An electron beam welding encapsulation method for a closed structure workpiece

Abstract

The present application relates to the field of electron beam welding packaging method of closed structure workpiece, and particularly relates to an electron beam welding packaging method of closed structure workpiece, which comprises the following steps: through welding preparation, a workpiece with completed opening and a preheated brass bottom plate are obtained, wherein the workpiece is an oxygen-free copper closed structure workpiece; the workpiece is placed on the brass bottom plate and quickly put into a vacuum chamber for vacuumizing; the workpiece is subjected to vacuum preheating treatment; the workpiece after vacuum preheating is subjected to electron beam welding; after the workpiece after electron beam welding is kept in the vacuum chamber for a preset time, air is filled, then the workpiece is taken out and the weld is checked. Through the welding preparation, vacuum pre-treatment, electron beam welding and heat preservation treatment, the welding treatment of the closed structure workpiece is realized, the quality of the weld is good, the mechanical properties are excellent and the appearance is beautiful.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electron beam welding, in particular to an electron beam welding packaging method for a closed structure workpiece. BACKGROUND

[0002] As a representative of the "new generation" developed in the new century, electron beam welding technology has developed rapidly in various fields.

[0003] Because it has incomparable conditions such as high energy density, small heating area, deep penetration, fast welding speed, narrow heat-affected zone, small workpiece deformation, high welding strength, easy precision control of welding parameters, and no environmental pollution of the weld under high vacuum conditions, it is widely used in the fields of aviation, aerospace, military industry, and automobile industry.

[0004] However, it is also because electron beam welding requires high vacuum conditions that electron beam welding of closed structure workpieces becomes a problem. The gas inside the closed structure needs to be removed and exhausted during the welding process, and the quality of the weld after welding needs to be good, the mechanical properties need to be excellent, and the appearance needs to be beautiful. SUMMARY

[0005] Therefore, it is necessary to provide an electron beam welding packaging method for a closed structure workpiece to provide a new method to realize electron beam welding processing of a closed structure workpiece, which has good weld quality, excellent mechanical properties, and a beautiful appearance.

[0006] The present application provides an electron beam welding packaging method for a closed structure workpiece, which comprises:

[0007] Through pre-welding preparation, a workpiece with completed holes and a preheated brass bottom plate are obtained, wherein the workpiece is an oxygen-free copper closed structure workpiece;

[0008] The workpiece is placed on the brass bottom plate and quickly placed in a vacuum chamber for vacuumizing;

[0009] The workpiece is subjected to vacuum preheating treatment;

[0010] The weld of the workpiece after vacuum preheating is subjected to electron beam welding;

[0011] After the workpiece after electron beam welding is kept in the vacuum chamber for a preset time, it is filled with gas, and then the workpiece is taken out and the weld is checked.

[0012] In some embodiments, the pre-welding preparation comprises:

[0013] Cleaning the heat-affected zone of the workpiece;

[0014] Holes are opened on the workpiece to make the internal space of the workpiece communicate with the external space;

[0015] placing the brass base plate into a high temperature box and heating to a first preset temperature.

[0016] In some embodiments, the cleaning of the heat affected zone of the workpiece comprises:

[0017] scraping the locations within a 25mm range of the heat affected zone of the workpiece to remove the attached oxides and color spots, the 25mm range of the heat affected zone being the locations within a 25mm range around the weld.

[0018] In some embodiments, the drilling holes on the workpiece to communicate the internal space of the workpiece with the external space comprises:

[0019] twelve holes are drilled on the workpiece, the twelve holes being arranged in a uniform spaced array along the circumferential direction of the workpiece, the specification of the holes being 0.2mm x 0.5mm, and the depth penetrating the internal space of the workpiece.

[0020] In some embodiments, the placing the brass base plate into a high temperature box and heating to a first preset temperature comprises:

[0021] selecting a brass plate with a specification of 5mm x 400mm x 600mm;

[0022] placing the brass plate into a high temperature box and heating to about 300 degrees.

[0023] In some embodiments, the placing the workpiece on the brass base plate and quickly placing into a vacuum chamber to evacuate comprises:

[0024] placing the workpiece on the brass base plate;

[0025] fixing the workpiece on a stainless steel platform in the vacuum chamber with a non-magnetic clamp;

[0026] quickly closing the hatch of the vacuum chamber and evacuating, the whole transfer process being completed within 2min, wherein the temperature of the brass base plate is maintained between 100 degrees and 240 degrees after closing the hatch, and the vacuum degree of the vacuum chamber reaches a high vacuum state between 5x10-3Pa and 5x10-2Pa.

[0027] In some embodiments, the vacuum preheating treatment of the workpiece comprises:

[0028] the vacuum bulk preheating of the workpiece, which refers to the bulk defocus preheating within a 120mm circular area extending outward from the welding area of the workpiece using an electron beam device;

[0029] The workpiece is subjected to vacuum local preheating, which refers to local focused preheating using an electron beam device in a circular area with an extension of 1mm based on the welding area of the workpiece.

[0030] In some embodiments, during the vacuum overall preheating process, the current of the electron beam device is set to 40±2mA, the travel speed is 800mm / min, the voltage is set to 60KV, and the preheating time is 15-20 minutes; and / or, during the vacuum local preheating process, the current of the electron beam device is set to 45±2mA, the travel speed is 700mm / min, the voltage is set to 60KV, and the preheating time is 25-30 minutes.

[0031] In some embodiments, the workpiece includes a circularly slotted cavity and a cylindrical end cover, the end cover is placed into the circularly slotted cavity, the end cover is provided with holes in the circumferential direction, the end cover is assembled with the circularly slotted cavity, the fitting surface of the end cover and the cavity are provided with welds to be welded at the holes, the welds to be welded of the workpiece include fitting surface welds and hole welds, the hole welds are formed through the holes, wherein the electron beam welding of the welds of the workpiece after vacuum preheating includes:

[0032] The fitting surface welds are spot welded by the electron beam device, and the twelve holes are avoided during the spot welding;

[0033] The hole welds are sealed by the electron beam device;

[0034] The fitting surface welds are sealed by the electron beam device.

[0035] In some embodiments, during the hole sealing process, the focal point of the electron beam device uses 1860±40mA, the voltage is set to 60KV, the current is set to 20±2mA, the speed is set to 1000mm / min, the amplitude is 1.0, and the frequency is 50Hz;

[0036] During the fitting surface sealing process, the focal point of the electron beam device uses 1860±40mA, the voltage is set to 60KV, the current is set to 45±2mA, the speed is set to 1200mm / min, the amplitude is 1.0, and the frequency is 50Hz.

[0037] The beneficial effects of the present application are:

[0038] The present application obtains the workpiece with completed opening and the preheated brass bottom plate through the pre-welding preparation; then, the workpiece is placed on the brass bottom plate and quickly put into the vacuum chamber to extract vacuum; then, the workpiece is subjected to vacuum preheating treatment; then, the weld of the workpiece after vacuum preheating is subjected to electron beam welding; finally, the workpiece after electron beam welding is subjected to heat preservation in the vacuum chamber for a preset time, then, the workpiece is taken out and the weld is checked. Through the pre-welding preparation, rapid pre-treatment, electron beam welding and heat preservation treatment, the welding treatment of the workpiece with closed structure is realized, the quality of the weld is good, the mechanical properties are excellent and the appearance is beautiful. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only an embodiment of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0040] Figure 1 The flowchart of the electron beam welding packaging method of the workpiece with closed structure provided for the embodiment of the present application;

[0041] Figure 2 The perspective schematic diagram of the electron beam welding equipment provided for the embodiment of the present application;

[0042] Figure 3 The cross-sectional perspective schematic diagram of the workpiece provided for the embodiment of the present application. DETAILED DESCRIPTION

[0043] In order to make the above-mentioned objects, features and advantages of the present application more apparent and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the drawings. In the following description, many specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the scope of the present application, so the present application is not limited to the specific embodiments disclosed below.

[0044] In the description of the application, it should be understood that the orientation or positional relationship indicated by terms such as "central", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the purpose of facilitating the description of the application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application.

[0045] In addition, the terms "first", "second", "third", etc. are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second", etc. can explicitly or implicitly include at least one of the features. In the description of the application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.

[0046] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0047] In the present application, unless otherwise explicitly specified and limited, the feature "on" or "under" the second feature can be in direct contact with the second feature, or indirectly in contact with the second feature through an intermediate medium. Moreover, the feature "on", "above" and "on" the second feature can be the feature directly above or obliquely above the second feature, or only indicate that the feature is higher than the second feature in horizontal height. The feature "under", "below" and "below" the second feature can be the feature directly below or obliquely below the second feature, or only indicate that the feature is lower than the second feature in horizontal height.

[0048] It should be noted that when an element is referred to as "fixed to" or "provided on" another element, it can be directly on the other element or there can be a middle element. When an element is considered to be "connected" to another element, it can be directly connected to another element or there can be a middle element. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are only for the purpose of illustration and do not represent the only implementation.

[0049] Since electron beam welding requires high vacuum conditions, it is difficult to electron beam weld workpieces with closed structures, and the gas inside the closed structure needs to be removed and exhausted during the welding process, and the quality of the weld is good, the mechanical properties are excellent, and the appearance is beautiful after welding.

[0050] To solve the existing problems, the embodiments of the present application provide an electron beam welding packaging method for workpieces with closed structures, which can realize electron beam welding processing of workpieces with closed structures, and the quality of the weld is good, the mechanical properties are excellent, and the appearance is beautiful. Figures 1-3 The embodiments of the present application provide an electron beam welding packaging method for workpieces with closed structures, which includes:

[0051] Step 1, through pre-welding preparation, a workpiece with completed openings and a preheated brass bottom plate are obtained, wherein the workpiece is an oxygen-free copper workpiece with a closed structure;

[0052] Step 2, the workpiece is placed on the brass bottom plate and quickly placed in a vacuum chamber for vacuumizing;

[0053] Step 3, the workpiece is subjected to vacuum preheating treatment;

[0054] Step 4, the weld of the workpiece after vacuum preheating is subjected to electron beam welding;

[0055] Step 5, after the workpiece after electron beam welding is kept in the vacuum chamber for a preset time, it is filled with gas, and then the workpiece is taken out and the weld is checked.

[0056] Through pre-welding preparation, a workpiece with completed openings is obtained, thereby ensuring the internal and external communication of the workpiece, which can not only make the internal of the workpiece vacuumized, but also improve the welding quality; the preheated brass bottom plate provides a higher temperature bottom support to hold the workpiece, which can keep the temperature of the workpiece high, which is beneficial to subsequent welding; the fast pre-treatment further heats the workpiece to avoid low temperature affecting the welding quality; the electron beam welding has high energy density, small heating area, deep penetration, fast welding speed, narrow heat-affected zone, small workpiece deformation, high welding strength, and easy precision control of welding parameters, which is beneficial to high-quality welding; finally, the heat preservation treatment realizes stable cooling, which is beneficial to avoid uneven stress caused by rapid cooling, resulting in poor welding and other problems, and realizes the welding processing of workpieces with closed structures, which has good weld quality, excellent mechanical properties, and beautiful appearance.

[0057] In some embodiments, the pre-welding preparation includes:

[0058] Step 1.1, cleaning the heat-affected zone of the workpiece;

[0059] Step 1.2, drilling holes on the workpiece to make the internal space of the workpiece communicate with the external space;

[0060] Step 1.3, placing the brass base plate into the high-temperature box and heating it to a first preset temperature.

[0061] Cleaning the heat-affected zone of the workpiece can keep it clean, which is conducive to improving the welding quality; drilling holes to make the internal space of the workpiece communicate with the external space facilitates subsequent vacuum welding processing; the heated brass base plate can support the workpiece and preliminarily heat the workpiece to improve the temperature, which is conducive to subsequent electron beam welding.

[0062] In some embodiments, the step 1.1 of cleaning the heat-affected zone of the workpiece includes scraping the positions within a 25mm range of the heat-affected zone of the workpiece to remove attached oxides and color spots, the 25mm range of the heat-affected zone being the positions within a 25mm range around the weld, which realizes efficient and accurate cleaning and ensures that the heat-affected zone is in a good state for welding.

[0063] In some embodiments, the step 1.2 of drilling holes on the workpiece to make the internal space of the workpiece communicate with the external space includes drilling twelve holes on the workpiece, the twelve holes being arranged in a uniform spaced array along the circumferential direction of the workpiece, the holes having a specification of 0.2mm×0.5mm and a depth penetrating the internal space of the workpiece. The uniform spaced array facilitates uniform communication between the internal and external spaces of the workpiece from all directions, and the uniform arrangement makes the deformation and stress diffusion of the workpiece after heating more uniform, which is conducive to improving the welding quality.

[0064] Specifically, the workpiece includes a cavity with an open circular groove and an end cover in the shape of a cylinder, the end cover is placed into the cavity with the open circular groove, the end cover is drilled in the circumferential direction, the end cover is assembled with the cavity with the open circular groove, and there are welds to be welded at the matching surfaces of the holes and the cavity. The welds to be welded of the workpiece include matching surface welds and hole mouth welds.

[0065] Further, referring to Figure 2 and Figure 3 , Figure 2 is a schematic diagram of an electron beam welding device; Figure 3 is a cross-sectional schematic diagram of a workpiece. In the figure, it is represented as a vacuum chamber 100, an H62 copper plate 200, a workpiece including a cavity with an open circular groove 310 and an end cover in the shape of a cylinder 320, the workpiece having holes 340 and matching surfaces 330.

[0066] In some embodiments, the step 1.3 of placing the brass base plate into the high-temperature box and heating it to a first preset temperature includes:

[0067] Step 1.31, select a piece of brass plate with a size of 5mm x 400mm x 600mm;

[0068] Step 1.32, put the brass plate into the high temperature box and heat it to about 300 degrees.

[0069] Specifically, the grade of the brass plate can be selected as H62, and heating to about 300 degrees ensures that it can maintain a relatively high temperature and preheat the supported workpiece while maintaining a high temperature itself.

[0070] In some embodiments, the step 2, placing the workpiece on the brass base plate and quickly placing it in the vacuum chamber to vacuum, includes:

[0071] Step 2.1, place the workpiece on the brass base plate;

[0072] Step 2.2, fix the workpiece on the stainless steel platform in the vacuum chamber with a non-magnetic clamp;

[0073] Step 2.3, quickly close the hatch of the vacuum chamber and vacuum, the entire transfer process is completed within 2 minutes, wherein the temperature of the brass base plate needs to be maintained between 100 degrees and 240 degrees after closing the hatch, and the vacuum degree of the vacuum chamber reaches a high vacuum state between 5x10-3Pa and 5x10-2Pa.

[0074] In the above steps, the hatch of the vacuum chamber is closed as quickly as possible and vacuumed, and the entire transfer process is completed within 2 minutes; this can avoid problems such as heat dissipation and oxidation of the workpiece exposed to the external air for a long time, thereby ensuring higher welding quality in the subsequent process.

[0075] In some embodiments, the step 3, vacuum preheating treatment of the workpiece, includes:

[0076] Step 3.1, vacuum bulk preheating of the workpiece, which means that based on the welding area of the workpiece, a circular area with an extension of 120mm is used for bulk defocusing preheating by an electron beam device;

[0077] Step 3.2, vacuum local preheating of the workpiece, which means that based on the welding area of the workpiece, a circular area with an extension of 1mm is used for local focusing preheating by an electron beam device.

[0078] The workpiece is first subjected to vacuum bulk preheating to preliminarily reach a relatively high temperature in the welding area, and then subjected to vacuum local preheating for focused preheating of more local positions; this can ensure a higher temperature, which is conducive to the rapid formation of a uniform molten pool during electron beam welding, reduces the generation of stress unevenness and other problems, and further improves the quality of electron beam welding.

[0079] In some embodiments, preferably, during the vacuum bulk preheating process of step 3.1, the current of the electron beam device is set to 40±2mA, the travel speed is 800mm / min, the voltage is set to 60KV, and the preheating time is 15-20 minutes. Similarly, preferably, during the vacuum local preheating process of step 3.2, the current of the electron beam device is set to 45±2mA, the travel speed is 700mm / min, the voltage is set to 60KV, and the preheating time is 25-30 minutes. The combination of the fast and short bulk preheating and the relatively slow and long local preheating can make the workpiece reach a more favorable state in its temperature distribution before electron beam welding, and the reasonable design of the preheating time can optimize the time of the entire welding process.

[0080] In some embodiments, the welds to be welded of the workpiece include the mating surface welds and the orifice welds, and the step 4 of electron beam welding the welds of the vacuum preheated workpiece includes:

[0081] Step 4.1, using the electron beam device to spot weld the mating surface welds, and avoiding the twelve openings during the spot welding process;

[0082] Step 4.2, using the electron beam device to seal weld the orifice welds;

[0083] Step 4.3, using the electron beam device to seal weld the mating surface welds.

[0084] The above steps first form a preliminary position fixation by spot welding the mating surface, and then perform orifice sealing and mating surface sealing, and finally complete the electron beam welding.

[0085] In some embodiments, preferably, during the orifice sealing process of step 4.2, the focal point of the electron beam device uses 1860±40mA, the voltage is set to 60KV, the current is set to 20±2mA, the speed is set to 1000mm / min, the amplitude is 1.0, and the frequency is 50Hz; in some embodiments, preferably, during the mating surface sealing process of step 4.3, the focal point of the electron beam device uses 1860±40mA, the voltage is set to 60KV, the current is set to 45±2mA, the speed is set to 1200mm / min, the amplitude is 1.0, and the frequency is 50Hz. By accurately controlling the parameters during the electron beam welding process, the welding quality can be effectively guaranteed, and the formed welds have good quality, excellent mechanical properties, and an attractive appearance.

[0086] In addition, in step 5, after the workpiece after electron beam welding is kept in the vacuum chamber for a predetermined time, it is inflated, and then the workpiece is taken out and the welds are inspected, and the keeping time in the vacuum chamber is preferably 40-45 minutes.

[0087] In some embodiments, the inspection of the welding bead can be verified by a test, which can specifically include a mechanical test and a CT detection.

[0088] Specifically, in the mechanical test, the workpiece after the vacuum chamber is welded is cut into a test piece, which is placed on a tensile testing machine for mechanical property detection. The tensile strength of the test piece is more than 80% of the lower limit value of the tensile strength of the base material. In the CT detection, the internal weld is mainly detected for defects such as cracks, weld bumps, pores, and slag, which meets the quality standard requirements of GJB 5312.

[0089] Finally, it should be noted that the technical features of the above embodiments can be combined arbitrarily. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the description.

[0090] The above-described embodiments only express one of the embodiments of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the scope of protection of the present application should be subject to the appended claims.

Claims

1. An electron beam welding encapsulation method of a closed structure workpiece, characterized by, The method comprises the following steps: obtaining a completed workpiece and a preheated brass base plate through pre-weld preparation, wherein the workpiece is an oxygen-free copper closed structure workpiece, and the workpiece is drilled to communicate the internal space of the workpiece with the external space; placing the workpiece on the brass base plate and quickly placing it in a vacuum chamber to perform vacuumization; performing vacuum preheating treatment on the workpiece; performing electron beam welding on the weld of the workpiece after vacuum preheating; after the workpiece after electron beam welding is kept in the vacuum chamber for a preset time, air is filled, and then the workpiece is taken out and the weld is checked; the vacuum preheating treatment on the workpiece comprises: performing vacuum whole-body preheating on the workpiece, wherein the vacuum whole-body preheating refers to using an electron beam device to perform whole-body defocusing preheating in a circular area with an extension of 120 mm based on the welding area of the workpiece; performing vacuum local preheating on the workpiece, wherein the vacuum local preheating refers to using an electron beam device to perform local focusing preheating in a circular area with an extension of 1 mm based on the welding area of the workpiece; in the vacuum whole-body preheating process, the current of the electron beam device is set to 40±2 mA, the travel speed is 800 mm / min, the voltage is set to 60 KV, and the preheating time is 15-20 minutes; and / or in the vacuum local preheating process, the current of the electron beam device is set to 45±2 mA, the travel speed is 700 mm / min, the voltage is set to 60 KV, and the preheating time is 25-30 minutes; the workpiece comprises a cavity with a circular groove and a cylindrical end cover, the end cover is placed in the cavity with a circular groove, the end cover is drilled in the circumferential direction, the end cover is assembled with the cavity with a circular groove, and there are welds to be welded on the matching surfaces of the cavity with a circular groove and the openings, the welds to be welded on the workpiece comprise matching surface welds and opening welds, and the opening welds are formed by drilling, wherein the electron beam welding on the welds of the workpiece after vacuum preheating comprises: point welding the matching surface welds by using an electron beam device, and avoiding the twelve openings during the point welding; sealing the opening welds by using an electron beam device; sealing the matching surface welds by using an electron beam device; in the opening sealing process, the focal point of the electron beam device uses 1860±40 mA, the voltage is set to 60 KV, the current is set to 20±2 mA, the speed is set to 1000 mm / min, the amplitude is 1.0, and the frequency is 50 Hz; in the matching surface sealing process, the focal point of the electron beam device uses 1860±40 mA, the voltage is set to 60 KV, the current is set to 45±2 mA, the speed is set to 1200 mm / min, the amplitude is 1.0, and the frequency is 50 Hz.

2. The method of claim 1, wherein the method further comprises: the pre-weld preparation comprises: cleaning the heat-affected zone of the workpiece; placing the brass base plate in a high-temperature box to heat it to a first preset temperature.

3. The method of claim 2, wherein the method further comprises: the cleaning of the heat-affected zone of the workpiece comprises: performing scraping treatment on the positions within a 25 mm range of the heat-affected zone of the workpiece to remove the attached oxides and color spots, and the 25 mm range of the heat-affected zone refers to the positions within a 25 mm range around the weld.

4. The method of claim 2, wherein the method further comprises: The hole drilling on the workpiece to make the internal space of the workpiece communicate with the external space comprises: The twelve holes are arranged in a uniform interval array along the circumferential direction of the workpiece, and the size of the holes is 0.2mm*0.5mm, and the depth penetrates the internal space of the workpiece.

5. The method of claim 2, wherein the method further comprises: The heating of the brass bottom plate in the high-temperature box to the first preset temperature comprises: Select a brass plate with a size of 5mm*400mm*600mm; The brass plate is heated to about 300 degrees in the high-temperature box.

6. The method of claim 1, wherein The workpiece is placed on the brass bottom plate and quickly put into the vacuum chamber to vacuumize, comprising: The workpiece is placed on the brass bottom plate; The workpiece is fixed on the stainless steel platform in the vacuum chamber by using a non-magnetic clamp; The hatch of the vacuum chamber is quickly closed and vacuumized, and the whole transfer process is completed within 2 minutes, wherein the temperature of the brass bottom plate needs to be maintained between 100 degrees and 240 degrees after the hatch is closed, and the vacuum degree of the vacuum chamber reaches a high vacuum state between 5*10-3Pa and 5*10-2Pa.

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