EP2741862B1 - Device for generating a pulsating fluid jet subjected to pressure - Google Patents

Description

The invention relates to a device for generating a pulsating fluid jet of pressurized fluid with a conduit system containing at least one nozzle having a nozzle mouth from which a fluid jet of pressurized fluid can escape, and which has a chamber in a pressure wave generating device for generating fluid pressure waves is formed, which communicates with the line system through an outlet opening for the generated fluid pressure waves.

Such a device is known from WO 2006/097887 A1 known.

To efficiently process workpieces with fluid jets, e.g. With water jets, conventionally very high pressures must be generated, which may be 3000 bar or even higher. That requires a lot of energy. Working with corundum and sand, on the other hand, causes undesirable residues. In comparison to the above-mentioned machining process, the machining, machining with cutting tools, for example, for materials with high hardness in particular the disadvantage that it is relatively expensive because of the wear of the cutting.

Against this background, the object of the invention is to provide a device for the efficient machining of the surface of workpieces with fluid jets, which can operate with comparatively low fluid pressures. In particular, it is an object of the invention to provide a device with which the surface of workpieces for the coating can be activated and / or which allows an editing of coatings applied to workpieces such as the removal of overspray and / or the removal of layers on workpieces allows.

This object is achieved by a device of the type mentioned above, which includes an adjustment for adjusting the amplitude of the fluid pressure waves in the line system before the at least one nozzle mouth, with which from the quotient of the path length L for the fluid pressure waves between the Outlet opening of the chamber and the at least one nozzle mouth of the at least one nozzle in the line system and the wavelength λ of the fluid pressure waves in the line system formed Helmholtz number He: = L / λ can be adjusted.

The device according to the invention is particularly suitable for applying a fluid to a workpiece surface in the form of wash liquor and / or water and / or emulsion, in particular water-oil emulsion and / or oil.

The invention is based on the idea that can be generated by coupling of vibration energy in the form of pressure waves in a fluid jet, in particular in a fluid jet, which is subjected to an increased pressure, which may be 20 bar, 30 bar or more, generate fluid pulses, in which the vibration energy is converted into kinetic energy. One idea of the invention is that the kinetic energy transferable to the fluid by generating pressure waves can be maximized by ensuring that the reflections of pressure waves in a conduit system for supplying pressurized fluid to a nozzle do not cancel the generated pressure waves but reinforce due to interference. In a device according to the invention, therefore, the ratio of the effective path length, which the pressure waves in the conduit system from the outlet opening of the chamber to the nozzle mouth of a nozzle cover and the wavelength of the fluid pressure waves, ie, a fluid pressure waves in the line system characterizing Helmholtz number are set.

For setting this Helmholtz number, the line system may include a first line piece and a at least partially received in the first line piece and communicating with this second line piece, which can be displaced relative to the first line piece in the longitudinal direction. It is advantageous in this case, if the second line piece, e.g. is guided linearly movable with a thread on the first line piece. Conveniently, a fixing device is provided, with which the second line piece can be fixed to the first line piece.

Alternatively, or in addition, to adjust the Helmholtz number, the device may include frequency adjustment means for adjusting the frequency of the generated fluid pressure waves. In fact, by varying the frequency of the fluid pressure waves, their wavelength in the fluid is also changed.

With a device according to the invention, workpieces can be roughened and cleaned, in particular without abrasive additives.

The conduit system advantageously has a first conduit system section with a connection for a pressure pump and has a second conduit system section with a receptacle for the nozzle. It is advantageous if the first section and the second section are connected to a swivel joint. In that the second conduit system portion in the pivot joint is coaxial with respect to the first conduit system portion about an axis of fluid passage formed in the second portion Axial oscillating and / or can be moved in rotation, it is possible to produce regular or irregular structures in the surface of a workpiece bore. The device preferably contains a motor drive for moving the second line system section.

Conveniently, the line system has a first line system section with a connection for a pressure pump and has a second line system section, in which a plurality of nozzles are each arranged with a nozzle mouth, which are acted upon by separate line branches with fluid. In the separate line branches to the nozzles in each case a length-adjustable line for pressurized fluid is arranged. By adjusting the line, the path length of fluid pressure waves generated in the chamber between the nozzle mouth and the outlet port for fluid pressure waves of the chamber can be adjusted.

By preferably monotonically decreasing the effective cross-section of the conduits in the conduit system between the fluid pressure wave exit opening of the chamber and the nozzle mouth of the nozzle, it is ensured that the amplitude of the pressure waves in the flow direction of the fluid increases towards the nozzle mouth. In order for any air bubbles in the chamber can be removed, a vent valve is beneficial. Preferably, this vent valve is arranged so that even with a displacement of the device, these air bubbles can escape. For this purpose, the vent valve may for example be accommodated in an upper ceiling portion of the chamber.

The chamber may have an opening separate from the exit opening for supplying high pressure fluid. This allows efficient delivery of fluid into the chamber. To ensure that the energy supplied to the pressure wave generating device with a good efficiency is converted into pressure waves, it is advantageous if the pressure wave generating device is located in a Totwassergebiet the chamber.

In order to reinforce the pressure waves coupled into the fluid, the chamber has a cross-section which is funnel-shaped in the direction of the outlet opening. It is advantageous to provide in the chamber a sensor for detecting pressure waves, so that the pressure wave generation can be monitored there. The sensor is conveniently designed as a pressure sensor and arranged in a portion of the chamber, which tapers in a funnel shape in the direction of the outlet opening.

The at least one nozzle may have a nozzle chamber whose cross-section is tapered towards the nozzle mouth. Extensive experiments have shown that with the nozzle fluid pulses can be generated with a very large kinetic energy when the nozzle chamber in front of the nozzle mouth has a conically tapered portion with an obtuse angle of aperture a, preferably an aperture angle a in the range 105 ° ≤ a ≤ 180 °. Preferably, the at least one nozzle has a cylindrical, preferably circular cylindrical nozzle chamber with an opening arranged on the front side in the nozzle mouth. The fluid pulses that can be generated with such a nozzle are particularly suitable for removing material from aluminum materials. Due to cavitation, such a nozzle makes it possible to form fluid droplets which are particularly suitable for removing material and which are then contained in the pulsating fluid jet.

By providing a means for generating a gas stream at least partially enveloping the pulsating fluid steel, workpieces immersed in liquid with the pulsating fluid jet can be processed. Here, with the gas stream surrounding the high-pressure fluid jet, it ensures that the liquid into which the workpiece is submerged, does not slow down the fluid jet. The liquid surrounding the workpiece advantageously causes the attenuation of noise. Extensive tests have shown that when the at least one nozzle has a cup-shaped portion facing the workpiece, in which the pulsating fluid jet emerges from the nozzle mouth and whose opening cross-section widens in the direction pointing to the workpiece, a particularly good cleaning action is achieved for the workpiece can be. In order to be able to clean as large a workpiece surface as possible, it is expedient if the at least one nozzle is designed in the form of a nozzle nozzle which has a plurality of nozzle orifices.

It is advantageous to form a system with a device for generating a fluid jet with a workpiece receiving device in which the workpieces are acted upon by a pulsating fluid jet, and with a fluid collecting device to collect fluid released from the device connected to a pressure pump to return the collected fluid into the device. By including a measuring device for detecting material removed from a workpiece with a fluid jet, it is possible to monitor the removal of material caused by the pulsating fluid jet.

In order to modify the physical properties of components for certain applications, for example in order to increase their mechanical and thermal stability in internal combustion engines, these are finished with high quality coatings in certain places.

As a rule, these coatings require that the surface of these assemblies be prepared for coating, ie, usually roughened or activated. For this purpose, it is known to work the workpieces with corundum or sandblasting. In addition, the surface can Such workpieces are machined by cutting tools to prepare for the coating and machined.

An idea of the invention against this background is also that with a pulsating fluid jet in the surface of a workpiece structures can be produced which improve the adhesion of a coating on the surface and in particular allow the coating can be loaded with very large shear forces.

It has namely been e.g. It has been shown that in particular the coating of aluminum materials by means of thermal spraying methods, such as flame spraying, plasma spraying, atmospheric plasma spraying or electric arc wire spraying, in particular, can significantly improve the tribological properties of aluminum assemblies. Arc wire spraying, for example, makes it possible to coat aluminum assemblies with an iron-based alloy having a carbon content between 0.8 and 0.9 weight percent and containing dispersive friction reducing fillers in the form of graphite, molybdenum disulfide or tungsten disulfide.

Coating materials also reduces the weight of engine components and allows compact designs, such as cylinder crankcases, in which the cylinder bores are at a reduced distance from each other compared to conventional housings.

It is advantageous to use one or more devices according to the invention for generating a fluid jet in a plant for applying workpieces with fluid, which contains a controllable device for adjusting the pressure of the fluid supplied from the conduit system and the one with the device for the setting of the pressure and the pressure wave generating means connected computing unit with a Data storage has, in which a parameter map for the application-specific adjustment of the fluid pressure and / or the amplitude and / or the frequency of the pressure wave generating device can be generated with the fluid pressure waves is stored. In the parameter map can also be a favorable nozzle rotation speed depending on a material to be machined, in particular substrate and / or a given workpiece geometry and / or a workpiece surface finish, in particular a workpiece surface roughness, and / or a kind of workpiece contamination and / or a machining distance of a workpiece to be machined from the at least one nozzle mouth of the device to be stored. In addition, an advantageous angle of a pulsating high-pressure fluid jet generated by a corresponding device to a workpiece surface can also be stored in the parameter map.

Preferably, such a system includes a manipulator to move a fluid-to-be-pressurized workpiece relative to the device or apparatus relative to the workpiece. The manipulator can perform completely free movements, in particular linear movements or free curve movements. In particular, an articulated robot with six axes of movement is provided as a manipulator.

An idea of the invention is also to activate a surface of a workpiece for flame spraying or plasma spraying or arc wire spraying with a pulsating fluid jet, which can be produced eg with an inventive device, or to prepare it for gluing. In addition, it is an idea of the invention to use such a pulsating fluid jet to process a workpiece surface produced by means of flame spraying or plasma spraying or electric arc wire spraying.

One finding of the invention is, in particular, that the preparation of the wall of a bore in a workpiece, in particular the adhesive properties of a workpiece surface produced by means of electric arc wire spraying, can be optimized if the nozzle is to produce at an angle β of 0 ° ≦ β ≦ 60 °, preferably β ≈ 45 °, is applied to the local surface normal of the wall inclined direction with a pulsating high pressure fluid jet, and the nozzle is thereby rotates relative to the workpiece about the axis of the bore and translationally displaced in the direction of the axis of the bore. The distance of the nozzle opening to the workpiece surface is favorably between 10 mm and 150 mm.

The inventors have recognized, in particular, that a section of a workpiece can be finished by applying a surface coating to the workpiece in a first step and then, in a second step, processing and / or partially removing the coating by means of a pulsating fluid jet. This fluid jet can be generated in particular with a device according to the invention. The inventors have also recognized that the surface of a workpiece can be activated by means of a pulsating fluid jet, in particular by means of a pulsating fluid jet generated by a device according to the invention, in order to achieve the adhesive properties for the coating on the surface and the mechanical or thermal resilience to increase the coating. In particular, it is a finding of the inventors that can be activated by means of a pulsating fluid jet, which can be produced for example with a device according to the invention, the surface of an existing at least partially made of aluminum or aluminum alloy or magnesium alloys workpiece on this by means of thermal spraying (Arc wire spraying, LDS, plasma spraying, etc.) to apply a surface coating of ferrous material and then with a pulsating fluid jet, eg from a to edit the device according to the invention. A finding of the inventors is also that by means of a pulsating fluid jet, which can be produced, for example, with a device according to the invention, the surface of a at least partially made of steel or gray cast workpiece can be activated to apply thereto by means of laser wire welding a surface coating of nickel-containing material , Moreover, it is an idea of the inventors that a coating applied to a workpiece made of steel or cast iron, aluminum, an aluminum alloy or a magnesium alloy is processed in the form of laser-wire-welded ferrous or nickel-containing material with a pulsating fluid jet can, in particular with a pulsating fluid jet from a device according to the invention.

In the context of the invention, it may be provided in particular to first apply a large surface area over a surface coating and then subsequently to remove it again in the area of small areas.

In the following the invention will be explained in more detail with reference to the embodiments schematically illustrated in the drawing.

Fig. 1

eine Anlage mit einer Vorrichtung für das Erzeugen eines pulsierenden Fluidstrahls mit einem Werkstück;

Fig. 2

eine Kammer für das Erzeugen von Fluid-Druckwellen in der Vorrichtung;

Fig. 3

eine in der Länge verstellbare Leitung der Vorrichtung für mit Druck beaufschlagtes Fluid;

Fig. 4

eine in der Vorrichtung einsetzbare Düse;

Fig. 5

eine weitere in der Vorrichtung einsetzbare Düse;

Fig. 6

eine in der Vorrichtung einsetzbare Düse mit einem Strahlrichter;

Fig. 7

einen Schnitt der in Fig. 6 gezeigten Düse entlang der Linie VII-VII;

Fig. 8

eine Vorrichtung für das Erzeugen eines pulsierenden Hochdruck-Fluidstrahls mit in einem Revolver angeordneten Düsen;

Fig. 9

einen Abschnitt einer Vorrichtung für das Erzeugen eines in einen Gasstrom eingehüllten pulsierenden Hochdruck-Fluidstrahls;

Fig. 10

einen Abschnitt einer weiteren Vorrichtung für das Erzeugen eines in einen Gasstrom eingehüllten pulsierenden Hochdruck-Fluidstrahls mit einer Düse;

Fig. 11

eine Vorrichtung für das erzeugen eines pulsierenden Hochdruck-Fluidstrahls mit einem Düsenrechen; und

Fig. 12

einen Schnitt der in der Fig. 11 gezeigten Vorrichtung entlang der Linie XII - XII.

Show it:

Fig. 1

a system with a device for generating a pulsating fluid jet with a workpiece;

Fig. 2

a chamber for generating fluid pressure waves in the device;

Fig. 3

a length-adjustable conduit of the pressurized fluid device;

Fig. 4

a usable in the device nozzle;

Fig. 5

another usable in the device nozzle;

Fig. 6

a usable in the device nozzle with a jet straightener;

Fig. 7

a section of in Fig. 6 shown nozzle along the line VII-VII;

Fig. 8

an apparatus for generating a pulsating high-pressure fluid jet with nozzles arranged in a turret;

Fig. 9

a portion of an apparatus for generating a pulsating high-pressure fluid jet enveloped in a gas stream;

Fig. 10

a portion of another apparatus for generating a high pressure pulsating high pressure fluid jet in a gas stream with a nozzle;

Fig. 11

an apparatus for generating a pulsating high pressure fluid jet with a nozzle screen; and

Fig. 12

a cut in the Fig. 11 shown device along the line XII - XII.

The plant 10 in Fig. 1 is designed to activate the surface 12 of a cylindrical recess 14 in a workpiece 15 by means of pulsating fluid jets 16, 18 of water.

For generating the fluid jets 16, 18, the system 10 has a device 20 with a chamber 22 in which a device 24 for generating fluid pressure waves 32 is formed. The device 24 is connected to a controllable frequency generator 31. The device 24 contains a piezoelectric crystal 28, which acts as an electromechanical transducer and is connected to a sonotrode 30. When the chamber 22 is filled with water, the sonotrode 30 in the water can generate pressure waves 32 at a frequency v which is preferably in the range of 10 kHz ≦ v ≦ 50 kHz.

For generating pressure waves, the piezoelectric crystal 28 is subjected to a high-frequency alternating voltage from a frequency generator 31. The frequency generator 31 is designed for generating ultrasonic frequencies, preferably ultrasonic frequencies in the range 10 kHz ≦ v ≦ 50 kHz. By adjusting the frequency v and the amplitude A _{P of} the alternating voltage generated by the frequency generator 31, the wavelength λ of the pressure waves 32 in the line system 36 can be varied.

The chamber 22 is preferably tuned to a wavelength range of the fluid pressure waves 32 that can be generated with the sonotrode 30. For fluid pressure waves 32 in this wavelength range, the chamber 22 then acts as a resonance chamber.

The chamber 22 has an outlet opening 34 to a conduit system 36 which connects the chamber 22 with nozzles 38, 40. The piping system 36 has a chamber-side section 42 and includes a nozzle-side section 44. The chamber-side section 42 and the nozzle-side section 44 are connected by means of a pivot joint 46. In the rotary joint 46, the nozzle-side section 44 can be moved by means of a motorized rotary drive 48 about an axis coaxial to the fluid channel 50 axis oscillating and / or rotationally by means of a drive motor 54 by motor.

The nozzles 38, 40 are located in the nozzle-side portion 44 of the conduit system 36 in line branches 56, 58, which are separated from each other. The fluid channel 60 formed in the nozzle-side section 44 is branched into the line branches 56, 58.

In the line branch 56 and the line branch 58, there is a respective line section with a length-adjustable line 62, 64. The adjustable line 62, 64 includes a first line piece 66, 68 and at least partially in the first line piece 66, 68 received and the second conduit 70, 72 communicating therewith. The second conduit 70, 72 can be displaced coaxially relative to the first conduit 66, 68 in the longitudinal direction 74, 76 corresponding to the double arrow 78, 80.

In each case one of the nozzles 38, 40 is received in the second line piece 70, 72. By displacing the second line piece 70, 72 relative to the first line piece 66, 68, the effective path length 26 for pressure waves 32 between the outlet opening 34 and the workpiece side facing away from the nozzle mouth 82, 84 of the nozzles 38, 40 can be adjusted. The movement play for the line piece 70, 72 is tuned to the wavelength of the pressure waves 32. The movement play is favorably at least half a wavelength of the pressure waves 32. It is preferably in a range between 40 mm and 300 mm. Also in the section 42 of the conduit system 36, the conduit 43 can be displaced coaxially translationally relative to the conduit 45 by means of an adjusting device 47. The adjusting device 47 makes it possible to set the effective path length 26 for the pressure waves 32 in the line system 36. The adjusting device 47 can be adjusted by means of a (electric) motor drive (not shown). By adjusting the effective path length 26 of the pressure waves 32 in the conduit system 36 can be achieved that the Pressure waves 32 immediately before the workpiece facing away from the opening of the nozzle mouth of the nozzles 38, 40 have a vibration belly.

The adjusting device 47 thus acts as an adjusting device for adjusting, ie setting the amplitude A _{P of} the fluid pressure waves 22 in the line system 36 before the at least one nozzle mouth 125. With the adjusting device 47, one of the quotient of the path length L for the fluid pressure waves 32 Helmholtz number He: = L / λ formed between the outlet opening 34 of the chamber 22 and the at least one nozzle mouth 125 of the at least one nozzle 38, 40 in the conduit system 36 and the wavelength λ of the fluid pressure waves 22 in the conduit system , The adjustable lines 62, 64 also act as adjusting means for controlling the amplitude A _P of fluid pressure waves 32 in front of the corresponding nozzle mouth of the nozzle 38, 40.

In a modified embodiment, the chamber-side portion and the nozzle-side portion are made in one piece. In a further modified embodiment, the nozzle-side portion is mounted translationally displaceable on the chamber-side portion, without which a rotary joint is provided with a rotary drive. The translational movement of the nozzle-side section is realized manually and / or by means of spring force, by means of an electromagnet and / or by means of an electric linear motor.

The adjustable frequency generator 31 is also such an adjustment device. By varying the frequency v of the alternating voltage generated by means of the frequency generator 31, it is possible to set the wavelength λ of the pressure waves 32 in the line system 36 and thus the amplitude A _{P of} the fluid pressure waves 22 in the line system 36, for example in front of the nozzle mouth 125.

Starting from the outlet opening 34 of the chamber 22, the effective line cross-section 86, 88 of the lines in the line system 36 to the nozzle mouth 82, 84 of the nozzles 38, 40 towards monotonically decreases. This causes the oscillation amplitude for the pressure of a pressure wave 32 in the direction of the fluid flow guided by the conduit system 36 in accordance with the arrow 90 to rise towards the nozzles 38, 40.

It should be noted that the device 20 can be formed in a further modified embodiment with only one nozzle or with a plurality of nozzles.

In a further modified embodiment, the device 20 can be implemented with a frequency generator 31 whose frequency v can be varied without the line system containing length-adjustable lines.

The system 10 includes a pressure pump 91 and includes a reservoir 92 having a funnel-shaped outlet 93 for collecting fluid that passes from the nozzles 38, 40 to the workpiece 15. With the pressure pump 91, the fluid for generating pulsating fluid jets in the system 10 is circulated in a circuit. The pressure pump 91 is designed so that in chamber 22, a fluid pressure in the range between 40 bar and 150 bar and preferably a fluid pressure in the order of 100 bar can be generated and adjusted. By adjusting the fluid pressure in the chamber 22, the frequency v and the amplitude A _{P of} the pressure waves, the size and spacing of liquid droplets in fluid jets 16, 18 exiting the nozzle 38, 40 can be varied.

In a modified embodiment, the system 10 may instead of the pressure pump 91, a device with a high pressure pump for the Supplying high-pressure fluid contained in the conduit system 36 of the device, which ensures a fluid pressure which can be up to 3000 bar. In order to pressurize the fluid in the system with high pressure, in particular a high-pressure pump is suitable, which provides a fluid pressure between 300 bar and 600 bar.

The Fig. 2 shows the chamber 22 for generating the fluid pressure waves 32 in the device 10. The chamber 22 has an opening 94 for supplying pressurized fluid from the high-pressure pump 91. The opening 94 is separated from the outlet opening 34 in a lateral portion the chamber 22 is arranged. The chamber 22 may be vented through an opening 96 with a controllable vent valve 98.

The sonotrode 30 is located in the chamber 22 in a dead water region 33 at a distance from the flow 35 of the fluid supplied through the opening 94 into the chamber 22 in the direction of the outlet opening 34.

To the outlet opening 34, the chamber 22 is formed in the section 99 with a funnel-shaped tapered cross-section. In section 99, the amplitude A _{P of} the pressure waves 32 generated by the sonotrode 30 of the device 24 is amplified. The graphic 100 in Fig. 2 shows with the curve 101, the amplitude of the pressure of a pressure wave 32 in the chamber 22 as a function of the distance z from the surface 26 of the sonotrode 28th

By adjusting the pressure P and the amplitude A _{P of} the pressure waves in the chamber 22, the flow rate and shape of the pulsating fluid jet generated by the nozzles 38, 40 can be adjusted.

In the chamber 22 is conveniently located a pressure sensor 102. The pressure sensor 102 is disposed in the portion 99 of the chamber 22. The pressure sensor 102 is connected to a measuring device 103, which is a display unit 105 has. The pressure sensor 102 can be used to detect the pressure fluctuations which are caused by the pressure waves 32 generated in the chamber 22 in the section 99. The display unit 105 thus allows an operator to monitor the operation of the device 20. Alternatively or additionally, the system 10 for monitoring the operation of the device 20 may also include a control computer 134 connected to the measuring device 103, which controls the device 24 for generating fluid pressure waves 32 and the pressure pump 91 as a function of the pressure fluctuation signal detected by the pressure sensor 102 ,

Alternatively or additionally, it is also possible to monitor the function of the device 20 in the system 10, e.g. the pulsating fluid jet 16, 18 exiting the nozzles 38, 40 is fed to an erosion meter (not shown). This erosion measuring device contains a test membrane to which the fluid jet is directed. In a proper operation of the device 20, a certain amount of material per unit time is removed from this test membrane. In order to detect the removal of material from this test membrane, the erosion measuring device contains a tactile sensor.

It is further alternatively or additionally provided to install a measuring device at a bypass to the outlet 93, which detects separated particles (for example a magnetic or optical particle counter), so that the function of the device 20 can be monitored in this way.

It is also advantageous if the control computer 134 includes a data memory 135 in which a parameter map 136 for the application-specific adjustment of the fluid pressure P and / or the amplitude A _P and / or the frequency v of the fluid pressure waves generated by the pressure wave generating means 32 and / or a nozzle rotation speed due a workpiece-specific application of the device 20 entered via an input unit 137 of the computer unit 136 is stored. The parameter map 136 sets, in particular, information about, for example, an empirically determined relationship between the abovementioned operating parameters and at least one of the following application parameters:
Type of material or substrate to be machined, workpiece geometry, target / actual workpiece surface finish, in particular workpiece surface roughness, type of workpiece contamination (eg chemical composition or hardness), machining distance of a workpiece to be machined for a given nozzle diameter of the Nozzle mouth of the nozzles 38, 40.

To control the system 10, the control computer 134 is connected via a control line 138 to the pressure pump 91 and connected via lines 139, 140 to the measuring device 103 and the frequency generator 31. With master computer 134, e.g. the pressure that can be generated with the pressure pump can be regulated so that wear of the nozzles used in the device 20 is compensated by increasing the pump pressure.

The Fig. 3 shows section III of the Fig. 1 with the length-adjustable conduit 62 in the device 20 in an enlarged view. The second line piece 70 is screwed into a thread 104 on the first line piece 66. The thread 104 is a fine thread. In the thread 104, the second line piece 70 can be displaced coaxially relative to the first line piece 66 corresponding to the double arrow 106. The second line piece 70 can be fixed to the first line piece 66 with a lock nut 110 arranged on the thread 108 of the second line piece 70 which is designed as a fine thread. The second line piece 70 passes through one arranged in the first line piece 66 Sealing ring 112, which prevents the escape of fluid between the first line piece 66 and the second line piece 70.

At the second line piece 70, the nozzle 36 is received. The nozzle 36 has an outside flange 114, which is pressed by means of a union nut 116 against an arranged on the end face 118 of the second line piece 70 sealing ring 119.

The Fig. 4 shows a further nozzle 39 for use in the device. The nozzle 39 has a nozzle body 120 with a nozzle chamber 122 and a nozzle mouth 125. The nozzle mouth 125 has a length L _M , which is preferably about 6 mm. The nozzle mouth 125 is conveniently in the form of a hollow cylinder. The hollow cylinder has a diameter D _M , which is preferably in the range between 0.5 mm and 3 mm and advantageously 1 mm. In the section 126 facing the nozzle mouth 125, the nozzle chamber 122 is formed with a cross-section which tapers conically towards the nozzle mouth 125. The opening angle α of the cone in the section 126 of conically tapered cross-section is obtuse. Preferably, for the opening angle a: 105 ° ≤ a ≤ 180 °. With an opening angle of the cone in the section 126 close to 180 °, the pulsating high-pressure fluid jet can be generated with fluid droplets which have a particularly favorable shape for the removal of material. With the nozzle 39 high-pressure fluid jet pulses with liquid droplets can then be generated even at a fluid pressure in a range between 300 bar and 600 bar, whose kinetic energy is so great that thus efficient removal of material is possible in particular on metallic materials.

In a further modified embodiment, the opening angle a is greater than 180 °, in particular selected to 240 °. In this case, cavitation increasingly occurs in the nozzle mouth, which in turn promotes droplet formation at the nozzle outlet.

The Fig. 5 shows a nozzle 150, which has a nozzle body 151 with a nozzle chamber 152 designed as a circular cylinder. The nozzle chamber 152 has an axially disposed end opening 154 in the nozzle mouth 156. The nozzle mouth 156 is designed as a bore. The diameter D _{B of} the bore of the nozzle mouth is about 1/3 of the diameter D _{Z of} the nozzle chamber. The nozzle mouth 156 has a length L _M which is about 6 mm. The use of such a nozzle in the device 20 described above allows even at a fluid pressure in the order of 60 bar the generation of pulsating fluid jets of water, with which metallic materials can be processed at a rapid material removal.

As nozzles for use in the device 20 are basically also so-called flat jet nozzles, star nozzles, square nozzles, triangular nozzles or nozzles that produce a fluid jet in the form of an omnidirectional.

An advantage of the device described above is that little or no cavitation occurs when operating with high-pressure liquid in the nozzles, so that then the wear of nozzles in the device is comparatively low.

The Fig. 6 shows another nozzle 170 for use in the device. The nozzle 170 has a nozzle body 171 with a nozzle chamber 172 and a nozzle mouth 173. The nozzle mouth has a length L _M which is about 6 mm and a diameter D _H ≈ 1 mm. In the section 174 facing the nozzle mouth 173, the nozzle chamber 172 is formed with a cross-section which tapers conically towards the nozzle mouth 173. The opening angle α of the cone in the section 173 of conically tapered cross section is acute. A favorable value for the opening angle a of the cone is: a ≈ 58 °.

The nozzle 170 includes a jet director 175. The jet director 175 inhibits turbulence in the pressurized fluid in the nozzle chamber 172.

The Fig. 7 shows a section of the nozzle 170 along the line VII - VII in Fig. 6 , The jet director 175 separates the nozzle chamber 172 in the section 176 into four separate flow channels 177.

In the in Fig. 1 As shown in Appendix 10, there is a means 130 for processing the fluid supplied to the chamber 22 with the pressure pump 91. In the device 130, the fluid circulated in the system 10 is freed of dirt particles. Particles and coating parts detached from a workpiece 15 are rinsed out of the workpiece in the system 10 with rinsing devices (not shown) and collected together with the fluid in a dirt tank in the device 130. The device 130 includes a filter system. With this filter system, the fluid supplied to the device 130 can remove the particles and contaminants detached from the workpiece, so as not to damage the device 20 for generating a pulsating fluid jet.

The Fig. 8 shows a system 210 for activating the surface 212 of cylinder head bores 214 in a cylinder crankcase 215 by means of pulsating high-pressure water jets 216. The assemblies in the system 210, the assemblies in the basis of Fig. 1 to Fig. 5 described in Appendix 10 are in the Fig. 8 marked with number increased by 200 numerals. In plant 210, there are a plurality of devices 220 disposed adjacent to each other for generating a pulsating high-pressure fluid jet.

In each of the devices 220, the conduit system 236 is formed with a tool portion 202 having a tool head 204 in which a plurality of Nozzles 238, 240 are included. The tool section 202 is arranged in the line system 236 by means of an automatically operable coupling device 206. The coupling device 206 allows the automatic replacement of the tool section 202 with a quick-change device (not shown) having a revolving magazine in which different tool heads are provided, which can be used in a device 220.

The nozzles 238, 240 may, for example, a reference to the Fig. 4 . Fig. 5 . Fig. 6 and Fig. 7 have described geometry. The tool section 258 with the tool head 204 can be rotated about the axis 229 by means of a drive not further shown. The nozzles 238, 240 are supplied with water, which is supplied to the device 220 with a high-pressure pump 291. For adjusting the effective path length for pressure waves generated in the chamber 222, the conduit system 236 of the device 220 includes an adjustment device 247.

In the plant 210 there is an industrial robot 211. The industrial robot 211 is a multi-axis manipulator for moving a workpiece in the form of a cylinder crankcase 215 relative to the device 220. In an alternative embodiment of the plant 210 may be provided with such an industrial robot Device 220 for generating high-pressure pulsating fluid jets by means of a handling device, in particular an industrial robot, to move relative to the workpiece.

With the industrial robot 211, the cylinder crankcases 215 are raised and lowered to the device 220 corresponding to the double arrow 217. With the pulsating high-pressure water jets 216 from the nozzles arranged in the turret 227, the surface of the material in the wall of the cylinder head bores 214 for an arc plasma coating activated by an adhesive structure is introduced into this surface. It has been found that, when the high-pressure water jet is acted upon by a pulsating high-pressure fluid jet with a direction inclined at the angle β of 0 ° ≦ β ≦ 60 °, preferably β≈45 ° to the local surface normal of the wall Tool head 204 in the cylinder head bore 214 according to the arrow 221 rotatably moved and simultaneously translates in the direction of the axis of the bore corresponding to the double arrow 223, structures, such as helical threaded structures can be generated, on which one by means of flame spraying, plasma spraying or wire arc spraying in a cylinder head bore produced layer adheres particularly well. With the device according to the invention, different degrees of roughness at different or adjacent locations of a workpiece can be generated in a particularly simple manner. In particular, more or less sliding transitions between areas of different roughness can be generated.

The Fig. 9 FIG. 12 shows a portion of a device 320 for generating a pulsating high pressure fluid jet 316 encased in a gas stream 317. The assemblies in the device 320, the assemblies in the basis of Fig. 1 to Fig. 4 are described in the device 20 are in the Fig. 6 marked with number increased by 300 numerals reference number.

The wrapping of the pulsating high-pressure fluid jet 316 in the gas stream 317 allows workpieces to be machined with the high pressure fluid jet 316 submerged in a liquid bath.

The device 320 has a nozzle 336 formed on a line piece 370. The line piece 370 is guided linearly movably in the line piece 366. It can be relocated according to the double arrow 378, so the effective path length of pressure waves between a chamber for generating pressure waves (not shown) and the side of the nozzle mouth 325 facing away from the workpiece can be adjusted.

The line piece 370 is arranged in a nozzle 369 with a nozzle chamber 371 having an opening 373 for supplying pressurized gaseous medium from a line 375 and having an outlet opening 377 from which the gas stream 317 exits. The nozzle chamber 369 and the line piece 370 can be displaced relative to each other according to the double arrow 379. By displacing the nozzle 369 relative to the nozzle 336, it is possible to adjust the shape of the fluid droplets in a pulsating high-pressure fluid jet 316 generated by the apparatus 320.

The Fig. 10 13 shows a portion of another device 380 for generating a pulsating high-pressure pulsating fluid jet 390 with a nozzle 382. The nozzle 382 has a nozzle chamber 384 with an axially disposed end opening 386 in the nozzle mouth 388. The nozzle mouth 388 is a bore designed. The diameter D _{B of} the bore of the nozzle mouth is about 1mm. At the front-side opening 386 in the nozzle chamber 384, the nozzle mouth 388 has a preferably rounded phase with the radius of curvature r <0.1 mm.

The workpiece-facing portion 381 of the nozzle 382 is configured as a funnel which widens in the direction of a pulsating fluid jet 390 exiting the nozzle orifice 388 and which has the aperture angle β≈60 °.

The shape of the workpiece-facing portion 381 of the nozzle 382 causes a gas flow passing along the outer wall 393 of the nozzle 382 to flow when the nozzle is in a liquid bath (not shown) removes liquid bath liquid from region 395 in front of the funnel-shaped section so that a pulsating high-pressure fluid jet can exit the nozzle orifice 388 unhindered and strike a workpiece located near die 382.

The Fig. 11 Figure 4 shows a device 420 for generating a pulsating high pressure fluid jet 416, 417, 418 and 419. The device 420 has a chamber 422 with a device 424 for generating fluid pressure waves 432. The device 420 has a conduit system 436 with a chamber side Section 442 and a nozzle-side portion 444. For adjusting the path length for the fluid-pressure waves 432 in the conduit system 436, the nozzle-side portion 444 relative to the chamber-side portion 442 with an adjusting device 447 corresponding to the double arrow 448 are displaced.

The Fig. 12 shows a section of the device 420 along line XII - XII in Fig. 11 , In the nozzle-side portion 444 of the conduit system 436, there is a branched in the form of a rake line 438 with four nozzles, which are integrated into the line 438. The nozzles integrated into the line 438 each have a nozzle body 450, 452, 454 and 456 which can be displaced in accordance with the double arrow 460 and has a nozzle mouth. By displacing the nozzle bodies 450, 452, 454 and 456, it is possible to obtain from the quotient of the path length L ₄₅₀ , L ₄₅₂ , L ₄₅₄ and L ₄₅₆ for the fluid pressure waves between the outlet opening of the chamber 422 and the respective nozzle mouth of the nozzle Helmholtz numbers He _n : = L _n / λ set in line system 436 and wavelength λ of fluid pressure waves 422 in line system 436 such that the amplitude A _{P of} a fluid pressure wave generated in chamber 422 in front of the nozzle orifice in question the nozzle bodies 450, 452, 454 and 456 is maximum.

The devices and systems described above are suitable for machining the surface of workpieces, for activating the surface of workpieces for coating, for processing and removing coatings on workpieces, and for cleaning workpieces.

The devices and systems described are particularly suitable for activating a workpiece surface, so that it can be coated by means of flame spraying or plasma spraying or electric arc wire spraying. The inventors have recognized that the microstructures with undercuts can be produced in the surface of workpieces by means of a corresponding pulsating high-pressure fluid jet. Thermal coatings which are applied to such a surface adhere particularly well here, because the molten particles can easily penetrate into these microstructures during coating due to the kinetic energy and due to capillary action, but then solidify there. A coating applied to a workpiece surface activated by means of a device and installation according to the invention therefore has, in particular, a high adhesive tensile strength, which may well be 30 MPa or more.

In order to ensure that the coating applied to a workpiece adheres well, it is advantageous if the surface to be coated of the workpiece is dried after activation in a device or equipment according to the invention, for example by panning, by air drying or by vacuum drying.

In particular, the inventors have recognized that a particularly good adhesion for a layer applied to the surface of a workpiece by means of flame spraying or plasma spraying or arc wire spraying can be achieved in that the surface of the workpiece initially with a pulsating high-pressure fluid jet in an inventive Plant is roughened to roughen this surface, and then the roughened surface of the workpiece with a defined contact pressure to rollers. The inventors have found that by rolling the mesoscopic projections of a roughened surface can be deformed and compressed so that this microstructures arise with undercuts, which have a high mechanical stability and in which the molten particles can easily penetrate during coating.

The devices and systems described are also suitable for the machining of workpiece coatings, such as for the removal of overspray on workpieces that have been subjected to a coating process. By the angle of attack of the pulsating high-pressure fluid jet, its exit velocity from a nozzle mouth and the frequency of the pressure waves, i. If the repetition rate for the high-pressure fluid jet is set, in particular the edges of coating sections can be processed in a defined manner on a workpiece. In particular, edges can thus be produced which form a 45 ° angle with the workpiece surface.

A finding of the inventors is also that with a pulsating high-pressure fluid jet in the coating of workpieces, such as a means of Lichtbogendrahtspritzen (LDS) generated coating on the cylinder head surfaces of internal combustion engines, a chamfer can be introduced without here as in the processing with cutting tools the There is a risk that this coating will detach from the workpiece during processing with the pulsating high-pressure fluid jets.

The devices and systems according to the invention are particularly suitable for processing a workpiece surface produced by means of flame spraying or plasma spraying or arc wire spraying and / or for Deburring of a workpiece and / or for the removal of dirt from a workpiece and / or for the removal of layers on a workpiece. The devices and systems according to the invention are also suitable for roughening workpiece surfaces, in order to prepare them for a cohesive joining (gluing, welding, soldering).

The devices and installations according to the invention may e.g. be operated with fluid in the form of wash liquor and / or water and / or emulsion, in particular water-oil emulsion and / or oil. In order to avoid the corrosion of the devices and systems according to the invention, it is advantageous to mix anti-corrosion agents with the fluid used for machining workpieces.

According to the invention with the devices and systems described above, portions of workpieces or workpieces are at least partially made of aluminum or magnesium, wherein the surface coating is applied by laser wire welding iron-containing material or the workpiece consists at least partially of steel or gray cast iron and the surface coating means Laser wire welding is applied nickel-containing material.

According to the invention, with the devices and installations described above, the surface of workpieces can also be compacted by applying a pulsating fluid jet to the workpiece. The inventors have recognized in particular that by treating cylinder crankcases made of die-cast aluminum, the voids interfering with a coating in the region of the cylinder running surfaces can be closed off with water using a pulsating high-pressure fluid jet of water.

In summary, in particular the following preferred features of the invention are to be noted: The invention relates to a device 20 for the Generating a pulsating fluid jet 16, 18 from pressurized fluid. The apparatus 20 includes a conduit system 36 having at least one nozzle 38, 40 having a nozzle mouth 125 from which a pulsating fluid jet of pressurized fluid may exit. The device 20 has a chamber 22 in which a pressure wave generating means 24 for generating fluid pressure waves 32 is formed. The chamber 22 communicates with the conduit system 36 through an exit port 34 for the generated fluid pressure waves 32. The device 20 includes an adjuster 31, 47, 62, 64 for controlling the amplitude A _{P of} the fluid pressure waves 22 in the conduit system 36 With the adjustment means 31, 47, 62, 64, a from the quotient of the path length L for the fluid pressure waves 22 between the outlet opening 34 of the chamber 22 and the at least one nozzle mouth 125 of the at least one nozzle 38, 40 in Helmholtz number He: = L / λ set in line system 36 and wavelength λ of fluid pressure waves 22 in the line system (36).

Claims (17)

1. An apparatus (20) for generating a pulsating fluid jet (16, 18) of pressurized fluid,
   comprising a line system (36), which comprises at least one nozzle (38, 40) having a nozzle orifice (125) from which a pulsating fluid jet (16, 18) of pressurized fluid can emerge, and
   comprising a chamber (22), in which a pressure wave generating device (24) for generating fluid pressure waves (32) is formed and which communicates with the line system (36) through an outlet opening (34) for the generated fluid pressure waves (32),
   characterized by
   a setting device (31, 47, 62, 64) for controlling the amplitude AP of the fluid pressure waves (22) in the line system (36) upstream of the at least one nozzle orifice (125), which setting device can be used to set a Helmholtz number He: = L / λ formed from the quotient of the path length L for the fluid pressure waves (22) in the line system (36) between the outlet opening (34) in the chamber (22) and the at least one nozzle orifice (125) of the at least one nozzle (38, 40) and the wavelength λ of the fluid pressure waves (22) in the line system (36).
2. The apparatus as claimed in claim 1, characterized in that the setting device comprises at least one line (62, 64) of adjustable length, arranged in the line system (36), for pressurized fluid (41), which can be used to adjust the path length (26) of fluid pressure waves (32) generated in the chamber (22) between the at least one nozzle orifice (125) of the at least one nozzle (38, 40) and the outlet opening (34) for fluid pressure waves (32) in the chamber (22).
3. The apparatus as claimed in claim 2, characterized in that the adjustable line (62, 64) comprises a first line section (66, 68) and has a second line section (70, 72) which is at least partially accommodated in the first line section (66, 68), which communicates therewith and which can be displaced relative to the first line section (66, 68) in the longitudinal direction thereof.
4. The apparatus as claimed in one of claims 1 to 3, characterized in that the setting device comprises means (31) for setting the frequency of the fluid pressure waves (32) generated by the pressure wave generating device (24).
5. The apparatus as claimed in one of claims 1 to 4, characterized in that the line system (36) has a first line system portion (42) with an opening for supplying fluid from a high-pressure pump (91) and has a second line system portion (44) with the at least one nozzle (38), wherein the first portion (42) and the second portion (44) are connected by a rotary joint (16).
6. The apparatus as claimed in claim 5, characterized in that the second line system portion (42) can be moved in the rotary joint (16) relative to the first line system portion (42) in a manner oscillating and/or rotating about an axis coaxial to the axis (52) of a fluid duct (60) formed in the second portion (42).
7. The apparatus as claimed in one of claims 1 to 6, characterized in that the line system has a first line system portion (42) with an opening (34) for supplying liquid to a high-pressure pump (91) and has a second line system portion (44) with a plurality of nozzles (38, 40), which can be supplied with fluid (41) through separate line branches (56, 58).
8. The apparatus as claimed in claim 7, characterized in that a line of adjustable length (62, 64) for pressurized fluid is arranged in each case in the separate line branches (56, 58) to the nozzles (38, 40), and can be used to adjust the path length (26) of fluid pressure waves (32) generated in the chamber (22) between a nozzle orifice (125) of the nozzle (38, 40) which can be supplied with fluid (41) via the line branch (56, 58) and the outlet opening (34) for fluid pressure waves (32) in the chamber (22).
9. The apparatus as claimed in one of claims 1 to 8, characterized in that the effective cross section of the lines in the line system (36) decreases between the outlet opening (34) for fluid pressure waves (32) in the chamber (22) and the nozzle orifice (125) of the nozzle (38, 40), and/or that the chamber (22) has an opening (94), spaced apart from the outlet opening (34), for supplying high-pressure fluid (41), and the fluid (41) supplied to the nozzle (38, 40) is guided through the chamber (22) and/or that the pressure wave generating device (24) is positioned in a dead water region (33) of the chamber (22) and/or that the chamber (22) has a portion (99) with a cross section which tapers like a funnel toward the outlet opening (34).
10. The apparatus as claimed in one of claims 1 to 9, characterized in that the at least one nozzle (38, 40, 170) has a nozzle chamber (122, 172) having a portion (126, 174) with a cross section which tapers toward the nozzle orifice (125, 173).
11. The apparatus as claimed in claim 10, characterized in that the portion (126) of the nozzle chamber (122) is conically tapered at an obtuse opening angle a, preferably at an opening angle α where 105° ≤ α ≤ 180°, or the portion (174) of the nozzle chamber (172) is conically tapered at an acute opening angle a, where it is preferable that α ≈ 58°, wherein a jet director (75) for avoiding or reducing turbulence is arranged in the nozzle chamber (172).
12. The apparatus as claimed in one of claims 1 to 11, characterized in that the at least one nozzle (150) has a cylindrical, preferably circular-cylindrical, nozzle chamber (152) with an opening (154) arranged at the end into the nozzle orifice (156) and/or that provision is made of a device (369, 370) for generating a gas stream (317) which envelops the pulsating fluid jet (316) at least in certain portions.
13. A plant (10) having an apparatus (20) formed as claimed in one of claims 1 to 12 for generating a fluid jet (16, 18) of pressurized fluid, characterized by a receiving device (92) for workpieces (15), in which the workpieces (15) can be subjected to a pulsating fluid jet (16, 18), and a fluid collecting device (93), in order to collect fluid (41) released by the apparatus (20), which is connected to a pressure pump (91) in order to return the collected fluid (41) into the apparatus (20) and/or characterized by a controllable device for setting the pressure of fluid supplied to the line system (36), and a computer unit (134), which is connected to the device (91) for setting the pressure P and to the pressure wave generating device (24) and has a data storage device (135), which stores a parameter map (136) for the application-specific setting of the fluid pressure P and/or the amplitude AP and/or the frequency v of the fluid pressure waves (32) which can be generated by the pressure wave generating device (24) and/or a nozzle rotational speed depending on a material to be machined, in particular a substrate, and/or depending on a workpiece geometry and/or a workpiece surface quality, in particular a workpiece surface roughness, and/or a type of workpiece contamination and/or a machining distance between a workpiece to be machined and the at least one nozzle orifice (120).
14. The use of an apparatus as claimed in one of claims 1 to 12 or of a plant as claimed in claim 13 for activating a workpiece surface (212), so that the latter can be coated by means of flame spraying or plasma spraying or arc wire spraying, and/or
    for machining a workpiece surface produced by means of flame spraying or plasma spraying or arc wire spraying, and/or
    for deburring a workpiece and/or for removing dirt from a workpiece, and/or
    for removing layers on a workpiece and/or for subjecting a workpiece surface to fluid in the form of washing liquor and/or water and/or emulsion, in particular water-oil emulsion and/or oil, and/or
    for compacting a workpiece surface by subjecting the workpiece surface to fluid, in particular to water.
15. A process for machining the wall (212) of a bore (214) in a workpiece (215) using an apparatus formed as claimed in one of claims 1 to 12, in which process the wall (212) of the bore is subjected to a pulsating high-pressure fluid jet from a nozzle which is inclined at an angle β in the range of 0° ≤ β ≤ 60°, preferably an angle β ≈ 45°, with respect to the local surface normal of the wall, wherein the nozzle is moved in a rotatory manner about the axis (229) of the bore (214) and displaced in a translatory manner in the direction of the axis (229) of the bore relative to the workpiece.
16. A process for finishing a portion of a workpiece, in which a surface coating is applied to the portion of the workpiece and in which, in a second step, the coating is machined by means of a pulsating high-pressure fluid jet, which is preferably generated by an apparatus formed as claimed in one of claims 1 to 12.
17. The process as claimed in claim 16, characterized in that the portion of the workpiece is activated, before the surface coating is applied, by means of a pulsating high-pressure fluid jet, which is preferably generated by an apparatus formed as claimed in one of claims 1 to 12.

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