RU2582412C1 - Method for jet processing of materials - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention relates to jet processing of materials. Method comprises generating a processing jet supplied from a nozzle to machined workpiece. Fluid medium used is molten fusible alloy, hydrostatic pressure of which is increased before forming processing jet. Method includes cooling processing jet of said molten alloy to its fractional crystallisation. Collecting partially crystallised spent molten alloy with particles of machined workpiece, is converted into liquid phase is separated particles of processed workpiece from melted alloy and latter is supplied to input of fluid medium circulation.

EFFECT: broader technological capabilities.

2 cl, 1 dwg

Description

The invention relates to the field of jet cutting and processing of materials that carry out a high-speed liquid jet, as well as a high-speed liquid jet containing free abrasive particles.

A known method of cutting with an energy jet carrying an abrasive powder, comprising mixing the abrasive powder with an energy carrier, accelerating the mixture in a supersonic accelerating nozzle using superheated water vapor at a temperature of 400-550 ° C and an abrasive powder concentration of 1-5 wt. % (RU No. 2050251, IPC B24C 1/00, 1993).

This method has the following disadvantages:

- as a result of dispersion of the abrasive stream, a relatively wide cut is formed, which leads to a significant energy consumption and intensive wear of equipment (especially nozzles, even made of wear-resistant materials: tungsten carbide or boride);

- due to high pressures and flow rates, it is rather difficult to maintain a coherent flow of the jet;

- the need for mixing the abrasive material in a liquid medium leads to rapid wear of the nozzle, which reduces its service life to hours and even minutes;

- The use of abrasive material leads to environmental pollution.

There is also known a method of jet processing of a workpiece, comprising forming a processing jet supplied from a nozzle to a workpiece using a fluid circulation system (see RU No. 2331503, IPC B24C 5/02, 2006). Water is used as a fluid, and for abrasive use it is frozen in ice. Used ice is thawed in the bath to form a liquid fluid, which is filtered from the processed products and then sent for reuse.

The disadvantages of this solution are that in many applications, water or known water-based systems cannot be used with specific materials or workpieces where the presence of water or the corrosion to which it can lead is unacceptable. In such circumstances, jet cutting is not applicable. In addition, the energy of the fluid is determined by the specific gravity of the processing material, which is small for water, as well as by the speed of the jet.

The problem to which the claimed invention is directed is expressed in providing the possibility of expanding the range of processed materials and increasing the energy saturation of the cutting jet.

The technical result obtained when solving the problem is expressed in that the possibility of a destructive effect of the cutting jet on the volume of the material being processed adjacent to the cut is excluded, which allows to expand the range of processed materials. In addition, a multiple (of the order of three to ten) increase in the energy density of the cutting jet (as compared to water) is provided due to an increase in the density of the processing material.

An alternative technical result: the exclusion of the use of external heat transfer at the phase change section, the shortening of this section due to an increase in the speed of sound and all phase transition processes in liquid metals, a decrease in the dispersion of both the liquid jet and the multiphase mixture (due to the higher density), leading to an increase concentration of jet energy.

To solve the technical problem, the method of jet processing of the workpiece, including the formation of a processing jet supplied from the nozzle to the workpiece using a fluid circulation system, is characterized in that a molten fusible alloy is used as the fluid, the hydrostatic pressure of which is increased before the formation of the processing jet while cooling the processing stream of said molten alloy until it is partially crystallized, collecting m partially crystallized exhaust molten alloy particles preform, converted it into a liquid phase separated particles preform from the molten alloy and the latter is fed to the input circuit of the fluid system. In addition, a heavy, chemically inactive and non-toxic alloy is used as a low-melting alloy.

A comparative analysis of the features of the claimed solution with the features of the prototype and analogues indicates the conformity of the claimed solution to the criterion of "novelty."

The features of the characterizing part of the claims solve the following functional tasks:

The sign "... a molten fusible alloy is used as a fluid ..." provides the possibility of forming a cutting jet from a material with a density greater than the density of water and not having a destructive effect on the processed material.

Signs indicating that "the hydrostatic pressure is increased before the formation of the processing stream", allow the fluid to transfer speed due to pumping means similar to those used when working with liquid.

Signs indicating that "carry out the cooling of the processing stream of the molten alloy mentioned before its partial crystallization", provide the possibility of forming in the cutting stream, after its departure from the means of its formation, abrasive particles, contributing to an increase in the processing effect. In this case, cooling is primarily a consequence of a sharp pressure drop in the cutting stream, after it leaves the nozzle.

Signs indicating that "collect partially crystallized spent molten alloy with particles of the processed billet, transfer it to the liquid phase, separate the particles of the processed billet from the molten alloy and feed the latter to the inlet of the fluid circulation system", ensure the fluid circulation.

Signs indicating that "a heavy, chemically inactive and non-toxic alloy is used as a low-melting alloy", provide the possibility of a multiple (about eight-fold) increase in the energy density of the cutting jet by increasing the density of the processing material and allow the method to be implemented without additional safety of the material (lack of it chemical transformations) and protecting personnel and the environment from the harmful effects of toxic products and secretions.

In FIG. 1 schematically shows a possible embodiment of a device that provides the implementation of the claimed method.

The drawings show the unit 1 for increasing the pressure of the working fluid (high pressure pump); its outlet jet forming nozzle 2, a drain pipe 3, a jet of 4 working liquids, a workpiece 5 mounted above a trap 6 provided with a filter pipe 7, a heater 8, a melt return pipe 9 to a block 1, a transfer pump 10, a heat insulating casing 11, a melt 12, cold store 13.

The device with which the claimed method is carried out comprises a block 1 for increasing the pressure of a liquid medium, a refrigerating chamber 13 for cooling the liquid medium to a design temperature at which the medium still remains in the liquid phase, an outlet nozzle 2, at the outlet of which the supercooled liquid medium instantly turns in the solid phase, which ensures efficient cutting and processing of the workpiece 5, the trap 6 of the medium and the pipe 9 of its return to the block 1 increase the pressure of the liquid medium.

Between the jet-forming nozzle 2 and the trap 6, a cooling chamber 13 can be installed to cool the jet 4 of the working fluid (jet of molten metal). When the cooling effect of a sharp pressure drop in the cutting stream 4, after it leaves the nozzle 2, is quite sufficient for partial or complete crystallization of the melt 12 or when the trap 6 is sufficiently removed from the jet forming nozzle 2 (when the duration of movement of the processing material to the workpiece 5 is sufficient to start or implementation of the process of crystallization of the working fluid), the refrigeration chamber 13 may not be needed.

The processing material used is a low-melting alloy, heavy, chemically inactive and non-toxic, for example, alloys with a density of about 8.8 g / cm ³ - Newton's alloy (composition - bismuth 50%, lead 31.2%, tin 18.8%, melting point 94 ° C), Rose alloy (composition - bismuth 50%, lead 25%, tin 25%, melting point 93 ° C), or Lichtenberg (composition - bismuth 50%, lead 30%, tin 20%, melting point 91 ° C). If it is possible to isolate the working area, then alloys with a lower melting point can be used, for example, Wood's alloy, Lipovitsa alloy, etc. with a melting point up to 70 ° C.

The heater 8 is selected so that operational melting of the particles of the hardened melt of the low-melting alloy (working fluid) trapped in 6 is ensured.

The nozzle diameter is determined by the following parameters:

firstly, and first of all, the larger the hole, the wider the flow through it and, consequently, the cut. The cutting accuracy will usually vary inversely with the diameter of the hole. As a rule, when cutting thin materials, the smaller the hole, the better the accuracy and possible detail, the less cutting medium is used per unit length of cut;

secondly, the larger the hole, the greater the mass flow of the jet stream and, therefore, the greater the cutting speed. Thus, the larger the hole, the better the cutting performance and the more cutting medium is used for the length of the cut.

The balance of these two conflicting requirements prevails over other requirements, which may affect the diameter of the hole.

In the present invention, nozzle diameters of 0.1 to 1 mm can be effectively used, but it is generally desirable to use diameters of 0.2 to 0.5 mm.

The hole may be formed from alloys of hard metals, materials having a hard surface, such as tungsten or silicon carbides, ceramic compositions, or crystalline materials, such as sapphire or diamond.

The distance from the nozzle exit to the workpiece surface is an important parameter for the quality of the cut. Although the quality of the cut, in particular the width and shape of the cut, will be significantly affected by the distance from the nozzle exit to the workpiece surface of up to 25 mm, the invention makes it possible to machine cutting at distances up to 250-300 mm. Although jet cutting can be used to cut materials up to 250 mm thick, this technology usually requires a “free gap” between the nozzle and the workpiece surface of no more than 25 mm.

Blast cutting in accordance with the invention can be used to cut any of the materials for which such technology has been used before. It should be noted that materials that are difficult to machine, including many metals and alloys, such as stainless steels, nickel alloys, titanium, ceramics and glass, rock materials, such as marble, granite and similar materials, and polymer composites and, in in particular, fiber reinforced layered polymeric materials are all efficiently cut with great accuracy in accordance with the present invention.

The implementation of the invention

Block 1 increasing the pressure of the liquid provides compression of the working fluid (molten alloy) to values of 0.8-2.0 kbar. The working fluid freely passes through the jet forming nozzle 2, without exerting an abrasive effect on the internal surfaces of the block 1 and its output jet forming nozzle 2 in contact with it, and leaves it in the form of a thin jet, the speed of which can vary from 50 to 1500 meters per second (preferably from 150 to 600 m / s) at the nozzle exit.

Jet 4 after leaving the jet forming nozzle 2 is instantly cooled, from a sharp pressure drop in it after departure from the nozzle, and also due to the intersection of the cooled zone during operation of the cooling chamber 13 (if used). This leads to crystallization of phases upon reaching the crystallization temperature of at least one of the alloy components, and solid inclusions appear in the composition of the jet.

Jet 4, in the composition of which an abrasive system of solid particles was formed, interacting with the workpiece 5, produces its effective destruction in the cutting zone (in the contact zone of the jet with the workpiece 5).

The spent working fluid containing particles of solidified melt trapped in the trap 6 is brought to the melting temperature of this alloy by a heater 8, preferably an electric one, made in the form of an inner lining of the bottom and walls of the trap 6. In this case, the “sawdust” of the workpiece 5 usually has a density less than the density of the working fluid, so they float in the melt, and then they are removed from the surface of the melt through the filter pipe 7. If the material of the workpiece 5 has a density greater than the density of the working fluid, then p iemnoe melt conduit opening 9 return to block 1 is provided with a mesh filter of known design (not shown).

The molten fusible alloy (working fluid), trapped in 6, is selected from it by a transfer pump 10 and returns to block 1 via the melt return pipe 9. Then everything is repeated.

To reduce the energy consumption of the cutting process, the melt return pipe 9 is equipped with a heat-insulating casing 11, which eliminates heat loss due to its removal to the surrounding space.

Drain pipe 3 provides emergency discharge of the working fluid in case of heater failure.

The stated offer provides the following:

- cutting and processing of materials is ensured by a renewable working medium - a low-melting alloy, which does not need to be specially prepared and changed after the resource has been exhausted, which ensures ecological cleanliness and economy of the declared proposal;

- due to the fact that the formation of the solid phase of the medium - crystals of the alloy components occurs at the moment of increasing the liquid volume after exiting the accelerating nozzle, the wear of the nozzle is minimal - unlike analogues in which the use of abrasive leads to rapid wear of the nozzle (within just a few hours and even minutes);

- thanks to the use of abrasive particles of the solid phase in the working fluid, there is an effective processing of the material.

Claims (2)

1. The method of jet processing of the workpiece, including the formation of a processing jet supplied from the nozzle to the workpiece using a fluid circulation system, characterized in that the fluid used is a molten fusible alloy, the hydrostatic pressure of which is increased before the formation of the processing jet, while cooling the processing stream of said molten alloy until it is partially crystallized; partially crystallized spent is collected th molten alloy particles preform, converted it into a liquid phase separated particles preform from the molten alloy and the latter is fed to the input circuit of the fluid system. 2. The method according to p. 1, characterized in that as a fusible alloy, a heavy, chemically inactive and non-toxic alloy is used.

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