EP0222969B1 - Surface grinding machine - Google Patents

Abstract

A back plate for a lamellar end grinding wheel is described, in which grinding flaps overlap one another in tile-like manner along the circumferential zone of a circular disc-like back plate. The arrangement is characterized in that the back plate is constructed as a metal plate, to which is fixed a supporting plate and that the grinding flaps are secured between these two plates.

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. Lameia fan front grinding discs of this type are preferably used in so-called angle grinders. However, such lamella fan-type 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 discs in question are also suitable for other work such as deburring, faceting, rust removal or removing old paints. A wide variety of materials such as steel, stainless steel, non-ferrous metals, aluminum, hard plastics, artificial stones, natural stones, wood or filler can be processed.

A flap face grinding wheel of the type mentioned at the outset 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. At its outer edge, the inner disk is embedded in a circular outer disk made of plastic, which has the radial slots for receiving the grinding flaps. 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 being braced against a raised edge provided with a rubber coating on the outer circumference of the clamping flange. The lamella sections in between are clamped in the initial area 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 in 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. The result of this is that the grinding wheel has to be stiff 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 flaps are applied, and therefore that other grinding flaps are not jammed more is guaranteed.

The invention has for its object to provide a flap disc of the type mentioned, in which the clamping of the grinding flaps directly, i.e. regardless of a grinding tool.

This object is achieved in that the base plate is designed as a sheet metal disc and that a support plate is arranged on the side of the base plate facing away from the working surface, that the support plate is firmly connected to the base plate at least on the outer circumference and that the rear ends of the grinding flaps between the base plate and the support plate are firmly clamped.

In this way, a disc arrangement is created, which is not only characterized by an extremely high level of dimensional stability and flexing stability, but also offers the possibility of anchoring the grinding flaps easily and at the same time in a reliable manner by the manufacturer, namely by pressing the base plate and the support plate against each other, after they are firmly connected to one another in the peripheral region.

A further preferred embodiment of the invention provides that the side of the base plate and / or the support plate assigned to the rear ends of the grinding flaps are provided with protruding embossing points for engagement in the grinding flaps. This measure ensures that the grinding flaps are firmly and securely anchored.

This development of the subject of the invention is particularly reliable in that the embossing points are designed as triangular barbs.

In principle, a single embossing point or a single barb would suffice for each grinding lamella to ensure that the grinding lamella in question is attached between the base plate and the support plate in a particularly durable manner. Of course, two barbs can also be provided per grinding flap, or a large number of barbs can be formed in a uniform distribution over the entire surface of the plate be det. When the grinding flaps are pushed into the slots and the support plate is pressed onto the base plate, the tips of the dig. Barbs firmly into the material of the added grinding flaps and deep into it. During operation, those forces which act on the grinding flaps always have the tendency to push the barbs according to the invention even deeper into the material of the grinding flaps. This further improves the attachment of the grinding flaps between the two plates.

If, during operation of the fan-type grinding wheel according to the invention, excessive movement causes the grinding lamellae to move, which would pull these grinding lamellae out of the base plate, the embossing points or barbs dig into the material of the grinding lamella more and more. This increases the anchorage. A particularly simple design of the barbs to achieve the advantages mentioned above is that they consist of a triangular sheet metal part, which are cut out of the material of the base plate or support plate to one side, on which they are bent out of the plate plane.

Furthermore, it can preferably be provided that the support plate has radially extending tongues which are arranged at an incline in the circumferential direction. This measure has the advantage that the individual slats can be pressed along the entire slot by the spring force of the tongues. Another advantage is that the tongues can be produced in a simple manner if the support plate is provided with radial slots and the intermediate sections are rotated against the support plate plane

The firm connection of the support plate and the base plate is preferably achieved in that the peripheral edge of the base plate is bent toward the side facing away from its working surface towards a circumferential flange which is hook-shaped in radial section, and in that the support plate is clamped under the bent edge. In this way, the grinding wheel gets additional rigidity.

Sheet metal, in particular light metal sheet, is used as the preferred material for the support plate.

An advantageous development of the flap disc is that the grinding flaps each have a thickening at their rear ends. These thickenings provide an additional safeguard against the fact that the grinding flaps slip out of their slots in spite of the clamping when in use, when particularly great tensile forces occur in use.

The thickening preferably consists of a clip which extends essentially over the entire width of the grinding flap in question. This clamp can be attached to the grinding flap, for example by gluing or by riveting. It consists of a slotted tubular part, which can be pushed onto the end of the grinding flap and attached by gluing or riveting.

Alternatively, the thickening can be easily produced by attaching rivets along the rear end of the abrasive flap in question. Another effective and easy to produce thickening also results from the fact that an adhesive bead is applied to the grinding flap.

In the event that the support plate is provided with tongues, it can furthermore preferably be provided that the grinding lamellae have at least one slot-shaped recess in their rear areas, which are inserted through the slots. This has the advantage that the tongue or at least a tongue section can be pushed through, so that the grinding flap is hooked on. This recess can be an opening in the grinding flap, which is completely surrounded by grinding flap material. Alternatively or in addition to this, it can also be advantageous that the grinding flaps are provided in their rear areas with projecting arms, into which the end faces of the slots provided in the support plate engage, and which extend beyond the longitudinal extent of the associated slot. As a result, both the grinding flap is supported between the base plate and the support plate, and the grinding flap is hooked into the tongue.

It proves to be advantageous if there is a flat, circular-arc-shaped band between the base plate and the support plate, which is pushed through the recesses of a plurality of abrasive flaps lying next to one another. Several grinding lamellae are suspended from this belt, which are additionally clamped between the support and base plate.

Through these measures, the manufacture of the grinding wheel according to the invention can be carried out with simple means and with little expenditure of time. Nevertheless, you get a grinding wheel, which is a self-contained and independent trading good that can be placed on a grinding tool by itself. In particular, when retrofitting the grinding tool, the operator does not have to take care that he himself clamps the grinding lamella in a reliable manner. Overall, the grinding wheel arrangement according to the invention is characterized in that it is easy to manufacture, works extremely reliably, and that a grinding tool can therefore be converted without problems.

• Fig. 1 zeigt eine perspektivische Darstellung eines Winkelschleifers mit einer erfindungsgemäßen Fächerstirnschleifscheibe;
• Fig. 2 zeigt eine schematische Ansicht eines Grundtellers, der teilweise mit Schleiflamellen bestückt ist;
• Fig. 3 zeigt einen Schnitt durch den in der Figur 1 dargestellten Grundteller;
• Fig. 4 zeigt eine schematische Teilansicht eines Stütztellers zur Veranschaulichung der Prägestellen zur Befestigung für Schleiflamellen;
• Fig. 5 bis 7 zeigen jeweils schematische Ausführungsformen von Schleiflamellen und
• Fig. 8 zeigt schematisch einen Querschnitt entlang der Umfangslinie durch eine Fächerstirnschleifscheibe.

In the following, details are further described with reference to exemplary embodiments shown in the drawings.

• Fig. 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, which is partially equipped with grinding flaps;
• Fig. 3 shows a section through the base plate shown in Figure 1;
• Fig. 4 shows a schematic partial view of a support plate to illustrate the embossing locations for fastening for grinding lamellae;
• 5 to 7 each show schematic embodiments of grinding flaps and
• Fig. 8 shows schematically a cross section along the circumferential line through a flap disc.

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 fan end grinding wheel. The grinding wheel is designed such that grinding flaps 13 are attached to a base plate made of metal, preferably of an aluminum alloy, which are arranged one above the other in the manner of scales and roof tiles. The grinding 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 are illustrated schematically in FIG. 2. In this way, through openings are created into which the rear ends of the grinding flaps 13 can be inserted.

For stiffening, and, as will be described later, to increase the contact surface pressure, the base plate 11 can be equipped with a bead 15, which is particularly suitable for heavy workloads, i.e. Flexing load, has a favorable effect on the dimensional stability of the base plate 11.

FIG. 3 illustrates, in a section through the base plate according to FIG. 1, the grinding flaps 13 in their position completely attached to the base plate 11. According to the illustration in FIG. 3, 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. As shown in FIG. 3, 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, the space which is enclosed by the peripheral flange 17 also widens from the peripheral edge of the peripheral flange 17 to the main plane of the base plate 11. It is thus possible to clamp an annular support plate 18 behind the peripheral edge of the peripheral flange 17. Such a ring creates a jamming of the rear lamella sections.

The rear area of the base plate 11, i.e. the area facing away from the grinding flaps 13 is covered by the support plate 18. The support plate 18 is shown purely schematically in a partial section in FIG. 3 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 by welding, gluing, riveting or flanging. In principle, however, it is also possible to attach additional fastening points to the surface of the two plates, should this be desirable in view of an even higher 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.

As schematically shown in FIG. 4, the fastening of the grinding flaps 13 can be improved further by the fact that tongues 14 with stamping points 16 are formed on the support plate 18. These embossing points 16 can be small elevations which are arranged on that side of the tongues 14 which face the grinding flaps 13. When the support plate 18 and the base plate 11 are pressed together for anchoring 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, for example the edges of the tongues 14 could also be slightly angled and formed with sharp edges in the direction of the grinding lamellae 13, so that when the two discs are pressed in, the edge regions dig into the material of the grinding lamellae 13 so far that a secure anchoring of the grinding flaps 13 between base plate 11 and support plate 18 is ensured.

4, an alternative embodiment of the support plate 18 is also shown schematically in the lower region. Two barbs 19 are formed on the tongue 14 shown below, which dig into the material of the grinding flaps 13 with their tips when the base plate and the support plate are pressed together, the tongues 14 being pressed into the body of the support plate 18.

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 protrudes from the base plate represents is. 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, the barbs 19 dig into the material of the grinding flaps and thereby form an extraordinarily reliable fastening of the grinding flaps 13 between the base plate 11 and the support plate 18.

In order to make FIG. 4 clear, only in the example of the upper tongue 14 is a dashed flap 13 shown in broken lines, which clarifies the assignment of the support plate 18 and the tongues 14 relative to the sanding flaps. The tongues 14 are bent out of the plane of the drawing in the direction of the base plate and the slats 13. They spread out against the grinding flaps 13 and thereby prevent them from being pulled out of the entire grinding wheel.

5, 6 and 7 each show, purely schematically, an advantageous development of the grinding flap 13, which has a slot-shaped recess 21 in its rear edge region 20, which is provided for insertion into one of the radial slots in the base plate (FIG. 5 and Fig. 6) or with several such recesses 21 (Fig. 7). 5, the tongues 16 are inserted through the recesses 21, which need not have an embossing or barb in this case. In this way, the grinding flaps 13 are caught over the recesses 21 and secured against being pulled out.

Alternatively, the tongues 16 can be divided in their longitudinal direction into a plurality of tongue sections (not shown) in order to hold the associated grinding flaps 13 in a combination of clamping and gripping behind. To use grinding flaps, for example according to FIG. 6, the tongues 14 are divided into three tongue sections. The middle train section is inserted through the recess 21 of the relevant grinding flap 13, while the two outer tongue sections press on the laterally adjacent flap sections.

7 shows an example of a grinding flap 13 which, in addition to the recess 21, has lateral recesses 22 so that cantilevered grinding flap arms 23 are formed. The end face of the slots made 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.

Another alternative of a flap face grinding wheel is that between the base plate and the support plate there is a flat, circular-arc-shaped belt (not shown) which is pushed through the recesses 21 by a plurality of grinding flaps 13 arranged next to one another. 8 shows a further 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 in the example shown here is a clip which extends essentially over the entire width of a grinding flap. This clamp can be attached to the grinding flap 13, for example by gluing or by riveting. Fig. 8 clearly does not illustrate the final state of the flap disc, which consists in that the base plate 11 and the support plate 18 are firmly connected and pressed against each other, so that there is a clamping of the grinding flap 13. In this state, the tongue 14 presses against the section 20, the end face of the tongue 14 digging into the material of the grinding flap 13.

Claims (14)

1. Lamellar end grinding wheel (Surface grinding machine), in which along the circumferential zone of a circular disc-shaped flexible back plate (11) grinding flaps (13) are arranged so as to overlap one another in tile-like manner and are fixed there, being passed through radial slots (12) in the circumferential zone, characterized in that the back plate (11) is constructed as a sheet metal plate, that a supporting plate (18) is arranged on the side of the back plate (11) remote from the working surface, that the supporting plate (18) is firmly connected to the back plate (11), at least on the outer circumference and that the rear ends (20) of the grinding flaps (13) are fixed between the back plate (11) and the supporting plate (18).

2. Lamellar end grinding wheel according to claim 1, characterized in that the side of the back plate (11) and/or the supporting plate (18) associated with the rear ends of the grinding flaps (13) are provided with projecting stamping points (16) for engaging in flaps (13).

3. Lamellar end grinding wheel according to claim 2, characterized in that the stamping points (16) are constructed as triangular barbs (19).

4. Lamellar end grinding wheel according to one of the preceding claims, characterized in that the supporting plate (18) has radial tongues (14), which are arranged in sloping manner in the circumferential direction.

5. Lamellar end grinding wheel according to one of the preceding claims, characterized in that the circumferential edge of the plate (11) is bent over towards its side remote from its working surface to form a hook-like circumferential flange (17) in radial section and that the supporting plate (18) is fixed under the bent-over edge.

6. Lamellar end grinding wheel according to one of the preceding claims, characterized in that the supporting plate (18) is made from sheet metal.

7. Lamellar end grinding wheel according to one of the preceding claims, characterized in that each of the rear ends of the grinding flaps (13) is provided with a thickened protion (24).

8. Lamellar end grinding wheel according to claim 7, characterized in that the rear thickened portion (24) comprises a mounted clip extending substantially over the entire width of the particular grinding flap (13).

9. Lamellar end grinding wheel according to claim 7, characterized inthat the thickened portion (24) is formed by rivets, which are fitted along the rear end of the particular grinding flap (13).

10. Lamellar end grinding wheel according to claim 7, characterized in that the thickened portion (24) is formed by an adhesive bead, which is applied to the grinding flap (13).

11. Lamellar end grinding wheel according to one of the claims 4 to 10, characterized in that the grinding flaps (13) have in each case at least one slot-like recess (21) in their rear regions which are passed through the slots (12).

12. Lamellar end grinding wheel according to claim 11, characterized in that the rear region of the grinding flaps (13) is provided with projecting arms (23), in which engage the end faces of the associated slots, which extend over and beyond the longitudinal extension of the associated slot (12).

13. Lamellar end grinding wheel according to one of the claims 11 or 12, characterized in that a flat, acurate strip is located between the back plate (11) and the supporting plate (18) and is passed through recesses (21) of several juxtaposed grinding flaps (13).

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