EP1687119A1

EP1687119A1 - Hand sanding tool

Info

Publication number: EP1687119A1
Application number: EP04798132A
Authority: EP
Inventors: Juszti Gyoergy
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2003-11-17
Filing date: 2004-11-02
Publication date: 2006-08-09
Also published as: WO2005049272A1; US20060172670A1; CN1882415A; DE10353682A1

Abstract

The invention relates to a hand sanding tool (10) with a sanding sheet (20), covering the underside (18) of the sanding plate and with clamping means (22, 24, 30), for fixing the sanding sheet (20) to the sanding plate (14), whereby the clamping means (22, 24, 30) comprise clamping bodies (24), pressing on the ends (21) of the sanding sheet, characterised in that the clamping body may be freely rotated about an eccentric axis (28) and the pivot axis (28) is arranged essentially perpendicularly above a concave curved retaining surface (22).

Description

Hand sanding tool

State of the art

The present invention is based on a hand grinding tool according to the preamble of claim 1.

According to GB patent application 232 2582, a hand-held grinding tool with a motor drive is known, which is provided with a system for tensioning and tightening a grinding sheet that can be held on the underside of the grinding plate. This system works reliably and is easy to use, but the tightening effect on the sanding sheet is relatively limited, so that a noticeable relative movement between the sanding sheet and the sanding plate cannot be ruled out.

Advantages of the invention

The invention with the features of claim 1 has the advantage that an inexpensive grinding hand tool has been created which, with simple means, enables highly effective clamping and at the same time effective tightening of the grinding sheet on the grinding plate, with a relative movement between the grinding blade and the grinding plate being so good as is excluded, whereby the fact that the pivot axis of the clamping body is arranged essentially perpendicularly above the clamping point on the upper side of the sanding plate above the holding surface and that the holding surface, which is spaced apart from the pivot axis, is curved, is a particularly long way of tightening the sanding paper given. Due to the fact that the clamping body is equipped as a cylindrical roller and the assigned area of the upper side of the sanding plate as a concave hollow cylindrical groove, when the clamping body is pivoted, the sliding sheet on the upper side of the sanding plate is initially pushed to a maximum possible tightening. When the sanding sheet is moved, the contact pressure between the clamping body and the holding surface of the sanding plate increases considerably, so that when the maximum clamping and locking force is reached while holding the sanding sheet end, there is at the same time a maximum material effect.

Because the clamping body is provided with a plastic tube as a friction lining, in particular carried by a metal core, a handy clamping body with a simple structure is created.

The fact that the metal core of the clamping body, in particular at both axial ends, holds a clamping lever in a rotationally fixed manner and secured against loss, in particular through radial and axial bores into which the clamping lever can be inserted or inserted, makes the clamping body particularly robust and capable to transfer high tightening or clamping forces securely and evenly to the sanding sheet.

The fact that the clamping lever, in particular with an end distant from the edge, can be locked in its clamping position in a spring-biased manner, does not release the clamping force on the sanding sheet.

Because the metal core has axial grooves on its circumference, into which the bent areas of the driver lugs can be inserted and run flush with the contour of the core, the driver levers are held particularly securely by the plastic tube pulled over the core.

The fact that the holding surface runs at an angle with respect to the swivel path of the clamping body, which is close to the self-locking, is a particularly safe one

Clamping of the sanding sheet possible with easy loosening.

Due to the fact that in the release position of the clamping body, there is a slot between the clamping body and the clamping surface, into which the end of the sanding sheet can be inserted under and / or on the clamping body, the abrasive flap can be clamped particularly securely. The fact that the holding surface, in particular concave, is gelled and runs at a distance of several millimeters to the outermost swiveling circle of the clamping body around the axis at the area of the sanding plate near the edge and intersects the swiveling circle in the area away from the edge is an advantage for the clamping body Stop created with which a secure clamping of the sanding sheet is possible. Characterized in that the Klemrnkö he has at least two, preferably circular, parallel to its axis and / or to the top of the grinding plate over the width of the clamping body eccentric cams, the radius of which is greater with respect to the axis than the distance between the axis and the, in particular straight and evenly running holding surface, the sanding sheet can then be tightened particularly securely after tensioning.

Characterized in that the clamping body, in particular its eccentric cam and / or the holding surface - at least partially - consist of elastically deformable material - the tensioning device can be automatically adapted to sanding sheets of different thicknesses to be tensioned.

Because a, in particular rounded, threshold is arranged on the front or rear edge of the sanding plate, via which the end of the sanding sheet can be guided such that it lies hollow between the threshold and the holding surface, it is after clamping by simply depressing the hollow one Area punishable.

Characterized in that between the front or rear edge on the upper side of the sanding plate there is a recess in the sanding plate into which the sanding sheet filled above can be pressed, the sanding sheet being elastically bridged, in particular by a leaf spring, after tensioning can be tightened by depressing its hollow area.

The fact that the leaf spring together with the sanding sheet can be pressed into the recess by means of the second eccentric cam means that it is reliably clamped at a further point in addition to tightening.

Because the second has a larger diameter than the first eccentric cam, it forms a rotary stop beyond which the clamp body cannot be rotated further and defines the clamping position of the clamp body. The fact that the first eccentric cam in the clamping position is at least two millimeters parallel to the vertical line extending from the swivel axis to the holding surface and that the eccentric cams are supported on the holding surface in the clamping position and thereby spread away from one another, make the clamping position clearly noticeably adjustable and only adjustable against releasably rests a resistance, so that unwanted loosening is excluded.

drawing

The invention is explained in more detail below on the basis of an exemplary embodiment with the associated drawing.

Show it

Figure 1 is a spatial representation of the hand grinding tool according to the invention

2 shows a detail of the hand grinding tool with the clamping means for grinding the sheet, FIG. 3 shows a spatial view of the detail according to FIG. 2 in the clamping position, FIG. 4 shows the view according to FIG. 3 in the open position

Figure 5 shows a further variant of the grinding sheet clamping device in the release position

FIG. 6 shows the grinding sheet clamping device according to FIG. 5 in the clamping position

7 shows a sanding plate with sanding sheet tensioning devices according to FIG. 5 and

8 shows the geometrical detail of a tension roller according to FIGS. 5 and 6.

Description of the embodiment

A hand-held grinding tool 10 - a hand-held orbital sander - shown laterally from the front in FIG. 1 has a housing 12, the upper region of which serves as a handle 13 and the lower region of which carries a grinding plate 14 which can be driven by a motor, to whose underside 18 a grinding sheet 20 can be attached. The sanding sheet 20 wraps around the front or rear edge 15, 17 of the sanding plate 14 with two opposite sanding sheet ends 21. The sanding sheet ends 21 each protrude a little parallel to the top 16 of the sanding plate 14 towards the center thereof. The grinding wheel ends 21 are tightened between a holding surface 22 on the top 16 and a tension roller 24 clamped. The tensioning roller 24 can be pivoted by means of a tensioning lever 30. The tensioning lever 30 extends from the tensioning roller 24 at an angle of 90 ° parallel to the longitudinal extension of the grinding plate 14. The end of the tensioning lever 30 can be pivoted upwards or counterclockwise in the tensioning position of the tensioning roller 24 in the direction of observation and in the tensioning position in an abutment 31 the upper side 16 elastically prestressed can be locked.

The abrasive sheet 20 has on its underside an abrasive layer 44 which, when the abrasive sheet 20 is inserted between the tensioning roller 24 and the holding surface 22, faces the tensioning roller 24 according to the direction of arrow 42. Due to the roughness of the

Abrasive layer 44 has particularly good adhesion when it comes into contact with the tensioning roller 24, so that when the tensioning roller 24 is pivoted into the tensioning position, the end of the sanding sheet 21 is pulled along with it and then securely clamped against loss. The sanding sheet 20 is tightened and secured against relative movement on the underside 18 of the sanding plate 14. The grinding stroke of the

Transfer sanding pads 14 to the sanding sheet 20 without slippage and with high efficiency. The removal rate during grinding is correspondingly high, whereby a consistently homogeneous grinding pattern is created that is almost independent of the contact pressure with which the hand-held grinding tool is pressed onto a workpiece to be machined.

FIG. 2 shows an enlarged section of the right side of the front area of the grinding plate 14. A bearing block 32 protrudes over the upper side 16 of the bearing plate 32, which receives a pivot axis 28 of the tensioning roller 24 with a central bore, which is not specified, about which it is pivotably mounted , Bent at a right angle to the pivot axis 28, a rigidly attached tensioning lever 30 emerges from the tensioning roller 24. In the tensioning position of the tensioning roller 24, it runs parallel to the longitudinal extension of the grinding plate and can be locked in place on a bearing block-like abutment 31 on the upper side of the grinding plate 16 so that it can be locked or spring-loaded. In this end position of the tensioning lever 30, the tensioning roller 24 is in its extreme left pivoting position, in which it bears against the holding surface 22 against the concave rising, stop-like pressing area 26 and thereby holds a sanding sheet stretched between the tensioning roller 24 and the holding surface 22.

In this tensioning position, the center of curvature 36 of the tensioning roller 24 has a position which is close to the center of the cooling center of the holding surface 22. The curvature fil 38 of the holding surface 22 corresponds essentially to the curvature radius 37 of the tensioning roller 24. The holding surface 22 lies in the swiveling circle of the tensioning roller 24 such that it forms a stop with the negative contour of the tensioning roller 24. As a result, a large surface area of the tensioning roller 24 bears against the holding surface 22 or the pressing area 26.

The front edge 15 of the sanding plate 14 lying on the right in the direction of observation is convexly curved in longitudinal section, so that an abrasive sheet 20 wrapped around it can slide over it relatively easily, without the risk of tearing.

The holding surface 22 extends from the front edge 15 to the pressing area 26 such that it forms an acute-angled slot 46 with respect to the swiveling circle of the tensioning roller 24. The sanding sheet 20 can enter into this slot 46 between the tensioning roller 24 and the holding surface 22 when the tensioning roller 24 has been pivoted upwards sufficiently in the counterclockwise direction about the axis 28 — in the release direction. Then will after

Insert the sanding sheet 20, the tensioning roller 24 pivoted clockwise about the axis 28 into its tensioning position, it first pulls the sanding sheet 20 over the holding surface 22 until it comes into contact with the pressing area 26 of the holding surface 22 and that Grinding sheet 20 securely tightened against losing. By tensioning and tightening the sanding sheet end 21 at the front and at the rear edge 15, 17 of the sanding plate 14, the sanding sheet 20 is tightened twice and secured against displacement relative to the underside 18 of the sanding plate. This enables slip-free grinding with a high degree of efficiency because a relative movement of the sanding sheet 20 with respect to the sanding plate 14 is excluded.

To remove the sanding sheet 20 from the sanding plate 14, the clamping lever 30 is laterally pivoted out of its locking position in the abutment 31 and further pivoted downward. The tensioning roller 24 moves counterclockwise with it, the slot 46 enlarging and finally the sanding sheet end 21 being released, so that the sanding sheet 20 can be easily removed.

FIG. 3 shows a spatial representation of the details of the front edge 15, which are essentially explained in relation to FIG. 2 - seen from the token side - which need not be explained again in every detail at this point. The tension roller 24 is in their Tensioned position pivoted, in which it clamps the sanding sheet end 21 of the sanding sheet 20 to the concave holding surface 22 and secures it against loss.

The tensioning roller 24 is connected in a rotationally fixed manner to an eccentric pivot axis 28 above the pressing area 26, the pivot axis 28 passing on both sides of the tensioning roller 24 into a tensioning lever 30 after being bent. The tensioning lever 30 can each consist of spring wire, so that the tensioning roller 24 presses the grinding wheel end 21 against the pressing area 26 in a spring-biased manner in its tensioning position.

FIG. 4 shows the same area of the grinding plate 14 with the tensioning roller 24 as in FIG

3 but in the "open" position in which the slot 46 between the holding surface 22 and the tensioning roller 24 is so large that the sanding sheet end 21 can easily be inserted far enough so that when the tensioning roller 24 is pivoted down it is carried away by it and via the Holding surface 22 - pushed to the right in the viewing direction - and finally clamped in its end position in the pressing area 26 of the holding surface 22. The tensioning levers 30 are directed vertically downward and hold the tensioning roller 24 in this position "open".

Figure 5 shows a further embodiment of a sanding plate 140 as a side view, which carries on its underside 180 a sanding sheet 200 running parallel thereto, which is looped with its sanding sheet end 210 around the front edge 150 of the sanding plate 140 and is guided over the top 160 thereof so that it is between the top 160 and the circumference of a partially cylindrical tensioning roller 54 is positioned. The tensioning roller 54 is mounted rotatably about an axis of rotation 280 in a bearing block 320, wherein it grips a suitable Jα-ice-shaped recess in the bearing block 320 with an axial ring collar 55 and serves as a bearing 310. On the circumference of the tensioning roller 54, two eccentric cams 56, 57 are arranged parallel to the axis 280 of the tensioning roller 54, the first eccentric cam 56 extending from the edge to the front edge 150 and a significantly lower eccentricity than the second eccentric cam located at the area of the tensioning roller 54 near the edge 57 has - measured in relation to the axis of rotation 280. The two eccentric cams 56, 57 are spaced apart from one another by a tooth gap 59.

The tensioning roller 54 can be pivoted by hand towards the sanding plate 140 into its tensioning position by means of a tensioning lever 60 pointing radially outwards to the front edge 150. The eccentric cam 56 remote from the edge first slides over the grinding blade end 210 and pulls it tightly to the right over the top 160 of the grinding plate 140 until the second eccentric cam 57 is pivoted down and is supported on the grinding blade end 210 or the top 160 of the grinding plate 140. Since the grinding wheel end 210 spans a threshold 64 which is partially cylindrical or rounded in cross section, it lies hollow between the threshold 64 and the first eccentric cam 56 until it presses the second eccentric cam 57 onto the top 160. By pressing the hollow sanding sheet area down by means of the second eccentric cam 57 onto the top 160 of the sanding plate 140, the sanding sheet 200 is pulled further to the right in the longitudinal direction and thus tightened noclxmally. It is assumed here that the sanding sheet end 210 positioned on the rear edge 170, which is not shown opposite the front edge 150, has previously been determined, because otherwise the tightening is nullified, ie when the opposite sanding sheet end yields.

FIG. 6 shows the tensioning roller 54 according to FIG. 5 in the “closed” position — in contrast to FIG. 5, which it shows in the “opened” position. The first eccentric cam 56 remote from the edge is positioned about 2 mm to the right of the axis of rotation 280 in the direction of observation, the second eccentric cam 57 near the edge being supported by the sanding sheet 200 or its sanding end 210 on the top 160 of the sanding plate 140. The second staging step is completed, in which the end of the sanding sheet 210 is pulled to the right and kept taut via the threshold 64 in the direction of observation.

The double tightening of the sanding sheet on both ends 150, 170 of the sanding plate 140 prevents relative movement between the sanding sheet 200 and the underside 180 of the sanding plate 140, so that when sanding the sanding plate 140 back and forth over a workpiece, particularly effective sanding is possible is possible.

The grinding plate 140 shown in FIG. 7 as a three-dimensional top view according to FIGS. 5 and 6 has the same, partially cylindrical tensioning roller 54 at both ends, the two of which

Tension levers 60 each face the front 150 or rear edge 170 and can be pivoted slightly downwards into the economy position by hand, in particular with the thumb. To release the sanding sheet 200, the tensioning levers 60 are to be pivoted upward in the direction of observation, so that the eccentric cams 56, 57 release a gap between the top 160 of the sanding plate 140 and the tensioning roller 54, from which the sanding sheet end 210 can be easily removed.

Fig. 8 shows a schematic cross section of a tensioning roller 54 pivoted into the tensioning position, in which the first eccentric cam 56 remote from the edge supports the grinding blade end 210 on the holding surface 62 of the top 160 of the grinding plate 140. Here, the eccentric cam 56 has a parallel distance 63 from the plumb line fell from the pivot axis 280 to the holding surface 260 of a few millimeters, so that a prestressed position of the

Tension roller 54 is effected. The tensioning roller 54 is made of elastic material. It is therefore possible to snap them on by resiliently deforming the first eccentric cam. It can also be advantageous if the holding surface 62 also consists of an elastically deformable material on which the grinding wheel end 210 or the two eccentric cams 56, 57 are supported. As a result, different sanding sheet thicknesses can be tightened regardless of their masses with the same holding security.

In the clamping position of the first eccentric cam 56, after it snaps over the holding surface 62, it builds up an elastic pretensioning force with which it presses the second eccentric cam 57 against the upper side 160 of the sanding plate 140, the abrasive disk end 210 being inserted into a recess 66 with precisely this pretensioning force presses down and thus additionally tightened. The recess 66 can be made with elastic means, e.g. Plastic or a leaf spring can be bridged.

Instead of an integrated in the chip roller 54, to the outside of the grinding plate edge 150,

170 pointing clamping lever 60, a clamping lever as shown in FIGS. 1 to 4 can be arranged, which in the clamping position points to the center of the grinding plate 140 and can be locked there by snapping.

Claims

Expectations

1. Hand-held grinding tool (10) with a sanding sheet (20) overlapping the underside of the sanding plate (18) and with clamping means (22, 24, 30) for fixing the sanding sheet (20) to the sanding plate (14), the clamping means (22, 24, 30 ) have clamping bodies (24) which can be pressed onto the grinding wheel ends (21), characterized in that the clamping body (24) is rotatably mounted about an axis (28) arranged essentially perpendicularly above a holding surface (22).

2. Hand grinding tool according to claim 1, characterized in that the clamping body (24) is designed as a, in particular cylindrical, roller, the holding surface (22) being designed as a cylindrical groove at least in a partial area.

3. Hand grinding tool according to claim 1 or 2, characterized in that the clamping body (24) has a friction lining on its circumference, in particular a plastic hose.

4. Hand grinding tool according to one of claims 1 to 3, characterized in that the clamping body (24) carries an angled clamping lever (30, 60), in particular flush with the, in particular made of metal, cylindrical core (25) rotatably and secured against loss.

5. Hand grinding tool according to one of the preceding claims, characterized in that an edge distal end of the clamping lever (30) in its clamping position is elastically biased, in particular latching, lockable.

6. Hand grinding tool according to one of the preceding claims, characterized in that the clamping lever (30) with the core (30) of the clamping body (24), inserted into radial and axial bores, is coupled.

7. Hand grinding tool according to claim 6, characterized in that the clamping body (24) has a clamping lever (30) at its axial ends.

8. Hand grinding tool according to claim 6 or 7, characterized in that the Klern body (24), in particular on its metal core (25), has radial and axial grooves into which the, in particular made of spring wire, clamping lever (30) flush with the Contour of the metal core (25) can be inserted and is coupled to the clamping body (24) in a rotationally fixed manner by means of the plastic hose (23).

9. Hand grinding tool according to claim 8, characterized in that in the release position of the clamping body (24) between this and the holding surface (22) there is a slot (46) in which the grinding wheel end (21). is plugged under and / or on the clamping body (24).

10. Hand grinding tool according to one of the preceding claims, character- ized in that the holding surface (22), in particular concave, is curved and to the outermost, about the axis (28) leading swiveling circle of the clamping body (24) at the edge area of the grinding plate (14 ) runs at a distance of several millimeters and intersects the swivel circle in the area distant from the edge.

11. Hand sanding tool (10), with a sanding sheet (20, 200) overlapping the underside (18, 180) of its sanding plate (14, 140) and with clamping means (24, 22, 54, 62) for clamping the sanding sheet (20, 200 ) on the grinding plate (14, 140), the clamping means (24, 22, 54, 62) having clamping bodies (24, 54, 56, 57) that can be pressed onto the grinding blade ends (21, 210), characterized in that the clamping body ( 54, 56, 57) at least two eccentric cams (56, 57), in particular round-shaped, parallel to its axis (28, 280) and / or to the top (160) of the grinding plate (140) over the width of the clamping body (24, 54) ), whose radius with respect to the pivot axis (28) is greater than the distance between the Pivot axis (28) and the holding surface (22, 62), in particular straight and level.

12. Hand grinding tool (10) according to one of the preceding claims, characterized in that the clamping body (24, 54), in particular its eccentric cam (56, 57) and / or the holding surface (22, 62) - at least partially - from elastically deformable material - adaptable to sanding sheets of different thicknesses to be tensioned.

13. Hand grinding tool (10) according to the preamble of claim 11, characterized in that a, in particular rounded, threshold (64) is arranged on the front or rear edge (150, 170) of the grinding disc (64), which ends the grinding wheel (21 ) positioned hollow between the threshold (64) and the holding surface (62).

14. Hand grinding tool (10) according to the preamble of claim 11, characterized in that the grinding plate (14, 140) between its front or rear edge (15, 17, 150, 170) on the top (16, 160) a recess (66) into which the sanding sheet (200) guided over it, particularly when the sanding sheet end (21) is fixed, can be pushed in, the depression being bridged, in particular by elastic means, preferably a leaf spring.

15. Hand grinding tool (10) according to one of the preceding claims, characterized in that the elastic means together with the grinding sheet (200) can be pressed into the recess by means of the second eccentric cam (57).

16. Hand grinding tool (10) according to any one of the preceding claims, characterized in that the second eccentric cam (57) forms a rotary stop, beyond which the clerical body (54) cannot be rotated further and which - measured between the pivot axis (280) and the End of the eccentric cam (57) - has a larger radius than the first eccentric cam (56).

7. Hand grinding tool (10) according to one of the preceding claims, characterized in that the first eccentric cam (56) in the clamping position of the clamping body (54) is arranged at least two millimeters in parallel in front of the perpendicular from the pivot axis (280) to the holding surface (62) and that the eccentric cams (56, 57) are supported on the holding surface (62) and spread apart.