EDGE-FINISHING APPARATUS

Abstract: The present invention relates to an edge-finishing apparatus, in particular a portable and/or hand-held edge-finishing apparatus (41). The edge-finishing apparatus comprises: a first and a second bearing surface (10, 20) for bearing on the one and, respectively, the other of the surfaces (44, 45) coincident at one edge (50) to be finished, wherein the first and second bearing surfaces (19, 20) enclose an angle (x) in which the edge to be finished can be accommodated; a drivable rotary shaft for rotary driving of a finishing element that is fixed or can be fixed thereto and operates by means of its circumferential surface. The first and second bearing surfaces (19, 30) are each in the shape of a sector of a cone. The axis of rotation of each of the bearing surfaces in the shape or a sector of a cone is coincident with the axis of rotation of the rotary shaft (15). Viewed in the axial direction of the rotary shaft, the active portion of the circumferential surface of the finishing element (21) is located between the first and second bearing surfaces.

Description: Edge-finishing apparatus The present invention relates to an edge-finishing apparatus, in particular a portable and/or hand-held edge-finishing apparatus, comprising: - a first and second bearing surface for bearing on the one and, respectively, the other of the surfaces coincident at one edge to be finished, wherein the first and second bearing surface enclose an angle in which the edge to be finished can be accommodated; a drivable rotary shaft for rotary driving of a finishing element that is fixed or can be fixed thereto and operates by means of its circumferential surface. US-A 2 856 975 discloses an edge- finishing apparatus of this type which is intended in particular for use when rounding the edges of workpieces. The apparatus according to US 2 856 975 consists of a cutting element that is mounted, with its circumferential surface having a cutting action, on the drive shaft of an electric motor. In order to be able to control the depth and angle of cut of the cutting element, said known edge-finishing apparatus is provided with a so-called edge guide and a flat so-called top surface guide, which guides, during operation, engage on the workpiece and specifically do so on the surfaces thereof which are coincident at the edge to be finished. The edge guide and flat top surface guide mutually enclose an angle of approximately 90°, within which part of the active portion of the cutting element protruding through the edge guide is located. A significant disadvantage of this known edge-finishing apparatus is that it requires flat contact of the bearing surface of the edge guide and of the flat bearing surface of the top surface guide for accurate control of the cutting depth and finishing angle of the cutting element. If there is no question of such a flat contact, the cutting depth of the cutting element will deviate in an uncontrollable manner or at least in a manner which is very difficult to control, and in particular will be less than in the case of flat contact. Such flat contact can be aimed for and ensured with some effort but, when achieved, appreciably restricts the freedom of movement and the ease of operation of the person using the edge- finishing apparatus. The aim of the present invention is to provide an improved edge-finishing apparatus, in particular an edge-finishing apparatus which is easy to operate and with which a specific desired depth of finish can be reliably ensured. Said aim is achieved according to the invention in that the first and second bearing surface are each in the shape of a sector of a cone, in that the axis of rotation of each of 2 the bearing surfaces in the shape of a sector of a cone is coincident with the axis of rotation of the rotary shaft, and in that, viewed in the axial direction of the rotary shaft, the active portion of the circumferential surface of the finishing element is located between the first and second bearing surface. During use, that is to say while finishing an edge, an edge- finishing apparatus of this type can be rotated about the axis of rotation of the rotary shaft, whilst, as a consequence of the bearing surfaces shaped as a sector of a cone, reliable contact with the surfaces coincident at the edge to be worked is guaranteed while maintaining the desired depth of finish or cutting depth. Finishing of an edge of a workpiece with a high degree of uniformity can be achieved in this way with substantial freedom of movement and an appreciably improved ease of use. This makes the edge- finishing apparatus according to the invention in particular also suitable for finishing workpieces which have been fitted, such as, for example, rounding the edges of wooden door and window frames, windows and doors, which, for example, have to be provided with a new paint system. When maintaining wood, metalwork, plastic structures and the like, in particular when applying or re-applying a paint system, film system or coating, it is extremely important for longer life of the paint system, film system or coating that the (right-angled, sharp) edges of the substrate/the workpiece have been adequately rounded. In the case of a paint system or coating the reason for this is to be able to obtain an adequate coating thickness at these locations and to improve adhesion, and in the case of a film system the reason for this is to improve the adhesion at these locations and to prevent tearing of the film. By this means the paint system, the film system or the coating is prevented from deteriorating more rapidly at the edges than on the adjoining surfaces. A further advantage is that rounded edges are less susceptible to mechanical damage inflicted from the outside. In order to improve the ease of use while maintaining adequate accuracy of finish, it is advantageous according to the invention if the angle enclosed between the bearing surfaces is up to at most approximately 10°, preferably up to at most approximately 5° greater than the angle which is enclosed by the surfaces coincident at the edge to be finished. In this way the edge-finishing apparatus acquires some degree of freedom of movement, which increases the ease of use for the operator. A further advantage is that somewhat oversizing the angle enclosed between the bearing surfaces in this way facilitates passage over irregularities in the trajectory of movement of the bearing surfaces while maintaining a sufficiently accurate finish. Taking account of more or less standard sizes for 3 the angle which is enclosed by the surfaces coincident at the edge to be finished, it is particularly advantageous according to the invention if the angle enclosed between the bearing surfaces is in the range of 30 - 35° or 45 - 50° or 60 - 65° or 90 - 95° or 120 - 125°. In this context it is very readily conceivable that one edge-finishing apparatus is provided with interchangeable or adjustable bearing surfaces in order to be able to adjust the angle between the latter to the angle enclosed by the surfaces coincident at the edge to be finished. Preferably, an interchangeable set of bearing surfaces with a fixed bearing surface angle of between 90 and 95° and an interchangeable set of bearing surfaces with a fixed bearing surface angle of between 90 and 105°, in particular 95 - 105°, will have been provided. So as also to be able to use the edge-finishing apparatus according to the invention easily at locations which are difficult to reach, it is advantageous according to the invention if the first bearing surface extends a greater distance from the axis of rotation than does the second bearing surface, the greater distance preferably being in the range from approximately 1 mm to approximately 5 mm. With this arrangement the second bearing surface is thus, with respect to the axis of rotation, as it were shortened relative to the first bearing surface. In this way the edge-finishing apparatus according to the invention is also usable if the surface on which the second bearing surface bears is relatively narrow with respect to the edge to be finished, it then being possible to ensure reliable support of the edge-finishing apparatus on the workpiece by means of the first bearing surface, which is still relatively broad. According to an advantageous embodiment of the edge- finishing apparatus, the cross- sectional shape, viewed in the axial direction of the rotary shaft, of the active portion of the finishing element will have been adapted to the desired cross-sectional shape of the edge to be finished. In this way any profiling can, in principle, be applied to the edge to be finished. Especially with regard to painting work, it is advantageous according to the invention if the cross-sectional shape of the active portion of the finishing element comprises a cutout in the shape of an arc of a circle, the radius of said cut-out preferably being in the range from approximately 1.5 mm to approximately 5 mm, and more preferentially being approximately 3 mm. According to a further advantageous embodiment, the edge- finishing apparatus according to the invention comprises a right-angle transmission, in particular a right-angle 4 gear transmission, via which the rotary shaft is or can be coupled to a drive motor, such as an electric motor. With an edge-finishing apparatus of this type, the housing in which the drive motor is housed can then be used as a handle and/or a fixing for handles, so that when the edge-finishing apparatus is in use a starting force exerted thereon can easily be achieved in the direction of the edge to be finished, approximately parallel to the bisecting plane of the surfaces of the workpiece which are coincident at the edge to be finished, which is highly beneficial for the ease of use and accurate edge- finishing. In this context it is advantageous in particular if the axis of rotation of the drive motor intersects the active portion of the circumferential surface of the finishing element. Preferably, the axis of rotation of the drive motor will extend essentially in or parallel to the bisecting plane of the first and second bearing surface. The invention also relates in particular to an edge- finishing apparatus according to the invention that has been designed as a so-called right-angle adaptor or right-angle attachment for mounting on the front end of a drill and driving by the drive shaft thereof. Such right- angle adaptors or right-angle attachments are supplied as accessories with a wide variety of drills in order to be able to drill at an angle. To this end the so-called chuck of the drill is then removed from the front end thereof in order to fit the right-angle adaptor or right- angle attachment. The chuck can then, if necessary, be re- fitted on the right-angle adaptor or right-angle attachment if the latter is not itself already provided with a chuck. A right- angle adaptor or right-angle attachment of this type, which is known per se, can easily be converted to an edge- finishing apparatus according to the invention by providing it with a finishing element on its output shaft and providing it with a support piece having a bearing surface according to the invention on either side of said finishing element, in the axial direction thereof. According to a further aspect, the invention relates to an edge-finishing apparatus, preferably an edge-finishing apparatus according to the first aspect of the invention, comprising: a first and second bearing surface for bearing on the one and, respectively, the other of the surfaces coincident at one edge to be finished, wherein the first and second bearing surface enclose an angle; a drivable rotary shaft for rotary driving of a finishing element that is fixed or can be fixed thereto, at least one handle for holding and manipulating the edge-finishing apparatus by one or both hands. By providing the at least one handle in the so-called bisecting plane of the first and second bearing surface it can be ensured that the starting force exerted by the user when handling the apparatus is directed towards the edge to be finished and extends in the bisecting plane, which promotes accurate finishing of the edge to be finished. Preferably, the rotary shaft and/or the active finishing surface of the finishing element will intersect said bisecting plane essentially perpendicularly. The present invention will be explained in more detail below with reference to illustrative embodiments shown in the drawing. In the drawing: Figure 1 shows a perspective view of an edge- finishing apparatus according to the invention, which view illustrates in particular the use thereof; Figure 2 shows a diagrammatic plan view of an edge-finishing apparatus according to the invention which has been slightly modified compared with Figure 1, which view in particular further illustrates the use of the edge-finishing apparatus according to the invention; Figure 3 shows a cross-sectional view of an example of an edge-finishing apparatus according to the invention; and Figure 4 shows a diagrammatic detailed view according to the arrow IV in Figure 3 of one of the bearing surfaces. Figure 3 shows a longitudinal section of a finishing apparatus according to the invention in the form of an accessory that can be used on the front end of a drill in order to be driven by the drive shaft. The edge-finishing apparatus 41 consists of a housing 1 having a generally cylindrical receiving opening 2 in which the front end of, for example, the drill can be accommodated and in which a coupling element 3 is accommodated, rotatably mounted in a bearing, which coupling element 3 is able to accommodate the output end of the drive shaft of, for example, the drill and can be coupled thereto via, for example, the threaded hole 4. The coupling element 3, which is mounted in the housing 1 such that it is rotatable in a bearing by means of a bearing sleeve 5 fitted in the receiving opening 2 by means of a retaining ring 6, is provided on that end thereof which faces away from the entrance of the receiving opening 2 with a bevel gear 7. The axis of rotation of the coupling element 3 and bevel gear 7 is coincident with the axis of rotation of the drive shaft of the driving installation, such as a hand drill. The bevel gear 7 together with a further bevel gear 8 arranged at right angles thereto forms a right-angle transmission. The 6 bevel gear 8 is fixed on a shaft 9, which is mounted in bearings such that it is rotatable in the housing 1, via a bearing bush 10 and a bearing bush 11 which is fixed on the shaft 9 by a retaining ring 12. A large gear 13 is also mounted on the shaft 9, which gear 13 engages with a small gear 14. The small gear 14 is mounted on an output shaft 15, the so- called rotary shaft 15. Said output shaft 15 is mounted in bearings such that it is rotatable in the housing 1, via a bearing bush 17, fixed by means of a retaining ring 16 on the output shaft 15, and a bearing bush 52, fixed with respect to the housing 1 by means of a support piece 18. The accessory described up to now with reference to Figure 3 can be presumed to be known per se and essentially can be replaced by any other so-called right-angle adaptor or right-angle attachment known per se from the prior art for, in particular, drills. In accordance with the invention, the accessory/auxiliary described up to now with reference to Figure 3 is provided with a finishing element 21, mounted on the output end of the output shaft 15, and, viewed in the axial direction from the output shaft 15, support pieces, arranged alongside, having bearing surfaces 19 and 20 in the form of a sector of a cone. The finishing element 21 is mounted on the output shaft 15 in order to be able, by means of/via the circumferential surface thereof, to act on a workpiece. The finishing element 21 can be constructed in a wide variety of ways. It is conceivable to construct said finishing element as a grindstone/sanding stone with profiling suited to the desired finish for the edge to be finished. The finishing element 21 can, however, also have been constructed as a file, a bit element or a blade element. The finishing element 21 shown in Figure 3 consists of a cylindrical part 22, by means of which it can be fixed on the output shaft 15, and two blades or bits 23 arranged diametrically opposite one another and protruding radially from the cylindrical part. It will be clear that it is also possible for more blades/bits 23 to have been mounted on the cylindrical part 22, in which context the aim will preferably be for equidistant mounting of blades/bits 23. Viewed in the axial direction of the output shaft 15, a support piece is mounted on either side of the finishing element 21, support piece 18 and support piece 24, respectively, which support pieces are each provided with a bearing surface which is in the form of a sector of a cone and extends over approximately 180°, i.e. bearing surface 19 and bearing surface 20, respectively. The axis of rotation of said bearing surfaces 19 and 20, which are in the form of a sector of a cone, is coincident with the axis of rotation of the output shaft 7 15 and of the finishing element 21. Although this is not necessary per se for the invention, the output shaft 15 is rotatably mounted in a bearing by means of a bearing bush 25 in support piece 24. Furthermore, it must be pointed out that the bearing surfaces 19 and 20 can also extend in the form of a sector of a cone over less than 180°, for example over 90°, 120° or 45°. In general, it can be stated that the bearing surfaces in the form of a sector of a cone extend over a range from greater than 0° to approximately 180°, in general over a range from 30° to 180°. In the view according to Figure 4, the nature of the bearing surface 19 in the form of a sector of a cone is illustrated in more detail. To this end Figure 4 shows a detailed view according to arrow IV in Figure 3 of support piece 18 (with finishing element 21 and support piece 24 omitted), the output shaft 15 being shown in cross-section. As can also be seen from Figure 3, the blades 23 are provided with cut-outs which are in the form of an arc of a circle and have a radius R of approximately 3 mm. The angle α enclosed between the bearing surfaces 19 and 20 is preferably somewhat greater than the angle which is enclosed by the surfaces of the workpiece which are coincident at the edge to be finished. In the embodiment according to Figure 3, the angle α is approximately 95°. With this arrangement, the configuration shown in Figure 3 is intended in particular for finishing the edge of two surfaces coincident at approximately 90°. Said oversizing of the angle α by approximately 5° promotes the ease with which the finishing apparatus according to the invention can be operated by the user without this resulting in an essential deterioration, at least visually discernible, in the accuracy of finish. In order also to be able to reach locations which are not readily accessible, it is advantageous according to the invention if one of the bearing surfaces, in particular bearing surface 20, which is located at the free end of the output shaft 15, is shortened relative to the other bearing surface 19 over a distance d with respect to the axis of rotation of the output shaft 15. The distance d can be, for example, 5 mm, 10 mm or also 2 mm. The accessibility of locations which are not readily accessible can also be improved or further improved by constructing support piece 24 in pointed form, for example by tapering it on its outside as well, as is indicated by 80. Figure 1 shows, highly diagrammatically, an edge-finishing apparatus 41 according to, for example, Figure 3 mounted on the front part of a hand drill 40, from which the chuck has been removed. As will be clear from Figure 1, with this arrangement the edge- finishing apparatus 41 is mounted on the drill 40 and fixed thereon by means of a screw 8 60 in such a way that the plane in which the motor housing 43 and the pistol grip 42 extend is approximately perpendicular to the bisecting plane of the bearing surfaces 19 and 20 which are able to bear on the edge 50, which is to be finished, in particular rounded, at the location where two surfaces 44 and 45 of the workpiece to be machined are coincident. It will be clear that, as a consequence of the bearing surfaces 19 and 20 which are in the form of a sector of a cone, the edge- finishing apparatus 41 according to the invention can easily be moved in the direction of the arrow 51 over the edge 50 to be finished, without the precise location of the imaginary axis of rotation 46 of the motor of the drill 40 with respect to the edge 50 to be finished having any substantial influence on the accuracy of finish, as long as said imaginary axis of rotation 46 is located in, parallel to or virtually in/parallel to the bisecting plane of the surfaces 44 and 45. The use of the edge- finishing apparatus according to the invention in accordance with a further advantageous embodiment thereof is explained in more detail in Figure 2. With this embodiment the assembly of the finishing apparatus 41 on the drill 40 is so designed that the plane spanned by the motor housing 43 and the pistol grip 42 extends essentially in the bisecting plane of the bearing surfaces 19 and 20. By this means the edge- finishing apparatus according to the invention can be moved relatively easily by a person, standing roughly at point 48, over an edge 50 to be finished, by said person making a sort of swaying movement in accordance with arrow 47 with his or her hands/arms. It will be clear that wherever painting or paintwork is mentioned in this application this must certainly also be understood as painting or paintwork and coating or coatings. It will also be clear that the invention is certainly not restricted to merely an attachment which has been mounted on, for example, a drill, but also relates to an edge- finishing apparatus in which drive, handles, housing, bearing surfaces and finishing element have been integrated into a whole, with the bearing surfaces and/or the finishing element optionally being supplied as interchangeable parts. As far as the attachment is concerned, it is also pointed out that the latter can also have been intended for a milling machine instead of for or solely for a drill.

Claims: 9 Claims 1. Edge- finishing apparatus, in particular a portable and/or hand-held edge- finishing apparatus, comprising: - a first and a second bearing surface for bearing on the one and, respectively, the other of the surfaces coincident at one edge to be finished, wherein the first and second bearing surface enclose an angle in which the edge to be finished can be accommodated; a drivable rotary shaft for rotary driving of a finishing element that is fixed or can be fixed thereto and operates by means of its circumferential surface, characterised in that the first and second bearing surface are each in the shape of a sector of a cone, in that the axis of rotation of each of the bearing surfaces in the shape of a sector of a cone is coincident with the axis of rotation of the rotary shaft, and in that, viewed in the axial direction of the rotary shaft, the active portion of the circumferential surface of the finishing element is located between the first and second bearing surface. 2. Edge- finishing apparatus according to Claim 1, characterised in that the angle enclosed between the bearing surfaces is greater, for example up to approximately 5° greater, than the angle which is enclosed by the surfaces coincident at the edge to be finished. 3. Edge- finishing apparatus according to one of the preceding claims, characterised in that the angle enclosed between the bearing surfaces is in the range of 30 - 35° or 45 - 50° or 60 - 65° or 90 - 95° or 120 - 125°. 4. Edge-finishing apparatus according to one of the preceding claims, characterised in that the first bearing surface extends a greater distance from the axis of rotation than does the second bearing surface, the greater distance preferably being in the range from approximately 1 mm to approximately 5 mm. 5. Edge-finishing apparatus according to one of the preceding claims, characterised in that the cross-sectional shape, viewed in the axial direction of the rotary shaft, of the active portion of the finishing element is adapted to the desired cross-sectional shape of the edge to be finished. 6. Edge-finishing apparatus according to Claim 5, characterised in that the cross- sectional shape of the active portion of the finishing element comprises a cut-out in the shape of an arc of a circle, the radius of said cut-out preferably being in the range from 10 approximately 1.5 mm to approximately 5 mm, and more preferentially being approximately 3 mm. 7. Edge-finishing apparatus according to one of the preceding claims, characterised in that said edge-finishing apparatus comprises a right-angle transmission, in particular a right-angle gear transmission, via which the rotary shaft is or can be coupled to a drive motor, such as an electric motor. 8. Edge-finishing apparatus according to Claim 7, characterised in that the axis of rotation of the drive motor intersects the active portion of the circumferential surface of the finishing element. 9. Edge- finishing apparatus according to Claim 7 or 8, characterised in that the axis of rotation of the drive motor extends essentially in or parallel to the bisecting plane of the first and second bearing surface. 10. Edge- finishing apparatus according to one of Claims 7 - 9, designed as a right- angle adaptor or right-angle attachment for mounting on the front end of a drill and driving by the drive shaft thereof. 11. Edge- finishing apparatus, preferably according to one of the preceding claims, comprising: a first and second bearing surface for bearing on the one and, respectively, the other of the surfaces coincident at one edge to be finished, wherein the first and second bearing surface enclose an angle; a drivable rotary shaft for rotary driving of a finishing element that is fixed or can be fixed thereto, at least one handle for holding and manipulating the edge-finishing apparatus by one or both hands, characterised in that the at least one handle extends essentially in the bisecting plane of the first and second bearing surface. 12. Edge- finishing apparatus according to Claim 11, characterised in that the rotary shaft and/or the active finishing surface of the finishing element intersect said bisecting plane essentially perpendicularly. 13. Edge-finishing apparatus according to one of the preceding claims, characterised in that the support piece supporting the bearing surface located at the free end of the rotary shaft is of pointed construction or chamfered on the outside.

Inventors: BARTELS MAURICE ANNA MARIA, BARTELS, MAURICE, ANNA, MARIA
Applicants: BARTELS MAURICE ANNA MARIA, BARTELS, MAURICE, ANNA, MARIA
Application year: 1999
Main classification: B23C3
IPC codes: B23C3