FI88537C - Anordning och foerfarande Foer att aostadkomma hoegtrycksvaetska som skall anvaendas vid spritsvattenskaerning - Google Patents

Description

8 8 52 7

Apparatus and method for providing a high pressure fluid for liquid jet cutting

The invention relates to an apparatus for providing a high-pressure fluid for use in liquid jet cutting.

Previously known liquid jet generating device constructions used in liquid jet surgery are 10 more generally based on the so-called Intesifier principle applications. In this case, the hydraulic pressure is generated by the freeze pump principle using a piston arrangement controlled by valves. The piston arrangement usually receives its energy from the electric motor via a hydraulic-15. The hydraulic pressure generated by the piston arrangement is pulsating in nature, so a pressure accumulator is required in the equipment to equalize the pressure of the fluid before it is used in the actual fluid jet cutting. As can be seen from the foregoing, the construction as a whole is relatively complex with a number of moving parts as well as a set of devices. On the other hand, perhaps the most important drawback of the known devices is that their service interval, especially with respect to the contact sealing surfaces of the piston arrangement, is relatively short, i.e. already approx.

200 hours of operation requires total maintenance of the equipment. The total service life of the equipment is also short, less than 10,000 hours. It is also clear that when the equipment is subject to 30 pressure vessel regulations due to the large volume under high pressure, the equipment is expensive, large in size and requires a great deal of occupational safety in the design.

Since the invention according to the title application closely involves the provision of a high pressure (about 3000-3500 bar) liquid; M at high rotational speeds, reference may first be made in this connection to K.

Kamijo, K. Hirata: Performance of small high speed cryogenic pumps. Journal of fluids engineering, June 8 3 53 7 2 1985, Vol. 107, p. 197-204. A rocket engine fuel pump is known from this publication for generating remarkably high pressures. Liquid oxygen pumps for rocket engines are generally single-stage 5 centrifugal pumps with a typical pressure rise of 120-250 bar. Instead, the head of the liquid hydrogen pumps can be raised to values corresponding to a pressure rise of 1830 bar with water. On the other hand, with regard to high rotational speeds, reference may be made to J.E. Boretz et 10 ai: Turbine organic Rankine engine system for artificial heat application, 749120, pp. 813-823, which discloses a centrifugal pump having a rotational speed of 200,000 rpm. It is generally known, for example, that the speeds of the fuel pumps 15 of rocket engines rarely exceed 80,000 rpm. In practice, the apparatus and method according to the invention aim to achieve a pressure rise in the liquid of at least on the order of 3000 bar. On the other hand, in terms of the overall dimensioning of the equipment 20, in particular to ensure the functionality of the equipment, rotational speeds higher than 5x10 4 are used.

The object of the present invention is to eliminate as far as possible the disadvantages associated with the prior art liquid jet surgery described above and thus to increase the state of the art in the art. The invention makes it possible to implement the device in such a way that it is long-lasting and substantially less maintenance-intensive than known devices. In addition, the equipment can be constructed to a very small size, making it possible to expand the range of technical applications for liquid jet cutting.

35 3 <3577

In order to achieve the above objects, the apparatus according to the invention is mainly characterized in that in order to provide a high-pressure fluid for liquid jet cutting, the apparatus is provided with a nozzle structure connected to the body and connected to the nozzle structure.

Thus, by rotating 10 shafts using a power plant, the solution can be used to transfer the rotational energy of the shaft with a certain efficiency to the pressure increase of the liquid in stages by increasing the pressure in each successive pump unit up to the final pressure. In the apparatus, only the pressure difference of the pressure increase generated by said booster stage is affected over each pump unit. It is clear that a relatively high rotational speed is required for the shaft, e.g. about 2 x 10 5 revolutions per minute, in order to constructively design the apparatus to be relatively small in size.

Other preferred embodiments of the apparatus according to the invention are set out in the appended dependent claims.

25

The invention also relates to a method for providing a high-pressure fluid for liquid jet cutting. The characteristic features of this method appear from the characterizing part of the appended independent method claim.

The invention is also defined by the appended claims.

. The invention is illustrated in more detail in the following description, which refers to the accompanying schematic example illustrating an embodiment 4,88537 in longitudinal section in the longitudinal direction of an apparatus according to the invention.

In the drawing, reference numeral 3 shows the body of the apparatus 5, which is preferably made of metal using suitable machining techniques. The frame 3 is designed to be assembled so that other elements of the equipment to be placed inside it can be installed in connection with the assembly of the frame. Such constructive details are known to the person skilled in the art to such an extent that they will not be explained in more detail in this connection.

A shaft 10 is mounted inside the frame 3. A power device 1, 2 is arranged at the first end of the shaft 15 for rotating the shaft. In the embodiment shown, the power plant 1, 2 is an air turbine, the rotor 1 of which is attached to the first end of the shaft 10. The turbine stator is indicated by reference numerals 2 and 20, the letter A shows the supply of compressed air to the stator, the air flow from the stator to the rotor being indicated by the flow direction arrows. The air turbine technology as well as the structural alternatives of the power plant are also obvious to a person skilled in the art to such an extent that they will not be explained in more detail in this connection. At one end of the shaft 10, which is opposite to the location of the power plant 1, 2, is placed a nozzle structure 11, which in the embodiment shown in the drawing is fixed to the body 3. 30

Four pump units 7 are arranged in succession on the shaft 10 in the embodiment shown in the drawing. 5a, 5 -8577 5b, 6a and between the last pump unit and the second bearing unit 6b as well as in the body 3 in the vicinity of the first end of the shaft.

The apparatus further comprises a duct system 8, 9, through which the liquid is introduced into the body (illustrated by the letter B in the drawing) and through all the pump units 7 to the nozzle structure 11. The duct system is arranged to pass through the first bearing unit 10a, 5b, 6a and the second bearing unit 6b, wherein both bearing units are arranged to operate on the principle of fluid lubrication. In each pump unit, the pressure of the liquid is arranged to be increased by the rotational energy of the shaft 10 in stages 15 so that the liquid is always directed along the duct to the inlet side of the previous pump unit, the previous pump unit always being closer to the other end of the shaft 10 than the next pump unit.

Each pump unit is positioned on the shaft 10 so that the inlet side of the unit is closer to the other end of the shaft than the outlet side of the pump unit. Upstream ^ '' between the discharge side is in question. a seal acting between the pump unit and the body 3 · - · -, such as a labyrinth seal.

In this case, the higher pressure acting at the pressure chamber 11a or the like of the nozzle structure 11, which: causes an axial force on the shaft 10 which tends to transfer towards it to the power plant 1, 2, can be at least partially compensated because in the pump unit. The resulting pressure difference causes an axial force in each pump unit opposite to the above-mentioned axial force.

The first bearing unit 5a, 5b, 6a comprises:. 35 both the central radial bearing arrangement 6a and the axial bearing arrangement 5a, 5b on both sides of the radial bearing arrangement 6a. For the axial bearing arrangement 6 0357.7, for both axial forces possibly acting in the axial direction.

The second bearing unit 6b at the other end of the shaft 10 comprises only a radially fluid-lubricated bearing.

10

The ductwork is mainly formed on the one hand by bores 9 formed inside the body and on the other hand by the guide devices 8 of the pump units, which are connected to each other.

15

The pump units 7 can be designed, for example, to operate on the centrifugal or holding principle. The drawing schematically shows the impeller of a centrifugal pump unit.

20

It is clear that the apparatus according to the invention can be considerably modified within the framework of the basic idea of the invention. For example, the bearing can be implemented e.g. as a magnetic bearing application, wherein the construction of the duct system 25 is independent of the lubrication of the bearings.

It is, of course, clear that liquid-lubricated bearing constructions can be implemented in such a way that liquid lubrication takes place with a separate liquid.

30 EXAMPLE

The following example illustrates an embodiment of the invention by means of an example calculation. The following values are selected for the dimensioning starting values of the liquid jet cutting equipment: flow 2 1 / min, number of pump units 10 and shaft rotation speed 200,000 rpm. In this case, the specific rotational speed of the shaft becomes 0.05 rad. In addition to 7: S 5 7 7, curved blades of the forward impeller of the impeller used in the pump unit are selected. Using the above data, the diameter D of the impellers (see drawing) becomes 5 20 mm. The shaft diameter d is chosen to be 10 mm, which makes it easy to implement a water-lubricated bearing that lasts 200,000 rpm. In order to maximize the efficiency, winged guide wheels are used, in which case the taxi D2 through the hull 3 comes about 60 mm. The length of the body 3 in the longitudinal direction of the shaft becomes approx. 190 mm. To avoid cavitation, the pressure of the liquid fed to the equipment must be at least 40 bar (water as the liquid to be used).

15 The largest single loss is the impeller friction of the impellers, which is about 26 kW. In this case, the total power requirement of the equipment is about 40 kW and the efficiency is 3 0%. The required power can be produced, for example, by a single-stage impulse turbine (hole-20 diameter 31 mm) shown in the drawing, which is supplied with compressed air at a pressure of three bar.

The efficiency of the above equipment can be increased by about 50% if it is designed for a rotational speed of 400,000 rpm with a flow rate of 2 1 / min or by increasing the flow to 8 1 / min at a shaft speed of 200,000 rpm. Correspondingly, the rotational speeds of the shaft can be reduced, for example, to the lower limit specified in the method requirement, if • · 30 the requirements, e.g. for the volume flow of the liquid flow and / or the size of the equipment, enable this dimensioning criterion. The example calculation presented above has only shown by way of example that the construction of the equipment is technically feasible.

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It is clear that a centrifugal pump (Partial Emission or Full Emission) can be used as the pump unit. At the indicated specific rotational speed of 0.05 rad, the holding pump would provide better efficiency, but its 5 rotating chambers are likely to be difficult to withstand the combined stress of high centrifugal force and compressive force. It is clear that the above-mentioned holding pump can be made to withstand rotational speeds lower than the above-mentioned specific rotational speed.

In the apparatus according to the drawing, the axial force compensation is implemented by using the inner circumference of the rear parts of the impellers of the pump units as a counter-piston to compensate for the high compressive force applied to the end of the shaft. The seals used are non-contact labyrinth seals made with a small clearance. Such labyrinth seals have been tried in practice and have withstood rotational speeds of about 300,000 rpm.

When the efficiency of the equipment in the example calculation is 30%, the final temperature of the liquid is about 200 ° C. It is clear that the high pressure prevents the water from evaporating and in most practical applications this temperature is not a disadvantage in the actual liquid jet cutting process.

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Claims (15)

An apparatus for producing high pressure fluid comprising: 5. a body (3), - a shaft (10), a (1, 2) shaft (1) stored in the etomine (3), - a rotary force device (1, 2) - at least two successive pumps (7) acting on the shaft, successively located on the shaft, and - a duct system (8, 9) for passing the liquid into the body (3) and through the pump units, pump unit (7), the liquid pressure is arranged to be incrementally increased by the rotational energy of the shaft (10) so that the liquid is conducted through the duct system (8, 9) from the drain side of the preceding pump unit or similar to the inlet side of the subsequent pump unit (7) or the like, , that for providing the high-pressure liquid to be used for injection water cutting, the device is provided with a nozzle structure (11) which interferes with the body (3) and that the duct system (8, 9) is connected to the nozzle. the structure (11). : \: 25 2. Device according to claim 1, characterized in that the force device (1,2) is connected to one end of the shaft (10) and that the nozzle structure (11) is connected to the pressure chamber or the like. : The proximity of the other end of the shaft into which the pressure chamber the liquid is conducted through the duct system (8, 9) from the pressure side of the last pump unit. Device according to one of Claims 1 or 2, characterized in that the shaft (10) is supported on the body (3) with liquid lubricated bearings. 14 «85 VI 4. Device according to claim 3, characterized in that the lubricating fluid is a liquid whose pressure is increased with the device. 5 Device according to any one of claims 1-4, characterized in that the bearing housing (13) for the first storage unit (5a, 5b, 6a) is formed at least one end of the shaft (10) as part of the duct system (8). , 9). Device according to any one of claims 1-5, characterized in that the bearing housing (13) at least one end of the shaft (10), which is formed as part of the duct system, comprises at least one bed axially (5a). , 5b) and radial (6a) fluid lubrication bearing device. 7. Device according to claim 1, characterized in that between the pump units (7) there is a seal operating between the shaft (10) and the body (3), preferably a labyrinth seal (4). 8. Apparatus according to claim 1, characterized in that the pump unit (7) and / or the body (3) have a seal operating between said pump unit (7) and the body (3), preferably a labyrinth seal. .30 9. Device according to claim 1, characterized in that in each pump unit (7) the inlet of the liquid is arranged relative to the outlet of the liquid, such that the axial force component caused by the pressure difference in said pump unit and which is aligned with the 35 hp shaft ( 10), faces the other end of the shaft (10); which is closer to the nozzle structure (l1). is 88537 10. Device according to claim 1, characterized in that the pump units (7) operate with the centrifugal and / or pitot principle. Device according to claims 1-4, characterized in that the bearing housing (14) for the second storage unit (6a) is formed at least one end of the shaft (10) as part of the duct system (8, 9), and that the storage unit comprises a radial storage device. A method for producing high pressure fluid comprising the following stages: 15. placing in connection with the shaft (1) stored in the body (3) and rotating the power device (1, 2) successively at least two pumping units operating with kinetic principle ( 7), 20. the liquid is passed through said pump units (7), whereby in each pump unit (7) the liquid pressure is gradually increased by the rotational energy of the shaft (10) so that the liquid. is conducted from the discharge side of the preceding pump unit or the like to the inlet side of the subsequent pump unit (7) or the like, characterized by a stage, where - the liquid is passed to the pumping units for auxiliary * 30 of the high pressure liquid to be used for the spray-water spraying liquid. (11). Method according to claim 12, characterized in that the rotational speed of the shaft (10) is selected: 35 to at least 5 x 10 4 revolutions per minute. «· • · 16 b 8 5 ~ 7 Process according to claim 12, characterized in that the liquid pressure is increased by the device to at least 3 x 103 bar. Use of at least two successive kinetic principle operating pump units stored in the body (3) for producing the high pressure liquid to be used for injection water cutting.