Abstract:
A Czochralski method of producing a single crystal silicon ingot having a uniform thermal history. In the process, the power supplied to the side heater is decreased during the growth of a latter portion of main body, and optionally the end-cone, of the ingot, while power supplied to a bottom heater is gradually increased during growth the same portion. The present process enables a substantial portion of an ingot to be obtained yielding wafers having fewer light point defects in excess of about 0.2 microns and improved gate oxide integrity.
Abstract:
An emitter follower circuit has series circuits, each consisting of an emitter follower transistor (Q3, Q4), a current source, and a current source resistor connected to the emitter side of the emitter follower transistor (Q3, Q4). The source resistors are MOS transistors (N4, N5), which are switched on and off by control signals so that they have conduction and cutoff states. Between the source and the drain of each MOS transistors (N4, N5), current path means (R1, R2) is provided which has a resistance greater than the on-resistance of the MOS transistors to permit a very small current to flow, at least when said MOS transistors are rendered nonconductive.
Abstract:
A resistance welding method according to the invention includes: a melting start time specification process for specifying a melting start time, which is a time at which at least a part of a welding portion (Y) of a welding subject (W) starts to melt while being subjected to Joule heating by a power input from an electrode (11) pressed against the welding subject (W), by detecting a variation in an ultrasonic wave emitted toward the welding portion; a first power amount calculation process for calculating a first power amount, which is an integrated value of the power input into the welding subject via the electrode from the melting start time; a first determination process for determining whether or not the first power amount has reached a first set value; and a heating process for performing the Joule heating from the melting start time until the first power amount reaches the first set value.
Abstract:
In a resistance welding method, by controlling the power amount from a melting start time onward, the weld quality may be stabilized efficiently, even when a disturbance is present, because of the correlation between the amount of power input from the melting atart time and a resulting nugget. The resistance welding method includes: pressing an electrode against a workpiece; inputting power to the workpiece through the electrode to subject the workpiece to Joule heating; detecting the melting start time, which is the time at which at least a portion of the faying portion of a workpiece starts to melt when subjected to Joule heating; calculating a first power amount input into the workpiece from the melting start time; and determining whether the first power amount has reached a first set value; and continuing the Joule heating until the first power amount reaches the first set value.
Abstract:
In a resistance welding method, by controlling the power amount from a melting start time onward, the weld quality may be stabilized efficiently, even when a disturbance is present, because of the correlation between the amount of power input from the melting atart time and a resulting nugget. The resistance welding method includes: pressing an electrode (11a, 11b) against a workpiece (Wa, Wb); inputting power to the workpiece (Wa, Wb) through the electrode (11a, 11b) to subject the workpiece (Wa, Wb) to Joule heating; detecting the melting start time, which is the time at which at least a portion of the faying portion of a workpiece (Wa, Wb) starts to melt when subjected to Joule heating; calculating a first power amount input into the workpiece (Wa, Wb) from the melting start time; and determining whether the first power amount has reached a first set value; and continuing the Joule heating until the first power amount reaches the first set value.
Abstract:
This invention aims to provide a resistance welding method capable of stabilizing quality or improving efficiency of resistance welding such as spot welding. This resistance welding method comprises a calculating step of calculating resistance ratio X of a second electric resistance value R2 of workpieces to be joined in residual heat after Joule heating stops to a first electric resistance value R1 of the workpieces immediately before the Joule heating stops or vice versa (R2/R1 or R1/R2); a determining step of determining whether the resistance ratio X is equal to or greater than a threshold value Xn, and a reheating step of carrying out the Joule heating again when the resistance ratio X is smaller than the threshold value Xn. Thereby at least part of a welding portion is melted and solidified to reliably form a nugget, and a stably resistance-welded member can be provided.