RU2122479C1 - Method for bending trough cross section parts - Google Patents

Abstract

FIELD: plastic metal working, namely manufacture of high-accuracy parts formed of sheet blanks. SUBSTANCE: method comprises steps of clamping blank edges to movable members of die and their common motion - at first along axis of die set until formation of necessary inclination angles of part walls and then - in opposite direction until providing necessary height of part cross section at keeping formed angles. EFFECT: enhanced accuracy of bent parts, lowered forming efforts. 1 dwg, 1 ex

Description

 The invention relates to the processing of metals by pressure and can be used to improve the accuracy of sheet-stamped parts.

 A known method of bending in a stamp parts such as brackets [1], in which move the edges of the workpiece in the direction of the axis of the stamp and at the same time bring together the moving elements of the matrix, which reduces the thinning of the stamped material that occurs when it is pulled over the edges of the matrix. This method does not allow to create sufficient tension in the walls of the parts of the trough-shaped section and eliminate their non-flatness.

 A known method of bending parts of a trough-shaped section in a stamp, including clamping the edges of the workpiece to the movable elements of the matrix and their joint movement [2].

 The technical problem that the claimed invention solves is the exclusion of non-flatness and springing during stamping of trough-shaped parts, reduction of stamping force.

 The problem is achieved in that in a method of bending parts of a trough-shaped section, including joint movements of the edges of the workpiece and matrix elements, these movements are carried out in the direction of the axis of the stamp until the required angles of inclination of the walls of the part are formed, and then in the opposite direction to obtain the desired section height, s preserving previously formed corners.

 The invention is illustrated by the drawing, which shows the workpiece before and after bending, as well as some elements of the stamp.

 The method is as follows. The workpiece is placed on the punch 1 and clamps 2. When lowering the upper part of the stamp, the elements of the matrix 3 press the edges of the workpiece, overcoming the counter-pressure of the pushers 4 of the buffer. The further course of the press slider causes the workpiece to bend along the edges of the punch and matrix elements and move its edges in the direction of the stamp axis. Together with the edges of the workpiece, the clamps and clamps move along the guide planes of the matrix, since the friction forces that prevent their movement are less than the forces required to pull the material through the edges of the matrix elements.

 Upon reaching the required angle of inclination of the walls of the part, the direction of movement of the matrix elements and clamps changes, they are moved from the axis of the stamp, along with them the edges of the workpiece move. In this case, the walls are stretched and the walls of the part are eliminated without changing their tilt angles. The stamping force when implementing the proposed method is less than when calibrating the part walls with normal pressure of punches and dies of a traditional design.

 Example.

 Sheet blanks with a thickness of S = 1 mm must be bent into a trough-shaped profile with a length of L = 500 mm, the width of each of the clamped edges is B = 40 mm, and the internal bending radii are r = 2 mm.

Подставляя коэффициент трения μ = 0,1 и прочие значения величин, входящих в формулу, получаем σ = 1,1σ_S. Следовательно, стенки детали в конце гибки получат пластическое растяжение. При заданном давлении прижима p = 0,1σ_S, напряжении текучести σ_S = 200 MПa и размерах детали усилие штамповки составляет
P = 2BLp + 2SLσ_Scosα = 970 кH.
Увеличив коэффициент трения при зажиме краев заготовки до 0,2, можно штамповать данную деталь с давлением прижима p = 0,05σ_S. Усилие штамповки составляет в этом случае 570 кН.We set the pressure value p = 0.1σ _S. According to the formula E.A. Popova tensile stresses in the walls of the part at the end of bending in the case of pulling the material through the edges of the matrix are

Substituting the coefficient of friction μ = 0.1 and other values of the quantities included in the formula, we obtain σ = 1.1σ _S. Therefore, the walls of the part at the end of bending will receive plastic tension. For a given clamp pressure p = 0.1σ _S , yield stress σ _S = 200 MPa and part dimensions, the stamping force is
P = 2BLp + 2SLσ _S cosα = 970 kH.
By increasing the coefficient of friction when clamping the edges of the workpiece to 0.2, it is possible to stamp this part with a clamping pressure p = 0.05σ _S. The stamping force in this case is 570 kN.

Compared with the proposed method, dressing at the end of bending the part walls with normal pressure requires more effort. The dressing pressure of the thin material according to the reference data is 5-10 kg / mm ² . The deviation of the thickness of the material from the nominal value affects the quality of the edit by normal pressure and does not affect the implementation of the proposed method.

Claims (1)

 A method of bending trough-shaped section details in a stamp, including clamping the edges of the workpiece to the movable matrix elements and moving them together, characterized in that the joint movement is carried out in the direction of the axis of the stamp until the required angles of inclination of the wall of the part are formed, and then in the opposite direction, while maintaining formed angles to obtain the desired section height.