EP0938958B1 - Cutting segment - Google Patents

Description

The present invention relates to cutting segments for circular saw or armor saw, these segments having a particular geometry of the general type known from FR-A-2 399 904. Segments of cut can be obtained by sintering a mixture of powders of a binder, and of an abrasive material such as diamond. Tools with these segments can be used for sawing hard materials, such as Pierre.

The invention also relates to a method of realization of the punches necessary for the confection of these segments.

The saw cutting segments have general in essence the shape of a parallelepiped rectangle of height X, width l and length L. The form and operating principle of such segments are illustrated in figure 1. It is in the codification of the European Federation of Abrasive Producers that the height of a cutting segment is called "X".

Each cutting segment is mounted on the cutting blade saw through his foot. When the blade penetrates a material to be sawn, it does it by its face called "cutting face", which cuts the material and determines the saw line, which increases as and when measurement of the sawing operation, while the segments sink into their height in the saw cut. Simultaneously, the segments wear out, which amounts to saying that their height X (between the cutting face and the foot of the segment) decreases.

In order to give the cutting tool the duration as long as possible, we naturally give segments a significant height X, that is to say greater at a value of 7 to 8 mm.

It is desirable to use abundant watering by means of a coolant, which cools the tool and the material being cut, and eliminates chips and sludge from cutting.

However, it has been observed that a saw blade comprising segments of high height, that is to say greater than a value of 7 to 8 mm, and used in presence of watering, presents lateral instability. In effect, if the blade is not perfectly centered in the sawtooth, the hydrodynamic pressure of the cooling is uneven and applies with more than force on the face of the blade away from the cut material, thus pressing the other side of the blade against the material cut, and the cutting segments start the material to be saw by parts other than their cutting face. This situation is illustrated in figure 2. The blade can then straighten under the effect of its rigidity, and harmful vibrations may ensue.

Practice shows that height segments less than 7 mm do not have this drawback.

We therefore sought to produce segments presenting both an important lifespan, and not presenting no lateral instability. This was achieved by giving on the lateral faces of the segments a stepped shape (called sometimes "pagoda"), shown in Figure 3. Two successive stages of a segment are separated by a bearing parallel to the cutting face. The width of a segment is therefore reduced at each level, from the face of cut at the foot of the segment. This embodiment gives the cutting tool an increasing clearance. Of such segments effectively avoid or reduce the lateral instability described above. They present nevertheless the following serious drawback: the segments of a saw wear in principle uniformly and all these simultaneously cross the degree of wear corresponding to a floor. In practice, however, slight imperfections in the centering of the saw, geometry of it and the segments themselves make that some segments are still working on a level upper wide, while other segments are working already at the level of the lower floor, more width scaled down. This then results, during the period of transition between two successive stages, one jerky sawing, noisy work, chips, and a bad sawn surface condition quality.

We know from documents JP 01 109 079 A and WO 95/22446 a type of segment whose shape aims to allow to some extent avoid these drawbacks. As seen in Figures 4 and 6, in the segments of this type, the stages of separation between successive stages do not are not parallel to the cutting face, but inclined by compared to it.

This in principle has the effect of making the passage from one stage to the other more progressive. However, we notes that the shape of the segments described by JP 01 109 079 A or WO 95/22446 does not prevent that, in the transition time between two stages, vibrations do not occur. In addition, the duration of the transition from one floor to floor is far too large.

Cutting segments are most often produced by sintering a powder of a binder, with a powder of a abrasive material such as diamond. The powder mixture is introduced into a mold, then compressed with a punch. This punch must be made of a material capable of resist the significant pressures implemented for the production of cutting segments, and must be able to resist to wear in the presence of an abrasive material. He must therefore be made of a hard material, and therefore difficult to machined. The cutting segments described in JP 01 109 079 A and WO 95/22446 have relatively shaped shapes complex, and the punches necessary for their production are therefore difficult to achieve.

The object of the present invention is precisely to provide a cutting tool segment that does not have the disadvantages mentioned above. Its purpose is to provide stepped cutting segments that allow for quick and easy transition between two successive stages.

A cutting segment for circular or armor saw, substantially shaped of rectangular parallelepiped, having a height greater than 5 mm, and comprising several stages. The segment width decreases in successive steps from cutting face of the segment at its base. The landing between a floor and the next lower floor, width reduced, is a bearing parallel to the cutting face of the segment, extended by one or more protrusions of a width equal to the width of the upper floor, spanning a portion of the length and height from the lower floor.

The protrusions are advantageously in number one or two per floor.

In a preferred variant of the invention, these protrusions have the shape of a half-disc whose diameter is between an eighth and a third of the segment length and is preferably equal to a quarter of the length of the segment.

In another variant of the invention, these protrusions have the shape of a triangle.

The invention also relates to a saw circular saw or armor saw on which are mounted cutting segments as described previously.

The invention also relates to a method of production of punches for the manufacture of segments of section as previously described, in which the successive bearings are obtained by a first machining plan, and the circular protrusions are obtained at by means of a second circular machining.

Other features and benefits of the invention will appear on reading the description which follows, reference being made to the appended figures.

Figure 1 is a schematic sectional view of a part of a saw with diamond segments following the prior art during work in a hard material.

Figure 2 is a view similar to that of Figure 1, the segment being eccentric in the saw cut.

Figure 3 is a sectional view of another saw according to the prior art, provided with stepped segments, the successive stages being separated by a landing parallel to the cutting face.

Figure 4 is a perspective view of a segment according to the prior art, the stages being separated by a bearing inclined with respect to the face of chopped off.

Figure 5 is a sectional view of a saw circular according to the prior art, provided with segments stages, the stages being separated by a landing inclined by compared to the cutting face.

Figure 6 is a side view of a stepped segment according to the prior art, the stages being separated by a inclined bearing with respect to the cutting face.

Figure 7 is a side view of a first embodiment of a segment according to the invention.

Figure 8 is a side view of a second form execution of a segment according to the invention.

Figure 9 is a perspective view of a third embodiment of a following segment the invention.

Figures 10 and 11 illustrate the calculation of the contact surface of the segments with the faces of the line saw.

Figure 12 is a graph showing this area contact, depending on the height x remaining at consume, for various forms of following segments the invention and according to the prior art.

Figure 1 shows part of a saw blade 1 circular or armor blade according to the prior art, of which a segment 2, 8, 12, 16 is engaged in a line of saw 3. The cutting segment 2, 8, 12, 16 is shaped substantially parallelepiped. The actual sawing is achieved by pressing the cutting face 4 of segment 2 on the bottom of the saw line 3. Abundant watering cools saw 1 and the material to be cut and take away the mud and sawdust. Segments 2, 8, 12, 16 of saw 1 are evenly distributed along of the saw blade and are joined by their foot 5 by an appropriate method, usually soldering.

If a slight asymmetry occurs, as is shown in Figure 2, the hydrodynamic pressure of the coolant is applied so preferential on the face of the saw furthest from material to be cut, and segment 2 is then pressed towards the other side of the saw cut 3. This results in work irregular, noisy and of poor quality.

Figure 3 is a sectional view of a saw 1 circular according to the prior art, provided with segments stages 8, the stages of each segment being separated by a bearing parallel to the cutting face. Segment 8 shown at the top of Figure 3 has a fraction of a wide stage 9 which is not yet completely worn out, and a narrow floor 10 not started. In the segment shown in bottom of the figure, the wide stage 9 is completely worn out, and the narrow stage 10 is being worn. This saw circular is rotated around an axis 13. As this is set out above, in this embodiment of the prior art, the transition period between two floors 9 and 10 is particularly difficult.

Figure 4 shows a type of stepped segment 12 according to the prior art, the stages being separated by a bearing 11 inclined relative to the cutting face 4. This embodiment aims to improve the conditions of operation of saw 1 during the transition between two floors.

Figure 5 shows a circular saw 1 fitted with such segments 12, in which there is shown by the letter E the height of the segment portion extending to both on a wide floor 9 and on a narrow floor 10, hereinafter called the transition zone. We have represented the situation where the segment represented at the top of the figure begins the wear of the transition zone between a stage upper 9 of width L2 and a lower stage 10 of width L1, and the segment shown at the bottom of the figure has just finished the wear of this transition zone. This situation can arise for example when the axis of rotation 13 of the saw 1 is offset by a runout E / 2 with respect to the axis of symmetry 14 of saw 1.

However, practice shows that the stepped segments 12 with bearings 11 inclined with respect to the cutting face 4 do not provide a satisfactory solution to the problems encountered with segments 8 with bearings 11 parallel to the cutting face. In addition they make the duration of the longer transition than with stepped segments parallel to the cutting face 4.

Figure 6 is a side view of the stepped segment according to prior art 12, shown above in the Figure 5, the floors being separated by an inclined landing with respect to the cutting face.

We therefore sought to produce segments 16 of cuts that allow a gradual transition between floors, while ensuring the speed of this transition.

Such an objective is achieved by the following segments invention 16, of which exemplary embodiments are shown in Figures 7, 8 and 9. In these segments according to the invention, a bearing 11 parallel to the face of section 4 of segment 16 separates each of the stages 17, 18 from immediately lower floors 18, 19. Each floor upper 17, 18 includes one or more protrusions 20, 21 extending the plan of the upper floor towards the low. These protuberances can take any form suitable, for example a half-disc 20 (FIG. 7) or a triangle 21 (figure 8). The number of floors can be between two and five, and is preferably from three. The number of protrusions per level can be between one and five, and is preferably one or two.

Improvement of the behavior of the following segments the invention is obtained by the fact that the protuberances 20.21 of the segments according to the invention have a contact surface 15, shown in hatched form at Figures 10 and 11, less than the contact surface, also shown in hatched form in FIG. 6, segments 12 according to the prior art. These protuberances 20.21 therefore disappear quickly by wear against faces of the saw cut in the cut material, ensuring thus a rapid transition.

In the case of the protrusion in the form of a half-disc, the contact surface 15, shown hatched in FIG. 10, is given by S = π * r 2 2 - [ x * r 2 - x 2 + r 2 * Bow sin ( x r )] where r is the radius of the half-disc and x the degree of wear of the protuberance, measured from the bearing separating the wide stage from the narrower stage.

In the case of the triangle-shaped protuberance, the contact surface, shown hatched in FIG. 11, is given by S = U * ( E - x ) 2 2 * E where U is the base of the triangle, and E is its height.

In the case of the contact zone 15, in the shape of a triangle, separating two stages of a segment according to prior art 12, the contact surface, represented hatched in FIG. 6, is given by S = The * ( E - x ) 2 2 * E where L is the length of a segment 12, and E the difference in height of the wide stage 9 between the two ends of the length of the segment 12.

FIG. 12 graphically represents the contact surface S, that is to say the surface remaining to be consumed, as a function of the height x remaining to be consumed, for various types of segments according to the invention and according to the prior art. The curve indicated by squares relates to a segment according to the prior art 12. The curve indicated by triangles relates to a segment according to the invention 16 having protuberances 21 in the form of a triangle. The curve indicated by circles relates to a segment according to the invention 16 having protuberances 20 in the form of a half-disc. The area is shown in mm ² as a function of the degree of wear x expressed in mm, for usual dimensions of segments. The segments according to the prior art have a length L of 25 mm, and E is 2.5 mm. The protrusions 20 in the form of a half-disc have a radius r of 2.5 mm. For the triangular protrusions 21, E is 2.5 mm and U is 7.85 mm. We thus compare three cases of transition zones capable of handling a geometric defect of 2.5 mm.

As we can easily see in this figure 12, the contact surfaces of the segments according to the invention 16 are much smaller than the contact surfaces of the segments 12 according to the prior art. The surfaces of contact of the segments according to the invention will therefore be more rapidly eroded during friction with the faces of the cut material, thus ensuring a much transition faster. The two embodiments of protrusions of the above examples are not limiting of the invention. Other specific forms can be carried out without departing from the the invention.

It can however be seen in Figure 12 that the protrusions in the form of a half-disc 20 provide faster decay of the contact surface S. La particular shape of the protrusions 20 in the form of a half-disc has the additional advantage that manufacturing punches necessary for their preparation is easy. In indeed, just machine, using a bur circular, a punch intended to make bearings 11 parallel to the cutting face 4. This circular machining is easier than machining a triangle. The punches to 11 parallel bearings are also easier to realize that level 11 inclined punches of art prior. It is even possible to reuse punches used for making segments according to art front 8 with bearings 11 not inclined. The form of realization with protrusions in the form of a half-disc 20 is therefore particularly preferred.

Claims (10)

1. Cutting segment (16) for a circular saw (1) or a stone cutters' frame saw, substantially in the form of a right-angled parallelepiped, having a height in excess of 5 mm, and comprising several tiers (17; 18; 19), the width of the segment (16) decreasing in successive stages (11) from the cutting face (4) of the segment (16) to its root (5), the stage (11) between one tier (17; 18;) and the tier (18; 19) immediately below, of smaller width, being a stage (11) parallel to the cutting face (4) of the segment, characterized in that this stage (11) is extended by one or more protrusions (20, 21) of a width equal to the width of the tier (17; 18) above, extending over a portion of the length and of the height of the tier below (18; 19).
2. Cutting segment (16) according to Claim 1, characterized in that there are two protrusions (20; 21) per tier.
3. Cutting segment (16) according to Claim 1, characterized in that there is one protrusion (20; 21) per tier.
4. Cutting segment (16) according to any one of the preceding claims, characterized in that the protrusions (20) have the shape of a half-disc.
5. Cutting segment (16) according to Claim 4, characterized in that the diameter of the half-disc of the protrusions (20) is between one eighth and one third of the length of the segment (16).
6. Cutting segment (16) according to Claim 4, characterized in that the diameter of the half-disc of the protrusions (20) is substantially equal to one quarter of the length of the segment (16).
7. Cutting segment (16) according to any one of Claims 1 to 3, characterized in that the protrusions (20) have the shape of a triangle.
8. Circular saw (1) on which cutting segments (16) according to any one of Claims 1 to 7 are mounted.
9. Stone cutters' frame saw (1) on which cutting segments (16) according to any one of Claims 1 to 7 are mounted.
10. Method for producing punches for manufacturing cutting segments (16) according to any one of Claims 1 to 7, characterized in that the successive stages (11) are obtained by a flat first machining operation and the circular protrusions are obtained by means of a circular second machining operation.

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