Squeezing detection control method for consumable electrode arc welding

Abstract

A squeezing detection control method is provided for consumable electrode arc welding in which a cycle of arc generation and short-circuiting is repeated between a consumable electrode and a base metal. First, squeezed droplet is detected as a premonitory sign of arc recurrence at the end of the short-circuiting. This detection is based on a fact that a squeeze detection reference value is attained by a differential value of the voltage or resistance between the consumable electrode and the base metal. Then, a welding current supplied to a short-circuit load is rapidly decreased upon detection of the squeezed droplet. Upon recurrence of the arc, the welding current is increased. This arc recurrence is detected by a fact that the differential value attains an arc recurrence reference value which is greater than the squeeze detection reference value.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a timing chart depicting a squeezing detection control method in consumable electrode arc welding according to Embodiment 1 of the present invention.

FIG. 2 is a block diagram of a welding power source for embodying the squeezing detection control method in consumable electrode arc welding according to Embodiment 1.

FIG. 3 is a timing chart depicting a squeezing detection control method in consumable electrode arc welding according to Embodiment 2 of the present invention.

FIG. 4 is a detailed block diagram of a second squeeze detection circuit ND2 in a welding power source for embodying the squeezing detection control method in consumable electrode arc welding according to Embodiment 2.

FIG. 5 shows an electric-current and voltage waveform and a droplet in consumable electrode arc welding in which a cycle of a short circuit period Ts and an arc period Ta is repeated.

FIG. 6 is a block diagram of a welding power source which operates on a conventional squeezing detection control method.

FIG. 7 is a timing chart of signals in the welding power source in FIG. 6.

FIG. 8 is a timing chart corresponding to FIG. 7, for describing problems.

Claims

1. A squeezing detection control method in consumable electrode arc welding in which a cycle of arc generation and short-circuiting is repeated between a consumable electrode and a base metal, the method comprising the steps of: detecting of squeezed droplet as a premonitory sign of arc recurrence at an end of the short-circuiting, the detecting being based on a fact that a predetermined squeeze detection reference value is attained by a differential value of a voltage or a resistance between the consumable electrode and the base metal;decreasing rapidly a welding current supplied to a short-circuit load upon detection of the squeezed droplet and increasing the welding current upon recurrence of the arc;wherein the arc recurrence is detected by a fact that the differential value attains a predetermined arc recurrence reference value which is greater than the squeeze detection reference value.

2. The squeezing detection control method according to claim 1, wherein the rapid decreasing of the welding current is performed only when a change rate of the differential value upon attainment of the squeeze detection reference value is smaller than a predetermined value.