A method of manufacturing a multilayer pipes

 

(57) Abstract:

Usage: metal forming, the production of multilayer pipes with capillary channels. The inventive method comprises a coaxial Assembly of layers of different diameters and their subsequent drawing. As layers are used longitudinally of the workpiece by the laser welding seam width equal to k h, where k = 0,3 to 1,1, h is the wall thickness, while the inner layer before Assembly is subjected to drawing with deformation rate of 40... 90% and use in cold-worked condition. Layers sochinyayut sequentially, by drawing with eliminating gaps between the layers, and the degree of deformation of each layer is determined from the expression % = A (100SK + 4) , where K is a numerical factor that determines the width of the bead; S - the numerical equivalent of the magnitude of subsidence seam of the workpiece by the laser welding, a is a coefficient depending on the assortment of pipes and equal ( 0,9...1,3 )%. table 2.

The invention relates to pipe manufacture and can be used in the manufacture of multilayer pipes.

In connection with intensive development engineering is constantly growing importance of the manufacturing isobutylester pipes of small diameter with znachitelnoi as determined by the surface quality and dimensional accuracy of the specified channel.

To provide for the increasing demands in the manufacture of pipes with internal diameter of less than 1.5 mm by known methods is difficult or impossible.

The number of known methods for the production of multilayer pipes, including seamless pipe Assembly-blanks and their subsequent drawing or hand.

The closest in technical essence to the present invention is a production method of a multilayer, in particular the double-wall pipe, comprising a coaxial Assembly of seamless tubular blanks and their joint drawing for the purpose of eliminating gaps between them.

Common drawbacks of these methods is the inability to manufacture pipes with capillary channel high quality and mnogochislenost and complexity of manufacturing seamless pipe-layers.

The aim of the invention is the provision of opportunities for making isobutylester pipes with capillary channel (0,2...2 mm) increased quality while reducing the complexity of the process.

This objective is achieved in that in the known method, including coaxial Assembly of layers of different diameters and their subsequent drawing, as layers using longitudinal C is Ni layer before Assembly is subjected to drawing with deformation rate of 40...90% and use in cold-worked condition, and layers sochinyayut consistently performing drawing by eliminating gaps between the layers, and the degree of deformation of each layer is determined from the expression:

% = A (100 S K + 4) where K is a numerical factor that determines the width of the bead;

S - the numerical equivalent of the magnitude of subsidence seam of the workpiece by the laser welding;

A is the coefficient dependent on the assortment of pipes and equal (0,9...1,3)%.

The proposed method is as follows.

For welding workpieces pipe-layers use a tape with a thickness of 0.20...1.00 mm stainless steel type HT, 08KH18N10T, 12H18N9, 20X13 (for example, GOST 4986-79). The specified thickness range is optimal, since the thickness of the tape is less than 0.20 mm, it is impossible to form a laser weld width less than the thickness of the wall due to the limits of technical feasibility compression of the laser beam (used laser type installations LTN-103, RS 500, RS-1200, "Comet", "Lantana", "Hop-25", "quantum", "TL-1,5", "Mandarin") up to a diameter of less than 0.20 mm, that is, the seam may not be already diameter of the laser beam. When the thickness of the tape is more than 1.00 mm becomes uneconomic moulding process pipe diameter...7,0 6,0 mm diameter to wall thickness less than 6. To perform laser seam width is eljnosti, as well as inadmissible technologically, as excessive talovlozheny seam has a coarse grain and reduced mechanical properties. An important parameter of a welded joint for subsequent cold deformation and quality multilayer pipes is the height of the seam. As the platen gain (Burr) on the blanks are invalid under the terms of the lug and the junction pipe-layers, the laser welding seam is formed along the height of the depression, that is less than the wall thickness 3...15%, by profiling the strip edges (performance bias) or by Assembly joint with a specified gap between the edges (both uniform and nonuniform thickness of the wall). Sagging of the weld is less than 3% of the wall thickness is difficult to maintain due to the variation of the gap between the edges during welding (i.e., when conditions change, the Assembly of the junction), resulting in some places cushions gain. The seam subsidence of more than 15% of the wall thickness of the workpiece is inadmissible under the terms of the subsequent drawing of pipes, as selected deformation modes will not occur thickening of the suture to the level of the wall thickness that is the reason for rejection of the pipe. Laser welding is performed at a speed of movement of the pipe 0,30 5,00...m/min at a power ish">

Possible options joints of pipe-layers are presented in table. 1.

A very significant element of the proposed method of manufacturing a multilayer isobutylester pipes is the preparation of the inner tube. With the aim of improving the durability of the developed methods of making isobutylester pipes with hardening of the inner surface nitriding, heat the outer surface and internal cooling, internal Hydrogenium. In the proposed method specified hardening channel is more cost-effective and efficient way by using an inner layer of the capillary pipes of required size with a given degree of hardening, reached a preliminary drawing - ProcNum and besprobochnym. As the experiments showed, the rational range of the degree of hardening of tubes of stainless steels is within ab= 1000...1700 MPa and corresponds to the degree of deformation 40...90%. The proposed method can be obtained multi-layer high-strength pipes with capillary channel sizes 4,5...7 CVI. 0,2...2 mm Number of layers is within 3. ..5. The thickness of the inner layer is 0.13...0.3 mm, the rest of 0.3. . .1 mm Number of layers and their oami with a minimum periodicity of production.

The calculation of the deformation modes of the layers in the drawing the above formula showed her a satisfactory convergence with the practical results. In General, the range of the degree of deformation is in the range of 4...20%, while increasing subsidence seam S necessary degree of deformation increases, which provides the required thickening of the wall in the spot weld and the receiving layer with a uniform wall thickness around the perimeter.

It should be noted that a greater wall thickness (see table 1), the greater the possible subsidence of the walls, of greater importance And, under the terms of laser welding - less numerical factor K, which determines the width of the bead.

As an example, below is an example of the calculation of the required degree of deformation of the layer with the drawing on the proposed formula .

The pipe-layer - size 6 x 1 mm steel 12X18H10T

The amount of sagging of the weld (see tab. 1):

S = 0,15 h = 0,15 1 mm = 0.15 mm

Factor K = 0,65

A = 1,3%

= 1,3 (100 0,15 0,65 + 4) = 17,87 18%.

During tests of the method were made of five-layer pipe size 6 x NR 1 mm of steel 12X18H10T sizes of pipe-layers (counting from the inner surface of the pipe): 1,4 x 0.2, 2 x 0.3, 3 x 0.5, 4.5 x 0.75 and 6 x 0.75 mm

It should be noted that to resolve the resulting depression was enough to make drawing with the reduction with the degree of

= 0,9 (100 0,01 1,1 + 4) = 4,59%.

However, for the desired hardening of the inner layer and the receiving channel of the pipe with high surface quality and accuracy of the drawing is first carried out without intermediate heat treatment to become automatically self-centering mandrel, and then, without mandrel-route:

3 x 0,25 ->> 2.3 x 0.2->> 1.8 x 0.2->> 1.4 x x 0.2 mm, with the total deformation= 65%. For welding layer 11 used a tape thickness of 0.3 mm, the Width of the seam when it was h1= 1 to 0.3 = 0.3 mm; the amount of sagging of the weld: S = 0.05 x 0,3 = 0,015 mm

Rational degree of deformation in this case is:

= 1,1 (100 0,015 1 + 4) = 6,05%

Considering the above the workpiece by the laser welding were made size 2.10 x 0,3 mm specified In the workpiece has entered the pipe layer 1 size of 1.4 x 0.2 mm and conducted joint drawing with a nozzle layer 11 to layer 1 (size 2 x 0.5 mm). The degree of deformation of the upper soybeans were $ 6,85 0,5 = 0,425 mm; subsidence seam: S = 0,4 0,5 = 0,02 mm

The necessary degree of deformation in this case is:

= 1,1 (100 0,02 1 + 4) = 6,6%.

A pipe-blank for the manufacture of the third soybeans received laser welding size 3,17 x 0.5 mm, Then the specified pipe has introduced a two-layer pipe size 2 x 0.5 mm and was jointly carried out by drawing on the size 3 x 1 mm

For the manufacture of layer IV used the tape with a thickness of 0.75 mm, joint width is h1= 0,6 0,75 = 0.45 mm; subsidence seam S = 0,05 0,75 = 0,037 mm

The necessary degree of deformation during wire drawing is

= 1,2 (100 0,037 0,6 + 4) = 7,46%.

Specific to the strain produced billet size 4,80 x 0.75 mm, introduced a three-layer pipe size 3 x 1 mm inside the specified workpiece and implemented drawing on the size of 4.5 x 1,75 mm, For the manufacture of layer V used a tape thickness of 0.75 m, respectively, the values of the width of the seam, subsidence, and deformation during the landing layer V on a four-pipe similar to the values obtained in the calculation of the parameters of layer IV. The pipe size of the workpiece based on the specified were: 6.42 per x 0.75 mm In the specified workpiece has introduced a four-layer pipe size 4.5 x 0.75 mm and implemented a joint in which the destination is within 0.02 mm, the inner surface roughness corresponded Ra 0,5...0,7 μm, the tensile strength of the metal pipe internal soy ran up to 1200 MPa. The manufacture of such pipes by known methods is not possible.

The data validation process parameters are given in table. 2.

Analysis of the data demonstrates the effectiveness of the use of the selected parameters of the manufacturing process of multilayer pipes with precision capillary channel. When the deviation beyond the rational limits the quality of pipes and process stability decreases dramatically. In particular, for small deformations (less than 40%) of the inner layer, taking into account the capillary channel becomes impossible for him otpravochnaya calibration, thus reducing the accuracy of the channel and increases the surface roughness. When exceeding the recommended degree of deformation (90%) due to low plasticity there are cases of fracture of the inner Sol. With exorbitant small amount of subsidence (S < 0,03 h) not possible formation of external or internal grata (roller amplification), in excess of the permissible magnitude of subsidence (S > 0,15 h) in place of a seam formed film, etc.

The developed method allows manufacturing the CSOs quality in diameter, for example 0.2 to 1 mm, which in a known manner to obtain not possible.

A method of MANUFACTURING a MULTILAYER PIPE comprising an Assembly coaxially installed layers of different diameters and their subsequent drawing, wherein, with the aim of ensuring the possibility of manufacturing isobutylester pipes with capillary channel, improving the quality of the pipes while reducing the complexity of the production process, as layers using longitudinal tubular workpiece by the laser welding seam width equal to K h, where K = 0,3 - 1,1, and h is the wall thickness, mm, while the inner layer before Assembly is subjected to drawing with deformation rate of 40 to 90% and use in cold-worked condition, layers were combined sequentially, by drawing with the elimination of the gap between the layers, and the degree of deformation and each layer is determined from the expression

= A (100SK + 4) , % ,

where K is a numerical factor that determines the width of the bead;

S - the numerical equivalent of the magnitude of subsidence seam of the workpiece by the laser welding, equal (0,03 - 0,15) h, mm, where h is the wall thickness of the workpiece;

A is a coefficient depending on the assortment of pipes, 0.9 to 1.3%.

 

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