Electric heating – Metal heating – For bonding with pressure
Reexamination Certificate
1999-07-30
2001-06-26
Evans, Geoffrey S. (Department: 1725)
Electric heating
Metal heating
For bonding with pressure
Reexamination Certificate
active
06252193
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an X type electric welding machine comprising at least two gun arms each having electrodes at tip ends thereof which oppose each other wherein at least one gun arm is rotatably pivoted on a connection part (6) between the two gun arms, particularly to a rotating mechanism of the gun arms.
2. Description of Related Art
Conventionally, there has been an X type welding machine having first and second gun arms wherein the first gun arm is integrated with a gun bracket and the second gun arm is rotatably pivoted on the gun bracket so as to obtain a high electrode pressing force while restraining the capacity of the servomotor, and wherein the second gun arm presses against the first gun arm by a crank mechanism (pressing mechanism) composed of an output disc fixed to the output side of a reduction gear by way of a servomotor and the reduction gear, a pin provided at the outer periphery of the output disc, and a connector arm (link) provided so as to connect between the pin and the rear end of the second gun arm (see e.g., JP-A 9-248678).
However, in rotating means of the gun arms of the conventional X type electric welding machine, a pressing operation is performed at the position immediately before an angle formed between a line connecting between the center of the output disc by way of the reduction gear and the pin provided at the outer periphery of the output disc and a ring connecting between the rear end of the second gun arm and the pin becomes 180 degrees, thereby increasing the pressing force utilizing a so-called toggle mechanism.
Meanwhile, in such pressing means, the variation rate of the electrode pressing force relative to the variation of rotational angle of the output disc is large in view of the relation of the output of the link relative to rotational torque of the output disc, and further, the electrode pressing force is varied not linear functionally but exponential functionally as the angle set forth above approaches to 180 degrees so that the electrode pressing force is greatly varied by a slight variation of the angle formed between the pin and the link. In the practical use of a welding machine, the deflection of the gun arms is varied for every application force in addition to the variation of the wear of the electrode, and the wear of bearings for supporting pins including a main shaft so that it is difficult to obtain a stable angle. Accordingly, in view of a toggle mechanism where the pressing force is exponential functionally varied relative to the amount of variation of the rotational angle of the output disc, it is very difficult to control for obtaining an accurate electrode pressing force conforming to a set value of an electrode pressing force in the conventional X type electric welding machine.
SUMMARY OF THE INVENTION
The invention has been made in view of the problems of the conventional X type electric welding machine, and it is an object of the invention to provide an X type electric welding machine in which an electrode pressing force is not susceptible to the wear of electrodes or bearings, the variation of deflection of gun arms which varies for every electrode pressing force, an accurate electrode pressing force is outputted relative to an electrode pressing force which is set with an easy control mechanism or means, thereby obtaining a steady electrode pressing force.
To achieve the above object, an X type electric welding machine according to a first aspect of the invention comprises at least two gun arms each having electrodes at tip ends thereof which oppose each other, and gun arms being connected to each other at a connection part on which at least one gun arm is rotatably pivoted, a reduction gear being disposed separately from the connection part of the gun arms, and a motor being connected to the reduction gear, a power transmission mechanism provided at an output side of the reduction gear for rotating one of the gun arms, wherein said power transmission mechanism comprises a swing arm fixed to an output shaft of the reduction gear and a link formed between the swing arm and one of the gun arms, characterized in that the swing arm and the link are connected to each other in the manner that an output outputted from a shaft of the motor and an electrode pressing force applied to one of the electrodes which is transmitted to one of the electrodes from a tip end of the swing arm by way of the link have a substantially linear proportional relation.
An X type electric welding machine according to a second aspect of the invention comprises at least two gun arms each having electrodes at tip ends thereof which oppose each other, and gun arms being connected to each other at a connection part on which at least one gun arm is rotatably pivoted, a reduction gear being disposed separately from the connection part of the gun arms, and a motor being connected to the reduction gear, a power transmission mechanism provided at an output side of the reduction gear for rotating one of the gun arms, wherein said power transmission mechanism comprises a swing arm fixed to an output shaft of the reduction gear, a groove formed in the tip end of the swing arm and a roller provided on one of the gun arms and movable along the groove, characterized in that the roller provided on one of the gun arms is disposed to be movable in the groove provided in the tip end of the swing arm in the manner that an output outputted from a shaft of the motor and an electrode pressing force applied to one of the electrodes which is transmitted to one of the electrodes from a tip end of the swing arm by way of the roller have a substantially linear proportional relation.
An X type electric welding machine according to a third aspect of the invention comprises at least two gun arms each having electrodes at tip ends thereof which oppose each other, and gun arms being connected to each other at a connection part on which at least one gun arm is rotatably pivoted, a reduction gear being disposed separately from the connection part of the gun arms, and a motor being connected to the reduction gear, a power transmission mechanism provided at an output side of the reduction gear for rotating one of the gun arms, wherein said power transmission mechanism comprises a swing arm fixed to an output shaft of the reduction gear, a roller disposed in a groove formed in one of the gun arms and provided at the tip end of the swing arm, characterized in that the roller provided at the tip end of the swing arm is movable in the groove in the manner that an output outputted from a shaft of the motor and an electrode pressing force applied to one of the electrodes which is transmitted to one of the electrodes by way of the groove from the tip end of the swing arm have a substantially linear proportional relation.
An X type electric welding machine according to a fourth aspect of the invention comprises at least two gun arms each having electrodes at tip ends thereof which oppose each other, and gun arms being connected to each other at a connection part on which at least one gun arm is rotatably pivoted, a reduction gear being disposed separately from the connection part of the gun arms, and a motor being connected to the reduction gear, a power transmission mechanism provided at an output side of the reduction gear for rotating one of the gun arms, wherein said power transmission mechanism comprises a gear fixed to the output shaft of the reduction gear and a gear provided on one of the gun arms, characterized in that the gear fixed to the output shaft of the reduction gear and the gear provided on one of the gun arms mesh with each other in the manner that an output outputted from a shaft of the motor and an electrode pressing force applied to one of the electrodes which is transmitted to one of the electrodes from the gear fixed to the output shaft of the reduction gear by way of the gear provided on one of the gun arms.
REFERENCES:
patent: 5750953 (1998-05-01), Sato et al.
patent: 5928531 (1999-07-01), Sato
Evans Geoffrey S.
Flynn, Theil, Boutell & Tanis, P.C.
Obara Corporation
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