EP0301269B1 - Grinding machine with dust sucking means - Google Patents

Description

The invention relates to a grinding device comprising a grinding tool which is driven to oscillate about a device-fixed pivot axis and a small pivot angle, which has a grinding surface with at least one corner area and which passes through at least one suction channel leading from a suction opening to a suction opening lying on a side facing away from the grinding surface is, wherein the suction opening is arranged outside the corner area.

Furthermore, the invention relates to a grinding tool for grinding devices with a drive shaft oscillating about a device-fixed pivot axis, which has at least one corner area and which is penetrated by at least one suction channel leading from a suction opening to a suction opening lying on a side of the grinding tool facing away from the grinding surface, the suction opening is arranged outside the corner area, in particular for a projecting grinder.

Such a grinding device and such a grinding tool are already known from PCT published patent application WO 87/02924. The grinding device disclosed in this publication with a dust extraction device comprises a triangular grinding tool, in which the suction opening is arranged in a corner region on the side opposite the grinding surface. Starting from this suction opening, an opening extends in the direction of the grinding surface to channels which are above the grinding surface, i.e. for example above the sanding paper, extend to an outer edge of the grinding tool and open into suction openings located on the outer edge. The suction openings are either on the outer edge of this corner area or approximately in the middle of the outer edge between two corner areas. In this grinding tool, the resulting grinding dust is only sucked in at the outer edge and reaches the suction opening via the channels and the opening, which is located in this corner region on the side of the grinding tool facing away from the grinding surface.

In this document, however, it was left open how further suction should proceed from the suction opening. In addition, the arrangement of the suction openings on the outer edge according to this document has the major disadvantage that the suction openings are not directed directly onto the grinding surface, so that on the one hand no direct suction effect is exerted on the grinding dust and on the other hand a large amount of so-called "false air" is sucked in , ie air that does not carry grinding dust.

In addition, the grinding dust must always be transported to the respective outer edges of the grinding tool in order to be able to be suctioned off from there, so that suction does not take place at the actual point of origin of the grinding dust.

Furthermore, EP 0 227 644-A has disclosed a swivel grinder with a suction device, in which the grinding dust is suctioned through openings in the grinding surface at the bottom. The openings open into a common channel, which is connected by an eccentrically arranged, flexible sleeve to a suction channel provided at the lower end of the drive unit.

The invention has for its object to improve a grinding device and a grinding tool of the type mentioned in such a way that an effective, reliable and in particular retrofittable dust extraction is possible with the simplest possible structure and without impairing the handling of the grinding device.

This object is achieved according to the invention in a grinding device of the type described at the outset in that a suction hood which can be fixed to the device is provided, which engages over the suction opening in all pivoting positions and allows the corner region of the grinding tool to protrude without a cover, and in that the suction hood faces one in and in relation to the grinding tool has pivoting invariant geometric surfaces lying sealing edge.

The design of the grinder according to the invention has the advantage that it is simple and reliable Problem of connecting a suction to the suction opening is solved, and that the arrangement of the suction opening in connection with the suction hood so that the free corner area protrudes further under the suction hood without any cover ensures that the handling of the grinder as such is not impaired . In addition, the solution according to the invention is characterized by its constructive simplicity.

The problem of a reliable seal between the suction hood and the grinding tool is solved according to the invention in that the suction hood has a sealing edge which faces the grinding tool and lies in geometric surfaces which are pivotally invariant with respect to it. This means that the sealing edges lie on those geometric surfaces that do not change their position due to the pivoting movements of the grinding tool. This would also be, for example, a circular cylinder surface around the pivot axis. However, in order not to make the grinding tool, which is a wearing part, unnecessarily complicated, the simplest solution provides that the sealing edges lie in a plane perpendicular to the pivot axis.

In the embodiment according to the invention described above, it is not determined how the suction hood should overlap the grinding tool outside the corner area. It would be conceivable, for example, that the suction hood also overlaps an outer edge of the grinding tool in order to avoid sealing problems between the suction hood and the grinding tool, at least in some areas. However, this would have the disadvantage that the outer edge of the grinding tool cannot be used for grinding edges, which means a significant advantage in the grinding device according to PCT publication WO 87/02924. For this reason, it is expedient if the suction hood overlaps the grinding tool in all pivot positions within its outer edges.

A particularly advantageous embodiment of the solution according to the invention provides that the suction hood overlaps the grinding tool in a radial direction pointing from its pivot axis to the corner region projecting without cover, at most approximately two thirds of its maximum extent in this direction, it even being desirable that the Suction hood only grips over the grinding tool in this direction up to half of the maximum extent in order to affect the handling of the grinding tool even less.

Especially for reasons of space saving, which plays a considerable role in the dust extraction device according to the invention, it is expedient if the sealing edge runs around all the pivoting positions of the suction openings at a small distance.

In the context of the solution according to the invention, however, it is often necessary to arrange not only one but several suction openings on the grinding tool. For this reason it is provided that the suction hood overlaps several suction openings of the grinding tool, in which case it has proven to be advantageous if the sealing edge wraps around the suction openings together.

The grinder according to PCT laid-open specification WO 87/02924 shows that the suction hood is as possible must be designed to be space-saving and on the other hand to solve the problem of the suction line without impairing the advantages of the device described in this document, which can be seen in the fact that one can advantageously work with the corner area of the grinding tool and the other edge grinding should also be possible with the lateral outer edges of the grinding tool. For this reason it is provided that the suction hood has an annular chamber located above the suction openings, into which a suction nozzle opens laterally at a small distance above the sealing edge. Such a lateral arrangement of the suction nozzle provided directly above the sealing surfaces leads to an extremely space-saving construction in the direction of the pivot axis. Above all, any other arrangement of the suction nozzle would significantly impair the handling of the grinding tool.

A very cost-effective design of the suction nozzle provides that it is integrally formed on the suction hood.

Despite the advantages of this suction nozzle arranged in this way, there is still the problem of how to lead a suction feed line to the suction nozzle in the best possible form. For this reason, it is advantageous if, in the case of a grinding device with a housing that extends in the radial direction away from the pivot axis, the suction nozzle extends along an underside of the housing. Such a design of the suction nozzle allows optimal handling of the grinding device according to the invention, without impairing the possible uses without a dust extraction device.

In such grinders, the housing itself usually serves as a handle for the grinder, so that the handiness of this device can be improved even more if the suction nozzle rests on the underside of the housing and there is no space between the suction nozzle and the underside of the housing. It is even more advantageous, however, if the suction nozzle, with its upper wall facing the housing, is adapted to a surface of the underside of the housing and thus bears over the entire surface of this housing and virtually forms a unit with the housing.

In particular when the housing itself serves as a handle, it has proven to be advantageous if the housing has an approximately cylindrical shape and the suction nozzle has an approximately inverted trapezoidal cross section.

A suction hose is usually connected to the suction nozzle. For this reason, it is advantageous if the suction nozzle extends beyond a housing end opposite the pivot axis, so that the suction hose can only be connected to a section of the suction nozzle protruding beyond the housing end. For this purpose, it has proven to be advantageous if the suction connection has a suction connection connection in its area extending beyond the housing end.

In the preferred embodiment of the solution according to the invention described above, it has proven expedient if the suction nozzle is held on the housing with a bracket in the region of the housing end, so that rotation of the suction nozzle relative to the housing is prevented due to tensile forces exerted by the suction hose is.

The embodiment of the suction hood according to the invention described above is not necessarily universally applicable for different types of housings. For this reason, a universally applicable embodiment of a grinder with a housing extending in the radial direction away from the pivot axis provides that the suction nozzle protrudes from the annular chamber in an approximately radial direction relative to the housing and is connected to a manifold. However, this embodiment has the disadvantage that the suction nozzle on the side on which it protrudes represents a certain disability.

For this reason, it is advantageous if the suction nozzle protrudes from the annular chamber in an approximately radial direction and is connected to a bend to which the suction line can then be connected.

This fixed manifold ensures in a simple manner that the suction line does not affect the working area when working.

In order to make the suction hood with the suction nozzle and the manifold suitable for right-handed as well as left-handed people using the grinder, it is provided that the manifold can be connected to the suction nozzle in at least two positions, in each of which a manifold opening points in opposite directions. Thus, the suction hood can be attached to the grinding device in such a way that the suction nozzle protrudes to the left or the right side and the manifold is arranged in such a way that its manifold opening points away from a front, in particular from the front corner area of the grinding tool. The suction line can then be connected to these manifold openings in a simple manner.

In the space-saving design of the suction hood, the next problem is the attachment of the suction hood to the grinder. It has proven to be advantageous if the suction hood on its side facing away from the grinding tool carries an integrally formed mounting flange above the annular chamber, so that simple assembly is possible without a large additional height.

The formation of the mounting flange as a cylindrical approach with a clamping element is preferred not only because of its constructive simplicity, but also because it allows the suction hood to be rotated relative to the grinding tool after the clamping element has been released and Thus, depending on the use, the suction nozzle can be rotated relative to the grinding tool, so that, for example, it is easy to switch between the position of the suction nozzle that is favorable for right-handed and left-handed users.

Since a certain amount of space must also be provided for the clamping element, but based on the construction described so far, the arrangement of the clamping element should not constitute an additional hindrance to the handling of the grinding device, it has proven to be expedient if the clamping element is arranged in the area of the suction nozzle is, so that any rotation of the suction nozzle, at the same time a moving away of the possibly also obstructing clamping element results.

A seal between the sealing edges of the suction hood and the grinding tool is usually necessary in order to avoid an excessive loss of suction between the sealing edges and the grinding tool. There is also the risk that whistling noises will occur between the sealing edges and the grinding tool if only a sealing gap is provided. For this reason, an advantageous embodiment provides that the sealing edge has a receptacle for a sealing ring made of sliding sealing material. This sealing ring should only be placed in this receptacle and consist of a material that is both on the sealing edges of the Suction hood and on the sealing surfaces of the grinding tool opposite the sealing edges glide easily.

Instead of a sealing ring loosely inserted into a receptacle, a simplified embodiment provides that the sealing edge is coated with a sliding sealing material, i.e. the sealing edges carry a material that can slide easily on the sealing surfaces of the grinding tool opposite them.

In addition, it is desirable that the sliding material be elastic to compensate for differences in tolerance.

Felt has proven to meet these requirements because it has sufficient elasticity and also slides easily on the usual materials used for the sealing edges and sealing surfaces.

In a modification of the seal described above between the sealing edges and the grinding tool, it is also conceivable to provide a rubber seal or a seal made of a foam material as an additional sealing element, the relative movement between the sealing edges and the grinding tool occurring during the oscillating pivoting movements being due to the elasticity of the material as such can be compensated, so that this material is tight or subject to only slight displacements both on the sealing edges of the suction hood and on the grinding tool and due to its elasticity compensates for the relative movements with the small swivel angles inherent in this device.

The task with regard to the grinding tool is achieved according to the invention in a grinding tool of the type described in the introduction in that the suction opening is arranged in the grinding surface of at least one corner region and that the suction opening is surrounded by a sealing surface lying in a pivotally invariant geometric plane.

In contrast to the prior art, in which the suction openings are on the outer edge of the grinding tool, the solution according to the invention provides that the suction opening lies in the grinding surface, i.e. that the grinding surface formed, for example, by an abrasive paper has this suction opening. In addition, the suction opening is arranged in the corner region of the grinding tool according to the invention, since this corner region generally has the greatest distance from the pivot axis and therefore the greatest material removal rate occurs in this region. This arrangement of the suction opening thus removes it directly in the area in which the greatest amount of grinding dust is produced. Furthermore, the grinding tool according to the invention has the additional advantage that, as explained in detail above, it allows the extraction hood to be designed which does not or only insignificantly affects the handling of the grinding device equipped with such a dust extraction device.

According to the invention, a seal between the sealing edges of the suction hood and the grinding tool is ensured in that the suction opening is surrounded by a sealing surface lying in a pivoting invariant geometric surface, ie the sealing surface should also lie on a geometric surface which does not change its position with respect to the grinding device when the swiveling movements of the grinding tool are carried out. Advantageously, this will also be a surface or plane running perpendicular to the swivel axis, since in this embodiment the sealing surface can be identical to the surface of the grinding tool in the simplest case.

In the embodiment described above, the suction opening could in principle still be in different planes. However, since the grinding tool is a wearing part that has to be replaced frequently, it should also be as simple as possible. For this reason, it is advantageous if the suction opening is arranged in a surface of the grinding tool that is opposite the grinding surface and perpendicular to the pivot axis.

In order to be able to design the suction hood dependent on the position of the suction opening as space-saving as possible, it has proven to be expedient if the suction opening is arranged at a small radial distance from the pivot axis. An embodiment is preferred in which the suction openings extend in the radial direction to the pivot axis up to at most half the maximum radial extent of the grinding tool.

Another advantageous solution provides that the suction opening is arranged offset from the corner region by an angle of rotation with the pivot axis as the axis of rotation. With this arrangement, an even greater distance is reached between the corner region in which the suction opening lies and the suction opening, so that further advantages with regard to the design of the suction hood are achieved.

Just as with the formation of the sealing edges, it can be advantageous if the sealing surface has a receptacle for a sealing ring made of sliding sealing material.

However, it can also be provided in another, somewhat simpler and in many cases sufficient embodiment of the grinding tool according to the invention that the sealing surface is provided with a sliding sealing material, it being advisable for production-related and cost reasons that the sliding sealing material is applied as a coating on the sealing surface . The embodiments with the sliding sealing material firmly attached to the sealing surfaces additionally have the great advantage that the sliding sealing material is inevitably renewed when the grinding tool, which is a wearing part, is replaced, and thus the sliding sealing material as such is not exposed to long-term and therefore high stresses is, so that the sliding seal material does not have to have a long service life and can therefore be chosen simply and inexpensively.

A fiber or felt material can be used as a sliding seal material.

In the embodiment of the grinding tool according to the invention described above, a suction opening was initially assumed. However, it is also possible for a plurality of suction openings to be provided, these suction openings then advantageously being surrounded by a common sealing surface.

Only elongate suction channels are known from the prior art. In a preferred embodiment, however, it is provided that the suction channel is a ring channel connecting the suction openings and running in the grinding tool, it having proven to be additionally advantageous if the course of the ring channel is adapted to an outer contour of the grinding tool and runs at a distance from its outer edges .

The ring channel mentioned in the exemplary embodiments described above is preferably to be understood as an annular channel which runs around a central recess for a tensioning element and without being connected to it. This is due to the fact that in the central area of the grinding tool the removal rate is low and a connection to the central recess would only result in an additional intake of air without one significant removal of grinding dust.

When the grinding tool is constructed in accordance with PCT laid-open specification WO 87/02924, it is advantageous if the ring channel has a substantially U-shaped cross section and runs directly under a cover plate of the grinding tool in an elastic layer. For reasons of stability, such a structure has proven to be more expedient than the structure described in this laid-open publication, since due to the elastic layer being adhesively bonded to the cover plate, the ring channel has only an insignificant impairment, in particular the service life, of such a grinding tool.

In the embodiment explained so far, it was only assumed that the grinding tool in the corner region has a suction opening arranged in the grinding surface. An additional improvement can be achieved in that further suction openings are provided in the grinding surface at a distance from its outer edge and along it, so that all of the grinding dust arising in the outer region of the grinding tool is removed.

In particular in connection with the ring channel, it has proven to be particularly expedient if the suction openings, as seen in the direction of the pivot axis, are arranged over the entire surface of the ring channel, so that starting from the ring channel in the direction of the intake openings, only a breakthrough running parallel to the swivel axis is necessary and therefore no additional detour lines are required.

For the same reasons, it is advantageous if the suction openings, as seen in the direction of the pivot axis, are arranged so as to be completely covered by the ring channel, so that overall a very simple and effective air guidance is possible from the suction openings via the ring channel to the suction openings, which on the one hand is necessary in order to achieve sufficient suction power and on the other hand is required to prevent grinding dust from settling in the airways of the grinding tool.

An advantageous arrangement of the suction openings, in particular outside the corner area, can also be achieved in the embodiment described above, namely in that the suction openings are arranged in the areas of the ring channel closest to the pivot axis.

In all the exemplary embodiments described so far, it has been assumed that the grinding tool has at least one corner region. However, grinding tools with two or three corner areas are preferred, since these grinding tools offer the advantage that after the grinding surface has been worked off, the grinding tool is rotated in one corner area and continued to be used with the second corner area or with the other corner areas which have not yet been used or have not been used extensively can be. For this reason, it has also proven to be advantageous if the grinding tool is designed to be triangular and has a two- or three-fold axis of symmetry with regard to its shape and the arrangement of the suction and suction openings, that is to say that this grinding tool has a shape and the arrangement of the suction and suction openings with respect to a rotation through 180 ° or 120 ° is symmetrical and thus a corner area other than the front corner area can be used in a simple manner simply by rotating the grinding tool.

Fig. 1

einen Schnitt durch ein Schleifgerät, ausgerüstet mit einer erfindungsgemäßen Staubabsaugvorrichtung;

Fig. 2

eine Draufsicht von unten auf eine erfindungsgemäße Absaughaube;

Fig. 3

einen Schnitt längs Linie 3-3 in Fig. 2;

Fig. 4

einen Teilausschnitt des Bereichs A in Fig. 1 bei einem zweiten Ausführungsbeispiel;

Fig. 5

einen Teilausschnitt entsprechend Fig. 4 bei einem dritten Ausführungsbeispiel;

Fig. 6

einen Teilausschnitt entsprechend Fig. 4 bei einem vierten Ausführungsbeispiel;

Fig. 7

einen Teilausschnitt entsprechend Fig. 4 bei einem fünften Ausführungsbeispiel

Fig. 8

einen Teilausschnitt entsprechend Fig. 4 bei einem sechsten Ausführungsbeispiel;

Fig. 9

einen Schnitt längs Linie 9-9 in Fig. 1;

Fig. 10

eine Draufsicht längs Linie 10-10 in Fig. 1;

Fig. 11

eine Draufsicht entsprechend Fig. 10 bei einem siebten Ausführungsbeispiel und

Fig. 12

einen Schnitt entsprechend Fig. 9 bei einem achten Ausführungsbeispiel;

Fig. 13

eine Draufsicht ähnlich Fig. 2 bei einem neunten Ausführungsbeispiel;

Fig. 14

einen Teilschnitt durch ein zehntes Ausführungsbeispiel;

Fig.15

eine Ansicht in Richtung des Pfeiles B in Fig. 14.

Further features and advantages of the solution according to the invention are the subject of the following description and the drawing of some exemplary embodiments. The drawing shows:

Fig. 1

a section through a grinder equipped with a dust extraction device according to the invention;

Fig. 2

a plan view from below of an exhaust hood according to the invention;

Fig. 3

a section along line 3-3 in Fig. 2;

Fig. 4

a partial section of area A in Figure 1 in a second embodiment.

Fig. 5

a partial section corresponding to Figure 4 in a third embodiment.

Fig. 6

a partial section corresponding to Figure 4 in a fourth embodiment.

Fig. 7

a partial section corresponding to FIG. 4 in a fifth embodiment

Fig. 8

a partial section corresponding to Figure 4 in a sixth embodiment.

Fig. 9

a section along line 9-9 in Fig. 1;

Fig. 10

a plan view taken along line 10-10 in Fig. 1;

Fig. 11

a plan view corresponding to FIG. 10 in a seventh embodiment and

Fig. 12

a section corresponding to Figure 9 in an eighth embodiment.

Fig. 13

a plan view similar to Figure 2 in a ninth embodiment.

Fig. 14

a partial section through a tenth embodiment;

Fig. 15

a view in the direction of arrow B in Fig. 14th

Fig. 1 shows in detail a grinding device designated as a whole by 10, comprising a motor 12 and a gear 14 for oscillating drive of a pivot shaft 16 with a pivot axis 18, with a grinding tool 22 through a in a central recess on a connecting flange 20 of the pivot shaft 21 of this clamping element 23 is held in a rotationally fixed manner. The characteristics of this grinding device essentially correspond to the grinding device according to PCT laid-open specification WO 87/02924.

The grinder 10 is additionally provided with a dust extraction device, which comprises a suction hood 24, which is shown in FIGS. 2 and 3 as a separate part. The suction hood 24 comprises a hood part 26 with a cylindrical wall 28 which encloses an annular chamber 30. A free edge area of the cylindrical wall 28 is designed as a sealing edge 32. On the side of the cylindrical wall 28 opposite the sealing edge 32, a cylindrical extension 34 is formed on the hood part 26 and is aligned coaxially with the cylindrical wall 28. An interior 36 of the cylindrical extension 34 merges into the annular chamber 30.

To hold the suction hood 24 on the gear 14 of the grinding device 10, the latter has a cylinder piece 38 surrounding the pivot shaft 16 and extending over a short distance along the pivot shaft 16 in the direction of its connecting flange 20. The suction hood with its cylindrical extension is on this cylinder piece 38 34 can be placed in such a way that the cylinder piece 38 lies in the interior 36 to form a snug fit with the cylindrical extension 34. The cylindrical projection 34 and the cylindrical wall 28 of the hood part 26 are thus aligned coaxially with the pivot shaft 16 and this pivot shaft 16 passes through both the interior 36 of the cylindrical projection 14 and the annular chamber 30 of the hood part 26.

On one side of the hood part 26, a suction nozzle 40 is formed on the cylindrical wall 28, which extends from the cylinder wall 28 in the radial direction to the pivot axis 18. A longitudinal central axis 42 of the suction nozzle 40 is preferably inclined at an angle with respect to a plane 44 formed by the sealing edges 32, so that the suction nozzle 40 stands out from the plane 44 with increasing extension.

A manifold 48, which has a manifold opening 50, is placed on the suction nozzle 40, spanning a nozzle opening 46 of this suction nozzle 40. The elbow opening 50 lies in a plane which is approximately perpendicular to a plane which is passed through the nozzle opening 46.

The suction nozzle 40 is expediently shaped in such a way that the elbow 48 can be plugged into two positions, each rotated by 180 °, so that the elbow opening 50 in FIG. 2 can point upwards or downwards once.

For the additional fixation of the cylindrical extension 34 of the suction hood 24 forming a snug fit with the cylinder piece 38, a fixing screw 52 is also provided, which is preferably arranged on a side of the suction nozzle 40 opposite the plane 44 and above it. The fixing screw 52 penetrates the cylindrical neck 34 with its threaded piece 54 and thus allows the cylindrical neck 34 to be braced with the cylindrical piece 38.

In order to ensure the best possible suction from the annular chamber 30 with the largest possible cross-section, the suction nozzle is arranged in such a way that it opens directly above the sealing edges 32 into the cylindrical wall 28 with a cross-section which is approximately the same height as the annular chamber 30 above the sealing edge 32 corresponds.

The plane 44, in which the sealing edge 32 lies, is arranged according to the invention in such a way that it is perpendicular to the pivot axis 18 and can therefore be referred to as a pivot-invariant plane, since a pivoting movement of the pivot shaft 16 and the grinding tool 22 about the pivot axis 18 determines the relative position the plane 44 to the pivot axis 18 and to the gear 14 of the grinding device 10 is not changed.

A groove 56, which is open to the grinding tool 22 and the annular chamber 30, is expediently machined into the sealing edge 32 and is provided for receiving a freely insertable sealing ring 58. This sealing ring 58 is preferably made of a sliding seal material, i.e. Made of a material that on the one hand has a certain elasticity and on the other hand glides easily on other materials with a smooth surface. In this case, a sealing ring 58 made of felt is particularly intended.

This sealing ring 58 establishes a more or less airtight connection between the sealing edge 32 and a cover plate 60 of the grinding tool 22 lying parallel to the plane 44. This cover plate 60 is preferably made of sheet metal.

However, the seal between the sealing edge 32 of the suction hood 24 and the cover plate 60 of the grinding tool 22 can also be released in another way. For example, in FIG. 4 there is only a narrow air gap between the sealing edge 32 of the cylindrical wall 28 and a sealing surface 74 opposite this provided on the cover plate 60. Such a seal is possible because the cover plate 60 is non-rotatably braced with the connecting flange 20 of the pivot shaft 16 and is therefore aligned parallel to the plane 44. A further modification of the embodiment according to FIG. 4, shown in FIG. 5, provides a labyrinth seal between the cover plate 60 and the sealing edge 32. For this purpose, a U-shaped groove 62, which is open towards the grinding tool 22 and into which a projection 64 held on the cover plate 60 protrudes, must be incorporated into the sealing edge 32. This projection 64 can be made of different materials. It would also be possible to produce the projection 64 from an elastic material that preferably slides easily in the groove 62.

Further embodiments of the seal between the cover plate 60 and the sealing edge 32 according to FIGS. 6 and 7 provide an O-ring 66 between the cover plate 60 and the sealing edge 32, the sealing edge 32 preferably having a recess 68 for receiving the O-ring . This O-ring can now be arranged freely between the cover plate 60 and the sealing edge 32, but it can also be glued to the cover plate 60 or, as shown in FIG. 7, received in a further depression 70 in the cover plate 60.

A simple and very practical solution is shown in Fig. 8. In this case, the cover plate 60 is provided with a layer of a sliding sealing material 72, which is preferably a fibrous material. This layer 72 can be used in the manufacture of the grinding tool Apply in a simple manner to the cover plate 60 and can cover the cover plate 60 completely or can only be applied to the cover plate 60 in the region of a sealing surface 74 opposite the sealing edge 32, as shown in FIG. 8.

The grinding tool 22, as shown in FIG. 1, shows, in addition to the cover plate 60, which is non-rotatably clamped to the connecting flange 20, an elastic layer 76, preferably made of foam rubber, held thereon under the cover plate, and a Velcro adhesive layer 78 arranged under the elastic layer 76. on which the abrasive paper 80 forming a grinding surface is held.

In this elastic layer 76, an annular channel 82 is preferably incorporated on its side facing the cover plate 60, which for the sake of simplicity has an approximately rectangular cross section and expediently runs longitudinally and at a distance from an outer edge 84 of the grinding tool 22. With a uniform cross section, outer boundary surfaces 86 and inner boundary surfaces 88 of this ring channel 82 thus run parallel to the outer edge 84 and thus into corner regions 90 of the triangular grinding tool shown in FIG. 9.

Since the greatest amount of grinding dust arises in the corner regions 90 during a grinding process, it is necessary for the annular channel 82 in each of the corner regions 90 to have an opening 92 through the elastic layer 76 to the Velcro adhesive layer 78 and through this and through the sanding paper 80 to a suction opening 94, from which the resulting sanding dust can be sucked into the ring channel 82.

In addition, breakthroughs 98 leading to further suction openings 96 can also be provided between the respective corner regions 90 along the remaining course of the annular channel 82.

The suction openings 94 and the openings 92 preferably have a smaller cross section than the suction openings 96 and the openings 98, since a greater suction effect should be present in the corner regions than between them.

Furthermore, there is the possibility, starting from the ring channel 82, to provide channels 100 which run obliquely in the direction of the Velcro adhesive layer in the direction of the outer edge 84 and which open into suction openings 102 located on the outer edge 84 above the Velcro adhesive layer.

The connection between the annular chamber 30 in the suction hood 24 and the annular channel 82 in the elastic layer 76 takes place via suction openings 104 arranged in the cover plate 60, which can be seen in the top view of the cover plate 60 according to FIG. 10. In the exemplary embodiment according to FIG. 10, these suction openings 104 are bores which are arranged exactly above the ring channel 82 in the elastic layer 76 and have a diameter which is approximately equal to the width of the ring channel 82. These suction openings 104 are preferably not arranged in the cover plate 60 facing the respective corner regions 90, but rather are rotated relative to the latter by an angle with respect to the pivot axis 18. In the embodiment shown in FIG. 10, this angle of rotation is 60 °, so that the suction openings 104 each lie between the corner regions.

The result of this position of the suction openings 104 is that they can be arranged at the smallest possible distance from the pivot axis 18 and are also connected directly to the annular channel 82.

In a modification of the exemplary embodiment according to FIG. 10, the suction opening 104 can be replaced by three bores lying next to one another at the same location or, according to the exemplary embodiment, drawn in FIG. 11, by an opening over the entire width of the annular channel 82, which according to the invention has a longitudinal extension of the annular channel 82 up to the annular sealing surface 74, which in turn lies opposite the circular sealing edge 32.

A further exemplary embodiment shown in FIG. 12 shows, in a modification of the exemplary embodiment according to FIG. 9, a further possibility of forming the annular channel 82 ', which likewise, as also shown in FIG. 9, has no connection to the central recess 21'. The shape of the annular channel 82 'is also triangular in adaptation to the triangular shape of the grinding tool 22', although, according to the invention, the outer boundary lines 86 'as connecting lines between the corners can be straight or even to improve the stability towards the central recess 21'. Furthermore, the suction openings 104 'indicated by dashed lines are arranged close to the inner boundary surfaces 88', which in this case are circular cylindrical.

As can be seen in Fig. 13 in plan view, the suction hood 24 does not necessarily have a circular sealing edge 32, which inevitably results in annular sealing surfaces 74 on the cover plate 60. It is also possible that the suction hood 24 ', as shown in Fig. 13, has a sealing edge 32' with an approximately trapezoidal cross-section, wherein the pivot axis 18 passes through the suction hood 24 'in cross-section, so that a front wall 28' the cover plate only reaches up to at most half of their maximum extent in the direction of the front corner area 90 '. In this embodiment of the solution according to the invention, care must be taken to ensure that the sealing edge 32 'of the suction hood 24' in all pivoted positions of the grinding tool 22 'lies within its outer edge 84'.

A tenth exemplary embodiment, shown in FIG. 14, is identical to the above with regard to the arrangement and design of the swivel shaft 16 and the grinding tool 22 and the suction hood 24, except for the design and arrangement of the suction nozzle 40. The same parts are therefore provided with the same reference numerals and are no longer described separately.

In contrast to the exemplary embodiment according to FIG. 1, a suction nozzle 110 is formed on the suction hood 24, which extends along an underside 112 of a housing 114 via a housing end 116 and carries a hose connection nozzle 118 in an area projecting beyond the housing end 116.

As shown in Fig. 15, the housing 114 has a substantially cylindrical shape with an approximately polygonal cross section with bulges.

The suction nozzle 110 comprises an upper wall 120 and an approximately parallel lower wall 122 and two side walls 124 which are designed in the manner of an inverted trapezoid, the upper wall 120 being the longest side of this trapezoid and the two side walls 124 the two side legs form this trapezoid. In addition, the upper wall 120, which rests on a surface of the underside 112, is adapted to this surface both in cross section and in longitudinal section, so that the entire suction nozzle 110 with its upper wall 120 covers the entire surface almost over the entire length of the housing 114 up to the housing end 116 is present. In addition, side extensions 126 are formed on the suction nozzle 110 as an extension of the side walls 124, which also lie over the entire surface on the underside 112 and bring about an additional improvement in a positive locking of the suction nozzle 110 on the underside 112 of the housing 114.

As in the exemplary embodiment shown and described in FIG. 1, the suction hood 24 is held on the cylinder piece 38. The suction nozzle 110 is additionally fixed by a U-shaped bracket 128, the free ends 130 of which are bent toward one another and engage in a suspension hole 134 arranged on opposite sides of an upper side 132 of the housing 114. This bracket 128 engages over the entire underside 112 of the housing 114, including the suction nozzle 110 near the housing end 116.

In its area projecting beyond the housing end 116, the suction connection 110 widens to the hose connection connection 118, which preferably has a circular cross section and is bent upwards in the direction of the upper side 132 of the housing 114. This hose connection piece 118 is additionally provided with an air regulating sleeve 136 which has a by-pass opening rotatable on an adjustment thread 140 covering is adjustable in different dimensions. By adjusting the air regulating sleeve 136, it is thus possible to adjust the suction power available on the grinding tool 22.

Claims (46)

1. Grinding machine, comprising a grinding tool (22) which is driven to oscillate about a pivot axis fixed relative to the machine and through a small pivot angle and which has a grinding face with at least one corner region (90) and through which passes at least one suction channel leading from a suck-in orifice (94, 96) to a suck-off orifice (104) located on a side facing away from the grinding face, the suck-off orifice (104) being arranged outside the corner region (90), characterised in that there is provided a suck-off hood (24) which can be secured fixedly relative to the machine and which engages over the suck-off orifice (104) in all the pivoting positions and allows the corner region (90) of the grinding tool (22) to project without covering, and in that the suck-off hood (24) has a sealing edge (32) confronting the grinding tool (22) and located in geometrical faces (44) invariant in terms of pivoting relative to the latter.
2. Grinding machine according to Claim 1, characterised in that the suck-off hood (24) engages over the grinding tool (22) in all pivoting positions within its outer edges (84).
3. Grinding machine according to Claim 1 or 2, characterised in that the suck-off hood (24) engages over the grinding tool (22), in a radial direction starting from its pivot axis (18) and pointing towards the corner region (90) projecting without covering, at most over approximately two thirds of its maximum extension in this direction.
4. Grinding machine according to Claim 3, characterised in that the suck-off hood (24) engages over the grinding tool (22), in the radial direction starting from its pivot axis (18) and pointing towards the corner region (90) projecting without covering, at most over approximately half its maximum extension in this direction.
5. Grinding machine according to Claim 4, characterised in that the sealing edge (32) extends so as to loop at a short distance round all the pivoting positions of the suck-off orifices (104).
6. Grinding machine according to one of the preceding claims, characterised in that the suck-off hood (24) engages jointly over a plurality of suck-off orifices (104) of the grinding tool (22).
7. Grinding machine according to Claim 6, characterised in that the sealing edge (32) jointly loops round the suck-off orifices (104).
8. Grinding machine according to one of the preceding claims, characterised in that the suck-off hood (24) has an annular chamber (30) which is located above the suck-off orifices (104) and into which a suck-off connection piece (40) opens laterally at a short distance above the sealing edge (32).
9. Grinding machine according to Claim 8, characterised in that the suck-off connection piece (40) is formed in one piece onto the suck-off hood (24).
10. Grinding machine according to Claim 8 or 9, with a housing extending away from the pivot axis in the radial direction, characterised in that the suck-off connection piece (110) extends along an underside (112) of the housing (114).
11. Grinding machine according to Claim 10, characterised in that the suck-off connection piece (110) bears against the underside (112) of the housing (114).
12. Grinding machine according to Claim 11, characterised in that the suck-off connection piece (110) is matched with its upper wall (120) confronting the housing (114) to a surface (112) of the housing (114).
13. Grinding machine according to Claim 12, characterised in that the housing (114) has an approximately cylindrical shape, and the suck-off connection piece (110) has an approximately inversely trapezoidal cross-section.
14. Grinding machine according to one of Claims 10 to 13, characterized in that the suck-off connection piece (110) extends beyond a housing end (116) located opposite the pivot axis (18).
15. Grinding machine according to Claim 14, characterised in that the suck-off connection piece (110) has a hose union piece (118) in its region extending beyond the housing end (116).
16. Grinding machine according to one of Claims 10 to 15, characterized in that the suck-off connection piece (110) is held on the housing (114) in the region of the housing end (116) by means of a clip (128).
17. Grinding machine according to Claim 8 or 9, with a housing extending away from the pivot axis in the radial direction, characterised in that the suck-off connection piece (40) projects from the annular chamber (30) in an approximately radial direction in a manner rotated at an angle relative to the housing and is connected to an elbow 48.
18. Grinding machine according to Claim 17, characterised in that the elbow (48) can be connected to the suck-off connection piece (40) in at least two positions, in which an elbow orifice (50) points respectively in opposite directions.
19. Grinding machine according to one of the preceding claims, characterised in that the suck-off hood (24) carries on its side facing away from the grinding tool (22), above the annular chamber (30), a mounting flange (34) formed on in one piece.
20. Grinding machine according to Claim 19, characterised in that the mounting flange is a cylindrical extension (34) having a clamping element (52).
21. Grinding machine according to Claim 20, characterised in that the clamping element (52) is arranged in the region of the suck-off connection piece (40).
22. Grinding machine according to one of the preceding claims, characterised in that the sealing edge (32) has a receptacle for a sealing ring (58) made of slidable sealing material.
23. Grinding machine according to Claim 22, characterised in that the sealing edge (32) is coated with slidable sealing material.
24. Grinding machine according to Claim 22 or 23, characterised in that the slidable sealing material is elastic.
25. Grinding machine according to one of Claims 22 to 24, characterised in that the slidable sealing material is a felt.
26. Grinding machine according to one of Claims 1 to 21, characterised in that a sealing element made of rubber or polyurethane foam is inserted between the sealing edge (32) and the grinding tool (22).
27. Grinding tool (22) for grinding machines (10), having a drive shaft (16) oscillating about a pivot axis (18) fixed relative to the machine, which grinding tool has at least one corner region (90) and through which passes at least one suction channel leading from a suck-in orifice (94, 96) to a suck-off orifice (104) located on a side of the grinding tool facing away from the grinding face (80), the suck-off orifice (104) being arranged outside the corner region (90), especially for a grinding machine according to one of Claims 1 to 26, characterised in that the suck-in orifice (94, 96) is arranged in the grinding face (80) of at least one corner region (90), and in that the suck-off orifice (104) is surrounded by a sealing face (74) lying in a geometrical plane invariant in terms of pivoting.
28. Grinding tool according to Claim 27, characterised in that the suck-off orifice (104) is arranged in a surface of the grinding tool (22) located opposite the grinding face (80) and perpendicular to the pivot axis (18).
29. Grinding tool according to Claim 27 or 28, characterised in that the suck-off orifice (104) is arranged at a short radial distance from the pivot axis (80) (sic).
30. Grinding tool according to Claim 29, characterised in that the suck-off orifice (104) extends in the radial direction of the pivot axis (18) as far as at most half the maximum radial extension of the grinding tool (22).
31. Grinding tool according to one of Claims 27 to 30, characterised in that the suck-off orifice (104) is arranged offset at an angle of rotation relative to the corner region (90), with the pivot axis (18) as the axis of rotation.
32. Grinding tool according to Claim 31, characterised in that the sealing face (74) has a receptacle (70) for a gasket (66) made of slidable sealing material.
33. Grinding tool according to Claim 32, characterised in that the sealing face (74) is equipped with slidable sealing material (72).
34. Grinding tool according to Claim 33, characterised in that the slidable sealing material (72) is applied as a coating to the sealing face (74).
35. Grinding tool according to one of Claims 27 to 34, characterised in that a plurality of suck-off orifices (104) are provided.
36. Grinding tool according to Claim 35, characterised in that the suck-off orifices (104) are surrounded by a common sealing face (74).
37. Grinding tool according to one of Claims 35 or 36, characterised in that the suction channel is an annular channel (82) connecting the suck-off orifices (104) and extending in the grinding tool (22).
38. Grinding tool according to Claim 37, characterised in that the path of the annular channel (82) is matched to an outer contour of the grinding tool (22) and extends at a distance from the outer edges (84) of the latter.
39. Grinding tool according to Claim 37 or 38, characterised in that the annular channel (82) extends around a central recess (21) for a clamping element (23) without any connection to said recess.
40. Grinding tool according to Claims 37 to 40, characterised in that the annular channel (82) has essentially a U-shaped cross-section and extends directly under a coverplate (60) of the grinding tool (22) in an elastic layer (76) of the grinding tool (22).
41. Grinding tool according to one of Claims 37 to 40, characterised in that further suck-in orifices (96) are provided in the grinding face (80) at a distance from its outer edge (84) and along this.
42. Grinding tool according to one of Claims 37 to 41, characterised in that the suck-in orifices (94, 96) are arranged so as to be covered over their full area by the annular channel (82), as seen in the direction of the pivot axis (18).
43. Grinding tool according to one of Claims 37 to 42, characterised in that the suck-off orifices (104) are arranged so as to be covered over their full area by the annular channel (82), as seen in the direction of the pivot axis (18).
44. Grinding tool according to one of Claims 37 to 43, characterised in that the suck-off orifices (104) are arranged in the regions of the annular channel (82) which are located nearest the pivot axis (18).
45. Grinding tool according to one of Claims 27 to 44, characterised in that the grinding tool (22) is made biangular or triangular and has a two-figure or three-figure axis of symmetry in terms of its shape and the arrangement of the suck-in (94, 96) and suck-off (104) orifices.
46. Grinding tool according to one of Claims 27 to 45, characterised in that, starting from the annular channel (82), channels (100) extending in the direction of the outer edge (84) and opening at the outer edge into suck-in orifices (102) are provided.

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