CN112672834A - Drawing die with associated die blank holder - Google Patents

Abstract

The present invention relates to a drawing die and associated die blank holder. The die blank holder is configured such that during drawing, at least 20% of the die blank mantle surface remains exposed to the coolant in a limited number (e.g., two, three, up to twelve) of non-intersecting regions. In this way, sufficient cooling of the mold base is ensured. The blank holder includes a base plate having a protruding clamp that holds a blank. The blank holder is made of a single piece of material. An associated method of inserting a mold blank into a mold blank holder is also described.

Description

Drawing die with associated die blank holder

Technical Field

The present invention relates to the field of drawing dies for drawing metal wires. The drawing die of claim 1 is particularly suitable for drawing wire in a liquid lubricant (also known as "wet drawing"). According to a second aspect of the invention, a blank of a drawing die is held in a blank holder. Representing a third aspect of the invention, a method of inserting a blank into a blank holder is also described.

Background

In the manufacture of metal wires like steel wire, copper alloy wire, aluminium alloy wire, the wire is drawn through a gradually smaller orifice in a drawing die, so that the diameter of the wire becomes gradually smaller. The drawing dies are held in a draw bench provided with a plurality of capstans between the drawing dies, which draw the wire through the orifice. A lubricant is applied to the wire to reduce friction between the drawing die and the passing wire.

Due to the large amount of heat generated by the plastic deformation of the wire and the friction between the wire and the drawing die, the drawing die must be cooled to prevent premature failure of the drawing die. In dry wire drawing, i.e. when using dry powder as a lubricant, the drawing dies are separately provided with a supply of coolant. In wet drawing, the drawing die and the wire are immersed in a liquid emulsion which acts as a lubricant as well as a coolant. In the remainder of the application, the word "coolant" will be used consistently, but it will be understood by those skilled in the art that "coolant" here also has other functions, such as lubrication.

The present application concerns drawing dies for wet drawing processes and machines, i.e. "wet drawing dies" or simply "drawing dies" in the following. In a typical wet wire drawing machine, 10-50 drawing dies may be assembled. A typical wire rolling mill uses hundreds to millions of drawing dies per year.

Known wet wire drawing dies include a cylindrical die blank held in a cylindrical metal housing. The mold base is made of a very hard material and an axial funnel shaped hole is machined and polished in the mold base. The housing is made of machine steel. One problem with known wet wire drawing dies is that heat transfer is not always optimal since the heat must leave the die blank and must be absorbed by the housing, which in turn is in contact with the coolant. To overcome this cooling problem, different proposals have been made in the prior art:

GB87225(D1) describes a blank holder (referred to as "die holder" in D1) in which a blank 17 (referred to as "pellet" in D1) is held, the holder being provided with a "cavity" having "radial ports" leading from the periphery of the cavity, for supplying a cooling medium directly around the blank. Such holders are complicated to manufacture and a coolant must be injected into the radial ports to cool the mold base.

DE596506(D2) describes a blank holder "F" for a dry-drawing die, in which a cooling channel is provided in the blank holder. Such holders are difficult to manufacture and the cooling liquid must be supplied separately.

GB298821(D3) describes a housing for a drawing die, wherein the housing is constituted by a hollow member surrounding the die, the hollow member being provided with an inlet opening at the front of the housing and an outlet opening at the rear of the housing, the inlet and outlet openings communicating with an annular space between the blank and the housing for the passage of a cooling liquid in the die. Such holders are complicated to manufacture and require cooling liquid to be forced through the drawing die to achieve good cooling.

CN201324454U (D4) describes a die blank holder provided with a peripheral cooling groove. The inventors have experienced that cooling channels tend to accumulate dirt, thereby reducing the cooling capacity of the mould.

To overcome the disadvantages of the prior art, the inventors propose a novel drawing die design, which will now be described in detail.

Disclosure of Invention

The main object of the present invention is to provide a drawing die capable of cooling a die blank satisfactorily. Another object of the inventors is to provide a drawing die and its associated blank holder that are easy to manufacture and that can reduce both material and manufacturing costs. It is another object of the present invention to provide a method of installing a blank into a blank holder. It is a further object of the present invention to provide a method of manufacturing a blank holder.

According to a first aspect of the invention, a drawing die is proposed having the features of claim 1. The wire drawing die comprises a die blank and a die blank holder, wherein the die blank is provided with a through hole. The through holes are generally funnel or horn shaped. The filaments enter at the wider entrance of the funnel (referred to as the "entrance cone") and exit through the narrower spout. After leaving the spout, the through-hole opens again into an "exit cone". The through hole defines a die blank axis.

The die blank has a frustoconical and/or cylindrical mantle coaxial with the die blank axis. Thus, the mantle of the mould blank may be completely a cylinder over the entire axial length of the mould blank. Alternatively, the mantle of the mold base may be a single truncated cone over the entire axial length of the mold base. The truncated cone is a truncated cone. The boot may also be a combination of a cylindrical surface over a portion of the axial length and a truncated cone over the remainder of the axial length. An alternative and equivalent expression is that the mold base has a "generally cylindrical mantle".

According to the invention, the blank holder leaves at least 20% of the surface of the blank jacket surface uncovered and this part is located in a limited number of uncovered areas. Where "uncovered area" means that the blank holder does not contact the blank at that area. The regions may be disjoint, meaning that a line may be drawn between regions on the mantle of the mold base without entering those regions. The total surface of the uncovered area is at least 20% of the surface of the mantle. For the sake of clarity: wherein the surface of the mantle refers to the surface of the frustoconical and/or cylindrical circumferential mantle of the mold base and thus does not include the axial extreme (top and bottom) regions of the mold base. The number of uncovered areas that may not be intersected is two or three or four or five or six or seven or eight up to and including twelve.

When the number of uncovered areas is less than two, the blank holder will not be able to hold the blank sufficiently. When there are more than twelve uncovered areas, the blank holder becomes difficult to manufacture.

In an alternative and equivalent manner of describing the present invention, at least 20% of the surface of the mantle surface is visible, i.e., in line of sight, when the mold blank held in the mold blank holder is viewed in all directions perpendicular to the mold blank axis.

When the drawing die is immersed in the coolant during drawing, the coolant can reach the die blank jacket immediately without hindrance, since the coolant completely surrounds the drawing die. The mold base is cooled well because the coolant can freely enter the mold base mantle. Due to the open structure of the blank holder, the blank is directly exposed to the coolant, so that no cooling feed channel is required. Due to the open structure of the blank holder, there is no risk that the cooling channel becomes clogged, e.g. due to dirt in the coolant, inhibiting the cooling of the mould.

In a simplified form of the invention, the drawing die consists only of the blank and the blank holder, without further components.

In a further preferred embodiment, at least 30%, 40%, 50%, 60%, 70% or even 80% of the mantle surface remains uncovered by the blank holder. While continued exposure of the mantle surface of the mold base may further improve cooling, this may result in increased difficulty in retaining the mold base in the mold base. The object of the drawing die of the invention is to improve the cooling of the die blank by exposing the mantle of the die blank as much as possible while the die blank is held in the die blank holder.

In another alternative and equivalent way of describing the invention, the blank holder covers at most 80% of the surface of the blank jacket in a number of areas covered by the blank holder, the number of said areas being one, two, three, four, five, six, seven or eight, up to and including twelve. If necessary, the cooling capacity of the mold blank will be increased when the coverage of the mold blank jacket by the mold blank holder is reduced to at most 70%, 60%, 50%, 40%, 30% or even 20% of the surface of the mold blank jacket.

The mold base is made of a hard material such as a cermet, a hard metal, a cemented carbide, a polycrystalline diamond (PCD) compact, or a single crystal diamond from natural or synthetic sources. Cemented carbides such as tungsten carbide with, for example, a binder containing cobalt are mainly used. PCD compacts are also preferred for use in the present invention.

In an alternative definition of the invention, the blank holder comprises a base plate from which the clamp protrudes. The clamp is used to hold the mold base firmly. The clamp is integral with the base plate, which means that the base plate and the clamp are made of one integral single piece of material: there is no soldering or mechanical connection between the substrate and the fixture. The base plate has at least one through hole, coaxial with the axis of the die blank, through which the wire is drawn during use. The wire is pulled in a direction from the clamp to the base plate.

According to the invention, the clamp covers at most 80% of the surface of the mould blank mantle. A smaller coverage, such as less than 70%, 60%, 50%, 40%, 30% or even 20%, may further enhance cooling of the mold base, but at the expense of not being sufficiently robust to remain in the mold base. Preferably, at least 20% of the surface of the mantle surface is in line of sight when viewing the mold blank held in the mold blank holder in all directions perpendicular to the mold blank axis. The amount of visible surface may also be greater than 30%, 40%, 50%, 60%, 70% or even 80% of the mantle surface.

The substrate may have any shape, but more preferably the substrate has a polygonal shape, such as a standard polygon or a Reuleaux (Reuleaux) polygon. The number of vertices is preferably equal to the number of clamps.

In another highly preferred embodiment, the substrate is annular or ring-belt shaped.

In another preferred embodiment, the clips protruding from the substrate are evenly distributed at an angle. For example, if the number of clamps is three, the angle between the clamps is 120 ° as viewed from the axis of the die blank. In the case where the number of the jigs is "N", the angle between the jigs as viewed from the axis of the die blank is 360/N.

In a further preferred embodiment, a recess is provided around the through hole in the base plate of the blank holder. The recess is for receiving the base of the mold base. The "base of the die blank" is one of the surfaces that axially bounds the die blank at the side of the die blank exit cone.

The number of clamps is at least two (since at least two clamps are required to hold the object) or any higher number, such as two, three, four, five, six, seven or eight, up to and including twelve. Increasing the number of clamps makes manufacturing more complicated. Preferably, the number of clamps is three, four, five or six. Depending on the manufacturing method, it may be preferable to use an even or odd number of jigs. An even number of clamps is more preferred when the blank holder is manufactured by machining, whereas an odd number of clamps is more preferred when the mold base is cast, in contrast.

In a highly preferred embodiment, the transition from the base plate to the clip protruding from the base plate is rounded. More specifically, the transition from the substrate to the clamps is radiused between the clamps. Wherein "rounded corners" means that the transition does not have sharp corners where dust may accumulate. The minimum value of the radius of curvature is at least half a millimeter. More preferably 1 mm, 2 mm or more.

In another preferred embodiment, the clamp projecting from the base plate extends at least two-thirds of the axial length of the mold base outside the base plate. A shorter extension of the clamp results in a too low holding force for the mould blank. More preferably, the clamp protrudes beyond the base plate about the axial length of the mold base. It need not protrude any more because that would result in too much material.

In another preferred embodiment of the invention, the clamp is provided with a protrusion, a projection, a bump at the radially inner side of the clamp at the end opposite the base plate. The protrusion prevents the blank from being pulled out of the blank holder when the machine is stopped and the wire is rewound during the drawing process.

According to a second aspect of the present invention, a blank holder is presented. The blank holder has a base plate with a clamp protruding from the base plate. The clamp and the base plate are one piece, i.e. integral. The clamp and the base plate are made from the same continuous piece of material. The substrate has a through hole at the center of the substrate for allowing the filament to pass through. The blank holder is specifically designed for use in a drawing die according to the first aspect of the invention.

According to a preferred embodiment, the blank holder has an axis of symmetry passing through a through hole perpendicular to the base plate. In a preferred embodiment, the protruding clamps are evenly distributed at an angle around the symmetry axis.

In another preferred embodiment, the base plate of the blank holder is a ring. The number of projecting clips is two, three, four, five, six, seven or eight, or up to and including twelve.

Preferably, at the transition where the clamp extends above the base plate, the transition is rounded. Preferably, the radius of curvature at the transition is greater than half a millimeter, for example 1 millimeter or 2 millimeters or more. This is to prevent build-up of dirt during use of the drawing die in the wet wire drawing machine.

Further preferred embodiments of the blank holder may exhibit the following additional features:

the circumferential (relative to the blank axis) thickness of the projecting clamp decreases radially towards the centre of the blank holder. In this way, the clamp maintains sufficient strength to hold the mold blank while sufficient surface of the mold blank mantle remains uncovered.

On the radially inner top of the clamp, there are provided tabs, protrusions, ridges for holding the top of the mould blank. This ensures that the blank is retained in the blank holder when the pulled wire is rewound due to a sudden stop of the machine.

The clamps are mechanically held by a snap ring connecting all the clamps. The snap ring fits in a circumferentially formed recess in the top of the clamp. The snap ring is used to provide additional strength to the clamp.

According to a third aspect of the invention, a method of clamping a blank in a blank holder is provided, thereby forming a drawing die according to the invention. The method begins by providing a blank holder according to the second aspect of the invention. Next, a mold base is provided. The die blank has a cylindrical or frustoconical circumferential mantle or a tandem of both. In a further step, a force is applied at the center of the substrate while maintaining the outer edge of the substrate. The force is applied from the side opposite to the side of the clamp from which the substrate protrudes. This force opens the clamp very slightly, but is sufficient to allow temporary clamping of the mold base. This allows the mold base to be inserted between the projecting clamps. In the last step, the blank is pressed completely into the blank holder. The mold base may be received in a recess on the base plate.

In an alternative embodiment of the method, the method may be combined with heating the mould blank holder (e.g. when using a pure cylindrical mould blank). It should be noted, however, that the combination of applying force and applying heat at the center of the base plate does not cause plastic deformation of the die holder.

According to a fourth aspect of the invention, a method of manufacturing a mould blank holder according to the above by metal injection moulding is described. The method comprises the following steps:

-providing a mixture of a binder comprising metal powder;

-injection moulding the mixture into a casting mould, the inner cavity of the mould having the shape of a blank holder, thereby forming a new blank holder;

-removing a new blank holder from the casting mould;

-debonding the adhesive from the new blank holder, thereby forming a baked blank holder;

-sintering the fired mold blank holder to maximum densification;

-cooling the sintered mould blank holder, thereby obtaining a finished mould blank holder.

Drawings

FIG. 1 shows a prior art drawing die;

figure 2 shows a first drawing die according to the invention;

figure 3 shows a second drawing die according to the invention;

figure 4 shows a third drawing die according to the invention;

fig. 5 shows a fourth drawing die according to the invention;

FIG. 6 illustrates a method of inserting a mold base into a mold base holder;

similar items in different figures have the same ones and tens digits, with the hundreds digit indicating the figure number.

Detailed Description

Fig. 1 illustrates a prior art drawing die 100 that includes a die blank holder 102 (also referred to as a "housing") and a die blank 104. The die blank has a through hole 110 through which the wire is guided. The filaments enter at a wide entrance cone 106 and exit through a small exit cone 108. Thus, the through-hole has a funnel shape.

The mold base was made of cemented tungsten carbide with cobalt as the binder. The dimensions and finish of the mould blank are unified according to international standards such as ISO 1684 and ISO 2804. The dimensions of the blank are denoted by D × H, where "D" is the outer diameter of the blank (usually in mm) and "H" is the axial height of the blank (usually also in mm). Typical die blank sizes are for example 12 x 10 or 16 x 13. The jacket shape of the blank is generally cylindrical (when the blank is inserted into the housing by means of a "hot housing") or a combination of a cylindrical surface and a frustoconical bevel on the side of the exit cone (when the blank is inserted into the housing by means of a "cold housing"). Mold blanks are available from suppliers such as Ceratitzit, Hyperion, and many others.

In prior art drawing dies, the die blank holder is a steel cylinder with a central bore in which the die blank is a tight fit (by a "hot" or "cold" shell). Since the mantle of the die blank is in intimate contact with the steel shell, it is believed that the heat generated in the die blank will readily pass through the die blank to the steel barrier. However, the minute clearance between the die blank and the housing can form a thermal barrier due to dirt or residual lubricant on the die blank or housing, thereby reducing heat extraction and increasing die blank temperature during drawing.

Fig. 2 shows a first embodiment of a drawing die 200. The drawing die includes a blank 204, which is a conventional blank held in a blank holder 202. The mold base holder is of an open design such that in three non-intersecting regions, approximately 50% of the outer jacket of mold base 204 is uncovered. The sum of the uncovered areas amounts to about 50% of the mantle surface. In other words: the blank holder covers only about 50% of the surface of the blank, the rest being directly visible.

The ratio of uncovered surface to the total surface of the mantle can be verified by a number of methods, for example:

removing the blank by spraying (a "line of sight" covering technique) the entire drawing die, measuring the sprayed surface and comparing it with the mantle surface of the blank;

-by computer-assisted visual techniques based on pictures of the drawing dies. The surface area of the mold base not covered by the mantle was calculated by taking into account the cylindrical shape of the mold base.

The drawing die is configured in such a manner that during use of the drawing die, the die blank is directly exposed to the coolant in which the drawing die is immersed. In this way, an intensive cooling effect of the mould blank is obtained, which is superior to the complete enclosure of the mantle of the mould blank in the prior art cylindrical shell. It is important that the coolant can be in direct contact with the mold base unobstructed without the need for additional feeding of coolant to the mold base (e.g., through channels).

In the shape of the blank holder 202, the substrate 212 can be identified, with three clamps 214, 214', 214 "protruding from the plane of the substrate 212. The clamps 214, 214', 214 "are distributed along the axis of the blank at an angle of 120 °, i.e. are evenly distributed angularly about the axis. Since the blank holder 202 is machined from a single piece of material, the clamp and base plate are integral. In this case, the substrate 212 is a ring provided with a central through hole for allowing the passage of the wire.

A second practical embodiment of a draw die 300 is shown in fig. 3. The draw die 300 is similarly made from a single piece of material with the clamp 314 protruding from the base plate 312 forming the blank holder 302. It differs from the first draw die in that the transition 316 from the base plate to the projecting clip is radiused. The rounding can prevent contaminants that may accumulate in the corners between the substrate and the clamp. Also in base plate 312, a circular recess is provided to accommodate the base of the mold base (not visible in FIG. 3).

Note that in both the first and second practical embodiments, the clamp is tapered, tapering in the radial direction towards the blank axis, i.e. the circumferential thickness of the clamp decreases progressively towards the blank axis. In this way, the surface of the mold blank jacket remains uncovered while the strength of the clamp is not compromised.

In a third practical embodiment of the draw die 400 shown in fig. 4, the die blank 404 is held in the die holder 402 by six evenly angularly distributed clamps 414. The transition from the base 412 to the fixture is rounded with a radius of curvature of about 1.5 mm. Note that in this case, the width of the jig 414 remains unchanged. In addition, a protrusion 422 is provided at the top, radially inside of the jig. Protrusion 422 serves to prevent mold base 404 from being pulled out of mold base holder 402 by the wire when the drawing machine is abruptly stopped and the wire recoil rebounds.

In a fourth practical embodiment of the draw die 500 shown in fig. 5, six clamps 514 are attached to a snap ring 520. The snap ring fits in a circumferential recess 524 formed in the top of the clamp. The snap ring adds additional strength to the clamp 514.

The material from which the blank holder is made is tool steel or machine steel. Examples are EN11SMnpb30 and EN C45E, etc.

The following method may be used to manufacture the blank holder:

first is a method of machining a blank holder. In this method, material corresponding to the outer dimensions of the die holder is removed from the round steel rod. The gap between the projecting clamps at the rod end is ground off, for example by a chisel or drill bit. The process ends with a turnmill rod end. With current numerically controlled machines, the process can be easily automated.

The casting method follows. The mold representing the blank holder may be manufactured by a lost wax technique. Molten metal is poured into the mold and the mold is opened after solidification to form a casting. The casting must be further finished to achieve the desired tolerances, which makes this method somewhat less preferred.

Thirdly, a metal injection molding technology is adopted. The technology comprises the following steps:

-thoroughly mixing the binder with the metal powder to obtain a homogeneous injection-material mixture, or

Obtaining ready-to-use commercially available injectables;

-injection moulding the mixture into a mould, forming a mould blank holder "green blank". The mold cavity has the shape of a mold blank holder;

removing the green compact of the compact holder from the casting mold;

-debonding the adhesive from the green blank of the mold blank holder, thereby forming a "brown blank" of mold blank holder;

-sintering the mould blank holder brown blank to maximum densification. During sintering, the green mold holder brown blank will shrink in its original dimensions. This shrinkage must be taken into account in the design of the blank holder mold.

The color words "green" and "brown" are used herein as customary in the art of metal injection molding, and do not have any relationship to the true color of the part. These two words only indicate the state of the sleeve: "Green" can be replaced by "New" and "Brown" can be replaced by "baking". This technique allows the die holder to be manufactured in large quantities and at low cost. Die blank holders made by this technique exhibit some tiny bubbles of entrained gas inside the metal. These micro-bubbles indicate the use of this metal injection molding technique.

Fig. 6a to 6d show a method of how a mould blank is inserted into a mould blank holder according to the invention.

In fig. 6a, a mold blank holder 602 according to the present invention and a mold blank 602 for insertion into the mold blank holder 602 are provided.

The blank holder 602 is placed in the clamps 630, 630', the clamps 630, 630' clamping the base plate 612 of the blank holder 602 between the protruding clamps 614 of the blank holder 602. The stamp 632 is pressed against the center of the substrate (see fig. 6 b).

The protruding clamp 614 of the mold blank holder is opened by applying a force 634 through the stamp 632. The mold base is fully inserted into the mold base holder by driving mold base 604 with force 636 (see fig. 6 c).

After all the force is released, the mold base is held firmly between clamps 614 as shown in FIG. 6 d.

Claims (18)

1. A wiredrawing die comprising a die blank and a die blank holder for holding said die blank, said die blank having a through bore defining a die blank axis, said die blank further having a frusto-conical and/or cylindrical mantle coaxial with said die blank axis,

it is characterized in that the preparation method is characterized in that,

the blank holder leaves at least 20% of the surface of the mantle uncovered over a number of uncovered areas, the number of uncovered areas being two, three, four, five, six, seven or eight up to and including twelve.

2. A wiredrawing die comprising a die blank and a die blank holder for holding said die blank, said die blank having a through bore defining a die blank axis, said die blank further having a frusto-conical and/or cylindrical mantle coaxial with said die blank axis,

it is characterized in that the preparation method is characterized in that,

at least 20% of the surface of the mantle is in line of sight when viewing the mold blank held in the mold blank holder in all directions perpendicular to the mold blank axis.

3. A wiredrawing die comprising a die blank and a die blank holder for holding said die blank, said die blank having a through bore defining a die blank axis, said die blank further having a frusto-conical and/or cylindrical mantle coaxial with said die blank axis,

it is characterized in that the preparation method is characterized in that,

the blank holder has a base plate with a clamp protruding from the plane of the base plate for holding the blank, the clamp being integral with the base plate, the base plate having a through hole coaxial with the blank axis.

4. The draw die of claim 3, wherein the clamp covers at most 80% of the surface of the mantle.

5. A wiredrawing die as claimed in claim 3 or 4, wherein said substrate is a ring.

6. A wiredrawing die as claimed in any one of claims 3 to 5, wherein said projecting clamps are evenly distributed angularly about said die blank axis.

7. A wiredrawing die as claimed in any one of claims 3 to 6, wherein said base plate is provided with an annular recess for receiving the base of said die blank.

8. A wiredrawing die as claimed in any one of claims 3 to 7, wherein the number of projecting clamps is two, three, four, five, six, seven, eight, up to and including twelve.

9. A wiredrawing die as claimed in any one of claims 3 to 8, wherein the transition from said base plate to said clip projecting from said base plate is radiused.

10. The wiredrawing die of any one of claims 3 to 9, wherein said clamp protruding from said base plate extends at least two-thirds of the axial length of said die blank outside said base plate.

11. A wiredrawing die as claimed in any one of claims 3 to 10, wherein the circumferential thickness of the projecting clip decreases radially towards the die blank axis.

12. A blank holder for holding a blank of a wire drawing die,

it is characterized in that the preparation method is characterized in that,

the blank holder has a base plate with a clamp protruding therefrom, the clamp and the base plate being unitary, the base plate having a through hole at a center of the base plate.

13. The die blank holder of claim 12, having an axis of symmetry passing through the through hole and perpendicular to the base plate, and wherein the projecting clips are evenly distributed angularly about the axis of symmetry.

14. The die blank holder according to claim 12 or 13, wherein the base plate is a ring.

15. The die blank holder according to any one of claims 12 to 14 wherein the number of projecting clips is two, three, four, five, six, seven, eight up to and including twelve.

16. The die blank holder according to any one of claims 12 to 15, wherein the transition from the base plate to the clamp protruding from the base plate is rounded.

17. A method of clamping a die blank in a die blank holder to form a drawing die according to any one of claims 3 to 10, the method comprising the steps of:

-providing a blank holder according to any one of claims 12 to 16;

-providing a mould base;

-applying a force at the center of the substrate while maintaining the outer edge of the substrate;

-partially inserting the mould blank between the protruding clamps;

-pressing the blank completely into the blank holder.

18. A method of manufacturing a die blank holder according to any one of claims 12 to 16,

-providing a mixture of a binder comprising metal powder;

-injection moulding the mixture into a casting mould, the cavity of which has the shape of the blank holder, thereby forming a new blank holder;

-removing the new blank holder from the casting mould;

-debonding said adhesive from said new blank holder, thereby forming a baked blank holder;

-sintering the fired mold blank holder to a maximum densification;

-cooling the sintered mould blank holder, thereby obtaining a finished mould blank holder.

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