Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
  • B21C37/00—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape
  • B21C37/06—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape of tubes or metal hoses; Combined procedures for making tubes, e.g. for making multi-wall tubes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
  • B21C23/00—Extruding metal; Impact extrusion
  • B21C23/02—Making uncoated products
  • B21C23/04—Making uncoated products by direct extrusion
  • B21C23/08—Making wire, bars, tubes
  • B21C23/085—Making tubes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
  • B21C23/00—Extruding metal; Impact extrusion
  • B21C23/22—Making metal-coated products; Making products from two or more metals
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
  • B21C33/00—Feeding extrusion presses with metal to be extruded ; Loading the dummy block
  • B21C33/004—Composite billet
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/4981—Utilizing transitory attached element or associated separate material

Definitions

• the invention relates to a method for producing hollow profiles, in particular pipes, with a small outside diameter and / or a small wall thickness from a nickel-titanium alloy by forming a composite block.
• Alloys with a titanium content between 49.7 to 50.7 atom% show a thermal shape memory, also called shape memory
• alloys with a titanium content from 49.0 to 49.4 atom% show a mechanical shape memory, also called super elasticity.
• a shape memory alloy can contain ternary components (e.g. iron, chromium or aluminum). The ratio of nickel and titanium as well as the presence of ternary additions have a great influence on the shape of the thermal and mechanical shape memory; even small changes in concentration result in major changes in the material properties.
• an alloy with a suitable composition is converted from the austenitic structure into the martensitic structure by cooling without diffusion. Subsequent deformation of a component made from this alloy can be reversed by thermal treatment of the component (heating to temperatures above a certain transition temperature). The original austenitic structure is restored and the component takes on its original shape.
• the transition temperature is generally the temperature at which the martensite is completely converted to austenite.
• the transformation temperature is strongly dependent on the composition of the alloy and the stresses prevailing in the component. Components that show a thermal shape memory can generate movements and / or exert forces.
• the mechanical shape memory effect occurs in a component made of a suitable alloy with an austenitic structure if the component is deformed in a certain temperature range. It is energetically more favorable for the austenitic structure to convert to martensite under stress-induced conditions, whereby elastic strains of up to ten percent can be achieved. When the load is released, the structure returns to the austenitic phase. Components made of such an alloy can therefore store deformation energy.
• Alloys which show the properties described above are known under the terms nickel-titanium, titanium-nickel, tea-nee, Memorite R , Nitinol, Tinel R , Flexon R and shape memory alloys. These terms do not refer to a single alloy with a specific composition, but to a family of alloys that show the properties described.
• shape memory alloys In many technical fields, e.g. medical technology and precision engineering, due to the special properties of nickel-titanium alloys, there is great interest in using components made from shape memory alloys. In mechanics, they can be used for switching, adjusting elements or valves, for example. Shape memory alloys are also increasingly being used in medical technology, since components made of such alloys are body-compatible and fatigue-proof and, in the case of super-elastic alloys, also show a high resistance to buckling.
• Examples of the use of nickel-titanium alloys in medical technology, in which the preliminary product is a nickel-titanium tube, are stents, catheters and endoscopic and laparoscopic instruments for minimally invasive diagnosis and therapy.
• preliminary products in the form of tubes, in particular with a small outside diameter, are also required.
• nickel-titanium tubes are made by drilling forged bars.
• the tubes typically have an outside diameter between 12 and 25 mm. Due to the poor machinability of nickel-titanium alloys, the deep hole drilling process is very complex, which leads to short tool downtimes, long machining times and high manufacturing costs for the pipes. Furthermore, there is a high loss of material, particularly in the manufacture of thin-walled pipes. The chips generated during drilling or turning represent lost material.
• European patent specification 0459909 describes the production of a seamless tube from a corrosion-resistant alloy consisting almost entirely of titanium by means of a tube extrusion process.
• a perforated press block is pressed by means of stamp pressure through a gap remaining between a press mandrel and a die.
• the pipes produced in this way are used after subsequent forming work, for example to heat brines in seawater desalination plants and as heat exchanger pipes in chemical production plants.
• a method of extruding composite blocks with a lost core without a press mandrel is known from document WO 96/17698.
• a hollow-drilled block is filled with a steel core and then pressed together once.
• the geometry of the hollow-shaped press product depends on the geometry of the press die and the core. The larger the core in relation to the die, the thinner the tube.
• this type of block preparation therefore leads to a considerable waste of material, which is a significant disadvantage in the case of nickel-titanium alloys.
• this method has the disadvantage that the metal core forms an intimate metal connection with the nickel-titanium material in the pressed product through the forming process, so that an additional processing step is required to remove the core material in order to obtain a hollow-shaped pressed product , for example by drilling out and / or chemically triggering the core material. Furthermore, the desired small profile dimension cannot be achieved in all cases by extruding the composite block.
• the invention has for its object to provide a method with which hollow profiles or tubes made of a nickel-titanium alloy with a small outer diameter and / or a small wall thickness can be produced inexpensively and efficiently.
• the hollow profiles or tubes can have any cross-sectional shapes.
• a tube is also understood to mean any profile tube or hollow profile.
• a method for producing hollow profiles with a small outside diameter and / or a small wall thickness from a nickel-titanium alloy by reshaping a composite block in which a composite block is formed in a first step, which has a solid core made of a nickel -Titanium alloy, a first hollow block of a nickel-titanium alloy surrounding the core and a separating layer between the first hollow block and the core.
• the composite block is formed by means of a forming process
• the first hollow block, which is formed into a first hollow profile, and the shaped core are removed from the formed composite block.
• the invention is based on the idea of reducing both the machining outlay and the lost waste amount of nickel-titanium by stabilizing the hollow block during the shaping with a tern, the core itself being deformed and in terms of both its material and its shape for another use suitable.
• the core consists of a nickel-titanium alloy.
• the core which is formed into a solid full profile, can, for example, be used as wire or used as a semi-finished product in further processing steps. In this way there is less waste of the starting material, which is expensive to manufacture.
• a nickel-titanium starting material is thus divided into zones, and the interstices are filled with a separating layer, for example a non-metallic powder material, which does not combine with nickel-titanium.
• a separating layer for example a non-metallic powder material, which does not combine with nickel-titanium.
• the dimensions of the formed products depend on the geometry and the zone division in the composite block and the selected forming process. The number and diameter of the individual zones can be varied and is based on the desired formed products.
• the function of the material forming the separating layer is to prevent the individual zones from touching before, during and after the shaping of the composite block, in order to ensure that the individual parts of the shaped composite block can be easily separated from one another after the shaping.
• a first advantageous embodiment can consist in that the composite block is reshaped by means of an extrusion process, in which the composite block is inserted as a heated press block into a block receiver of a press and is pressed through the opening of a die by pressing a press ram.
• the hollow block which is to be extruded into a tube, is inserted with one during extrusion Core stabilized. The ker can be removed after extrusion.
• the method according to the invention is comparable to a step from a multiple composite extrusion method, but in contrast to the classic, repeatedly repeated composite extrusion, a single extrusion may be sufficient and, furthermore, the components of the composite strand obtained after the extrusion are separated to obtain a tube .
• Another advantageous embodiment of a forming process can consist in that the composite block is formed by means of a hot drawing, cold drawing, rolling, round hammer or pilger process.
• the tube formed is stabilized by the core during the forming.
• the core is pushed into the first hollow block, in particular into a hollow profile, preferably into a tube.
• a tube is a tubular hollow block.
• the composite block is formed with one or more further hollow blocks which are arranged around the first hollow block and each have a separating layer between adjacent hollow blocks, in the second step the plurality Hollow blocks and the core comprising composite block is formed. This is particularly advantageous in order to produce several thin-walled hollow profiles in one forming step.
• the composite block is formed by pushing together a plurality of hollow blocks, in particular hollow profiles, preferably tubes.
• hollow blocks in particular hollow profiles, preferably tubes.
• the hole can be drilled or milled into a block or through a block. Since this inevitably leads to a loss of material, even if the hole, with the exception of the separating gap, is filled by a solid profile, it is proposed according to a preferred feature of the invention that the composite block, a hollow block or the core by EDM or wire EDM a solid nickel Titanium blocks, a nickel-titanium hollow block or another nickel-titanium workpiece is formed.
• nickel-titanium workpieces can advantageously be processed by means of a spark erosion method, in particular by means of countersinking or wire EDM, in particular when a part, in particular a solid core or a hollow profile, is removed or separated from a Block.
• a spark erosion method in particular by means of countersinking or wire EDM, in particular when a part, in particular a solid core or a hollow profile, is removed or separated from a Block.
• the use of a tubular electrode made of copper or a copper alloy is preferred.
• the method according to the invention relates to the production of pipes made of a nickel-titanium alloy, in particular a shape memory alloy described above.
• the alloys used can be binary or contain ternary additions.
• the method is preferably used to produce tubes from a nickel-titanium alloy with superelastic properties.
• the core which is formed into a solid full profile, also preferably has superelastic properties.
• the outer diameter of the pressed composite block and thus the outer tube depends on the diameter of the opening of the die, which cannot be chosen to be as small as desired. The smaller it is, the greater the pressure to be applied for pressing and the shorter the service life of the pressing tools.
• the formed composite block is, in an advantageous embodiment, removed in a second hole, which has been incorporated into a further hollow block made of a nickel-titanium alloy, before removing the reduced core, with the formation of a multiple composite block which forms the comprises further, perforated hollow block and the first, formed composite block with the reduced core, the second composite block thus formed forming a separating layer between the as the core serving first composite block and the second composite block.
• a multiple composite rod is then extruded from the multiple composite block, the diameter of the further perforated hollow block, the first hollow block and the core being reduced. This also applies to composite blocks with multiple layers and other forming processes.
• the formed multiple composite block comprises a second tube formed by the second, reduced hollow block, the first, further reduced tube and the further reduced core.
• the tubes are separated and the reduced core is removed.
• this two-stage forming for example extrusion, it is possible to work with a larger die opening, which has an advantageous effect on the pressing pressure to be applied and the service life of the pressing tools.
• two extruded tubes with different diameters are available for further processing.
• the reshaped multiple composite block before the tubes are separated and the core is removed, is inserted into a further hole which has been incorporated into another hollow block, and the further multiple composite block thus formed is reshaped to produce another tube.
• the insertion and shaping can be repeated, with each tube forming a further tube.
• a hole is worked into the block to be formed or into the required hollow blocks, the diameter of which is preferably between 10 mm and 60 mm, preferably between 20 mm and 40 mm.
• the hole is preferably eroded, but can also be machined into the material in a different way.
• a continuous hole compared to a blind hole has the advantage that no massive piece, i.e. a section of the extruded rod without a core is formed, which must first be cut off to produce a tube and represents lost material.
• the composite block is formed to a diameter which is essentially the diameter of the first hole in the core Before the forming corresponds - In this way, the formed composite block can be used in a further hollow block with the same core diameter as the previous hollow block to form a multiple composite block.
• the multiple composite block can also be formed to a diameter which essentially corresponds to the diameter of the composite block serving as the core before the forming.
• the formed multiple composite block can be used in a further hollow block with the same core diameter to form a further multiple composite block.
• the required diameter of the formed composite block or multiple composite block is achieved by appropriate dimensioning of the forming tools.
• These process variants include the advantage that holes with a uniform diameter can be worked into the required hollow blocks, which reduces the effort required for the block preparation.
• the outer diameter of the first hollow block or tube after the first forming step is advantageously less than 40 mm, preferably less than 25 mm.
• the wall thickness of a thin-walled tube is usually between 2% and 10% of the outside diameter.
• FIG. 10 shows a longitudinal section to FIG. 9,
• FIG. 11 shows a cross section of a die-eroded block divided into three zones
• FIG. 12 shows a longitudinal section to FIG. 11,
• FIG. 14 shows a longitudinal section to FIG. 13,
• FIG. 16 shows a longitudinal section to FIG. 15,
• FIG. 17 shows a longitudinal section of the composite block from FIG. 14 or 16 during extrusion
• Fig. 19 is a cross section corresponding to Fig. 11 and
• Fig. 20 shows the cross section of Fig. 19 after forming.
• the first hollow block 1 shown in FIG. 1 is made of a shape memory alloy with superelastic properties, for example forged.
• a continuous first hole 7 is worked, for example drilled.
• the diameter dl of the first hole 7 is approximately 30 mm.
• a sliding layer 2 made of a friction-reducing material is applied to the outer surface of the first hollow block 1.
• the sliding layer 2 comprises copper and was applied by inserting the first hollow block 1 into a copper tube with a corresponding diameter.
• a copper layer can also be applied, for example, by plasma or flame spraying.
• the sliding layer 2 can also consist of glass or another material. Copper has the advantage over a sliding layer made of glass that is often used in extrusion that it can also serve as a sliding layer in a subsequent cold forming process, for example drawing. A sliding glass layer, on the other hand, must first be removed in order to protect the forming tools.
• the sliding layer 2 can also comprise other materials, in particular graphite applied as a paste or a ceramic substance applied as a slurry.
• the total diameter d2 of the first hollow block 1 including the applied sliding layer 2 (hereinafter referred to as the press block diameter) is approximately 110 mm in the exemplary embodiment shown.
• a sliding layer 2 could be dispensed with if a material is used for the forming tools (for example in extrusion) for which the nickel-titanium alloy has essentially no shows welding, or a forming process is selected in which there is no welding.
• a core 3 is inserted into the first hole 7 of the first hollow block 1 to form a composite block 10, the diameter d3 of which, including an applied separating layer 4 (hereinafter referred to as the core diameter), essentially corresponds to the diameter d1 of the first hole 7.
• the core 3 also comprises a nickel-titanium alloy. When pressed, it thus shows the same flow behavior as the first hollow block 1.
• an alloy composition was selected for the core 3 which has a higher martensite-austenite transformation temperature than the alloy of the first hollow block 1. This is advantageous for the removal of the core 3 described below after the shaping.
• the core 3 has the task of stabilizing the first hollow block 1 when it is formed into a first tube. Furthermore, since its diameter is also reduced when it is pressed out, it determines the inside diameter of the first tube. It is therefore advantageous if the core 3 has a material that shows a similar or the same flow behavior as the alloy of the first hollow block 1 during the forming. In this way, the composite block diameter d2 and the core diameter d3 are uniformly reduced during the shaping, ie the ratio of the cross-sectional area of the first hollow block 1 including the sliding layer 2 to the cross-sectional area of the core 3 including the separating layer 4 remains essentially the same before and after the shaping. Thus, the outer and inner diameter of the resulting pipe can be used for given starting conditions (in particular composite block diameter d2, core diameter knife d3, diameter of the die opening during extrusion) can be calculated.
• the core 3 also comprises a super-elastic alloy.
• the core 3 can comprise a copper-chromium alloy. This shows a similar flow behavior as the nickel-titanium alloy of the first hollow block 1.
• a temperature-resistant separating layer 4 made of copper is applied to the core 3. It can also have other materials, in particular graphite, talc, a mixture with talc or a ceramic substance such as, for example, aluminum oxide, magnesium oxide or titanium oxide.
• the separating layer 4 has the task of preventing a diffusion of atoms between the core 3 and the first press block 1 during pressing.
• a core 3 produced by means of a forming process is used.
• a sliding layer 4a made of copper is applied to a solid core press block 11 made of a shape memory alloy.
• the core press block 11 is formed into a strand by means of a known forming process, for example an extrusion process.
• the strand is cut to length, as a result of which the actual core 3 is formed (FIG. 3).
• the sliding layer 4a located on the outer surface of the core 3 can serve as a separating layer 4 in the further process.
• the core 3 can be produced by means of the forming or extrusion process according to the invention.
• the core 3 is inserted into the first hole 7 of the first hollow block 1, as shown in FIG. 1. If the core press block 11 has been pressed out without a sliding layer 4a, a separate separating layer 4 is applied to the resulting core before insertion.
• the forming by extrusion is explained with reference to Figures 4 and 5.
• the composite block 10 from FIG. 1, which comprises the first hollow block 1 and the core 3 is heated to approximately 900 to 950 ° C. and inserted into a heatable block receiver 16 of a press 15.
• the temperature depends on the alloys used.
• the extrusion temperature can typically be between 850 and 950 ° C.
• these can be heated separately to different temperatures before being pressed out, then joined together and then pressed together to form a formed composite block 12.
• the die 17 and the block receiver 16 are fixed.
• a press ram 19 moves downward in the direction of arrow 21 and exerts pressure on the composite block 10.
• the latter moves relative to the block receiver 16 and is pressed out through the opening 18 of the die 17 as a deformed composite block 12.
• the composite block 10 is preferably pressed out by indirect extrusion (FIG. 5).
• the die 17 arranged at a tip of a hollow punch 20 moves for pressing out as a result of the pressure of the press die 19 relative to the block receiver 16 and the composite block 10 inserted therein. It penetrates into the composite block 10 while it passes through the opening 18 of the die 17 and the hollow punch 20 is pressed as a formed composite block 12.
• the indirect extrusion has the advantage over the direct one that essentially no different flow velocities occur between near-edge and further inner areas of the composite block 10 during the extrusion. This results in a largely homogeneous material flow, which counteracts an undesirable fluctuation in the wall thickness of the resulting pipe. Because of the lower pressing force requirement and better material flow due to the lack of friction between the transducer and the press block, indirect extrusion is preferred.
• a first tube is formed from the first perforated hollow block 1 as a formed hollow block la and a reduced core 3a from the original core 3, which are components of the formed composite block 12 ( Figure 6).
• Figure 6 A comparison between Figure 1 and Figure 6 shows that both the composite block diameter d2 and the core diameter d3 were reduced by the pressing. It can be seen that the press ratio was chosen so that the outer diameter d4 of the formed composite block 12 essentially corresponds to the core diameter d3.
• the pressing ratio in the present case is approximately 14: 1.
• the reduced core 3a can be removed from the tube 1a after a single shaping.
• the shaped composite block 12 is treated mechanically to remove or loosen the reduced core 3a.
• the reduced core 3a is stretched at a temperature below the transition temperature of the core material. At this temperature, the tube la remains in the austenitic and thus elastic state, while the reduced core 3a is plastically deformed in the martensitic region. As a result of the expansion stress, the reduced core 3a becomes longer (change in length up to 10%) and thinner and can therefore be pulled out of the tube 1a.
• the stretching is preferably carried out by clamping the reduced core 3a on one side and the tube 1a on the other side.
• Other options for mechanically loosening the reduced core 3a are, in particular, flexing, rolling and hammering the composite block 12.
• the composite block 12 can also be subjected to a thermal shock treatment. As a result of material or composition differences, voltages are induced which lead to the loosening of the reduced core 3a in the tube 1a, so that it can subsequently be pulled out.
• the composite block 12 can also be chemically treated in order to to remove or loosen the induced core 3a.
• the composite block is treated, for example, with nitric acid, which dissolves or dissolves the reduced core 3a, but does not attack the nickel-titanium tube.
• Mechanical, chemical or thermal methods for removing or loosening the reduced core 3a can also be used in combination.
• the parts can be separated without complex processes, for example by simply pulling them apart.
• the composite block 12 can be cut to length before the reduced core 3 a is removed and into a second hole 8 that has been machined into a second hollow block 5 made of a nickel-titanium alloy , are used to form a multiple composite block 13, as shown in FIG.
• the sliding layer 2 on the composite block 12 from the first pressing process can serve as a separating layer. If the composite block 10 has been pressed out without a sliding layer 2, a separate separating layer is applied to the composite block 12 before it is inserted into the second hole 8.
• a sliding layer 6 made of copper is also applied to the outer surface of the second hollow block 5, the outer diameter d5 of which, including the sliding layer 6, is approximately 110 mm.
• the diameter d6 of the second hole 8 corresponds to the diameter dl of the first hole 7 in the first hollow block 1.
• the multiple composite block 13 formed in this way which comprises the second hollow block 5 and the composite block 12 with a reduced core 3a, is extruded, for example, to an outer diameter d7 which essentially corresponds to the diameter Knife d6 corresponds to the composite block 12 used, reshaped (FIG. 8).
• the diameters of the second hollow block 5 and the composite block 12 are reduced.
• the formed multiple composite block 14 comprises a second tube 5a formed by the second hollow block 5, the further reduced, first tube 1a and the further reduced core 3a.
• the second tube 5a has an outer diameter of approximately 30 mm and an inner diameter of approximately 8 mm, while the first tube 1 a has an outer diameter of approximately 8 mm and an inner diameter of approx.2.2 mm.
• the reduced core 3a is removed as described above.
• the concentric, one inside the other tubes la, 5a of the multiple composite block 14 are separated.
• the tubes la, 5a thus produced are available for further forming work.
• the formed core 3a can be used as wire or processed further.
• the second forming stage can be followed by one or more further forming stages before the tubes 1a, 5a are separated and the reduced core 3a of the multiple composite block 14 is removed, in order to further reduce the tube diameter.
• the reduced core can also be removed with one or more internal tubes and replaced with another core.
• FIGS. 9 to 20 illustrate a method according to the invention for producing thin hollow profiles made of nickel-titanium alloys, in which the starting material is divided into three zones and the intermediate zones are filled with non-metallic powder materials.
• the Forming is preferably carried out by extrusion, whereby an extruded product is formed in which the zone structure is retained. Due to the powder material in the intermediate zones, the individual parts do not come into contact with one another, so that they can be separated into a hollow tubular profile with different diameters and a solid profile after being formed.
• FIGS. 9 to 20 show an embodiment with a core and two tubular hollow blocks arranged around it, each with intermediate spaces between them. Other variants can only comprise one or more than two hollow blocks.
• FIGS. 9 to 12 illustrate how a solid, cylindrical nickel-titanium starting material is divided into three zones comprising the core 3, the first hollow block 1 and the second hollow block 5.
• the division can preferably be carried out by spark erosion.
• the division takes place by wire EDM.
• wire EDM With a wire that is thinner than the joint width, the starting material can be cut along the circumference of the joint both on its inner and on its outer diameter.
• the process of wire EDM has the advantage that little waste material arises, since a compact, recyclable sleeve with the dimensions of the separating joint 23 or 24 is created.
• There are basically two ways of carrying out the process If the eroding wire is introduced into the starting material along a longitudinal bore, a compact tube closed over its circumference is released from the parting line 23 or 24. If, on the other hand, the wire is fed radially, the piece separated from the starting material forms one longitudinally carved sleeve, which is also usable.
• the cross section of the parting line 23 or 24 is eroded out.
• the electrodes are thin-walled tubes made of copper or a copper alloy, the diameter of which corresponds to the diameter of the joints. When eroding, the electrodes can be moved about their longitudinal axis and / or along their longitudinal axis.
• the material corresponding to the parting lines 23, 24 is produced as fine erosion waste.
• die sinking EDM has the advantage that if the electrodes are not completely guided through the starting material, a bottom remains at one end of the block, which stabilizes the arrangement and during the subsequent filling of the separating joints 23, 24 with a material forming the separating layer is advantageous to facilitate the filling and to prevent it falling out.
• Fig. 12 the bottom can be seen at the right end of the illustration.
• Both the wire and the sinker EDM have the advantage over other methods such as drilling etc. that little waste of nickel-titanium arises, since only the material of the separating joints 23, 24 or part of this material is produced as waste.
• FIGS. 13 to 16 show such finished composite blocks 10 prepared for pressing. They are covered with a sleeve 25 made of copper in order to prevent direct contact between the nickel-titanium of the second hollow block 5 and the pressing die during extrusion and to prevent welding between nickel -Titan and the tool steel to avoid.
• a disk 26 made of a high-strength copper alloy is also attached to the end faces of the composite blocks 10.
• the end of the block is closed with a second disk 27 made of a high-strength copper alloy.
• guide pieces 22 are provided which fill the parting lines 23, 24 or partial sections in the area of the block ends. For example, as shown in FIGS. 14 and 16, they can be molded onto the second disks 27.
• the disk 26 also has guide pieces 22, since the parting lines 23, 24 pass through the material entirely. 16 is stabilized in the right block end by the webs left during EDM.
• the powder material used to fill the parting lines 23, 24 preferably consists of hard, temperature-resistant metal oxides such as, for example, aluminum oxide powder, which has the ability to slide during the shaping process in accordance with the shape change of the nickel-titanium material without plastic deformation of the Oxide particles takes place.
• FIG. 17 shows how the prepared composite block 10 is hot-formed into an extrusion by extrusion. Both direct and indirect extrusion is also possible. Indirect extrusion, which is shown in FIG. 17, is preferred.
• the composite block 10 is inserted into the block receiver 16 and is pressed and pressed against the press die 17 by the pressing process in which the block receiver 16 and the press die 19 together with the composite block 10 to be pressed move in the direction of the press die 17 lying on a hollow die 20 a deformed composite block 12 in the form of a strand.
• Figures 19 and 20 show a numerical example of a method according to the invention according to Figures 9 to 18, in which a nickel-titanium press block with a three-zone division after hot forming by extrusion, in which the diameter and wall thickness of the individual parts are reduced , is divided into three pressed products.
• Composite blocks 10 with a diameter D ⁇ of approximately 110 mm using a block transducer with a diameter of 110 mm and a die with a diameter of approximately 26 mm a pressing ratio of approx. 18: 1.
• the ratio of the cross-sectional area of the composite block 10 to be pressed, which corresponds to the cross-sectional area of the block receiver, to the cross-sectional area of the strand block 12, which corresponds to the cross-sectional area of the die opening, is 18: 1.
• the individual zones and inter-zone spaces are also formed with a pressing ratio of 18: 1.
• the dimensions of the individual zones in the composite block 10 and in the formed composite block 12 shown in FIGS. 19 and 20 are approximately as follows: D- ⁇ 110 mm, D 2 108 mm, D 3 89 mm, D4 76 mm, D 5 63 mm, D g 51 mm, D 11 26 mm, D 22 25.5 mm, D 33 21 mm, D 44 18 mm, D 55 15 mm and D gg 12 mm.
• a possible further compression of the powder material contained in the parting lines 23, 24 as parting layer is not taken into account during the pressing process, which can lead to a slight deviation in the product dimensions. However, this effect can be compensated for by a corresponding change in the diameter of the individual zones in the composite block 10.
• the reduced core 3a is a round, full profile with a diameter D gg .
• the formed first hollow block la is a tube with an outer diameter D 44 and an inner diameter D ⁇ .
• the formed second hollow block 5a is a second tube 5a with an outer diameter D 22 and an inner diameter D 33 . If a sleeve 25 made of copper was used, it is covered with an approximately 0.25 mm thin copper layer (diameter D- j ⁇ ).

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Extrusion Of Metal (AREA)
• Catalysts (AREA)
• Inorganic Fibers (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=7847200

Family Applications (1)

Country Status (5)

Families Citing this family (10)

Family Cites Families (4)

• 1998
  • 1998-10-29 DE DE19881722T patent/DE19881722D2/de not_active Expired - Fee Related
  • 1998-10-29 US US09/530,661 patent/US6453536B1/en not_active Expired - Fee Related
  • 1998-10-29 EP EP98962224A patent/EP1027177B1/fr not_active Expired - Lifetime
  • 1998-10-29 AT AT98962224T patent/ATE217551T1/de not_active IP Right Cessation
  • 1998-10-29 WO PCT/DE1998/003262 patent/WO1999022886A1/fr active IP Right Grant
  • 1998-10-29 DE DE59804155T patent/DE59804155D1/de not_active Expired - Fee Related

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events