DE2715827A1 - Stone cutting wire saw - with abrasive in epoxy blocks mounted in wire slot over flexible metal interlayer - Google Patents

Abstract

A wire saw, e.g. for cutting granite, comprises a laterally flexible endless metal wire loop for driving around a pair of sheaves, spaced blocks of composite comminuted abrasive in a bonding matrix mounted along the wire, and layers of flexible metal each metallurgically bonded to a corresponding block and bonded to the wire by elastically pliant epoxy-based adhesive, and sandwiched between wire and block. The wire is pref. a cylindrical body with a helical slot along its length, the slot twist direction being reversed along the wire and the blocks being mounted spaced in the slot. The layers are e.g. of Cu and promote bonding while imparting mounting resiliency.

Description

Designation: cutting tool

The invention relates to cutting tools, and more particularly to Cutting tools that have emery elements as cutting elements and also the invention relates to a method for manufacturing such cutting tools.

Compositions of finely powdered emery particles, for example Diamond dust or diamond grit deposited in a metallic or ceramic Matrix are increasingly used as cutting elements in tools to cut large blocks to cut minerals such as marble, granite or the like. To the Cutting large blocks of minerals, for example, especially for manufacturing Architectural cladding used to use very large cutting tools, which presented a number of problems. For example, a well-known System a fixed rotating paddle with a number of diamond / metal matrix blocks used, which were installed on the circumference of the blade as cutting elements. Big cuts require a large shovel, e.g. with a radius of 2 m or more. Such rotating blades show the tendency to evade sideways from their plane of rotation. Accordingly, such blades have been made very thick to the required to convey the structural rigidity that seemed necessary to make clean cuts. These thick blades cut a slot of the same thickness and they work therefore slowly and generate a large amount of dust, being valuable mineral material is destroyed, and there is also a great deal of wear and tear on the emery material and as a result an expensive operation.

Instead, it is also known to use oscillating blades, where the diamond components were attached to the cutting edge of the blade. However, the operation of such an oscillating blade is considerably slower than that of a rotating blade and it is quite a complex device required to set the saw blade in oscillating vibrations and a cut considerable size, as required for architectural purposes. In addition, there are the same bending problems and these require the blade must be reinforced and accordingly also becomes thick again and both emery material and mineral material is wasted in cutting. Also are the sowing rates relatively low in these saws due to the limitations of the surface speed, with which the cutting blades can be moved.

In both cases, when using rigid blades, the emery elements, which the cutting units for the system provide, mainly shear stresses resulting from the cutting movement of the saw. Accordingly, he needs Structure that is used to fix the emery components, only the shear forces resist that are substantially parallel to the direction of cutting movement of the blade originate.

There is another system that has so far been used in particular for Cutting large blocks of granite was used and this process uses a twisted one Wire and a slurry of silicon carbide grit as emery elements. This too However, the system is relatively slow and requires a large amount of silicon carbide and this is quite expensive and also requires a large amount of fresh water to be used Wash out and for cooling. This last requirement has been particularly recent Time proved to be a specific problem in relation to the laws against t he pollution that has caused some stone processing plants who used this type of cutting system.

It is already known to use wire saws or band saws for cutting To use minerals of large dimensions. However, it must be taken into account that the emery elements applied to the surface of such a wire not just shear stresses due to the cutting effects the Saw exposed, but because the wire saw or the band saw the shape has an endless belt, a bend must necessarily be made around deflection pulleys, so that the saw must be laterally flexible for proper operation. Emery elements, that are attached to the saw must necessarily withstand the tensile forces, which result from the bending movement of the blade and lead to the binding of the To weaken emery elements or even to peel the elements, so that finally the insert bodies have fallen out of the carrier.

Composite emery parts made by mixing diamond grit, E.g. in the installation in a metal matrix, have been used in known systems with the metallic substrate in most cases either by electrolytic Connection or connected by sintering processes.

In known electrolytic joining techniques are typically If relatively long and commercially unacceptable storage times are required, especially when relatively dense deposits are desired. Also are often Oxide films are present on the metallic substrate, which adversely affect the adhesion can. Accordingly, electrolytic deposits have hitherto been in an inert or carried out in a reducing atmosphere and in certain cases a flux applied to the metallic surface prior to deposition. These procedures obviously increase the manufacturing cost.

Sinter bonding techniques are usually faster than known ones electrolytic joining processes, but they require elevated temperatures that turn into other problems. For example, the sintered bond typically require temperatures as high as 80 ç or more of the melting temperature (in degrees Kelvin) of the connection matrix. Typically this can be metallic or ceramic material, which forms the matrix, at 120ob to 1500 ° K or more can be decomposed. At such temperatures the properties of the metallic substrate are adversely affected. Even the diamond that Exposure to such temperatures can deteriorate due to graphitization will. A graphitization of diamonds takes place relatively quickly with a Temperatures of around 1000 ° K and even below 1000 ° K can still cause graphitization occur, albeit at a slightly lower rate. The latter problem can be solved by the sintering process in a non-oxidizing atmosphere is carried out, but this then again requires increased costs.

In addition, emery materials that come with a wire or applied to a tape by sintering or by electrolytic bonding, has not been found to be satisfactory because the compounds generally do not have any Have long-term stability.

Another method of connecting emery elements to metallic ones Substrates are there to be soldered. This is where the grinding tool produced by having one or more cutting elements on the metallic Substrate are soldered, which can be designed as a wire or band saw. The soldering requires at least three layers, namely a flexible elastic one metallic layer enclosed between two binder layers of metal and melted below the melting point of the substrate or matrix metal and in this way adheres to both. In order to carry out the soldering, lays place the three-layer body between an emery block and the substrate and holds the block, sole body and substrate together under pressure and heats then the layered body to soldering temperature by inserting an electric wire through it Substrate is sent.

An advantage of this method is that the heating relative can be done quickly, with the result that the diamond particles become a high temperature are only exposed for a relatively short time, so that high temperature damage the diamond can be kept to a minimum. Another benefit is there in that the extensive systems can be omitted, which in known systems were required, e.g. systems for heating in an inert or reducing The atmosphere. On the other hand, those manufactured in this way can possibly Abrasive tools do not appear to have the desired strength This is because the metallic substrate is occasionally due to the heating on the required soldering temperature is weakened.

The invention is therefore based on the object of a novel wire saw and to provide a method of making this wire saw, whereby the problems inherent in known systems are avoided. Another goal of the Invention is to carry out such a method in such a way that it is on the whole simpler than many of the known processes and in particular It is the purpose of the invention to provide a method by which a composite Matrix is attached to a substrate that must be bent, the attachment takes place so that a continuous bending of the substrate at least up to one limited extent there is no fear of a harmful solution of the parts. Another one An important aim of the invention is to create a new type of wire cutter, which is a quick and economical cutting of large blocks from architecturally usable material allows cutting at high speeds and a small cutting gap can be carried out.

According to the invention, the object is achieved in that a cutting tool is made by having one or more composite Elements made of powdered Abrasives in a matrix glued to a metallic substrate. The adhesive consists of one elastic, resilient epoxy material, e.g. an epoxy synthetic resin. According to a preferred embodiment of the invention is a relatively thin layer or film made of a flexible metal, e.g. copper, metallurgically connected to the metal matrix and placed between the mated elements and the epoxy adhesive. The metal film acts as a shock absorber and also improves the bonding of the epoxy resin.

A steel wire is preferably used as the metallic substrate, that under extreme tension just below its elastic limit is negligible Has extension and the wire preferably has two helical lines Grooves that run in the opposite direction. The cutting elements are shaped into the grooves used by spaced apart teeth, with an elastic compliant epoxy adhesive is used. The wire is in an endless belt arranged and is held under tension between at least two Rdlen, the Have grooves which are lined with a comparatively soft elastic material are, on which the emery elements can attack, serve that an essential Distortion, cutting, or damage occurs.

An exemplary embodiment of the invention is described below with reference to FIG Drawing described. The drawing shows: FIG. 1 a perspective partial view a saw wire designed according to the invention; Fig. 2 on a larger scale Section along line 2-2 of FIG. 1.

The drawing shows a saw wire 20 with a substrate body 22 made of metal, for example in the form of a steel wire or the like. The substrate body 22 has a substantially elliptical one according to the illustrated embodiment Cross-section, but this body 22 can also have a different cross-sectional shape, it can e.g. be circular, triangular or square. The body 22 carries several Abrasive segments or blocks 24 as described in detail below.

The wire body 22 has one or more relatively thin narrow ones Notches or slits in its surface that run diagonally along its length. Preferably, the slots 26 are in the form of elongated grooves that e.g., as shown in Fig. 1, as a helical line around the longitudinal axis of the wire 22 can be performed. It is clear, however, that the slots 26 also consist of several short notches, preferably on a helical line along the Wire 22 lie. In any case, it is useful that the twisting direction of the helical line is reversed over the length of the wire (e.g. every 4.50 m to 6 m, as shown at 27). This latter feature results in how has shown a particularly favorable surface with regard to the use of the As a band saw.

Several relatively short emery segment blocks 24 are spaced in the slots 26 arranged. The blocks 24 typically consist of one Mixture of diamond particles, e.g. diamond lumps and grit 28 in a binding matrix 30, as is known per se. The size of the diamond particles 28 and the proportion the particles relative to the binding matrix are not critical to the invention and can widely changed, as is known. So can the blocks 24 contain diamond particles, for example, which range in size between Change 1 to 1200 and they can be in an amount in a range between 5 and 74 volume percent based on quantity the binding matrix provided will.

The sanding blocks 24 are in the slots 26 through a film 32 held by an elastic, resilient epoxy adhesive.

There are many epoxy-based adhesives known and commercially available that have utility here. A typical epoxy resin which can be used here can be obtained by reacting bisphenol A and epichlorohydrin according to the following general formula: H2COCHCH20 (RCHOHCH20) nROC, 5, CHOCH2, where R 5 is C6H4C (CH3) 2C6H4.

Variations of these basic compositions can be created by that the ratio between bisphenol A to epichlorohydrin is changed, or that the reaction conditions and the catalyst or final curing agent changed will. Such epoxy resins are typically relative prior to curing Viscose liquids or they can be solids with a relatively low melting point below 1750C. The curing requires a further reaction of the epoxy and the hydroxide groups to cause chain growth and cross-bonding and this is typically achieved by heating.

The reaction can also be carried out by the presence of a catalyst e.g. Boron trifluoride amine or polyamine, a double basic acidic anhydride or a phenolic or a urea resin can be achieved. The epoxy and hydroxide groups can also are esterified, with unsaturated monobasic acids and then takes place Curing with catalysts containing an alkyd synthetic resin. The hardened Epoxy materials are typically referred to as epoxy resins. You own a high adhesive force, which in certain cases can be greater than that of the binding matrix 30th

As mentioned, the wire must be flexible. In order to crack the Matrix 30 to be avoided by forces that occur during the bending of the wire 20 and to resist the tendency to expel the abrasive grit, there is one essential feature of the invention in the ability of the connection system to to bend and to absorb the forces that occur when the wire 20 is bent. Also, the connection system should act as a cushion to prevent the blocks from falling 24 touch the wire. In certain cases, the epoxy layer 32 can be sufficiently flexible designed to meet the requirements for flexibility and cushioning. E.g. mixtures of epoxy resins with one or more polyamine resins, Polysulfide rubber and polyurethanes can be made as is known. These Mixtures have great strength and flexibility.

On the other hand, known break-proof epoxy adhesives do not need to be used necessarily have the flexibility required for the invention. In In such cases, the necessary flexibility and cushioning is created the connection is a relatively thin film 34 of a flexible metal, for example Copper metallurgically on the block 24 as an interface between the blocks and the Adhesive 32 set. The use of a copper layer gives an additional one Flexibility of the connection between the blocks 24 and the body 22. This increased Flexibility has two advantages. First, materials such as cobalt which have particularly good wear characteristics and are known to have good ones Allow connection with diamonds, but are relatively brittle and flexible, successful can be used as the main matrix material. Another advantage is that the wire can be bent around a comparatively small radius, with the result that the wire saw according to the invention in most already existing Wire saw devices can be used without modification. If necessary, can the bottom surface of layer 34 also be roughened like this is indicated at 36 in order to enlarge the surface and a ~ key " for the adhesive layer 32 to form. So the strength of the connection between blocks 24 and wire 20 are further increased. Instead, the blocks 24 consist mainly of copper as the matrix material, with a copper content up to about 70% copper or some other ductile metal can be provided and small amounts of other metals, e.g. Iron, zinc, tin, titanium, chromium, Zirconium, or the like can be included.

The use of copper as the main matrix material can make the blocks 24 give sufficient flexibility so that the film layer 34 is not required is. On the other hand, copper doesn't wear as well as cobalt and it also bonds not as solid with diamond as cobalt. In any case, the blocks 24 are considered uniform Mass for example by sintering the connection matrix (and the film) known techniques.

Layers 32 and 34 can be the same or different Thickness, depending on the nature of the epoxy resin used and depending on the length of the adhesive connection lines, the flexibility, the adhesive, the Matrix material and film material as well as the flexibility and the required Cushioning. Preferably, layers 32 and 34 are so thick that substantially the slot 26 is filled in, causing the blocks 24 to be close to the surface of the wire 20 can be arranged. For example, when the slots 26 are approximately 0.5 mm are deep along their length, then the two layers 32 and 34 can typically Case 0.25mm thick. These layers 32 and / or 34 form a cushion or one Boundary layer that prevents diamond particles in the blocks 24 from entering the layers enter and cut into the wire 30 and accordingly stress concentration points where the wire could break.

To make a wire saw according to the invention, an adhesive layer 32 introduced into the slots 26, e.g. in liquid form, before hardening. then the emery blocks 34 with the layer 54 connected to them are in the slots 26 placed on the layer32. Then the blocks are clamped under pressure and the layer 32 and the blocks and the body 22 are then hardened by the Adhesive bonded together, creating an epoxy body. During the Curing can optionally be done depending on different heat treatment Factors, particularly with regard to the composition of the adhesive and of the hardener used. When hardening is carried out using heat the temperatures used must be compared with those used during soldering Temperatures be low. So a typical epoxy resin curing temperature can be in the range between 125 and 1750C, compared to soldering temperatures that are typical 0 case at 700 C or higher. The connection method according to the present Invention has a number of important advantages. On the one hand, the heating, though it is required to be carried out at relatively low temperatures with the result that the diamond particles are also not exposed to high temperatures that could damage the diamonds. Further The advantages are that the large systems required in the known processes can be saved, which were required, for example, to make an electrolytic To carry out bonding or a sintered bond in an inert or reducing atmosphere.

An exemplary embodiment of the invention is described below with reference to FIG Drawing described: Example I Figures 1 and 2 show a wire saw, which was made according to the teachings of the present invention.

A steel wire manufactured by Hamilton Precision Metals, Lancaster, Pennsylvania, USA "and under the designation No. 250 is distributed. According to the manufacturer, it is a cold one Machined steel, which is about 18% nickel, 7.7% cobalt, 4.9% molybdenum, 0.4% titanium and less than about 0.1% carbon, manganese, silicon, aluminum, boron, zirconium and contains calcium in percent by weight. The rest is iron. This material with a cross section of 1.3 cm2 has a tensile strength of approximately 190 kg / mm2 maximum.

In the surface of the wire substrate are two helical lines Grooves 26 cold rolled to make cuts and weakenings on the inner surface of the grooves 26 to avoid. The slots 26 have a width of about 2.4 mm and a depth of about 0.43 mm along its entire length. The slots 26 complete one turn on wire 22 every 90 cm. The screw grooves are outside around 1800 Phase to each other. The rising direction of the two helical grooves is all 4.5 m over the length of the wire 23 reversed.

The emery element blocks 24 are made as follows: The blocks 24 consist of a uniform mass of diamond particles in a binding matrix. The diamond particles consist of a mixture of diamond particles of different types Size as follows: 20 percent by volume with 20 to 30 mesh, 30 percent by volume with 30 up to 40 mesh and 50 percent percent with 40 to 60 mesh (all mesh sizes are Tyler Standard screen scale information). The diamond particles are bonded with a matrix mixed, which is about 69% copper, 11% zinc, 8 ffi ivory, 2% tin, 3% titanium, Contains 2% chromium, 1% zirconium and the remainder 4% of Isi-Flo No. 3 (the latter is a solder powder manufactured and sold by Hardy and Harman, New York is.) The manufacturer describes this solder powder as a product, which is approximately 50% silver, 16% cadmium, 15.5% copper and 15.5% zinc and 3 % Contains nickel (all in percent by weight). The mixtures of diamond particles are mixed with the binding matrix in a small volume ratio of 1:10. The mixture of diamond particles and binding matrix is pressed into blocks with a length of 12.7 mm, a width of 2.5 mm and a height of 1.8 mm. Oxygen-free Copper foil material with a length of 12.7mm, a width of 0.25mm and a Thickness 9f of 0.25 mm is clamped onto one side of the blocks thus pressed. the Blocks with the copper foils are then heated to cure the bonding mixture, typically at a temperature of 9550C and this temperature remains Received for 3 to 5 seconds. The resulting blocks have a Length of approximately 12.7 mm, a width of approximately 2.5 mm, and a height of 2.03 mm. They have a metallurgically defined layer 32 of copper of about 0.25 mm thickness on one side of the block.

An epoxy / nylon-based adhesive is used as an adhesive, which under the name EA 9651 from

Dexter Chemical Corporation, Olean, New York / USA. According to the manufacturer, this adhesive should have a high strength and peel resistance Be epoxy nylon. It is available as a solvent-free film 0.25 mm thick. This adhesive requires curing for 60 minutes at 2000C.

A film of this adhesive is placed in the slots 26.

The blocks 24 so pressed and sintered are then inserted into the slots 26 with the copper layer on the inside adjacent to the epoxy film and at a distance of 12.5 mm.

Then the blocks are in place on the wire with a 2 push of a button Exposed to 0.017 kg / mm.

Then the wire 20 with the blocks 24 arranged on it is heated, to raise the temperature of the structure to around 1750C and the The temperature is maintained for 60 minutes and then air cooling is applied. After the pressure is removed from the blocks 24, it is found that they are firmly with the substrate of the wire 20 are connected.

The wire was used to cut granite blocks over 200 hours, without showing any error.

Example II The procedure of Example I was repeated, however the copper layer was omitted and a type 2214 adhesive was used, made by Minnesota Mining and Manufacturing Company, St. Paul, Minnesota, will be produced. The manufacturer describes this adhesive as highly flexible Epoxy adhesive, which is filled with aluminum. The adhesive is with Room temperature a viscose liquid and there is curing at 1200C for 60 minutes long carried out. The adhesive is supplied in such an amount that the Slots 26 are essentially filled. A wire saw is then obtained, which is structured as in example I.

Claims (5)

Claims: Wire saw, consisting of a metal wire that a sufficient elasticity has to run as an endless wire over pulleys to be done by making a multitude of blocks of composite powder emery material in a connection matrix at a distance is attached to each other in the wire body and that several layers of flexible Metal metallurgically attached to each block and between the wire and the block be arranged so that these layers are essentially completely between each block and the wire extend, each of the layers with the perimeter of the Wire is connected by an elastic epoxy adhesive. 2. Wire saw according to claim 1, characterized in that g e k e n n z e i c h -n e t that the wire has a cylindrical cross-section, in the at least one Helical groove is formed and that the blocks are spaced apart in this Groove are set. 3. Wire saw according to claim 2, characterized in that g e k e n n z e i c h -n e t, # ß the direction of rise of the screw grooves along the length of the wire, respectively alternates. 4. A method for producing a wire saw according to the claims 1 to 3, in that the blocks are pressed into a Groove filled with the epoxy adhesive are pressed in and that the adhesive then cures will. 5. The method according to claim 4, characterized in that g e k e n n z e i c h -n e t that each of the blocks has a layer of flexible metal between the Blocks and the surface of the wire is arranged so that they extend over the the entire area between the block and the wire.