Sealing method and crimping device for high-vacuum sealing sheath

Abstract

The invention belongs to the technical field of material processing and powder metallurgy, and discloses a sealing method and a crimping device for a high-vacuum sealing sheath. The method comprises the following steps: providing a to-be-sealed sheath, wherein the sheath is provided with an exhaust pipe; the sheath is vacuumized, so that the interior of the sheath reaches a high-vacuum state; a crimping device is provided, the crimping device comprises a primary block and a secondary block which can move relatively, and the opposite surfaces of the primary block and the secondary block are provided with corrugated tooth-shaped structures which are matched with each other; the exhaust pipe is arranged between the mother block and the son block, the mother block and the son block are driven by hydraulic power to move relatively, the exhaust pipe is subjected to cold pressing, the exhaust pipe is subjected to plastic deformation and meshed under the action of the corrugated tooth-shaped structure, and therefore sealing is achieved. According to the invention, through the specially designed corrugated tooth-shaped jaw, a compact non-porous mechanical sealing joint surface can be formed. And a multi-stage pressing process is combined, so that the internal channel of the exhaust pipe is ensured to be completely and firmly sealed.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of material processing and powder metallurgy, in particular to a sealing method of high-vacuum sealing sleeve and a crimping device. BACKGROUND

[0002] Hot isostatic pressing technology is a key process in the field of material processing and powder metallurgy, which uses inert gas as a pressure transmission medium to densify powders or near-net-shaped parts packaged in a sleeve under high temperature and pressure. Before the implementation of this process, the sleeve containing the material and having been pumped to high vacuum must be reliably sealed to maintain its internal vacuum for a long time, isolate the external environment, and ensure product quality.

[0003] Currently, the sealing of the sleeve's evacuation pipe mainly relies on traditional welding methods such as argon arc welding or high-temperature fusion welding. However, these methods have several inherent and difficult-to-overcome defects: (1) significant heat-affected zone, damaging product quality: the high temperature generated during welding can form a wide heat-affected zone, and heat can easily be transmitted to the inside of the sleeve. This can cause the internal wall of the sleeve to oxidize, or cause the internal powder material to undergo pre-sintering, composition segregation, or even decomposition, which seriously affects the purity and performance of the final product. (2) Complex process, low production efficiency: welding operations require experienced professional welders, as well as complex protective gas systems and fine control of process parameters such as current and voltage. The entire process is cumbersome, slow, and difficult to meet the needs of modern mass production. (3) Quality fluctuation, reliability questionable: the welded area is prone to defects such as pores and micro-cracks, which poses a potential risk of leakage. This instability in quality directly threatens the success rate of the hot isostatic pressing process and the densification of the final product. (4) High overall cost: welding equipment itself is expensive and has certain requirements for the working environment. In addition, it has high energy consumption, requires continuous supply of protective gas, and involves high labor costs, resulting in high overall sealing costs.

[0004] In view of the above, the present application is proposed. SUMMARY

[0005] The present application aims to at least solve one of the above technical problems and provides a sealing method of high-vacuum sealing sleeve and a crimping device.

[0006] To achieve the above-mentioned purpose, the first technical solution adopted by the present application is: A sealing method of high-vacuum sealing sleeve, comprising the following steps: providing a sleeve to be sealed, the sleeve being provided with an evacuation pipe; performing vacuum treatment on the sleeve to achieve a high-vacuum state inside the sleeve; The application provides a crimping device, which comprises a female block and a male block capable of relative movement, and a corrugated tooth structure is arranged on the opposite surfaces of the female block and the male block and matched with each other. The suction pipe is arranged between the female block and the male block, the female block and the male block are driven to move relative to each other by hydraulic power, the suction pipe is cold-pressed, and plastic deformation and occlusion of the suction pipe occur under the action of the corrugated tooth structure, so that sealing is realized.

[0007] Preferably, the step of cold-pressing the suction pipe adopts a multi-stage pressurizing mode. First, the suction pipe is preliminarily pressed to cause micro-deformation by using a first pressure. Then, the suction pipe is finally pressed to be completely flattened and occluded by using a second pressure greater than the first pressure.

[0008] Preferably, the first pressure is 20-40 Mpa, and the second pressure is 50-70 Mpa.

[0009] Preferably, the tooth groove circular arc radius of the corrugated tooth structure is 2-4 mm, and the tooth height is 1-2 mm.

[0010] Preferably, the high vacuum state refers to that the vacuum degree in the sleeve is not higher than 5*10⁻ 5 Pa.

[0011] Preferably, after the cold-pressing sealing is completed, the sealed sleeve is subjected to leakage detection, and it is confirmed that the leakage rate is less than 1*10⁻¹ 0 Pa.m³ / s.

[0012] The second technical scheme adopted by the application is as follows: A crimping device for realizing any sealing method described above, comprising: A handheld hydraulic clamp having a fixed end and a movable end; A female block fixed to the fixed end of the hydraulic clamp through a locking screw; A male block fixed to the movable end of the hydraulic clamp; Wherein, a corrugated tooth structure matched with each other is arranged on the opposite surfaces of the female block and the male block.

[0013] Preferably, the tooth groove circular arc radius of the corrugated tooth structure is 2-4 mm, and the tooth height is 1-2 mm.

[0014] Preferably, the tooth groove circular arc radius of the corrugated tooth structure is 3 mm, and the tooth height is 1.5 mm.

[0015] Compared with the prior art, the application has the following beneficial effects: The present application adopts cold forming principle to seal, the whole process is completed at room temperature, without any form of heat input. This fundamentally avoids the oxidation of the inner wall of the sleeve and the performance variation of the internal powder material caused by high temperature welding, which is of decisive significance for maintaining the activity of the material and ensuring the uniformity of the chemical composition and microstructure of the final product, and significantly improves the comprehensive performance and qualification rate of the product.

[0016] The present application can guide the metal material to flow and deform in an orderly manner under high pressure by the specially designed corrugated tooth-shaped jaw, so as to form a dense and pore-free mechanical sealing joint. Combined with the multi-stage pressing process, it is ensured that the internal passage of the suction pipe is completely and firmly sealed, and the leakage rate after sealing can be stably lower than 1*10 -10 Pa.m³ / s, which fully meets or even exceeds the stringent requirements of the hot isostatic pressing process on the vacuum retention performance of the sleeve.

[0017] The sealing method provided by the present application can be completed within a few seconds to tens of seconds from clamping to pressing. It is simple and convenient to operate, and does not require complex preheating, post-welding treatment and other processes, greatly shortening the production cycle. The method is easy to integrate into an automatic production line, which removes the obstacles for large-scale and batch production. The method has low dependence on the skills of the operator, and mainly relies on the equipment and mold to complete, and the key process parameters are easy to control accurately. This effectively avoids the quality fluctuation caused by human factors, and ensures the high consistency and reproducibility of the sealing quality between different batches and different sleeves. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The present application provides a flowchart of the sealing method of the high-vacuum sealed sleeve. DETAILED DESCRIPTION

[0019] The present application will be specifically described below by examples, and the technical solutions of the present application are not limited to the specific embodiments listed below. It is necessary to point out here that the present embodiment is only used to further illustrate the present application, and cannot be understood as a limitation on the protection scope of the present application. Some non-essential improvements and adjustments made by technical engineers in the field to the present application based on the content of the above-mentioned application are also regarded as falling within the protection scope of the present application.

[0020] REFERENCE Figure 1 The first embodiment of the present application provides a sealing method of a high-vacuum sealed sleeve, comprising the following steps: S1, providing a sleeve to be sealed, the sleeve being provided with a suction pipe.

[0021] This step is the preparation stage of the operation object. The sleeve is a container for containing powder or blank in the hot isostatic pressing process, and the suction pipe is the only passage for vacuumizing and subsequent sealing.

[0022] The "sleeve", usually made of metal (such as stainless steel, titanium alloy, aluminum alloy, etc.), needs to have good airtightness, high temperature strength and compatibility with the internal material.

[0023] The "exhaust pipe", a metal pipe welded to the main body of the sleeve, is the component directly affected by the method of the present application.

[0024] One premise of the present application is that the exhaust pipe needs to have certain plasticity and ductility to facilitate subsequent cold pressure deformation. Preferred materials are easily deformable metals such as aluminum alloy and pure copper.

[0025] S2, vacuum treatment is performed on the sleeve to achieve a high vacuum state inside.

[0026] The purpose of this step is to exclude air inside the sleeve and material adsorbed gas, creating a high vacuum environment, which is a prerequisite to ensure that the hot isostatic pressing product is non-oxidizing and high density.

[0027] "High vacuum state", in the present application, specifically refers to a state where the vacuum degree is not higher than 5x10 -5 Pa. This is the typical requirement of the hot isostatic pressing process for the internal environment of the sleeve.

[0028] As an example, the specific operation method is to connect the free end of the exhaust pipe to the vacuum unit (usually including mechanical pump, molecular pump, etc.) through the vacuum pipeline; first, perform leak detection using a helium mass spectrometer leak detector and other equipment to ensure that the sleeve and vacuum pipeline itself have no leaks, which is a conventional and necessary quality assurance step; after confirming that there is no leakage, start the vacuum unit for degassing and vacuumizing treatment until the vacuum gauge shows that the vacuum degree inside the sleeve is stable at 5x10 -5 Pa or a more optimal level.

[0029] The overall process of this step is a conventional technical means in the art, but the specific vacuum degree achieved is the background and premise for the effective implementation of the method of the present application.

[0030] S3, a crimping device is provided, which includes a female block and a sub-block capable of relative movement, and the relative surfaces of the female block and the sub-block are provided with mutually matched corrugated tooth structures.

[0031] This step provides the core tool for cold pressure sealing - the crimping device. The device is responsible for applying pressure to the exhaust pipe and guiding its plastic deformation into a specific sealing structure.

[0032] "Corrugated tooth structure" refers to the continuous, wavy protrusions and grooves machined on the engaging surfaces of the female block and the sub-block.

[0033] The radius of the circular arc and the tooth height are the key geometric parameters defining the tooth profile. Preferably, the radius of the circular arc is 2-4 mm, and the tooth height is 1-2 mm. In one preferred embodiment, the radius of the circular arc is 3 mm, and the tooth height is 1.5 mm.

[0034] The crimping device is usually mounted on a hand-held hydraulic clamp or similar pressure mechanism. The female block is fixed to the non-moving end of the clamp by a locking screw, and the male block is fixed to the moving end. This is the conventional way of fixing the clamp.

[0035] The key operation of this step is that before crimping, the positions of the female block and the male block must be finely adjusted to ensure that the corrugated tooth structures of the two are completely and accurately aligned. This is a decisive link to form a uniform and complete sealing line and avoid local stress concentration leading to pipe wall damage.

[0036] The corrugated tooth structure has the following effects: (1) guiding material flow: the tooth shape guides the orderly filling of metal materials to the tooth valley, avoiding disordered wrinkling; (2) forming multiple seals: the corrugated interface formed after crimping is equivalent to multiple mechanical seal barriers, greatly extending the potential leakage path; (3) strengthening mechanical interlocking: the upper and lower tooth shapes interlock, forming a firm mechanical connection macroscopically; (4) promoting metallurgical bonding: under extremely high local pressure, the pipe wall metal atoms in the tooth top region diffuse into each other, possibly forming a microscopic cold welding effect, i.e., metallurgical bonding, thereby achieving an essential seal.

[0037] S4, placing the suction pipe between the female block and the male block, driving the female block and the male block to move relative to each other by hydraulic power, cold pressing the suction pipe, causing it to plastically deform and engage under the action of the corrugated tooth structure, thereby achieving sealing.

[0038] This step is the core action of performing sealing, permanently closing the internal passage of the suction pipe through cold pressing plastic deformation.

[0039] "Cold pressing" refers to pressure processing at room temperature without external heat input, which is a fundamental feature that distinguishes it from welding.

[0040] As some preferred embodiments, the step of cold pressing the suction pipe adopts a multi-stage pressing method: first, a first pressure is used to preliminarily press the suction pipe to cause micro-deformation; then, a second pressure greater than the first pressure is used to finally press the suction pipe to be completely flattened and engaged.

[0041] As a specific example, the step operating method is: (1) place the vacuumed exhaust pipe between the aligned female block and the male block; (2) first pressurization (preliminary pressing): start the hydraulic power source and apply a relatively low pressure (for example, 20-40 MPa, preferably 30 MPa). The purpose of this stage is not to immediately seal the pipe, but to cause a controllable micro-deformation of the exhaust pipe, so that it preliminarily fits the tooth profile, and prepares for the final pressing, and at the same time, the alignment accuracy can be checked again. This step can effectively prevent the pipe wall from being sheared and broken due to direct high pressure impact. (3) Second pressurization (final pressing): immediately apply a higher pressure (for example, 50-70 MPa, preferably 60 MPa) to completely flatten the exhaust pipe. Under this high pressure, the upper and lower teeth are fully engaged, and the pipe wall metal is extruded and filled into all tooth valley spaces, and the internal passage is completely isolated. The pipe wall material bears a great surface pressure at the tooth top contact area, thereby realizing the aforementioned metallurgical bonding, and ensuring the essential reliability of the seal.

[0042] In some preferred embodiments, in order to verify the reliability of the sealing quality and ensure that the package meets the long-term vacuum preservation requirements of the hot isostatic pressing process, the step of detecting the sealed package is further included.

[0043] The second embodiment of the present application provides a crimping device for implementing any of the above sealing methods, comprising: a handheld hydraulic clamp having a fixed end and a movable end; a female block fixed to the fixed end of the hydraulic clamp by a locking screw; a male block fixed to the movable end of the hydraulic clamp; wherein the relative surfaces of the female block and the male block are provided with mutually cooperating corrugated tooth structures.

[0044] The crimping device is a special tool designed specifically for the aforementioned cold pressure sealing method. Its core function is to provide a mechanism that can accurately align, apply a large pressure, and guide metal plastic deformation, so as to press the metal exhaust pipe to form a corrugated joint with multiple sealing effects without heat input.

[0045] The device mainly includes two functional modules: power and execution module (handheld hydraulic clamp) and forming module (male and female blocks and corrugated tooth structure).

[0046] The handheld hydraulic clamp provides stable and controllable crimping force for the entire crimping process, and realizes the relative linear motion of the male block and the female block. It needs to provide a large enough rated pressure, and has enough rigidity and stroke accuracy to ensure the stability and controllability of the crimping process.

[0047] The sub-mother block and the corrugated tooth structure are the core components of the device, which are directly responsible for interacting with the suction pipe and shaping it into a predetermined sealing shape. The mother block and the sub-block are the components that directly contact and clamp the suction pipe, and are the carriers of pressure transmission and tooth shape forming. The mother block is fixed to the non-moving end of the hydraulic clamp by locking screws; the sub-block is fixed to the moving end of the hydraulic clamp in the same way. This explicit fixing method ensures that there is only pure relative linear motion between the two molds during the crimping process, avoiding deviation or twisting, which is the key mechanical design to ensure consistent sealing quality.

[0048] The corrugated tooth structure is a decisive design feature to achieve excellent sealing effect, and its purpose is far from simply flattening the pipe. The structure is composed of a series of continuous, parallel semicircular teeth and tooth tops, precisely machined on the opposite surfaces of the mother block and the sub-block, and ensures complete mutual cooperation (i.e. mirror symmetry). The tooth groove radius (R) is preferably in the range of 2-4 mm, and the best embodiment is R=3 mm. This radius design is crucial: too small radius will cause stress concentration and easily cut the pipe wall; too large radius will weaken the tooth structure and cannot effectively guide the material flow and form sufficient sealing line pressure. R=3 mm is the best balance point between ensuring the integrity of the pipe wall and forming an effective seal. The height of the tooth (H) is preferably in the range of 1-2 mm, and the best embodiment is H=1.5 mm. The tooth height determines the thickness of the sealing interface and the depth of mechanical interlocking after crimping. A height of 1.5 mm is sufficient to form a solid mechanical connection and multiple sealing barriers, while not requiring excessive crimping force or causing material instability due to excessive deformation.

[0049] The above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A sealing method for a high-vacuum sealing sleeve, characterized in that, Includes the following steps: A package to be sealed is provided, the package being equipped with an air extraction tube; The casing is evacuated to achieve a high vacuum state inside; A crimping device is provided, the crimping device comprising a mother block and a daughter block capable of relative movement, wherein corrugated toothed structures that cooperate with each other are provided on the opposing surfaces of the mother block and the daughter block. The suction pipe is placed between the mother block and the daughter block. The mother block and the daughter block are driven to move relative to each other by hydraulic power, and the suction pipe is cold-pressed, so that it undergoes plastic deformation and meshing under the action of the corrugated tooth structure, thereby achieving a seal.

2. The sealing method as described in claim 1, characterized in that, The cold compression process for the extraction pipe employs a multi-stage pressurization method: First, the suction pipe is initially compressed using a first pressure to cause it to deform slightly. Then, a second pressure greater than the first pressure is used to finally compress the suction tube, so that it is completely flattened and engaged.

3. The sealing method as described in claim 2, characterized in that, The first pressure is 20-40 MPa, and the second pressure is 50-70 MPa.

4. The sealing method as described in claim 1, characterized in that, The radius of the tooth groove of the corrugated tooth structure is 2-4 mm, and the tooth height is 1-2 mm.

5. The sealing method as described in claim 1, characterized in that, The high vacuum state refers to a vacuum level within the enclosure that is no higher than 5 × 10⁻⁻⁻⁻⁻⁵. 5 Pa.

6. The sealing method as described in claim 1, characterized in that, After cold pressing and sealing, a leak test is performed on the sealed package to confirm that the leakage rate is less than 1×10⁻¹. 0 Pa·m³ / s.

7. A crimping device for implementing the sealing method according to any one of claims 1-6, characterized in that, include: A handheld hydraulic clamp with a fixed end and a movable end; The mother block is fixed to the fixed end of the hydraulic clamp by locking screws; Sub-block, fixed to the movable end of the hydraulic clamp; The mother block and the child block have corrugated tooth-shaped structures that cooperate with each other on their opposite surfaces.

8. The sealing device as described in claim 7, characterized in that, The radius of the tooth groove of the corrugated tooth structure is 2-4 mm, and the tooth height is 1-2 mm.

9. The sealing device as described in claim 8, characterized in that, The tooth groove radius of the corrugated tooth structure is 3mm, and the tooth height is 1.5mm.

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