Abstract:
A device for the extraction of processing products includes a double-walled extraction hood, which has a first inner housing part and a second outer housing part arranged at a distance from the first inner housing part. The two housing parts are arranged coaxial with each other and partially within each other in such a way that an air channel is formed between the two housing parts. The air channel has a front end that can be aligned with the workpiece and a rear end opposite the front end. A flow directed from the front end to the rear end can be created in the air channel. The extraction hood, in particular the inner housing part of the extraction hood, is designed to accommodate at least part of the processing device and can be connected thereto.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is the U.S. National Stage of International Application No. PCT/EP2012/052965, filed Feb. 22, 2012, which designated the United States and has been published as International Publication No. WO 2012/119852 and which claims the priority of German Patent Application, Serial No. 10 2011 013 111.6, filed Mar. 4, 2011, pursuant to 35 U.S.C. 119(a)-(d). 
     BACKGROUND OF THE INVENTION 
     The present invention relates to a device for the extraction of processing products arising during the processing of a workpiece by means of a processing device. In particular, it concerns the discharging of processing products which are conveyed in an air- or respectively gaseous flow through a defined flow channel. 
     From DE4225014C2 an extraction device for welding or cutting installations is known, in which an extraction hood is fastened to the burner or to a burner holder. The extraction hood is connected via extraction tubes to a vacuum generator, in order to extract the flue gases occurring during welding or cutting. 
     SUMMARY OF THE INVENTION 
     The invention is based on the problem of being able to reliably discharge processing products arising during the processing of a workpiece also in contour processing operations in the 3-dimensional range. In particular, by the invention the processing products are to be received directly at their point of origin into a suitable flow and can be discharged parallel to the process. The degrees of freedom and the freedom of movement of the directing motion automaton are to be compromised to an extremely small extent, in particular in media-supplied tools. 
     To solve this problem, an extraction device includes a double-walled extraction hood which has a first inner housing part and a second outer housing part arranged at a distance from the first inner housing part, wherein the two housing parts are arranged coaxial with each other and partially within each other in such a way that an air channel is formed between the two housing parts, wherein the air channel has a front end that can be aligned with the workpiece and a rear end opposite the front end, wherein a flow directed from the front end to the rear end can be created in the air channel, and wherein the extraction hood, in particular the inner housing part of the extraction hood, is designed to accommodate at least part of the processing device and can be connected thereto. Advantageous embodiments and further developments are to be found in the dependent claims. 
     Through the fact that a double-walled extraction hood is provided, which has a first inner housing part and a second outer housing part arranged at a distance from the first inner housing part, wherein the two housing parts are arranged coaxial with each other and partially within each other in such a way that an air channel is formed between the two housing parts, wherein the air channel has a front end that can be aligned with the workpiece and a rear end opposite the front end, wherein a flow directed from the front end to the rear end can be created in the air channel, and wherein the extraction hood, in particular the inner housing part of the extraction hood, is designed to accommodate at least part of the processing device and can be connected thereto, a targeted air flow can be generated at the point of origin of the processing products. The air, which is accelerated by a pressure difference, is guided within an air channel surrounding the tool. The air channel is designed in an optimized manner with regard to flow and is thereby optimally suited for the transportation of particles in the flow. By avoiding obstacles to the flow or resistances, disadvantageous turbulences or stalls are prevented. 
     Furthermore, the double-walled embodiment of the extraction hood offers the advantage that almost no processing products impact as accelerated particles onto the tool which is projecting into the flow. This applies in particular when the inner housing part of the extraction hood forms a protective, thin-walled casing which is at least partially placed over the processing device. The fastening of this protective casing, which assumes at the same time the function of the first inner housing part and hence the inner wall of the flow-directing channel, can be integrated into the connection clamping to the motion automaton of the entire processing device. The inner housing part is provided at its end facing the workpiece with an opening or respectively an aperture. This enables the connection from the tool drive to the actual tool holder, which in turn ensures the torque transmission of the drive to the tool itself. A small clearance of this aperture to the tool holder permits a defined exit for sealing air of the pressurization of the drive into the free flow region of the extraction hood and therefore prevents in operation, also without a mechanically closed containment, an entry of particles into the drive housing. 
     The second outer housing part of the extraction device, i.e. the outer casing of the flow channel, can preferably be likewise produced from a stable flat material. Depending on the case of application, the size of the tool drive, the type of tool or quantity and size of the processing products which are to be discharged, the second outer housing part is arranged at a defined distance from the inner housing part. This means that between the inner and outer wall of the current-directing air channel, a defined distance is formed. By the selection of this distance measurement, the flow cross-section and the volume flow connected therewith and the speed of flow can be varied in a targeted manner. Likewise, the size of the processing products which are able to be conveyed is set by the delimitation of the cross-section. 
     Advantageously, between the front end of the inner housing part and the front end of the outer housing part a space can be provided to accommodate a front end section of the processing device. Furthermore, advantageously the inner housing part can have a region with an internal diameter which is slightly greater than the external diameter of the inner processing device in this region, so that the inner housing part is constructed in this region for the preferably accurately fitting accommodating of at least part of the processing device, in particular for accommodating and fastening the drive unit. Particularly advantageously, the outer housing part can have a conically tapering front end piece, which is preferably adapted to the contour of the processing device in this region. The tool holder and the tool can be arranged in this region. As a result, the outer housing part therefore extends the flow-directing enclosing of the extraction device up to the area of application of the processing tool, so that the occurring processing products can be received in a targeted manner into a guided defined flow immediately after they occur in the free flow. The structural form of the outer housing part is adapted to the necessary flow cross-sections. It preferably has a smooth surface and a slim geometry. Thereby, the extraction device according to the invention is optimally suited for use on motion automatons. 
     This novel structural form, which is adapted and to the greatest possible extent integrated to the conditions such as drive unit and tool type, offers the smallest possible interfering contours and therefore enables a maximum utilization of the degrees of freedom and movement possibilities of the motion automaton which is used, in particular in complex three-dimensional contour processing operations. The flow guidance for the transportation of processing products is therefore an integrated component of the processing unit. 
     At the upper end of the flow channel, the flow enveloping the tool is brought together centrally again and is guided via a flow deflection chamber to a connecting piece. A standardised continuing flow line can be connected to this connecting piece, which continuing flow line is able to be connected in turn for example to a suitable vacuum generator. 
     In a preferred embodiment, at the lower end of the flow channel a brush attachment or respectively a brush ring is provided as sealing element to the processing product part, which brush attachment or respectively brush ring can be detachably mounted onto the outer wall of the flow channel. This brush serves for the flexible encasing of the immediate processing region. Particles which are accelerated by the processing process are prevented by the bristles, encircling in a ring shape, from leaving the range of influence of the directed air flow and hence of the particle transport flow. Furthermore, this bristle closure enables a mechanical, but flexible sealing contact to the workpiece which is to be processed. Hereby, the flow action is brought into optimum proximity to the point of origin of processing products which are to be conveyed away; a flow saturation already before reaching this position by inflowing foreign media can therefore be as far as possible prevented. In a special variant embodiment, the fibres of the brush can consist of materials which prevent an electrostatic charging of the workpiece which is to be processed in this region or of the bristles themselves. The base body which is used for fixing the bristles can be produced from an elastic material, which makes it possible—depending on the variant embodiment—to embrace the corresponding diameter of the lower end of the flow channel. 
     According to a further aspect of the present invention, the outer housing part is constructed so as to be detachable from the extraction hood as a whole or in one or more segments, wherein the detachable parts of the outer housing part are movable from a position forming a closed state of the extraction hood into a position forming an opened state of the extraction hood and vice versa. With this possibility, the complete tool holder device of the drive unit can be exposed and an automatic tool change can be carried out by magazine equipment. Furthermore, this offers the possibility, with not necessary conveying away of processing products, to also reach contour regions of the workpiece which is to be processed, which in the closed state of the extraction hood can not be processed or can only be processed with increased effort. 
     To move the detachable parts, drive means can be provided by which the detachable parts of the outer housing part are movable back and forth parallel to the longitudinal axis of the extraction hood. In a first alternative embodiment, the detachable parts can also be constructed so as to be movable away from the longitudinal axis of the extraction hood. In a further alternative embodiment, the detachable parts can be constructed so as to be pivotable respectively about an axis lying parallel or orthogonal to the longitudinal axis of the extraction hood. 
     Through this technology with the detachable parts, variants of the outer housing part can be constructed, in particular for the formation of various flow channels with different geometries, brush types or bristle lengths. The detachable parts and, if applicable, matching brush attachments, can be removed fully automatically from a magazine according to the case of application, and assembled to the outer housing part with the desired geometry. The detachable parts of the one variant merely have to be exchanged for detachable parts in another variant. The correct positioning of the detachable parts is monitored by a corresponding sensor system. 
     In addition to all conventional machining processing operations in CNC machines, machining tasks in robotically guided processes are also to be mentioned as fields of application of this invention. Particularly with the use of industrial robots as flexible guiding motion automatons, in complex contour processing operations the machine-typical movement possibilities are not to be compromised with the use of extraction devices for the elimination of machining waste. This is achieved with the present invention. Furthermore, this invention makes possible, especially in the machining processing of fibre-reinforced plastics, the controlled conveying away from the processing area of dusts which are a health- or explosion hazard. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The invention is to be described in further detail below with the aid of example embodiments and with reference to  FIGS. 1 to 7   b . There are shown: 
         FIG. 1  side view of extraction device and processing device in dismantled state; 
         FIG. 2  side view of extraction device and processing device in assembled state; 
         FIG. 3 a    side view according to  FIG. 2  with extraction hood in closed state; 
         FIG. 3 b    side view according to  FIG. 2  with extraction hood in opened state; 
         FIG. 4 a    side view according to  FIG. 2  with extraction hood in closed state and with linear drive means; 
         FIG. 4 b    side view according to  FIG. 2  with extraction hood in opened state and with linear drive means; 
         FIG. 5 a    side view according to  FIG. 2  with intake tubes and in closed state of the extraction hood; 
         FIG. 5 b    side view according to  FIG. 2  with intake tubes and in opened state of the extraction hood; 
         FIG. 6 a    side view according to  FIG. 2  and with a first embodiment of an extraction hood with separable outer housing part in closed state; 
         FIG. 6 b    side view according to  FIG. 2  and with a first embodiment of an extraction hood with separable outer housing part in opened state; 
         FIG. 7 a    side view according to  FIG. 2  and with a second embodiment of an extraction hood with separable outer housing part in closed state; 
         FIG. 7 b    side view according to  FIG. 2  and with a second embodiment of an extraction hood with separable outer housing part in opened state. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG. 1  shows a diagrammatic side view of a device for the processing of a workpiece with a workpiece processing device  1 , which has a drive unit  1   a , a tool holder device  1   b  and a tool  1   c . For example, the workpiece processing device can be a milling device with a milling spindle  1   a  and a milling tool  1   c . The extraction device  2  according to the invention, also referred to in the description as extraction hood, comprises a first, inner housing part  2   a  and a second, outer housing part  2   b . The two housing parts  2   a  and  2   b  have respectively a cone-shaped front end piece  2   a ′ or respectively  2   b ′ and cylinder pieces  2   a ″ and  2   b ″ lying therebehind. A brush attachment  2   c  is provided at the lower end, facing the workpiece in operation. Opposite this end, a flow deflection chamber  2   d  is provided, having a connecting piece  3  to which a flexible tube can be connected which is able to be connected to a suitable vacuum generator. Furthermore, a clamping ring  4  and a mount  5  can be seen in  FIG. 1 . By means of the clamping ring  4 , the extraction device  2  can be fastened to the drive unit  1   a  of the workpiece processing device. The mount  5  serves for fastening the unit of workpiece processing device  1  and extraction device  2  to a handling automaton, for example to an arm of an industrial robot. 
       FIG. 2  shows the arrangement of  FIG. 1  in the assembled state and with the assumption that a vacuum generator is connected to the connecting piece  3 . In order to be able to identify the individual components better, some of these components are provided with component-specific hatching. The drive unit  1   a  is accommodated in the inner housing part  2   a  and is fastened to the drive unit  1   a  inner housing part  2   a  by means of the clamping ring  4 . The inner housing part  2   a  extends over the entire front section of the drive unit  1   a . The length of the inner housing part  2   a  and the length and the contour of the end piece  2   a ′ are dimensioned such that the tool holder device  1   b  projects at least partly out from the inner housing part  2   a . The outer housing part  2   b  is fastened to the underside of the flow deflection chamber  2   d , for example by means of a suitable flange  13 , and the flow deflection chamber  2   d  can be connected, in turn, with the clamping ring  4 . Between the front end of the inner housing part  2   a  and the front end of the outer housing part  2   b  a space  6  is formed for accommodating a front end section of the processing device  1 . Here in this space  6  the tool holder device  1   b  and the tool  1   c  are accommodated. In this way, an air channel  7  is formed between the outer side of the inner housing part  2   a  and the inner side of the outer housing part  2   b . The air channel  7  has a front end  7   a  that can be aligned with the workpiece, and a rear end  7   b  opposite this end. The above-mentioned space  6  therefore forms a segment of the air channel  7 . In this air channel  7  a flow is able to be generated, directed from the front end  7   a  to the rear end  7   b , which flow is to be illustrated by the arrows  8 . The flow  8  is deflected in the flow deflection chamber  2   d  in the direction of the connecting piece  3  and is guided into a flexible tube, not illustrated here, which is connected to a vacuum generator, which is likewise not illustrated here. Depending on the configuration of the front end of the extraction hood  2 , the front end  7   a  of the air channel  7  can lie at the front end of the outer housing part  2   b  or at the front end of the brush attachment  2   c . It is merely necessary that at the front end of the extraction hood  2   a  vacuum is generated and therefore a flow  8  at the front end of the extraction hood  2  entering into the latter, which flow can receive the processing products arising at the processing site. These processing products are then entrained by the flow  8 , guided around the tool  1   c  and the tool holder device  1   b  and subsequently guided into the annular clearance between the two housing parts  2   a  and  2   b . The inner housing part  2   a  therefore prevents an impacting or a penetrating of processing products onto or respectively into the remaining components of the processing device  1 . 
     According to a further aspect of the invention, the outer housing part  2   b  is constructed so as to be detachable as a whole or in one or more segments from the extraction hood  2 , wherein the detachable parts of the outer housing part  2   b  can be brought or respectively are movable from a position forming a closed state of the extraction hood  2  into a position forming an opened state of the extraction hood  2 , and vice versa.  FIG. 3 a    shows the arrangement of  FIG. 1  in assembled state and in the closed state of the extraction hood  2 .  FIG. 3 b    shows a state in which the outer housing part  2   b  has been detached as a whole from the extraction hood  2 , in which the extraction hood  2  is therefore in an opened state. It can be seen from  FIG. 3 b    that in an opened state of the extraction hood  2 , the space  6  and the components  1   b  and  1   c  of the processing device  1  which are situated there are freely accessible. The outer housing part  2   b  can be detached by hand or mechanically from the extraction hood  2  and removed.  FIGS. 4 a  and 4 b    show the use of a linear drive  9 , by which for example a rod  10  connected with the outer housing part  2   b  can be moved parallel to the longitudinal axis of the extraction device  2 .  FIG. 4 a    shows the outer housing part  2   b  in a position which forms the closed state of the extraction hood  2  and  FIG. 4 b    in a position which forms the opened state of the extraction hood  2 . As a modification of the example which is shown here, the outer housing part  2   b  can also be constructed from several parts. For example, the front end piece  2   b ′ and the cylinder piece  2   b ″ lying therebehind can be constructed so as to be detachable from one another. In this case, it can be sufficient if only the front end piece  2   b ′ is removed from the extraction hood  2 , in order to expose the space  6  and the components of the processing device  1  which are situated there. 
     In addition, the front end piece  2   b ′ of the outer housing part  2   b  does not necessarily have to be constructed as a closed housing. Also, as is illustrated in  FIGS. 5 a  and 5 b   , individual intake tubes  11  can be joined together to an end piece  2   b ′ and connected with the cylinder piece  2   b ″ lying therebehind, wherein the openings of the intake tubes  11  must be positioned so that the air channel  7 , described above, is formed. The housing part  2   b  can either be removed as a whole from the extraction hood  2  (not illustrated here), or only the front end piece  2   b ′ with the intake tubes  11  is detached from the extraction hood  2 , as is shown here. For this, drive means  9 ,  10 , adapted in a suitable manner, can be used, as is described in connection with  FIGS. 4 a    and  4   b.    
     According to a further configuration, the detachable parts of the outer housing part  2   b  can be pivotable respectively about an axis lying parallel or orthogonal to the longitudinal axis of the extraction hood  2 . These embodiments are illustrated in  FIGS. 6 a   / 6   b  and  7   a / 7   b . Both the outer housing part  2   b  and also the brush attachment  2   c  are embodied in two parts, so that two half shells  12   a  and  12   b  are formed. According to the example embodiment of  FIGS. 6 a  and 6 b   , the two half shells  12   a  and  12   b  are mounted articulatedly on axes A and B, which lie orthogonally to the longitudinal axis of the extraction device  2 . By a pivoting movement about the axes A and B, the two half shells  12   a  and  12   b  can be moved out from the position shown in  FIG. 6 a    into the position shown in  FIG. 6 b   , and back. According to the example embodiment of  FIGS. 7 a  and 7 b   , the two half shells  12   a  and  12   b  are mounted articulately on an axis C, which lies parallel to the longitudinal axis of the extraction hood. In the figures, this axis C lies precisely behind the longitudinal axis of the extraction hood  2 . By a pivoting movement about the axis C, the half shells  12   a  and  12   b  can be moved out from the position shown in  FIG. 7 a    into the position shown in  FIG. 7 b   , and back. By the previously described pivoting movements, the detachable parts  12   a  and  12   b  of the outer housing part  2   b  (here with  2   c ) can be brought from a position forming a closed state of the extraction hood  2  ( FIG. 6 a    or respectively  FIG. 7 a   ) into a position forming an opened state of the extraction hood  2  ( FIG. 6 b    or respectively  7   b ) and vice versa. 
     LIST OF REFERENCE NUMBERS 
     
         
           1  processing device 
           1   a  drive unit 
           1   b  tool holder device 
           1   c  tool 
           2  extraction device 
           2   a  inner housing part 
           2   a ′ conical end piece 
           2   b  outer housing part 
           2   b ′ conical end piece 
           2   b ″ cylinder piece 
           2   c  brush attachment 
           2   c ′,  2   c ″ parts with divided brush attachment  2   c    
           2   d  flow deflection chamber 
           3  connecting piece 
           4  clamping ring 
           5  mount 
           6  space for accommodating a front end section of the processing device  1   
           7  air channel 
           7   a  front end of the air channel 
           7   b  rear end of the air channel 
           8  flow 
           9  linear drive 
           10  rod 
           11  intake tubes 
           12   a  first half shell 
           12   b  second half shell 
           13  fastening flange 
         A, B, C pivot axes