Patent Application
20170225296
The present invention relates to a device, in particular for blasting a suspension onto one or more workpieces, wherein the device encompasses: At least one pressure vessel for the suspension, at least one feed line for the suspension connected to the pressure vessel at its one end, the other end of which is or can be connected to a blasting device, which can preferably be a blasting gun, at least one valve that is switched between the pressure vessel and blasting device, at least one prechamber for the suspension, which is connected to the pressure vessel with at least one valve interposed, at least one return line for the suspension, which is connected to the prechamber, preferably with a valve interposed, and a line and a valve, with which the prechamber is or can be connected to a compressed air source separate from the device, or with which the prechamber is connected to a compressed air source belonging to the device.
Generic devices are conventionally used for the surface treatment of workpieces by having the pressure from a blasting gun apply (i.e., “blast”) a suspension containing water and preferably fine-grained blasting agents onto the workpiece surface. Such a wet blasting treatment can have a grinding effect on the workpiece surface, for example, due to the abrasively acting blasting agent. Also known is a dry blasting treatment, in which a blasting agent is blasted onto the surface of workpieces without a liquid phase.
Very fine-grained, as a rule mineral, blasting agents, such as corundum, silicon carbide, glass powder, glass pearls, ceramic pearls, etc., can be used dry in blasting systems only to a very limited extent, because in addition to undesirably forming dust, they have virtually no effect on the surface of a workpiece to be machined. For this reason, they are reacted with a liquid, as a rule water, for purposes of wet blasting. This flowable mixture, consequently referred to as a suspension, can be handled similarly to a liquid, e.g., conveyed by a pump in pipes or tubes. One major challenge in systems or blasting devices that work with such suspensions involves the extremely specific differences in weight between the liquid phase and solid blasting agents in the suspension. For example, the ratio for the specific weight between water and corundum measures 1:4. An attempt is often made to keep the blasting agent suspended by means of agitating mechanisms. However, since such devices operate with rotating elements, there is a tendency for the blasting agent therein to nonetheless be deposited in the outer regions. This is more or less of a problem, depending on the blasting agent concentration in the suspension. For this reason, low concentrations have as a rule been used previously, at which the weight ratio between the solid blasting agent and liquid phase in the suspension lies within a value range of only 1:10-1:20. One requirement and concurrent difficulty has to do with the uniform distribution of the blasting agent in the liquid. The blasting result on a workpiece will to a great extent be advantageously influenced by a uniform distribution, and disadvantageously influenced by a non-uniform distribution. In order to be able to pump a suspension for a blasting process, there is also the difficulty that a centrifugal pump also acts as a centrifuge, for example, i.e., that it causes the heavier blasting agent to separate from the water, which is lighter by comparison. The higher the blasting agent concentration, the more serious the separation effect as well. This can also result in two streams forming next to each other in a pipe system, one rapidly flowing liquid stream and one slowly blasting agent stream.
In conventional blasting systems, the suspension is as a rule conveyed into an injector blasting gun by a centrifugal pump. Also known is to blow compressed air into the suspension stream. However, a large portion of the water is atomized or evaporated as a result, and the blasting agent grains impacting the workpiece thus have more or less the same “hacking” effect as when dry blasting without liquid. The difference then practically lies only in the absence of a dust problem. A generic device of the kind mentioned at the outset is known in prior art from WO 2013/079490 A2.
The object of the invention is to advantageously further develop such a generic device. In particular, the aim is to be able to thereby entirely or at least partially eliminate individual or several of the described previously existing limitations and disadvantages. The aim in particular is to advantageously further develop a generic device for blasting suspensions, thereby making a suspension suitable for the blasting process that has a higher percentage of blasting agent by comparison to the weight ratios indicated above possible in prior art. In particular, the aim is further to not have to blow compressed air into the suspension before the blasting nozzle, and spread or atomize the suspension jet.
In a first aspect of the invention, the object is initially and essentially achieved in conjunction with the features in which the valve between the prechamber and pressure vessel is a check valve, which at its one, preferably upper, terminal is connected directly or indirectly to a pressure vessel terminal that discharges into the pressure vessel through the floor of the pressure vessel, preferably at its lowest point, and its other, preferably lower, terminal is directly or indirectly connected to the prechamber, wherein the passage direction of the check valve is directed toward the pressure vessel, and the blocking direction of the check valve is directed toward the prechamber. The pressure vessel is preferably located above, either directly above or laterally above, the prechamber. In light of the described components, reference could also be made to a blasting installation or a blasting system instead of a blasting device. Within the framework of the invention, the term connected or terminal includes a direct or alternatively an indirect (e.g., interposing additional components, such as lines, valves or the like) terminal. A terminal permits a fluidic connection, which either exists permanently or, given an interposed valve, with the valve open.
The features proposed by the invention make it possible to supply a suspension into the pressure vessel from below through the floor from the prechamber. This advantageously agitates the suspension in the pressure vessel. The suspension directed upwardly from below, i.e., against gravity, enables a uniform distribution of the blasting agent in the liquid phase of the suspension without any additional measures.
In a preferred further development, the device can encompass a vacuum generating device, for example a vacuum injector or a vacuum pump, to which the prechamber is connected by means of at least one line and one valve. Alternatively or additionally, for example, a pump can be switched between the prechamber and return line, or a pump can be connected to the end of the return line facing away from the prechamber, wherein the conveying direction of the pump during operation is directed toward the prechamber. In a second aspect of the invention, these features can also be important independently of the features of the first aspect of the invention, i.e., also be independent of the characterizing features in claim 1, optionally independent of or in combination with the features indicated in the first section of the text. Here as well, the device encompasses at least one pressure vessel for a suspension and at least one prechamber for a suspension. If the return line is connected to a collection receptacle of a blasting cabinet for flowable media, e.g., for a suspension, these variants each enable a transport of the suspension from the preferably collection receptacle of a blasting cabin, which is preferably ventilated, and thus at ambient temperature or at the pressure prevailing inside the blasting cabin. In particular during the blasting operation, the suspension that downwardly deposits, downwardly flows, drips or the like in the interior of the blasting cabin accumulates in such a collection receptacle of a blasting cabin. Instead of a collection receptacle, reference could also be made to a collection terminal. The collection terminal can preferably be formed on the lower side, for example on the floor, of the blasting cabin. It is possible for the collection receptacle to encompass a receiving vessel that is at least partially open toward the top or toward the interior of the blasting cabin (“blasting chamber”). For example, this can be a cup-shaped vessel. For example, the vessel can be situated underneath an opening in the floor of the blasting cabin, which is preferably located at the lowest point of the floor, in particular underneath a grate. Reference could also be made to a collection vessel for a suspension or to an outflow vessel. The receiving vessel could also be tubular in design. Depending on the capacity of the receiving vessel, the collection receptacle can, alternatively or additionally to a receiving vessel, encompass the in particular funnel-shaped floor of the blasting cabin or a region thereof. If a vacuum generating device is used to return a suspension, the suspension can be conveyed from a collection receptacle for flowable media (e.g., a suspension) of a blasting cabin back into the pressure vessel, partially exposed to a negative pressure or partially exposed to an overpressure, and the device according to the invention requires neither pumps nor agitators given a suitable configuration. Since the suspension flows into the pressure vessel through a terminal in the floor, undesirable deposits of blasting agent can be avoided.
In a conventional blasting process, even during conventional wet blasting, blasting agent grains fly through the air from the blasting nozzle up to the workpiece surface, and their effect is based on their impact on the workpiece. Reference could thus be made to a hacking effect. By way of derogation from the above, the device according to the invention allows the solid particles added to the liquid in the suspension to be always or at least predominantly embedded in the liquid phase, so that their effect is not one of hacking, but rather of grinding. Therefore, reference could also be made to a device or method for liquid jet grinding. As relates to the mentioned aspects of the invention, there are numerous other options for preferred further development.
For example, it is possible for the device to encompass a compressed air source. However, this is not necessary. In one expedient embodiment, the device can be or is connected to a compressed air source that is separate from it, e.g., in a manner yet to be described.
In order to return a suspension from a blasting cabin, the return line can be or is connected to the latter, specifically preferably to a collection receptacle for flowable media, e.g., for a suspension, of the blasting cabin.
The valve that can be used to connect the vacuum generating device to the prechamber can preferably be a pneumatically or electrically actuated valve, for example a so-called pinch valve, which can be optionally opened or closed by means of a control valve to be electrically switched.
It is possible for the device to encompass a valve switched between the return line and prechamber, which consists of a check valve whose passage direction is directed toward the prechamber, and whose blocking direction is directed toward the return line. It is preferred that this check valve be connected preferably at its one, preferably upper, terminal directly or indirectly to a prechamber terminal, which discharges into the prechamber through the floor of the prechamber, preferably at its lowest point, and at its other, preferably lower, terminal directly or indirectly to the return line. It is possible for this check valve to be structurally identical to the check valve switched between the prechamber and pressure vessel. If this additional valve is connected to a floor terminal of the prechamber, suspension is conveyed out of the return line from the bottom up, i.e., against the sinking direction of blasting agent in the suspension, and into the prechamber, which then leads to a uniform mixing of the suspension even there.
For example, it is possible that the floor of the pressure vessel have a conical or curved shape, so that the cross section of the pressure vessel perpendicular to a vertical direction tapers downwardly, and/or that the floor of the prechamber have a conical or curved shape, so that the cross section of the prechamber perpendicular to a vertical direction tapers downwardly.
It is possible that the device encompass at least one line and one valve, with which the pressure vessel can be or is connected to a compressed air source separate from the device, or with which the pressure vessel is connected to a compressed air source belonging to the device.
In order to be able to connect the prechamber in a preferred embodiment to a compressed air source that does not comprise part of the device, i.e., is external in relation to the device, it can preferably be connected by means of a line and a valve to a compressed air terminal of the device. In order to be able to connect the pressure vessel in a preferred embodiment to a compressed air source that does not comprise part of the device, i.e., is external in relation to the device, it can preferably be connected by means of a line and a valve to a compressed air terminal of the device. Such a compressed air terminal of the device is intended for compressed air supply in the device or from an external compressed air supply line or, for example, directly from an external compressed air source (e.g., a compressor). Reference could therefore also be made to a compressed air receiving terminal of the device. For example, the compressed air terminal can encompass a pneumatic terminal element, e.g., a pneumatic plug terminal or a pneumatic threaded terminal or the like.
A vent valve is preferably connected to the pressure vessel. A throttle valve or pressure relief valve can here preferably be involved.
It is possible that the check valve switched between the prechamber and pressure vessel and/or the check valve switched between the return line and prechamber encompass at least the following components: A sealing element comprised of an elastically deformable material and a valve sleeve, which forms a seal seat that expands in the passage direction of the check valve, in particular conically, wherein the sealing element forms a sealing edge extending along its periphery, which when the sealing element moves out of an open position in a direction toward the seal seat along the sealing edge, in particular initially only along a circle, comes into contact with the seal seat.
Both check valves can preferably have an identical structural design. Viewed as expedient is an installation position for the check valves, in which the sealing element is located at the top end of the valve, and the passage direction points from the bottom up. If the sealing element is pressed toward the top from the suspension flow, this opens an annular gap through which the suspension can flow, and the check valve is in the open position. If the flow moving toward the top comes to a standstill or an unpressurized state arises, the sealing element that can move relative to the valve sleeve (i.e., the valve body) sinks toward the bottom under its own weight. The sealing element can preferably be fabricated out of an elastic material, such as rubber or polyurethane. To increase the weight, a plate, e.g., made of metal, of a desired thickness can be secured thereto. The lower edge of the sealing element can be sharp-edged at the sealing edge. As the sealing element sinks down, the first contact with the inclined valve seat thus takes place only in the form of a line. As a result, the probability that blasting agent grains will get jammed in the process is minimal. As soon as contact in the unpressurized state has occurred, the suspension located above the sealing element, which can be designed as a valve cone, bears down on the latter from above, which leads to a certain pressure being exerted on the valve seat. A certain additional pressure on the valve seat can arise if a negative pressure exists in the prechamber. The valve element is preferably constituted so as not to be deformed by this yet. The sealing element is preferably designed in such a way that it deforms at its outer edge that contacts the valve seat as the pressure in the suspension located above the valve increases, thereby resulting in a sealing surface, and the sealing element further approaches the seal seat to some extent. The deformation preferably does not take place suddenly; rather, a wedge-shaped gap preferably arises first, which successively closes from the top down, thereby downwardly forcing out liquid and solids. If no pressure gradient from the top down is present any longer, or if a pressure gradient from the bottom up prevails, the valve body once again assumes its original shape. The movability of the sealing element toward the valve seat is preferably limited, e.g., by means of a positive stop, so as to limit the deformation of the sealing element.
It is viewed as expedient that the sealing edge be bordered by two surfaces of the sealing element, which in a cross section oriented transverse to its circumferential direction run inclined to each other, in particular at a right angle to each other, wherein both surfaces of the sealing element each include an acute angle with the surface of the seal seat in a cross section perpendicular to the circumferential direction of the sealing edge. Alternatively or additionally, it is possible that the sealing element be accommodated in a longitudinally displaceable manner in the valve sleeve parallel to its longitudinal central axis, to which end the sealing element is connected in particular with guiding means that leave one or several flow-through openings in the valve cross section, and on their radially outer edge form a longitudinal guide with an inwardly pointing cylindrical surface of the valve sleeve. For example, the longitudinal guide can have a slight radial clearance of approx. 0.5 mm, which ensures an exact guidance. For example, the guiding means can be plate-like guiding lamellae, e.g., which have a thickness of only about 2 mm. The guiding lamellae thereby offer virtually no resistance to the flow, and given the only narrow radial outer edge that interacts with the valve sleeve as a guide, blockage by jammed blasting agents can be precluded. The components of the check valves preferred by the invention can also be removed and replaced in the event of wear.
It is viewed as expedient that the feed line extends through the wall of the pressure vessel and into the latter, wherein the distance between the mouth of the feed line and lowest point of the pressure vessel measures less than half, in particular less than one fourth, in particular less than one eighth, of the height of the interior of the pressure vessel. Alternatively or additionally, it is possible for the check valve switched between the prechamber and pressure vessel to be connected to a riser, in particular a riser pipe, at its lower terminal in the installation position, which extends through the upper side wall of the prechamber into its interior, wherein the distance between the lower opening of the riser and the lowest point of the prechamber measures less than half, in particular less than one fourth, in particular less than one eighth, of the height of the interior of the prechamber.
It is possible for the device to encompass a bypass line and a valve accommodated therein, wherein the one end of the bypass line discharges into the interior of the pressure vessel, in particular at more than half or three fourths of its height, in particular inside of an ascending sifter placed in the pressure vessel, and wherein the other end of the bypass line discharges into the interior of the prechamber, in particular at less than half or one fourth of its height.
In a further development viewed as expedient, the device encompasses two prechambers for a suspension, two return lines and four, preferably structurally identical, check valves, the prechambers are connected in parallel with each other and, interposing a respective check valve between each prechamber and the pressure vessel for the suspension, with the pressure vessel, and a respective return line is connected to a respective prechamber, interposing a respective check valve between the return line and prechamber.
Viewed as an expedient embodiment is that at least the pressure vessel, the prechamber or the prechambers, the check valve(s), the bypass line or bypass lines, the vacuum generating device and/or the pump as a combined assembly be situated in particular in a shared or cubic housing, out of which the feed line and return line extend, the assembly encompasses a compressed air terminal that is or can be connected to a compressed air source that belongs to the assembly or is separate from the assembly, the prechamber is connected to the compressed air terminal by at least one valve, the pressure vessel is connected to the compressed air terminal by at least one valve, and the vacuum generating device and/or pump is connected to the compressed air terminal. This enables an autonomous configuration of the device according to the invention. The blasting chamber need not be integrated into the device according to the invention; rather, the device can also be connected to a separate blasting chamber. The blasting chamber serves to blast treat the workpiece and collect the suspension used in the process in a collection receptacle, so as to return it to the circulation. A separate controller can be used to provide the device according to the invention even when blasting cabins are present, and is thus also suitable for subsequently equipping or converting blasting cabins. If the blasting cabin is not integrated into the device according to the invention, it is also possible, for example, to arrange all components of the device according to the invention (possibly with the exception of certain longitudinal sections of the feed and return lines) in a shared housing, for example in a switch cabinet, which can also contain a controller.
Depending on the different tasks at hand, nozzles with varying size and varying shape (e.g., round, square or flat shapes) can be used on the blasting device in the device according to the invention. As evident from the preceding description, the device according to the invention can be operated continuously. The suspension flows from the pressure vessel to the blasting devices, is collected in the blasting chamber once again, and conveyed back into the pressure vessel again from the bottom up. This continuous flow from the bottom up, i.e., opposite the blasting agent deposition process in the liquid phase, produces a constant and uniform mixing. An especially advantageous mixing of the suspension is achieved by introducing the latter into the pressure vessel through a terminal on the bottom side. Mixing can be improved even further by also returning the suspension into the prechamber from below through its floor. Even after prolonged downtimes, the device according to the invention enables a restarting of a plant, even after standing idle for several weeks. The described bypass line is suitable for this purpose. After a prolonged operational interruption or prolonged service life, the means described in relation thereto can be used to extract clean liquid from the pressure vessel via deposited blasting agent, and press it into the prechamber from below. From there, the liquid or suspension can again be pressed into the pressure vessel from below. Even a compact mass in the pressure vessel can be broken up and again mixed by taking this measure. Emulsion is preferably not stocked in the prechamber for a prolonged period. Instead, it is preferred that, once operation has been interrupted, e.g., with the prechamber only partially filled, a transport process be automatically initiated after a prescribed period of time, e.g., after approx. 2 minutes, in which suspension is pressed into the pressure vessel from the prechamber. Even when turning off a plant, the controller can first effect the evacuation of the prechamber.
By comparison to the check valves preferred by the invention, conventional, commercially available check valves with a flap or ball would also be suitable as a sealing element for the intended purpose, but less suitable for a variety of reasons. Solids could also become deposited on the sealing element and impede its function. Solids between the movable sealing element and valve seat could hamper or prevent the seal. The check valves preferred according to the invention are especially well suited for the circumstances that exist during suspension blasting, especially at a high blasting agent concentration. Apart from the tendency for blasting agent to sink into the liquid phase, turbulences in the mixture flow can also exert uncontrollable forces onto the movable valve part in the case of such suspensions. Therefore, it is preferred that the sealing element be precisely and robustly guided and centered.
The invention also relates to a method for wet blasting one or several workpieces, comprising at least the following procedural steps: Providing a device that exhibits individual or several of the preceding features; providing a blasting cabin if the provided device encompasses no blasting cabin; introducing the blasting device for the suspension, and in particular at least one longitudinal section of the supply line for the suspension into the interior of the blasting cabin; connecting one end of the return line for the suspension to a collection receptacle for flowable media (e.g., flowable suspension) of the blasting cabin, and introducing flowable suspension into the collection receptacle of the blasting cabin, e.g., for startup or, e.g., during operation of the device. Against the backdrop of the prior art described at the outset, the object of the invention is to advantageously further develop a generic method, so that in particular individual or several of the described limitations or disadvantages that previously existed can be diminished or avoided. As a solution, the invention proposes that the invention encompass the following as an additional procedural step:Aspirating suspension through the end of the return line connected to the collection receptacle of the blasting cabin, preferably by generating a vacuum in the prechamber and/or by turning on a pump arranged between the collection receptacle and prechamber, and opening a vent valve connected to the prechamber.
There are various options for preferred further development. It is preferred that the method encompass at least the following procedural step: Ending the aspiration of suspension through the end of the return line connected to the collection receptacle of the blasting cabin; supplying compressed air into the prechamber at least partially filled with suspension, and opening a vent valve connected to the pressure vessel, for example which is a throttle valve or a pressure relief valve. It is preferred that the method encompass at least the following procedural step: Aspirating suspension through the end of the return line connected to the collection receptacle of the blasting cabin, in particular by generating a vacuum in the prechamber and/or turning on a pump arranged between the collection receptacle and prechamber, and opening a vent valve connected to the prechamber; as this takes place, supplying compressed air to generate overpressure in the pressure vessel at least partially filled with suspension; and, given an overpressure in the pressure vessel, at least intermittently opening the valve allocated to the feed line so as to blast suspension onto one or several workpieces.
It is preferred that the method encompass at least the following: Turning off the compressed air supply in the pressure vessel; generating overpressure in the prechamber by supplying compressed air into the prechamber; given an overpressure in the prechamber, at least intermittently opening the valve allocated to the feed line, and blasting suspension onto one or several workpieces, and in particular at least intermittently opening a vent valve connected to the pressure vessel. In a preferred further development, the method encompasses at least the following procedural steps: Generating overpressure in the pressure vessel by supplying compressed air into the pressure vessel and opening the valve allocated to the bypass line, so that at least the liquid phase of the suspension or the suspension is transported from the pressure vessel into the prechamber; once a specific level has been reached in the prechamber, ending, in particular automatically ending, the supply of compressed air into the pressure vessel and generating overpressure in the prechamber by supplying compressed air, and in the process at least intermittently opening a vent valve connected to the pressure vessel and/or opening the valve allocated to the feed line for blasting suspension out of the blasting device. Alternatively or additionally, it is preferred that the suspension be blasted onto one or several workpieces, wherein the weight ratio between the overall solid phase contained in the suspension and the overall liquid phase contained in the suspension is greater than 0.5, in particular greater than 0.9, and in particular has the value 1.
The invention will be described in more detail below with reference to the attached drawings, which show preferred exemplary embodiments. Shown therein on:
a are sectional views through a check valve, which corresponds to the check valves depicted on
Introduced with regard to
During operation of the arrangement shown on
The device 1 encompasses a compressed air terminal 22, which is centralized in the example, and serves to supply the device 1 according to the invention with compressed air. To this end, for example, the compressed air terminal can be connected to an external compressed air supply line or, for example, directly to a compressed air source (e.g., to a compressor), which either belongs to the device 1 according to the invention or is not integrated into the latter. The device 1 encompasses a pneumatic line 21, in which a valve 23 is placed, and which is connected to the compressed air terminal 22 by means of a regulator unit 24. The pneumatic line 21 is connected to the pressure vessel 2 on its upper side. The pressure vessel 2 is pressure-tight in design, so that it can be exposed to a pressure freely selectable with the regulator unit 24 with the valve 23 open. For example, the valve 23 can be a two-way valve, which can optionally be opened or closed. During operation, the suspension as a rule does not fully take up the interior of the pressure vessel 2, so that an air cushion forms above the suspension, and dynamically adjusts to a varying level of suspension in the pressure vessel 2, so that the same pressure set with the regulator unit 24 always acts on the suspension during pressurization. The device 1 also encompasses a pneumatic line 25 and a valve 26 placed therein, by means of which the prechamber 10 is connected to the compressed air terminal 22. In the example, the upper side of the prechamber 10 has connected to it a line 27, whose other end is connected to a crossing 28. In the example (i.e., not necessarily), the crossing 28 has four line terminals, which are connected with each other, permanently open. The mutually open connection is symbolically denoted by a point. One end of the line 25 is connected to the crossing 28, and the other end to a line junction 29, from which the line 21 also branches, and which is connected with the compressed air terminal 22 with the regulator unit 24 interposed. The line 21 has placed into it a line junction 30 from which a throttle valve 31 branches. A vent valve 32 is connected to the prechamber 10. The vent valve 32 can be optionally opened or closed by means of a valve 33 connected thereto, which in this regard can also be referred to as a control valve. In the example, the vent valve involves a known, so-called pinch valve. The valve 33 used to control the latter is located in a line 34 that is connected to the vent valve 32, and branches away from a line 35 that is connected to the compressed air terminal 22 with an additional regulator unit 36 interposed. If the valve 33 is opened, compressed air flows into the vent valve 32, thereby closing the latter. By contrast, if the valve 33 is moved into a switch position that allows air to flow out of the pinch valve through a vent terminal of the valve 33, the vent valve 32 is opened. The valve 33 is preferably a three-way valve.
The device 1 encompasses a vacuum generating device 37, which is connected to the prechamber 10 by means of a line 38 and by means of a valve 39. In the example, the vacuum generating device 37 involves a vacuum injector. In the example, the line 38 is connected to a terminal of the crossing 28, and thereby connected to the prechamber. The vacuum generating device 37 functions based on the Venturi principle in the example. The vacuum generating device 37 is connected by means of a line 40 that incorporates a valve 41 and by means of an additional regulator unit 42 with a pressure supply line 43, which extends from the compressed air terminal 22, and from which the regulator units 24 and 36 also branch in the example (also not necessarily). For example, the valve 41 can be a two-way valve, which can optionally be opened or closed. If the valve 41 is opened, compressed air flows through the vacuum generating device 37 into the environment, which creates negative pressure in the line 38. The valve 39 also involves a pinch valve in the example. Connected to the latter for control purposes is a line 44, which in the example branches away from the line 35, and in which is placed a valve 45, a three-way valve in the example. If the valve 45 is opened, compressed air flows into the valve 39 (i.e., into the pinch valve), which is thereby closed. On the other hand, if the valve 45 is moved to a valve position in which air can escape from the valve 39 into the environment through the line 44 and through a vent terminal of the valve 45, the valve 39 is opened, thereby resulting in an open connection between the prechamber 10 and vacuum generating device 37.
The valve 7 also involves a pinch valve in the example. Connected thereto for control purposes is a line 46 with valve 47 placed therein for control purposes. The line 46 is connected with the compressed air terminal 22, with the regulator unit 36 interposed. The valve 47 involves a three-way valve in the example. If the latter is opened, compressed air flows into the valve 7, which is thereby closed. On the other hand, if the valve 47 is moved into a valve position in which air can escape from the valve 7 into the environment through the line 46 and through a terminal of the valve 47 serving as a vent, the valve 7 is opened.
The device 1 encompasses a bypass line 48 for a suspension and a valve 49 situated therein. The one end 50 of the bypass line 58 discharges into the interior of the pressure vessel 2. In the example, the pressure vessel 2 has an ascending sifter 51 placed into it from above, into which the bypass line 48 enters from above. The bypass line 48 leads pressure-tight through the wall of the prechamber, and its corresponding end 52 discharges into the interior of the prechamber 10. In the example, the valve 49 also involves a pinch valve. For control purposes, the latter is also connected to a line 53, into which is placed a valve 54, a three-way valve in the example, and which in the example is connected with the compressed air terminal 22, with the regulator unit 36 interposed. If the valve 54 is opened, compressed air flows into the valve 49, so that the latter is closed. On the other hand, if the valve 54 is switched to a valve position in which air can flow out of the valve 49 and into the environment through the line 53 and through a terminal of the valve 54 serving as a vent, the valve 49 is opened.
In the example, the regulator units 24, 36 and 42 each involve a pressure regulating valve. For example, a proportional valve can be involved. An air pressure can be set on the regulator unit 24 and used to pressurize the interior of the pressure vessel 2 and/or the interior of the prechamber 10, depending on the position of the valves 23 and 26. As will be explained below, the regulator unit 24 can be used to set or regulate the jet pressure with which the suspension is pressed out of the blasting device as a jet, i.e., blasted. For example, the valves 23, 26 involve two-way valves. As described, the valves 33, 45, 47 and 54 serve to pre-control the valves 32, 39, 7 and 49, which each involve a pinch valve. The pressure of the compressed air with which the pinch valves are actuated can be set or regulated by means of the regulator unit 36. The valve 41 can once again involve a two-way valve, for example. The regulator unit 42 can be used to set or regulate the pressure of the compressed air flowing through the vacuum generating device 37 with the valve 41 open.
It goes without saying that the described terminals of the pressure vessel 2 and prechamber 10 are outwardly pressure-tight in design on their respective housing. Secured to the pressure vessel 2 is a level sensor 55, so as to detect when the fill level of liquid or suspension has dropped below a specific level. Secured to the prechamber 10 in its lower half is a level sensor 56, so as to detect when the suspension or liquid has dropped below a specific, minimal level. In addition, the prechamber 10 has secured to it an upper level sensor 57, so as to detect when the suspension or liquid has exceeded a specific upper level. In order to automate the device 1, the valves 23, 26, 31, 33, 41, 45, 47 and 54 in the example involve electric valves, i.e., valves that can be electrically switched between the different valve positions. These valves and the level sensors 55-57 are connected with a controller of the device 1 (in a manner not shown on the figures). Marked 58 is a sensor connected to the receptacle 17, which detects the presence of the suspension, and can also be connected to the controller.
The valve 11′ between the pressure vessel 2 and prechamber 10 involves a check valve 11, which is only schematically depicted on
As relates to the selected exemplary embodiment of the check valve, for example,
In the selected example, an installation position is selected for the check valve 11 in which the longitudinal central axis 79 runs vertically, and the sealing element 66 points upwardly. During operation of the device 1, the sealing element 66 shifts automatically relative to the immovably mounted valve sleeve 67 as a function of the pressures and forces acting on the sealing element 66. Therefore, the valve need not be separately actuated. If the pressure in the prechamber 10 is greater than the pressure in the pressure vessel 2, the pressure difference produces a resultant compressive force that acts on the sealing element 66 in the passage direction 65. If the latter is greater than the opposing weight of the movable valve parts, the sealing element 66 with the valve components fastened thereto is upwardly displaced relative to the valve sleeve 67 into the open position shown on
In the exemplary embodiment shown on
In the example on
In the example on
Suspension 72 present in the pressure vessel 2 is pressed out of the blasting device 4 with the pressure prevailing in the pressure vessel 2. The feed line 3 encompasses the hose 6 and riser pipe 5 connected thereto. The riser pipe 5 passes from above through a wall of the pressure vessel 2, and extends vertically downward therein. Its downwardly open mouth 9 is located in a lower region of the interior of the pressure vessel 2, in the area of the funnel-shaped floor 61 in the example. During operation, the level probe 55 can be used to ensure that the downwardly open mouth 9 of the feed line is always immersed in the suspension 72, specifically in a container region in which a through mixing of the suspension is always ensured during operation. As illustrated by the following description, the structural design of the device 1 allows the operating process in which suspension is blasted onto one or more workpieces 19 to run independently of the processes in the pressure vessel 2, e.g., independently of the respective level of the suspension in the pressure vessel 2. The blasting process can thus run permanently, i.e., if needed over a prolonged period without interruption, or also in intervals. In order to ensure a continuous operation, the suspension in the blasting cabin 14 that exits the blasting device 4 (e.g., a blasting gun) must be returned to the pressure vessel 2 again. To this end, the prechamber 10 is provided underneath the pressure vessel 2, and connected to the return line 12 hooked up to the collection receptacle. A respective one of the check valves 11 or 13 already described with reference to
Alternatively, it would be possible to install (e.g., pneumatically or electrically) controllable valves, e.g., pinch valves, instead of the check valves 11, 13. Since activation is required for opening and closing such valves as needed, this would necessitate a greater outlay. In addition, pneumatic pinch valves would open given a compressed air supply failure, and allow the suspension located above to drain uncontrollably.
The blasting process results in a certain atomization of the liquid. In order to keep the mixing ratio in a tolerable range and not disrupt the operation of the device 1, liquid can periodically be replenished. The level probe 55 of the pressure vessel 2 monitors a minimum level. Depending on the type of plant, a warning is issued at too low a level, or a valve can be directly switched to automatically compensate for the lost liquid until at least the minimum level has again been reached.
Needless to say, several feed lines 3 can be connected to the pressure vessel 2 as needed, to which one or several respective blasting devices 4 can be connected.
In the example, the device encompasses a controller that is connected with the described valves used for controlling the pinch valves and with the level probes, which is adapted to set the operating states described for
It goes without saying that a wide range of variations from the described exemplary embodiments is possible for implementing the invention. For example, individual or several of the described components can be omitted (for example, the cyclone separator), or replaced by other, in particular identically or similarly acting components.
The above statements serve to explain the inventions encompassed by the application as a whole, which further develop the prior art least by way of the following feature combinations, each taken separately, specifically:
A device 1, characterized in that a valve 11′ between the prechamber 10 and pressure vessel 2 is a check valve 11, that its one, in particular upper, terminal 59 is connected to a pressure vessel terminal 60 that discharges into the pressure vessel 2 through the floor 61 of the pressure vessel 2, in particular at its lowest point, and that its other, in particular lower, terminal 62 is connected to the prechamber 10, wherein the passage direction 65 of the check valve 11 is directed toward the pressure vessel 2.
A device 1, characterized in that the device 1 encompasses a vacuum generating device 37, in particular a vacuum injector or a vacuum pump, to which the prechamber 10 is connected by means of at least one line 38 and one valve 39, and/or that a pump is switched between the prechamber 10 and return line 12, or a pump is connected to the end of the return line 12 facing away from the prechamber 10, wherein the conveying direction of the pump during operation is directed toward the prechamber 10.
A device 1, characterized in that the device 1 encompasses a valve 13′ switched between the return line 12 and prechamber 10, which involves a check valve 13, wherein this check valve 13 is connected at its one, especially upper, terminal 93 to a prechamber terminal 94, which discharges into the prechamber 10 through the floor 95 of the prechamber 10, in particular at its lowest point, and at its other, preferably lower, terminal 97 to the return line 12, and wherein the passage direction (98) of this check valve 13 is directed toward the prechamber 10, and wherein it is provided in particular that this check valve 13 be structurally identical to the check valve (11) switched between the prechamber 10 and pressure vessel 2.
A device 1, characterized in that the floor 61 of the pressure vessel 2 has a conical or curved shape, so that the cross section of the pressure vessel 2 perpendicular to a vertical direction tapers downwardly, and/or that the floor 95 of the prechamber 10 has a conical or curved shape, so that the cross section of the prechamber 10 perpendicular to a vertical direction tapers downwardly.
A device 1, characterized in that the device 1 encompasses at least one line 21 and one valve 23, with which the pressure vessel 2 can be connected to a compressed air source separate from the device 1, or with which the pressure vessel (2) is connected to a compressed air source belonging to the device 1.
A device 1, characterized in that the check valve 11 switched between the prechamber 10 and pressure vessel 2 and/or the check valve 13 switched between the return line 12 and prechamber 10 encompasses at least the following: A sealing element 66 comprised of an elastically deformable material and a valve sleeve 67, which forms a seal seat 70 that expands in the passage direction 65 of the check valve 11, in particular conically, wherein the sealing element 66 forms a sealing edge 71 extending along its periphery, which when the sealing element 66 moves out of an open position in a direction toward the seal seat 70 along the sealing edge 71, in particular initially only along a circle 73, comes into contact with the seal seat 70.
A device 1, characterized in that the sealing edge 71 is bordered by two surfaces 74, 75 of the sealing element 66, which in a cross section oriented transverse to its circumferential direction run inclined to each other, in particular at a right angle to each other, wherein both surfaces of the sealing element 66 each include an acute angle α, β with the surface of the seal seat 70 in a cross section perpendicular to the circumferential direction of the sealing edge 71.
A device 1, characterized in that the sealing element 66 is accommodated in a longitudinally displaceable manner in the valve sleeve 67 parallel to its longitudinal central axis 79, to which end the sealing element 66 is connected in particular with guiding means that leave one or several flow-through openings 91, and on their radially outer edge 87 form a longitudinal guide with an inwardly pointing cylindrical surface of the valve sleeve 67.
A device 1, characterized in that, when moved from an open position toward the seal seat 70, the sealing edge 71 of the sealing element 66 hits an annular zone of the seal seat 70 spaced apart from the tapered end of the seal seat 70, and that pressurizing the sealing element 66 against the seat seal 70 triggers an elastic deformation of the sealing element 66, as a result of which the sealing element 66 abuts flat against the seal seat 70 along its circumference.
A device 1, characterized in that the feed line 3 extends through the wall of the pressure vessel 2 into its interior, wherein the distance between the mouth 9 of the feed line 3 and lowest point of the pressure vessel 2 measures less than half, in particular less than one fourth, in particular less than one eighth, of the height of the interior of the pressure vessel 2.
A device 1, characterized in that the check valve 11 switched between the prechamber 10 and pressure vessel 2 is connected to a riser, in particular a riser pipe 63, at its lower terminal in the installation position, which extends through the upper side wall of the prechamber 10 into its interior, wherein the distance between the lower opening 64 of the riser and the lowest point of the prechamber 10 measures less than half, in particular less than one fourth, in particular less than one eighth, of the height of the interior of the prechamber 10.
A device 1, characterized in that the device 1 encompasses a bypass line 48 and a valve 49 accommodated therein, wherein the one end 50 of the bypass line 48 discharges into the interior of the pressure vessel 2, in particular at more than half or three fourths of its height, in particular inside of an ascending sifter 51 placed in the pressure vessel 2, and wherein the other end 52 of the bypass line 48 discharges into the interior of the prechamber 10, in particular at less than half or one fourth of its height.
A device 1, characterized in that the device 1 encompasses two prechambers 10, two return lines 12 and four, in particular structurally identical, check valves 11, 13, that the prechambers 10 are connected in parallel with each other and, interposing a respective check valve 11, with the pressure vessel 2, and that a respective return line 12 is connected to a respective prechamber 10, interposing a respective check valve 13.
A device 1, characterized in that at least the pressure vessel 2, the prechamber 10 or the prechambers 10, the check valve(s) 11, 13, the bypass line 48 or bypass lines 48, the vacuum generating device 37 and/or the pump as a combined assembly are situated in particular in a shared or cubic housing 112, out of which the feed line 3 and return line 12 extend, that the assembly encompasses a compressed air terminal 22 that is or can be connected to a compressed air source that belongs to the assembly or is separate from the assembly, that the prechamber 10 is connected to the compressed air terminal 22 by at least one valve 26, that the pressure vessel 2 is connected to the compressed air terminal 22 by at least one valve 23, and that the vacuum generating device 37 and/or pump is connected to the compressed air terminal 22.
A device 1, characterized in that the device 1 is connected to a blasting cabin 14 or encompasses a blasting cabin 14, wherein the respective blasting cabin 14 exhibits an interior 15 into which the feed line 3 extends, and wherein the return line 12 is connected to a collection receptacle 17 of the blasting cabin 14 for flowable media, e.g., for a flowable suspension, wherein it is provided in particular that the drain 17 always be in a state of pressure equalization with the environment.
A method characterized by the following procedural step:— Aspirating suspension 72 through the end 20 of the return line 12 connected to the collection receptacle 17 of the blasting cabin 14 for the suspension, in particular by generating a vacuum in the prechamber 10 and/or by turning on a pump arranged between the collection receptacle 17 and prechamber 10, and opening a vent valve 32 connected to the prechamber 10.
A method, characterized in that the method, in particular subsequently, encompasses at least the following:
A method, characterized in that the method, in particular subsequently, encompasses at least the following:
A method, characterized in that the method, in particular subsequently, encompasses at least the following:
A method, characterized in that the method, in particular subsequently, encompasses at least the following:
A method, characterized in that suspension 72 is blasted onto one or several workpieces 19, wherein the weight ratio between the overall solid phase contained in the suspension 72 and the overall liquid phase contained therein is greater than 0.5, in particular greater than 0.9, and in particular has the value 1.
All disclosed features are essential to the invention (whether taken separately or in combination with each other). The disclosure content of the accompanying/attached priority documents (copy of prior application) is hereby included in the disclosure of the application in its entirety, to include for the purpose of also incorporating features in these documents into the claims of the present application. The features in the subclaims characterize independent inventive further developments of prior art, in particular so as to generate partial applications based upon these claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2014 111 043.9 | Aug 2014 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2015/067624 | 7/31/2015 | WO | 00 |
