EP0634959B1 - Procede et dispositif de fabrication continue de barres cylindriques comportant au moins un canal interieur helicoidal, et ebauche frittee realisee selon ce procede - Google Patents

Procede et dispositif de fabrication continue de barres cylindriques comportant au moins un canal interieur helicoidal, et ebauche frittee realisee selon ce procede Download PDF

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Publication number
EP0634959B1
EP0634959B1 EP93908925A EP93908925A EP0634959B1 EP 0634959 B1 EP0634959 B1 EP 0634959B1 EP 93908925 A EP93908925 A EP 93908925A EP 93908925 A EP93908925 A EP 93908925A EP 0634959 B1 EP0634959 B1 EP 0634959B1
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EP
European Patent Office
Prior art keywords
pin
nozzle
flow
nozzle mouthpiece
section
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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EP93908925A
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German (de)
English (en)
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EP0634959A1 (fr
Inventor
Joachim Heisinger
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Individual
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Individual
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Priority claimed from DE19924211827 external-priority patent/DE4211827C2/de
Priority claimed from DE19924242336 external-priority patent/DE4242336A1/de
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES, PROFILES OR LIKE SEMI-MANUFACTURED PRODUCTS 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
    • B21C23/14—Making other products
    • B21C23/147—Making drill blanks
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/20—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces by extruding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
    • B22F2005/004—Article comprising helical form elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy

Definitions

  • the invention relates to a method for the continuous production of cylindrical rods with at least one internal helical channel according to the preamble of claim 1, further to an apparatus for performing the method, i. H. to an extrusion tool suitable for carrying out the method, and finally to a cylindrical molded body produced by the method according to the preamble of claim 44.
  • extruded cylindrical moldings with internal, at least partially helical channels of predetermined cross-section are increasingly required, for example, in the tool industry, and here in particular in the manufacture of drilling tools that have an internal cooling or Have a detergent supply so that the coolant or detergent can exit the tool in the immediate vicinity of the cutting edge.
  • the helical course of the at least one internal cooling channel is required if the tool to be manufactured, such as. B. helical flutes are provided on a drilling tool, for example, are ground.
  • a method for producing a drilling tool with at least one helical internal coolant channel is already presented, in which the helical course of the at least one internal coolant channel is generated simultaneously with the extrusion of the plastic mass.
  • the inside of the nozzle mouthpiece is equipped with a helical profile, the helical pitch of these projections being adapted to the desired helical pitch of the internal cooling channels.
  • elastic pins are provided, which are attached with their upstream ends to a nozzle mandrel and whose elasticity is chosen so large that the pins can follow the swirl flow induced by the inner contour of the nozzle mouthpiece.
  • the circular diameter on which the cross-sections or the cross-section of the at least one internal coolant channel comes to lie in the extruded blank is influenced by the flow speed and by the friction losses in the nozzle mouthpiece, which is particularly the case when changing the extrusion mass from one batch to another can have a negative impact.
  • Document EP 0 431 681 A2 finally discloses a method and a device for producing a cylindrical, metallic or ceramic blank of the type described in the introduction, in which at least one twisted center pin consists of a rigid center pin through the center of an internally smooth, circular-cylindrical nozzle mouthpiece Material stretches. This at least one twisted center pin is attached to a stationary mandrel in front of the inlet area of the nozzle mouthpiece. The pins are thus preformed helically in this process and made of a rigid material such as. B. made of hard metal or steel.
  • the invention is therefore based on the object of developing a method and a device according to the preamble of claim 1 or claim 11 or claim 28 such that extrusion blanks with a precisely defined course of internal, helical cooling channels with a maximum of reproducibility and with high
  • the quality of the structure can be produced, and there should be no restrictions with regard to the scope of the method with regard to the composition of the extrusion, the process parameters or the geometry of the blank.
  • the invention has for its object to produce a cylindrical rod with helical cooling channels according to claim 44, in which the strength of the rod can be varied or adjusted over the rod cross-section and it can be produced in a material-saving manner.
  • the inner channels are in the original molding process without plastic deformation of the mass located in the nozzle mouthpiece manufactured, preferably the mass enters the nozzle mouthpiece essentially without swirl, either flows over the entire flow cross-section essentially swirl-free at least one pin and, when passing through the nozzle mouthpiece, sets it in a continuous rotary movement corresponding to the pitch of its helix, or on a pin suspension flows past that in dependence is drivable by the flow rate.
  • the device is characterized in that the at least one pin is connected in a rotationally and axially fixed manner to a shaft which is rotatably mounted in the nozzle mandrel about an axis parallel to the nozzle axis and is twisted in such a way that the plastic mass flowing along its axis essentially over the impresses a constant angular momentum defined by the pitch of its helix over the entire length.
  • the shaft carrying the at least one pin, the connection point to the pin located radially inside the pin in the nozzle mouth has an additional drive, in which case the pin can be flexible and the drive can be controlled independently of the desired pitch.
  • the invention fundamentally frees itself from the idea of imparting a swirl movement corresponding to the helix pitch to be generated to the highly viscous mass flow during extrusion and thereby plastically deforming the mass relatively strongly. Rather, the invention is based on the idea of putting the at least one wire into such a rotational movement by the flow inflow forces accumulating over the length of the pin that when the plastic mass passes through the nozzle mouthpiece, at least one helical inner channel is formed, the pitch of which is exactly the same the slope of the pre-twisted pin matches. To this extent, the method according to the invention works by reversing a corkscrew effect, the corkscrew coil being compared to the pin and the cork being compared to the plastic extrusion.
  • the at least one inner helix is thus created according to the invention in the primary molding process.
  • the particular advantage of the method according to the invention lies in the fact that virtually no energy has to be used to impart a swirl flow to the cross-section of the extrusion compound, which at the same time means that the cooling duct former in the form of the rotating parts is only slight and subjected to reproducible forces.
  • the invention takes advantage of the fact that, for a given helix pitch, the pitch angle increases with increasing proximity of the helix surface to the central axis, so that the approach angles become smaller. This leads in comparison to the arrangement of swirl device inflow surfaces in the area of the inner jacket of the nozzle mouthpiece bwz. at radially more distant places to energetic advantages.
  • the flow of the extrusion is stressed as little as possible in the manufacture of the internal cooling channels, which results in the particular advantage that the blank has a very homogeneous structure at the outlet of the nozzle mouthpiece.
  • the accuracy of the introduced, at least one helical cooling channel namely with respect to the slope, radial position, angular position and cross section, could be kept at a very high level straight away, regardless of whether and if so in what way a certain roughness of the inner surface of the nozzle mouthpiece is selected or not.
  • the first time it is thus possible for the first time to produce a cylindrical extrusion body with internal, helical cooling channels, which has a cross-sectional shape that deviates from the circular shape, for example a rectangular, polygonal or elliptical shape, the position of the center of rotation of the cooling channel former with respect to the nozzle cross section no longer being important.
  • the method according to the invention there are no longer any dependencies between the cross section or the diameter of the blank and / or the degree of plasticization and / or the extrusion parameters, such as, for example, the extrusion speed.
  • the helix in the blank corresponds exactly to the preformed helix of the twisted wires.
  • a friction-reducing fluid preferably a friction-reducing liquid or a liquid-like substance, is preferably supplied to the rigid or flexible pins under pressure.
  • the greatly reduced friction in this way leads to the smallest reaction forces between the molding compound and the at least one pin.
  • These smallest reaction forces in turn make it possible to design the pin carrier organs with the smallest possible cross section.
  • These pin carrier organs are formed by components such as webs, shafts and shaft bearings. Because these pin carrier members can thus be designed with a smaller cross-section according to the invention, they also lead to smaller reaction forces which would otherwise disrupt the molding compound flow.
  • the sum of the forces acting radially on the molding compound according to the invention is so small due to the measures according to the invention that they are no longer reproducibly able to impose a swirl movement neither locally nor across the cross section. It could be shown that the internal and external cohesive forces of the molding compound counteract this tendency effectively.
  • the measures according to the invention result in the additional advantage that there is no longer any noticeable wear on the at least one pin forming the cooling channel.
  • the development according to the invention of the subject matter of the main patent is thus comparable to a quasi hydrostatic mounting of the cooling channel former in the molding compound.
  • the fluid is preferably supplied under pressure (claim 2) and the fluid consists of the plasticizer of the molding compound or it has at least one component of this plasticizer.
  • the pressure is controlled via the mass flow cross section by the design of the inner surface area of the nozzle mouthpiece.
  • This lateral surface can, for example, also be designed in such a way that the flow cross-section gradually decreases towards the outflow side in order to counteract the pressure reduction to the environment caused by the fluid mechanics (outlet cross-section of the nozzle mouthpiece).
  • the mass entering the nozzle mouth hits the twisted rods, it must absorb a reaction moment.
  • the inner jacket and / or by suitable measures in the area of the cooling channel former in the area of the nozzle inlet the traction forces of the cooling channel former can be absorbed in such a way that the mass flows swirl-free through the nozzle mouth and exits from it.
  • a suitable measure is, for example, the rotational movement of the rods forming the cooling channels, i.e. the mass flow. to support the cooling channel former by means of an additional drive, the most advantageous embodiment of such an additional drive being designed so that the additional drive torque is just large enough to compensate for the reaction counter-torque.
  • the auxiliary drive can advantageously be combined with a cooling duct former, in which at least one flexible core pin sits at the end of a shaft protruding into the nozzle mouth, so that the shaft depends on the desired pitch of the channel spiral is set in a controlled rotary motion.
  • a further, particularly simple way of providing this additional drive torque is the subject of claim 5 or claim 19.
  • the friction-related braking torque can be largely compensated for by a beveling of the upstream end faces of the rods forming the cooling channels. This is the subject of patent claim 20.
  • the at least one pin, which forms the associated internal cooling channel is extended in the upstream direction beyond the hub body which connects to the shaft, which is the subject of claim 18, the introduction of the bending moment from the bars into the hub body is additionally very favorable, as a result of which the connection point between the hub body and the pin can be kept shorter.
  • a linearization ie an axial alignment and stabilization of the flow with the aid of a flow guide arrangement is carried out.
  • An advantageous possibility of designing such a flow guide surface arrangement is the subject of claim 34.
  • regular axial grooving can be used, this design of the inner surface of the nozzle mouthpiece being used advantageously to compensate for the cross-sectional change resulting at the end of the hub of the rotary shaft .
  • the axial grooves then only run to the end of the connecting hub between the pins and the rotary shaft.
  • guide devices are also advantageous, which can also have the smallest dimensions, the axially incident cross section similar to a turbomachine with a small axial gap next to the turbine-like channel former, ie the at least one pin is placed.
  • These guide devices are preferably fin-like and, for example, are made in one piece with the mandrel. However, they can also be attached to this mandrel as required.
  • the flow guide surface arrangements which act as swirl prevention surfaces, preferably do not extend over the entire flow cross-section because the swirl movement mentioned above in this case also has only a small radial extension. However, it is of course also possible to have these swirl prevention devices act over the entire flow cross section.
  • a particularly effective device for compensating for the swirl acting on the molding compound from the cooling channel former is the subject of claim 39.
  • the swirl pulse triggered by the cooling channel former on the molding compound is compensated for by a counter-swirl introduced in the opposite direction of swirl.
  • This guide device which compensates for the swirl can, for example, have the exact shape of the hub body or be designed such that the frictional forces of the center pins which trigger the swirl pulse are also compensated.
  • This part in the flow i. H. this flow part can then also be driven in a controlled manner or freely stored and rotates counter to the direction of rotation of the channel former.
  • the invention can be used for any cross-sectional configuration of the blank, but also for any cross-sectional and positional configuration of the internal cooling channels. Particularly simple, because symmetrical relationships arise when the rods are arranged point-symmetrically to the axis of the rotary shaft.
  • the inflow conditions of the highly viscous ie. H. Optimize the plastic mass in the nozzle mouthpiece and the inflow conditions of the helical core rods.
  • FIGS. 1 to 4 in order to be able to clarify the principle of the cooling channel shaping on which the method is based in the primary molding process.
  • the reference numeral 10 denotes an extrusion tool, through which a highly viscous, plasticized metallic or ceramic material 12 flows from right to left according to FIG. 14.
  • a nozzle mouthpiece is designated, which is either formed in one piece with a nozzle carrier part 16, or replaceable on the latter is held.
  • the nozzle mouthpiece 14 and / or the nozzle carrier part are preferably fixed interchangeably in the extrusion tool 10.
  • the extrusion die has two sections, namely a die mouth DM and a die inlet area DE, in which the plastic mass 12 is passed in a funnel shape into the die mouth.
  • a nozzle mandrel 18 is provided, which will be described later with reference to FIG. 15 and has a conical surface 20 on its downstream side, so that an annular space 22 is formed between the nozzle mandrel 18 and the nozzle carrier part 16 the nozzle mouth DM opens.
  • the extrusion die 10 or the extrusion die 14, 16 is used for the continuous extrusion of cylindrical rod-shaped shaped bodies 24 with at least one, inner and helical, left-hand or longitudinally extending channel 26.
  • Such blanks are required, for example, in the manufacture of drilling tools, in which there are If the extrusion process is followed by a drying or pre-sintering process, before the correspondingly cut blank bars are subjected to the actual sintering process.
  • the finished sintered blanks are then regularly machined by grinding at least one helical flute into the outer surface of the blanks.
  • the extrusion tool is constructed as follows: A shaft 30 is rotatably mounted in the center of the nozzle mandrel 18.
  • the shaft 30 extends beyond the front end 32 of the nozzle mandrel 18 into the nozzle mouth DM and carries at the downstream end a plate-shaped hub body 34 (see also FIG. 16), which has a radially outer side surface 36, 38 with one each helically pre-twisted pin or core pin 40, 42 is connected.
  • a plate-shaped hub body 34 see also FIG. 16
  • two such pins 40, 42 are provided, which are point-symmetrical to the axis 44 of the shaft 30 and thus of the hub body 34.
  • the invention is not limited to such a number and arrangement of the pins.
  • the helically pre-twisted pins 40, 42 have exactly the pitch that the extruded blank 24 has.
  • the dimension of the slope WS is determined taking into account the expected sintering shrinkage, as is the pitch circle diameter TKD.
  • the helical axis 28 coincides with the axis 44 of the shaft 30, so that the cross section of the pin 40, 42 always moves on the pitch circle 46 when the shaft 30 rotates.
  • a material for the pins 40, 42 a material with a large modulus of elasticity, such as. B. steel, hard metal or a ceramic material is used.
  • the pins 40, 42 have essentially the length of half a helical pitch WS / 2 and the arrangement is such that the pins 40, 42 extend at least up to the end face 48 of the nozzle mouthpiece 14, so that those of the rods 40, 42 internal channels 26 formed during the extrusion process maintain their shape and position outside the nozzle.
  • the hub body 34 is seated in the nozzle mouth DM so that it has a predetermined axial distance AX from the front end 32 of the nozzle mandrel 18.
  • This axial distance AX is preferably adjustable in order to be able to influence the flow conditions of the nozzle mouth DM and thus of the at least one pin 40, 42.
  • the pins 40, 42 are defined and the flow flows axially in the area of the nozzle mouth DM.
  • the flow thus hits below that determined by the slope WS and the pitch circle diameter TKD Angle PHI on the pins 40, 42. Since these are fixed via the hub body 34 and the shaft 30 about the axis 28 of the helix, namely about the axis 44 in the nozzle mouth DM, the wires 40, 42 become when the plastic mass 12 passes through the nozzle mouth in a continuous rotary movement corresponding to the pitch of the helix of the preformed pins with the angular velocity OMEGA.
  • the force components acting in the circumferential direction caused by the inclination of the helical pins in relation to the flow direction add up over the length of the pins 40, 42.
  • the arrangement of shaft 30, hub body 34 and at least one helically twisted pin 40, 42 will therefore perform a uniform rotational movement predetermined by the flow speed, the bending stress of the pins 40, 42 being kept relatively small.
  • the pins 40, 42 function according to the principle of an axially flow-through turbine with the output shaft 30, although the medium is not formed by an ideal, incompressible liquid, but by a highly viscous and to a certain extent elastic mass.
  • the nozzle mouth is basically divided into two areas, namely a nozzle mouth entry area DME and a pure nozzle mouth flow area DMS.
  • DMS nozzle mouth entry area
  • DMS pure nozzle mouth flow area
  • the nozzle mouth has a predetermined, essentially constant cross section, through which the flow rate can be controlled. If the cross-section does not change in the DMS area, a constant flow velocity can also be assumed in this area as a first approximation.
  • the diameter in the DME area is just increased by a dimension M in comparison to the section DMS, so that the ring area defined by the two diameters of the areas DMS and DME becomes approximately as large as the cross-sectional areas of the shaft 30 that can be seen in FIG. 3 and the radial sectional area of the hub body 34, including the connection points 52.
  • Excessive pressure fluctuations in the mass 12 can be eliminated by flowing through the nozzle mouth DM by suitable design of the transitions between the inner surface areas in the DME and DMS area.
  • the design of the nozzle mouth DM according to the invention prevents an excessive pressure drop precisely in the transition area between the sections DME and DMS, so that it is ensured that there is sufficient pressure in the section DMS to close the cross section.
  • shaft 30 is assigned not only a radial bearing 58, but also an axial bearing 60, which will be explained in more detail below with reference to FIG. 15. Otherwise, the embodiment according to FIG. 15 essentially corresponds to that according to FIG. 14, so that the same reference numerals are also used for the comparable components.
  • the axial bearing 60 is formed by a roller bearing, preferably a needle bearing, the needles 62 of which roll on running surfaces 64, 66 in the form of support disks.
  • the disks are threaded onto the shaft 30.
  • One of the disks, namely the disk 64, is supported flatly on an end face 68 of a mandrel insert 70 which is screwed into a central body 72 of an annular nozzle insert 74.
  • narrow ribs 78 are preferably provided at a uniform circumferential distance from one another, preferably connected in one piece to the outer ring 76. With 80 seals or seal packs between the mandrel insert 70 and the central body 72 are designated.
  • the second running disk 66 on the other side of the needles 62 is supported by a thrust washer 82, which in turn is supported on the shaft 30 by a bearing adjusting nut 84.
  • a plug labeled 86 can be removed from the mandrel central body 72 to lubricate the bearing.
  • Reference number 88 denotes a gap seal which has proven to be completely sufficient for the effective sealing of the bearings 58 and 60 against the mass 12.
  • an O-ring can be provided behind the gap seal.
  • the above-described structure of the mounting of the rotatable cooling channel former opens up the possibility of converting the extrusion head within a very short time, for example by replacing the entire mandrel extension 70 with the pre-assembled bearing 60.
  • FIG. 2 does not differ in terms of the design of the channel former in the form of the helically pre-twisted wires or rods 40, 42 from the embodiment according to FIG. 14.
  • the transition of the pins or wires 40, 42 to the shaft is somewhat solved differently:
  • the shaft 30 has a thickening 134 at its downstream end, and the pins 40, 42 are connected to the shaft 30 via a soldered or welded connection or a corresponding connection. It has been shown that even with this arrangement it is possible to ensure a very homogeneous structure of the extruded blank at the outlet of the nozzle mouth DM when using the method according to the invention or the extrusion device according to the invention.
  • the web designated by 234 is kept very narrow in cross-section and is preferably also formed on both sides of the axis by a helical surface, so that the continuous rotational movement of the cooling channel former 40, 42 results in the lowest possible flow resistances.
  • the axial length of the connecting section between the wires 40, 42 and the hub body 34 or 134 or 234 can be made relatively short, since the pins or wires 40, 42 when rotating through the mass 12 are mainly pulling and slightly similar a coil spring - be subjected to torsion.
  • the highly viscous mass 12 enters from the annular space 22 over a short inlet distance over the axial distance AX into the inlet region of the nozzle mouthpiece DME in the axial direction and displaces it from the rods or wires 40, the hub body 34 or 134 or 234 as well as the Shaft 30 existing cooling channel former due to the angle of attack PHI in a continuous rotary movement corresponding to the pitch WS of the helix.
  • the position of the helix in the nozzle mouth DM and the slope of the helix WS correspond exactly to the position and the slope of the helix of the cooling channel formed in the blank.
  • the flow through the nozzle mouth DM does not result in any plastic deformation of the mass passing through, but rather the formation of the internal, helical cooling channels in a primary molding process.
  • the rods 40, 42 are mainly stressed in train. The same applies to the stress on the shaft 30, which can thus be formed with a relatively small diameter.
  • the jacket 90 of the cylindrical inner recess of the nozzle mouth DM is smooth, and also in the area of the nozzle mouthpiece inlet DME.
  • the cross section of the nozzle mouth DM has a circular shape
  • the - although small - frictional moments, caused by the surface area of the coiled pins 40, 42 and the bearing frictional forces, lead to the blank 24th emerges with a slight rotation about axis 44.
  • the dimensional accuracy of the inner channels formed with the cooling channel former is not affected by this, but in some applications this self-rotation can be undesirable.
  • Various measures can therefore be taken to switch off this self-rotation:
  • One measure - not shown in the figures - is to assign an additional drive to the shaft 30, which applies an additional torque to the shaft 30 which is just large enough to cover the reaction moments.
  • a further measure, shown in FIG. 1, is to provide the upstream end faces 92 of the pins 40, 42 with such a bevel that an additional torque is applied to the cooling duct former by the flow.
  • FIG. 2 Another possibility is indicated in FIG. 2 with dash-dotted lines. This is to provide the wires 40, 42 upstream of the hub body 134 with an extension section 140, 142 and to provide this extension section with a spiral pitch that deviates from the desired spiral pitch in the blank in such a way that the mass flowing onto the extensions 140, 142 12 applies the additional torque covering the reaction torque to the cooling duct former.
  • flow guide surfaces in the area of the nozzle mouth DM, which axially align the flow of the mass 12 in the nozzle mouth, ie help to linearize it.
  • Flow guiding surfaces of this type can be provided, for example, in the inlet area DME, but also in the remaining area of the nozzle mouth DM.
  • Such a flow guide surface arrangement in the form of an internal toothing 94 is indicated in FIG. 4. If the internal toothing 94 is limited to the nozzle mouth entry area DME, it is advantageous to choose the toothing in such a way that the toothing cross sections 96 which extend beyond the diameter 98 add up over the circumference, just the sum of the cross sections of the shaft and the hub 134 or 234 matters.
  • the rods pre-twisted to the exact spiral pitch desired in the blank no longer have to be over-twisted by complex preliminary tests in order to achieve the desired pitch and position of the inner channel in the blank.
  • the mass 12 is not subjected to any deformation work when it flows through the nozzle mouth DM and the moving components of the inner channel former are mechanically relatively low because the cross-sectional areas claimed by the cooling channel former are relatively small compared to the total passage area of the nozzle mouth DM.
  • the nozzle mouth DM in the device described above is approximately as long as half the helix pitch WS, it should be emphasized that the nozzle mouth DM can also be shortened compared to the helix pitch, but then the wires are shortened accordingly, so that they end up in the area of the nozzle outlet. It is also possible, instead of the point-symmetrical arrangement of the rods 40, 42 described above, to choose a different arrangement in comparison to the axis 44 or 28, it even being possible to use different cross-sections of the rods or wires on different sides of the axis work.
  • the cooling duct former according to FIG. 5 differs only slightly from that according to FIG. 1.
  • the helically pre-twisted pins 340, 342 are fastened to a shaft 330 via webs 392.
  • the special feature is that the shaft 330 mounted in the nozzle mandrel 318 is equipped with an inner bore 331 and that the webs 392 are also provided with radial bores 393, which emerge at 395 on the surface of the pins 340, 342.
  • the inner bore 331 and the radial bores 393 form a flow path for supplying a substance which reduces the frictional force between the molding compound and the pins 340, 342, for example a fluid, preferably a friction-reducing liquid or liquid-like substance.
  • the feed is indicated by arrow 397 and is preferably carried out under pressure.
  • a friction-reducing liquid or liquid-like Substance for example, the plasticizer of the molding compound can be used.
  • This substance exits at 395 (a plurality of such radial channels can also be provided around the circumference and also in the longitudinal direction of the pins 340, 342) and flows along the surface of the pins 340, 342, the entire surface of the pins being wetted.
  • the cross-section of the webs 392 and the shaft 330 can be reduced, which also reduces the reaction forces between the pin carriers and the molding compound.
  • FIG. 6 shows a variant of the extrusion tool, in which, in contrast to the illustration according to FIG. 5, no rigid, pre-used pins, but flexible pins 440, 442 are used, which are fixed to a fork-like branch 492 of a drive shaft 430.
  • the shaft 430 and the fork 492 are hollow, so that - as indicated by the arrow 497 - a friction-reducing fluid is introduced through an inner bore 431 in the shaft 430 into the fork-like branch 492 and there to the flexible pins 440 , 442 can be passed on.
  • the pins are flexible and they are actively driven via shaft 430.
  • a friction wheel 441 is provided at the exit of the nozzle, which is equipped with a displacement measuring device, not shown in detail.
  • Both embodiments have in common that the fluid supplied to the pins or threads results in a quasi hydrostatic bearing of the pins or threads in the molding compound, which drastically reduces the influence of disturbance variables.
  • FIGS. 7 and 8 show variants of the suspension for the pins 440, 442. 7, orifices 495, which are distributed over the circumference and in the longitudinal direction of the pins 440, 442, in order to ensure a uniform outlet of the fluid fed in at 497 to reduce the frictional forces.
  • the fork-like branch 492 in the embodiment in FIG. 6 is replaced in the variant according to FIG. 7 by a diametral web 492 'which has an inner bore 493'.
  • the variant according to FIG. 8 can be used particularly advantageously if a thread-like band 441 ′′ is attached to the shaft 430 ′′.
  • the shaft 430 ′′ is again hollow and carries at its end facing the nozzle mouth a fork piece 492 ′′ into which the thread or a cord 441 ′′ is suspended.
  • the point at which the friction-reducing substance emerges from the fork piece 492 ′′ is designated by A.
  • Fig. 9 shows a variant in which all components of the cooling channel former downstream of the nozzle mandrel 518 with the Friction-reducing substance are wetted.
  • the nozzle mandrel 518 forms a shaft bearing 519 at its front end.
  • a bore 521 In front of this shaft bearing 519 there is a bore 521 with a larger diameter, which surrounds the shaft 530, which in this embodiment can be designed as a solid shaft.
  • the shaft 530 can be driven or can be rotated freely in the nozzle mandrel 18.
  • Pins 540, 542 can be rigid or flexible.
  • the space between the shaft 530 and the inner bore 521 is filled with the friction-reducing fluid, preferably the liquid, which in turn is preferably supplied under pressure, which is indicated by the arrow 597.
  • the friction-reducing fluid preferably the liquid
  • this fluid is supplied through the shaft bearing 519, which can thus advantageously be designed as a hydrostatic bearing. Accordingly, in this configuration, the entire surface of the cooling channel former downstream of the nozzle mandrel 518 is wetted with the friction-reducing substance, as a result of which the cross sections of the shaft 530 and the fork-shaped holding part 592 can be kept to a minimum.
  • Points 595 indicate that the friction-reducing liquid along the pins 540, 542 forms a hydrostatic carrier film on the entire surfaces of the cooling duct former located downstream of the nozzle mandrel. The liquid only exits through the channels that are then formed.
  • the variant shown in FIG. 9 has the advantage that the hub body 592 can be equipped with the smallest possible cross-section that can be designed to be very aerodynamic.
  • the aim of the embodiments according to FIGS. 10 and 10 is to minimize or compensate for the angular momentum exerted on the molding compound by the flow around the cooling channel former.
  • flow guide surface arrangements are in these embodiments provided that can also compensate for the angular momentum that triggers only a swirl movement of the molding compound with a small radial extension towards the nozzle jacket.
  • guide vanes 641, 643 are attached to the nozzle mandrel 618 parallel to the axis of the extrusion die, which extend close to the upstream ends of the pins 640, 642 and have flattened portions 647, 645 at their front areas.
  • the guide surface bodies are accordingly fin-like and they end with a very small gap SP upstream of the pins 640, 642, which act like a turbine.
  • the guide bodies 643, 641 act like a guide device of a turbomachine, in which swirl compensation takes place at the crucial point.
  • FIGS. 12 and 13 A first variant of this swirl prevention device is shown in FIGS. 12 and 13.
  • the interface between flow guide pin 741, 743 and turbine-like pins 740, 742 differs from the variants described above.
  • the gap SP is set here in the direction of flow. It can best be seen from the illustration according to FIG. 13 that the flow guide pin 741, 743 attached to the nozzle mandrel 718 forms a flattened portion 745, 747 at the downstream end.
  • flow guide surface arrangements are provided, which are designated 841 and 843.
  • these flow guide surfaces are formed by plate-like bodies which cover the entire flow cross section.
  • a flow guide surface 841, 843 is again provided for each pin which is to form an internal channel, the downstream end of the flow guide surfaces 841, 843 extends as close as possible to the upstream end of the pins 840, 842.
  • the shaft 930 which carries the pins 940, 942 via a web 292
  • the outer shaft 935 like the other flow guide surface arrangements of the embodiments according to FIGS. 10 to 15, projects into the nozzle mouthpiece DM and carries, at a small axial distance AX from the upstream end of the pins 940, 942, a flow part 937 which has essentially the same cross-sectional configuration as that Web 992 has, however, as indicated by arrow G, is driven in the opposite direction as the cooling channel former 940, 942 (part K).
  • the cross section of the flow guide part 937 which compensates for the swirl can also be optimized in such a way that the frictional forces of the center pins which trigger the swirl pulse are also compensated for at the same time.
  • the flow part 937 is preferably driven in a controlled manner. However, it can also be stored freely, the adjustment of the partial flow surfaces being such that an opposite rotational movement (direction of rotation G) to the rotational movement of the cooling channel former (direction of rotation K) is induced.
  • the invention thus provides a process for the continuous production of cylindrical rods with at least one, preferably a plurality of internal, helically extending channels of predetermined cross-section that are uniformly distributed over the circumference.
  • This method is used in particular in the production of a sintered metal or ceramic blank, the plastic mass forming the blank being pressed out of a nozzle mouthpiece by the mass flowing along the axis of the helically twisted pin held on a nozzle mandrel.
  • a rotatably mounted cooling duct former is provided in the nozzle mouth, which has at least one helically pre-twisted pin, which is attached to a shaft at least at the fastening point and thus rigidly and rigidly.
  • the helical pre-twisting corresponds exactly to the helix shape of the inner channels to be formed in the blank.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Powder Metallurgy (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)
  • Press-Shaping Or Shaping Using Conveyers (AREA)

Claims (44)

  1. Procédé de fabrication continue de barres cylindriques ayant au moins un canal intérieur s'étendant au moins par tronçon en forme de façon hélicoïdale et ayant une section transversale prédéterminée, en particulier pour la fabrication d'une ébauche en métal fritté ou d'une ébauche en céramique pour une partie d'outil, dans lequel la masse plastique constituant l'ébauche est obtenue par pressage à partir d'une pièce d'embouchure de buse, en fluant le long de l'axe d'au moins une tige, présentant un vrillage en hélice et maintenue sur un mandrin de buse, caractérisé en ce que les canaux intérieurs sont fabriqués lors du processus de formage initial sans déformation plastique et sans écoulement rotatif, c'est-à-dire sans déformabilité plastique de la masse se trouvant dans la pièce d'embouchure de buse, par le fait que la masse entre sans aucune rotation dans la pièce d'embouchure de buse (DM), s'écoule sans rotation sur la totalité de la section transversale suivie par l'écoulement, soit sur la au mains une tige et met celle-ci en un mouvement de rotation continu lors du passage à travers la pièce d'embouchure de buse, mouvement de rotation correspondant au pas de son hélice, ou bien fait passer son écoulement sur un élément d'accrochage de tige qui est entraîne, en fonction de la vitesse d'écoulement, de manière que la au moins une tige tourne de manière correspondant à l'hélice à générer du canal, par rapport à la masse se trouvant dans la pièce d'embouchure de buse, en donnant une forme correspondant à l'hélice à fabriquer.
  2. Procédé selon la revendication 1, caractérisé en ce qu'à la au moins une tige (40, 42; 340, 342; 440, 442; 540, 542; 940, 942) est amené un fluide diminuant la valeur de frottement vis-à-vis de la masse, en particulier un liquide ou substance analogue à un liquide, qui diminue la valeur du frottement.
  3. Procédé selon la revendication 2, caractérisé en ce que le fluide est amené sous pression, de préférence le fluide étant constitué de l'agent plastifiant de la masse ou bien ayant au moins un composant de cet agent plastifiant.
  4. Procédé selon la revendication 2 ou 3, caractérisé en ce que le fluide est amené à la au moins une tige (540, 542) par l'élément d'accrochage de tige, si bien qu'un film support hydrostatique est constitué sur l'ensemble de la surface qui se trouve en aval du mandrin de buse (518), d'un formateur de canal de refroidissement (530, 592, 540, 542).
  5. Procédé selon l'une des revendications 1 à 4, caractérisé en ce que la section transversale d'écoulement à l'intérieur de la pièce d'embouchure de buse (DM) est maintenue sensiblement constante, et en ce que les conditions d'écoulement ou de pressions sur la longueur de la pièce d'embouchure de buse (DM) sont maintenues constantes ou contrôlées à une valeur constante dans l'aire de la section transversale de la pièce d'embouchure de buse (DM), de préférence la masse (12), s'écoulant dans la pièce d'embouchure de buse (DM), étant utilisée pour assister l'entraînement en rotation, contrôlé par l'écoulement de la masse à l'intérieur de la pièce d'embouchure de buse (DM), de la au moins une tige (40, 42).
  6. Procédé selon l'une des revendications 1 à 5, caractérise en ce que la au moins une tige (40, 42) a un axe de rotation (44) coïncidant avec l'axe central (28) de la section transversale d'écoulement.
  7. Procédé selon l'une des revendications 1 à 6, caractérisé en ce que plusieurs tiges (40, 42) reçoivent un écoulement de masse plastique, et en ce que les tiges ont un axe de rotation (44) commun et sont réparties de préférence régulièrement de façon réglable à volonté sur le cercle primitif (46) afférent.
  8. Procédé selon l'une des revendications 1 à 7, caractérisé en ce que les couples de réaction du formateur de canal comportant la au moins une tige (40, 42) sont pris en compte par un entraînement additionnel, de manière à ce que l'ébauche sorte de l'embouchure de buse pratiquement sans aucune rotation.
  9. Procédé, en particulier selon l'une des revendications 1 à 8, caractérisé en ce que l'écoulement de la masse à travers la pièce d'embouchure de buse (DM) est linéarisé au moins radialement à l'extérieur de la au moins une tige (40, 42), au moyen de surfaces directrices d'écoulement (94).
  10. Procédé, en particulier selon l'une des revendications 1 à 8, caractérisé en ce que l'impulsion de rotation déclenchée par la au moins une tige et la fixation prévue pour celle-ci, exercée sur la masse d'extrusion est compensée par un dispositif directeur compensant la rotation et induisant une contre-rotation orientée à l'encontre de l'impulsion de rotation.
  11. Dispositif pour la mise en oeuvre du procédé selon l'une des revendications 1 à 10, avec un outil d'extrusion, de la pièce d'embouchure de buse duquel une barre cylindrique, ayant un canal intérieur s'étendant en hélice, au moins par tronçons et ayant une section transversale prédéterminée peut être extrudée, à l'intérieur de la pièce d'embouchure de buse (DM) étant prévue au moins une tige (40, 42) maintenue sur un mandrin de buse et pré-vrillée en hélice avec une orientation co-axiale par rapport à l'axe (44) de la pièce d'embouchure de buse (DM), caractérisé en ce que la au moins une tige (40, 42) est reliée, en étant assujettie en rotation et axialement, à un arbre (30) monté tournant autour d'un axe (44) parallèle à l'axe de buse (44), dans le mandrin de buse (70, 72), et vrillée de manière que la masse plastique (12) s'écoulant de long de son axe (44) lui inculque, sensiblement sur la totalité de sa longueur, une impulsion de rotation constante, définie par le pas de son hélice.
  12. Dispositif selon la revendication 11, caractérisé en ce qu'est prévu un moyen, à l'aide duquel à la au moins une tige peut être amené un fluide diminuant la force de frottement par rapport à la masse en particulier un liquide ou une substance analogue à un liquide, diminuant la force de frottement.
  13. Dispositif selon la revendication 11 ou 12, caractérisé en ce que la section transversale d'écoulement à l'intérieur de la pièce d'embouchure de buse (DM) est sensiblement constante, et en ce que les conditions d'écoulement, ou de pression, sur la longueur de la pièce d'embouchure de buse (DM) sont maintenues constantes, ou susceptibles d'être commandées à dessein, par une configuration correspondante de la section transversale de la pièce d'embouchure de buse (DM).
  14. Dispositif selon l'une des revendications 11 à 13, caractérisé en ce que la au moins une tige (40, 42) a sur la totalité de la longueur de la pièce d'embouchure de buse (DM) le même pas d'enroulement d'hélice.
  15. Dispositif selon l'une des revendications 11 à 14, caractérisé en ce que la fixation de la au moins une tige (40, 42) sur l'arbre (30) s'effectue par l'intermédiaire d'un corps formant moyeu (34; 234), plat lorsqu'on l'observe en coupe transversale faite perpendiculairement à la direction d'écoulement ou à l'axe de buse (44).
  16. Dispositif selon l'une des revendications 11 à 15, caractérisé en ce que la liaison entre la tige et l'arbre, ou le corps formant moyeu (34; 134; 234), est située dans la zone d'entrée (DME) de la pièce d'embouchure de buse (DM).
  17. Dispositif selon la revendication 16, caractérisé en ce que la section transversale de la pièce d'embouchure de buse (DM) dans la zone du corps formant moyeu (34; 134; 234) est augmentée, de la valeur de l'aire de la section transversale du corps formant moyeu (34; 134; 234), de manière que la vitesse d'écoulement de la masse plastique soit pratiquement constante au passage de la zone d'entrée (DME) dans la section restante d'écoulement de la pièce d'embouchure de buse (DM).
  18. Dispositif selon l'une des revendications 15 à 17, caractérisé en ce que la au moins une tige (40, 42) est prolongée (140, 142) au-dessus du corps formant moyeu (134), dans la direction de l'amont de l'écoulement.
  19. Dispositif selon la revendication 18, caractérisé en ce que la pièce de prolongement (140, 142) de la au moins une tige (40, 42) est utilisée pour assister l'entraînement en rotation contrôlée par l'écoulement de masse à l'intérieur de la pièce d'embouchure de buse (DM) de la au moins une tige (40, 42).
  20. Dispositif selon l'une des revendications 15 à 19, caractérisé en ce que la face frontale (82), placée en amont de la au moins une tige (40, 42; 140, 142), est orientée dans la direction de l'écoulement de manière à assister, ou réguler, l'impulsion de rotation.
  21. Dispositif selon l'une des revendications 15 à 20, caractérisé en ce que le corps formant moyeu (234; 34) est réalisé sous forme de surface hélicoïdale ayant un pas d'enroulement d'hélice adapté au pas (WS) de la au moins une tige (40, 42).
  22. Dispositif selon l'une des revendications 15 à 21, caractérisé en ce que l'arête d'entrée et/ou de sortie (54, 56) du corps formant moyeu (34) est profilée de préférence en accord avec le contour intérieur de la pièce d'embouchure de buse (DM) et/ou les transitions de fixation par rapport à la tige (40, 42) sont profilées de manière que, lors d'un écoulement-contournement sur le corps formant moyeu (34), des fluctuations de pression aussi faibles que possibles se produisent dans la masse plastique, à l'intérieur de la pièce d'embouchure de buse (DM).
  23. Dispositif selon l'une des revendications 11 à 22, caractérisé en ce que l'arbre (30) portant la au moins une tige (40, 42) a dans le mandrin de buse (70, 72) un palier radial et un palier axial (58, 60).
  24. Dispositif selon la revendication 23, caractérisé en ce que le palier axial et/ou le palier radial (58) est un palier à roulement (60).
  25. Dispositif selon l'une des revendications 11 à 24, caractérisé en ce que la longueur axiale de la pièce d'embouchure de buse (DM) et des tiges (40, 42) est une fraction du pas (WS/2) de l'hélice en fil métallique, de préférence est au moins de la valeur de la moitié d'un pas.
  26. Dispositif selon l'une des revendications 11 à 25, caractérisé en ce que la au moins une tige (40, 42) a un axe de rotation (44) coïncidant avec l'axe central (44) de la section transversale offerte à l'écoulement.
  27. Dispositif selon l'une des revendications 11 à 26, caractérisé en ce que plusieurs tiges (40, 42) sont contournées par un écoulement de la masse plastique et en ce que les tiges ont un axe de rotation (44) commun et sont réparties régulièrement sur le cercle partiel (46) afférent.
  28. Dispositif de fabrication continue de barres cylindriques avec au moins un canal intérieur s'étendant en hélice au moins par tronçons, ayant une section transversale prédéterminée, en particulier pour la fabrication d'une ébauche en métal fritté ou d'une ébauche en céramique pour une partie d'outil, avec au moins une tige pénétrant dans l'écoulement de la masse et qui forme, lors du passage de l'écoulement de la masse dans l'embouchure de buse, le au moins un canal de refroidissement, pour la mise en oeuvre du procédé selon l'une des revendications 1 à 10 et, en particulier, selon l'une des revendications 11 à 27, caractérisé en ce que l'arbre (30) portant la au moins une tige (40, 42), dont le point de liaison à la tige, situé radialement à l'intérieur de la tige, se trouve dans l'embouchure de buse, a un entraînement additionnel, à l'aide duquel la au moins une tige (40, 42) peut être conformée en hélice, à une forme correspondant à la forme du canal intérieur à façonner.
  29. Dispositif selon la revendication 28, caractérisé en ce qu'est prévu un moyen, à l'aide duquel, à la au moins une tige (440, 442; 440', 442'; 441''), peut être amené un fluide diminuant la force de frottement par rapport à la masse, en particulier un liquide ou une substance analogue à un liquide, diminuant la force de frottement.
  30. Dispositif selon la revendication 28 ou 30, caractérisé en ce que la au moins une tige (440, 442; 440', 442'; 441'') est flexible et l'entraînement est susceptible d'être commandé en fonction du pas d'enroulement souhaité.
  31. Dispositif selon l'une des revendications 11 à 30, caractérisé en ce que la substance diminuant la force de frottement est guidée à travers l'arbre (330; 440) monté tournant et à travers le point de liaison (392; 492; 492'; 492''; 992) à la au moins une tige, sur la surface de la au moins une tige formant le canal de refroidissement.
  32. Dispositif selon la revendication 31, caractérisé en ce que la au moins une tige a des canaux ou des ouvertures de passages radiaux (radiales), pour permettre le passage du fluide diminuant la force de frottement.
  33. Dispositif selon l'une des revendications 28 à 32, caractérisé en ce que le fluide peut être amené par le palier de tourillonnement (519) de l'arbre tournant (530).
  34. Dispositif selon l'une des revendications 11 à 33, caractérisé en ce que dans la zone de la pièce d'embouchure de buse (DM) est prévue, au mois radialement à l'extérieur de la au moins une tige (40, 42), un dispositif à surface directrice d'écoulement (94), destiné à linéariser et/ou à orienter axialement l'écoulement de la masse, de préférence le dispositif à surface directrice d'écoulement étant réalisé d'une seul pièce avec la paroi intérieure de la pièce d'embouchure de buse (DM).
  35. Dispositif selon la revendication 34, caractérisé en ce que la longueur du dispositif à surface directrice d'écoulement (94) est limitée à la zone de la liaison de la au moins une tige (40, 42) à l'arbre (30).
  36. Dispositif selon l'une des revendications 32 à 35, caractérisé en ce que le dispositif à surface directrice d'écoulement (94) est constitué par une surface de denture.
  37. Dispositif selon la revendication 34, caractérisé en ce que le dispositif à surface directrice d'écoulement (641, 643, 645, 647; 741, 743, 745, 747) présente à proximité du cercle partiel de la au moins une tige concernée, associée, est disposé à proximité et présente une faible étendue radiale.
  38. Dispositif selon la revendication 37, caractérisé en ce que le dispositif à surface directrice d'écoulement est réalisé à la façon d'un élément de plan et est relié au mandrin de buse (618; 718).
  39. Dispositif selon la revendication 34, caractérisé en ce que le dispositif à surface directrice d'écoulement est constituée par un dispositif directeur (937, 935), compensant l'impulsion de rotation déclenchée par le formateur de canal de refroidissement (930, 992, 940, 942) sur la masse extrudée.
  40. Dispositif selon la revendication 39, caractérisé en ce que le dispositif directeur (935, 937) est monté tournant dans la buse (918).
  41. Dispositif selon l'une des revendications 11 à 40, caractérisé en ce que le mandrin de buse (70) s'achève à une distance (AX) prédéterminée, de préférence réglable, devant la pièce d'embouchure de buse (DM).
  42. Dispositif selon l'une des revendications 11 à 41, caractérisé en ce que le mandrin de buse (70, 72) est réalisé en deux parties, une partie (70), servant au tourillonnement de l'arbre et assurant une étanchéité du palier vis-à-vis de la pièce d'embouchure de buse (DM), étant susceptible d'être insérée de préférence vissée dans un corps support (72).
  43. Dispositif selon l'une des revendications 11 à 42, caractérisé en ce que la au moins une tige est constituée d'un matériau ayant un module d'élasticité-E élevé tel que, par exemple, en acier ou en métal dur ou en un matériau céramique.
  44. Barre cylindrique fabriquée en une masse plastique en particulier une masse en poudre métallique plastifiée ou céramique, ou bien fabriquée selon un procédé d'extrusion avec au moins un canal intérieur, s'étendant au moins par tronçon en forme d'hélice et ayant une section transversale prédéterminée, caractérisée en ce que la section transversale de la barre est différente d'une forme circulaire et la barre n'étant pas vrillée.
EP93908925A 1992-04-08 1993-04-07 Procede et dispositif de fabrication continue de barres cylindriques comportant au moins un canal interieur helicoidal, et ebauche frittee realisee selon ce procede Expired - Lifetime EP0634959B1 (fr)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
DE19924211827 DE4211827C2 (de) 1992-04-08 1992-04-08 Verfahren und Strangpreßwerkzeug zur kontinuierlichen Herstellung von zylindrischen Stäben mit zumindest einem innenliegenden, wendelförmigen Kanal, und nach diesem Verfahren hergestellter Stab
DE4211827 1992-04-08
DE19924242336 DE4242336A1 (de) 1992-12-15 1992-12-15 Verfahren und Vorrichtung zur kontinuierlichen Herstellung von zylindrischen Stäben mit zumindest einem innenliegenden, wendelförmigen Kanal, und nach diesem Verfahren hergestellter Sinterrohling
DE4242336 1992-12-15
PCT/EP1993/000860 WO1993020961A1 (fr) 1992-04-08 1993-04-07 Procede et dispositif de fabrication continue de barres cylindriques comportant au moins un canal interieur helicoidal, et ebauche frittee realisee selon ce procede

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EP0634959A1 EP0634959A1 (fr) 1995-01-25
EP0634959B1 true EP0634959B1 (fr) 1997-03-26

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DE602004028726D1 (de) * 2003-06-04 2010-09-30 Seco Tools Ab Verfahren und vorrichtung zur herstellung eines zuschnitts für ein werkzeug
CN1298451C (zh) * 2005-06-16 2007-02-07 上海交通大学 螺旋式挤压成型加工装置
CN1298449C (zh) * 2005-06-16 2007-02-07 上海交通大学 螺旋式挤压成型方法
CN102744282A (zh) * 2012-07-19 2012-10-24 西北工业大学 螺旋分流挤压镁合金棒材的模具
CN103252679A (zh) * 2013-05-20 2013-08-21 苏州瑞森硬质合金有限公司 加工切削刀具用高效螺形内冷棒材
FR3131544B1 (fr) 2021-12-30 2024-01-05 Tech Avancees Et Membranes Industrielles Dispositif et procédé pour la fabrication par extrusion d’un support poreux avec un canal central rectiligne et des canaux non rectilignes

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DE3714479A1 (de) * 1987-04-30 1988-11-17 Krupp Gmbh Strangpresswerkzeug zur herstellung eines bohrerrohlings mit mindestens einer innenliegenden, wendelfoermig verlaufenden spuelbohrung
AT400687B (de) * 1989-12-04 1996-02-26 Plansee Tizit Gmbh Verfahren und strangpresswerkzeug zur herstellung eines rohlings mit innenliegenden bohrungen
DE4120165C2 (de) * 1990-07-05 1995-01-26 Friedrichs Konrad Kg Strangpreßwerkzeug zur Herstellung eines Hartmetall- oder Keramikstabes
DE4120166C2 (de) * 1991-06-19 1994-10-06 Friedrichs Konrad Kg Strangpreßwerkzeug zur Herstellung eines Hartmetall- oder Keramikstabes mit gedrallten Innenbohrungen

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EP0634959A1 (fr) 1995-01-25
ATE150675T1 (de) 1997-04-15
JP3662249B2 (ja) 2005-06-22
WO1993020961A1 (fr) 1993-10-28
JPH08502015A (ja) 1996-03-05
JP2004339610A (ja) 2004-12-02
DE59305967D1 (de) 1997-04-30

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