WO1998045088A1

WO1998045088A1 - A grinding device

Info

Publication number: WO1998045088A1
Application number: PCT/SE1998/000565
Authority: WO
Inventors: Kjell Persson
Original assignee: Kjell Persson
Priority date: 1997-04-04
Filing date: 1998-03-27
Publication date: 1998-10-15
Also published as: AU6935198A; SE9701234L; SE9701234D0; SE508033C2

Abstract

A grinding device includes three mutually parallel guide rollers (31-33) around which an endless grinding belt (134) runs. One (31) of the rollers is rotated by a drive motor and the rollers are mounted for rotation in bearings at least at one end thereof, wherein one of the rollers is mounted for parallel movement against the action of a spring device (54) that tightens the grinding belt. At least two (33, 34) of the rollers are mounted in bearings on a base (40) and means (41, 42) are provided for fixing the position of the base (40) in relation to a bottom plate (14) belonging to a column-drill stand (11). The drill-stand is adapted to support an electric hand-drill (2) in vertical orientation and to enable the vertical position of the drill (2) to be adjusted. The motor-driven roller (31) has a first end (37) which can be connected to the driving spindle (21) of the drill (2). A support plate (60) can be fitted behind a part of the grinding belt so as to enable a flat surface on a workpiece to be ground.

Description

A GRINDING DEVICE

The present invention relates to a grinding device of the kind defined in the preamble of Claim 1.

The type of grinding device to which the invention relates includes three parallel guide rollers around which an endless grinding belt runs, wherein one of the rollers is driven for rotation by a drive motor, and wherein one of the rollers is mounted so that it can be moved in parallelism against the action of a spring device, said spring device being operative to tension the endless belt running around the guide rollers.

One such grinding device is known from DE 844 420, for instance.

Grinding devices of this kind are used to finely grind round objects, by pressing the object against the grinding belt between two peripherally adjacent rollers.

It is highly desirable that artisans have access to such belt grinders. However, such grinders are relatively expensive, due to the costs entailed by the motor, and such grinding devices also require a relatively large amount of storage space when not in use.

The object of the present invention is to provide a grinding device that alleviates these drawbacks. This object is achieved with a grinding device according to the following Claim 1. Further embodiments of the inventive grinding device are set forth in the dependent Claims.

The invention is based on the use of an electric hand drill as a drive motor, wherewith the drilling machine is carried by a drill stand and adapted to support and rotate one of the rollers of said grinding device. Means are provided for fixing the position of the base of the grinding device in relation to the bottom plate of the drill stand.

Ideally, the free end of the driven guide roller will be mounted for rotation in the base or bottom plate, in a manner that will ensure that the driven guide roller will be kept parallel with the remaining two guide rollers.

According to one embodiment of the invention, the base carries a support plate inwardly of the path travelled by the grinding belt, said support plate lying in the area between two mutually sequential guide rollers in the peripheral direction thereof, wherewith the plate is generally parallel with the adjacent part of said grinding belt. When a workpiece is pressed against this part of the belt, the belt is able to slide on the support plate, due to the displaceability of the roller mounted for parallel movement, wherein the grinding effect can be amplified by virtue of enabling the force at which the grinding belt abuts the workpiece to be stepped-up markedly when the belt slides supportingly on the support plate.

The invention will now be described in more detail with reference to an exemplifying embodiment thereof and also with reference to the accompanying drawings, in which Fig. 1 is a schematic, perspective view of an inventive grinding device; and

Fig. 2 is a horizontal view of the inventive device.

As will be seen from Fig. 1, the device includes three mutually parallel guide rollers 31-33 and an endless grinding belt 134 that runs around said rollers. The roller 31 includes a trunnion 37 which is connected to the chuck 21 of an electric hand drill 2. The hand drill 2 is carried by a pillar stand 11 which includes a vertical pillar or post 12 carried by a horizontal support plate 14 and supporting a fixture 13 for vertical adjustment of the position of the drilling machine 2.

The rollers 32, 33 are mounted on a base 40 and means 41 are provided for fixing the position of the base 40 in relation to the stand plate 14. As will be seen from Fig. 2, the base 40 includes an edge recess 142 between the rollers 33, 34. It will also be seen that the roller 34 is carried on the outer end of a pivot arm 50 that is pivotal about a pivot axis 51 at the inner end of the arm, and that the arm 50 is biased by a spring 54 to tighten the grinding belt 134 running around the rollers 31-33. Because the roller 34 is mounted for parallel movement, the part of the belt that is located between the rollers 33 and 34 can be pressed into the recess 142. In this regard, the bottom of the recess 142 will preferably lie inwardly of the edge 5 of the table 4 on which the base 40 and the bottom plate 14 stand. As shown in Fig. 2, a support plate 60 is mounted inwardly of the belt run between rollers 33, 34, the outer surface of said plate being located outwardly of the table edge 5. When a workpiece is pressed more heavily against the belt, the belt will be pressed towards and slide along the plate 60, therewith increasing the contact pressure between workpiece and belt and therewith greatly amplifying the grinding effect. Furthermore, a flat part of a workpiece may be ground over the whole of its area on the belt, since the belt runs while supported against the, e.g., planar support plate 60. The support plate 60 may be detachably connected to the base 40, e.g. by means of a fishtail connection as shown at 61. When the plate 60 is in an operative position, the grinding device will, in practice, function as a flat grinder. When the plate 60 is not fitted, or has been moved to a position in which it does not support the grinding belt in its grinding work, the grinding belt will shape flexibly around the workpiece in that region thereof that is pressed against said belt. Due to the resilient suspension of one of the rollers and also due to the flexibility of the grinding belt, the belt is able to shape conformingly to the workpiece and enable rounded workpiece surfaces to be ground.

As will be seen from Fig. 2, the base 40 may be provided with pegs 41 which fit into corresponding holes 42 in the bottom plate 14, so as to enable the base to be held in position relative to the base plate. In the illustrated case, the bottom end of the roller 31 is mounted in a bearing in the base 40 or the plate 14, even when the trunnion 37 has a relatively small diameter.

It will be understood, however, that the bottom end-part of the roller 31 need not be mounted in a bearing.

Claims

1. A grinding device that includes three mutually parallel guide rollers (31-33) around which an endless grinding belt (134) runs, wherein one (31) of the rollers is driven rotatably by a drive motor and the rollers are rotatably mounted in bearings at at least one end thereof, and wherein one of the rollers is mounted for parallel movement against the action of a spring device (54) that functions to tighten the belt, characterised in that at least two (33, 34) of the rollers are mounted in bearings on a base (40); and in that means (41, 42) are provided for fixing the position of the base (40) in relation to the base plate (14) of a column drill-stand (11) adapted to carry an electric hand-operated drilling machine (2) in vertical orientation and to enable adjustments to be made to the vertical position of the drilling machine (2); and in that the motor-driven roller (31) has a first end (37) which can be connected to the driving spindle (21) of the drilling machine (2).

2. A grinding device according to Claim 1, characterised in that the bottom end-part of the roller (31) that is driven by said drilling machine (2) is rotatably mounted in the base (40) or in the bottom plate (14).

3. A grinding device according to Claim 1 or 2, characterised in that the base (40) carries a support plate (60) that extends between two mutually adjacent rollers (33, 34) in the movement direction of the grinding belt (34), and is disposed generally parallel with and slightly spaced inwardly of that part of the grinding belt that runs between said rollers.

4. A grinding device according to Claim 3, characterised in that one of said two mutually adjacent rollers (33, 34) supporting said part of said grinding belt is spring-biased (54) away from the second (33) of said rollers (33, 34).

5. A grinding device according to Claim 3 or 4 , characterised in that the base includes a recess (142) on that side on which the support plate (60) is located, wherein the bottom edge-surface of the recess (142) lies inwardly of the support surface of said support plate (60).

6. A grinding device according to any one of Claims 1-5, characterised in that the roller (31) that is driven by the hand drilling machine has a trunnion (37) which is intended to be gripped by the chuck (21) of said drilling machine.

7. A grinding device according to any one of Claims 2-6, characterised in that the lower end of the guide roller (31) driven by said drilling machine has a bearing pin that is received in a bearing on the base (40).

8. A grinding device according to any one of Claims 3-7, characterised in that the support plate (60) can be detached from the base.

9. A grinding device according to any one of Claims 3-7, characterised in that the support plate (60) can be moved to and from an operative position.