Precise laser welding device and method for centrifugal injection assembly

Abstract

The invention discloses a precise laser welding device and method for a centrifugal injection assembly. The method comprises the following steps that the butt joint face of the injection assembly to be welded is cleaned before welding; the to-be-welded injection assembly is fixed in a welding tool; the welding tool is filled with deionized water, and then the to-be-welded injection assembly and the welding tool are placed in a low-temperature environment to enable water to be frozen, so that the to-be-welded injection assembly is fixed; and then the to-be-welded injection assembly and the welding tool are integrally taken out, and positioned welding and formal welding are carried out. According to the method, the to-be-welded injection assembly is fixed in a water freezing mode, on one hand, thermal deformation in the welding process is restrained, on the other hand, the to-be-welded injection assembly can be effectively cooled, heat input to the to-be-welded injection assembly is reduced, the risk that deformation is out of tolerance after welding is greatly reduced, and the welding quality is improved. And the qualified rate of post-welding liquid flow of the injection assembly is improved.

Description

Technical Field

[0001] The present invention relates to a precision laser welding device and method for a centrifugal injection assembly, belonging to the field of welding technology. Background Art

[0002] With the improvement of the integration of future attitude and orbit control power systems, higher requirements are put forward for the volume of thrust chamber products. The centrifugal thrust chamber has the characteristics of compact structure and high reliability, and is an important development direction for future attitude and orbit control power systems. Among them, the injection assembly is the core component of the centrifugal thrust chamber, which is often welded into a cantilever structure. Due to the influence of welding thermal deformation, the coaxiality of the cantilever structure will change during welding, resulting in problems such as out-of-tolerance uniformity, unqualified atomization, and unstable liquid beam in the liquid flow test of the injector, and the qualified rate has always been not high.

[0003] Currently, the method of rigid fixture fixation is often used to control welding deformation. Since the surface of the injection component is a precision polished surface, problems such as scratches and bruises often occur after rigid fixation. Moreover, the injection components are generally microstructures within Φ10, and traditional heat dissipation fixtures cannot effectively remove the welding heat, resulting in excessive deformation problems. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: overcoming the deficiencies of the prior art, providing a precision laser welding device and method for a centrifugal injection assembly, overcoming the problems of product damage and heat dissipation caused by rigid fixtures, and providing a new solution for the welding of centrifugal injection assemblies.

[0005] The object of the present invention is achieved through the following technical solutions:

[0006] In the first aspect, the present invention provides a precision laser welding device for a centrifugal injection assembly, including a cover plate, a base, and bolts connecting the two;

[0007] The front of the cover plate is distributed with hollowed-out waist-shaped grooves, and there are blind holes on the back. At the same time, through connection holes and water injection holes are provided. The waist-shaped grooves are symmetrically distributed for the laser to shine down during positioning. The blind holes on the back are matched with the outer diameter of the injector housing to realize the positioning of the injector. The water injection holes are connected to the cavity of the base for injecting water into the base. The bolts pass through the connection holes and are connected to the base;

[0008] The inside of the base is provided with a first cavity and a second cavity. Among them, the first cavity is used for water injection, and the second cavity is used for fixing the injection assembly to be welded. The two are connected through a hole to ensure that the water levels in the two cavities are the same.

[0009] In the second aspect, the present invention provides a precision laser welding method for a centrifugal injection assembly using the welding fixture described in the first aspect, including:

[0010] (1) Clean the butt joint surface of the jet injection component to be welded before welding;

[0011] (2) Fix the jet injection component to be welded in the welding device;

[0012] (3) Fill the welding device with deionized water, and then place the jet injection component to be welded and the welding device in a low-temperature environment to freeze the water, thereby fixing the jet injection component to be welded;

[0013] (4) Take out the whole jet injection component to be welded and the welding device, and carry out tack welding and formal welding.

[0014] In a third aspect, the present invention provides a centrifugal jet injection component, which is prepared by using the precision laser welding method described in the second aspect.

[0015] The present invention has the following beneficial effects compared with the prior art:

[0016] (1) The method of the present invention utilizes the principle of water freezing to achieve high-precision fixation of different parts of the jet injection component, avoiding defects such as indentation and scratches on the surface of the jet injection component caused by rigid fixation, maintaining the good state of the surface of the machined parts, and suppressing the fluid dispersion phenomenon;

[0017] (2) Ice can strengthen the heat dissipation effect during the welding process, reduce the heat accumulation on the jet injection component, thereby reducing the amount of thermal deformation and improving the post-welding precision of the parts;

[0018] (3) After welding, measures such as heating and drying can be used to conveniently remove the moisture inside the parts, and no redundant substances and residues are generated, and the product quality consistency is high.

[0019] (4) Pure water is the most commonly used medium in life, and the high-precision welding method for the jet injection component proposed by the present invention can be implemented more conveniently. Description of the Drawings

[0020] Figure 1 It is a structure diagram of the jet injection component;

[0021] Figure 2 It is a cover plate;

[0022] Figure 3 It is a base;

[0023] Figure 4 It is an assembly drawing of the jet injection component and the tooling. Detailed Embodiments

[0024] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will further describe the embodiments of the present invention in detail with reference to the drawings.

[0025] A precision laser welding device for a centrifugal injection component, comprising a cover plate, a base, and bolts connecting the two, as Figure 2 and Figure 3 shown.

[0026] The front of the cover plate is distributed with hollow waist-shaped grooves, and there are blind holes on the back. At the same time, through connection holes and water injection holes are processed. The waist-shaped grooves are symmetrically distributed and are used for the laser beam from below during positioning; the blind holes on the back are matched with the outer diameter of the injector housing to achieve the positioning of the injector; the water injection holes are connected to the cavity 1 of the base and are used to add water into the base. The bolts pass through the connection holes and are connected to the base. By the pressing of the bolts, the blind holes on the cover plate can be in contact with the plug and the housing to achieve positioning.

[0027] Inside the base, there are cavity 1 and cavity 2. Among them, cavity 1 is used for water injection, and cavity 2 is used for fixing the injection component to be welded. The two are connected through a hole channel to ensure that the water levels in the two cavities are the same.

[0028] A precision laser welding method for a centrifugal injection component, comprising:

[0029] (1) Before welding, clean the butt joint surfaces of the injection component to be welded (including the plug and the housing). The plug is a T-shaped rotating body, the lower part of which is a smooth hemispherical surface, and the height of the center of the spherical surface is H1. The housing is a rotating structure with tangential injection holes, and the height position of the lowest point of the tangential hole is H2;

[0030] (2) Fix the injection component to be welded in the welding device;

[0031] (3) Fill the welding device with deionized water, and then place the injection component to be welded and the welding device in a low-temperature environment to freeze the water so as to fix the injection component to be welded;

[0032] (4) Take out the injection component to be welded and the welding device as a whole, and perform tack welding and formal welding.

[0033] Further, in step (1), the butt joint surfaces to be welded should be thoroughly cleaned. The cleaning methods include processes such as machining, precision pickling, and laser cleaning to ensure that there is no oxidation color and other impurities attached to the butt joint surfaces.

[0034] Further, in step (2), when fixing the injection component to be welded, uniform downward pressure should be applied.

[0035] Further, in step (3), the height of the filled water is lower than the plane where the weld is located. The temperature of the low-temperature environment should be lower than 0 °C, and the storage time in the low-temperature environment should be not less than 1 h to ensure that all the water is changed from liquid to solid.

[0036] Further, in step (4), the welding method used is vacuum laser welding. Among them, the tack welding adopts a symmetric positioning form, and the starting and ending arcs of the formal welding should avoid the tack welding points.

[0037] Further, in step (4), the vacuum degree of the welding chamber is not greater than 10 Pa, the defocus amount during welding is -10 to +10, and the welding speed is 1 m / min to 3 m / min.

[0038] Example:

[0039] As Figure 1 shown, the injection component is formed by vacuum laser welding of a housing and a plug cover, and the materials are both TC4. The specific steps are as follows:

[0040] (1) Before welding, the welding parts of the housing and the plug cover are cleaned by precision pickling to ensure that there is no oxidation color or other impurities attached to the butt joint surface.

[0041] (2) Place the inner nozzle into the housing, then place the housing into cavity 2 of the base, and fix the base and the cover plate with bolts. Tighten the three bolts alternately to ensure that the plug is in a uniformly stressed state.

[0042] (3) Inject pure water into the base through the water injection hole on the cover plate. The water level height H should satisfy: H2 ≥ H > H1, see Figure 4 .

[0043] (4) Place the assembled body after water injection into the refrigerator (-18 °C), take it out after cooling for 5 h, ensure that all the water has frozen, and then invert the tooling. No liquid water should flow out from cavity 1.

[0044] (5) Use vacuum laser welding to weld the product. First, perform symmetric positioning with a positioning power of 100 W and a single-point positioning time of 1 s. After positioning, remove the fixing bolts and the cover plate, and perform circumferential welding. The starting and ending arcs of the circumferential welding should avoid the positioning points. The vacuum degree during welding is 10 Pa, the defocus amount is -5, and the welding speed is 2.4 m / min.

[0045] (6) After welding, place the injection component and the base in a normal temperature environment (temperature > 0 °C). After the ice melts, take out the product and dry it for 2 h.

[0046] Welding is carried out according to the method of this embodiment. The coaxiality between the plug cover and the housing after welding is 0.01 mm. Five-level liquid flow tests are carried out under the rated water flow rate of 5.47 g / s and its variations of 10% and 20%. All are qualified at one time.

[0047] The content not detailed in the description of the present invention belongs to the well-known technology of those skilled in the art.

[0048] Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A precision laser welding device for centrifugal injection components, characterized in that: It includes a cover plate, a base and bolts connecting the two; The front of the cover plate is provided with hollow waist-shaped grooves, the back is provided with blind holes, and penetrating connection holes and water injection holes. The waist-shaped grooves are symmetrically distributed and used for laser beam lowering during positioning. The blind holes on the back are matched with the outer diameter of the injector shell to realize the positioning of the injector. The water injection holes are connected with the cavity of the base and used to add water into the base. Bolts penetrate the connection holes and are connected to the base. A first cavity and a second cavity are provided inside the base, wherein the first cavity is used for water injection, and the second cavity is used for fixing the injection assembly to be welded, and the two cavities are connected through a channel to ensure that the water levels in the two cavities are the same.

2. The precision laser welding device according to claim 1, characterized in that: By tightening the bolts, the blind holes on the cover plate can be brought into contact with the plugging cover and the shell to achieve positioning.

3. A precision laser welding method of a centrifugal injection assembly using the welding tooling according to claim 1 or 2, characterized in that: include: (1) Clean the butt joint of the injection molding assembly before welding; (2) Fixing the injection assembly to be welded in the welding device; (3) filling the welding device with deionized water, and then placing the injection component to be welded and the welding device in a low-temperature environment to freeze the water, thereby fixing the injection component to be welded; (4) Take out the injection assembly to be welded and the welding device as a whole, and perform positioning welding and formal welding.

4. The precision laser welding method according to claim 3, characterized in that: In step (1), the cleaning method includes one of mechanical processing, precision pickling, and laser cleaning to ensure that there is no oxidation color and other impurities attached to the butt joint surface.

5. The precision laser welding method according to claim 3, characterized in that: In step (2), the injection-molded component to be welded is fixed with uniform downward pressure.

6. The precision laser welding method according to claim 3, characterized in that: In step (4), the welding method adopted is vacuum laser welding, wherein the positioning welding adopts a symmetrical positioning form, and the starting and ending arcs of the formal welding avoid the welding points of the positioning welding.

7. The precision laser welding method according to claim 6, characterized in that: In step (4), the vacuum degree of the welding chamber is not greater than 10Pa, the defocusing amount during welding is -10 to +10, and the welding speed is 1m / min to 3m / min.

8. The precision laser welding method according to claim 3, characterized in that: Pure water is injected into the base through the water injection hole on the cover plate, and the water level height H should satisfy: H2≥H>H1; the plug cover is a T-shaped rotating body, the lower part is a smooth hemispherical surface, the center height of the spherical surface is H1, and the shell is a rotating structure with a tangential injection hole, and the lowest height position of the tangential hole is H2.

9. A centrifugal injection assembly, characterized in that: The method is prepared by the precision laser welding method described in any one of claims 3 to 8.

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