A power supply device for wire electric discharge machining includes: a first DC power supply; first switching elements between the first DC power supply and a machining gap; a second DC power supply; a second switching element between the second DC power supply and the machining gap; and a pulse generator controlling the first and second switching elements. The pulse generator is configured so that, in order to generate an electric discharge in the machining gap, the second switching element is switched on and the voltage of the second DC power supply is applied to the machining gap; the first switching element is switched on intermittently at a predetermined frequency in response to an electric discharge generation detection signal, and a series of current pulses is fed to the machining gap. The feeding of the series of current pulses is discontinued when the current pulses don't reach a reference current.

A wire electrical discharge machine for machining a workpiece by generating electric discharge at a discharge gap between the workpiece and a wire electrode includes: a machining current setting unit for setting the magnitude of a normal machining current depending on the discharge gap state at application of a discharge induction voltage at the previous time or previous times; and a machining current control unit configured to control a main discharge circuit so as to supply the normal machining current to the discharge gap when the present discharge gap state is the normal state, control the main discharge circuit so as to supply a short-circuit machining current smaller than a predetermined current to the gap when the discharge gap state is the short-circuited state, and control the main discharge circuit so as not to supply any machining current to the gap when the discharge gap state is the open state.

A machining method for three-dimensional open flow channel using high-speed arc discharge layered sweep, which arranges an axial line of an installation shaft of a tool electrode with six degrees of freedom to be perpendicular to an axial line of a to-be machined work piece in an arc discharge process, with the tool electrode sweeping in a closed path in a plane or a curved surface perpendicular to the installation shaft, wherein the path of the sweeping satisfies: a space of an enveloped space being formed by the tool electrode moving in the path and being coincident with a removed portion of the work piece does not exceed a preset machined cavity of the flow channel. The present invention is based on high-speed arc discharge of hydrodynamic arc breaking and realized layered milling and surface machining for three-dimensional open flow channels.

A machining method for three-dimensional open flow channel using high-speed arc discharge layered sweep, which arranges an axial line of an installation shaft of a tool electrode with six degrees of freedom to be perpendicular to an axial line of a to-be machined work piece in an arc discharge process, with the tool electrode sweeping in a closed path in a plane or a curved surface perpendicular to the installation shaft, wherein the path of the sweeping satisfies: a space of an enveloped space being formed by the tool electrode moving in the path and being coincident with a removed portion of the work piece does not exceed a preset machined cavity of the flow channel. The present invention is based on high-speed arc discharge of hydrodynamic arc breaking and realized layered milling and surface machining for three-dimensional open flow channels.

A wire electric discharge machine for machining a workpiece by causing a discharge between a wire electrode delivered from a wire bobbin and the workpiece. The wire electric discharge machine includes: a remaining length calculation unit that calculates a remaining length of the wire electrode based on electrode winding coefficients, bobbin draw-out radius correlation information, and a spool diameter of the wire bobbin. The electrode winding coefficients depend on a winding density of the wire electrode, an inner width of the wire bobbin, a wire diameter of the electrode wire, and a winding tension of the wire electrode. The bobbin draw-out radius correlation information is correlated with a bobbin draw-out radius that is a distance between a position at which the wire electrode wound around the wire bobbin is separated from the wire bobbin and a central axis of rotation of the wire bobbin.

A wire electric discharge machine for machining a workpiece by causing a discharge between a wire electrode delivered from a wire bobbin and the workpiece. The wire electric discharge machine includes: a remaining length calculation unit that calculates a remaining length of the wire electrode based on electrode winding coefficients, bobbin draw-out radius correlation information, and a spool diameter of the wire bobbin. The electrode winding coefficients depend on a winding density of the wire electrode, an inner width of the wire bobbin, a wire diameter of the electrode wire, and a winding tension of the wire electrode. The bobbin draw-out radius correlation information is correlated with a bobbin draw-out radius that is a distance between a position at which the wire electrode wound around the wire bobbin is separated from the wire bobbin and a central axis of rotation of the wire bobbin.

Coupling device (1) for a pipe (2), including a sleeve (13) for receiving the pipe (2) and at least one sealing member (5) to provide a seal between the sleeve (13) and the pipe (2), a pressure member (6) for applying a pressure to the sleeve (13) and to the pipe (2), and a grip element (4) extending along at least a part of the perimeter of the pipe (2), wherein the grip element (4) is provided with dents (9) pressed out of the plane of the grip element (4) adjacent to slit like openings (8) punched out of the grip element (4), wherein edges (8) of the slit like openings (8) are subjected to a peening operation.

Coupling device (1) for a pipe (2), including a sleeve (13) for receiving the pipe (2) and at least one sealing member (5) to provide a seal between the sleeve (13) and the pipe (2), a pressure member (6) for applying a pressure to the sleeve (13) and to the pipe (2), and a grip element (4) extending along at least a part of the perimeter of the pipe (2), wherein the grip element (4) is provided with dents (9) pressed out of the plane of the grip element (4) adjacent to slit like openings (8) punched out of the grip element (4), wherein edges (8) of the slit like openings (8) are subjected to a peening operation.

A wire electrical discharge machine includes: an electrode unit for supplying a machining current to an electrode gap; a switch for changing impedance between a machining power source and the electrode unit; and a controller for, at the time of a core retaining process, controlling the switch to set the impedance to be higher than the impedance in a cutting process and thereby suppressing the machining current flowing through the electrode gap.

A wire electrical discharge machine includes: an electrode unit for supplying a machining current to an electrode gap; a switch for changing impedance between a machining power source and the electrode unit; and a controller for, at the time of a core retaining process, controlling the switch to set the impedance to be higher than the impedance in a cutting process and thereby suppressing the machining current flowing through the electrode gap.