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CN-117046915-B - Forming method and die device for zirconium alloy high-precision seamless pipe

CN117046915BCN 117046915 BCN117046915 BCN 117046915BCN-117046915-B

Abstract

The invention discloses a forming method and a die device of a zirconium alloy high-precision seamless pipe, a forming die device of the zirconium alloy high-precision seamless pipe, relating to the technical field of industrial equipment production, comprising a vertical reamer, wherein the vertical reamer comprises a reaming barrel, the reaming barrel comprises a reaming barrel lining and a reaming barrel shell, a base is fixedly arranged at the bottom of the reaming barrel through a high-strength bolt, an ejection mechanism is arranged at the center of the bottom of the reaming barrel in a penetrating way, and a shearing ring support is arranged at the top of the base. The integral cone die is beneficial to smooth flow of metal during extrusion, changes from concentrated deformation into gentle deformation, reduces extrusion force, reduces metal deformation intensity by low-speed extrusion, improves metal flow uniformity, solves the problem of pipe body cracking during extrusion by using a flat die, and improves the surface quality, internal tissue and performance quality of a zirconium pipe by a cold rolling process. The zirconium alloy pipe produced by the invention has high dimensional accuracy, good surface quality and high yield.

Inventors

  • GAO JIE
  • WANG JINYONG
  • LIU FUQIANG
  • Qi Xilun
  • HAN HENGLI
  • FEI ZHIWEI
  • CAO HONGBO

Assignees

  • 邯郸新兴特种管材有限公司

Dates

Publication Date
20260512
Application Date
20230808

Claims (9)

  1. 1. A forming method of a zirconium alloy high-precision seamless pipe is characterized by comprising the following steps: S1, firstly, zirconium alloy blank smelting forging is needed, namely sponge zirconium and alloy elements are pressed into a rod-shaped electrode together, a vacuum consumable process is adopted for smelting for two times to obtain an ingot, a box-type resistance furnace is used for heating before ingot casting forging, the ingot casting can be protected by a glass coating for reducing high-temperature oxidation, a cylindrical blank is forged, and the forging pressure ratio is more than 3.5; S2, blanking the forged blank according to the size of a finished product, machining 3-10 mm of an outer circle unilateral, machining a through hole with the diameter of 45-80 mm in the center, and machining according to a blank drawing, wherein the gamma angle of a bell mouth at the head of the blank is 46.0 DEG, the M value is the diameter of a working section of a reaming head, the L value is calculated according to the gamma angle by using a trigonometric function relation, and the inner and outer circles are machined, polished and polished to remove defects such as scratches, lathe tool lines and the like, the surface roughness Ra is less than or equal to 6.3 mu M, the diameter deviation is +/-1.0 mm, the length deviation is +/-10 mm, and the verticality of two ends is less than or equal to 1mm; S3, heating the processed blank to 80-95 ℃ by using a resistance furnace, spraying boron nitride anti-oxidation coating, placing the blank heated to the temperature in a reaming barrel of a 2500-ton vertical reamer for one or two times of reaming, preheating the reaming barrel to 100-300 ℃ including ①, coating graphite emulsion on the inner wall of the reaming barrel, heating the ② blank to 780-1100 ℃, coating glass powder lubricant on the inner and outer surfaces of ③ blank, wherein the outer diameter of the blank is 7-15 mm smaller than the inner diameter of the reaming barrel, one end of a blank bell mouth faces upwards, placing a reaming head at the bell mouth of the blank for reaming, wherein the reaming speed is 120-180 mm/S, the area ratio of the cross section before reaming to the cross section after reaming is 1.01-1.30, and air cooling after reaming; S4, machining and extruding the blank after reaming: removing oxide skin and defects on the inner and outer surfaces of the blank after reaming by a machining mode or a polishing mode, wrapping the inner and outer surfaces by copper sheets with the thickness of 0.5 mm-1 mm, placing the blank heated to the temperature in an extrusion barrel of a 6300 ton horizontal extruder for extrusion, wherein the extrusion barrel is preheated to the temperature of 250-350 ℃, an extrusion die and a mandrel are preheated to the temperature of 300-400 ℃, graphite lubricant is coated on the surfaces of the inner wall of the extrusion barrel, the extrusion die and the mandrel, ② heats the blank wrapped by the copper sheets to the temperature of 730-850 ℃ by a resistance furnace, and a tail pad is prepared before ③ extrusion, the tail pad is made of plain carbon steel, the outer diameter of the tail pad is smaller than the outer diameter of a blank by 1 mm-4 mm, the inner diameter of the tail pad is larger than the inner diameter of the blank by 2 mm-5 mm, the length of the tail pad is 60 mm-100 mm, the heating temperature of the tail pad is 900-1000 ℃, the tail pad is stuck to the rear of the blank before extrusion and is extruded together with the rear of the blank, the tail pad is automatically separated from a pipe body after extrusion, hot sharp cutting procedures are saved, hot sharp sheet consumption is reduced, the extrusion speed is 30 mm/S-80 mm/S, the ratio of the area of the cross section before extrusion to the area of the cross section after extrusion is 4-10, the low-speed extrusion is favorable for reducing the metal deformation intensity, the metal flow stability is improved, and the air cooling is carried out to room temperature after extrusion; s5, acid washing to remove copper sheets and extruded tube finishing treatment are needed, namely the extruded tube is subjected to copper sheet removal in acid liquor, the acid liquor is prepared by 20% -35% of nitric acid, the balance is water, other acid liquor is not added, the band saw is flat-headed, the inner surface and the outer surface are polished, and surface defects are removed; S6, cold rolling and annealing and finished product inspection-mark spraying-bundling are finally needed, one-pass or multi-pass cold rolling deformation is carried out by adopting a two-roller cold rolling mill, the feeding amount is 2.5-3.5 mm/time, the rolling speed is 30-50 times/min, the cold rolling deformation amount of each pass is 30-45%, annealing and degreasing are carried out after each pass of cold rolling, the annealing is carried out in a vacuum furnace or an atmosphere furnace, the annealing temperature is 500-590 ℃, the zirconium alloy tube is straightened, flat head, water pressure and inner and outer surface polishing are carried out, then the size and the tissue performance are detected, and finally mark spraying, bundling and warehousing are carried out.
  2. 2. The method for forming the zirconium alloy high-precision seamless pipe according to claim 1, wherein the diameter of the outer circle of the zirconium alloy pipe is set to be phi 19 mm-phi 245mm, and the wall thickness of the zirconium alloy pipe is set to be 1.5 mm-20 mm.
  3. 3. The method for forming the zirconium alloy high-precision seamless pipe according to claim 1, wherein the graphite lubricant in the extrusion stage consists of calcium grease, graphite and cylinder oil, and the components are respectively calcium grease, graphite and cylinder oil=2:1:0.5 in mass ratio, and the components are required to be uniformly mixed before use.
  4. 4. The forming die device for the zirconium alloy high-precision seamless pipe is based on the forming method for the zirconium alloy high-precision seamless pipe according to claim 1 and comprises a vertical reamer, and is characterized in that the vertical reamer comprises a reaming barrel (5), the reaming barrel (5) consists of a reaming barrel lining (51) and a reaming barrel shell (52), a base (2) is fixedly arranged at the bottom of the reaming barrel (5) through a high-strength bolt, an ejection mechanism (1) is arranged at the center of the bottom of the reaming barrel (5) in a penetrating manner, a shearing ring support (3) is arranged at the top of the base (2), a shearing ring (4) is arranged at the top of the shearing ring support (3), a dowel bar (8) is arranged on one side of the reaming barrel (5), a reaming needle (7) is arranged at one end of the dowel bar (8) through a threaded connector, and a reaming head (6) is arranged at one end of the reaming needle (7).
  5. 5. The device for forming the zirconium alloy high-precision seamless pipe according to claim 4, wherein the diameter of the reaming needle (7) is 5 mm-10 mm smaller than the diameter of the working section of the reaming head (6), the inner diameter of the shearing ring (4) is 1 mm-2 mm larger than the diameter of the working section of the reaming head (6), the center line of the reaming barrel (5) is not deviated by more than 1mm by the reaming needle (7), the reaming barrel lining (51) has a taper of 0.4 mm-1 mm in the length direction of an inner circle, and the thickness of the reaming barrel lining (51) is smaller than the thickness of the reaming barrel shell (52).
  6. 6. The forming die device for the zirconium alloy high-precision seamless pipe is characterized by comprising a horizontal extruder, wherein the horizontal extruder comprises an extrusion barrel (24), the extrusion barrel (24) consists of an extrusion barrel lining (21), an extrusion barrel middle lining (22) and an extrusion barrel shell (23), a core rod (15) is arranged on the inner side of the extrusion barrel shell (23), an extrusion pad (14) is sleeved at one end of the core rod (15), a core rod connecting piece (13) is arranged at one side of the extrusion pad (14), a core rod supporting piece (11) is arranged at one end of the core rod connecting piece (13), an extrusion rod (12) is sleeved at the outer side of the core rod supporting piece (11), a die holder (33) is arranged at the other end of the core rod (15), an integrated conical extrusion die (31) and a die support (32) are arranged inside the die holder (33), and a die middle pad (34) and a die tail pad (35) are sequentially arranged at the rear side of the die support (32).
  7. 7. The device for forming the zirconium alloy high-precision seamless pipe is characterized in that the extrusion barrel lining (21) and the extrusion barrel middle lining (22) are assembled in an interference fit mode, the front end structure shape of the extrusion barrel (24) is designed corresponding to the structure shape of the die holder (33), the central line of the extrusion barrel (24) is not deviated by more than 0.5mm by the extrusion rod (12), the core rod (15) is connected to the core rod support (11) through the core rod connecting piece (13) in a threaded mode, the gap between the extrusion rod (12) and the extrusion barrel lining (21) is 4-5 mm, and the gap between the maximum outer diameter of the core rod support (11) and the inner hole of the extrusion rod (12) is 0.1-0.5 mm.
  8. 8. The device for forming the zirconium alloy high-precision seamless pipe according to claim 6, wherein the cavity size of the die support (32) is 10 mm-15 mm larger than that of the integral conical extrusion die (31), the cavity size of the die cushion (34) is 15 mm-20 mm larger than that of the die support (32), the cavity size of the die tail cushion (35) is 20 mm-25 mm larger than that of the die cushion (34), the cavity shapes of the integral conical extrusion die (31), the die support (32), the die cushion (34) and the die tail cushion (35) are all round, the central line deviates from not more than 0.6mm, a lifting hole is formed above the die cushion, and the bottom is fixed by a clamping groove.
  9. 9. The forming die device of the zirconium alloy high-precision seamless pipe is characterized in that the clearance between the outer circle of the extrusion pad (14) and the inner hole of the extrusion barrel (24) is 1.0 mm-2.5 mm, the clearance between the inner hole of the extrusion pad (14) and the core rod (15) is 1.5 mm-2.5 mm, the length of the extrusion pad (14) is 200 mm-210 mm, the connecting part of the core rod connecting piece (13) and the core rod (15) is provided with internal threads, the connecting part of the core rod connecting piece (13) and the core rod supporting piece (11) is provided with external threads, the integral conical extrusion die (31) consists of an inlet transition zone, a middle sizing zone and an outlet reverse taper, the thickness is 100mm, the included angle alpha corresponding to the assembly of the extrusion barrel (24) is 60 degrees, the included angle beta of the inlet of the integral conical extrusion die (31) is 58-62 degrees, the included angle delta of the outlet of the integral conical extrusion die (31) is 8-10 degrees, and the length of the middle sizing zone L is 10 mm-15 mm.

Description

Forming method and die device for zirconium alloy high-precision seamless pipe Technical Field The invention relates to the technical field of industrial equipment production, in particular to a forming method and a die device of a zirconium alloy high-precision seamless pipe. Background Zirconium is a rare metal with the characteristics of remarkable corrosion resistance, extremely high melting point, ultra-high hardness and strength, and the like, and is widely used in the fields of aerospace, military industry, nuclear reaction and atomic energy. Zirconium and zirconium alloy have good plasticity and can be made into pipes, plates, bars and wires, wherein the pipes are main products. The processing of zirconium and zirconium alloys depends on the basic properties of zirconium and the particular requirements of the nuclear reactor for the zirconium component. Zirconium is easy to be polluted by oxygen, nitrogen, hydrogen and the like, is easy to adhere to a die, and has isomorphous transformation. The nuclear reactor has the requirements on zirconium components that the dimensional accuracy is high, the microstructure requirements are strict, and the performance is stable. Therefore, the alloy pipe has the problems of easy oxidation, easy hydrogen absorption and the like in preparation, and the traditional preparation method has lower yield and wastes metal. At present, a welding mode is adopted to process the pipe, and the welding seam cannot meet the requirement of the seamless pipe for nuclear power, so that a cold rolling mode is adopted to further process. The high-dimensional-accuracy pipe processing has the technical problems that the extruded pipe blank is difficult to match with the subsequent deformation size, the extrusion force is overlarge, the extrusion process is likely to be in a closed state, the treatment difficulty of the inner surface and the outer surface of the extruded pipe is large, the wall thickness deviation of the extruded pipe is difficult to control, the rolling dimensional accuracy is ensured, the dimensional deformation in the finishing stage is effectively controlled, the straightness of the finished pipe is controlled, and the like. Disclosure of Invention The invention aims to provide a forming method and a die device of a zirconium alloy high-precision seamless pipe, which are used for solving the problems in the background technology. In order to achieve the purpose, the invention provides the following technical scheme that the forming method of the zirconium alloy high-precision seamless pipe comprises the following steps: S1, firstly, zirconium alloy blank smelting forging is needed, namely sponge zirconium and alloy elements are pressed into a rod-shaped electrode, a vacuum consumable process is adopted for smelting for two times to obtain an ingot, a box-type resistance furnace is used for heating before ingot casting forging, the ingot casting can be protected by a glass coating for reducing high-temperature oxidation, a cylindrical blank is forged, and the forging pressure ratio is larger than 3.5. S2, blank machining is needed, namely blanking is conducted on the forged blank according to the size of a finished product, the outer circle is machined to be 3-10 mm away from one side, and a through hole with the diameter of 45-80 mm is machined in the center. The machining is carried out according to a blank drawing, wherein the gamma angle of a bell mouth of a blank head is 46.0 degrees, the M value is the diameter of a working section of a reaming head, the L value is calculated according to the gamma angle by using a trigonometric function relation, the machining, grinding and polishing of inner and outer circles are carried out, the defects of scratches, lathe tool lines and the like are removed, the surface roughness Ra is less than or equal to 6.3 mu M, the diameter deviation is +/-1.0 mm, the length deviation is +/-10 mm, and the verticality of two ends is less than or equal to 1mm. And S3, performing blank oxidation prevention treatment and reaming processing, namely heating the processed blank to 80-95 ℃ by using a resistance furnace, spraying boron nitride oxidation prevention coating, and placing the blank heated to the temperature in a reaming barrel of a 2500-ton vertical reamer for one or two times of reaming, wherein the step of preheating the reaming barrel to 100-300 ℃ comprises the step of preheating the reaming barrel to ① ℃, coating graphite emulsion on the inner wall of the reaming barrel, and the step of heating the ② blank to 780-1100 ℃ and coating glass powder lubricant on the inner and outer surfaces of the ③ blank. The outer diameter of the blank is 7 mm-15 mm smaller than the inner diameter of the reaming barrel, one end of a blank bell mouth faces upwards, a reaming head is placed at the bell mouth of the blank for reaming, the reaming speed is 120-180 mm/s, the ratio of the area of the cross section before reaming to the area of the cr