EP2349642B1 - Ceiling grinder - Google Patents

Description

The present invention relates to a ceiling grinder, comprising a drive unit, a sanding plate which can be set into rotation by means of the drive unit, a grinding head housing receiving the sanding disc with an opening freeing the sanding pad to the surface to be sanded and a retaining element for holding the ceiling sanding machine (see, for example, US Pat. OA-2005/053902).

Such ceiling grinders, which are not only suitable for grinding a ceiling, but also for grinding walls or other surfaces, are from the prior art, for example from the EP 0 727 281 B1 , in various versions known. Often, in such (ceiling) grinding machines, as for example in the grinding machine after the EP 0 727 281 B1 In the case of the grinding head housing, a connection is provided for an air duct leading to a vacuum cleaner in order to suck the dust contaminated with grinding dust from the grinding head housing during the grinding operation.

Furthermore, from the DE 20 2005 011 659 U1 a further grinding device of the aforementioned type, in which in addition to the aforementioned features also means for generating a negative pressure within the grinding head housing are provided by the head of the grinder or the grinder - due to a negative pressure resulting from the force - to be ground Surface is pulled or held on her.

In this case, the cover surrounding the local sanding pad is adjustable relative to the sanding pad against a spring force and equipped at its (pointing to the surface to be grounded) edge with a replaceable seal ring in grinding mode with the front the sanding plate is aligned and thereby largely or completely closes the gap between the hood and the machined surface for a suction air flow. In this way, a negative pressure can be generated within the hood by means of a hood connected to the vacuum cleaner, which sucks the head part of the grinder, so to speak, on the wall or the ceiling and if necessary. Keeps against the entire weight. Working with such a grinder is much easier because of the mentioned negative pressure generating means and less tiring for the operator, as this particular no overhead or no longer the entire weight of the grinder must be kept when ceiling sanding overhead.

Nevertheless, this device also has certain disadvantages.

Firstly, a grinder designed in such a way, especially if the total weight of the grinder is to be held on a ceiling, requires a particularly powerful suction device which is still adequate for maintaining operational safety even under difficult conditions (strong dust formation and correspondingly rapidly polluting dust filters inside the suction device) ensure high suction power. Secondly, the negative pressure that can be generated within the hood - and thus the suction force that can be achieved via its contact surface - also depends on a sufficient evenness of the surface to be ground, which is not always the case in practice or in a specific application. In the range of (more or less) large unevenness of the surface to be ground, the gap between the hood and the surface to be machined by the slide ring can no longer be "largely" or "completely" closed, causing it to an undesirable air ingress The hood of the grinding head comes. As a result, the negative pressure generated by the vacuum cleaner can collapse directly, so that the grinder pulls the power to be ground surface suddenly abruptly or significantly reduced. The same problem can also arise in case of operating errors, for example when the operating with the grinder operator tilts the grinding head by an awkward motion, which also suddenly collapses the previously prevailing in the hood vacuum suddenly collapses. The grinder, which may not be sufficiently firmly held by the operator at this moment, can then come loose from the slab (or wall) to be ground and - at high speed of the sanding disc - fall down to the floor, resulting in a considerable risk of injury to the operator or other surrounding people is connected. And finally, the sliding rings provided in the aforementioned prior art are exposed to high abrasive wear, which also leads to a progressive reduction in the required sealing or throttling effect of such a sliding ring. The slip rings must therefore be frequently replaced for the purpose of achieving the highest possible negative pressure.

And finally that shows WO 2007/093874 A1 a floor grinding machine and a dedicated grinding wheel. The grinding wheel is provided on a mounting surface facing the grinding wheel with a plurality of mutually independent grinding elements, which are detachably mountable on the mounting surface. However, said floor grinding machine is not suitable for grinding ceilings and it is further neither described nor recognized that the said grinding elements are suitable for generating a negative pressure.

Starting from the above-described prior art, the object of the present invention is to provide an effectively self-sustaining on the surface to be ground ceiling grinding machine of the type mentioned, which works in the most reliable manner possible independent of the presence of a suction device or is as independent as possible of the suction power of a possibly additionally connected suction device and in which the above-described disadvantages are reduced or not even occur. A force acting on the grinding machine in the direction of the surface to be ground should thus be achieved in a particularly advantageous manner without the intervention of a optionally connectable dust extraction device, ie with alternative means for this purpose.

This object is achieved with a ceiling grinder according to claim 1.

This is in addition to the already mentioned features in particular characterized in that the means for generating the negative pressure (vacuum generating means) comprise lamellar elements which rotate in the grinding operation of the grinding machine about the axis of the grinding disc and thereby within the grinding head housing a static negative pressure causing air flow cause.

Thus, the slat-like elements provided according to the invention and the air flow generated thereby in the grinding operation provide a new principle for generating negative pressure, with which a (ceiling) grinding machine can be attracted to a surface to be ground against its weight force or held completely against it.

Particularly preferably, the lamellar elements are designed or disposed within the grinding head housing on the grinding divider so that there is a stationary air circulation with driven grinding disc (also), which contributes to a static negative pressure in the desired size or caused alone.

The "law of Bernoulli" linking the static and dynamic pressure relations, from which it can be deduced that the sum of static and dynamic pressure is always constant (under the conditions that prevail approximately here), is explained in the context of the The present invention adjusting negative pressure (and the resulting force) of particular importance. Because caused by the lamellar elements air flow or air circulation within the Schleifkopfgehäuses (which is covered in the grinding operation on the side of its opening from the surface to be ground) causes a high dynamic air pressure, so that - using the above-mentioned constancy of the sum of static and dynamic air pressure - which reduces static air pressure within the grinder housing relative to the air pressure outside the grinder housing. Since a certain (sub) pressure is known to be equal to the force exerted thereon on a certain surface, in the context of the present invention, the (static) negative pressure averaged over the area of the opening of the grinding head housing multiplied by just this surface of the grinding head housing opening just corresponds to that the grinder acting force.

In a particularly preferred embodiment of the invention, it is provided that the lamellar elements rotate in the grinding operation of the grinding machine together with the grinding plate about its axis.

Insofar as it is understood that the lamellar elements acting as means for producing negative pressure rotate with the sanding disk about its axis, this is to be understood in the sense according to the invention that the lamellar elements (one or more parts) are formed on the sanding pad or in a suitable manner rotatably attached to it (if necessary, releasably or exchangeable) are attached.

Alternatively, however, it may also be appropriate to arrange the lamellar elements on a support structure separate from the sanding pad and to set this separately (eg by means of a separate drive) in rotation, wherein the rotation in the grinding operation of the grinding machine can take place in the same direction or in opposite directions to the rotation of the sanding pad , However, a common drive of sanding disc and lamellar elements is preferable in terms of the lowest possible weight of the ceiling grinder invention. It can be advantageously provided in the context of the invention that the lamellar elements are indeed offset by the same drive unit as the sanding pad in rotation, but that the sanding pad and / or the lamellar elements (or a support structure carrying them) via a switchable coupling mechanism optional - Individually or jointly - coupled to the drive unit or can be decoupled from this, whereby, for example, when commissioning a ceiling grinder according to the invention in a first step, the appropriate negative pressure generating lamellar elements can be set in rotation and only in a second step, if For example, the ceiling grinder is already applied to the surface to be ground and held against it, the sanding plate added, ie can also be set in rotation. Finally, in order to increase the static negative pressure caused according to the invention, it may also be advantageous to drive the lamellar elements with a higher rotational speed relative to the sanding pad, for example by using a separate gearbox for the lamellar elements (with different gear ratios compared to the gearbox for the sanding pad). is possible.

• Zunächst ist hierbei anzuführen, dass die vorliegend gewählten Mittel zur Unterdruckerzeugung im Vergleich zum Stand der Technik weniger abhängig von etwaigen Unebenheiten der zu schleifenden Fläche sind. Es hat sich nämlich in der praktischen Anwendung einer erfindungsgemäßen Deckenschleifmaschine gezeigt, dass sich die erfindungsgemäß mittels der lamellenartigen Elemente im Schleifbetrieb einstellende und den Unterdruck verursachende Luftzirkulation nicht erst dann einstellt, wenn das den Schleifteller umgebende Schleifkopfgehäuse der zu schleifenden Fläche bereits mit seinem umlaufenden Rand zur Anlage kommt, sondern dass sich die den Unterdruck im erfindungsgemäßen Sinn ausbildende Luftzirkulation (bei entsprechend angetriebenem Schleifteller mit daran geeignet angeordneten lamellenartigen Elementen) schon dann einstellt, wenn das Schleifkopfgehäuse noch einen gewissen Abstand (bis hin zu mehreren Zentimetern) von der zu schleifenden Fläche hat. Dies gilt im Übrigen auch dann, wenn der mit angetriebenem Schleifteller in Deckennähe gebrachte Schleifkopf zunächst noch nicht exakt parallel zur Decke ausgerichtet ist - bezogen die Grundfläche des Schleiftellers bzw. die Ebene der im Wesentlichen kreisförmigen Öffnung des Schleifkopfgehäuses. Das Schleifkopfgehäuse wird also (sofern der Schleifteller samt der daran angeordneten Lamellen in Rotation versetzt ist) bereits bei Annäherung desselben an die zu schleifende Fläche gezogen und richtet sich ausgehend von einer zunächst schiefen Lage zu der zu schleifenden Fläche auch selbsttätig parallel hierzu aus.

The presently used principle of generating a - causing a static negative pressure - air flow or air circulation within the grinding head housing by means of the rotating or with the grinding plate co-rotating lamellar elements proves over the prior art for several reasons as superior:

• First of all, it should be mentioned here that the presently chosen means for generating negative pressure are less dependent on any unevenness of the surface to be ground in comparison to the prior art. It has been shown in the practical application of a ceiling grinding machine according to the invention that adjusts the invention by means of the lamellar elements in the grinding operation and the negative pressure causing air circulation does not stop only when surrounding the grinding disc grinding head housing the surface to be ground already with its peripheral edge Plant comes, but that the negative pressure in the inventive sense forming air circulation (with appropriately driven sanding pad with suitably arranged lamellar elements) already sets when the grinding head housing still a certain distance (to towards several centimeters) of the surface to be ground. Incidentally, this also applies if the grinding head brought close to the ceiling with the driven grinding disc is not yet aligned exactly parallel to the ceiling - the base of the grinding disc or the plane of the substantially circular opening of the grinding head housing. The grinding head housing is thus (if the sanding plate is set together with the lamellae arranged thereon) already drawn on approaching the same to the surface to be grounded and is directed from an initially oblique position to the surface to be ground and automatically parallel to this.

The effect of setting a (stationary) air circulation already when approaching the grinding head to the surface to be ground can be recognized in practice that (using a certain output power providing drive motor), the speed of the grinding machine increases significantly as soon as the grinding head housing is approximated with its opening to the grinding disc releasing an (to be ground) interface. The (turbulent) air flow produced by the lamellas and the sanding pad then gives way to a partially automatically maintained air circulation, which requires less power from the drive motor than the generation of the turbulent air flow (without adjacent boundary surface). This explains the observed in practice increase in speed of the grinding disc as the grinding head approaches a surface and makes the already taking place at this stage vacuum generation plausible.

This also results in that in the sense of the invention by means of rotating blades and a thereby induced air flow / air circulation achieved negative pressure not collapsed (or not reduced to such a degree as in the prior art), if, for example, due to unevenness of the ceiling in the region of the peripheral edge of the grinding head housing creates an additional air contact with the ambient air. In this case too, the air flow or circulation induced by the lamellae and causing a vacuum remains substantially maintained.

The negative pressure generated according to the invention by means of the rotating lamellar elements and the resulting force acting on the grinding head in the direction of the surface to be ground thus prove to be considerably more stable against a non-optimal position of the grinding head housing relative to the prior art against any unevenness in this area. This not only increases operator safety but also the reliability and user-friendliness of the grinding machine.

Incidentally, it has been found that the air flow or circulation necessary for a suitably high attractive force also sets without a "sliding ring" in the region of the edge of the opening of the grinding head housing. Rather, it is sufficient, which is also useful to avoid a dust turbulence in the environment, when the grinding head housing at its the abrasive surface zuweisenden edge region has a circumferential, dustproof but as dense brush assembly. From a largely airtight connection between surface to be ground and grinding head housing can therefore be dispensed with in an advantageous manner, whereby the frequent replacement of the provided in the prior art for generating negative pressure slip rings can be avoided.

Furthermore, the negative pressure applied by the rotation of the lamellar elements and the resulting force on the grinding machine (or on its grinding head) are independent of the suction power of e.g. if necessary, additionally to the vacuum cleaner connected to the grinding head housing.

The negative pressure generated solely by the lamellar elements should therefore be as large as possible, by means of suitable design and alignment of the lamellar elements inducing the airflow or circulation, in order to produce a force acting in the direction of the surface to be grounded already with the rotating lamellar elements , which preferably corresponds to at least 60% or at least 80% of the weight of the entire ceiling grinder. The differential force still necessary to hold the ceiling sander on the slab to be ground can then be removed e.g. by additional vacuum generation by means of additional negative pressure generating means (e.g., an air exhaust means suitably connected to the wheelhead housing via suitable air ducts). These additional means then do not have to apply - as in the prior art - alone the vacuum necessary to hold the grinding machine on the blanket to be ground and are therefore subject to (substantially) lower demands on its suction power.

However, in order to bring the advantage which can be generated according to the invention to full advantage, in a first particularly preferred development of the present invention, it is provided that the negative pressure generated in the grinding operation within the grinding head housing solely by means of the lamellar elements (ie without the possibly adding influence of an optional connectable air suction device) is so high that the grinding machine with a force exceeding the weight of the entire grinding machine is held on the surface to be ground. A failure or a reduction in performance of a vacuum cleaner connected to the suction of the grinding dust thus has no appreciable or no safety-relevant influence on the functioning of the grinding machine, including the force acting on it in the direction of the surface to be ground.

As far as in the present case is repeatedly said that some of the above technical characteristics "in grinding" of the grinding machine are to be met, this of course affects the operation of the grinding machine in a mode in which in addition to the sanding pad and the lamellar elements are set in rotation, and Although at a customary and can be provided by the drive unit speed of the grinding plate or the lamellar elements, which (in the load) preferably in the range of at least 1000 revolutions per minute, preferably in the range of 2000 - 3000 or even up to 5000 revolutions per minute. Higher rotational speeds are also conceivable in principle for increasing the producible negative pressure by means of the lamellar elements provided according to the invention.

Nevertheless, in an optional quite possible and for the sake of constant removal of the abrasive products also preferable connection of a suitable suction by means of this on the Schleifkopfgehäuse - preferably back - to be provided connection for a (down) air line to ensure that of the suction Air suction generated by the lamellar elements generated air flow or circulation and the resulting Not reduced negative pressure disadvantageously, but advantageously even increased again.

If the negative pressure caused by the lamellar elements due to their concrete design and arrangement e.g. only corresponds to a force which is less than the total weight of the grinding machine, the necessary for a complete overcoming of the weight of the grinder additional negative pressure in the grinding head housing of the suction device, so that in such a case, different negative pressure generating means for holding the grinding machine on the Ceiling work together.

A further preferred embodiment of the present invention provides that the lamellar elements protrude axially from one end side of the sanding disk in the direction of the surface to be sanded and thereby form the grinding wheels of the ceiling sanding machine. This leads to a - even in grinding operation - spacing of the end face of the sanding pad from the opposite and sanding surface. As a result, the abrading in the aforementioned sense of the end face of the grinding disc abrasive - also in the area of the sanding pad - a substantially around the axis of the sanding pad (between the base and the surface to be sanded) circulating air flow and thus an increase in the dynamic air pressure in this Area. In other words, the area of the sanding disk can contribute to the generation of the necessary holding force for the grinding machine as a result of a static negative pressure which also occurs in the region, which was not the case with the hitherto known vacuum generating means, since here the sanding pad with its abrasive material located on it (For example, a grinding wheel) all over the surface to be ground applied. The vacuum generation Therefore, with the previously known suction devices, the annular surface surrounding the sanding pad within the hood of the sanding head was limited as an active surface for the force exerted on the sanding machine.

The meaning explained above also in the area of the grinding disc, i. between the rotating grinding wheels, applying static negative pressure and therefore acting in the direction of the surface to be ground force then - at suitable sprung storage of the sanding pad to Schleifkopfgehäuse - at the same time acting on the sanding pad in the ceiling direction of attraction and thus for an increase of the rotating grinding wheels on the ceiling (or the other surface to be ground) exerted grinding power.

In a further expedient development of the present invention, it can then additionally be provided that the lamellar elements are equipped at least in their grinding area contacting the surface to be ground with an exchangeable abrasive, in particular a sandpaper, or are themselves exchangeably fastened to the sanding pad. This ensures in a particularly simple manner that the abrasive abrasive - if necessary, with the lamellar elements - can be renewed if necessary.

It is furthermore particularly advantageous if the lamella-like elements forming the grinding bodies are resiliently mounted on the sanding pad or designed to be spring-elastic with respect to the axial direction of the sanding pad. As a result, the contact pressure of the grinding bodies prevailing during grinding can be set or influenced in a particularly expedient manner on the surface to be ground.

In this context (but not only then), it proves to be particularly advantageous if a surrounding the opening for the sanding pad edge region of the Schleikopfgehäuses in its non-operating position laterally projects beyond the grinding body and is resiliently mounted so that it upon pressing the grinding head housing to the surface to be ground counter to a spring force is deflected so that the abrasive located on the sanding plate come into contact with the surface to be ground.

In a further development can then be preferably provided that the resilient mounting of the grinding head housing to the sanding pad has a stop by which the maximum contact pressure of the turn resiliently shaped abrasive is specified to the surface to be sanded. This results in - in connection with the force caused by the negative pressure generating means in the grinding operation on the sanding pad and the entire grinding head housing - an always constant, said maximum value corresponding contact pressure of contrary to their resilience of the surface to be ground for (dynamic) system coming abrasive body.

Moreover, in the context of the present invention, it is advantageous if the lamella-like elements extend in the radial direction of the sanding disk, since this can cause a suitable air circulation in the sense of the invention. In particular, if in this case the lamellar elements protrude in the direction of the surface to be ground of the sanding pad, it is also advantageous if the sanding pad, at least in the intermediate region of the abrasive body, ie in the limited by the radial extent of the lamellar elements annulus, has no open openings, as this favors the setting of a particularly effective air circulation between the sanding pad and sanding surface.

A further advantageous embodiment of the present invention, in which no need to be provided with the surface to be grounded in contact lamellar elements, in contrast, characterized in that the sanding pad has a flat grinding surface with a plurality of apertures, wherein the apertures an air duct between the provide surface to be ground and non-abrasive surface side arranged lamellar elements.

In that regard, in this embodiment of the invention, the openings prove to be advantageous, since they each provide an air channel between the non-grinding surface side arranged lamellar elements and the grinding surface. The non-abrasive side arrangement of the lamellar elements allows this e.g. on the grinding surface at the back of the sanding pad or on a separate, not the grinding surface of the ceiling grinder forming support structure to order.

In this embodiment of the invention, the static flow inducing dynamic pressure acts, inter alia, in the area of the openings of the grinding wheel on the surface to be ground, whereby an intake effect in the sense of the invention can be achieved. It is of great advantage that here a flat and compared to the use of separate grinding elements larger grinding surface is provided. Furthermore, such a sanding pad is easier to manufacture and the lamellar elements are - with the exception of the air flow - exposed to no additional burden.

It is particularly advantageous in the context of the present invention, when the sanding pad in the region of its grinding surface with a flat, exchangeable abrasive, in particular in the form of an abrasive paper, equipped, which has the openings through the grinding surface of the sanding pad corresponding recesses to a produce appropriate air passage between lamellar elements and the surface to be ground.

Such an exchangeable abrasive, especially in the form of an abrasive paper, is particularly favorable to manufacture, corresponds to the features of the invention a particularly preferred embodiment of the present invention and is thus made the subject of an independent claim.

The lamellar elements of a ceiling sanding machine according to the invention are preferably against the sanding pad, i.e. in order to obtain a suitable air flow or circulation. against the standing perpendicular to the axis of rotation end face of the sanding pad, employed, in a particularly advantageous manner at an angle of about 40 ° - 65 ° degree.

The holding element is advantageously designed as a telescopically adjustable in its length holding tube and is pivotally mounted on the grinding head housing, which positively affects the handling of a ceiling grinder invention. If, which is a further preferred development of the present invention, the drive unit is arranged in or on the grinding head housing can, in an advantageous manner the electrical connection cable for the drive motor to be guided within the hollow holding tube, and - in order to ensure its telescopic adjustability - in a spiral shape.

Furthermore, a hollow holding tube - in addition to its advantageously low weight - simultaneously serve the air duct for a Schleifstaubabsaugung and this grinding head side via a flexible air duct with a related connection to the Schleifkopfgehäuse be connected and on the side facing away from the Schleifkopfgehäuse a connection for an air suction, e.g. a connecting piece for connecting a vacuum cleaner, have. A separately attached to the holding element or holding tube handle is preferably arranged rotatably attached thereto.

As a drive motor is preferably used in a grinding machine according to the invention, a brushless and constructed as an external rotor electric motor, which is available in spite of suitable performance in a particularly compact design and low weight.

In the context of the present invention, special attention is finally also to be paid to the total weight of the grinding machine according to the invention, since this must finally be held by the negative pressure generated by means of the "vacuum generating means" and the force resulting therefrom on the surface to be ground. It has been shown that it is of particular advantage if the total weight of the (ceiling) grinding machine according to the invention does not exceed three kilograms or, even more advantageously, two kilograms.

Fig. 1

eine perspektivische Ansicht des Ausführungsbeispiels einer erfindungsgemäßen Deckenschleifmaschine,

Fig. 2

zwei mit verschiedenen lamellenartigen Elementen bestückte Schleifteller zur Verwendung in der Schleifmaschine aus Fig. 1,

Fig. 3

den Schleifteller aus Fig. 2 (unten) ohne und mit Kontakt zu der zu schleifenden Fläche,

Fig. 4

einen Schnitt durch die erfindungsgemäße Schleifmaschine aus Fig. 1,

Fig. 5

zwei Detailansichten zur Kabelführung im Halterohr und zur Anordnung des Griffs,

Fig. 6

ein weiteres Ausführungsbeispiel eines Schleiftellers zur Verwendung in einer Deckenschleifmaschine nach Fig. 1 mit schleifflächenrückseitig angeordneten lamellenartigen Elementen in zwei verschiedenen Ansichten sowie ein hierfür geeignetes Schleifmittel und

Fig. 7

ein nochmals alternatives Ausführungsbeispiel eines Schleiftellers zur Verwendung in einer Deckenschleifmaschine nach Fig. 1 mit zugehörigem Schleifmittel.

Various embodiments of the present invention will be explained in more detail with reference to the drawing. Showing:

Fig. 1

a perspective view of the embodiment of a ceiling grinder according to the invention,

Fig. 2

two sanding plates equipped with different lamellar elements for use in the sanding machine Fig. 1 .

Fig. 3

the sanding pad Fig. 2 (bottom) without and with contact to the surface to be ground,

Fig. 4

a section through the grinding machine according to the invention Fig. 1 .

Fig. 5

two detailed views of the cable guide in the holding tube and the arrangement of the handle,

Fig. 6

a further embodiment of a sanding pad for use in a ceiling grinder after Fig. 1 with sanding surface back arranged lamellar elements in two different views and a suitable abrasive and

Fig. 7

a yet alternative embodiment of a sanding pad for use in a ceiling grinder after Fig. 1 with associated abrasive.

That in the Fig. 1 and 4 In a perspective view and in a sectional view illustrated embodiment of a ceiling grinder 1 according to the invention comprises a grinding head 2 and a thereto by means of a hinge 3 pivotally mounted about an axis holding element 4 in the form of a holding tube with a handle 5. The housing 6 of the grinding head 2 comprises a mounting plate 7, on which an electric drive motor 8 is mounted, in the Grinding operation together with an in Fig. 1 Not shown bevel gear from two mutually offset by 90 ° bevel gears 9, 10 acts as a drive unit and the in Fig. 1 from the grinding head housing 6 concealed sanding pad 12 via a rotatably connected to the sanding pad 12 and the turntable side bevel gear 10 journals 11 set in rotation. For good rotational properties of the turntable 12 of the journal 11 is mounted by means of ball bearings against the grinding head housing 6.

The grinding head housing 6 also has an in Fig. 1 up and in Fig. 4 to the left-facing opening 13, which releases the sanding pad 12 to a surface 14 to be ground, in particular a ceiling or wall to be ground. This opening 13 is bounded by an edge 15 circulating around the sanding pad 12 and extending in the direction of the surface 14, which terminates at its end facing the sanding surface 14 with a circumferential bristle arrangement 16. This serves in particular as dust protection for the environment, since the grinding dust produced in the grinding operation could otherwise be discharged into the environment because of the prevailing within the grinding head housing air flow or circulation.

The sanding head housing 6 substantially completely surrounding the sanding pad 12 (with the exception of the area of the opening 13) further comprises a grinding head housing part 19 resiliently mounted on the mounting plate 7 via suitable bolts 17, 18, which holds the actual receptacle for the relative to the support plate 7 (with the exception of FIG its rotatability) arranged fixed position sanding plate 12 forms. Due to the resilient mounting of the housing part 19, the sanding pad 12 and the sanding plate 12 surrounding edge 15 of the grinding head housing in its relative position are adjustable.

At the surface 14 facing end face 21 of in Fig. 4 shown grinding plate 12, the in Fig. 2 (below) and in Fig. 3 is shown in more detail, a total of four lamellar elements 20 are rotatably mounted, projecting axially from said end face 21 of the grinding plate 12, each extending in the radial direction on the grinding plate and evenly, ie in each case 90 ° apart, over the circumference of Sanding plate 12 are distributed. Obviously, a larger number (eg five, six, seven or even more) or a smaller (eg three or even only two) number of lamellar elements 20 can also be provided.

The lamellae 20 serve in the present embodiment of the invention at the same time as an abrasive body, so that the face 14 facing the surface 14 of the grinding plate 12 during the actual grinding process is spaced from the surface 14. In order that the lamellar elements 20, which are preferably made of a robust carbon fiber material 23 having a certain flexibility, can fulfill the intended purpose of the abrasive function, they are coated on their front side pointing in the direction of rotation R with an abrasive 22 in the form of a particularly robust abrasive paper. which can be suitably (exchangeably) attached to the lamellar elements 20. Alternatively, the lamellar elements 20 may be exchangeably attached to the sanding pad 12 or even the entire sanding pad 12 may be provided for replacement. Incidentally, the lamellae 20 can also be made of other materials, for example of plastic or light metal, and, owing to the material selected and their inclination (angle alpha, cf. Fig. 3 above) to the end face 21 of the grinding plate 12 a certain spring elasticity so that they are bent, for example depending on their contact pressure on the surface 14 to be ground within certain limits according to arrow E to the sanding pad.

Incidentally, the second, in Fig. 2 Sanding plate shown above, on which also four lamellar and turn acting as an abrasive body elements 20 'are mounted in a similar manner and arrangement. Here, the grinding bodies consist of an approximately wedge-shaped base body 23 'made of an elastic foam, which is again provided on its pointing in the direction of rotation R front and its facing the wall or ceiling top with a robust sandpaper 22'. Again, there is a comparable elasticity (see arrow E ') as in the previously described embodiment. Furthermore, the sanding pad 12 and 12 'in the region of a circular ring, which is bounded to the inside by the dashed circle and outwards by the circumference of the sanding plate, not broken.

With reference to the Fig. 3 and 4 can now take the example of in Fig. 2 will be explained below, as by means of the lamellar elements 20 within the grinding head housing 6 (in Fig. 3 only partially shown) a negative pressure in the grinding head housing 6 and a resulting force F is achieved on the grinding head 2.

The lamellae or grinding bodies 20 rotating about the axis of rotation S of the sanding disk 12 according to the arrow R can be seen in the upper illustration Fig. 3 , in which the grinding machine still has a certain distance from the surface 14 to be ground, nor rotate substantially freely with the sanding pad, while in the lower illustration Fig. 3 which is the actual Abrasive operation shows, are in frictional contact with the surface 14 to be ground. Therefore, at preferred load speeds of about 2000 to 3000 revolutions per minute (or more), they scoop the air present in the grinding head housing between the surface to be ground and the turntable in the direction of the arrows A and B pointing out of the plane of the drawing or into it , which due to the rotation of the sanding plate 12 together with lamellae 20 to a circular flow substantially circulating about the axis S within the grinding head housing (between the sanding pad 12 and 12 to be ground blanket) leads.

A further effect results from the centrifugal force acting on the air in the vicinity of the grinding plate, which causes a radially outward flow of air according to arrow D there, ie directly above the end face 21 of the grinding plate 12 facing the surface 14, between two adjacent plates 20. Since the air obtained for this essentially from the center of the sanding pad has to get there again in a different way, an air stream directed radially inward will be arranged in the immediate vicinity of the surface 14 to be ground in accordance with the arrow C, which turns in the direction of the sanding plate 12 and returns there according to arrow D is transported to the outside. In the superposition of these two air flows, a circulation of air essentially rotating about the central axis S occurs, which, as it were, wanders radially outwards in the vicinity of the grinding plate and spirals radially inwards in the vicinity of the ceiling or wall. This induced by the drive unit 8 and the lamellar elements 20 air circulation or air flow generates a high dynamic air pressure and thus a correspondingly reduced static air pressure within the grinding head housing 6, whereby the entire grinding head 2 (also on the attached in the axial direction of the mounting plate 7 grinding plate 12) is pulled with a force according to arrow F in the direction of the surface to be ground. If this force F exceeds the total weight G (cf. Fig. 1 ) of the grinding machine, so this is held in grinding operation on a ceiling, which is the purpose of the invention.

The above-described air flow conditions are essentially already established when the grinding head 2 (with rotating sanding pad 12) approaches the ceiling or some other surface 14 to be sanded, and not at all with its edge 15 or the bristle arrangement 16 of the surface located thereon is applied. Incidentally, the force F acting on the sanding pad also ensures that the sanding head housing part 19, which protrudes resiliently on the mounting plate 7 with its bristle arrangement 16, is displaced against the spring force according to arrow Z, which results in a higher contact pressure is exerted on the abrasive body 20, which is in an elastic deformation of the abrasive body 20 (see. Fig. 3 below). If this adjustability is limited by means of suitable stop elements 24, 25, a defined contact pressure of the (elastic or sprung) grinding body 20 against the surface 14 to be ground is established during grinding operation.

On the grinder head housing 6, a connection 26 is also provided for an air hose 27, the latter being connected on the head end air-conducting with the hollow handle tube 4, on which - on the opposite side - another connection 28 for a (commercial) vacuum cleaner for Schleifstaubabsaugung is provided. Thus, contaminated with grinding dust air from the grinding head housing 6 according to arrow L (see. Fig. 4 Be sucked out, which if necessary with a additional negative pressure generation within the grinding head housing 6 and, accordingly, an increase in the grinding machine 1 at a surface to be grounded holding force F is connected.

The electric motor 29 supplying power to the drive motor 8 is also guided on the grinding head side into the hollow holding tube 4, where, in order not to impair the telescopic length changeability of the holding tube 4, it is guided as a spiral cable, as described in US Pat Fig. 5 is shown above.

Fig. 5 Finally, below shows the concrete embodiment of the arranged on the holding tube 4 handle 5, which is rotatable relative to the holding tube using a circumferentially extending elongated hole 30.

Fig. 6 shows in three superimposed views - from top to bottom - first a top view of another sanding pad 31 for use in a grinding machine after Fig. 1 , Then a perspective view of the respective grinding disc 31 and finally on the grinding surface 33 of the respective grinding disc 31 exchangeable attachable abrasive 32 in the form of an abrasive paper.

The sanding pad 31 has an in Fig. 6 upwardly facing grinding surface 33, which is formed by a first substantially or exactly circular disc 47 of the grinding plate 31 and a total of four - substantially rectangular - openings 34 - 37 has. The openings 34-37 extend in their longitudinal direction - comparable to the grinding elements of the previous embodiments - substantially in the radial direction and each give an air duct to one of a total of four lamellar Elements 39-42 at. Experiments have shown that even with this design of the Schleitellers 31, an air flow can be generated, which - at a suitable high speed and a suitably low weight of the ceiling grinder total - can hold the grinder on the sanding ceiling.

The lamellar elements 39-42 are formed by the inclined front side of four substantially wedge-shaped elements, which are arranged between the first disc 47 and a parallel thereto arranged second disc 38 and - viewed in plan view - slightly offset from the openings 34 - 37th are arranged. On the upper side, each wedge-shaped element has a flat web 43, with which it rests against the back surface of the first disk 47.

Down in Fig. 6 In addition, a sandpaper 32 for sanding surface side and replaceable attachment on the sanding pad 31 is shown, which has a total of four recesses 44 - 47, which correspond to the openings 34 - 37 of the sanding surface 33 of the sanding pad 31 ,

Finally shows Fig. 7 a last embodiment of a usable in the context of the invention grinding plate 49 in a perspective view (shown in FIG Fig. 7 above) together with associated abrasive paper 50 (illustration in FIG Fig. 7 below). The grinding surface 51 of the grinding disc 49 produced in the present case from only one disk has a total of eight apertures 52-59, to which corresponding recesses 60-67 of the abrasive paper 50 are assigned. In addition, a lamellar element 68-75 is arranged at each opening of the grinding wheel 51, which is integral with the grinding wheel 49 is formed and protrudes obliquely there grinding surface back.

Such a grinding plate 49 can be made of aluminum, for example, by punching out of an aluminum disc, the openings 52-59 at three edges and bent to form the lamellar elements 68-75 in the position shown.

Claims (19)

1. A ceiling grinding machine (1) comprising:

   a drive unit (8, 9, 10),

   a grinding plate (12, 12'; 31; 49), which can be set in rotation by means of the drive unit (8, 9, 10),

   a grinding-head housing (6) receiving the grinding plate (12, 12'; 31; 49) and having an opening (13) giving the grinding plate (12, 12'; 31; 49) access to a surface (14) to be ground, and

   a holding element (5) for holding the grinding machine (1), the ceiling grinding machine (1) further comprising means for generating a reduced pressure inside the grinding-head housing (6) so that the ceiling grinding machine (1) is held against the surface (14) to be ground,

   characterized in that

   the means for generating the reduced pressure comprising lamellar elements (20, 20'; 39 - 42; 68 - 75) that rotate (arrow R) around an axis (S) of the grinding plate (12, 12'; 31; 49) during grinding operation of the ceiling grinding machine (1) and cause an air flow (arrows A, B, C, D) that induces a static reduced pressure inside the grinding head housing (6), wherein the reduced pressure generated by the suitably designed and arranged lamellar elements (20, 20'; 39 - 42; 68 - 75) alone is so strong that the thereby generated force which acts in the direction of the surface to be ground (F) corresponds to at least 60% of the weight (G) of the entire grinding machine.
2. A ceiling grinding machine according to claim 1, wherein the lamellar elements (20, 20'; 39 - 42; 68 - 75) rotate together with the grinding plate (12, 12'; 31; 49) around the axis (S) thereof during grinding operation of the grinding machine (1)
3. A ceiling grinding machine according to claim 1 or claim 2, wherein the reduced pressure generated inside the grinding-head housing (6) by the lamellar elements (20, 20'; 39 - 42; 68 - 75) alone during grinding operation is so strong that the grinding machine (1) is held against the surface (14) to be ground with a force (F) that exceeds the force (G) due to the weight of the entire ceiling grinding machine (1).
4. A ceiling grinding machine according to one of the claim 1 to 3, wherein a port (26) for an air-conducting line (27) of a suction device is provided on the grinding-head housing (6).
5. A ceiling grinding machine according to one of the preceding claims, wherein the lamellar elements (20, 20') project axially toward the surface (14) to be ground from an end face (21, 21') of the grinding plate (12, 12') and form the grinding members of the grinding machine (1).
6. A ceiling grinding machine according to claim 5, wherein the lamellar elements (20, 20') are equipped, at least in their grinding region in contact with the surface (14) to be ground, with an exchangeable grinding means (22, 22'), such as abrasive paper, or are fastened exchangeably to the grinding plate (12, 12').
7. A ceiling grinding machine according to claim 5 or claim 6, wherein the lamellar elements (20, 20') forming the grinding members are spring-mounted on the grinding plate (12, 12') relative to the axis (S) of the grinding plate (12, 12') or are resilient by design.
8. A ceiling grinding machine according to one of the preceding claims, wherein a rim region (15) of the grinding-head housing (6) surrounding the opening (13) for the grinding plate (12, 12') projects laterally beyond the grinding members (20, 20') in its non-operating position and is spring-mounted in such a way that, when the grinding-head housing (6, 19) is pressed counter to a spring force against the surface (14) to be ground, it becomes deflected in such a way that the grinding members (20, 20') disposed on the grinding plate (12, 12') come into contact with the surface (14) to be ground.
9. A ceiling grinding machine according to claim 7 or claim 8, wherein the spring-mounting of the grinding-head housing (6, 19) has a stop (24, 25) relative to the grinding plate (12, 12'), thus predetermining the maximum contact pressure that can be exerted on the surface (14) to be ground by the grinding members (20, 20'), which in turn are resilient by design.
10. A ceiling grinding machine according to one of the preceding claims, wherein the lamellar elements (20, 20') extend in radial direction of the grinding plate (12, 12').
11. A ceiling grinding machine according to claim 10, wherein the grinding plate (12, 12') does not have any open through holes in the annulus bounded by the radial extent of the lamellar elements (20, 20').
12. A ceiling grinding machine according to one of the claims1 to 4, wherein the grinding plate (31, 49) has a plane grinding face (33, 51) with a plurality of through holes (34 - 37; 52 - 59), wherein the through holes (34 - 37; 52 - 59) provide an air duct between the surface to be ground and the lamellar elements (39 - 42; 68 - 75), which are disposed on the side corresponding to the non-grinding face.
13. A ceiling grinding machine according to claim 10, wherein the grinding plate (31, 49) is equipped in the region of its grinding face with a plane, exchangeable grinding means (32, 50), especially in the form of an abrasive paper (32, 50), which has cutouts (44 - 47; 60 - 67) corresponding to the through holes (34 - 37; 52 - 59) in the grinding face (33, 51) of the grinding plate (31, 49).
14. A ceiling grinding machine according to one of the preceding claims, wherein the lamellar elements (20, 20') are oriented at an angle (alpha) of approximately 40° - 65° relative to the grinding plate (12, 12').
15. A ceiling grinding machine according to one of the preceding claims, wherein the holding element (4) is designed as a holding tube of telescopically adjustable length and is fastened to swivel on the grinding-head housing (6).
16. A ceiling grinding machine according to one of the preceding claims, wherein the drive unit (8, 9, 10) is disposed in or on the grinding-head housing (6).
17. A ceiling grinding machine according to claim 14, wherein the drive unit (8, 9, 10) comprises a brushless electric motor (8) designed as an external rotor.
18. A ceiling grinding machine according to one of the preceding claims, wherein the grinding machine (1) does not exceed a total weight of three kilograms.
19. A ceiling grinding machine according to claim 12, wherein the grinding machine further comprises grinding means (32, 50) which is plane and has a plurality of cutouts (44 - 47; 60 - 67), each of which gives access to a through hole (34 - 37; 52 - 59) of the grinding face (33, 51) of the grinding plate (31, 49) or to the air duct created thereby to the lamellar elements (39 - 42; 68 - 75).

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