Electric heating – Metal heating – For bonding with pressure
Reexamination Certificate
2002-07-12
2004-04-13
Kerns, Kevin P. (Department: 1725)
Electric heating
Metal heating
For bonding with pressure
Reexamination Certificate
active
06720517
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a resistance welding head, and a resistance welding apparatus and a resistance welding method, which use the resistance welding head.
2. Description of Related Art
In general, a wire harness for an automobile has adopted an electric connection box. The electric connection box contains wiring materials such as laminated bus bars or the like. The laminated bus bars constitute branch circuits in electric wiring. A plurality of bus bar blanks, which constitute electric circuits corresponding to a type of an automobile are formed by stamping a hoop material. Cutting and upset the bus bar blanks form tab terminals. The laminated bus bar is formed by interposing an insulation plate between the bus bars. The laminated bus bars are accommodated in a case.
A contact of the electric connection box is formed by welding the spots being welded between bus bars or by welding the spots being welded between the bus bar and electric wires by means of a spot welding apparatus.
Currently, circuits to be contained in the electric connection box are rapidly increasing in connection with the increase of electrical equipments to be mounted on an automobile. Accordingly, it has been required to produce branch circuits having a high density from a few parts.
Consequently, it has been known to divide the electric connection box into several sections, to design the sections in modules and to form circuits by welding conductor terminals provided between the modules.
As described above, the divided modules are joined to each other upon production of the electric connection box designed in modules. Consequently, it is necessary to join and weld free ends of the bus bars provided in the respective modules. Many spots being welded of the bus bars are juxtaposed very closely to one another. Since the bus bars are cut and set by a press operation, the bus bars are not always aligned precisely in the juxtaposing direction. On the other hand, a spot welding apparatus carries current in a pair of electrodes while clamping the spots being welded between the electrodes. If only one of the electrodes comes into contact with the spot being welded, the welded portion will deteriorate. In the case where many spots being welded are arranged in a poor alignment condition, it is necessary to position a pair of electrodes for every spot being welded, thereby lowering the working efficiency.
SUMMARY OF THE INVENTION
In view of the above problems, an object of the present invention is to provide a resistance welding head that can weld a number of spots, which may be poorly aligned, and a resistance welding apparatus and a resistance welding method that utilize the resistance welding head.
In order to overcome the above problems, the present invention is directed to a resistance welding head including a pair of holding units including a pair of electrodes that clamp spots being welded along a joining direction, the spots being welded being stationary in positions joined to each other, the electrodes being movable relative to each other between a welding position where the electrodes clamp the spots being welded and a releasing position where the electrodes release the spots being welded; and a driving mechanism for driving the pair of electrodes through the holding units between the welding position and the releasing position. The resistance welding head is characterized in that: a floating guide supports the pair of holding units floated movably along the joining direction so that the center of the distance between the opposing electrodes coincides with the joining center of the distance between joined surfaces of the spots being welded in a process in which the electrodes clamp the spots being welded; the driving mechanism is provided on one of the holding units; and the driving mechanism drives the other holding unit through the one holding unit.
According to the present invention, since the driving mechanism is provided on the one holding unit and drives the other holding unit through the one holding unit, when the other holding unit is displaced by the actuation of the driving mechanism, the one holding unit is displaced by the reaction force against the other holding unit and thus the pair of the electrodes are displaced from the releasing position to the welding position. During this displacement process, the respective electrodes come into contact with the spots being welded and then clamp them. At the time, even if the joined surfaces of the spots being welded are offset from the center of the distance between the opposing electrodes, both electrodes are floated movably along the clamping direction of the spots being welded through the floating guide by means of the reaction force against the electrode that is first brought into contact with the spots being welded. Consequently, the opposing center of the distance between the opposing electrodes coincides with the joined surfaces of the spots being welded. Since the present invention can perform such a self-centering function, both electrodes can clamp the spots being welded, which are in an equal contact condition and a precise welding can be carried out efficiently after the electrodes reach the welding position.
Another aspect of the present invention is directed to a resistance welding apparatus including a current-carrying mechanism for carrying welding current to the respective electrodes; an electrode position detecting mechanism that detects whether or not the respective electrodes clamp spots being welded; and a control device that controls the current-carrying mechanism so that the welding current can be carried to the respective electrodes when the electrode position detecting mechanism detects that the respective electrodes clamp the spots being welded.
Still another aspect of the present invention is directed to a resistance welding apparatus for welding a number of spots being welded, which are juxtaposed at equal intervals, by using a plurality of resistance welding heads described above, that includes a work holder for holding the spots being welded; a welding head assembly including a plurality of resistance welding heads disposed along the juxtaposing direction of the spots being welded; a mechanism for disposing the spots being welded between the electrodes of the resistance welding heads by driving the welding head assembly and the work holder relative to each other; and an intermittent driving mechanism for intermittently driving the resistance welding heads at a pitch between the spots being welded supplied between the electrodes by driving the welding head assembly and the work holder relative to each other. The electrodes of the resistance welding heads are spaced at a distance of an integer times a pitch of the spots being welded, and a control device that controls the intermittent driving mechanism is provided so that the electrodes of the resistance welding heads pass over the welded spots.
In the present invention, when a plurality of resistance welding heads weld a number of spots being welded, which are juxtaposed at equal intervals of distance, the respective electrodes of the resistance welding heads are disposed at intervals of the integer times the pitch of the spots being welded. When the respective resistance welding heads are driven by the intermittent driving mechanism, the respective resistance welding heads can weld the corresponding spots being welded.
Still another aspect of the present invention is directed to a resistance welding method for welding a number of spots being welded, which are juxtaposed at equal intervals of distance, including: disposing a resistance welding head having a pair of electrodes for clamping spots being welded in a manner of floating movably in a direction perpendicular to the juxtaposing direction of the spots being welded; applying to the resistance welding heads a reaction force exerted when the electrodes clamp the spots being welded; clamping the spots being welded while centering the electrodes; and starting a re
Hattori Tatsuya
Kato Shigeru
Kerns Kevin P.
Sumitomo Wiring Systems Ltd.
LandOfFree
Resistance welding head and resistance welding apparatus and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Resistance welding head and resistance welding apparatus and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Resistance welding head and resistance welding apparatus and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3207734