Welding assembly and welding method for medical CT metal bulb tube shell

Abstract

The invention discloses a welding assembly and a welding method for a medical CT metal bulb tube shell. The welding assembly comprises a base, a tool protection side plate, an upper fixing seat and a lower fixing seat, wherein the tool protection side plate is fixed to the base and used for limiting the CT metal bulb tube shell, and the upper fixing seat and the lower fixing seat are fixed to the base and used for assembling the CT metal bulb tube shell. The welding method comprises the steps that S1, a to-be-welded assembly part is assembled; s2, vacuum welding; s3, discharging and leakage detection; s4, welding a window area; the welding assembly can be positioned and assembled so as to realize integrated welding, the welding method can avoid deformation caused by nonuniform internal structure of a material to be welded due to nonuniform furnace temperature, meanwhile, the problems of collision damage, scratch and the like caused by shape correction are solved, the assembly production and processing period is effectively shortened, and the production efficiency is improved. The production efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of welding, and in particular to a welding assembly and a welding method for a medical CT metal ball tube shell. Background Art

[0002] The CT tube is the core component of the CT (Computed Tomography) scanner, which contains the X-ray tube that generates X-rays. The main function of the CT tube is to generate high-energy X-ray beams, which pass through the patient's body, are captured by the detector, and then processed by the computer to generate cross-sectional images. The structure of the CT tube usually includes the X-ray tube, vacuum chamber, insulating oil, and tube shell. The X-ray tube contains a cathode (generating an electron beam) and an anode (receiving an electron beam and generating X-rays). The vacuum chamber is a sealed vacuum environment in which the electron beam moves from the cathode to the anode. Insulating oil is an oil used for cooling and insulation, which is filled between the vacuum chamber shell and the tube shell. The tube shell is the shell that protects the X-ray tube and is usually made of metal. The internal structure of the CT tube is complex, with many types of parts and involving many disciplines. The selection of materials is crucial. Many parts are used in a vacuum environment, and the material cannot release gas at high temperatures, so as to ensure the service life of the tube.

[0003] In the prior art, after the shell and casing parts of the CT tube are processed, they need to be assembled and welded multiple times in graded temperature steps. Multiple welding may cause deformation of the metal parts, which will cause trouble for each welding assembly. The deformation will lead to problems such as the final assembly being unsuitable. The use of a deformed shell and casing may cause problems such as reduced CT image quality, damage to internal components of the tube, increased maintenance costs, and safety issues. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a welding assembly and a welding method for a medical CT metal ball tube shell.

[0005] A welding assembly for a medical CT metal tube shell; comprising a base, a tooling protection side plate fixed on the base for limiting the CT metal tube shell, and an upper fixing seat and a lower fixing seat fixed on the base for assembling the CT metal tube shell, wherein the upper fixing seat and the lower fixing seat are clamped by a clamp, the lower fixing seat is clamped with the base, and a beryllium window welding movable pressing block is provided on the upper fixing seat.

[0006] A method for welding a medical CT metal tube shell comprises the following steps: S1. Assemble the parts to be welded; Cleaning the various components of the CT metal tube shell, the components of the CT metal tube shell include a stainless steel ring, a tube shell, a kovar ring, a grounding block and a beryllium window; firstly, the stainless steel ring is matched with the tooling for fixing the various components for installation, and then the stainless steel ring is matched with the tube shell for installation, and then the kovar ring is placed on the port or connection of the tube shell for assembly and installation, and then the beryllium window is placed on the tube shell and fastened with the tooling; and then the heat dissipation strip and the grounding block are assembled to obtain the assembly to be welded; S2, vacuum welding; First, the vacuum furnace is preheated to a temperature of 800-900°C, and then the vacuum furnace is cooled to 400-500°C. The assembly to be welded is then placed in the vacuum furnace, and the pressure in the vacuum furnace is less than or equal to 6.5×10 -3 Pa, and when the temperature is raised to T-20~T-10℃ at a rate of 5~7℃ / min, welding is performed for a welding time of 0.1~5min to obtain a tooling part; wherein T is the melting point of the tube shell; S3, leak detection after furnace exit; After welding is completed, the temperature in the vacuum furnace is lowered to 100-200°C, and then the tooling and each component are taken out and a leak test is performed. If there is a component that fails the leak test, the component that fails the leak test is cleaned and step S2 is repeated until the leak test is passed and the next step is performed; S4, welding window area; First, heat the vacuum furnace to 400-500°C, rotate the tooling by 90°, and weld the window area when the temperature is raised to T-20-T-10°C and the welding time is 0.1-3min. Then, perform a secondary leak test. If there are components that fail the secondary leak test, clean the components that fail the secondary leak test and repeat the welding of the window area until they pass the test.

[0007] Description: Welding by the above method can reduce the thermal deformation of shell parts at high temperature, avoid bumps and scratches caused by shape adjustment, effectively shorten the component production and processing cycle, and improve production efficiency; the process also has a high pass rate for welding tube shell components, small deformation of parts, and prevents the influence of shell deformation on subsequent processing. The finished component does not need to be shaped after the second welding of the window, and the various components can be positioned and assembled to facilitate integrated welding. By adjusting the temperature and preheating the vacuum furnace, the internal structure of the material to be welded due to uneven furnace temperature can be avoided, which causes deformation. The cleaning step can avoid cleaning residues such as welding slag generated by welding to avoid affecting the quality of the welded joint.

[0008] Furthermore, the material of the tube shell is oxygen-free copper.

[0009] Note: Since oxygen-free copper has good electrical conductivity and heat dissipation properties, it can ensure that the X-rays generated by the CT tube during operation have sufficient strength and stability, which helps to improve the clarity and accuracy of CT images.

[0010] Furthermore, the welding is performed by vacuum brazing.

[0011] Description: Vacuum brazing can ensure high-quality welds, avoid material deformation, reduce material loss, improve production efficiency, have wide applicability, good cleanliness and strength, etc.

[0012] Furthermore, the primary leak detection adopts a soap solution method, and the secondary leak detection adopts an ultrasonic method or a gas detection method.

[0013] Furthermore, the cleaning in step S1 is completed by a first cleaning agent, and the cleaning in S3 and S4 is completed by a second cleaning agent, the first cleaning agent includes alkyl glycoside, ethylene glycol monobutyl ether and glutamic acid tetraacetic acid in a mass ratio of 1:3~5:2, and the second cleaning agent includes citric acid, castor oil derivatives, borates and ethylenediaminetetraacetic acid in a mass ratio of 5~7:5:2~3:2.

[0014] Description: By using two different cleaning agents for cleaning before and after welding, the surface of the material corresponding to each step can be treated in a targeted manner to ensure high quality of welding; before welding, the material mainly needs to be cleaned of the surface oxide layer and grease layer, and the combination of alkyl polyglycoside, ethylene glycol monobutyl ether and glutamic acid tetraacetic acid can remove these impurities without damaging the metal surface, and has a good cleaning effect. After welding, the use of the second cleaning agent with the above ingredients can achieve efficient cleaning.

[0015] Furthermore, the preparation method of the second cleaning agent is: first, add castor oil derivatives to citric acid and mix and stir for 5 to 8 minutes; the stirring speed is 500 to 600 r / min, then add borate and ethylenediaminetetraacetic acid in sequence, and stir for 10 to 20 minutes; obtain a mixture, use a pH adjuster to adjust the pH of the mixture to 7, and obtain the second cleaning agent.

[0016] Description: The second cleaning agent prepared by the above method can achieve efficient cleaning, and at the same time, a protective film is formed on the metal surface after cleaning to prevent it from being further oxidized and corroded.

[0017] Furthermore, in S1, gaps are left between the components of the CT metal bulb tube shell, and the gap values ​​of the gaps are determined by the material expansion coefficient and structure of the material.

[0018] Note: Since the CT metal tube shell is a thin-walled component, the thin-walled component will expand at high temperatures, and the thermal deformation coefficient of each component is different, it is necessary to consider different material expansion coefficients and structures to determine the gap after assembly.

[0019] Furthermore, the gap value is calculated by the following formula: ; In the formula, is the gap value, is the gap contact surface length, is the average value of the thermal expansion coefficients of the two materials at the gap contact surface, K is the difference between the thermal conductivity of the tube shell and the thermal conductivity of the heat dissipation strip, P is the thermal power of the CT metal bulb when it is working, A is the area of ​​the heat dissipation strip, and t is the total welding time.

[0020] Note: In the prior art, the size of the gap to be retained in welding is usually determined through experience. Judging by experience alone may result in welding failing to achieve the desired effect, with slight deformation at the weld, air leakage after welding, etc. Therefore, calculating the appropriate gap is very important for welding the CT metal tube shell. The gap value calculated by the above formula is more practical, and the product after welding has a higher yield rate and a lower deformation rate.

[0021] Furthermore, the heat dissipation strip is a wavy heat dissipation strip.

[0022] Description: The wavy heat dissipation strip has a high heat dissipation efficiency and can make the temperature in the welding high-temperature furnace more uniform, reducing the uneven heating between various components, and is suitable for the welding process of the present invention.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: the welding method of the present invention can reduce the thermal deformation of shell parts at high temperatures, avoid bumps and scratches caused by shape adjustment, effectively shorten the component production and processing cycle, and improve production efficiency; the process also has a high pass rate for welding tube shell components, small deformation of parts, and prevents the influence of shell deformation on subsequent processing. The finished component does not need to be shaped after the second welding of the window, and the various components can be positioned and assembled to facilitate integrated welding. Through the temperature adjustment and preheating of the vacuum furnace, the internal structure of the material to be welded due to uneven furnace temperature can be avoided, thereby causing deformation. Through the cleaning step, the welding slag and other residues generated by welding can be avoided from being cleaned to avoid affecting the quality of the welded joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic diagram of the appearance of the welding assembly assembly of Example 1 of the present invention; Figure 2is a left side view of the welding assembly assembly of Example 1 of the present invention; Figure 3 is a front view of the welding assembly assembly of Example 1 of the present invention; Figure 4 It is a bottom view of the welding assembly assembly of Example 1 of the present invention.

[0025] Among them, 1-base, 2-CT metal tube shell, 3-tooling protection side plate, 4-upper fixed seat, 5-lower fixed seat, 6-beryllium window welding movable pressure block. DETAILED DESCRIPTION

[0026] In order to further illustrate the method adopted by the present invention and the effect achieved, the technical solution of the present invention will be clearly and completely described in combination with experiments below.

[0027] The embodiment of the present invention provides a welding assembly and a welding method for a medical CT metal ball tube shell. The assembly parts are assembled and the various parts are assembled and then welded as one piece. The effect of the one-piece welding can be optimized by setting the welding method and parameters, and deformation of the CT metal ball tube shell during welding can be avoided.

[0028] In the prior art, some argon arc welding areas after the assembly is welded need to be assembled with matching parts for argon arc welding. If the area after welding is deformed, it will affect the assembly and make the parts unable to be assembled. At the same time, the positioning tolerance requirements of each area of ​​the assembly should also be considered. If the positioning tolerance exceeds the tolerance seriously, it will cause the X-ray imaging to deviate from the preset trajectory. Since the welding is carried out in a vacuum furnace, the welding temperature is generally around 1000°C, and the temperature is 700°C until the last welding. Metal parts will deform after high-temperature welding, which will cause trouble for each welding assembly, and deformation will lead to problems in the final assembly. Therefore, a new welding method is needed, which not only ensures that the welding is not deformed, but also considers the better welding effect.

[0029] Example 1: Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown, a welding assembly of a medical CT metal tube shell includes a base 1, a tooling protection side plate 3 fixed on the base 1 for limiting the CT metal tube shell 2, and an upper fixing seat 4 and a lower fixing seat 5 fixed on the base 1 for assembling the CT metal tube shell 2, the upper fixing seat 4 and the lower fixing seat 5 are clamped by a clamp, the lower fixing seat 5 is clamped with the base 1, and a beryllium window welding movable pressing block 6 is provided on the upper fixing seat 4; A method for welding a medical CT metal tube shell is based on the above welding assembly and comprises the following steps: S1. Assemble the parts to be welded; Clean the various components of the CT metal tube shell 2, which include a stainless steel ring, a tube shell, a kovar ring, a grounding block and a beryllium window; first, install the stainless steel ring in conjunction with a welding assembly for fixing the various components, then install the stainless steel ring in conjunction with the tube shell, then place the kovar ring at the port or connection of the tube shell for assembly and installation, then place the beryllium window under the beryllium window welding movable pressing block 6, and fasten and fix it with a welding assembly; then assemble the heat sink and the grounding block to obtain an assembly to be welded; the tube shell is made of oxygen-free copper; vacuum brazing is used for welding; the heat sink is a wavy heat sink; The cleaning is completed by a first cleaning agent, and the raw materials of the first cleaning agent include alkyl glycoside, ethylene glycol monobutyl ether and glutamic acid tetraacetic acid in a mass ratio of 1:4:2; There are gaps between the components of the CT metal tube shell 2, and the gap value of the gap is determined by the material expansion coefficient and structure of the material; Specifically, the gap value is calculated by the following formula; ; In the formula, is the gap value, is the gap contact surface length, is the average value of the thermal expansion coefficients of the two materials on the gap contact surface, K is the difference between the thermal conductivity of the tube shell and the thermal conductivity of the heat sink, P is the thermal power of the CT metal tube when it is working, A is the area of ​​the heat sink, and t is the total welding time; after calculation, a gap of 0.75mm is left; S2, vacuum welding; First, preheat the vacuum furnace to 850°C, then cool the vacuum furnace to 450°C, and then put the assembly to be welded into the vacuum furnace. The pressure in the vacuum furnace is less than or equal to 6.5×10 -3 Pa, and when the temperature is raised to T-15℃ at a rate of 6℃ / min, welding is performed for 0.1~5min to obtain the tooling parts; wherein T is the melting point of the tube shell, which is 1080℃; S3, leak detection after furnace exit; After welding is completed, the temperature in the vacuum furnace is lowered to 150°C, and then the tooling and components are taken out and a leak test is performed. If there are components that fail the leak test, the components that fail the leak test are cleaned and the S2 step is repeated until the leak test is qualified. The next step is performed. The soap solution method is used for the leak test: S4, welding window area; First, heat the vacuum furnace to 450°C, rotate the tooling 90°, and when the temperature rises to T-20~T-10°C and the welding time is 1 minute, weld the window area, and then perform a secondary leak test. If there are components that fail the secondary leak test, clean the components that fail the secondary leak test and repeat the welding of the window area until they pass. The welding is completed; the secondary leak test uses ultrasonic method or gas detection method; The cleaning in S3 and S4 is completed by using a second cleaning agent, and the raw materials of the second cleaning agent include citric acid, castor oil derivative, borate and ethylenediaminetetraacetic acid in a mass ratio of 6:5:2.5:2; The preparation method of the second cleaning agent is as follows: first, add a castor oil derivative to citric acid and mix and stir for 6 minutes; then add borate and ethylenediaminetetraacetic acid in sequence at a stirring speed of 550 r / min, and stir for 15 minutes; obtain a mixture, and use a pH adjuster to adjust the pH of the mixture to 7 to obtain a second cleaning agent.

[0030] Example 2: This example is different from Example 1 in that the temperature parameters of vacuum welding are different. In S2, the vacuum furnace is first preheated to a temperature of 800°C, and then the vacuum furnace is cooled to 400°C. Subsequently, the assembly to be welded is placed in the vacuum furnace, and the pressure in the vacuum furnace is less than or equal to 6.5×10 -3 Pa, and when the temperature is raised to T-20℃ at a rate of 5℃ / min, the welding time is 0.1min; wherein T is the melting point of the tube shell, which is 1080℃.

[0031] Example 3: This example is different from Example 1 in that the temperature parameters of vacuum welding are different. In S2, the vacuum furnace is first preheated to a temperature of 900°C, and then the vacuum furnace is cooled to 500°C. Subsequently, the assembly to be welded is placed in the vacuum furnace, and the pressure in the vacuum furnace is less than or equal to 6.5×10 -3 Pa, and when the temperature is raised to T-10℃ at a rate of 7℃ / min, the welding time is 5min; where T is the melting point of the tube shell, which is 1080℃.

[0032] Embodiment 4: This embodiment is different from Embodiment 1 in that the leak detection temperature parameters are different. In S3, the temperature in the vacuum furnace is lowered to 100°C.

[0033] Embodiment 5: This embodiment is different from Embodiment 1 in that the leak detection temperature parameters are different. In S3, the temperature in the vacuum furnace is lowered to 200°C.

[0034] Example 6: This example is different from Example 1 in that the temperature parameters of the welding window area are different. In S4, the vacuum furnace is first heated to 400°C, the tooling is rotated 90°, and then heated to T-20°C and the welding time is 0.1 min.

[0035] Example 7: This example is different from Example 1 in that the temperature parameters of the welding window area are different. In S4, the vacuum furnace is first heated to 500°C, the tooling is rotated 90°, and then heated to T-10°C and the welding time is 3 minutes.

[0036] Example 8: This example is different from Example 1 in that the first cleaning agent includes alkyl glycoside, ethylene glycol monobutyl ether and glutamic acid tetraacetic acid in a mass ratio of 1:3:2.

[0037] Example 9: This example is different from Example 1 in that the first cleaning agent includes alkyl glycoside, ethylene glycol monobutyl ether and glutamic acid tetraacetic acid in a mass ratio of 1:5:2.

[0038] Example 10: This example is different from Example 1 in that the second cleaning agent includes citric acid, castor oil derivative, borate and ethylenediaminetetraacetic acid in a mass ratio of 5:5:3:2.

[0039] Example 11: This example is different from Example 1 in that the second cleaning agent includes citric acid, castor oil derivative, borate and ethylenediaminetetraacetic acid in a mass ratio of 7:5:2:2.

[0040] Example 12: This example is different from Example 1 in that the preparation method of the second cleaning agent is: first, add the castor oil derivative to citric acid and mix and stir for 5 minutes; then add borate and ethylenediaminetetraacetic acid in sequence at a stirring speed of 500 r / min, and stir for 10 minutes; obtain a mixture, and use a pH adjuster to adjust the pH of the mixture to 7.

[0041] Example 13: This example is different from Example 1 in that the preparation method of the second cleaning agent is: first, add the castor oil derivative to citric acid and mix and stir for 8 minutes; then add borate and ethylenediaminetetraacetic acid in sequence at a stirring speed of 600 r / min, and stir for 20 minutes; obtain a mixture, and use a pH adjuster to adjust the pH of the mixture to 7.

[0042] Experimental Example: The description of this experimental example is based on the scheme described in Example 1, and is intended to illustrate the practical application effect of the present invention.

[0043] Experimental Example: 1. The welded CT metal tube shells of Examples 1 to 13 were observed respectively, and no observable deformation occurred; 1. Explore the influence of different parameters on the performance of CT metal tube shell; Comparative Example 1: The difference from Example 1 is that the welding assembly of the CT metal tube shell adopts the pressing block counterweight method, the welding stability is very poor, the shell is severely deformed at high temperature, and the welding area will have an incomplete welding phenomenon.

[0044] Comparative Example 2: The difference from Example 1 is that in S2, vacuum welding is performed; the vacuum furnace is not preheated to a temperature of 850°C and then cooled to 450°C; instead, the temperature is directly increased at 6°C / min and welding is performed at the temperature of Example 1; Comparative Example 3: The difference from Example 1 is that in S4, the vacuum furnace is not heated to 450°C, but directly heated and welded.

[0045] Comparative Example 4: The difference from Example 1 is that ethanol is used to clean S1, S3 and S4; Comparative Example 5: The difference from Example 1 is that no gaps are left between the components; Example 1 and Comparative Examples 1 to 5 were compared, as shown in Table 1; Table 1 Experimental results of CT metal tube shell welded under different welding methods

[0046] As can be seen from Table 1, by comparing Example 1 with Comparative Example 1, it can be seen that after welding by the method in Example 1, the deformation is very small and can be ignored, while in Comparative Example 1, the deformation caused during the welding process is relatively large. The reason may be that the prior art method does not adopt integrated welding, and the temperature, pressure and other environments of the front and rear welding are different, resulting in deformation of several welds, which makes the finished weldment difficult to use and the finished product efficiency is low; By comparing Example 1 with Comparative Example 2 and Comparative Example 3, it can be found that the vacuum furnace is not preheated in Comparative Example 2, which may cause the furnace temperature to be unstable, and then the internal structure of the tooling to be welded is relatively scattered during the heating process, which may lead to slight deformation; By comparing Example 1 with Comparative Example 4, it can be found that the quality of the welded parts varies with the different cleaning agents, and the cleaning agent in Example 1 of the present invention is more suitable; Comparing Example 1 with Comparative Example 5, the deformation of Example 1 is small. This may be because the tube shell is a thin-walled part. The assembly brazing process of thin-walled parts mainly relies on limiting or positioning tooling to ensure the welding quality. After the product is assembled, it is pushed into the vacuum furnace and is invisible. The reliability of welding can only be ensured by experience and experimental results. Moreover, such thin-walled parts will expand at high temperatures. The thermal deformation coefficient of each part is different. It is necessary to consider different material expansion coefficients to determine the gap after assembly. Example 1 takes this into account, so a suitable gap is retained to ensure that the deformation of the welded parts is low.

Claims

1. A welding assembly of a medical CT metal tube shell, characterized in that: The invention comprises a base (1), a tooling protection side plate (3) fixed on the base (1) and used for limiting the position of the CT metal tube shell (2), and an upper fixing seat (4) and a lower fixing seat (5) fixed on the base (1) and used for assembling the CT metal tube shell (2), wherein the upper fixing seat (4) and the lower fixing seat (5) are clamped together by a clamp, the lower fixing seat (5) is clamped with the base (1), and a beryllium window welding movable pressing block (6) is provided on the upper fixing seat (4).

2. A method for welding a medical CT metal tube shell, based on the welding assembly of the medical CT metal tube shell according to claim 1, characterized in that: The following steps are involved: S1. Assemble the parts to be welded; The components of the CT metal tube shell (2) are cleaned, wherein the components of the CT metal tube shell (2) include a stainless steel ring, a tube shell, a ferrite ring, a grounding block, and a beryllium window; the stainless steel ring is first installed in coordination with a welding assembly for fixing the components, and then the stainless steel ring is installed in coordination with the tube shell, and then the ferrite ring is placed at the port or connection of the tube shell for assembly and installation, and then the beryllium window is placed under the beryllium window welding movable pressing block (6) and fastened and fixed using the welding assembly; and then the heat dissipation strip and the grounding block are assembled to obtain the assembly to be welded; S2, vacuum welding; First, the vacuum furnace is preheated to a temperature of 800-900°C, and then the vacuum furnace is cooled to 400-500°C. The assembly to be welded is then placed in the vacuum furnace, and the pressure in the vacuum furnace is less than or equal to 6.5×10 -3 Pa, and when the temperature is raised to T-20~T-10℃ at a rate of 5~7℃ / min, welding is performed for a welding time of 0.1~5min to obtain a tooling part; wherein T is the melting point of the tube shell; S3, leak detection after furnace exit; After welding is completed, the temperature in the vacuum furnace is lowered to 100-200°C, and then the tooling and each component are taken out and a leak test is performed. If there is a component that fails the leak test, the component that fails the leak test is cleaned and step S2 is repeated until the leak test is passed and the next step is performed; S4, welding window area; First, heat the vacuum furnace to 400-500°C, rotate the tooling by 90°, and weld the window area when the temperature is raised to T-20-T-10°C and the welding time is 0.1-3min. Then, perform a secondary leak test. If there are components that fail the secondary leak test, clean the components that fail the secondary leak test and repeat the welding of the window area until they pass the test.

3. A method for welding a medical CT metal tube shell as claimed in claim 2, characterized in that: The material of the tube shell is oxygen-free copper.

4. A method for welding a medical CT metal tube shell as claimed in claim 2, characterized in that: The welding is performed by vacuum brazing.

5. A method for welding a medical CT metal tube shell as claimed in claim 2, characterized in that: The primary leak detection adopts a soap solution method, and the secondary leak detection adopts an ultrasonic method or a gas detection method.

6. A method for welding a medical CT metal tube shell as claimed in claim 2, characterized in that: The cleaning in step S1 is completed by a first cleaning agent, and the cleaning in S3 and S4 is completed by a second cleaning agent, the first cleaning agent includes alkyl glycoside, ethylene glycol monobutyl ether and glutamic acid tetraacetic acid in a mass ratio of 1:3~5:2, and the second cleaning agent includes citric acid, castor oil derivatives, borates and ethylenediaminetetraacetic acid in a mass ratio of 5~7:5:2~3:

2.

7. A method for welding a medical CT metal tube shell as claimed in claim 6, characterized in that: The preparation method of the second cleaning agent is as follows: first, castor oil derivative is added to citric acid and mixed and stirred for 5 to 8 minutes; the stirring speed is 500 to 600 r / min, and then borate and ethylenediaminetetraacetic acid are added in sequence and stirred for 10 to 20 minutes; a mixture is obtained, and the pH of the mixture is adjusted to 7 using a pH adjuster to obtain the second cleaning agent.

8. A method for welding a medical CT metal tube shell as claimed in claim 2, characterized in that: In S1, gaps are left between the various components of the CT metal bulb tube shell (2), and the gap values ​​of the gaps are determined by the material expansion coefficient and structure of the material.

9. A method for welding a medical CT metal tube shell as claimed in claim 8, characterized in that: The gap value is calculated by the following formula: ； In the formula, is the gap value, is the gap contact surface length, is the average value of the thermal expansion coefficients of the two materials at the gap contact surface, K is the difference between the thermal conductivity of the tube shell and the thermal conductivity of the heat dissipation strip, P is the thermal power of the CT metal bulb when it is working, A is the area of ​​the heat dissipation strip, and t is the total welding time.

10. A method for welding a medical CT metal tube shell as claimed in claim 9, characterized in that: The heat dissipation strip is a wave-shaped heat dissipation strip.

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