Stretching as a sheet metal fabrication process
So much has been said about cutting and bending of sheet metal fabricating Toronto to form shapes and designs according to the specifications laid out by the client. Stretch forming or simply stretching is one of the processes in sheet metal fabricating Toronto that involves stretching and bending at the same time over a die in order to form a large contoured part. Stretching of sheet metal is often performed on a stretch press where the piece of sheet metal is held securely along its edges by gripping jaws. The gripping jaws are attached to a carriage that is being pulled through pneumatic or hydraulic force to stretch the sheet. The tooling used in the process is called the stretch form block or form die that is composed of a solid contoured piece against which sheet metal will be pressed. Sheet presses are usually oriented vertically so that the form die which rests on the press table can be raised into the sheet metal using a hydraulic ram. When the form die is driven into the sheet, the tensile forces increase and the sheet will plastically deform to form a new shape.
There are two types of stretch forming equipment: longitudinal and transverse. The longitudinal equipment stretches the workpiece along its length while the transverse equipment stretches the workpiece along its width. Both have specifications that determine the kinds of jaws, die table and hydraulic system. The gripping jaws are very important so that various factors have to be taken into account like the number of jaws, their width, distance between the jaws, stroke per jaw, tonnage per jaw, jaw swing and the gripping pressure. In the choice of the die table, it is important to consider its size and weight, its maximum and minimum tonnage, the length and width of the workpiece, the tile angle, forming speed and stroke.
Specifications for the hydraulic system include the power unit and the ram. Important power unit parameters include motor speed, flow, pressure and fluid type. Ram can be best described by force, open/close rate and pressing rate. A stretch forming equipment can be integrated with CNC technology that does not require consistent monitoring. The operator can simply program the instruction on the computer and the equipment is all set to do its job. Instead of manually adjusting the radius of the jaw by adjusting the locking screws on the curving arms for each of the jaw assembly, it can easily be programmed to minimize manual intervention.