Sheet metal machines and joints

SHEET METAL WORKING MACHINES

For production and heavier works, machines are used to carry out different sheet metal operations. Some commonly used machines in sheet metal shop are:

Rolling machine: 

The machine is used to form cylindrically shaped articles and is must in any sheet metal shop. Most commonly used is 3-roll bending machine. Two rolls are one above one another. The bottom role is fixed while the top roll is adjusted according to the thickness of sheet. The third roll can be moved up and down to produce cylindrical form of required diameter.

Sheet bending machine: 

This is used for bending and folding the edges of sheet metal and is most widely used machine. It consist of basic three parts:
• Bed
• Top leaf
• Bending leaf
Average capacity is to bend sheet of 16 S.W.G or lighter. For heavier sheets press brake is used. Forming molds are attached to bending leaf for forming operations. The forming operation could be a curved shape. The required bend is made by raising the bending leaf to the proper position.

Swaging machine: 

Swaging machine consist of sharp teeth blade that can be removed by means of handles. While moving on the joint, the joint gets pressed and locked. This machine is used for pressing i.e. locking and grooving joints or seam joints.

Lever shearing machine: 

This is must in sheet metal shop. It is a universal shearing machine. It is used for sheet cutting, flat shearing, round bar shearing, square bar shearing, angle iron cutting.

Universal cutting machine: 

It is used for cutting the metallic sheet into any desired shape and size. Its straight as well as circular cutting capacity in 22 S.W.G sheets and thinner. The machine has two circular tools used for circle cutting.

Grooving machine: 

It is used to make grooves. Depth of the groove as well as position can be conveniently adjusted.

SHEET METAL JOINTS

According to the requirements many different types of joints are used in sheet metal work. 

A lap joint is very frequently used and can be prepared by means of soldering or riveting.

Seam joint is a very commonly used one. It is locked so as to ensure a positive grip and also to make the joint flush with the surface.

Hem (single and double) wired edge, cup and angular enables the edges to join the pieces along them.

The cap joint provides another useful form of locked seam joint.