EP2286959B1 - Scrubbing-grinding tool - Google Patents

Description

The invention relates to a snap-grinding tool according to the preamble of claim 1.

Schmpp grinding tools are known in practice in large numbers. Here, the fiber grinding wheels are flexible and releasably mounted on the support plate. The mounting on the support plate is done by a screw-on flange in the Kröpfungsbereich the fiber grinding wheel. For work in which uniform surface structures on the workpiece to be machined must be achieved by means of the roughing and grinding tool, the service life of the fiber grinding wheel is short, for example only about 1 minute. After this time, the abrasive grain of the fiber abrasive disc shows its first signs of wear, whereby the surface of the workpiece to be machined is no longer completely uniform. The fiber grinding wheel is therefore already replaced after this time.

In order to enable a quick replacement of such fiber grinding wheels, a quick-change system has been developed, as in the EP 1 741 515 B1 is shown and described. For the mentioned application fine-grained abrasive grain is used. These fine grains result in a high heat load on the workpiece during grinding. If the material to be ground, for example, is stainless steel or has a low thermal conductivity, tarnish occurs. For this reason, in the aforementioned quick-change system according to the EP 1 741 515 B1 Cooling channels provided in the support plate to achieve a good cooling of the grinding wheel.

If grinding wheels with coarse abrasive are used for rough grinding - as is customary in practice - then there is a risk that the base carrying the abrasive tears. This is especially true when serving as a base for the abrasive serving discs of little solid material.

From the EP 0 750 539 B1 (corresponding DE 695 06 851 T2 ) and the EP 0 617 652 B1 (corresponding DE 692 28 760 T2 ) Abrasive base are known, as they are common practice, which thus consist of a serving as a support or underlay elastically flexible disc on which an abrasive grain is attached by means of a synthetic resin.

From the DE 10 2006 010 366 B3 and the DE 90 17 256 U1 So-called flap discs are known in which the abrasive blades are glued in the usual way to a carrier.

From the EP 1 541 288 A1 a grinding tool having the features of the preamble of claim 1 is known, which has a mounted on a backsheet resin-bonded abrasive grain layer, wherein the backsheet is adhered by means of an adhesive layer on a Supporting substrates. The backsheet can be made of cotton fabric. The Supporting Substrates may consist of a phenolic resin impregnated glass fiber fabric.

From the EP 1 595 645 A1 is a diamond grinding wheel, so no roughing-grinding tool, known, which has a disc on the section of diamond abrasive grain is attached. The disk surface is convex toward the grinding side, with the curvature increasing towards the outer edge of the disk. No justification for the purpose of this increasing curvature can be found in D3. In addition, D3 does not concern a roughing abrasive tool but a diamond wheel that does not have the problems associated with roughing tools.

Out WO 2008/035934 A1 is an abrasive coated abrasive tool known, which is formed as a composite tool and is produced in a single manufacturing process as a flat grinding tool. It has in the middle an opening for receiving the drive shaft of a grinding machine. In an embodiment according to FIG. 1 In this publication, a binder layer has been applied to a vulcanized fibrous substrate and abrasives have been spread. This was dried in an oven and then a second make coat was applied. This is by nature a uniform composite train.

Out DE 88 14 637 U1 For example, there is known an abrasive article comprising a plastic semi-rigid plastic disc having an abrasive coated abrasive fiber disc secured thereto by an adhesive layer on a vulcanized fiber. The weakly cambered, ie convexly curved towards the grinding side plastic plate with fiber grinding disc is firmly connected to a concavely curved counter-plate, wherein the plastic plate and the counter-plate are clamped together by means of a bolt. On the side facing away from the grinding side of the plastic plate For this purpose, a nut is attached, into which the bolt is screwed. Among other things, silicon carbide, ie a ceramic grain, can be used as the abrasive grain.

Out WO 02/074 494 A1 is a grinding tool is known which has a flat support plate on which a grinding wheel is fixed by means of hot melt adhesive. The grinding wheel itself consists of a flexible carrier material, on which the abrasive grain is attached. The flexible grinding wheel projects beyond the edge of the support plate and is convexly curved in this area. In the area of the carrier plate, it is even. It is a tool for smoothing drywall.

The invention has for its object to design a roughing-grinding tool of the generic type so that it has a long service life with simple and inexpensive construction.

This object is achieved in a roughing-grinding tool of the generic type by the features in the characterizing part of claim 1. By sticking the fiber grinding wheel on the support plate has surprisingly revealed that a ripping of the fiber grinding wheel does not occur despite the high loads during rough grinding. This can be explained by the fact that torque occurring during rough grinding does not have to be completely absorbed by the fibers of the fiber disk. There is considerable transfer to the carrier plate. Even with torque overload and when abutting the outer edge of the fiber grinding wheel to a workpiece, it does not break the fiber grinding wheel. So there are no smaller or larger segments of the fiber grinding disc, so that injury to the user are largely excluded. The risk of detaching the grinding wheel From the support plate is further reduced by the fact that the outer grinding area is curved towards the grinding side convex toward the back of the grinding tool. By this measure, the grinding tool can also be used for a short time for face grinding.

The fiber disc is made of vulcanized fiber, a material that has been known for a century and a half and made from cotton fibers. Surprisingly, it has also been found that the roughing and grinding tool is far superior to conventional roughing wheels both in terms of machined mass per unit time and in terms of total machinable mass. This is especially true because Ceramic grain is used as an abrasive.

To be particularly advantageous, it has been found that the grinding wheel with the abrasive coating is slightly convex towards the grinding side. Since such roughing wheels, ie roughing and grinding tools, are used on hand-held grinding machines, an exact angular position of the grinding tool with respect to the surface to be ground is generally not maintained during use. The slight curvature causes no high local surface pressures between the grinding wheel and the workpiece to be machined, with the result of a corresponding tearing of abrasive grain occur. This leads to a considerable increase in the service life or the cutting performance. The further subclaims give advantageous developments again.

Fig. 1

eine erste Ausführungsform eines nicht erfindungsgemäßen Schrupp-Schleif-Werkzeugs in einer Rück-Ansicht gemäß dem Sichtpfeil I in Fig. 3,

Fig. 2

eine Draufsicht auf die Schleifseite des Schrupp-Schleif-Werkzeugs gemäß dem Sichtpfeil II in Fig. 3,

Fig. 3

einen Querschnitt durch das Schrupp-Schleif-Werkzeug gemäß der Schnittlinie III-III in Fig. 1,

Fig. 4

einen Querschnitt durch eine Ausführungsform eines Schnipp-Schleif-Werkzeugs gemäß der Erfindung und

Fig. 5

eine Hand-Schleifmaschine mit einem Schrupp-Schleif-Werkzeug nach der Erfindung im Schleifeinsatz.

Further features, advantages and details of the invention will become apparent from the following description of exemplary embodiments with reference to the drawing. It shows

Fig. 1

a first embodiment of a non-inventive roughing-grinding tool in a rear view according to the viewing arrow I in Fig. 3 .

Fig. 2

a plan view of the grinding side of the roughing-grinding tool according to the viewing arrow II in Fig. 3 .

Fig. 3

a cross section through the roughing-grinding tool according to the section line III-III in Fig. 1 .

Fig. 4

a cross-section through an embodiment of a flick-grinding tool according to the invention and

Fig. 5

a hand grinder with a roughing-grinding tool according to the invention in the grinding insert.

That in the FIGS. 1 to 3 illustrated roughing-grinding tool has a in the usual way from impregnated with phenolic resin and compressed glass fibers existing support plate 1, which has a flat, annular clamping area 2 in the usual way, in which a likewise circular opening 3 for receiving a drive shaft Drive machine is formed. The annular clamping region 2 surrounding the opening 3 is provided with a metal ring 5 on the rear side of the support plate 1 remote from a grinding side 4. The clamping area 2 is adjoined by a cranking area 6, which is likewise of annular design and rises radially to the axis 7 of the carrier plate 1 towards the grinding side 4. At the Kröpfungs area 6, an annular closes Grinding area 8, which is inclined radially to the axis 7 against the cranking area 6, namely radially to the axis 7 outwardly from the grinding side 4 away. This embodiment of a support plate 1 is well known and common.

On the grinding side 4, a fiber grinding wheel 9 is attached. This is a so-called abrasive on a base, which consists of a fiber disk 10 as a support or base and a resin-bonded abrasive coating 11. The fiber disk 10 is made of vulcanized fiber, which is a bound, pressed material based on cotton fibers. The abrasive coating 11 is formed by ceramic grain 11.1, which is produced from a microgranulate by sintering. The microgranules break individually from the respective grain, so that thereby the stability of the ceramic grain 11.1 is significantly increased compared to conventional abrasives. The resin bonded abrasive pad 11 is bonded to the fiber disk 10 in the usual manner. The fiber disk 10 of the fiber grinding wheel 9 is connected to the grinding side 4 of the support plate 1 by means of an adhesive layer 12.

$$\mathrm{R}\mathrm{9}=\mathrm{R}\mathrm{8}$$

The radius R1 of the support plate 1 is - like FIG. 1 can be removed - slightly smaller than the radius R9 of the fiber grinding wheel 9, without the fiber grinding wheel 9 projecting radially to the axis 7 on the outer edge 13 of the support plate 1. The cranking region 6 has a radius R6 from the axis 7 at the transition to the main grinding region 8. The main grinding area 8 of this non-inventive grinding tool has a radius R8 from the axis 7 which is equal to the radius R9 of the fiber grinding wheel 9. For the radii R6 and R8 with respect to the radius R9, the following applies: $$\mathrm{0}.\mathrm{45}\mathrm{R}\mathrm{9}\le \mathrm{R}\mathrm{6}\le \mathrm{0}.\mathrm{7}\mathrm{R}\mathrm{9}$$

$$\mathrm{R}\mathrm{9}=\mathrm{R}\mathrm{8th}$$

The use of the grinding tool takes place in the usual manner at an angle to the axis 7.

As far as in the embodiment according to the invention FIG. 4 the same or similar parts or regions are present as in the embodiment according to the FIGS. 1 to 3 , the same reference numbers are used with a prime. The support plate 1 'consists of a glass cloth impregnated with epoxy resin. He has - as in the embodiment of the FIGS. 1 to 3 - a constant thickness h. The planar annular clamping area 2 'is likewise formed with a circular opening 3' for receiving a drive shaft of a drive machine. The annular clamping region 2 'surrounding the opening 3' is not reinforced with a metal ring in this exemplary embodiment. The curvature region 6 'adjoining the clamping region 2' is likewise of annular design and rises radially to the axis 7 'of the carrier plate 1' towards the grinding side 4 '. The planar clamping region 2 'merges with a radius of curvature r2' in the cranking region 6 '. The cranking region 6 'is adjoined in turn by an annular main grinding region 8', which extends radially to the axis 7 'against the cranking region 6', namely radially to the axis 7 'outwardly from the grinding side 4' is inclined. Seen from the axis 7 'to the outside of the grinding area 8' so from the grinding side 4 'inclined away. Also in the design FIG. 4 is on the grinding side 4 'of the support plate 1' a fiber grinding disc 9 'attached. This is also a so-called abrasive on a base, which consists of a fiber disk 10 'as a support or base and a resin-bonded abrasive coating 11'. The fiber grinding wheel 9 'is thus a self-contained grinding wheel, which could be used, as described above for the prior art according to EP 1 741 515 B1 has been described. It is flexible, so flexible. The structure of the fiber grinding wheel 9 'corresponds to the above to the FIGS. 1 to 3 already described. The abrasive coating 11 'thus has ceramic grain 11.1'. Also in the execution after FIG. 4 is the fiber slice 10 'of the fiber abrasive disc 9' connected to the support plate 1 'by means of an adhesive layer 12'.

As FIG. 4 can be removed, the cranking region 6 'is in the grinding area 8' with a radius of curvature r6 'on. The main grinding area 8 'itself is also curved, slightly convex to the grinding side 4' with a radius of curvature r8 '.

The outer grinding area 15 'adjoining the main grinding area 8' is inclined radially outward away from the grinding side 4 'and convexly curved toward the grinding side 4' with a radius of curvature r15 '.

• 15 mm ≤ r2' ≤ 30 mm und bevorzugt 20 mm ≤ r2' ≤ 25 mm
• 15 mm ≤ r6' ≤ 40 mm und bevorzugt 15 mm ≤ r6' ≤ 20 mm
• 190 mm ≤ r8' ≤ 300 mm und bevorzugt 200 mm ≤ r8' ≤ 250 mm
• 17 mm ≤ r15' ≤ 40 mm und bevorzugt 15 mm ≤ r15' ≤ 20 mm

The curvatures with the radii of curvature r6 ', r8' and r15 'are formed convex to the grinding side 4'; the reason for this is that the use of the roughing and grinding tool takes place in the usual way at an angle to the axis 7 '. The fiber disc 10 'ends - as FIG. 4 is removable - flush with the outer edge 13 'of the support plate 1'. The following relationships apply for the radii of curvature r2 ', r6', r8 'and r15':

• 15 mm ≤ r2 '≤ 30 mm and preferably 20 mm ≤ r2' ≤ 25 mm
• 15 mm ≤ r6 '≤ 40 mm and preferably 15 mm ≤ r6' ≤ 20 mm
• 190 mm ≤ r8 '≤ 300 mm and preferably 200 mm ≤ r8' ≤ 250 mm
• 17 mm ≤ r15 '≤ 40 mm and preferably 15 mm ≤ r15' ≤ 20 mm

The fiber abrasive disc 9 'has a radius R9' from the axis 7 '. The offset area 6 'has a radius R6' from the axis 7 'at the transition to the main grinding area 8'. The main grinding area 8 'has a radius R8' from the axis 7 '.

• 0,45 R9' ≤ R6' ≤ 0,7 R9'
• 0,75 R9' ≤ R8' < R9'

For the radii R6 'and R8' with respect to the radius R9 ', the following applies:

• 0.45 R9 '≤ R6' ≤ 0.7 R9 '
• 0.75 R9 '≤ R8'<R9'

Out FIG. 5 the use of the roughing-grinding tool according to the invention on manual grinding machines 19 emerges. The roughing-grinding tool is mounted on an output shaft 20 of the hand grinder 19, which is inserted through the opening 3 of the grinding tool, so that the axis 7 coincides with the central axis of the output shaft 20. The attachment of the grinding tool on the output shaft 20 by means of a clamping nut 21st

Due to the convex curvature of the main grinding area 8 "towards the grinding side 4 ', it is achieved that during surface grinding of workpieces 22, ie in the main field of application of such grinding tools, even in the case of the unavoidable pendulum movements of the grinding tool, a uniform loading of the abrasive The result of this rough grinding / grinding tool, which is always used on hand-held grinders, is lower wear and thus a longer service life or a higher removal rate of the grinding wheel.
The stronger curvature in the outer grinding area 15 'causes that upon abutting the outer edge 13' of the grinding wheel to an object no detachment of the fiber grinding wheel 9 'together with abrasive coating 11 from the support plate 1' takes place.

Claims (5)

1. Rough grinding tool, consisting

   - of a support plate (1, 1', 1"), which

   -- is concentrically configured with respect to a centre longitudinal axis (7, 7') and

   -- has a centre opening (3, 3') for receiving a drive shaft of a drive machine, and

   -- consist of a glass fabric impregnated with epoxy resin having a constant thickness h,
   and

   - of a fiber grinding disc (9, 9'), which

   -- consists of a fiber disc (10, 10'), with a resin-bound grinding means covering (11, 11'),

   -- has an outer annular grinding region (8, 8') arranged radially with respect to the centre longitudinal axis (7, 7'),

   -- is supported on the support plate (1, 1') without projecting radially with respect to the axis (7, 7') over the outer edge (13) of the support plate (1, 1'),

   -- is glued to the support plate (1, 1') by means of an adhesive layer (12, 12'), and

   -- has a grinding side (4, 4'),

   characterized
   in that ceramic grain (11.1, 11.1') is provided as the grinding means, in that the fiber disc (10, 10') consists of vulcanized fiber,
   in that the grinding region has a main grinding region (8') and an outer grinding region (15') which adjoins radially outwardly with respect to the axis (7') and which grinding region (15') is convex toward the grinding side (4') with a radius of curvature r15',
   in that with regard to the radius of curvature r15' there applies: 17 mm ≤ r15' ≤ 40 mm, and
   in that the main grinding region (8') has an inner radius R6' and an outer radius R8' and the fiber grinding disc (9') has an outer radius R9' wherein there applies:

   0.45 R9' ≤ R6' ≤ 0.7 R9' and

   0.75 R9' ≤ R8' < R9'.
2. Rough grinding tool according to claim 1, characterized in that the grinding region (8', 8") is convex toward the grinding side (4') with a radius of curvature r8'.
3. Rough grinding tool according to claim 1 and 2, characterized in that with regard to the radius of curvature r15' in relation to the radius of curvature r8' there applies: r15' < r8'.
4. Rough grinding tool according to claim 2, characterized in that with regard to the radius of curvature r8' there applies: 190 mm ≤ r8' ≤ 300 mm and preferably 200 mm ≤ r8' ≤ 250 mm.
5. Rough grinding tool according to claim 1, characterized in that with regard to the radius of curvature r15' there applies: 15 mm ≤ r15' ≤ 20 mm.
   Rough grinding tool according to claim 11, characterized in that

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