RU2313416C2 - Method for making hollow thin-wall parts - Google Patents

Abstract

FIELD: plastic working of metal, possibly manufacture of hollow thin-wall parts.

SUBSTANCE: method comprises steps of producing initial blank; calibrating it; then pressing it out and drawing. Near-bottom cylindrical portion of wall and bottom portion are shaped in die. Diameter of said die is less than diameter of part by value of elastic deformation of wall of near-bottom portion of part.

EFFECT: improved quality of ready part.

4 dwg, 1 ex

Description

The invention relates to the processing of metals by pressure, in particular to the technology of cold forming, and can be used, for example, in the manufacture of cases of telescopic racks of vehicle suspensions (reservoirs of shock absorbers).

A known method of manufacturing hollow parts having a wall and a bottom, including cutting blanks, calibration, extrusion, drawing and forming the bottom cylindrical part of the wall and the bottom part (see patent SU 1807914 A3, B21K 21/04. 04/07/1993).

According to this method, the initial billet obtained by cutting the bar is subjected to calibration in the matrix by the action of a punch. In the next shaping step, the semi-finished product is extruded and then the drawing operation is performed with thinning of the wall.

The disadvantage of this method is the reduced quality of manufacturing parts, due to the instability of the geometric dimensions of the bottom part during deformation of the workpiece due to the displacement of metal into the bottom of the part with the formation of the protrusion.

Another disadvantage is the lack of straightness of the wall and the bottom part of the part in the deformation section during extrusion of the bottom with the formation of the internal profile due to the compressed-stretched volumetric stress state of the bottom part of the part during its deformation (Fig. 1).

The deviation from the straightness of the outer surface of the bottom part in the deformation section during the extrusion of the bottom with the formation of the inner profile is due to the presence of a technological gap Z between the inner diameter of the extrusion matrix and the outer diameter of the workpiece for free entry of the latter into the matrix, which leads to the formation of a convex bottom part on the outer surface "A" (figure 2).

This embodiment of the part with a bulge in the bottom part is unacceptable due to the conditions of use of the part, for example, when assembling it only from the bottom part with the reciprocal part, for example, with the bracket of the telescopic strut of the shock absorber, therefore, to ensure the straightness of the outer surface of the wall of the part and to ensure the shape of the bottom according to the design its documentation (detail) is subjected to additional processing by cutting, which narrows the technological capabilities of the method.

The objective of the invention in the manufacture of hollow thin-walled parts having a wall and a bottom is to improve quality by ensuring that the finished part along the entire height of the rectilinear outer contour of one diameter, as well as expanding the technological capabilities of the method by eliminating additional finishing operations.

To this end, in a method for manufacturing hollow thin-walled parts having a wall and a bottom, including cutting blanks, calibration, extrusion, drawing and forming the bottom part of the wall and the bottom part, the formation of the bottom cylindrical part of the wall and the bottom part is performed in a matrix having a diameter smaller than the diameter of the part by the amount of elastic deformation of the wall of the bottom of the part.

The sign “the formation of the bottom cylindrical part of the wall and the bottom part is carried out in a matrix having a diameter less than the diameter of the part by the amount of elastic deformation of the wall of the bottom part of the part” is significant, as it allows to obtain a high-quality, straight external contour of the same diameter from the entire height due to exclusion bulges on the outer surface of the bottom of the part.

Figure 1 shows a part made in a known manner, having a deviation from straightness of the outer surface of the bottom part "A", and the area of the lapping operation.

Figure 2 presents the extrusion scheme of the bottom of the part with the formation of the inner profile and the outer bottom part in a known manner.

Figure 3 presents the technological scheme of the manufacturing process of a hollow thin-walled part.

Figure 4 presents the scheme of extrusion of the bottom with the formation of the inner profile and the outer bottom part "A" of the proposed method.

The method is carried out in the following way.

The initial billet obtained by cutting the bar (Fig.3 "a"), is subjected to calibration (Fig.3 "b"). Then produce the 1st and 2nd extrusion (Fig.3 "c" and "g") and two hoods (Fig.3 "d" and "e").

A thin-walled hollow billet (Fig. 3 “e”) having a wall 2 and a bottom 3 is installed on the punch 4 (Fig. 4 is the left side), then the matrix 5 is lowered by the entry part 6 onto the billet 1 and when moving down the punch-ejector 7 deforms the bottom, while voids 8 and 9 are filled, and at the final moment of deformation, the internal profile of the part is formed.

Since the deformation process proceeds under conditions of a compressed-extended bulk stress state and due to a sharp change in the cross section — a sharp transition from a thin wall to a thick one, the phenomenon of elastic deformation is present, therefore, the formation of the wall of the bottom part “A” of the part is carried out in a matrix 5 having a diameter D smaller the diameter of the outer wall 10 by the amount of elastic deformation "h".

When removing the load and removing the part 1 from the matrix 5, the outer bottom surface "A" is springy and the part 1 acquires a rectilinear outer surface (Fig. 3 "g").

An example implementation of a method for manufacturing hollow thin-walled parts in the manufacture of a telescopic rack housing for an OKA automobile.

From a bar (steel 11YUA) with a diameter of 46 mm, in the first cutting operation, a billet with a length of 72 mm is obtained.

In the second operation, the workpiece is calibrated to obtain a semi-finished product in the form of a solid rod 59.1 mm high, having a cylinder in the upper part with a diameter of 56.9 mm and a height of 37.2 mm, turning into a lower conical section with a taper angle of 30 ° and with a diameter of the lower base 46.4 mm.

In the third and fourth operations, the obtained billet is subjected to cold back extrusion, the result is a semi-finished product such as a glass with a bottom thickness of 4.2 mm and a height of 113 mm, having a cavity diameter of 44.5 mm and a stepped outer surface in the form of an upper cylinder with a diameter of 57.1 mm , 99 mm high, turning into a conical surface with a taper angle of 30 °, with a diameter of the lower base of 46.8 mm.

The semi-finished product obtained by backward extrusion is subjected to hoods with thinning to obtain a thin-walled blank such as a cup 345 ± 1 mm long with an inner diameter of 46.55 mm and an outer diameter of 47.85 mm.

In the last operation, by extrusion, the outer bottom part of the wall and the bottom part of the part are formed into a matrix with a diameter of 47.75 mm. As a result, after removing the deformation force, due to the increase in the outer diameter of the bottom part by the amount of elastic deformation, a part with an outer diameter of 47.85 mm and a stepped surface in the form of a cylinder 043.3 mm turning into the lower section with a taper angle are obtained 30 ° with a diameter of the lower base of 13.7 mm

The proposed method for the manufacture of hollow thin-walled parts makes it possible to obtain a high-quality rectilinear outer contour of one diameter from a part. This allows you to expand the technological capabilities of the method by eliminating the additional lapping operation of the bottom part by cutting, which was necessary to bring the outer diameter of the part to one diameter.

Compared with the base object (figure 1), which is taken as a prototype, the proposed method allows to improve the quality of the parts by eliminating deviations from the straightness of the outer bottom part relative to the wall of the part and to expand technological capabilities by extruding the bottom and the outer bottom surface, eliminating the need performing additional lapping operations.

The invention is industrially applicable.

Confirmation is the fact of the manufacture of hollow thin-walled parts (cases of telescopic racks of vehicle suspensions, for example, for the Oka car) at FSUE PA Plant named after Sergo.

Claims (1)

A method of manufacturing hollow thin-walled parts having a wall and a bottom, including cutting blanks, calibration, extrusion, drawing and forming the bottom part of the wall and the bottom part, characterized in that the formation of the bottom cylindrical part of the wall and the bottom part is produced in a matrix having a diameter smaller than the diameter of the part the amount of elastic deformation of the wall of the bottom of the part.

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