RU1787644C - Riveting method - Google Patents

Abstract

Usage: riveting and assembly work, riveting structures with elements of fibrous composite materials. SUMMARY OF THE INVENTION: A hole is formed in a bag and a rivet is installed in it with a recess at the end of the shaft. The volume of the cavity of the recess is partially filled with a deformable medium. A spacer ring is mounted on the protruding end of the rivet shaft. After the package is fixed, a pulse deforming force is applied to the end of the rod, and by filling the free volume of the cavity of the recess with de-hardened material, a reinforced layer is formed at the end of the rod. After that, the hardened layer is moved into the volume of the insertion head with the simultaneous removal of the deformable medium from the cavity of the cavity and complete its formation. The method provides high performance and high strength characteristics of the joint. 6 ill.

Description

The invention relates to riveting and assembly operations, primarily for structures containing mixed bags, and can be used in all sectors of the economy where riveting of structures with elements of fibrous composite materials is required.

A method of riveting is known, which consists in forming a hole in the packet, installing a rivet in it, fixing the packet and subsequent riveting by axial plastic compression of the part of the rivet shaft protruding above the packet.

The known riveting method is not applicable to structures containing elements of fibrous composite materials, due to uncontrolled distribution of the rod on the thickness of the bag. The latter causes the destruction of the element of the fibrous composite material.

There is also a method of riveting predominantly packages; containing elements of fibrous composite materials, in which a hole is formed in the bag, a rivet is placed in it with an axial recess at the end of the rod, the cavity of the recess is filled with a deformable medium, a spacer ring is installed on the protruding part of the rod, the package is fixed with the subsequent formation of a locking head in the axial process plastic compression of the rivet stem portion protruding above the plane of the packet.

However, the formation of the closing head of the rivet is associated with thinning of the walls of the axial recess and, as a result, causes two possible types of destruction:

XI 00 x O

separation of the locking head in the plane of the bottom of the recess and the shift of the washer ring relative to the rivet shaft. Moreover, the first type of destruction is most likely since the known method does not give recommendations for controlling the strength characteristics in a dangerous section. A second type of collapse can be eliminated by adjusting the height of the locking head.

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In addition, in the implementation of this method, two transitions are required, which lengthens the technological process, and two sets of technological equipment, which increases the cost of the power point.

The purpose of the invention is to increase labor productivity and strength characteristics of a power point.

This is achieved by the fact that in the riveting method, mainly of packages containing elements of fibrous composite materials, in which a hole is formed in the package, a rivet with an axial recess at the end of the rod is placed in it, the cavity of the recess is filled. with a deformable medium, a lining ring is installed on the protruding part of the rod, the bag is fixed, followed by the formation of a locking head during axial plastic compression of the rivet rod portion protruding above the package plane, the cavity cavity is partially filled with the deformable medium, when the closing head is formed, a hardened layer is first formed at the end of the rod by filling the volume of the cavity cavity free of the deformable medium with the deformation-hardened rivet material, and then are the axial movement of the hardened layer into the volume of the locking head while removing the deformable medium from the cavity of the recess.

In FIG. 1 shows the initial position of the die tooling before the formation of the closing head of the rivet; Figure 2 shows the end of the step of forming a reinforced layer at the end of the rivet rod; in Fig.3 - the stage of distribution of the rivet rod; Fig. 4 shows the initial stage of axial movement of the hardened layer; Fig. 5 shows the final stage of axial movement of the hardened layer into the volume of the closure head while removing the deformable medium from the cavity of the recess; figure 6 is a power point.

 In a mixed bag containing an element 1 of a fibrous composite material, for example carbon fiber. and an element 2 of a uniform material, for example aluminum alloy B95, has a through hole.

Next, a rivet 3 is installed in the opening of the bag, for example, from

. aluminum alloy B65. having an axial recess. The volume of the cavity of the deepening of the rivet 3 is previously partially filled. They are removed by deformable medium 4, for example, water. A spacer ring 5 is placed on the protruding part of the rivet rod 3. The package is fixed by pressing 6 with a force

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A step hole is made in the clamp 6, and the diameter of the step is equal to the diameter of the closing head of the rivet (selected from the drawing of the power point), and the diameter of the hole provides clearance-free placement of the rivet 3 in the clamp 6. In the hole of the clamp 6

a cylindrical punch 7 is mounted to fit the movement. In the punch 7 there is a through hole with a diameter of zn. significantly smaller than the diameter of the axial recess in the rivet 3 (Fig. 1).

The implementation of the invention is as follows.

When a pulsed force PT acts on the end face of the punch 7, at the first moment, plastic rivet 3 is compressed in place of its contact with the punch 7. As a result, a reinforced layer of thickness h is formed on the end surface of the rod 3. In this case, the plastic flow of the rivet material 3 is localized on a conical surface with

forming ab (figure 2). the hardened layer h is calculated from the condition of constant volume and is found by the formula:

-Cff-d2).

h

I

where D is the diameter of the stud rivet 3; d is the diameter of the cavity of the recess; I - part of the depth of the cavity of the cavity free of viscous medium.

Further movement of the punch 7 in the direction of the mixed bag causes the rivet 3 material to be squeezed out into the clamping step 6, which is facilitated by both the generated axial force and the pressure of the deformable medium 4 (Fig. 3).

From the moment the rivet 3 rod touches the walls of the press step 6, the cavity of the recess is removed by axial movement of the reinforced layer. The procedure for this elimination is characteristic in that a conical surface of local shear is formed with a generatrix cd (Fig. 4). Deformable medium 4 at the stage

The elimination of the recess cavity during axial movement of the hardened layer is expelled through the through hole in the punch 7.

At the final stage (Fig. 5), the diameter of the cavity of the recess is extremely small, i.e. the cross section of the rivet rod 3 in the upper cavity of the backing ring 5 is up to 95-99% of the total cross section.

The method has passed a pilot test when riveting a mixed package with a thickness of 6 mm The package contained an element made of carbon fiber grade KMU 2.0 mm thick and an element made of aluminum alloy B95 4.0 mm thick. A hole with a diameter of 4.0 mm was obtained by punching in a tool stamp. A rivet made of B65 alloy with a diameter of 4.0 mm and a rod length of 13.0 mm was placed in the opening of the bag.

A deformable medium — water — was introduced into the rivet cavity in a volume equal to 60% of the total volume of the cavity of the recess. A lining ring 1.0 mm thick of D16T alloy was installed on the rivet shaft.

The package was fixed with a clamping force of 40 kN. Riveting was carried out by means of a pulsed impact by a striker on the end of the rivet rod through a punch. The mass of the impactor was 450 g. The initial impact velocity was 20-21.0 m / s. The tooling was made of U8A steel according to the 7th accuracy class.

The MiU-10 magnetic pulse pulse installation was used as an energy drive at a discharge energy of 3.3 kJ.

Rivet joint tests revealed a breakage pattern by shifting the spacer ring relative to the rivet shaft. The shear force was determined by the height of the locking head.

Microsections made from locking heads of rivets confirmed the presence of surfaces of maximum shifts

(ab and cd), and microhardness measurements on the PMT-3 device revealed anomalous hardening, more than 50% with respect to the initial one.

The riveting method is effective in comparison with the Bolee prototype, since it implements riveting in one transition, which increases labor productivity; only one set of tooling is required, which reduces the cost of the power point;

hardening of the rivet takes place in the region of the locking head, which predetermines only one type of separation-shear failure. . .... .....,.

The latter is controlled by the height of the locking head.

Formula and Method of riveting predominantly packets containing elements of fibrous composite materials, which consists in forming a hole in the packet, placing rivets in it with an axial recess at the end of the rod, filling the cavity of the recess deformable medium, installation on the protruding part of the rod

a backing ring and fixing the package with the subsequent formation of a locking head during axial plastic compression projecting above the plane of the package of the rivet rod part, characterized in that, in order to increase labor productivity and strength characteristics of the force point, the cavity of the recess is partially filled with the deformable medium during formation

the closure head first form a hardened layer at the end of the rod by filling the volume of the cavity cavity free of the deformable medium with the deformation hardened rivet material,

and then, the hardened layer is axially displaced into the volume of the closure head while removing the deformable medium from the cavity of the recess.

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