ES2361708T3 - PROCEDURE FOR THE MANUFACTURE OF A SAW TAPE. - Google Patents

Abstract

Procedure for the manufacture of a saw belt (1), in which at least one row of teeth (11) of the saw belt (1) is applied a coating of a hard material by a coating process in empty, so that the saw belt is spirally wound in a coil (8) and coated in this way, characterized in that at least the row of teeth (11) of the saw belt (1) wound in the coil (8) before the application of the coating of hard material is subjected to brushing for chip removal, that the coating is carried out with a thickness of 0.5 to 3 μm, and that the material constituting the The coating is applied by a PVD process or a paCVD procedure or a combination of both at a temperature between 450 and 550 ° C.

Description

The invention refers to a process for manufacturing a saw belt, according to the introductory part of claim 1.

A procedure of this type is known from GB-A-1 513 667. In this procedure, a metal with a high melting point is applied to the saw belt and finally hardened by impulses.

US 4 337 300 discloses a vaporization process at a temperature between 300 ° C and 600 ° C for the manufacture of a cutting tool based on a metallic substrate of a fast steel with a surface coating with a thickness of 0.5 at 10 µm, for example by vacuum vaporization (PVD) or by chemical vaporization under a plasma stream (paCVD).

JP 03 032516 describes a procedure for applying a coating to a saw belt by a vacuum coating process.

From JP 61 044 171 A it is known to provide a layer of mitride, oxide or carbon on a titanium-based tool.

WO 01/90436 A1 defines a coating process in which the object to be coated is cleaned by a jet of balls before coating.

A state-of-the-art saw belt is known, for example, from DE 102 02 770 A1. It is used in band saw machines such as those described in DE 25 38 718 A1 and especially for sawing large parts that cannot be machined with disc saws. In spite of the great efforts made to achieve improved material compositions for these band saws, these are provided or are only suitable, for relatively low cutting speeds and small advances and show reduced lifespan, that is, they are dull. very quickly, and correspondingly they must be changed frequently.

It is also known to provide tools and components for increasing wear resistance and as corrosion protection, surface coatings. For this, PVD (physical vapor deposit) or paCVD (plasma-assisted chemical vapor deposit) or combinations of both methods are used in many cases.

Publication WO 2005/014877 A1 discloses the coating of a steel band in a roller-to-roller process such that a layer of different hard materials is applied on one side on the strip preferably made of cold rolled steel. or on both sides in successive stages of the process. Next, a saw belt can be made from this band.

It is an inconvenience, in this case, that the coating takes place from one side. In this way the smallest coating layer is applied on the surfaces with greater functional solicitations (free surfaces and detachment surfaces) and on the less functionally requested surfaces the greater thickness of the layer is applied, whereby the coating material, which is expensive, it is misused. Frequently the coating is also applied on cold rolled steels that are only hardened later, which can be an inconvenience for the layer-substrate bond. On the other hand, said cold rolled steels cannot be easily coated after hardening, since the usual PVD processes far exceed the tempering temperatures of said materials. The low temperature PVD processes also have the disadvantage of generating layers with poor adhesion, which constitutes a serious inconvenience in the case of high loads such as they take place in the saws and abrasive wear. Another drawback is presented by the procedure provided, according to the state of the art, called roller to roller. In this case, it is not possible to choose any geometry of the saw, for example, a cross-tooth geometry is not possible since these bands cannot be bent or are only with great difficulty. Since the layer thicknesses known in the state of the art are substantially greater than 5 µm, they are expensive in manufacturing and do not provide substantial improvements with respect to uncoated saws since there is a tendency for the layer to break at the beginning of the work on the tip of the teeth and therefore the advantage of the coatings cannot be used in these areas.

Therefore, it is an objective of the present invention to disclose a process for the manufacture of a saw belt of the aforementioned type, by means of which a saw belt that allows a high functional capacity in mechanization can be achieved, especially with materials metallic In addition, the manufacturing economy and also the use of these saw belts will be improved.

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According to the invention, this objective is achieved with the characteristics of claim 1.

In accordance with the present invention, it is also provided that, at a minimum, the row of teeth, before application of the coating, receives a brush for the removal of burrs. This removal of burrs in the row of teeth prevents burrs from breaking in the subsequent use of the saw belt, so that an uncoated saw belt surface would be generated.

By means of the coating object of the invention, a much longer time of use or, at least, of the row of teeth of the saw belt is possible when applying the method object of the present invention, which in addition to the longer time of the use of the saw belt also allows greater intervals in the exchange of worn saw belts.

Another advantage of the saw belts manufactured in accordance with the process of the invention, consists in the higher cutting speeds that are possible as well as in some cases a greater work progress. In addition, the coating can lead, due to less friction, to a smooth and regular work of the saw belt, so that substantially smaller efforts are necessary to produce the feed.

A very simple manipulation of the saw belt during the coating is achieved when the band of the saw is provided with the coating taking the form of a coil forming, for which before the coating is wound, a spiral and is manipulated in the installation of coating of this way, so that all rows of tapes are directed in the same direction. This way of proceeding also leads to a substantial reduction in process costs, since a relatively large length of the saw belt can be simultaneously coated.

A saw belt, according to the invention, that is, a corresponding saw band, consists of a HSS (fast steel) basic material on which a hard layer is applied by PVD or paCVD procedures. HSS steels are suitable because of their high temperature resistance for coating with PVD or paCVD processes, since the tempering temperatures of these steels are normally significantly above 500 ° C and therefore a coating is possible without any problem at 500 ° C, which guarantees a substantially improved bonding of the coating layer / base material with respect to low temperature processes.

Materials especially suitable for coating layers of band saws are TiAlN as well as AlCrN layers, as can be manufactured, for example, with industrial coating systems of the BAI1200 or RCS types. Other layers that facilitated, at least, special combinations of layer / work material, a significant increase in cutting performance were combinations of TiAlN, AlCrN, CrN, as well as the carbonitrides and carbides of the corresponding layers, for example also multiple layers or with gradient with increasing carbon content, combined with metallic or non-metallic DLC (diamond like carbon) coating layers, as well as different layers containing Si, for example, TiAlSiN, AlCrSiN and the corresponding carbonitrides with a Si content between 1 and 12% in proportion to the total metal content.

Other especially suitable layer systems also comprise other hard materials such as one to several metals of group IV-, V-, or VI-, of the periodic table (transition metals), as well as aluminum or silicon and its compounds. Especially, nitrides such as the known TiN, VN or TiSiN, carbides or carbonitrides such as, for example, SiN, borides, oxides such as, for example, Al2O3, (AlCr) 2O3, as well as others mixtures of the corresponding nonmetals such as, for example, boron-nitride, carboxynitride among others with said metals. Multi-layer systems can also be advantageous, as well as layers specially constituted as adhesive or transition layers for the mechanization of certain materials.

A coating of a nitride based material has been shown to be especially advantageous as well as cutting speeds and advances, a coating of a nitride based material. In this case, a coating with advantageous embodiments of TiN, TiCN, TiAlN and / or AlCrN can be used. In this case, all materials can also be used in the form of alloys or mixtures.

Another coating that is very suitable for practical use can have WC / C as a coating layer, since this metal-containing DLC coating system has a particularly appropriate work start process, for example a polishing of the layer during the first cycles cutting As a support layer, the systems explained above can be taken into consideration.

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When in a further advantageous development of the invention the coating has a thickness of 2-3 µm, this leads advantageously to a very quiet and regular work of the saw belt and does not produce adhesion or other similar problems such as could be produce in the case of a coating with a high thickness in the sawing of work pieces. The thickness of the layer also depends on the pitch of the teeth, the geometry of the teeth, the material to be worked on and the material of the coating itself, so that depending on the case, higher layer thicknesses are also possible.

For the optimization of the cutting performance, a saw with the coating, according to the invention, must therefore be adjusted for the appropriate layer thickness. In this case it has been surprisingly demonstrated in investigations that thinner layers, according to the invention, approximately between 0.5 and 3 m, especially between 0.7 and 2 m, provide substantially better cutting results than thick layers, starting at a layer thickness of about 4 m and higher. The latter achieved only a very small or no improvement in cutting behavior with respect to uncoated saws.

In a further embodiment of the invention, it can be provided that the row of teeth is made of HSSE. This base material for the row of teeth together with the coating, according to the invention, leads to a particularly wear-resistant saw belt.

In the state of the art, uncoated saws are used, usually with a geometry of the angle of detachment of  = 0 ° for simple sawing works, such as sawing of materials with a high carbon content (for example cast iron) or for pieces with reduced cross sections, for example, thin-walled profiles and tubes. In this case, coated saws with a detachment angle geometry of  = 0 ° can be used especially advantageously for sawing hard materials, such as tool steels, for example X38CrMoV5-1, material number 1.2343 with a hardness up to HB30 = 235. This is especially advantageous since this geometry of the saw belt can be manufactured more simply and economically than geometries with higher chip detachment angles and possibly curved detachment surfaces. In this way it is possible, despite additional coatings, to manufacture the saws for hard sawing processes, or for sawing solid geometries of large sizes, especially large diameters, at favorable manufacturing costs. In addition, tooth geometries with negative detachment angles can be tested, so that for hard sawing with coated band saws, detachment angles between -5 and + 5 °, preferably between -2 and 3 °, can be taken into account.

For soft materials with strong lubricating characteristics, such as, for example, stainless steels VA, for example X6Cr17, material number 1.4016 with a hardness up to HB30 = 185, saws with a more aggressive tooth geometry could be used, with a angle of detachment of  = 10º to achieve the best results. Similar results can be achieved in a range of  = 103º.

Another additional improvement could be achieved for different applications by means of an obliqueness of the free surfaces, according to an angle between  = 1 and 5 °, preferably  = 2 to 3 °.

A coated saw belt according to the invention can be achieved with a satisfactorily controllable process with very good results when the material constituting the coating is applied, according to the invention, by PVD or PaCVD at a temperature of 450-500 ° C, preferably approximately from 500 to 550 ° C.

When, in an advantageous arrangement of the process, it is provided that the row of teeth is provided with coating only to the transition zone towards the counter edge of the saw, this leads to the saving of coating material, to a reduction of costs in the manufacture of the saw belt according to the invention. In this case there is no reduction in the quality of the saw belt, according to the invention, since said areas of the saw that have no coating do not have a cutting function. In addition, the cut sawbands can be assembled for example in stacks and provided with a joint coating on cassette type supports. In particular, when the rows of teeth are made of a different material that contrafiles of the band it can be advantageous that the rows of teeth are welded with said counter edge of the band.

In addition, it can be provided that the saw belt, after coating, is welded into a ring. In this way, an immediate use of the saw belt is possible in a saw belt machine.

In a further advantageous embodiment of the invention, spirally wound saw belts are coated together in a single load once mounted on supports.

The figures show: Figure 1, a tooth;

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Figure 2, a fragment of a saw belt;

Figure 3, an uncoated and sectioned coated tooth;

Figure 4, a coating installation;

Figures 5 to 9, testing diagrams of sawing with the saw belt, according to the invention.

Figure 1 shows a schematic representation of a tooth (2) of a saw belt (1) with counter edge (3), so that the tooth has a shavings exit surface (4) with a shavings exit angle  , an incidence surface (5) with an angle of incidence  as well as a lateral face (7).

The saw belt can be constituted in the form of a closed ring and in a known way it can be mounted on a band saw machine. The direction of the cutting movement of the saw belt (1) has been indicated by the arrow "v" in Figure 1. These saw belts are used in band saw machines in both horizontal and vertical orientation. Depending on the way of use, the workpiece will be moved on the saw belt (1) or vice versa.

A segment of the saw belt (1) is shown in Figure 2. In it it can be seen that the saw belt (1) has a counter edge (10) in which the saw belt (1) is placed, in a manner not shown but known in itself, within the band saw machine as well as multiple teeth (2) in a row of teeth (11). The counter edge (10) is preferably constituted by a relatively simple "soft" steel, whereas, on the contrary, the row of teeth (11) is made of a high-performance fast steel, preferably HSSE. By using a simpler steel for the counter edge (10) costs can be reduced and the flexibility of the saw belt (1) can be increased. For the union of the row of teeth (11) with the counter edge (10), a welding procedure is recommended.

In order to especially increase the service life, preferably, however, also the cutting speed and, if necessary, the advance of the saw belt (1), at least the row of teeth

(11) is provided with a coating that increases wear resistance. The coating, which is not recognizable in the drawings, may comprise a material such as that explained in the foregoing, or a material of this type. The coating also entails a reduction in the cutting force of the saw belt (1).

Figure 3 schematically shows an uncoated or endowed tooth with a coating of the previously known type (2 ') as well as a tooth (2 ") provided with a coating according to the invention after a long period of use, in section cross. The tip, that is, the geometry of the unspent tooth has been shown by a dashed line (6). In the uncoated tooth it shows, after the same number of cuts, a more pronounced wear of the tip (6 ’) as well as a rounding of the tip (6’), according to the cross section. On the contrary, the tooth (2 ’) provided with coating shows, even after a complete detachment of the layer, a reduced wear of the tip (6’) as well as no rounding or only a smaller rounding. This has substantial advantages since, in this way the guidance that is essentially secured by the edges of the tip (6) continues to take place within the material and a straight cut is possible even for stronger wear of the saw belt, by On the contrary, a band with very rounded teeth (2 ') shows a strong tendency to wear, which increases the rejection and / or consumption of material.

Figure 4 shows, in a very schematic way, a coating installation (12), with which a process for manufacturing the saw belt (1) described above for a belt saw machine can be carried out. Within said coating installation (12), the coating described above, which increases the wear resistance of the saw belt (1), is applied at least on the row of teeth (11). The installation (12) preferably carried out in the form of a vacuum coating installation has, although it has not been represented, the necessary installations for coating such as metallization nozzles by ionic bombardment nozzle, vaporization nozzles or arc sources (also in combination) in addition to its electric drive devices, as well as gas lines and regulating devices to be able to project, for example, oxide or nitride layers; Vacuum pumps and elements necessary to create the precise pressure conditions for a PVD or paCVD procedure, as well as heating devices, measuring devices and other auxiliary elements. Installations of this type belong, as installations for coating tools or components, to the state of the art.

In the present case, for the coating of the saw belt (1) it will be taken to a coil form (8) wound to the coating installation (7) and suspended from one of the supports provided for it (9) . In this case, the coil (8) can have a diameter of up to about 50 cm, which results in a total length of the saw belt (1) of 100 m. Preferably, only the row of teeth (6) will be provided until the transition thereof to the counter edge (10), that is, essentially to the bottom of the tooth, with the coating to save coating material. After coating, the saw belt (1) will be removed from the installation (12) and can be welded in a known way constituting a ring.

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To avoid that any shavings found in the teeth (2) can lead to breakages in the subsequent use of the saw belt (1), thereby appearing an uncoated area of the saw belt (1) in its surface and therefore the wear resistance is significantly reduced, according to the invention, at least, the row of teeth (11) before the coating is brushed for chip removal. Instead of shavings, the corresponding tooth (5), after mechanization has a small radius. In the case of brushing, a rotating brush that brushes, according to the invention, the wound belt (1) wound forming the coil (8) will be used.

Example:

Figure 5 shows very clearly the advantages of a saw belt, according to the invention. A 91.45x14.3 mm tube of 100 Cr6, material number 1.3505, was machined with a saw belt with a coating of approximately 1 to 2 m TiAlN (Bailinit FuturaNano, procedure FN1) and 0 ° chip exit angle with a cutting speed of 120m / min. For an uncoated tape, cutting speeds of 60m / min were used according to the manufacturer's recommendations. The curves show the cutting time depending on the number of cuts. The upper curve shows the values for the uncoated saw belt and the lower one for the coated saw belt. The total cutting time for 300 pieces with the saw belt provided with a coating was 5 hours. The total cutting time for 300 pieces with the uncoated saw belt amounted to 8 hours and 24 minutes. After 300 cuts, the cutting time of the coated saw belt was cut by less than half of the cut time of the uncoated saw belt.

Figure 6 shows two tests of saws with coating of approximately 1 to 2 m of TiAlN (Bailinit FuturaNano, w.o) of different geometries on tool steel 80x80mm, X38CrMoV5-1, material number 1.2343. The cutting speed amounted to 90m / min., The cutting pressure was 16 bar, and the feed was 4. The differences between the two tapes reside exclusively in the geometry of the teeth or more precisely, the exit angle of chips. It was completely surprising that the saw belt with the smallest chip exit angle of 0 ° (diamond-marked curve, bottom) is clearly superior to the saw belt with the sharpest chip exit angle of 10º (curve with marking of rectangles, middle part), which is contrary to the experience with laminar saws equipped with coating.

For coated tapes in a comparative test that have been shown in this case as "10 ° tapes" at half the cutting speed, that is, 45m / min. (according to the manufacturer's recommendation) and otherwise with the same conditions explained above, the saw belt with a chip exit angle of 0º was already after the third part of the first cut and the saw belt with shavings exit angle after half the first round or dull cut. The investigation was continued, therefore, only with the “10º tape” (curve with triangle marking, upper part). However, the cutting time was, at the third cut, about 18 minutes, while the geometrically identical tape, provided with a coating, had a cutting time of about 10 minutes and the “saw 0º” coated tape required , however, a cutting time of about 6 minutes.

Figure 7 shows the comparison of the types of cutting of saw belts with and without coating with different geometric shapes. In this case, C45 bonded steel, material number 1.0503, d = 100mm, solid was sawn. Sawing parameters for tapes with coating were adjusted as indicated below. The first result is shown in column 1 of figure 7.

Cutting speed 120m / min

Cutting pressure 18 bar

Advance 4

If uncoated tapes are operated with the same parameters, a so-called deviation of the cut occurs, that is the cut is oblique, which results in rejection of the piece. For this reason the uncoated tapes should have been used with lower cutting speeds and corresponding corresponding pressures, the result being shown in column 4 of Figure 7:

Cutting speed 75m / min

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Cutting pressure 12 bar

Advance 3

Both for tapes with an exit angle of shavings of 0º as well as for tapes with an exit angle of shavings of 10º, the cutting time could be reduced by coating and by the possible working method with high cutting speed and pressure approximately in 50%. However, for the selected cutting parameters, only a regular cut for “0 ° saw belts” could be achieved. On the contrary, for “10º saw belts” with and without coating, a bulging of the cutting surface was verified with a maximum deviation of 1 mm with respect to the cutting plane, which led to rejection or revision of the elaborated pieces.

Figures 8 and 9 show results of sawing investigations with saw blades of different geometries (type 1-3) with 0º / 10º shavings exit angle in version with and without coating. The workpiece of figure 8 was ferritic stainless steel X6Cr17, material number 1.4016. The cutting width was d = 102mm, the cutting speed 120m / min. and feed pressure 6.90. In figure 9, tempered steel, 42CrMo4, material number 1.7225 with cutting width d = 90mm, cutting speed 90m / min was machined. and a feed pressure of 4.4. In all cases, the superiority of coated saw belts is shown compared to those that do not.

In relatively soft ferritic stainless steel, the best cutting results are achieved with a coated saw belt with a chip exit angle of 10 °. In steels with relatively hard tempering, however, the best result was achieved with a coated saw belt and an exit angle of shavings of 0 °, which is as much or more surprising since an uncoated saw belt with the same Chip departure angle facilitated the worst results.

Another additional sawing experiment was carried out with tempered steel / cold rolled steel 42CrMo4V, material number 1.7225, d = 300mm solid with a cutting speed of 50m / min., Cutting pressure 16 bar and feed 3, and in this In this case, a useful life and surface duration of an uncoated saw belt with an exit angle of 16º was determined, as well as a coated saw band with an exit angle of chips of 0º. Under these conditions, the uncoated saw belt had worn out after 6 hours, with a production of 21 cuts and an area of 1.48 m2. With the coated saw belt, a duration of 8 hours and 53 minutes, 31 cuts and an area of 2.19 m2 could be achieved, which means an increase in the magnitude of cut and corresponding surface area of approximately 50%.

In addition, it was demonstrated in long-term sawing investigations in which the sawing of raw material with a diameter of 91 mm, 16 mm wall thickness of 16MnCr5, material number 1.7131 (HB 140 to 207), which for the In the case of an uncoated saw belt with a chip exit angle of 10 ° after 500 to 600 cuts, the cut over the diameter was 1 mm out of angle. On the contrary, with similar saw belts, but with coating, 900 to 1200 cuts could be achieved without noticeable movement of the saw belt angle. This is all the more surprising since the coated saw belts at the end of their life period retain the angle even if they have been rounded or blunt. Thus, for example, an automated sawing process is possible without problems overnight.

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Claims (6)

1. Procedure for the manufacture of a saw belt (1), in which at least one row of teeth (11) of the saw belt (1) is applied a coating of a hard material by a process of vacuum coating, so that the saw belt is spirally wound in a 5 coil (8) and coated in this way, characterized in that at least the row of teeth (11) of the saw belt (1) wound on the coil (8) before the application of the hard material coating is subjected to brushing for chip removal, that the coating is carried out with a thickness of 0, 5 to 3 µm, and that the material constituting the coating is applied by a PVD procedure or a paCVD procedure or a combination of both at a temperature 10 between 450 and 550 ° C. 2. Method according to claim 1, characterized in that the saw belt is welded in the form of a ring after coating. 3. Method according to one of claims 1 or 2, characterized in that the coating of hard material is applied substantially only to the incidence surfaces (5) and to the chip removal surfaces 15 (4) of the row of teeth (11). 4. Method according to one of claims 1 to 3, characterized in that the coating contains one or more metals of subgroups IV, V, or VI of the periodic system or aluminum or silicon. 5. Method according to claim 4, characterized in that the coating contains nitrides, oxides, carbides, carbonitrides, borides of the aforementioned metals or mixtures thereof. Method according to claim 5, characterized in that the coating contains TiAlN, AlCrN, DLC, TiAlSiN, TiAlCN, metallic or non-metallic WC / C.