Device with a high-pressure pump for conveying a fluid

Abstract

In a device with a high-pressure pump for conveying a fluid through at least one nozzle to generate at least one fluid jet suitable for the erosive machining of a material, the device has a device for generating fluid pulses emerging through the nozzle and the fluid pulses are each designed to remove a predetermined quantity of particles from the material.

Description

Prior ArtThe present invention relates to an apparatus having a high-pressure pump for conveying a fluid through at least one nozzle for generating at least one fluid jet which is suitable for the erodible machining of a material.Devices for water jet cutting materials such as steel, stone, glass, tiles, ceramic, foodstuffs and plastics are known from the prior art. A water jet used by these devices for cutting reaches a pressure of up to 6,000 bar and an outlet speed from an associated nozzle of up to 1,000 m / s. Such a high-pressure water jet can be produced with single-stage or multistage, preferably electrically driven high-pressure pumps which can have drive powers of up to 150 kW. In order to achieve a comparatively high cutting precision of up to ±0.01 mm with such a high-pressure water jet, a correspondingly fine jet geometry can be used and friction-enhancing additives (see g. "abrasives") can be used. Suitable friction-enhancing substances are, for example, corundum, quartz or the like.Furthermore, DE 30 34 753 A1 discloses a method for enhancing the cutting properties of a liquid jet, and DE 10 2009 055 227 B3 discloses a method for conveying a fluid and a device for generating a volume flow.The disadvantage of the prior art is that the generation of such a high-pressure water jet requires the use of high-performance and consequently bulky and heavy high-pressure pumps. In addition, in known devices, the water jet is always guided past the workpiece to be machined on the outside, i.e. repeatedly guided along an outer edge or the cutting edge of the material, so that the creation of three-dimensional structures within the material surface is not possible.Disclosure of the InventionIt is therefore an object of the invention to provide a novel apparatus for water jet cutting materials which requires a comparatively low drive power, which can be used in a mobile and / or stationary manner and which furthermore allows the creation of complex three-dimensional structures within the materials.This problem is solved by a device with a high-pressure pump for conveying a fluid through at least one nozzle for generating at least one fluid jet which is suitable for the erodible machining of a material. The apparatus comprises means for generating pulses of fluid emerging through the nozzle, and the pulses of fluid are each configured to remove a predetermined quantity of particles from the material. The device for generating the fluid pulses emerging through the nozzle has at least one valve which is designed in the manner of an injection valve of an internal combustion engine, so that recourse can advantageously be made to the known technology of conventional injection valves of diesel or gasoline engines for realizing the valve of the device.The invention thus makes it possible to provide a device in which a high removal effect can be achieved with a comparatively low delivery pressure of an associated high-pressure pump and a simultaneously high dimensional accuracy by means of a discontinuous, i.e. in particular periodically interrupted, fluid jet. Due to corresponding particles blown out of a material, a self-intensifying effect occurs in conjunction with the specifically frequencyd pulse pulses or fluid pulses of the fluid jet. The device allows, with a reduced fluid pressure of preferably less than 3,000 bar, the production of molded parts with a three-dimensional geometry and with a high accuracy from different materials. Due to the pulsed fluid jets, it is often possible to dispense with the addition of friction-increasing agents with the same removal rate, resulting in less wear of the associated nozzle and a longer service life of the same, which overall leads to a reduced cost use. The pulsed fluid jets moreover lead to a reduced fluid consumption, which leads to a significantly reduced dust release or contamination of the material compared to water-cooled separating or sawing devices. For example, purified water can be used as the fluid.The at least one valve preferably has at least one magnetic and / or piezoelectric actuator.Thus, proven, robust and reliable actuators can be used in the realization of the valve.According to one embodiment, the fluid pulses are designed to enable a cutting and / or introduction of a three-dimensional geometry into the material.In this way, workpieces having a complex, three-dimensional configuration can be produced comparatively quickly and cost-effectively.Preferably, the at least one nozzle is pivotable about an associated pivot point.Undercut trapezoidal grooves can be produced in this way, for example.Preferably, the at least one nozzle is alignable at a predetermined angle to a material surface of the material.As a result, complex three-dimensional structures, such as blind holes or undercut grooves, can be introduced into a material, wherein a depth of the structures can be influenced in particular by a change in the number of fluid pulses and / or their length over time. In principle, the device can be designed as a portable hand-held device and / or as a stationary device, wherein in the case of a stationary device the at least one nozzle can be moved parallel to the material surface, for example by means of a suitably designed portal. Alternatively, the material can also be moved in relation to a fixed nozzle. The method or the positioning of the nozzle with respect to the material can be carried out manually and / or automatically. In automatic operation, the nozzle is guided with high precision on preprogrammed paths of movement along a material to be machined by suitable actuators, which are preferably controlled by a control and / or regulating device and whose movement is likewise monitored by the control and / or regulating device with the aid of sensors.Preferably, a distance between the at least one nozzle and the material surface is variable.As a result, the geometry of a structure to be produced can be influenced by means of a further parameter. Preferably, the distance can be adjusted manually to a then constant value. Alternatively, a vertical adjustability can be provided under the control of the control and / or regulating device.The fluid can preferably be conveyed by means of a feed pump from a storage container and / or an inflow into an intermediate store, and the high-pressure pump conveys the fluid from the intermediate store as far as the device for generating the fluid pulses emerging through the nozzle.This results in a persistence of the delivery flow and thus of the delivery pressure on the high-pressure side. Alternatively, the high-pressure pump can also be fed directly from the storage container and / or the inflow. If necessary, a return from the high-pressure pump and / or the device for generating the fluid pulses emerging through the nozzle can be returned to the storage container, in order to reduce the fluid consumption, for example.According to one embodiment, an additive, in particular an abrasive agent, can be added to the fluid in order to increase an associated removal power.This allows the processing speed to be increased. For wear reduction, the abrasive agent is preferably supplied between the device for generating the fluid pulses emerging through the nozzle and the nozzle.The at least one nozzle preferably has at least one outlet opening for the fluid pulses.The geometric design of the outlet openings and / or their arrangement in the region of the nozzle can influence the shape of the structure to be created. In addition, the nozzle can have, for example, at least two groups each having at least one outlet opening, wherein the at least two groups can be controlled independently of one another and the outlet openings each have a different geometry in groups (see, for example, "Coaxial Vario Nozzle"). By further reducing the cross section of the outlet opening, it is possible to minimize the jet diameter. This enables a lower water throughput, more precise operation and optionally the omission of a collecting basin for the energy reduction of the fluid jet. An increase in the accuracy of the jet geometry can be effected, for example, by "hydroerosionive rounding" of the outlet openings.Preferably, an angle between a nozzle longitudinal axis and a fluid impulse axis is at least approximately between 0° and 150°.As a result, undercut structures in the material can also be easily and quickly produced by means of the device.Preferably, the at least one nozzle is releasably fixed in an associated nozzle holder.This makes it possible to exchange nozzles with a different number of outlet openings and / or outlet openings with different cross-sectional geometries and / or nozzles with differently arranged outlet openings.Preferably, the device for generating the fluid pulses emerging through the nozzle can be controlled by means of a control and / or regulating device.As a result, for example, the frequency and / or the duty cycle of the fluid pulses and thus, as a result, the resulting (total) volume flow Q(t) of the fluid jet can be influenced within wide limits in order, inter alia, to control the cutting or removal characteristic of the device for creating complex geometric structures in the material.Brief Description of the DrawingsThe invention is explained in more detail in the following description with reference to exemplary embodiments shown in the drawings. The following are shown: FIG. 1 shows a perspective view of a nozzle arranged in a nozzle holder for generating a fluid jet, FIG. 2 shows an exemplary profile of a volume flow Q(t) which results from a sequence of fluid pulses of different lengths over time t, FIG. 3 is a simplified view of a hand-held device; and FIG. 4 shows an exemplary hydraulic circuit diagram of the device of FIG. 3.DESCRIPTION OF THE EMBODIMENTSFIG. 1 shows a nozzle 10 arranged in a nozzle holder 12 for generating a fluid jet which is suitable for the erodible machining of a material 14. According to one embodiment, at least the nozzle 10 is designed to be used in a preferably hand-guided device ( 90 in FIG. 3 ) for cutting and / or forming a complex, spatial geometry in the material 14.Illustratively, the nozzle 10 is releasably received in the nozzle holder 12. For this purpose, a mechanical lock 18 for mechanically and hydraulically firmly coupling between the nozzle 10 and the nozzle holder 12 is provided at an end 16 of the nozzle 10 facing away from the material 14, which lock can be released if necessary, in order to enable, for example, a rapid nozzle change.The nozzle 10 has at its other end 20 facing the material 14-lower in FIG. 1-at least one and here exemplarily two outlet openings 22, 24, through which fluid pulses 26, 28 respectively emerge according to the invention. Alternatively, only one vertical outlet opening 22 for the fluid pulses 26 can also be provided.In order to make very fine cuts or micromachining of the material 14 possible, an opening width of the outlet opening 22, 24 can be set down to 60 μm. The opening width is preferably in a range between 60 μm and 200 μm. By means of an outlet opening with variable cross-sectional geometry, application-specific jet shaping, i.e. in particular a change in the cross-sectional geometry of the fluid pulses 26, 28, can optionally also take place in a jet zone directly before the impingement on the material 14.The lower end 20 is positioned within a material surface 32 of the material 14 at a distance 34 therefrom to provide a complex, three-dimensional geometry 30. In order to avoid fanning out too much, the distance should be less than 1 cm. A fluid pulse axis 36 of the outlet opening 22 extends at an angle α of approximately 0° to a nozzle longitudinal axis 38 for generating the vertical fluid pulses 26, whereas a fluid pulse axis 40 of the outlet opening 24 extends at an angle β of approximately 90° to the nozzle longitudinal axis 38 for generating the horizontal fluid pulses 28. As a result, the fluid pulses 26, 28 each embody a part of a pulsed fluid jet 42, 44. Alternatively, the outlet openings 22, 24 of the nozzle 10 can have values for the angles α, β that differ therefrom, and the nozzle 10 can have more than two outlet openings 22, 24.By way of example, a vertical groove 46 with a square cross-sectional geometry is produced as a part of the complex three-dimensional geometry 30 within the material 14 by means of the vertical fluid pulses 26 or the vertical fluid jet 42, whereas a horizontal groove 48 with a rectangular cross-sectional geometry is introduced into the material 14 as a further part of the three-dimensional geometry 30 by means of the horizontal fluid pulses 28 or the horizontal fluid jet 44. In addition, the horizontal groove 48 can have, as indicated by a dashed line, an undercut 50, for example trapezoidal. When producing the geometry 30, an outer edge 52 of the material does not need to be taken as a basis here. Rather, the pulsating fluid jets 42, 44 according to the invention allow the production of the geometry 30 to be started at any point on the material surface 32.The outlet openings 22, 24 are each individually supplied with the fluid under high pressure via two indicated channels 54, 56, so that fluid pulses 26, 28 or fluid jets 42, 44 can be generated with respectively different pulse durations, amplitudes and / or frequencies. In such a configuration, the nozzle 10 can be embodied, for example, as a "coaxial vario nozzle". Alternatively, only the one outlet opening 22 for the vertical fluid pulses 26 of the fluid jet 42 can be provided, whereby the design outlay is considerably reduced.In order to further optimize the flexibility of the spatial positionability of the nozzle 10 in order to create even more complex three-dimensional spatial structures, it can be designed to be pivotable about a pivot point 58-as indicated by a double arrow 60-about an angle γ with respect to the material surface 32 or its orthogonal, wherein the angle γ of the nozzle 10 in the position shown in FIG. 1 is approximately 0°. As a result, the horizontal outlet opening 22 within the nozzle 10 can be omitted, as the case may be, as a result of which the structural design is simplified.To increase the service life of the nozzle 10, purified water is preferably used as the fluid, which water can be mixed with a friction-increasing additive ("abrasive") only in exceptional cases to increase the removal effect.FIG. 2 shows an exemplary course of a volume flow Q(t) which results from a sequence of fluid pulses of different lengths over time t and which here serves as an example for creating an undercut blind bore as a further complex spatial geometry. For this purpose, a plurality of short fluid pulses 70 and a long fluid pulse 72 are shot from the nozzle 10 onto the material surface 32 of the material 14 by means of the correspondingly controlled nozzle 10 of FIG. 1. In contrast to the illustration of FIG. 1, only vertical fluid pulses are used here.The short fluid pulses 70 lead to small volume flow pulses 74, whereas the long (stronger) fluid pulse 72 results in a large volume flow pulse 76 in the volume flow Q(t) of the fluid. For the sake of better graphic overview, only a first, short volume flow pulse 74 is representative of the remaining, short volume flow pulses with a reference numeral. The small volume flow pulses 74 have a significantly smaller maximum amplitude A 1 than a maximum amplitude A 2 of the large volume flow pulse 76. Accordingly, a respective pulse length T 1 of the small volume flow pulses 74 is in each case significantly shorter than a corresponding pulse length T 2 of the large volume flow pulse 76.The lower kinetic energy of the short fluid pulses 70 results in a reduced removal power compared to the long fluid pulse 72. Therefore, small-volume hollow cylindrical cavities 78 can be formed with the short fluid pulses 70 and a large-volume cavity 80 can be formed with the aid of the one long fluid pulse 72. For the better overview of the drawings, only one small-volume cavity is provided with reference numeral 78 as representative of all the remaining ones. The cavities 78, 80 together form the three-dimensional geometry 82 to be produced in the material 14, which geometry is here, by way of example, a blind bore 84 with an undercut 86.To introduce the blind bore 84, two small-volume cavities 78 arranged one above the other are initially driven into the material 14 from the material surface 32 with the aid of two short fluid pulses 70 following one another. The large-volume cavity 80 is formed by the long fluid impulse 72, which cavity has an enlarged diameter in order to create the undercut 86 compared to the small-volume cavity 78. Finally, two further small-volume cavities 78 are applied below the large-volume cavity 80 by the application of two short fluid pulses 72. All cavities 78, 80 are each aligned centrally with respect to a longitudinal central axis 88 of blind bore 82 and are each arranged one above the other.FIG. 3 shows a hand-guided device 90 for cutting and / or forming a complex spatial geometry in a material (e.g. 14 of FIG. 1 ), which is preferably provided primarily for locally flexible, mobile use on construction sites or the like. This comprises, by way of example, at least a first and a second unit 92, 94 which are coupled to one another by means of a flexible line 96.The first unit 92 illustratively comprises a box-shaped housing 98, in which e.g. the nozzle 10 of FIG. 1 is integrated. On the housing 98, which serves as a jet and noise protection in addition to the integration of further functional components of the device 90, two bow-shaped handles 100, 102 are furthermore attached, which are provided for manually guiding the unit 92 on the material surface 32 of the material 14 to be processed.By guiding the first unit 92 along a predefined travel path in the direction of the two arrows 104, 106, the schematically illustrated three-dimensional geometry 108, for example, can be introduced into the material surface 32. The geometry 108 can be, for example, a groove, a cut or a tear of the material surface 32 with a small depth. Cuts can be made by means of the device 90 without problems outside the edges of the material 14, so that, for example, a recess with any desired geometric shape for the passage of a line or the like can be cut out of a tile or a stone plate in a simple manner.The second unit 94, which is connected to the first unit 92 by means of the flexible line 96, likewise has a box-shaped housing 110. In addition to further components, the housing 110 of the second unit 94 encloses in particular a high-pressure pump 112, a reservoir container 114 for the fluid and an optional intermediate reservoir 116 for the fluid.The flexible conduit 96 comprises in particular a high-pressure conduit for supplying the nozzle 10 with the fluid under high pressure of up to 3,000 bar, but can additionally comprise a plurality of further electrical, hydraulic and / or pneumatic conduits. For simplifying handling, the flexible line 96 is preferably connected at least to one of the two units 92, 94 in a detachable manner, for example by means of a plug connection, mechanically, hydraulically, electrically and optionally also pneumatically.The spatial separation between the two units 92, 94 shown here merely by way of example allows a comparatively low weight of the first unit 92, as a result of which the handling for a user is simplified. Alternatively, both units 92, 94 can also be combined to form a large unit, so that the external flexible line 96 can be dispensed with. The device 90 can be designed selectively in network-operated and / or network-independent or battery-operated fashion. For this purpose, a preferably electrical energy supply is preferably integrated into the housing 110 of the second unit 94.Alternatively, the first unit 92 can also be designed to be fully automatically displaceable on the material surface 32 in the direction of the arrows 104, 106 along predetermined (preprogrammed) paths, for example, with the aid of a plurality of drive wheels arranged on the underside of the housing 98. In this case, a control and / or regulating device (cf. FIG. 4 ) takes over the control of all sequences within the apparatus 90 and in particular the monitoring of the travel paths covered by the first unit 92 on the material surface 32.In addition, it is possible to design a stationary device in which the nozzle 10 is arranged on a gantry, so that the nozzle 10 can be moved in all three directions of the space in a controlled manner by the control and / or regulating device with high precision in relation to the material, in order to be able to produce highly complex three-dimensional structures or geometries in workpieces with large dimensions in a fully automated manner and with the highest possible accuracy.FIG. 4 shows an exemplary hydraulic circuit diagram illustrating a preferred implementation of the apparatus 90 of FIG. 3. Accordingly, the reservoir 114 is provided for storing a fluid 120, such as water. Alternatively or additionally, the fluid 120 can be supplied to the device 90 via an inflow 122. With the aid of an optional (pre)feed pump 124, the fluid 120 is sucked out of the storage container 114 or via the inflow 122, and is conveyed into an likewise optional intermediate storage 116. The fluid 120 is sucked from the intermediate reservoir 116 by means of the high-pressure pump 112 and is supplied to the nozzle 10 via the flexible line 96. Alternatively, the feed pump 124 and the intermediate reservoir 116 can be omitted. In this configuration, the high-pressure pump 112 draws in the fluid 120 directly from the storage container 114 and / or from the external inflow 122.The nozzle 10 includes, among other things, the outlet opening 22, from which the fluid pulses 26 of the vertical fluid jet 42 emerge. In addition, the nozzle 10 preferably contains a device 126, which is preferably realized with an electromagnetically and / or piezoelectrically actuatable valve 128, which is preferably designed in the manner of an injection valve of an internal combustion engine, in order to generate the fluid pulses 26 from the fluid present at the valve 128 at a virtually constant pressure p of up to 3,000 bar. By suitable actuation of the valve 128 by means of a control and / or regulating device 130, it is possible, for example, to generate the temporal sequence of fluid pulses shown in FIG. 2. The control and / or regulating device 130 is preferably designed with a digital computer unit, such as a microcontroller, for example. For the independent control of the horizontal fluid pulse 28 of the nozzle 10 of FIG. 1, a further valve, not shown here, and controlled by the control and / or regulating device 130, together with an associated outlet opening, is to be provided within the device 126.In principle, the incoming fluid can be modulated within wide limits with the aid of the control and / or regulating device 130, i.e. fluid pulses 26 with a frequency, amplitude and / or pulse width that can be varied within wide limits can be generated, so that even complex spatial geometries in the material ( 14 of FIG. 1 ) can be easily generated. As a result, the graph of the volume flow Q(t) of FIG. 2 can be given a virtually arbitrary curve profile--deviating from the sinusoidal profile shown merely by way of illustration--(cf. FIG. 2 ).If a corresponding removal capacity of the device 90 is not sufficient irrespective of the pulsating fluid jet 42, an additive, preferably an abrasive agent 132, i.e. a friction-increasing substance ("abrasive"), can be added to the fluid stream, if necessary, by means of a feed device 134, preferably upstream, directly upstream of the outlet opening 22.

Claims

Device (90) having a high-pressure pump (112) for conveying a fluid (120) through at least one nozzle (10) for generating at least one fluid jet (42, 44) which is suitable for the erodible processing of a material (14), wherein the device (90) has a device (126) for generating fluid pulses (26, 28) emerging through the nozzle (10), and the fluid pulses (26, 28) are each designed to remove a predefined quantity of particles from the material (14), characterized in that the device (126) for generating the fluid pulses (26, 28) emerging through the nozzle (10) has at least one valve (128) which is designed in the manner of an injection valve of an internal combustion engine.Device according to Claim 1, characterized in that the at least one valve (128) has at least one magnetic and / or piezoelectric actuator.Device according to claim 1 or 2, characterised in that the fluid pulses (26, 28) are designed to enable a three-dimensional geometry (30, 82, 108) to be cut and / or introduced into the material (14).Device according to one of the preceding claims, characterized in that the at least one nozzle (10) is pivotable about an associated pivot point (58).Device according to claim 4, characterised in that the at least one nozzle (10) can be aligned at a predetermined angle (γ) to a material surface (32) of the material (14).Device according to claim 4 or 5, characterised in that a distance (34) between the at least one nozzle (10) and the material surface (32) is variable.Device according to one of the preceding claims, characterized in that the fluid (120) can be conveyed by means of a feed pump (124) from a storage container (114) and / or an inflow (122) into an intermediate store (116), and the high-pressure pump (112) conveys the fluid (120) from the intermediate store (116) as far as the device (126) for generating the fluid pulses (26, 28) emerging through the nozzle (10).Device according to one of the preceding claims, characterized in that an additive, in particular an abrasive agent (132), can be added to the fluid (120) in order to increase an associated removal power.Device according to one of the preceding claims, characterized in that the at least one nozzle (10) has at least one outlet opening (22, 24) for the fluid pulses (26, 28).Device according to claim 9, characterised in that an angle (α, β) between a nozzle longitudinal axis (38) and a fluid impulse axis (36, 40) is at least approximately between 0° and 150°.Device according to one of the preceding claims, characterized in that the at least one nozzle (10) is releasably fixed in an associated nozzle holder (12).Apparatus according to one of the preceding claims, characterized in that the device (126) for generating the fluid pulses (26, 28) emerging through the nozzle (10) can be controlled by means of a control and / or regulating device (130).

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