention comprises feeding means for supplying material wire, rectangular forming means whereby the material wire provided through said feeding means is deformed to form rectangular wire shaped rectangular in cross section, and coil forming means whereby said rectangular wire is wound on a winding form to form a rectangular-wire coil; and wherein forming rectangular wire and winding on said winding form are performed in a sequence of contiguous processes.
Wire used as a raw material for manufacturing a coil of this invention may be an inexpensive conductor of circular or other cross sectional shape. A process to form rectangular wire from the material wire and a process to take up the rectangular wire on a winding form and form a coil are executed in a sequence of contiguous processes. Since the occurrence of torsion set caused by taking up the rectangular wire to a bobbin is thereby prevented, an apparatus process for removing such torsion set may be excluded. The material wire has torsion set, but this torsion set is spontaneously removed in the process to form the rectangular wire through deforming the material wire. Thus, this invention allows a rectangular-wire coil to be manufactured through a simple and low-cost apparatus using a low-cost wire as raw material. Consequently, it becomes possible to provide a high-performance motor at a low cost.
In addition, it is preferable to cover material wire beforehand with an insulation resin (enamel and so on) of which elasticity is high. As a result of this, uniform insulating coating is spontaneously deposited on a circumference of the finished rectangular wire when it is formed from material wire. In this regard, this invention allows rectangular-wire coil to be manufactured simply and at low cost.
(2) It may be preferable for said rectangular forming means to include rectangular forming rollers for deforming material wire plastically and for said coil forming means to include a winding-form motor for rotating said winding form. By rotating said winding form using the turning force generated by said winding-form motor, the rectangular wire is pulled so as to provide rectangular wire with the tension required to remove the material wire from the rectangular forming rollers as well and to wind the rectangular wire on said winding form. According to this aspect, turning force of the winding-form motor works to form the rectangular wire and to form a coil. An apparatus for manufacturing a coil may thereby be simplified.
(3) An apparatus for manufacturing a rectangular-wire coil in an aspect of this invention may comprise winding-form motor control means for controlling said winding-form motor in order to vary a rotational speed of the motor according to a rotation angle of said winding form. When the rectangular wire, for example, is wound on a flexion portion of the winding form, reliable forming of the flexion portion is necessary. Therefore, the winding-form motor preferably reduces speed at that point. When the rectangular wire is wound on a flat portion of the winding form, the coil is reliably formed, compared with the time of winding to the flexion portion, even though the winding-form motor increases speed. According to this aspect, the control corresponding to each rotation angle thus allows rotational speed of motor to increase while maintaining reliability of coil formation, and therefore enables coil manufacturing speed to increase.
(4) In another aspect of the present invention, said feeding means includes a rotatable material wire reel on which said material wire is wound, and back tension producing means to prevent an occurrence of sag by imparting back tension to a part of the material wire between said material wire reel and said rectangular forming rollers. In this aspect, said back tension producing means imparts back tension, based on a difference between a rotational speed of said winding form and that of said material wire reel, to the material wire and changes said back tension according to a rotational speed of said winding-form motor and in conjunction with said winding-form motor control means.
When material wire is pressed through the rectangular forming rollers, the raw wire stretch
Endo Katsuhisa
Ishimaru Yasuhiko
Kawabata Yasutomo
Miura Tetsuya
Nakamura Masayuki
Hall Carl E.
Oliff & Berridg,e PLC
Toyota Jidosha & Kabushiki Kaisha
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