What is Mechanical Link?

The mechanical connection of steel bars refers to a connection method in which the force in one steel bar is transmitted to another steel bar through the mechanical occlusion of a connector or the pressure bearing effect on the end face of a steel bar.

Mechanical connection process

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This type of connection method has been developed in China in the past 10 years. It has the following three advantages: First, the quality of the joint is stable and reliable, not affected by the chemical composition of the steel bar, and the influence of human factors is small; Second, the operation is simple and the construction It is fast and not affected by climatic conditions; three, no pollution, no fire hazards, construction safety, etc.

In the connection of thick-diameter steel bars, the mechanical connection method of steel bars has broad development prospects.

There are four main connection methods: 1. Extrusion connection of reinforced sleeve; 2. Connection of reinforced tapered threaded sleeve; 3. Connection of reinforced upset straight threaded sleeve; 4. Reinforced rolled straight threaded connection (direct rolling, extrusion) Rib rolling, peeling rib rolling).

Mechanical connection process refers to the process and method of connecting parts with fasteners. The commonly used mechanical fasteners are mainly bolts, screws and rivets. A modern aircraft uses millions of fasteners of various types, of which the labor in the drilling and riveting process alone accounts for 20% of the component manufacturing man-hours.

Process and method of connecting parts using fasteners.

The commonly used mechanical fasteners are mainly bolts, screws and rivets. Mechanical connection is more reliable than connection technology such as glue or spot welding, and it is easy to replace, so it still occupies an important position in modern aircraft manufacturing.

Aircraft mechanical connection joints should be of minimum weight under the premise of safety and reliability. Not only should they have sufficient static strength, they should also be resistant to fatigue and, at times, leak tightness.

Fasteners used in aircraft and spacecraft also have special considerations in material selection, construction and connection processes. This is to replace ordinary steel with aluminum alloy, titanium alloy or alloy steel with high specific strength; develop new fasteners such as high lock bolts, ring groove rivets, headless rivets, hollow rivets and their connection processes. These fasteners can ensure stable locking force and static strength from the structure.

Fatigue damage is the main danger of aircraft. Fastener holes on structural elements are a weak link in the structure to resist fatigue damage.

Therefore, technical measures such as static fit (interference fit), hole finishing, cold extrusion strengthening, and high locking are often adopted at important parts of the aircraft structure. The purpose is to alleviate the stress concentration around the fastener holes, reduce the level of alternating stress, and improve the fatigue strength of the structure (see fatigue and fracture).

When the amount of interference between the fastener and the hole is 1% to 3% of the diameter of the fastener, the fatigue life of the joint can be doubled, and stress corrosion caused by excessive tensile stress around the hole can be avoided. The use of titanium alloy fasteners and interference fit is an important way to increase the fatigue strength and reduce the weight of aircraft structures from the perspective of mechanical connection.