Method for producing a blank from extrusion material, and extruder

Abstract

The invention relates to a method for producing a blank, in particular a blank for the production of a cutting tool, wherein a green body extending in the direction of the extrusion axis is produced from extrusion material by means of an extruder which has an extrusion channel extending along an extrusion axis; wherein the extrusion channel together with a movable mold element forms a die of the extruder; and wherein the mold element is moved relative to the extrusion channel and within said extrusion channel during the extrusion of the green body, whereby the shaping geometry of the die is changed so that the completely extruded green body hereby has a first functional segment and a second functional segment adjacent thereto in the direction of the extrusion axis (4); wherein the two functional segments differ with regard to their geometries impressed by the die.

Claims

1. A method for producing a blank for the production of a cutting tool in which a green body extending in the direction of an extrusion axis is produced from extrusion material by means of an extruder that has an extrusion channel extending along the extrusion axis, wherein the extrusion channel, together with a movable mold element, form an adjustable die of the extruder, the method comprising: moving the first movable mold element relative to the extrusion channel and within said extrusion channel during the extrusion of the green body, wherein the first movable mold element is moved during the extrusion of the green body so that, as a result, the extruded green body has a first functional segment and a second functional segment following in the direction of the extrusion axis, wherein the first functional segment and the second functional segment have different geometries that are formed by the adjustable die, wherein the first movable mold element is moved in an orthogonal direction to the extrusion axis during the extrusion of the green body; and moving a second movable mold element along the extrusion axis of the extrusion channel during the extrusion of the green body, wherein the first movable mold element is configured to guide a filament that is moved relative to the first movable mold element during the extrusion of the green body so that said filament at least intermittently emerges with a free end from the first movable mold element and extends into the extrusion material.

2. The method according to claim 1, wherein a hollow shaft is produced within the extrusion material during the extrusion of the green body.

3. The method according to claim 1, wherein the first movable mold element is moved during the extrusion of the green body in such a way that a reduced cross section, a hollow shaft, at least one flute, and/or at least one cooling channel is formed in one of the first and second functional segments.

4. The method according to claim 1, wherein the second movable mold element comprises a cylindrical nozzle insert located in the extrusion channel.

5. The method according to claim 1, wherein the free end of the filament emerges from the first movable mold element in a direction with a radial component.

6. The method according to claim 1, wherein the first movable mold element and/or the filament is moved together with the extrusion material in the extrusion channel at the same velocity during the extrusion of the green body.

7. The method according to claim 1, wherein the first movable mold element has a filament at an end facing toward the extrusion channel, and in that, during the extrusion of the green body, a free end of the filament is driven in the direction of the extrusion axis of the extrusion channel.

8. The method according to claim 1, wherein the filament has a continuously varying diameter over the length of the filament.

9. The method according to claim 1, wherein a movable twist element is arranged downstream of the extrusion channel in the extrusion direction, and wherein the twist element is moved or rotated during the extrusion of the green body.

10. The method according to claim 1, wherein the geometry of an already extruded part of the green body is detected by one or more sensors during the extrusion of a green body, and in that, based on the information thereby obtained, the further movement of the first movable mold element during the further extrusion of the green body is controlled in order to produce a predetermined geometry of the green body.

11. The method according to claim 1, wherein the first movable mold element is rotated during the extrusion of the green body.

12. The method according to claim 1, wherein the first movable mold element has an end with a non-hemispherical shape.

13. A method for producing a blank for the production of a cutting tool in which a green body extending in the direction of an extrusion axis is produced from extrusion material by means of an extruder that has an extrusion channel extending along the extrusion axis, wherein the extrusion channel, together with a first movable mold element, form an adjustable die of the extruder, the method comprising: moving the first movable mold element relative to the extrusion channel and within said extrusion channel during the extrusion of the green body, wherein the first movable mold element is moved during the extrusion of the green body so that, as a result, the extruded green body has a first functional segment and a second functional segment following in the direction of the extrusion axis, wherein the first functional segment and the second functional segment have different geometries that are formed by the adjustable die, wherein the first movable mold element is moved in an orthogonal direction to the extrusion axis during the extrusion of the green body; and moving a second movable mold element along the extrusion axis of the extrusion channel during the extrusion of the green body, wherein the green body is produced from two different extrusion materials, wherein the extruder has a slide control movable between two positions, wherein the slide control releases one of two extrusion material feed devices toward the extrusion channel depending on the position, and wherein the slide control is moved between the two positions during the extrusion of the green body.

14. An extruder for producing green bodies, comprising: an extrusion channel extending along an extrusion axis and a first movable mold element, wherein the extrusion channel and the first movable mold element form an adjustable die configured for producing an extruded green body extending in the direction of the extrusion axis, wherein the first movable mold element is movable relative to the extrusion channel within the extrusion channel during the extrusion of the green body, whereby the first movable mold element of the adjustable die is moved so that the extruded green body has a first functional segment and a second functional segment following the first functional segment in the direction of the extrusion axis, wherein the first functional segment and the second functional segment have different geometries that are formed by the adjustable die, wherein the first movable mold element is moved in an orthogonal direction to the extrusion axis during the extrusion of the green body, wherein a second movable mold element is moved along the extrusion axis during the extrusion of the green body, and wherein the first movable mold element is configured to guide a filament that is moved relative to the first movable mold element during the extrusion of the green body so that said filament at least intermittently emerges with a free end from the first movable mold element and extends into the extrusion material.

15. The extruder according to claim 14, wherein a hollow shaft is produced within the extrusion material during the extrusion of the green body.

16. The extruder according to claim 14, wherein the first movable mold element is moved during the extrusion of the green body in such a way that a reduced cross section, a hollow shaft, at least one flute, and/or at least one cooling channel is formed in one of the first and second functional segments.

17. The extruder according to claim 14, wherein the second movable mold element comprises a cylindrical nozzle insert which is located in the extrusion channel and is moved along the extrusion axis of the extrusion channel during the extrusion of the green body.

18. A method for producing a blank for the production of a cutting tool in which a green body extending in the direction of an extrusion axis is produced from extrusion material by means of an extruder that has an extrusion channel extending along the extrusion axis, wherein the extrusion channel, together with a first movable mold element and a second movable mold element, form an adjustable die of the extruder, the method comprising: moving the first movable mold element relative to the extrusion channel and within said extrusion channel during the extrusion of the green body, wherein the first movable mold element is moved during the extrusion of the green body so that, as a result, the extruded green body has a first functional segment and a second functional segment following in the direction of the extrusion axis, wherein the first functional segment and the second functional segment have different geometries that are formed by the adjustable die, wherein the first movable mold element is moved in an orthogonal direction to the extrusion axis during the extrusion of the green body; and moving the second movable mold element along the extrusion axis of the extrusion channel during the extrusion of the green body, wherein the green body is produced from two different extrusion materials, wherein the extruder has a slide control movable between two positions, wherein the slide control releases one of two extrusion material feed devices toward the extrusion channel depending on the position, and wherein the slide control is moved between the two positions during the extrusion of the green body.

19. The method according to claim 18, wherein the first movable mold element is configured to guide a filament that is moved relative to the first movable mold element during the extrusion of the green body so that said filament at least intermittently emerges with a free end from the first movable mold element and extends into the extrusion material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These respectively show simplified schematic illustrations of:

(2) FIG. 1 a sectional view of a first embodiment of an extruder with a mold element and a partially produced green body,

(3) FIG. 2 a sectional view of a second embodiment of the extruder with a mold element and a partially produced green body,

(4) FIG. 3 a sectional view of a third embodiment of the extruder with a mold element and a partially produced green body,

(5) FIG. 4 a sectional view of a fourth embodiment of the extruder with three mold elements and a partially produced green body,

(6) FIG. 5 a sectional view of a fifth embodiment of the extruder with three mold elements and a partially produced green body,

(7) FIG. 6 a sectional view of a sixth embodiment of the extruder with five mold elements and a partially produced green body,

(8) FIG. 7 a sectional view of a seventh embodiment of the extruder with a mold element, a twist element, and a partially produced green body,

(9) FIG. 8 a perspective view of a first green body prior to a torsion,

(10) FIG. 9 a sectional view of an eighth embodiment of the extruder with five mold elements, a twist element, and a partially produced green body,

(11) FIG. 10 a sectional view of a second green body,

(12) FIG. 11 a rear view of the second green body,

(13) FIG. 12 a sectional view of a ninth embodiment of the extruder with five mold elements and a slide control in a first position,

(14) FIG. 13 a sectional view of the ninth embodiment of the extruder with five mold elements and the slide control in a second position,

(15) FIG. 14 a rear view of a third green body,

(16) FIG. 15 a rear view of a fourth green body,

(17) FIG. 16 a sectional view of a tenth embodiment of the extruder with four mold elements and a partially produced green body,

(18) FIG. 17 a sectional view of an eleventh embodiment of the extruder with a nozzle insert in a first position,

(19) FIG. 18 a sectional view of an eleventh embodiment of the extruder with a nozzle insert in a second position,

(20) FIG. 19 a sectional view of a twelfth embodiment of the extruder with a partially produced green body,

(21) FIG. 20 a sectional view of a thirteenth embodiment of the extruder with two mold elements and a partially produced green body,

(22) FIG. 21 a sectional view of a fourteenth embodiment of the extruder with two mold elements and a partially produced green body,

(23) FIG. 22 a sectional view of a fifteenth embodiment of the extruder with four mold elements and a partially produced green body,

(24) FIG. 23 a sectional view of a sixteenth embodiment of the extruder with two mold elements and a partially produced green body,

(25) FIG. 24 a sectional view of a seventeenth embodiment of the extruder with two mold elements and a partially produced green body, and

(26) FIG. 25 a sectional view of an eighteenth embodiment of the extruder with two mold elements and a partially produced green body.

(27) The terms used, in particular the designations of components and assemblies and the reference symbols used, are hereby introduced gradually, wherein reference is typically made to a selected Figure in various sections in each instance. Since most design variants have commonalities, thus for example a number of similar components, diverse embodiments in different sections of the description can be read or transferred among multiple figures. This also becomes evident in that parts having the same effect are provided with the same reference symbols in Figures.

DETAILED DESCRIPTION

(28) A method described below by way of example serves to produce a blank, in particular a blank for the production of a cutting tool, thus for example a drill or a reamer. Within the course of the method, a green body 8 extending in the direction of the extrusion axis 4 is initially produced from extrusion material 10 by means of an extruder 2, which is shown in various design variants in FIG. 1 to FIG. 7, FIG. 9, FIG. 12, FIG. 13, and FIG. 16 to FIG. 25, and which has an extrusion channel 6 extending along an extrusion axis 4. The produced green body 8 is then typically subjected to a sintering process, and in some instances a finishing finally takes place, for example via grinding.

(29) In this instance, the extrusion channel 6 together with a movable mold element 12 forms a die, effectively an adjustable die, of the extruder 2, and the mold element 12 is moved relative to the extrusion channel 6 during the extrusion of the green body 8. Via this movement, and thus the adjustment of the die, the shaping geometry of the die is changed so that the completely extruded green body 8 hereby has a first functional segment 14 and a second functional segment 16 adjacent thereto in the direction of the extrusion axis 4 or in the longitudinal direction of the green body 8, wherein the functional segments 14, 16 differ with regard to their geometries impressed by the die.

(30) In this way, a hollow shaft 18 and/or a reduced cross section 20 and/or at least one flute 22 and/or at least one cooling channel 24 is then realized in the green body 8 in one of the functional segments 14, 16, for example. Typical in this instance in particular is an embodiment in which a reduced cross section 20, a number of flutes 22, and a number of cooling channels 24 are realized in the first functional segment 14 in comparison to the second functional segment 16, and in which a hollow shaft 18 is realized in the second functional segment 16 following thereon, which hollow shaft either is open at the end as indicated in FIG. 14 or is closed at the end as shown in FIG. 10, FIG. 11, and FIG. 15.

(31) In particular for realizing a hollow shaft 18 and/or for realizing cooling channels 24, the mold element 12 is moved along the extrusion axis 4 during the extrusion of the green body 8 as indicated in FIG. 1, for example. The mold element 12 is in particular transferred from a starting position to an end position during the extrusion of the green body 8, and is typically transferred back into the starting position at a later point in time, wherein the mold element 12 produces a free space in the green body 8 in one of the positions, which free space then, for example, forms a hollow shaft 18 and/or a number of cooling channels, whereas the mold element 12 does not produce a corresponding free space in the other position. The position generating a free space is reproduced in FIG. 1, for example.

(32) The mold element 12 for creating a hollow shaft 18 furthermore has a cylindrical shape, for example, and is preferably arranged centrally in the extrusion channel 6. According to another design variant, the mold element 12 has a cylindrical basic geometry, wherein projections and/or indentations are formed in the region of the cylinder jacket, for example in order to realize a cross section for the green body 8 as indicated in FIG. 14 in one of the functional segments 14, 16. A variant is shown here in which the green body 8 has elongated projections on the inside, which projections protrude into the hollow shaft 18.

(33) In an advantageous development, the mold element 12 for creating a hollow shaft 18 and/or for creating a number of cooling channels 24 is designed as a kind of nozzle insert 28, in particular as a cylindrical nozzle insert 28, which is located in the extrusion channel 6 and is moved along the extrusion axis 4 during the extrusion of the green body 8. The nozzle insert 28 is in particular moved once before the beginning of the extrusion of one of the two functional segments 14, 16 and once at the end of the extrusion of the corresponding functional segment 14, 16, and is thereby preferably moved back and forth between a starting position and an end position. This situation and the two positions are reproduced in the illustrations of FIG. 17 and FIG. 18.

(34) Alternatively, a corresponding hollow shaft 18 is produced in that the extrusion material 10 in is driven in the extrusion direction 30 against an auxiliary mold 32 inserted into the extrusion channel 6 in the direction opposite the extrusion direction 30. This auxiliary mold 32 is then removed again after forming the hollow shaft 18. The situation with inserted auxiliary mold 32 is shown in FIG. 19.

(35) According to another design variant, the mold element 12 has at least one filament 34 and/or is designed to guide a corresponding filament 34, in particular in order to form a number of cooling channels 24. A corresponding filament 34 is typically of spicular or thread-shaped design. Nevertheless, such a filament 34 has a dimensional stability such that the corresponding filament 34 is substantially not deformed by the extrusion material 10 driven through the extrusion channel 6. Depending on the use case, such a filament 34 furthermore has a cross section changing along the longitudinal extent of the filament 34, thus for example a cross section that continuously increases starting from one free end 36 of the filament 34, as is the case in the instance of the two filaments 34 according to FIG. 16.

(36) In this way, by displacing the filament 34 or the filaments 34 during the extrusion of the green body 8 along the extrusion axis 4, it can be predetermined not only whether this filament or these filaments produce a free space or free spaces in order to form a cooling channel 24 or cooling channels 24 but rather, depending on the position of the filament 34 or the filaments 34 in the extrusion channel 6, also what diameter the respective free space or the respective free spaces have. This means, that in the instance of the exemplary embodiment according to FIG. 16, the cross sections of the two cooling channels 24 are larger the further that the filaments 34 are positioned in the direction of the outlet opening of the extrusion channel 6. As an alternative or in addition to this, the position of the cooling channels 24 can also be variably predetermined in that a radial position is individually predetermined for each filament 34 via a radial displacement transversal to the extrusion axis 4 of the respective filament 34.

(37) In principle, in this instance the number of filaments 34 varies depending on the intended use, and/or the cross-sectional shape of the filaments 34 is adapted to the respective intended use. Thus, as indicated in FIG. 15, in some instances round cross sections are provided and, for example, trapezoidal cross sections are provided in other instances.

(38) As already mentioned above, in some instances the mold element 12 does not simply have only one or a plurality of filaments 34, but rather is designed to guide a filament 34 or a plurality of filaments 34. In this instance, the filament 34 is or the filaments 34 are then displaced relative to the mold element 12 during the extrusion of the green body 8 so that the filament 34 at least intermittently emerges with one free end 36, or the filaments 34 at least intermittently emerge with respectively one free end 36, from the mold element 12 and reaches or reach into the extrusion material 10. Such a design variant is reproduced in the illustrations of FIG. 2 and FIG. 3, for example. In the instance of the exemplary embodiment of FIG. 3, the two filaments 34 are thereby guided in the mold element 12 in such a way that the free ends 36 are driven out of the mold element 12 in a direction with a radial component in order to in this way form openings of cooling channels 24 that are formed laterally or circumferentially at the green body 8.

(39) Particularly in the instance of this exemplary embodiment, the mold element 12 is moved together with the extrusion material 10 in the extrusion channel 6 at the same velocity and in the same direction, thus in the extrusion direction 30, at least intermittently during the extrusion of the green body 8. In particular in the instance of the exemplary embodiment according to FIG. 3, during this movement the free ends 36 of the two filaments 34 are additionally further preferably moved once out of the mold element 12 and into it again in order to ensure that the free ends 36 produce openings of the cooling channels 24, the cross section of which corresponds to the cross section of the free ends 36 of the filaments 34.

(40) Alternatively or in addition to the previously described exemplary embodiments, the extruder 2 has a mold element 12 which is moved in a direction with a radial component, and in particular along a transverse axis 38 transversal to the extrusion axis 4 of the extrusion channel 6, during the extrusion of the green body 8. A corresponding exemplary embodiment is reproduced in FIG. 4, for example. The mold element 12 is, for example, driven into the extrusion channel 6 or pulled out of the extrusion channel 6, in particular in order to realize a reduced cross section 20 and/or at least one flute 22.

(41) Such a mold element 12 movable along the transverse axis 38 is typically supplemented by a further movable mold element 12 which also forms part of the die of the extruder 2, such that a mold element pair is formed, for example. The two mold elements 12 of the mold element pair are in this instance preferably arranged circumferentially opposite each other at the extrusion channel 6. Furthermore, the two mold elements 12 of the mold element pair are preferably moved simultaneously and in particular along a common transverse axis 38, wherein the movements are usually opposite so that the two mold elements 12 of the mold element pair move toward or away from one another.

(42) If two flutes 22 are to be produced with the aid of the mold elements 12 of a mold element pair, it is furthermore advantageous if the two mold elements 12 of the mold element pair are designed to be pin-shaped as indicated in FIG. 20, for example, and respectively have an end protruding into the extrusion channel 6 and having a hemispherical shape. In this way, two straight flutes 22 can then be realized in one of the two functional segments 14, 16. By contrast, if helical flutes 22 are to be formed with the aid of the mold element 12 of the mold element pair, mold elements 12 are used whose ends have a deviating shape, for example as indicated in FIG. 21. In this exemplary embodiment, it is moreover advantageous if the mold elements 12 of the mold element pair are rotatable about their respective longitudinal axis as indicated. With the aid of these mold elements 12, a torsion is then impressed on the green body 8 in the corresponding functional segment 14, 16.

(43) Moreover, a not explicitly shown embodiment is also advantageous in which at least one mold element 12, and in particular both mold elements 12 of the mold element pair, is or are formed in the manner of a gouge or in the manner of a hollow needle. With such mold elements, not only are spatial regions then occupied so that they are effectively blocked for the extrusion material, but rather extrusion material is thus preferably removed and guided away in a targeted manner while the extrusion material is driven in the extrusion direction 30.

(44) Further design variants of a mold element pair made of two mold elements 12 for forming two flutes 22 are shown in the illustrations of FIG. 23 to FIG. 25, for example. While the two mold elements 12 of the mold element pair are designed to be pin-shaped and linearly movable along the longitudinal axis in the instance of the exemplary embodiments according to FIG. 23 and FIG. 24, in the exemplary embodiment according to FIG. 25 the mold elements 12 have a ring shape or disk shape and are respectively rotatable about an axis of rotation 40. In this instance, each ring-shaped mold element 12 has a flat portion 42 which is always rotated in the direction of the extrusion channel 6 via a rotation of the mold elements 12 about the axes of rotations 40 when no flutes 22 are to be formed.

(45) According to another design variant, a mold element movable in a direction with a radial component or along the transverse axis 38 has a filament 34 of the type described above or a filament 34 with a thickening at the end as reproduced in FIG. 5, for example. In this instance, the free end 36 of the filament 34 is preferably moved along the extrusion axis 4 if the mold element 12 is moved along the transverse axis 38. For this, a corresponding filament 34 then has a certain flexibility so that it can be deformed by a guide in the extruder 2 but not by the extrusion material 10.

(46) According to a further design variant, a movable twist element 44 is additionally or alternatively arranged downstream of the extrusion channel 6 in the extrusion direction 30, wherein the twist element 44 is moved during the extrusion of the green body 8 and in particular is rotated about the extrusion axis 4 of the extrusion channel 6. A torsion is then hereby impressed on the green body in at least one of the functional segments 14, 16. This situation is shown in FIG. 7, for example. For example, such a twist element 44 is in this instance designed in a hollow cylinder shape, for example as indicated in FIG. 7, or has a cylindrical basic geometry with additional pins as shown in FIG. 22, for example. The additional pins engage in the still-straight flutes 22 and prevent a cross section deformation of the flutes 22 during the impression of a torsion.

(47) Alternatively, a corresponding torsion can also be impressed subsequently via a post-processing in that, for example, the corresponding functional segment 14, 16 is positioning between two flat bodies which execute a type of shearing movement at a constant distance. This approach is indicated in FIG. 8.

(48) The mold elements 12 described above are combined with each other in diverse ways depending on the intended use, wherein the illustrations according to FIG. 6 and FIG. 9 reproduce two further design variants.

(49) As an alternative or in addition to the method variants described above, a one-piece green body 8 that is manufactured from at least two different extrusion materials 46, 48 is produced with the aid of the method. For example, a green body 8 is produced in which, as viewed along the extrusion axis 4, the first functional segment 14 is formed by means of a first extrusion material 46, and in which the second functional segment 16 is realized by means of a second extrusion material 48.

(50) A one-piece green body 8 depicted in FIG. 10 and FIG. 11 is preferably further produced in which a first segment 50 of the first functional segment 14 is produced from the first extrusion material 48, in which a second segment 52 of the first functional segment 14 is produced from the second extrusion material 48, in which a first segment 54 of the second functional segment 16 is produced from the second extrusion material 48, and in which a second segment 56 of the second functional segment 16 is again produced from the first extrusion material 46. In this exemplary embodiment, the first extrusion material 46 is of higher quality and, after completion, the finished cutting tool has a higher durability, in particular a higher hardness, in the segments 50, 56 which are produced from the first extrusion material 46. At least one cuffing edge is then, for example, positioned in the first segment 50 of the first functional segment 14 in the finished cuffing tool.

(51) The fact that the second segment 56 of the second functional segment 16 is at least preferably also produced from the second extrusion material 48, which is typically of higher quality, is due to the fact that, preferably in the instance of all previously mentioned method variants, a continuous extrusion process is provided in which a type of endless strand emerges from the extrusion channel 6, which endless strand is then divided at regular intervals to finish the green body 8. The severing typically takes place at the end of each second functional segment 16 of a green body 8 which is adjoined in the endless strand by a first functional segment 14 of a further green body 8. Via the formation of the second segment 56 of the second functional segment 16 from the first extrusion material 46, it is then ensured that the first segment 50 of the first functional segment 14 of each green body 8 is in each instance completely formed from first extrusion material 46.

(52) For the production of a green body 8 from two different extrusion materials 46, 48, it is advantageous if the extruder 2 has a slide control 58 which in particular can be moved between two positions and which, depending on the position, releases one of two extrusion material feed devices 60 toward the extrusion channel 6 so that subsequently only the extrusion material 46, 48 fed through this extrusion material feed device 60 is driven through the extrusion channel 6. The two positions are indicated in FIG. 12 and FIG. 13. During the extrusion of the green body 8, the slide control 58 is then brought into one of these positions in order to subsequently produce a section of the green body 8 from one of the extrusion materials 46, 48.