Abstract: Apparatus for and method of electro-erosive cutting with a cathode in the form of a wire. The wire advances through at least one or two guides, especially open V-grooved guides that do not surround the wire. One wire guide is upstream and the other downstream, in the direction the wire advances along, of the workpiece being processed. The wire guide or guides can rotate around the wire.

Abstract: Apparatus for electro-erosive cutting. A cathode in the form of a wire advances through at least one wire guide, with one guide being upstream and the other, if any, downstream of the workpiece in terms of the direction advanced by the wire. The at least one wire guide is an open, specifically a notched, wire guide, one that does not surround the wire, that is, and has associated with it a closed wire guide, specifically a wire guide in the from of a torus that surrounds the wire.

Abstract: To permit machining of workpieces on spark erosion cutting equipment with large angles of inclination, the guidance heads which guide the wire electrode in the cutting zone with respect to the workpiece are pivotably arranged and controlled, by being mounted on individual gimbal suspensions so that it is possible to provide for a controllable slope angle up to large amounts. Individual drive motors control movement about the respective gimbal axes.

Abstract: Erosive working machine for cutting prepared closed inner shapes (15) and closed outer shapes (16) of a workpiece (12) fixed by a workpiece holder by means of a filamentary or strip electrode (14) arranged on guidance means (13, 18). At least one guidance means (13, 18) is arranged on a motor-rotatable rotating mechanism (20) in such a way that the center line (23) of rotating mechanism (20) at at least one geometrical locus coincides with the center of the cross-section of electrode (14). Thus, during the erosion process, a collision between the guidance means (13, 18) and the closed inner shape (15) or closed outer shape (16) or a tool holder (11) is avoided.

Abstract: The disclosed method includes forcing a flushing medium through the work zone in the workpiece in one direction by providing a flushing chamber to one side of the workpiece where the workpiece is being machined.Also disclosed is an apparatus for practicing the method. The apparatus includes means for forming a chamber on one side of the workpiece and for effectively covering portions of the chamber walls which are cut by the wire electrode as the machining progresses, to maintain sufficient flushing pressure in the chamber. In one embodiment, a chamber wall mamber is spaced from the workpiece by a gasket ring and flushing fluid is forced into the space between the two members, so that it is forced from there out from that space through the machining zone in the workpiece.

Abstract: The circuit is for driving motors in which there is access to all the ends of the motor winding sections. The circuit is of the type having a set of drive circuit units connected together as a gang in parallel between power source terminals. Each unit includes in series a winding section and a transistor control switch. There is additionally provided an auxiliary circuit with an auxiliary winding and resistor combination which substantially matches the motor winding and resistor combination impedance. The auxiliary winding is used to store the energy from a motor winding section when it is turned off and then to supply the energy to the next motor winding section to be turned on, thus reducing the driving energy needed for the motor and also reducing the current rise and fall times in the windings.

Abstract: To provide constant tension on an electro-erosive electrode machining wire, tape or ribbon stretched in a working path between advancing rollers and pulling rollers, a tension loading arrangement, for example weights, springs, or the like, are applied to the wire to maintain the tension thereof at a constant value. The deflection of the wire, due to elongation thereof as a result of heating, differences in manufacturing technologies and the like, is sensed and fed back to the motors driving the advancing and pulling rotors to maintain the tension, as controlled by the motor torques and speeds at a uniform value.

Abstract: The disclosed circuit is for controlling step motors of the type which have access only to a common winding neutral point or to partial neutral points. A switching transistor switches a low-loss circuit into the motor drive circuit for free running of the motor. A common circuit common to all the windings is switched in for rapid switching off of the current in the windings and for recovery of the energy stored in the inductors of the circuits.

Abstract: Disclosed is a system and method for controlling the motor drive for positioning a workpiece on a compound slide in such a way that the workpiece arrives at the target position in minimum elapsed time and without overshoot. A fixed program memory, in conjunction with a comparator and a combiner, is used to process information as to the actual position and velocity of the body and the desired position and velocity of the body to determine the optimum torque for the motor. The memory includes information as to the control characteristics of the motor and the desired path yet to be traveled to the target position.The method of positioning comprises the steps of controlling the motor so that it runs initially at maximum torque in a first region, at less than maximum torque and in the same direction in a second region, and then at yet another torque magnitude and with the torque in the opposite direction in a third region.

Abstract: A movement control apparatus, which can be constructed as an accessory, provides in addition to the primary process-controlled movement of the electrode circular a secondary movement. The secondary movement is imparted to the electrode through a drive arm fixed at one end to the bottom slide of a cross-slide on which the electrode is also fixed and attached pivotably at the other end to an eccentric point of a rotating spindle. The mechanism for rotating the spindle is so designed that the degree of eccentricity of the eccentric point may be adjusted mechanically while the spindle is rotating. The eccentricity may also be controlled by the action of a cam follower which runs along a template, so that the circular movement of the electrode is controlled by the template in a copying mode.

Abstract: A head assembly for an electro-erosion machine tool comprises, in a housing, a guide for guiding the moving filamentary or strip-form tool electrode and first contact means for supplying erosion energy to the electrode. The scavenging medium is fed into the housing so as to cool the contact means and guide, and leaves it by way of a nozzle through which also the electrode leaves the housing on its way to another head assembly arranged on the opposite side of the location where machining is performed, the scaverging medium being thereby fed to the machining location as an envelope coaxial to the electrode. Second contact means for contacting the workpiece to be machined are fixed to the nozzle and the connections to each contact means are arranged for low inductive energy loss.

Abstract: A generator for machining by means of electrical discharges between a tool electrode and a workpiece electrode. The generator consists of a main voltage source connected between the tool electrode and the workpiece electrode through an improved switching circuit which is activated by an adjustable oscillator. The switching circuit delivers short pulses of high pulse current and consists of a plurality of identical impulse amplification stages. A first one of these impulse amplification stages drives all the additional ones. Power transistors are used. With a base current regulating system, the turn-off delay of these power transistors is eliminated by keeping them far away from saturation. Resistance-capacitance and resistance-inductance elements and a special cabling are used to eliminate certain impulse transmission problems.

Abstract: In a spark erosion machine in which the tool electrode comprises a tensioned flexible wire or tape, machining induced force due, for example, to the magnetic and electric fields induced by the sparks, act on the tool electrode and may cause it to vibrate. To reduce the tendency for such vibration, a compensating signal is passed through the tool electrode or applied between the tool electrode and workpiece so as to produce a magnetic or electric field which compensates for the machining induced forces. The compensating signal is preferably adjustable in magnitude and/or frequency (the latter assuming it is an alternating signal) and the output of the generator which produces it is decoupled from the output of the spark pulse generator. The spark pulse generator and the compensating signal generator may be interdependently synchronized by a synchronizing signal lead connected between them.

Abstract: An assembly such as a tool head for a spark erosion profiling machine tool comprises an elongate tool holding member having first and second opposed lengthwise bearing surfaces and third and fourth opposed lengthwise bearing surfaces. By way of example the member can be square, the bearing surfaces then being the four long sides of the member. The member is partly housed in a housing wherein there are mounted bearings which support the member for movement in the direction of its length with respect to the housing. The bearings can comprise discrete circulating roller bearing shoes and they are in abutting contact with the member at five positions in the region of each of two planes spaced apart along the length of the member by a calculated optimum distance.

Abstract: Casting apparatus for use in making intermediate molds for the preparation of tool electrodes comprises a pallette for holding the casting and adjusting devices for ensuring parallelity and correct alignment for the mouldingfaces. There is also vibrator to ensure improved consolidation of the casting material and to provide for degassing.

Abstract: An over or undersize abrasive master mould is used to form tool electrodes by abrading a workpiece using a circular reciprocatory motion. The master mould is made by a casting process which starts with a preformed model, positive or negative, of the exact shape to be machined by the tool electrodes to be made. Positive and negative castings of the model, one of which castings is abrasive, are subjected to a relative circular reciprocatory motion in an abrading operation to provide the correct under or oversize of the master mould, which is then made directly or indirectly from the abraded casting. Casting apparatus for use in the method comprises a pallette for holding the casting and adjusting devices for ensuring parallelity and correct alignment for the moulding faces and there is also disclosed apparatus for the abrading operation in which an error detection system regulates the amplitude of the reciprocatory abrading movement.

Abstract: A control system, for a machine tool of the kind in which electrical energy passes across a gap between a tool electrode and a workpiece to erode the workpiece, comprises means for forming signals representative of the rate of erosion of the workpiece and the rate of undesirable erosion or "wear" of the tool electrode, and a computer means which receives the signals and combines them with a signal received from a data input device, which signal represents a desired optimum relationship between the two rates of erosion, and forms an appropriate output signal for controlling the machine tool. The data input device is usable, in rough machining operations where the tool electrode may be relatively cheaper than machine time, to ensure that machining is done in the shortest time by allowing a relatively high rate of tool wear and, in fine machining where the tool electrode is expensive, to ensure minimal tool wear at the cost of machine time.

Abstract: In order to machine a multidimensionally curved surface on a workpiece using an electro-erosion, i.e. spark erosion or electro-chemical erosion, machine tool, the machine tool is provided with a tool electrode which has an effective machining face inclined to the direction in which the advance feed drive of the machine tool advances the tool electrode towards the workpiece. By using transverse feeding mechanisms for the tool electrode or the workpiece acting under the control of a computer, or by using a cam and guide arrangement coupled to the tool electrode, the tool electrode and workpiece are so relatively moved that the effective machining face of the electrode always moves in the direction of the momentary largest radius curvature of the curve to be machined. When a cam and guide arrangement is used, the tool electrode can be coupled to the advance feed drive by way of a coupling device which incorporates a universal joint, or a domed surface sliding joint.

Abstract: Electroerosion machining (EDM or ECM) is carried out with a minimum of manual intervention. Under control of recorded data an electronic control system utilizing control logic directs the set-up operations as well as the actual machining process. The operations automatically (i.e., without the necessity of manual intervention) include loading and removal of workpieces and electrode material, trueing up of the workpiece (which may be by providing a transformation of the data rather than by adjusting the position of the workpiece), making starting bores, threading the electrode through a starting bore, applying a low melting alloy or other conducting adhesive to cement a core in the process of being cut out by machining, cutting the electrode after completing a starting bore and joining electrode ends after rethreading in a new starting bore. In threading the electrode it may be pushed simply or with the support of a surrounding jet of pressure medium, or it may be pulled by a grapple member.

Abstract: Two condition index variables are used for controlling operation in such a manner that one of the variables is kept as close as possible to a minimum value, while the other is held within an assigned range. Both condition index variables depend on the rate of flow of the flushing liquid through the working gap, on the interval between discharges in the gap or on the duty cycle or repetition frequency and amplitude of the discharge pulses. The condition index variable held to a minimum may be the integral of the square of the error signal from the regulating circuit of the electrode advancing drive, the integral of the square of the acceleration of electrode movement or the quotient obtained by dividing the square of the error signal by the square of the gap current. The regulating value to be held within an assigned range is a calculated breakdown potential defined by the relation of the variation of the error signal to the variation of the electrode spacing.