RU2607362C2 - Heat-resistant matrix for moulding articles from composite materials - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to moulding articles from composite materials. Heat-resistant matrix has inside one or several layers of electrically conducting material, connected to an electric power source, wherein electroconductive elements are also included in stiffness ribs of matrix.

EFFECT: higher strength of matrix, as well as preventing its warpage during heating.

1 cl

Description

The invention relates to dies and punches for molding products from composite materials.

Such matrices are known, see, for example, US Pat. No. SU 550213, which are made of composite material and in which products are molded at room temperature. However, some synthetic resins have better hot curing strength.

The objective and technical result of the invention is to improve the mechanical characteristics of products from composite materials obtained in matrices.

For this, the matrix implements the technology of hot curing (hot binder polymerization).

The matrix with the molded product can be heated by air in a heat chamber, in particular, by the autoclave method. However, for faster and more uniform heating of the matrix, eliminating its warping or cracking, inside it there is one or more layers of electrically conductive material connected to an electric source, and the conductors are bent or branched so as to provide approximately the same heat release per unit volume of the matrix, and for this conductors with lower electrical resistance are used (simply put, wires).

The electrically conductive material can be often used nichrome, a wire or stainless steel mesh, carbon fiber itself and other materials suitable for this.

For a more uniform distribution of heat from the internal conductors to the product, the matrix has a layer of a mixture of cement with copper, or bronze, or aluminum powder, or stainless steel powder between the electrically conductive layer and the working surface. It is desirable that the coefficient of thermal expansion of the electrically conductive layer and this heat-distributing layer be close to the coefficient of thermal expansion of cement or concrete (for reference: concrete - 10-14, nichrome - 14, copper - 17, bronze - 13-21, aluminum - 2.4 , duralumin - 23, steel - 10-17).

To increase strength with limited weight, the matrix can have stiffeners in the direction of smaller size, and stiffeners located on the stiffeners mentioned above (i.e., with greater construction height) in the direction of the larger size. Moreover, to eliminate warpage of the matrix, the electrically conductive elements can also be in stiffeners, especially in the external ones.

Example: the matrix has in its volume a branched network of nichrome conductors (nichrome is closest in thermal expansion coefficient to concrete), in some places connected by simple wires (to reduce heat generation in this area). Between this layer and the working surface there is a layer with copper filings (copper is also close in thermal expansion to concrete).

The matrix works as follows: a composite material blank is placed in it, after which electricity is connected and an autoclave process follows, which gives the highest quality of the composite material obtained.

Claims (2)

1. Heat-resistant matrix for molding articles made of composite materials, having inside one or more layers of an electrically conductive material connected to an electricity source, characterized in that the electrically conductive elements are also present in the stiffening ribs of the matrix. 2. The matrix according to claim 1, characterized in that it has stiffening ribs in the direction of smaller size, and has stiffening ribs located on said stiffening ribs in the direction of larger size.