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(11) | EP 0 228 079 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | A method for manufacturing a fiber reinforced metal |
| (57) A method for manufacturing a fiber reinforced metal which comprises arranging fiber
reinforced metal composite wire rods in one direction, heating the thus arranged wire
rods to a temperature which is at least 200°C and is not higher than melting point
of the to-be-reinforced metal contained in the wire rods and then roll forming the
thus heated wire rods. |
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] This invention relates to a method for manufacturing a fiber reinforced metal in the sheet or tape form or in the rod form such as a round or square bar by roll forming a fiber reinforced metal composite wire rod.
2. Prior Art
[0002] Conventional fiber reinforced metals have been manufactured by coating reinforcing fibers by means of CVD, PVD, ion plating or the like or by applying plasma spray to untreated (not treated yet) fibers and then roll forming the thus sprayed fibers.
[0003] These conventional methods have raised the following problems.
(1) If untreated fibers is subjected to pretreatment, then the fibers will suffer damage and the fibers so pretreated will decrease in strength;
(2) Forming conditions such as forming temperatures and pressures, are required to be strict or severe ones since there are used materials which have not completely composited, and, in addition, vacuum or an inert gas atmosphere is needed to improve the resulting product in properties; and
(3) Conventional preforms are insufficient in permeation of a matrix metal between the fibers of the preforms, and, therefore, they will produce a FRM having low strength because of its inner defects even if they are roll formed.
SUMMARY OF THE INVENTION
[0004] An object of this invention is to provide a method which eliminates the above disadvantages of the conventional methods.
[0005] This object may be achieved by using a fiber reinforced metal composite wire rod, preheating the wire road and then roll forming the thus preheated wire rod.
[0006] The reinforcing materials used in the fiber reinforced metal composite wire rods which are used in this invention, include silicon carbide fibers, carbon fibers, boron fibers, alumina (Al₂O₃) fibers, metal fibers such as stainless steel, molybdenum (Mo) and tantalum (Ta), and preforms thereof such as silicon carbide/Al wires, C/Al wires and Al₂O₃/Al wires. The matrix metals used in said fiber reinforced metal composite wire rods, include aluminum (Al), magnesium (Mg), silicon (Si), titanium (Ti), lead (Pb), copper (Cu) and alloys thereof. Such fiber reinforced metal composite wire rods may be produced from such reinforcing materials and such matrix metals by a known method.
[0007] In the method of this invention, the fiber reinforced metal composite wire rods are provided in an amount which is determined depending on desired products to be obtained, arranged in one direction, preheating the wire rods, preferably in a furnace, to a temperature in the range of from at least 200°C to the melting point of a matrix metal which is the metal to be reinforced in said wire rods, and then subjected to roll forming. The roll forming may be effected by passing at a rolling pressure of at least 200 kg/cm² the preheated wire rods through rolls heated to a temperature which is usually in the range of ambient temperature to 500°C and at which the to-be-reinforced metal does not fusion bonded to the rolls. This roll forming may be carried out batchwise or continuously.
[0008] This invention will be better understood by reference to the accompanying drawing in which:
Fig. 1 is a schematic view showing a method for carrying out this invention using continuous roll forming; and
Fig. 2 is a schematic view showing a method for carrying out this invention using batchwise roll forming.
[0009] In Fig. 1, fiber reinforced metal composite wire rods 2 are withdrawn from supply creels 1 and passed through an arranging guide 3-1 to a preheating furnace 4 where the wire rods are heated to a predetermined temperature within said temperature range. The wire rods so heated is further passed through another arranging guide 3-2 and an arranging jig 5 to a rolling mill 6 heated to a predetermined temperature within said temperature range where the wire rods are roll formed to obtain a sheet 7 which is then wound on a take-up reel 8. If necessary, the sheet 7 is cut by a cutter 9 into pieces of a desired size which are then placed on a sheet table 10.
[0010] In Fig. 2, the fiber reinforced metal composite wire rods 2 are, without being withdrawn from supply creels as indicated above, passed through an arranging guide 3-1 to a preheating furnace 4 where the wire rods are preheated, and then further passed through another arranging guide 3-2 and an arranging jig 5 to a rolling mill 6 where the wire rods are roll formed to obtain a sheet which is then placed on a sheet table 10. The roll formed product is a sheet in this case, but the wire rods can of course be roll formed into round or square bars in a manner similar to the above.
[0011] As mentioned above, the roll forming may be effected continuously or batchwise depending on the length of the wire rods, and the wire rods may be roll formed without or with the use of jigs and the like.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Example 1
[0013] There were provided fiber reinforced metal composite wire rods having an 0.5-mm diameter and a fiber volume ratio of 20% which were produced from Nicalon/-aluminum preformed wires as the reinforcing material and aluminum as the matrix metal. The wire rods so provided were treated by an apparatus using jigs as shown in Fig. 2 to obtain a tape-like fiber reinforced metal. Nicalon (NL) stands for silicon carbide fibers produced by Nippon Carbon Co., Ltd.
[0014] First of all, the wire rods were preheated to 400-500°C in a preheating furnace and then roll formed at a rolling pressure of 550-650 kg/cm² to obtain a tape-like fiber reinforced metal which was 10 mm wide and 150 mm long. The tape-like metal so obtained had a tensile strength of 60 kg/mm² which was at least 80% of that (70 mg/mm²) of the original wire rods.
Example 2
[0015] The procedure of Example 1 was followed except that Nicalon fibers were used as the reinforcing material, to obtain wire rods having an 0.5-mm diameter and a fiber volume ratio of 50%. The wire rods so obtained were subjected to roll forming without the use of jigs. More particularly, the wire rods were preheated to 400-500°C and then roll formed at a rolling pressure of 550-650 kg/cm² and a roll heating temperature of 100-200°C thereby to obtain a tape-like fiber reinforced metal having a width of 10 mm and a length of 300 mm. The tape-like metal so obtained had a tensile strength of 90 kg/mm² which was at least 80% of that (110 kg/mm²) of the original wire rods.
(Effects of this invention)
[0016] As has been so far described, a method for the manufacture of a fiber reinforced metal comprises subjecting fiber reinforced metal composite wire rods to roll forming under specific operational conditions. The effects of this invention obtained by the practice of the above method are as follows.
(1) The method of this invention can dispense with such pretreatment with plasma spray or the like as practiced in conventional methods since the wire rods can directly be roll formed and, in addition, it can produce fiber reinforced metals in a continuous tape-like or rod-like form;
(2) The present method can produce fiber reinforced metal moldings from the wire rods even in the air under milder conditions than conventional methods since the wire rods are a composite;
(3) The specific properties of the wire rods can fully be retained in the resulting fiber reinforced metals since not only the operational conditions are mild but also the pretreatment with plasma spray and the like is unnecessary, and the fiber reinforced metals have a higher tensile strength of 60-90 kg/mm², whereas those obtained by conventional rolling methods have a tensile strength of about 50 kg/mm²;
(4) A large mass (a starting material) is conventionally transferred or transformed to a small mass (a product obtained from the starting material) from the view-point of plastic working, while in the present method a small mass (a starting material) is transferred to a large mass (a product), this being to the contrary;
(5) Since there can be obtained fiber reinforced metals which are a composite prepared using the wire rods, there can also be obtained a composite containing at least two kinds of matrices; and
(6) The present method enables continuous forming and production of long moldings and may be widely used in manufacturing structural materials for automobiles, aircrafts, rockets, spacecrafts and the like and also in manufacturing sporting goods.
arranging fiber reinforced metal composite wire rods in one direction,
heating the thus arranged wire rods to a temperature which is at least 200°C and is not higher than the melting point of the to-be-reinforced metal contained in the wire rods and then
subjecting the thus heated wire rods to roll forming.