EP0212062A1 - Planar face-grinding machine - Google Patents

Abstract

The invention relates to a flap disc, in which grinding flaps overlap each other like roof tiles along the peripheral zones of a circular disk-shaped base plate and are advantageously clamped in with the aid of tongues. The grinding lamellae are further anchored in the base plate in that thickenings are applied on one or both sides along their rearward edge region. The anchoring can also consist in the fact that the grinding flaps have one or more slot-shaped recesses in their edge area, through which tongues or tongue sections are pushed.

Description

The invention relates to a flap disc, in which along the circumferential zone of a circular disk-shaped flexible base plate, grinding flaps are arranged to overlap one another like a roof tile and can be clamped and project through radial slots in the circumferential zone.

Flap flap face grinding wheels can be used in a variety of ways. Preferably, such lamellar flap discs are used in so-called angle grinders. However, such lamella flap face grinding wheels can also be used in drilling machines or other grinding devices.

A preferred area of use for a lamella flap face grinding wheel is the smoothing and plastering of weld seams and welding points. Such flap-flap face grinding wheels can be used for roughing and polishing at the same time, without requiring different wheels or grits. A particularly good surface quality can thus be achieved with the aid of a single tool. However, the lamella flap disc grinding discs in question are also suitable for other work such as deburring, faceting, rust removal or removal of old colors. Various materials such as steel, stainless steel, non-ferrous metals, aluminum, hard plastics, artificial stones, natural stones, wood or filler can be processed.

In the known flap discs, the base plate consists of a plastic material. In addition to plastic, vulcanized fiber pressed cardboard has also been used as material for the round plate in the past. In the base plate, grinding lamellae are either inserted into existing recesses and glued with synthetic resin, or the grinding lamellae are glued to the plastic body of the base plate. It must be ensured that when the grinding flaps are attached to the plastic body of the base plate, the grinding flaps are brought into an arrangement required for the grinding or sanding effect, in which the grinding flaps overlap each other like a scale or roof tile.

Although good work results can be achieved with the known flap discs, there have also been disadvantages in practice. For example, it has been shown that the plastic base plates can break apart when subjected to a corresponding load. Furthermore, it has so far not been ruled out that even with careful processing, individual grinding lamellae could be thrown out of their fastening during the grinding process.

The required elasticity of the plastic base plate generally only results from the absorption of a certain amount of moisture. It was therefore necessary to store a plastic base plate for several weeks in an environment that allowed the required moisture to be absorbed. Due to different climatic conditions, the Storage process, however, essentially incalculable, so that discs with insufficiently defined elasticity were created. As a result, it could happen that a plastic base plate broke due to the loads at high speeds or heavy workload, which created a considerable risk of accident.

There were also difficulties in resin bonding, which was used to bond the abrasive flaps in the plastic base plate. It has namely been shown that such a strong heating can occur in operation with a corresponding workload that the adhesive softens and individual slats or packs of slats can thus be thrown out. This also created a certain risk of accidents.

A flap face grinding wheel of the type mentioned is known from US Pat. No. 3,616,581. This grinding wheel consists of a completely rigid metallic inner wheel with an opening in the center, around which a ring with an internal thread is concentrically placed for screwing with a spindle attached to a grinding tool. The inner disk is embedded at its outer edge in a circular outer disk made of plastic, which has the radial slots for receiving the grinding lamellae. To operate this grinding wheel, a completely rigid clamping flange is necessary, which must be placed on the tool spindle in front of the grinding wheel. The grinding wheel equipped with grinding flaps, which partially protrude from the slots on the side facing away from the workpiece, is then screwed onto the spindle, the peripheral edge of the inner wheel against one another a raised rubber edge is clamped on the outer circumference of the clamping flange. The lamella sections in between are clamped in the beginning of the slots. The lamellae are therefore not clamped in the outer area of the grinding wheel.

This flap disc has the disadvantage that it can only be used with an individually adjusted clamping flange, and that the grinding flaps can only be jammed in cooperation with a grinding tool, the spindle thread of which must correspond to the grinding wheel thread. A further disadvantage is that the grinding flaps are only held at one end, the reliability of the clamping being dependent on the care of the operator, who clamps the grinding wheel. Another disadvantage is that the rubber coating of the clamping flange is subject to wear, so that the clamping can decrease with increasing use. In order to generate the required high contact pressure, which is essential to keep the grinding flaps over a relatively small pressing surface, the inner disk and the clamping flange must be rigid. This means that the grinding wheel must be rigid in its interior and does not have the flexibility desired in use. A further disadvantage is that the operator, when placing a grinding wheel on the clamping flange, must ensure that the protruding ends of the grinding flaps are arranged and aligned uniformly in the clamping area, in order to avoid that individual lamellas are applied and the jamming of other grinding lamellas is no longer guaranteed.

The invention has for its object to provide a basic dish for a Lamellar end grinding wheel, which ensures particularly high operational reliability with simple production.

To achieve this object, the invention provides that the base plate is designed as a sheet metal disc, and that the grinding lamellae are held by clamping at the edges of the radial slots.

According to the invention, the great advantage and the essential technical progress can be achieved that, with a low weight, such a high strength of a grinding wheel arrangement can be achieved that the operational reliability is extremely high even at extremely high speeds. On the one hand, it is ensured according to the invention that the base plate has such a high strength and stability that the previous risk of breaking apart has been completely eliminated. In addition, according to the invention such a secure attachment of the grinding flaps in the base plate has been achieved that it is practically impossible to throw a grinding flap out of its holder during operation even at very high speeds.

The base plate according to the invention can also withstand considerable loads during operation, in particular also flex loads, without being damaged.

Furthermore, the work with the base plate according to the invention also proves to be advantageous because it is nevertheless relatively light in weight with very good strength and stability. Also essential is the advantage which is achieved in that practically every risk of breakage and thus also every risk of accident is reliably excluded.

An advantageous embodiment of the invention provides that the clamp is formed by at least one tongue, and that the tongue is formed on the edge of a radial slot.

A preferred development of the invention is that the tongues are divided into several tongue sections.

Furthermore, it can be advantageous that tongues are mutually offset on both opposite edges of the slots.

According to an advantageous development of the invention, it is provided that the tongues have embossing points projecting counter to the opening direction. This can further increase the reliability with which the grinding flaps are attached to the base plate.

A particularly simple device-technical embodiment of the embossing points results from the fact that the embossing points are angled and sharp-edged edges forms are. If the tongues are pressed into the main level of the base plate by a suitable tool after the grinding flaps have been inserted, the grinding flaps are extraordinarily firmly and permanently anchored to the base plate.

A particularly preferred development of the subject matter of the invention provides that a support plate is arranged on the side of the base plate facing away from the working surface, that the peripheral edges of the base plate and the support plate are firmly connected to one another and that the rear ends of the grinding flaps are fixed between the base plate and the support plate are clamped. In this way, a base plate arrangement is created, which is not only characterized by an extraordinarily high dimensional stability and flexing stability, but also offers the possibility of anchoring the grinding flaps easily and at the same time reliably in the base plate, namely by pressing the base plate and the support plate against each other, after they are firmly connected to each other in the peripheral area.

The object of the invention is alternatively achieved in that each grinding lamella is provided with an anchor at its rear end.

This measure is based on the idea of designing the naturally flat grinding lamellae in such a way that their shape supports a clamping effect. This solution therefore has the advantage that a disc arrangement is obtained which is not only characterized by an extraordinarily high dimensional stability and flexing stability, but which also offers the possibility of fastening the grinding flaps easily and at the same time in a reliable manner by the manufacturer. However, this solution is also characterized by all the advantages which have already been listed above in connection with the other solution of the invention.

An advantageous development of this solution according to the invention is that the anchoring is designed as a thickening at the rear end of the grinding flap. This has the advantage that the thickening is supported when tensile forces occur at the slot edges or against the end face of a tongue or is pushed between the base plate and a tongue and wedged there.

Another advantageous embodiment of the anchoring consists in providing at least one recess in the rear edge region of the grinding flap, through which a tongue or at least one tongue section can be pushed. This anchoring has the advantage that the grinding flap is hooked in over a relatively large area.

It can also be advantageous that there are two laterally open recesses for anchoring, in which the end faces of the relevant base plate slot engage.

If the associated tongue is additionally divided into a plurality of tongue sections, it is possible both to support the grinding lamella between the base plate and the tongue sections, and to hang the grinding lamella in one of the tongue sections.

Instead of tongues for engaging in the recesses of the grinding flaps, it can be advantageous for a flat, circular-arc-shaped band to be pushed through the recesses of a plurality of grinding flaps lying next to one another.

The grinding lamellae are also advantageously fastened in that they are glued to the base plate.

• Figur 1 zeigt eine perspektivische Darstellung eines Winkelschleifers mit einer erfindungsgemäßen Fächerstirnschleifscheibe;
• Figur 2 zeigt eine schematische Ansicht eines anhand der folgenden Figuren in mehreren Varianten beschriebenen Grundtellers, der teilweise mit Schleiflamellen bestückt ist;
• Figur 3 zeigt einen Schnitt durch den in der Fig. 2 dargestellten Grundteller (erstes Beispiel) und
• Figur 4 zeigt eine schematische Teilansicht des Grund­tellers nach Fig. 3 zur Veranschaulichung der Prägestellen an den Befestigungslaschen des Grundtellers für Schleiflamellen.
• Figur 5 zeigt einen Schnitt durch einen Grundteller (zweites Beispiel);
• Figur 6 zeigt schematisch einen Querschnitt entlang der Umfangslinie eines Grundtellers (drittes Beispiel);
• Figuren 7 bis 9 zeigen jeweils schematisch Einzelheiten einer Schleiflamelle,
• Figuren 10 bis 12 zeigen jeweils schematisch eine Ansicht einer Schleiflamelle;
• Figur 13 zeigt eine schematische Teilansicht eines Grundtellers (viertes Beispiel) zur Veran­schaulichung der Zungen und
• Figur 14 zeigt schematisch einen Querschnitt entlang der Umfangslinie durch einen weiteren Grund­teller (fünftes Beispiel).

In the following, the invention is further described on the basis of several exemplary embodiments shown in figures.

• Figure 1 shows a perspective view of an angle grinder with a flap disc according to the invention;
• FIG. 2 shows a schematic view of a base plate described in several variants on the basis of the following figures, which is partly equipped with grinding flaps;
• Figure 3 shows a section through the base plate shown in Fig. 2 (first example) and
• FIG. 4 shows a schematic partial view of the base plate according to FIG. 3 to illustrate the embossing locations on the fastening tabs of the base plate for grinding flaps.
• Figure 5 shows a section through a base plate (second example);
• Figure 6 shows schematically a cross section along the circumference of a base plate (third example);
• FIGS. 7 to 9 each show schematically details of a grinding flap,
• Figures 10 to 12 each schematically show a view of a grinding flap;
• Figure 13 shows a schematic partial view of a base plate (fourth example) to illustrate the tongues and
• FIG. 14 schematically shows a cross section along the circumferential line through a further base plate (fifth example).

In Fig. 1, an angle grinder 10 is illustrated in a perspective view, which is equipped with a lamellar grinding wheel, which can also be referred to as a flap face grinding wheel. The grinding wheel is designed such that on a base plate 11 made of metal, preferably of an aluminum alloy (for which the five examples are described below), grinding flaps 13 are attached, which are arranged one above the other in the manner of scales and roof tiles. The Sanding flaps 13 are attached to the base plate 11 as follows:

First, radial slots 12 are made in the outer circumferential area of the base plate 11, which is basically in the form of a circular disk, as schematically illustrated in FIG. 12 tongues are then pressed on like gills or blinds in the areas next to the radial slots. In this way, oblique through openings are created, into which the rear ends of the grinding flaps 13 can be inserted. Thus, already in this manufacturing phase, the grinding flaps 13 have the preferred direction that is necessary for the later operation. After the grinding flaps 13 have been pushed through the radial slots 12, the tongues are pressed together again from the rear side of the base plate 11. As a result, the grinding flaps 13 are firmly anchored in the base plate 11.

For stiffening, the base plate 11 can be equipped with a stiffening bead 30, which is particularly suitable for heavy workloads, i.e. Walk stress has a favorable effect on the dimensional stability of the base plate 11.

3 illustrates in a section through the base plate acc. Fig. 2, the grinding lamella 13 in its fully attached to the base plate 11 position. 3, the base plate 11 has tongues 14 on its side facing away from the work surface provided, which are each attached to the edge of the slots 12. 3 shows the tongues 14 in the state in which they are pressed firmly onto the base plate 11 and the rear part of the grinding flaps 13 inserted through the slot 12 is clamped in each case.

The flap face grinding wheel is thus produced in that a grinding flap is inserted with its rear part through a slot 12 and this is then clamped to the base plate 11 by bending and pressing the associated tongue 14 together.

The attachment of the grinding flaps 13 can be further improved in that embossing points 16 are formed on the tongues 14, as are shown schematically in FIG. 4. These embossing points 16 can be small elevations which are arranged on the side of the tongue 14 which faces the grinding flaps 13. When the tongues 14 are pressed to anchor the grinding lamella 13, the raised embossing points 16 dig into the material of the grinding lamella 13 and thereby form additional anchoring points.

Instead of the embossing points 16 illustrated in FIG. 4, the edges of the tongues 14, for example, could also be slightly angled and formed with sharp edges in the direction of the grinding lamellae 13, so that when the tongues 14 are pressed together, the edge regions become aligned Dig so far into the material of the grinding flaps 13 that secure anchoring of the grinding flaps 13 in the base plate 11 is ensured.

4, an alternative embodiment of the embossing points is also shown schematically in the lower region. Two barbs 19 are formed in the tongue 14, which dig into the material of the grinding flaps 13 with their tips when the base plate is pressed together, the tongues 14 being pressed into the body of the base plate 11.

The barbs 19 are produced in such a way that an angular slot is first made in a tongue 14. The area of the tongue 14 enclosed by the angular slot is then bent out of the tongue plane against the direction in which the tongue is extended relative to the base plate. A grinding flap 13 can be easily inserted into the slot without any appreciable hindrance being caused by the barbs bent out towards the grinding flap. Only when the tongues 14 are pressed firmly onto the grinding flaps 13 do the barbs 19 dig into it Material of the grinding lamella into it and thereby form an extremely reliable fastening of the grinding lamella 13 to the base plate 11.

5 illustrates in a section through the base plate acc. Fig. 2 shows another example. According to the illustration in FIG. 5, the base plate 11 has on its outer circumference a peripheral flange 17 which is bent like a hook relative to the main plane of the base plate 11. This peripheral flange can be flanged, for example. 5, the outer peripheral edge of the base plate 11 is bent more than 90 degrees to form the peripheral flange 17. The peripheral flange 17 gives the base plate 11 an extraordinarily high torsional stiffness, which has a favorable effect on the dimensional stability during operation. The slightly inwardly turned edges of the peripheral flange 17 form a circular opening. Since the diameter of the peripheral flange 17 increases conically towards the main plane of the base plate 11, it also widens from the peripheral edge of the peripheral flange 17 to the main plane of the base plate 11 the space which is enclosed by the peripheral flange 17. It is thus possible to clamp a ring, for example made from a cardboard box, behind the peripheral edge of the peripheral flange 17. Such a ring (not shown) can cover the rear lamella jamming, and this ring can also serve as a label for the grinding wheel according to the invention.

An alternative embodiment of the subject matter of the invention is indicated schematically in FIG. 5 in that the rear region of the base plate 11, i.e. the area facing away from the grinding flaps 13 is covered by a support plate 18. The support plate 18 is shown purely schematically in a partial section in FIG. 5 only in the left area. The support plate can extend over the entire circular disk surface of the base plate 11, of course with the exception of the mounting hole that is always required. If the support plate 18 has a construction and in particular a strength and rigidity which roughly corresponds to the corresponding properties of the base plate 11, an extremely stable and rigid construction is produced. In addition, the support plate 18 can be used to bend the rear ends of the grinding flaps 13 and at the same time to jam them.

In general, it is sufficient to firmly connect the support plate 18 to the base plate 11 in the outer circumferential area, for example to weld, glue or crimp it. In principle, however, it is also possible to have additional fastening on the surface of the two plates points if this should be desirable in view of even greater strength, stability and rigidity.

The support plate 18 can be formed like the base plate 11 in light metal, so that an extremely light, at the same time elastic and very stable construction is created. This construction of the subject of the invention is also largely corrosion-resistant and, as a used waste product, is also environmentally friendly.

6 shows an example of a flap face grinding wheel in a purely schematic cross section along the circumferential line. The grinding flap 13 is provided in its rear edge region 20 with a thickening 24, which is, for example, a tubular, slotted clamp which extends essentially over the entire width of the grinding flap 13. This clamp can be attached to the grinding flap 13, for example by gluing or by riveting.

Fig. 6 clearly does not illustrate the final state of the flap disc, which consists in that the tongue 14 is pressed firmly against the base plate 11, so that there is a clamping of the grinding flap 13. In this state, the tongue 14 presses on the edge region 20, the end face of the tongue 14 also digging into the material of the grinding flap 13. If tensile forces act on the working side of the flap disc on the grinding flap 13, then the Ver spreads Thickening 24 against the tongue 14. In this way, a secure anchoring of the grinding flap 13 is produced and it is prevented from being pulled out of the slot 12. FIGS. 7, 8 and 9 show further examples of anchoring consisting of a thickening at the rear edge region 20 of a grinding flap.

In Fig. 7, the thickening is formed by applying edge strips 25 on both sides essentially along the entire width of the grinding flap. These edge strips 25 can, for example, be made from strong cardboard, from light metal sheet or from another tear-resistant material.

In the example shown in FIG. 8, the thickening consists of beads of adhesive 27 applied on both sides.

FIG. 9 illustrates an example in which the thickening is produced by rivets 28 which are inserted into the grinding flap in some places along the edge of the rear edge region 20. All of these anchors are unique in that they interact positively with the jamming of the grinding flap 13 and prevent them from being pulled out of the base plate.

FIGS. 10, 11 and 12 each show purely schematically advantageous developments of the anchoring which are formed in the rear edge regions 20 of the grinding flaps 13. According to FIG. 10, the anchoring consists of a slot-shaped recess 21 through which a tongue 14 (Fig. 6) or a corresponding tongue section 15 (Fig. 13) can be pushed through. In addition to the recess 21, the grinding flap 13 according to FIG. 11 has clamping areas 26 on the side, the function of which is described together with FIG. 13.

12 shows an example of a grinding flap 13 which, in addition to the recess 21, which is completely surrounded by grinding flap material, has two laterally open recesses 22, so that projecting grinding flap arms 23 are formed. The end faces of the slots provided on the base plate engage in the cutouts 22. The cantilevered arms 23 extend beyond the longitudinal extent of a radial slot in the base plate and ensure additional support by being supported on the base plate.

In the partial reproduction of FIG. 13, an example of a flap face grinding wheel is shown, which has a plurality of tongue sections 15 along the slot 12. A sliding flap 13 according to FIG. 11 is pushed through the slot 12, and the middle tongue section is inserted through the slot-shaped recess 21 thereof. The two outer tongue sections each lie on a clamping area 26 of the grinding lamella 13 and press it against the base plate 11. The grinding lamella 13 is therefore held on the one hand by a jamming of the outer tongue sections and on the other hand by anchoring to the middle tongue section. To hook the grinding flap 13 into the middle tongue section, it can be advantageous if the free end tapers (not shown).

A further example is illustrated in FIG. 14, which shows a section in the circumferential direction approximately along the center line of the base plate 11. According to this embodiment, 12 tongue sections 15 are arranged on one edge of the slot and another tongue section 29 on the other edge. The further tongue section 29 engages in a slot 21 (not shown) in the grinding flap 13, as described in the context of FIG. 13. The representation of this arrangement is purely schematic and does not show the final state in which the tongue sections 15 and 16 are pressed onto the base plate 11.

Regardless of how the grinding flaps 13 are held by clamping in the radial slots, it can be provided as a further measure that the grinding flaps 13 are glued with their rear edge regions 20 on the base plate and / or on the tongues 14 or the tongue sections 15 .

Claims (13)

1. flap face grinding wheel, in which along the circumferential zone of a circular disk-shaped flexible base plate, grinding flaps are arranged to overlap one another in the manner of roof tiles and can be clamped and protrude through radial slots in the peripheral zone, characterized in that the base plate (11) is designed as a sheet metal disk and that the grinding flaps (13) from the edges of the radial slots (12) are held by clamping. 2. flap face grinding wheel according to claim 1, characterized in that the clamping is in each case formed by at least one tongue (14) and that the tongue (14) is integrally formed on the edge of a radial slot (12). 3. flap face grinding wheel according to claim 2, characterized in that the tongues (14) are divided into several tongue sections (15). 4. flap face grinding wheel according to claim 2 or 3, characterized in that on both opposite edges of the slots (12) mutually offset tongues (14) are attached. 5. flap face grinding wheel according to one of the preceding claims 2 to 4, characterized in that each tongue (14) to the grinding lamella foot protruding embossing points (16). 6. flap face grinding wheel according to claim 5, characterized in that the embossing points are designed as angled and sharp-edged edges. 7. flap face grinding wheel according to one of the preceding claims, characterized in that on the side facing away from the working surface of the base plate (11) a support plate (18) is arranged that the peripheral edges of the base plate (11) and the support plate (18) firmly connected are, and that between the base plate (11) and the support plate (18), the rear ends of the grinding flaps (13) are firmly clamped. 8. flap face grinding wheel, in which along the circumferential zone of a circular disk-shaped flexible base plate grinding flaps overlap each other like roof tiles and are arranged such that they can be clamped and protrude through radial slots in the circumferential zone, characterized in that each grinding flap (13) is provided with an anchoring at its rear end. 9. flap disc according to claim 8, characterized in that the anchoring at the rear end is designed as a thickening of the grinding flap. 10. flap face grinding wheel according to one of claims 8 or 9, characterized in that the anchoring consists of at least one in the rear edge region (20) of the grinding flap (13) arranged recess (21) through which a tongue (14) or at least one tongue section ( 15) can be pushed through. 11. flap face grinding wheel according to one of claims 8 to 10, characterized in that the anchoring consists of two laterally open recesses (22) of the grinding flap (13) for engaging the end faces of the slot (12) in question. 12. flap face grinding wheel according to one of claims 8 to 11, characterized in that a flat circular arc-shaped band is pushed through the recesses (21) of a plurality of adjacent grinding flaps (13). 13. flap face grinding wheel according to one of the preceding claims, characterized in that the grinding flaps (13) are glued to the base plate (11).

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