Blasting container

Abstract

A blasting container for blasting workpieces with abrasive media has a wall with openings for the abrasive media to exit. Covers are located over the openings on the outside of the wall.

Description

[0001] The present invention relates to the processing of bulk materials using blasting methods. This can be carried out, for example, in drum blasting systems. A blasting container in the form of a drum with a horizontal or inclined axis is loaded with workpieces. Rotation of the drum keeps the workpieces in motion and causes them to circulate. In this way, the components change their position within the drum. This change in position can be supported by internal components within the drum that selectively influence the sliding and gliding movements of the components, or, in the case of a transverse installation, can act similarly to drop steps and thus also cause the workpieces to be turned over.

[0002] The components, held in motion in this way, are then subjected to abrasive material from nozzles or centrifugal wheels (turbines) to treat their surfaces. The movement of the workpieces (sliding, tilting, rotating, dropping, turning, etc.) is essential to ensure that all surfaces are reached during treatment and that the component surfaces are as uniform as possible.

[0003] The blasting media consists of small particles with varying geometries and size distributions. These particles impact the component surfaces directly or indirectly as rebound particles, but must then be removed. This is achieved in a drum blasting system by circulating the parts within the drum. The blasting media then collects in cavities, depressions, and the lower part of the drum. This has the added benefit of protecting the parts from damage (part against part or part against drum). However, the workpieces must then be removed from the drum, otherwise the bulk material would quickly become completely embedded in the blasting media, preventing any further surface treatment.

[0004] To remove the abrasive material from the processing chamber in the drum, its wall is equipped with openings. These openings serve two functions: Firstly, they are large enough to allow the abrasive material and surface debris to flow out of the processing chamber. This allows the abrasive material to be processed outside the processing chamber (e.g., using a classifier, sieve, etc.) and then fed back into injector nozzles or centrifugal wheels (turbines). Secondly, the openings are small enough to retain the bulk material in the drum and prevent it from entering the abrasive circuit.

[0005] These well-known blasting containers have proven effective for a wide variety of components, as the dimensions of the components differ sufficiently from the particle diameter of the blasting media in all orientations (length, width, height, diameter). Typical blasting media have similar dimensions in all three spatial directions. "Similar" here means that these dimensions are approximately the same order of magnitude, but not necessarily identical (differing by less than a factor of 10). In contrast, workpieces can be entirely or partially rod-shaped, bar-shaped, blade-shaped, or even tapered, so that their minimum dimension differs significantly from their maximum dimension. However, problems can arise during blasting if the workpieces to be processed, either entirely or in certain sections, have a dimension that is less than approximately 5 to 20 times that of the blasting particles.Components characterized by this description will subsequently be referred to as "pointed components." Examples of "pointed components" include thin rods, needles, knife blades, scissor blades, or components with protruding or pointed sections that exhibit, at least locally, geometric properties that can become entangled in the openings of the drum and thus be damaged. However, if the openings in the wall of the blast container are reduced to such an extent that the components can no longer become stuck, the blasting media will no longer be adequately removed from the processing area. Effective and efficient processing aimed at achieving a largely uniform surface finish is then no longer possible, despite the significant advantages of continuous circulation.

[0006] The object of the present invention is therefore to create a blasting container with which it is possible to blast workpieces (“pointed workpieces”) without interference if their minimum and maximum dimensions differ significantly from each other, at least in some areas.

[0007] This problem is solved by the features of claim 1 and in particular by a blasting container comprising at least one wall with an inner and an outer surface, wherein the wall is provided with a first and at least one further opening for the discharge of blasting media. A cover is provided on the outer surface of the wall above the first and the further opening, wherein a passage for blasting media is formed between the cover and the opening it covers.

[0008] The blasting container can be of any design, but is typically configured as a blasting drum rotatable around an axis of rotation, with the drum forming its perimeter. The rear wall of the blasting container can be closed, while the side opposite the rear wall may be either open, have an opening, or have a closable opening. These openings are intended solely for feeding workpieces into and out of the blasting container. The wall of the blasting container can be a fully curved perimeter wall or composed of planar or curved sections. The blasting container need not have a circular cross-section; it can also have a polygonal cross-section.It can be advantageous to have not just one and one additional opening for the exit of the blasting media, but rather a multitude of such openings in the wall. These openings can, for example, have a circular cross-section. Ovals, "smiley" shapes, triangles, rectangles, squares, or slit-like structures are also possible.

[0009] According to the invention, a cover is located over both the first and the second opening on the outside of the blast container wall. However, this cover does not completely close the opening, but is arranged such that a passage for the blasting media is formed between the cover and the opening it covers. The cover is thus mounted at a distance from the outside of the blast container wall, allowing the blasting media to exit first through the opening in the wall and then through the passage between the cover and the wall. This ensures, on the one hand, that the blasting media can flow freely through sufficiently large openings to guarantee the proper functioning of the blasting system. On the other hand, pointed workpieces are also held movable within the blast container; that is, the workpieces can neither exit the blast container nor become jammed in the openings in the wall.

[0010] It is understood that, according to the invention, it is harmless if additional openings without covers are present in the wall of the blast container, as long as these are sufficiently small to prevent workpieces from getting stuck or jammed.

[0011] The openings in the wall can, in principle, be designed in any way from above, for example round, triangular or polygonal.

[0012] Advantageous embodiments of the invention are described in the description, the drawing and the dependent claims.

[0013] According to a first advantageous embodiment, the cover can completely cover its associated opening, wherein the area of ​​the cover can in particular be larger than that of the opening.

[0014] According to a further advantageous embodiment, the cover can be planar, at least in the area of ​​the opening. The geometry of the outer contour of the opening and the cover can also be the same. For example, both the opening and the cover can have a circular outer contour, but the diameter of the cover is chosen to be larger than the diameter of the opening.

[0015] In a further advantageous embodiment, the cover can have edges curved towards the wall, or the wall can have opening edges curved towards the cover. Such bends or curved sections can create narrower gaps and even labyrinths that prevent workpieces from leaving the processing area, while still allowing the blasting media to flow freely.

[0016] In a further advantageous embodiment, the cover can be provided with raised sections on its opening-facing side to prevent the workpieces from jamming or wedged. The cover can, for example, be made of a generally flat, but structured, embossed, or corrugated sheet metal. It is also possible to provide the cover with concave or convex raised sections or indentations. Cup-like or bowl-shaped structures are also possible.

[0017] In a further advantageous embodiment, the cover can be attached to the wall, for example, detachably or permanently. Screws or welded connections are suitable for this purpose. The cover can be secured over its corresponding opening, for example, by means of struts or spacers.

[0018] In a further advantageous embodiment, the wall of the blasting container can also be double-walled, with the wall containing the openings for discharging the blasting media being an inner wall surrounded by an outer container wall, which is fitted with covers. If this outer wall is also provided with openings for the discharge of blasting media, the media can flow away unhindered. Preferably, these openings are arranged offset from the openings of the inner wall. The openings in the outer wall can be formed by punching out sections, which can then be bent over and used as spacers. For example, rib-like sections of the outer wall can be punched out, bent over, and soldered or welded to the outside of the inner wall, so that the outer wall is attached at a distance from the inner wall.

[0019] It can also be advantageous to round off the edges and corners of the openings to prevent the components from jamming. An outer edge of the covers can be bent towards the outside of the wall to reduce the gap between the wall and the cover.

[0020] Structural elements (pins, protrusions, half-shells) on the cover and / or beveled or rounded edges or rims can create simple, labyrinthine structures through which the blasting media can flow safely. Components cannot penetrate or become wedged here. Furthermore, the constant circulation of the components within the blasting container ensures that they do not remain permanently clustered, but rather repeatedly separate from one another.

[0021] According to a further advantageous embodiment, the wall in the area of ​​a recess in the container wall can be formed by an insert that is placed into the recess, wherein the insert has openings and wherein at least one cover is attached to an outer side of the insert. This results in a modular design, since different inserts with different openings can be used in the blasting container as needed. The insert can be designed to be flush with the rest of the container wall, particularly in the area of ​​the inner wall. The insert can also be provided with screens or perforated plates that allow liquid to pass through. The insert can, for example, be L-shaped, extending on one side into the container wall and on the other side into the area of ​​the container bottom.The front of the insert can form the inner wall of the container in the area of ​​the recess, with retaining ribs on the back of the insert, between which a cover is mounted.

[0022] According to a further aspect, the present invention relates to a method for blasting workpieces with blasting media in a blasting container of the type described above, wherein the maximum clear width of the openings in the container wall W max and the maximum dimension of the workpieces L max is, whereby the maximum clear width of the openings is chosen such that L max greater than W maxThis allows the size of the openings to be optimized, ensuring that the maximum clear opening width is larger than the maximum dimensions of the workpieces, preventing them from falling through the opening when placed flat over it. The cover also prevents the workpieces from penetrating the opening if they strike it perpendicularly. The maximum clear opening W max The opening can be, for example, the diameter of a round opening in a perforated sheet or the diagonal of a rectangular opening.

[0023] According to a further advantageous embodiment, the maximum dimension of the blasting medium S is max , and the minimum clear width of the passage is in the range of 3 S max up to 5 S max This dimensioning ensures that the blasting media can exit the blasting container sufficiently.

[0024] Another problem can arise if the workpieces strike the wall opening at a shallow angle. In this case, the workpieces can at least partially penetrate the opening, but then their front end will hit the cover. To prevent a workpiece from completely passing through the opening in this case, the product of the maximum clear width D can be used. max of the passage and the maximum clear width of the opening W max , divided by the minimum dimension L min The workpieces should be chosen to be smaller than the maximum dimension of the workpieces L. maxIn this case, the size of the passage and the size of the opening are chosen depending on the minimum and maximum dimensions of the workpieces so that even with a shallow penetration of a pointed workpiece into the space between the opening and the cover, part of the workpiece still protrudes from the opening, so that it does not fully immerse itself in it, but moves out of the opening again when the blast container is rotated.

[0025] The method according to the invention takes into account the fundamental dimensional differences between the blasting media and the workpieces. While the dimensions of the blasting media particles are of the same order of magnitude in all spatial directions (e.g., µm or mm), the dimensions of the workpieces or of individual elements on the workpieces differ from one another by several orders of magnitude. Examples of this are components with pointed elements such as needles with a length of 50 mm and a diameter of 0.5 mm, where the length and diameter are in a ratio of 100:1.

[0026] According to a further aspect of the present invention, it also relates to a blasting system with a blasting container of the type described above and a blasting device for applying abrasive media to workpieces located in the blasting container. The blasting device can, for example, comprise a blasting nozzle or a centrifugal wheel. Furthermore, the blasting system can have a rotary drive for the blasting container.

[0027] The present invention is described below purely by way of example with reference to advantageous embodiments and the drawing. The drawing shows: Fig. 1 a partial section through the wall of a blasting container; Fig. 2a) to h) highly schematic sections through a wall, similar to the representation Fig. 1; Fig. 3 a workpiece extending partially through an opening in the wall; Fig. 4 a perspective view of a blast container; Fig. 5 a partially cutaway view of an insert for the blast container of Fig. 4; and Fig. 6 to Fig. 8 illustrations of components of the deployment.

[0028] Fig. Figure 1 shows, in a highly schematic and purely exemplary manner, a section through a wall 10 of a blast container used for blasting workpieces with an abrasive. The blast container can be designed as a metal blast drum, open on one side, in particular, with the wall 10 having a circular or polygonal contour. The wall 10 has an inner side 12 facing the interior of the blast container and an outer side 14 facing in the opposite direction. Furthermore, the wall 10 has several openings 16 for the exit of abrasive from the interior of the container. Fig. Figure 1 shows only a first opening. However, it is understood that the wall 10 has a multitude of such openings 16.

[0029] How Fig. As further illustrated in Figure 1, a cover 18 is arranged on the outer surface 14 of the wall 10 above the opening 16. However, this cover is spaced away from the wall 10, so that a passage 20 for blasting media is formed between the cover 18 and the opening 16 it covers. The cover 18 completely covers the opening 16, and its surface area is also larger than the surface area of ​​the opening 16. In the illustrated embodiment, the cover 18 is planar in the area of ​​the opening and also beyond.

[0030] The geometry of the outer contour of the opening 16 and the cover 18 can be arbitrary in principle, whereby both outer contours can also be the same, for example circular, oval, triangular, polygonal or irregular.

[0031] At the in Fig. In the illustrated embodiment 1, the cover 18 is attached to the outside 14 of the wall 10 via spacers 22. In principle, the fastening can be achieved by screws, rivets, a one-piece connection, or a material-fit connection.

[0032] According to another embodiment, not shown, the cover 18 can also be part of an outer wall which has further openings for the emission of blasting media between the covers and offset from the openings 16 of the wall 10.

[0033] Fig. Figure 2 shows, in a highly schematic and simplified manner, various design possibilities for the cover 18 and the edge areas of the opening 16.

[0034] At the in Fig. In the embodiment shown in 2a), the edge of the cover 18 is bent downwards towards the outer side 14 of the wall 10. This is the case in the embodiment according to Fig. 2b) is also the case, in this embodiment the edge of the opening 16 is additionally bent towards the cover 18 to form a kind of labyrinth seal through which blasting media can escape to a sufficient extent, but no workpieces can escape to the outside.

[0035] In the embodiment according to Fig. 2c) The edge of the opening 16 is also bent towards the outside. However, in this embodiment, the cover 18 is designed as a planar element.

[0036] In the embodiment according to Fig. 2d) are similar to the variant according to Fig. 2b) Both the edge of the opening 16 towards the cover 18 and the edge of the cover 18 towards the wall 10 are bent over. However, in this embodiment, the edges are angled obliquely, whereas in the embodiment according to Fig. 2b) are uniformly curved.

[0037] Fig. 2e) shows a variant in which the cover 18 is provided on its side facing the opening 16 with protrusions in the form of ribs or pins 24, which are located above the opening 16.

[0038] At the in Fig. In the embodiment shown in 2f), the wall 10 is planar in the area of ​​the opening 16. However, a convex dome 26 is provided on the cover 18 in the area of ​​the opening 16.

[0039] In the embodiment according to Fig. 2g) In the area of ​​the opening 16, the wall 10 is again planar. However, the cover 18 has the form of a corrugated sheet or checker plate.

[0040] Finally, in the embodiment of Fig. 2h) Several pins 28 are attached to the cover 18, located above the opening 16. Otherwise, the cover 18, like the wall 10, is planar.

[0041] Fig. Figure 3 shows a purely schematic representation of a workpiece 30, which extends partially through the opening 16 in the wall 10 and with its one (in Fig. 3 left) end rests against cover 18. In Fig. 3 is the maximum clear width of the opening 16 with W max designated as the maximum dimension L max In the illustrated embodiment, the workpiece 30 extends in the longitudinal direction and has a minimum dimension L min The workpiece 30 extends perpendicularly to it and also in the plane of the drawing. It is therefore a rod-shaped or pin-shaped workpiece, for example scissors, parts of scissors, surgical instruments, or the like.

[0042] Also in Fig. The maximum clear width D is shown in point 3. max of the passage 20. The maximum dimension L max The workpiece 30 is larger than the maximum clear width W. max the opening 16th.

[0043] Furthermore, it can be advantageous if the maximum clear width of the passage 20 is approximately 3 to 5 times larger than the maximum dimension S. max (not shown in the figure) of the abrasive. This ensures that the abrasive can flow through the passage 20 with a sufficient flow rate.

[0044] Fig. Figure 3 further clarifies that there is a critical length for the workpiece 30 (in Fig. (3, shown with a dashed line), in which the workpiece 30 could fall completely into the gap between wall 10 and cover 18 and thus exit the blast container. However, it has been found that this does not occur if the maximum dimension L max The workpieces are 30 greater than or equal to the product of the maximum clear width D. max of the passage 20 and the maximum clear width W max the opening 16, divided by the minimum dimension L minof workpiece 30. In this case, it can be advantageous if the maximum dimension L max The workpieces are chosen to be slightly larger, for example 10-15% larger, to prevent the workpieces from getting stuck in the Fig. The position shown in point 3 can be ruled out with certainty.

[0045] A blast container of the type described above can be used in a blasting system equipped with a blasting device for applying abrasive media to workpieces located in the blast container. A rotary drive can be provided for the blast container to rotate it during blasting. The blast container can be equipped with an inlet and outlet opening, which may optionally be closable.

[0046] Fig. Figure 4 shows a perspective view of an embodiment of such a blasting container 50, whose circumferential wall 10 has an inner side 12 and an outer side 14. In the illustrated embodiment, the circumferential wall is not purely cylindrical, but composed of different planar segments extending circumferentially and radially. The circumferentially oriented segments of the circumferential wall in the illustrated embodiment are provided with rectangular recesses, into each of which an insert 52 is inserted, forming the wall in the area of ​​the recesses.

[0047] The 52 unit, with its individual components, is located in the Fig. 6, Fig. 7 to Fig. 8 is explained in more detail. How in particular Fig. As illustrated in Figure 7, the insert 52 has, for example, a rectangular plate 54 with several rectangular openings 16 arranged parallel to one another. In the area of ​​the recess, the front or inner side of the plate 54 thus forms the wall 10. On the back of the plate 54, rear webs 56 are attached to both sides of each opening 16, with a rectangular cover 18 being attached between each pair of adjacent webs, the two outer ends of which are angled obliquely (see also Figure 7). Fig. 5) This arrangement is approximately the same as that of Fig. 2a) The arrangement is such that between each cover 18 and the opening 16 it covers, in the area of ​​the angled ends of the cover 18, there is a passage 20 (see below). Fig. 5) is formed for blasting media.

[0048] To assemble the insert 52, the prepared plate 54 is attached to an L-shaped support 58. A spacer 60 with flow openings can also be arranged between the support 58 and the plate 54.

[0049] The shorter leg of the support 58 can be covered with a cover plate 62. This can also be designed as a sieve plate, with corresponding recesses provided in the bottom of the container 50 into which the shorter leg of the insert 52 is inserted flush.

[0050] Fig. Figure 5 shows a partially cut-down side view of insert 52 from Fig. 4 and Fig. 8. As can be seen, the trapezoidal cover 18 is attached to the web 56 on both sides, with the openings 20 being formed between the plate 54 and the cover 18 in the area of ​​the opening 16.

[0051] The container wall 12 can contain flow openings 51 for blasting fluids (e.g., gases, usually air, or liquids, usually water), particularly in the area of ​​its radially extending segments. These fluids either enter the drum from two-fluid nozzles (gas / abrasive or water / abrasive) or are entrained from the surroundings, for example, as air by abrasive exiting centrifugal wheels at high velocity. These blasting fluids accumulate on the surfaces and must be discharged from the drum to prevent adversely affecting the blasting process.

Claims

[1] Blasting container for blasting workpieces (30) with an abrasive, comprising at least one wall (10) with an inner side (12) and an outer side (14), wherein the wall (10) is provided with a first and at least one further opening (16) for an outlet of abrasive, characterized by , that on the outside (14) of the wall (10) there is a cover (18) above the first and above the further opening (16), wherein a passage (20) for blasting media is formed between the cover (18) and the opening (16) it covers. [2] Blasting container according to claim 1, characterized by that the cover (18) completely covers the opening (16), wherein the area of ​​the cover (18) is in particular larger than that of the opening (16). [3] Blasting container according to claim 1 or 2, characterized by that the cover (18) is planar in the area of ​​the opening (16). [4] Blasting container according to one of the preceding claims, characterized by , that the geometry of the outer contour of opening (16) and cover (18) is the same. [5] Blast container according to one of the preceding claims, wherein the cover (18) has curved edges in the direction of the wall (10), or wherein the wall (10) has curved opening edges in the direction of the cover (18). [6] Blasting container according to one of the preceding claims, characterized by , that the cover (18) is provided with protrusions (24, 26, 28) on its side facing the opening (16). [7] Blasting container according to one of the preceding claims, characterized by , that the cover (18) is attached to the wall (10). [8] Blasting container according to one of the preceding claims, characterized by that it is double-walled, wherein the wall (10) with the openings (16) is an inner wall surrounded by an outer wall which is provided with the covers. [9] Blasting container according to claim 8, characterized by, that the outer wall is also provided with openings for the exit of blasting media, which are arranged offset from the openings (16) of the inner wall (10). [10] Blasting container according to one of the preceding claims, characterized by , that the wall in the area of ​​a recess is formed by an insert (52) which is inserted into the recess, wherein the insert (52) has the openings (16) and at least one cover (18) is attached to an outside of the insert (52). [11] Method for blasting workpieces (30) with blasting media in a blasting container according to one of the preceding claims, wherein - the maximum clear width of the openings (16) W max is, and - the maximum dimension of the workpieces (30) L max is, whereby - L max greater than W max is. [12] Method according to claim 11, wherein the maximum dimension of the blasting medium S maxis, and the minimum clear width of the passage (20) in the range of 3 S max up to 5 S max lies. [13] Method according to claim 11 or 12, wherein the maximum dimension of the workpieces (30) L max is greater than or equal to the product of the maximum clear width D max of the passage (20) and the maximum clear width of the opening (16) W max , divided by the minimum dimension L min the workpieces (30). [14] Method according to any one of claims 11 to 13, wherein the workpieces (30) are at least partially rod-shaped, pin-shaped, blade-shaped and / or tapered to a point. [15] Blasting system comprising a blasting container according to one of claims 1 to 10 and a blasting device for applying blasting media to workpieces (30) located in the blasting container.

Images