RU2527108C2 - Tooling for local spark processing of inner surfaces of bodies of revolution - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention relates to machine building It is intended for machining of cylinder-shape mechanisms and parts, in particular, ICE cylinder inner surfaces, hydraulic cylinder bodies, bearings seats, etc. proposed tooling comprised rotary axial electrode holder and self-aligning three-point mechanism The latter can locate and centre rigid bearing bar inside machined part Parallelogram-type actuator is articulated with said bar to slide on and turn about machined part axis Said actuator has current conducting bus at bottom plate to feed electrode holder to machined surface and to press it there against to required force.

EFFECT: local spark processing at no direct view of working zone.

5 dwg, 2 tbl

Description

This invention relates to mechanical engineering, in particular to a technological tool for carrying out electrophysical processing of the inner surfaces of machine parts and mechanisms made in the form of a cylinder, in particular the inner surface of the cylinders of internal combustion engines, hydraulic cylinder housings, bearing bore holes, etc.

During the literary review on the design of technological equipment for the implementation of the technological process of electrospark alloying (EIL) of machine parts and working tools, the most common design options were identified.

The most widespread is the design with a manual vibration tool, where the electrode holder is made in rigid mechanical connection with a powerful vibrator, providing a vibration amplitude of up to 2 mm. The appearance of a manual vibration tool is shown in figure 1A [14]. A design variant in the form of a vibration tool with a disk electrode is also possible, where the electrode holder is the axis of rotation of the disk electrode with a remote vibration exciter (figure 1b) [14, 15]. To reduce the dimensions of the equipment in a plane perpendicular to the axis of the rod electrode, a design variant with an axial rotating electrode holder is used (Figure 1c) [18]. To increase productivity, multi-electrode accessories are used. One of the options for the construction of multi-electrode snap-in is presented in figure 1d [17].

A comparison of the capabilities of these design options is given in table 1.

There are options for combining mechanical effects, for example, combining axial rotation and mechanical vibrations in a vertical plane [19].

The most common drawback of most technological tooling options is its bulkiness. This drawback is primarily due to the fact that in the vast majority of cases, the method of electrospark alloying is used to repair and harden the outer surfaces of massive parts processed on standard turning equipment. Most often, the mechanization of the technological process of electrospark alloying is carried out through the use of screw-cutting lathes. Those. the constant movement of the processing tool relative to the hardened surface is due to the rotation of the workpiece. In view of the fact that when machining the inner surface of bodies of revolution, the overall dimensions of tooling are limited by the diameter of the cylinder, it is not possible to use the vast majority of the widespread design options for the working tool of spark spark alloying. In addition, it must be borne in mind that processing the inner surface of the cylinder requires a fundamentally different way of organizing the movement of the consumable electrode relative to the surface being treated.

It is important to note that all the considered options for the performance of technological equipment are positioned relative to the workpiece using external mechanisms (machine supports, manipulator supports, etc.). This approach makes it almost impossible to accurately position and base relative to the surface being machined.

Table 1 Comparison of the most common versions of technological equipment for electric spark alloying Execution option Advantages disadvantages Manual vibration tool - simplicity of design - versatility of customization - low positioning accuracy - the complexity of mechanization and automation - low productivity Disc electrode holder - increased productivity - the possibility of violating the stability of the process with uneven consumption of the electrode - energy loss of technological pulses - bulkiness of the structure - occurrence of inaccuracies in positioning Axial Rotating Electrode Holder - simplicity of design - versatility of customization - the possibility of a slight decrease in the mechanical properties of the coatings - oscillations of the electrode during beating of a rotating shaft Multi electrode accessories - high performance - positioning difficulty - violation of the stability of the ESA process - bulkiness of the structure

To select a basic analogue, it is necessary to consider the totality of technical and technological requirements related both to the requirements of the method of electric spark alloying and to the requirements caused by the geometry of the workpiece.

The method of electrospark alloying (ESA) is widely used in the field of hardening and repair (restoration of geometry) of a working tool and critical parts of heavily loaded machines and mechanisms. The method is based on the phenomenon of electrical erosion and polar transfer of the material of the anode (electrode) to the cathode (part) during pulsed discharges in a gaseous medium. Schematic diagram of the process of electrospark alloying is shown in figure 2.

The essence of the ESA process is that when the electrodes approach each other, the electric field strength increases. At a certain distance between the electrodes, it will be sufficient for the occurrence of a spark electric discharge. Through the channel of through conductivity that has arisen, the electron beam is focused focused on the solid metal surface of the anode (electrode). The motion energy of stopped electrons is released in the surface layers of the anode. Due to the fact that at the moment the system releases the stored energy by a throw, the current density significantly exceeds the critical values. As a result of this action, a drop of molten metal is separated from the anode (electrode), which moves to the cathode (part), ahead of the moving anode (electrode).

In the process of separation from the anode, the flying drop manages to heat up to a high temperature, boils and "explodes". The current circuit is interrupted, the compressive forces of the electromagnetic field disappear, and therefore the formed particles fly a wide front. Since the superheated drop and particles are in contact with the gas, they may differ in composition and properties from the starting material of the anode (electrode). The molten particles, having reached the cathode (part), are welded with it and partially embedded in its surface. The process does not end there, because after the particles the anode (electrode) moves, included in the electrical circuit, which has already managed to again accumulate energy. Through hot particles lying on the cathode (parts), a second current pulse occurs, accompanied by a mechanical shock of the moving mass of the anode (electrode) [2, 3].

At the next stage of the process, with the mechanical contact of the electrode and the workpiece, the particles are welded together, simultaneously warming up a thin layer of the cathode surface (part) on which they are located. In addition to the diffusion of the transferred particles deep into the cathode under the influence of an electric current, chemical reactions occur between these particles and the cathode material. A mechanical impact on the hot mass of materials forges the resulting coating, thereby significantly increasing its uniformity and density. Next, the anode (electrode) moves up, and on the surface of the cathode (part) remains a layer of anode material firmly connected to it [4].

The surface layers resulting from ESA have high adhesion to the base (part) and can provide an increase in hardness, corrosion resistance, wear and heat resistance, a decrease in the ability to set during friction, a decrease in the friction coefficient, restoration of the dimensions of the tool, change in electrical properties, etc. P. [5]

The literature cites data that EIL processing increases the resistance of mills, drills, cutters, taps by half, and the resistance of circular saws and cutting links of agricultural machines up to three times. Extensive practical experience has been gained in TsNIITMash during the hardening of machine parts. The EIL method was used to process the details of railway equipment (steam locomotives, diesel locomotives, wagons) - turbines for smoke exhaust vanes (2.5-3 times increase in durability), wheel bandages, locomotive roller axle boxes (3-4 times increase), spring suspension parts , automatic coupler, axle box. The literature mentions the processing of die tooling, mainly hammer dies as the most complex and expensive, where results are achieved by increasing the resistance by 2-5 times (up to a maximum of 10 times) [6].

The advantage of ESA technology is the possibility of local surface treatment, relative simplicity, which does not require the use of labor of highly qualified personnel, the lack of preliminary preparation of the treated surface, and high reliability of the equipment [2-4].

The disadvantages of the method when using traditional carbide electrode materials include low productivity, limited thickness of the formed layer, its high roughness and porosity [2-4].

The main difficulties in the design of technological equipment to ensure the technological process of electrospark alloying are associated with the fact that structural elements must combine high mechanical and electrical properties [4, 5, 6].

The requirements associated with the features of the process can be formulated as follows:

a) the need to ensure reliable isolation of tooling elements from the work surface;

b) the need to ensure the physical effect of the consumable electrode (anode) on the discharge zone on the part (cathode) for forging;

c) the need to ensure the mobility of the consumable electrode (anode) relative to the surface to be treated during processing to prevent erosion of the cathode (part) as a result of local multiple exposure to working pulses;

d) the need to maintain the operability of tooling at elevated temperatures (up to 200 ° C) arising from prolonged operation.

Requirements related to the geometry of the workpiece (cylindrical body with a rectilinear or non-rectilinear generatrix of the side surface) can be formulated as follows [1, 7, 8, 9, 10]:

a) minimizing the size of the equipment due to the relatively small size of the internal work surfaces;

b) ensuring accurate positioning of the sacrificial electrode relative to the workpiece while providing conditions for the normal (perpendicular surface) mechanical impact of the anode;

c) ensuring the stability of the processing process under conditions of a change in the linear dimensions of the consumable electrode;

d) ensuring the stability of the process at tilt angles from 0 to 180 degrees.

Based on the complex of the above requirements, the design with a rotating axial electrode is taken as the basic analogue. The main task of developing a new kinematic scheme for the execution of technological equipment is to overcome the main shortcomings of the basic design shown in Table 1, as well as minimizing the size of the mechanisms and developing a basic basing scheme relative to the inner surface of the workpiece.

The technical problem of the invention: the development of the concept of technological equipment for the implementation of the process of electrospark alloying (ESA) of the internal through surfaces of structures and mechanisms, which will allow processing holes and mating surfaces with a diameter of less than 200 mm

The problem is solved by using a fundamentally new kinematic scheme for moving the electrode based on a relatively motionless surface. As a guide for moving the electrode holder, there is a rigid rod fixed inside the workpiece by means of a self-centering three-support mechanism (figure 3) [13].

table 2 Structural elements of technological equipment No. p / p Name The position in figure 5 one. The emphasis basing four 2. Support rod axis 5 3. Support rod spring 6 four. Supporting rod 7 5. Electrode holder top plate 8 6. Lower electrode holder plate 9 7. Guide pin 10 8. Axial electrode holder eleven 9. Parallelogram knee 12 10. Contact bus 13 eleven. Axial Lock Nut fourteen 12. Longitudinal feed handle fifteen 13. Operating clearance adjustment knob 16 fourteen. Flexible cable 17 fifteen. Pulley eighteen 16. Electric motor 19

Such a system for organizing the positioning of the actuator will prevent its transverse movements while ensuring the movement of the electrode around and along the axis of the cylinder. These possibilities of movement provide the requirement for the mobility of the electrode relative to the workpiece.

The supply of the electrode holder with a consumable electrode to the surface of the workpiece is carried out by adjusting the parallelogram actuator shown in figure 4 [13].

The stability of the positioning of the electrode holder during operation of the parallelogram actuator is provided by the guide pins 10 (Figure 5).

To ensure forging and mixing of the material transferred to the surface of the product, the electrode holder 11 is made in the form of a shaft with axial rotation [3, 11].

In order to ensure the supply of a technological pulse for the implementation of the process of electrospark alloying, a conductive bus 13 is connected to the installations for electrospark alloying using standard connectors [12] on the bottom plate of the parallelogram actuator.

The appearance of the prototype tooling for the implementation of the process of spark processing of the inner surface of the bodies of revolution is shown in figure 5. The names of the positions in figure 5 are shown in table 2.

The developed technological equipment can be demanded during repair and hardening of internal cylindrical surfaces of mechanisms and working tools, such as cylinder-piston groups of modern internal combustion engines, electric motor housings, supporting structures of household appliances, parts of air conditioning systems, etc.

LIST OF USED SOURCES

1. Schipkov M.D. Welding of alloys based on aluminum and high-melting refractory metals. Tutorial. - L., LPI, 1983, p. 80.

2. Verkhoturov A.D., Podchernyaeva I.A., Pryadko L.F., Egorov F.F. Electrode materials for electrospark alloying. - M: "SCIENCE", 1988.

3. Gitlevich A.E., Mikhailov VV, Parkansky N.Ya., Revutsky V.M. electrospark alloying of metal surfaces. - Chisinau: “STIINZA”, 1985.

4. Verkhoturov A.D. The formation of the surface layer of metals during electrospark alloying. - Vladivostok: Dalnauka, 1995 .-- 323 p.

5. Yarkov D.V. The formation of functional coatings by ESA using electrode materials from mineral raw materials of the Far Eastern region, Khabarovsk: 2004. - 187 p.

6. Korotaev D.N. Creation of wearproof coatings by electrospark alloying in oxidizing and inert environments with optimization of modes and use of carbide electrodes, Dissertation, Omsk: 2009.

7. “Repair of aluminum cylinder blocks. Service References & Information ”, Alexander Schafer, Uwe Schilling, Simon Schneibel, Hamburg, MSI Motor Service International GmbH, ISBN 978-3-86522-201-5.

8. Zusin V.Ya., Serenko V.A. Welding and surfacing of aluminum and its alloys. - Mariupol: Renata Publishing House, 2004. - 468 p.

9. http://www.splav.kharkov.com/mat_start.php?name_id=1441

10. http://www.spbmotor.ru “Specialized motor center. The nuances of shelling "Alexander Khrulev, Sergey Samokhin.

11. Timoshenko S.P. Fluctuations in engineering. Translation from English. Edition 3 2007.440 s.

12. Rules for the installation of electrical installations (PUE). Seventh Edition. APPROVED by Order of the Ministry of Energy of Russia dated 08.07.2002 No. 204.

13. Reference technologist-machine builder. In 2 t. C74 T.2 / ed. A.G. Kosilova and R.K. Meshcheryakova. - 4th ed., Revised. and add. - M.: Mechanical Engineering, 1986.- 496 p.

14. Lazarenko N.I., Lazarenko B.R. A.S. No. 70651 (USSR). Device for coating of metals and alloys. Bull. Inventor, 1964. No. 22.

15. Mitskevich M.K. and others A.S. No. 557899 (USSR). Device for electrospark coating. Publ. in B.I. 05/15/1977.

16. Hight M.L., Koval N.P. and others A.S. No. 870046 (USSR). Device for electrospark coating. Publ. in B.I. 1981, No. 37.

17. Morozenko V.N., Andreev V.I. and others A.S. No. 428903 (USSR). Multi-channel rotary instrument. Publ. in B.I. 1974, No. 19.

18. Kulakov V.P., Galay V.I. and others A.S. No. 624760 (USSR) Device for electrospark alloying of metal parts. Publ. In B.I. 1978, No. 36.

19. Davydov V.M., Bogachev A.P. and others A.S. RU 2393067 (RU). Device for electrospark alloying. Publ. In B.I. 06/27/2010 (rotation and ultrasonic vibration along the outer surface of the part).

Claims (1)

Tooling for electrospark alloying of the inner surface of a part made in the form of a body of revolution, containing a rotating axial electrode holder, characterized in that it contains a self-centering three-support mechanism, made with the possibility of basing and centering inside the workpiece a rigid support rod, which is movable with the ability to move around and along the axis of the surface to be machined, a parallelogram actuator is fixed having a conductive bus on the bottom plate and made with the possibility of the supply of the electrode holder to the work surface, adjusting the degree of approximation of the electrode and the pressure of the electrode against the work surface.

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