FR2468452A1 - PROCESS AND DEVICE FOR SAWING STONES AND MARBLE - Google Patents

Abstract

1. A method for sawing stone or similar material using a chain saw comprising cutting inserts (5a-5f) of tungsten carbide each fixed by mechanical clamping (6a-6f, 7) in a housing or receptacle with a corresponding cross-section so enabling the insert to be rotated, after being unclamped, through a suitable angle for evening out the wear, characterized in that the chain comprises successive sequences of links each formed by a large number of links (1a, 2, 1b, 2 ... 1f, 2), with the geometrical axes (8a-8f) of these inserts, and therefore of their respective housing, being so positioned as to meet the axis of the chain (9) at a constant distance from the corresponding insert, with each of these axes being angularly offset with respect to the axis of the preceding link by a constant amount round the chain axis, the cutting face or the inserts being coated with synthetic diamond reconstituted in situ by a known method and the inserts being positioned to have a negative cutting angle of 3 to 6 degrees, these inserts having a cylindrical shape of revolution or a polygonal prismatic shape with multiple symmetry.

Description

The invention relates to sawing stones and marbles,

  especially for quarrying.

  To carry out this operation, it is known to use a chain saw, but the chain used wears extremely quickly, even with cutting parts made of tungsten carbide, which constantly forces the work to be stopped for resharpening. This results in low productivity and at the same time a high consumption of carbide inserts and chain links on which these inserts are generally

brazed.

It is also known to use tools with diamond concretion, most often made up of small natural industrial diamonds embedded in a mass of copper or another metal. These tools require a high speed of rotation and a significant effort, consequently a great expenditure of energy leading to a great heating which requires permanent cooling. In addition, tool wear

remains extremely important given their high cost.

  In metal machining, recent work has made it possible to develop wear pads made up of a tungsten carbide base on which is directly formed, by the application of high pressure and high temperature, a layer of synthetic diamond. Such

  wear pads give extremely integrated results

  strong in working with metals and even materials

relatively abrasive composites.

We have naturally tried to use these same plates in the drilling of rocks, in particular to constitute the drill bits. For this the drilling head was provided with helical series of such plates, fixed by brazing at a significant negative cutting angle of the order of 150 and used with a cutting speed of 30 to 40 m / s as we

used for grinding wheels.

The object of the invention is to use diamond carbide wear plates of the above type on the links of a chain for cutting stones or marbles while eliminating the above drawbacks, that is to say in particular

  significant wear, overheating and high cost of res-

tools tauration.

The invention consists in working at low speed,

1.60 to 3 m / s with a small negative cutting angle of 3 to 60.

The invention also consists in using diamond plates of circular or polygonal shape with multiple symmetries and in mechanically fixing them in one-piece metal links so that they can easily be rotated on themselves by a certain angle at each

tool restoration. Finally, the invention also consists of

  to be mounted in the cutting chain of successive sequences

sives each comprising a large number of different links

  rents between them in an evolutionary manner so that the geometric axes of the various plates of these links successively occupy the positions corresponding to generators regularly spaced on a half-cone of revolution having as axis the axis of the chain and for half angle at the top the aforementioned negative cutting angle of 3 to 6, so that each insert only works along a reduced arc of its periphery. Other features of the invention will appear in

the following description of an embodiment taken

  as an example and shown in the accompanying drawing, in which FIG. 1 represents, seen in profile, a fragment of the cutting chain; fig. 2a to 2f represent respectively seen at the end the various links of a sequence; fig. 3a to 3f respectively represent these same links seen from above; fig. 4 represents the bottom section on a large scale

of the saw cut obtained.

The saw chain shown in fig. 1 is from

classic design, as well as its training and guidance

  who were not represented. It includes in particular an alternation of tool-carrying links such as la and lb joined together by connecting links 2 in the form of

double screed of a classic realization.

  Each of the tool-carrying links is made up of a single piece of steel. For example, for the first link in a sequence, this one-piece piece comprises a body 1a, extended at each end by a narrower tab 3a for articulation with the links 2, and surmounted by a head

cutting 4a carrying a cutting insert 5a.

  This plate 5a has a tungs carbide base-

  tene covered on its upper working surface with a layer of diamond. It can in particular be constituted by the product manufactured by the General Electric Company and

  sold under the brand name STRATAPAX. In accordance with the

  vention one preferably chooses a cylindrical shape of revolution, which allows its mechanical fixing in the head

  4a by practicing therein a cylindrical counterbore

  edge on the periphery and in which the plate 5a is exactly embedded, and it is locked in place

by a blocking plate 6a tightened by a blocking screw 7.

  The links lb and lc are identical in all respects to the

link it except that their plates 5b and 5c are respected

slightly offset to the right for one and to the left for the other. Finally, the links ld, le and lf are also identical to the previous ones except that they comprise

each two laminations to receive two respective inserts

  5d to 5f, which are symmetrically arranged and go in

  gradually moving away while approaching the base.

The shape of their heads 4b to 4f and their clamping plates

6d to 6f naturally evolves accordingly.

The nine diamond plates in each sequence of six links are preferably all identical and have been assigned a corresponding index only to refer to

their respective positions.

Indeed, in accordance with the invention each of the nine inserts works only with a limited arc and with a negative cutting angle of 3 to 60. This double result is obtained by ensuring that the geometric axis of each

insert, i.e. therefore the axis of the counterbore cy-

the corresponding link in the head of the corresponding link, meets the axis of the chain, and this at a constant distance from the plate; on the other hand the angle of offset of each of these axes with respect to the previous one around the axis of the chain

is also constant.

  To better understand this geometry, it suffices to assume by thinking that we geometrically superimpose the

-six links and their plates in the same mail position-

  lons by translation along the axis of the chain. In this case, the various axes 8a to 8f of the plates and counterbores, as shown in FIG. 4, are all concurrent at a single point 9 located at a distance from the common plane of coincidence of the various plates which is determined so that the acute angle formed by each of these axes with the axis of the chain is equal to l desired angle of incidence, that is to say from 3 to 60. It therefore follows that the

  nine axes 8a to If are all arranged according to genera-

  of a semi-cone of revolution centered on the axis of the chain.

Furthermore, under the second condition, these axes are

equidistant on this cone.

Thanks to this, we obtain as shown in FIG. 4 that the various arcs lOa to 1of, - according to which the corresponding plates 5a to 5f work, are all equal arcs

  and of small extent regularly distributed in half

wavy circle. The whole of the figure represents the shape of the bottom of the saw cut produced by the saw in the mass of

  stone designated by 11, the advance of the saw being natural

  actually in the direction of arrow 12 which is the chain circulation plane in the usual manner. For this reason the lateral arcs 10f actually extend towards

the rear by the tangents 13 parallel to 12.

According to the invention, the chain thus formed is driven at a relatively low linear speed of 1.60 to 3 m / s, which therefore requires only a small driving force, with as a consequence a low heating

  requiring only a small amount of cooling water

is lying. In addition, thanks to this cutting speed and the low negative cutting angle, an extremely reduced wear is obtained which allows working for whole days without having to stop the saw for restoration. Finally, when such a restoration proves necessary, it suffices to unlock the locking screws 7a to 7f and to turn the plates on themselves by a reduced angle corresponds in principle to the common length of the arcs lOa to 1of. After re-locking the screws

  blocking, the saw chain can be reused

reducing and considerably spacing downtime

size, which greatly increases production, and therefore greatly reduces the cost price per m2 sawn by

compared to traditional means.

Of course, the same result could be achieved if, instead of using an entirely revolution shape for the inserts, they were given a polygonal shape or with multiple symmetries, for example hexagonal, allowing them to be mounted in a certain number of positions different. In this case, the housing of each plate in the

heads of the links would be more difficult to achieve, but for-

should be milled at the end using for the tops of the

  plate of rounded corners in a known manner.

Alternatively, the half-cone of revolution exposed above could have a more flattened configuration in the direction of advance, and be for example semi-elliptical, by distributing the successive spacings of the axes on this cone so as to

  have cutting arcs of substantially equal length.

Claims (5)

1. Method of sawing stones or the like using a chain saw with cutting inserts carried, characterized in that one uses as cutting pins for tungsten carbide wafers including the cutting face is coated with reconstituted synthetic diamond   killed on the spot according to a known process, these inserts being arranged to have a negative cutting angle of 3 to 6 and the chain being driven at a linear speed of 1.60 to 3 m / s. 2. Method according to claim 1, characterized by the   the fact that the inserts have a cylindrical form of revolution tion, or prismatic polygonal with multiple symmetries, and that they are each fixed by mechanical locking in a cell of corresponding section so as to allow, after unlocking, the rotation of the plate by an angle suitable for distributing wear.   3. Method according to claim 2, characterized in that the chain comprises successive sequences of links each formed by a large number of links,   the geometrical axes of the various plates, and consequently   quent of their respective cells, being positioned   so as to meet the axis of the chain at a distance cons- aunt relative to the corresponding plate, each of these axes being offset relative to the axis of the previous link   a constant amount around the axis of the chain. 4. Chain for sawing stones or the like for implementing the method according to claim 2, and comprising successive links, at least some of which carry cutting tools, characterized in that each of the tool-carrying links is made of a single solid piece with a tool head in which is machined one or several counterbores of circular or polygonal shape cons- each titué the cell intended to receive one of the cutting inserts and emerging at the periphery to clear at least the cutting arc of this insert, the axes of these counterbores meeting the axis of the chain according to the negative angle of cut   above from 3 to 60, a pressure plate and a locking screw   cage to block the platelet (s) in their socket. 5. Saw chain according to claim 4 for the implementation of the method according to claim 3, characterized in that it comprises successive sequences of links of progressive shape and that the geometric axes of the various plates or cells, assumed to be brought back at the same link by translation along the axis of the chain, are arranged according to generators regularly spaced by a half-cone of revolution whose half-angle at the top is equal to the aforementioned negative cutting angle from 3 to 65.