RU2242320C2 - Method for forming hollow parts of flat sheet blanks and apparatus for performing the same - Google Patents

Abstract

FIELD: plastic working of metals, possibly manufacture of hollow parts, mainly spherical, toroidal and others.

SUBSTANCE: method for forming hollow parts of flat sheet blanks setting constant total thickness of pack in direction of force action upon it; making shaping surfaces on pressure members; at forming spherical, toroidal parts and tore-halves setting thickness value of flat sheet blank and its diameter equal to that of container according to predetermined relations; then realizing first stage of forming procedure by upsetting pack of shaping members with blank and transforming blank in case of hemisphere - into cone semifinished product, in case of tore half - to semifinished product with annular cone cavity having predetermined conicity degree; then removing lower shaping member and pressure member and placing instead of the last spherical or toroidal die with cone inlet edges; drawing respective semifinished product to hemisphere or to tore half by applying pressure at side of upper shaping member. Die of apparatus for forming hollow parts of sheet blanks has inlet cone whose conicity angle is set according to given formula.

EFFECT: improved quality of parts due to elimination of thickness difference.

3 cl, 21 dwg, 1 ex

Description

The invention relates to the processing of metals by pressure and can be used in the manufacture of hollow parts, mainly spherical, toroidal, other forms.

A known method of stamping hollow parts from flat sheet blanks, according to which the force exerted on the workpiece is transmitted through a plastic easily deformable material installed in contact with the workpiece [1].

The disadvantage of this method is the corrugation of the material when stamping thin-sheet parts, which reduces the quality of the manufactured parts.

Closest to the invention in terms of technical nature and the achieved effect is a method of stamping sheet parts, based on the deformation of the workpiece in the package between the forming elements of deformable materials, the total thickness of which with the workpiece is constant in the direction of force impact on them [2]. This method, having wide technological capabilities, has a significant drawback, namely, that the initial thickness of the workpiece varies depending on the angle between the tangent to the wall of the product and the direction of the force acting on the workpiece, and the decrease in thickness can be twice or more.

The method can be implemented in a device for stamping hollow parts from flat sheet blanks containing the upper and lower strikers, punch, die [3]. However, due to the lack of a feed cone on the matrix, it is difficult to control the thickness at the edge of the part.

The technical problem to which the claimed invention is directed is to eliminate the noted drawback of manufacturing hollow parts from sheet blanks according to the prototype and, as a result, to increase the equal thickness and quality of the manufactured parts.

To solve the problem in the known method of stamping hollow parts from sheet blanks, the workpiece is placed in a package between the forming elements of plastic low-melting metal, forming surfaces are performed on opposite surfaces of the forming elements, after which the package is deposited in the container between the pressure elements, and the total thickness of the package is taken constant in the direction of the force acting on the latter, the forming surfaces will be performed on the pressure elements, and the thickness of the flat sheet billet S _o and its diameter D _osf equal to the diameter of the container D _ksf , when stamping parts predominantly spherical and toroidal in shape with a diameter d of the cross section, set according to the dependencies

where D _OSF - the diameter of the flat billet for the manufacture of the hemisphere,

D _CSF - the diameter of the container,

d is the diameter of the cross section of a sphere or torus,

S _o - the initial thickness of the flat workpiece,

S _and - wall thickness of the product,

and for stamping one and a half relevant parameters are set according to the dependencies

where D _from - the outer diameter of the flat billet for the manufacture of one and a half,

D _CT - the outer diameter of the base of the annular cone of the semi-finished product,

D _t - the diameter of the circular axis of one and a half or the distance between the centers of the passage section of the torus,

D _VN - the inner diameter of the flat billet for the manufacture of one and a half.

After that, the first stage of stamping is carried out by settling a package of forming elements with a workpiece, which transforms the latter: for a hemisphere - into a semi-finished product of a conical shape, for one and a half - into a semi-finished product with a ring conical cavity at a taper angle of 2 · α _and = 90 °, then, after removing the lower forming and pressing elements and installation in place of the last spherical or toroidal matrix with tapered inlet edges, the corresponding semi-finished product is drawn into a hemisphere or one and a half pressure from us mold member. In addition, in the device for stamping hollow parts from flat sheet blanks containing the upper and lower strikers, the punch, matrix, matrix is made with an input cone, the taper angle of which is set by the formula

where α _and - the taper angle of the conical semi-finished product to its axis,

E is the degree of thickening of the hemisphere edge for welding,

α _у - taper angle of the annular input edge of the matrix.

The essence of the proposed technical is illustrated by drawings, which depict the various stages of hemisphere stamping:

figure 1 - initial position (before the first stage of stamping),

figure 2 - position before stamping the conical semi-finished product,

figure 3 - position after stamping of the conical semi-finished product,

figure 4 - position before the second stage of stamping of the semi-finished product (after removing the lower forming element from the striker),

figure 5 - initial position before the extraction of the hemisphere,

figure 6 - position before the stamping of the hemisphere,

Fig.7 - position after drawing the hemisphere,

on Fig - position before removing from the working area of the press stamped parts with forming element,

figure 9 - the parameters of the workpiece,

figure 10 - parameters of the conical semi-finished hemisphere,

figure 11 - parameters of the stamped hemisphere,

in Fig.12 - the parameters of the conical semi-finished product for one and a half,

in Fig.13 - the parameters of the stamped one and a half.

The captions for Figs. 14-21 (in the case of stamping with forming elements in the form of flat disks) completely repeat the captions for Figures 1-8, respectively.

A device for implementing the proposed method comprises a press 2 fixed on the table 1 and on the internal slider (not shown conventionally), respectively, lower 2 and upper 3 strikers, as well as a container 5. The punch and die are mounted on the punch and matrix by forming elements 6 and 7, from ductile low-melting metal, the total thickness of which is taken constant in the direction of force impact on it. Elements 6 and 7, after stamping the flat billet 8 into a conical semi-finished product 9, take the form 10 and 11, respectively. The extraction of the conical semi-finished product 9 into the spherical part 12 is carried out by the upper forming element 10 into a spherical matrix 13 with a pusher 14 (drive conditionally not shown), in as a result, the forming element takes the form 16 (Fig.6 and 7), in addition, it should be noted that the forming surface is performed either on opposite surfaces of the forming elements, or on the pressing elements (Fig.14 and 15).

A method of stamping spherical parts as follows. A flat sheet blank 8 is placed between two forming elements 6 and 7 and installed on the lower hammer 2 (figure 1), so that during the working stroke of the press they are inside the container 5 (figure 2). During the working stroke of the press, the lowering upper head 3 first contacts the upper forming element 6 (Fig. 2), and then upsets the bag from a height H _to + H _oc to a height of H _OS , as a result of which a flat sheet blank 8 takes the form under the action of shear deformations conical semi-finished product 9 (figure 3). Remaining on the lower striker 2, the lower forming element 11, together with the lower striker 2 (after raising the outer slider of the press 4), is removed from the working area of the press. In this case, the upper forming element 10 with the conical semi-finished product 9 is held in the container 5 by friction forces (Fig. 4). This ends the first stage of manufacturing parts.

The second stage of the manufacture of the part consists in the extraction of the conical semi-finished product 9 into the hemisphere 12, for which a spherical matrix 13 with an ejector 14 is placed in place of the lower striker 2 (see Fig. 5, the drive is conditionally not shown). The inclusion of the working stroke of the press first leads to lowering the container 5 to the extremely low position and to clamp the conical semi-finished product 9 to the input cone 15 of the matrix 13 (see Fig. 6), after which pressure is applied from the side of the upper striker 3 to the upper forming element 10 from the side of the latter, which draws the conical semi-finished product 9 into the hemisphere 12, while the element 10 takes the form 16 after lowering it to a height h _oc (Fig.6 and 7). The inclusion of the reverse stroke of the press leads to the lifting of the upper striker 3 and the container 5 to an extremely upper position (Fig. 8). This ensures the lifting of the spherical part 12 with the element 16 using the ejector 14 and the subsequent removal of the stamped part 12 with the element 16 from the working area of the press for their subsequent processing, and, if necessary, to change the exhaust matrix 13 to the lower hammer 2.

The above description of the method shows how to make parts such as equal-thickness hemispheres. However, it should be borne in mind that almost all stamped hemispheres are welded into spheres, which leads to a decrease in the strength of the material in the weld by 20-30%. This, in turn, leads to an increase in the flight weight of spherical and toroidal capacities of aerospace engineering. In this regard, the developed method for manufacturing hollow products, as it were, simultaneously solves the noted problem, namely, it provides the production of spherical and toroidal containers with thickened edges, compensating for the loss of strength of the welded spheres and tori in the zone of their thermal influence. For this, at the first stage of stamping, the initial billet in the form of a flat disk 8 (Fig. 9) with a diameter of D _OSF = D _CSF (where D _CSF is the diameter of the container, D _OSF is the diameter of the flat workpiece for manufacturing a hemisphere) by shear deformation is stamped into a two-cone semi-finished product, the wall of which is performed with two taper angles: 2 · α _and is the cone angle of the semi-finished product with its wall thickness S _and = S _o · sinα _and and 2 · α _y is the taper angle of the thickened peripheral zone with the wall thickness S _y = S _o · sinα _y . This allows according to Fig.9 and 10 to determine the thickness of the original flat workpiece S _o according to the formula

S _o = S _and / sinα _and .

The second stamping stage is carried out with a force action from the side of the upper striker 3 on the forming element 10 (Fig. 10), the pressure from the side of which presses the flange part of the semi-finished product to the inlet cone 15 of the matrix 13 and draws it with the formation of a hemisphere along the working surface of the matrix 13, this additional sediment forming element 10 to a height h _oc (Fig.11). After the element 16 with the stamped hemisphere 12 is removed from the press working zone, the latter is machined to obtain its height d / 2 (where d is the diameter of the cross section of the sphere or torus) and for subsequent welding of the hemispheres along their thickened edge sections.

The proposed method of manufacturing hemispheres of two-stage stamping is also applicable for the manufacture of half-and-a-half with thickened edges according to the diagrams in Figs. 12 and 13. First, annular conical semi-finished product (Fig. 12) is stamped with ring forming elements similar to elements 6 and 7 (Fig. 1) with an outer and inner diameter _of D and E _y, and an annular cavity diameter d, which wall thicknesses S _y and S _and operate with the cone angles 2α and _at 2α _and then pressure from the (relatively not shown in Figure 12) of the upper mold member provide rizhim inclined flange portions of the annular semifinished product with subsequent stretch of the walls of the toroidal die surface 13 with a tapered leading edge (13). The stamped one and a half are removed from the working area of the press and subjected to mechanical processing for subsequent welding them into tori along the thickened edge sections.

Based on the analysis of the shaping of the conical semi-finished product with a taper angle of 2 · α _and = 90 ° and a thickness S _and a hemisphere with a cross-sectional diameter d of constant thickness S _and set the diameter of the base of the cone D _to and the initial thickness of the workpiece S _o . From the condition that the lateral surface of the conical semi-finished product F _{v is} equal to the surface of the hemisphere F _and, according to [4], we have

whence we establish the value of the diameter of the base of the conical semi-finished product (at 2 · α _and = 90 °)

Taking into account the allowance for the anisotropy of the stamped material and for some asymmetry in the drawing of the hemisphere relative to its axis, _we take the value of D _ksf

Similarly and with sufficient accuracy for practical purposes, we establish that according to Figs. 12 and 13 for steeply curved half- _tones , the width of the base of the annular conical semi-finished product V _t , the diameter of the container D _kt = D _from and the diameter of the hole in the workpiece D _vn will

where D _from - the outer diameter of the flat billet for the manufacture of one and a half,

D _CT - the outer diameter of the base of the annular cone of the semi-finished product,

D _t - the diameter of the circular axis of one and a half or the distance between the centers of the passage section of the torus,

D _VN - the inner diameter of the flat billet for the manufacture of one and a half.

The taper angle 2α of the thickened section of the flange of the conical semi-finished product is set depending on the hemisphere edge for welding the product E = S _у / S _и = (S _о · sinα _у ) / (S _o · sinα _и ), where

where α _and - the taper angle of the conical semi-finished product to its axis,

α _у - taper angle of the annular input edge of the matrix.

Mold-forming elements should be made of fusible metals, for example, from Wood alloys (T _pl = 60.5 ° C), Goutry (T _pl = 45 ° C), Lipovitsa (T _pl = 70 ° C), D "Arce (T _pl = 140 °) and others [5].

The characteristic of the forming elements in the claims in terms of the fact that "... the total thickness of which is taken constant in the direction of the force acting on the last ...", implies the execution of the forming elements not only as shown in figure 1, but also their use in the form of flat disks with the implementation of the corresponding forming surfaces on the lower and upper strikers (Fig), which in this case play the role of a matrix and a punch, respectively. This embodiment of the forming elements can significantly reduce their total thickness HΣ and, therefore, reduce the weight of the used fusible alloy. In addition, it allows to reduce energy consumption both for their smelting from parts, and for the manufacture of new forming elements. It should be noted that the use of flat disks in the method leads to the conversion of flat strikers in the device into a punch and a die, respectively. In this case, the captions for FIGS. 14-21 remain the same as for FIGS. 1-8, and the description of the invention is continued below.

) устанавливают на матрицу 18 (фиг.14) и при рабочем ходе пресса они находятся внутри контейнера 21 (фиг.15), причем опускающийся пуансон 19 сначала соприкасается с верхним диском 22, а затем осаживает пакет, в результате чего плоская заготовка 24 под действием деформации сдвига принимает форму конического полуфабриката 25 (фиг.19), а оставшийся на матрице 18 нижний формообразующий элемент 27 (после подъема наружного ползуна пресса 20) удаляется из рабочей зоны пресса. При этом верхний формообразующий элемент 26 с коническим 25 удерживается в контейнере 21 силами трения (фиг.17). На этом кончается первый этап изготовления детали, после чего наружный ползун 20 с верхним формообразующим элементом 26 и с коническим полуфабрикатом 25 поднимаются вверх (фиг.17), а нижний формообразующий элемент 27 вместе с матрицей 18 удаляются из рабочей зоны пресса для подготовки устройства к следующему этапу штамповки конического полуфабриката. Второй этап изготовления детали заключается в вытяжке конического полуфабриката 25 в полусферу 28, для чего формообразующий элемент 27 удаляют из рабочей зоны пресса и на место матрицы 18 помещают сферическую матрицу 29 с выталкивателем 30 (фиг.18, привод условно не показан). Включение рабочего хода пресса приводит сначала к опусканию контейнера 21 в крайнее нижнее положение и к прижатию конического полуфабриката 25 к входному конусу 31 матрицы 29 (фиг.19), после чего силовым воздействием со стороны пуансона 19 на верхний формообразующий элемент 26 создают давление со стороны последнего, которое вытягивает конический полуфабрикат 25 в полусферу 29, при этом элемент 26 принимает форму 32 после опускания его на высоту h_oc (фиг.19 и 20). Включение обратного хода пресса приводит к подъему пуансона 19 и контейнера 21 в крайне верхнее положение (фиг.21), что обеспечивает подъем сферической детали 28 с элементом 32 и последующее удаление отштампованной детали 28 с элементом 32 из рабочей зоны пресса для их последующей обработки и при необходимости к смене вытяжной матрицы 29 на матрицу 18. Для предложенного способа штамповки полых деталей применение легкоплавкого сплава по [5] имеет ряд технологических преимуществ. Во-первых, он дешевле других сплавов, так как содержит меньше висмута, а дорогостоящий компонент - олово - в нем отсутствует. Во-вторых, температура плавления этого сплава ниже 100° С и, следовательно, для выплавления этой рабочей среды из отштампованного изделия и для получения новых формообразующих элементов можно применять ванну с кипящей водой. В - третьих, содержание в этом сплаве цинка в 1,2 и 3% обеспечивает твердость по Бринеллю соответственно в 13,9, 15,1 и 17,0 НВ, что позволяет применять этот сплав при штамповке полых изделий с широким диапазоном механических свойств листовых заготовок. Учитывая, что для осуществления предложенного способа на формирующие элементы необходимо задавать давление q до двух σ _в пластичного легкоплавкого сплава (т.е. до q=2· σ _в), усилие штамповки можно установить по формулеSheet blank 24 (at

) are mounted on the matrix 18 (Fig. 14) and during the working stroke of the press they are inside the container 21 (Fig. 15), and the lowering punch 19 is first in contact with the upper disk 22, and then upsets the packet, as a result of which the flat blank 24 under the action the shear strain takes the form of a conical semi-finished product 25 (Fig. 19), and the lower forming element 27 remaining on the matrix 18 (after raising the outer slide of the press 20) is removed from the working area of the press. In this case, the upper forming element 26 with a conical 25 is held in the container 21 by friction forces (Fig. 17). This ends the first stage of manufacturing the part, after which the outer slider 20 with the upper forming element 26 and with the conical semi-finished product 25 rise up (Fig. 17), and the lower forming element 27 together with the matrix 18 are removed from the working area of the press to prepare the device for the next the stamping step of the conical semi-finished product. The second stage of manufacturing the part is to draw the conical semi-finished product 25 into the hemisphere 28, for which the forming element 27 is removed from the press working area and the spherical matrix 29 with the ejector 30 is placed in place of the matrix 18 (Fig. 18, the drive is conditionally not shown). The inclusion of the working stroke of the press first leads to lowering the container 21 to its lowest position and pressing the conical semi-finished product 25 to the inlet cone 31 of the matrix 29 (Fig. 19), after which the pressure from the side of the punch 19 on the upper forming element 26 creates pressure from the side of the latter , which pulls the conical semi-finished product 25 into the hemisphere 29, while the element 26 takes the form 32 after lowering it to a height h _oc (Fig.19 and 20). The inclusion of the reverse stroke of the press leads to the rise of the punch 19 and the container 21 to an extremely upper position (Fig. 21), which ensures the lifting of the spherical part 28 with the element 32 and the subsequent removal of the stamped part 28 with the element 32 from the working area of the press for their subsequent processing and when the need to change the exhaust matrix 29 to the matrix 18. For the proposed method of stamping hollow parts, the use of a low-melting alloy according to [5] has a number of technological advantages. Firstly, it is cheaper than other alloys, since it contains less bismuth, and the expensive component - tin - is absent in it. Secondly, the melting point of this alloy is below 100 ° C and, therefore, to boil this working medium from a stamped product and to obtain new forming elements, you can use a bath of boiling water. Thirdly, the content of zinc in this alloy of 1.2 and 3% provides Brinell hardness of 13.9, 15.1 and 17.0 HB, respectively, which allows this alloy to be used for stamping hollow products with a wide range of sheet mechanical properties blanks. Given that for the implementation of the proposed method on the forming elements, it is necessary to set the pressure q to two σ _{in a} ductile low-melting alloy (i.e., to q = 2 · σ _in ), the stamping force can be set by the formula

where f _k is the area of the "mirror" of the container.

Consider the example of a hemisphere by the proposed method with the following data: hemisphere material - Aluminum alloy AMg6 (σ _in = 30 kgf / mm ^2), the sphere diameter d = 150 mm, wall thickness _and S = 1.5 mm, the degree of wall thickening E = S _y / S _u = 1.3, the fusible alloy to [5] with 1% of zinc (σ _in = 5 kgf / mm ^2). The diameter of a flat sheet billet equal to the diameter of the container is established by the formula D _osf = D _ksf = 1.3 · d = 1.3 · 150 = 195 mm, and the thickness S _o by the formula (2). Then S _o = S _and / sinα _u = 1.5 / sin45 ° = 1.5 / 0.71 = 2.1 mm. The angle of conicity of the thickening according to formula (11) will be 2 · α _y = 2-arc sin (E · sinα _and ) = 2 · arc sin (1.3-0.71) = 2-arc sin 0.82 = 134 °. The stamping force P _u set by the formula (14)

R _W = 2 · σ _in · F _k = 2 · 5 · 0.785-195 ² = 300000 kgf = 300 tf.

According to (13), the thickness of one of the forming elements is H _fe = 0.5-200 / 2 = 50 mm.

Thus, for the considered example, the geometric parameters of the initial billet and die tooling, as well as the power modes of the stamping process, are determined.

The above description of the invention shows that the proposed technical solution for stamping hollow sheet parts, combining the use of shear deformations in the first stamping step upon receipt of the conical semi-finished product with a constant wall thickness S _and together with exhaust strains obtained in the second stamping step, provides a significant expansion technological capabilities for manufacturing hollow sheet parts in comparison, for example, with exhaust work

- when stamping parts from difficult to deform alloys (titanium, molybdenum, etc.), since shear deformations are significantly larger in magnitude than permissible elongated deformations [4];

- in the manufacture of parts from thin-walled blanks, since the use of deformable forming elements eliminates the appearance of unpressed sections of the blank that are prone to corrugation;

- in the production of steeply bent one and a half (at Д _у ~ 0), since a multi-junction hood of the latter is practically impossible.

Sources of information

1. USSR Copyright Certificate No. 172265, Cl. In 21 D 22/20, 06.29.59 (analogue).

2. Copyright certificate of the USSR No. 1061889, Cl. In 21 D 22/20, 16.12.83 (prototype).

3. USSR Copyright Certificate No. 1061889, Cl. B 21 D 22/20, 12/21/1983.

4. V.P. Romanovsky. Handbook of cold stamping. M .: Engineering. Leningrad Department, 1979, pp. 96 and 97.

5. USSR author's certificate No. 1226858 (low-melting alloy based on bismuth. Kh. M. Munasipov, V. K. Doronchenkov, O. A. Moskovsky, Yu. M. Leontiev).

Claims (2)

1. A method of stamping hollow parts from flat sheet blanks, in which the blank is placed in a bag between the forming elements of ductile low-melting metal, forming surfaces are performed on opposite surfaces of the forming elements, after which the package is deposited in the container between the pressing elements, characterized in that the total thickness of the package take constant in the direction of the force acting on it, forming surfaces are performed on the pressure elements, when stamping parts sf eric or toroidal shape with a cross-sectional diameter d, the values of the thickness of the flat sheet billet So and the diameter Dosf equal to the diameter of the container Dksf, set according to the dependencies Dosf = Dxf = 1.3 · d, So = Si and sina _and , where Dosf is the diameter of a flat billet for manufacturing a hemisphere; Dksf - container diameter; d is the diameter of the cross section of a sphere or torus; So is the initial thickness of the flat sheet stock; Si - the wall thickness of the product, and for stamping one and a half relevant parameters are set according to the dependencies Dot = Dct = Dt + 1.3 · d; Dvn = Dt-1,3 · d, where Dot is the outer diameter of the flat billet for the manufacture of one and a half; Dct - the outer diameter of the base of the annular cone of the semi-finished product; Dm is the diameter of the circular axis of one and a half or the distance between the centers of the passage section of the torus; Dvn - the inner diameter of the flat billet for the manufacture of one and a half, after which the first stage of stamping is carried out by settling a package of forming elements with a billet transforming the latter: for a hemisphere, into a semi-finished product of a conical shape, and for one and a half, into a semi-finished product with an annular conical cavity at a taper angle of 2 · a _and = 90 °, then, after removal lower forming and pressing elements and installation in place of the last spherical or toroidal matrix with conical input edges, the corresponding semi-finished product is drawn into a hemisphere or one and a half pressure with one hundred rons of the upper forming element. 2. A device for stamping hollow parts from flat sheet blanks containing the upper and lower strikers, a punch, a die, characterized in that the die is made with an inlet cone, the taper angle of which is set by the formula a _y = arcsin (Е sina _и ), where a _and - the taper angle of the conical semi-finished product to its axis; E is the degree of thickening of the hemisphere edge for welding; a _y is the taper angle of the annular input edge of the matrix.

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