WO2022211714A1

WO2022211714A1 - Blast cabinet with a directed exhaust

Info

Publication number: WO2022211714A1
Application number: PCT/SE2022/050313
Authority: WO
Inventors: Ulf QVIBERG
Original assignee: Am Efficiency Nordic Ab
Priority date: 2021-04-01
Filing date: 2022-03-30
Publication date: 2022-10-06
Also published as: SE2150418A1; SE545087C2; EP4313487A1

Abstract

The disclosure relates to a blast cabinet (100) for blasting at least one object by directing a flow of blasting media from a blasting nozzle (101) arranged within the blast cabinet (100) towards a point of blasting (102) of the at least one object, whereby the blasting media and waste material removed from the at least one object are mixed within the blast cabinet (100). The blast cabinet (100) comprises a directed exhaust (106) comprising an exhaust pipe (108), extending from an exhaust outlet (110) in an outer wall of the blast cabinet (100) to an interior volume (112a,112b) of the blast cabinet (100) containing a relatively high concentration of waste material and a relatively low concentration of blasting media during blasting of the at least one object. The exhaust pipe (108) comprises at least one exhaust pipe inlet (114a, 114b) configured to withdraw gas from the interior volume (112a,112b) for removal of waste material from the blast cabinet (100) via the exhaust outlet (110).

Description

BLAST CABINET WITH A DIRECTED EXHAUST

Technical field

The present disclosure relates to a blast cabinet for blasting at least one object by directing a flow of blasting media from a blasting nozzle arranged within the blast cabinet towards a point of blasting of the at least one object. More specifically, the disclosure relates to a blast cabinet as defined in the introductory parts of claim 1 .

Background art

Abrasive blasting techniques, or simply blasting, may be used to remove coatings, scale, dirt, grease, corrosion, waste material or other contaminations from the surface of an object. Blasting may also be used in the post-processing of components manufactured through additive manufacturing techniques, also known as 3D printing. For example, blasting is commonly used for removal of residual material from additively manufactured parts produced with powder bed-based 3D printing techniques, including Selective Laser Sintering (SLS), Multi Jet Fusion (MJF) and High Speed Sintering (HSS).

Abrasive blasting of objects, such as additively manufactured parts, often take place in a blast cabinet. A blast cabinet may be a manual blast cabinet for manual blasting of objects within the cabinet via a hand-held blasting nozzle, or it may be an automatic blast cabinet for automatic blasting of objects via a fixed and automatically operated blasting nozzle of the blast cabinet. Automatic blast cabinets typically comprise a movable member for accommodating and moving the objects to be blasted, e.g., in form of a rotating cylindrical drum. When the movable member moves, the objects tumble and fall into a point of blasting where they are subjected to a flow of blasting media from the blasting nozzle.

In abrasive blasting processes, waste material is removed from the blasted objects by the impact on the objects of the blasting media. The waste material may comprise contaminants, residual material from manufacturing processes, and/or constituent material of the objects themselves. The waste material typically contains very fine grained particles and is usually referred to as abrasive blasting dust, or simply dust. In order to increase the visibility within the blast cabinet and to improve the efficiency of the blasting process, the blast cabinet may be provided with an exhaust for removal of the waste material from the blast cabinet. Typically, the exhaust comprises an outlet formed in an outer wall of the cabinet, which outlet is connected to an extractor unit for withdrawal of gas out from the cabinet via the exhaust outlet.

The blasting media used in a blast cabinet is typically a relatively hard particulate material, such as steel shot, glass beads, aluminium oxide, plastic particles, or the like. For economic and environmental purposes, the blasting media should preferably be collected and reused. To this end, the blast cabinet may be equipped with a so called blasting media reclaimer, which is an arrangement for recycling reusable blasting media.

A problem with blast cabinets of the prior art is that the dust exhaust does not effectively remove the dust from the interior of the blast cabinet, which impedes visibility and causes dust to mix with the blasting media in the blasting media reclaimer, thereby complicating or even preventing reuse of blasting media.

Traditionally, this problem has been addressed by increasing the exhaust flow, e.g. by increasing the power of a motor-driven extractor unit coupled to the exhaust outlet. However, this has the undesired effect of venting not only the dust but also the blasting media, or at least a non-negligible amount of blasting media, out from the blast cabinet, thereby preventing or at least impairing the reuse of blasting media.

Summary

It is an object of the present disclosure to mitigate, alleviate or eliminate one or more of the above-identified deficiencies and disadvantages in the prior art.

It is another object of the present disclosure to provide means for improved operation of a blast cabinet. It is yet another object of the present disclosure to provide means for improved visibility during blast cabinet operations, and for increased reusability of blasting media in blast cabinets.

These and other objects, which will become apparent in view of the detailed description following hereinafter, are achieved in accordance with the present disclosure by a blast cabinet as defined by the appended claims.

According to one aspect there is provided a blast cabinet for blasting at least one object by directing a flow of blasting media from a blasting nozzle within the blast cabinet towards a point of blasting of the at least one object, whereby the blasting media and waste material removed from the at least one object are mixed within the blast cabinet. The blast cabinet comprises a directed exhaust comprising an exhaust pipe extending from an exhaust outlet in an outer wall of the blast cabinet to an interior volume of the blast cabinet containing a relatively high concentration of waste material and a relatively low concentration of blasting media during blasting of the at least one object. The exhaust pipe comprises at least one exhaust pipe inlet configured to withdraw gas from the interior volume for removal of waste material from the blast cabinet via the exhaust outlet.

The effect of providing the blast cabinet with a directed exhaust having an exhaust pipe extending into the blast cabinet to withdraw gas from an interior volume of the blast cabinet containing a relatively high concentration of waste material and a relatively low concentration of blasting media is that waste material can be efficiently removed from the blast cabinet while minimizing the amount of blasting media that is vented out of the exhaust. As compared to a solution where gas is vented directly out of the blast cabinet via an exhaust outlet arranged in an outer wall of the blast cabinet, the directed exhaust of the present disclosure allows the same amount of waste material to be removed from the blast cabinet using a substantially reduced exhaust flow since the exhaust pipe inlet is arranged “closer” to high concentrations of waste material. Furthermore, the reduced exhaust flow and the relatively low concentration of blasting material at the location of the exhaust pipe inlet significantly reduces the amount of blasting material that is vented out of the blast cabinet. In other words, the directed exhaust increases the amount of waste material in relation to the amount of blasting media in the exhaust gases while decreasing the amount of waste material in relation to the amount of blasting media within the blast cabinet. Among other things, this provides the advantages of increasing the visibility within the blast cabinet, facilitating post-processing of exhaust gases, and facilitating reuse of the blasting media by reducing the cumbersome burden of filtering the used blasting media before recycling the blasting media to the blasting nozzle.

According to some embodiments, the blast cabinet comprises a movable member configured to accommodate and move the at least one object during blasting operations, wherein the at least one exhaust pipe inlet is arranged in close proximity of the movable member.

The movable member serves to move the object in relation to the blasting nozzle, and/or to change the orientation of the object in relation to the blasting nozzle, such that the stream of blasting media from the blasting nozzle hits different surfaces of the object during the blasting operation. This is especially advantageous if the blasting nozzle is a stationary blasting nozzle, e.g. a stationary blasting nozzle of an automatic blast cabinet. By arranging the exhaust pipe inlet in close proximity of the outside of the movable member, the exhaust pipe may be stationary arranged within the blast cabinet with its inlet still being located relatively close to the point of blasting, at a location where waste material concentrations are high. Another advantage of the exhaust pipe inlet being arranged in close proximity of the outside of the movable member is that the fine-grained waste material tends to adhere to the surface of the movable member, thus making the movable member surface serve as a collector of waste material. The proximity between the at least one inlet and the movable member thus ensures that large amounts of waste material will be drawn into the inlet and be removed from the blast cabinet.

According to some embodiments, the movable member is at least partly permeable to the waste material in order for the waste material to penetrate the movable member from a first side of the movable member on which the point of blasting is located, to a second side of the movable member, wherein the at least one exhaust pipe inlet is arranged in close proximity of the second side of the movable member. The separation between the exhaust pipe and the point of blasting by the movable member serves to structurally shield the point of blasting from the directed exhaust while the permeability of the movable member permits waste material to be drawn into the exhaust pipe inlet from both sides of the movable member, thereby providing for efficient removal of waste material.

According to some embodiments, the movable member is a rotatable cylindrical drum arranged in a substantially vertical plane within the blast cabinet and configured to accommodate the at least one object within the drum. At least a part of a lateral surface of the cylindrical drum is permeable to the waste material, and the at least one exhaust pipe inlet is arranged in close proximity of, and directed towards, the lateral surface of the drum. The substantially vertically arranged rotatable drum causes the at least one object to tumble and turn while remaining at substantially the same position within the blast cabinet, which position is also the point of blasting of the at least one object. In accordance with the above rationale, waste material will adhere to the inside and the outside of the lateral surface of the cylindrical drum and, by arranging the exhaust pipe inlet in close proximity of the lateral surface of the cylindrical drum, the inside and outside of the lateral surface of the drum are efficiently cleaned from waste material. Furthermore, due to the rotation of the cylindrical drum, the exhaust pipe inlet may be stationary arranged on an outside of the lateral surface and still be brought in close proximity of the entire lateral surface of the cylindrical drum.

According to some embodiments, a rear end of the cylindrical drum comprises a back- wall structure for retaining the at least one product in the cylindrical drum, wherein at least parts of the back-wall structure is permeable to the waste material. In this case, the at least one exhaust pipe inlet may be arranged in close proximity of, and directed towards, said back-wall structure. In this way, advantages similar to the advantages obtained by positioning the exhaust pipe inlet proximate the lateral surface of the cylindrical drum are obtained.

According to some embodiments, the at least one exhaust pipe inlet comprises a nozzle extending along said lateral surface in an axial direction of the cylindrical drum, and preferably along substantially an entire axial extension of the lateral surface. This has the effect that the inlet nozzle will be brought in close proximity of the entire outer lateral surface of the cylindrical drum during rotation of the drum, and thus serve to efficiently clean the drum from waste material.

According to some embodiments, at least a part of the movable member that is located below the point of blasting during movement of the movable member is perforated to make it permeable to the blasting media.

This has the effect that used blasting media, which is relatively heavy, especially compared to the waste material, will fall through the movable member into a lower part of the blast cabinet where it may be collected for subsequent reuse or fed straight into a reclaimer arrangement for recycling of the blasting media to the blasting nozzle. The fine-grained and relatively lightweight waste material will not, to the same extent, fall downwards through the perforated movable member. Instead, the waste material will, under the influence of gas flows caused by the flow of blasting media from the blasting nozzle, the movement of the movable member, and the withdrawal of gas by the exhaust pipe inlet, whirl around in the blast cabinet, allowing the exhaust pipe inlet to be arranged at a location where the concentration of waste material is high and the concentration of blasting media is low. The perforated movable member hence provides for efficient reuse of uncontaminated blasting media.

According to some embodiments, the exhaust pipe comprises at least two exhaust pipe inlets located at a distance from each other and configured to withdraw gas from different interior volumes of the blast cabinet, each interior volume containing a relatively high concentration of waste material and a relatively low concentration of blasting media during blasting of the at least one object.

This has the effect that gas containing a relatively high concentration of waste material and a relatively low concentration of blasting media can be withdrawn from two or more locations within the blast cabinet simultaneously. For example, if it is determined, based on computer simulations and/or experience, that there exist a plurality of subvolumes within the blast cabinet that contain high concentrations of waste material in relation to blasting media, the exhaust pipe may be provided with a separate exhaust pipe inlet arranged within each of these subvolumes. This may result in an even more efficient removal of waste material from the blast cabinet.

According to some embodiments, the exhaust pipe is branched into at least two exhaust pipe branches, wherein each branch is provided with a respective exhaust pipe inlet. In this way,

According to some embodiments, the exhaust pipe is arranged to extend along an inside of the outer wall, from the exhaust outlet to a location along the inside of the outer wall from which the exhaust pipe protrudes towards the interior volume in a direction that is substantially perpendicular to the outer wall.

This provides the advantage of discreet and robust blast cabinet design. The exhaust pipe will not interfere with the blasting operation or the function of other internal components of the blast cabinet.

According to some embodiments, the interior volume from which the gas is withdrawn is located in an upper part of the blast cabinet.

This provides the advantage of minimizing the concentration of blasting media in the exhaust gases since the relatively heavier blasting media, compared to the waste material, is more likely to be pulled by gravity to a lower part of the blast cabinet. Furthermore, in particular in embodiments where the point of blasting is located in or close to an upward-moving part of a movable member, the waste material tends to whirl upward in the blast cabinet due to an upward gas flow caused by the upward movement of the movable member. In this scenario, the withdrawal of gas from an upper part of the blast cabinet, in particular from a point of gas withdrawal that is located substantially straight above the point of blasting, or above and somewhat behind the point of blasting from the blasting nozzle’s point of view, ensures that the waste material concentration is relatively high whereas the blasting media concentration is relatively low at the point of gas withdrawal. According to some embodiments, the blast cabinet comprises a blasting media outlet for removal of blasting media from the blast cabinet, the blasting media outlet being located in a lower part of the blast cabinet.

This has the effect that blasting media is gathered at or close to the blasting media outlet under the influence of gravity, thus facilitating collection and/or reuse of blasting media. According to some embodiments, the blasting media outlet may be connected to a reclaimer arrangement for recycling of the blasting media to the blasting nozzle.

According to some embodiments, the exhaust pipe and/or a nozzle of an exhaust pipe inlet is movably arranged in order to make the directed exhaust redirectable towards different interior volumes of the blast cabinet.

In other words, the directed exhaust may be adjustable such that the at least one exhaust pipe inlet of the directed exhaust can be relocated to withdraw gas from different interior subvolumes of the blast cabinet. This provides the advantage of a dynamic directed exhaust that can be optimized for different blasting operations. Typically, for a particular blast cabinet arrangement, the locations of interior volumes having high concentrations of waste material in relation to blasting media do not vary to any significant extent between blasting operations. However, depending on factors such as material, size, structure and shape of the blasted object, the number of blasted objects, the blasting pressure and the type of blasting media used, the shape and movement of any moving movable member accommodating the blasted object(s) during the blasting operation, etc., the distribution of waste material and blasting media may vary slightly between blasting operations. In this case, the redirectable exhaust ensures that the exhaust pipe inlet can be relocated to make sure that gas is withdrawn from an interior volume of the blast cabinet having a high relatively high waste material concentration and a relatively low blasting media concentration.

According to some embodiments, the interior volume from which the gas is withdrawn comprises an interior volume of the blast cabinet that is located above and/or above and behind the point of blasting from the blasting nozzle’s point of view. In some embodiments, the at least one point of gas withdrawal may be located in or close to a vertical plane running through the point of blasting, along the blasting direction, and above a horizontal plane running through the point of blasting.

As mentioned above, the gas volume above the point of blasting is typically a volume with a high concentration of waste material and a low concentration of blasting media due to the relatively high weight of the blasting media and upward whirling of waste material at the point of blasting. In particular, the concentration of waste material in this volume of gas may be high when the movement of a movable member in the blast cabinet generates an upward flow of gas at or close to the point of blasting. The gas volume behind the point of blasting from the blasting nozzle’s point of view is typically also high in waste-material content. This is because waste material is pushed into this volume from the point of blasting by the mix of blasting media and pressurized air that is directed towards the point of blasting from the blasting nozzle. By arranging an exhaust pipe inlet behind and slightly above the point of blasting, high concentrations of waste material will still be drawn into the inlet due to whirling of the waste material under the influence of the blasting media and the pressurised air flow, while no or only low concentrations of blasting media is drawn into the inlet as the blasting media is pulled downwards due to gravity.

According to some embodiments, the blast cabinet is adapted for automated blasting operations.

This provides the advantage of higher production rates and increased productivity, improved safety, and reduced manual workload.

According to some embodiments, the blast cabinet is adapted for blasting of objects manufactured through a polymer powder bed-based 3D printing technique, such as Selective Laser Sintering (SLS), Multi Jet Fusion (MJF) or High Speed Sintering (HSS).

The directed exhaust of the blast cabinet is especially advantageous during blasting of additively manufactured objects and, in particular, during blasting of 3D-printed parts produced with polymer powder bed-based 3D printing techniques, since the waste material produced during blasting of such objects is relatively lightweight compared to the blasting media typically used in the blasting process, which blasting media may be, e.g., glass beads.

More advantageous aspects of the blast cabinet will be described in the detailed description of embodiments following hereinafter.

Brief descriptions of the drawings

The above objects, as well as additional objects, features and advantages of the present disclosure will be more fully appreciated by reference to the following illustrative and non-limiting detailed description of example embodiments of the present disclosure, when taken in conjunction with the accompanying drawings which are given by way of illustration only.

Figs. 1a-1b schematically illustrate a blast cabinet according to an exemplary embodiment of the present disclosure, where some components of the blast cabinet have been left out of the drawings so as not to obscure a directed exhaust of the blast cabinet.

Figs. 2a-2b schematically illustrate the blast cabinet of Figs. 1a-1b including some additional blast cabinet components that are left out of Figs. 1a-1b.

Detailed description

The present disclosure will now be described with reference to the accompanying drawings, in which preferred example embodiments of the disclosure are shown. The disclosure may, however, be embodied in other forms and should not be construed as limited to the embodiments disclosed herein. The disclosed embodiments are provided to fully convey the scope of the disclosure to the skilled person.

Figs. 1a-1b and 2a-2b illustrate a blast cabinet 100 for blasting at least one object by directing a flow of blasting material from a blasting nozzle 101 arranged within the blast cabinet 100 towards a point of blasting 102, according to an exemplary embodiment of the present disclosure. In the illustrated embodiment, the blast cabinet 100 is an automatic blast cabinet comprising a stationary blasting nozzle 101 and a movable member 120 for accommodating and moving at least one product to be blasted in the blast cabinet through the application of a stream of blasting media from the blasting nozzle 101. In order not to obscure a directed exhaust 106 of the blast cabinet 100, the blasting nozzle 101 and the movable member 120 have been left out of Figs. 1a-1b.

The blast cabinet 101 comprises a front wall 100a, a rear wall 100b, a top 100c, a bottom 10Od, and two side walls 100e-1 OOf defining a total interior volume of the blast cabinet 100, which interior volume constitutes what is sometimes referred to as a blasting chamber 130 of the blast cabinet. The front wall 100a is openable to provide the user access to the interior of the blast cabinet 100 and to allow the user to put objects into, and remove objects from, the movable member 120. The front wall 100a may further comprise a window 100a’ enabling the user to visually monitor the blasting process.

With reference now made to Figs. 2a-2b, the blasting nozzle 101 is arranged within the blast cabinet 100 and directed towards the point of blasting 102 where the at least one object to be blasted is located during blasting operations. The blasting nozzle 101 may, for example, be mounted in a stand extending downward into the blasting chamber 130 from the top 100c of the blast cabinet 100. The blasting nozzle 101 is coupled to a source of pressurised air and to a source of blasting media (not shown). In this exemplary embodiment, the bottom 100d of the blast cabinet 100 is funnel-shaped and comprises an outlet 118 for used blasting media. The outlet 118 may, in some embodiments, be connected to a reclaimer arrangement for collecting and recycling used blasting media to the blasting nozzle 101 , as well known in the art.

During blasting operations, waste material is removed from the at least one blasted object by the impact on the object by the blasting media, whereby blasting media and waste material are mixed within the blasting chamber 130. The blasting media is typically a relatively hard particulate material, such as steel shot, glass beads, aluminium oxide, plastic particles, or the like. The blast cabinet 100 of the illustrated embodiment is intended for, but not limited to, blasting of additively manufactured parts produced with polymer powder bed-based 3D printing techniques, such as SLS, MJF or FISS. The blasting media used during such blasting operations may comprise glass beads or any other blasting media suitable for removal of residual material from objects manufactured through a polymer powder bed-based 3D printing technique.

With reference again made to Figs. 1 a-1 b, the blast cabinet 100 comprises a directed exhaust 106 for removal of the waste material from the blasting chamber 130. The directed exhaust 106 comprises an exhaust pipe 108 that extends from an exhaust outlet 110 in an outer wall of the blast cabinet into the blasting chamber 130 and onto an interior volume of the blast cabinet. The interior volume is a subvolume of the total volume of the blast cabinet 100, which subvolume is known to contain a relatively high concentration of waste material and, preferably, a relatively low concentration of blasting media, during blasting operations. The exhaust pipe 108 comprises at least one exhaust pipe inlet 114a, 114b that is configured to withdraw gas from said interior volume for removal of waste material from the blast cabinet 100 via the exhaust outlet 110. The exhaust outlet 110 may in turn be connected to an arrangement (not shown) for post-processing of exhaust gases, as well known in the art. In this exemplary embodiment, the exhaust outlet 110 is arranged in the rear wall 100b of the blast cabinet. However, the exhaust outlet 110 may as well be arranged in any outer wall of the blast cabinet 100.

The at least one inlet 114a, 114b of the exhaust pipe 108 is hence configured to withdraw gas from an interior volume of the blast cabinet 100 that contains a relatively high concentration of waste material and, preferably, a relatively low concentration of blasting media during blasting of the at least one object. In this context, a relatively high concentration of waste material means that the concentration of waste material in said volume is higher than a mean concentration of waste material within the total volume 130 of the blast cabinet 100. Likewise, a relatively low concentration of blasting material means that the concentration of blasting media in said volume is lower than a mean concentration of waste material within the total volume 130 of the blast cabinet 100. An interior volume of the blast cabinet 100 exhibiting a relatively high concentration of waste material will herein be referred to as a volume having a high waste content, an interior volume of the blast cabinet 100 exhibiting a relatively low concentration of blasting media will herein be referred to as a volume having a low media content, and a volume exhibiting a relatively high concentration of waste material and a relatively low concentration of blasting media will herein be referred to as a volume having a high waste-low media content. Using a slightly different wording, the exhaust pipe 108 is hence devised and configured such that at least one inlet 114a, 114b of the exhaust pipe 108 is arranged to withdraw gas from an interior volume of the blast cabinet having a high waste content and, preferably, a low media content.

The interior volume from gas should be withdrawn, and hence the position of the exhaust pipe inlet 114a, 114b, may be determined based on computer simulations, measurements of waste material and/or blasting media contents in the blasting chamber 130, and/or experience. In general, volumes with high waste-low media content are often found at a location above the point of blasting 102 and/or above and behind the point of blasting, at a distance from the point of blasting 102 that is neither too short nor too long.

The optimal length of extension of the exhaust pipe into the blasting chamber 130 depends on multiple parameters, including the size and geometry of the blast cabinet 100, the size, movement and geometry of the movable member 120, the position of the point of blasting 102, the direction and pressure of blasting media, the material, shape and size of the blasted object(s), the number of blasted objects, etc. In a typical blasting application, however, the exhaust pipe 108 of the directed exhaust 106 should extend into the blasting chamber such that the at least one inlet 114a, 114b of the exhaust pipe is located at least 5 cm, preferably at least 10 cm, and most preferably at least 15 cm from any outer wall of the blast cabinet 100, and preferably in the range of 10-40 cm from the point of blasting 102.

As mentioned above, the at least one inlet 114a, 114b should preferably be located above the point of blasting, and/or above and behind the point of blasting. Throughout this disclosure, “above the point of blasting” generally means above a horizontal plane running through the point of blasting 102, whereas “behind the point of blasting” generally means behind a plane running through the point of blasting 102, which plane has a normal that is parallel to the blasting direction, i.e. the direction of blasting media flowing from the blasting nozzle 101 towards the point of blasting 102. It has been found that in most blasting applications, the subvolumes with the highest waste content and low media content are to be found in the part of the blasting chamber 130 that is located above said horizontal plane and behind said plane having a normal that is parallel to the blasting direction. Preferably, the at least one inlet 114a, 114b is located in or close to a vertical plane running through the point of blasting 102, along the blasting direction, and above a horizontal plane running through the point of blasting.

As best illustrated in Fig. 1b, the exhaust pipe 108 may comprise at least two exhaust pipe inlets 114a, 114b located at a distance from each other and configured to withdraw gas from different interior volumes 112a, 112b of the blast cabinet 100. The at least two exhaust pipe inlets 114a, 114b are preferably located in the range of 1-40 cm from each other. Preferably, the at least two inlets 114a, 114b are directed in different directions. Preferably, each of the at least two inlets is directed substantially towards the point of blasting 102, meaning that a normal to the plane of extension of the inlet opening points in the general direction of the point of blasting 102.

In some embodiments, the exhaust pipe 108 may comprise a single unbranched pipe provided with a plurality of exhaust pipe inlets located at different locations along the extension of the pipe. In the illustrated embodiment, however, and as best illustrated in Fig. 1b, the exhaust pipe 108 is branched into at least two exhaust pipe branches 108a, 108b. The exhaust pipe branches 108a, 108b comprise a respective exhaust pipe inlet 114a, 114b for withdrawal of gas from two different interior volumes of the blast cabinet 100. This is advantageous if there are more than one subvolume within the blast cabinet 100 that exhibits a high waste-low media content, and/or in situations where it is found to be beneficial to withdraw gas from the same subvolume from different directions.

As illustrated in the drawings, the at least one exhaust pipe inlet 114a, 114b may be provided with a nozzle 116a, 116b for optimizing a direction of withdrawal of gas, and/or for optimizing a shape and/or a size of the inlet region.

The exhaust pipe 108 may be arranged to extend along an inside of an outer wall of the blast cabinet 100, which in the illustrated embodiment is the rear wall 100b, from the exhaust outlet 110 to a location along the inside of the outer wall from which the exhaust pipe protrudes towards the point of gas withdrawal in a direction that is substantially perpendicular to the outer wall. In some embodiments, the exhaust pipe 108 and/or the nozzle 116a, 116b of one or more exhaust pipe inlets 114a, 114b may be movably arranged in order to make the directed exhaust 106 redirectable towards different interior volumes of the blast cabinet 100, meaning that the at least one exhaust pipe inlet 114a, 114b may be relocated and/or redirected to withdraw gas from different locations within the blasting chamber 130. If, for example, the type of blasting media used in the blast cabinet 100 is changed, this may affect the movement of waste material and/or the movement of blasting media within the blasting chamber 130 during blasting operations. In this case, a redirectable exhaust ensures that gas may still be withdrawn from a subvolume of the blast cabinet 100 exhibiting a high waste-low media content.

In order for the exhaust to be redirectable, the exhaust pipe 108 and/or one or more branches 108a, 108b of the exhaust pipe 108 may be adjustable in length, and/or the nozzle 116a, 116b of the one or more exhaust pipe inlets 116a, 116b may be rotatable and/or redirectable in relation to the exhaust pipe 108 or any exhaust pipe branch on which the nozzle is mounted. In order for the exhaust pipe 108 and/or the one or more exhaust pipe branches 108a, 108b to be adjustable in length, they may be formed by partly overlapping pipes or tubes that are slidably arranged in relation to each other in a telescopic configuration.

With reference again made to Figs. 2a-2b, the movable member 120 is configured to accommodate and move the at least one object to be blasted in a manner making the at lest one object tumble and fall while remaining at substantially the same position, which position coincides with the point of blasting 102. In the illustrated embodiment, the movable member 120 is a rotatable cylindrical drum arranged in a substantially vertical plane within the blast cabinet 100. The drum rotates in a clockwise direction which causes the at least one object to repeatedly tumble and fall into the point of blasting 102, located at a position corresponding to around 7 o’clock along the circumference of the cylindrical drum.

The directed exhaust 106 is configured such that the at least one exhaust pipe inlet 114a, 114b is arranged in close proximity of the movable member 120. Preferably, the at least one exhaust pipe inlet 114a, 114b is arranged at the most 10 cm from a surface of the movable member 120, more preferably at the most 5 cm from the surface of the movable member 120, even more preferably at the most 3 cm from the surface of the movable member 120, and most preferably at the most 1 cm from the movable member. In some embodiments, the nozzle 116a, 116b of the at least one exhaust pipe inlet 114a, 114b may be provided with a brush or another flexible element configured to abut the surface of the movable member to brush or scrape away waste material from the surface of the movable member as it passes by the nozzle. Such a flexible element may further assist in directing waste material removed from the movable member into the inlet, thereby further increasing the amount of waste material withdrawn by the inlet.

The movable member 120 is at least partly made in a material that is permeable to the waste material in order for the waste material to penetrate through the movable member 120, from a first side of the movable member on which the point of blasting 102 is located to a second side of the movable member. The at least one exhaust pipe inlet 114a, 114b is preferably arranged in close proximity of said second side of the movable member 120.

In the illustrated embodiment where the movable member 120 is a substantially vertically arranged rotatable cylindrical drum, at least parts of a lateral surface 115 of the cylindrical drum may be permeable to the waste material in order for the waste material to penetrate from the inside of the cylindrical drum, where the point of blasting 102 is located, to an outside of the cylindrical drum. The directed exhaust 106 may be configured such that an exhaust pipe inlet 114a is arranged in close proximity of, and directed towards, the lateral surface 115 of the drum. The nozzle 116a of the inlet 114a is configured to extend along said lateral surface 115, in an axial direction of the cylindrical drum, and preferably along substantially the entire axial extension of the lateral surface 115. Preferably, the exhaust pipe inlet 114a is arranged in close proximity of the lateral surface of an upper part of the cylindrical drum 115, and most preferably in close proximity of a part of the cylindrical drum that is located substantially above the point of blasting 102.

As best illustrated by Fig. 2a, a rear end of the cylindrical drum may be provided with a back-wall structure 121 for retaining the at least one product to be blasted in the cylindrical drum. At least parts of the back-wall structure 121 may be permeable to the waste material in order for the waste material to penetrate from the inside of the cylindrical drum, where the point of blasting 102 is located, to an outside of the cylindrical drum. The directed exhaust 106 may be configured such that an exhaust pipe inlet 114b is arranged in close proximity of, and directed towards, said back-wall structure 121 of the drum. Preferably, the exhaust pipe inlet 114b is arranged in close proximity of a back-wall structure 121 in an upper part of the rear end of the cylindrical drum, and most preferably in close proximity of a back-wall structure 121 in a part of the rear end that is located substantially above the point of blasting 102.

The movable member 120 may be perforated to make it permeable to both waste material and blasting media. The movable member may, for example, be provided with a mesh structure where the mesh size is selected such that blasting media can pass through the openings of the mesh structure whereas the objects to be blasted cannot.

In the illustrated embodiment, the perforated components of the cylindrical drum may, for example, be made of plastics and manufactured through an additive manufacturing process.

In order for the blasting material to fall down through the perforations of the movable member 120 towards the bottom of the blast cabinet 100, at least a part of the movable member 1230 that is located below the point of blasting 102 during movement of the movable member should be perforated. In the illustrated example with the cylindrical drum, the entire lateral surface 115 of the drum is perforated, as well as parts of the back-wall structure 121. During the blasting process, used blasting media will fall through the cylindrical drum and further out through the outlet 118. The outlet 118 may, in some embodiments, be connected to a reclaimer arrangement for recycling of the used blasting media to the blasting nozzle.

Although described herein with reference to an automatic blast cabinet 100 comprising a stationary blasting nozzle 101 and a movable member 120 for accommodating and moving the at least one product to be blasted, it should be appreciated that the directed exhaust 106 and the principles of the directed exhaust disclosed herein may be beneficially used also in manual blast cabinets. Likewise, it should be appreciated that although the illustrated embodiment comprises a movable member 120 in form of a cylindrical drum, the directed exhaust 106 may be beneficially used also in conjunction with other types of movable members. For example, in other embodiments (not shown), the movable member may be a substantially C-shaped conveyer belt running around a plurality of rotary bearings in a counter-clockwise direction, such that the at least one product to be blasted is tumbled and turned at a point of blasting located in the inner lower part of the C. The lower open end of the C-shaped arrangement may be extended in a substantially horizontal direction to form a substantially horizontal conveyer-belt platform for on-loading and/or off-loading (when the movement of the conveyer belt is reversed) of products to be brought to or from the point of blasting. Of course, such a C-shaped conveyer belt arrangement may also be horizontally flipped (mirror inverted) and operated in a reversed direction. In this case, in accordance with the above-described embodiment where the movable member is a cylindrical drum, the conveyer belt may be perforated such that the blasting media falls down towards the bottom of the blast cabinet through the conveyer belt, and the at least one exhaust pipe inlet of the directed exhaust may be arranged in close proximity of the conveyer belt, preferably in an upper part of the C-shaped conveyer-belt structure. The advantages of such an arrangement is similar to the advantages described above with reference to the embodiment in which the movable member 120 is a cylindrical drum.

Based on the above, it is envisaged that the blast cabinet 100 of the present disclosure may be modified and adjusted to any extent falling within the scope of the claims following hereinafter.

Claims

1. A blast cabinet (100) for blasting at least one object by directing a flow of blasting media from a blasting nozzle (101) arranged within the blast cabinet (100) towards a point of blasting (102) of the at least one object, whereby the blasting media and waste material removed from the at least one object are mixed within the blast cabinet (100), characterized in that the blast cabinet (100) comprises a directed exhaust (106) comprising an exhaust pipe (108) extending from an exhaust outlet (110) in an outer wall of the blast cabinet (100) to an interior volume (112a, 112b) of the blast cabinet (100) containing a relatively high concentration of waste material and a relatively low concentration of blasting media during blasting of the at least one object, the exhaust pipe (108) comprising at least one exhaust pipe inlet (114a, 114b) configured to withdraw gas from the interior volume (112a, 112b) for removal of waste material from the blast cabinet (100) via the exhaust outlet (110).

2. The blast cabinet (100) according to claim 1, comprising a movable member (120) configured to accommodate and move the at least one object during blasting operations, wherein the at least one exhaust pipe inlet (114a, 114b) is arranged in close proximity of the movable member (120).

3. The blast cabinet (100) according to claim 1 or 2, wherein the movable member (120) is at least partly permeable to the waste material in order for the waste material to penetrate the movable member from a first side of the movable member on which the point of blasting (102) is located, to a second side of the movable member, wherein the at least one exhaust pipe inlet (114a, 114b) is arranged in close proximity of the second side of the movable member (120).

4. The blast cabinet (100) according to claim 3, wherein the movable member (120) is a rotatable cylindrical drum arranged in a substantially vertical plane within the blast cabinet (100) and configured to accommodate the at least one object within the drum, wherein at least parts of a lateral surface (115) of the cylindrical drum is permeable to the waste material, the at least one exhaust pipe inlet (114a, 114b) being arranged in close proximity of, and directed towards, said lateral surface (115) of the drum.

5. The blast cabinet (100) according to claim 4, wherein the at least one exhaust pipe inlet (114a, 114a) comprises a nozzle (116a) extending along said lateral surface (115) in an axial direction of the cylindrical drum, and preferably along substantially the entire axial extension of the lateral surface (115).

6. The blast cabinet (100) according to claim 3, wherein the movable member (120) is a rotatable cylindrical drum arranged in a substantially vertical plane within the blast cabinet (100) and configured to accommodate the at least one object within the drum, wherein a rear end of the cylindrical drum comprises a back-wall structure (121) for retaining the at least one product in the cylindrical drum, at least parts of the back-wall structure being permeable to the waste material, the at least one exhaust pipe inlet (114a, 114b) being arranged in close proximity of, and directed towards, said back-wall structure (121).

7. The blast cabinet (100) according to any of the claims 2 to 6, wherein at least a part of the movable member (120) that is located below the point of blasting (102) during movement of the movable member (120) is perforated to make it permeable to the blasting media.

8. The blast cabinet (100) according to any of the preceding claims, wherein the exhaust pipe (108) comprises at least two exhaust pipe inlets (114a, 114b) located at a distance from each other and configured to withdraw gas from different interior volumes (112a, 112b) of the blast cabinet (100), each interior volume containing a relatively high concentration of waste material and a relatively low concentration of blasting media during blasting of the at least one object.

9. The blast cabinet (100) according to claim 8, wherein the exhaust pipe(108) is branched into at least two exhaust pipe branches (108a, 108b), each comprising a respective exhaust pipe inlet (114a, 114b).

10. The blast cabinet (100) according to any of the previous claims, wherein the exhaust pipe (108) is arranged to extend along an inside of the outer wall, from the exhaust outlet (110) to a location along the inside of the outer wall from which the exhaust pipe (108) protrudes towards the interior volume (112a, 112b) in a direction that is substantially perpendicular to the outer wall.

11 . The blast cabinet (100) according to any of the preceding claims, wherein the interior volume (112a, 112b) from which the gas is withdrawn is located in an upper part of the blast cabinet (100).

12. The blast cabinet (100) according to any of the preceding claims, further comprising a blasting media outlet (118) for removal of blasting media from the blast cabinet (100), the blasting media outlet (118) being located in a lower part of the blast cabinet (100).

13. The blast cabinet (100) according to any of the preceding claims, wherein the exhaust pipe (108) and/or a nozzle (116a, 116b) of an exhaust pipe inlet (114a, 114b) is movably arranged in order to make the directed exhaust (106) redirectable towards different interior volumes of the blast cabinet (100).

14. The blast cabinet (100) according to any of the preceding claims, wherein the interior volume (112a, 112b) from which the gas is withdrawn is an interior volume of the blast cabinet (100) that is located above the point of blasting (102), and/or above and behind the point of blasting (102) from the blasting nozzle’s point of view.

15. The blast cabinet (100) according to any of the preceding claims, wherein the blast cabinet (100) is adapted for automated blasting operations.

16. The blast cabinet (100) according to any of the preceding claims, wherein the blast cabinet (100) is adapted for blasting of objects manufactured through a polymer powder bed-based 3D printing technique.