Fastening Tool Quickly Produces Cold-Formed Joints

Bollhoff has developed a fastening tool that enables class D airtight duct flanges to be manufactured more quickly, cleanly and economically than traditional drill and fix methods. Called Rivclinch 0404 IP Aero, the tool is TUV Nord certified for class D and produces cold-formed airtight joints in cycle times of between 0.9 and 1.5 seconds - less time than it takes to drill a hole. The pneumatically operated tool achieves low-cost, high-quality joints in a single operation, according to the company.

No additional fastener components are required; there is no swarf and hence no waste. Bollhoff claims that key to the success of Rivclinch, and the class D joint it achieves, is its tooling, which is designed to penetrate the top and bottom layers of each joint while leaving a middle layer in tact to prevent air leakage. The process delivers high-strength, interlocking joints that do not vibrate or work loose over time. The clinching tool said to be is straightforward to use. Jaws are opened either manually or pneumatically and positioned along the profile.

A trigger is pulled to deliver a clinching force of 35kN. Distances between fastening points are generally between 120mm and 160mm. Weighing in at 4.7kg, the clinching tool requires a 5-6bar air pressure supply. Clinching is a method of joining sheet metal extrusions by localised cold forming. The process results in an interlocking friction joint when two or more layers of materials are compressed by a punch into a special die. Coated and prefinished materials can be joined together without surface damage. The Rivclinch technique can be used to join steel and stainless steel sheet as well as aluminium and other non-ferrous materials.

Standard clinching tools produce round or rectangular-shaped joints to suit most applications, but customised tooling design options are available. The size and shape of the joint, coupled with parameters such as the punch diameter or the depth of the die, can be varied to suit the materials to be joined. Advantages of the Rivclinch process include no consumable items, low-energy use, the absence of thermal load and damage to workpieces, the option to use interim layers of film or adhesives, no pre- or post-treatments, excellent repeatability and good environmental credentials (no heat or fumes and low noise).