BE1022845B1 - GRINDING TOOL - Google Patents

Abstract

The invention relates to the field of abrasive machining, and in particular to a grinding tool (1) comprising a rod (2) with a tip (2a) intended to be received by a tool-holder spindle for driving the machine. 'tool (1) rotating about a longitudinal axis (X) of the rod (2), and at least one sheet (3) fixed to said rod (2). The sheet (3) has at least one abrasive outer face (6) between a proximal edge (8), a distal edge (7) and two side edges (9). In addition, it has, between said outer abrasive face (6) and an opposite face (5), at least one slot (12) extending from one of said proximal (8) or distal (7) edges. The invention also relates to a method for shelving edges (21) comprising an abrasive machining step with such a grinding tool (1).

Description

GRINDING TOOL Background of the Invention

The present invention relates to the field of machining tools, and more particularly to a grinding tool, as well as to an edge shelving method comprising an abrasive machining step with such a grinding tool.

In this context, grinding is understood to mean any method of machining by abrasion, and in particular by contact with an abrasive surface in motion. In order to ensure the finishing of mechanical parts, it is often desirable to round their sharp edges, both to facilitate their handling without risk of cutting, as to allow their assembly with other parts. Among the tools used with this object are in particular abrasive staple-blade brushes, such as those sold by the company 3M® under the brand ScotchBrite® FF-ZS. Nevertheless, these brushes have certain drawbacks, especially at the time of ensuring the finishing of edges of difficult access, as may be those of some internal festoons turbine wheels.

Object and summary of the invention

The present invention aims to remedy these disadvantages. In particular, the invention aims at providing a grinding tool comprising a rod with a bit intended to be received by a tool-holder spindle for driving the tool in rotation about a longitudinal axis of the rod, and less a sheet attached to said rod and having at least one abrasive outer face, and which allows the finishing of difficult access edges. Said abrasive outer face may in particular be delimited by a proximal edge and a distal edge, offset with respect to each other along at least the direction of said longitudinal axis of the rod, and two lateral edges offset with respect to the other following at least one direction orthogonal to said longitudinal axis of the rod. In the present context, the term "proximal" means the direction towards the tip of the rod in the longitudinal axis thereof, and the opposite direction by "distal".

In at least one embodiment of the present invention, the purpose of facilitating the finishing of edges of difficult access can be achieved by virtue of the fact that said sheet has, between said abrasive outer face and an opposite face, at least one slot from one of said proximal or distal edges. With this arrangement, a working area is delimited by the slot, the proximal or distal edge of the slot, and the lateral edge closest to the slot, this work area being able to tilt around a bending line said sheet extending from an inner end of the slot to the side edge of the nearest sheet. The tilting of the working zone around this bending line thus makes it possible to use this tool for finishing difficult access edges.

The sheet may especially be a sheet of sandpaper with a waterproof paper paper backing, having a basis weight between A and C, and an average abrasive grain size between 150 and 600 μm. These abrasive grains may be, for example, silicon carbide grains, with closed powdering, bonded to the paper support by a resin binder. However, other types of grain and support could alternatively be used depending on the circumstances, such as for example paper carriers of different weights, canvas supports, abrasive grains of different sizes or materials, or related to the paper support by another type of binder.

Said slot may have a width of not less than 1 mm and / or not greater than 2 mm, a distance from the nearest lateral edge of the sheet of not less than 10 mm and / or not greater than 15 mm, and or a depth, from the proximal or distal starting edge, not less than 12 mm and / or not greater than 22 mm. In the present context, the term "depth" of the slit means the minimum distance on the abrasive outer surface of the sheet between the proximal or distal edge of the slit and an opposite end of the slit within the sheet. . The grinding tool may be substantially symmetrical with respect to a plane aligned with said longitudinal axis of the rod and perpendicular to the proximal and distal edges of the sheet. In this way it can present at least one such slot and a corresponding working area on each side of said plane of symmetry, increasing the frequency of passage of the abrasive surface on the machined material, while ensuring the balance of the tool of grinding to allow its use at high rotational speeds.

In order to allow bidirectional use of the tool, even with a sheet having only one abrasive surface, said sheet may be folded by one of its proximal or distal edges.

In particular, with said sheet folded by its distal edge, said distal edge of the sheet may be retained between a support integral with said rod and substantially perpendicular to its longitudinal axis, and a removable retention piece.

Alternatively, however, said rod may have, on a distal end, a clamp retaining said sheet.

The present invention also relates to a method of edge shelving comprising an abrasive machining step with the aforementioned grinding tool. The method may further include a prior step of chamfering the ridges prior to said abrasive machining step. Thanks to the shape of this grinding tool, this process even allows the radiation of edges of difficult access.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood and its advantages will appear better on reading the detailed description which follows, of an embodiment shown by way of non-limiting example. The description refers to the accompanying drawings in which: - Figure 1 is a perspective of a grinding tool according to a first embodiment of the invention; Figure 2 is a side view of the grinding tool of Figure 1; - Figure 3 illustrates the abrasive sheet of the tool of Figure 1 in the unfolded position; FIG. 4 illustrates the use of the grinding tool of FIG. 1 for the shelving of the edges of a festoon; FIGS. 5A to 5C illustrate the profile of the festoon of FIG. 3 at each step of the shelving method; - Figures 6 to 9 illustrate variants of the grinding tool of Figure 1; and FIG. 10 is a perspective view of a grinding tool according to another embodiment of the invention.

Detailed description of the invention

A grinding tool 1 according to a first embodiment is illustrated in Figures 1 and 2. As can be appreciated in Figure 1, this tool 1 comprises a rod 2 and a flexible sheet 3. The rod 2 has a nozzle 2a to be received by a tool spindle for driving the tool 1 in rotation about a longitudinal axis X of the rod 2. On its opposite end 2b, the rod 2 has a cross member 4 forming a support for the sheet 3 integral with the rod 2, and substantially perpendicular to its longitudinal axis X. In this context, the term "substantially perpendicular" as forming a non-inferior angle, for example, at 80 ° and not higher, for example, at 100 °.

The sheet 3 is supported on the crosspiece 4 with an inner face 5, which is not necessarily abrasive. By against its outer face 6 has an abrasive surface formed by grains of a material of high hardness, such as silicon carbide, adhered to a flexible substrate of the sheet 3, which may be for example waterproof paper . Thus, the sheet 3 may be formed by so-called glass or emery paper with its abrasive face facing outwards.

The sheet 3 is folded against the crosspiece 4, thus forming a distal edge 7 between two wings 3a, 3b opposite. The ends of each wing 3a, 3b form proximal edges 8. These proximal edges 8 are connected by lateral edges 9 on either side of the rod 2. In the illustrated embodiment, said lateral edges 9 are substantially perpendicular to the distal edge 7 and the proximal edges 8. The sheet 3 is arranged substantially symmetrically with respect to a plane of symmetry S substantially perpendicular to the outer face 6 of the sheet 3 and comprising the longitudinal axis X of the rod 2. By "substantially symmetrical" is meant, in the present context, a center line of the sheet 3 is not shifted by, for example, more than 10% of the width of the sheet 3 relative to this plane of symmetry S.

The sheet 3 is retained against the crosspiece 4 by a removable retention piece 10, which in turn is fixed, in the illustrated embodiment, by a screw 11 engaged in an internal thread of the end 2b of the rod 2. However, other releasable attachment means of the removable retention piece may optionally be envisaged.

The sheet 3 also has, on each side of the plane of symmetry S, a slot 12 from each proximal edge 8, so as to form a bending line 13 between an inner end 14 of the slot 12 and the nearest lateral edge 9. Each slot 12 and bending line 13 delimit, with the proximal edge 8 and the corresponding lateral edge 9, a working area 14 that can tilt around the bending line 13. In the illustrated embodiment, the slots 12 are substantially parallel to the side edges 9 of the sheet 3. By "substantially parallel" is meant in this context, that the slots do not diverge more than, for example, 10 ° with respect to the side edges 9. As illustrated in particular on the 3, each slot 12 has a width Lf, a depth PF between the proximal edge 8 of departure and its inner end 14, and a distance DF with respect to the nearest side edge 9. For example, in the embodiment of FIG. As illustrated, the width LF can be between 1 and 2 mm, the depth PF between 12 and 22 mm, and the distance DF between 10 and 15 mm.

In Figure 2, it can be appreciated how the sheet 3 is bent by its distal edge 7 with an angle α (ALPHA) of, for example, 20 to 60 °. This sheet 3, unfolded as illustrated in FIG. 3, has a width L between the lateral edges 9 of, for example, 127 mm, and a length H between the proximal edges 8 of, for example, 70 mm.

This grinding tool 1 can in particular be used in a method of shelving difficult access edges, and in particular annular festoons such as that illustrated in FIG. 4. For this, the grinding tool 1, oriented with the axis longitudinal X of the rod 2 substantially perpendicular to the festoon 20, as illustrated in FIG. 4, is rotated about the longitudinal axis X at a speed N which can be, for example, between 1000 and 5000 revolutions / minute, contacting the ridges 21 of the festoon 20 with the work areas 14 to round these edges. The grinding tool 1 can move in the plane of the festoon along the edges 21 to treat them over their entire length. The tool spindle (not shown) driving the grinding tool in rotation can, for example, be actuated electrically or by a fluid actuator, in particular pneumatic.

These ridges 21 may have been previously chamfered in a first step of the shelving process, which can be implemented, for example, by milling. The evolution of the ridges 21 following each step of such a process is illustrated in FIGS. 5A to 5C. Figure 5A illustrates the raw profile of the festoon 20 prior to any operation of the shelving process. FIG. 5B illustrates the same profile after the chamfering of the ridges 21. Finally, FIG. 5C illustrates the profile after the abrasive machining, with the grinding tool 1, of the edges 21 previously chamfered.

Although, in the embodiment illustrated in Figures 1 and 2, the crossbar 4 of the grinding tool 1 has a round cross section, other alternatives may be envisaged, such as that illustrated in Figure 6. In this variant, the crosspiece 4 has a trapezoidal cross-section, with side surfaces 4a and 4b converging in a distal direction with substantially the same angle α (ALPHA) as the wings 3a, 3b of the sheet 3. In addition, it is also it is possible to have several abrasive sheets 3, each supported by a crosspiece 4. These crosspieces 4 can be arranged in a cross, as in the variants illustrated in FIGS. 7 and 8, or in a star, as in the variant illustrated in FIG. 9 In each of these figures, the elements receive the same reference numerals as the equivalent elements of the first embodiment. It is thus possible, by cutting and gluing these abrasive sheets, a multi-blade brush as illustrated.

Figure 10 illustrates yet another different embodiment. In this other embodiment, the rod 2 has, on its distal end 2b, a clamp 30 for retaining the sheet 3. This clamp 30 comprises two branches 30a, 30b connected by a central hinge 31 supported by the distal end of the rod 2. The branch 30b is fixed in the rod 2, while a spring 32 located behind the hinge 31 provides a return closing the distal end of the pivoting arm 30a against that of the fixed branch 30b. In order to reinforce this return during the rotation of the tool 1 about its longitudinal axis X, the center of mass CM of the pivoting branch 30a is located behind the central hinge 31, so that the centrifugal forces acting on the branch pivoting 30a contribute to close its distal end against that of the fixed branch 30b.

In this embodiment, the sheet 3 is retained between the distal ends of the two branches 30a, 30b. It is folded, unlike the first embodiment, by its proximal edge 8, although it can also be alternately considered to bend by its distal edge. As in the first embodiment, the grinding tool 1 is substantially symmetrical about a plane of symmetry S perpendicular to the outer face 6 of the sheet 3, which has, on each side of the plane of symmetry S, a slot 12 from each proximal edge 8, so as to form a bending line 13 between an inner end 14 of the slot 12 and the nearest side edge 9. Each slot 12 and bending line 13 delimit, with the proximal edge 8 and the corresponding side edge 9, a working area 14 capable of tilting around the bending line 13. As in the first embodiment, the slots 12 are substantially parallel to the side edges 9 of the sheet 3. Each slot 12 has a width LF, a depth PF between the proximal edge 8 of departure and its inner end 14, and a distance DF relative to the nearest side edge 9. These dimensions, as well as the width L and length H of the fe 2, may be similar to those of the first embodiment, but they are also adaptable according to the application given to the grinding tool 1. The remaining elements of the grinding tool 1 illustrated in this figure receive the same reference numerals as the equivalent elements of the first embodiment.

Although the present invention has been described with reference to a specific exemplary embodiment, it is obvious that various modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. In addition, individual features of the various embodiments mentioned can be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

Claims (10)

A grinding tool (1) comprising: a rod (2) with a bit (2a) to be received by a tool spindle for driving the tool (1) in rotation about a longitudinal axis (X) of the rod (2); at least one sheet (3) fixed to said shank (2) and having at least one abrasive outer face (6) between a proximal edge (8) and a distal edge (7) offset with respect to each other along at least the direction of said longitudinal axis (X) of the rod (2), and two lateral edges (9) offset with respect to each other in at least one direction orthogonal to said longitudinal axis (X) of the rod (2); characterized in that said sheet (3) has, between said abrasive outer face (6) and an opposite face (5), at least one slot (12) extending from one of said proximal (8) or distal (7) edges . 2. Grinding tool (1) according to claim 1, wherein said slot (12) has a width (LF) of not less than 1 mm and / or not greater than 2 mm. The grinding tool (1) according to any one of claims 1 to 3, wherein said slot (12) has a distance (Df) from the nearest side edge (9) of the sheet (3), not less than 10 mm and / or not more than 15 mm. The grinding tool (1) according to any one of claims 1 to 3, wherein said slot (12) has a depth (PF) from the proximal (8) or distal (7) starting edge, no less than 12 mm and / or not more than 22 mm. Grinding tool (1) according to any one of claims 1 to 4, which is substantially symmetrical with respect to a plane (S) aligned with said longitudinal axis (X) of the rod (2) and perpendicular to the proximal edges (8) and distal (7) of the sheet (3). The grinding tool (1) according to any one of claims 1 to 5, wherein said sheet (3) is bent by one of its proximal (8) or distal (7) edges. The grinding tool (1) according to claim 6, wherein said sheet (3) is folded by its distal edge (7), said distal edge (7) of the sheet (3) being held between a support (4) secured to said rod (2) and substantially perpendicular to its longitudinal axis (X), and a removable retention piece (10). 8. Grinding tool (1) according to any one of claims 1 to 6, wherein said rod (2) has, on a distal end (2b), a clamp (30) retaining said sheet (3). A method of edge shelving (21) comprising an abrasive machining step with a grinding tool (1) according to any one of claims 1 to 8. The edge shelving method (21) of claim 9, further comprising a prior step of chamfering the ridges (21) prior to said abrasive machining step.