An existing convex curvature of a wire is eliminated by bending it in the opposite direction. Under the effect of the bending moment M_bZ, the process material deforms elastically or elastic-plastically.
A condition for a successful straightening process is the elastic-plastic deformation of the process material cross-section, i.e. the wire is permanently deformed and does not spring back into its original shape curve. Ideally, an elastic-plastic deformation over the cross-sectional height of the wire results in a linear strain distribution Epsilon_x and a non-linear stress distribution Sigma_x. The process material wire begins to flow plastically at the inner and outer fibres or the edge zones or to deform permanently. In the core there remains an elastic part or an area which is not permanently deformed. As a result of the elastic deformation of the core and the plastic deformation of the edge zones, there is a residual stress curve over the cross-section height without the effect of the bending moment or after the springback, which determines the resulting geometric shape curve of the wire after the springback and is the initial state for the stress distribution over the cross-section height of a subsequent bend.
The membership functions of the input variables and those of the output variable are defined in Figure 2.2, Figure 2.3 and Figure 2.4.
The fuzziness is shown here in particular by the fact that the respective quantities of the sizes merge into each other. A yield strength R_p_0.2 = 800 MPa is assigned to 33 % (degree of membership μ = 0.33) of the quantity very_small and to 67 % (degree of membership μ = 0.67) of the quantity small. The rule base consists of 25 rules, each of which embodies knowledge in the standardized form "IF condition 1 AND condition 2 THEN instruction 1".
The use of a suitable inference mechanism and a specific defuzzification method results in a specific transmission behavior according to the current background image (Figure 2.5). Thus, a sharp output variable can be generated for a set of sharp input variables at any time.
Depending on the magnitude of the total force F_G, specific designs are recommended for the implementation of a quick-closing mechanism for a straightener. The most common designs are those that use at least one excenter, such as those used in the ER, RS or DRS series of straighteners.
Alternatives to the excenter are motion screws or spindle mechanisms, as shown in the adjacent Figure 2.8 (ERS series straightener). These solutions are based on the action of the wedge or use pneumatic or hydraulic cylinders.
The use of cylinders to apply the closing force, as documented in Figure 2.9 (ERS H series levelers), ends the technical category of straighteners. Directive 2006/42/EC declares an assembly of connected parts as machinery if it is equipped or intended to be equipped with a drive system other than directly applied human or animal power and if at least one part is movable. Semi-automated straightening technology as shown in Figure 2.6, which uses actuators to position straightening rollers, also complies with the scope of the aforementioned Machinery Directive, which applies to the EU states and the EFTA states of Iceland, Liechtenstein, Norway and Switzerland.
The assembly instructions inform about the conditions which must be fulfilled by the partly completed machinery to be assembled correctly to form with other parts a complete machinery without impairing the safety and health of persons. Each assembly instruction contains information and instructions on the following topics:
- Information, safety and residual risks
- Characteristics and data
- Setting up
- Handling and use
- Servicing, cleaning and maintenance
- Decommissioning, disassembly and disposal
The intended use of any partly completed machinery is to be assembled or completed with other partly completed machinery (e.g. guards and controls, whether or not they separate) to form a functional and complete machinery. The instructions and conditions given in the assembly instructions must be observed and ensured for the completion or installation of the incomplete machinery in a complete machinery. Accordingly, the assembly instructions must be read and understood before completion or installation of the incomplete machinery and before commissioning. In the event of incomprehension or uncertainty in understanding the assembly instructions, the manufacturer's authorized documentation representative named in the installation declaration for the incomplete machinery must be consulted in writing and in detail. The communication process following the interview must be documented and conducted with the aim of achieving complete understanding. The system and process control of the incomplete machinery is determined by the electrics, hydraulics, pneumatics, hardware, software, protective devices, peripheral elements of the complete machinery, upstream and downstream machinery, user specifications, etc. The communication process following the interview must be documented and with the aim of creating a complete understanding. The Machinery Directive 2006/42/EC as well as pending standards and legal bases apply to the design of these subsystems and machines as well as to possible user specifications which must not lead to an impairment of the safety and health of persons. The designer and the operator of the complete machinery or plant in which an incomplete machinery of WITELS-ALBERT GmbH is installed are responsible for compliance with and consideration of these standards and legal bases. The adjustment force F_iA according to Equation/Gleichung 2.3 causes the mechanism for roll adjustment to spring out. If an appropriate straightener or straightener is designed, the spring deflection is negligibly small. A low spring deflection or sufficient rigidity is considered a quality feature for straighteners and straightening machines, as it is also responsible for the exact securing of the roll positions under load. Nevertheless, it is sometimes advisable not to use the upper limit of the given straightening range of a straightener or a straightener, especially if wire with a high yield point R_p_0.2 is to be processed and wear is to be minimized.
In case of doubt, the manufacturer must always be consulted when selecting the size of a straightener or a straightening machine. Depending on the parameters of the process material wire described at the beginning and other influencing factors, the manufacturer will carry out the necessary calculations and make the selection considering the results of the calculations.
Multidimensionally curved wire, as shown in Figure 1.6 on the left, is straightened with a straightening system. A straightening system consists of at least two straighteners. Each straightener manages the elastic-plastic deformation of the process material wire in a specific plane. Accordingly, at least one straightener has horizontal roll axes and at least one remaining second straightener of the straightening system has vertical roll axes, i.e. there is an angle of 90° between the straightening planes of such a straightening system. The orientation of the roll axes (horizontal or vertical) correspond to the axis around which the respective bends are realized in the plane. Depending on the series of straighteners, connecting angles or bottom plates are used to design a straightening system (Figure 2.12).