Electric heating – Metal heating – Cutting or disintegrating
Patent
1994-02-23
1995-06-06
Evans, Geoffrey S.
Electric heating
Metal heating
Cutting or disintegrating
2424199, B23H 100, B23H 710
Patent
active
054224543
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a wire-cut electrical discharge machine, in particular, to a device for setting the tension of an electrode wire (referred to as a wire tension setting device) during a normal machining operation. The wire tension setting device is integral with a wire feeding device which provides the electrode wire for the electrical discharge machine during operation.
BACKGROUND ART
An electrical discharge machine with an electrode in the form of an electrically conductive wire, referred to as an electrode wire, electrically machines a workpiece into the desired shape by using an electrical discharge generated between the electrode wire and the workpiece by applying a discharge voltage therebetween. The electrode wire is drawn from a wire bobbin by a wire conveying device, and moves through upper and lower wire guides provided in a machining region.
A wire tension setting device is provided between the wire bobbin and the wire conveying device in order to apply a wire tension to the moving electrode wire.
Referring FIG. 3, an example of the wire tension setting device of the prior art is illustrated.
The wire tension setting device of FIG. 3 comprises a brake roller 6 which applies a braking torque to an electrode wire 2. The brake roller 6 is connected to a output shaft 75 of a powder clutch 74, and is rotatable about the output shaft 75. The electrode wire 2 is around the brake roller 6, and moves in a predetermined direction. An input shaft 82 of the powder clutch 74 is connected to an output shaft 80 of a speed reducer 79 through a coupling 76. An input shaft (not shown) of the speed reducer 79 is connected to an output shaft (not shown) of a DC motor 78 which is used for feeding the electrode wire 2.
The powder clutch 74 is a commercially available means for transmitting a torque, which comprises magnetic powder and a exciting coil. When the exciting coil is energized, it generates magnetic field. In this magnetic field, the magnetic powder connects the input shaft 82 to the output shaft 75 so that torque is transmitted from the input shaft 82 to the output shaft 75. The magnetic powder allows slip between the input shaft 82 and the output shaft 75. The torque transmitted from the input shaft 82 to the output shaft 75 is controlled by the current to the exciting coil which controls the slip between the two shafts. During the normal machining operation of the electrical discharge machine, the braking torque on the brake roller 6 produces the tension in the electrode wire 2.
When the electrical discharge machine begins to operate or when the electrode wire 2 is broken, an electrode wire 2 must be installed, that is, a new portion of the electrode wire 2 must be drawn from the wire bobbin (not shown) and be engaged with the wire conveying device provided in the lower wire guide or within a column. This process is referred to as "wire connection".
The wire tension setting device is also used during wire connection. The DC motor 78 is energized after the new portion of the electrode wire 2 is drawn from the wire bobbin and wound around the brake roller 6.
The rotation of the DC motor 78 is transmitted to the input shaft 82 of the powder clutch 74 through the coupling 76. When current is supplied to the powder clutch 74, the input shaft 84 is connected to the output shaft 75. Thus, the rotation of the DC motor is transmitted to the brake roller through the output shaft 75. The rotation of the brake roller 6 feeds the electrode wire 2 toward the wire conveying device. The above described wire connection is referred as "automatic wire connection", since it is automatically performed as one of the functions of the electrical discharge machine.
Once wire connection is completed, the current to the DC motor 7 is cut off. Since the electrode wire 2 is wound around the brake roller 6, the brake roller 6 continues rotating due to the friction between the surface of the brake roller 6 and the moving electrode wire 2. From FIG. 3, it may be understood that the powder clutch 74 a
REFERENCES:
patent: 4748310 (1988-05-01), Aso et al.
patent: 4978828 (1990-12-01), Umetsu et al.
patent: 5023420 (1991-06-01), Aso et al.
patent: 5130508 (1992-07-01), Umetsu et al.
patent: 5142116 (1992-08-01), Yokomichi et al.
patent: 5268551 (1993-12-01), Kawanabe et al.
Evans Geoffrey S.
Fanuc Ltd.
LandOfFree
Device for setting wire tension for a wire-cut electrical discha does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Device for setting wire tension for a wire-cut electrical discha, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device for setting wire tension for a wire-cut electrical discha will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-988836