Hot press tool

Abstract

A hot press tool for use in a hot press process is formed of at least one material selected from a group consisting of materials characterized by formula Mn+1AXn, wherein

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a hot press tool for producing workpieces by a hot process and formed of at least two elements.

[0003] 2. Description of the Prior Art

[0004] In the hot press process, workpieces are produced of a basic powder material by using a powder metallurgical process, with formation of the workpieces with hot press tools under high pressure and high temperature. Among the workpieces produced with the hot press process are, e.g., abrasive segments for annular bits.

[0005] The hot press tools, which are used in the hot press process, are usually formed of graphite and hard metal. A drawback of the conventional hot press tools formed of graphite is their low wear-resistance and fracture-resistance. They also have a low oxidation resistance at high temperatures. The drawbacks of the hot press tools formed of hard metals consist in their large weight, their difficult machinability, and their limited temperature and oxidation resistance. Because of their low or limited oxidation resistance, the hot press tools are used under an inert atmosphere.

[0006] Accordingly, an object of the present invention is to provide a hot press tool that can be economically used under natural atmospheric conditions.

[0007] Another object of the present invention, is a hot press tool having a high wear-resistance and which is easily machinable.

SUMMARY OF THE INVENTION

[0008] These and other objects of the present invention, which will become apparent hereinafter, are achieved by forming a hot press tool of at least one material selected from a group consisting of materials characterized by formula Mn+1AXn, wherein

[0009] M is an element selected from the group consisting of Sc, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W;

[0010] A is an element selected from the group consisting of Al, Si, P, S, Ga, Ge, As, Cd, In, Sn, Tl, and Pb; and

[0011] X is an element selected from the group consisting of C and N.

[0012] The compound Mn+1AXn and its production in laboratory amounts are known since 1967. The variable n preferably amounts from 1 to 3. U.S. Pat. No. 5,942,455 discloses production of this compound in bulk amounts.

[0013] The materials of the compound Mn+1AXn are ceramic materials and, as such, have mechanical characteristics which do not depend on temperatures. The hot press tools, which are produced from a compound Mn+1AXn have a high wear-resistant and are easily machinable. The high oxidation resistance of the hot press tools, which are produced from compounds Mn+1AXn, at high temperatures permits to use the tools produced from these materials under natural atmospheric conditions. Moreover, by selecting appropriate elements and the variable n, the hot press tools, which are produced from the compound Mn+1AXn can be formed with an electrical conductance similar to that of hard metal.

[0014] The hot press tools are produced from powder materials by using a powder metallurgical process in per se known manner with a desired shape. The hot press tools can, e.g., be produced with a final shape and dimensions, i.e., be “net shaped.” Alternatively, the hot press tools, which are produced from a compound Mn+1AXn, can be produced in a basic form and be brought into a final form by subsequent processing. The hot press tools in a basic form can be then subjected to electroerosion machining, grinding, drilling, sawing, etc.

[0015] The selection of the elements and the value of the stochiometric coefficient of a compound Mn+1AXn is based essentially on the preferable characteristics of the hot press tool.

[0016] Advantageously, from the group M, Ti is selected, from the group A, SI is selected, and from the group X, C is selected, which with a preferable variable n=2, permits to obtain a compound Ti3SIC2. The hot press tool produced from this compound is characterized by a particularly good mechanical characteristic.

[0017] Hot press tools with a particularly good oxidation resistance are obtained when from the group M, Ti is selected, from the group A, Al is selected, from group X, C is selected and n=1, which provides a material Ti2AlC.

[0018] Hot press tools with a high electrical resistance are obtained when from the group M, Ti is selected, from the group A, Al is selected, and from the group X, N is selected and n=3, i.e., the hot press tools are produced from Ti4AlN3.

[0019] Advantageously, a hot press tool is essentially entirely produced from a material selected from a group of materials Mn+1AXn. However, a hot press tool can be produced only partially from the compound Mn+1AXn. When several materials are used for producing a hot press tool, the material, which is selected from the group Mn+1AXn, forms the outer surface or layer of the tool and constitutes a percentage volume of the entire amount of materials.

[0020] Preferably, in hot press tool, the outer layer is formed of the compound Mn+1AXn which is applied to a base body. The base body can be formed, e.g., of a hard material on which a layer of a compound Mn+1AXn having an adequate thickness is deposited. The thickness of the outer layer is determined by the required characteristics and by existing conditions during the use of the hot press tool. With such a hot press tool, after the wear of the outer layer, a new layer can be deposited on the base body. Thus, the based body can be used many times.

[0021] Advantageously, the hot press tool is formed as a punch and/or sleeve. The sleeve can be formed with a bottom, whereby a pot-shaped member is produced. Also, other components of a hot press frame, such as, e.g., dies, separation walls, pins, cores, screws, etc., can be produced from a material selected from the group of materials Mn+1AXn.

[0022] The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of the preferred embodiments, when read with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings show:

[0024] FIG. 1 a schematic cross-sectional view of a hot press frame with a hot press tool according to the present invention;

[0025] FIG. 2 a perspective view of the punch shown in FIG. 1;

[0026] FIG. 3 a perspective view of the sleeve shown in FIG. 1;

[0027] FIG. 4 a perspective view of another embodiment of a punch according to the present invention; and

[0028] FIG. 5 a perspective view of another embodiment of a hot press tool according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0029] As discussed above, FIG. 1 shows schematically a partial cross-sectional view of a hot press frame 1 with a hot press tool according to the present invention. The hot press frame 1 includes a die 2 with a plurality of recesses 3 (only one recess 3 is shown in the drawing). The hot press tool according to the present invention is formed of three parts, a sleeve 4 which is located in the recess 3 and serves as a first hot press tool, a punch 5 which serves as a second press tool, and a bottom member 8 which is likewise located in the recess and which serves as a third hot press tool. With the formation of the hot press tool of three parts, a produced workpiece 6 is completely surrounded by hot press tools forming the hot press tool according to the present invention. This permits to produce the workpiece 6 under natural atmospheric conditions. According to an embodiment of the invention, the sleeve 4 can be formed integrally with the bottom member 8 as a pot-shaped member.

[0030] A workpiece 6, which is produced by the hot press process, can be, e.g., preliminary formed as a powered mold, as a cold-pressed workpiece, or as a sintered part and then placed in the sleeve 4. The punch 5 is displaced in the direction shown with arrow 7 towards the die 2 with a high pressure and at a high temperature until the workpiece 6 is sufficiently compressed. Essentially, for producing the workpiece 6, a powder metallurgical process is used. When the die 2 is formed of a material selected from a group of material Mn+1AXn, the arrangement of the sleeve 4 in the recess 3 can be dispensed with, so that the punch 5 would slide directly along the inner surface of the recess 3.

[0031] The punch 5, the sleeve 4 and, if necessary, the die 2 are produced by using a powder metallurgical process of a material selected from a group of a material characterized as it has already been discussed above, by formula Mn+1AXn. The elements of the hot press tool preferably are produced in a final form. However, the elements of the hot press tool can first be produced in a basic form and then be formed into a final form by using further processing steps, such as cutting, grinding, etc.

[0032] The punch 5, a perspective view of which is shown in FIG. 2, is formed as a circular cylinder the outer dimensions of which correspond to the inner dimensions of the sleeve 4 or to the inner dimensions of the recess 3. In order to insure a high resistance to oxidation and good characteristics at high temperatures and good wear-resistance, the punch 5 is produced, as discussed above, from a material selected from a group of materials Mn+1AXn.

[0033] FIG. 3 shows, as discussed above, a perspective view of the sleeve 4. The sleeve 4 has a tubular shape and has its dimensions adapted to the outer dimension of the punch 5 and the inner dimension of the recess 3. To insure the performance capability of the sleeve 4 as a hot press tool in the hot press frame, the sleeve 4, as the punch 5, is formed of a material selected from the group of materials Mn+1AXn.

[0034] FIG. 4 shows another embodiment of the punch. The punch 11 has a cylindrical basic body 12 provided with an outer layer 13 formed of a material selected from the group of materials Mn+1AXn. The basic body can be formed, e.g., of a hard material.

[0035] A further embodiment of a combination hot press tool according to the present invention is shown in FIG. 5. The tool has wall sections 21.1 and 21.2 which as spaced from each other by separation walls 22.1 and 22.2. A square-shaped punch (not shown) is introduced into space 23 defined by the spaced from each other, separation walls 22.1 and 22.2.

[0036] The elements of the combination hot press tool are characterized by their high mechanical characteristics and by flexibility of their formation. It is to be noted that hot press tool having specific shapes can be economically produced. The hot press tool elements can be connected with, e.g., screws which are likewise produced of a material selected from the group of materials Mn+1AXn.

[0037] Examples of the materials of the group of materials Mn+1Xn are compounds TiSiC2, Ti2AlC, Ti4AlN3.

[0038] Though the present invention was shown and described with references to the preferred embodiments, such are merely illustrative of the present invention and are not to be construed as a limitation thereof and various modifications of the present invention will be apparent to those skilled in the art. It is therefore not intended that the present invention be limited to the disclosed embodiments or details thereof, and the present invention includes all variations and/or alternative of the present invention as defined by the

Claims

1. A hot press tool for producing workpieces by a hot press process, wherein the hot press tool is formed of at least one material selected from a group consisting of materials characterized by formula Mn+1AXn, wherein

M is an element selected from the group consisting of Sc, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W;

A is an element selected from the group consisting of Al, Si, P, S, Ga, Ge, As, Cd, In, Sn, Tl, and Pb; and

X is an element selected from the group consisting of C and N.

2. A hot press tool according to claim 1, wherein the selected material is Ti3SiC2.

3. A hot press tool according to claim 1, wherein the selected material is Ti2AlC.

4. A hot press tool according to claim 1, wherein the selected material is Ti4AlN3.

5. A hot press tool according to claim 1, wherein the at least one material forms an outer layer (13) of the tool deposited on a base body (12).

6. A hot press tool according to claim 1, comprising at least one of a punch (5), (1) and a sleeve (4).