WO2013079488A2

WO2013079488A2 - Method, abrasives and apparatus for wet blasting

Info

Publication number: WO2013079488A2
Application number: PCT/EP2012/073750
Authority: WO
Inventors: Werner Hunziker
Original assignee: Werner Hunziker
Priority date: 2011-11-28
Filing date: 2012-11-27
Publication date: 2013-06-06
Also published as: WO2013079488A3; DE102011055770A1

Abstract

The invention relates to a method for wet blasting workpieces, comprising the provision of a suspension (10) which contains a liquid (11) and abrasives (12) that includes solid abrasive particles (13, 14), and comprising blasting the suspension (10) onto one or more workpieces for treating the workpiece surface. In order to improve said method, a suspension (10) is used the abrasives of which (12) comprise abrasive particles (13) of a first type of abrasives and abrasive particles (14) of at least one second type of abrasives that is different from the first. The invention also relates to abrasives (12) for wet blasting workpieces, said abrasives (12) comprising abrasive particles (13) of a first type of abrasives and abrasive particles (14) of at least one second type of abrasives that is different from the first. In order to improve said abrasives, abrasive particles (13) of the first type of abrasives have a higher hardness than abrasive particles (14) of the second type of abrasives, the mass of individual abrasive particles (13, 14), on average, being higher among the abrasives of the second type than among the abrasives of the first type. The invention also relates to an apparatus for wet blasting one or more workpieces.

Description

Method, blasting abrasive and apparatus for wet blasting

The present invention relates to a method for wet blasting of one or more workpieces, comprising providing suspension including at least one liquid, such as water, and blasting agent having solid blasting agent particles, and comprising accelerating and blasting from provided ones Suspension on one or more workpieces for machining workpiece surface, preferably for polishing, grinding, matting or the like of workpiece surfaces.

In the prior art, on the one hand, so-called dry-blasting processes for the surface treatment of workpieces are known. In this case, more or less finely divided, for example. Granular or dusty, so-called. Blasting agent is usually performed by compressed air as a dry flow through a supply line in a blasting gun and directed by means of the blasting gun for blasting on the surface to be machined of workpieces. Very fine-grained, in particular mineral abrasives, such as, for example, corundum, silica, glass powder, quartz powder, glass beads or the like, can be used only to a limited extent for various reasons in dry processes. On the one hand, finely grained grains tend to stick to the surface and thus prevent a blasting effect. In addition, depending on the abrasive dust problems. There are therefore known for many years, so-called. Wet blasting method in which the blasting agent is mixed with water and this sludge, also referred to as slurry is pumped with a centrifugal pump to so-called. Injector blasting guns, where by means of a strong compressed air jet the blasting additional energy can be supplied so that it achieves an effect on the irradiated surfaces. However, in the known wet blasting processes it is considered disadvantageous that the solid matter parts rapidly sink in the water-blasting agent suspension, so that the suspension must be kept in constant motion. In addition, the centrifugal pumps used in conventional wet-jet systems for pumping the suspension are subjected to great wear by the suspension and favor separation of the liquid and solid phases of the suspension, resulting in an uneven spray pattern on the workpiece surface.

The known blasting processes are used for a very wide variety of workpieces. However, in practice, there are often jet tasks where the desired effect in one operation is not or only with great expenditure of time achievable and where therefore traditionally two or more operations must be performed. These are, for example, beam tasks in which only a small workpiece removal, ie removal of material by blasting, and overall a glossy workpiece surface is desired at certain areas of the workpiece surface, while at certain other areas of the workpiece surface, for example. There, adhering burrs (eg.

Grinding burrs) should be removed with. Are used to achieve the desired smooth workpiece surface finely divided steel agent, eg. With grain sizes of No. 320 (this corresponds to a typical grain size of 16-49 μιη) to No. 500 (this corresponds to a typical grain size of 5 - 25 μιη), it requires for the removal of the adhering burrs, depending on the dimensions or the burr cross-section, quite a considerable period of time for the blasting process, so that the workpiece removal permitted there at other workpiece surface areas would already be exceeded. Against this background, the invention has the object of developing a generic method for wet blasting advantageous. In particular, it is desirable that in the course of a preferred development as far as possible one or more of the aforementioned difficulties can be completely or partially eliminated.

The object is achieved according to the invention firstly and essentially in conjunction with the features that a suspension is used, the blasting agent of which comprises blasting agent particles of a first blasting medium type and blasting agent particles of at least one second blasting medium variety. This advantageously makes it possible to select the blasting agent types which are different from each other, also in accordance with different or even possibly conflicting requirements of a blasting task on the blasting abrasive which can not be combined with a single blasting abrasive. Compared to conventional wet blasting processes in which the suspension contains only one type of blasting medium, with the wet blasting process according to the invention, the suspension of which comprises blasting agent particles of at least two or more different blasting agent types, blasting tasks in which the requirements for the blasting medium differ or contradict comparatively lesser number of operations, ideally be done in a single operation.

Inasmuch as it has been stated that the suspension comprises a liquid and abrasive containing solid abrasive particles, the phrase "solid abrasive particles" does not indicate a particular strength, but serves only to distinguish between the liquid components and solid components of the suspension. The term Strahlmittelteilchen does not specify a specific size of these particles, so that under this term in addition to, for example. granular abrasive particles also, for example, powdered Strahlmittelteilchen be taken. For the purpose of standardizing the use of language, therefore, in the context of the invention, the term "abrasive particles" and, in this broad meaning, also "abrasive grains" are used, so that the usual terms grain size, grain class, etc. can also be used for the further description. While the term Strahlmittelart in common parlance the blasting agent on the basis of a material designation and possibly based on information on the extraction or the manufacturing process, characterizes the previously selected term of blasting abrasive not only a Strahlmittelart, but also after his

Grain group, grain size, grain shape and hardness of the abrasive. Under a grain or abrasive grain is understood a contiguous particle of a blasting agent, the typical dimensions depending on the chosen grain size of a few μιτι can reach up to a few mm. The term "grain group" refers to a grain size produced with undersize and oversize, characterized by a lower and upper test grain size, in which the permitted proportions are specified outside the two test grain sizes. The so-called. Grain size is a fineness feature with the dimension length, for example. Nominal diameter of the Analysensieböffnung, which can happen just the abrasive grain. The grain shape indicates the geometric shape of the grain, for example, spherical, cylindrical, cube-shaped, irregular, with a smooth or fissured surface. To speak in this respect of two mutually different types of blasting agent is sufficient if they differ in at least one criterion. With certain blasting media, it can be observed that certain characteristics or characteristic variables change with increasing duration of use or blasting. For example, in the course of time, the size, the abrasiveness, etc., may decrease. Unless otherwise specified below for comparisons of types of blasting abrasive, these comparisons apply. at least for the still unused initial state of the blasting agent particles in question. In order for the suspension used for blasting to be retained as a mixture of liquid and solid particles, the solid blasting agent particles preferably comprise material which is insoluble in the liquid, it being possible in principle to use all the blasting agents known for the wet blasting method.

There are numerous possibilities for advantageously developing the method according to the invention for wet blasting. Thus, it is regarded as an advantageous possibility that, at least on average, abrasive particles of the first abrasive species have a higher hardness than abrasive particles of the second abrasive species and that, especially on average, the mass of individual (or each) abrasive particles is greater in the second abrasive species than in the first type of abrasive is. The average-related comparison means that an average or average value determined for the abrasive particles of the first abrasive species is compared with an average or average value to be determined for the abrasive particles of the second abrasive species. As a result of their comparatively larger mass per individual abrasive particle (or per abrasive grain), the abrasive particles of the second abrasive species have their impact on the

Workpiece surface a comparatively greater kinetic energy, on the other hand, but they have a relatively lower hardness than the Strahlmittelteilchen the first abrasive species. In this respect, it has now surprisingly been found that the use of a suspension with blasting agent particles or blasting agent particles differing from each other in this way is particularly advantageous for certain blasting tasks in which only a small workpiece removal and a high surface smoothness on certain surface areas and on the other hand at certain Oberflächenabschnit- The elimination of burrs is required, and this is now possible even in a single operation. A typical example is jet tasks, in which cutting edge machining tools form the workpieces. To round off the cutting edges, an abrasive blasting medium, such as corundum, is required. The intention is to achieve a limited rounding of the cutting edges by means of a small workpiece removal and at the same time to leave the smallest possible surface roughness. This is achieved by selecting, for example, corundum in comparatively small grain sizes as the so-called first type of blasting medium. For example. Grits from No. 320 to No. 500 can be used. The desired rounding of the

Cutting edges are effected by means of the blasting agent particles of the first type of blasting medium by a grinding and / or polishing process which produces a high surface smoothness. On the other hand, the removal of the grinding burrs by grinding away or polishing away is hardly possible or only with unreasonable effort. However, since blasting agent particles additionally contained in the suspension of the so-called second type of blasting medium have a comparatively larger mass and consequently greater kinetic energy, these can bend over the grinding burrs, eventually break off and possibly level into the surface without the action of the blasting agent particles of the so-called first Blasting grade (ie in the example of Korundstrahlmittels) to influence. The remaining after the separation of the grinding burrs possibly on the workpiece surface ridge residues can be removed due to their only small dimensions of the Strahlmittelteilchen the first type of abrasive. The blasting agent particles of the second blasting medium type preferably have a smooth surface, at least one surface which is less rough than the blasting agent particles of the first blasting medium, in order not to produce scratches on the workpiece surface. In this context, it has been proven in experiments that it is the Strahlmittelteilchen the second type of abrasive For example, to broken Duroplastgranulat, as it is, for example, in dry blasting equipment used, can act. Experiments have surprisingly shown that when wet blasting with a suspension in which Strahlmittelteilchen the first and the second blasting abrasive are included as a mixture, despite the simultaneous effect on the workpiece, the two simultaneously occurring different action mechanisms not mutually adversely affect each other, but advantageously supplement , In particular, this contributes to the fact that the blasting agent particles of the second blasting medium type which strike the workpiece surface with comparatively greater energy leave no undesirable scratches or damage there due to their suitably low hardness. It is preferred that, at least on average, the mass of the individual blasting agent particles of the second blasting medium is greater by two to four orders of magnitude than the mass of the individual blasting agent particles of the first blasting medium. The different hardness of the two types of abrasive blasting can be advantageously used in a preferred embodiment of the method, in which a workpiece is used whose hardness is less than the hardness of Strahlmittelteilchen the first Strahlmittelorte and greater than the hardness of Strahlmittelteilchen the second blasting abrasive.

In order to realize different (average) masses per abrasive particle or grain at the different blasting agent types, there is the possibility that the density and / or the volume per blasting agent particle is larger in the second blasting medium than in the first blasting medium. In this respect, it is preferable, inter alia, that the density of the material having the abrasive grains is higher than, preferably one (not necessarily integer), several times higher, and more preferably many times higher, than the density of the material of the first abrasive species in the second abrasive species. For example. For example, the material density in the second blasting medium type may be about 4 kg / dm ³ and in the first blasting medium type, for example about 1.3 kg / dm ³ . However, it should be noted that with increasing density difference in the case of conventional use of pumps, in particular of centrifugal pumps, to promote the suspension, the tendency increases that separate in the flow, the abrasive particles of the first Strahlmittelorte from the particles of the second Strahlmittelorte and accumulate in different flow areas with different flow velocities. In order to avoid this detrimental influence emanating from suspension-flowed pumps and to counteract the effects of the tendency for separation of the suspension components on the jet result, which is also present in reservoirs in principle, suitable possibilities are described below, also in connection with the attached figures Further training is proposed, also for the purpose of including corresponding features if necessary. In particular, a preferred option is shown to dispense entirely with a pump through which a suspension flows.

According to another aspect, it is preferred that, in particular average loan, the abrasiveness of the Strahlmittelteilchen the first Strahlmittelsorte is greater than the abrasiveness of the Strahlmittelteichen the second Strahlmittelsorte. There is the possibility that this distinction either only with respect to at least one selected workpiece material or a material on which for comparison purposes with each of the two blasting abrasive types of workpiece removal, preferably the so-called. Specific, ie a certain beam time or on a certain enforced blasting material amount related, workpiece removal can be determined, applies. On the other hand, however, the first abrasive species may have a higher abrasiveness compared to the second abrasive species also with respect to a whole group of materials, for example against workpieces made of metallic or ceramic materials or of plastic (in particular of elastomers or thermosets). It is furthermore preferred that, preferably on average, the mean maximum roughness of the abrasive particles of the first abrasive species is greater than the average maximum roughness of the abrasive particles of the second abrasive species.

Blasting agent particles of the first blasting medium type may alternatively or in combination, for example, have corundum, silicon oxide, silicon carbide, glass powder, quartz powder, glass beads or the like. Preferably, the abrasive particles of the first abrasive species are mineral material. With regard to the second type of blasting medium, for example, there is the possibility that the blasting agent particles have duroplastic, which may be broken thermoset granules. There is also the possibility that the blasting medium particles of the second blasting medium type have, alternatively or in combination, plastic, fine ceramics and / or zinc or aluminum granules.

According to a further aspect, it is preferred that abrasive particles of the first abrasive species are comparatively edged, and that abrasive particles of the second abrasive species have smooth surfaces in comparison thereto and are, for example, cylindrical or spherical.

Another possible area of application, in which a mixture of blasting agent mixtures of blasting agent particles or blasting abrasive species brings advantages in the suspension, or actually enables an application, are applications in which powdery blasting abrasives, such as, for example, "polishing red", are to be used for polishing purposes. Embedded in water, such agents alone have hardly any effect when wet blasting. Are the abrasive particles of the However, surprisingly, the process can advantageously be carried out by selecting, for example, polyamide grains, preferably having a smooth surface, as blasting agent particles of the second blasting medium type, the polyamide grains preferably being cylindrical or cube-like Have shape whose dimensions are preferably less than 1 mm. According to a further aspect, it is preferred that suspension is used whose abrasive particles of the second abrasive species are produced as granules, preferably of vegetable material. With such a combination of abrasives is not a processing of flat bodies in the foreground, but it can, for example, polishing and fine sanding tasks on bodies with a highly structured surface or with complex shape rational and efficient. In contrast to the usual sand blasting, where for physical reasons certain shapes and dimensions of the jet nozzles are bound, this type of wet blasting opens up a broad field of variation with regard to the type, shape and dimension of the nozzles. With little effort nozzles for a variety of tasks in almost any way possible. The invention also includes a blasting medium for wet blasting of workpieces, preferably for polishing, grinding, matting or the like of workpiece surfaces, wherein the blasting abrasive comprises abrasive particles of a first abrasive species and abrasive particles of at least one second abrasive species.

Starting from the prior art described at the outset and the limitations of conventional blasting means explained therefor, the invention The task is based on developing a generic blasting agent advantageous.

The object is achieved according to the invention firstly and essentially in conjunction with the features that abrasive particles of the first abrasive species have a higher hardness than abrasive particles of the second abrasive species and that, preferably on average, the mass of individual (or per) abrasive particles in the second abrasive species larger than the first type of blasting medium. For achievable effects and advantages, reference is made to the preceding description. For expedient development within the scope of the invention, the blasting agent may preferably have one or more of the features described above. Furthermore, the invention relates to a suspension for wet blasting of workpieces, comprising at least one liquid, preferably water, and blasting agent, which has one or more of the features described above.

The invention also includes a device for wet blasting of one or more workpieces, comprising at least one container for blasting agent-containing suspension, and a blasting device, such as a

Blasting gun, blasting nozzle or the like, which is connected by means of a beam line with the container.

Against the background of the prior art described above and the difficulties explained therefor, the invention has the object of developing a generic device for wet blasting advantageous. The object is achieved according to the invention first and essentially in conjunction with the features that the container contains suspension, which has one or more of the features described above. The device can be developed advantageously by having, for example, a blasting cubicle for receiving one or more workpieces and by having means which are adapted to the recovery of suspension from the blasting cubicle into the container, wherein it is preferably provided that the in the device total existing or circulating amount of suspension greater, preferably many times greater than the in the container, preferably on average, recorded amount of suspension. With a dimensioning of the container adapted to this, the recovery of the suspension in the container causes a flow which keeps the suspension in motion and mixes it, so that separation or separation into the various suspension components is counteracted. In order to pressurize the suspension from the container with the required jet pressure, instead of a pump through which a suspension flows, at least one pressurizing device is preferred which displaces the interior of the container in which suspension is located for the blasting process in order to displace the suspension into the supply line to the jet - Pressurized direction. In this respect, the container can also be spoken of a pressure vessel. To further aggravate segregation of the suspension in the container, the container may preferably be made taller than thick. It is preferably provided that the supply line comprises at least one mixing device, which is arranged in front of the blasting nozzle, preferably in front of the blasting gun, with respect to the suspension flow direction. Preferably, it is provided that the mixing device has a mixer housing, in which one or more mixer elements positionally and positionally fixed in the housing hollow cross-section through which suspension flows are arranged. There is also the possibility that the supply line for suspension, for example. In the form of a hose or the like or, for example. In the form of a cavity such as. A bore into the jet device, which is preferably a jet gun, extends where - In itself, the mixing device of the supply line, for example, may be wholly or partially in the blasting gun. It is preferably provided that in the mixing device a plurality of mixer elements in the flow direction of the suspension are arranged one behind the other. Preferably, it is further provided that the mixer elements are lamellae whose two longitudinal ends are connected to each other about an imaginary axis of rotation about each one, for example

Quarter turn are twisted, wherein it is preferably further provided that at least a first mixer element is present, to which a first direction of rotation of the longitudinal ends is selected to each other, and that at least a second mixer element is present, on which a second direction of rotation of the longitudinal ends is selected to each other, the is opposite to the first twisting direction. To that extent additionally existing possibilities for the preferred development is also made to the description of the figures. The invention will be further described below with reference to the accompanying figures, which show preferred embodiments. It shows:

Fig. 1 schematically simplifies a device according to the invention for

Wet blasting according to a first preferred embodiment;

Fig. 1a is an enlargement of detail Ia of Fig. 1; FIG. 2 schematically shows an apparatus according to the invention for wet blasting according to a second preferred embodiment, during the preparation of the blasting operation; FIG. FIG. 3 shows the device shown in FIG. 2, in ready-to-jet mode; FIG.

Fig. 4 shows the apparatus shown in Figs. 2, 3 during blasting operation;

5 shows the device shown in FIGS. 2 to 4, during the blasting operation with the recovery of blasting agent;

FIG. 6 shows the device shown in FIGS. 2 to 5 in the ready-to-jet mode with, in addition to FIG. 3, additionally activated circulation of the suspension in the container used for receiving and delivering suspension to the blasting pistol;

7 shows in a sectional view a pressure lock for suspension of the device according to the invention in accordance with an embodiment slightly modified from FIGS. 2 to 6 and, conversely, in enlargement;

Fig. 7a is a plan view of the lid of the pressure lock according to Figure 7, with structures and mounting elements are not shown. 8 schematically shows a device according to the invention for wet blasting in accordance with yet another preferred embodiment, in which, unlike the example of FIGS. 2 to 6, two pressure locks for suspension are provided for intermittent operation; 9 is a sectional view of a container for receiving and dispensing of

Suspension to the blasting gun in a slightly modified from Figure 8 embodiment and with respect to Figure 8 in magnification.

9a is a plan view of the lid of the container of FIG. 9;

10 schematically shows an overall view of a device according to the invention for wet blasting in accordance with the preferred exemplary embodiment shown in FIGS. 2 to 6, wherein starting from the operating state in FIG. 4 a compressed air supply device for supplying compressed air into the feed line of the suspension has been activated ;

11 is a sectional view, enlarged and shortened by means of an exploded view, of the blasting gun shown in FIG. 10 and a section of its suspension supply line with compressed air supply line connected thereto; FIG.

12 schematically shows a device according to the invention for wet blasting, according to yet another preferred embodiment, deviating from Figure 4, the compressed air supply line is connected to the mixer housing arranged in front of the blasting nozzle mixing device, with still switched off compressed air feed into the mixer housing;

FIG. 13 shows the arrangement shown in FIG. 12, but with compressed air feed into the mixer housing included in the suspension supply line; FIG. FIG. 14 is a sectional view, enlarged in comparison to FIG. 13, of the blasting gun shown there with the compressed air supply line connected to the mixer housing and FIG

Fig. 15 is a schematically simplified, high magnification of a designated in Fig. 5 with XV section of the blasting agent-containing suspension. With reference to Figures 1 and la fiction, a method according to the invention and a device 1 according to the invention, each according to a first preferred embodiment, presented. As in other figures, the representation is simplified schematically, with a partial section comparable to the view of the interior of housings and containers is possible. The device 1 comprises a blasting cubicle 2, in the inner blasting chamber 3 of which a workpiece 5 is temporarily or detachably held by means of a holder 4 for the purpose of wet-jet treatment of its workpiece surface 6. For the wet-jet method according to the invention, by means of a jet device 8, which in the example is a jet gun 9, suspension 10 is irradiated onto the freely accessible workpiece surface 6 under a jet pressure which is higher than the ambient pressure. As FIG. 1a indicates, in a very simplified form, the suspension comprises a liquid 11, in the example water, and blasting agent 12, which is composed of a very large number of solid abrasive particles 13, 14. On closer examination, the particles of abrasive particles 13 of a first type of abrasive means and of different abrasive particles 14 of a second type of abrasive medium are used. Compared to the blasting agent particles 13, the blasting agent particles 14 have a larger mass per blasting agent particle, ie a greater weight, a greater comparatively lower hardness and a comparatively smoother surface. In the example, the abrasive particles 13 are corundum and the abrasive particles 14 to Duroplastgranulat. The suspension is initially stored in a container 15 which, in view of its still-explained function and meaning, can also be referred to as a pressure container. The container 15 is in fluid communication with the jet device 8 by means of a supply line 16. At 17, a total of greatly simplified a pressurizing device is indicated. The arrow leading from there to the container 15 represents a preferred embodiment, in which the pressurizing device 17 pressurizes the interior 18 of the container 15 to displace suspension 10 into the supply line 16 with overpressure. Preferably, the pressurizing device 17 can have a compressed air source and a pressurizing line leading from there to the pressure-tight sealable container 15, so that no pump through which the suspension 10 flows is required. However, the dashed arrow extending from the pressurizing device 17 to the supply line 16 indicates that the pressurizing device 17 could alternatively be a pump which is either inserted into the supply line 16 or, for example, immersed in the container 15 as a submersible pump. orders could be.

The device 1 comprises for adding comparatively small amounts of air into the suspension a compressed air supply device 19, which includes the components contained in the imaginary system boundary 20 and the compressed air supply line 21, which in the embodiment in the flow direction 22 of the suspension 10 viewed in front of the blasting gun 9 opens from the side into the supply line 16. The compressed air supply device 19 comprises a compressed air source 32, which is, for example, a compressed air generating pump or can be a supply line. The compressed air supply line 21 has on the input side a branching into two line branches, of which the one line branch 24 has an optional opening or closing valve 26 and is fed with the valve 26 open by the compressed air source 32, wherein the air pressure in the line branch 24 means one

Pressure regulator 28 is adjustable. The other line branch 25 has a valve 29 to be optionally opened or closed and is likewise fed by the compressed air source 32 when the valve 29 is open, wherein the air pressure in the line branch 25 can be adjusted individually or deviatingly by means of a pressure regulator 31. In the example chosen, the pressure set by the pressure regulator 28 for the line branch 24 corresponds to the pressure exerted by the pressurizing device 17 on the suspension 10 in the container 15, whereas with the pressure regulator 31 for the line branch 25 a higher pressure is preselected. Of the valves 26, 29, one valve is closed in each case and the other is opened, with this assignment being reversible. If, as indicated in Figure 1 by "X", the valve 26 is closed and the valve 29 is opened, the air pressure in the compressed air supply line 21 is greater than the suspension pressure in the supply line 16, so that compressed air is fed into the supply line 16. In the reverse position of the valves 26, 29 corresponds to the air pressure in the compressed air supply line 21, the suspension pressure in the supply line 16 so that no compressed air is fed into the supply line 16, but on the other hand prevents penetration of suspension 10 in the compressed air supply line 21 becomes. For this purpose, the air pressure in the compressed air supply line 21 could also be set slightly higher if necessary. The explained different valve positions can also be clocked in time, in particular automatically, so that air is supplied during beam operation only during one or more time intervals. It has been shown that even by supply of Very small amounts of air or an air flow, which is significantly lower than the suspension volume flow, already a significant acceleration of the suspension in the jet nozzle and improving the beam effect can be achieved.

With reference to FIGS. 2 to 5, a device 1 according to the invention and a method according to the invention are presented according to a further preferred embodiment, wherein, as in the following, for features that correspond at least functionally to an example described above, the same reference numbers are used for the overview are selected. Compared to the example of FIG. 1, further components have been added. In the supply line 16 for the suspension 10, a valve 30, which in the example is a pneumatically actuated pinch valve, is arranged. This is selectively opened or closed by means of a control line 33 arranged in a control line 34. To mark a closed valve position, the symbol "X" is used. A return line 35, which extends from a pressure lock 36 arranged below the blast cabin 2 into the container 15, has also been added. In the return line 35 is a valve 62, which is also a pneumatically controllable pinch valve arranged. This is actuated by means of a control line 38 arranged in a control line 38. The container 15 is designed with respect to all ports so that it can be pressure-sealed from the environment, wherein a arranged in the pressurizing line 27 valve 39 is provided to reduce the pressure in the interior of the container 15 if necessary can. The aforementioned pressure lock 36 can also be pressure-tightly sealed off from the external environment and in its supply and discharge lines, wherein a valve is designated by 40, by means of which the pressure lock can be filled with air from the interior of the (not pressure-tight) jet. Room can be ventilated or vented. The blast cabin 2 has a funnel bottom 41, which collects sprayed suspension 10 by means of the blasting device 8, so that it can flow off into the pressure lock 36 through a central bottom opening 42 when it is open. From the pressure regulator 28 (it is a pressure control valve) branches parallel to the pressurizing line 27, which has a valve 7, which can be opened and closed optionally, and is connected to the container 15, a further pressurizing line 43 with a valve 44, which can optionally open and close, and leads into the pressure lock 36. As FIG. 7 shows with reference to a slightly deviating exemplary embodiment, an opening of the valve 44 has two

Effects. First, a cone-shaped sealing body 45 is displaced upwards against a seal seat and pressed by the inflowing compressed air, thereby sealing the bottom opening 42 pressure-tight. From an annular gap 46, which is bounded between the discharge pipe 47 of the pressurizing line 43 and a central bore in the sealing body 45, compressed air flows into the interior 48 of the pressure lock 36. When the valve 40 is closed and the valve 62 is opened, this causes in that suspension contained in the pressure lock 36 is pumped into the container 15 because of the air pressure acting on it through the return line 35 immersed in it to the bottom of the pressure lock 36. In the container 15 are the inlet opening 49 of the supply line 16 and the outlet opening 50 of the return line 35 in each case only a small, mutually equal distance above the bottom of the container 15. This is at an inflow of suspension 10 through the return line 35 in the container 15 advantageously causes a suspension flow, which leads to a desired mixing of the suspension components. 51 denotes a pneumatically operated pump, which in the example is a diaphragm pump. This is connected by means of a compressed air line 52, in which a valve 53, which can optionally open and close, is connected to a further pressure regulator 54. The total of three existing in the example pressure regulators 28, 31 and 54 may be known per se control valves, such as preferably proportional valves, act. The pump 51 can serve to mix the suspension 10 received in the container 15, preferably after longer periods of stoppage of the blasting machine, in order to counteract a drop of blasting agent in the liquid. The two connections of the pump 51 are connected to an intake pipe 55 and to an exhaust pipe 56, wherein in the container 15, the opening of the intake pipe 55 is placed well above the opening of the exhaust pipe 56. The opening of the discharge pipe 56 is located only a short distance above the bottom of the container 15. This makes it possible after longer downtime, by means of the intake pipe 55th

Absorb liquid and mix them through the discharge pipe 56 from below into the suspension 10, whereby a turbulence flow is formed, which leads to an overall uniform distribution of the blasting agent 12 in the liquid 11, and this uniform blending favors and upholds.

In the example chosen, the central compressed air source 32 is a compressed air connection. An outgoing central supply line 57 branches off parallel to the pressure regulators 28, 31 and 54. At the output of the branch 58, in which the pressure regulator 28 is located, the line branch 24, the pressurizing line 27 and the pressurizing line 43 connect in parallel with each other. At the output of the branch 59, in which the pressure regulator 31 is located, close to each other in parallel the line branch 25, the control line 37 and the control line 33 at. In this respect, in the example, the compressed air supply line 21 is indirectly connected to the compressed air source 32 with regard to the lines and valves connected therebetween. At the output of the branch 59 ', in which the pressure regulator 54 is located, connects only the compressed air line 52 at.

In the following, a preferred method for operating the device 1 will be briefly presented on the basis of various operating states. Figure 2 shows an operating condition for filling the blasting agent or the suspension 10 in the blasting chamber 3 and for its transport through the pressure lock 36 and the

The return line 35 into the container 15. The pressure lock 36 has an upper level probe 60 which indicates a corresponding filling, and a lower level probe 61, which indicates an emptying up to this level. The suspension 10 is filled with initially closed valve 44 and can thus flow into the open top pressure lock 36. When the upper level probe 36 is reached, the venting valve 40 is closed, the valve 44 is opened, thereby closing the bottom opening 42, pressurizing the pressure lock 36, and pumping suspension 10 through the return line 35 and the open valve 62 into the container 15 while the valve 39 is opened.

FIG. 3 shows a subsequent operating state in which the device 1 is in ready-to-jet mode. The suspension in the container is pressurized with the valve 7 open by the pressurizing line 27 while the valves 30, 39 and 62 are closed. By means of the air cushion formed above the suspension 10, the suspension 10 in the container is under pressure, in accordance with the pressure set on the regulator 28. FIG. 4 shows an operating state in which suspension 10 from blasting device 8 is blasted onto a workpiece 5 according to the blasting pressure determined by pressure regulator 28. For this purpose, the valve 30 was opened. The suspension pumped out or out of the container 15 is replaced by inflowing compressed air because of the still open valve 7, the pressure on the suspension 10 remaining the same. In this operating state, the valve 44 is closed and the venting valve 40 is opened, so that the bottom opening 42 is opened and the suspension 10 can flow back into the pressure lock 36.

FIG. 5 shows a further operating state in which an automatic recovery of suspension 10 takes place during the blasting operation from the pressure lock 36 into the container 15. This operating condition is triggered when the upper level probe 60 is reached. This causes valves 44 and 62 to open and valves 40 and 7 to close. The compressed air flowing through the pressurizing line 43 presses the suspension 10 out of the pressure lock into the container 15 and from there on to the jet device 8. In the container 15, which is also referred to as a pressure vessel, there is practically the same pressure as in the lock 36, and from the pressure lock 36 flows the same amount of suspension 10 to the container 15 as emerges from the jet device 8. Since, however, during the transition from the operating state of FIG. 4 to the operating state from FIG. 5, a short time interruption occurs during which the blasting process is to be continued, the flow rate of the suspension 10 through the return line 35 can be slightly higher than the flow velocity to compensate for the amount of suspension through the supply line 16. This can be achieved by lowering the pressure in the container 15 slightly below the pressure in the pressure lock 36 by means of the valve 39. Due to the resulting small pressure difference between pressure lock and container, the level in the latter rises slightly. With this measure, it can also be achieved that the recovery is slowly completed when the jet process is interrupted. If the lower level probe 61 is reached in the pressure lock, it is possible to switch back to the operating state according to FIG. 4, so that intermittent operation is possible.

From the foregoing description it is clear that the selected pressurizing device 17, which comprises the compressed air source 32, the pressurizing lines 27, 43 and their valves, enables reliable operation of the device 1. In this construction, the device 1 advantageously has no pump 10 through which the suspension flows, so that the unwanted separation of the suspension, which is typical for pumps, and the wear occurring thereon are avoided.

FIG. 6 shows a modification of the operating state shown in FIG. 3, in which the device 1 is in ready-to-jet mode. In order to mix the suspended in the container 15 under pressure suspension 10, the pump 51 was turned on.

FIG. 8 shows a device 1 according to a further preferred embodiment. This has two, parallel to the bottom opening 42 connected pressure locks 36. As can be seen from the valve positions, during the blasting operation shown in Figure 8 suspension 10 is pumped from the left in the viewing direction pressure lock 36 into the container 15, while simultaneously from the blast cabin 2 outflowing suspension 10 is collected in the adjacent pressure lock 36. Switching tion of these two functions of the pressure locks 36 can be done by means of the respective level sensors 60, 61.

FIGS. 9, 9a show a container 15 slightly modified from FIG. 8 and shown enlarged in comparison with FIG. 8. It has two connecting tubes 35 'for connecting one of the two return lines 35 present in FIG. 8. In addition, in a modification of FIG. a total of four connecting pipes 16 'are provided for the connection of a respective supply line 16 so that four jet devices 8 can be connected to it at the same time.

FIG. 10 shows an operating state in which, during the blasting operation, the compressed air supply device 19 has been set such that small air bubbles 63 are supplied to the suspension 10 flowing through the supply line 16. In the example shown, the compressed air supply device 19 comprises the compressed air supply line 21 and the compressed air source 32 and the pneumatic components located therebetween. These include the line branches 24, 25 with the valves 26, 29. It is envisaged that the line branch 24 with the pressurizing line 27 on the input side, d. H. before the valves 26 and 7, is connected, so that the pressure in the line branch 24 of the

Pressure regulator 28 is dependent. The comparatively in the example by two bar higher pressure in the other leg 25 is determined by the pressure regulator 31. In the operating state of FIG. 10, the valve 26 is closed and the valve 29 is opened so that at the connection point 64 pressurized air with about two bar pressure difference, but in only a small amount, into the

Suspension 10 is entered. In the example of FIG. 10, the connection point 64 is located in the region of a supply hose 65, which is a component of the supply line 16. The blasting device 8 shown in FIG. 11 has a blasting agent outlet opening 66 and a blasting nozzle 67 located upstream of it in relation to the suspension flow direction 22, which has a constant flow cross section in a length section viewed in the direction of flow before the blasting means outlet opening. The supply line 16 comprises a mixing device 68. In the tubular mixer housing 69, three mixer elements 70 are fixed one behind the other in the flow direction 22 in the example. These are, for example, lamellas made of plastic or of steel, the two longitudinal ends 71, 72 of which are rotated relative to each other about an imaginary rotation axis by a quarter turn each. In comparison to the two other mixer elements 70, the middle mixer element is twisted in the opposite direction in order to achieve a good mixing effect. FIG. 11 also shows that the compressed air supply line 21 is connected to the supply line 16 by means of an angle piece 73, so that the air supply takes place transversely directed to the flow direction 22. Into the angle 73, an air supply nozzle 74 is firmly inserted by means of serving as a transition conical plastic part 75, which is formed in the example as an injection needle and inserted with its tip in the supply tube 65. It can clearly be seen that the inner diameter of the air supply nozzle 74 is significantly smaller than the inner diameter of the compressed air supply line and to a much greater extent smaller than the inner diameter of the supply line 16 of the suspension 10, so that particularly finely dispersed or small air bubbles 63 in the suspension 10 (not shown in Figure 11 with) bring. In the example, the outer diameter of the air supply nozzle 74 and the injection needle is 1.2 mm.

FIG. 12 differs from the exemplary embodiment shown in FIG. 10 in that the connection point 64 of the compressed air supply line 21 is located on the supply line 16 to the mixer housing 69. While FIG. 5 indicates an operating state in which the pressure in the compressed air supply line 21 corresponds to the pressure of the suspension 10 in the supply line 16 and consequently no air bubbles are supplied, FIG. 13 indicates the alternative operating state (cf. the already explained valve positions). in which finely distributed small air bubbles are introduced into the suspension 10. In this respect, FIG. 14 illustrates in enlargement a possible connection of the compressed air supply line to the mixer housing 69 of the supply line 16.

FIG. 15, in a manner similar to FIG. 1 a, schematically illustrates the composition of the suspension 10 used in the example for blasting. This consists of a liquid 11 and blasting agent 12 distributed therein in the form of very many small solid particles. The blasting agent 12 comprises blasting agent particles 13 of a first blasting medium type as well as different or different blasting agent particles 14 of a second blasting medium type. The Strahlmittelteilchen 13 are significantly smaller than the Strahlmittelteilchen 14 and have, based on each individual Strahlmittelteilchen, a comparatively lower mass. While the abrasive particles 14 are smooth surface spheres, the abrasive particles 13 are irregular and ragged in shape and have a sharp-edged surface. In this respect, the blasting agent particles 13 when hitting a workpiece surface 6 have a higher abrasiveness compared to the blasting agent particles 14, while the steel middle particles 14 have a comparatively higher kinetic energy when hitting them.

All disclosed features are essential to the invention. In the disclosure of the application, the disclosure content of the associated in full, including for the purpose of including features of these documents in claims of the present application. The subclaims characterize in their optionally sibling version independent inventive developments of the prior art, in particular to make on the basis of these claims divisional applications.

Claims

A method of wet blasting of one or more workpieces (5), comprising providing suspension (10) comprising at least one liquid (11), such as water, and blasting media (12), the solid blasting agent particles (13, 14). comprising, and comprising the blasting of prepared suspension (10) on one or more workpieces (5) for machining workpiece surface (6), in particular for polishing, grinding, matting or the like workpiece surface (6), characterized in that a Suspension (10) is used, the blasting agent (12) comprises Strahlmittelteilchen (13) of a first Strahlmittelorte and Strahlmittelteilchen (14) at least one of them, different second Strahlmittelorte.

2. The method according to claim 1 or in particular according thereto, characterized in that, in particular average, Strahlmittelteilchen (13) of the first Strahlmittelorte have a higher hardness than Strahlmittelteilchen (14) of the second Strahlmittelorte and that, in particular average, the mass of individual Strahlmittelteilchen (13, 14) is larger in the second blasting medium than in the first blasting medium.

3. The method according to one or more of the preceding claims or in particular according thereto, characterized in that a workpiece (5) is used, whose hardness is less than the hardness of Strahlmittelteilchen (13) of the first abrasive species and greater than the hardness of Strahlmittelteilchen (14) the second abrasive species is. Method according to one or more of the preceding claims or in particular according thereto, characterized in that, in particular average, the density and / or the volume per blasting agent particles (13, 14) in the second blasting medium sort is greater than in the first blasting abrasive.

Method according to one or more of the preceding claims or in particular according thereto, characterized in that, in particular average, the abrasiveness of the Strahlmittelteilchen (13) of the first Strahlmittelorte is greater than the abrasiveness of the Strahlmittelteilchen (14) of the second Strahlmittelorte.

Method according to one or more of the preceding claims or in particular according thereto, characterized in that, in particular average, the mean maximum surface roughness of the abrasive particles (13) of the first abrasive species is greater than the average maximum surface roughness of the abrasive particles (14) of the second abrasive species.

Method according to one or more of the preceding claims or in particular according thereto, characterized in that abrasive particles

(13) of the first type of abrasive medium alternatively or in combination comprise corundum, silicon oxide, silicon carbide, glass powder, quartz powder, glass beads or the like.

(14) of the second type of blasting agent duroplastic, in particular broken thermoset granules having. Method according to one or more of the preceding claims or in particular according thereto, characterized in that blasting agent particles (14) of the second blasting medium type alternatively or in combination plastic, fine ceramics and / or zinc and / or aluminum granules or the like.

Method according to one or more of the preceding claims or in particular according thereto, characterized in that blasting agent particles (13) of the first blasting medium are edged and that blasting agent particles (14) of the second blasting means are smoother, in particular cylindrical or spherical, in comparison.

Method according to one or more of the preceding claims or in particular according thereto, characterized in that Strahlmittelteilchen (13) of the first Strahlmittelorte are dust-fine, in particular so-called. Polished red, and that as Strahlmittelteilchen (14) of the second Strahlmittelsorte polyamide grains, in particular with smoother Surface, are provided, wherein the polyamide grains in particular cylindrical or cube-like shape, whose dimensions are in particular less than one millimeter.

Method according to one or more of the preceding claims or in particular according thereto, characterized in that suspension (10) is used whose blasting agent particles (14) of the second blasting medium type are produced as granules, in particular of vegetable material.

13. Blasting agent (12) for wet blasting of workpieces (5), in particular for polishing, grinding, matting or the like of workpiece surfaces (6), wherein the blasting agent (12) Strahlmittelteilchen (13) of a first Strahlmittelorte and Strahlmittelteilchen (14) at least one of them characterized in that Strahlmittelteilchen (13) of the first Strahlmittelorte have a higher hardness than Strahlmittelteilchen (14) of the second Strahlmittelorte and that, in particular average, the mass of individual Strahlmittelteilchen (13, 14) in the second Strahlmittelsorte greater than at the first blasting medium is.

14 suspension (10) for wet blasting of workpieces (5), comprising at least one liquid (11), in particular water, and blasting agent (12) according to the preceding claim.

15. Device (1) for wet blasting of one or more workpieces (5), comprising at least one container (15) for blasting agent (12) containing suspension (10), and a blasting device (8), such as a blasting gun (9), blasting nozzle or the like, which is connected to the container (15) by means of a supply line (16), characterized in that the container (15) contains suspension (10) according to the preceding claim.

16. Device (1) according to claim 15 or in particular according thereto, characterized in that the device (1) has a blasting cubicle (2) for receiving one or more workpieces (5) and has means which are responsible for the recovery of suspension (10) are adapted from the blasting cubicle (2) into the container (15), wherein it is provided in particular that the apparatus (1) in its entirety or in surrounding running suspension amount (10) greater, in particular by a multiple greater than that in the container (15), in particular temporally average, recorded suspension amount (10).

17. Device (1) according to one or more of claims 15 and 16 or in particular according thereto, characterized in that at least one pressurization device (17) is provided, which seals the interior (18) of the container (15) for displacement of suspension (10). in the supply line (16) subjected to overpressure.

18. Device (1) according to one or more of the preceding claims 16, 17 or in particular according thereto, characterized in that the supply line (16) comprises at least one mixing device (68) with respect to the suspension flow direction (22) in front of the Blasting nozzle (67), in particular in front of the blasting gun (9), is arranged, wherein it is provided in particular in the mixing device (68) several mixer elements (70) in the flow direction (22) of the suspension (10) are arranged one behind the other It is further provided that the mixer elements (70) are lamellas whose two longitudinal ends (71, 72) are rotated relative to each other about an imaginary axis of rotation by a quarter turn, wherein it is further provided in particular that at least a first mixer element (70 ) is present, to which a first direction of rotation of the longitudinal ends (71, 72) is selected to each other, and that at least one second mixer element (70) vorhan that is to which a second direction of rotation of the longitudinal ends (71, 72) is selected to each other, which is opposite to the first direction of rotation.