Sander, especially for sanding curved surfaces

Abstract

A sander especially suited for sanding curved surfaces. The sander has an elongate body and a grinding plate movably attached thereto. A power unit drives the grinding plate. At least two lever beams are attached to the elongate body. Each of the lever beams has two opposite ends. The grinding plate is attached to ends of lever beams using flexible connecting elements to allow the grinding plate to move relative to the sander body.

Claims

1. Sander especially for sanding curved surface areas, comprising: an elongate body (1,17); a sanding plate (14) movably attached to said body (1, 17); and a power unit (19) connected to said sanding plate (14) for driving said sanding plate to provide a sanding motion of said sanding plate, wherein the sanding plate (14) is connected with said body (1) by at least two movable lever beams (9, 20) that are attached to said body (1, 17) one apart from another, said lever beams being provided with two opposite ends, wherein said sanding plate (14) is attached to said ends of said movable lever beams (9,20) by elastic connecting elements (10, 21) allowing to equally distribute a pressing force onto said flexible sanding plate, and allowing a shapeability/malleability of said sanding plate towards said curved surface, and enabling said sanding plate to make a defined linear or orbital motion relative to said body (1, 17) when driven by said power unit.

2. Sander according to claim 1, wherein, each lever beam (9, 20) is movably attached by means of a pivot (7) to said body (1), wherein said two flexible connecting elements (10, 21) are attached at each opposite end of said movable lever beams (9, 20), wherein said flexible sanding plate is connected over said flexible connecting elements (10,21) with said lever beams (9) so as to provide for a longitudinal flexibility of said sanding plate towards a curvature of said curved surface area to be sanded, said flexible connection of said sanding plate (14) allowing a relative sanding motion of said sanding plate towards said body (1), when being driven by said power unit, regardless of a deformation of said sanding plate and a mutual position of said sanding plate to said elongate body (1).

3. Sander according to claim 1, wherein said sanding plate (14) is attached to said power unit by means of a grooved shaft (11) having a variable length, said grooved shaft (11) being provided on an end of it with an eccentrically mounted pivot, rotating in a bearing case (12), whereas an off-set distance of said pivot defines a magnitude and direction of a movement of said sanding plate in relation to said body (1).

4. Sander according to claim 1, wherein said variable length grooved shaft (11) is provided on an end of it with a counterweight (5) in order to eliminate sanding plate inertia forces as well as vibrations induced by said forces into said body (1).

5. Sander according to claim 1, wherein a flexible cover plate is arranged in parallel with said sanding plate (14), an elastic sealing (16) being arranged between said flexible cover plate and said sanding plate so as to bond them together and/or to seal them together.

6. Sander according to claim 5, wherein a space is arranged between said sanding plate (14) and said cover plate (13), said space between said sanding plate and said cover plate being in communication with an extraction sleeve (8), whereas said sanding plate (14) is provided with openings arranged for an extraction of a material sanded by said sanding plate (14) through said sleeve (8).

7. Sander according to claim 6, wherein said sanding segments (23,25) are connected with said base plate by means of flexible connecting elements connected to at least three brackets (28).

8. Sander according to claim 1, wherein said sanding plate (14) comprises a flexible basic plate (26) and at least two flexible sanding segments (23, 25), said at least two flexible sanding segments (23, 25) being arranged in parallel with said flexible basic plate (26), said flexible sanding segments (23, 25) being driven to carry out a relative moment in relation to said body and said base plate.

9. Sander according to claim 1, wherein said flexible connecting element is a rubber bushing or a spring.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The subject of the invention will be more apparent with a help of the drawings, on which

(2) FIG. 1 illustrates the basic principle of the sander according to the invention by means of an example of the embodiment with a grinding plate in one piece;

(3) FIG. 2 illustrates the principles of the sander with a grinding plate consisting of two grinding elements; and

(4) FIG. 3 illustrates a detail of a connection of basic flexible plate and the flexible moving segment in a section A-A from FIG. 2.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Example 1

(5) A sander for grinding curved surface areas according to FIG. 1 is accomplished with a body 1 of the sander, having a power unit 6 placed on it. The Power unit 6 is in the present example an electric motor having an angled transmission unit 4, which is mounted on a bearing case 3 with a telescopic grooved shaft 11. The grooved shaft 11 allows for a transmission of the torque from the power unit to the grinding plate 14 even in different bents of the grinding plate 14 due to its adaptation to a shape the grinded surface area. The grooved shaft 11 is provided on its end with an eccentric pivot, whereas the distance of its off-sett from the longitudinal axis of the grooved shaft imparts the relative movement, i.e. oscillation, being performed by grinding plate 14 in relation to the body 1 of the sander. The pivot is accommodated in the bearing case 12 which is firmly connected to the grinding plate 14. The grinding plate 14 is attached to the body 1 of the sander by means of four pairs of flexible connecting elements 10, in this example also formed by a silent-block, and by means lever beams 9, pivotally situated on pins 7. The flexible connecting elements 10 provide for either an equally distributed pressure of the grinding plate onto the grinded surface, an either for partial torsion deformation and flexible adaptation of the grinding plate 14 towards the grinded surface. When fixing the shape of the grinding plate 14 would be required, it is possible to fix the position of the lever beams 9 in relation to the body 1 of the sander by means of appropriate locks or possibly by means of transversal mortising etc.

(6) In a preferable embodiment of the sander according to the invention, the grinding plate 14 is provided with orifices allowing extraction of sanding dust. The arrangement of the extraction system comprises a grinding plate 14 provided with a cover plate 13 with a sealing 16. The cover plate 13 is connected with a sleeve 8 arranged so as to allow a connection of an extraction device, being place on a lever beam 9, through a flexible bellow 15. After connection of the extraction device, suction occurs between the grinding plate 14 and the cover plate 13 by means of which material remover by grinding is extracted.

(7) In order to reduce vibrations, the sander is equipped with a counterweight 5. The grooved shaft 11 with the counterweight 5 may be covered with a flexible sleeve in order to provide sealing against dust as well as to provide safety covering of the rotating counterweight 5.

Example 2

(8) A sander for grinding curved surfaces according to FIG. 2 is in principle similar to the sander according to FIG. 1. The difference from FIG. 1. is, that the grinding plate is in this embodiment formed of a flexible base plate 26 and of flexible grinding segments (blades) 23,25. The parameters as flexibility and stiffness of the tool are determined in by the flexible base plate 26 in this embodiment, instead of the grinding plate as it was in the embodiment from FIG. 1. The grinding itself is accomplished by two flexible grinding segments 23, 25 that are attached to the flexible base plate 26 through flexible connecting elements 21, 22 and brackets 28. Again, the flexible connecting elements are on FIG. 2 accomplished as silent-blocks. Each of the grinding segments 13, 25 is connected with the flexible base plate 26 by means of four brackets 28, displace equally along the length of the grinding plate, and four pairs of flexible connection elements 21. Said flexible connection elements 21 keep the grinding elements 23,25 in a relatively constant distance from the base plate 26, regardless of its deformation (bending). Thus designed mounting which uses flexible connection elements, silent-blocks in the example, allows for movement of the grinding segments in relation to the flexible base plate 26, similarly to the embodiment on FIG. 1. Each of these grinding segments 23, 25 is driven independently by a power unit 19, provided with a shaft with an eccentric pivot so as to transform the rotational movement of the power unit onto a sliding linear or orbital movement of each grinding segments 23, 25. Said power units are firmly connected to a flexible base plate 26. The base plate 26 replaces in this embodiment the function of the body 1 of the sander on FIG. 1, as it is connected with the body 17 of the sander and it does not carry out any grinding movements in relation to the body 17. The power unit 19 can be represented by e.g. a separate motor as seen on FIG. 2, but it can be also represented by a transmission unit, which is driven by a flexible shaft or cardan shaft from one central motor, etc. In case the transmission units are used, it is preferred to set the mutual synchronization of their movements so the grinding plates move one against the other. This way is preferred especially in case even number of the grinding segments. The flexible base plate 26 is equipped with similar system of equal distribution of the force onto the grinded surface area, as in case of the embodiment on FIG. 1, using the lever beams 20 connected with the flexible base plate 26 by means of silent-blocks 22. The lever beams 20 are connected with the body 17 of the sander by means of pivots allowing turn movement of the lever beams 20 in relation to the body 17. The flexible base plate 26 can be advantageously used in a sanding dust extraction. The flexible base plate overlaps the flexible grinding segments on its each side. To the overhang, sealing profile 27 is attached, reaching up to the grinded surface, thus creating a closed space. It is sufficient to attach properly an extraction device to the flexible base plate 26. It is possible to fix the position of the lever beams 20 relative to the body 17, thus fixing the respective plane or bending diameter as in case of the example 1. The technical solution according to FIG. 2 allows for a use of substantially any number of the flexible grinding segments. So a construction of a tool with substantially any length is possible.

(9) An implementation of a power unit on FIG. 1 and FIG. 2 is mentioned only as an example and it is possible to combine them as required. It means that any implementation is linked only for the respective embodiment of the sander. Thus it is possible to use for the embodiment of the sander from FIG. 1 an analogous embodiment of the grinding plate from FIG. 2 etc.

INDUSTRIAL APPLICABILITY

(10) The design of the sander according to the invention can be used in a structure of new types of sanders or grinding machines for grinding different types of curved surface areas in all fields of industry.

LIST OF REFERENCE NUMERALS

(11) 1—body of the sander 2—grip/handle 3—bearing case 4—transmission unit 5—counterweight 6—power unit 7—pivot 8—sleeve for an extraction 9—lever beam 10—flexible connecting element 11—grooved shaft with an eccentric pivot 12—bearing case 13—cover plate 14—flexible grinding plate 15—extraction bellow 16—sealing elastomer 17—body of the sander 18—grip/handle 19—power unit 20—lever beam 21—flexible connecting element 22—flexible connecting element 23—flexible grinding segment A 24—shaft with an eccentric pivot 25—flexible grinding segment B 26—flexible base plate 27—sealing 28—bracket of the flexible connecting elements 29—screw 30—spacer