JPH0351353A - Preparation of three dimensional structure consisting of uniformly- needled fibrous material - Google Patents

Abstract

PURPOSE: To obtain a homogeneously needled three-dimensional structure excellent in heat resistance and suitable for high-performance brake elements, rocket motor parts, etc., by superimposing intermediate textile elements subjected to napping and successively needling the superimposed elements. CONSTITUTION: Warp yarns 12 and weft yarns 13 each comprising multifilament yarns such as polyacrylonitrile are woven into fabric 11 and the surface of the fabric 11 is subjected to raising operation so as to create a nap 14 to provide intermediate textile elements. The intermediate textile elements are superimposed and laminated and subjected to needling treatment so that the depth of needling is changed so as to become successively shallow to provide the objective structure.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to highly uniform needled structures used as reinforcements to form high-performance brake elements, rocket motor components, and other heat-resistant structures. The present invention relates to a method for producing the same, and in particular to an intermediate woven unit for forming such a reinforcing structure.

Brake discs used in the brake systems of high-speed vehicles, such as racing cars and aircraft, are subjected to extremely high braking loads and must be able to withstand these loads reliably.

In particular, the brake disc must have physical properties that allow it to withstand the high stresses brought about in such cases.

(Prior Art) A method for manufacturing three-dimensional structures of fibrous materials for use as reinforcement in composite materials is disclosed in U.S. Pat.
9 (described in the specification of No. 1052).

This involves stacking and individually needling fibrous sheets.

The homogeneity required for the three-dimensional structure forming the reinforcement body must be such that the needling process that binds and integrates the individual layers has a constant effect on each successive layer that makes up the structure. The aforementioned US Pat. No. 479 (1052) discloses a special method for achieving this objective.

Similarly, the uniformity of the needling process is important to provide the required homogeneity of the three-dimensional structure, and it is also important to use fiber sheets that are very similar to each other in terms of physical properties.

The layers used to form the three-dimensional structure are: - In boat fishing, a cursed or wrapped fibrous web of continuous yarn or tow is bonded to a woven layer; lacks homogeneity in its nature. Therefore, it has been difficult to achieve desirable homogeneity of the three-dimensional structure.

It is therefore an object of the present invention to provide an improved form of fibrous sheet for forming the above-mentioned reinforcing structure.

SUMMARY OF THE INVENTION According to the present invention, there is provided a method for forming a uniformly reinforced structure formed by sequential needling of successive overlapping intermediate woven units. Provided is a method characterized in that at least one side of the unit bodies constituting the densely woven structure is fluffed.

Preferably, such a dense structure is a woven structure,
For example, a needled fibrous web may be used, optionally incorporated with a laminate fabric, or reinforced with parallel spaced rows of fibers unwound from a reel. .

The present invention is also directed to an intermediate woven unit formed from fibers that are precursors of carbon fibers or ceramic fibers, and which has one surface subjected to a napping treatment. This forms the woven structure described above.

(Structure of the Invention) The present invention will be described in more detail with reference to the accompanying drawings illustrating embodiments.

First, in FIG. 1, a woven body 11, in particular a twill weave fabric, is shown consisting of warp threads 12 and weft threads 13 made of multifilaments of P, A, N, yarns (polyacrylonitrile, a precursor of carbon fibers). There is.

The woven body is subjected to a conventional napping process on both sides (only one side is shown) to form a nap 14. The degree of fluffing is determined by the amount of fluff required.

Due to the regular nature of the woven body, the density of the fluff is essentially uniform and can be easily reproducible.

The fluffed woven material shown in Figure 1 is assembled into a laminate in successive layers and then needled to provide uniformity throughout its thickness to achieve the desired thickness. Used to construct homogeneous structures. This process is schematically illustrated in FIGS. 2A-2C as disclosed in U.S. Pat. No. 479 (1052). FIG. The vertically movable needle 23 carried by the needle bar 24 indicates that the lowermost layer of the stack is no longer being subjected to the needling process, and the needle is in the lowermost piercing position. FIG. 2C shows the platen 22 as the laminate is gradually formed.
is gradually lowered, and the needling process is limited only to the upper region of the laminate. In the early stages of stack formation, the needle passes completely through the stack and its tip engages a slot 26 drilled in the platen. However, as stack formation progresses, the platen is lowered relative to the lower dead center of the needle stroke. The needling process continues until the desired thickness of the laminate is reached. The top layer 27A of the stack is subjected to the same degree of needling as the bottom layer 27B and middle layer 27C, while the platen is gradually lowered.

The thus needled woven material is subjected to a conventional singulation treatment (conversion of P, A, N, before oxidation to carbon), followed by a conventional densification treatment in which chemical vapor is infiltrated into the luminescent carbon. Attached to processing. The resulting material is suitable for use as a brake pad under extremely high loads. The regularity of the fluff formed in each layer provides a high degree of homogeneity to the brake pad, giving it strength and stress load resistance.

The fluff itself is subjected to a high temperature calendering process or extended outwardly and orthogonally to the woven structure before the next woven structure is superimposed on the laminate formed on the needling device. It is processed so that it remains in the same condition as it is, so it is flattened. The latter condition is preferred in that it provides a uniform height of fluff on the fluffed surface.

By selecting an appropriate twill weave, it is possible to form a fluffed patterned surface with regular fluffed and non-fluffed areas. This uneven portion allows woven bodies having similar fluff patterns to be superimposed in a complementary manner so that their relative positions do not shift. The fuzzy portion and the non-fuzzy portion are formed complementary to each other in each woven body. In this way there is a degree of natural interlocking between the successive layers, which contributes to the shear strength of the final product.

Furthermore, the use of a weft satin weave and irregularly napped surfaces can be readily used to provide woven layers with different degrees of nuff on each surface.

Of course, due to the wide range of different weave structures,
Correspondingly, a variety of fluffed structures can be provided, and any desired degree or distribution of fluff, or combinations thereof, can be formed. For example, a broken twill weave with a large number of weft yarns, especially a twill weave with a plurality of weft yarns woven together, results in a woven body with a high degree of fuzz on both sides.

In the case of pure or nearly pure carbon fibers, it results in a multi-layered structure, and the woven surface is not affected, regardless of the fragility of the carbon fibers or the damage caused to the fibers on the woven surface by the straddling process. Preferably, weaving methods are used in which the napping does not have an adverse effect on layers remote from this surface. A typical weave pattern for a woven body woven from pure or nearly pure carbon fibers is shown in FIG.

Of course, other weaving patterns will readily occur to those skilled in the art.

In the above, the present invention has been described in which the surface of the woven body is fluffed, layers of this type of woven body are laminated, and the layers are integrated by a needling process. It is also possible to use a fabric in which a cursed fiber strip is inserted between the fluffed woven fabric layers and integrated with a fiber fixing machine.

The invention is not to be limited to the details of the specific embodiments described above. Various modifications of the above-described embodiments will be readily available to those skilled in the art. For example, the mutual weights of the warp and weft may be different, and after the fluffing, the weft and warp weights can be made equal, and the initially excessive amount of yarn can be made into fluff or reinforcing yarn.

Although referred to as a woven material for convenience, methods other than weaving may be used, such as a needle-pierced fiber web of 5 (10 g/m2) with a fluffed surface for bonding. Needle-pierced webs include woven bodies interposed between fibrous webs, or simply spaced parallel threads.

The basic objective of the present invention is to provide a uniformly reinforced structure that can withstand large mechanical forces at high temperatures.
The fibers may be carbon fibers or ceramic fibers (or precursor fibers until converted thereto), or a combination thereof. Since the purpose of the present invention is to provide a uniform reinforced structure, the fibers or their precursors may be natural fibers, artificial or synthetic fibers, or a combination thereof. .

[Brief explanation of drawings]

FIG. 1 is a perspective view of a woven article according to the invention having a partially brushed surface; FIG. 2 shows a method of forming a woven laminate and needling it to produce a homogeneous structure. Schematic diagram: Figure 3 shows a weaving pattern suitable for use with pure carbon fiber. 11... Twill weave woven body, 12... Warp, 13...
Weft, 14...Fluff, 21...Laminated body, 22...
Platen, 23...needle.

Claims (15)

[Claims] (1) In the method for forming the unit used to manufacture a uniformly reinforced structure formed by sequentially needling intermediate woven units, the densely woven structure is A method characterized in that at least one side of the above-mentioned constituent units is subjected to a napping treatment. (2) Each layer of the densely woven structure is successively stacked to form a sequentially needled laminate of similar structure, and each successive layer is needled uniformly through the entire thickness of the laminate. to construct a laminate of desired thickness,
A method for producing a uniformly reinforced structure, characterized in that at least one side of the densely woven structure is subjected to a napping treatment before forming the laminate. (3) The method according to claim (1) or (2), characterized in that both sides of the densely woven structure are subjected to a napping treatment. (4) The method of claim (3), characterized in that each surface of the densely woven structure is selectively subjected to a napping treatment, resulting in a napped portion and a non-fussy portion. How to do it. (5) The method according to claim (4), characterized in that on both sides of the densely woven structure, the raised portions and the unfurled portions are arranged and formed so as to complement each other. (6) In the method of claim (2) or any one of (3) to (5), the densely woven structure is formed from carbon fibers, ceramic fibers, or their precursor fibers, and has a high density. A method including a step of oxidation. (7) An intermediate woven unit used for manufacturing a uniformly reinforced structure formed by sequentially needling intermediate woven units, in which at least one side is A unit body characterized in that it has a densely woven structure which has been previously subjected to a napping treatment. (8) The intermediate woven unit according to claim 7, wherein both sides of the densely woven structure are fluffed. (9) The intermediate woven unit according to claim (8), characterized in that each surface of the structure is selectively fluffed to form a fluffed portion and a fluff-free portion. unit body. (10) The intermediate woven unit according to claim (9), characterized in that fluffed portions and non-fluffed portions are arranged complementary to each other on both sides of the densely woven structure. unit body. (11) An intermediate woven unit according to any one of claims (7) to (10), characterized in that the structure is made of a woven fabric. (12) An intermediate woven unit according to claim (11), characterized in that the structure consists of a punched laminate of two woven fabrics and a fiber batt inserted between them. body. (13) An intermediate woven unit according to any one of claims (7) to (12), characterized in that the structure is formed from carbon fibers, ceramic fibers, or their precursor fibers. body. (14) The intermediate woven unit according to claim (13), characterized in that the structure is a multilayer woven body. (15) An aggregate of intermediate woven units according to any one of claims (7) to (14), in which the structures are overlapped in a superimposed position and needled to form a uniform three-dimensional reinforced woven fabric. An aggregate characterized by bringing about.