SU1508020A1 - Bolted connection of works - Google Patents

Abstract

FIELD OF THE INVENTION The invention relates to mechanical engineering, to high resource bolt joints of parts. The purpose of the invention is to increase the fatigue life of the joint by creating a local tension between the bolt stem and the hole in the parts being joined. The bolted connection of parts 1 and 2 contains the lining 3, 4, bolt 5, nut 6, washer 7. The bolt rod is made with two longitudinal projections. The protrusions have a rounded shape in cross section and are located symmetrically in the axis of the bolt in a plane perpendicular to the load vector on the parts being joined. The protrusions ensure the formation of local tension between the bolt rod and the hole of the connected part. Tension is created in the areas most likely to cause fatigue cracks, which contributes to an increase in fatigue life. 3 il.

Description

R.

cl

about c about to

7

figl

FIELD OF THE INVENTION The invention relates to mechanical engineering, to high resource bolt joints of parts.

The purpose of the invention is to increase the fatigue life of the joint by creating a local tension between the shaft of the bolt and the hole in the parts to be joined.

FIG. 1 shows a multi-shear bolted joint, side view; in fig. 2 is a fragment of the bolted design and geometric bolt widths, section A-A in FIG. one; in fig. 3 - E1NOR of tensile and circumferential holes on the contour of the hole, voltage plots on the wall of the bolt hole.

The bolted connection of parts consists of sheets 1 and 2 to be joined, plates 3, 4, bolts 5, nuts 6, and washers 7. The bolts in the joint have two longitudinal protrusions 8 on the rod. The protrusions are located symmetrically with the bolt axis in a plane perpendicular to the load vector on the parts being joined. In Ionerechnogo section of the protrusions have a rounded shape.

The lip of the protrusions 8 contributes to the realization of a tension at the points of the contour of the hole from which the fatigue crack arises.

The fatigue durability of the component connection: | it depends on the amount of tension in the part at the location of the protrusion 8. Value of tension (Fig. 2) He d.

D

"6

where c / o is the diameter of the bolt hole;

HS is the diametral height of the projections.

Nat g on the rest of the surface. holes can be made minimal (for tightness) or even without it, while maintaining high fatigue characteristics with stress. The technological force of the pressing in of the bolt consists of the force of pressing the edges of the hole with the protrusion 8, which constitutes 5-15% of the perimeter of the hole for the bolt. The magnitude of circumferential tensile stresses at the edge of the hole decreases.

ln

(local tension

compared to

nat - st

rk

bolted as well

with a protrusion with an equal dimensional value of the stresses of the SM ti along the wall of the hole compared to of /.

The rigorous orientation of the protrusions with respect to the aperture and the small force of the bolt being pressed out provide the best maintainability of the joint. For aircraft construction, the use of duralumin alloys of the type L16T, B95 for the connection of parts and crush, titanium of the type ZOHGSA, 16XCN, and BT-16 is typical for bolts. For these

0

five

0

five

0

five

0

combinations of materials recommend the ratio of the geometric parameters of the bolt Yag / ib 1.05-1.2; Be / a 0.15-0.25; , 05-0.1; where de is the diameter of the rod: the bolt; BB - the width of the protrusion; g - the radius of the protrusion.

The magnitude of the geometric tension in the joint at the location of the projections

Lj

AN - it is advisable to limit its value

This is due to the fact that the further increase in durability in tension is very insignificant. As for the value of Вв, it is necessary to choose it from the fact that under conditions of real loading the value of operating voltages varies in magnitude and direction. It is necessary that the tension zone overlaps the area of the hole contour with places of possible fatigue failure, i.e. the width of the protrusion depends on the parameters of the stress state in the joint. For uniaxially loaded connections, the central angle of the protrusion can be 15–25 °, which ensures that the point of destruction falls into the zone of large plastic tensions. On the rest of the surface, the tension is absent and the distribution of tensions along the contour of the hole practically follows the profile of the bolt.

The technical solution is also applicable when bolts are fitted along the cylindrical part with a slight tension (for rigidity). In this case, its effectiveness is still greater than the connection with a cylindrical bolt with the same tension.

The presence of strictly oriented protrusions contributes to an increase in the shearing gesture of the bone (by rolling the bolt), i.e. the protrusion bolt works like a tongue. This creates both operational benefits (increased joint rigidity) and technological (no need for a second wrench when tightening the bolt nut).

Claims (1)

Invention Formula Bolted connection of parts, bolted, fixed and nut-free, fixed without holes in the holes of the parts being joined, characterized in that, in order to increase the fatigue life of the joint by creating a local tension between the bolt rod and the holes of the parts to be connected, the rod the bolt is made with two symmetric with respect to the bolt axis longitudinal protrusions of a rounded cross section arranged in a plane perpendicular to the load vector on the parts to be joined. A a fig 2 About C / Yeah Fig.Z