Electric heating – Metal heating – For bonding with pressure
Reexamination Certificate
1999-12-22
2001-02-13
Shaw, Clifford C. (Department: 1725)
Electric heating
Metal heating
For bonding with pressure
C219S086250
Reexamination Certificate
active
06188038
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to resistance welders, and more particularly, to a device for removing an electrode tip fitted to a tapered shaft of a shank in a resistance welder.
2. Background of the Related Art
As related art devices of this kind, there are a device in which an expandable member or wedge is inserted by force between a shank and an electrode tip for separating the electrode tip from the shank, and a device in which fine impacts are applied to the electrode tip for pulling the electrode tip from the shank. (see Japanese Laid Open Patent No. 3-291175, and Japanese Laid Open Patent No. 4-9285) However, because devices using the expandable member or inserting the wedge by force require disposition of an expandable part or a wedge part between the electrode tip and the shank by inserting the expandable part or the wedge part through an entire length of the electrode tip, and further require provision of a device for holding the removed electrode tip in place near to a fore end of the electrode tip, which causes the portion of the device in the vicinity of the electrode tip to leave a tight space to the shank disposed above and below thereof, employment of a robot becomes difficult. And, the type of devices applying impact suffer from the inconvenience of generating noise as the impacts are applied to the electrode tip repeatedly.
SUMMARY OF THE INVENTION
In accordance with an aspect of the invention, a device is disclosed for removing an electrode tip from a shaft of a resistance welder by turning the electrode tip. The device comprises a holding member having a center of rotation. The holding member defines a first hole sized to receive the electrode tip. The device also includes a claw disposed adjacent the first hole and mounted for rotation between an engagement position wherein at least a portion of the claw is positioned within the first hole to secure the electrode tip within the first hole, and a disengagement position wherein the at least a portion of the claw is displaced from the first hole. Additionally, the device includes a turning plate having a center of rotation coincident with the center of rotation of the holding member. The turning plate defines a second hole at the center of rotation. The turning plate is structured to move the claw from the disengagement position to the engagement position to secure the electrode tip in the first hole when the turning plate rotates in a first direction and to move the claw from the engagement position to the disengagement position to release the electrode tip from the first hole when the turning plate rotates in a second direction opposite the first direction. The device further includes a brake operatively engaging the holding member to substantially secure the holding member against movement during at least a first phase of movement of the claw from the disengagement position toward the engagement position. The holding member turns with the turning plate in the first direction after completion of the first phase of movement to turn the electrode tip.
Preferably, the claw has an axis of rotation and the axis of rotation of the claw is substantially parallel to an axis of the first hole.
In some embodiments, the first phase ends when the claw enters the engagement position.
Preferably, the first and second holes are coincident with the centers of rotation of the turning plate and the holding member.
Preferably, the second hole is sized to receive a portion of the holding member, the holding member includes an end portion projecting from the turning plate, and the brake cooperates with the end portion to apply the braking force to the holding member. In some such embodiments, the brake comprises a pair of brake arms engaging an outer surface of the end portion of the holding member; and a spring biasing the brake arms into frictional engagement with the end portion.
In some embodiments, the first hole has an inner wall and an inner diameter, and the inner diameter is sized such that, when the claw is in the engagement position and engages the electrode tip, a side of the electrode tip frictionally engages a portion of the inner wall. In some such embodiments, grooves are formed in the portion of the inner wall. In some such embodiments, the device includes only one claw and the portion of the inner wall is located opposite the claw.
In some embodiments, the claw comprises at least three claws, and the claws are spaced around the first hole such that, when the claws enter their engagement positions, the electrode tip is secured between the claws.
Preferably, the device includes a motor operatively coupled to the turning plate for rotating the turning plate in at least one of the first and second directions. In some such embodiments, the turning plate includes gear teeth, and the motor is operatively coupled to the gear teeth of the turning plate via at least one intermediate gear.
Preferably, the first hole is positioned to receive the electrode tip from two directions.
In accordance with another aspect of the invention, a device is disclosed for removing an electrode tip from a shaft of a resistance welder by turning the electrode tip. The device includes a holding member defining a first hole. It also includes a claw disposed adjacent the first hole and mounted for rotation between an engagement position wherein at least a portion of the claw is positioned within the first hole to secure the electrode tip within the first hole, and a disengagement position wherein the at least a portion of the claw is displaced from the first hole. The device also includes a turning plate cooperating with the claw to move the claw from the disengagement position to the engagement position to secure the electrode tip in the first hole when the turning plate rotates in a first direction and to move the claw from the engagement position to the disengagement position to release the electrode tip from the first hole when the turning plate rotates in a second direction opposite the first direction. Additionally, the device includes a brake operatively engaging the holding member such that, during a first phase of operation, the holding member does not rotate and the turning plate moves the claw from the disengagement position toward the engagement position, and during a second phase of operation, the holding member rotates with the turning plate to rotate the electrode tip.
In accordance with another aspect of the invention, a method of removing an electrode tip from a shaft of a resistance welder by turning the electrode tip is provided. The method comprises the steps of; inserting the electrode tip into a bore defined in at least one of a turning plate and a holding member; rotating the turning plate in a first direction without rotating the holding member to thereby move at least one claw into engagement with the electrode tip to secure the tip within the bore; and subsequently rotating the turning plate and the holding member in the first direction while the at least one claw secures the electrode tip in the bore to thereby turn the tip.
Preferably, the method also comprises the step of rotating the turning plate and the holding member in a second direction opposite the first direction to release the electrode tip from the bore.
REFERENCES:
patent: 4794221 (1988-12-01), Takabe et al.
patent: 4935595 (1990-06-01), Fuse
patent: 5073692 (1991-12-01), Jackson et al.
patent: 5387774 (1995-02-01), Boyer et al.
patent: 5495663 (1996-03-01), Saito
patent: 5734141 (1998-03-01), Voilmy et al.
patent: 5767474 (1998-06-01), Shimada
patent: 6049053 (2000-04-01), Shimada
patent: 3-291175 (1991-12-01), None
patent: 4-9285 (1992-01-01), None
Kyokutoh Company
Marshall O'Toole Gerstein Murray & Borun
Shaw Clifford C.
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