RU2149722C1 - Method for making branched parts - Google Patents

Abstract

FIELD: machine engineering, possibly manufacture of branched parts of pipelines such as T-pieces, cross pieces. SUBSTANCE: method comprises steps of bending blank along axis of branch pipe with inner radius equal to 1-2 thickness values of initial blank; applying bending efforts in plane passing through axes of tubular blank and branch pipe for preliminarily accumulating blank material in zone of branch pipe; forming branch pipe by hydrostatic shaping; simultaneously upsetting blank at both ends by applying to it in bending plane straightening efforts directed opposite relative to bending efforts; after hydrostatic shaping and upsetting blank one or two times successively realizing operations of bending tubular blank, subjecting it to hydrostatic shaping and upsetting at both ends. EFFECT: lowered cost price of branched parts. 3 cl, 9 dwg, 1 ex

Description

 The invention relates to the field of engineering and construction and can be used for the manufacture of various pipeline parts with bends, mainly tees and cross pieces from tubular blanks of various systems in mechanical engineering, as well as in heat and gas supply systems in construction.

 A known method of manufacturing parts with bends from tubular billets by hydrostatic molding with simultaneous end settlement [1, p. 22-96].

The disadvantages of this method are:
a) the inability to stamp thin-walled parts (S / d≤0.01);
b) under real conditions of stamping parts such as tees, the working fluid pressures during hydrostatic molding exceed 200-300 MPa, which requires complex multipliers;
c) stamps of complex design are required, consisting of at least two halves;
d) the need to carry out active backwater.

Therefore, equipment for hydrostatic molding must have the following independent drives:
1. Power cylinders of the working course;
2. Closing cylinders of semi-matrices;
3. Cylinders of active backwater.

 In addition, it is still necessary to adjust the pressure during the molding process.

 Therefore, complex, even unique, and expensive equipment and accessories for hydrostatic molding by a known method increase the cost of manufacturing parts with bends.

 The closest in technical essence to the claimed invention is a method of manufacturing parts with bends from tubular billets, including the preliminary accumulation of the billet material in the bend zone and its transformation into a bend by hydrostatic molding of the billet with its simultaneous two-side end settlement [2].

 Although this method allows stamping thin-walled parts, the disadvantages inherent in known methods of hydrostatic molding in the part relating to equipment and tooling are also characteristic of this method.

 The technical problem to which the invention is directed is to simplify the design of equipment and tooling used in the manufacture of parts with bends, and to improve the quality of the parts obtained.

 The technical result obtained by the implementation of this invention is to reduce the cost of manufacturing parts with bends.

 To solve the problem in a known method of manufacturing parts with bends from tubular billets, including the preliminary accumulation of the billet material in the bend zone and its transformation into the bend by hydrostatic molding of the billet with its simultaneous two-side end settlement, the billet material is accumulated in the bend zone by bending it along the axis allotment along the inner radius equal to one or two thicknesses of the initial billet, with the application of bending forces in the plane of the bend passing through the axis of the tubular billet and retraction, and end draft is carried out by applying to the billet in the plane of the bend, the straightening forces directed opposite to the bending efforts.

 After hydrostatic molding and face upsetting of the workpiece, additionally one or two times in succession the operations of bending the tubular workpiece and its subsequent hydrostatic molding with face upsetting are performed.

 This method can be used for the manufacture of tees and crosses.

The fluid pressure during hydrostatic molding of tee-type parts is determined by the following formula [1, p. 47]:
q ₁ ≥ 1.13σ _s + 1.15σ _s s / d, (1)
where σ _s is the yield stress taking into account simplification,
S is the thickness of the material of the tubular workpiece,
d is the diameter of the tubular workpiece.

 In the proposed method, the required pressure of hydrostatic molding is determined from the condition that it should ensure the straightening of the accumulated material and its fit to the contour of the matrix in the area of the formed tap.

Для реальных деталей относительная толщина лежит в интервалах

т. е. давление гидростатической формовки деталей с отводами по предлагаемому способу в несколько десятков раз меньше, чем в известных способах. Соответственно отпадает необходимость в специальных источниках высокого давления - мультипликаторах, резко уменьшается усилие осевого сжатия, подпора вершины отвода, отпадает необходимость в специальных уплотнениях.To calculate the pressure, a simplified formula such as:
q ₂ = 2σ _s • s / d. (2)
If we take the ratio of pressures with known methods of forming parts with bends (q ₁ ) to the hydrostatic molding pressure according to the proposed method (q ₂ )

For real parts, the relative thickness lies in the intervals

that is, the pressure of hydrostatic molding of parts with bends according to the proposed method is several tens of times less than in the known methods. Accordingly, there is no need for special high-pressure sources - multipliers, the axial compression force, back-up of the outlet tip are sharply reduced, and there is no need for special seals.

 All these advantages of the proposed method ultimately can significantly simplify the process of stamping parts with bends, dramatically reduce the cost of manufacturing tubular parts with bends.

 When using known methods for manufacturing parts with bends, the permissible thinning at the top of high bends depends on the material of the workpiece and is usually 25-35%. The greatest thickening is achieved in the area of the tubular billet, located opposite the branch and may exceed 30-50%, i.e. the total thickness variation of the finished part when using known methods for manufacturing parts with bends is on average (60-80)%.

 Carrying out the operations of bending the tubular billet and the subsequent hydrostatic molding of the outlet with the end draft one after another several times, it is possible to reduce the thickening in the formed outlet to 15-20%. In this case, there will be no thickening of the workpiece material in other parts of the part. Therefore, the thickness of the part will be determined only by thinning the tap and the total thickness of the part according to the proposed method will be three to four times less than the thickness of the parts with bends obtained using known methods.

Figure 1 shows the stages of the process:
a) the initial position of the tubular billet before flexible;
b) the position of the tubular billet at the end of bending;
c) the position of the tubular billet in the final stage of the formation of the branch.

 In FIG. 2 shows the shape of the tubular workpiece in axonometric projection in the initial position (a), the position after completion of bending (b) and the finally molded tee (c).

 The proposed method is as follows. Pre-cut a piece of pipe from a lengthy workpiece on existing equipment.

 Then the ends of the pipes are milled according to a specially made template. The obtained billet 1 is installed in a specially made fixture for bending, the main element of which is a bending device consisting of two symmetrical mandrels 2 and 3 and mandrels 4 and 5. On mandrels 2 and 3, special reductions were made to the thickness of the tubular billet forming an annular stream in which the workpiece is installed 1. Another important element of the bending device is a stepped pin 6, the axis of which determines the position of the bending axis "O". The position of the axis "O" is set by the size "l", equal to one or two thicknesses of the workpiece from the initial position of the outer diameter of the tubular workpiece. On the basis of 7 bending devices, a matrix 8 is fixed, the dimensions of which correspond to the dimensions of the formed branch. The axis of the branch and the axis of the tubular workpiece determine the position of the bending plane.

The bending device assembly with the tubular billet is connected to the rods of the power cylinder (not shown in the drawing). When pressure is applied into the cavity under the piston of the power cylinder (not shown) is transmitted force bending "P _mfd" on the mandrels 2 and 3, and there is a mutual reversal in the cavity mandrel bend 2 and 3 together with the mandrels 4 and 5 on the bending angle "α ₂ ". In this case, a specific variation of the pipe bending scheme is realized with tension, when the neutral bending line lies in the region of the bending inner radius, which, as is known from the literature, excludes shaping.

 With an increase in the bending angle, an additional supply of material of the tubular billet from the stream between the mandrels 2 and 3 and the mandrels 4 and 5 to the increasing deformation zone in the branch area occurs, while the deformation zone is flattened.

 If bending is carried out with an internal bend radius exceeding one or two thicknesses of the tubular billet, destruction occurs along the outer most stretched fibers at the beginning of the process and the part goes into marriage.

Upon reaching the bending angle “α ₂ ” of a predetermined value, the shape of the intermediate tubular semi-finished product 9 will have the form shown in FIG. 2 "b". This completes the operation of preliminary accumulation of material in the removal zone. The operation of transforming the accumulated material into a tap is as follows. A pump is turned on (not shown in the drawing), supplying liquid under a working pressure "q" to the internal cavity of the intermediate semi-finished product, and excess liquid is discharged through a pressure regulator (not shown in the drawing). The force "P _OS " from the influence of the working pressure "q" on the ends of the mandrels is transmitted to the base of the bending device (not shown).

Pressure is applied to the cavity above the piston of the power cylinder (not shown in the drawing), the rod of which provides an impact on the mandrels 2 and 3 of the straightening force "P _sp ". The accumulated material and additional material are transformed from end upsetting under the influence of the working pressure "q" and the straightening forces "P _sp ", directed opposite to the bending forces, into the bend. The process of hydrostatic molding with end draft is completed when α _sp = 180 ^{° is} reached.
After the operation is completed, the working pressure pump is stopped, the pressure "q" is released, the forming matrix of the outlet 8 is retracted, the bending device is disconnected instead of the molded part 10 from the rods of the power cylinder (not shown in the drawing).

 The right and left halves of the bending device from the part are sequentially disconnected. An axonometric projection of the finished retracted part is shown in FIG. 2 "in".

 The next workpiece is installed and the process continues. To reduce the thickness difference of the finished part or to increase the height of the tap, the operations of bending the tubular billet and subsequent hydrostatic molding with end settlement are repeated two or three times in succession.

Example. An equal bore tee was made from a трубы 22 × 1 copper pipe of grade M3 in the delivery state. The length of the workpiece was L ₀ = 70 • 10 ³ m. The shape of the template for making a bevel at the ends of the workpiece was determined according to the method described in the special overview information [3, p.31-36]. Before flexible produced annealing of the workpiece at T = 750 ^o C.

Bending (and flattening) was carried out on a specially designed and manufactured installation, the pneumatic cylinder of which provided a force of 1800 N. The operating pressure q = 22 MPa was provided by a manual pump NRA1. Bending (and flattening) of the deformation zone for preliminary accumulation of material was performed at an angle α = 90 ^° . After hydrostatic molding with end draft, the proposed method received a tap ⌀ 22 × 20. The maximum thinning at the top of the branch was 18-20%.

 For comparison: when stamping a tee with the above dimensions according to known methods, the required values of deforming forces are [1, p. 47, p. 50] pressure q = 330 MPA.

где q - давление = 330 МПа = 33 кгс/мм²;
d - диаметр d = 22 мм;
S - толщина S = 1 мм;
σ₂- предел текучести с учетом упрощения σ₂= 28 кгс/мм²;
μ - коэффициент трения μ = 0,10;
l - длина заготовки в конце штамповки, принимает l = 45.Axial draft force

where q is pressure = 330 MPa = 33 kgf / mm ² ;
d is the diameter d = 22 mm;
S is the thickness S = 1 mm;
σ ₂ - yield strength, taking into account the simplification of σ ₂ = 28 kgf / mm ² ;
μ is the coefficient of friction μ = 0.10;
l is the length of the workpiece at the end of stamping, takes l = 45.

Substituting these values in the above formula, we obtain
F = 3.14 (3930 + 498 + 1633) = 3.14 • 6061 = 19031 kgf
or F = 190 310 N.

соотношение усилий основного цилиндра

С уменьшением относительной толщины трубчатой заготовки эффект от применения предлагаемого способа увеличивается.so about pressure ratio

ratio of efforts of the main cylinder

With a decrease in the relative thickness of the tubular billet, the effect of the application of the proposed method increases.

 The application of the proposed method in industry will make it possible to make the cost of manufacturing parts with bends comparable to the cost of the material of the tubular billet from which it is made, by replacing unique equipment with a simplified bending device.

References
1. Hydraulic processing of metals (Epiphany K.N., Vagin V.A., Kobyshev A.N. et al .; Translated from Bulgarian G. Peshkov G.K. and Chalova D.I., Engineering, Leningrad branch, Sofia, Technique 1988.

 2. USSR N 531591 B 21 C 37/29. Claim 11.25.74 N 2078194/27. Publ. 10.15.76, BI N 38.

 3. Written E.I., Erbeigem S.A., Zayats V.I., Myazhtsa A.K. Forming of elements of pipeline systems by polyurethane on a hydraulic press. - M .: 1990-64 s, 28 ill. (Engineering production, ser. Technology and equipment of KShP: review. Information. VNIIGEMR. Issue 3).

Claims (3)

 1. A method of manufacturing parts with bends from tubular billets, including the preliminary accumulation of the billet material in the bend zone and its transformation into a bend by hydrostatic molding of the billet with its simultaneous two-side end settlement, characterized in that the billet material is accumulated in the bend zone by bending it along the axis retraction along the inner radius equal to one or two thicknesses of the initial workpiece, with the application of bending forces in the plane of the bend, passing through the axis of the tubular workpiece and retraction, end precipitate is performed by applying to the workpiece in a plane bending straightening efforts directed oppositely bending efforts.  2. The method according to claim 1, characterized in that after hydrostatic molding and face upsetting of the workpiece, additionally one or two times sequentially perform operations of bending the tubular workpiece and its subsequent hydrostatic forming with end upset.  3. The method according to any one of claims 1 to 2, characterized in that the manufacture of parts with bends in the form of tees and crosses.

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