Technology

The following intensive methods of forming profiles were developed and are currently used in PC “Ulyanovski NIAT”:

• method of restrained bending;
• method of intensive deformation;
• method of directed losses of stability.

The method of restrained bending is to precipitate a wave-like workpiece with thickening of the metal in the zone of bending. The method is designed for hard-deformable and less-plastical materials, used in aircraft structures and contains 2-4 transition for the profiles type channel, trough type, Z-shaped type. Constrained bending is characterized by the fact that in the process of bending a sheet blank applies additional compression forces in the tangential, radial and axial directions. In contrast to the usual bending (traditional profiling), in which the neutral layer shifts towards the inner contour, under the influence of additional forces in the compression zone of the fold there is a shift of the neutral layer of the median line in the direction of the outer loop. Reducing stretching reduces the tensile stresses and deformation of the outer contour, eliminates the risk of fracture during bending with small relative radius. The method allows to obtain constrained bending radius bending (rв=0,5-2 mm) less than the maximum allowable under normal bending.

Method of intense deformation most applicable in the present time at the enterprise, developed 22 years ago, included the advantages of restrained bending and traditional profiling and represents a more progressive method of production profiles almost any section. The advantage of the method of intense deformation in comparison with traditional profiling is to maximize the use of elastic properties of the metal, that allows to use the minimum number of transitions and to reduce the cost of equipment and products.

The principal technological features, that implement the idea of the method of intense deformation in the rolls are:

• reduced the number of transitions compared to the traditional profiling;
• carrying out by a special circuit forming process using more tool settings and impact on a workpiece;
• the application of the roller tool with closed working circuit;
• Combination of the final forming with corrections.

Scheme implementation of profiling techniques and characteristic features of different methods, are given in the following tables:

	Traditional profiling	Method of intense deformation	Cramped bending
Scheme implementation process
Stress - strain state in a bending zone

Characteristics of different methods:

Further improvement of methods of formation led to the creation of a method of aimed loss of stability which is currently being developed. This method, during which the workpiece is forced to lose its stability in a given direction and creates a certain form (arcuate, curvilinear, until the completion of the profile elements) with the following alignment or calibration in next transitions. This method is new and only now passes the development and scientific justification, but a number of profiles obtained by method of directional instability allows to talk about it’s good prospects in the intense deformation area in the manufacture of bended profiles.