GB2049796A - A Vibrating Abrader - Google Patents

Abstract

A vibrating abrader comprises a base plate (10), an abrasive paper (11), a clamping member (12) pivoted to the plate (10) and secured by a locking device (14) capable of locking it in its raised position releasing the abrasive paper (11) or in its gripping position. The locking device (14) includes a manually actuable two- position, latching control unit (18). The control unit (18) is so formed that, with each actuating stroke, the locking device (14) takes up its locking position or its unlocking position alternately and successively. <IMAGE>

Description

SPECIFICATION A Vibrating Abrader State of the Art The invention originates from a vibrating abrader according to the type set forth in the main claim. An abrasive paper holder or an abrasive paper clamping device is already known for such a vibrating abrader in which the locking device has a rising guide slot arranged on the clamping member provided with an end section extending substantially parallel to the abrasive plate and in which engages a hand lever retained on the abrasive plate by spring force and forced downwards. By moving the hand lever downwards in the guide slot and sliding it inwards into the substantially horizontal end section, the clamping member is removed from the abrasive plate and the locking device is transferred into its locking position.In this raised position of the clamping member, the ends of the abrasive paper overlapping the abrasive plate can be pushed between the surface of the abrasive plate and the clamping member. If the hand lever is then moved out of the horizontal end section of the guide slot then the locking device releases the clamping member. The clamping member is automatically pressed against the abrasive plate under the influence of its compression spring and thus rigidly clamps the ends of the abrasive paper.

With this arrangement of abrasive paper retention, the lever extends substantially parallel to the abrasive plate. So that it does not act as a troublesome part during a smoothing operation, it is countersunk in one end of the abrasive plate.

The disadvantage here is the bad suitability of the paper retention and the extremely unfavourable ergonomic arrangement of the hand lever. In this respect, it must be considered that the clamping member must press the abrasive paper against the abrasive plate with a relatively high spring pressure. This high spring pressure must be overcome by hand during the manual transfer of the clamping member into its raised position. This requires large adjustment forces which need to be applied to the lever and transmitted by the lever.

Thus, a hand lever which is pivotable in the plane of the abrasive plate or in a plane parallel thereto and which is also arranged countersunk in the abrasive plate, is extremely unfavourable from the ergonomic point of view. Also, such an abrasive paper retention is very expensive from the constructional and manufacturing point of view.

Advantages of the Invention As opposed to this, the vibrating abrader in accordance with the invention comprising the characterising features of the main claim has the advantage of simpler, easier and ergonomically better serviceability during clamping and unclamping of the abrasive paper. It is constructively relatively simply made and is cheap to produce from a manufacturing point of view.

Without impairing the favourable handling during clamping and unclamping of the abrasive paper, the vibrating abrader in accordance with the invention makes the use of relatively large pressure forces of the clamping member on the abrasion plate possible and with it a greater security of the abrasive paper retention; since the actuation of the two point adjuster directed away from the abrasive plate makes it possible for the operator to apply large actuating forces for overcoming the said clamping forces of the clamping member, without any trouble.

Advantageous further developments and improvements of the clamping regulator set forth in the main claim are made possible by the measures set forth in the sub-claims.

Drawing The invention is illustrated diagrammatically in a number of embodiments with the aid of the drawing and is described in detail in the following specification.

There are shown in: Figure 1 a perspective view of a vibrating abrader, Figure 2 a sectional side view of the abrasive plate, clamping member and locking device of the vibrating abrader according to a first embodiment.

Figure 3 a sectional and enlarged plan view in the direction of the arrow Ill in Figure 2, Figure 4 a sectonal side view of the abrasive plate, clamping member and locking device according to a second embodiment, Figure 5 a sectional and enlarged representation of an outline development of the switching and locking cams in Figure 4, Figure 6 a sectional side view of the abrasive plate, clamping member and locking device according to a third embodiment, Figure 7 a sectional and enlarged representation of an outline development of the locking and switching cams in Figure 6, Figure 8 a section along the line VIll-VIll in Figure 6, enlarged, Figures 9 and 10 each a sectional side view of the abrasive plate, clamping member and locking device according to a fourth and fifth embodiment, Figure 11 a sectional side view of the abrasive plate, clamping member and locking device according to a sixth embodiment, Figure 12 an enlarged representation of the detail XII in Figure 11.

Description of the Embodiments The complete vibrating abrader which can be seen in Figure 1 has an abrasive plate 10 the lower free surface of which can be covered by an abrasive paper 11. At its two ends the abrasive paper 11 is clampingly held against the abrasive plate 10 by means of a spring loaded clamping member 12. By means of a gripping plate 13 or gripping surface arranged on it, the clamping member can be manually moved out of a clamping position illustrated in Figure 1 in which the clamping member 12 forces the abrasive paper 1 1 against the abrasive plate 10 into a raised position illustrated in the other figures releasing the abrasive paper. Moreover, the vibrating abrader also has a locking device 14 for the clamping member 12 which can be transformed into a locking and unlocking position.

In its locking position, the locking device 14 retains the clamping member 12 in its raised position and in its unlocking position, releases the clamping member 12. The clamping member 12 automatically moves back into its clamping position under the influence of a compression spring 15 (Figure 2) and is pressed against the surface of the abrasive plate 10. In so doing, the clamping member 12 is pivotable about an axis 16 retained on the abrasive plate and on one side-with respect to the pivotal axis 16has a clamping stirrup 17 extending over substantially the entire width of the abrasive plate 10 pressing against the abrasive paper 11 and on the other side has the gripping plate 13.

The locking device 14 has a manually actuable automatically returning two-step control unit 18 having a direction of actuation directed away from and substantially perpendicular to the abrasive plate 10. The two-step control unit is so arranged and designed that with each actuating stroke, thus with each depression of the two-step control unit 18, the locking device 14 alternately and successively takes up its locking and unlocking position. Moreover, the two-step control unit 18 is so coupled to the clamping member 12 that an actuation of the clamping member 12-by exerting pressure on the gripping plate 13~also is or effects an actuation of the two step control unit 18. Thus, the gripping plate 13 of the clamping member 12 also forms part of the two-step control unit 18.

In the embodiment according to Figures 2 and 3, the locking device 14 has a clamping member 20 held against the abrasive plate 10 and a latch 21 connected to the clamping member 12 and associated with the said clamping member 20, and which are both movable relatively to each other. In this instance, the latch 21 forms a part of the two-step control unit 18. In this case, the clamping member 20 is formed as a catch 22 engaging behind the latch 21 in the locking position of the locking device 1 4. The two-step control unit 18 has two switching webs 23 and 24 arranged on the catch 22. The switching webs 23 and 24 act alternately and cooperate successively with the latch 21 and effect pivoting of the pivotally mounted catch 22 against the force of a return spring 25.For simplicity of construction, the catch 22 and switching webs 23 and 24 are arranged on a pivot plate 26, which is pivotally mounted in a recess 27 in the abrasive plate 10. Thus, the pivot plate 26 can be pivoted both in a plane lying parallel to the abrasive plate 10 and also in a plane perpendicular thereto. The latch 21 projects substantially perpendicularly from the clamping member 12 and indeed at the underside of the gripping plate 1 3 and extends through an elongate slot 28 in the abrasive plate 10 into the recess 27. Due to the pivotal movement of the lever-like clamping member 12, the end of the latch 21 is moved in the longitudinal direction of the elongate slot 28.The switching web 23 is so arranged on the pivot plate 26 that, on displacement of the latch 21 in the elongate slot 28, the pivot plate 26 is pivoted parallel to the abrasive plate 10 out of the dotted line position in Figure 3 into the full line position.

As soon as the latch 21 has left the switching web 23, the pivot plate 26 pivot back under the action of the return spring 25, the catch 22 engages behind the latch 21 and the locking device 14 takes up its locking position. The clamping member 12 is located in its raised position illustrated in Figure 2. The switching web 24 is tilted out of the plane of the pivot plate 26 thus out of the plane of the drawing in Figure 3. If the two-step control unit 18 is then actuated afresh and indeed so that the gripping plate 13 is forced towards the abrasive plate 10, then the latch 21 is displaced further in lhe elongate slot.

As soon as it takes up the left-hand dotted line position in Figure 3, the pivot plate 26 pivots somewhat further clockwise until the switching web 24 and the end of the latch 21 are in line with one another. In that manner, the locking device 14 takes up its unlocking position. On release of the gripping plate 13 and with it the two-step control unit 18, the compression spring 15 is expanded, the clamping member 12 moves automatically into its clamping position and the end of the latch 21 is moved in the elongate slot 28 towards the right in Figure 3. By means of the switching web 24 tilted out of the plane of the pivot plate 26, the pivot plate 26 is pivoted perpendicularly with respect to the plane of the drawing so that the catch 22 cannot engage the latch 21.

The embodiment according to Figures 4 and 5 is the same as the embodiment according to Figures 2 and 3 described above with respect to the references 10 to 18, so that in the following the same references are retained. Likewise, the locking device 14, as in the previously described embodiment, has a locking member 30 supported on the abrasive plate 10 and a pin-like latch 31 associated with the said locking member 30. The latch 31 is rigidly connected to the clamping member 12 and once again forms part of the twostep control unit 18. In this instance, the locking member 30 is formed as a cylindrical locking cam 32 which, at its end, has rests 33 uniformly distributed over the periphery with slotted recesses 34 lying therebetween. The rests 33 fix the latch 31, which extends substantially transversely with respect to the axis of the locking cam 32, whereas the slotted recesses 34 release the latch 31. In other words, the locking device 14 takes up its locking position when the latch 31 is located in a rest 33 and takes up its unlocking position when the latch 31 engages in a slotted recess 34.

The two-step control unit 18 also has a switching cam 35 cooperating with the latch 31 which is likewise cylindrical and is arranged coaxially with respect to the locking cam 32. The switching cam 35 has a sliding guide 36 cooperating with the latch 31 which extends at a distance from the rests 33 and the slotted recesses 34 of the locking cam 32 and extends opposite the latter. The sliding guide 36 is so constructed that, during actuation of the two-step control unit 18, the latch 31 is successively and alternately associated with a rest 33 and a slotted recess 34. The locking cam 32 and the switching cam 35 are rigidly connected to one another and are arranged on the abrasive plate 10 for rotation about their common longitudinal axis.The latch 31 rigidly connected to the clamping member 12 is orientated substantially transversely with respect to the longitudinal axis of the locking cam 32 and the locking cam 35 and projects between them.

In the raised position of the clamping member 12 illustrated in Figure 4, the latch 31 lies in a rest 33 (Figure 5) and the locking device 14 is located in its locking position. If the clamping member 12 is pivoted clockwise by pressure on its gripping plate 13, then the latch 31 which is thus displaced along the longitudinal axis of the locking cam 32 and the switching cam 35, strikes the sliding guide 36 and in this instance against an inclined shoulder 37. By means of this inclined shoulder 37, the locking cam 32 and the switching cam 35 are rotated together until the latch 31 arrives at the lowest point in the sliding guide 36. In this position, the locking device 14 takes up its unlocking position. If the gripping plate 13 is then released, then the clamping member 12 is reset anticlockwise under the influence of the compression spring 1 5.In so doing, the latch 31 slides into the slotted recess 34 which is made deep enough for the clamping stirrup 17 to be able to press against the surface of the abrasive plate 10 under spring pressure.

The side edges of the slotted recesses 38 are made slightly sloping so that when the latch 31 slides into a slotted recess 34, the locking cam 32 and the switching cam 35 are slightly rotated. In so doing, an inclined shoulder 37 on the sliding guide 36 once again lies opposite the latch 31.

With a fresh actuation of the gripping plate 13, the latch 31 once again engaging an inclined shoulder 37, displaces the locking cam 32 and the switching cam 35 in the direction of the arrow A in Figure 5 until the latch pin 31 once again lies opposite a rest 33. On releasing the gripping plate 13, the pin 31 then slides into the rest 33 and the locking device 14 is located once again in its locked position illustrated in Figure 4 in which it maintains the clamping member 12 in its raised position.

In the embodiment according to Figures 6 to 8, the components referenced 10 to 18 correspond to those of the previously described embodiment so that they have the same reference numerals.

As already described in respect of the embodiment according to Figures 4 and 5, in this instance, the locking device 14 also has a clamping member 40 supported on the abrasive plate 10 and a pin-like latch 41 associated therewith and rigidly connected to the clamping member 12, clamping member and the latch being movable relatively to one another. In this case, the latch 41 also forms part of the two-step control unit 18. The locking member 40 is formed as a hollow cylindrical locking cam 42 fixedly arranged on the abrasive plate 10. Once again, the locking cam 42 has rests 43 fixing the latch 41 in the locking position of the locking device 14 and which are uniformly distributed at the end over the periphery of the locking cam 42.

Between the individual rests 43, there are respective slotted recesses 44 which are deep enough for the latch 41 to be able to slide therein without it being blocked in its longitudinal movement.

The latch 41 is both part of the locking device 14 and a part of the two-step control unit 18. A switching cam 45 is likewise hollow cylindrical and is so arranged coaxially with respect to the locking cam 42 that the inclined shoulders 47 on its sliding guide 46 lie opposite the rests 43 and the slotted recesses 44 on the locking cam 42.

The switching cam 45 is also non-rotatably supported on the abrasive plate 10.

The latch 41 cooperating with the switching cam 45 is fixed to a switching pin 48, projecting transversely therefrom, arranged substantially coaxially with respect to the locking cam 42 and the switching cam 45 (Figure 8). The switching pin 48 is mounted on the clamping member 12 for rotation about its longitudinal axis and projects through the locking cam 42 far enough for the pin-like transversely projecting latch 41 to penetrate between the locking cam 42 and the switching cam 45.

In the raised position of the clamping member 12 illustrated in Figure 6, the locking device 14 is located in its locking position and the latch 41as can be seen in Figure 7-is fixed in a rest 43 by the locking cam 42. If the two-step control unit 18 is now actuated towards the abrasive plate 10, in this instance by brief pressure on the gripping plate 13 of the clamping member 12 against the action of the compression spring 15, then the switching pin 48 is displaced in a longitudinal direction and the latch 41 is moved downwards in Figure 7 until it strikes the inclined shoulder 47 of the sliding guide 46 on the switching cam 45. By further displacement of the switching pin 48 in an axial direction, the latch 41 is moved along the inclined shoulder 47 with rotation of the switching pin 48 up to the deepest point in the sliding guide 46.In this position of the latch 41, the locking device 14 is transferred into its unlocking position. If the gripping plate 13 is then released, the clamping member 14 pivots anticlockwise and the switching pin 48 is then moved in the opposite direction. In so doing, the latch 41 strikes a further inclined shoulder 49 which is arranged at the entrance to each slotted recess 44 in the locking cam 42. Due to this inclined shoulder 49, the latch 41 slides into the slotted recess 44 with rotation of the switching pin 48, without coming to rest therein. The clamping member 12 is pressed under the action of the compression spring 15 against the abrasive plate 10 and the abrasive paper 11 is rigidly clamped.An inclined shoulder 47 of the sliding guide 46 then lies opposite to the latch 41 ining in the slotted recess 44, so that with a fresh actuation of the two-step control unit 18~which causes the clamping member 12 to pivot clockwise by means of its gripping plate 13 and to thus transfer into its raised position-the latch 41 is so rotated after striking the said inclined shoulder 47 that it then lies opposite a rest 43 into which it then slides on release of the twostep control unit 1 8 or of the gripping plate 13 and takes up the position illustrated in Figure 7 once again.

The two embodiments according to Figures 9 and 10 correspond to the above-described arrangement with respect to the components referenced 10 to 18. In both embodiments, the locking device 14 has a clamping member 50 or 60 supporting the clamping member 12 against the abrasive plate 10 in the locking position. In the locking position of the locking device 14, the said clamping member 50 or 60 takes up a clamping fit between the abrasive plate 10 and the clamping member 12 whereas, in the unlocking position of the locking device 14, it passes into a dwell position.The clamping member 50 or 60 is provided with a certain mass and is so arranged on the abrasive plate 10 that, under the influence of gravity, it is urged to take up its clamping fit position-as illustrated in Figures 9 and 10-in a vertical or upwardly directed position of the abrasive plate 10 and is urged to take up its raised position in an horizontal or downwardly directed position of the abrasive plate 10. For this purpose, the clamping member 50 in the embodiment according to Figure 9 is pivotally mounted on the abrasive plate 10 in the form of a pivoting cam 51 having a certain mass whereas in the embodiment according to Figure 10 it (60) is formed as a heavy ball 61 which is maintained in a ball track 62.The longitudinal axis of the ball track 62 forms an acute angle with the abrasive plate 10 whereby the ball track 62 is inclined away from the bearing point of the clamping stirrup 1 7 on the abrasive plate 10. In both embodiments, the clamping member 50 or 60 is held clamped in the clamping fit by the clamping member 12 wherein, in the embodiment according to Figure 10, the clamping member 12 also has a shaped nose which, over a small region of the surface of the heavy ball 61, engages in a conforming manner.

In this case, the two-step control unit 18 is formed by the clamping member 12 together with the gripping plate 13 and the compression spring 1 5 and by the mass of the clamping member 50 or 60. A predetermined position of the abrasive plate 10 is associated with each actuation stroke of the two-step control unit 1 8, that is to say with each actuation of the clamping member 12 against the action of the compression spring 15.

In the locking position of the locking device 14 illustrated in Figures 9 and 10, the clamping member 50 or 60 is located in its clamping bearing position and maintains the clamping member 12 in its raised position. Since the clamping member 12 is forced by the compression spring 15 against the clamping member 50 or 60, the latter cannot leave its clamping bearing position in the horizontal position of the abrasive plate 10. After the abrasive paper 11 has been inserted, the gripping plate 13 of the clamping member 12 is pushed down briefly. In so doing, the clamping member 50 or 60 moves into its dwell position under the influence of gravity. In so doing, the inclined cam 41 pivots anticlockwise and the heavy ball 61 rolls in its ball track 62 towards the abrasive plate 1 0.If the clamping member 12 is then released, then it can pivot anticlockwise until the clamping stirrup 17 forces the abrasive paper 11 against the abrasive plate 10.

For transferring the locking device 14 into its locking position, the clamping member 12 must first of all be transferred into its raised position manually whereupon the gripping plate 13 must be moved towards the abrasive plate 10. Then the vibrating abrader must be so pivoted that the abrasive plate 10 is inclined upwards or vertical whereby the clamping bugle end of the clamping member 12 points upwards. The clamping member 50 or 60 again takes up its clamping bearing position under the influence of gravity. If the clamping member 12 is then released then the clamping member 50 or 6Q is rigidly held in its clamping bearing position. The locking device 14 is located in its locking position and fixes the clamping member 12 in its raised position.The vibrating abrader can then be pivoted back into the working position in which the abrasive plate 10 is horizontal (Figure 9 and Figure 10).

The embodiment according to Figures 11 and 12 corresponds to the above-described embodiments in respect of the components referenced by the reference numerals 10 to 18. In this case, the locking device 14 has a retaining pin 70 and a clamping piece 71 non-positively and/or positively engaging around the retaining pin 70 in the locking position of the locking device 14. The retaining pin 70 is arranged on the abrasive plate 10 projecting substantially perpendicularly therefrom. The clamping piece 71 is supported on the clamping member 12. A spring stirrup 72, which is a part of the two-step control unit 18, connects the clamping piece 71 to the clamping member 12 and is preferably fixed to the gripping plate 13. In this instance, the clamping piece 71 and the spring stirrup 72 are integral wherein the spring stirrup 72 has a recess 73 in the region of the clamping piece 71 through which the retaining pin 70 projects. The retaining pin 70 also has a notch 74 in which the spring stirrup 72. latches in the locking position of the locking device 14.

In this case, the two-step control unit 18 is formed by the clamping member 12 with the gripping plate 13 and the compression spring 15 and the spring stirrup 72. In the raised position of the clamping stirrup 12 illustrated in Figure 11, the locking device 14 takes up its locking position. For unlocking, the gripping plate 13 of the clamping member 12 must be forced against the action of the compression spring 15. Thus, due to the arrangement and formation of the spring stirrup 72, the spring stirrup 72 slides in the region of the clamping piece 71 out of the notch 74 and is displaced on the retaining pin 70 somewhat towards the abrasive plate 10. If the gripping plate 13 is then released, the clamping member 12 pivots anticlockwise. The clamping piece 71 of the spring stirrup 72 slides along the retaining pin 70 and over the notch 74 without latching therein. The clamping member 12 pivots until the clamping stirrup 17 is forced by the compression spring 1 5 against the surface of the abrasive plate 10.

If the clamping member 12 is to be transferred once again into its raised position then the gripping plate 13 has to be displaced once again towards the abrasive plate 10. In so doing, the clamping piece 71 of the spring stirrup 72 once again slides along the retaining pin 70 until it arrives at the notch 74 and snaps into the latter.

If, at this instant, the gripping plate 13 is released then the spring stirrup 72 latches in the notch 74 and the locking device 14 is located in its locking position.

Claims (20)

Claims

1. A vibrating abrader comprising an abrasive plate which can be covered with an abrasive paper, a spring loaded clamping member rigidly clamping the abrasive paper which can be transferred into a clamping position clamping the abrasive paper to the abrasive plate and into a raised position releasing the paper, and comprising a locking device which can be transformed into a locking and unlocking position and which, in its locking position, retains the clamping member in its raised position and in its unlocking position releases the clamping member, characterised in that, the locking device has a manually actuable self-resetting two-step control unit with an actuating direction directed towards the abrasive plate, preferably perpendicularly thereto, the spatial arrangement and formation of which is such that, with each actuating stroke, the locking device alternately and successively takes up its locking and unlocking position.

2. A vibrating abrader according to claim 1 characterised in that the two-step control unit is so coupled to the clamping member that actuation of the clamping member also effects actuation of the two-step control unit and vice versa.

3. A vibrating abrader according to claim 2 characterised in that the clamping member has a gripping plate or gripping surface serving for its actuation, which is part of the two-step control unit.

4. A vibrating abrader according to claim 3 characterised in that the clamping member is mounted on the clamping plate pivotable about an axis and on one side with respect to the pivotal axis-carries a clamping stirrup pressing against the abrasive paper and on the other side carries the gripping plate and that the locking device comprising the two-step control unit engages the clamping member and the abrasive plate on the gripping plate side.

5. A vibrating abrader according to one of claims 2 to 4 characterised in that the locking device has a locking member mounted on the abrasive plate and a latch connected to the locking member and associated therewith or vice versa, which are movable relatively to each other and that the latch is also part of the two-step control unit.

6. A vibrating abrader according to claim 5 characterised in that the locking member is formed as a locking hook engaging behind the latch in the locking position, that the two-step control unit has two switching webs for pivoting the locking hook or the latch and cooperating successively and alternately with the latch and arranged on the locking hook and that a return spring engages the locking hook or the latch.

7. A vibrating abrader according to claim 6 characterised in that the locking hook comprising the switching webs is arranged on a spring loaded pivot plate which is pivotable in a plane preferably lying substantially parallel to the abrasive plate and in a plane substantially perpendicular thereto against the force of a spring and preferably that the pivot plate is arranged on the abrasive plate and the latch is arranged on the clamping member.

8. A vibrating abrader according to claim 5 -characterised in that the locking member is formed as a locking cam with at least one rest rigidly supporting the preferably pin-like latch in the locking position and with at least one slotted recess releasing the latch and that the twostep control unit has a switching cam cooperating with the latch which has a sliding guide aligning a latch and a locking cam to each other and which is formed so that the latch is associated successively and alternately with the rest or the slotted recess.

9. A vibrating abrader according to claim 8 characterised in that the locking cam and the switching cam are made cylindrical whereby the rests and the slotted recesses or the sliding guide extend respectively uniformly over its periphery, that the locking cam and the switching cam are arranged coaxially at a distance from one another wherein the rests or the slotted recesses are facing the sliding guide and that the latch projects between the locking cam and the switching cam substantially transversely with respect to their longitudinal axis.

10. A vibrating abrader according to claim 9 characterised in that the locking cam and the switching cam are rigidly connected to one another and are arranged on the abrasive plate for rotation about the common longitudinal axis and that the latch is rigidly fixed to the clamping member.

11. A vibrating abrader according to claim 9 characterised in that the locking cam and the switching cam are made hollow cylindrical and are arranged on the abrasive plate, that the latch is fixed transversely projecting on a switching pin orientated substantially coaxially with respect to the locking and to the switching cams and projecting at least partially therethrough, and that the switching pin is retained on the clamping member rotatable about its longitudinal axis.

12 A vibrating abrader according to claim 2 or 3 characterised in that the locking device has a clamping member indirectly or directly supporting the clamping member against the abrasive plate and which, in the locking position of the locking device, takes up a clamping bearing position between the clamping member and the abrasive plate and in the unlocking position of the locking device takes up a raised position, that the twostep control unit has a gravity actuated mass on the clamping member and that a substantially vertical or a substantially horizontal position of the abrasive plate is associated alternately with each actuating stroke of the two-step control unit.

13. A vibrating abrader according to claim 12 characterised in that the clamping member is so arranged preferably on the side of the clamping stirrup that it is urged under the influence of gravity and due to the position of the abrasive plate inclined with respect to the horizontal, to take up its clamping bearing position and in a substantially horizontal position to take up its dwell position.

14. A vibrating abrader according to claim 12 or 13 characterised in that the clamping member is formed as a pivotal cam pivotally movable on the abrasive plate in the form of a member having a certain mass.

15. A vibrating abrader according to claim 12 or 13 characterised in that the clamping member is formed as a heavy ball which is retained in a ball track arranged on the abrasive plate and the longitudinal axis of which forms an acute angle with the abrasive plate.

16. A vibrating abrader according to claim 15 characterised in that the clamping member has a shaped nose retaining the heavy ball in the clamping bearing position over a small region of its surface, substantially positively.

17. A vibrating abrader according to claim 2 or 3 characterised in that the locking device has a retaining pin fixed to the abrasive plate and a clamping piece supported on the clamping member engaging around the supporting pin nonpositively and/or positively in the locking position of the locking device and that the two-step control unit has a spring stirrup connecting the clamping piece to the clamping member preferably by means of its gripping plate.

18. A vibrating abrader according to claim 17 characterised in that the clamping piece is integral with the spring stirrup and the spring stirrup has a recess matching the cross-section of the retaining pin and through which the retaining pin projects.

19. A vibrating abrader according to claim 17 or 18 characterised in that the retaining pin has a notch in which the clamping piece or the spring stirrup latches in the locking position of the locking device.

20. A vibrating abrader substantially as herein described with reference to Figures 1 to 3, Figures 4 and 5, Figures 6 to 8, Figure 9, Figure 10 or Figures 11 and 12 of the accompanying drawings.