The invention relates to the removal of dust generated in the process of sawing concrete products, rock material, or other suchlike material. Saws used in the sawing of concrete products are typically equipped with a circular saw blade, as well as with water cooling for the saw blade. This cooling of saw blade is needed during a sawing operation as the saw blade is heated by frictional heat generated in the sawing process.

In the process of sawing a concrete product, or respectively for example rock material, the sawing results in the generation of sawing dust which disperses into the air and the environment. The dust generated in the sawing of concrete products, especially the rock material contained therein, is typically made up at least partially of quartz dust. Quartz dust is known to be particularly harmful, because being finely divided dust it becomes airborne and is conveyed by breathing into the lungs without being cleared from there by conventional means. Hence, especially from the standpoint of occupational safety, the generation of airborne quartz dust is a highly undesirable occurrence.

The generation of quartz dust is in its part suppressed by cooling water used in saw blade cooling, some of which finds its way into a cutting groove along with the blade and produces thereby a sludge with cutting residue, including quartz dust. However, the cooling water drifting into a cutting groove along with the saw blade is not sufficient for wetting the entire cutting groove, especially in the process of sawing products of considerable height, in which case the air is still exposed to the dispersion of quartz dust. In addition, the sludge produced by cooling water is readily able to spread on a casting bed, as well as on a production plant floor, with the result that, once the sludge has dried, quartz dust is again capable of dispersing into the air, especially during the course of cleaning work.

Attempts have also been made for precluding the dispersion of sawing- generated dust with various suction systems provided in connection with a saw. For example, patent publication US 5,1 67,215 discloses a dust removal solution for a movable concrete saw, wherein dust is drawn out of a saw blade guard by a funnel means mounted on the guard. A problem in this solution arises from situations in which the saw blade guard does not establish a closed space with a workpiece surface, which is often the case when cutting slip-form cast concrete products.

In a dust removal solution according to the present invention, inside a circular saw blade are formed radially directed channels, along which sawing- generated dust is sucked from a center of the saw blade. This enables the removal of sawing-generated dust directly from a cutting surface prior to its dispersion into the environment.

In a solution of the invention, the saw blade is also cooled by air current in the saw blade's suction channels. In order to enhance saw blade cooling as nec- essary, it is possible, in a preferred embodiment for a solution of the invention, that some of the channels constructed inside a saw blade can be used for cooling the saw blade, i.e. by feeding into the channels a suitable cooling medium, such as for example refrigerated air or some other appropriate gas. This provides a capability of conducting or enhancing saw blade cooling without producing a sludge of cooling water and sawing residue, which further enhances the elimination of dust with a dust removal solution of the invention.

Alternatively, the cooling of a saw blade according to the invention can be conducted with cooling channels constructed in the saw blade by feeding into the cooling channels a suitable amount of cooling water. In this case, the cool- ing water vaporizes as a result of the cooling effect, thus discharging from the saw blade's cooling channels at least partially as water vapor. Then, this water vapor is sucked through suction channels along with dust. If necessary, such water cooling also enables the purging of suction channels to be carried out by feeding cooling water momentarily through the suction channels for clearing possible obstructions present in the suction channels.

If necessary, such purging of suction channels can also be used for responding to a momentarily increased saw blade cooling demand, which may result from a saw blade loading spike. In this embodiment, the sawing apparatus is preferably also provided with a means for determining saw blade temperature, such as the one described for example in Patent application Fl 201 161 68.

When using saw blade water cooling, the cooling channels are also preferably constructed to be smaller in diameter than the suction channels, thus enabling the vaporized cooling water to be drawn, if necessary in its entire volume, through the suction channels. The feeding rate of cooling water into the cooling channels is preferably in the order of 0,05-1 dl/s, almost the entire volume of cooling water being thus vaporized, and the amount of water does not require channels unreasonably large in diameter. On the other hand, it is desirable to construct the suction channels as large as possible in diameter for enhancing the suction effect and precluding possible obstructions.

The saw blade with suction channels according to the invention can nevertheless be also used, if necessary, with conventional saw blade water cooling, wherein cooling water is sprayed in considerable amounts onto the side surfaces of a saw blade. Such conventional water cooling does not remove all of the dust generated in sawing, and the saw blade's suction channels can also be used at least to some extent for drawing out a sludge of sawing residue and excess cooling water.

One way of constructing internal channels in such a saw blade is known from patent publication EP 1 ,334,790, wherein channels, constructed in the saw blade and extending from a center area to the saw blade's edge, are provided for a cooling liquid. The saw blade presented in the publication has been designed as a sandwich structure, wherein the internal channels are constructed by removing material from an inner blade layer disposed between outer blades. In a solution of the invention, the saw blade has its suction channels opening in terms of the outer ends thereof onto a cutting face of the saw blade or in its substantial proximity, thus enabling the suction of dust as it is being produced. The substantial proximity of a cutting face refers in this context to spaces between the teeth of a saw blade. As for the outer ends thereof, the suction channels open preferably in the proximity of a saw blade's center onto either one of the side surfaces, whereby the elements generating a suction effect in the suction channels can be set at least partially in the proximity of a saw blade's center.

Another implementation for a solution of the invention is such that the suction effect is generated simultaneously for just some of the suction channels. Thus, dust is only drawn through those suction channels which at this particular time are located within the zone over which the saw blade is cutting the workpiece material. In addition, the saw blade of the invention is preferably a circular blade for a concrete saw, having its cutting face provided with teeth containing a diamond material.

More specifically, the method of the invention is characterized by what is pre- sented in the characterizing part of claim 1 , the saw blade of the invention by what is presented in the characterizing part of claim 5, and the saw of the invention by what is presented in the characterizing part of claim 9.

The invention will now be described more precisely by way of example with reference to the accompanying figures, in which fig. 1 shows schematically one saw blade according to the invention, fig. 2 shows schematically the saw blade of fig. 1 in an installed condition, and fig. 3 shows schematically one alternative saw blade according to the invention. A saw blade 1 according to the invention, shown schematically in fig. 1 , is formed with internal radially extending suction channels 2. The outer ends of the suction channels 2 open onto an outer peripheral surface of the saw blade

1 between teeth 3 of the saw blade. The inner ends of the suction channels 2 open into the proximity of a center 4 of the saw blade 1 on a side surface of the saw blade with a circular pattern being established around the center 4 by openings 5 of the suction channels' inner ends.

The saw blade 1 depicted in fig. 1 can be constructed as a sandwich structure as described for example in patent publication EP 1 ,334,790.

In fig. 2, the schematically shown saw blade 1 of fig. 1 is in an installed condi- tion. In the installed condition, the inner end openings 5 of the saw blade's 1 suction channels 2 are located under a cup-shaped element 6 placed upon the saw blade's center. To the cup-shaped element 6 is attached a dust collection pipe 7. This enables a suction effect to be established in the suction channels

2 by way of the dust collection pipe 7 and the cup-shaped element 6 as the dust collection pipe has its outer end connected to a suitable suction device, such as for example a fan (not shown) drawing air from the dust collection pipe. It is preferred that in connection with the fan be integrated some suitable filter solution to prevent dust and other extracted sawing residue from damaging the fan.

Fig. 3 shows schematically an alternative saw blade 8 according to the invention, which is formed with both radial suction channels 9 and radial cooling channels 10. In this saw blade 8, the suction channels 9 have inner end openings 1 1 thereof established peripherally further away from the saw blade's center than inner end openings 12 of the cooling channels 10. Hence, a saw carrying the saw blade 8 can be provided with two separate zones, whereof an outer zone covers the inner openings 1 1 of the suction channels 9 and an inner zone covers the inner openings 12 of the cooling channels 10, whereby the establishment of a suction effect in the suction channels can be conducted by way of the outer zone and the supply of a cooling medium can be conducted by way of the inner zone.

A suitable cooling medium is preferably gaseous, such as refrigerated air or some other appropriate gas. Alternatively, the cooling can be carried out with small amounts of water or carbonic acid, which vaporizes in the cooling channels 10 to provide a cooling effect. This provides a capability of precluding the generation and environmental spreading of a sludge made up in conventional solutions by cooling water and sawing dust. An optional arrangement is such that the inner end openings 1 1 of the suction channels 9 and the inner openings 12 of the cooling channels 10 are adapted to open onto different sides of the saw blade 8, whereby the establishment of a suction effect in the suction channels 9 can be conducted from one side of the saw blade and the supply of a cooling medium into the cooling channels 10 from the opposite side of the saw blade.

Regarding the embodiments illustrated in the figures and discussed above, it should be appreciated that those are just examples of solutions according to the invention and, hence, by no means limiting to the invention. The invention has its scope of protection defined in the appended claims.