Iridium radioactive source shell welding method and welding system

Abstract

The invention relates to an iridium radioactive source shell welding method and system, and belongs to the technical field of welding. The iridium radioactive source shell welding method comprises the following steps that a shell is rotated, and the shell and an end cover are preheated through laser; inputting actual thickness size information of the shell and actual thickness size information of the end cover; the laser adjusts the preset laser power density and defocusing amount according to the actual thickness size information and the standard thickness size information of the shell and the end cover; the automatic rotating mechanism adjusts a preset rotating speed according to the actual thickness size information of the shell and the actual thickness size information of the end cover; the assembled shell and end cover are installed on an automatic rotating mechanism; and the shell and the end cover are welded according to the preset laser power density and defocusing amount, and the automatic rotating mechanism drives the shell and the end cover to rotate according to the preset rotating speed until welding is completed. According to the iridium radioactive source shell welding method provided by the embodiment of the invention, the thickness size of each part of the manufactured iridium radioactive source shell is uniform.

Description

Technical Field

[0001] The present application relates to the field of welding technology, and in particular to a welding method and a welding system for an iridium radiation source housing. Background Art

[0002] Iridium radioactive sources are mainly used in medical and industrial fields. Iridium radioactive sources are mainly composed of iridium sheets and shells. During the production process of iridium radioactive sources, the produced iridium sheets are placed in bars for transportation, and then packaged, measured for activity, placed in shells and welded to form iridium radioactive sources.

[0003] During the use of the iridium radiation source, the irradiated component can receive radiation from the iridium radiation source. The amount of radiation from the iridium radiation source that a local area of ​​the irradiated component can receive is positively correlated with the radiation activity of the local area of ​​the iridium radiation source that it is facing. Therefore, in order to ensure that the radiation effect received by various parts of the irradiated component is the same, the radiation activity emitted by various parts of the iridium radiation source needs to be uniform.

[0004] The outer shell of the iridium radiation source has a blocking effect on the radioactivity of the inner iridium sheet, and this effect is positively correlated with the thickness of the iridium radiation source. The outer shell of the iridium radiation source is welded by a shell and an end cover. In order to ensure that all parts of the outer shell of the iridium radiation source have the same blocking effect on the radioactivity of the inner iridium sheet, the weld between the shell and the end cover needs to have a uniform thickness and the actual thickness size needs to be close to the actual thickness size of the shell and the end cover.

[0005] On the one hand, during the welding process of the shell, the energy output by the laser to the welding area will cause the parts of the shell and the end cover that have not been welded to expand and deform due to heat. The expansion and deformation of the shell and the end cover will cause the gap between the shell and the end cover (i.e., the weld position) to gradually deviate from the landing point of the laser on the shell, which will result in the weld to be welded later being able to receive less energy, and the amount of solid metal converted into molten metal per unit time is less. The thickness of the weld finally formed is reduced, the thickness of the weld between the shell and the end cover is uneven, and the blocking effect on the radioactivity of the iridium sheet is uneven.

[0006] On the other hand, there may be a deviation between the actual thickness of the shell and the end cover used in the processing and the standard thickness; when the actual thickness of the shell and the end cover used in the processing is greater than the standard thickness, the time required for the shell and the end cover to transfer heat is longer, and the amount of the shell and the end cover converted from solid to molten metal per unit time is less, resulting in a shallower depth of the molten pool, and the thickness of the weld finally formed is reduced, resulting in the weld's blocking effect on the radioactivity of the iridium sheet being weaker than other areas, and the connection strength between the shell and the end cover is weaker; When the actual thickness of the shell and the end cover used in the processing process is smaller than the standard thickness, the shell and the end cover transfer heat faster, and continuous heating will cause part of the molten metal on the surface of the molten pool formed at the welding point of the shell and the end cover to vaporize and dissipate, which will lead to a reduction in the thickness of the final weld and depressions on the surface, which ultimately causes the weld to have a weaker blocking effect on the radioactivity of the iridium sheet than other areas, and the unevenness of the weld will affect the radiation direction of the iridium sheet after it passes through this place, affecting the local radiation effect of the iridium radiation source. Summary of the invention

[0007] The purpose of the present application is to provide a method for welding an iridium radiation source shell in order to solve the above problems, so that the thickness of the iridium radiation source shell is uniform at all locations, thereby improving the above problems.

[0008] This application is achieved through the following technical solutions: In a first aspect, the present application provides a method for welding an iridium radiation source housing, the method comprising the following steps: Step S100: rotating the shell and preheating the shell and the end cover by laser; Step S200: inputting the actual thickness dimension information of the shell and the actual thickness dimension information of the end cover; Step S300: the laser adjusts the preset laser power density and defocusing amount according to the actual thickness dimension information of the shell and the actual thickness dimension information of the end cover to control the actual thickness dimension of the weld between the shell and the end cover; Step S400: the automatic rotating mechanism adjusts the preset rotation speed according to the actual thickness dimension information of the shell and the actual thickness dimension information of the end cover to control the welding speed of the weld between the shell and the end cover; Step S500: installing the assembled housing and end cover to the automatic rotation mechanism; Step S600: welding the shell and the end cover according to the preset laser power density and defocusing amount, and the automatic rotating mechanism drives the shell and the end cover to rotate according to the preset rotation speed until the welding is completed.

[0009] In the technical solution of the embodiment of the present application, the shell and the end cover are sent into the hot chamber in batches after the actual thickness size measurement is carried out outside the hot chamber. S100 rotates the shell and preheats the shell and the end cover by laser. During preheating, the defocus of the laser is positive and the power of the laser is about 50% to 70% of the power during welding. The laser focus is located above the surface of the shell and the end cover, so the laser beam has begun to diffuse before reaching the surface of the workpiece, which results in a larger light spot being formed on the surface of the workpiece. The energy distribution in the light spot is relatively uniform, but the overall energy density is lower than that at the focus, so that the shell and the end cover can be evenly heated and not easily melted. The temperature of the shell and the end cover can rise to a temperature close to that during welding, and the shell and the end cover complete expansion during the heating process. The laser can keep facing the weld between the shell and the end cover, so that the energy received by the laser at each weld between the shell and the end cover during the welding process is similar, and the size of each weld between the shell and the end cover is uniform. After S200 obtains the actual thickness dimension information of the shell and the end cover sent into the hot chamber, it determines the actual thickness dimension information of the shell and the end cover to be welded next according to the order of the shell and the end cover put into the hot chamber. The S300 laser adjusts the preset laser power density and defocus amount (generally negative defocus) according to the actual thickness dimension information of the shell and the end cover to be welded next. Focus, if the thickness of the shell and the end cover is less than the standard thickness, the laser power density is reduced to reduce the defocus amount; if the thickness of the shell and the end cover is greater than the standard thickness, the laser power density is increased to increase the defocus amount). The S400 automatic rotation mechanism adjusts the preset speed according to the actual thickness size information of the shell to be welded next and the actual thickness size information of the end cover (if the actual thickness of the shell and the end cover is less than the standard thickness, the speed is increased; if the actual thickness of the shell and the end cover is greater than the standard thickness, the speed is reduced). After the shell is filled with an appropriate amount of iridium sheet, the end cover is assembled to the corresponding shell, and the S500 installs the assembled shell and end cover to the automatic rotation mechanism. The S600 laser adjusts the preset speed according to the actual thickness size information of the shell and the actual thickness size information of the end cover. The shell and the end cover are welded with a preset laser power density and defocus amount, and the automatic rotating mechanism drives the shell and the end cover to rotate according to the preset rotation speed until the welding is completed; the iridium radiation source shell welding method provided by the present application can timely adjust the laser power density and defocus amount of the laser and the rotation speed of the automatic rotating mechanism according to the actual thickness size information of the shell and the end cover of the iridium radiation source to be welded, even when there is a deviation between the actual thickness size of the shell and the end cover and the standard thickness size, the actual thickness size of the weld formed finally can be close to the actual thickness size of the shell and the end cover, so that the thickness of each part of the outer side of the finally formed iridium radiation source is similar, so that the activity of the radiation emitted to the outside by each part of the iridium radiation source is similar; If the thickness of the shell and the end cover to be welded next is less than the standard thickness, the laser power density is reduced to reduce the energy received by the shell and the end cover from the laser per unit time, reduce the risk of the molten metal on the surface of the molten pool vaporizing and escaping due to high temperature, resulting in a reduction in the total amount of molten metal and a too small thickness of the weld, reduce the risk of depressions on the surface of the finally formed iridium radiation source shell affecting the radiation transmission direction of the iridium sheet, reduce the defocus amount, and keep the focal point of the laser in the area directly facing the shell and the end cover, so as to avoid the laser energy from melting and deforming the shell outside the predetermined heat-affected zone, thereby affecting the shielding effect of the corresponding part of the iridium radiation source shell on the radiation of the iridium sheet; If the thickness of the shell and the end cover is greater than the standard thickness, the laser power density is increased to allow the laser energy to be transferred to the predetermined position of the weld more quickly. The solid metal in the heat-affected zone can be converted into molten metal in a timely manner to ensure the depth of the molten pool, so that the thickness of the final weld is sufficient. On the one hand, the risk of uneven thickness of the iridium radiation source at the weld and other parts is reduced, so that the activity of radiation emitted by various parts of the iridium radiation source to the outside world is similar, the defocus amount is increased, the depth of the molten pool is deeper, and the actual thickness of the weld formed can be close to the actual thickness of the shell and end cover to be welded next.

[0010] In the second aspect, the present application provides an iridium radiation source shell welding system, which includes an automatic rotation mechanism, a laser, a receiver and a control module. The automatic rotation mechanism includes a turntable for installing the assembled shell and end cover, and the turntable is used to drive the shell and the end cover to rotate; the laser is used to preheat or weld the shell and the end cover by laser; the receiver is used to receive actual thickness dimension information of the shell and the end cover to be welded; the memory stores the standard thickness dimension of the shell and the end cover; the control module adjusts the rotation speed of the turntable and the laser power density and defocus amount of the laser based on the actual thickness dimension information of the shell and the end cover received by the receiver, as well as the standard thickness dimension of the shell and the end cover, so as to control the actual thickness dimension of the weld between the shell and the end cover; wherein the turntable is provided with a limit portion and a rotating assembly, the limit portion is in close contact with the outer wall of the shell on the side close to the laser landing point, and the rotating assembly drives the shell to rotate relative to the turntable.

[0011] In the technical solution of the embodiment of the present application, the rotating assembly drives the shell to rotate relative to the turntable, and at the same time, the laser preheats the rotating shell and the end cap thereon at a relatively low power and positive defocus state. The expansion deformation of the shell and the end cap starts from the position of the light spot formed by the laser falling on the shell and the end cap. The limiting portion is in close contact with the outer wall of the shell on the side close to the laser landing point, limiting the expansion direction of the shell, and preventing the end cap from expanding outward and pushing the shell toward the outside. The uneven deformation amount leads to uneven movement of the position where the gap between the shell and the end cap is located toward the outside of the shell, reducing the risk of uneven weld size caused by the laser spot not being able to face the weld in the subsequent welding process. The actual thickness dimension information of the shell and the end cap sent into the hot chamber in batches is sent to the receiver, and the control module matches the actual thickness dimension information received by the receiver with the shell and the end cap in sequence, and adjusts the rotation speed of the turntable and the laser power density and defocus of the laser according to the corresponding actual thickness dimension information. The power of the laser increases, and the focal position of the laser drops from the preheating height to the height determined according to the actual size of the shell and the end cap, so that the actual thickness dimension of the weld finally formed can be close to the actual thickness dimension of the shell and the end cap. In addition, the use of laser welding instead of the common argon arc welding in the existing iridium radiation source welding method can, on the one hand, improve the quality of the weld through the characteristics of laser welding (the surface is smoother and the number of pores on the surface and inside is smaller, and the internal material of the weld is tighter), so that the weld can block the radioactivity of the iridium sheet to a degree close to that of other parts of the one-piece molded shell; on the other hand, laser welding can be performed automatically by a machine, and the welding quality of the iridium radiation source shell produced by manual remote-controlled argon arc welding is more stable, the welding speed is faster, and the technical requirements for the staff are lower.

[0012] In some embodiments, the control module controls the actual thickness of the weld between the shell and the end cover by adjusting the rotation speed of the turntable and the laser power density and defocus of the laser. Specifically, when the actual thickness of the weld required is greater than the standard thickness, the control module controls the turntable to slow down the rotation speed, and controls the laser to increase the laser power density and increase the defocus; when the actual thickness of the weld required is less than the standard thickness, the control module controls the turntable to speed up the rotation speed, and controls the laser to reduce the laser power density and reduce the defocus.

[0013] In the technical solution of the embodiment of the present application, when the actual thickness dimension of the required weld is greater than the standard thickness dimension, the control module controls the turntable to slow down the rotation speed, and controls the laser to increase the laser power density and increase the defocus, deepen the molten pool depth, increase the energy output to the welding area, and increase the welding time for the unit area, so that the actual thickness dimension of the weld between the end cover and the shell is greater than the standard thickness dimension and close to the actual thickness dimension of the shell and the end cover; when the actual thickness dimension of the required weld is less than the standard thickness dimension, the control module controls the turntable to speed up the rotation speed, and controls the laser to reduce the laser power density and reduce the defocus, reduce the molten pool depth, reduce the energy output to the welding area, and reduce the welding time for the unit area, so that the actual thickness dimension of the weld between the end cover and the shell is less than the standard thickness dimension and close to the actual thickness dimension of the shell and the end cover, so that the radiation intensity of the final iridium radiation source is uniform everywhere.

[0014] In some embodiments, the surface of the limiting portion in contact with the housing is a curved surface.

[0015] In the technical solution of the embodiment of the present application, the surface where the limiting portion contacts the shell is an arc surface, so that the outer wall surface of the shell that expands after heating can maintain its original curvature when being squeezed by the limiting portion, thereby reducing the deformation of the shell and the end cover caused by welding.

[0016] In some embodiments, the rotating assembly includes a transmission wheel, and an outer circumferential surface of the transmission wheel abuts against an outer circumferential surface of the shell.

[0017] In the technical solution of the embodiment of the present application, the outer circumferential surface of the transmission wheel abuts against the outer circumferential surface of the shell, and the shell is driven to rotate through the rotation of the transmission wheel. The transmission wheel can provide stable friction for the shell, and the rotation effect is stable; during transmission, when the load is too large, slippage may occur between the transmission wheel and the shell, and this slippage can prevent the shell from being damaged due to overload; the transmission wheel can allow shells of different actual sizes to rotate stably.

[0018] In some embodiments, there are multiple transmission wheels, and the multiple transmission wheels are arranged along the outer circumferential surface of the shell. At least one transmission wheel among the multiple transmission wheels is arranged relative to the limiting portion with the shell as the center.

[0019] In the technical solution of the embodiment of the present application, multiple transmission wheels are arranged along the outer circumferential surface of the shell, and the multiple transmission wheels can share the driving force transmitted to the rotation of the shell, so that the shell obtains less force from a single transmission wheel, avoiding excessive force applied to the shell by a single transmission wheel, causing the shell to be squeezed, deformed or scratched. At least one transmission wheel and a limiting portion are arranged relative to each other with the shell as the center. The force applied to the shell by the transmission wheel can push the shell to contact the limiting portion, so that the limiting portion can more easily contact the shell and limit the movement of the weld between the shell and the end cover.

[0020] In the technical solution of the embodiment of the present application, the laser emits laser through the welding gun head to weld the iridium radiation source shell, and the laser generator is arranged outside the hot chamber to avoid the radiation of the iridium sheet from affecting the laser generator of the laser, thereby ensuring the welding effect of the laser and extending the service life of the laser generator.

[0021] In some embodiments, it also includes a base plate and a moving mechanism, the automatic rotation mechanism and the moving mechanism are both arranged on the base plate, the moving mechanism includes a gantry bracket, and the welding gun head is liftably arranged on the gantry bracket.

[0022] In the technical solution of the embodiment of the present application, the automatic rotating mechanism and the moving mechanism are both arranged on the bottom plate, so that the relative position of the automatic rotating mechanism and the moving mechanism can be determined, and the moving mechanism can drive the welding gun head to move to the corresponding position of the turntable of the automatic rotating mechanism in time. The moving mechanism includes a gantry bracket, which reduces the time required for the mutual positioning of the two. The welding gun head can be raised and lowered on the gantry bracket, which is convenient for the welding gun head to weld iridium radiation source shells of different heights, thereby increasing the scope of application of the iridium radiation source shell welding system provided by the present application.

[0023] In some embodiments, the moving mechanism also includes a first guide rail, a first driving member, a second driving member and a third driving member. The first guide rail is arranged on the base plate, and the first guide rail extends along the width direction of the gantry bracket. The gantry bracket is movably arranged on the first guide rail, and the first driving member is used to drive the gantry bracket to move along the first guide rail; the second driving member is arranged on the gantry bracket, and the second driving member is used to drive the welding gun head to move along the length direction of the gantry bracket; the third driving member is arranged at the output end of the second driving member, and the third driving member is used to drive the welding gun head to rise and fall.

[0024] In the technical solution of the embodiment of the present application, the first driving member, the second driving member and the third driving member can drive the welding gun head to move in the horizontal direction and the vertical direction so that it can weld weldments of different thicknesses, sizes and shapes.

[0025] In some embodiments, a scope camera is further included, which is used to collect image information of the welding point between the shell and the end cover and transmit it to a display outside the hot chamber.

[0026] In the technical solution of the embodiment of the present application, the endoscope camera is used to collect image information of the welding point between the shell and the end cover and transmit it to the display outside the hot chamber, so that the staff can observe and discover the internal situation of the hot chamber in time and perform remote intervention.

[0027] In some embodiments, the outside of the scope camera is covered with a lead shell.

[0028] In the technical solution of the embodiment of the present application, the outer side of the endoscope camera is covered with a lead shell, which reduces the impact of the radiation of the iridium sheet on the endoscope camera and extends the service life of the endoscope camera.

[0029] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 A flow chart of a method for welding an iridium radiation source housing provided in some embodiments of the present application; Figure 2 A schematic diagram of the structure of an iridium radiation source housing welding system provided in some embodiments of the present application; Figure 3 A schematic diagram of a structural welding system for an iridium radiation source housing provided in some other embodiments of the present application Figure 4 A front view of an iridium radiation source housing welding system provided for some embodiments of the present application; Figure 5 A side view of an iridium radiation source housing welding system provided for some embodiments of the present application; Figure 6 A schematic diagram of the structure of the limit portion and the housing provided in some embodiments of the present application when they cooperate; Figure 7 A schematic diagram of the structure of a limiter and a rotating assembly provided in some embodiments of the present application; Figure 8 A schematic diagram of the structure of a rotating assembly provided in some embodiments of the present application.

[0032] Icon: 1-housing; 2-laser; 20-welding gun head; 3-automatic rotation mechanism; 30-turntable; 300-limiting part; 301-rotation assembly; 3010-transmission wheel; 4-bottom plate; 5-moving mechanism; 50-gantry bracket; 51-first guide rail; 52-first driving member; 53-second driving member; 54-third driving member. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0034] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as those commonly understood by technicians in the technical field of this application; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned drawings and any variations thereof are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship.

[0035] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0036] The term "multiple" as used in the present application refers to more than two (including two). Similarly, the term "multiple groups" refers to more than two groups (including two groups), and the term "multiple sheets" refers to more than two sheets (including two sheets).

[0037] According to some embodiments of the present application, optionally, Figure 1 As shown, the present application provides a method for welding an iridium radiation source housing, and the method for welding an iridium radiation source housing comprises the following steps: Step S100: rotating the shell 1 and preheating the shell 1 and the end cover by laser; Step S200: inputting the actual thickness dimension information of the shell 1 and the actual thickness dimension information of the end cover; Step S300: the laser 2 adjusts the preset laser power density and defocusing amount according to the actual thickness dimension information of the shell 1 and the actual thickness dimension information of the end cover to control the actual thickness dimension of the weld between the shell 1 and the end cover; Step S400: the automatic rotating mechanism 3 adjusts the preset rotation speed according to the actual thickness dimension information of the shell 1 and the actual thickness dimension information of the end cover to control the welding speed of the weld between the shell 1 and the end cover; Step S500: installing the assembled housing 1 and end cover to the automatic rotating mechanism 3; Step S600: The shell 1 and the end cover are welded according to the preset laser power density and defocus amount, and the automatic rotating mechanism 3 drives the shell 1 and the end cover to rotate according to the preset rotation speed until the welding is completed.

[0038] The outer shell of the iridium radiation source is composed of a shell 1 and an end cover. The shell 1 has an opening for placing the iridium sheet. After the iridium sheet is placed in the shell 1, the end cover is inserted into the opening of the shell 1 to seal the opening, and then the end cover and the shell 1 are welded together by laser welding.

[0039] Laser welding is a precision welding method that uses a high-energy-density laser beam as a heat source. It heats the workpiece surface through laser radiation, and the heat diffuses into the interior through heat conduction, melting the workpiece and forming a specific molten pool. Laser welding has the advantages of fast welding speed, small heat-affected zone, small deformation, high weld quality, and non-contact processing.

[0040] The size information of the shell 1 is obtained by measuring the outer diameter and inner diameter of the opening of the shell 1. Taking the standard thickness size of the iridium radiation source shell mentioned in this application as an example, the inner diameter of the shell 1 is 3.8 mm, the outer diameter is 4.8 mm, the standard thickness size is 1 mm, the outer diameter of the end cap is 3.8 mm, the inner diameter of the end cap is 2.8 mm, and the standard thickness size is 1 mm.

[0041] Laser power density refers to the power of the laser beam projected on a unit area. In laser welding, the power density determines the welding mode and the weld penetration. When the laser energy density is lower than the threshold, welding is carried out in a stable heat conduction manner, and when the energy density exceeds this threshold, a deep fusion weld is formed, and the penetration depth and welding speed increase accordingly. In laser cutting, the power density affects the cutting speed and the cross-section quality. The appropriate power density helps to achieve a more refined and efficient cutting effect. The welding method provided in this application uses a lower laser power density because it takes several milliseconds for the surface temperature to reach the boiling point at low power density. Before the surface vaporizes, the bottom layer reaches the melting point, and it is easy to form a good fusion weld.

[0042] Defocus refers to the distance between the focal point of the laser and the surface of the material being acted on. Positive defocus means that the focal plane is above the workpiece, while negative defocus means that the focal plane is below the workpiece. The choice of defocus is directly related to the power density of the laser acting on the workpiece, which in turn affects the depth of penetration, width of penetration and welding effect. The welding method provided in the present application adopts negative defocus. When the defocus is negative, a greater depth of penetration can be obtained, which is related to the formation process of the molten pool. When the defocus is negative, the power density inside the material is higher than that on the surface, which can easily form a stronger melt and allow light energy to be transmitted deeper into the material.

[0043] The rotation speed of the automatic rotating mechanism 3 is the rotation speed of the housing 1 and the end cover assembled on the automatic rotating mechanism 3. By controlling the rotation speed of the automatic rotating mechanism 3, the contact time of laser welding can be controlled (the faster the rotation speed, the shorter the laser ablation time).

[0044] The shell 1 and the end cover are sent into the hot chamber in batches after the actual thickness dimensions are measured outside the hot chamber. S100 rotates the shell 1 and preheats the shell 1 and the end cover through the laser. During preheating, the laser defocus is positive and the laser power is about 50%~70% of the power during welding. The laser focus is located above the surface of the shell 1 and the end cover, so the laser beam has begun to diffuse before reaching the workpiece surface, which results in a larger light spot on the workpiece surface. The energy distribution in the light spot is relatively uniform, but the overall energy density is lower than that at the focus, so that the shell 1 and the end cover can be heated evenly and are not easily melted. The temperature of the shell 1 and the end cover can rise to a temperature close to that during welding. The shell 1 and the end cover complete expansion and deformation during the heating process, thereby avoiding the shell 1 and the end cover. The weld between the shell 1 and the end cover moves during the welding process, and the laser can keep facing the weld between the shell 1 and the end cover, so that the energy received by the laser at each weld between the shell 1 and the end cover during the welding process is similar, so that the size of each weld between the shell 1 and the end cover is uniform. After S200 obtains the actual thickness size information of the shell 1 and the end cover sent into the hot chamber, the actual thickness size information of the shell 1 and the end cover to be welded next is determined according to the order of the shell 1 and the end cover put into the hot chamber. S300 laser 2 adjusts the preset laser power density and defocus amount (generally negative defocus, if the shell 1 and the end cover are If the actual thickness is smaller than the standard thickness, the laser power density is reduced to reduce the defocus amount; if the actual thickness of the shell 1 and the end cover is larger than the standard thickness, the laser power density is increased to increase the defocus amount). S400 The automatic rotating mechanism 3 adjusts the preset rotation speed according to the actual thickness size information of the shell 1 to be welded next and the actual thickness size information of the end cover (if the actual thickness of the shell 1 and the end cover is smaller than the standard thickness, the rotation speed is increased; if the actual thickness of the shell 1 and the end cover is larger than the standard thickness, the rotation speed is reduced). After a proper amount of iridium sheet is filled into the shell 1, the end cover is assembled to the corresponding shell 1. S500 installs the assembled shell 1 and the end cover to the automatic rotating mechanism 3. S600 The laser 2 adjusts the preset rotation speed according to the actual thickness size information of the shell 1 to be welded next and the actual thickness size information of the end cover. The shell 1 and the end cover are welded with the laser power density and defocus amount set, and the automatic rotating mechanism 3 drives the shell 1 and the end cover to rotate according to the preset speed until the welding is completed; the iridium radiation source shell welding method provided by the present application can timely adjust the laser power density and defocus amount of the laser 2 and the speed of the automatic rotating mechanism 3 according to the actual thickness size information of the shell 1 and the end cover of the iridium radiation source to be welded, even if there is a deviation between the actual thickness size of the shell 1 and the end cover and the standard thickness size, the actual thickness size of the finally formed weld can be close to the actual thickness size of the shell 1 and the end cover, so that the thickness of each part of the outer side of the finally formed iridium radiation source is similar, so that the activity of the radiation emitted to the outside by each part of the iridium radiation source is similar; If the thickness of the shell 1 and the end cover to be welded next is less than the standard thickness, the laser power density is reduced to reduce the energy received by the shell 1 and the end cover from the laser per unit time, reduce the risk that the molten metal on the surface of the molten pool vaporizes and escapes due to high temperature, resulting in a reduction in the total amount of molten metal and an undersized actual thickness of the weld, reduce the risk that the surface of the finally formed iridium radiation source shell will be concave and affect the transmission direction of the radiation of the iridium sheet, reduce the defocus amount, and keep the focal point of the laser in the area directly facing the shell 1 and the end cover, so as to avoid the laser energy from melting and deforming the shell 1 outside the predetermined heat-affected zone, thereby affecting the shielding effect of the corresponding part of the iridium radiation source shell on the radiation of the iridium sheet; If the thickness of the shell 1 and the end cover is greater than the standard thickness, the laser power density is increased to allow the laser energy to be transferred to the predetermined position of the weld more quickly, so that the solid metal in the heat-affected zone can be transformed into molten metal in a timely manner to ensure the depth of the molten pool, so that the thickness of the final weld is sufficient. On the one hand, the risk of uneven thickness of the manufactured iridium radiation source at the weld and other parts is reduced, so that the activity of radiation emitted by various parts of the iridium radiation source to the outside world is similar, the defocus amount is increased, the depth of the molten pool is deeper, and the actual thickness of the formed weld can be close to the actual thickness of the shell 1 and the end cover to be welded next.

[0045] According to some embodiments of the present application, optionally, Figure 2~Figure 8 As shown, the present application provides an iridium radiation source shell welding system, which includes an automatic rotation mechanism 3, a laser 2, a receiver and a control module. The automatic rotation mechanism 3 includes a turntable 30 for installing the assembled shell 1 and the end cover, and the turntable 30 is used to drive the shell 1 and the end cover to rotate; the laser 2 is used to preheat or weld the shell 1 and the end cover by laser; the receiver is used to receive the actual thickness size information of the shell 1 and the end cover to be welded; the memory stores the standard thickness size of the shell 1 and the end cover; the control module adjusts the rotation speed of the turntable 30 and the laser power density and defocusing amount of the laser 2 based on the actual thickness size information of the shell 1 and the end cover received by the receiver, and the standard thickness size of the shell 1 and the end cover, so as to control the actual thickness size of the weld between the shell 1 and the end cover; wherein the turntable 30 is provided with a limiting portion 300 and a rotating assembly 301, the limiting portion 300 is in close contact with the outer wall of the shell 1 on the side close to the laser landing point, and the rotating assembly 301 drives the shell 1 to rotate relative to the turntable 30.

[0046] A socket for placing the assembled housing 1 and end cover is provided in the center of the turntable 30 .

[0047] The rotating assembly 301 drives the shell 1 to rotate relative to the turntable 30, and at the same time, the laser 2 preheats the rotating shell 1 and the end cap thereon at a relatively low power and positive defocus state. The expansion deformation of the shell 1 and the end cap starts from the position of the light spot formed by the laser falling on the shell 1 and the end cap. The limiter 300 is in close contact with the outer wall of the shell 1 on the side close to the laser landing point, limiting the expansion direction of the shell 1, preventing the end cap from expanding outward and pushing the shell 1 to deform outward unevenly, resulting in uneven movement of the position where the gap between the shell 1 and the end cap is located toward the outside of the shell 1, reducing the unevenness of the laser spot in the subsequent welding process. The risk of uneven weld size can be caused by the weld seam. The actual thickness size information of the shell 1 and the end cover sent into the hot chamber in batches is sent to the receiver. The control module matches the actual thickness size information received by the receiver with the shell 1 and the end cover in order, and adjusts the rotation speed of the turntable 30 and the laser power density and defocus of the laser 2 according to the corresponding actual thickness size information. The power of the laser increases, and the focal position of the laser decreases from the preheating height to the height determined according to the actual size of the shell 1 and the end cover, so that the actual thickness size of the weld seam finally formed can be close to the actual thickness size of the shell 1 and the end cover. In addition, the use of laser welding instead of the common argon arc welding in the existing iridium radiation source welding method can improve the quality of the weld seam through the characteristics of laser welding (the surface is smoother and the number of pores on the surface and inside is less, and the internal material of the weld seam is more compact), so that the blocking effect of the weld seam on the radioactivity of the iridium sheet can be close to other parts of the integrally formed shell 1; on the other hand, laser welding can be performed automatically by a machine, and the welding quality of the iridium radiation source shell made by argon arc welding operated by manual remote control is more stable, the welding speed is faster, and the technical requirements for the staff are lower.

[0048] According to some embodiments of the present application, optionally, the control module controls the actual thickness dimension of the weld between the shell 1 and the end cover by adjusting the rotation speed of the turntable 30 and the laser power density and defocus of the laser 2. Specifically, when the actual thickness dimension of the required weld is larger than the standard thickness dimension, the control module controls the turntable 30 to slow down the rotation speed, and controls the laser 2 to increase the laser power density and increase the defocus; when the actual thickness dimension of the required weld is smaller than the standard thickness dimension, the control module controls the turntable 30 to speed up the rotation speed, and controls the laser 2 to reduce the laser power density and reduce the defocus.

[0049] When the actual thickness of the required weld is greater than the standard thickness, the control module controls the turntable 30 to slow down its rotation speed, and controls the laser 2 to increase the laser power density and increase the defocus, deepen the molten pool depth, increase the energy output to the welding area, and increase the welding time for the unit area, so that the actual thickness of the weld between the end cover and the shell 1 is greater than the standard thickness and close to the actual thickness of the shell 1 and the end cover; when the actual thickness of the required weld is less than the standard thickness, the control module controls the turntable 30 to speed up its rotation speed, and controls the laser 2 to reduce the laser power density and reduce the defocus, reduce the molten pool depth, reduce the energy output to the welding area, and reduce the welding time for the unit area, so that the actual thickness of the weld between the end cover and the shell 1 is less than the standard thickness and close to the actual thickness of the shell 1 and the end cover, so that the radiation intensity of each part of the final iridium radiation source is uniform.

[0050] According to some embodiments of the present application, optionally, Figure 6~Figure 7 As shown, the surface where the limiting portion 300 contacts the housing 1 is an arc surface.

[0051] The portion outside the contact area between the limiting portion 300 and the shell 1 may extend in a direction away from the shell 1 , thereby reducing the possible contact area between the limiting portion 300 and the shell 1 and reducing the risk of the limiting portion 300 blocking the shell 1 from rotating.

[0052] The surface of the limiting portion 300 in contact with the shell 1 is an arc surface, so that the outer wall of the shell 1 that expands after heating can maintain its original curvature when being squeezed by the limiting portion 300, thereby reducing the deformation of the shell 1 and the end cover caused by welding.

[0053] According to some embodiments of the present application, optionally, Figure 7~Figure 8 As shown, the rotating assembly 301 includes a transmission wheel 3010 , and the outer circumference of the transmission wheel 3010 abuts against the outer circumference of the housing 1 .

[0054] The outer peripheral surface of the transmission wheel 3010 may be provided with an anti-skid layer. The material of the anti-skid layer may be but is not limited to resin, viscose, rubber, etc. The surface of the transmission wheel 3010 may also be provided with small particles, raised structures, etc. for anti-skid.

[0055] The outer circumferential surface of the transmission wheel 3010 abuts against the outer circumferential surface of the shell 1, and the shell 1 is driven to rotate through the rotation of the transmission wheel 3010. The transmission wheel 3010 can provide a stable friction force for the shell 1, and the rotation effect is stable. During transmission, when the load is too large, slippage may occur between the transmission wheel 3010 and the shell 1. This slippage can prevent the shell 1 from being damaged due to overload. The transmission wheel 3010 can allow shells 1 with different actual sizes to rotate stably.

[0056] According to some embodiments of the present application, optionally, Figure 7~Figure 8 As shown, there are multiple transmission wheels 3010 , and the multiple transmission wheels 3010 are arranged along the outer circumferential surface of the shell 1 . At least one transmission wheel 3010 among the multiple transmission wheels 3010 is arranged opposite to the limiting portion 300 with the shell 1 as the center.

[0057] The number of transmission wheels 3010 can be two, three, four, five, six, seven, eight or more.

[0058] A plurality of transmission wheels 3010 are arranged along the outer circumferential surface of the shell 1. The plurality of transmission wheels 3010 can share the driving force transmitted to the shell 1 for rotation, so that the shell 1 obtains less force from a single transmission wheel 3010, thereby preventing the shell 1 from being squeezed, deformed or scratched due to excessive force applied to the shell 1 by a single transmission wheel 3010. At least one transmission wheel 3010 and the limiting portion 300 are arranged relative to each other with the shell 1 as the center. The force applied to the shell 1 by the transmission wheel 3010 can push the shell 1 to contact the limiting portion 300, so that the limiting portion 300 can more easily contact the shell 1 and limit the movement of the weld between the shell 1 and the end cover.

[0059] According to some embodiments of the present application, optionally, Figure 2~Figure 6 As shown, the laser 2 includes a laser generator and a welding gun head 20. The laser 2 emits laser through the welding gun head 20 to weld the iridium radiation source shell. The laser generator is arranged outside the hot chamber, and the welding gun head 20 and the automatic rotation mechanism 3 are both arranged inside the hot chamber.

[0060] The connecting lines such as the power supply line, control line and optical fiber between the laser generator and the welding gun head 20 all enter the hot chamber through the through-piece.

[0061] A hot cell is a specially designed shielded room for conducting high-radioactivity tests and operations. It is isolated from the surrounding environment to protect the workers and the environment from radioactive contamination. The inner wall of the hot cell is usually covered with stainless steel for easy washing and decontamination, while the outer wall is made of heavy concrete to protect against gamma rays. The interior of the hot cell is equipped with a manipulator and remote operation equipment, and the staff can operate it from the outside by controlling the manipulator and observation window to ensure safety.

[0062] The laser 2 emits laser through the welding gun head 20 to weld the iridium radiation source shell. The laser generator is arranged outside the hot chamber to avoid the radiation of the iridium sheet from affecting the laser generator of the laser 2, thereby ensuring the welding effect of the laser 2 and extending the service life of the laser generator of the laser 2.

[0063] According to some embodiments of the present application, optionally, Figure 2~Figure 5As shown, it also includes a base plate 4 and a moving mechanism 5. The automatic rotating mechanism 3 and the moving mechanism 5 are both arranged on the base plate 4. The moving mechanism 5 includes a gantry bracket 50. The welding gun head 20 is liftably arranged on the gantry bracket 50.

[0064] The base plate 4 can be detachably connected to the ground or the work platform, so as to facilitate the movement of the iridium radiation source housing welding system provided by the present application.

[0065] The automatic rotating mechanism 3 and the moving mechanism 5 are both arranged on the base plate 4, so that the relative position of the automatic rotating mechanism 3 and the moving mechanism 5 can be determined, so that the moving mechanism 5 can drive the welding gun head 20 to move to the corresponding position of the turntable 30 of the automatic rotating mechanism 3 in time. The moving mechanism 5 includes a gantry bracket 50, which reduces the time required for the mutual positioning of the two. The welding gun head 20 can be raised and lowered on the gantry bracket 50, which is convenient for the welding gun head 20 to weld iridium radiation source shells of different heights, thereby increasing the scope of application of the iridium radiation source shell welding system provided in the present application.

[0066] According to some embodiments of the present application, optionally, Figure 2~Figure 5 As shown, the moving mechanism 5 also includes a first guide rail 51, a first driving member 52, a second driving member 53, and a third driving member 54. The first guide rail 51 is arranged on the base plate 4, and the first guide rail 51 extends along the width direction of the gantry bracket 50. The gantry bracket 50 is movably arranged on the first guide rail 51. The first driving member 52 is used to drive the gantry bracket 50 to move along the first guide rail 51; the second driving member 53 is arranged on the gantry bracket 50, and the second driving member 53 is used to drive the welding gun head 20 to move along the length direction of the gantry bracket 50; the third driving member 54 is arranged at the output end of the second driving member 53, and the third driving member 54 is used to drive the welding gun head 20 to rise and fall.

[0067] The first driving member 52 , the second driving member 53 and the third driving member 54 can drive the welding gun head 20 to move in the horizontal direction and the vertical direction so that it can weld weldments with different thicknesses, sizes and shapes.

[0068] According to some embodiments of the present application, optionally, the output ends of the first driving member 52, the second driving member 53 and the third driving member 54 are all quick-connect plugs, and are all provided with positioning pins.

[0069] The first driving member 52, the second driving member 53 and the third driving member 54 can be connected to the input end of the reducer through a quick-plugging open-flap slot.

[0070] The radiation intensity in the hot chamber is relatively strong. The output ends of the first drive member 52, the second drive member 53 and the third drive member 54 are all quick-plug plugs, and are all provided with positioning pins, which can be quickly plugged in and out without using fasteners, so that the first drive member 52, the second drive member 53 and the third drive member 54 can be quickly disassembled and assembled with other components, reducing the operating time of the operator in the hot chamber when the operator replaces the first drive member 52, the second drive member 53 and the third drive member 54, thereby reducing the risk of radiation damage to the operator.

[0071] According to some embodiments of the present application, optionally, the output ends of the first driving member 52 , the second driving member 53 , and the third driving member 54 are all radiation-resistant motors.

[0072] Radiation-resistant motors are motors designed specifically for working in high-radiation environments. They can maintain stable operation in extreme environments such as nuclear power plants, space exploration, and medical radiotherapy equipment.

[0073] The output ends of the first drive member 52 , the second drive member 53 and the third drive member 54 are all radiation-resistant motors, so that the first drive member 52 , the second drive member 53 and the third drive member 54 can work under the radiation of the iridium sheet without being easily damaged, thereby extending the service life of the first drive member 52 , the second drive member 53 and the third drive member 54 .

[0074] According to some embodiments of the present application, optionally, a peephole camera is further included, which is used to collect image information of the welding point between the shell 1 and the end cover and transmit it to a display outside the hot chamber.

[0075] The peephole camera can be held by a robotic arm and moved within the hot chamber.

[0076] The endoscope camera is used to collect image information of the welding point between the shell 1 and the end cover and transmit it to the display outside the hot chamber, so that the staff can observe and find out the internal situation of the hot chamber in time and conduct remote intervention.

[0077] According to some embodiments of the present application, optionally, the outer side of the endoscope camera is covered with a lead shell.

[0078] Lead is a commonly used radiation protection material, and its main function is to absorb and attenuate radiation, especially X-rays and gamma rays, through its high density and atomic number.

[0079] The outer side of the endoscope camera is covered with a lead shell, which reduces the impact of the radiation of the iridium sheet on the endoscope camera and extends the service life of the endoscope camera.

[0080] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present application. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An iridium radiation source housing welding system, characterized in that: include: An automatic rotating mechanism, comprising a turntable for mounting the assembled housing and end cover, the turntable being used to drive the housing and the end cover to rotate; A laser, used for preheating or welding the shell and the end cover by laser; A receiver, used to receive actual thickness dimension information of the shell and the end cover to be welded; A memory storing standard thickness dimensions of the shell and the end cover; a control module, based on the actual thickness dimension information of the shell and the end cover received by the receiver and the standard thickness dimensions of the shell and the end cover, adjusting the rotation speed of the turntable and the laser power density and defocusing amount of the laser to control the actual thickness dimension of the weld between the shell and the end cover; The turntable is provided with a limit portion and a rotating assembly, the limit portion is in close contact with the outer wall of the shell on a side close to the laser landing point, and the rotating assembly drives the shell to rotate relative to the turntable.

2. The iridium radiation source housing welding system according to claim 1, characterized in that: The control module controls the actual thickness of the weld between the shell and the end cover by adjusting the rotation speed of the turntable and the laser power density and defocus of the laser: When the actual thickness of the weld required is greater than the standard thickness, the control module controls the turntable to slow down the rotation speed, and controls the laser to increase the laser power density and the defocus amount; When the actual thickness of the weld required is smaller than the standard thickness, the control module controls the turntable to increase the rotation speed, and controls the laser to reduce the laser power density and the defocus amount.

3. The iridium radiation source housing welding system according to claim 1, characterized in that: The surface of the limiting portion in contact with the housing is an arc surface.

4. The iridium radiation source housing welding system according to claim 1, characterized in that: The rotating assembly includes a transmission wheel, and the outer peripheral surface of the transmission wheel abuts against the outer peripheral surface of the shell.

5. The iridium radiation source housing welding system according to claim 4, characterized in that: There are multiple transmission wheels, and the multiple transmission wheels are arranged along the outer peripheral surface of the shell. At least one of the multiple transmission wheels is arranged opposite to the limiting part with the shell as the center.

6. The iridium radiation source housing welding system according to claim 1, characterized in that: It also includes a base plate and a moving mechanism. The automatic rotating mechanism and the moving mechanism are both arranged on the base plate. The moving mechanism includes a gantry bracket. The welding gun head is liftably arranged on the gantry bracket.

7. The iridium radiation source housing welding system according to claim 6, characterized in that: The moving mechanism further includes a first guide rail, a first driving member, a second driving member and a third driving member, wherein the first guide rail is arranged on the bottom plate, the first guide rail extends along the width direction of the gantry bracket, the gantry bracket is movably arranged on the first guide rail, and the first driving member is used to drive the gantry bracket to move along the first guide rail; The second driving member is disposed on the gantry bracket, and the second driving member is used to drive the welding gun head to move along the length direction of the gantry bracket; The third driving member is arranged at the output end of the second driving member, and the third driving member is used to drive the welding gun head to rise and fall.

8. The iridium radiation source housing welding system according to claim 1, characterized in that: It also includes a endoscope camera, which is used to collect image information of the welding point between the shell and the end cover and transmit it to a display outside the hot chamber.

9. The iridium radiation source housing welding system according to claim 8, characterized in that: The outer side of the scope camera is covered with a lead shell.

10. A method for welding an iridium radiation source housing, characterized in that: include: Step S100: rotating the shell and preheating the shell and the end cover by laser; Step S200: inputting the actual thickness dimension information of the shell and the actual thickness dimension information of the end cover; Step S300: the laser adjusts the preset laser power density and defocusing amount according to the actual thickness dimension information of the shell and the actual thickness dimension information of the end cover to control the actual thickness dimension of the weld between the shell and the end cover; Step S400: the automatic rotating mechanism adjusts a preset rotation speed according to the actual thickness dimension information of the shell and the actual thickness dimension information of the end cover to control the welding speed of the weld between the shell and the end cover; Step S5 00: Installing the assembled housing and the end cover to the automatic rotation mechanism; Step S600: welding the shell and the end cover according to a preset laser power density and defocusing amount, and the automatic rotating mechanism drives the shell and the end cover to rotate according to a preset rotation speed until the welding is completed.

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