Device for a grinding machine

The present invention relates to a device for the detachable fastening of a number of holding plates for carrying grinding elements on a rotatably driven circular grinding plate for floors or similar surfaces.

It is previously known to detachably fasten grinding elements on rotatably mounted driven grinding plates. Examples of this are shown in, for instance, SE 525 501 C2, US 2,842,904 A and US 1,470,957 A.

However, the grinding segments known according to SE 525 501 C2 are carried by holding plates in the form of bent sheet-metal plates, which diverge in the direction out- ward, as seen in the radial direction. The production of a grinding plate intended for holding the holding plates will be costly and the elevation of grinding segments from the grinding plate as seen in the radial direction also entails great effect on the grinding plate because of uneven load. According to the embodiment in US 2,842,904 A, tightening of the grinding tools is required, which is time- consuming and US 1,470,957 A relates to a construction having oblique wedge-shaped grooves widened outward requiring wedge elements for holding grinding tools. By DE 2051898 A, a device is previously known for the detachable fastening of a number of holding plates for carrying grinding elements on a rotatably driven grinding plate. The device comprises radial grooves, extending converg- ingly in the direction from the centre of the grinding plate toward the outer portion thereof, which grooves are arranged to holdingly co-operate with detachable congruent gripping members projecting from the underside of the respective holding plate. Grinding elements are arranged to be situated on the top side

of the respective holding plate. The grooves as well as the gripping members have wedge-shaped sloping edge surfaces for the mutual gripping co-operation between pair-wise groove edge surfaces and grip edge surfaces. Similar devices having external wedge-shapedly forming grooves possible to screw on are previously known by CH 523746 C, FR 2131299 A and DE 1777051 A.

The same solutions require much work both as regards the parts included and also for the assembly of the numerous parts on grinding discs.

Therefore, the main objects of the present invention are primarily to easily and efficiently solve the problem of providing simple exchange of grinding tools when they need to be exchanged and replaced by other grinding tools, and in that connection, that the carrying grinding plate is easy both to manufacture and to use as well as that the grinding tools are clamped safely and efficiently on the grinding plate .

Said objects are attained by means of a device according to the present invention, which substantially is characterized in that radial grooves, extending convergingly in the direction from the centre of the grinding plate toward the outer portion thereof and formed by cavities in the rotatably driven grinding plate, are arranged to holdingly co-operate with detachable congruent gripping members projecting from the underside of the respective holding plate, which gripping members are situated at the centre of the holding plate extending radially, that related grinding elements are arranged to be situated on the top side of the respective holding plate, that the grooves have a length greater than the length of the gripping members of the respective holding plate, and that the grooves as well as the gripping members have wedge-shaped slop-

ing edge surfaces for the mutual gripping co-operation between pair-wise groove edge surfaces and grip edge surfaces.

The invention is described below by way of a number of preferred embodiment examples, reference being made to the accompanying drawings, in which

Figs. 1-lA show a first embodiment of the invention as seen in front view and side view, respectively,

Figs. 2-2A show a second embodiment example of the invention, Fig. 3 shows a holding plate for carrying grinding elements as seen from one of the short ends, from below and the other short end, respectively,

Fig. 4 shows in perspective a grinding plate having cut out grooves therein, Fig. 5 shows examples of a holding plate having grinding elements and gripping members, respectively, diametrically facing away from each other,

Fig. 6 shows in perspective a part of a holding plate having fastened grinding segments, and Fig. 7 shows a method for the fastening of grinding elements on a holding plate.

A device 1 allowing to provide detachable fastening of a number of holding plates 2, which are intended for carrying grinding elements 3 on a rotatably driven circular grinding plate 4 intended for grinding floors of stone or concrete or for other similar surfaces, comprises fastening means 5 therefor. More precisely, there are radial 6 grooves 10 extending convergingly in the direction 7 from the centre 8 of the grinding plate toward the outer portion 9 of the grinding plate. Said grooves 10 are arranged to holdingly co-operate with detachable congruent gripping members 12 projecting from the underside 11 of the respective holding plate. Related grinding elements 3 are arranged to be fastened and situated on

the top side 13 of the respective holding plate. The grooves 10 as well as the gripping members 12 have, in that connection, wedge-shaped sloping edge surfaces 14; 15; 16; 17 in order to thereby provide mutual gripping co-operation between pair-wise groove edge surfaces and gripping-member edge surfaces 14-16 and 15-17, respectively.

According to the present invention, the grooves

10 are formed by cavities in the rotatably driven circular grinding plate 4 and are evenly distributed along the circum- ference 18 of the grinding plate 4. The grinding plate 4 has screw holes 19 to be used for the tightening of the grinding plate 4 on a common frame plate, not shown, for carrying a plurality of grinding plates 4. In that connection, the screw holes have a countersink 20 adapted to the head diameter 21 and the head countersink angle 22, respectively, of fastening screws. Said screw holes 19 are distributed on the grinding plate 4 along a common diameter 23 while the grinding plate 4 has a greater diameter 24.

Said grooves 10 are preferably sparked out of the grinding plate 4 and extend preferably entirely through the entire thickness 25 of said grinding plate with the inclination in such a way that the grooves, in addition to tapering in the direction outward toward the circumference edge 9 of the grinding plate, also tapering toward the back side 26 of the grind- ing plate from the front side 27 thereof.

As is seen in Fig. 3, radial gripping members

12, are situated on the underside 11 of the laterally 28 extending holding plates, which have a greater extension B laterally 28 at the farthest out ends 29 of the holding plates than the width b the same have at the innermost ends 30 of the holding plates.

Said grooves 10, which preferably are three, extend by a length L of between 0,4-0,6 of the radius of the

plate and are situated between the centre 8 and outer edge portion 9 of the grinding plate at a distance 31 from said centre 8.

In the thick end 32 and in the small end 33, respectively, the grooves have a width 34 and 35, respectively, that makes that the grooves become evenly conical, and that they are conical from one side to the other side of the plate 4.

In order to enable to get the holding plate 2 in place on the grinding plate 4, the grooves 10 in the grinding plate 4 have a length L greater than the length A of the gripping members 12 of the respective holding plate.

As is shown in the drawings in Figs. 6-7, the fastening of holding plates 2 carrying grinding elements 3 takes place readily without any screwing of the holding plates 2 that are fixed firmly by means of gripping co-operation between the mating grooves 10 and the gripping members 12. In that connection, the grinding elements 3 are V- or U-shaped as seen along the plane that they are arranged to grind on, e.g., an underlay such as a floor. In Fig. 7, there are seen the different steps of first choosing a groove 10 for a grinding-ele- ment carrying holding plate 2, next placing the subjacent gripping member 12 of the holding plate 2 into the groove 10 at the inner portion thereof, and finally, after radial pulling out of the holding plate 2 toward the outer portion of the groove 10 and after possible striking action from within on the holding plate 2, fastening said grinding element 3 and holding plate 2 in place. Then it remains the fastening of other holding plates 2 and grinding elements 3 into mating slot-shaped grooves 10 distributed evenly along the grinding plate 4. All this takes less than a minute.

Thus, the device according to the present invention now allows quick exchange of holding plates carrying

grinding elements by the fact that the old ones easily are knocked loose radially in the direction 36 inward toward the centre of the grinding plate 4 and are lifted away from the groove 10. Next, new holding plates carrying new grinding ele- ments are inserted by being lowered with the gripping members 12 thereof into the mating grooves 10. A hammer, for instance, is then used to strike gently on the slender end 30 of the holding plates 2 in the radial direction 7 from the centre of the grinding plate 4. By the fact that the respective holding plate rests with the underside thereof directly against the planar surface of the grinding plate, and that the holding plates have a great extension laterally, efficient support is obtained upon action by the grinding elements when the machine is run on a floor and machines the same or against another hard material.

Naturally, the invention is not limited to the embodiments described above and shown in the accompanying drawings. Modifications are feasible, particularly as for the nature of the different parts, or by using an equivalent tech- nique, without departing from the protection area of the invention, such as it is defined in the claims.