RU2810473C1 - Method for manufacturing lap joints from dissimilar materials - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: invention relates to the production of heterogeneous lap joints and can be used in the transport industry, namely in automotive, aviation, railway and other areas of industry where the production of difficult-to-weld materials is required. The invention is characterized by making holes in the lower, more refractory part, placing and securing a part made of a lower-melting metal on it, and deepening into this part by 0.2-0.3 mm a rotating cylindrical tool mounted at an angle ϕ equal to 1-5°, and moving it forward at an angle, whereas the holes are made in the form of an ellipse with a larger axis located perpendicular to the acting force.

EFFECT: reduced stress in riveted joints.

1 cl, 4 dwg, 1 tbl

Description

The invention relates to the production of heterogeneous lap joints and can be used in mechanical engineering and in the transport industry, namely in automotive, aviation, railway and other areas of industry where the production of difficult-to-weld materials is required.

There is a known method for producing dissimilar parts using rivets, which allow joining materials that cannot be welded by fusion. Patent (see RU2006691C1, F16B19/08 “Rivet and tool for setting it”).

A rivet is a part of a riveted connection made in the form of a round rod, on one side having a filling head and a closing head formed during the riveting process.

The joining method is that rivets are inserted into pre-prepared holes in parts or sheets and riveted.

The closest in technical essence and achieved result is the technology for producing steel-aluminum joints STIR-LOCK, (see Friction stir technology - recent developments in process variants and applications [Electronic resource] / Staines D.G., Thomas W.M., Kallee S.W. and Oakley P.J. - United Kingdom: TWI Ltd, 2006. - Access mode http://www.twi.co.uk/content/spwmtoct2006.html - Caption from screen.). The connection is obtained as follows. First, holes are made in the more refractory plate. The plate is fixed, and a plate made of a less refractory and more ductile metal (aluminum alloy) is placed on top of it and secured. Then a rotating tool in the form of a cylinder, installed at an angle of 1-5° relative to the vertical axis, is lowered to the assembled parts and inserted into the more plastic one to a depth of 0.2-0.5 mm. In this case, the upper part is heated and plasticized, and the tool moves along the holes at an angle forward. In this case, the plasticized metal moving over the hole fills them. Thus, a mechanical connection is formed with the rivet from a body of more fusible metal.

The disadvantage is that to reduce stress in cylindrical rivet joints, an increase in their diameter is required, and this leads to an increase in the required volume of plasticized metal.

The objective of the invention is to reduce stress in rivet joints without increasing the required volume of plasticized metal.

The essence of the invention lies in the fact that a method for manufacturing lap joints consisting of dissimilar materials, characterized by making holes in the lower, more refractory part, placing and securing a part made of a more ductile metal on it, deepening 0.2-0.3 mm into this part a rotating cylindrical tool installed at an angle ϕ=1-5°, and moving it forward at an angle, while the holes are made in the form of an ellipse with a larger axis located perpedicular to the acting force.

The technical result is achieved by the fact that in the method of producing lap joints of parts made of dissimilar materials, which includes making parts made of a more refractory material, holes are made in the form of an ellipse with a larger axis located perpendicular to the acting force.

The proposed method for producing lap joints by making elliptical rivets allows you to obtain the following advantages:

- Stresses in rivet joints are reduced without increasing the volume of plasticized metal, which increases the load-bearing capacity of overlap rivet joints.

The essence of the invention is illustrated by the drawing, where:

fig. 1 - shows a diagram of the process of obtaining an overlap rivet connection;

fig. 2 - loading diagram of rivet joints shown on the reverse side (steel 20) of an overlap rivet joint;

fig. 3 - results of stress calculation in a lap joint with cylindrical rivets, which was performed using the finite element method (FEM), σ _max =24.1 MPa;

fig. 4 - results of calculating FEM stresses in a lap joint with ellipsoidal rivets, σ _max =16.2 MPa.

To implement the method, a cylindrical tool with a flat end, position 1, a part made of a more refractory material (steel 20) 2 is used as a lower plate, in which holes 3 are made, and a part made of a more fusible material - aluminum alloy AMg6M 4 - is the upper plate, as well as the resulting as a result of implementing the rivet method from AMg6M 5 alloy.

The method for manufacturing lap joints from dissimilar materials is carried out as follows: holes 3 in the lower plate 2 (a more refractory part) are made in the form of an ellipse with a larger axis located perpendicular to the acting force. A part made of more ductile metal 4 is placed and fixed on it. During welding, the axis of the tool 1 is tilted at an angle ϕ=1-5 relative to the normal. First, tool 1, rotating at a given speed, is immersed in the welded metal of the upper, more plastic part 4 to a depth of 0.2-0.3 mm and moves along the holes 3. As a result of the influence of the thermal cycle and the deformation effect of tool 1, in front of it (tool) a wave of plasticized metal is formed, which, moving over the holes 3, fills them, forming an elliptical rivet 5.

The results of stress calculations in riveted joints performed using the finite element method (FEM), presented in Fig. 3, 4 showed that with equal areas of rivets, connections made in the form of ellipses have a reduced stress state.

The calculation results are shown in the table.

Table Maximum stresses in lap joints depending on the shape of the rivet Form
rivets Rivet dimensions, mm Rivet area, mm ² Maximum stress value, MPa Cylindrical Diameter = 6 28.27 σ=24.1 MPa Elliptical Longitudinal axle length = 2
Cross shaft length = 4.5 28.27 With a length of the transverse semi-axis of the ellipse equal to 4.5 mm, located perpendicular to the acting force σ = 16.2 MPa

Claims (1)

A method for manufacturing lap joints from dissimilar materials, including making holes in the lower, more refractory part, placing and securing a part made of a lower-melting metal on it, deepening a rotating cylindrical tool installed into the part made of a lower-melting metal by 0.2-0.3 mm at an angle ϕ equal to 1-5°, and moving it forward at an angle, characterized in that the holes are made in the form of an ellipse with a larger axis located perpendicular to the acting force.