Wire electrode supply device for wire-cut electric discharge machine

Abstract

A wire electrode supply device capable of preventing slack and snapping of a wire electrode even using a heavy wire bobbin without using a wire electrode tension detector. A pulley is provided between the wire bobbin driven by a torque motor and a brake roller. The wire electrode unwinds from the wire bobbin, passes through the pulley, brake roller and a workpiece work area, and is taken up by a wind-up roller. When the wire electrode traveling speed is changed from fast to slow, the pulley descends to prevent the wire electrode from slackening between the wire bobbin and the brake roller. When the traveling speed is changed from slow to fast, the back tension from the torque motor is reduced for a predetermined period of time, reducing tension on the wire electrode and preventing it from snapping. Also, the pulley descends, rotating the wire bobbin in the feeding direction and quickening tracking of the shift to fast feed speed, enabling snapping of the wire electrode to be prevented even when a heavy wire bobbin is used.

Description

BRIEF DESCRIPTION OF THE DRAWING

FIGURE is a schematic diagram showing an embodiment of the present invention.

Claims

1. A wire electrode supply device for supplying a wire electrode from a wire bobbin to a machining region of a wire-cut electric discharge machine, said wire electrode supply device comprising: a wire winding roller for winding the wire electrode;a brake roller for braking the wire electrode, said wire winding roller and said brake roller being arranged with the machining region in between;a torque motor operatively connected to the wire bobbin, for applying back tension to the wire electrode fed from the wire bobbin;a pulley arranged between the wire bobbin and said brake roller movably to ascend/descend by gravity and wire tension, such that the wire electrode fed from the wire bobbin travels to said brake roller through said pulley; anda controller for reducing the back tension applied by said torque motor for a predetermined period of time when a winding speed of the wire electrode by said wire winding roller is changed from low to high.

2. A wire electrode supply device according to claim 1, further comprising a spring for exerting an elastic force to said pulley at an end of a stroke of ascending/descending motion thereof.

3. A wire electrode supply device according to claim 1, further comprising a spring that expands and contracts with ascending/descending motion of said pulley.