EP1925401B1 - Motor driven hand grinder with adjustable suction mechanism - Google Patents

Description

The invention relates to a motor-driven hand grinder with a rotating during operation about a Rotationsachslinie grinding pad on which the workpiece to be sanded underside a planar shape exhibiting abrasive is fastened, wherein the sanding pad has air passage openings, so that by means of a suction device air from the bottom of the sanding pad ago can be sucked through the flow openings and a subsequent airway.

From the DE 2005 011 659 U For example, a grinder is known that exhibits all of the above features.

Such grinders are well known. In this case, the sanding pad usually has distributed over its surface arranged through openings, through which the dust air, in which the resulting in the workpiece machining dust particles are sucked off and fed to a dust collector mounted on the sander, for example in the form of a filter bag, or in a separate, connected to the grinder via a suction hose vacuum cleaner can be arranged with a dust separator downstream in the flow direction vacuum generator.

Motor-driven hand grinders are also used for sanding building ceilings, so you have to work overhead. Such grinding devices are usually equipped with a rod-like elongated retaining element on which they can be held by the user up against the ceiling.

When trained in the above-mentioned grinding device occurs depending on the number and arrangement of the passage openings during operation when held against the ceiling sanding pad on the underside of a negative pressure, so that an upward suction arises, so to speak, the grinder for the user makes it easier. This is done with simultaneous extraction of the resulting dust particles during grinding.

However, this suction effect can interfere with sanding other surfaces than ceilings, such as when sanding walls.

In the from the DE 2005 011 659 U known grinder, this suction effect can be adjusted by an additional opening with a variable cross section in the suction hood. This variable opening allows the entry of false air in Absaugspalt between the sanding pad and the suction hood, whereby the suction effect can be reduced.

The present invention is therefore an object of the invention to provide for the adjustment of the suction effect an alternative solution.

This object is achieved by a grinding device according to claim 1, wherein between the outer periphery of the sanding pad and the suction hood, an annular circumferential suction gap is formed, which is connected to a second airway, so that air can be sucked through the Absaugspalt and the second airway, and that an adjustable between two positions adjusting device is present, which is assigned to either two airways, so that in each of the two positions one of the airways is free and the other airway is shut off, or only the associated with the second airway, so that in the two positions at free first airway of the second airway is free or shut off.

In this way, a suction not only through the air passage openings and the first airway but also on the outside of the outer periphery of the sanding pad by said suction, which is bounded radially outwardly from the suction hood, and the second airway is possible. The use of suction hood of this type is known per se.

If the second air path is blocked, only the suction via the passage openings and the first air path is effective, so that the sanding pad and with this the craft machine is sucked to the surface to be ground. This mode is therefore used especially when grinding ceilings.

If, on the other hand, you are working with a free second airway, there is no suction effect at all with the first airway shut off and, with the first airway still free, a greatly reduced, no longer disturbing intake force. This operating mode is therefore preferably used when grinding a building wall or the same area.

Advantageous embodiments of the invention are specified in the subclaims.

Figuren 1 und 2

eine erste Ausführungsform des erfindungsgemäßen Handschleifgerätes im Längsschnitt in zwei Betriebszuständen, wobei in Figur 1 der erste Luftweg frei und der zweite Luftweg abgesperrt und in Figur 2 der erste Luftweg abgesperrt und der zweite Luftweg frei ist,

Figuren 3 und 4

eine zweite Ausführungsform des erfindungsgemäßen Handschleifgerätes in der gleichen Darstellungsweise wie in den Figuren 1 und 2, wobei der erste Luftweg in beiden Betriebszuständen frei ist, während der zweite Luftweg in Figur 3 abgesperrt und in Figur 4 frei ist,

Figuren 5 und 6

ein weiteres Ausführungsbeispiel des erfindungsgemäßen Handschleifgerätes in den Figuren 1 bis 4 entsprechender Darstellungsweise, wobei, wie im Falle der Figuren 3 und 4, der erste Luftweg in beiden Betriebszuständen frei ist, während der zweite Luftweg im Betriebszustand der Figur 5 ebenfalls frei und im Betriebszustand der Figur 6 abgesperrt ist, und

Figur 7

die für alle Ausführungsbeispiele geltende Draufsicht auf die Unterseite des Handschleifgerätes.

Hereinafter, embodiments of the invention will be explained with reference to the drawing. Each shows in a highly schematic way:

Figures 1 and 2

a first embodiment of the hand grinder according to the invention in longitudinal section in two operating states, wherein in FIG. 1 the first airway free and the second airway closed off and in FIG. 2 the first airway is closed off and the second airway is free,

FIGS. 3 and 4

a second embodiment of the hand grinder according to the invention in the same representation as in the Figures 1 and 2 , wherein the first airway in both operating states is free, while the second airway in FIG. 3 locked off and in FIG. 4 free is,

FIGS. 5 and 6

a further embodiment of the hand grinder according to the invention in the FIGS. 1 to 4 corresponding representation, whereby, as in the case of FIGS. 3 and 4 , The first airway is free in both operating conditions, while the second airway in the operating state of FIG. 5 also free and in the operating condition of the FIG. 6 is closed off, and

FIG. 7

the valid for all embodiments plan view of the underside of the hand grinder.

In all three embodiments are of the respective hand grinder 1a; 1b; 1c, only the parts of interest in the present case are shown schematically. Here, in all embodiments, the same principle of generating a respective grinder against the workpiece, in this case a building ceiling 2, sucking Suction realized, each additionally a further Staubabsaugmöglichkeit is available.

It should be noted in advance that the same reference numbers are used in all embodiments for corresponding parts.

The respective hand grinder 1a 1b; 1 c is powered by a motor and is used for grinding building ceilings 2, but it can also be used for sanding building sidewalls or other surfaces.

To the grinder 1a; 1b; 1c to hold against the ceiling 2, it may be provided with a not shown, rod-like elongated support member which is gripped by the user. However, the grinder may also comprise a handgrip assembly formed from or disposed on its device housing, such that the rod-like elongate retainer is not necessarily required when the user can reach the surface to be sanded with the grinder held by him on the handle assembly.

Each illustrated hand grinder 1a; 1b; 1c has a grinding plate 4 rotating during operation about a rotation axis line 3. The sanding pad 4 is detachably attached to an output shaft 5 whose center line is the axis of rotation axis 3. The drive takes place by means of a drive motor 6, in particular an electric motor, via a drive shaft 7, which can be formed by the motor shaft, and via a mechanical clutch or a transmission 8, expediently a motor speed to the smaller grinding disc speed reducing reduction gear, between the drive shaft. 7 and the output shaft 5.

At the workpiece to be ground, in this case the building ceiling 2, facing bottom 11 of the grinding plate 4 is a flat shape exhibiting abrasive 9, also called abrasive sheet, interchangeably attached. For detachable attachment of the abrasive 9 is expediently provided over the contact surface between the sanding pad 4 and abrasive 9 extending adhesive device in the form of a Velcro fastener. The grinder 1a; 1b; 1c is held against the building ceiling 2 with the abrasive 9 fastened to the sanding pad 4, so that the abrasive 9 grips the building ceiling 2 in a sanding manner and carries out a material removal there.

In the figures, a gap is drawn between the abrasive 9 and the building ceiling 2. In reality, however, the abrasive 9 is applied to the building ceiling 2. The gap was drawn only for the sake of clarity, in order to be able to indicate the existing despite the plant during operation air flow between the abrasive 9 and the building ceiling 2 by the arrows.

The sanding pad 4 has a suction recess 10 that is coaxial with the axis of rotation 3 and that is inserted into the sanding pad 4 from the sanding pad bottom 11. The abrasive 9 includes a suction passage 10 corresponding passage opening 21, so that the Absaugausnehmung 10 remains uncovered. The Absaugausnehmung 10 is covered by one of the sanding pad top 12 facing and the bottom of Absaugausnehmung 10 forming cover wall 13 of the sanding pad 4, which is formed by a sanding pad upper part 14 of rigid material over which the sanding pad 4 is connected to the output shaft 5 ,

The cover wall 13 includes a plurality of air passage openings 15, through which the Absaugausnehmung 10 is connected to a arranged above the sanding pad 4 space 16 in the housing of the grinder, which belongs to a first air passage 17.

In this way, by means of at least one suction device 18, 19 during operation, air can be sucked out of the suction recess 10 through the air passage openings 15 into the first air path 17.

The aspirated air contains dust particles that accumulate during grinding, so that it is dusty air. The extracted dust air is therefore guided to a dust collector 22, which may be arranged on the grinder, in the simplest case, for example, a filter bag, or externally, in particular in a with the grinder via a suction hose 23 connectable vacuum cleaner 24 is arranged. The vacuum cleaner could also be attached directly to the grinder. The dust particles contained in the dust air are deposited on the dust collector 22. The air freed from the dust particles is blown into the environment.

The suction device can be formed by a suction blower 25 arranged downstream of the dust separator 22 in the flow direction ( FIGS. 1 . 3 . 5 and 6 ). Alternatively or in addition to the suction fan 25 may be arranged on the drive shaft 7, a suction fan 26, which is associated with at least the first airway 17.

It is understood that the suctioned air leading rooms, channels, etc., and the Sauggebläserad 26 are sealed so that no air leakage occur and the extracted air can not get to parts of the grinder, which are sensitive to dust. Accordingly, for example the space 16 into which the air passing through openings 15 of the sanding pad 4 passes air, be surrounded by a fixed neck portion 27 of the grinder housing, which is sealed by means of an example formed by a lip seal ring seal 28 against the rotating sanding pad 4. Furthermore, it can be seen from the drawing that the output shaft 5 extending through the space 16 is supported by means of a sealed bearing 29 which creates a seal of the space 16 at the point of entry of the output shaft 5 into the space 16.

Since the Sauggebläserad 26 is disposed on the motor-side drive shaft 7, it rotates in the case of a arranged between the drive shaft 7 and the output shaft 5 reduction gear 8 at a higher speed than the sanding pad 4, so that you get a correspondingly high suction.

In the embodiments, a plurality of air passage openings 15 are arranged distributed in a ring around the output shaft 5 around.

The Absaugausnehmung 10 is enclosed by a ring portion 20 of the grinding plate 4. The suction opening 10 facing inner peripheral wall 30 of the ring portion 20 is formed closed. Furthermore, the ring portion 20 is connected in the axial direction on the one hand tight with the sanding pad upper part 14 and on the other hand, on its underside, the fastening means for securing the abrasive 9. In this way it is ensured that the suction 10 except at the bottom of the sanding pad and the air passage openings 15 is sealed as far as possible. Furthermore, the abrasive 9 is in operation on the building ceiling 2, so that only little air from the environment in radial direction between the abrasive 9 and the building ceiling 2 passes through to Absaugausnehmung 10. The air flow is shown symbolically by the arrows.

In this way, during operation, when the air is sucked out of the suction 10, in the Absaugausnehmung 10 a negative pressure, so that the suction device 1a; 1b; 1c directed towards the building ceiling 2 suction force is exerted, which relieves the grinder upwards against the building ceiling 2 holding user.

Simultaneously with this effect of the suction of the grinder to the building ceiling 2 is obtained a suction of the reaching into the Absaugausnehmung 10 dust particles.

The resulting in the Absaugausnehmung 10 vacuum remains substantially constant during grinding. The pressure drop from the ambient atmospheric pressure to the negative pressure in the suction 10 takes place in the radial direction over the annular abrasive 9 away.

The lower side 11 of the sanding plate 4 forming underside of the ring portion 20 is formed closed, so there is an optimal pressure drop over the radius of the ring portion 20 away as far as possible.

The ring portion 20 extends radially outward to the outer periphery of the grinding plate 4, so that it forms its outer periphery. The ring portion 20 further consists of elastically yielding material, in particular foam plastic. The abrasive 9 is supported during operation on this ring section 20 on existing of rigid material sanding pad upper part 14. Due to the elastic yielding training the abrasive element 9 bearing ring section 20 nestles the abrasive 9 also on bumps in the building ceiling 2 at.

The suction force exerted on the grinder is proportional to the area of the suction recess 10. This should therefore be as large as possible if a large suction force is desired. The illustrated Absaugausnehmung 10 therefore has in plan view of the sanding pad bottom 11 a circular disk-shaped shape, which is consistently open.

The sanding pad can also be formed without the suction recess 10. In this case, the passage openings pass through the sanding pad from its top to its bottom. Such a sanding pad has instead of the ring portion 20 a - from the passage openings - continuous sanding pad lower part of elastically yielding material, in particular foamed plastic, which is connected to the illustrated embodiments according to fixed with a sanding pad upper part of rigid material and at Loops on this supports. It is also important in this variant, not shown, that the underside of the sanding pad forms an air passage openings enclosing, closed trained annular surface, so that a corresponding effect as with the bottom of the ring section 20 results.

In any case, one can optimize the number of the passage opening of the sanding plate and their arrangement with respect to the described suction effect.

It is understood that in the variant just described, the abrasive has a hole pattern corresponding to the passage openings of the sanding plate.

The sanding pad 4 may be surrounded by a suction hood 32 having a larger diameter than the sanding pad 4, so that an annular circumferential gap 33 is formed between the outer circumference of the sanding pad 4 and the suction hood 32. The suction hood 32 may, on its operation during operation, be gripped by the workpiece to be ground, i. the building ceiling 2 facing bottom a sealing brush ring 37 or the like, would be possible, for example, a flexible, circumferential sealing lip, have. The brush ring 37 is in operation on the building ceiling 2 and causes a seal.

The gap 33 forms a suction gap, which is connected to a second air path 34, so that air can be sucked through the suction gap 33 and the second air path 34. This represents a further possibility of dust extraction, which also takes place by means of the at least one suction device 18, 19, specifically off the passage openings 15 in the sanding pad 4.

In this context, an adjustable between two positions Verstelleinrichung 35 is provided, which is assigned to either two airways 17, 34 ( Figures 1 and 2 ), so that in each of the two positions one of the airways is free and the other airway is shut off, or is assigned only to the second airway 34 ( FIGS. 3 to 6 ), so that in the two positions with free first airway 17 of the second airway 34 is free or shut off.

In this way, the grinder from the "suction" in which the grinder is sucked to the workpiece to be sanded, be switched to a "normal operation" in which no or only a very small suction to the workpiece. The user can therefore, depending on the requirements either in Ansaugbetrieb or in normal operation work. Normal operation is suitable, for example, for grinding vertical walls or floors. Also in normal operation, a dust extraction, by the second airway 34. The extracted via the second airway 34 dust air is also fed to the dust collector 22.

The FIGS. 1 . 3 and 5 show the respective grinding device 1a; 1b; 1c in the operating mode "suction mode". In the Figures 2 . 4 and 6 the respective device is shown in the operating mode "normal operation".

In the grinding devices 1a and 1b according to FIGS. 1 to 4 The first airway 17 and the second airway 34 merge to form a common airway 36 leading to the dust collector 22. However, the two air paths 17 and 34 can also be separated from each other to the dust separator 22, as in the grinding device 1c according to the FIGS. 5 and 6 the case is.

When out of the Figures 1 and 2 resulting grinder 1a, the adjusting device 35 is assigned to both airways 17 and 34, so that in the intake position corresponding to the position of the adjusting device 35, the first airway 17 is free and the second airway 34 is shut off ( FIG. 1 ), and in the position corresponding to the normal operation of the adjusting device 35, the first airway 17 is shut off and the second airway 34 is free ( FIG. 2 ). In this case, the adjusting device 35 is in the region of the junction of the two air paths 17 and 34th

In the case of the grinding apparatuses 1b and 1c, the adjusting device 35 is assigned only to the second air path 34, so that it is shut off (intake operation according to FIGS Figures 3 and 5 ) or free (normal operation according to the FIGS. 4 and 6 ). In the grinding apparatuses 1b and 1c, the first air path 17 is independent from the position of the adjusting device 35 is always open, so that even in normal operation air flows through the first air passage 17. However, it is a relatively small amount of air, so that the suction effect practically eliminated.

In the illustrated embodiments, the adjusting device is formed by a pivoting flap. However, the adjustment could also be formed by a slide.

In the case of the grinder 1a, the arrangement may be such that in the first airway 17 shut-off position of the adjusting device 35 (FIG. FIG. 2 ) of the adjusting device 35 from the sanding pad 4 facing region of the first air path 17 is connected to the outside atmosphere. In order to counteract possible misunderstandings when viewing the drawing, it is pointed out that in the case of the sanding device 1a the area 38 is connected to the outside atmosphere. In this way, not only the air extraction is interrupted by the first air passage 17 but conversely creates an opposite air flow through the first air passage 17, the air passage openings 15 and between the abrasive 9 and the workpiece through radially outward, so located on the underside of the abrasive 9 Dust particles migrate radially outward and there pass through the Absaugspalt 33 in the second air path 34 and are deposited together with the sucked from the outside radially into the suction gap 33 dust particles in the dust collector 22.

Between the embodiments of the Figures 1 and 2 on the one hand and the FIGS. 3 and 4 On the other hand, there is the difference that in the grinding device 1a, the suction device 18 of a suction blower downstream of the dust separator 22 25 is formed, while in the case of the grinder 1b, the suction device 19 is formed by the seated on the drive shaft 6 Sauggebläserad 26, which is here associated with two air paths 17, 34.

In the grinding device 1c, in which the two air paths 17 and 34 run separately to the dust, both the first air path 17, sitting on the drive shaft 6 Sauggebläserad 26 and the dust separator 22 downstream suction fan 25 is present.

As already mentioned, the grinders are only shown very schematically. The air guide can therefore also be done differently than shown in detail, as far as the described principles are met.

The different air flows are each characterized by arrows.

Finally, it should be noted that the suction hood 32, seen from the gap 33, is sealed to the grinder housing.

Claims (11)

1. Motor driven hand-operated grinding tool with a grinding plate rotating during operation around an axis of rotation line, on whose lower side facing the worksurface to be ground flat-shaped grinding means can be attached, wherein the grinding plate has air passages, so that air can be sucked by a vacuum device from the lower side of the grinding plate through the passages and an adjoining airway, the grinding plate (4) being surrounded by a suction hood (32) which has a larger diameter than the grinding plate (4), so that a suction gap (33), running around in a ring, is formed between the outer circumference of the grinding plate (4) and the suction hood (32), characterized in that the suction gap (33), running around in a ring, is connected to a second airway (34), so that air can be sucked through the suction gap (33) and the second airway (34), and characterized in that there is present adjustable between two positions an adjusting device (35), which is either associated with both airways (17, 34), so that in each of the two positions one of the airways (17, 34) is open and the other airway is blocked, or is only associated with the second airway (34), so that in both positions, when the first airway (17) is open, the second airway (34) is open or blocked.
2. Hand-operated grinding tool according to claim 1, characterized in that when the first airway (17) is blocked the area, facing the grinding plate (4) seen from the adjusting device (35), of the first airway (17) is connected to the outside atmosphere.
3. Hand-operated grinding tool according to claim 1 or 2, characterized in that, when the adjusting device is associated with both airways, the first airway (17) and the second airway (34) unite into a common airway (36) on the adjusting device and, when the adjusting device is only associated with the second airway (34), in the suction direction after the adjusting device (35).
4. Hand-operated grinding tool according to any one of claims 1 to 3, characterized in that the adjusting device (35) is formed by a pivoting flap.
5. Hand-operated grinding tool according to any one of claims 1 to 3, characterized in that the adjusting device is formed by a slide.
6. Hand-operated grinding tool according to any one of claims 1 to 5, characterized in that the air passages (15) are arranged in a ring around the axis of rotation line (3).
7. Hand-operated grinding tool according to any one of claims 1 to 6, characterized in that the lower side of the grinding plate forms a ring face, which has a closed configuration, surrounding the air passages (15).
8. Hand-operated grinding tool according to any one of claims 1 to 7, characterized in that the grinding plate (4) contains a suction recess (10) coaxial to the axis of rotation line (3), which is embedded into the grinding plate (4) from the grinding plate lower side (11) and is covered by a cover wall (13) facing the grinding plate upper side (12), containing the air passages (15), wherein the suction recess (10) is enclosed by a ring part (20) of the grinding plate (4), forming the grinding plate lower side, whose inner periphery wall (30) facing the suction recess (10) has a closed configuration and which in the axial direction is closely connected to a grinding plate upper part (14) forming the cover wall (13).
9. Hand-operated grinding tool according to any one of claims 1 to 6, characterized in that the suction recess (10), viewed from above onto the grinding plate lower side (11), has a circular shape.
10. Hand-operated grinding tool according to any one of claims 1 to 9, characterized in that it exhibits an engine-side drive shaft (7) and a grinding plate-side drive shaft (5) driven by the latter via a reduction gearbox (8) and characterized in that a suction fan wheel (26) associated at least with the first airway (17) sits on the drive shaft (6).
11. Hand-operated grinding tool according to any one of claims 1 to 10, characterized in that it is designed as a grinding tool for ceilings.

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