09.2024 a1 b1 a b 30 30-70 a1 b1 b a 30 30 b1 b a subject to alterations APPLICATION EXAMPLES OF FORMING OPERATIONS WITH FIBROFLEX® ELASTOMERS Bending of Vee- and U-Shapes One of the easiest elastomer-forming operations is that of Vee-bending off a solid punch and into a die cushion of stacked FIBROFLEX® pads. The necessary penetration of the punch and the amount of over-bending depend on the thickness, hardness and type of the material – and furthermore on the bending radius, the length of the free legs on the piece part, and lastly on the Shore hardness of the cushion. Applicable to all kinds of bending operations is the general rule: the smaller the bending radius, the less will be the spring-back of the bend and the shallower is the required penetration of the punch. Especially with larger batch quantities it is advisable to ensure all-round retention of the stacked elastomer cushion; it also pays to make punch and cushion identical in length. V- and U-bending can be carried out with layered FIBROFLEX® plates in different Shore hardnesses, as shown in Fig. 1. In the case of solid or plate materials, it is necessary to create an additional displacement zone for reasons of wear, e.g. with the aid of insert strips at the bottom of the forming case, as shown in Fig. 3. An undercut of the bending punch must always be provided to compensate for the workpiece spring. U-bends with a large bottom radius are difficult to accomplish. Punch penetration must of need be large; springback can be quite considerable. In order to fulfil these requirements, the use of FIBROFLEX® cushions (see Fig. 4) is necessary. Displacement possible: a1 = 30-40% of a b1 = 30-40% of b Fig. 1 Fig. 3 Displacement possible: a1 = 40 - 50% of a b1 = 50 - 60% of b Fig. 4 Displacement possible: b1 = 60 - 70% of b Depending on stock specifications the bending of a channel section may either be done off a Vee-shaped punch as a voluntary choice – or it may become an absolute necessity. Two operational sequences are required, and a goose-necked punch configuration is essential. Fig. 2
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