Wire electric discharge machine

Abstract

A lower arm is passed through a slot in a machining tank. The slot of the machining tank is provided with a seal section for sealing with a plate-shaped seal member. The movable table is moved by a servomotor. The machining tank and a workpiece are fixed on the movable table. At the seal section, a seal member on the machining tank side slides with respect to the plate-shaped seal member, thereby generating a sliding resistance. This sliding resistance increases as a sludge produced by electric discharge adheres to the seal section, thereby distorting the lower arm and influencing the machining accuracy. Accordingly, a load that acts on the servomotor is detected, and a sliding resistance load at the seal section is obtained. When a reference load is exceeded by the detected resistance load, arrival of the seal section at the timing for maintenance is displayed and notified.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention will be obvious from the ensuing description of embodiments with reference to the accompanying drawings, in which:

FIG. 1 shows a drive section of one embodiment of a wire electric discharge machine according to the present invention and a seal section of a machining tank;

FIG. 2 is a schematic block diagram mainly showing a controller of the wire electric discharge machine according to the one embodiment of the invention; and

FIG. 3 is a flowchart showing maintenance timing detection notification processing executed by a processor of the controller of FIG. 2 for each predetermined period during the operation of the wire electric discharge machine of FIG. 1.

Claims

1. A wire electric discharge machine, in which a lower arm penetrates a slot formed in one side plate of a machining tank movable in an axial direction of the lower arm and a direction perpendicular to the axial direction, and which has a seal section configured to prevent a machining fluid from leaking out through the slot of the machining tank, the wire electric discharge machine comprising: load detecting means for detecting a sliding resistance load at the seal section;determination means for determining whether or not a predetermined load is exceeded by the load detected by the load detecting means; andwarning means which issues a warning to prompt maintenance of the seal section when the determination means concludes that the predetermined load is exceeded by the detected load.

2. The wire electric discharge machine according to claim 1, wherein the warning means is a display unit, a signal lamp, or an alarm generator configured to generate an alarm sound.

3. The wire electric discharge machine according to claim 1, wherein the load detecting means detects a load on a motor for driving the movable table.

4. The wire electric discharge machine according to claim 1, wherein the seal section is composed of a machining-tank-side seal member mounted on the side plate of the machining tank so as to surround the slot and a plate-shaped seal member which presses the first seal member against the side plate of the machining tank, thereby sealing the slot, and the load detecting means is a current detector which detects a drive current of a motor for driving the movable table with respect to the lower arm in a longitudinal direction of the slot of the machining tank, perpendicular to the axial direction of the lower arm, thereby detecting a sliding resistance generated when the machining-tank-side seal member slides with respect to the plate-shaped seal member as the movable table is driven to move by the motor.

5. The wire electric discharge machine according to claim 1, wherein the load detecting means is composed of a disturbance estimation observer for estimating a load on a drive motor for driving the movable table.

6. The wire electric discharge machine according to claim 1 or 2, wherein the load detecting means is a load cell attached to a member which is influenced by the sliding resistance load at the seal section.