A positive contact resistance soldering unit which has a relay therein, which is operated by a foot switch for selectively coupling a milliohmeter to the electrodes for measuring the resistance between the electrodes and the workpiece in order to determine the best contact therebetween. When the milliohmmeter indicates that the electrodes are in good contact with the workpiece the foot switch is depressed connecting the output of a power transformer to the electrodes to begin the soldering operation.
Apparatus and method for forming a reinforcing cage for a prestressed concrete pile, in which the cage includes a set of main steel bars arranged in a circular pattern and an auxiliary wire which is helically wound around and welded at its crossings with the steel bars, that prevents any crossings from being welded when the current for welding is either insufficient in magnitude or not present and that prevents any unwelded crossings from being subsequently tempered.
Apparatus provides for measuring weld resistance of each of a group of weld sites that are subject to variation with respect to weld resistance. The apparatus includes circuitry for inducing a flow of alternating current in a weld site. The magnitude of the induced alternating current is substantially constant; in particular, the percentage variation in its magnitude is substantially less than the percentage variation in resistance to which the weld sites are subject. The apparatus further includes voltage responsive circuitry for producing a signal representative of the magnitude of the resistance of the weld site.
The present invention provides a soldering iron with a graphite tip having two separate halves that are electrically isolated from one another. When both halves of the tip are applied to an electrically conductive material, such as the material to be soldered, an electrical circuit between the tip halves and an electrical power source is completed. Therefore, the tip can reach operating temperatures quickly. When the tip is removed from the joint, the electrical circuit is broken and the tip material may quickly cool to a temperature safe for human contact. The tip material permits higher power outputs than other battery operated portable soldering irons and permits over 300 joints for each full charge.
The present invention provides a soldering iron with a graphite tip having two separate halves that are electrically isolated from one another. The tip halves are each electrically connected to the opposite sides of an electrical power source. When both halves of the tip are applied to an electrically conductive material, such as the material to be soldered, an electrical circuit between the tip halves and electrical power source is completed. The halves are of the tip are constructed from material semi-conductive electrically and having high thermal conductivity. Therefore, the tip can reach operating temperatures quickly. When the tip is removed from the joint, the electrical circuit is broken and the tip material may quickly cool to a temperature safe for human contact. Because electricity is only able to flow when the two pieces of the tip are electrically connected, no separate switch is required. The tip material permits higher power outputs than other battery operated portable soldering irons and permits over 300 joints for each full charge. The soldering iron also includes a light disposed on the case to illuminate the tip and joint. However, the light is controlled by a separate switch and permits the tool to be used to illuminate the operator's surroundings without the risk of damage to persons or property from a heated tip. The tool also includes an electrical lead connected in series with the lamp, the power source, and a continuity testing probe. This aspect of the invention permits the tool to function as a continuity tester.
A method and apparatus is disclosed for fabricating a dry cell storage battery from a plurality of dry cells by soldering a battery strap to terminals of adjacent dry cells in a battery pack. A resistance heat solder apparatus is provided for soldering a joint defined by an end portion of a battery strap and a terminal of a dry cell, so that adjacent dry cells in the battery pack are in physical and electrical contact. Terminal probes, connected across the secondary coil of a step-down transformer, are used to make contact with the joint to be soldered for applying a voltage across the joint. Terminal probes have contoured tips. A preferred embodiment provides terminal probes which are contoured to be a mirror image of the contour of the joint where the particular terminal probe makes contact with the solder joint. Application of a voltage across the joint provides a collimated current flow path through the joint. An intense heat is created within the joint by the current flow.
