Locking mechanism for metal pipe annealing, annealing tool and annealing method

Abstract

The invention belongs to the technical field of metal material machining, and relates to a locking mechanism for metal pipe annealing, an annealing tool and an annealing method. According to the locking mechanism, through the combined design of the neck bush, the lifting mechanism and the adjusting part, the adjusting part is driven by lifting of the lifting mechanism to extend outwards or retract back along the peripheral wall of the neck bush, so that the distance between the adjusting part and the inner wall of the metal pipe is adjusted, and the extending end of the lifting mechanism and the top of the neck bush are locked and fixed; therefore, the locking mechanism and the end of the metal pipe are fixed, it is further guaranteed that the metal pipe is not subjected to size deformation in the annealing process, the straightness and ovality of the pipe are improved, the heat treatment efficiency of the thin-wall metal pipe and the extremely-thin-wall metal pipe is improved, and the pipe yield is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of metal material processing, and relates to a locking mechanism for annealing a metal pipe, an annealing tool and an annealing method. Background Art

[0002] Metal pipes have the advantages of excellent corrosion resistance, high pressure bearing capacity, high stability and rigidity, good plasticity, safety and hygiene, environmental protection and recyclability, and long life, and have been widely used in various fields (such as industrial, construction, home, etc.). Especially in the field of petroleum and chemical industry, metal pipes can be used to transport various corrosive media, such as acidic gases, salt solutions, etc. For example, corrosion-resistant metal pipes such as titanium pipes, zirconium pipes and Hastelloy pipes play an important role in the production process of the petroleum and chemical industry. In short, metal pipes play a key role in many fields due to their high strength, corrosion resistance, high temperature resistance and other characteristics, and with the continuous advancement of science and technology, the application scope and performance of metal pipes will continue to improve.

[0003] It is well known in the industry that pipes are classified according to the ratio of their outer diameter (D) to wall thickness (S), and can be divided into the following categories: extra thick pipes (D / S≤10), thick wall pipes (10<D / S≤20), thin wall pipes (20<D / S≤40) and ultra thin wall pipes (D / S>40). Thin wall pipes and ultra thin wall pipes are widely used in the fields of automobiles, aerospace, medical equipment, petrochemicals, nuclear power, precision electronic instruments, etc. due to their lightweight and high strength characteristics, such as light weight, good thermal conductivity, and the ability to withstand high pressure and high temperature, as well as good mechanical properties. Their lightweight and high strength characteristics make them one of the indispensable materials in the manufacturing industry.

[0004] During the manufacturing process of metal pipes, internal stresses may be generated due to various reasons, and these stresses may cause plastic deformation and fracture of the pipes. Therefore, after the cold processing or hot processing of the finished pipes is completed, the finished pipes need to be heat treated to change the organizational structure of the pipe material and refine and homogenize the internal grains. At the same time, eliminating defects and stress concentration inside the material is conducive to improving the toughness and plasticity of the pipe, so that the isotropic stress can be evenly distributed inside the pipe, avoiding fracture or plastic deformation of the pipe, and thus ensuring the reliability and safety of the pipe. The annealing temperature of existing metal pipes generally uses the recrystallization temperature for annealing, and the annealing temperature is relatively high. For example, the annealing temperature of low carbon steel is between 550℃ and 650℃, that of medium carbon steel is between 650℃ and 750℃, and that of high carbon steel is between 750℃ and 850℃.

[0005] However, for pipes of different specifications, different annealing tools and annealing processes are required according to the requirements of the technical indicators of the pipes. For thin-walled pipes and ultra-thin-walled pipes, horizontal annealing furnaces or vertical annealing furnaces are generally used for heat treatment. Specifically: ① When thin-walled pipes and ultra-thin-walled pipes are annealed in a horizontal annealing furnace, the pipes are placed horizontally in a silo or on a flatbed material cart; during the high-temperature annealing process, due to the small lateral bearing capacity of thin-walled pipes, it is very easy to cause the bottom layer of pipes to deform under the pressure of the upper layer of pipes, resulting in unqualified dimensions of the bottom layer of pipes and reduced pipe batch yield. In the prior art, the problem of deformation of thin-walled pipes during high-temperature annealing can be solved by reducing the loading amount of pipes. However, for high-temperature annealing of ultra-thin-walled pipes, even if a layer of pipes is laid in the silo or material cart, the ultra-thin-walled pipes will deform in the lateral direction under the action of their own weight, resulting in unqualified pipe dimensions. ② When thin-walled pipes and ultra-thin-walled pipes are annealed in a vertical annealing furnace, holes need to be punched at both ends of the pipe, which causes uneven force on both ends of the pipe at the punching position, which can easily lead to deformation of the pipe ends; at the same time, the furnace loading process is cumbersome, the process is complicated, and the efficiency is low. In addition, the surface quality of both ends of the pipe is easily damaged during the punching process, and it needs to be cut again, which reduces the production efficiency and the pipe yield rate. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a locking mechanism, annealing tool and annealing method for metal pipe annealing, so as to ensure that thin-walled pipes and ultra-thin-walled pipes do not undergo dimensional deformation during vacuum annealing, which is beneficial to improve the straightness and ovality of the pipes, improve the heat treatment efficiency of thin-walled pipes and ultra-thin-walled pipes, and thus improve the yield rate of the pipes.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] On the one hand, the present invention provides a locking mechanism for annealing a metal pipe, the locking mechanism is installed at the end of the metal pipe, the locking mechanism comprises an inner sleeve, a lifting mechanism is provided in the inner sleeve and passes through the top thereof and can move in a vertical direction, and an adjusting portion is provided at the bottom of the lifting mechanism and can extend or retract along the peripheral wall of the inner sleeve;

[0009] When the lifting mechanism moves, the adjusting part is driven by the lifting mechanism to extend outward along the peripheral wall of the inner sleeve until the adjusting part abuts against the inner wall of the metal pipe, and the extended end of the lifting mechanism is locked and fixed to the top of the inner sleeve, thereby achieving the fixation of the locking mechanism and the end of the metal pipe.

[0010] Specifically, the locking mechanism also includes an outer sleeve located outside the metal pipe and used to prevent the metal pipe from cracking, and the outer sleeve is adapted to the inner sleeve; the lifting mechanism extends through the top of the outer sleeve, and the extended end of the lifting mechanism is locked and fixed to the top of the outer sleeve.

[0011] Furthermore, the difference between the inner diameter of the outer bushing and the outer diameter of the metal pipe is ≤0.2 mm.

[0012] Furthermore, the inner bushing and the outer bushing are both steel bushings.

[0013] Specifically, the protruding end of the lifting mechanism is also provided with a lifting ring for connecting with the annealing rack.

[0014] Specifically, the lifting mechanism is further provided with a gasket assembly, and the gasket assembly is located between the adjusting portion and the top wall of the inner sleeve.

[0015] Furthermore, the gasket assembly includes a plurality of steel gaskets arranged at equal intervals, and each of the steel gaskets is fixedly sleeved on the lifting mechanism.

[0016] Specifically, the lifting mechanism includes a vertically arranged lifting core rod and a horizontally arranged base, the upper surface of the base is a continuous slope structure; the base is gap-matched with the inner wall of the inner bushing;

[0017] The lifting core rod is installed with a fastening assembly after passing through the inner bushing, and the fastening assembly includes a fastening nut adapted to the lifting core rod, the protruding end of the lifting core rod is provided with a first thread, and the inner ring of the fastening nut is provided with a second thread matched with the first thread;

[0018] The lifting core rod is moved in the vertical direction by rotating the fastening nut and utilizing the cooperation between the first thread and the second thread.

[0019] Specifically, the adjustment part includes: a plurality of adjustment balls located in a space area formed by the base and the inner sleeve, an arc groove for constraining the movement trajectory of the adjustment balls is formed on the upper surface of the base, and an opening adapted to the arc groove is formed on the peripheral wall of the inner sleeve, and the size of the opening is smaller than the diameter of the adjustment ball;

[0020] The lifting core rod is moved in the vertical direction, driving the adjusting ball to move along the arc groove until the adjusting ball extends outward through the opening and abuts against the inner wall of the metal pipe, and the fastening nut is used to lock and fix the protruding end of the lifting core rod to the top of the inner sleeve, thereby completing the fixation of the locking mechanism to the end of the metal pipe.

[0021] Furthermore, the volume of the adjusting ball after extending outward through the opening is defined as V 伸出 , define the volume of the adjustment ball as V 整体 , and V 伸出 <0.5V 整体 .

[0022] Preferably, a transition arc is provided at the connection between the lifting core rod and the base.

[0023] On the other hand, the present invention also provides an annealing tool for metal pipes, comprising: a locking mechanism for preventing the metal pipes from deforming during the annealing process in a vacuum atmosphere or inert gas protection and improving the straightness and ovality of the metal pipes, and an annealing rack for vertically hanging the metal pipes; the metal pipes are thin-walled pipes or ultra-thin-walled pipes, and the locking mechanism is a locking mechanism for annealing the metal pipes described above in part or in whole;

[0024] The locking mechanism is detachably mounted on the upper and lower ends of the metal pipe, respectively; the upper end of the metal pipe is fixedly connected to the top of the annealing rack through the locking mechanism; the lower end of the metal pipe is fixedly connected to the bottom of the annealing rack through the locking mechanism, the counterweight and the fasteners.

[0025] Specifically, after annealing, the ovality of the metal tube is 0-0.05 mm, and the straightness is ≤0.5 mm / 1000 mm.

[0026] Specifically, the mass of the counterweight is not greater than 0.5R p0.2 S / g, where R p0.2 is the yield strength of the metal pipe after annealing (the yield strength is obtained by annealing a small sample in a test furnace using the same process and testing after annealing), S is the cross-sectional area of ​​the metal pipe, and g is the acceleration of gravity.

[0027] In addition, the present invention also provides an annealing method for a metal pipe, firstly, according to the uniform temperature zone size, heating method, heating belt layout structure and size of the metal pipe of the vacuum annealing furnace or the inert gas protection furnace, an annealing tool for the metal pipe as described above is manufactured, and the annealing method comprises the following steps:

[0028] Step 1: pre-treat the metal pipe;

[0029] Step 2: Dry the pretreated metal pipe to ensure that the dryness meets the annealing requirements;

[0030] Step 3, inserting the locking mechanism into both ends of the metal pipe to be annealed, and fixing the locking mechanism and the end of the metal pipe by adjusting the adjustment component;

[0031] Step 4: hang one end of the metal pipe on the top of the annealing rack, hang a counterweight on the other end, and connect the counterweight to the bottom of the annealing rack with a fastener to prevent collision between the metal pipes to be annealed during the movement of the annealing rack;

[0032] Step 5: placing the annealing rack into a vacuum annealing furnace and completing vacuum annealing according to set annealing process parameters.

[0033] Specifically, the annealing process parameters in step 5 include:

[0034] The temperature of the vacuum annealing furnace is set to 0.8-0.95T, and the temperature averaging time t1 is 30-90min, where T is the annealing temperature;

[0035] Set the annealing temperature to 0.2~0.45T m The holding time t2 is 20 to 500 min, and the vacuum degree in the furnace is not greater than 1×10 -2 Pa, where T m The melting point of the metal.

[0036] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0037] 1) The locking mechanism is designed by combining the inner sleeve, the lifting mechanism and the adjusting part. The lifting and lowering of the lifting mechanism drives the adjusting part to extend / retract outward along the peripheral wall of the inner sleeve to adjust the distance between the adjusting part and the inner wall of the metal pipe. The extended end of the lifting mechanism is locked and fixed to the top of the inner sleeve, thereby fixing the locking mechanism and the end of the metal pipe, further ensuring that the metal pipe does not undergo dimensional deformation during the annealing process, improving the straightness and ovality of the pipe, and being beneficial to improving the heat treatment efficiency of thin-walled metal pipes and ultra-thin-walled metal pipes, and improving the pipe yield rate.

[0038] 2) The annealing fixture is suitable for batch annealing tests of thin-walled metal pipes and ultra-thin-walled metal pipes in horizontal annealing furnaces and vertical annealing furnaces. The annealing fixture includes an annealing rack and a locking mechanism. By setting positioning holes around the annealing rack, the annealing rack can be conveniently connected to the annealing furnace trolley, and the size of the annealing rack can be made according to the size of the uniform temperature zone of the annealing furnace chamber. The annealing fixture solves the problem of deformation of thin-walled metal pipes and ultra-thin-walled metal pipes during the traditional annealing process, improves the straightness and ovality of thin-walled metal pipes and ultra-thin-walled metal pipes after annealing, reduces the processes of shaping and straightening after annealing of metal pipes, and reduces the amount of waste generated in the subsequent processing of metal pipes. Compared with the problems of small furnace loading, low annealing efficiency and high cost in traditional vertical annealing furnaces, the use of this annealing fixture can significantly increase the furnace loading and annealing efficiency, thereby reducing production costs. At the same time, the problem of the traditional vertical annealing pipe punching process and other vertical annealing methods that cannot perform recrystallization annealing is avoided, thereby improving material utilization.

[0039] 3) Whether the annealing tool is used in a horizontal annealing furnace or a vertical annealing furnace, the metal pipe can always be placed vertically in the annealing furnace. The distance between the metal pipes can be adjusted by adjusting the hook position on the annealing rack to ensure that there is a certain gap between the metal pipes. With this method of laying, whether the metal pipes are heat treated under vacuum conditions or under inert gas protection, the heat generated by the heating body in the annealing furnace is quickly transferred to the surface of the metal pipe by thermal radiation and thermal convection, reducing the time difference of the metal pipes at different positions in the furnace during large-scale annealing, avoiding the phenomenon of increased performance fluctuations of the metal pipes due to inconsistent heat treatment temperatures and insulation times of metal pipes at different positions, eliminating the "hot outside and cold inside" phenomenon of pipes caused by traditional batch annealing methods, and improving the stability of the size and performance of thin-walled metal pipes and ultra-thin-walled metal pipes subjected to batch heat treatment. In terms of pipe straightness control, by hanging a counterweight at the bottom of the metal pipe and adjusting the weight of the counterweight according to the mechanical properties of the metal pipe, it is possible to effectively avoid bending, twisting and other deformation phenomena caused by stress release during the annealing process of the metal pipe, thereby improving the straightness and ovality of the metal pipe.

[0040] 4) The metal pipes are hung on the loading platform and fixed to the annealing rack. The annealing rack can be hoisted as a whole and placed in the annealing furnace by a crane or other equipment, and the annealing rack and the annealing car are fixed by positioning pins, which significantly improves the loading / unloading efficiency.

[0041] In summary, the present invention provides a locking mechanism, annealing tool and annealing method for metal pipe annealing, the locking mechanism can ensure that thin-walled pipes and ultra-thin-walled pipes do not undergo dimensional deformation during vacuum annealing, can effectively improve the pipe straightness and ovality of thin-walled pipes and ultra-thin-walled pipes, improve the heat treatment efficiency of thin-walled pipes and ultra-thin-walled pipes, and significantly improve the yield rate of thin-walled pipes and ultra-thin-walled pipes. Moreover, the annealing process of the annealing tool using the locking mechanism has a simple process, greatly reduces the manufacturing cost, and is conducive to popularization and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The accompanying drawings are incorporated in and constitute a part of this specification and, together with the description, serve to explain the principles of the present invention.

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0044] Figure 1 A schematic diagram of the structure of the locking mechanism provided by the present invention;

[0045] Figure 2 A schematic diagram of the structure of an annealing rack applicable to a vertical annealing furnace provided by the present invention;

[0046] Figure 3 A schematic diagram of the structure of an annealing rack suitable for a horizontal annealing furnace provided by the present invention;

[0047] Figure 4 A schematic diagram of the structure of a metal pipe installed on a vertical annealing rack provided in Example 3 of the present invention;

[0048] Figure 5 A schematic diagram of the structure of a metal pipe installed on a horizontal annealing rack provided in Example 4 of the present invention;

[0049] Figure 6 The present invention provides a flow chart of the annealing process of the metal pipe.

[0050] Among them: 1. Metal pipe; 2. Inner bushing; 3. Outer bushing; 4. Lifting core rod; 5. Adjusting ball; 6. Opening; 7. Lifting ring; 8. Gasket assembly; 9. Adjusting nut; 10. First thread; 11. Transition arc; 12. Annealing rack; 13. Base. DETAILED DESCRIPTION

[0051] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are merely examples consistent with some aspects of the present invention as detailed in the appended claims.

[0052] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0053] Example 1

[0054] See also Figure 1 As shown, this embodiment provides a locking mechanism for annealing a metal pipe, which is installed at the end of a metal pipe 1, and the locking mechanism includes an inner sleeve 2, and a lifting mechanism is provided in the inner sleeve 2 that passes through the top thereof and can move in a vertical direction, and an adjusting portion that can extend or retract along the peripheral wall of the inner sleeve is provided at the bottom of the lifting mechanism;

[0055] When the lifting mechanism moves, the adjusting part is driven by the lifting mechanism to extend outward along the peripheral wall of the inner sleeve 2 until the adjusting part abuts against the inner wall of the metal pipe, and the extended end of the adjusting part is locked and fixed to the top of the inner sleeve 2, thereby achieving the fixation of the locking mechanism and the end of the metal pipe.

[0056] Furthermore, the locking mechanism also includes an outer sleeve 3 located outside the metal pipe and used to prevent the metal pipe from cracking, and the outer sleeve 3 is adapted to the inner sleeve 2; the lifting mechanism extends through the top of the outer sleeve 3, and the extended end of the lifting mechanism is locked and fixed to the top of the outer sleeve 3.

[0057] Furthermore, the lifting mechanism includes a vertically arranged lifting core rod 4 and a horizontally arranged base 13 (the lifting core rod 4 and the base 13 together form a "T"-shaped core rod), and the upper surface of the base 13 is a continuous slope structure; the base 13 is in clearance with the inner wall of the inner bushing 2;

[0058] After the lifting core rod 4 passes through the inner bushing 2, a fastening assembly is installed, and the fastening assembly includes a fastening nut 9 adapted to the lifting core rod 4, the protruding end of the lifting core rod 4 is provided with a first thread, and the inner ring of the fastening nut 9 is provided with a second thread matched with the first thread;

[0059] By rotating the fastening nut 9, the lifting core rod 4 is moved in the vertical direction by utilizing the cooperation between the first thread and the second thread.

[0060] Further, the adjustment part includes: a plurality of adjustment balls 5 located in the space formed by the base 13 and the inner bushing 2, an arc groove for constraining the movement trajectory of the adjustment balls 5 is provided on the upper surface of the base 13, and an opening 6 adapted to the arc groove is provided on the peripheral wall of the inner bushing 2, and the size of the opening 6 is smaller than the diameter of the adjustment ball 5;

[0061] By moving the lifting core rod 4 in the vertical direction, the adjusting ball 5 is driven to move along the arc groove until the adjusting ball 5 extends outward through the opening 6 and abuts against the inner wall of the metal pipe 1, and the extending end of the lifting core rod 4 is locked and fixed to the top of the inner sleeve 2 by using the fastening nut 9, thereby completing the fixation of the locking mechanism and the end of the metal pipe 1.

[0062] Furthermore, the size of the opening 6 is smaller than the diameter of the adjusting ball 5; the volume of the adjusting ball 5 after extending outward through the opening 6 is defined as V 伸出 , define the volume of the regulating ball 5 as V 整体 , and V 伸出 <0.5V 整体 .

[0063] Furthermore, the difference between the inner diameter of the outer bushing and the outer diameter of the metal pipe is ≤0.2 mm.

[0064] Furthermore, the inner bushing and the outer bushing are both steel bushings.

[0065] Specifically, the lifting mechanism is further provided with a lifting ring 7 for connecting with the annealing rack 12 .

[0066] Specifically, the lifting mechanism is further provided with a gasket assembly 8 , and the gasket assembly 8 is located between the adjusting portion and the top wall of the inner sleeve 2 .

[0067] Furthermore, the gasket assembly 8 includes a plurality of steel gaskets, each of which is fixedly sleeved on the lifting core rod 4 .

[0068] Preferably, a transition arc 11 is provided at the connection between the lifting core rod 4 and the base 13 .

[0069] Specifically, the thin-walled metal pipe is a thin-walled pipe (20<D / S≤40) or an ultra-thin-walled pipe (D / S>40).

[0070] Specifically, the number of adjusting balls 5 can be adaptively selected according to the inner diameter of the inner sleeve 2 and the inner diameter of the pipe. For example, in this embodiment, the number of adjusting balls is 3, and the number of openings 6 is the same as the number of adjusting balls 5.

[0071] Example 2

[0072] On the basis of Example 1, this embodiment provides an annealing tool for a metal pipe, comprising: a locking mechanism for preventing the metal pipe 1 from deforming during vacuum annealing and improving the straightness and ovality of the metal pipe 1, and an annealing rack 12 for vertically suspending the metal pipe 1; the metal pipe 1 is a thin-walled pipe or an ultra-thin-walled pipe, and the locking mechanism is a locking mechanism for annealing the metal pipe as described above in part or in whole; the locking mechanism can be detachably installed at the upper end and the lower end of the metal pipe 1, respectively.

[0073] For a single-layer annealing rack, the upper end of the metal tube 1 is fixedly connected to the top of the annealing rack 12 through a locking mechanism, and the lower end of the metal tube 1 is fixedly connected to the bottom of the annealing rack 12 through a locking mechanism, a counterweight and a fastener. For a multi-layer annealing rack, taking a separate rack chamber capable of hanging the metal tube 1 as an example, in each rack chamber, the upper end of the metal tube 1 is fixedly connected to the top of the current rack chamber through a locking mechanism, and the lower end of the metal tube 1 is fixedly connected to the bottom of the current rack chamber through a locking mechanism, a counterweight and a fastener.

[0074] Here, the suspended counterweight method of the counterweight and fastener is adopted, that is, the ring 7 of the locking mechanism at the lower end of the metal pipe 1 is connected to the counterweight through a chain, so as to ensure that the position of the metal pipe 1 is fixed at high temperature, and avoid position movement caused by factors such as gravity or thermal expansion, thereby ensuring the uniformity and consistency of the annealing treatment.

[0075] Preferably, the mass of the counterweight is not greater than 0.5R p0.2 S / g,R p0.2 is the yield strength of the metal tube 1 after annealing, S is the cross-sectional area of ​​the metal tube 1, and g is the acceleration due to gravity. p0.2 , is obtained by annealing a small sample in a test furnace using the same process and testing it after annealing.

[0076] Preferably, the ratio of the length of the metal tube 1 to the height of the annealing rack is about 1:1.5.

[0077] Specifically, after annealing, the maximum ovality of the metal tube 1 is 0.05 mm, and the maximum straightness is 0.5 mm / 1000 mm.

[0078] Specifically, a hook for hanging the metal pipe 1 is provided on the top of the annealing rack 12 , and the distance between the metal pipes 1 can be adjusted by adjusting the position of the hook on the annealing rack 12 (the minimum distance is 3 mm).

[0079] Specifically, positioning holes are arranged around the annealing rack 12 to facilitate the connection between the annealing rack 12 and the annealing furnace trolley, and the size of the annealing rack 12 can be made according to the size of the uniform temperature zone of the annealing furnace chamber, and the number of positioning holes can be adaptively adjusted according to the size of the annealing rack 12.

[0080] Example 3

[0081] This embodiment provides an annealing method for a metal pipe. First, an annealing tool corresponding to the metal pipe 1 is manufactured according to the uniform temperature zone size, heating method, heating belt layout structure and size of the metal pipe to be annealed of the vacuum annealing furnace chamber. Figure 6 As shown, the annealing method comprises the following steps:

[0082] Step 1: Pre-treat the metal pipe to be annealed:

[0083] First, the thin-walled TA2 titanium alloy tube (diameter × wall thickness × length, Φ50 × 2 × 800 mm) was ultrasonically cleaned twice, each time for 30 minutes; then the tube was taken out of the sink and placed on the work platform, the outer surface of the tube was wiped with a white cotton cloth soaked in alcohol, and the inner surface was cleaned with a sponge block or sponge ball sprayed with compressed air until there was no obvious stain on the white cotton cloth, sponge block or sponge ball;

[0084] Step 2, drying the pretreated metal pipe 1 to ensure that the dryness meets the annealing requirements; wherein the drying temperature is 60°C, the drying time is 60 minutes, and after the drying is completed, visually inspect the inner and outer surfaces of the pipe to ensure that the dryness meets the annealing requirements;

[0085] Step 3: A vertical vacuum annealing furnace is used to carry out heat treatment tests. The heating elements are evenly distributed in the furnace, and the effective heating range is Ф1000×3000mm. The vertical vacuum annealing furnace is equipped with a furnace temperature control system and a vacuum system to achieve precise control of the temperature in the furnace and high vacuum. According to the effective heating range of the vertical vacuum annealing furnace, a special annealing rack 12 is designed (see Figure 2 The double-layer rack shown in the figure has a size of Ф1000×3000mm;

[0086] Step 4: Insert the two ends of the metal pipe to be annealed into the locking mechanism on the loading platform, then slowly turn the adjusting nut 9 to fix the pipe to be annealed, and then hang one end of the pipe on the top of the annealing rack 12, and hang a stainless steel block as a counterweight (mass 10 kg) on ​​the other end through a chain, and connect the stainless steel block to the bottom of the annealing rack 12 with a steel wire to prevent the pipes from colliding with each other during the movement of the annealing rack 12, thereby damaging the surface quality of the pipes;

[0087] Step 5: Place the annealing rack 12 into a vacuum annealing furnace, wherein the vertical annealing furnace adopts a layered loading method (see Figure 4 As shown), grids are used between adjacent layers ( Figure 4 When loading the furnace, the pipes on each layer of the rack can be operated at the same time. According to the material of the metal pipe 1, the pipe annealing process is set: the heating rate is 2℃ / min, the annealing process sets the temperature platform, the temperature is 550℃, the temperature averaging time is 30min, the annealing temperature is 650℃, and the holding time is 60min. The pipe loading volume is 2 / 3 of the volume of the annealing furnace chamber temperature averaging zone. After the loading is completed, close the annealing furnace door. Start to evacuate. When the vacuum degree in the furnace is not more than 1×10 -2 When Pa, the annealing furnace temperature control system is turned on, and annealing is performed according to the set annealing curve (determined by the above-mentioned annealing process parameters).

[0088] Step 6: After the heat treatment of the pipe is completed, when the temperature in the furnace is lower than 100°C, open the annealing furnace, pull the annealing rack 12 out of the annealing furnace, take out the metal pipes 1 one by one, and cut off the contact area between the two ends of the pipe and the locking mechanism according to the size requirements in the technical conditions of the pipe (it can also be cut off in the subsequent cutting and sizing process, which is conducive to reducing the total blind area cutting amount), and then immediately put a filler (such as natural rubber) that does not damage the inner surface of the metal pipe 1 into the pipe to prevent the finished pipe from deforming during transportation.

[0089] Implementation effect: The finished pipes are placed on a marble platform for inspection. The ovality of the pipes is ≤0.05mm, and the straightness of the pipes is ≤0.45mm / 1000mm. The ovality and straightness bending of the finished pipes meet the technical requirements.

[0090] Example 4

[0091] This embodiment provides an annealing method for a metal pipe. First, according to the size of the uniform temperature zone of the vacuum annealing furnace chamber, the heating method, the layout structure of the heating belt, and the size of the metal pipe to be annealed, an annealing tool corresponding to the metal pipe is manufactured. The annealing method includes the following steps:

[0092] Step 1: Pre-treat the metal pipe to be annealed:

[0093] First, the ultra-thin-wall Zr-4 zirconium alloy pipe (diameter × wall thickness × length, Φ20 × 0.4 × 500mm) was ultrasonically cleaned twice, each time for 30 minutes; then the pipe was taken out of the water tank and placed on the working platform, the outer surface of the pipe was wiped with a white cotton cloth soaked in alcohol, and the inner surface was cleaned with a sponge block or sponge ball sprayed with compressed air until there was no obvious stain on the white cotton cloth, sponge block or sponge ball;

[0094] Step 2: Dry the pretreated metal pipe to ensure that the dryness meets the annealing requirements; wherein the drying temperature is 100°C and the drying time is 40 minutes. After the drying is completed, visually inspect the inner and outer surfaces of the pipe to ensure that the dryness meets the annealing requirements;

[0095] Step 3: Use a horizontal vacuum annealing furnace to carry out heat treatment tests. The heating elements are evenly distributed in the furnace, and the effective heating range is 4000mm (length) × 1000mm (width) × 1200mm (height). The horizontal vacuum annealing furnace is equipped with a furnace temperature control system and a vacuum system to achieve precise control of the temperature in the furnace and high vacuum. According to the effective heating range of the horizontal vacuum annealing furnace, a special annealing rack 12 is designed (see Figure 3 The dimensions are 4000mm (length) × 1000mm (width) × 1200mm (height);

[0096] Step 4: insert the two ends of the metal pipe to be annealed into the locking mechanism on the loading platform, then slowly turn the adjusting nut 9 to fix the metal pipe to be annealed, and then hang one end of the metal pipe on the top of the annealing rack 12, and hang a stainless steel block as a counterweight (mass 5 kg) on ​​the other end, and connect the stainless steel block to the bottom of the annealing rack 12 with a steel wire to prevent the pipes from colliding with each other during the movement of the annealing rack 12 and damaging the surface quality of the pipes;

[0097] Step 5: Place the annealing rack 12 into a vacuum annealing furnace. Figure 5 As shown, the horizontal annealing furnace adopts a single-layer loading method, and the pipes are hung one by one on the annealing rack 12. According to the material of the metal pipe, the pipe annealing process is set: the heating rate is 2.5℃ / min, the annealing process sets the temperature platform, the temperature is 450℃, the temperature equalization time is 30min, the annealing temperature is 550℃, and the insulation time is 300min. The pipe loading volume is 2 / 3 of the volume of the temperature equalization zone of the annealing furnace chamber. After the loading is completed, close the annealing furnace door. Start to evacuate. When the vacuum degree in the furnace is not more than 1×10 -2 When Pa, the annealing furnace temperature control system is turned on, and annealing is performed according to the set annealing curve (determined by the aforementioned annealing process parameters).

[0098] Step 6: After the heat treatment of the pipe is completed, when the temperature in the furnace is lower than 100°C, open the annealing furnace, pull the annealing rack 12 out of the annealing furnace, take out the metal pipes 1 one by one, and cut off the contact area between the two ends of the pipe and the locking device according to the size requirements in the technical conditions of the pipe (it can also be cut off in the subsequent cutting and sizing process, which is conducive to reducing the total blind area cutting amount), and then immediately put fillers made of polyurethane or other materials into the pipe to prevent deformation of the finished pipe during transportation.

[0099] In this embodiment, the metal pipe to be annealed is suspended on the loading platform and fixed to the annealing rack 12. The annealing rack 12 can be hoisted as a whole and placed in the annealing furnace by using an overhead crane or other equipment, and the annealing rack 12 is fixed to the annealing car by positioning pins, which significantly improves the loading / unloading efficiency.

[0100] Implementation effect: The finished pipes are placed on a marble platform for inspection. The ovality of the pipes is ≤0.03mm, and the straightness of the pipes is ≤0.3mm / 1000mm. The ovality and straightness of the finished pipes meet the technical requirements.

[0101] It should be noted that the technical solution provided by the present invention is not limited to the application in the annealing process of thin-walled titanium tubes and ultra-thin-walled zirconium alloy tubes given in the above embodiments, but can also be applied to the annealing process of thin-walled or ultra-thin-walled Hastelloy tubes, aluminum tubes, copper tubes, steel tubes and other metal tubes, which is beneficial to improve the straightness of the tube, improve the heat treatment efficiency of thin-walled tubes and ultra-thin-walled tubes, and thus improve the yield rate of the tube.

[0102] The above description is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0103] It should be understood that the present invention is not limited to what has been described above and that various modifications and changes may be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A locking mechanism for metal pipe annealing, characterized in that: The locking mechanism is installed at the end of the metal pipe (1), and the locking mechanism comprises an inner sleeve (2), a lifting mechanism passing through the top of the inner sleeve (2) and capable of moving in a vertical direction is provided inside the inner sleeve (2), and an adjusting portion capable of extending or retracting along the peripheral wall of the inner sleeve (2) is provided at the bottom of the lifting mechanism; When the lifting mechanism moves, the adjusting portion is driven by the lifting mechanism to extend outward along the peripheral wall of the inner sleeve (2) until the adjusting portion abuts against the inner wall of the metal pipe (1), and the extended end of the lifting mechanism is locked and fixed to the top of the inner sleeve (2), thereby achieving the fixation of the locking mechanism and the end of the metal pipe (1).

2. The locking mechanism for metal pipe annealing according to claim 1, characterized in that: The locking mechanism also includes an outer sleeve (3) located outside the metal pipe (1) and used to prevent the metal pipe (1) from cracking, and the outer sleeve (3) is compatible with the inner sleeve (2); the lifting mechanism extends through the top of the outer sleeve (3), and the protruding end of the lifting mechanism is locked and fixed with the top of the outer sleeve (3).

3. The locking mechanism for metal pipe annealing according to claim 2, characterized in that: The difference between the inner diameter of the outer bushing (3) and the outer diameter of the metal pipe (1) is ≤0.2 mm.

4. The locking mechanism for metal pipe annealing according to claim 1, characterized in that: The protruding end of the lifting mechanism is also provided with a lifting ring (7) for connecting with the annealing material rack (12).

5. The locking mechanism for metal pipe annealing according to claim 1, characterized in that: The lifting mechanism is also sleeved with a gasket assembly (8), and the gasket assembly (8) is located between the adjustment portion and the top wall of the inner liner (2).

6. The locking mechanism for metal pipe annealing according to claim 1, characterized in that: The lifting mechanism comprises a lifting core rod (4) arranged vertically and a base (13) arranged horizontally, wherein the upper surface of the base (13) is a continuous slope structure; the base (13) is in clearance fit with the inner wall of the inner bushing (2); The lifting core rod (4) is installed with a fastening assembly after passing through the inner bushing (2), and the fastening assembly includes a fastening nut (9) adapted to the lifting core rod (4), the protruding end of the lifting core rod (4) is provided with a first thread, and the inner ring of the fastening nut (9) is provided with a second thread matched with the first thread; By rotating the fastening nut (9), the first thread and the second thread cooperate with each other to achieve the movement of the lifting core rod (4) in the vertical direction.

7. The locking mechanism for metal pipe annealing according to claim 6, characterized in that: The adjusting portion comprises: a plurality of adjusting balls (5) located in a space area formed by the base (13) and the inner bushing (2); an arc groove for constraining the moving trajectory of the adjusting balls (5) is provided on the upper surface of the base (13); an opening (6) adapted to the arc groove is provided on the peripheral wall of the inner bushing (2); and the size of the opening (6) is smaller than the diameter of the adjusting balls (5); The lifting core rod (4) moves in the vertical direction, driving the adjusting ball (5) to move along the arc groove until the adjusting ball (5) extends outward through the opening (6) and abuts against the inner wall of the metal pipe (1), and the fastening nut (9) is used to lock and fix the protruding end of the lifting core rod (4) to the top of the inner sleeve (2), thereby completing the fixation of the locking mechanism to the end of the metal pipe (1).

8. The locking mechanism for metal pipe annealing according to claim 7, characterized in that: The volume of the regulating ball (5) after extending outward through the opening (6) is defined as V 伸出 , define the volume of the regulating ball (5) as V 整体 , and V 伸出 <0.5V 整体 .

9. The locking mechanism for metal pipe annealing according to claim 7, characterized in that: A transition arc (11) is provided at the connection between the lifting core rod (4) and the base (13).

10. A metal pipe annealing tool, characterized in that: include: A locking mechanism for preventing the metal tube (1) from being deformed during annealing in a vacuum atmosphere or inert gas protection and improving the straightness and ovality of the metal tube (1), and an annealing rack (12) for vertically hanging the metal tube (1); the metal tube (1) is a thin-walled tube or an ultra-thin-walled tube, and the locking mechanism is a locking mechanism for annealing the metal tube (1) as claimed in any one of claims 2 to 9; The locking mechanisms are detachably mounted on the upper and lower ends of the metal pipe (1), respectively; the upper end of the metal pipe (1) is fixedly connected to the top of the annealing rack (12) via the locking mechanism; the lower end of the metal pipe (1) is fixedly connected to the bottom of the annealing rack (12) via the locking mechanism in conjunction with a counterweight and a fastener.

11. The annealing tool for metal pipe according to claim 10, characterized in that: After annealing, the metal tube (1) has an ovality of 0 to 0.05 mm and a straightness of ≤0.5 mm / 1000 mm.

12. A method for annealing a metal pipe, comprising: firstly manufacturing an annealing tool for the metal pipe (1) as claimed in claim 10 or 11 according to the size of the uniform temperature zone of the vacuum annealing furnace or the inert gas protection furnace chamber, the heating method, the layout structure of the heating belt and the size of the metal pipe, wherein: The annealing method comprises the following steps: Step 1, pre-treating the metal pipe (1); Step 2, drying the pretreated metal pipe (1) to ensure that the dryness meets the annealing requirements; Step 3, inserting the locking mechanism into the two ends of the metal pipe (1) to be annealed respectively, and fixing the locking mechanism and the end of the metal pipe (1) by adjusting the adjustment component; Step 4: Hang one end of the metal pipe (1) on the top of the annealing rack (12), hang a counterweight on the other end, and connect the counterweight to the bottom of the annealing rack (12) with a fastener to prevent the metal pipes (1) to be annealed from colliding with each other during the movement of the annealing rack (12); Step 5: placing the annealing rack (12) into a vacuum annealing furnace and performing vacuum annealing according to set annealing process parameters.

13. The annealing method of a metal pipe according to claim 12, characterized in that: The annealing process parameters in step 5 include: The temperature of the vacuum annealing furnace is set to 0.8-0.95T, and the temperature averaging time t1 is 30-90min, where T is the annealing temperature; Set the annealing temperature to 0.2~0.45T m The holding time t2 is 20 to 500 min, and the vacuum degree in the furnace is not greater than 1×10 -2 Pa, where T m The melting point of the metal.

Images