Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – To produce composite – plural part or multilayered article
Reexamination Certificate
2000-07-20
2001-04-17
Ortiz, Angela (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
To produce composite, plural part or multilayered article
C264S261000, C425S123000, C425S577000
Reexamination Certificate
active
06217810
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a method of manufacturing a gear case having two support cylinders inclined relative to each other.
A brush cutter includes a drive shaft driven by an engine and a rotary shaft inclined relative to the drive shaft. The rotary shaft is coupled to a joint shaft through bevel gears in a gear case connected to an elongated cylinder in which is mounted the drive shaft. The joint shaft is coupled to the driven shaft. Thus, torque is transmitted from the engine to the rotary shaft through the drive shaft, joint shaft and bevel gears.
Since the drive shaft and the rotary shaft are inclined relative to each other, they are inserted in and supported by two support cylinders of the gear case, which are inclined at the same angle as the inclination angle between the drive shaft and the rotary shaft. The joint shaft is rotatably supported by a single bearing or a combination bearing mounted on the inner wall of one of the support cylinders. The rotary shaft is rotatably supported by two bearings mounted on the inner wall of the other support cylinder so as to be axially spaced from each other.
In this arrangement, if the two bearings for supporting the rotary shaft are not precisely aligned with each other when pressed into the support cylinder, it would be difficult to press the rotary shaft into the bearings. Also, if the inclination angle between the axis of the single bearing mounted in one of the support cylinders and the axis of the two bearings mounted in the other support cylinder is inaccurate, the bevel gears mounted to the joint shaft and the rotary shaft tend to mesh incompletely. This makes it difficult to smoothly transmit torque from the joint shaft to the rotary shaft. Also, the bevel gears would produce rattling sound.
Thus, it is required to mount the bearings with high accuracy. In order to mount the bearings with high accuracy, it is necessary to finish the inner surfaces of the support cylinders by turning with high accuracy. But machining the inner surfaces of cylindrical objects with high accuracy is troublesome and time-consuming.
An object of the invention is to provide a method of easily manufacturing a gear case which has little error in the inclination angle.
SUMMARY OF THE INVENTION
According to the present invention, there is provided a method of manufacturing a gear case comprising a first support cylinder and a second support cylinder inclined relative to the first support cylinder, the method comprising the steps of:
arranging a fixed mold and a movable mold such that the movable mold is movable between an open position and a closed position in which a cavity is defined between the fixed mold and the movable mold, the cavity comprising a first portion in which the first support cylinder is molded and a second portion in which the second support cylinder is molded, the second portion protruding obliquely from the first portion;
supporting a first slide core having a protrusion for forming the inner periphery of the first support cylinder, a second slide core having pins, and a third slide core having a protrusion for forming the inner periphery of the second support cylinder so as to be slidable relative to the movable core such that when the movable mold is moved to the closed position, the protrusion of the first slide core is fully inserted into the first portion of the cavity from one end thereof, the pins of the second slide core are fully inserted into the first portion from the other end thereof to abut the end of the protrusion of the first slide core, and the protrusion of the third slide core is fully inserted into the second portion of the cavity, thereby forming a space between the inner wall of the cavity and the protrusions of the first and third slide cores;
moving the movable mold to the open position;
forming aligned cylindrical first and second case-mounting surfaces on the outer periphery of the protrusion of the first slide core near its distal and proximate ends, respectively, the second case-mounting surface having a greater diameter than the first case-mounting surface;
forming a cylindrical third case-mounting surface on the outer periphery of the protrusion of the third slide core;
mounting a metallic cylindrical bearing case having a radially inwardly extending flange at one end thereof and a radially outwardly extending eccentric flange at the other end, on each of the first to third case-mounting surfaces such that the radially inwardly extending flange is located near the distal end of the respective protrusion;
moving the movable mold to the closed position; and
injecting under pressure a molten resin into the space.
REFERENCES:
patent: 3532402 (1970-10-01), Beery et al.
patent: 3893816 (1975-07-01), Payne
patent: 4423540 (1984-01-01), Hishida
patent: 5562372 (1996-10-01), Baima et al.
patent: 5584202 (1996-12-01), Kanamaru et al.
patent: 58-82071 (1983-05-01), None
patent: 7-214184 (1995-08-01), None
Ortiz Angela
Viv Engineering Inc.
Wenderoth , Lind & Ponack, L.L.P.
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