GB1574547A

GB1574547A - Orbital abrader

Info

Publication number: GB1574547A
Application number: GB12985/78A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1977-05-04
Filing date: 1978-04-03
Publication date: 1980-09-10
Also published as: IT1096199B; IT7822976A0; ES469403A1; DE7713994U1; NL7804678A; FR2389455A1; JPS53136793A

Description

(54) AN ORBITAL ABRADER (71) We, ROBERT BOSCH GUSH, a German company of Postfach 50, 7000 Stuttgart 1, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention is concerned with orbital abraders.

Orbital abraders are known which comprise a handle, a driving motor incorporated in a motor housing, an abrader housing, an abrader plate connected to the abrader housing by at least one resilient connecting member, and two clamping devices attached to the abrader plate and adapted to clamp a flexible abrasive sheet stretched over the abrader plate.

In one such orbital abrader, each clamping device comprises a stirrup formed as a two-armed lever, one arm of which is a clamping arm and the other of which is a free arm actuable by hand and the clamping devices are located between the abrader housing and the abrader plate. This abrader is further described below with reference to Figure 1 of the accompanying drawings.

In this abrader, the resilient connecting member between the abrader housing and the abrader plate is a hollow, elastic rubber cylindrical sleeve which serves to protect the crank drive to the abrader plate against dust, but also hinders the removal of heat developed in the crank drive. Since this abrader has a metal abrader housing through which the heat dissipated from the abrader plate drive flows and from which the heat is dissipated to the atmosphere, the enclosing of the drive provided by the resilient connecting member is not noticeably troublesome in practice, even on lengthy operation of the abrader.

Tn another known orbital abrader of the kind referred to, four elastic rubber pillars are provided as the resilient connecting members between the abrader housing and the abrader plate. This abrader is further described below with reference to Figures 2 and 3 of the accompanying drawings.

In this abrader, the clamping devices are of the same general kind as those of the previously described abrader, but the free lever arm of each device is arranged outside and above the abrader housing. While this makes the free lever arms very accessible for use, the very accessibility of these free arms can give rise to accidents when the abrader is being used.

We have now developed an improved orbital abrader of the kind referred to- in which the clamping devices are safely located and resilient connecting members are provided between the abrades housing and the abrader plate which do not hinder the escape of heated air from the driving parts which move the abrader plate.

According to the present invention, there is provided an orbital abrader comprising a handle, a driving motor incorporated in a motor housing, an abrader housing, an abrader plate connected to the abrader housing by two pairs of resilient pillars, the pairs being spaced from and on either side of the drive for the abrader plate and near the outer edge of the latter, and two clamping devices attached to the abrader plate and adapted to clamp a flexible abrasive sheet stretched over the abrader plate, each clamping device being located between a pair of the pillars and comprising a stirrup formed as a two-armed lever, one arm of which is a clamping arm and the other of which is a free arm actuable by hand and located between the abrader housing and the abrader plate.

The abrader housing is preferably formed of a plastics material and is preferably formed integrally with the motor housing and the handle. The abrader can then be made fully insulating and when so- constructed is lighter in weight than- with a metal abrader housing and cheaper to manufacture.

In order that the invention may be more fully understood. two known orbital abraders and a preferred embodiment of the orbital abrader according to the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a partial sectional elevation of a first known orbital abrader; Figure 2 is a partial sectional elevation of a second known orbital abrader; Figure 3 is a partial perspective view of the abrader plate of the abrader shown in Figure 2; Figure 4 is a sectional elevation of an embodiment of the orbital abrader according to the invention; and Figure 5 is a partial perspective view of the abrader plate of the abrader shown in Figure 4.

In the following, " above " is to be understood as the direction towards the driving motor and "below" is to be understood as the direction towards the abrader plate.

The orbital abrader illustrated in Figure 1 has a plastics motor housing 1 with a driving motor 2 incorporated therein, a metal abrader housing 3 and an abrader plate 4. The abrader housing 3 extends slightly beyond the abrader plate and is provided with a skirt 3' which forms a suction enclosure that surrounds the abrader plate and, by means of a sealing lip 3", is substantially flush with the abrasive paper (not shown) stretched over the abrader plate.

The abrader plate can be set in oscillating motion describing small circles by the motor through a V-belt 5 and a crank drive 6. The abrader plate 4 is resiliently connected to the abrader housing 3 by a shield 7 consisting of elastic rubber material in the form of a hollow cylinder. The shield is fixed to the abrader housing and to the abrader plate by hose clips 8 and 9 and sealingly encloses the V-belt drive and the crank drive.

Two two-armed clamping stirrups 10 and 11 are mounted at the two narrow sides of the abrader plate, each on a bearing block 12, 13 and each has a clamping arm 14, 15 and a free lever arm 16, 17. The clamping stirrups further comprise a helical torsion spring 18, 19, one end of which bears against the underside of the free arm 16, 17, while the other end bears against the upper surface of the abrader plate. The spring 18, 19 urges the clamping arm 14, 15 into clamping engagement with the abrasive paper. The clamping stirrups and all their parts are located between the abrader plate and the abrader housing, the free lever arms extending in a direction towards the drive for the abrader plate.

The known orbital abrader illustrated in Figures 2 and 3 has an abrader housing 20 and an abrader plate 21 which is made somewhat longer than the abrader housing; the abrader housing and the abrader plate are connected to one another by four pillars 22. The pillars 22 are elastic rubber hollow cylinders. Two clamping stirrups 23 are mounted at the narrow ends of the abrader plate 21 by means of bearing lugs 24. Their clamping arms 25 are pressed inwardly against a rim 27 on the abrader plate, where the abrasive paper 28 is clamped, by helical torsion springs 26. The free lever arms 29 of the clamping stirrups are located above the abrader housing 20.

The orbital abrader according to the invention shown in Figures 4 and 5 has an abrader housing 30, which projects slightly beyond the abrader plate 31 beneath it.

The housing 30 is formed of plastics material and is integral with the motor housing and the handle. The abrader plate can be set in oscillating motion by the driving motor 33 through a crank drive 32. The abrader housing and the abrader plate are connected by four elastic rubber pillars 34 which are arranged in two pairs substantially at the ends of the abrader plate. A clamping stirrup 35 is rotatably mounted on bearing lugs 36 between each pair of pillars at a narrow side of the abrader plate.

Each clamping stirrup has a clamping arm 37 and a free lever arm 38 directed towards the drive to the abrader plate. The damp ing arm 37 are forced against the upper surface of the abrader plate, where they clamp the abrasive paper (not shown), by a helical torsion spring 39. By pressing on the free lever arm 38, which extends laterally up to one of the longer edges of the abrader plate and is accessible from above through a cut-out in the abrader housing, the associated clamping arms 37 can be raised so as to release the abrasive paper for exchanging.

WHAT WE CLAIM IS: 1. An orbital abrader comprising a handle, a driving motor incorporated in a motor housing, an abrader housing, an rader plate connected to the abrader housing by two pairs of resilient pillars, the pairs being spaced from and on either side of the drive for the abrader plate and near the outer edge of the latter, and two clamping devices attached to the abrader plate and adapted to clamp a flexible abrasive sheet stretched over the abrader plate, each clamping device being located between a pair of the pillars and comprising a stirrup formed as a two-armed lever, one arm of which is a free arm actuable by hand and located between the abrader housing and the abrader plate.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. metal abrader housing and cheaper to manufacture. In order that the invention may be more fully understood. two known orbital abraders and a preferred embodiment of the orbital abrader according to the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a partial sectional elevation of a first known orbital abrader; Figure 2 is a partial sectional elevation of a second known orbital abrader; Figure 3 is a partial perspective view of the abrader plate of the abrader shown in Figure 2; Figure 4 is a sectional elevation of an embodiment of the orbital abrader according to the invention; and Figure 5 is a partial perspective view of the abrader plate of the abrader shown in Figure 4. In the following, " above " is to be understood as the direction towards the driving motor and "below" is to be understood as the direction towards the abrader plate. The orbital abrader illustrated in Figure 1 has a plastics motor housing 1 with a driving motor 2 incorporated therein, a metal abrader housing 3 and an abrader plate 4. The abrader housing 3 extends slightly beyond the abrader plate and is provided with a skirt 3' which forms a suction enclosure that surrounds the abrader plate and, by means of a sealing lip 3", is substantially flush with the abrasive paper (not shown) stretched over the abrader plate. The abrader plate can be set in oscillating motion describing small circles by the motor through a V-belt 5 and a crank drive 6. The abrader plate 4 is resiliently connected to the abrader housing 3 by a shield 7 consisting of elastic rubber material in the form of a hollow cylinder. The shield is fixed to the abrader housing and to the abrader plate by hose clips 8 and 9 and sealingly encloses the V-belt drive and the crank drive. Two two-armed clamping stirrups 10 and 11 are mounted at the two narrow sides of the abrader plate, each on a bearing block 12, 13 and each has a clamping arm 14, 15 and a free lever arm 16, 17. The clamping stirrups further comprise a helical torsion spring 18, 19, one end of which bears against the underside of the free arm 16, 17, while the other end bears against the upper surface of the abrader plate. The spring 18, 19 urges the clamping arm 14, 15 into clamping engagement with the abrasive paper. The clamping stirrups and all their parts are located between the abrader plate and the abrader housing, the free lever arms extending in a direction towards the drive for the abrader plate. The known orbital abrader illustrated in Figures 2 and 3 has an abrader housing 20 and an abrader plate 21 which is made somewhat longer than the abrader housing; the abrader housing and the abrader plate are connected to one another by four pillars 22. The pillars 22 are elastic rubber hollow cylinders. Two clamping stirrups 23 are mounted at the narrow ends of the abrader plate 21 by means of bearing lugs 24. Their clamping arms 25 are pressed inwardly against a rim 27 on the abrader plate, where the abrasive paper 28 is clamped, by helical torsion springs 26. The free lever arms 29 of the clamping stirrups are located above the abrader housing 20. The orbital abrader according to the invention shown in Figures 4 and 5 has an abrader housing 30, which projects slightly beyond the abrader plate 31 beneath it. The housing 30 is formed of plastics material and is integral with the motor housing and the handle. The abrader plate can be set in oscillating motion by the driving motor 33 through a crank drive 32. The abrader housing and the abrader plate are connected by four elastic rubber pillars 34 which are arranged in two pairs substantially at the ends of the abrader plate. A clamping stirrup 35 is rotatably mounted on bearing lugs 36 between each pair of pillars at a narrow side of the abrader plate. Each clamping stirrup has a clamping arm 37 and a free lever arm 38 directed towards the drive to the abrader plate. The damp ing arm 37 are forced against the upper surface of the abrader plate, where they clamp the abrasive paper (not shown), by a helical torsion spring 39. By pressing on the free lever arm 38, which extends laterally up to one of the longer edges of the abrader plate and is accessible from above through a cut-out in the abrader housing, the associated clamping arms 37 can be raised so as to release the abrasive paper for exchanging. WHAT WE CLAIM IS:

1. An orbital abrader comprising a handle, a driving motor incorporated in a motor housing, an abrader housing, an rader plate connected to the abrader housing by two pairs of resilient pillars, the pairs being spaced from and on either side of the drive for the abrader plate and near the outer edge of the latter, and two clamping devices attached to the abrader plate and adapted to clamp a flexible abrasive sheet stretched over the abrader plate, each clamping device being located between a pair of the pillars and comprising a stirrup formed as a two-armed lever, one arm of which is a free arm actuable by hand and located between the abrader housing and the abrader plate.

2. An orbital abrader according to

claim 1, in which the abrader housing is formed of a plastics material.

3. An orbital abrader according to claim 2, in which the abrader housing is formed integrally with the motor housing and the handle.

4. An orbital abrader according to any of claims 1 to 3, in which the clamping arm of each clamping device is on the side of the pivot towards the edge of the abrader plate and the free lever arm is on the other side of the pivot towards the centre of the abrader plate.

5. An orbital abrader according to any of claims 1 to 4 in which the pillars are substantially cylindrical and are formed of an elastic rubber material.

6. An orbital abrader substantially as herein described with reference to Figures 4 and 5 of the accompanying drawings.