RO131489A0 - Equipment for machining curved holes and micro holes by ultrasound-assisted electrical discharge - Google Patents

Abstract

The invention relates to an equipment for machining curved holes and micro holes by ultrasound-assisted electrical discharge, intended to be mounted on a volume electrical discharge machine and connected to an ultrasound generator. According to the invention, the equipment comprises an upper plate (1) mounted on the working head of an electrical discharge machine on which a vertical rule (2) is mounted, which takes over the working head advance and withdrawal movements (2a) to transmit them to a drive wheel (4) by means of some flexible metal strips (3) winding in some circular channels (3a) to the drive wheel (4), some columns (5) which are mounted in a diametric channel (4a) with T-shaped profile, a cross member (6) mounted on the said columns (5), an attachment device (7) assembled onto the cross member (6) for attaching an ultrasonic chain (8) which performs torsional vibrations about the longitudinal axis that coincides with the rotary axis of the drive wheel (4), a tool-electrode holder (9), a tool electrode (10) for curved holes, two adjustable bearing bodies (11) and some vertical columns (12) with helical channels mounted on a base plate (13).

Description

Equipment for the processing of curved holes and microg holes by ultrasonic assisted erosion, requesting the .Politehnica University "from Bucharest

I - DESCRIPTION

The invention relates to an equipment for ultrasonic assisted erosion processing of the holes and microg holes with a longitudinal axis, which can be mounted on a machine by volume erosion and is connected to an ultrasound generator.

Known drilling equipment along a longitudinal curved axis, patents US 550783 A and US 5017057 A, which allow the drilling of the curve with the aid of a cutting tool, the rotation of which is transmitted by means of a flexible cord, but which allow only the drilling of materials with relatively low hardness and strength, lower than that of the cutting tool.

Also known are the equipment for electro-erosion processing of holes and micro-holes with a longitudinal axis with the help of electrodes-tool with conjugated form, patents US 5637239 A and US 3402279 A, but the processing process is very unstable and with low performances.

The disadvantages of the aforementioned solutions are:

- extremely difficult processing of holes with longitudinal curved axis in materials with high hardness and resistance with the help of cutting tools;

- the impossibility of processing the micro-holes with longitudinal axis curved in materials with high hardness and resistance by means of the cutting tools which should have sub-millimeter diameters;

- the difficult elimination of the particles taken from the interstices during the processing by electro-erosion;

- frequent phenomena of short-circuit or even continuous arc and repeated withdrawals of the tool when machining by erosion, resulting in a low productivity;

- reducing the quality of the processed surface due to the instability of the EDM process;

- the instability of the process of electro-erosion processing, especially in the case of microgas with curved axes, determined by the very low processing intersection, by the order of the micrometers.

- making holes with longitudinal axis curved at an angle at the relatively small center, generally less than 180 °.

The technical problem solved by the invention consists in the processing with high productivity and quality of holes and microgates with longitudinal curved axes with an angle at center greater than 180 ° in thermally hardened, electrically conductive materials.

The equipment for processing curved holes and micro-holes by ultrasonic assisted erosion, according to the invention solves the mentioned technical problem by the fact that:

- allows the processing of holes and micro-holes with curved axes in thermally hardened, electrically conductive materials, by means of electro-erosion, using electrodes-tool of conjugated form that executes torsional vibrations with ultrasonic frequency;

- the accuracy of the hole shape is ensured by the fact that the center of rotation of the ultrasonic torsional oscillation movement of the tool electrode coincides with the center of curvature of the longitudinal axis of the hole / microg holes;

- allows the holes and micro-holes to be made with a longitudinal axis curved at an angle at the center greater than 180 ° by rotating the driving wheel of the equipment in the initial position and then rotating the tool-electrode port around its axis, using a sliding adjustment until the electrode- the tool returns to the end of the drilled hole;

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Equipment for the processing of curved holes and micro-holes by ultrasonic assisted erosion, requesting the "Politehnica * University" of Bucharest

- increases the quality of the surface processed by electro-erosion due to the ultrasonic cavitation induced in the processing intersection, effectively removing the particles taken from the processing intersection;

- the quality of the surface processed by electro-erosion increases by the ultrasonic torsional vibrations of the tool electrode along the longitudinal curve axis of the hole, which have the capacity to substantially reduce the short-circuit phenomena between the tool electrode and the processed surface;

- Increases the productivity of the processing by ultrasonic assisted erosion by reducing the repeated withdrawals of the tool electrode in the direction of the longitudinal axis of the curved hole generated as a result of obtaining the stability of the electroerosive process;

- increases the productivity of the EDM processing by further removing the liquid and solid material as a result of the ultrasonic cavitation induced near the EDM spot on the surface of the machined material.

The equipment for the processing of holes and micro-holes with longitudinal curved axes by ultrasonic assisted erosion has the following advantages:

- performs the processing of holes and micro-holes with longitudinal axis curved in high-hardness, electrically conductive materials;

- increases the quality and precision of the machined surface of the bores and microgrid curves as a result of torsional ultrasonic vibrations with the center of the torsional motion in the center of curvature of the longitudinal axis;

- increases the productivity through the torsional ultrasonic vibrations of the tool electrode, reducing the short-circuit phenomena between it and the processed surface, avoiding the repeated withdrawals through the stability of the electroerosive process;

- increases the productivity of the electroerosive processing by the additional removal of material in liquid and solid state, as an effect of the ultrasonic induced cavitation in the processing intersection due to the ultrasonic torsional vibrations of the tool electrode;

- the possibility to process holes with an angle at the center of the longitudinal axis curved greater than 180 °, through the auxiliary rotational movements of the steering wheel of the equipment and the electrode holder.

The following is an example of embodiment of the invention in relation to Figures 1, 2, 3, 4 and 5, which represents:

- Figure 1, the assembly of the equipment for the processing of curved holes and micro-holes by ultrasonic assisted erosion in axonometric view;

- Figure 2, horizontal section of the equipment for the processing of curved holes and micro-holes by ultrasonic assisted erosion;

- Figure 3, vertical section of the equipment for the processing of curved holes and micro-holes by ultrasonic assisted erosion;

- Figure 4, the electrode-tool attachment module for curved holes;

- Figure 5, the electrode-tool attachment module for curved micro-holes;

The equipment for the processing of curved holes and micro-holes by ultrasonic assisted erosion - figure 1 - is composed of: the top plate 1 which is attached to the working head of the EDM machine (not shown), with the screws 1a for T channels, which is mounted through plastic deformation vertical ruler 2 for transmitting the forward or withdrawal movement 2a of the working head of the machine by means of the two flexible metal strips 3, which are wound in the circular channels 3a at the driving wheel 4, the strips 3 being fastened with screws 2b on the ruler 2 and the wheel 4, which performs the rotational movements 4b in one direction and in the other; columns 5, which are mounted on the diameter channel 4a with a T-profile, assembled by tightening adjustments with the bushings 5a and the screws 5b for the T-channels (see fig. 2), the cross member 6 mounted on the columns 5 in the openings 6a and fastened with the screws 6b , the clamping device 7 of the ultrasonic chain 8 which performs the torsional ultrasonic oscillation movements 23b; cross (V 2 Ο 1 6 - - 0 0 5 3 4 2 7 -07-2016

Equipment for the processing of curved holes and micro-holes by ultrasonic assisted erosion, requesting the Polytechnic University of Bucharest can move along the axis of the diameter channel 4a with a T profile, so that the longitudinal axis of the ultrasonic chain 8 coincides with the axis of rotation of the wheel 4 ; electrodule holder 9, tool hole 10 for curved holes, positioned at an antinodal point (maximum amplitude) on the ultrasonic chain 8, which performs circular movements of advance and withdrawal 10a simultaneously with torsional ultrasonic oscillations 10b with the rotation center located on longitudinal axis of the driving wheel 4 and the ultrasonic chain 8; the two adjustable bearing bodies 11, the vertical columns 12 with helical channels, mounted on the base plate 13, assembled on the working table of the machine with T channels (not shown), using the channels 13a.

The clamping device 7 of the ultrasonic chain - figure 2 - is composed of: the screw 14 inserted into the channel 14a of the crosspiece 6, the flange 15 having a spherical surface 15a, which is in contact with the conjugated surface of the flange 16; the screws 17 which by rotation change the relative position of the flanges 15 and 16 and implicitly of the axis of the ultrasonic chain 8 (electrode-tool) relative to the machined part and the axis of rotation of the wheel 4, the disc springs 18 which maintain the relative position between the flanges 15 and 16 ; the nodal flange 19 (of zero amplitude) which is assembled with the flange 16 through the threaded rods 7a and the nuts 7b (see fig. 1); the reflecting bushing 20, the piezoelectric discs 21 connected to the ultrasonic generator (not shown) and the radiating bushing 22 which are pre-assembled with the screw 24 together with the nodal flange 19; the concentrator 23 having the helical channels 23a (see also fig. 1) for the production of the torsional ultrasonic vibrations 23b and which is caught by the radiant bush 22 with the bolt 25.

The tool-electrode holder 9 - figure 4 - is composed of: a rod 26 with threaded surface 26a (see fig. 2) assembled with the hub 23, having the flat surfaces 26b (see fig. 3) for tightening the key, the bush 27 which forms a sliding fitting 27a with the rod 26, the circular tool electrode 10, which has a straight portion 10c with the flat surfaces 10d, which enter the notch 27b, the threaded bushing 28 which secures the tool electrode 10; the bushing 27 can be rotated with the tool electrode 10 relative to the rod 26, the fixing in the desired position being realized with the threaded pin 26c; after the wheel 4 has reached the end of the stroke and is brought to the initial angular position, the tool electrode 10 is positioned at the end of the hole made for further processing of the boreholes with angles at the center greater than 180 °.

The tool electrode holder 9a for curved microgels - figure 5 - is composed of: threaded rod 26 for assembly with the concentrator 23 (see fig. 2), the bush 30, which forms the slip fitting 30a with the rod 26, the tool electrode 10e circularly. (with sub-millimeter section) for curved micro-holes which is inserted into the transverse hole 30b of the bush 30, the threaded pin 31 which secures the tool electrode 10e; the bush 30 can be rotated and fixed in the desired position by means of the threaded pin 29, and implicitly the tool electrode 10b, relative to the threaded rod 26 in order to make curved microgels with the center angle greater than 180 °; after the pre-cast, the driving wheel 4 has been brought to the initial angular position, the tool electrode 10e rotates to the end of the hole made to further process the micro-hole.

The driving wheel 4 - figure 3 - is composed of: the disc made of insulating material 32, assembled on the wheel 4 with the screws 32a (see also fig. 1), in order to create the potential difference between the tool electrode and the machined part fixed to the machine table. , the shaft 33 on which the wheel 4 is assembled, which is widened with the bearings 34, assembled in the bodies 11, whose position is adjustable vertically, depending on the height of the workpiece, by moving on the columns 12 and fixed in the desired position with the screws 35 , which penetrate into the vertical channels 12b and secured with the nuts 36 with profile conjugated to the columns 12a, the threaded pins 35a, ensuring the vertical translation, the columns 12 being assembled on the base plate 13 with the screws 37, washers, plates and additional screws 37a.

Of 2 O 1 6 - - 0 0 5 3 42 7 -07- 2010

Equipment for the processing of curved holes and micro-holes by ultrasonic assisted erosion, requesting .Politehnica University · from Bucharest

Claims (1)

1. Equipment for the processing of curved holes and micro-holes by ultrasonic assisted erosion which is mounted on a volumetric erosion machine and is connected to an ultrasound generator characterized in that it comprises a top plate 1 mounted on the working head of the machine. electro-erosion on which the vertical ruler 2 is assembled, which takes on the movement 2a of advance and withdrawal of the working head and transmits it to the conductive wheel 4 by means of flexible metallic strips 3, which are fastened with the screws 2b of the ruler 2 and the wheel 4 and which it is wound on the channels 3a of the driving wheel 4, on which the columns 5 are mounted in the diameter channel 4a with profile T, with the help of the bushes 5a and the screws 5b with profile T, the cross member 6, mounted on the columns 5 in the openings 6a and fastened with the screws 6b , the device 7, assembled on the cross member 6 with the screw 14 whose head is inserted into the channel 14a, by end of the ultrasonic chain 8, which executes torsional vibrations about the longitudinal axis coinciding with the axis of rotation of the driving wheel 4, the position of the beam 6 being adjustable by displacement along the diameter channel 4a, and the longitudinal axis of the ultrasonic chain 8 being parallel to the axis of the wheel conductor 4, the flanges 15 and 16, belonging to the device 7 with two spherical conjugate surfaces 15a relatively displaceable, by rotating the screws 17, the disc springs 18 maintaining this position, the tool-electrode holder 9, which holds the circular tool-electrode 10 for making the holes curves or circular electrode 10e for making curved microgels, which is positioned at the end of the ultrasonic chain at an antinodal point, the tool electrode 10 having a straight portion 10c with the flat surfaces 10d, assembled in the notch 27b of the bush 27, which forms an adjustment slide 27a with threaded rod 26 in concentrate hour 23 with the help of the flat surfaces 26b, the bushing 27 being able to rotate around its axis to make curved holes with an angle at the center greater than 180 °, being fixed in the desired position with the radial threaded pin 26c, after previously the leading wheel 4 was brought to the initial position, the threaded bushing 28 which secures the tool electrode 10, or the tool electrode 10b for making the curved microgreens having a straight portion 10f which is assembled with the bush 30 through the transverse hole 30b and fixed with the threaded pin 31, the threaded rod 26 in the hub 23, which forms the slip fitting 30a with the bush 30, which can be rotated for making curved microgas with center angles greater than 180 °, the radial threaded pin 29 for fastening the bush 30 in the desired position, after, previously, the driving wheel 4 was brought to its initial position, the driving wheel 4 having the insulating disc 32, as well wide on the shaft 33, widened in the bodies 11, the columns 12 showing the helical surfaces 12a, on which the bodies 11 move, whose position is adjusted vertically, depending on the position of the surface to be worked, and is fixed in the desired position by means of the screws 35, which penetrate into the vertical channel 12b the threaded pin 35a, ensuring the movement of vertical translation and the nuts 36 with profile conjugated to the helical columns 12a, which ensures the vertical position.