RU2801427C1 - Carbon composite threaded connecting element based on 3d solid-woven preform - Google Patents

Abstract

FIELD: connecting elements.

SUBSTANCE: present invention relates to a composite threaded connecting element and can be used in mechanical engineering, the manufacture of satellites and spacecraft, the railway and aviation industries, mining, shipbuilding and other industries for connecting and fixing structural elements. Carbon composite threaded connecting element in the form of a rod with an external thread reinforced with reinforcing carbon continuous threads located in three directions at once, connecting the threads to the central power rod, made of a polymer matrix reinforced with continuous carbon threads, which is an epoxy resin for creating a polymer composite material. The composite is made on the basis of a three-dimensional solid-woven 3D preform using an orthogonal weave in such a way that the transition from the rod to the cylindrical head is made with a change in the reinforcement structure so that the warp threads, which are located rectilinearly in the longitudinal direction of the rod, change the trajectory and form an angle to its axis, that is, they envelop the walls of a cylindrical head on which a structural element for transmitting torque is located.

EFFECT: increased structural integrity of the polymer composite, increased reliability, increased impact and load resistance, increased impact strength.

1 cl, 6 dwg

Description

The present invention relates to a composite threaded connecting element, and can be used in mechanical engineering, the production of satellites and spacecraft, the railway and aviation industries, mining, shipbuilding and other industries for connecting and fixing structural elements. The connecting element has the form of a rod with an external thread at one end and a structural element for transmitting torque at the other, made of a carbon fiber-reinforced polymer material, and the volumetric reinforcement extends in three axial directions. Contains a solid threaded thread on the outer surface.

In particular, the present invention relates to a carbon fiber reinforced propeller with increased strength provided by volumetric orthogonal reinforcement.

The screw contains a matrix material and reinforcement with continuous carbon threads, while the solid-woven volumetric reinforcement runs in three axial directions at once.

The matrix according to this utility model preferably consists of curable synthetic resins: epoxy, phenol-formaldehyde, not subject to carbonization. Another suitable matrix forming material is carbon, for example, to create a carbon-carbon composite material.

The screws realizing this utility model are not limited to any particular shapes and thread pitches.

Metal screws are widely known in the prior art. Currently, metal screws are used as fasteners in a wide variety of areas, in particular in aggressive environments, in chemical plants or water treatment plants, but there are a number of serious problems that arise during their operation. For example, it can be noted that metal screws are unsuitable for use in marine structures: boats, artificial reef structures, since constant contact with sea water leads to corrosion and rust, and consequently to the destruction of structures.

Known threaded connecting elements made of composite materials, obtained by layer-by-layer laying out of reinforcing fabrics, to obtain a given thickness of the product.

Composite materials, including those made of carbon fiber, have the advantages of light weight, high specific strength, strong fatigue, corrosion and insulation resistance, thermal insulation, non-magnetic, decorative properties, and inertness to chemicals compared to metal ones.

However, previously composite male connectors have not met reliability requirements due to their low shear resistance under axial loads. In addition, the production of such connecting elements was unprofitable due to the complexity of threading with its additional profiling in special forms.

In the prior art, a fibre-reinforced plastic element with an external thread is known, containing a rod consisting of a plurality of yarns impregnated with a thermosetting resin, said yarn tapes being fabrics created by interweaving two systems of threads, woven in the form of tapes. The external thread on the rod can be made threaded (US patent No. 4623290, IPC B29C70 / 22; B29C70 / 52; B29D1 / 00; F16B33 / 00; F16B21 / 00, publ. 1986-11-18, Patentee "ASAHI CHEMICAL IND" [ JP], "Fiber Reinforced Plastic Element with Male Thread and Method for Making the Same").

In the proposed element, a pultrusion rod is used as its basis, made of a composite based on thermoplastic or thermosetting resin, organic or inorganic fiber, unsuitable for direct threading on it.

The disadvantage of this technical solution is the possibility of delamination of the material, since a polymer composite on a woven basis is created by superimposing layers of fabric made using traditional 2D weaving technology, bonded only with a polymer binder. In service, this male prepreg-pressed element is subject to interlaminar shear stress, which causes the composite layers to separate under load.

The closest to the claimed technical solution is a solid composite bolt made of continuous carbon fiber as a reinforcement material and imidazole epoxy resin as a matrix for the manufacture of prepregs, formed by curing them (CN patent No. 111621119, IPC C08J5 / 24; C08K7 / 06; C08L63/00; F16B33/00; F16B35/00, Published 2020-09-04, Applicant HARBIN INST TECHNOLOGY, "Carbon Fiber Composite Solid Bolt").

The disadvantage of this technical solution is the low manufacturability when laying prepregs manually, since to obtain a workpiece it is necessary to lay out a large number of layers of reinforcing fabric in one direction. Difficulties may also arise when cutting a thread on a workpiece: layer breaks, manufacturing inaccuracies, as a result of which such samples have a relatively low margin of safety and reliability, which can lead to delamination of the material during operation.

The technical problem to be solved by the claimed utility model is the development of a reliable, lightweight design of a composite connecting element with an external thread, increased shear and shear strength, by creating a special 3D reinforcement structure that reinforces the thread and prevents pulling out of the threads of the base of the rod from the cylindrical head and thereby enabling the insertion of the element for transmitting torque.

This problem is solved due to the fact that the claimed composite threaded connecting element, in the form of a rod with an external thread at one end and a structural element for transmitting torque at the other, is made of a polymer matrix reinforced with continuous carbon filaments, which is an epoxy resin, to create a polymer composite material, based on a three-dimensional solid-woven 3D preform using an orthogonal weave. Moreover, the transition from the rod to the cylindrical head is made with a change in the reinforcement structure, as a result of which the warp threads, located rectilinearly in the longitudinal direction of the rod, change the trajectory and form an angle to its axis, that is, they go around the walls of the cylindrical head, which further increases the strength of the product by eliminating the possibility of pulling out the threads and the introduction of an element for transmitting torque.

The external threaded thread is reinforced with reinforcing carbon continuous threads located in three directions at once, connecting the threads to the central power rod, which also makes it possible to increase the strength of the entire structure.

The reinforcing fibers are mutually located in the three-dimensional structure of the entire connecting threaded element with a uniform interval, which allows you to evenly distribute the load in the composite material.

In particular, fiberglass, aramid and boron fibers or ultra-high molecular weight polyethylene yarns can be selected. And when using a carbon matrix, the composite acquires high thermal stability, thereby increasing the structural integrity of the composite material during operation at elevated temperatures.

The technical result provided by the above combination of features is an increased structural integrity of the polymer composite based on a 3D woven preform, increased element reliability due to increased chipping and shear strength under axial loads of its thread, increased impact resistance and resistance to loads such as bending, lack of layering of the material, moreover, the impact strength is several times higher than that of conventional layered materials.

The claimed element, unlike the prototype, is more reliable due to the fact that its thread, due to the presence of not only longitudinal unidirectional, but also transverse to the axis of the screw reinforcing continuous carbon threads, has increased chip and shear strength. Moreover, each thread turn has reinforcing continuous carbon threads running across the longitudinal axis of the screw, connecting it with the central power rod of the screw. A clear threaded contour of the thread provides a high quality of adhesion of the proposed element with the mating thread of the element connected to it.

The essence of the invention is illustrated by drawings, which show:

Figure 1 - Isometric view of the screw based on orthogonal weave;

Figure 2 - Isometric view of the finished screw with threaded threads;

Figure 3 - Isometric structure of the screw with orthogonal reinforcement;

Figure 4 - Longitudinal section of figure 3 with the structure of bulk reinforcement;

Figure 5 - View In figure 4;

Figure 6 - Screw based on orthogonal reinforcement, front view.

The invention is illustrated by a description of a specific, but not limiting, implementation example and the accompanying drawings. A screw was taken as an example of development, having the form of a rod with an external thread at one end and a structural element for transmitting torque at the other.

Carbon composite threaded connector shown in figure 1 and figure 2, contains a solid-woven rod 1 with a cylindrical head 2, made on the basis of orthogonal weave, where three systems of reinforcing continuous carbon threads are used to reinforce the structure: warp threads 3, weft threads 4 and stitched threads 5. Threaded thread 7 (figure 2)located on the outer side of the rod, including reinforced orthogonal weave (shown in figure 5).

A special structure (shown in Fig.3 and Fig.4) is created due to the trajectory of laying the main threads 3 not completely straight, but only in the rod 1, in the area of the cylindrical head 2, the longitudinal threads 3 change the trajectory and go around its walls, preventing the possibility of pulling out the threads bases from the head under mechanical stress, increasing the strength of the structure of the entire composite and the element for transmitting torque.

A manufacturing option for a carbon composite threaded connector may be as follows.

With the technology of manufacturing a composite screw by vacuum infusion, first, a volume-reinforcing preform is manufactured, based on an orthogonal weave, which fits into a tooling mold, followed by impregnation with resin under vacuum. After curing the resin, a solid-woven composite screw is cut out from the impregnated preform by machining (Fig. 1), a threaded thread 7 is created on the peripheral surface of one end of the rod 1 (Fig. 2) and a structural element 6 for transmitting torque on the cylindrical head 2, for example , a groove for a screwdriver, for an imbus key, an open-end wrench.

The diameter and thickness of each of the systems of reinforcing continuous carbon filaments 3, 4, 5, constituting the elongated woven material of the seamless 3D preform, can vary in accordance with the mechanical strength required for the externally threaded element (view B of FIG. 4).

As the underlay matrix used in the present invention, epoxy resins, unsaturated polyester resins, vinyl ester resins, epoxy acrylate resins, phenolic resins, and the like can be mentioned. Epoxy resins are preferred in terms of various desirable properties such as adhesive strength, tensile strength, flexural strength, electrical insulating properties, and no cure shrinkage.

As can be seen from the above, an externally threaded composite element having sufficient physical strength for practical use can be easily manufactured by threading a rod produced from a resin impregnated solid 3D preform. Thus, the male threaded member of the present invention can be produced at a lower cost than the conventional prepreg press method, which requires not only a step of preparing prepreg sheets, but also a step of stacking a plurality of prepreg sheets into a stack of predetermined thickness.

The claimed connecting element is manufactured under industrial conditions on the equipment for the production of composite products.

In addition to high strength, screws according to the present invention are characterized by excellent corrosion resistance, and carbon matrix screws are additionally characterized by high temperature resistance. Accordingly, screws are particularly suitable for use in joining elements composed of composite materials, ceramics, carbon or graphite, which are subjected to high thermal loads or chemical attack. Such threaded elements are very important in such key areas as aerospace and defense engineering.

Claims (1)

Carbon composite threaded connecting element in the form of a rod with an external thread, reinforced with reinforcing carbon continuous threads located in three directions at once, connecting the threads to the central power rod, made of a polymer matrix reinforced with continuous carbon threads, which is an epoxy resin for creating a polymer composite material , characterized in that the composite is made on the basis of a three-dimensional solid-woven 3D preform using an orthogonal weave, so that the transition from the rod to the cylindrical head is made with a change in the reinforcement structure so that the warp threads, located rectilinearly in the longitudinal direction of the rod, change the trajectory and form an angle to its axis, that is, they go around the walls of a cylindrical head, on which a structural element for transmitting torque is located.