Method of forming parts of moulded-welded shells of spherical and elliptical shape

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming. Proposed method consists in consecutive local clampings in several passes. In first pass, spherical surface is produced with curvature radius equal to maximum preset radius on entire surface of sheet billet. Here, used is round female die and spherical male die. In second pass, sheet billet section with smaller curvature radius is drawn using annular female die and spherical made die. Working radius of said male die varies with drawing radius, with due allowance for spring back of billet and its thickness and depends upon Gauss curvature of part surface: Note here that where Rd is drawing radius, m; R1 is preset transverse radius of billet central surface, m; R2 - is preset lengthwise radius of sheet billet central surface, m; K is double Gauss curvature of billet central surface, 1/m2. In third pass, spherical make die is used with working surface radius proportional to preset transverse radius R1 with due allowance for spring back and thickness, as well and prismatic female die.

EFFECT: reduced residual strain and thinning.

2 cl, 2 dwg

 

The invention relates to the forming of metal parts pressure, in particular to the production of a torispherical and ellipsoidal elements of stamped shells with double curvature surface.

Known methods of forming double curvature components based on application of methods of hot stamping and cold flexible method of successive local taps (PLN) using universal or special stamps (Moshnin E.N. Flexible, stretch-forming and straightening presses, Meters, motor cycle", 1959; Kuklin O.S, Brooke MB Technology and equipment for forming thick-walled shells and their elements, L, CRI "RUMB", 1986).

A known method of forming products of double curvature of the sheet metal by A.S. 1616746, including shaping for the two transitions, the first of which impart a curvature in one direction, and the second final shape, and forming on the first transition is carried out in the direction of maximal curvature of the product, providing a curvature equal to the difference between the largest and smallest curvature of the product, and the second transition get the final shape. Shaping produce a spherical tool, having a curvature corresponding to the smallest curvature of the product. However, to use the above method of forming the mu who needs to have a lot of large stamping equipment, and in some cases to apply the hot bending operation.

Closest to the claimed technical solution to the technical essence and the achieved result is a method of forming the double curvature components items torispherical shells under the patent of the Russian Federation No. 2194587, including the shaping of the workpiece consecutive mouse clicks for the two transitions, the first transition on the sheet blank to receive the spherical surface and tore part of the surface with a given radius of curvature in the latitudinal direction, and the second tore a part of the surface with a given radius of curvature in the meridional direction, with both transitions formation starting from the wide end edge of the workpiece.

However, as demonstrated by work experience in the use of this method of forming the item, acquiring the specified form, has a high level of residual stresses and thinning, which requires a subsequent heat treatment after bending or forming in a hot state that the complexity of the process and the accuracy of the details give the worst 3-4 times the results than when cold bending.

The present invention is to develop a method of forming double curvature components, allowing to obtain high quality items while snizeni the complexity and intensity, as well as reducing the metal snap.

The use of the invention will provide the technical result consists in a greater uniformity of deformation of the sheet during bending and, consequently, to reduce the level of residual stresses and thinning.

The task can be solved, when in accordance with the proposed method of forming parts of stamped torispherical shells and elliptical forms the sheet-metal part formed by the method of successive taps for multiple transitions. However, unlike the prototype on the first transition receive the spherical surface with radius of curvature equal to the greater of the specified radii across the surface of the workpiece, which use a punch with a working surface of the spherical shape (hereinafter - spherical punch) and the matrix in the form of a ring with a working surface of a spherical or conical shape (hereinafter - ring matrix). On the second transition are stretching the part of the sheet-metal part, which has a smaller radius of curvature, while the use of the ring matrix and spherical punch, the radius of the working surface of which is proportional to the radius of the drawing with regard to the springback of the material and thickness of the workpiece and depends on the Gaussian curvature of a given surface details:

inis the radius of the drawing, m;

R1- set the radius of the middle surface of the plate part in the meridional direction, i.e. in the direction of the generatrix (hereinafter transverse radius), m;

R2- set the radius of the middle surface of the plate part in the circumferential direction (hereinafter longitudinal radius), m;

K is the Gaussian curvature of the middle surface of the plate part, 1/m2.

On the third transition for bended form neognathae part of the sheet-metal part in the meridional direction using spherical punch with the radius of the working surface, is proportional to a given transverse radius R1considering springback, and the matrix in the form of a prism with a cylindrical recess (hereinafter referred to prismatic matrix).

In the particular case of the proposed method for final finishing details on the fourth transition use a stamp, comprising a punch and die working surface which corresponds to the internal and external surface details with regard to the springback of sheet blanks in the circumferential direction, as well as its thickness. However, as shown by experimental work, for parts, wall thickness over 40 mm, subject to the technology in the first three transitions fourth transition may not be necessary.

Thus, in the proposed method, the surface plate part receives the specified double (Gauss is Wu) curvature* after the second transition and does not require further extraction. The third transition is brought to a specified radius, only tore a part of the sheet-metal part in the meridional direction, i.e. they perform the bending curvature in one direction without changing the dual (Gaussian) curvature of the surface plate part. Therefore, the curvature of the surface plate part in the circumferential direction becomes a desired value while receiving a given curvature in the meridional direction, which significantly reduces the complexity of the process while improving the quality of the finished product, and the implementation of formation for several transitions makes it possible to reduce deformations and thinning of the sheet workpiece in the process of its formation.

* The curvature is the reciprocal of the curvature radius.

The whole process is flexible on the most time-consuming the first and second stages of morphogenesis can be implemented on a single die for forming spherical parts, comprising a spherical punch with interchangeable nozzles and annular matrix. This allows to solve the problem of reducing the complexity of the process of forming and metal bending (die) snap-in.

The invention is illustrated by the scheme shown in figure 1 and 2.

1 shows a diagram of forming torispherical details on the second transition, i.e. when drawing the torus sleeve part foxes the OIC procurement. Leaf harvesting (petal) torispherical shape 1 is specified radii: the same radii Rmaxin the latitudinal (district) and the meridional direction in the spherical part of the plate part and the radius Rminin the meridional direction in the torus sleeve side plate part. Radius values in the latitudinal direction in spherical and torus sleeve parts differ slightly.

The forming plate part 1 (figure 1) on the first and second transition is carried out in a universal stamp, including the punch 2 (figure 1) with a spherical surface and an annular matrix 3 (in figure 1 the matrix has a working surface of a spherical shape). The radii of curvature of the working surface of the punch Rpand the matrix Rmless than the specified radius of the sphere of procurement of Rmaxon the first transition and range hoods RBon the second transition by an amount equal to pruginin (elastic aftereffect) workpiece material with regard to its thickness.

Figure 2 shows the scheme of forming torispherical details on the third transition, when do pogibko the torus sleeve side plate part in the meridional direction, i.e. in only one direction using a stamp, comprising a spherical punch 2 (figure 2) and prismatic matrix 4. Pogibko sheet 1 exercise local serial pressed the s to achieve a given radius R minin the meridional direction. In the circumferential direction sheet item is straight and gets the specified radius of curvature in the circumferential direction while receiving a given radius of curvature in the meridional direction.

It should be noted that the radius of curvature of the working surface of the spherical punch on the second transition is chosen smaller than the first and the third transition is smaller than the second, i.e. decreases as the forming plate part.

In the particular case on the latter, as a rule, the fourth transition adjustments are performed shaped sheet-metal part in the bulk are specially manufactured for forming this sheet details the stamp, consisting of a punch and die working surface which repeats the specified form of the sheet-metal part with regard to the springback and the thickness of the sheet stock to adjust the degree of drawing and correcting any skew in the sheet-metal part. Note that this step is not required if flexible sheets developed by the company.

Experimental verification of the proposed method of forming carried out on a regular torispherical petals of steel AK-SU thickness 45-80 mm in OJSC "sevmashpredpriatie". The proposed method is carried out on a hydraulic press with a force of 1500 cu 2000 cu. The sheet-metal part was molded in a cold state, PR is more than three transition. After the second transition plate stock received the required hood, the corresponding dual (Gaussian) curvature of the surface, and after the third transition is finalized. At the first transition of the received spherical surface, the second surface with a given dual (Gaussian) curvature, the third transition tore a part of the surface with a given radius of curvature in the Meridian and at the same time the circumferential direction. With proper operation of all three transitions of the form sheet parts after the third transition met.

Forming at all transitions in successive local presses. All transitions were performed in the cold state of the metal and, as a rule, without heat treatment.

Compared to another possible method of manufacture of such parts - hot stamping, the proposed method allows to reduce in 3-4 times the complexity and cycle parts manufacturing, to ensure harmless and less dangerous working conditions of gershikov, to eliminate or substantially reduce metal loss due to intoxication. The measured strain values in 2-2,5 times lower than during the hot forming, which allows to increase the dimensions of the molded parts and to perform image forming in a cold state without subsequent heat treatment or with mini the actual displacement of the heat treatment in the form of high holidays.

1. Method of forming parts of stamped torispherical shells or elliptical shape by successive local presses a few transitions, characterized in that the first transition receive the spherical surface with radius of curvature equal to the greater of the specified radii on the entire surface of the sheet workpiece, using the ring matrix and spherical punch, the second transition carry out the hood part of the sheet stock, having a smaller radius of curvature, using the ring matrix and spherical punch, the radius of the working surface of which is proportional to the radius of the drawing with regard to the springback of the workpiece material and its thickness and depends on the Gaussian curvature of a given surface details:
while,
where RBis the radius of the drawing, m;
R1- set transverse radius of the middle surface of the plate part, m;
R2- given the longitudinal radius of the middle surface of the plate part, m;
K - dual of the Gaussian curvature of the middle surface of the plate part, 1/m2on the third transition for bended form neognathae part of the sheet-metal part using a spherical punch with the radius of the working surface, is proportional to a given transverse radius R1with regard to spring the Oia and the thickness of the sheet, and prismatic matrix.

2. The method according to claim 1, characterized in that for final finishing sheet parts for the fourth transition use a stamp, comprising a punch and die working surface which corresponds to the internal and external surface details with regard to the springback of sheet parts in the circumferential direction.



 

Same patents:

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