Patent Application
20190061108
The invention relates to a grinding wheel with a support body, which has a central coupling region for attaching the grinding wheel to a rotary drive for rotating the grinding wheel about a rotational axis running through the coupling region and a circumferential surface, and with a grinding layer which is applied, in particular sintered, onto the circumferential surface of the support body.
The objective technical problem of the present invention thus consists of specifying a grinding wheel according to the preamble of claim 1 in which these disadvantages are avoided.
This problem is solved by the features of independent claim 1.
According to the invention it is thus provided that the support body comprises a first part and a second part connected thereto, wherein the first part has the circumferential surface, and the second part has the coupling region and consists substantially of a vibration-damping material.
Due to the provision of a second part which consists substantially of a vibration-damping material, the vibrations occurring during the grinding operation can be efficiently absorbed in the support body. A resonance behaviour in the range of the resonant frequencies is thereby suppressed. Even in the case of a high speed of rotation of the grinding wheel, no additional ear protection is needed. A vibration decoupling of the grinding wheel from the rotary drive also takes place, with the result that vibrations are not transmitted from the grinding wheel to the rotary drive—and vice versa. The vibration decoupling or damping through the second part of the support body thus takes place in two directions: firstly the vibrations generated by the grinding layer and secondly the vibrations caused by the rotary drive or the grinding machine are damped and decoupled from one another. In the state of the art a partial superimposition of and additional increase in these vibrations takes place. In addition, a damping of the vibrations caused by the spindle of the drive through the second part of the support body also has a further favourable effect, e.g. on the bearings of the spindle as the latter are subjected to less stress.
Furthermore, through the provision of a first part, it is possible to make this of a material which is heat-conducting and thus efficiently removes the heat forming in the region of the grinding layer. If only a one-part support body were to be used, which completely consists of a vibration-damping material, a heat accumulation would result, promoting vibrations and disc distortion. The invention thus not only consists of providing a support body with a vibration-damping material, but making the support body of at least two parts, wherein one part consists substantially of a vibration-damping material and the other part can be made from a material different therefrom, which has different physical properties favourable for the grinding operation.
If the grinding layer arranged on the first part is worn, the first part can be removed again and replaced with a fresh first part, wherein the second part can be reused. This is also a further advantage of the two-part structure of the support body in comparison with the state of the art.
The vibration-damping material of the second part can be, for example, cast iron, preferably with lamellar graphite (e.g. GJL 250), spheroidal graphite, vermicular graphite, or cast steel, and/or aluminium bronze and/or fibre-reinforced, preferably carbon fibre-reinforced, plastic.
The first part of the support body can substantially consist of a vibration-conducting and/or heat-conducting material, preferably steel or aluminium.
It is also possible for the grinding layer to be formed contact-less with respect to the second part, with the result that vibrations occurring during a grinding process can be indirectly transmitted via the first part to the second part and can be damped by means of the second part.
A particularly advantageous choice of material consists of the first part consisting substantially of a fibre-reinforced, preferably carbon fibre-reinforced, plastic and the second part consisting substantially of cast iron. In this case both parts are manufactured from a vibration-damping material. The invention thus does not necessarily provide that the first part consists of a vibration-conducting material.
In order to connect the first and second parts of the support body a, preferably axial, screw connection can be provided. It is particularly advantageous to provide, in the first and/or second part, recesses into which threaded bushes are inserted, preferably adhesively bonded. In this way the second part can be supplied for reuse in a particularly simple manner. Alternatively, it would however also be possible to cut the threads directly into the first and/or second part.
It has proved particularly advantageous that the second part has a volume approximately twice as large as the first part, and/or the second part has a greater weight in comparison with the first part. It is thus a very solid second part which, in a particularly efficient manner, damps the vibrations occurring in the grinding operation.
Further advantageous embodiments of the grinding wheel according to the invention are defined in the dependent claims 9-15.
Further details and advantages of the invention are explained in the following in more detail, by means of the description of the figures with reference to the drawings. There are shown in:
The grinding wheel 1 represented in
The first part 2 is connected to the second part 3 via two contact surfaces 10 and 11, wherein the rotational axis 5 is oriented substantially normal to the contact surface 10 and substantially parallel to the contact surface 11. The contact surface 10 is many times larger than the contact surface 11. The vibrations are transmitted via these contact surfaces 10 and 11 to the second part 3. The latter consists substantially of a vibration-damping material, for example cast iron with lamellar graphite or aluminium bronze or fibre-reinforced, preferably carbon fibre-reinforced, plastic. Due to the vibration-damping properties of the second part 3 the vibrations transmitted by the first part 2 are damped.
Viewed as a whole, the grinding wheel 1 is formed asymmetrically with respect to an imaginary central plane normal to the rotational axis 5.
The second part 3 has a coupling region 4 for attaching the grinding wheel 1 to a rotary drive for rotating the grinding wheel 1 about a rotational axis 5 running through the coupling region 4. The coupling region 4 is formed as a central bore. The coupling region 4 is thus formed directly in the vibration-damping material of the second part 3, with the result that the second part 3 functions as a hub.
During the assembly of the grinding wheel 1 the second part 3, with an approximately cylindrical projection 16, is inserted into a corresponding recess 14, which is provided in the first part 2 until the parts 2 and 3 are flush with each other. The two parts 2 and 3 are then firmly connected to each other. In the embodiment example shown, there is an axial screw connection, i.e. a screw connection parallel to the rotational axis 5. For the realization thereof, in the second part 3 recesses 9 are arranged into which threaded bushes 8 are adhesively bonded. These are arranged flush with recesses 15, which are provided in the first part 2. In the recesses 15 there is room for a screw head. After the two parts 2 and 3 are joined together, these can be firmly connected to each other by screws 13.
If the grinding layer 7 arranged on the first part 2 is worn, the first part 2 can be removed again and replaced with a new first part 2, wherein the second part 3 can be reused. This is also a further advantage of the two-part structure of the support body 2 and 3 in comparison with the state of the art.
The arrangement of the recesses 9 and 15 in the two parts 2 and 3 represents only a possible example of how a screw connection can be realized. A reversed arrangement is also possible. Furthermore, as already stated, the thread can also be directly cut into one of the two parts 2 or 3. And finally, instead of the screw connection, other kinds of connection can also be used—alternatively or complementarily—such as for example a bonding of the two parts 2 and 3.
| Number | Date | Country | Kind |
|---|---|---|---|
| A 50447/2016 | May 2016 | AT | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/AT2017/060099 | Apr 2017 | US |
| Child | 16173034 | US |
