Fastener

The connection technology describes the methods of assembling technical structures (machinery, equipment, appliances and modern buildings ) from their individual parts.

In general, there are solid connections. Compounds that restrict the mobility only between two parts are joints (for example, rotary or sliding joints).

The compounds may be releasably (e.g., screw or hook and loop fastener ) or non- removably (for example riveting, welding or bonding ). Soluble compounds can be separated by reverse the connection process again. Non- detachable connections are separable only by destruction.

The classification according to physical principles of action is: a form-fitting, positively and cohesively.

Form closure

Positive connections arise from the interaction of at least two link partners. Thus, the link partner can not be solved without or by interrupting the power transmission. In other words, in a form-fitting connection of a connection partner in the other path. Operating load pressure forces normal, that is perpendicular to the surfaces of the connection partner. Such " closures " are found in at least one direction. Is a second pair of surfaces arranged opposite, and the opposite direction is blocked ( see figure, Schematic diagram and tongue and groove ). There is a pair of two mutually coaxial cylindrical surfaces, there is form-fitting in all directions of the plane perpendicular to the cylinder axis. Example is plugged into a hole pin that is removable again. The hole is advantageously a blind hole so that the pin can not fall through. Here, a one-sided form-fitting will be added in the axial direction. Pin-like connecting elements are rivets and screws, screw connections are both positively and non-positively in general.

Only two primary components are form-fitting to link one another, which is often by means of a third section - is realized - the particular connecting element. For example, the compound is of two overlapping plate edges by means of rivets or screws. The form-fit is out in the sheet plane and perpendicular to manufacture it. The sheets are to be held together, and the connecting elements are not to fall out. To this end, the rivet heads on both sides. The screw has her head opposite is the mother (if the screw is not screwed into the sheet ).

For thin sheets or large forces between the sheets in the direction of their planes there is a risk of plastic deformation or destruction at the hole edges of the sheets ( bearing stress ) and the shear in the pins. Tin compounds are also generally provided with traction or even exclusively designed so that the adhesion alone can withstand the stress. The rivets and screws are axially elastically stretched, which is done by shrinking after a hot rivets or by tightening the screws.

Other examples are: solvable:

• Tongue and groove connection
• Feather
• Zip
• Dovetail joint
• Connecting fitting
• Gear coupling

Not solvable:

• Clinching
• Staking

Traction (frictional )

Flexible joints put a normal - speed ahead on the surfaces to be joined. Their mutual displacement is prevented as long as that caused by the static friction is not exceeded counter - force. The force or frictional connection is lost and the surfaces slide on each other when the tangential load acting force is greater than the static friction force, as for example between wheel and rail or road surface for vehicles under its own power. In the friction clutch of a car the power circuit is interrupted when she is depressed. If they only partially entered against the normal force causing built-in spring, it grinds.

Flast = tangential load force ( blue) FHaft = Haftreib tangential force ( red) μ = coefficient of static friction FN = normal force (green)

Traction is the cause of the self- inhibiting loaded wedges or screws. The static friction between the active surfaces prevents the wedge from slipping out or the screw begins to turn. Screws are tightened, therefore, even if its bias is not required to generate a frictional connection between the connected parts of them (for example, in a sheet metal joining, see above).

The terminal is also a traction: Some hold between your thumb and index finger or with a spring clip.

Two ropes knotted together transmit a tensile force only on force closing when one neglects that the ropes have a residual stiffness against bending, so form-fitting is also involved to a small extent.

Meanwhile include bolted to the positive connections.

Material bond

The metallurgical compounds are called all compounds where the link partners are held together by atomic or molecular forces. They are also non-detachable connections, which can be separated only by destroying the means of fastening:

• Solder
• Stick
• Vulcanize