WO2006056621A2

WO2006056621A2 - Method of obtaining tools by means of concrete mould forging

Info

Publication number: WO2006056621A2
Application number: PCT/ES2004/000510
Authority: WO
Inventors: Isaac Valls Angles; Aniceto Valls Segura
Original assignee: Rovalma, S.A.
Priority date: 2004-11-16
Filing date: 2004-11-16
Publication date: 2006-06-01
Also published as: EP1892049A1

Description

TITLE:

OBTAINING USEFULS BY FORGING IN CONCRETE MOLD.

DESCRIPTION:

SUMMARY OF THE INVENTION:

The invention object of this application consists in the method of production (as well as the elements produced) by closed forging of molds, dies or any single piece or small series (always metal parts or compounds with metal base) using a mold of form constructed of concrete or mortar (especially concretes and mortars made of high-strength cements and / or refractories based on porcelain, aluminous, silicate, ... and with aggregates of basalt, silicon oxide, or other aggregate of those usually used in construction, or aggregates based on alumina or other refractory materials).

The main interest of the invention is focused on the drastic reduction of costs and time involved in being able to form metal parts of difficult geometry by closed forging. In the case of the present invention (obtaining molds, dies and small series pieces) it is essential that the production cost of the shape mold is not excessively high.

Another point of interest is the possibility of forming materials, metal based, very difficult to machine, or non-mechanizable, but on the other hand they have enough hot creep to be shaped by forging.

BACKGROUND AND SITUATION:

Plastic parts and metal parts are often obtained industrially through the use of molds and dies. This is usually the case when the number of pieces to produce is high since the construction of a mold or matrix is almost always very expensive, being able to justify this high cost, only when it can be distributed among many units produced.

Mold or matrix is considered to be any element shaped to form metal, polymer, ceramic, or composite parts. (The shape of the mold or matrix can be the negative of the piece to be obtained, as is the case of injection molds, pressing, drawing dies, bending, stamping or any other form of forming, they can also simply be a contoured profile as in the case of some cutting matrices). The mold or matrix can be used to obtain a single piece or more commonly to obtain hundreds to millions of pieces per repeated action, and often also, obtaining more than one piece at each stage of forming.

CLARIFICATION NOTE OF TERMINOLOGY: It is often understood as "forming" in the industrial sector of sheet metal stamping to a very specific operation consisting of deforming flat geometry sheet, until it acquires a certain shape (usually final piece), this can be done in one or more operations. In this document the term "forming" is used to designate any operation that forms a material in which a mold or matrix is used (Examples of operations designated by the term "forming": cutting, stamping, drawing, hot forging , cold forging, extrusion, pressure molding, gravity molding, thermoforming, pressing, blowing, ...).

CLARIFICATION NOTE OF TERMINOLOGY: In this document the denomination "form mold" is used to designate any container capable of shaping a metal part in a closed forging operation (Also commonly referred to as: forging stamps, forging molds, dies of forging or forging tools).

Depending on the application, three main types of molds or dies can be distinguished, the differences are found not only in the application but also in the type of materials used to build them and the process: 1.- Molds for forming polymers (thermoplastics and thermosets). [more typical forming operations in this case: injection, thermoforming, curing, blowing, thermostable pressing, ...].

2.- Molds and dies for hot work: Forming of any high temperature metal alloy, generally greater than 0.5 Tm and often with the alloy in a liquid state. [Forming operations more typical in this case: injection or hot pressing, extrusion, closed forging, drawing and hot stamping, ....].

3.- Matrices and molds for cold work: forming of metal alloys at temperatures below 0.5 Tm [more typical forming operations in this case: cutting, drawing, stamping, bending ...].

At present, two methods are mainly used to obtain molds and dies for the applications described above: Machining by chip removal and casting. Each method has advantages and disadvantages with respect to the other and is the option economically depending on the geometry and the number of pieces to obtain.

In machining by chip removal, a metal block is used (usually a forged block, or cut from a forged or laminated bar, but molten blocks are also used), obtaining the desired geometry by mechanically removing the excess material . If starting from forged material, the toughness is much higher than that of the same alloy obtained by casting which often translates into a longer life of the tool (NOTE: in this document the term useful is used to simultaneously designate molds and matrices). This option is generally used for the manufacture of long series where the profile of the piece to be obtained does not have very large differences in dimensions. Well, machining by chip removal is an expensive process and the greater the emptying, the more material becomes a chip and more hours are spent on it. In addition, the increase in toughness achieved by the process of forging or rolling is smaller the farther from the surface of the material with which the tool is constructed, thus in a deep emptying the part of the cavity of the finished die or mold, which is the part that works, has structure and properties practically of molten material. So that rarely is this method used for tools with differences in dimensions greater than 400mm with most mold and die building materials. It is the preferred method for long series, since the tools manufactured with this method are customary. to have greater durability. In fact, this method is in principle rocambolesque, since the molten material instead of sneaking directly to a geometry close to the desired one, sneaks into ingots, which are subsequently forged to turn them into billets that are again forged or rolled to obtain Forged blocks or bars, in the latter case the bars must be cut to the desired block size, and in both cases (forged block or bar cut) the block must be machined by chip removal or electro-erosion conferring the desired geometry . The subsequent processes of tempering, finishing machining, ... are common for both production methods.

Of all the processes for obtaining cast iron tools, the most commonly used is sand casting and polystyrene model, which is consumed during mold filling. Normally a preform is obtained, since the tool must be machined by chip removal, to achieve the dimensional tolerances that are required in the work area. The preform has a geometry very similar to the final one, which greatly reduces the amount of machining to be carried out and the resulting scrap material. With this method, cheaper molds and matrices are achieved (the difference is greater the greater the differences in dimensions and therefore the material to be removed if it is part of a forged block), but which generally last less. It is the preferred method when the series of parts to be manufactured are short or the differences in large dimensions.

The forge has been used for many years as a means of obtaining shaped pieces, a process that is generally called a "closed forge", since a mold of a shape or cavity must be used so that the piece to be obtained acquires the desired shape by the creep of the material filling and copying the shape of the cavity or shape mold. In this process, molds of metallic or technological ceramics are used to obtain several pieces with the same mold, to amortize the cost of said mold. In the present invention since the molds and dies are generally unique, and very exceptionally there are more than ten cavities or segments with the same geometry, the Mold cost has to be amortized in one or very few pieces. Thus the product produced, mold or matrix, has to have a cost clearly higher than the shape mold. This is also the case in obtaining molds and dies by casting in a sand-shaped mold. OBJECTIVE OF THE INVENTION:

With the process of the present invention, molds and dies are obtained as economically and as simply as is currently achieved with the foundry, but at the same time with durability qualities as good or even superior to those of the molds and dies obtained by the machining of forged or laminated blocks (often blocks cut from forged and / or laminated bars). The method allows the use of materials of difficult mechanization (even those considered "non-mechanizable") that greatly increase the hours of service and / or productivity of the tools or parts manufactured with these materials.

The present invention consists in providing a method of producing matrices, molds and single or short series pieces by forging in a mold form. The method consists in the construction of a mold so that it can withstand the temperature and mechanical stresses required for forging in a closed system of the material to be used for the construction of the mold or matrix (it is not important if the shape mold is destroyed during the forging process if it is possible to deform the material of the mold, matrix or piece), the mold being sufficiently economical so that its amount does not exceed the cost reduction with respect to the machining process. The optimization of the forging parameters to be used (especially temperature and deformation speed), as well as the geometry of the shape to be obtained, and the material with which the mold or matrix is to be constructed, have great influence on the solicitations to which the form mold is subjected, largely determining the potential materials for the construction of the form mold.

The materials used for the construction of the form mold have to be as economical as possible but with the thermal and mechanical properties required for the forging operation. Mortars and concrete are especially indicated: with cements high strength (based on porcelain, silica, ...), with refractory cements (based on alumina, aluminosilicates, ...), with basaltic aggregate, sand (SiO ₂ ), other refractory aggregates (based on alumina ,), or other aggregates commonly used in construction. Other mortars can also be used (based on: MgO, SiC, ZnO, Cr ₂ O ₃ , ZrO ₂ , B ₂ O ₃ , Al ₂ SiO ₅ , CeO ₂ , C ₂ Si ₃ , CaF ₂ , Silica, graphite, magnesite, silicates, linosulfonates, phosphates (boron, aluminum, ...))). Some of the aggregates mentioned above can also be used with a binder (for example aluminum phosphate).

The application of part of the invention in the production of die molds or castings is also a great advantage, since if molds of mortar or concrete form are used, the dimensional tolerances that can be achieved as well as the quality of the surface finish, They look remarkably increased.

The present invention also has a great advantage for obtaining finished parts or preforms (especially if it is a single piece or few units), especially if the material used to obtain the piece has a high cost or is difficult to mechanize . Some geometries are not possible to obtain economically in any other way in the case of very difficult machining materials such as metal or polymer matrix compounds with ceramic charge.

An important economic advantage is also provided in obtaining sintered parts with the use of concrete molds, especially if high strength concrete is used. In this process the material with which the mold, matrix or piece is to be obtained is introduced in powder form into the form mold and cold or hot pressing is performed to obtain the final geometry or preform pressed in green, something sintered or fully sintered with or without liquid phase.

Claims

CLAIMS:

PRELIMINARY NOTE: In all claims, where "mold or matrix is read by forging", it should also be understood to be obtained by forging in a mold of any form of preform that simplifies the machining for obtaining the final mold or matrix.

- 1) Process by which molds or dies are obtained by forging in a mold of concrete or mortar form. The materials used for the construction of molds or dies can be metals, metal alloys or "composites" with metal phase (either the matrix or any of the phases).

- 2) Process by which single or short series pieces are obtained by forging in a concrete or mortar shaped mold. The materials used for the construction of the pieces can be metals, metal alloys or "composites" with metal phase (either the matrix or any of the phases).

- 3) Any mold, matrix or piece produced by forging in a concrete or mortar shaped mold.

- 4) Claims 1 to 3 when the forging deformation process is carried out within the superplastic deformation regime, in preheated or tempered concrete or mortar form molds during the forging process.

- 5) Claims 1 to 4 when the form mold is placed inside a mechanical tensile strength strip superior to that of the concrete or mortar used for the construction of the form mold. (Also when the greater resistance is partly due to the temperature difference, especially if the suncho is cooled). - 6) Claims 1 to 5 when the form mold is made of high strength concrete or mortar (Rm> = 25MPa).

- 7) Claims 1 to 5 when the form mold is made of refractory concrete or mortar, with special mention of concretes or mortars made of cement with alumina content greater than 20%.

- 8) Claims 1 to 5 when the form mold is made of high strength refractory concrete or mortar (Rm> = 25MPa).

- 9) Claims 1 to 5 when the form mold is made of high strength refractory concrete or mortar (Rm> = 25MPa), with special mention of concretes or mortars made of cement with alumina content greater than 20%.

- 10) Claims 1 to 5 when the form mold is made of concrete or mortar where some of the aggregates used have an alumina content greater than 10%.

- 11) Claims 1 to 5 when the form mold is partly manufactured with some of the following materials: MgO, SiC, ZnO, Cr ₂ O ₃ , ZrO ₂ , B ₂ O ₃ , Al ₂ SiO ₅ , CeO ₂ , C ₂ Si ₃ , CaF ₂ , Silica, graphite, magnesite, silicates, linosulfonates, phosphates (boron, aluminum ...), porcelain, silica, alumina or aluminosilicates.

- 12) Claims 1 to 5 when the shape mold is partly made of some of the following materials: sand (with or without binder), granulate or powder of any refractory or basalt material.

-13) Claims 1 to 5 when the form mold is made of granules or powder of refractory material or any aggregate and any binder, not necessarily cementitious, is used, such as phosphate-based binder (with special mention of aluminum phosphate ). - 14) Claims 1 to 5 when the shape mold is made of any non-metallic material.

-15) Claims 1 to 14 when a thermal paint or coating is used on the shape mold. Thermal paint or coating is understood as any layer less than 5 mm thick with refractory characteristics, especially when the thermal emissivity is greater than that of the material used for the construction of the shape mold. Also paints or coatings that have greater resistance to working temperature. (Typical paints or coatings based on: SiO ₂ , BN, ZrO ₂ , YO ₂ , Al ₂ O ₃ , ...)

-16) Claims 1 to 15 when a metal strap is used to reduce the tensile stresses supported by the shape mold (the suncho can be cooled during the forging process to increase its tensile strength and / or to increase interference with the shape mold).

-17) Claims 1 to 16 when the shape mold is preheated before introducing the material to be forged.

-18) Claims 1 to 17 when the shape mold is heated to a temperature similar to that of the material for the manufacture of the mold, die or piece, also when the material is heated within the shape mold itself.

-19) Claims 1 to 18 when the shape mold is heated to minimize heat loss. Also when heat is added to the shape mold during the process of forming the mold, die or piece, either by radiating screens or cartridge resistors inserted in the shape mold itself, heating blankets or any other heating mechanism. - 20) Claims 1 to 19 when the forging deformation to obtain the mold, matrix or piece is applied within the superplastic deformation regime of the material used for the construction of the mold or matrix.

- 21) Claims 1 to 20 when the forging deformation to obtain the mold, matrix or piece is applied within the dynamic recrystallization regime of the material used for the construction of the mold or matrix.

- 22) Claims 1 to 21 when the forging deformation to obtain the mold, matrix or piece is applied within the dynamic restoration regime of the material used for the construction of the mold or matrix.

- 23) Claims 1 to 22 when a deformation speed greater than 0.1 s ^{"1 is used} in the forging process.

- 24) Claims 1 to 23 wherein the shape mold has been obtained from a machined model in an easily machined material (polymer, wood, light alloy).

- 25) Claims 1 to 23 wherein the shape mold has been obtained from a molten or injected model.

- 26) Claims 1 to 23 wherein the shape mold has been obtained from a high density expanded polystyrene model.

- 27) Claims 1 to 26 when the material used for the manufacture of the mold, matrix or piece is a metal or metal alloy.

- 28) Claims 1 to 26 when the material used for the manufacture of the mold, matrix or piece is a metal matrix compound. - 29) Claims 1 to 26 when the material used for the manufacture of the mold, matrix or piece is composed with polymeric hue.

- 30) Claims 1 to 26 when the material used to manufacture the mold, die or piece is a steel.

- 31) Claims 1 to 26 when the material used for the manufacture of the mold, die or piece is a tool steel.

- 32) Any mold, matrix or part produced by casting in a mold made of concrete or mortar.

- 33) Any mold, die or part produced by casting in a mold made of concrete or high-strength mortar (Rm> = 25MPa).

- 34) Any mold, matrix or piece produced by casting in a mold made of concrete or refractory mortar, with special mention of concrete or mortar made of cement with alumina content greater than 20%.

- 35) Any mold, matrix or part produced by casting in a mold made of concrete or high-strength refractory mortar (Rm> = 25MPa).

- 36) Any mold, matrix or part produced by casting in a mold made of concrete or high-strength refractory mortar (Rm> = 25MPa), with special mention of concretes or mortars made of cement with alumina content higher than twenty%.

- 37) Any mold, matrix or part produced by casting in a mold made of concrete or mortar where some of the aggregates used have an alumina content greater than 10%. -38) Process for obtaining matrix molds or parts using powder pressing in a concrete or mortar form mold. The material with which the mold, matrix or piece is to be obtained is introduced as powder into the form mold and cold or hot pressing is performed to obtain the final geometry or preform pressed in green, something sintered or sintered completely with or without liquid phase.

- 39) Any matrix mold or part obtained by the process described in claim 38.

-40) Claims 38 and 39 when the form mold is made of concrete or mortar where the cement and / or any of the aggregates used has an alumina content greater than 10%.

-41) Claim 38 and 39 when the shape mold is made of high strength concrete or mortar (concrete or high strength mortar is understood as one that has a mechanical strength greater than 40 MPa).