RU2222402C2 - Method for making symmetrical shapes - Google Patents

Abstract

FIELD: plastic metal working, possibly small-batch production of symmetrical wide-flange bent shapes, mainly with coating. SUBSTANCE: method for making symmetrical shapes during successive transitions for bending up members of shape in rolls of shape bending mill comprises steps of additionally bending up flanges in interstand space by 3 - 4 degrees; during first transition in mean portion of bent up flange forming groove (to be straightened) turned outside by its convexity and having constant joining radiuses; during second transition bending up flanges while straightening groove; in interstand zone at least between two successive transitions simultaneously with additionally bending up flange performing cross bending of said flange in such a way that its convexity is turned outside; then straightening flange during next transition in closed roller grooved pass; determining height of straightened groove according to dependence given in description of invention. EFFECT: reduced degree of non-planeness of flanges at integrity of coating, lowered number of transitions, enlarged manufacturing possibilities, lowered production cost. 4 dwg, 1 ex

Description

 The invention relates to the processing of metals by pressure and can be used in small-scale production of symmetric wide-shelf (with a width of flexible shelves of more than 40 thicknesses of the initial workpiece) of bent profiles, mainly coated.

 The known method (ed. St. 1754267 USSR of 08.15.92, BI 30, class B 21 D 5/06. The method of profiling mainly channels. // Antipanov V.G., Kirillov R.I., Pakhomov N.T. and Kochubeev V.N.), which consists in bending the profile elements along transitions with a technological bend of the profile element in one of the transitions and its subsequent straightening in nine transitions, the technological bending being performed in the third transition and the straightening in the last two.

 The disadvantage of this method is the impossibility of manufacturing wide-shelf thin-walled profiles due to the occurrence of edge waviness in a limited number of transitions characteristic of the equipment used for small-scale production (in the description of this analogue in all three examples of the method, the relative width of the shelf did not exceed 17 with a wall thickness of not less than 5 mm in the manufacture of the profile in 9 transitions, and the edge waviness was a limitation). In addition, the method cannot be implemented, for example, on six-stand tools of the GPS family of the FSUE Ulyanovsk NIAT, intended for small-scale production of profiles, due to the limited number of transitions.

Closest to the proposed invention is a "Method for the manufacture of symmetrical profiles" (ed. St. 1719124 of the USSR dated 03.15.92, BI 10, B 21 D 5/06 // Antipanov V.G., Kirillov R.I., Gridnevsky V. I. and Kirillov A.S.), according to which the manufacture of symmetrical profiles is carried out by sequentially bending the bending of the profile elements in the rolls of the bending machine with additional bending of the shelves in the interstand space by 3-4 ^o .

This method is adopted as a prototype. The prototype and the claimed invention have the following similar essential features:
1. The bending of the shelves is carried out by transitions in rolls of a profiled machine.

2. In the space between the stands produce additional folding shelves 3-4 ^o .

 The disadvantage of this method is the low quality of the products in the manufacture under conditions of a limited number of transitions of wide-shelf profiles with a wall thickness of not more than 1 mm, due to the presence of defects such as edge waviness and violations of the coating.

 In conditions of small-scale production (with frequent changes in production facilities) it is economically feasible to use compact equipment and the production technology of long-length wide-shelf profiles with a minimum number of transitions, providing for relatively large bending angles per transition. However, it is known (IS Trishevsky, ME Doctors. Theoretical Foundations of Profiling. - M .: Metallurgy. - 1980. - 288 p., P. 76) that in the manufacture of wide-shelf profiles in rollers at large bending angles waviness due to large deformations of the peripheral sections of the foldable shelves, which is a practically unrecoverable profile defect. It is also known that the distribution of normal contact stresses along the width of the foldable shelf in caliber from the side of the enclosing roller has the form of a concave curve indicating the uneven distribution of the acting forces and stresses in the contact area (Trishevsky I.S., Doctors M.E. Theoretical basis for profiling. - M.: Metallurgy. - 1980. - 288 p., P. 221, Fig. 122-a). Due to the difference in linear velocities on the surface of the conical sections of the rollers, a slip occurs between the roller and the workpiece, which leads (with high contact forces) to a violation of the integrity of the coating of the workpiece or risks, which also affects the quality of the profile.

 The technical problem solved by this invention is to improve the quality of the profile by reducing the flatness of the shelves due to edge waviness and violation of the integrity of the coating, as well as reducing the number of transitions by increasing the rigidity of the bent elements while maintaining the accuracy of the linear dimensions of the profile.

 This problem is solved by a combination of existing and new significant features.

In the known method, improving the quality of the profile, in particular, the accuracy of the linear dimensions is ensured by the fact that the production of the profile is carried out by sequentially bending the bending of the profile elements in the rolls of the bending machine with additional bending of the shelves in the interstand space by 3-4 ^o .

где

- относительная высота рифта

;

- относительный радиус сопряжения элементов рифта

;

- относительная ширина полки

;
S₀ - толщина заготовки.A feature of the proposed method is that at the first transition in the middle part of the foldable shelf, the removable rift is formed by convexity outward with constant mating radii; at the second transition, the shelf is bent with straightening of the rift, and in the interstand space between at least two of the subsequent transitions, simultaneously with the additional folding of the shelf, it is transversely bent outward and then straightened in the next transition in a closed roller gauge, and the height of the rift to be removed is determined according to the formula:

Where

- relative height of the rift

;

- relative radius of conjugation of rift elements

;

- relative width of the shelf

;
S ₀ - the thickness of the workpiece.

The essence of the proposed method consists in the fact that when bending the shelf in the second transition to an angle of 25-40 ^{o, the} rigidity of the shelf is increased due to the rift, reducing its tendency to lose stability in the form of edge waviness. This makes it possible to increase the bending angles in comparison with known methods. The low stiffness of the cross section of the entire profile in the interstand space between the first and second transitions (in comparison with the subsequent ones) allows longitudinal deflection and buckling of the bottom, softening the molding mode. Moreover, due to the straightening of the rift in the second transition, the distribution of normal contact forces along the width of the shelf becomes more uniform, which helps to prevent coating damage. In subsequent transitions, in order to reduce the deformation of the shelf due to the effect of "winding up" of the flexible shelf on the roller (which substantially depends on the size of the contact zone), additional folding of the shelf is made in the interstand space, while bending it in the transverse direction, for example, using vertical roller or rigid wiring, increasing, on the one hand, the rigidity of the foldable shelf in the current inter-stand space to prevent edge waviness, and on the other, creating conditions for more vnomernogo distribution of contact forces on the shelf width in this caliber in order to avoid damage to the coating. Moreover, the accuracy of the linear dimensions of the cross-section of the profile in comparison with the known methods does not deteriorate: the presence of additional bending and the use of closed gauges guarantee the preservation of accuracy, especially since with small-scale production, the wear of the rolls is usually negligible.

 As additional effects, one can also indicate the expansion of technological capabilities by increasing the range of profiles, including small thicknesses and wide shelves with a coating; reduction of production costs associated with the manufacture, debugging and change of technological equipment; the use of compact equipment, its operation, etc.

 In FIG. 1 is a diagram of the shaping of the channel profile; in FIG. 2 shows plots of normal contact stresses in the prototype and in the proposed method; figure 3 shows the geometric parameters of the rift; in FIG. 4 shows a diagram of the implementation of the angle of folding and the applicable interstand wiring.

h = 2•R(1-cosξ)
где ξ - внутренний угол, соответствующий элементу рифта в обозначениях фиг. 3.The proposed method is implemented on a six-gang roll forming machine GPS-350M6, which also contains a guide and a correct device, as follows. The workpiece is fed into the guiding device, and then into the roller gauge of the first transition (Fig. 1), where rifts are performed with their symmetry centers located in the middle of the future shelf with the parameters defined in the claims. The radii of conjugation of the rift elements R are selected from the conditions of the transition of the workpiece to the plastic state during bending (at R / S ₀ ≈5, where s is the thickness of the workpiece, the radial stress is about 10% of the yield strength, and σ _ρ -σ _θ = from the plasticity condition −σ _s implies that −σ _θ = −σ _s . Here σ _ρ , σ _θ are the radial and tangential stresses; σ _s is the yield strength of the material). This means that the shelf hood in the latitudinal direction is practically absent. From consideration of FIG. 3 follows a system of equations (Gorbunov M.N. Procurement and stamping technology in aircraft manufacturing. M: Mashinostroenie, 1981. - 224 p., P. 51):

h = 2 • R (1-cosξ)
where ξ is the internal angle corresponding to the element of the rift in the notation of FIG. 3.

 By eliminating ξ from the above system, it is easy to obtain an expression for determining the height of the rift used in the claims. The involved flange width 1/3 • b is taken on the basis of considerations of matching the curved section of the stress diagram. So, if the workpiece width for the rift is more than b / 3, the height of the rift becomes too large, which makes it difficult for the profile to enter the roller gauge and re-shape the profile, and with a small width the height of the rift is small and the plastic state of the workpiece in caliber is not achieved: significant springing occurs.

In the second transition, the rift settles (straightening of the shelf), moreover, the contact stresses are aligned in magnitude in accordance with FIG. 2, and in the interstand space after the second transition in the intermediate stand transverse profile bending is performed with simultaneous bending of the shelf by 3-4 ^o using inter-stand wiring (see figure 4).

 Inter-stand wiring (see Fig. 4) is used to bend the profile 1 shelf using rollers 7 mounted on axes rigidly mounted on the slider 5. The slider 5 has the ability to be positioned along the guide 6, pivotally connected to the rack 8, with the help of a screw 3, closed to the guide 6 through the cross member 2. In turn, the cross member 2 is pivotally connected to a tension 4, which can be rotated and fixed in the disk head with a wide groove of the rack 8. The rack was adjusted in height with respect to the surface of the machine table yayut through the gaskets. The rack is attached to the machine desktop with two screws through the holes in the base of the interstand rack.

After the second transition, the bending radius of the foldable flange after the second transition is set so that the magnitude of the deflection of the flange does not exceed the rift value at the first transition for reasons of normal profile entry into the roller gauge (practically the same value of h should be taken). The magnitude of the angle of folding is limited by values of 5-6 ^o , since with a large transverse deflection of the shelf, a break in the stretched edge of the profile is possible. In subsequent transitions, the procedure can be repeated if necessary. The sixth transition is calibrating, and the profile emerging from it passes into the correct device, which creates favorable conditions for calibration in order to balance the stresses.

An example of a specific implementation. According to the proposed method, for six transitions, a channel profile with a section size of 110 • 60 • 0.7 mm is obtained from galvanized steel in the absence of edge waviness. Deplanation of the shelves did not exceed 0.6 mm / m, which corresponds to the conditions for the supply of profiles. No coating disturbances were found. The application of the traditional scheme and the prototype scheme lead to edge waviness with a pitch of 51-72 mm and an amplitude of up to 4 mm when all six stands of the profile bending machine are activated. In addition, on the surface of the shelves were observed dark stripes with a relatively regular pitch at an angle of about 45 ^o to the line of profiling. From the profiling experience at FSUE Ulyanovsk NIAT it follows that at least 8-9 transitions would be required to produce this profile according to the prototype scheme.

 The claimed invention does not adversely affect the state of the environment.

Claims (1)

A method of manufacturing symmetrical profiles by successive bending of profile elements in rolls of a roll forming machine with additional bending of shelves in the inter-stand space by 3-4 °, characterized in that at the first transition in the middle part of the bent shelf, a removable rift is formed by convexity outward with constant mating radii, the second transition, the shelves are bent with straightening the rift, and in the interstand space between at least two of the subsequent transitions simultaneously with the additional oh podgibkoy shelves produce its transverse bending outwardly convex and subsequent straightening in the next transition in the closed roller caliber, and the height eliminates rift determined by the formula

Where

- relative height of the rift

- the relative radius of the elements of the rift

- relative width of the shelf

; S ₀ - the thickness of the workpiece.

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