BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a plan view of a grinding blade,
FIG. 2 shows a plan view of a fan-type grinding wheel according to the invention,
FIG. 3 shows a cross section through the fan-type grinding wheel according to FIG. 2,
FIG. 4 shows a grinding belt from which grinding blades are to be cut in succession,
FIG. 5 shows a modified embodiment of a grinding blade,
FIG. 6 shows a further modified embodiment of a grinding blade,
FIG. 7 shows a further modified embodiment of a grinding blade,
FIG. 8 shows a grinding blade similar to the illustration in FIG. 1 with rounded corners,
FIG. 9 shows a grinding blade similar to the illustration in FIG. 5 with rounded corners,
FIG. 10 shows a grinding blade similar to the illustration in FIG. 6 with rounded corners, and
FIG. 11 shows a grinding blade similar to the illustration in FIG. 7 with rounded corners.
DESCRIPTION OF THE PREFFERED EMBODIMENTS
The grinding blade 1 shown in FIG. 1 has a triangular configuration. Its three edges are called outer edge 2, inner edge 3 and rear edge 4, depending on their subsequent position on a support plate of a fan-type grinding wheel. The edges 2 to 4 are configured as arcuate portions with a corresponding radius of curvature R2, R3 and R4. With respect to the grinding blade 1, the outer edge 2 and the rear edge 4 have a convex configuration while the inner edge 3 has a concave configuration. Geometric shapes of this type are also triangles as, according to the rules of spherical geometry, the boundary lines of a triangle do not have to be rectilinear, but can also be curved. It is crucial that two respective lateral edges intersect at a point of intersection, in other words form a corner.
Referring to FIGS. 2 and 3, a fan-type grinding wheel comprises a support plate 5 with a hub 6 comprising a central circular opening 7. The support plate 5 has an outer annular rim region 8 for receiving the grinding blades 1. This rim region 8 is connected to the hub 6 via an annular web 10 which projects in the direction of the centre line 9 of the support plate 5. The rim region 8 is inclined radially outwardly from the annular web 10, as shown in FIG. 3. As a result, the working face 11 of the grinding blades 1 which are to be arranged on the support plate 5 in turn extends substantially radially and perpendicularly to the centre line 9. This geometry is due to the fact that more and more grinding blades 1 overlap or cover one another from the interior outwards, as shown in FIG. 2. The grinding blades 1 are fastened on the rim region 8 of the support plate 5 using an adhesive layer 12.
Referring in particular to FIG. 2, the grinding blades 1 are arranged at equal angular intervals on the support plate 5, more specifically rotationally symmetrically in each case in the same position relative to the support plate 5. In the embodiment shown in FIGS. 2 and 3, the outer radius R13 of the grinding blade package 13 fastened on the support plate 5 corresponds to the radius of curvature R2 of the outer edge 2, so that the outer rim 14 projecting outwardly beyond the rim region 8, of the grinding blade package 13 is circular.
A grinding blade 1 is shown in broken lines in FIG. 2, although its respective grinding region 15 extends only from its rear edge 4 to the next rear edge 4 arranged in a leading manner in the direction of rotation 16 of the grinding wheel.
Referring again to FIG. 2, the tangent 17 to the rear edge 4 at the point of intersection 18 with the outer edge 2 and the radius R13 through the point of intersection 18 form an angle α>0, the tangent 17 leading relative to the radius R13 in the direction of rotation 16.5°≦α≦35° applies to this angle α.
In this embodiment, R2≅R4 and R3>R2 and R3>R4. Since the inner edge 3—with respect to the grinding blade 1—extends concavely, the number of overlaps of adjacent grinding blades 1 is much smaller in the region of the inner rim 19 of the grinding blade package 13 than in the outer region and increases significantly only towards the exterior, as shown by the hatched area in FIG. 2.
Referring again to FIG. 2, the outer edge 2 of each grinding blade 1 extends over an angle β of the circular grinding blade package 13, wherein 25°≦β≦90° applies. 10≦n≦80 applies to the number n of grinding blades 1.
FIG. 4 shows how the grinding blades 1 are cut from a grinding belt 20. The width a of the grinding belt 20 is selected in such a way that the intersection point 21 of the outer edge 2 and the inner edge 3 lies on a longitudinal rim 22 of the grinding belt 20 whereas the intersection point 23 between the inner edge 3 and the outer edge 4 lies on the other longitudinal rim 24 parallel to the longitudinal rim 22. The intersection point 18 between the outer edge 2 and the rear edge 4 abuts the inner edge 3 of the grinding blade 1 which is to be cut out adjacently. This method of cutting the grinding blades 1 results in scrap cut portions 25, 26. This scrap is not detrimental as the arrangement—trailing from the exterior inwardly with respect to the direction of rotation 16—of the rear edge 4 on the support plate 5 leads to optimum, i.e. minimum wear of the grinding blades 1 from the beginning of grinding with a new fan-type grinding wheel. The concave configuration of the inner edge 3 also reduces scrap.
FIGS. 5 to 7 show variations of the grinding blades. The grinding blade 1′ shown in FIG. 5 has the aforementioned outer edge 2 and rear edge 4. However, the inner edge 3′ has a rectilinear configuration. Its radius of curvature R3′ is therefore infinitely long.
Referring to FIG. 6, the grinding blade 1″ shown therein has an arcuate outer edge 2, as already described, and a rectilinear inner edge 3′, also as already described. The rear edge 4′ also has a rectilinear configuration, the foregoing statement concerning the angle α also applying to the rear edge 4′ on the support plate 5. The radius of curvature R4′ therefore has an infinite length.
Finally, FIG. 7 also shows the configuration of a grinding blade 1′″, with which not only the inner edge 3′ and the rear edge 4′ but also the outer edge 2′ have a rectilinear configuration. The radius of curvature R2′ therefore also has an infinite length.
The embodiments according to FIGS. 8 to 11 correspond in their basic construction to the embodiments according to FIGS. 1, 5, 6 and 7, rounded corners being provided instead of the sharp-edged points of intersection 18, 21, 23 respectively. Each of these grinding blades therefore have the basic shape of a triangle. The outer edges, inner edges and rear edges forming main edges are therefore connected to one another by convexly curved secondary edges, the radius of curvature r of which is much smaller in each case than the radius of curvature R of the aforementioned main edges. The outer edges, inner edges and rear edges forming the main edges are designated with the same reference numerals in FIGS. 8 to 11 as the corresponding edges in FIGS. 1, 5, 6 and 7, with the addition of a distinguishing “a” in each case. The same applies to the radii of curvature R.
The secondary edges are provided with the same reference numerals as the intersection points 18, 21, 23, also with the addition of a distinguishing “a”. The same applies to the designation of the radii of curvature r of the secondary edges.
The following applies, in particular:
With the grinding blade 1a according to FIG. 8, all three main edges, namely the outer edge 2a, the inner edge 3a and the rear edge 4a have a curved configuration, more specifically, the outer edge 2a and the rear edge 4a are convexly curved whereas the inner edge 3a is concavely curved. The radii of curvature are R2a, R4a and R3a. The main edges are each connected to one another by three secondary edges R18a, R21a and R23a which are convexly curved and have radii of curvature r18a, r21a and r23a.
The grinding blade 1′a according to FIG. 9 differs from that according to FIG. 8 in that the inner edge 3′a has a rectilinear configuration and the radius of curvature R3′a of this inner edge 3′a consequently has an infinite length.
The grinding blade 1″a according to FIG. 10 in turn differs from that according to FIG. 9 in that the rear edge 4′a also has a rectilinear configuration and its radius of curvature R4a consequently has an infinite length.
With the grinding blade 1′″ according to FIG. 11, finally all three main edges have a rectilinear configuration, in other words also the outer edge 2′a, of which the radius of curvature R2′a consequently has an infinite length.
The radii of curvature R of the main edges are much greater than the radii of curvature r of the secondary edges. 3≦R/r and preferably 10≦R/r apply. If the main edges do not have a rectilinear construction, 3≦R/r≦20 and preferably 10≦R/r≦20 applies to the ratio of the radii of curvature R of the main edges to the radii of curvature r of the secondary edges.
Patent Application
20070275643
