Types of Couplings and Welding Techniques in Mechanical Engineering

Rigid Couplings

Rigid couplings are used when trees are on the same axis and do not change their position. There are several types:

• Flange Couplings: These are based on placing two flanges on the ends of the shafts so that when tightening the screws, the flanges are joined together.
• Clamp Couplings: These use a tapered internal conical piece that is compressed when tightening the screws, pressing the two pieces together.

Mobile Couplings

Mobile couplings are designed to accommodate some degree of misalignment or movement between shafts.

• Couplings with Gaskets: These absorb minor irregularities through elastic rotation and allow for very little misalignment.
• Universal or Cardan Joints: These transmit motion between two non-aligned trees.
• Homokinetic Joints: Similar to Cardan joints but do not produce oscillations. They are commonly used in the automotive industry.
• Oldham Couplings: These transmit parallel movement between two trees.
• Spline Shafts: These allow the tree to vary its length.

Detachable Joints

• Leveling Screws: These are screws that are screwed into a nut.
• Screw Unions: Similar to leveling screws but do not use a nut. They are used to hold large pieces of thick material.
• Set Screws: These are screws that are screwed into one piece and become lodged in a hole in the other piece.
• Studs: These are rods threaded at both ends with the central part unthreaded. They are used in large or expensive metal parts.
• Bolts: These are used to connect several pieces, providing support and anchorage.
• Sheet Metal Screws: These are used for joining pieces of thin metal. It is not necessary to thread the hole.
• Wood Screws: These are used for joining pieces of wood or wood-derived materials. If the screw is not large, a pre-drilled hole may not be necessary.

Welding

Welding is a process for creating a permanent joint between two pieces of metal or two parts of a single piece by applying high temperature to the surfaces to be joined.

Welding Procedures

• Heterogeneous Welding: This involves using a filler material with a different composition than the base materials, or using a filler material of the same composition but with a different nature.
• Homogeneous Welding: This involves using materials of the same nature.
• Autogenous Welding: A type of homogeneous welding where no filler material is used.

Cold Welding

Also called chemical welding, cold welding uses a mixture of metal powder and plastic resins. The mixture is applied to the pieces to be joined, and it hardens to create a bond. It can be used to join both metals and nonmetals.

Hot Welding

Hot welding involves permanently joining materials by applying heat to the joint area until it melts, uniting the pieces. In homogeneous soldering, the union becomes stronger after cooling.

Welding Types

• Soft Soldering

  This is a type of heterogeneous welding that uses temperatures below 400 degrees Celsius, typically with a tin-lead alloy at around 230 degrees Celsius. It is used for welding cables, electrical components, and thin metal sheets.

• Strong Soldering

  This is a type of heterogeneous welding that uses temperatures up to 1000 degrees Celsius. A brass filler rod is used, and an antioxidant is added to help the filler flow through the metal parts to be soldered.

• Oxyacetylene Welding

  This type of welding uses the heat from a torch to reach temperatures of around 3000 degrees Celsius. It requires a bottle of butane, an oxygen bottle, and a torch. The oxyacetylene flame is obtained by mixing oxygen and acetylene in the torch, creating a focused heat zone.

• Electric Welding

  This is used to join pieces of great thickness and size. An electric arc is created between two electrodes, melting the materials at the joining point.

Types of Electric Welding

• Electric Arc Welding

  An electrode is connected to the wires of a transformer. The electrode and the surface of the workpiece melt, creating the weld.

• Electric Spot Welding

  This is used to merge thin sheets or pieces between two electrodes. The current fuses the contact points, creating the weld.