RU2455133C1 - Spark-erosion boring machine - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to spark-erosion boring machine tool intended for making tangential bores in fuel nozzles. Machine tool comprises bed to support slide with tool head and displace crosswise, slide with divider including spindle to carry workpiece. Note here that said divider is mounted on slide to reciprocate therewith while slide is arranged on sector to turn through preset angle in vertical plane. It comprises also bath for working fluid with drive for vertical displacement. Machine tool is furnished with mechanism to recover shape of electrode working part shape. Said electrode is arranged in tool head and provided with "П"-shape case attached to vibrator armature with bore for electrode aligned with guide tube bore. Said tube is secured on case cover to accommodate electrode. Said "П"-shape case has electrode feed mechanism arranged between vibrator armature and guide tube. Said mechanism is made up of articulated pull roller and pressure roller spring-loaded thereto.

EFFECT: higher efficiency and precision.

3 cl, 6 dwg

Description

The invention relates to the field of machine tools, and in particular to EDM machines designed for forming holes in fuel nozzles.

Known electroerosive automatic machine for flashing holes in bodies of revolution, containing a base, a head with a spindle mounted on the base, equipped with a vertical spindle drive, on which a sub-electrode plate is fixed. There is a flange with an insulator on the spindle, to which an electrode holder with an internal channel is attached, the free end of which is made in the form of a collet with a tubular graphite electrode-tool (EI) inserted into it. The electrode holder channel is in communication with the reservoir for the working fluid and the pumping station. On the basis of the installed drain pan for waste fluid, connected by a pipeline with a container for the working fluid. The machine is equipped with a firmware controller, one output of which is connected to the machine control system, complete with which there is a pulse generator supplying current to the EI, while the machine control system is connected to the vertical head drive. The other output of the firmware controller is connected to the input of the electromagnetic valve regulating the supply of working fluid to the treatment zone.

An automatic dividing mechanism mounted on the base support plate has also been introduced into the EDM machine.

To carry out processing, the necessary program is laid down in the machine control system, in accordance with which a workflow is carried out, in particular, flashing of the pins of the shell of the nozzle of the aircraft engine, where the centers of the pins are located along a circular arc (shell) with a constant step. The shell is mounted and mounted on the faceplate.

The control system with the pulse generator is turned on, and the signal enters the hydraulic drive of vertical movement, lowering the spindle with EI and the local fluid supply unit fixed to it, the local chamber of which first touches the shell and is pressed against it by the lower shelf. At the moment of touching the local chamber of the shell, the end switch and the adjustable stop are closed, as a result of which the electromagnetic valve for supplying the working fluid from the tank with the help of the pumping station is turned on, through a hose with a connecting fitting and an internal channel of the electrode holder in the electrodes. The local chamber is filled with working fluid to the level of the drain gap. The movement of the electrode holder down stops at the moment of the appearance of the electrical contact between the EI and the pin head, after which the burning of the pin to a predetermined depth begins. In the process of operation, when the EI is worn out, the electrode plate with the electrode holder moves by the amount of wear, when this value is exceeded, the adjustable stop contacts the limit switch, which gives a signal to turn off the pulse generator and the firmware controller, as a result of which the burning process stops.

During processing, the erosion products of the metal of the pin and graphite EI accumulate within the stitched hole, in this case, the firmware controller sends a signal to the control system of the machine, as a result of which the pulse generator is turned off. The hydraulic actuator of vertical movement for a split second removes the EI from the stitched hole and reinserts it, while the erosion products are washed out by a stream of working fluid flowing into the drain pan, and then through the hose into the container. At the end of the firmware, the pulse generator of the operating current is turned off and the electrode holder with EI rises to the upper position. When the electrode holder stops in the upper position, the vertical movement drive is turned off, the control system of the machine sends signals to the drive of the automatic dividing mechanism, which rotates the faceplate at a given angle. The plate is rotated at a given angle with high accuracy, as a result of which the axes of the next shell pin and EI coincide. After turning the faceplate at a predetermined angle, the vertical displacement drive is automatically turned on, lowering the electrode holder. The following processing cycle is carried out (see RF patent No. 2032505, class B23H 9/14, 1995).

As a result of the analysis of the design of this machine, it should be noted that it provides the processing of holes in automatic mode. However, the known machine is designed to handle relatively large parts, allowing the use of local pressure chambers, providing a given level of liquid above the processing zone. In addition, the vertical arrangement of the head reduces its functionality, since a rotary installation device is required to ensure the tilt of the part relative to its vertical axis. In the control system of the machine’s cycle of operation, it is possible to combine program control with electromechanical, which provides for manual adjustment of a given operation, which reduces the accuracy and reliability of the machine. The design of the machine provides accurate positioning of the EI relative to the machined holes in the pins, however, it does not provide for the restoration of the shape of the EI, which reduces the accuracy of processing the holes in their shape.

A known machine for electric spark piercing spray holes in nozzles, containing a base on which an electric spark tool head with a drive mechanism of an electrode tool (EI) is mounted, a transverse carriage with a mechanism for its movement (rotation) and a dividing device with a mechanism for installing and fixing the workpiece to be processed.

An EI wear compensation system is mounted in the tool head housing, made in the form of an electromagnetic clutch with an adjusting screw, a friction clutch disc mounted on the end of the drive shaft of the EI drive, and an armature. The coupling anchor, through a ball bearing, is spring-loaded to the friction clutch disc and can rotate from the drive shaft, which is hollow, with a roller placed in its cavity, one end of which is attached to the drive shaft through the diaphragm and the other to the feed roller system. To limit the rotational movement of the armature, two limit switches are installed, one of which is fixed to the handle, and the other to the body.

The transverse carriage mechanism is designed to obtain axial displacement of the spray hole. A handle with a nonius is provided for moving the carriage. The gap-free connection in the screw-nut system is provided by tension springs.

The carriage rotation mechanism is designed to set a given angle of inclination of the dividing device with respect to EI. For this, an arc groove is made on the mechanism case, in which a longitudinal carriage is installed, made similarly to the transverse one. The longitudinal carriage carries a dividing device. There are two handles for moving the carriage, one of which is connected to the screw and by means of its rotation the longitudinal carriage is rotated in an arc and thereby the angle of inclination of the workpiece relative to the EI is set, and the other handle is used to fix the carriage set to a predetermined angular position. At the base, a bath for the working fluid is mounted, equipped with a drive for its vertical movement.

For flashing a hole in a part (nozzle), the carriage is installed at a predetermined angle with respect to the EI, and a predetermined angle of displacement of the hole is set with a divider. The EI supply is turned on, which is brought to touch the workpiece with the work surface, after which the EI supply is switched to the working one. At the same time, the electromagnet coil of the compensation system is turned off, the anchor of which is pressed to the end of the drive shaft of the electrode feed mechanism and the hole flashing begins, while simultaneously monitoring the firmware depth. Since during the time of flashing the EI hole is worn out by a certain amount, after it is withdrawn from the machined hole between the nozzle surface and the end of the EI, a gap is formed that allows the workpiece to be turned through a dividing mechanism by a certain angle, after which the next nozzle hole is flashed taking into account the amount of EI wear (see USSR AS No. 218345, class B23P 1/08, 1973 - the closest analogue).

As a result of the analysis of the design of the known machine, it is necessary to note that all its functions are manually configured (including setting the specified axial displacement of the spray hole and its height in the part). The control of the machine during operation is provided by an electromechanical system, including ball screw pairs, handles with scales and dials on the carriages for moving the spark tool head and dividing mechanism, manually adjustable screw stops, twin shafts, end and travel switches operating from the screw stops, dividing rings, retainers and mechanism of the Maltese cross. Rotary drives are equipped with DC motors. Such a machine is characterized by limited functionality and, as a rule, can be configured to process parts (nozzles) and holes of the same name. In addition, during the processing of the part, the wear of the EI occurs not only at the end (shortening its length), but also along the lateral surfaces, forming at the end of the working part of the EI close to a conical surface, which does not allow ultimately to fully calibrate the machined hole with a cylindrical part EI. The restoration of the necessary form of the working part of EI is not provided. All this reduces the productivity and quality of machining parts.

The technical result of the present invention is the development of a machine for electroerosive shaping of holes, providing efficient and accurate formation of holes located at different angles to each other and to the axis of the part, ensuring operational readjustment of the machine over a wide range.

The specified technical result is ensured due to the fact that in the machine for electroerosive shaping of openings containing a base, on the upper plane of which there is a carriage with a tool head (IG) with the possibility of lateral movement, a carriage with a dividing mechanism (DM) containing a spindle with a device for installation of the workpiece, and the DM is mounted on the carriage with the possibility of reciprocating movement, and the carriage is installed on the sector with the possibility of its rotation to a given a goal in the vertical plane, as well as a bath for the working fluid (RG), equipped with a vertical displacement actuator, pressure and drain, which sets the preset level of the RG in the bath, nozzles connected respectively to the mains for supplying and discharging water from the bath, is new, that the machine is equipped with a mechanism for restoring the shape of the working part of the electrode-tool (EI), a vibrator mounted on the IG, equipped with a U-shaped body fastened to the vibrator armature, in which there is an axial hole for the EI, coaxial the guide tube mounted on the cover of the housing and designed to pass EI, while on the body of a U-shaped, between the armature of the vibrator and the guide tube, is placed the feed mechanism of the electrode-tool, made in the form of pulling and spring-loaded pressure rollers on it, while the mechanism for restoring the shape of the working part of the EI can be made in the form of a bracket mounted on the housing of the DM, and a plate of refractory material is fixed on the bracket, or in the form of a bracket fixed to the bracket of the mechanism the formation of the shape of the working part of the EI with a transverse slot for passing through the slot of the end of the EI, with rollers and guiding elements moving along them with an electrode-wire, connected with the mechanism of its tension and rewinding, made in the form of coils placed on a rack, one of which is equipped with a rotation drive and the other with an adjustable brake.

The invention is illustrated graphic materials on which:

- figure 1 shows the machine, front view;

- figure 2 - machine, top view;

- figure 3 is a tool head in section;

- figure 4 is a dividing mechanism in section;

- figure 5 - recovery mechanism EI - execution 1;

- figure 6 - recovery mechanism EI - performance 2.

The machine for electroerosive forming holes contains a base 1, which is a welded frame made of rolled steel and covered with panels. On the upper plane of the base 1, with the possibility of reciprocating transverse movement along the guides, a carriage 2 is mounted on which a tool head (IG) 3 is mounted. The lateral drive of the carriage 2 of IG 3 can be made in various known ways, for example, in the form of a ball screw pair, screw which is mounted on the base 1 and connected to the stepper motor, and the nut screwed on it is mounted on the carriage 2.

A sector 4 is also fixed on the upper plane of the base, on which a carriage 5 with a dividing mechanism (DM) is installed 6. The carriage 5 is mounted on a sector 4 with the possibility of moving in a vertical plane and fixing in a predetermined position, setting the angle of inclination of the part axis (or the hole being machined) to the axis of EI. The law of movement of the carriage is set by a radius groove 7 made on sector 4. This radius groove is a guide (for example, such as "dovetail") for moving the carriage.

The angular movement drive of the carriage 5 is made in the form of a worm pair, consisting of a worm (not shown) sitting on the same shaft with a handle 8 for its rotation, and a section of the worm wheel (not shown) that is engaged with the worm.

DM 6 is mounted on the carriage 5 with the possibility of reciprocating movement along the guides and is designed to fix the workpiece and rotate it around its axis by a predetermined angle (depending on the number of holes in a row) with respect to the EI. DM is made in the form of a casing 9, a spindle 10 is mounted in the casing with a possibility of rotation about the axis, on the shank of which a gear 11 is fixed, which is engaged with a gear 12 fixed on the output shaft of the stepper motor 13. On the front of the spindle there is a device 14 for installation and fixing the workpiece to be processed 15.

The drive of longitudinal movement of DM 6 can be made in various known ways, for example, in the form of a ball screw pair, the screw of which is mounted on the base of the carriage 5 and connected to the stepper motor 16, and a nut screwed on it (not shown) is mounted on the carriage 5 of the housing 9 of DM 6 .

IG 3 of the machine is located on the carriage 2 and is made in the form of a housing 17, in the upper part of which is placed a vibrator, including the core (fixed element) 18 of the vibrator and the armature (movable element) 19 of the vibrator; the anchor 19 is fastened to the upper part of the U-shaped body 20 by a sleeve 21, mounted on the membrane 22, mounted in the housing 3 IG 3 on top. In the lower part of the body of the U-shaped form 20, a tube 23 is installed for the passage of EI (not shown), mounted on a membrane 24 installed in the housing 17 of IG 3 from the bottom. The core 18 and the anchor 19 are made hollow to pass EI. The lower part of the housing 17 of IG 3 is closed by a cover 25, in the center of which a guide tube 26 with a tip 27 mounted on it with a conductive sleeve 28 is mounted. The holes in the core 18, anchor 19, sleeve 21, tube 23, and guide tube 26 are mounted coaxially during assembly. Between the sleeve 21, fastened to the anchor 19, and the tube 23 on the inner side of the housing of the U-shaped form 20, a mechanism for moving the EI is made, made in the form of a pulling 29 and pressure (not shown) rollers. The pulling roller 29 has a rotation drive, the implementation of which is known and not disclosed in this application, and the pinch roller is pressed by an elastic element (not shown) to the pulling roller. The pulling and pressing rollers are kinematically connected to each other through a guitar of gears 30 located on the outer (back) side of the U-shaped body 20. The guitar ensures their rotation in opposite directions. Minimum backlash in the drive when changing the direction of rotation of the rollers and moving the EI are provided by tension springs (not shown).

The machine is equipped with a mechanism for restoring the shape of the working part of the EI, which can be made in the form of a bracket 31, mounted on the DM housing, and mounted on the bracket of the plate 32 of refractory material (tungsten, molybdenum). The bracket with the plate is located outside the working area, but in close proximity to it. The mechanism for restoring the shape of the working part of the EI can be performed in another way, for example, in the form of a bracket 33, mounted on an arm 31 with rollers 34 and guide elements 35, through which an electrode wire 36 is drawn, wound from the feed coil 37 and wound onto the take-up reel 38 on the block 39 of the rewind and tension of the wire with the corresponding drives of rotation and tension (not shown).

At the base of 1 machine there is a lifting bath 40 for RJ equipped with a drive for its vertical movement (not shown).

The machine is equipped with a control panel 41, a program control system, a pulse generator, a power supply (not shown).

As a program control system, a DGT 735-5 type CNC system can be used, including a CNC unit and a personal computer (PC), which allows you to control the tuning movements of the IG and DM carriages and the rotation of the part and the working movement of the EI, control the operation of the recovery mechanism of the working part EI, setting the pulse generator modes.

The control system consists of two main modules: a CNC system and a personal computer. Using the CNC system, the operating and commissioning feeds are controlled, the processing modes are set and the pulse generator parameters are selected, the electrodes touch control, the processing start reference system is reset, the EI working displacement is set given the EI wear value at the end and the machined hole is calibrated, position control EI relative to the part, control of the actual EI movement speed at the moment, setting different EI movement speeds and various operating modes of the imp lsov and processing values at different portions of the working movement EI. The adaptive interelectrode gap tracking system provides maximum performance. The software has a clear graphical interface and allows you to simultaneously solve several technological problems in graphical mode.

As a generator of electrical pulses, a program-controlled generator of the DGT 740 GI type can be used.

The transistor program-controlled generator DGT-740-GI allows you to: work on tap water (dielectric working fluid - RH), increase the speed of processing parts, and reduce wear on the electrode tool. All parameters of the generator are controlled by the CNC system, which makes it possible to optimally select the technological modes of processing the part from the database. Thanks to the use of microprocessor control, the generator provides: roughness within Ra 0.8 μm during finishing, dimensional stability of the resulting holes, protection against short circuit during processing, turning off the generator when the wire breaks (during cutting of the electrode-tool), protecting the generator from prolonged short circuit, setting the generator to the optimal number of working pulses, pulse repetition rate, pulse duration time, setting the generator to reduce ionization the spark gap. The generator parameters are controlled using a personal computer included in the machine control system.

As stepper motors, a wide range of commercially available motors, for example, type RK 264, can be used.

Stepper motors provide tuning (installation) program movements, rotation of the workpiece by a given angle and working movements of the EI when flashing holes, as well as carriages with IS and EI when restoring the shape of the working part of EI.

The machine operates as follows.

To implement the processing of the workpiece 15, the latter is installed in the fixture 14 and fixed in it.

The EI is passed through the holes in the core 18, the vibrator armature 19 and the sleeve 21, the EI is fed into the EI pulling 29 and pressure rollers by manually squeezing the pressure roller, then the EI tube 23, the guide tube 26, the tip 27 and the conductor sleeve 28 are passed through. the access key on the control panel turns on the machine, turn on the PC. From the PC keyboard, a pre-compiled comprehensive program for controlling the part processing process is introduced into the CNC system, including tuning (installation) and working movements of the machine elements in the process of making holes in the part, restoring EI, all the functions performed by the CNC to implement and control the processing process.

By rotating the handle 8, the carriage 5 with the DM 6 is moved across the sector 4 by means of the groove 7, it is set, and consequently, the axis of the workpiece to be processed at a given angle relative to the axis of the EI. From the PC keyboard, the tuning movements of the carriage 2 are included, which sets the offset of the axis of the hole relative to the axis of the part and the carriage 5, which sets the height of the processed row of holes in the DM (its position relative to the EI). In the set position, the coordinates are fixed and are reset to zero on the display.

Raise the bath 40 in the upper (working) position, set the overflow valve in the working position, open the pressure and drain valves and turn on the water supply (RH) until it reaches a predetermined level, which will be maintained by the overflow valve. A control program is launched, which includes a pulse generator, a drive for rotating the pulling 29 and the pressure rollers, as a result of which the EI moves until it contacts the workpiece surface, the amount of EI movement from the initial position to the touch is displayed on the monitor, after which the electrode-tool changes speed the rotation of the roller 29 communicates the working feed, and the coordinate of the start of processing is reset, after which the countdown of the set value of the movement of the EI begins and the hole is processed, dnovremenno the beginning of processing power is supplied to the vibrator core 18, the armature 19 which performs reciprocating movements with an amplitude of ± 0,03 mm and a frequency of 50 Hz. Considering that the U-shaped body 20 is attached to the anchor 19, on which the pulling 29 and the pressure rollers are mounted, in which the EI is clamped, the latter also makes similar reciprocating movements. Communication of axial vibrations to the tool during hole shaping removes sludge from the treatment area. After the hole forming is completed, the rotation of both rollers is reversed and the EI is removed from the machined hole by the value of the specified processing depth. Since there was wear of the EI at the end during processing, a gap has formed between the EI and the part, the part is rotated around its axis by a predetermined angle (division step), after which the cycle of processing the next hole is repeated. In this case, the magnitude of the electrode displacement from the starting point to touching the part corresponds to the value of the EI wear at the end face. As practice has shown, in the process of processing holes, the wear of the EI occurs not only at the end, which is easily compensated by zeroing the start of processing when the EI touches the part and counts the amount of movement of the EI from this point, but also along the lateral surfaces of the EI, the working part of which acquires a conical shape, which reduces the accuracy of subsequent machined holes. Therefore, after processing a certain number of holes (determined experimentally for each size of the hole, part material and EI, processing parameters), the EI form is restored. The process of restoring the shape of the working part of EI is carried out depending on the execution of the mechanism for restoring the shape of the working part of EI.

To restore the shape of the working part of the EI according to a given program, change its polarity, telling it the polarity of the workpiece, and report the transverse movement of the carriage 2 with IG 3, as a result of which the EI is located opposite the plate 32 of refractory material, to which the potential of opposite polarity is applied; turn on the supply of EI and, as a result of their contact, the EER is machined by EI plate 32, which is currently EI, of the end part of EI, which is currently being processed by the part, by a certain amount, after which, according to a given program, the polarity of EI is changed and the carriage is moved backwards 2 return IG 3 to its original position.

When performing EI recovery using an electrode wire 36 moving along the rollers 34 and guide elements 35 of the bracket 33, mounted on an arm 31 mounted on the DM 6 housing connected to its rewinding 37 coils and tension 38, the EI polarity is changed in the same way as described above, and a potential of opposite polarity is applied to the electrode wire 36, the carriage 2 is moved with the IG 3 to the electrode wire 36, while at the same time pushing the EI from the conductor sleeve by its feeding mechanism by the amount of cutting relative to the wire electrode 36 and include wire-drive displacement electrode 36, since the touch-EI and the wire electrode feed carriage 36 2 3 IG is switched on and a working spark occurs trimming end portion EI-wire electrode 36 by a predetermined amount. From the point of contact of the electrodes, the IG 2 carriage 2 moves a distance slightly larger than the sum of the diameters of the EI and the wire electrode 36, after which the feed drive takes the EI to its original position, the polarity changes to EI, and the carriage 2 with IG 3 and EI returns to its original position position for processing the next hole in the part.

To process the next hole, at the command of the control system, the stepper motor 13 rotates the DM 10 spindle 10 through the gears 11 and 12, and therefore the workpiece mounted on it by a predetermined angle, and then the next hole processing cycle is carried out similarly to that described above until all the workpiece holes are formed.

Using this machine provides:

- precision manufacturing of holes within ± 0.01 mm;

- the exception of the refinement of the obtained holes in the flow rate and spray;

- improving the accuracy and stability of the flow characteristics of the nozzles by increasing the accuracy of the shape of their holes.

Claims (3)

1. Machine for EDM forming holes, containing a base, on the upper plane of which there is a carriage with a tool head having the ability to transverse movement, a carriage with a dividing mechanism containing a spindle with a device for mounting the workpiece, and the dividing mechanism is mounted on the carriage with the possibility of reciprocating movement, and the carriage is mounted on the sector with the possibility of its rotation by a predetermined angle in the vertical plane, as well as a bathtub for workers liquid with a vertical displacement drive, characterized in that it is equipped with a mechanism for restoring the shape of the working part of the electrode-tool, a vibrator mounted on the tool head, equipped with a U-shaped body, fastened to the vibrator armature, in which there is an axial hole for the tool electrode , coaxial to the hole of the guide tube mounted on the housing cover and intended for the passage of the electrode-tool, while on the U-shaped body between the armature of the vibrator and the guide t the cabin is the feed mechanism of the electrode-tool, made in the form of pulling and spring-loaded pinch rollers kinematically connected to each other. 2. The machine according to claim 1, characterized in that the mechanism for restoring the shape of the working part of the electrode-tool is made in the form of a bracket mounted on the housing of the dividing mechanism, and a plate of refractory material is fixed to the bracket. 3. The machine according to claim 1, characterized in that the mechanism for restoring the shape of the working part of the electrode-tool is made in the form of an arm fixed to the casing of the dividing mechanism of the bracket with a bracket with rollers, guide elements for the wire electrode and coils for the wire electrode placed on the rack, one of which is equipped with a rotation drive, and the other with a brake.

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