EP0322613B1 - Contact disc for supporting a rotation grinding belt - Google Patents

Abstract

Contact disc (1) for supporting a rotating grinding belt (2), with a belt-running cushion (4) which is arranged all round the disc body (3) and has belt-supporting webs (5) distributed over the periphery. In order to improve a contact disc (1) of the type mentioned at the beginning in such a way that the acoustic loading of the grinder is reduced at a certain grinding capacity, it is designed in such a way that the belt-supporting webs (5) are designed with belt-contact edges (6) arranged at non-uniform distances (a to d) apart. <IMAGE>

Description

The invention relates to a contact disc for supporting a circumferential grinding belt, with a belt running pad arranged all around on the wheel body, which has belt supporting webs distributed over the circumference and which are formed with belt running edges arranged at uneven distances from one another.

Such a contact disk is known from FR-A-1 381 341.

Such contact discs are rotatable and are used in belt grinding devices to support a rotating grinding belt. The running pad is a flexible covering of the support disc. The hardness of the running pad is chosen the greater the larger the chip removal should be. The smaller the workpiece shape, the more this is required. The webs supporting the belt are arranged more or less transversely to the direction of rotation. The time span volume is significantly increased by the webs of the contact disk. However, such webs have the disadvantage that the noise pollution of the grinder increases very considerably. The noise comes from that the webs or their leading edges converge with the tape. In particular, there are howl tones, the frequencies of which depend on the number of webs on the contact disk and their speed. In order to reduce the pronounced tonalities of the known contact disks, slanted bars are chosen. However, this helical arrangement or helical toothing has the disadvantage that the grinding becomes less aggressive, ie the time span volume and the surface roughness are reduced. So if a high grinding performance is desired, this can only be achieved at the expense of an additional acoustic load on the grinder.

A contact disk is known from FR-A-1 381 341, in which the strip leading edges do not run parallel to one another and the strip-supporting webs are consequently trapezoidal. However, it has been shown that such measures are not sufficient.

From the VDI magazine, vol. 124, no. 11, June 1982, Düsseldorf DE, pages 407-412; Heiner Degenhardt: "Noise reduction measures for belt grinding on contact disks" a contact disk is known in which slots between the webs run parallel and the webs or teeth are to have an uneven division. Because of the shape of the slots between the teeth, however, it remains open whether the webs are formed with tape leading edges which are arranged at uneven distances from one another. In any case, it is stated with regard to this feature and further developments of the belt running pad that it was not possible to achieve high amounts of sanding, but at the same time to produce a reduction in the airborne sound radiation.

The invention is therefore based on the object of improving a contact disk of the type mentioned in such a way that the acoustic load on the grinder is reduced at a specific grinding performance.

This object is achieved in the case of a contact disk of the type mentioned at the outset in that the distances between the mutually parallel strip leading edges are at least partially in a non-integer relationship to one another, and in that the spacings of the strip leading edges from one another at least partly have no common denominator.

It is important for the invention that the webs causing the aggressive grinding, which support the belt, are arranged in a way to avoid howling tones. This avoids a rhythmic run-up of the webs or their belt run-up edges on the back of the grinding belt and thus the howling tone caused by a rhythmic run-up. The mutually different distances can be dimensioned such that there is also a more uniform noise development, the noise formation taking place in frequency ranges which are less disruptive. A metrological check has confirmed the effects described above. The distances between the tape leading edges are at least partially in a non-integer relationship. Howling tone formation is reduced, namely a tone formation that occurs due to the superimposition of harmonic tone vibrations to a howling tone of greater amplitude. In this sense, the distances between the tape leading edges at least partially have no common denominator. Vibration synthesis can also be reduced in this way.

It is advantageous in terms of production if the contact disk has webs of unequal width, the web leading edges and webs of equal width between these webs. In this case, the slits can be produced by simply cutting or grooving, that is without measures to give the slits different widths. Therefore, in the manufacture of the contact disks, a control that takes into account the unequal width of the webs to the desired extent when adjusting a slotted or saw disk, or with one, is sufficient controlled positioning device for mutually independent webs.

If the contact disk has webs of the same width, the strip leading edges, and slots of unequal width between these webs, a correspondingly larger proportion of slot area can result with appropriate dimensioning. As a result, the slider can penetrate deeper into the tape running pad, making the disc more aggressive. The grinding performance can therefore be increased.

In order to be able to produce a contact disk that can be used as universally as possible, the webs are one-piece parts of a belt running pad designed as a laminated circumferential covering. The tape running pad can thus be a one-piece body in a simple manner, the attachment of which to the disk body is problem-free.

It is particularly advantageous for the invention that the conventional construction techniques of the contact disk can be used in realizing the invention in that the webs are lamellae individually fastened to the disk body, which are arranged on the disk body unevenly wide and close to one another, or the same wide and attached to the disc body at a distance from each other are, the unevenly wide spaces forming the slots are each filled with foam.

In an embodiment of the invention, it is advantageous that a limited number of strip leading edges arranged at uniform, specific distances from one another is present as a single group of all strip leading edges of the contact disk. Such a single group of tape leading edges can advantageously consist of webs of unequal width with web leading edges and slots of equal width between these webs, or of equally wide webs of tape leading edges and slots of uneven width between these webs. In both cases, there is the advantage that the single group leads to a simplified manufacturing effort, for example to use one and the same slotted or saw disk to produce slots of the same width, but that a howling tone is avoided or a uniform noise development is made possible.

Fig.1

eine teilweise geschnittene Seitenansicht einer Kontaktscheibe, und

Fig.2

eine Abwicklung eines Teils der Kontaktscheibe der Fig.1.

The invention is explained in more detail using an exemplary embodiment shown in the drawing. It shows:

Fig. 1

a partially sectioned side view of a contact disc, and

Fig. 2

a development of part of the contact disc of Fig.1.

The contact disk 1 shown in FIG. 1 essentially consists of a disk body 3 with an axis of rotation 9 about which the contact disk rotates in the direction of arrow 10. The disk body 3 consists, for example, of a light metal alloy and has a clamping recess (not shown) in the region of its axis of rotation 9 and is essentially plate-shaped, with a disk flange 11 arranged transversely to the disk plane being present on the outside, which carries a tape run-up cushion 4. The disc flange 11 and the overrun pad 4 have the width B shown in FIG.

The contact disc 1 is wrapped on its lower part by a band 2, which is supported on the belt running pad 4 and is held taut in connection with a drive roller, not shown, so that it drives the contact disc 1. This can also drive the belt 2 itself. On its outside 13, the band 2 is provided, for example, with a corundum coating, so that an object pressed in direction 14 against the band 2 and the contact disk 1 supporting it is ground. This grinding effect is reinforced by the fact that the tape running pad 4 is not smooth on its outer circumference, but is formed by slots 8 on its outer circumference with a plurality of webs 5. These webs 5 run in the direction of rotation 10 with their front or tape leading edges 6 on the back 14 of the rising run 2 'of the tape 2. Correspondingly, these edges 6 also run onto the object to be ground at point 14 and cause an increased grinding effect there.

The formation of the tape overrun pad 4 can be different. In FIG. 1, the design of the cushion as a laminated peripheral covering of the flange 11 of the contact disk 1 is shown on the left. The material of this peripheral covering is, for example, a plastic, such as polyurethane. This can be set to different degrees of hardness and is slitable. The slots 8 are produced, for example, with a slot or saw disk, a groove having a groove width determined by the saw blade width being produced by sawing, as can also be seen in FIG. The depth of the slots 8 or the grooves is determined by the intended use of the respective contact disk. Instead of a one-piece circumferential cover, the tape running pad 4 can also consist of several close or less close to each other on the outer circumference of the Flange 11 of the contact plate 1 attached individual webs or slats.

Fig. 1 shows webs 5 in the middle and right as individual lamellae. The webs 5 of the middle illustration are fastened tightly to one another on the outer circumference of the flange 11, e.g. by gluing. For example, they consist of a comparatively flexible foamed urethane rubber. The webs 5 are arranged so close to one another that the slot 8 between two webs 5 is only very narrow and is weakly wedge-shaped due to the geometry or the curvature of the flange 11. There are a total of five webs, that is, the webs 5a to 5e, each of which has a strip leading edge 6.

Fig.1 shows on the right as individual lamellae webs 5, which are fastened at a distance from one another on the flange 11 of the contact disk 1, e.g. by gluing. The webs 5 consist, for example, of a plastic, such as urethane rubber. The slot 8 forming the space between two webs 5 is filled with foam, which also serves to dampen noise. From the illustration it can be seen that the webs 5 are all of the same width and can therefore be produced from a single plate material which only has a corresponding thickness. There is therefore a group 7 'of webs 5 of the same width, while the middle figure of FIG. 1 has a group 7' of webs 5a to 5e of the same width. These webs must be cut accordingly from unevenly strong primary material.

It can be seen from FIGS. 1 and 2 that the edges 6 of the band-supporting webs 5 are arranged at uneven distances from one another. This results in particular from FIG. 2, where the distances a, b, c, d are different and, for example, have the dimensions 6, 11, 15 and 22 mm in the case of a disc with a diameter of 450 mm. The slots 8 are evenly 5 mm wide. It can also be seen from FIG. that the slots 8 or the webs 5 do not run parallel to the axis of rotation 9, but are inclined at an angle α, which in FIG. 2 is 45 °, but can generally be in a range between 25 ° and 60 °. The inclination of the slots 8 also serves to reduce the noise generated during grinding.

In order to avoid the formation of howling tones or to avoid the superposition of tones of different frequencies to a howling tone of greater amplitude, it is important that the spacing of the tape leading edges 6 be in a non-integer relationship to one another. This is the case with the web measurements mentioned above, for example, if one takes into account that the groove width is 5 mm, so that the distances between the strip leading edges 6 are 11, 16, 20 and 27 mm. In addition, the distances a, b; c, d; a, c; a, d and b, d have no common denominator, so that a howling tone is also excluded.

In this case, it is assumed that the best possible result of a quiet running of the contact disk is achieved in that the webs and / or the slots are distributed as unevenly as possible, so that any law that leads to the formation of a fast rotation of the contact disk Tonality could be avoided.

Claims (6)

1. Contact disc (1) for supporting a rotational abrasive belt (2), the disc comprising a belt-engaging pad (4) arranged peripherally on the disc body (3) and having belt-supporting strips (5) which are distributed around the circumference and which are provided with leading edges (6) arranged at unequal spacings (a to d) from each other, characterised in that the spacings (a to d) of the parallel leading edges (6) from each other stand at least partly in ratios to each other which are not whole numbers, and in that the spacings (a to d) of the leading edges (6) from each other have at least in part no common denominator.
2. Contact disc according to claim 1, characterised in that the disc has strips (5) of unequal width defining the leading edges (6) and slots (8) of equal width between these strips (5).
3. Contact disc according to claim 1 or 2, characterised in that the disc has strips (5) of equal width defining the leading edges (6) and slots (8) of unequal width between these strips (5).
4. Contact disc according to one of claims 1 to 3, characterised in that the strips (5) are integral parts of a belt-engaging pad (4) formed as a laminated circumferential overlay.
5. Contact disc according to one of claims 1 to 4, characterised in that the strips (5) are individual lamellae secured on the disc body (3), the strips being of unequal width and arranged in contacting relationship on the disc body (3), or being of equal width and secured spaced from each other on the disc body (3), with the unequal width intermediate spaces forming the slots (8) each being filled with foamed material.
6. Contact disc according to one of claims 1 to 5, characterised in that a limited number of leading edges arranged at regular defined spacings from each other is provided as a single group of all the leading edges of the strips of the contact disc (1).

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