RU2200666C2 - Blank of rigid hollow panel structure - Google Patents

Abstract

FIELD: plastic metal working, welding, possibly plastic working of sheet materials by gasostatic molding in mode of superplastic yielding of material. SUBSTANCE: blank includes placed between two boards filler in the form of two sheets mutually joined by intermittent welded seams and passing along perimeter sealed welded seam. Inlet for supplying gas to cavity formed by filler sheets is connected with filler. Additional gas inlet is provided for supplying gas to cavity formed by board sheets and filler. Sealing welded seam joints boards and filler along perimeter. Surface area of cells formed by intermittent welded seam on sheets of filler from periphery towards center of panel changes inversely relative to law defining surface of formed panel structure. EFFECT: enhanced operational reliability of panel structure. 2 cl, 3 dwg

Description

 The invention relates to the processing of metals by pressure, in particular to the mechanical processing of sheet metal by gas-static molding in the superplastic flow mode of the material, and can be used to produce complex profiles with spatial curvature, such as profiles of hollow wings having a hollow panel structure.

 Known designs of blanks for the manufacture of hollow structures of streamlined bodies with spatial curvature of complex shape by molding in a state of superplasticity, which are used when implementing the methods protected in RF patents 2047408 and 2047409, 21 D 26/02, 1995

 Billets are made in the form of a package of sheet parts connected together by a contour through a tight welded joint. The package is equipped with a means of communication with a gas pressure source. After heating the workpieces until superplastic deformations appear, gas is supplied into the cavity between the sheet parts through fittings, which load the workpiece parts with internal pressure. The use of blanks of this shape allows you to make hollow structures with spatial curvature and internal cavities of complex shape.

 However, loading with the same pressure different areas of the workpiece, which must have a different degree of deformation, leads to the fact that there is a need for multi-stage methods of loading, the occurrence of areas of corrugation and thinned sections is not excluded, which reduces the quality of the resulting products.

 Closest to the claimed design in technical essence is the design of the workpiece, protected by RF patent 1531302, B 21 D 26/02, 1994, which is selected as a prototype of the claimed device.

 The design is a blank for a multilayer metal panel containing a filler placed between two sheathing in the form of two sheets interconnected by intermittent welds and a perimeter sealed weld, as well as a gas inlet connected to the filler to supply gas into the cavity formed by the sheets filler, while the casing and sheets of filler are made with a seam zone, and the gas inlet is located in the seam zone of the latter, while the workpiece is equipped with an additional a gas inlet for supplying gas to the cavity formed by the filler and casing made in the form of a fitting made of heat-resistant material located in the access zone perpendicular to the surface with a flange with an end face facing surface, a pressure sleeve with a conical end face, mounted on the fitting, the fastening element of this sleeve and the housing washer of plastic material mounted coaxially with the fitting between its flange and the conical surface of the pressure sleeve and a single cone by welding along the perimeter of a large base with a single skin, and in the said skin and the filler sheets there are holes coaxial with the nozzle of the additional gas inlet forming a bypass channel, the main gas inlet for supplying gas to the filler cavity is made in the form of a perpendicular plane of the fitting billet, pressure sleeve and its mounting element, similar to an additional gas inlet, as well as two conjugated to each other and located between the fitting flange and the pressure sleeve conical washers made of plastic material, while one sheathing and a filler sheet conjugated with it have openings coaxial with the fitting of the main gas inlet, one of the conical washers of the latter is connected via an annular tight welded seam to the inner surface of the sheathing, and the other to the surface facing it the filler, the filler sheets are additionally interconnected by a collector weld located around the bypass channel, and the casing and filler are fastened together along the perimeter the workpiece is sealed by a weld.

 Such a constructive implementation of the workpiece allows you to produce a rigid hollow panel structure used in the form of hollow wings, wing sections, in which the dimensions of the cavity vary in different areas of the wing of the product.

 However, the presence of a uniform grid of intermittent welds leads to the fact that the entire flat surface of the workpiece is divided into cells of equal area. The cavities obtained on these surfaces after molding must have different volumes. This leads to the fact that the deforming force generated at different parts of the surface of the filler during molding is different, which will lead to a significant difference in thickness of the filler wall and can lead to a decrease in the reliability of the wing during operation.

 The claimed invention solved the problem of increasing the reliability of the structure made of the workpiece, while ensuring high strength.

 The problem is solved in that the workpiece for a rigid hollow panel structure, containing a filler placed between two sheathing in the form of two sheets interconnected by intermittent welds and a perimeter sealed weld, as well as a gas inlet connected to the filler to supply gas into the cavity formed by the aggregate sheets is provided with an additional gas inlet for supplying gas to the cavity formed by the aggregate and the casing, the aggregate sheets are interconnected by an annular according to the invention, the area of the cells formed by the intermittent weld on the filler sheets from the periphery to the center of the panel is made according to the law, opposite to the one that describes the surface that forms the welded seam, and the lining and the filler are bonded to each other panel structure. In one design embodiment, the area of cells from the periphery to the center of the panel is made to vary according to the law of cosine, because the surface forming the panel structure is described by the law of sine.

 The possibility of solving this problem is due to the fact that the implementation of the cell area in the reverse law will allow for approximately equal volumes in the cells, which will create conditions for a more uniform load on the filler walls during molding in various areas, both in the narrowed part and in the most extended hollow area and exclude the formation of defects in the form of thickness variation of the walls, undercuts and others.

 The presence of distinctive features from the prototype features allows us to conclude that the claimed design meets the criterion of "novelty."

 In the search process, no technical solutions were found containing features similar to the distinguishing features of the claimed design, which allows us to conclude that the claimed design meets the criterion of "inventive step".

 The proposed design is illustrated by the drawings shown in figures 1-3.

 Figure 1 shows the view of the workpiece before assembly.

 Figure 2 shows a view of the workpiece after molding.

 In FIG. 3 shows a graph of the distribution of deformations, 1 - prototype, 2 - the claimed device.

 The blank contains casing 1 and 2 in the form of flat sheets, between which there is a filler in the form of sheets 3 and 4.

 The filler sheets are interconnected by intermittent welds 5, forming a pattern of flat cells 6. To supply gas to the cavity formed by the filler sheets 3 and 4, the main gas inlet is installed 7. To supply gas to the cavity between the casing 1 and 2 and the filler, the workpiece is provided additional gas inlet 8. The weld 9, made around the perimeter of sheets 3 and 4, creates a sealed package inside the filler. A sealed weld 10, made around the perimeter of the skin 1 and 2, creates a sealed package of the entire workpiece.

 For the manufacture of parts of complex shape with a rigid panel structure that forms complex curved cavities, the workpiece is first assembled, for which sheets of aggregate sheets 3 and 4 are connected by an intermittent weld, forming a pattern of different-sized flat cells. The type of pattern of the cells is determined depending on the shape of the cavity that will be formed under the cell area. Cells having a large height will have a smaller area to ensure an equal volume of the cavity, and cells located on the periphery of the cavity and having a small height will have a large area. Cells of close volume will provide similar pressure, which will prevent increased thinning of the filler walls in the cells observed during the formation process, where a significant change in volume per unit cell area occurs. Then, the aggregate sheets are joined with a hermetic weld along the perimeter of the aggregate packet, the gas inlet fitting 7 is installed. Sheathing sheets 1 and 2 are installed outside the aggregate sheet packet, covering the latter.

 The assembly is sealed by performing a weld along the perimeter of the sheathing sheets. To supply gas between the sheets of sheathing and aggregate, an additional gas inlet is installed 8. The assembled billet is installed in a forming tool (not shown in the drawings). They provide gas supply to the fittings 7 and 8, create a preliminary pressure both between the casing and the aggregate, and between the aggregate sheets. The billet is loaded into the furnace and heated to the temperature of forming. When the forming temperature is reached, the pressure begins to gradually increase, and the pressure in the aggregate should always be higher than the pressure between the skin and the aggregate. After molding, the pressure between the casing and the filler is reduced to atmospheric pressure, and the pressure in the filler is increased to a value corresponding to the pressure required for diffusion welding. Then carry out the specified exposure of the workpiece.

Example
At the institute, during the development of the design of the hollow panel structure, blanks for cladding and for aggregates were cut from a sheet of VT-14. A package of aggregates was assembled from two sheets, a fitting was welded to them, the package was sealed around the perimeter with a welded seam, then a pattern of cells was welded using intermittent welds. The cell sizes were provided depending on the height of the material in the cavity under the cell, providing an approximate equality of volumes. When welding, the corners of the cells were located at the place of welding, and the common faces of the cells had the appearance of dihedral angles. In the zone of contact of the side faces when forming the panels, windows were formed sufficient for the passage of gas. The presence of windows of sufficient area ensured the normal formation of cells over the entire area of the panel. A package of aggregates was assembled together with cladding covering the package, a fitting was welded, and the entire assembly was sealed by creating a weld along the assembly perimeter. The welding seam was positioned so that after laying the bag in the die tooling, it would be outside the working space of the tooling. After laying the assembly in the die tooling, the fittings were connected to the gas lines, the assembled tooling was placed in a furnace heated to a temperature of 860 ^o C. Superplastic molding was carried out by feeding argon into the cavity between the skin and the aggregate package, then pressure was applied between the aggregate sheets and the pressure in the cavity between the skin was removed. Excerpted, maintaining the pressure between the sheets of aggregate for 30 minutes. In the process of design development, a stress diagram was taken during molding of a part with equal cell areas (as in the prototype), the stresses in the molded wall in the cells, where a larger cavity volume had to be formed over an equal area, were significantly larger than in cells where the cavity volume smaller (see figure 3, line 1).

 When molding approximately equal volumes during the implementation of the claimed design, the stresses in the filler material do not have significant differences (see figure 3, line 2). The resulting design eliminates significant wall thickness, defects in the weld in the cells, thinning of the stiffeners created in the cavity by the filler, which increases the reliability of the structure.

Claims (2)

 1. A blank for a rigid hollow panel structure, comprising a filler placed between two sheathing in the form of two sheets interconnected by intermittent welds and a perimeter sealed weld, a gas inlet connected to the filler to supply gas into the cavity formed by the filler sheets, an additional gas inlet for supplying gas into the cavity between the sheathing sheets and the filler, sealing the weld, fastening the sheathing and perimeter filler, characterized in that the area is to, formed by a discontinuous weld on the filler sheets from the periphery to the center of the panel, made changing according to the law, the opposite of that which describes the surface forming the panel structure.  2. The blank according to claim 1, characterized in that the area of the cells from the periphery to the center of the panel is made varying according to the law of cosine.

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