Head shapes ❹ – ⓫ The simplest head shape, as in illustrations A and B, is used chiefly for rivet pins up to approx. d = 4 mm. Partically crystalline thermoplastics can in certain circumstances be difficult to work in these forms, because no particular care is over melting of the material. A proven, modified shape helps here. The horn has a central tip. The ultrasonic energy is thereby heavily concentrated and greatly assists melting of the material. As a result short welding times and good strength values are achieved. Shapes C and D are suitable for all thermoplastics and rivet spigots where d = approx. 2 8 mm. – Head shape E shows an alternative to the central spike. Here melting of the material is assisted by suitable shaping of the spigot. lt is important for this tip to be sharp-edged or shaped with a maximum radius of 0.2 mm. This shape is favourable for working with glass fibre reinforced materials. Multiple rivet joints in one plane with spigot diameters up to about 4 mm can also be produced with large area, plane horns. Positional inaccuracies and measurement tolerances have no effect or are insignificant. As head shapes F and G are not defined, these applications are limited to places which are not visible on the finished product. For partially crystalline thermoplastics and larger spigots, steps must be taken to assist with the melting. A rhombic shaping (Kourl pattern) of the horns has proved very successful. Quite understandably, these two variants do not meet any special requirements for strength. They are used in preference for the fixing of metal parts in electrical engineering. For the larger spigot diameters, from about 6 mm upwards, the use of hollow spigots as in illustration H is recommended. Accumulations of material and therefore sink marks on injection moulded parts can thus be avoided. The quantity of material to be shaped is reduced, which is beneficial in terms of the welding time and the energy requirement. The suggested standardization represents approximate values. These can of course be varied and adapted to individual requirements. The of the hollow rivet brings us to a further shaping technique: flanging.
Head shapes ❹ – ⓫ The simplest head shape, as in illustrations A and B, is used chiefly for rivet pins up to approx. d = 4 mm. Partically crystalline thermoplastics can in certain circumstances be difficult to work in these forms, because no particular care is over melting of the material. A proven, modified shape helps here. The horn has a central tip. The ultrasonic energy is thereby heavily concentrated and greatly assists melting of the material. As a result short welding times and good strength values are achieved. Shapes C and D are suitable for all thermoplastics and rivet spigots where d = approx. 2 – 8 mm. Head shape E shows an alternative to the central spike. Here melting of the material is assisted by suitable shaping of the spigot. lt is important for this tip to be sharp-edged or shaped with a maximum radius of 0.2 mm. This shape is favourable for working with glass fibre reinforced materials. Multiple rivet joints in one plane with spigot diameters up to about 4 mm can also be produced with large area, plane horns. Positional inaccuracies and measurement tolerances have no effect or are insignificant. As head shapes F and G are not defined, these applications are limited to places which are not visible on the finished product. For partially crystalline thermoplastics and larger spigots, steps must be taken to assist with the melting. A rhombic shaping (Kourl pattern) of the horns has proved very successful. Quite understandably, these two variants do not meet any special requirements for strength. They are used in preference for the fixing of metal parts in electrical engineering. For the larger spigot diameters, from about 6 mm upwards, the use of hollow spigots as in illustration H is recommended. Accumulations of material and therefore sink marks on injection moulded parts can thus be avoided. The quantity of material to be shaped is reduced, which is beneficial in terms of the welding time and the energy requirement. The suggested standardization represents approximate values. These can of course be varied and adapted to individual requirements. The of the hollow rivet brings us to a further shaping technique: flanging.
Construction-Guidelines-Ultrasonic-Fusion-Forming_april-2018.docx