EP2186600A1 - Surface grinder, especially concrete grinder - Google Patents

Abstract

The grinder has a drive shaft (6) mounted in a gear neck (5), and a concrete grinding wheel (8) detachably attached at the drive shaft and provided with a funnel-shaped extraction hood (9) that covers the concrete grinding wheel. The extraction hood is fastened in the region of a central opening of the gear neck by a holding device. The holding device has a height adjustment device (10) with which the extraction hood is height-adjustably directly or indirectly guided and fixed in an axial direction of the drive shaft with respect to the gear neck.

Description

The invention relates to a surface grinder, in particular a concrete grinder according to the preamble of claim 1.

In a known generic concrete grinder ( CH 694 756 A5 ) is mounted in a Getriebehals a drive shaft to which a concrete grinding wheel is detachably connected. In addition, the concrete grinder has a funnel-shaped suction hood, which covers the grinding wheel from above and engages over the edge with a protective ring. The suction hood is fastened in the region of a central opening for the gear neck by means of a holding device.

Specifically, the known concrete grinder is designed as a hand-held angle grinder with a motor housing for an electric motor and an attached angle gear, which has the gear neck and the central drive shaft with an end-side threaded pin for mounting and holding the concrete grinding wheel by means of a clamping nut. A suction device can be connected to the suction hood via a suction pipe and the grinding dust is extracted by suction. In addition, the suction hood also has a protective function for a user by retaining abraded grit. The funnel-shaped suction hood consists here in one piece of a funnel neck and a hood bell part formed thereon, wherein the suction hood with the funnel part is fixedly screwed to the gear neck.

Commercially available concrete grinding wheels which can be used with the known concrete grinder consist of a plate-shaped, curved base disk with a central connection opening and with through openings for the sanding dust extraction. On the base disk projecting, web-shaped, segment-like grinding elements are attached to the grinding surface as diamond grinding stones. These abrasive elements wear out and wear out over time as the concrete grinder operates, reducing the useful grinding element height.

In the known concrete grinder a sealing brush ring is attached to the open edge of the hopper, which engages over the edge of the grinding wheel and rests on the grinding surface during operation. The sealing bristle ring here largely prevents sanding dust from the extraction hood during grinding. In addition, the space required for the suction of air from the environment for the extraction of the grinding dust is created between the bristles of the sealing brush ring. However, such a suction hood with a sealing brush ring has the following disadvantages:

The sealing brush ring resting on the grinding surface during grinding slows down the grinding movement, which unfavorably increases the handling force. In addition, this force changes their depending on the support and position of the brush ring elements, so that is lost to an operator of the desirable direct contact with the grinding surface. Just as the height of the grinding elements decreases during operation, the bristle length of the sealing brush ring is reduced by wear. If a grinding wheel consumed by wear is replaced by a new one, the bristle length of the sealing brush ring may possibly only be so long that it no longer rests on the grinding surface with not yet worn grinding elements, but a relatively large gap between the sealing brush ring and the grinding surface is due to the large amounts of sanding dust and eroded abrasive in an inadmissible manner outside the extraction hood. This deficiency can only be remedied by replacing the entire suction hood with a new brush ring.

Next is a concrete grinder known ( DE 10 2006 041 671 A1 ) with a suction hood, the edge partially, in particular by a hinged lid can be opened so that in the open hood segment a grinding wheel is exposed to its outer edge and thus grinding operations by leading to a corner in this edge region are possible.

The object of the invention is to develop a generic concrete grinder so that an effective extraction of sanding dust and sanding material can be ensured regardless of the degree of wear of the grinding elements of the grinding wheel.

This object is achieved with the features of claim 1.

According to claim 1, the holding device for attaching the suction hood on a height adjustment device with which the suction hood is guided in the axial direction of the drive shaft directly or indirectly with respect to the transmission neck, height adjustable and fixable.

Thus, a distance compensation according to the wear of the grinding elements can be performed by a height adjustment of the suction hood. It is thus possible, a minimum distance of about 1 to 3 mm, preferably of about 2 mm, between the free edge of a protective ring of the suction hood, which engages over the concrete grinding wheel edge and adjust a grinding surface, which with increasing wear of the grinding elements or optionally at Replacement by a new grinding wheel is adjustable. The distance of the guard ring edge to the Grinding surface is therefore on the one hand chosen so large that the required air intake is ensured by the environment for the suction and on the other hand by the relatively small gap gap no grinding dust from the suction hood penetrates to the outside. If there is too little clearance, especially if the protective ring edge of the suction hood rests on the grinding surface, it will be sucked in impermissibly. On the other hand, grinding dust can penetrate to the outside due to an excessive gap distance. Both states, which require an altitude adjustment of the extraction hood, are readily communicated to the user during operation. Since the grinding elements wear only gradually or replacement of grinding wheels is required only at longer intervals, a corresponding readjustment of the height adjustment of the suction hood is only carried out at longer intervals.

As can be seen in the inventive arrangement "flexible" and wear compensating elements on the free funnel edge of the suction hood, such as the known brush ring or also known for the same purpose rubber slats completely omitted, so that the associated and explained above disadvantages are no longer present. Optionally, however, such flexible edge formations in connection with the inventive arrangement can be used for special applications, in which case the wear of such flexible edge formations by an inventive height adjustment of the suction hood is avoidable or at least considerably reduced.

In a specific embodiment according to claim 2 includes a funnel neck of the suction hood as the central passage opening the gear neck and is guided vertically adjustable by respectively associated intermeshing guide elements. A clampable clamping ring surrounds the funnel neck for fixing the respective height adjustment.

In a particularly preferred embodiment according to claim 3, the funnel neck for realizing the height adjustment of the exhaust hood from an inner sleeve which is rotatably supported on Getriebehals and with an engaging nose as a first guide element directly or indirectly in a helically mounted spiral groove on Getriebehals as associated second guide element intervenes. This can be done easily and accurately with a screwing by rotation of the inner sleeve relative to the Getriebehals a continuous height adjustment for distance compensation at a wear of grinding elements. A certain height adjustment can then be fixed with the inner sleeve comprehensive clamping ring. If the engagement nose is formed directly on the inner sleeve, this and / or the inner surface of the inner sleeve for fixing by the clamping ring on the gear neck must be pressed, for which it may be necessary to perform the inner sleeve partially slotted.

In a modified embodiment according to claim 4, the engagement nose is formed as a radially inwardly facing clamping lug on the clamping ring. In this case, this clamping lug engages through an associated slot-shaped recess of the inner sleeve into the spiral groove on the gear neck. The engagement nose can thus act in a further function when contracting the clamping ring as a clamping nose, which exerts a clamping fit at the bottom of the spiral groove.

If the inner sleeve is formed as part of the height adjustment with the screw mechanism of engaging nose and spiral groove integral with the downwardly adjacent hood bell part, this twists with a Schraubverdrehung the inner sleeve and thus possibly also connected to this hood part suction tube, which then in the different rotational positions the inner sleeve or the associated height settings in different angular positions on the concrete grinder projects. This can interfere with handling. In order now to give the hood bell part and an attached suction tube a non-rotatable position on the concrete grinder, is proposed with claim 5, the suction hood form multiple parts, such that the inner sleeve is rotatably received as a funnel neck in the central passage opening of a subsequent hood bell part of the suction hood. The passage opening edge of the hood bell part is held between a lower radially projecting support flange of the inner sleeve and an upwardly spaced spring ring, preferably a snap ring on the inner sleeve, whereby a simple running pivot bearing between the inner sleeve and the hood bell part is formed. Preferably, between the spring ring and the passage opening edge of the hood bell part, a protective disk is used to improve the ease of pivoting and as protection against scratching. In addition, the hood bell part and / or an adjoining suction tube has an upwardly projecting extension as a torque transducer, which engages in a height-displaceable manner with respect to the transmission neck fixed torque support. As a result, with a screw rotation of the inner sleeve and thus carried out height adjustment of the suction hood the hood bell part and optionally connected thereto a suction tube is held non-rotatably on the concrete grinder. Likewise, forces are supported on the suction tube by a connected suction hose. In this construction, the clamping ring is arranged above the snap ring.

A height adjustment is easy to carry out when the inner sleeve is rotatable together with the clamping ring, in particular when the engagement nose is formed as a clamping lug on the clamping ring and engages through the slot-shaped recess of the inner sleeve into the spiral groove. For this purpose, it is proposed with claim 6, that at least one radially inwardly directed driving lug is attached to the clamping ring, which in a assigned catch opening engages the inner sleeve. In a suitable concrete embodiment, a respective driver nose can be attached to the dividing edge of the clamping ring as a vertical web and the driver opening is designed as an associated vertical slot in the inner casing.

To set the clamping ring expedient in its axial position on the inner sleeve, a horizontally encircling engagement groove is formed according to claim 7 on the outer side of the inner sleeve into which the clamping ring engages with a correspondingly associated inner web.

According to claim 8, the clamping ring can be designed in the manner of a clamp, wherein in each case at the dividing edge region, a radially projecting clamping block is attached. By means of these clamping blocks, a tangential clamping screw which can be manually operated via a knurling wheel is guided. Instead of a clamping screw, a clamping closure known per se could also be provided. Advantageously, so that the entire height adjustment and wear tracking, both the Schraubverdrehung the inner sleeve with the clamping ring and the fixation of the clamping ring, without tools and quickly carried out by hand.

Basically, the above height adjustment of the suction hood for wear compensation of the grinding elements can be used in differently constructed concrete grinding. This technique is particularly well suited according to claim 9 for a concrete grinder in the form of a hand-held angle grinder, in particular a concrete floor grinder with a tubular, usable as a handle motor housing for an electric motor and an angle gear connected to the Getriebehals. In Getriebehals the central drive shaft is housed in pivot bearings with an end-side threaded pin for attaching the concrete grinding wheel and for mounting by means of a clamping screw.

With claim 10, a suction pipe with the suction hood, in particular with a hood bell part is connected so that it extends with a hand engagement distance below and parallel to the motor housing and expedient for ergonomic handling about the length of the motor housing. A torque support for the non-rotatable hood bell part or the suction tube is executed in a structurally suitable design as a housing-fixed, from the motor housing downwardly facing and transversely extending U-support bracket with an insertion for integrally formed on the hood bell part or the suction torque transducer.

In a simple to manufacture and easy to clean design, the suction tube is formed in two parts, wherein a lower shell is integrally formed on the suction hood, in particular on the hood bell part. The upper shell is placed as a separately manufactured component on the lower shell and fastened, in particular clipped. For a Ansaugschlauchanschluss while end of the suction tube a connection-clamping ring is provided.

In a further development according to claim 12 is provided as a further handle in addition to the motor housing a transversely extending bow handle, which is arranged above the angle gear about a transverse axis pivotable and fixable so that the handle portion is in a forward pivoted position on a front angular segment of the hood and is pivoted in a zurückgeschwenkten position from this area to the rear and lies approximately above the angle gear. With this bow handle part a good leadership of the concrete grinder is possible and it can be applied ergonomically a large pressure force on the grinding wheel when needed, with the other hand on the motor housing also a guide of the concrete grinder takes place.

Suitably, the bow handle is U-shaped and open on one side with a longer U-leg as a handle part, wherein the shorter U-leg is selectively connected to the left or right of the engine or transmission housing pivotable and lockable. This provides an ergonomically favorable grip shape for both left-handed and right-handed users.

In order to be able to carry out sanding work, in particular in floor corners to adjacent side walls, it is necessary to grind with the grinding wheel edge into such corners. For this purpose, it is provided according to claim 14 that a forward-facing hood segment part of the suction hood, in particular a hood bell part for releasing an underlying grinding wheel segment is designed to be pivotable in a horizontal plane.

For this purpose, it is proposed for a specific construction with claim 15 that the hood segment part with a hood segment ring part, the inner sleeve pivotally surrounds. In the closed position, the hood segment part covers a segment clearance of the suction hood from above and in the open position, the hood segment part is pivoted out of the region of the Segementfreiraums, so that this, and thus a revolving in Segementfreirarum grinding wheel edge area are released. The hood segment part is thus held captive on the suction hood or the inner sleeve and can be pivoted without tools in its respective function division. Advantageously, the hood segment part is then held in both the closed position and in the open position by überdrückbare latching connections.

A training example of the invention will be explained in more detail with reference to a drawing.

Fig. 1

eine perspektivische Ansicht eines Betonschleifers mit einem geschlossenen Haubensegmentteil;

Fig. 2

den Betonschleifer nach Fig. 1 mit offenem Haubensegmentteil;

Fig. 3

eine Seitenansicht des Betonschleifers mit offenem Haubensegmentteil und nach oben geschwenktem Griffteil;

Fig. 4

eine Ansicht von unten auf eine Schleifscheibe und eine Absaughaube bei geschlossenem Haubensegmentteil;

Fig. 5

eine Ansicht entsprechend Fig. 4 mit geöffnetem Haubensegmentteil;

Fig. 6

einen Vertikalschnitt durch die Längsmitte des Betonschleifers;

Fig. 7

einen vergrößerten Ausschnitt aus Fig. 6 im Bereich der Absaughaube;

Fig.8

eine Ansicht von vorne auf den Betonschleifer und die abgenommene Absaughaube;

Fig. 9

eine perspektivische Ansicht einer Innenhülse mit Schutzring und eines Klemmrings;

Fig. 10

eine perspektivische vergrößerte Ansicht der Absaughaube im Bereich des montierten Klemmrings;

Fig. 11

eine perspektivische Ansicht im Bereich eines Drehmomentaufnehmers in dessen unterer Stellung; und

Fig. 12

eine Ansicht entsprechend Fig. 11 mit dem Drehmomentaufnehmer in der oberen Stellung.

Show it:

Fig. 1

a perspective view of a concrete grinder with a closed hood segment part;

Fig. 2

after the concrete grinder Fig. 1 with open hood segment part;

Fig. 3

a side view of the concrete grinder with open hood segment part and upwardly pivoted handle part;

Fig. 4

a view from below of a grinding wheel and a suction hood with hood part closed;

Fig. 5

a view accordingly Fig. 4 with open hood segment part;

Fig. 6

a vertical section through the longitudinal center of the concrete grinder;

Fig. 7

an enlarged section Fig. 6 in the area of the extraction hood;

Figure 8

a view from the front of the concrete grinder and the removed suction hood;

Fig. 9

a perspective view of an inner sleeve with guard ring and a clamping ring;

Fig. 10

a perspective enlarged view of the suction hood in the region of the mounted clamping ring;

Fig. 11

a perspective view in the region of a torque transducer in its lower position; and

Fig. 12

a view accordingly Fig. 11 with the torque transducer in the upper position.

In the Fig. 1 to 3 views of the complete concrete grinder 1 are shown, which is designed as a hand-held angle grinder, in particular for concrete floor grinding work with a tubular, usable as a handle motor housing 2, in which an electric motor is received, which can be switched on and off with a switch 3.

To the front of the motor housing (2) is followed by an angle gear 4 with a gear neck 5, in which a drive shaft 6 projects with an end-side gear pin 7 down to which a grinding wheel 8 is attachable and is held with a (not shown) clamping nut ( see Fig. 6 and 7 ).

At the gear neck 5 a funnel-shaped suction hood 9 is fixed in the region of a central passage opening for the transmission neck 5, wherein the holding device has a height adjustment device 10, which will be described in detail below.

The suction hood 9 is designed in several parts and consists in particular of an inner sleeve 11, which comprises a clamping ring 12 and a hood bell part 13. The inner sleeve 11 is rotatably mounted in the hood bell part 13, wherein the hood bell part 13, the grinding wheel 8 engages over the edge with a guard ring 14.

The cowl bell part 13 has a forwardly directed portion as a segment clearance 15, which can be covered by a forwardly facing hood segment part 16. For this purpose, the hood segment part 16 is pivotably held by a hood segment ring part 17 on the inner sleeve 11. In the closed position of the hood segment part 16 (FIG. Fig. 1 ), the segmental space 15 is covered and the suction hood 9 is closed as a whole. In the position of the hood segment part 16 pivoted into the open position, the area of the segment free space 15 is released ( Fig. 2 ), so that there protrudes a portion 18 of the rotating grinding wheel 8, for example, for grinding work on the ground in a corner region to a side wall. By überdrückbare snap-in connection elements 19, the hood segment part 16 is set and held in two functional positions.

The functional positions of the hood segment part 16 on the suction hood 9 are also clear from the Fig. 4 and 5 can be seen, which show a view from below of the suction hood 9 with mounted grinding wheel 8. The grinding wheel 8 is fitted with a central opening on the threaded pin 7 of the drive shaft 6 and held with a clamping nut 20. The grinding wheel 8 consists of a convex towards the center (see Fig. 6 ) Projecting base disk part 29 of the edge side and at a center offset circle segment-like grinding elements 22 in the manner of diamond grinding stones to the concrete grinding plane out with a certain grinding element height. In addition, 8 offset flow openings 23 are arranged for the extraction of sanding dust in the grinding wheel.

In Fig. 4 the hood segment part 16 is closed and in Fig. 5 to open the segment free space 15 shown open.

At the suction hood 9 and the hood bell part 13, a suction pipe 24 is connected, which extends below and parallel to the motor housing 2. The Suction tube 24 is formed in two parts, wherein a lower shell 25 is integrally formed on the hood bell part 13 and a separate upper shell 26 is clipped onto the lower shell 25. For the connection of a suction hose (not shown), a connection clamping ring 27 is provided at the end of the suction pipe 24, which also holds the upper shell 26 and lower shell 25 of the suction pipe 24 together.

Transverse to the motor housing 2 extends a U-shaped bow handle 28 having a longer U-leg as a handle portion 29, wherein the shorter U-leg 30 is either left or right on the motor housing 2 or slightly offset to the front of the transmission housing pivotally connected and lockable.

In the Fig. 1 and 2 the handle member 29 is pivoted forward in a working position, which is particularly suitable for grinding work with a closed hood segment part 16. When working with open Haubensegmenfteil 16, however, the handle member 29 can be pivoted upwards, as in Fig. 3 shown, so that a hand on the handle 29 in a corner area does not abut against a side wall.

Based on 6 to 12 In the following, the height adjusting device 10 for the suction hood 9 and the hood bell part 13 with respect to the gear sleeve 5 for a distance adjustment at a height reduction by wear and tear of the grinding elements 22 is explained in:

On the Getriebehals 5, the inner sleeve 11 is slidably mounted. The inner sleeve 11 has at the lower end side a radially projecting support flange 31, wherein the hood bell part 13 is supported and held there from above with a passage opening edge 32 of a passage opening. Farther upward, the hood segment ring part 17 connects to it, with which the hood segment part 16 is pivotally mounted.

Subsequently, a protective plate 33 is inserted and these superimposed wall layers are held axially by an overlying Seeger ring 34.

About the snap ring 34 of the clamping ring 12 is mounted, each having a driving lug 35, 36 at the dividing edge, which engage in a vertical slot 37 of the inner sleeve 11, so that the inner sleeve 11 and the clamping ring 2 are rotatable together. In the region of Mitnehmemasen 35, 36 radially protruding clamping blocks 38, 39 are formed on the clamping ring 12, through which a hand-operated via a thumb wheel 40 clamping screw 41 is guided. In addition, for an axial relative fixing between the clamping ring 12 and the inner sleeve 11, on the outside of a horizontally encircling engagement groove 42 is mounted, into which engages a formed on the clamping ring 12 inner web 43.

On the clamping ring 12, a radially inwardly projecting clamping nose 44 is formed, which engages through an associated slot-shaped recess 45 of the inner sleeve into a spiral groove 46 on the gear neck 5. The clamping nose 44 and the slot-shaped recess 45 are also inclined according to the inclination of the spiral groove 46.

At the hood bell part 13, an upwardly projecting extension is formed as Drehmomentaufnehmer 47 in the region of the connection point of the suction tube 24, which is height-displaceably held in an insertion 48 of a housing-fixed, from the motor housing 2 facing downwards and transversely extending U-support bracket 49.

The height adjustment device 10 has the following function:

Upon rotation of the inner sleeve 11 together with the clamping ring 12 on the gear neck 5 is effected by the engagement of the clamping nose 44 in the spiral groove 46th a height adjustment of the suction hood 9 and the hood bell part 13 with the guard ring 14 with respect to the gear neck 5 and thus also with respect to the grinding elements 22 of the grinding wheel 8. Thus, the lower guard ring edge of the hood bell part 13 can be positioned so that compared to the guard ring edge, the grinding elements by about mm project downward and thus a correspondingly large gap between the grinding surface and the guard ring 14 of the hood part 13 is created, on the one hand allows a sufficient air intake and on the other hand can leak small sanding dust. Due to the simple tool-free height adjustment, a simple and quick adaptation to wear of the grinding elements is possible. The respective height adjustment can be easily and quickly fixed with the clamping ring 12.

By the pivotal mounting of the inner sleeve 11 at the central passage opening of the hood member 13 in conjunction with the Drehmomentaufnehmer 47 and the U-support bracket 49 ensures that, although the relative height of the intake pipe 24 and the hood segment part 16 is adjusted relative to the transmission neck 5, however Position of the suction tube 24 is maintained parallel under the motor housing 2 and the forward position of the segmental clearance 15 together with the hood segment part 16.

In Fig. 11 the suction hood 9 and thus also the torque transducer 47 is shown in the insertion opening 48 of the U-support bracket 49 in the lowermost position in which the guard ring 14, the grinding elements 22 of the grinding wheel 8 are covered. In Fig. 12 on the other hand, the suction hood 9 and thus the torque transducer 47 is shown in the uppermost setting position, in which at a grinding wheel with new or little worn grinding rites 22 these project under the guard ring 14. The easy-to-use height adjustment device 10 can between these two Adjusted extreme positions the above-explained gap setting of about 2 mm for optimal Schleifstaubabsaugung and fixed. P 73CO 08 70

Claims (15)

Surface grinders, especially concrete grinders
with a transmission shaft (5) mounted drive shaft (6) to which a concrete grinding wheel (8) is detachably connected, and
with a funnel-shaped suction hood (9) which covers the grinding wheel (8) and engages peripherally with a guard ring (14), wherein the suction hood (9) is fastened in the region of a central opening for the gear neck (5) by means of a holding device,
characterized,
in that the holding device has a height adjustment device (10) with which the suction hood (9) can be adjusted in height and fixed in the axial direction of the drive shaft (6), directly or indirectly, with respect to the transmission neck (5). Surface grinder according to claim 1, characterized in that
that a funnel neck of the suction hood (9) as a central passage opening the gear neck (5) and is guided vertically adjustable by respectively associated, interlocking guide elements (44, 46), and
zusammenspannbarer that a clamping ring (12) surrounding the funnel neck for a fixing of the height adjustment. Surface grinder according to claim 2, characterized in that for the realization of the height adjusting device (10) of the funnel neck of the suction hood (9) consists of an inner sleeve (11) which is rotatably held on the gear neck (5) and with an engaging nose (44) as a Guiding element umittelbar or indirectly engages in a helically mounted spiral groove (46) as an associated second guide element on the transmission neck (5), such that a rotation of the inner sleeve (11) causes a height adjustment with respect to the Getriebehalses (5), with the inner sleeve (11 ) comprehensive clamping ring (12) is fixable. Surface grinder according to claim 4, characterized in that the engagement nose is formed as a radially inwardly facing clamping lug on the clamping ring, which engages through an associated slot-shaped recess of the inner sleeve into the spiral groove on the Getriebehals, wherein the clamping ring is mounted above the Segers ring. Surface grinder according to claim 3 or 4, characterized in that the inner sleeve (11) is received as a funnel neck in the central passage opening of a subsequent hood bell part (13) of the suction hood (9) rotatably, wherein the passage opening edge of the hood bell part (13) between a lower radially projecting Support flange (31) of the inner sleeve (11) and an upwardly spaced spring ring (34) in the manner of a snap ring on the inner sleeve (11) is preferably held with an intermediate protective disc (33), and that the cowl bell part (13) and / or an adjoining suction tube (24) has an upwardly projecting extension as Drehmomentaufnehmer (47) which engages vertically displaceable in a relative to the Getriebehalses (5) torque support (48, 49), so that at a Screw twisting of the inner sleeve (11) and height adjustment of the suction hood (9) the hood bell part (13) and optionally the suction tube (24) is held non-rotatably. Surface grinder according to claim 4 or 5, characterized in that on the clamping ring (12) at least one radially inwardly directed driving lug (35, 36) is mounted, which engages in an associated driving opening (37) on the inner sleeve (11), preferably depending a driving lug (35, 36) is attached to the dividing edge of the clamping ring (12) as a vertical web and the driving opening (37) is an associated vertical slot in the inner sleeve (11). Surface grinder according to claim 6, characterized in that on the outer side of the inner sleeve (11) has a horizontally encircling engagement groove (42) is mounted, and in that on the clamping ring (12) has a correspondingly associated inner web (43) is integrally formed. Surface crevice according to one of claims 2 to 7, characterized in that in each case at the dividing edge region of the clamping ring (12) a radially projecting clamping block (38, 39) is mounted, and that by the clamping blocks (38, 39) via a knurled wheel (40) manually operable tangential clamping screw (41) is guided. Surface grinder according to one of claims 1 to 8, characterized in that the concrete grinder is designed as a hand-held angle grinder, in particular as a concrete floor grinder with a tubular, usable as a handle motor housing (2) for an electric motor and with an attached angular gear (4) which the Transmission neck (5) and the central drive shaft (6) with an end-side threaded pin (7) for attaching the concrete grinding wheel (8) and for holding by means of a clamping nut (20). Surface grinder according to claim 9, characterized in that a suction pipe (24) with the suction hood (9), in particular with a hood bell part (13) is connected to a hand engagement distance below and parallel to the motor housing (2), optionally with a torque support as housing-fixed, from the motor housing (2) downwardly facing and transversely extending U-support bracket (49) with an insertion opening (48) for the torque transducer (47) is mounted. Surface grinder according to claim 10, characterized in that the suction tube (24) is formed in two parts, wherein a lower shell (25) integrally formed on the suction hood (9), in particular on a hood bell part (13) and an upper shell (26) as manufactured separately Assembled component, in particular clipped, preferably for a suction hose connection end of the suction tube, a terminal-clamping ring (27) is provided. Surface grinder according to one of claims 9 to 11, characterized in that as a further handle in addition to the motor housing (2) a transverse bow handle (28) is provided which is arranged above the angle gear about a transverse axis pivotable and fixable so that the handle portion (29) in a forwardly pivoted position over a front angle segment of the suction hood (9) and is pivoted in a zurückgeschwenkten position from this area to the rear and approximately above the angle gear (4). Surface grinder according to claim 2, characterized in that the bow-shaped handle (28) is U-shaped with a longer U-leg than handle part (29), wherein the shorter U-leg (30) either left or right on the engine or transmission housing (2) is connected pivotable and lockable. Surface grinder according to one of claims 1 to 13, characterized in that a forward-facing hood segment part (16) of the suction hood (9), in particular a Haubenglockenieüs (13) for releasing an underlying grinding wheel segment is designed to be captively pivotable. Surface grinder according to claim 14, characterized in that the hood segment part (16) with a hood segment ring part (17) pivotally surrounds the inner sleeve (11) and in the closed position covers a segment free space (15) of the suction hood (9) from above, and in that the bonnet segment part (17) is pivoted out of the region of the segment clearance (15) in the open position, the bonnet segment part being held in the closed position and in the open position by push-on snap-in connections (19).

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