RU-2861469-C1 - METHOD FOR FORMING ONE-PIECE T-SHAPED JOINT OF PARTS OF THREE-LAYER STRUCTURE WITH HONEYCOMB CORE

RU2861469C1RU 2861469 C1RU2861469 C1RU 2861469C1RU-2861469-C1

Abstract

FIELD: design. SUBSTANCE: invention relates to the manufacture of structural elements consisting of three-layer panels with a low-density core (e.g., a honeycomb core). A method for forming a one-piece T-shaped joint of parts of a three-layer structure with a honeycomb core is characterised by preparing the parts to be joined by machining one of the parts along the end part and fitting the surfaces to be glued. After that, mutually aligned holes are prepared in the parts to be joined for installing threaded fasteners. In one of the parts, the holes are made along the normal or at a given angle to the surface, and in the mating part, the holes are made from its end side. Then, a gap-filling adhesive composition is applied into the prepared holes and onto the parts to be joined themselves in the area of their joint. After that, the parts to be glued are aligned, and they are fixed by installing threaded fasteners into the prepared holes. Fillets are formed on the sides of the T-shaped joint from adhesive composition extrusions using a profiled tool. After gluing the parts, they are kept for the time necessary for the adhesive composition to polymerise. EFFECT: simplification of the process of forming a T-shaped joint of parts of a three-layer structure, as well as reduction of the weight of the T-shaped joint assembly of panels. 1 cl, 1 dwg

Inventors

Ivanov Aleksei Ilich
Kamalov Ildar Nailevich
Morozov Boris Borisovich
Iskhakov Viktor Sergeevich
Bakushkin Anton Sergeevich

Dates

Publication Date: 20260505
Application Date: 20251121

Claims (7)

A method for forming a permanent T-shaped connection of parts of a three-layer structure with a honeycomb core, which includes the following steps:
- preparation of the parts to be joined by mechanical processing of one of the parts along the end part and fitting along the surfaces to be glued;
- preparation of holes in the parts to be joined that are coordinated with each other for the installation of threaded fasteners, the diameter of which is less than or equal to the internal diameter of the fastener used, while in one of the parts the holes are prepared normally or at a given angle to the surface, and in the mating part the holes are prepared from the side of its end;
- application of an adhesive gap-filling composition into the prepared holes and onto the parts being joined in the area where they join;
- joining the parts to be glued and fixing them by installing threaded fasteners into the prepared holes;
- formation of a T-shaped joint of fillets on the sides from pressings of the adhesive composition using a profiled tool;
- holding for the time required for polymerization of the adhesive composition.

Description

The invention relates to the field of aviation technology, namely to the production of structural elements consisting of three-layer panels with a low-density filler (for example, with a honeycomb filler). A method for forming permanent connections of parts of a three-layer structure made of polymer composite materials is known (patent RU 2738944, published 12/18/2020), characterized by the fact that in the basic three-layer structure (BTS) a groove is made in the outer and middle layers, at the edge of the attached three-layer structure (ATS) a recess of the middle layer is made along the entire length of the connection, into which an embedded part of a U-shaped profile is installed with an adhesive along the entire length of the recess with the middle shelf inside the recess, close to the end of the middle layer of the TCS, then the TCS is installed along the entire length of the connection in the central part of the TCS groove and pre-fixed, after which the TCS is molded on both sides using internal "wet" corners to the inner surface of the outer layer of the TCS, after which inserts are placed in the formed parts of the TCS groove on both sides of the TCS along the entire length of the connection to the entire depth of the groove, filling The BTK groove is pressed vertically up to its outer layer, and the internal corners press against the PTK and the inner side of the outer BTK layer. The PTK is then molded along the entire length of the joint on both sides using external "wet" corners to the inserts installed in the BTK groove, and then to the BTK, ensuring a tight fit without air inclusions. A disadvantage of this known method is the need to use an embedded part, internal and external "wet" corners, and inserts filling the BTK groove between the internal and external corners. Furthermore, when forming a joint in this manner, the parts being joined must be securely fastened relative to each other in special fixtures until the adhesive and "wet" corners have fully cured. These disadvantages significantly complicate the process of forming a T-joint and also increase the weight of the resulting structure. Methods for forming adhesive-mechanical joints (M.I. Semin, "Strength and Durability Calculations for Joints of Polymer Structural Elements," monograph, Moscow, MADI, 2016, pp. 4-6, 9-11) are known to involve joining parts by overlapping them. The strength of such a joint is determined primarily by the installed threaded fasteners. When forming a T-shaped joint between two parts using the known method, it is necessary to use an additional mating element, overlapping each part, which complicates the design and increases the labor intensity of the joining process. The objective of the present invention is to form a T-shaped joint between parts while simultaneously securing them to one another without the use of additional joining elements. Furthermore, the parts being bonded do not require fixation in a special technological device such as a jig or similar device. The technical result achieved by the present invention is a simplification of the process of forming a T-shaped connection of parts of a three-layer structure, as well as a reduction in the weight of the parts connected by the proposed method and, as a consequence, of the aircraft as a whole. The technical result is achieved by the claimed method of forming a permanent T-shaped connection of parts of a three-layer structure with a honeycomb filler, which includes the following steps: - preparation of the parts to be joined by mechanical processing of one of the parts along the end part and fitting along the surfaces to be glued; - preparation of holes in the parts to be joined that are coordinated with each other for the installation of threaded fasteners, the diameter of which is less than or equal to the internal diameter of the fastener used, while in one of the parts the holes are prepared normally or at a given angle to the surface, and in the mating part the holes are prepared from the side of its end; - application of an adhesive gap-filling composition into the prepared holes and onto the parts being joined in the area where they join; - joining the parts to be glued and fixing them by installing threaded fasteners into the prepared holes; - formation of a T-shaped joint of fillets on the sides from pressings of the adhesive composition using a profiled tool; - holding for the time required for polymerization of the adhesive composition. When forming a T-shaped connection of parts using the proposed method, the technological fixation of the parts to be joined is carried out using threaded fasteners, and the strength of the final adhesive joint is ensured mainly by the area of the contacting surfaces of the parts to be glued and the adhesive fillets formed in the gluing zone. The essence of the claimed invention - a T-shaped connection of parts of a three-layer structure with a honeycomb filler - is explained in Fig. 1, which shows a cros