DE2318269B2 - DISC GRINDING DISC - Google Patents

Description

The invention relates to a flexible disc, consisting of a carrier disk, a transition layer connected to this, one on the latter applied, preferably net-shaped reinforcement and a grinding layer connected to this.

It is known once, such preferably flexible grinding wheels with frontal, mostly profiled To provide the grinding surface with a fiber backing as a carrier, which, however, has considerable disadvantages brought. Such fiber underlays have a sufficient service life for panes (layer thickness = several Grain layers) on the one hand too thick for mechanical reasons, which affects the flexibility of such Grinding wheel has an unfavorable effect, on the other hand, they are only conditionally resistant to wet grinding. Furthermore, fiber tends to Splitting into layers, which is particularly important at high circumferential speeds and intermittent loads occurs. But there are, for example, the intermittent loads that lead to cracks and fractures in everyday life Operation are frequent, the safety of such a grinding wheel is significantly reduced.

As a result, there was a change to grinding wheels of the above type with a glass fabric or fiber fleece (consisting of ;; glass or organic fibers) to be provided as a carrier base. Since such disks as pure single grain discs are generally unprofitable, you had to get the necessary strength for so To achieve the thicker disc, to an inner reinforcement, which is in addition in the actual abrasive grain layer is embedded in the carrier plate, grab (US-PS 34 98 010).

A disadvantage of such grinding wheels has proven to be the relatively short service life, due to the fact that the grinding surface can only be worn down to the inner reinforcement and can therefore be used. Furthermore, for manufacturing reasons, the layer between the carrier plate and the inner reinforcement has to be a few grain layers f> o thick, which causes a reduction in flexibility and the proportion of the total weight of the usable grinding layer, especially in the case of coarse grains. The large grain size of the intermediate layer also brought as a result of the above ^h .s difficulty in imaging and relatively low internal resistance, a low explosive speed, which caused either a substantially reinforced structure, or a loss of security. This led to major problems, especially with grits 46 and coarser, and especially with wet grinding wheels.

There is also a grinding tool known (DT-Gbm 16 64 636), in which on a carrier material, for example made of paper, fiber, etc., several layers of abrasive grains are arranged. Here is also provided that from layer to layer the type of abrasive grain, the grain size of the abrasive grain and whose sprinkling range is different to suit the respective purpose of the grinding tool adapt.

It has not been recognized that the grain size is the The blasting speed of a grinding wheel can be influenced. There is also no indication of which layer should have larger or smaller grain.

It is therefore the object of the invention to create a flexible disc grinding wheel which, while avoiding the above-mentioned disadvantages, has better utilization and a longer service life, significantly increased safety and better flexibility.

In particular, it is the object of the invention to improve the explosion speed or explosion resistance of a To increase grinding wheel with relatively coarse grain, without disadvantages in terms of the elasticity of the Grinding wheel must be accepted.

According to the invention, this is achieved by making the grains of the transition layer finer in a known manner than are the grains of the abrasive layer.

According to the invention, it is essential that only one transition layer is involved. which immediately the carrier disk connects.

Tests carried out with regard to the invention have shown that an optimal operating result is achieved when the mean grain size of the fillers of the transition layer is less than 150 μ or a maximum is approx. 80% of the grain size of the grinding layer.

It is: advantageous if the binder, preferably resin, of the transition area is the same as the binder of the outer abrasive layer or at least compatible with it and can be processed in the same way. For example It can be cold or thermosetting thermosetting plastics with the same, sufficient for the grinding process Resistance to temperature, for example phenol, epoxy, polyester, melamine or similar resins.

The invention is described in detail below with reference to the figure of the drawing.

The drawing shows a schematic section through a grinding wheel according to the invention in FIG the direction of the axis of rotation of the disc.

The disk grinding disk according to the drawing has a carrier disk 1, which is flexible and as thin as possible can be produced and must be able to absorb high centrifugal forces.

According to the invention, a glass fabric or a fleece made of glass or fiberglass is used as the raw material of the carrier disk 1 Organic fibers od. The like. Provided, which with appropriate adhesion promoters (z. B. silanes) and Impregnating agents (e.g. resol resins) are provided.

A so-called transition layer A is located on the carrier disk 1 and is formed between this carrier disk 1 and a reinforcement 2.

It has proven to be advantageous to use a wide-meshed glass fiber network as reinforcement, since this enables a particularly good connection between the transition layer A and the grinding layer B.

18 269

In the transition layer A, the resin of which is the same as that of the grinding layer B , there is now a large number of polishing grains 3 functioning as fillers, the average grain size of which is a fraction (equal to or less than 150 μ) of the grain size of the abrasive grains 4 of the grinding layer £.

Since the transition layer A and the grinding layer B differ only in terms of the grain size of the grinding wheel or the filler material in the disc grinding wheel according to the invention, but are uniform in terms of the resin, the strength of such a wheel is increased by the fact that the fine-grained mixture the transition layer A adheres more firmly to the carrier disk 1 and reinforcement 2 and also has a higher mechanical strength than is the case with the large-grain mixture of the actual grinding layer B , as is usual with the previously conventional grinding wheels of this type.

The advantages of the disc grinding wheel according to the invention lie in the good binding, which allows a profile depth for the profiling of the surface up to the inner reinforcement, in the higher explosive strength and thus safety, especially when wet grinding or after extreme climatic storage conditions, proven by tests, and also in the possibility of this to be made as thin as possible and thus flexible with optimal usability. It should be mentioned that the transition layer A must be a few grain layers of the filler size thick for manufacturing reasons.

Another advantage of the disc grinding wheel according to the invention results from the fact that when used of fillers 3 with grinding or polishing properties the grinding wheel after the actual wear Abrasive layer ö, can still be used as a polishing wheel, because of the thin layer thickness on the then of course the central reinforcement that is omitted in the grinding zone can be dispensed with, and this fine-grained layer still has sufficient adhesion to the carrier plate 1.

Below is a list of a possible composition of a grinding wheel according to the invention:

l. carrier plate (l)

Glass fabric (0.045 g / cm ² , mesh size approx. 2.5 mm) with thermally curable phenolic resin impregnation (Resole type).

2nd transition layer (A)

0.8 mm thick. composition

a) normal corundum grain size 100 wt. 74%

b) phenolic resin liquid 4%

c) phenolic resin powder 14.5%

d) cryolite 7.5%

3. Reinforcement (2)

Glass fabric (0.045 g / cm ² , mesh approx. 5 mm)

4th sanding layer (B)

with a profiled surface
(Waffle pattern) 3 mm thick

a) Normal corundum grain size 24

b) Liquid phenolic resin

c) Phenolic resin in powder form

d) cryolite

79%

3.5% 10.5%

7%

In addition, some safety data (targets for 80 m / s working speed, mandatory Blasting speed 150 m / s, or comparison of a pane according to the invention with a previously known one).

No.

disc

Medium blasting speed (Mean value ims 5 measurements)

1 as in the above recipes 195 m / s 10 days after production,

strongly "flexed"

2 as 1 185 nvs 10 days at 100% humidity. 40 ⁰ C

3 like 2 178ms then grind for 15 min concave surfaces (approx. 30% wear)

4 disc with coarse-grained 160 m / s intermediate layer (same Abrasive layer, grain 24)

5 target like 4135 m / s 10 days after production

Storage according to No. 2

6 as 5 124 m / s grinding conditions as No. 3

Here / u 1 sheet of drawings

Claims (3)

Patent claims: 1. Flexible disc grinding wheel, consisting of a carrier disk, a grain-containing transition layer connected to this, a preferably reticulated reinforcement applied to the latter with a grinding layer connected to this, characterized in that the grains (3) are the transition layer (A) in known ι ο Way finer than the grains (4) of the abrasive layer (B) . 2. Disc grinding wheel according to claim 1, characterized in that the grain size in the transition layer (A) is smaller than 150 μ 3. Disc grinding wheel according to claim 1, characterized in that the grain size in the transition layer (A) is a maximum of 80% of the grain size in the grinding layer ^