RU2576970C1 - Production of deep-profile corrugated membrane - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: round blank is cut from the sheet and barrel-like semi-finished product is drawn therefrom. Then, the corrugated bottom is formed at serial rolling-out with reversing. Note here that it is formed from the periphery to the centre. Note here that at every step the barrel is drawn. Note also that the barrel area and drawing depth are decreased while the male die stroke L is defined by the relationship disclosed in the invention.

EFFECT: higher quality of membranes owing to eliminated folding.

7 dwg

Description

The invention relates to the processing of metals by pressure, in particular to the production of a radially corrugated membrane.

Radially corrugated membranes are widely used in military equipment. In particular, the corrugated membrane is used as an actuating element in a device for implementing the method of transforming the aft compartment of an artillery shell in flight [RF Patent No. 2478183 in class F42B 10/38 “Method for increasing the flight range of an artillery shell and device for its implementation”, publ. 03/27/2013].

A distinctive feature of such a membrane is a sufficiently large relative depth of the corrugation profile:

where H, t - depth and corrugation pitch, respectively.

This circumstance determines the complexity of the manufacturing process of the membrane.

, определяемое из условия отсутствия образования складок на внешнем краю изделия. То есть, изготовление гофрированной мембраны с необходимой относительной глубиной профиля указанным способом невозможно.A known method of manufacturing corrugated membranes is given in [RF Patent No. 2292532 in class G01L, H04R "Method for the manufacture of membranes for elastically sensitive elements (options)", publ. January 27, 2007]. A circle is cut from the sheet, which serves as a blank for the membranes. The membranes are corrugated between the rigid punch and the die, and then heat treatment is performed in special gaskets that prevent warping and distortion of the profile. The disadvantage of this method is that there is a strict restriction on the depth of the corrugation

, determined from the condition of the absence of wrinkling at the outer edge of the product. That is, the manufacture of a corrugated membrane with the required relative profile depth in this way is impossible.

From [Zubtsov M.E. Sheet stamping. L .: Mechanical engineering. Leningrad, det. 1980. 431 pp.] The method of reverse (reverse) drawing or drawing with twisting is known. According to this method, the workpiece is installed upside down on the matrix and the punch is pulled from the bottom inward. The metal, in contact with the two exhaust edges of the matrix, receives useful braking, which contributes to obtaining smooth, without folds, products. At the same time, the need to limit the punch during the implementation of this method is not specified separately.

Closest to the claimed technical solution is the method known from [Patent SU 942849 A1, class B21D 13/00 "Method for the manufacture of membranes with annular corrugations", publ. 07/15/1982]. According to the method, a workpiece in the form of a shell of revolution with a section continuously changing in one direction (a cone or a hemisphere) is installed in a matrix having annular ribs configured in accordance with the shape of the obtained membrane and fixed in the machine spindle with a small base. The matrix is brought into rotation and from the center to the periphery the corrugations are formed using a pressing tool fixed in the caliper. To do this, the pressing tool is moved to the matrix in a direction parallel to the generatrix of the inner wall of the corrugation, which is obtained by turning the part of the workpiece by applying a deforming force around the circumference. The circumferential deformations and tensile stresses in the contact zone of the tool with the workpiece are relatively small and do not lead to a loss of stability of the corrugation walls. The disadvantage of this method is the fact that there is a likelihood of wrinkling in a peripheral, in no way fixed zone, where circumferential stresses arise during the whole process due to a decrease in the diameter of the workpiece in the manufacture of membranes with a large relative depth of corrugation.

An object of the invention is to develop a method for producing a part such as a radially corrugated membrane with a relative groove depth of more than 1.00 with smooth, wrinkled-free surfaces based on the extrusion method.

To solve this problem, a method is implemented that includes cutting a round billet from a sheet, forming a semi-finished product from it in the form of a glass, and then the process of forming the corrugated bottom by successive hoods with inverting hoods. In the formation of the corrugated bottom, the corrugations are formed from the periphery to the center, and at each transition, a hood is drawn, the area of which and the drawing depth are reduced, and the stroke of the punch L is determined by the dependence:

where F _n - side surface area drained at this transition of the cylinder;

D is the diameter of the punch at this transition, while the number of transitions of the hood is set equal to twice the number of corrugations.

The invention is illustrated by figures. In FIG. 1 shows a general view of a radially corrugated membrane; FIG. 2 is a diagram for determining the surface area of a part; FIG. 3 - prefabricated in the form of a glass, in FIG. 4 - semi-finished product after the first hood with inversion; in FIG. 5 - semi-finished product after the second hood with inversion; in FIG. 6 - semi-finished product after the third hood with inversion; in FIG. 7 - membrane with two radial corrugations.

The method is implemented as follows.

The number of technological transitions in the formation of corrugations is determined: N = 2n, where n is the number of corrugations.

The original flat blank is cut down. All calculations related to the determination of the geometric parameters of the workpiece, as well as the drawing depth at each transition, are carried out according to the analytical scheme based on the method of equality of areas corresponding to drawing without thinning.

For this purpose, it is necessary to determine the surface area of the part. Based on the analysis of the configuration of the product profile (Fig. 2), its surface area is determined as the sum of the areas of the following elements:

- Central flat area with a diameter of d ₀ :

- adjacent to it an element of a toroidal surface with a diameter of d ₀ and with a generatrix radius a :

, концентрически расположенных друг относительно друга с шагом

:- surfaces 2n of cylindrical elements of height l ₁ and diameter

concentrically spaced relative to each other in increments

:

радиусами образующей a:- surfaces 2n of the bridges between the cylindrical sections, which are toroidal elements with diameters

the radii of the generator a :

- the outer cylindrical surface of the membrane with a height l ₂ and a diameter D:

F = πDl ₂ .

Thus, the surface area of the part is determined by the analytical dependence:

As a result, the diameter of the round billet should be equal

The semi-finished product in the form of a glass is folded into several transitions calculated on the basis of [Zubtsov M.E. Sheet stamping. L .: Mechanical engineering. Leningrad, det. 1980. 431 p.]. The height of such a glass is determined from the condition of equality of its surface area F ₀ . Given the fact that the diameter of the flat bottom of the glass is D, and the curvature is equal to half the area of the outer toroidal lintel, the drawing depth at the last transition of the formation of the glass is:

A corrugated bottom is formed during 2n junctions. The process is carried out on the basis of the method of drawing with inversion (the semi-finished product at each transition is installed on the matrix upside down), while the corrugations are formed from the periphery to the center.

At each transition, the area of the drawn cylinder and, accordingly, the drawing depth are reduced. In order to determine the area of the cylindrical surface stretched at each transition, it is necessary to subtract from the value of F _{0 the} area of the flat bottom of the semi-finished product obtained at this transition (taking into account the rounding on the punch) and the sum of the areas already formed on the previous transitions of the surfaces F ^* :

An example implementation of the method

In the manufacture of a membrane from a sheet with a thickness of 0.8 mm, consisting of two radial corrugations (Fig. 7), this method is implemented as follows.

The number of hood extraction operations is determined:

N = 2 · 2 = 4.

The surface area and circle diameter are determined:

A cup is drawn from a cut-out circle with a diameter of 136.6 mm (Fig. 3), the depth of which is equal to

The glass is installed on the matrix upside down and the first corrugation is pulled out from the periphery (Fig. 4). Thus, as a result of this operation, an external cylindrical surface (length 23 mm on a diameter of 73.2 mm) and the first corrugation from the periphery are formed.

The total area of the formed surfaces in this case will be

elongated cylinder area:

and drawing depth:

At the next (second) transition, the part is turned upside down and the next semi-finished product is formed (Fig. 5), while the drawing depth is determined similarly:

Similarly, the third transition is performed, as a result of which a second corrugation is formed from the periphery (Fig. 6). The drawing depth is determined in the same way as in the previous transitions:

At the last transition, the drawing depth will be 6.4 mm and as a result of the operation, the final part is formed (Fig. 7).

.Thus, this method of manufacturing membranes allows to obtain radially corrugated membranes with smooth, wrinkle-free surfaces and with a relative depth of corrugation

.

Claims (1)

A method of manufacturing a radially corrugated membrane, including cutting a round billet from a sheet, drawing a semi-finished product from it in the form of a glass, and then the process of forming the corrugated bottom by successive transitions with extracts with inversion, characterized in that the corrugations are formed from the periphery to the center when forming the corrugated bottom, moreover, at each transition, the cup is drawn, the area of which and the drawing depth are reduced, and the stroke of the punch L is determined by the dependence

where F _n - side surface area drained at this transition of the cylinder;
D is the diameter of the punch at this transition,
while the number of transitions of the hood is set equal to twice the number of corrugations.

Images