The method of fixing tubes

 

The invention relates to the processing of metals by pressure and can be used when attaching the tubes of heat exchangers. The ends of the tube profiles with education ends in the form of cylindrical sections, the mating conical transitional section. On the outer surface of the loaded section of the tip to form an annular ledge trapezoidal cross-section. The protrusion is formed in separable matrix with the annular groove of the stepped radial crimping of the length of the ending and its subsequent distribution donovania holes with simultaneous profiling of the inner surface of the loaded area. At step crimping of the length of the loaded area ending console feature to the edge of the ring grooves of the matrix and partially fill the volume of this groove material shaped ends, not affected by the radial crimping. In the process of distribution completely fill the pipe material volume of the annular grooves of the matrix. Then ending is installed in the hole of the tube with the annular grooves of trapezoidal and triangular cross-section, fix the pipe from possible displacements and fix. In achiev"ptx">

The invention relates to the field of metal forming, in particular to the process of fixing the tubes of heat exchangers using the effect of localized directional plastic deformation of the pipe material.

A known method of fixing tubes, including the installation of a heat pipe with one end in the tube hole, the fixation of the possible displacements, welded pipe end to the face of the tube with the subsequent expansion of the pipe by the application of compressive force to the inner surface, for example, mechanical rolling (see P. Doroshenko A. manufacturing Technology marine steam generators and heat exchangers, Leningrad, Sudostroenie, 1972, 143 S.).

To the main disadvantage of this method of fixing tubes should be attributed to the increased cost of production of the combined compounds. In addition, the known method has a limitation on the application, as not all of the material, forming a pair of connected elements are welded.

There is also known a method of fixing tubes, including the profiling of the pipe ends is sleduushee formation on the external surface of the loaded area profiled ends of the annular ledge of the trapezoidal cross-section, the installation of each ending in an orifice tube, made with annular grooves of trapezoidal and triangular cross sections, fixing pipes from possible movements and then pinning it in the hole in the tube by application of compressive force to the inner surface of the ending (EN 2171155 C2, 27.07.2001, 21 D 39/06 - prototype).

The disadvantage of this method is a significant dependence of the performance characteristics of the permanent connection from the aligned holes in tube sheets and annular grooves cut in them. The annular protrusion shaped ends having high strength characteristics, is placed in a corresponding annular groove hole tube with a variable on-orbit gap relative to the surface of the latter. In this case, the fastening of profiled ends of the pipe in the hole of the tube is associated with increased effort on deforming the tip of the tool. Formed ring density between the joined elements are determined by the intensity of local plastic deformation of the jumper tube, so as circumferential deformation of the pipe material in the ledge difficult.

The above Vesti tube grates from the nominal value.

Object of the invention is to provide such a method of fixing tubes, which would ensure quality ring densities between joined elements due to plastic deformation of the pipe material in the annular ledge.

The technical result is achieved in that in the method of fixing tubes, including the profiling of the pipe ends with the formation of edge lines containing cylindrical sections, the mating conical transitional section, the subsequent formation on the external surface of the loaded area profiled ends of the annular ledge of the trapezoidal cross-section, each ending in an orifice tube, made with annular grooves of trapezoidal and triangular cross sections, fixing pipes from possible movements and then pinning it in the hole in the tube by application of compressive force to the inner surface of the ending, according to the invention the formation of the external the loaded surface area of each profiled ends of the annular ledge of the trapezoidal cross-section is carried out in a split matrix with Kalki donovania her holes simultaneously profiling the inner surface of the loaded area, at this speed radial crimping of the length of the tail pipe is produced with maintenance console location of the length of the loaded area profiled ends to the edge of the ring grooves of the matrix and the partial filling of the annular groove by placing its material part of the profiled ends, not affected by the radial crimping and maintains its outer diameter, and in the process of distribution make final filling pipe material volume of the annular grooves of the matrix.

Implementation of the proposed method of fixing tubes repair option allows you to get a quality ring density between the joined elements and in cases where there are wide variations geometric dimensions of the annular grooves from the nominal values.

This is because, using the design of the profiled ends of the annular ledge of the relatively hardened material, create conditions of plastic deformation of the material (as in the radial and circumferential directions) in the annular ledge in the formation of permanent connection. As a result, the inner surface of the profiled for is not deteriorating the corrosion resistance.

The invention is illustrated by drawings, where Fig.1 shows the starting position of the segment split matrix and profiled end of the pipe with a larger geometrical dimensions on the external diameters; Fig.2 - stage end of the stepped radial crimping within the length of the profiled ends; Fig.3 - implementation phase low-speed tapered mandrel into the hole ends; Fig.4 - the end stage of forming an annular ledge introduction hole ending great degree mandrel; Fig.5 - connect the elements before the implementation of the pre-fixing pipe shaped tip in the hole of the tube; Fig.6 - end of the pre-fixing pipe in the hole of the tube; Fig.7 - initial position of the stepped mandrel and connected elements before final mounting of Fig.8 - stage formation of the bell on the edges of the holes of the tube; Fig.9 - the permanent connection of the tubes and tube sheets.

Variant implementation of the invention consists in the following.

Heat transfer pipe 1 (Fig.1) perform operations with the aim of preparing the outer surface of its ends to the profile: edit tronolane end of the tube, what pipe is fixed from possible movements and through hard punch to produce the distribution end to the external diameter greater than the diameter of the holes in the tube sheet holes, for example, for a pipe 252.5 mm outer diameter end after its distribution to equal...25,5 25,7 mm

Then the pipe is fixed from possible movements and, by moving the matrix with the speed of the working cavity on its end, perform a stepped radial crimping. As a result, three cylindrical section with diameter D1D2and D3mating conical transition sections. Pipe it shaped tip mounted in the hole of the split matrix consisting of three segments (Fig.1). The cavity formed by the segments when they are closing, contains an annular groove of trapezoidal cross-section. Carry out the fixing of the pipe from possible movements outside tooling (arrows).

Then make the closing segments of the matrix, causing a radial stepped crimping within part of the profiled ends, i.e. pureprofile her so into smaller external diameters of D4and D5. In the meter of D2and a console located to the edge of the ring grooves of the matrix is in the last volume, partially filling it (Fig.2). It should be emphasized that the stepped radial crimping, on the one hand, causes a lateral shift in the fabric of cylindrical sections, and on the other hand, forms the field of compressive stresses in the radial and tangential directions. Thereby form the stiffness of the deformation zone during subsequent operations on the pipe and eliminate the axial course of the pipe material.

In the hole profiled ending implement a stepped mandrel 3, which distributes the cylindrical section with an outer diameter of D3up to a diameter of the matrix, with the placement of Flexural deformation of the conical transition section in the volume of the annular grooves. Opposite the annular grooves of the matrix is formed an annular cavity (Fig.3).

Further axial movement of the stepped mandrel causes the influence of his greater speed to plastic for pipe material and the final formation of the annular ledge. Moreover, because of the relatively small deformation of the pipe material in the annular protrusion does not undergo large hardening. Moving large degree mandrel OGRANIChENNOI (Fig.4).

Then finally shaped ending set in the hole of the tube, controlling the correctness of the location of the pipe on the protrusion of the end-ends over the front surface of tube (Fig.5).

In the hole ending enter the case of the mechanical rolling and produce distribution plot (the action of the rollers rolling conventionally shown by arrows) ending with a minimum diameter of holes (Fig.6).

Contact deformation ending calls non-contact bending of the cylindrical control section ends with an outer diameter of D4CPC volume filling groove with a triangular cross-section.

The final fastening of the pipe in the hole of tube reach implementation in the hole ending stepped mandrel 5 (Fig.7). In this case, a small step to provide a distribution of the blade tips to the diameter of the hole in the tube sheet holes with the formation of lateral shifts in the canvas (shown in dashed lines) and the formation of the bell on the edges of the holes of the tube (Fig.8).

The permanent connection of the tubes and tube sheets has elevated service characteristics, where the density is achieved kolawale operations are performed on the second end of the pipe.

Pilot validation of the developed method was pinned steel (20) tubes with shaped ends in the tube sheets of steel 16GS thickness of 80 mm, an Initial geometrical dimensions of the tube were: outer diameter - 25 mm, wall thickness - 2.5 mm Outer surface of the pipe ends pre-profiled in industrial equipment hydraulic press, double action, developing maximum force of 0.6 MN. The cylindrical section ends with a minimum external diameter had to 23.8 mm, the maximum outer diameter of 25.6+0,05mm Conversion reached its reduction to the diameter of 25.3+0,05mm Width of the conical transition sections was equal to 2.0 mm

Pipe holes were produced with diameters equal to 25,35+0,05mm groove tube holes with triangular cross-section were: base - 6 mm, a depth of 0.3 mm, with a trapezoidal cross section: large base - 4.0 mm, the smaller base is 2.0 mm, a depth of 0.4 mm

Pre-fixing pipe in pipe hole was completed on a rolling stand firm “Indresco (USA) complete expanders, domestic production, and the final consolidation - dornbecher Saudi 0,2 MN.

Technological equipment for the production of tubes with shaped ends and hold them in place in the tube holes were made from tool steel WA with hardness after quenching HRC of not less than 56 units and precision of the Executive sizes according to the ninth degree.

The formation of a permanent connection with use of the tips that have shaped both external and internal surfaces, in combination with a bell on the edges of the holes of the tube provides guaranteed high performance characteristics of compounds; removing any defects that affect the operation of the tube bundle.

Tests for pulling tubes from the tube confirmed the increased strength characteristics of permanent joints (destruction occurred outside of fixing the original section of the pipe).

The density of connections in combination with high corrosion resistance provided 100% of their suitability to the requirements of production.

The invention is applicable in the manufacture of the tube bundles of heat exchangers in the oil refining, petrochemical, gas and other industries.

Claims

Ways is containing a series of cylindrical sections, the mating conical transitional section, the subsequent formation on the external surface of the loaded area profiled ends of the annular ledge of the trapezoidal cross-section, each ending in an orifice tube, made with annular grooves of trapezoidal and triangular cross sections, fixing pipes from possible movements and then pinning it in the hole in the tube by application of compressive force to the inner surface of the ending, characterized in that the formation on the outer surface of loaded area of each profiled ends of the annular ledge of the trapezoidal cross-section is carried out in a split matrix with the annular groove by a stepped radial crimping of the length of the ending and the subsequent distribution of ending donovania her holes simultaneously profiling the inner surface of the loaded area, with a stepped radial crimping of the length of the tail pipe is produced with maintenance console location of the length of the loaded area profiled ends to the edge of the ring grooves of the matrix and casting is subjected to radial crimping and maintains its outer diameter, and in the process of distribution make final filling pipe material volume of the annular grooves of the matrix.

 

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