Patent Publication Number: US-2013237135-A1

Title: Disc sander for deburring and/or rounding of metal work pieces

Description:
RELATED APPLICATION 
     This patent claims the benefit of German Patent Application DE 20 2012 002 267.9, which was filed on Mar. 7, 2012, and which is hereby incorporated by reference in its entirety. 
     FIELD OF THE DISCLOSURE 
     The present disclosure relates to a disc sander of a device for deburring and/or rounding of metal work pieces in a through-feed process. 
     BACKGROUND 
     A through-feed sanding machine for deburring or rounding of the edges of a metal work piece is known from German Patent DE 10 2008 052 564 A1, which mentions punched parts or laser-cut parts being worked. This through-feed sanding machine features a conveyor belt for continuously conveying the work piece and at least one continuous belt sanding unit. This belt sanding unit is disposed transversely to the conveying direction and extends across the entire width of the conveyor belt. In order to secure the work piece against shifting laterally, pressing rolls holding the work piece are provided ahead of and after the continuous sanding belt. 
     A disadvantage of this is that the transversely disposed belt sanding unit does not optimally machine the edges of the work piece, which are oriented transversely to the feed direction. 
     A device for neatening plate-shaped, coated work pieces having at least one disc sander is known from European Patent EP 1 258 315 A2, which mentions the disc sander moving over the work piece transversely to its conveying direction. The disc sander simultaneously rotates around its vertical axis so that a 360° machining of all the edges of the work piece are achieved irrespective of the outline of the work piece. Here also, the work pieces must be held by the pressing rolls attached ahead of and after the disc sander, in order to prevent them from shifting. However this also means that work pieces smaller than the distance between the two pressing rolls cannot be machined or that work pieces so thin that they are not captured by the pressing rolls cannot be machined. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1   a  shows a schematic view of a device for deburring and rounding in a plan view at a first point in time. 
         FIG. 1   b  shows the device according to  FIG. 1   a  at a second point in time. 
         FIG. 1   c  shows the device according to  FIG. 1   a  at a third point in time. 
         FIG. 2  shows an alternate device for deburring and rounding. 
         FIG. 3   a  shows the device according to  FIG. 1   a  in a front view with an apposed pressing roll. 
         FIG. 3   b  shows the device according to  FIG. 3   a  with a lifted pressing roll. 
         FIG. 4  shows a first embodiment of a disc sander according to the present disclosure for a device according to  FIG. 1   a , along line IV in  FIG. 3   a.    
         FIG. 5  shows a second embodiment of a disc sander according to the present disclosure. 
         FIG. 6  shows a third embodiment of a disc sander according to the present disclosure. 
         FIG. 7  shows a fourth embodiment of a disc sander according to the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Disclosed herein is a disc sander of a device for deburring and/or rounding of metal work pieces in a through-feed process. 
     One object of the present disclosure is to develop a device with which small and thin work pieces can also be machined efficiently. According to the present disclosure, a disc sander such as described and claimed herein is proposed as a technical solution to this object. Advantageous embodiments of this disc sander can be taken from the sub-claims. 
     A disc sander configured according to this technical teaching is advantageous in that due to the sanding means being held in a resilient manner, a certain force is applied to the work piece, which presses the work piece onto its support, thus preventing a shifting. An interaction between the sanding force that is required for sanding and acts on the work piece and the restoring force acting through the spring system onto the work piece thus occurs. 
     When a big burr is machined by the disc sander, the sanding means is pressed in by it in a particularly strong manner. This occurs against the spring force, so that in this case, a particularly strong spring return force, which in turn presses the work piece against the support and fixes it there, acts on the sanding means. Since, most of the time, strong transverse forces also occur with particularly big burrs, they can be well compensated for via the sanding means held in a resilient manner, with the result that the work piece is held on its support without shifting. If a comparatively smaller burr is to be debarred, the transverse forces will be less, so that in this case less spring return forces are sufficient in order to hold the work piece. 
     In a first embodiment, the spring element is formed by a dimensionally stable, elastic layer made of a synthetic or natural material and extends along the entire underside of the disc sander, the spring element resting planarly against the underside of the disc sander. It has thereby proven advantageous to use a dimensionally stable and yet elastic foam rubber, sponge rubber or EPDM rubber or another type of synthetic material. 
     This is advantageous in that a corresponding spring element is configured on the entire underside of the disc sander, so that a corresponding pressing force always acts on the work piece when the work piece is being machined by the sanding means. 
     As a result it is made possible to also deburr or round smaller or flatter work pieces that would otherwise not be held by the pressing rolls of the flat-bed machine. 
     In some examples, a circulating chamfer is configured at the lower edge of the disc sander so that the work piece is first captured by the disc sander in the area of the chamfer. This is advantageous in that the forces coming from the spring-loaded sanding means progressively act on the work piece, so that the work piece is uniformly captured and pressed against the support. 
     In another preferred embodiment, a rigid intermediate plate is provided between the spring element and the sanding means. This rigid intermediate plate prevents the resiliently carried sanding means from being pressed in at certain points, the consequence being that all the protruding burrs of the work piece that are to be removed, are reliably removed. Another advantage is that the forces impinged onto the spring element are distributed across a large area and correspondingly exert a restoring force across a large area of the intermediate plate and thus of the sanding means, so that a particularly great sanding force acts on the burr, while only negligible forces act onto the remaining surfaces of the work piece. As a result, a much more thorough and much quicker deburring is thus achieved without machining the remaining surface of the work piece. 
     In some examples, a circulating chamfer is configured at the lower edge of the intermediate plate, in order to allow for the work piece to be uniformly captured by the disc sander and pressed onto the support. 
     In some examples, the spring element is configured as a disc sander, a rigid intermediate plate, on the underside of which the sanding means can be mounted, being attached to the disc sander. In this embodiment, the spring force is exerted by the disc springs. As a result, the advantages described above are also achieved here. 
     In another example, the disc sander is held by at least one axially acting helix coiled spring. The sanding means is hereby directly attached to the underside of the disc sander, the result being that the sanding means is held by the helix coiled spring in a resilient manner. The entire disc sander can thereby be shifted in a resilient manner orthogonally relative to the work piece. The previously mentioned advantages also apply to this embodiment. 
     Each of the three embodiments of the disc sander according to the present disclosure shown here, whether they are achieved by means of a helix coiled spring, a disc spring or a dimensionally stable, elastic layer made of a synthetic or natural material, has the advantage that a particularly great sanding force is exerted onto the burr of the work piece or on the edge of the work piece to be rounded, because the burr at first shifts the resiliently held sanding means in opposition to the spring force, so that the spring force supports the sanding process. More specifically when a rigid intermediate plate is provided thereby or when the sanding means is attached directly to the disc sander as in the third embodiment, this furthermore has the advantage that the sanding means primarily rests on the burr or on the point of the work piece to be machined but not on the other surfaces. Thus a rapid deburring or machining can hereby be achieved without sanding the remaining work piece. It has also turned out that much lower temperatures hereby occur, so that wear of the sanding means is reduced. 
     Other advantages of the disc sander according to the examples disclosed herein are shown in the enclosed drawings and in the embodiments described herein. According to the present disclosure, the previously mentioned and further explicated features can also be used individually or in any mutual combination. The mentioned embodiments must not be understood as an exhaustive enumeration but as examples. 
     In  FIGS. 1 ,  2  and  3  a device for deburring and/or rounding metal work pieces, more specifically punched or laser-cut parts is schematically shown, in which the work pieces are machined in a continuous method. This device comprises a continuously running conveyor belt  10  and a mounting bridge  12  to which four disc sanders  14  are attached. The disc sanders  14  rotate around their vertical axis and feature a planar sanding means, e.g. a sandpaper on their planar underside. 
     The disc sanders  14  can be moved, as suspended to the mounting bridge  12 , transversely to the conveying direction across the entire width of the conveyor belt  10 . Both outer disc sanders  14  thereby end up beyond the conveyor belt  10 . 
     Such a device for deburring and/or rounding of metal work pieces, more specifically of punched and laser-cut parts, in a through-feed process, comprises a conveyor belt  10  for continuously conveying the work pieces  16  and at least one, and in some examples four, disc sanders  14  rotating around their respective vertical axes, sanding means being attached on its underside facing the work piece  16 , the at least one disc sander being oscillatably held transversely to the motion direction of the conveyor belt and the disc sander  16  being held so that it is movable up to the right and/or the left of the conveyor belt. This example has the advantage that a uniform wear of the sanding means occurs because the sanding means of each disc sander is used for approximately the same amount of time. 
     Thereby, it has proven advantageous to design the disc sander  14  and the conveyor belt  10  in such a manner that the distance travelled by the disc sander  14  corresponds to at least 2.5 times the diameter of the disc sander  14 . Thereby, it is ensured that the sanding means is worn uniformly, which results in an efficient operation of the device. 
     Respectively one pressing roll  18  is provided ahead of and after the disc sanders  14 , in the conveying direction of the work piece  16 . The pressing roll  18  presses the work piece  16  onto the conveyor belt so that the transverse forces appearing during deburring or rounding cannot displace the work piece  16 . In order to be able to machine work pieces with different thicknesses and in order to exert an appropriate contact pressure onto the respective work piece  16 , it has proven advantageous to configure the pressing roll  18  so that its height is adjustable independently from the disc sanders. 
     Thereby, it is particularly advantageous if the height of the pressure rolls  18  is adjustable independently from the at least one disc sander  14 . The sanding pressure of the disc sander  14  as well as the contact pressure of the pressing rolls  18  can thus be adjusted according to the requirements of the work piece. 
     In order to simplify the installation of this device and/or in order to individually adjust the sanding pressure of the disc sander  14  and the contact pressure of the pressing rolls  18  it has proven advantageous if the heights of all the pressing rolls  18  are adjustable together but independently from the at least one disc sander  14 . The height of the pressing rolls  18  can hereby be adjusted according to the thickness of the work piece and at the same time the adjustment can be implemented in a single operation. The height of the disc sanders and thus their sanding pressure on the work piece can be independently adjusted in an appropriate manner. 
     In some examples, the disc sanders are attached to the mounting bridge by means of a helix coiled spring, so that the disc sander is movable in the direction of its vertical axis by up to 4 mm, preferably by up to 2 mm. On the one hand, the disc sander can hereby be adjusted to the thickness of the respective work piece, and on the other hand the sanding pressure onto the work piece can also be adjusted in the desired manner. 
     The device shown in  FIG. 2  differs from the devices shown in  FIGS. 1 and 3  in that two disc sanders  14  are shown here. 
       FIG. 4  shows a first embodiment of the disc sander  14  according to the present disclosure, on the underside  20  of which a sanding means  22  is held in a resilient manner. This sanding means  22  extends across the entire surface of the underside  20  and is held there by means of a hook-and-loop connection  24  (e.g., a Velcro connection). This hook-and-loop connection  24  is slightly flexible and resilient, so that the sanding means  22  is held on the disc sander  14  in a resilient manner. 
     A circulating chamfer  26  is configured on the edge of the underside  20  of the disc sander  14 , this chamfer  26  taking up an angle of 22.5° relative to the vertical axis of the disc sander. In other embodiments, this angle can also amount to between 10° and 45°. 
     The work piece  16  can be uniformly captured with this chamfer  26  and uniformly pressed onto the underlying conveyor belt, so that a shifting of the work piece during machining is prevented. 
       FIG. 5  shows another embodiment of the disc sander according to the present disclosure. In this example, a spring element  128  is applied across a great area onto the underside  120  of the disc sander  114 , and the spring element is made of foam rubber, sponge rubber, EPDM or another soft synthetic material. A hook-and-loop connection  124 , on which the sanding means  122  is held across a great surface, is then also provided on the underside of the spring element  128 . Here too, a circulating chamfer  126  is configured on the lower edge of the underside  120  of the disc sander  114 , as was the case in a prior example embodiment. 
     Another alternative embodiment shown in  FIG. 6 , which differs from the embodiment shown in  FIG. 5  in that a rigid intermediate plate  130 , which also has a circulating chamfer  132  at its outer edge, is disposed between the spring element  128  and the sanding means  122 . This chamfer  132  on the intermediate plate  130  corresponds to the chamfer  126  of the disc sander  114 . 
     In the embodiment described in  FIG. 7 , a spring element  228 , to which a rigid intermediate plate  230  is attached, formed by six disc springs  234 , is disposed on the underside  220  of the disc sander  214 . Like in the previous embodiment a sanding means  222  is also held on this intermediate plate  230  by means of a hook-and-loop connection  224 . A chamfer  232  is also formed on the outer edge of the intermediate plate  230 , in order to be able to easily and uniformly capture the work piece. 
     The sanding means described here, is a planar sandpaper, which is held to a great surface of the underside of the disc sander. 
     Although certain example methods, apparatus and articles of manufacture have been disclosed herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus and articles of manufacture fairly falling within the scope of the claims of this patent.