EP1613454A1

EP1613454A1 - Blade and tie-rod assembly for stone material sawing machinery

Info

Publication number: EP1613454A1
Application number: EP04725473A
Authority: EP
Inventors: Michele Calistri
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-04-10
Filing date: 2004-04-02
Publication date: 2006-01-11
Anticipated expiration: 2024-04-02
Also published as: ES2310724T3; ATE403530T1; EP1613454B1; ITLU20030005A1; PT1613454E; DE602004015583D1; BRPI0409098A; WO2004089586A1

Abstract

In a gangsaw for stone materials comprising a blade 24 and tie-rod assembly 26 intended to perform an oscillating sawing movement, fixing between each blade and the two tie-rods, on the connecting-rod side and tensioning side respectively, is performed by means non-circular shaped pins 34 which engage inside coaxially arranged holes 36 of corresponding shape formed at the ends of the blade and in the adjacent ends of the tie-rods respectively.

Description

Blade and tie-rod assembly for stone material sawing machinery

The present invention relates to gangsaws for sawing stone material, in particular blocks of stone material for the production of rough slabs which must undergo subsequent finishing operations.

More specifically, the present invention relates to assembly and fixing of the sawing blades to the supports or tie-rods used for fastening to the gangsaw.

For many years now the sawing of hard stone materials has been performed using machines comprising essentially a structure formed by four angular columns having, mounted thereon, oscillating-arm units which are movable vertically along the columns and which have, pivotably mounted at their bottom ends, a horizontal blade-carrying frame. The latter, which supports a plurality of parallel and spaced cutting blades, is imparted a to-and-fro oscillating movement such that it is obliged to perform oscillating strokes with respect to the axes - likewise horizontal - for pivotably mounting the frame on the oscillating-arm • units .

Figures 1 and 2 show a side view and a partially sectioned view, at right angles to the first view, of an example of a sawing machine (more precisely the model "Alcione" which is manufactured and marketed by the company Barsanti Macchine S.p.A.).

As can be seen from the two abovementioned figures, the machine consists of four vertical columns 10 on which a carriage 12 is mounted, said carriage, during sawing, as the cutting depth increases, being displaced vertically along the columns in a controlled manner and over a desired distance. The carriage 12 has, pivotably mounted thereon, two arms 14 carrying at the bottom a blade-carrying frame 16 performing the aforementioned oscillating movement in the direction indicated by the double arrow F.

The oscillating movement is produced by a connecting-rod and crank mechanism (Fig. 1 shows the connecting rod 18 which is operated by means of a motorized flywheel 20 actuated by an electric drive system) .

Since these are machines which have been well- known in the art for several decades, further details are not required.

Each blade-carrying frame, which has a substantially rectangular shape, is formed, on two opposite sides, ^' by two sections or plates 22 having, mounted between them, a plurality of sawing blades which are made of ferrous material (normally varying from 100 to 200 in number) and mounted, parallel to each other and in an adjustable manner, at a variable mutual distance of between a few millimetres and a few centimetres: each blade is fixed to the two opposite sides of the frame by means of coupling elements or tie-rods, called respectively "connecting-rod side tie- rod" and "tensioning side tie-rod"; the latter also function as tensioning elements so as to, keep the blade at a predefined tension. For this purpose usually sets of oil pistons are used, being mounted so that each piston acts on the "tensioning side tie-rod" of a blade, so that the latter is tensioned with a predetermined force.

An example of an arrangement of oil pistons for tensioning the blades is described and illustrated in Italian patent No. 1,263,312.

Usually, in order to tension the blades, a tensile force of various tonnes, in particular in the region of 7-8 tonnes, is applied.

The abovementioned blades in reality do not have a cutting edge, but, depending on the type of sawing blade (grit frames and diamond frames) , have the function of keeping in contact and pressing abrasive elements (such as an aqueous suspension containing lime and abrasive particles in the former case) against the groove formed in the surface of the material to be sawn.

In the case of diamond frames the blade has, fixed thereto, diamond-coated inserts consisting of sintered blocks of highly abrasive material.

As each groove formed in the surface of the block to be sawn deepens, the blade-carrying frame, as already mentioned, is lowered along the columns (descent) : depending on the nature and in particular the hardness of the stone material forming the block to be sawn into slabs, the lowering speed varies from 2 to 8 cm/hour, so that sawing of an entire block, usually having a height of 1.5 - 2 metres, involves many hours of machining.

The blades, during the sawing operation, become worn and wear of the blades occurs within a relatively short amount of time (usually a blade wears to the point that it needs to be replaced, within the space of one or two sawing cycles) , such that replacement thereof with new blades must be performed frequently: if it is considered that each blade has a length in the region of 3 to 5 metres and that each time from 100 to 200 blades must be disassembled and replaced with the same number of new blades (each of which must also be tensioned) , it is obvious that this operation results in a considerable amount of downtime which obviously affects the productivity and consequently the profitability of the industrial process in question.

Hitherto attempts have been made to simplify as far as possible the methods used for coupling the blades to the frame and thus fixing them to the aforementioned tie-rods, so that universally a first end of each blade is seated inside a bracket, forming the end of the tie-rod, and is secured inside the bracket by means of a cross-pin which engages inside holes aligned axially and formed in the terminal portion of the blade and in the two flanges of the end bracket between which said blade end is inserted.

Figures 3 and 4 of the accompanying drawings show a detail of the system for fastening the end of the blade to the connecting-rod side tie-rod (Fig. 3) and tensioning side tie-rod (Fig. 4).

These figures show a blade portion 24 which, at its ends, is fixed to the end of the tie-rod denoted by 26 (connecting-rod side tie-rod) and 28 (tensioning side tie-rod) . These figures also show schematically fixing together thereof by means of the cylindrical pin 30. ^■

Fig. 5 shows, schematically also in this case, but on a larger scale, the already mentioned system for fixing together tie-rod 26 and blade 24, an identical system also being used for fixing the end of the blade 24 and the tie-rod 28. The end of the tie-rod 26 is shaped in the manner of a bracket comprising two flanges 23 forming a seat for the end of the blade 24. The cylindrical pin 30 is inserted into the holes 31 which are axially aligned and formed in the two flanges 23 and in the terminal portion of the blade 24.

In Fig. 4 it can also be seen how a locking wedge 32 is provided in the region of the tie-rod 28, being inserted between the outer end of the tie-rod and the perimetral structure of the blade-carrying frame.

Figures 6 and 7 show again, but in schematic form, a tie-rod/blade/tie-rod assembly according to the known art in the situation where the blade is new (Fig. 6) and the blade is worn (Fig. 7) .

In fact, as already mentioned, the sawing blades wear rapidly: however, their wear, precisely owing to the abovementioned oscillating movement of the sawing frame, has a very particular progression, as shown in Fig. 7, in which it is possible appreciate in qualitative terms the condition of a blade and in particular its bottom edge 25 (its "cutting" edge in the sense of the edge engaged with the groove which is formed in the block being sawn) after one or two sawing cycles, namely with considerable wear of material in the central portion of the blade.

This condition, as the blade become worn, is accentuated since the tensile forces applied to the two ends of the blade (which are equivalent to about 7-8 tonnes) and which initially are distributed over the whole height of the blade, are instead transmitted solely to the upper portion of the blade, so that the latter not only is not perfectly tensioned, but also tends to rotate about the two pins used for fixing to the two end tie-rods and the wear of the central portion of the blade is consequently increased.

This progression in the wear of the blades also has consequences on the characteristics and quality of the slabs resulting from sawing of the block: in fact, when the blade is worn, each slab has:

(a) opposite surfaces with a marked roughness, making the subsequent slab finishing operations

(calibrating honing and polishing) more difficult;

(b) a surface which is not perfectly flat; and

(c) a pronounced concavity in the central portion of the cut slab.

Special mention needs to be made of the dimensions of the blades in terms of both height and thickness.

The blades used hitherto (except in special cases) have a maximum height of 110 mm and a thickness of not less than 4.2 mm.

These values are determined by requirements relating to strength and quality of the cut performed. In fact blades with a height greater than 110 mm, taking into account their length which on average is about 4 metres or more, would tend to deviate, along their edges and therefore their bottom edge (i.e. the edge which engages with the cutting groove) , from a perfectly straight condition, with negative effects on the characteristics of the resultant cut slabs.

As regards instead the thickness, blades with thicknesses smaller than that indicated above tend to buckle in the sense that the top and bottom edges curve inwards with a concavity directed upwards.

In this case also this deformation is to the detriment of the quality of the cut slabs and in any case of the cutting speed.

With the blades known hitherto it is possible to perform two cutting cycles since the wear of the blades after two cutting cycles is such that the residual blade height (in the central portion and symmetrically with respect thereto) is reduced to about 38-40 mm, which is not sufficient for completion of a third cutting cycle.

On the other hand, replacement of the blades performed not at the end of a cutting cycle, but during an intermediate stage thereof, results in problems and drawbacks not only as regards extraction of the blades from the grooves formed in the block, but also in respect of reinsertion of the set of new blades in the previously formed grooves.

It is obvious that if it were possible to increase the height of the blade without the drawbacks mentioned above, each blade could be used for a greater number of cycles .

Equally well, if it were possible, for the same performance, to reduce the thickness of the blades, this would mean an increase in the number of blades which can be used for each sawing cycle.

All these considerations show how an improvement in fixing of the blades to the blade-carrying frame as well as an increase in the height of the blade and a reduction in the thickness of the blade are of great interest industrially speaking and these improvements represent the main object of the present invention.

It has now been discovered, this discovery forming the subject of the present invention, that substantial improvements, as regards rate of wear and hence duration of the sawing blades, cutting speed, more advantageous dimensions of the blades, and finally improvements of the slabs resulting from sawing, are achieved with a blade and tie-rod assembly for stone- material gangsaws, in which each tie-rod has its outer end fixed in a known manner to the frame and its other end fastened to the end of the blade by means of a pin passing through concentric holes formed in the superimposed parts of said blade and said tie-rod, characterized in that said holes have a non-circular shape and said pin has a shape suitable for engagement in said holes so as to prevent a relative rotation of tie-rod and blade about the axis of said holes.

In the preferred embodiment of the present invention, said pin has an oval shape so that said concentric holes also have a correspondingly oval- shaped form.

It should be noted that the scope of the invention also extends to the two individual components of the assembly defined above, namely on the one hand the blade and on the other hand the tie-rod.

The different aspects and advantages of the present invention will emerge more clearly from the detailed description which follows of a preferred embodiment provided with reference to the accompanying drawings in which, in addition to the figures already mentioned, relating to solutions of the prior art and the problems associated therewith,

Fig. 8 is a side view of a blade according to the present invention;

Figs. 9 and 10 are views, similar to those of Figs. 3 and 4, but simplified, of the tie-rods according to the present invention on the connecting rod side and the tensioning side respectively;

Fig. 11 is a view, similar to that of Fig. 5, of the tie-rod and blade assembly according to the present invention; and

Figs. 12 a, b, c, d, e, f, g and h show a cross- sectional view of variations of embodiment of the pin for assembling the blade with the tie-rod.

With reference to Figures 8 to 11, it is possible to appreciate readily the inventive aspect introduced with the present invention: the blade 24 is provided at its two ends with an eyelet hole 33 having a non- circular shape, suitable for receiving a pin 34 of corresponding shape, which also engages with an eyelet hole of corresponding shape 36 or 38 respectively formed in the end of the tie-rod to be coupled with the end of the blade.

In order to facilitate comprehension of the present invention, in these figures parts corresponding to those in Figures 3 to 5 have been identified by the same reference numbers .

Therefore, in this case also the blade 24 is fastened at its two ends to the tie-rods 26 and 28 which, in the shaped bracket ends, have coaxial holes 3.6 and 38 able to receive the pin 34 which, as can be easily appreciated, has a non-circular cross-section and in particular an oval or elliptical shape.

It is therefore obvious that, with this coupling system, relative rotation of blade 24 and tie-rods 26 and 28 is not possible.

Fig. 11 shows how .in the preferred embodiment the end of the tie-rod, in this case the tie-rod 26 (but the same is also applicable to the tie-rod 28) is shaped in the form of a bracket having two parallel flanges 23, each of which is provided with the respective eyelet hole 36 intended to be arranged coaxially with the eyelet hole 33 formed in the end of the blade 24 so as to allow insertion, preferably with a slight forcing action, of the pin 34.

It is nevertheless understood that the shaping of the end of the tie-rods in the form of a bracket provided with flanges is preferred, but not obligatory, since the desired technical effect is obtained owing to shaping of the eyelet holes 33 and 36 and 38, respectively, as well as the pin 34.

Fig. 12 shows other possible embodiments of the pin 34 (identified by the reference numbers 34A-H respectively) : it is obvious that in this case also the shape of the eyelet holes 33, 36 and 38 must be correspondingly modified.

Sawing tests were carried out with the tie-rod and blade assemblies according to the present invention, mounting on a same blade-carrying frame blades and tie- rods according to the present invention and one or more sets of blades and tie-rods according to the prior art, i.e. of the type shown in Figures 1 to 4.

The tests were carried out at a sawmill in Pietrasanta (Lucca, Italy) , more precisely the sawmill Tirrenia, using a Barsanti gangsaw with interchangeable unit, performing the cutting of blocks of so-called "Nero Africa" granite, with a height of 145 cm, and using abrasive grit of the type Murga HG1, size 9.

The blade-carrying frame was fitted with 31 blades according to the present invention, having dimensions of 4066 x 3.9 x 120 mm with an eyelet hole (51 x 20 mm) , and a blade which had the same dimensions, but in which the connection between blade and tie-rods was performed using circular pins with a diameter of 20 mm.

The maximum speed of descent was 35 mm/h and the power consumption of the motor was 26 kW.

The following tests were carried out:

1) "Res 1": for checking the resistance of the hole to the tensile force of 8.5 tonnes (1 tonne more than the value normally used) . The blade/tie-rod assemblies according to the present invention did not raised any problems.

2) "Lin 2": for checking the curving effect of the blade (known technically as "buckling"), due to the tensile force which is applied centrally. In the case of the blade/tie-rod assemblies according to the present invention there was no curving, while a small of degree of curving was detectable in the conventional blade .

3) "Con 1": for checking the degree of use or wear in the vertical direction. The vertical wear was the same both in the conventional blade and in the blade coupled to the tie-rod according to the present invention.

4) "Sup 1": for checking the roughness of the cut surface. The surface of the slab obtained with the tie-rod/blade/tie-rod assembly of the present invention was smoother than that obtained with the tie- rod/blade/tie-rod assembly according to the prior art.

5) "Sup 2": for checking the levelness of the cut slab. The vertical linearity of the slab cut with the blade and tie-rod assembly according to the present invention was good, while the slab cut with the blade/tie-rod assembly according to the prior art was bowed at the top, at about 60 cm from the start of the cut.

The same tests were carried out cutting granite of the quality known as "Desert Brown".

In this case also, advantageous results in terms of flatness of the cut slabs and lack of bowing were encountered.

It is worth noting that, in the abovementioned tests in which the blade/tie-rod assembly according to the invention was that shown in Figures 8-10, the height of the blade was 120 mm, while the thickness was 3.8 mm.

In these conditions, instead of the usual two cycles, it was possible to perform three sawing cycles and moreover about 20 cm was recovered over the whole width of the blade-carrying frame, allowing a corresponding increase in the number of slabs cut during a single sawing cycle.

The results of these experiments lead one to conclude that, with the blade and tie-rod assembly according to the present invention, it is possible to reduce the thickness of the blade to 3.5 or also 3 mm and at the same time increase the height of the blade to 130 mm or more.

Obviously the choice of the height of the blade and the thickness are also dependent upon the characteristics of the stone material to be sawn; for example in the case of so-called "poor" granites the height of the blade must be reduced to 120 mm or less and the thickness must instead be increased, without varying obviously the main characteristic feature of the invention.

Finally, a reduction or saving, in the region of 10-15%, in the consumption of electric power needed for the oscillating movement of the blade-carrying frame was noted. If it is considered that the sawing of a block of 1.5 to 2 metres height requires on average a sawing cycle of about 70 hours, the savings in electric power which can be achieved is immediately obvious.

Finally, during the above tests it was also found that it is possible to increase the speed of descent or lowering of the blade-carrying frame, which increase may be in the region of 0.5 cm/hour, with obvious advantages in industrial terms.

Finally, it must be commented that the present invention may be used equally well in frames using so- called diamond blades, namely blades where the bottom edge has a plurality of diamond-coated inserts.

Claims

1. Blade and tie-rod assembly for stone-material gangsaws, in which each tie-rod has its outer end fixed in a known manner to the frame and its other end fastened to the end of the blade by means of a pin passing through concentric holes formed in the superimposed parts of said blade and said tie-rod, characterized in that said holes have a non-circular shape and said pin has a shape suitable for engagement in said holes so as to prevent a relative rotation of tie-rod and blade about the axis of said holes.

2. Blade and tie-rod assembly according to Claim 1, characterized in that said end of said tie-rod coupled to said blade end is U-shaped so as to receive said blade end between the flanges of said U, said concentric holes being formed in said two flanges and in the blade seated between them.

3. Blade and tie-rod assembly according to Claim 1 and/or 2, characterized in that said holes and said pin have an elliptical shape.

4. Blade and tie-rod assembly according to Claim 1 and/or 2, characterized in that said holes and said pin have a prismatic shape.

5. Blade for sawing frames, characterized in that at the ends for coupling with the tie-rods of the frame it has fastening holes with a non-cylindrical shape.

6. Blade for sawing frames according to Claim 5, characterized in that said holes have an elliptical shape.

7. Blade for sawing frames according to Claim 5, characterized in that said holes have a polygonal shape .

8. Blade for sawing frames according to Claim 5, characterized in that it has a height of at least 120 mm and thickness not greater than 4 mm.

9. Tie-rod for sawing frames, characterized in that at the ends for coupling with a blade it has holes for receiving pins, said holes having a non-circular shape.

10. Tie-rod for sawing frames according to Claim 8, characterized in that said holes have an elliptical shape.

11. Tie-rod for sawing frames according to Claim 8, characterized in that said holes have a polygonal shape.