Compression chamber, pressure booster, polishing device and method for increasing hydraulic oil pressure

Abstract

FIELD: precision machining.SUBSTANCE: invention relates to precision machining of internal channels. The compression chamber comprises the following elements arranged sequentially along the flow: a first rectilinear section with a length-to-diameter ratio of > 5, a second arcuate section made as a concave quarter of a circle, a third rectilinear section with a length-to-diameter ratio of < 3, wherein the first rectilinear section and the third rectilinear section are arranged coaxially and in parallel, and the outlet end of the third rectilinear section is the outlet opening of the compression chamber, the ratio of the cross-sectional area of the first rectilinear section and the third rectilinear section is 2.5-3.EFFECT: combined action of all sections of the compression chamber structure ensures the output of hydraulic oil at high and stable pressure. A pressure booster, a polishing device and a method for increasing hydraulic oil pressure are also presented.12 cl, 3 dwg

Description

[0001] Field of technology

[0002] The present invention relates to the field of precision machining of internal passages, and in particular, to a compression chamber, a pressure intensifier, a polishing device and a method for increasing the pressure of hydraulic oil.

[0003] State of the art

[0004] Parts with a design with complex internal microchannels are widely used in aerospace, shipbuilding, nuclear, automotive, toolmaking and other industries. In particular, parts of hydrodynamic systems often have a complex design of internal cavities with thin channels, deep micro-holes and their connections, which perform the functions of transporting fluids, exchanging them or creating hydraulic pressure, for example: fuel injectors of various aircraft / space / marine / automotive engines, heat exchangers, hydraulic units, throttles for controlling the oil circuit, etc.

[0005] Technological processes capable of processing complex internal microchannels include precision machining, femtosecond laser / water-guided laser / long-pulse laser machining, electrical discharge machining, and additive manufacturing (3D printing). With the exception of additive manufacturing, the structure of complex internal microchannels processed using other technologies alone is relatively simple, with a relatively small length-to-diameter ratio. Therefore, complex internal microchannels can only be processed using welding and other combined technologies.

[0006] During precision machining of internal microchannels, burrs, sharp bending angles, steps from contact with the cutting tool, and other problems may appear. Adhered residual granules and a "stepped" surface effect may appear on the surface of internal channels after machining with a femtosecond laser. A remelting layer may appear on the surface of internal channels after machining with a water-guided / long-pulse laser.

[0007] Additive manufacturing (3D printing) is a technology that dissects a complex 3D part model into 2D structures by sequentially depositing layers to create a mold. This method enables the solid-mold production of parts with complex microscopic internal channels, leading to its growing use in industries such as aerospace, automotive, and moldmaking.

[0008] However, since additive manufacturing technology has a temperature gradient, layer-by-layer molding and other technological features during the molding process of the part, this leads to the presence of half-sintered and glued powder granules on the surface of the internal channels of the parts, as well as to the effect of “stepped” surface.

[0009] Burrs from machining, sintered particles adhering to internal channels during femtosecond laser processing, and powder adhering to the surface of internal channels during additive manufacturing all impact the serviceability and safety of components. When fluid is introduced into the channels, high frictional velocities with the surface layer cause burrs, adhering residual granules, or adhered powder to dislodge. These can accumulate in excess and be carried by the fluid, clogging the oil circuit or causing mechanical wear and damage, leading to serious accidents. A highly rough internal surface easily becomes a source of fatigue cracks during long-term operation, which in high-temperature oil systems also easily leads to carbon deposits.

[0010] Cutting tool marks on the channel surface, sharp angular transitions, stepped irregularities in tool change zones, and the "stepped" surface of internal channels during femtosecond laser processing and additive manufacturing cause a significant deterioration in hydrodynamic characteristics: the formation of turbulent eddies, the emergence of reverse flow zones, an increase in the hydraulic resistance coefficient, which in turn causes vibration and a reduction in the service life of the part.

[0011] A rough surface creates numerous cavitation bubbles, which affect combustion and hydrodynamics, and in some cases lead to cavitation corrosion. For some components made of certain materials (such as hollow blades), the surface of the remelted layer in the internal channels and connecting holes is prone to microcracks, leading to premature failure. Therefore, it is necessary to reduce the thickness of the remelted layer or eliminate its occurrence entirely.

[0012] In this regard, when processing the surface of the internal channels of parts with moving fluids by machining, femtosecond laser / water-guided laser / long-pulse laser processing, electrical discharge machining and additive manufacturing (3D printing), such adverse phenomena as burrs, powder residues or sintered granules, rough surface, remelting layer, etc. will occur, which requires the use of suitable polishing technologies to eliminate such adverse phenomena so as to ensure that the product meets the performance requirements.

[0013] However, at present, there is no technology that can effectively polish the surface of complex internal microchannels, which leads to the following results:

[0014] The parts produced by additive manufacturing have an internal surface with an initial average roughness of Ra ≥ 6.3 μm, but do not achieve the optimal roughness of Ra ≤ 1.6 μm;

[0015] The parts processed by laser or EDM do not achieve the optimum roughness of Ra ≤ 0.8 μm;

[0016] machined parts with complex internal microchannels with optimal internal channel roughness Ra ≤ 0.4 μm are also absent.

[0017] Currently, complex microchannel shapes such as S-shaped, L-shaped, U-shaped, and O-shaped curved channels cannot be machined using linear tool movement, and such parts can only be produced using additive manufacturing. However, even for such complex microchannels produced by additive manufacturing, it is not possible to achieve an optimal surface roughness of Ra ≤ 1.6 μm.

[0018] The essence of the invention

[0019] The purpose of the present application is to provide a compression chamber, a pressure intensifier, a polishing device and a method for increasing the pressure of hydraulic oil.

[0020] In a first aspect, the present application provides a compression chamber including the following elements arranged sequentially downstream: a first rectilinear section 11 with a length-to-diameter ratio of >5; a second arcuate section 12 formed as a concave quarter circle; and a third rectilinear section 13 with a length-to-diameter ratio of <3. The first rectilinear section and the third rectilinear section are arranged parallel and coaxially; and the outlet end of the third rectilinear section 13 is an outlet of the compression chamber; the ratio of the cross-sectional area of ​​the first rectilinear section 11 and the third rectilinear section 13 is 2.5-3.

[0021] In the technical solution of the embodiments of the present application, by using a combined structure in the compression chamber consisting of a first rectilinear section, a second arcuate section made as a concave quarter of a circle, and a third rectilinear section, a high and stable pressure of the output flow of hydraulic oil is ensured after passing through the pressure booster.

[0022] The principle is as follows: the first straight section compensates for the loss of volume of hydraulic oil, which becomes compressible liquid under high pressure, due to the increased piston stroke.

[0023] The second arc-shaped section with a concave arc shape increases the contact area for pressure dissipation, preventing excessive lateral loads from concentrating on the walls. It also helps stabilize the flow and direct the fluid, ensuring a smooth, low-velocity movement toward the throat. Furthermore, the concave arc creates a compression effect, promoting flow compaction and increasing its stability.

[0024] The third straight section is designed with a length-to-diameter ratio of <3, providing additional pressure stabilization and minimizing output pressure fluctuations by shortening the flow path, preventing the development of turbulence in the boundary layer. The shortened length of the third section promotes laminar fluid flow, ensuring a stable hydraulic oil output and improving control accuracy and final hydraulic pressure stability. The first straight section and the third straight section are arranged parallel and coaxially, with a cross-sectional area ratio of 2.5-3. This design further ensures stable flow and increased hydraulic oil pressure within the compression chamber.

[0025] Through the above-described interaction mechanisms, the output pressure in the compression chamber is achieved in the range of 2.5 MPa - 45 MPa. At the same time, the adjustment accuracy is 0.01 MPa - 0.1 MPa, with an output pressure deviation of <0.1%, ensuring high and stable output pressure.

[0026] In some embodiments, the ratio of the length of the first straight section, the radius of the second arcuate section and the length of the third straight section is 11:5:4.

[0027] In some embodiments, the radius of rounding at the junction of the first straight section and the second arcuate section is 0.1 mm - 0.5 mm.

[0028] In some embodiments, the compression chamber is made of steel.

[0029] In some embodiments, the compression chamber is made of grade 45 steel.

[0030] In some embodiments, the roughness of the inner wall of the compression chamber is Ra 0.1 μm-0.4 μm, the ovality ≤100 μm, the cylindricality ≤200 μm.

[0031] In a second aspect, the present application provides a pressure booster comprising: a compression chamber as described in the first aspect, wherein the compression chamber contains hydraulic oil. A piston is located within the compression chamber and is designed to receive a driving force on one side, move progressively along the walls of a first rectilinear section of the chamber, and displace hydraulic oil located on the opposite side of the piston through an outlet opening of a third rectilinear section.

[0032] In some embodiments, the piston receives a driving force of 1 MPa - 15 MPa, the output pressure is 2.5 MPa - 45 MPa.

[0033] In a third aspect, the present application provides a polishing device comprising a drive mechanism; a sealing system containing a polishing material for polishing; a pipeline system connected to the sealing system; wherein the drive mechanism transmits force to the sealing system, causing the polishing material contained therein to move through the pipeline system to the workpiece. The drive mechanism comprises a hydraulic pump and a pressure intensifier mentioned in the second aspect. The hydraulic pump generates a drive force for the piston of the pressure intensifier, and hydraulic oil is supplied to the system after the pressure in the intensifier increases.

[0034] In some embodiments, the drive mechanism further comprises an electric motor and a vertical plunger pump. The hydraulic pump, driven by the electric motor, moves the piston, and hydraulic oil, after increasing pressure in the pressure booster, is supplied to the vertical plunger pump. The vertical plunger pump is connected to the sealing system and exerts pressure on the polishing material contained therein.

[0035] In some embodiments, the drive mechanism creates a pressure in the sealing system of > 50 MPa, with an adjustment accuracy of 0.01 MPa - 0.1 MPa and an output pressure deviation of < 0.1%.

[0036] In a fourth aspect, the present application provides a method for increasing the pressure of hydraulic oil, which comprises moving hydraulic oil sequentially through a first straight section, a second arcuate section, and a third straight section with increasing pressure, wherein the length-to-diameter ratio of the first straight section is >5, the second arcuate section is designed as a concave quarter circle, and the length-to-diameter ratio of the third straight section is <3. The first straight section and the third straight section are arranged parallel and coaxially. The cross-sectional area ratio of the first straight section and the third straight section is 2.5-3.

[0037] Description of drawing figures

[0038] The above and other features, characteristics and advantages of the present invention will become more apparent from the following description in conjunction with the drawings and embodiments, and it should be noted that all the attached figures of the drawings are for illustrative purposes only, are not drawn to scale and should not be interpreted as limiting the actual scope of legal protection of the invention.

[0039] Fig. 1 is a schematic block diagram of a polishing method according to some embodiments of the invention.

[0040] Fig. 2 is a schematic diagram of the structure of a polishing device according to some embodiments of the invention.

[0041] Fig. 3 is a schematic diagram of the structure of a compression chamber of a pressure booster according to some embodiments of the invention.

[0042] Preferred embodiments of the present invention

[0043] This description discloses numerous different ways of implementing technical solutions or embodiments. To simplify the disclosure, specific examples of elements and their arrangements are described below. Naturally, these examples are provided for illustrative purposes only and do not limit the scope of the present invention.

[0044] The terms “one embodiment,” “an embodiment,” and / or “some embodiments” in this application mean that a particular characteristic, structure, or feature pertains to at least one embodiment of the present invention.

[0045] It should be especially emphasized and taken into account that the terms “embodiment variant”, “one embodiment variant”, “alternative embodiment variant” used in the present description in various places, when mentioned twice or multiple times, do not necessarily refer to the same embodiment of the invention.

[0046] Furthermore, some features, structures, or characteristics mentioned in various embodiments of the present invention, including the current, subsequent, and additional embodiments, may be suitably combined.

[0047] This application uses flowcharts to explain operations performed by a device according to embodiments of the invention.

[0048] Please understand that the preceding or following operations are not necessarily performed in the exact sequence described. Other operations may be added to these processes, or some individual or multiple operations may be deleted from these operations.

[0049] The average roughness listed below is an index obtained by measuring multiple surface areas and calculating the average value to characterize the roughness of the measured surface.

[0050] The optimal roughness value specified below is determined by measuring multiple surface areas and selecting the minimum value, which is then used to characterize the measured surface. For example, when measuring roughness, a section of a piping system 8 mm long might be selected. During the measurement, several such 8 mm sections are selected, a measurement is taken at each, and the minimum value, representing the optimal roughness, is selected from the resulting values.

[0051] The parts with complex internal microchannel structures have been widely used in aerospace, shipbuilding, nuclear, automobile, tool making and other industries, but current processing technologies, such as precision machining, femtosecond laser / water-guided laser / long-pulsed laser processing, electrical discharge machining, additive manufacturing (3D printing), when processing the surface of internal channels in parts with moving fluids, may have problems such as burrs, bonded powder or sintered granules and other foreign residual substances, rough surface, remelting layer, etc., which requires appropriate polishing technologies to remove such adverse effects, so as to ensure that the product performance requirements are met.

[0052] Currently, there are no additively manufactured parts with internal microchannels where the optimal channel surface roughness is ≤1.6 μm. There are also no parts with laser- or electrical discharge machining-processed internal microchannels where the optimal channel surface roughness is ≤0.8 μm. Furthermore, for mechanically machined parts with internal microchannels, the optimal channel surface roughness of ≤0.4 μm has not been achieved.

[0053] The peculiarities of internal microchannels with complex shapes such as S-, L-, U-, and O-shaped ones preclude the use of linear tool motion machining. These shapes can only be created using additive manufacturing, but parts with optimal internal channel roughness produced by this method have not yet been produced.

[0054] After conducting in-depth research and comparisons of various internal channel polishing methods, the inventors found that for parts with internal channels having a large diameter (>3 mm), a small length-to-diameter ratio (<50:1) and a nearly straight profile, standard processing methods such as manual grinding, chemical machining, electrochemical machining, plasma machining, magnetic machining, magnetorheological machining, abrasive flow machining, waterjet machining or ultrasonic machining can be used.

[0055] However, for processing microchannels with a smaller diameter (≤3 mm) and a large length-to-diameter ratio (≥50:1), standard methods are not effective enough or technologically complex.

[0056] (1) When applying abrasive flow machining technology using a semi-solid soft paste polishing material with relatively high hardness to polish internal cavities through an extrusion polishing mechanism, the authors found that this technology, based on the movement of a fluid with an extremely low Reynolds number, has great difficulty uniformly machining complex, long microchannels. This leads to blockages in bends and "dead zones," and forced passage can cause channel deformation or even destruction.

[0057] Even when forced to pass the polishing material through internal microchannels with a length-to-diameter ratio ≥50:1, a sharp decrease in pressure and flow velocity is observed as the flow path increases. This leads to "overpolishing" at the channel outlets and "underpolishing" of the internal areas due to significant pressure and velocity losses. Furthermore, material containing water-insoluble colloidal abrasive particles tends to settle in bends and "dead zones" within the microchannels, making subsequent removal extremely difficult or impossible.

[0058] (2) Abrasive jet technology, also known as micro-abrasive solution jet polishing, high-speed jet polishing, and high-speed water-particle polishing, uses a water jet to generate pressure on nozzles. This jet ejects a stream of water containing abrasive particles, using the kinetic energy to erosively remove material from the surface of the workpiece. The water-atomizing nozzle is held close to the surface of the workpiece. However, due to the need to maintain a small distance between the nozzle and the surface of the workpiece, this technology encounters difficulties when machining microchannels with small diameters (≤3 mm) and large length-to-diameter ratios (≥50:1).

[0059] (3) Magnetic polishing technology can only achieve light polishing of the surface of internal channels with a bore diameter > 3mm and a direction close to a straight line. It cannot effectively polish the surfaces of complex internal microchannels with a bore diameter ≤3mm and three-dimensional spatial orientation, including S-shaped, L-shaped, U-shaped, O-shaped, and spiral curves. This is because magnetic polishing is a soft processing method using relatively large magnetic abrasive particles.The principle is that the protrusions and depressions of the surface are simultaneously processed under the action of an external magnetic field, so such soft processing methods can only achieve minor polishing of the surface, and, despite the large volume of material removed, they also cannot significantly correct the “stepped” effect of the surface, reduce its roughness and remove powder, particles and burrs stuck to the surface on a large scale.

[0060] Furthermore, this method, limited by the movement of the magnetic field, is also unable to effectively process complex internal microchannels with three-dimensional spatial geometry present in the parts.

[0061] (4) When using the chemical polishing method, when the hole diameter of the internal channels is very small, the volume of the etching solution that can be accommodated is relatively small, which leads to low efficiency of the chemical polishing method, up to the occurrence of local reactions with the accumulation and clogging of air bubbles, which makes polishing impossible.

[0062] (5) When using electrochemical, plasma or ultrasonic polishing methods, due to the difficulty of placing profile electrodes inside narrow channels with three-dimensional spatial geometry, including S-shaped, L-shaped, U-shaped, O-shaped and spiral bends, polishing complex internal microchannels becomes impossible.

[0063] Furthermore, for points (4) and (5), chemical, electrochemical, and plasma polishing methods can cause numerous defects, such as corrosion and the formation of altered layers in the microstructure of the channel base material. Etching solutions and reaction gases also have adverse effects on the environment and equipment.

[0064] However, (4) and (5) are soft processing methods, and they also encounter the same shortcomings as (3), only slightly improving the polishing quality, and despite the large volume of material removed, they also cannot significantly improve the “step” effect of the surface, reduce the surface roughness, or significantly remove the powder, particles, and burrs adhered to the surface.

[0065] To summarize the above, through in-depth research, the inventors have found that all of the above processing methods in relation to structures with internal microchannels encounter problems such as difficulty in penetrating into the microchannels for polishing and / or imperfect polishing quality, and therefore can be difficult to apply to polishing processing of internal microchannels.

[0066] Based on the above, the inventors conducted further research and developed a method for polishing the surface of microchannels. This method utilizes a two-phase polishing material with a liquid phase viscosity of less than 1000 cP, ensuring a flow rate exceeding 5 m / s and creating a hydrodynamic saturation regime by delivering the material in a volume corresponding to the maximum channel capacity. This, combined with controlled pressure, creates conditions for effective polishing of the internal surfaces. The combination of low liquid phase viscosity, polishing material flow rate, and saturated flow solves the complex problems associated with polishing microchannels.

[0067] The principle is that, thanks to the combined action of the low viscosity of the liquid phase, the liquid flow rate, and the saturated flow, the polishing material can freely penetrate complex microchannels and transform into a non-Newtonian fluid. The liquid wall layer, oriented parallel to the microchannel surface, creates conditions for the "instrumental" action of the abrasive particles, ensuring selective processing of surface irregularities through targeted shear friction.

[0068] The combined effect of low viscosity (<1000 cP), high flow velocity (>5 m / s) and saturated flow generates directed micro-shear forces in the polishing material, providing a controlled cutting effect of abrasive particles on the surface of internal microchannels, achieving the most optimal roughness (Ra 0.05 μm) regardless of the material of the workpiece, which is fundamentally different from traditional abrasive processing methods based on volumetric deformation and leading to surface defects on soft materials.

[0069] The principle is that the cutting tool using the abrasive particle flow technology is the volumetric force generated by the pressure of abrasive particles on the surface, so when processing low-hardness metals and high-molecular flexible materials, dents and defects with roughness (Ra> 0.8 μm) easily occur.

[0070] In abrasive jet technology, cutting force is generated by the erosive action of abrasive particles upon impact with the surface. When machining soft metals, this results in a rough surface texturing effect with a roughness of Ra > 0.8 µm.

[0071] The inventors discovered that polishing a part requires high-speed, high-pressure polishing material, requiring the polishing device's drive mechanism to deliver very high and stable polishing material pressure. However, existing piston-based pressure boosters struggle to deliver stable, high hydraulic pressure.

[0072] Based on these studies, the inventors developed a compression chamber of a pressure booster, which, through the joint interaction of a first straight section, a second arc-shaped section formed in the form of a quarter circle and having a concave shape, and a third straight section, ensures a high and stable pressure of the output flow of hydraulic oil after passing through the pressure booster.

[0073] The principle is as follows: the first straight section compensates for the loss of hydraulic oil volume, which becomes a compressible flow under high pressure due to the increased piston stroke. The second arcuate section, with its concave arc, increases the contact area for pressure dissipation, preventing excessive lateral loads from concentrating on the walls. It also helps stabilize the flow and direct the fluid, allowing it to move at a reduced velocity into the throat area. Furthermore, the concave arc creates a compression effect, promoting flow compaction and increasing its stability.

[0074] The third straight section is designed with a length-to-diameter ratio <3, providing additional pressure stabilization and minimizing output pressure fluctuations by shortening the flow path, preventing the development of turbulence in the boundary layer. The shortened length of the third section promotes laminar fluid flow, ensuring a stable hydraulic oil output and improving control accuracy and final hydraulic pressure stability.

[0075] The first straight section and the third straight section are arranged parallel and coaxially, and their cross-sectional area ratio is 2.5-3. This design further ensures stable flow and increased hydraulic oil pressure within the compression chamber.

[0076] The above-described interaction mechanisms achieve an output pressure in the compression chamber in the range of 2.5 MPa - 45 MPa. The adjustment accuracy is 0.01 MPa - 0.1 MPa, with an output pressure deviation of <0.1%, ensuring high and stable output pressure. Ensuring a stable speed and flow rate of polishing material during processing guarantees the polishing effect.

[0077] It can be understood that the embodiment of the compression chamber of the pressure intensifier presented in this application provides high and stable pressure of the polishing material during the operation of the polishing device, in order to set the polishing material in motion at a high speed of >5 m / s during the processing, and also stably ensure the point processing of the protrusions on the surface of the part due to the shear friction of the non-Newtonian fluid, which has a rigidity comparable to cutting tools, and creates high micro-cutting ability of abrasive particles.

[0078] It should be understood that the embodiments disclosed in the present application are applicable not only to the described polishing method and polishing device, but can also be used in other installations for increasing the pressure of hydraulic oil in order to create a high and stable hydraulic pressure.

[0079] First, let us take a look at the method for polishing the surface of internal microchannels and the polishing device to which the pressure intensifier in the present invention is applicable, which can clearly demonstrate its performance characteristics.

[0080] Figure 1 shows a method for polishing the surface of an internal channel, which includes the following steps:

[0081] Uses a two-phase polishing material consisting of a liquid and a solid phase. The viscosity of the liquid phase of the polishing material is less than 1000 cP, and the solid phase contains abrasive particles.

[0082] A given pressure is applied to the polishing material, ensuring a flow rate in the microchannels of >5 m / s, and the material is supplied to the microchannel inlet in a saturated flow mode, reaching the maximum throughput capacity of the microchannel cross-section, which creates a hydrodynamic saturation mode inside the channel.

[0083] The specified liquid phase has a viscosity of <1000 cP. All viscosity values ​​given in this application refer to the Ubbelohde viscosimetric viscosity measured under standard conditions (temperature of about 25°C).

[0084] For different materials, sizes and initial average roughness of microchannels, the optimal value of viscosity of the liquid phase used in the polishing method can be determined by gradually increasing the viscosity starting from a specified minimum value.

[0085] According to embodiments, the minimum viscosity value is approximately 50 cP. Based on extensive experimental data, the inventors have determined that for microchannels made of the following common materials—titanium alloys, heat-resistant alloys, steel alloys, ceramic materials, aluminum alloys, and polymeric materials—the viscosity of the liquid phase should be at least 50 cP to achieve the target roughness values ​​after polishing.

[0086] The specified viscosity limit of 1000 cP is usually not optimal, but represents the maximum permissible limit to ensure continuity, uninterrupted flow, and stability of the polishing material in the microchannels.

[0087] In an embodiment of the invention, the liquid phase is an aqueous base, in particular a certain thickening agent is added to deionized water to give the aqueous base a certain viscosity.

[0088] Using a water-based liquid phase offers several advantages: low cost, availability, eco-friendliness, and ease of cleaning the polishing material after polishing. However, it's important to note that the liquid phase is not limited to a water-based one. Any liquid with a viscosity of μ<1000 cP can also be used.

[0089] The materials of the abrasive particles that make up the solid phase can be selected from common abrasive materials, such as carbide composites: silicon carbide, tungsten carbide, etc.; heat-resistant oxides: aluminum oxide, zirconium oxide, cerium oxide, etc.; nitride-based ceramics: boron nitride, chromium nitride, etc.; natural minerals: diamond / sand, mica, quartz, olivine, etc.

[0090] Preferably, one material or a combination of several materials such as diamond / sand and heat-resistant oxides can be selected.

[0091] When selecting the abrasive particle size and mass concentration, the optimum range is determined by successively increasing from the minimum base value.

[0092] If the diameter and mass concentration of abrasive particles are below the lower limit, the expected polishing effect is not achieved, and the microchannel surface does not achieve the target roughness level. The principle is that if the particle size is too small, the particle mass is insufficient to generate sufficient kinetic energy for effective polishing.

[0093] If the particle concentration is too low, the probability of processing the points on the surface decreases, which also leads to a decrease in efficiency.

[0094] When selecting abrasive particle size and mass concentration, it's common to start with the lower limit and gradually increase it to the optimal range to ensure polishing efficiency. Therefore, the minimum microchannel diameter to particle size ratio is 20 (the channel must allow at least 20 abrasive particles to pass through in parallel without clogging), the maximum particle size is 1 / 20 of the channel diameter, and the minimum is 1 / 5 of the maximum.

[0095] The minimum mass concentration of abrasive particles is typically 10 g / L. The lower limit is generally chosen with caution, as the system operates under high pressure. If clogged with abrasive particles, this can lead to failure of both the workpiece and the device itself, and in extreme cases, to pressure failure or even explosion.

[0096] Thus, starting from the set lower limit, the abrasive particle size and mass concentration gradually increase until the following negative effects occur: a significant increase in hydraulic resistance due to excessive particle size, excess concentration, and a reduction in flow velocity and flow rate. The likelihood of abrasive particle collisions also increases, further reducing flow velocity and impairing polishing efficiency. Therefore, the optimal parameter values ​​are determined experimentally based on the lower limit.

[0097] The polishing material is subjected to a predetermined pressure, which ensures its movement within the microchannel at a speed of >5 m / s. Here, the predetermined pressure refers to the pressure applied at the initial stage of the polishing process, at which point the polishing material is already moving within the microchannel at the specified speed. As the polishing process progresses, as the microchannel surface roughness decreases while maintaining the same pressure, the speed of the polishing material within the microchannel gradually increases.

[0098] It should be understood that since the achievable flow rate is a range of values, the set pressure in this case is also considered as a range of values, and not a fixed value applied to the polishing material.

[0099] Immersion measurement methods cannot be used to measure the movement speed of polishing material inside microchannels, otherwise abrasive particles may damage any sensors and probes.

[0100] Ultrasonic velocity measurement can be used, as well as the Hagen-Poiseuille law for viscous liquids. These methods help determine flow parameters without the need for direct intervention, which is important for equipment safety in highly abrasive polishing media.

[0101] for indirect measurement;

[0102] where in the formula D is the diameter of the internal microchannel,

[0103] l– microchannel length,

[0104] p– pressure difference between the two ends of the microchannel, i.e. hydraulic pressure,

[0105] Re– Reynolds number,

[0106] u m – the flow rate of the liquid phase of a two-phase water-based flow,

[0107] p1– density of the liquid phase.

[0108] The speed of the liquid phase is approximately equal to the speed of the polishing material.

[0109] The flow rate of the polishing material > 5 m / s corresponds to the critical condition for the formation of a non-Newtonian fluid, theoretically substantiated and confirmed by experimental data by the authors of the invention.

[0110] According to the literature on engineering fluid dynamics (for example, bibliographic source: Yang Shuren, Wang Zhiming, He Guangyu et al. Engineering Fluid Mechanics [M]. Oil Industry, 2006.), the limiting velocity at which water with a viscosity of 1 cP transitions to a non-Newtonian fluid state is >16.6 m / s, while the lower limit value of the viscosity of the liquid phase in the present embodiments of the invention is 50 cP, which is higher than 1 cP. Therefore, the limiting velocity for the occurrence of a non-Newtonian fluid state in this case will be <16.6 m / s.

[0111] At the same time, in combination with practical results, the inventors found that at a speed of less than 5 m / s, it is impossible to achieve the ideal processing effect, so the limit value is 5 m / s.

[0112] The polishing material enters the microchannel through one of its ends with a flow reaching the maximum flow capacity for a given channel diameter (saturated flow regime), creating an increased pressure inside the channel (a "locked" state), known in the technical field as the hydrodynamic saturation regime.

[0113] The meaning of the terms "maximum flow capacity" and "saturated flow regime" refers to the state in which the flow completely fills the cross-section of the channel and the maximum possible linear density of liquid molecules in the cross-section is achieved.

[0114] It should be understood that the use of the above-described embodiment of the polishing method has the following beneficial effects:

[0115] The use of a polishing material with a liquid phase viscosity of <1000 cP in combination with a two-phase flow velocity in microchannels of >5 m / s and feeding the material into the microchannel through one of its ends in the saturated flow mode creates a hydrodynamic saturation mode.

[0116] Thus, the combination of low viscosity of the liquid phase, high liquid velocity and saturated flow mode makes it possible to effectively solve the problem of polishing microchannels.

[0117] The principle is as follows: due to the combined effect of low liquid viscosity, high flow rate, and saturated flow, the polishing material easily penetrates microchannels and creates a non-Newtonian fluid state within. The liquid wall layer moves parallel to the microchannel surface, while the abrasive particles in the solid phase act as "cutting tools," performing targeted machining of the surface protrusions.

[0118] This process overcomes the problem of traditional soft machining, which simultaneously processes both peaks and valleys, resulting in only minor surface polishing. Furthermore, regardless of the microchannel material, the micro-cutting forces generated between the abrasive particles and the microchannel surface achieve an optimal surface roughness corresponding to the average contact length with the abrasive cutting edges. This overcomes the limitations of abrasive flow and waterjet machining, where the polishing mechanism relies on the volumetric force generated by the pressure of the abrasive particles on the surface, leading to the formation of pits and defects on low-hardness metals and flexible polymer materials (Ra > 0.8 μm).

[0119] Furthermore, thanks to the low-viscosity, high-flow hydrodynamic machining method, areas of the channel's inner surface, such as steps, sharp corners, and geometric contour curvatures that do not conform to the principles of hydrodynamics, are subjected to more intensive polishing. As a result, inflection points, sharp edges, the curvature of the inner channel, and the hole profile acquire a streamlined geometric shape, significantly improving the fluid flow characteristics within the channel.

[0120] Furthermore, the above-described embodiment utilizes the flow velocity of the polishing material to form a non-Newtonian fluid with a hardness comparable to that of the cutting tool. This, combined with the mechanical action of the abrasive particles through shear friction, enables targeted machining of surface protrusions. The maximum flow velocity for this process is 5 m / s.

[0121] Regarding the processing time of the polishing material on the internal microchannel, it is allowed for the polishing material to process the internal microchannel for a standard period of time until the target value of the optimal surface roughness of the internal microchannel is reached.

[0122] The standard time interval can be a preset continuous period or an intermittent one consisting of several stages. It can also be an unspecified continuous time interval during which the polishing material flow rate or volume within the microchannel is measured after the polishing process begins. If the flow rate or volume reaches values ​​corresponding to the target level of optimal microchannel surface roughness, the polishing process is automatically stopped.

[0123] For example, in some embodiments, after the start of processing, the flow rate or volume of polishing material in the microchannel is measured, allowing for an indirect assessment of whether optimal surface roughness has been achieved. When the flow rate or volume reaches a preset value corresponding to the target roughness level, the polishing process can be stopped manually or automatically.

[0124] The target optimal surface roughness value in this context is not limited to direct measurement of the roughness itself. It can also be characterized indirectly, for example, through parameters such as the flow rate or volume of polishing material flowing within the microchannel, as described previously.

[0125] The specified target value typically represents the established optimal microchannel surface roughness required for the final result. However, this does not preclude the possibility of subsequent polishing steps after the steps described. In this case, the target value will not represent the final optimal roughness, but rather the intermediate requirements corresponding to this processing step.

[0126] To summarize, the above-described embodiment of the polishing method provides a solution to the long-standing industry problem of processing microchannels with a diameter of ≤3 mm and a length-to-diameter ratio of ≥50:1.

[0127] In some embodiments, Fig. 2 shows a polishing device 100 that includes a drive mechanism 101, several sealing systems 102, and several piping systems 103.

[0128] Each sealing system 102 includes a piston 21 and a cylinder 18 that interacts with the piston 21. The cylinder serves to accommodate the polishing material 8 used in the polishing process. A drive mechanism 101 is connected to one end of the piston 21 and transmits the drive force necessary to push the polishing material 8 through the outlet 190 of the cylinder 18.

[0129] Each pipeline system 103 supplies polishing material 8 from the corresponding sealing system 102 to different openings of the workpiece 34 with internal channels. As shown in Fig. 2, one unit consisting of the sealing system 102 and the pipeline system 103 is connected to the inlet opening of the workpiece 34, the second unit consisting of the sealing system 102 and the pipeline system 103 is connected to the outlet opening of the workpiece 34. Thus, the sealing systems communicate through the internal channels of the workpiece 34. The upper end of the pipeline system 103 is connected to the outlet opening 190 of the sealing system 102. The lower end of the pipeline system 103 is intended to supply polishing material 8 to the workpiece 34 with internal channels.

[0130] The drive mechanism 101 can be represented by a hydraulic system, as shown in Fig. 2. It includes an electric motor 1, a hydraulic tank 2, a hydraulic pump 3, a pressure amplifier 6, a vertical plunger pump 5 and an oil pipeline 4. The electric motor 1 drives the hydraulic pump 3, which extracts hydraulic oil with a certain pressure from the tank 2. After the oil pressure is increased by the amplifier 6, it is transported to the vertical plunger pump 5.

[0131] Vertical plunger pump 5 is connected to piston 21 via ball joint 13, enabling its actuation. This allows piston 21 to expel polishing material 8 through outlet 190 of cylinder 18. The use of a hydraulic system with an electric motor ensures not only high traction force but also high force precision.

[0132] The polishing mechanism shown above ensures high pressure and high flow rate of polishing material during the polishing process. The pressure supplied to piston 21 by vertical plunger pump 5 should reach > 50 MPa and remain stable. Regarding amplifier 6, the pressure required to supply vertical plunger pump 5 should reach 2.5 MPa - 45 MPa, with an adjustment accuracy of 0.01 MPa - 0.1 MPa and an output pressure error of <0.1%, ensuring a very high and stable output pressure.

[0133] As shown in Fig. 3, the pressure booster 6 includes a compression chamber 61, a piston 62 and a hydraulic oil 63. The piston 62 and the hydraulic oil 63 are located inside the compression chamber 61.

[0134] Piston 62, under the action of a driving force on one side, moves along the wall of compression chamber 61, causing hydraulic oil 63 located on the other side of piston 62 to be discharged under high pressure from the pressure booster.

[0135] As shown in Fig. 2, the electric motor drives the hydraulic pump, which transmits a driving force to piston 62 in the range of 1 MPa to 15 MPa. The electric motor / hydraulic pump combination not only provides a high driving force but also ensures high control accuracy.

[0136] In this context, pressure booster 6 means a device for increasing the pressure of incoming hydraulic fluid.

[0137] The piston 62 is a member that can perform a reciprocating motion inside the compression chamber 61.

[0138] As shown in Fig. 3, in some embodiments, the compression chamber 61 includes sequentially arranged downstream (upstream and downstream) elements: a first rectilinear section 11, a second arcuate section 12, and a third rectilinear section 13. In this context, the upstream and downstream flows are determined relative to the direction of movement of the hydraulic oil inside the compression chamber 61, that is, the fluid moves from the upstream to the downstream. In this case, the inner wall of the first rectilinear section 11 is designed to move the piston 62 along the wall, which ensures the expulsion of the hydraulic oil 63.

[0139] It should be understood that the description of straight and arc-shaped sections, as well as straight lines and arcs, represent a figurative description of the cross-section of the compression chamber 61. The actual structure of the compression chamber 61 is a spatial chamber formed by rotating the aforementioned straight lines and arcs around the axis of the pressure intensifier by 360°. For example, rotating a straight line around the axis by 360° results in the formation of a cylindrical chamber.

[0140] The ratio of the length of the first straight section 11 to the diameter is >5. If the length of the corresponding piston 62 is 40 mm, then the length of the first straight section 11 (Ls1) typically exceeds 120 mm. This is because the volumetric loss of the compressible fluid must be taken into account when calculating the length of the first straight section 11. Under high hydraulic pressure, the hydraulic oil 63 becomes a compressible fluid, which leads to volumetric losses, and the increased piston stroke length helps compensate for these losses.

[0141] The second arcuate section 12 is a concave arc corresponding to 1 / 4 of a circle, i.e., it is designed as a concave quarter circle. The narrowed throat region functions to restrict fluid flow and increase hydraulic pressure. By "concave arc" here is meant that the arc faces the inside of the compression chamber 61, not the outside. In other words, the center of the arc's circumference is located outside the compression chamber 61. The term "concave quarter circle" means that this arc is 1 / 4 of a circle, i.e., the corresponding central angle is 90°.

[0142] Since the first straight section 11 and the third straight section 13 have different diameters but are arranged coaxially and parallel, an arcuate section corresponding to 1 / 4 of the circle is required to ensure the smooth connection of their structure.

[0143] The concave arc design has a larger surface area, preventing high localized wall pressures from lateral forces. Furthermore, the change in forces and angles between fluid elements occurs over a longer flow path, ensuring stability and uniformity.

[0144] Another function of the arc section is to direct the flow of hydraulic oil, ensuring its smooth movement at low speed to the filler neck.

[0145] In addition, the concave arc creates a compression effect, helping to compact the flow and improve its stability.

[0146] The third straight section 13 represents the final stroke of the hydraulic oil after its pressure has increased. The lower end of the third straight section 13 is the outlet end of the compression chamber 61.

[0147] The ratio of the cross-sectional area S1 of the first straight section 11 to the cross-sectional area S3 of the third straight section 13 is 2.5-3, i.e. the pressure increase coefficient is 2.5-3. Length L s3 third straight section 13, as a rule, less than 50 mm.

[0148] The inventors found that if the stroke of the hydraulic oil in the third straight section 13 is too long, this leads to an increase in the thickness of the boundary layer, the formation of turbulence, and instability of the output hydraulic pressure.

[0149] The shorter length of the third straight section 13 helps to shorten the flow path, which improves the laminar flow of the fluid, ensuring a stable flow rate of the outgoing hydraulic oil and improving the adjustment accuracy of the final hydraulic pressure.

[0150] During practical tests, the inventors found that the ratio of the cross-sectional area of ​​the first straight section 11 and the third straight section 13 equal to 2.5-3 ensures the maximum pressure force.

[0151] It should be noted that the formula for calculating the pressure force: F = πR 2 ×p.

[0152] If the radius (R) of the outlet of the third straight section 13 is too small, although the acceleration of the hydraulic oil is high and the pressure (p) after the pressure increase is large, the flow volume will be insufficient, resulting in insufficient pressing force. Conversely, if the radius of the outlet (R) is too large, although the flow volume is large, the acceleration efficiency of the hydraulic oil will be impaired, and the increased pressure (p) will be insufficient, also resulting in insufficient pressing force.

[0153] In practice, the optimal pressure force is determined not only by the calculation formula but also by a multitude of factors. The inventors discovered that the ratio of the diameters of the first straight section 11 and the third straight section 13 has an optimal range that ensures maximum pressure force—from 2.5 to 3.

[0154] The advantage of using the above-described design variants is that the compression chamber, thanks to its first straight section, second arcuate section designed as a concave quarter circle, and third straight section, ensures the coordinated operation of all three elements. Their combined action ensures the hydraulic oil exits at high and stable pressure after passing through the pressure booster.

[0155] In some embodiments, the ratio between the length L s1 first straight section 11, with radius r ssecond arcuate section 12 and length L s3 the third straight section 13 is 11:5:4.

[0156] With this ratio, the hydraulic oil maintains stable pressure. Turbulence is minimal in all areas of the flow. During compression and constriction of the flow, the forces acting on the fluid's mass elements and their direction converge and stabilize uniformly. It should be understood that the 11:5:4 ratio is not a strict limitation, but allows for a certain range of deviations, for example, within 5%.

[0157] In some embodiments, the radius of the fillet sThe junction of the first straight section 11 and the second arcuate section 12 is 0.1 mm–0.5 mm. Since the second arcuate section 12 is designed as a concave quarter circle, it smoothly mates with the third straight section 13 tangentially, eliminating the need for a rounding at the junction. The use of a rounding helps eliminate stress concentrations that arise during fluid flow on stepped sections or sharp edges, and also prevents turbulent disturbances caused by these elements.

[0158] In some embodiments, the material of the compression chamber 61 is steel, such as conventional grade 45 steel. This choice of material ensures low manufacturing costs and ease of processing.

[0159] The 61 Ra compression chamber's inner wall roughness is 0.1 μm-0.4 μm, with ovality ≤100 μm and cylindricity ≤200 μm. These parameters ensure stable hydraulic oil flow, preventing localized turbulence in the boundary layer and cavitation caused by poor surface quality, thereby improving the stability of the pressure increase force. These parameters are achieved using polishing technology.

[0160] Therefore, the pressure intensifier 6 shown above works in conjunction with the electric motor and hydraulic pump at the front end to provide the pushing force of the piston 62. At the rear end, the pressure intensifier 6 transmits compressed hydraulic oil to the vertical plunger pump, forming a drive mechanism that can maintain the pressure in the sealing system of the polishing device at > 50 MPa. Meanwhile, the adjustment accuracy is 0.01 MPa - 0.1 MPa, and the pressure deviation is < 0.1%, which ensures stability, high speed, and high pressure of the polishing material for polishing the workpiece with internal channels.

[0161] The present application provides a method for increasing the pressure of hydraulic oil, in which the oil sequentially passes through a first straight section 11, a second arcuate section 12 and a third straight section 13, wherein:

[0162] • the ratio of the length to the diameter of the first straight section 11 > 5,

[0163] • the second arcuate section 12 is designed as a concave quarter of a circle,

[0164] • the ratio of the length to the diameter of the third straight section 13 is < 3,

[0165] • the first straight section 11 and the third straight section 13 are located coaxially and parallel,

[0166] • The ratio of the cross-sections of the first and third straight sections is 2.5 - 3.

[0167] It can increase the hydraulic oil pressure stably and reliably, ensuring high and stable pressure output.

[0168] Although the present invention has been disclosed above through the embodiments described above, it is not limited thereto. Any person skilled in the art can make possible changes and modifications without departing from the scope of the present invention.

[0169] Thus, any changes, equivalent transformations and modifications made on the basis of the technical essence of this invention and not going beyond the scope of its technical solution fall within the scope of protection defined by the claims.

Claims

1. A compression chamber characterized in that it is a spatial chamber formed by rotating elements arranged sequentially along the flow, around an axis by 360°, wherein said elements include: the first rectilinear section with a length-to-diameter ratio > 5, forming the cylindrical part of the chamber, a second arcuate section, designed as a concave quarter of a circle and forming a correspondingly tapering part of the chamber, a third rectilinear section with a length-to-diameter ratio of <3, wherein the first rectilinear section and the third rectilinear section are located coaxially and parallel, and the outlet end of the third rectilinear section is the outlet opening of the compression chamber, the ratio of the cross-sectional area of ​​the first rectilinear section and the third rectilinear section is 2.5-3.

2. A compression chamber according to claim 1, characterized in that the ratio between the length of the first straight section, the radius of the second arcuate section and the length of the third straight section is 11:5:

4.

3. A compression chamber according to claim 1, characterized in that the radius of rounding at the junction of the first straight section and the second arcuate section is 0.1-0.5 mm.

4. The compression chamber according to paragraph 1, characterized in that the compression chamber is made of steel.

5. The compression chamber according to paragraph 4, characterized in that the compression chamber is made of grade 45 steel.

6. The compression chamber according to item 4, characterized in that the roughness of the inner wall of the compression chamber is Ra 0.1-0.4 μm, ovality ≤ 100 μm, cylindricality ≤ 200 μm.

7. A pressure booster characterized by the fact that it contains a compression chamber made according to any one of paragraphs 1-6, containing hydraulic oil, a piston located inside the compression chamber, designed to receive a drive force on one side, a translational movement along the walls of the first rectilinear section of the chamber, displacing hydraulic oil located on the opposite side of the piston, through the outlet opening of the third rectilinear section.

8. The amplifier according to item 7, characterized in that the piston perceives a driving force of 1-15 MPa, the output pressure is 2.5-45 MPa.

9. A polishing device characterized in that it contains a drive mechanism, a sealing system that contains a polishing material for polishing, a pipeline system connected to the sealing system, wherein the drive mechanism transmits force to the sealing system, causing the polishing material contained therein to move through the pipeline system to the workpiece, and said drive mechanism contains a hydraulic pump and an amplifier according to claim 7 or 8, wherein the hydraulic pump creates a drive force for the piston of the pressure amplifier, and hydraulic oil after increasing the pressure in the amplifier is supplied to the system.

10. A polishing device according to claim 9, characterized in that the drive mechanism additionally comprises an electric motor, a vertical plunger pump, a hydraulic pump driven by the electric motor and moving the piston, wherein the hydraulic oil, after increasing the pressure in the pressure booster, is supplied to the vertical plunger pump connected to the sealing system and exerting pressure on the polishing material contained therein.

11. A polishing device according to item 10, characterized in that the drive mechanism creates a pressure in the sealing system of > 50 MPa with an adjustment accuracy of 0.01-0.1 MPa and an output pressure deviation of < 0.1%.

12. A method for increasing the pressure of hydraulic oil in a compression chamber according to claim 1, characterized in that it includes moving the hydraulic oil sequentially through said first straight section, second arcuate section, and third straight section, forming a chamber, with increasing pressure.

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