阅读说明：本技术 一种带肋包壳管的冷拔模具、生产工艺及其成品管 (Cold drawing die for ribbed cladding tube, production process and finished tube thereof ) 是由 蔡志刚 王涛 唐睿 邱吕强 杨红 吴静娜 张超 董洪卫 罗霞 于 2020-07-24 设计创作，主要内容包括：本发明涉及异形截面不锈钢精密无缝管材加工制造领域,尤其涉及一种带肋包壳管的冷拔模具、生产工艺及其成品管,冷拔模具包括有用于管道外部轮廓成型的冷拔外模及用于限制管道内径的冷拔芯头,所述冷拔外模内部型腔包括依次排列的入口段、成型段及出口段,所述入口段及所述出口段均为圆台形槽,所述成型段包括外径成型孔及设置于所述外径成型孔外围的至少一段的肋槽；所述冷拔芯头为实心结构包括依次排列的定内径段、圆台段及后圆柱段；工艺包括加工管材准备、冷拔前处理、冷拔成型、切管清洗、固溶处理及矫直。模具结构简单生产成本低,所用到的工艺生产效率高、表面质量好、尺寸精度高、综合性能优。(The invention relates to the field of processing and manufacturing of stainless steel precise seamless pipes with special-shaped sections, in particular to a cold-drawing die for a ribbed cladding pipe, a production process and a finished pipe thereof, wherein the cold-drawing die comprises a cold-drawing outer die for forming the outer contour of a pipeline and a cold-drawing core head for limiting the inner diameter of the pipeline, an inner cavity of the cold-drawing outer die comprises an inlet section, a forming section and an outlet section which are sequentially arranged, the inlet section and the outlet section are both truncated cone-shaped grooves, and the forming section comprises an outer diameter forming hole and at least one section of rib groove arranged on the periphery of the outer diameter forming hole; the cold-drawing core head is of a solid structure and comprises a fixed inner diameter section, a circular truncated cone section and a rear cylindrical section which are sequentially arranged; the process comprises the steps of pipe processing preparation, cold drawing pretreatment, cold drawing forming, pipe cutting cleaning, solution treatment and straightening. The die has the advantages of simple structure, low production cost, high production efficiency of the used process, good surface quality, high dimensional precision and excellent comprehensive performance.)

1. The utility model provides a cold drawing mould of ribbed cladding pipe which characterized in that: the pipe inner diameter cold-drawing die comprises a cold-drawing outer die (1) used for forming the outer contour of a pipe and a cold-drawing core head (2) used for limiting the inner diameter of the pipe, wherein an inner cavity of the cold-drawing outer die (1) comprises an inlet section (1.1), a forming section (1.2) and an outlet section (1.3) which are sequentially arranged, the inlet section (1.1) and the outlet section (1.3) are both circular truncated cone-shaped grooves, and the forming section (1.2) comprises an outer diameter forming hole (a) and at least one section of rib groove (b) arranged on the periphery of the outer diameter forming hole (a); the cold-drawing core head (2) is of a solid structure and comprises a fixed inner diameter section (2.1), a circular truncated cone section (2.2) and a rear cylindrical section (2.3) which are sequentially arranged.

2. A cold-drawing die for a ribbed cladding tube according to claim 1, wherein: the rib groove (b) is divided into a guide section (b-1) and a fixed-length section (b-2), the guide section (b-1) and the fixed-length section are sequentially arranged, the guide section (b-1) is close to the inlet section (1.1), and the cross-sectional profile of the guide section (b-1) is always larger than that of the fixed-length section.

3. A cold-drawing die for a ribbed cladding tube according to claim 2, wherein: all bending parts of the guide section and the fixed-size section are round corners.

4. A cold-drawing die for a ribbed cladding tube according to claim 1, wherein: the surface roughness of the working surface of the cold-drawing external mold (1) is less than or equal to 0.5 mu m; the working surface roughness of the cold-drawing core head (2) is less than or equal to 0.2 mu m; the tail end of the outlet section (1.3), namely one side far away from the forming section (1.2), is provided with a round angle.

5. A process for producing a ribbed cladding tube using the cold-drawing die of claim 1, comprising the steps of:

firstly, preparing a processing pipe: the surface quality of the pipe to be processed is checked, the diameter reduction treatment is carried out on the front section part area of the pipe in a heading or necking mode, and lubricating oil is filled in the pipe;

cold drawing pretreatment: adding the cold-drawing core head (2) into the pipe, placing the core head at the front edge of the heading or necking in the step I, placing the pipe with the cold-drawing core head (2) inside into the cold-drawing outer die (1) from the inlet section (1.1), and enabling the front end part of the pipe to be located at the position of the outlet section (1.3) in a sub-region manner;

cold-drawing and forming: performing cold drawing treatment on the pipe by using a cold drawing machine, continuously putting lubricating oil into the cold drawing outer die (1), and obtaining a hollow metal pipe with ribs by using a cold drawing process;

cutting and cleaning: partially cutting off the tail end of the metal pipe head obtained in the step (III) and degreasing and cleaning the processed metal pipe;

solution treatment and straightening: and (4) carrying out solid solution treatment on the metal pipe treated in the step (iv) and then carrying out straightening treatment to obtain the finished product of the ribbed cladding pipe.

6. A process for manufacturing a ribbed cladding tube according to claim 5, wherein: and secondly, performing high-temperature heat treatment on the diameter-reduced part, preserving the heat for a certain time, and cooling to room temperature.

7. A process for manufacturing a ribbed cladding tube according to claim 5, wherein: when various parameters of the die are designed, the following data are required to be ensured, the relative cold-drawing deformation of the cladding tube is greater than or equal to 15%, the actual cold-drawing deformation is controlled between 30% and 55%, the cold-drawing reduction amount is greater than or equal to 1mm, the cold-drawing wall reduction amount is greater than or equal to 0.05mm, and the rib height generated by the rib groove (a) is reduced along with the reduction of the deformation and is reduced along with the reduction of the reduction.

8. The process of claim 5 for cladding a tube with ribs, wherein: the solution treatment mode in the fifth step adopts bright heat treatment.

9. The process of claim 5 for cladding a tube with ribs, wherein: the speed control should be performed during cold drawing, and the cold drawing speed is controlled to be 1.0-10.0 m/min.

10. A ribbed cladding tube characterized in that: produced by the process of any one of claims 5 to 9.

Technical Field

The invention relates to the technical field of processing and manufacturing of stainless steel precise seamless pipes with special-shaped sections, in particular to a cold-drawing die for a ribbed cladding pipe, a production process and a finished pipe thereof.

Background

At present, nuclear fuel assemblies mainly comprise a pressurized water reactor fuel assembly, a heavy water reactor fuel assembly, a sodium-cooled fast reactor fuel assembly and the like, and stable isolation among fuel cladding tubes in the prior art is one of keys for ensuring the operation safety of the fuel assemblies. The pressurized water reactor fuel assembly mainly comprises a zirconium alloy fuel cladding tube and a zirconium alloy fuel spacer, the cladding tubes are mutually isolated by the zirconium alloy spacer, and the pressurized water reactor fuel assembly is safe and stable in a high-pressure water environment, but has small unit power density and large volume; the pressurized heavy water reactor fuel assembly mainly comprises a zirconium alloy metal cladding tube and an outer sleeve, the fuel cladding tubes in the outer sleeve are mutually isolated by zirconium alloy positioning pads to ensure stability, but the heavy water reactor has large volume, high construction cost and high power generation cost due to expensive heavy water, and the heavy water reactor can adopt low-enriched uranium or even non-enriched uranium as nuclear fuel, so that nuclear diffusion is easily caused when the heavy water reactor is popularized in a large scale; the sodium fast-cooling reactor fuel assembly mainly comprises a stainless steel cladding tube and a hexagonal outer sleeve, wherein the stainless steel fuel cladding tube in the hexagonal outer sleeve is spirally wound by a stainless steel wire for mutual isolation, and the defect is that the stainless steel spiral winding wire is fixed in a spot welding mode and cannot resist high temperature and high pressure. Under the condition of long-term scouring of high-temperature and high-pressure media, spot welding parts are easy to fall off, so that isolation failure is caused.

The utility model discloses a chinese utility model patent that grant publication number is CN 203055470U discloses a ribbed cladding pipe of fuel rod radial positioning, including the cladding pipe body, the cladding pipe body wholly is cylindricly, and its inside is the cavity structure be provided with a rib of protrusion in its surface on the outside lateral wall of cladding pipe body at least, rib and cladding pipe body structure as an organic whole. The fuel cladding tube is isolated by adopting the spiral ribbed form integrally formed with the cladding tube substrate, so that the safety is higher, and the high unit power density and small volume of the reactor can be considered.

Although the ribbed cladding tube mentioned in the utility model, how to design and manufacture the ribbed cladding tube meeting the performance requirement is not mentioned, or what kind of integrated into one piece mode is adopted can satisfy the nuclear industry standard to satisfy the safety and stability of the sodium-cooled fast reactor fuel assembly.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a cold-drawing die for a ribbed cladding tube, a production process and a finished tube thereof.

The technical scheme for solving the technical problems is as follows:

a cold-drawing die for a ribbed cladding tube comprises a cold-drawing outer die for forming the outer contour of a pipeline and a cold-drawing core head for limiting the inner diameter of the pipeline, wherein an inner cavity of the cold-drawing outer die comprises an inlet section, a forming section and an outlet section which are sequentially arranged, the inlet section and the outlet section are both circular truncated cone-shaped grooves, and the forming section comprises an outer diameter forming hole and at least one section of rib groove arranged on the periphery of the outer diameter forming hole; the cold-drawing core head is of a solid structure and comprises a fixed inner diameter section, a circular truncated cone section and a rear cylindrical section which are sequentially arranged.

The invention relates to a cold-drawing external mold used for the existing cold-drawing processing, which is characterized in that in order to prolong the service life of the mold, the inner contour of the cold-drawing external mold is mostly round or square as the contour shape, but the invention aims to produce a special pipe with ribs, so the invention adopts the mode that the cavity is provided with rib grooves, the material of the pipe to be processed moves in the rib grooves when the pipe to be processed is extruded and deformed by a simpler structure to form the ribs on the pipe to be processed, the shape of the mold is simple, even if the mold is used for a long time, the damage of the mold is caused, and the production cost of the same mold is relatively lower due to the simple shape structure; in order to prevent the cold drawing core head from being deeply drawn into the forming section hole to cause the phenomenon of pipe breakage or being directly drawn out of the forming section hole, the slope of the circular platform section is smaller than that of the inlet section.

Preferably, the rib groove is divided into a guide section and a fixed-length section, which are arranged in sequence, the guide section is close to the inlet section, and the cross-sectional profile of the guide section is always larger than that of the fixed-length section.

The guide section is set to move metal to the rib groove as much as possible during wall reduction in the cold drawing process of the pipe, the effect of guiding to form the rib is achieved by adopting the technical scheme, and meanwhile, the service life of the sizing section can be greatly prolonged due to the buffer of the section, and the precision of finally forming the rib groove is improved.

In a further preferred embodiment of the above technical solution, all bending portions of the guide section and the fixed-length section are rounded corners.

If the die is a bevel, the capability of deforming the material is stronger, but the service life of the die is shorter relatively, the risk of die cracking can also be generated, and the invention does not need to ensure that the forming of the rib is a right angle and sets a round angle for avoiding the risk.

Preferably, the surface roughness of the working surface of the cold-drawing external mold is less than or equal to 0.5 μm; the working surface roughness of the cold-drawn core head is less than or equal to 0.5 mu m; and a round angle is arranged at the tail end of the outlet section, namely one side far away from the forming section.

The surface quality of the finished pipe drawn by the cold drawing process meets the requirement of the cladding pipe on the surface quality, and the surface quality of the finished pipe depends on the surface roughness of a working area of a cold drawing die, so the surface roughness of the cold drawing die is further controlled; and the round angle arranged at the tail end of the outlet section of the cold drawing core head can effectively prevent the pipe wall of the finished pipe from being pulled and roughened in the cold drawing process.

The invention provides a production process of a ribbed cladding tube based on the cold-drawing die in the technical scheme, which comprises the following steps:

firstly, preparing a processing pipe: the surface quality of the pipe to be processed is checked, the diameter reduction treatment is carried out on the front section part area of the pipe in a heading or necking mode, and lubricating oil is filled in the pipe;

cold drawing pretreatment: adding the cold-drawing core head into the pipe, placing the core head at the front edge of the heading or necking in the step I, placing the pipe with the cold-drawing core head inside in the cold-drawing external mold from the inlet section, and enabling the front end part of the pipe to be located at the position of the outlet section in a sub-area mode.

Cold-drawing and forming: performing cold drawing treatment on the pipe by using a cold drawing machine, continuously putting lubricating oil into the cold drawing outer die, and obtaining a hollow metal pipe with ribs by using a cold drawing process;

cutting and cleaning: partially cutting off the tail end of the metal pipe head obtained in the step (III) and degreasing and cleaning the processed metal pipe;

solution treatment and straightening: and (4) carrying out solid solution treatment on the metal pipe treated in the step (iv) and then carrying out straightening treatment to obtain the finished product of the ribbed cladding pipe.

Preferably, in the second step, the diameter-reduced part is subjected to high-temperature heat treatment, and after keeping the temperature for a certain period of time, the part is cooled to room temperature.

And eliminating internal stress of the part subjected to the diameter reduction treatment so as to reduce the phenomenon of tensile failure in the cold drawing process.

Preferably, when various parameters of the die are designed, the following data are ensured, the relative cold drawing deformation of the cladding tube is greater than or equal to 15%, the actual cold drawing deformation is controlled to be 30-55%, the cold drawing reduction is greater than or equal to 1mm, the cold drawing wall reduction is greater than or equal to 0.05mm, and the rib height generated by the rib groove is reduced along with the reduction of the deformation and is reduced along with the reduction of the reduction.

The rib height setting of specific parameter according to actual need, because the process of whole cold drawing is extrusion deformation, so the appearance of rib relies on whole deformation of treating processing tubular product, and the height of rib can be showing along with the reduction of reducing volume and reduce, guarantees to treat when the design that processing tubular product is in a higher deflection as far as possible to guarantee the appearance of rib, consequently treat when the design mould that processing tubular product reducing volume is big more, the rib height that can design is high more.

Preferably, the solution treatment in the fifth step is performed by bright heat treatment.

The ribbed pipe after cold drawing needs to be subjected to internal stress elimination treatment, the ribbed pipe after bright heat treatment can enable the surface of the ribbed pipe to be bright and flat and has certain mechanical property, a spiral twisting process can be possibly carried out at the later stage of the ribbed pipe, and the ribbed pipe can also have certain toughness due to the bright heat treatment, so that the ribbed pipe cannot be fractured during spiral twisting.

Preferably, the speed is controlled during cold drawing, and the cold drawing speed is controlled to be 1.0-10.0 m/min.

Because the cold-drawing outer die adopted by the invention is provided with more rib grooves, the cold-drawing forming difficulty is increased relatively, in order to prolong the service life of the cold-drawing die, the speed is reduced as low as possible so as to avoid influencing the surface quality of a finally formed finished pipe, but the cold-drawing speed is not too low for the production efficiency, so the cold-drawing speed is controlled to be 1.0-10.0 m/min.

A ribbed cladding tube is produced by applying the process of the ribbed cladding tube in the technical scheme.

In conclusion, the invention has the following beneficial effects:

1. the mould and the process adopted by the invention can directly form the cladding tube with the rib in an integrated manner, and the structural performance is good;

2. the die has the advantages of simple structure, convenient manufacture and low manufacturing cost, and the structural design of the cold-drawing forming section ensures the service life of the whole die;

3. designing the number of ribs and the rib height of the ribs according to the pre-calculated technological parameters so as to ensure that the formed ribs have good mechanical properties and smooth surfaces without cold drawing defects;

4. the ribbed tube produced by the invention can also relate to a spiral twisting process subsequently, so that the finally formed ribbed tube has certain toughness during process design, and the ribbed tube cannot be twisted off during subsequent twisting.

Drawings

FIG. 1 is a full sectional view of a cold-drawn external mold structure used in the present invention;

FIG. 2 is a side view of a cold-drawn overmold structure used in the present invention;

FIG. 3 is an enlarged view of area A of FIG. 2;

FIG. 4 is a schematic view of a cold drawn core print according to the present invention;

wherein, the outer die is drawn by 1-cold, the inlet section is 1.1, the diameter fixing section is 1.2, the outlet section is 1.3, the core head is drawn by 2-cold, the inner diameter fixing section is 2.1, the circular table section is 2.2, the cylindrical section is 2.3, the outer diameter forming hole is a, the rib groove is b, the guide section is b-1 and the size fixing section is b-2.

Detailed Description

The invention is further illustrated by the following examples: