SU1214267A1 - Method of straightening articles by flat bending - Google Patents

Description

The invention relates to the processing of metals by pressure, in particular to the tenology of metal straightening, and can be used in metallurgy and mechanical engineering for straightening special products of complex shapes, as well as small batches of wide assortment profiles.

The aim of the invention is to improve the quality of editing by reducing the deformation of products during further processing and operation.

The selection of parts of the product subjected to pre-bending and bending radius is due to the following: the stability of the product’s geometric shape to subsequent processing and operation is achieved by forming a favorable distribution of residual stresses during the correction, while the maximum values of the latter can be reduced by Compared with the known method, n may remain approximately at the same level. When the curvature values of the sections subjected to preliminary bending are less than 0.07, the values of curvature at maximum elastic bending are secondary deformation, for example, after subsequent machining correction less than 40% of the maximum and the proposed method does not provide an improvement in the quality of products compared to the known . With curvature of selected areas greater than 2.5 curvature values with maximum elastic bending, the use of pre-bending also becomes ineffective, since it does not reduce the secondary deformation compared to the known method. At the same time, within the established interval, the secondary deformation decreases 1.1-2.8 times in comparison with the known method. The interval of the values of the C (O, 3–0.8) coefficient in the formula R CRo-n (1 2 Ry / Rc) is chosen similarly: for values of C, less than 0.3 and greater than 0.8, the secondary deformation is reduced. in comparison with the known method, while within the specified interval, the proposed method allows to reduce the deformation by 1.2-7 times. The logarithmic dependence in the above formula was established when analyzing and generalizing the calculated data.

Example 1, Straightening is a cylindrical billet with an outer diameter of 50 mm, inner 35 mm and a length of 2 m of steel with an elastic modulus of 210 GPa and a yield strength of 0.25 GPa, uniform curvature with a deflection boom of 40 mm. After straightening, a part of the blanks will be turned to an outer diameter of 45 mm, and some will go directly to the excavation at 300 ° C, and the creep rate of the structural material in these conditions is described by the equation

p & / e / 10

21,

where P is the creep rate, 1 h; o - voltage. Pa; | & I is the absolute value of the stress in the structure. Pa. Editing is as follows. First, pre-bent portions are determined. The radius of the initial curvature of the workpieces is determined by the formula

-four

where f is the length of the curved section of approximately constant curvature (in this case, the length of the workpiece);

S-arrow deflection in this area. According to the initial data of R 12J5 m, the initial curvature is equal to I / RC, 0.08 m (in practice, these values can be determined not by calculation, but by means of editing process control).

The curvature of the workpiece with maximum elastic bending is determined by the formula

I- 2 - -1--, Ry ED

where From - the yield strength of the material;

E is the modulus of elasticity, in this case this value is 0.0476 m, Rif 21 m. Consequently, the initial curvature of the blanks is 1.67 from the curvature at maximum elastic deformation. This value lies in the set interval of 0.07-2.5 and the whole billet is pre-bent. The preliminary method is carried out by acting on the ends

workpieces directed perpendicular to its surface during the entire exposure time, and the angles of rotation of the ends of the workpiece are chosen so as to plasticize the workpiece in the direction opposite to the initial curvature by the bending radius determined by the formula

R (1 + 2 | i)

KO

where C is a coefficient taking values of 0.25-0.81.

Then, the workpieces are edited according to a known method, which includes the impact on the ends of the workpieces, perpendicular to the surface of the workpiece during the entire exposure time, and the angle of rotation of the ends of the workpiece is chosen depending on the value of the curvature of the workpiece after preliminary bending so as to minimize the curvature of the workpieces.

The results of the calculation of the parameters of the dressing and the secondary deformation formed after turning the blanks and their operation, and similar data for the blanks in the initial state, subjected to editing by a known method, are presented in Table 1.

These data indicate that in the implementation of the proposed method of editing with a radius of pre-bending, determined by the formula

R cr fn (1 + 2)

RO

with a coefficient C equal to 0.3-0.8, the product after dressing better preserves the resulting shape: the strain value is 1.2–7 times less than that of similar products after dressing by a known method (0.3–1.8 mm instead of 2.2 mm).

Example 2. Workpieces with the characteristics of Example 1 are edited, but with different curvature, both in the interval of values equal to 0.07 to 2.5 values of curvature with maximum elastic bending, and with curvature outside this interval.

12142674

All these blanks are subjected to preliminary plastic bending in the direction opposite to the initial curvature, along the radius defined by the formula

R 0,43 RO-In (1 + 2 -)

RO

Then the workpiece is subjected to editing by a known method.

Straightened blanks are ground at an outer diameter of up to 45 mm. In the initial state, similar blanks are edited by a known method and ground to a diameter of 45 mm.

Editing parameters and characteristics of finished products are given in table 2.

From the data table. 2 it follows that the workpieces, the curvature of which is 0.07-2.5 of the curvature at maximum elastic bend, after editing by the proposed method, have an improved quality, expressed in increased resistance to subsequent processing: after machining, the curvature of the products is characterized by deformation 0.9-2.9 mm, while similar products after editing by a known method have a deformation of 1.3-2.2 mm, which is 1.1-2.8 times higher. Outside the set interval, for example, if the curvature of the blanks is

0.05 or 3.33 curvature values at

the maximum elastic deformation, the proposed method does not provide an increase in the quality of products compared to the known one, since a favorable redistribution of internal stresses in the blanks is ensured.

Using the proposed method of editing elongated blanks

and details ensures reliable preservation of the obtained sizes and shapes of products when working with various temperature regimes, including and at elevated temperatures; an exception

intermediate straightening operations from the manufacturing process; povyshenie product life and reducing the deformation of products during subsequent machining and operation.

Table 1

Claims (1)

METHOD FOR EDITING PRODUCTS BY PLANE BEND, including the impact on the ends of the curved section of the product of efforts directed perpendicular to its surface during the entire exposure time, and the magnitude of the angles of rotation of the ends of the curved section when exposed to forces is selected depending on the value of the initial curvature in the rectified section, characterized in that , in order to improve the quality of dressing, reduce the deformation of products during further technological processing and operation, before exposure to the ends of the sparks ennogo portion effort perpendicular to its surface, selected portions of products with a curvature, the curvature component 0,07-2,5 products at maximum elastic bending, and subjected to plastic bending in a direction opposite the initial curvature, the radius R of bending, defined by the expression R = (0.3-0.8) R _o tn (1 + 2 | * -), K © where R _o is the radius of the initial curvature.!; Ry is the radius of curvature of the product at maximum elastic bending. > Hi 1 1214267