Magnetic field shielding method and device for mechanical pump electron beam welding

Abstract

The invention discloses a magnetic field shielding method and device for electron beam welding of a mechanical pump, based on simulation analysis of magnetic field distribution at a weld joint of the mechanical pump, according to the appearance of the mechanical pump, the magnetic field shielding device is iteratively designed, a two-half splicing type double-layer shielding structure is made of permalloy with high magnetic permeability, and a splicing seam of an inner shielding layer and an outer shielding layer forms an included angle of 90 degrees. The device is installed on the periphery of the mechanical pump, beam deflection in the mechanical pump electron beam welding process is avoided on the premise that the performance of the mechanical pump is not changed and electron beam welding equipment is not transformed, and precise welding of the mechanical pump is achieved.

Description

Technical Field

[0001] The invention relates to the field of aerospace welding, in particular to a magnetic field shielding device for mechanical pump electron beam welding. Background Art

[0002] As mechanical pumps continue to develop in the direction of miniaturization and precision, the spatial structure of their parts and components has become more compact, which places higher requirements on the overall sealing of the mechanical pump.

[0003] In order to ensure the sealing of the mechanical pump, the sealing methods considered mainly include two categories. One is to use a threaded sealing structure to improve the sealing. However, the use of a threaded sealing structure usually requires increasing the overall dimensions and wall thickness of the interface position, and using sealing gaskets, applying thread anti-loosening glue, or using locking wires and other anti-loosening measures. While increasing the size and weight of the mechanical pump, it also increases the risk of sealing reliability. It is not suitable for use in conditions with high requirements on the appearance and weight of the mechanical pump, where there are compatibility issues between the sealing gasket / thread anti-loosening glue and the working medium, and where there are vibration environments. The second is to use laser welding, vacuum brazing, electron beam welding and other welding methods to achieve effective connection between the pump casing and the motor end face by remelting the material, so as to obtain better welding accuracy and sealing performance; however, laser welding is a non-continuous pulse, and it is difficult to ensure high weld quality and product leakage rate; vacuum brazing is not suitable for whole machine welding of mechanical pumps due to its excessively high welding temperature; electron beam welding is a more preferred method, but because the magnets in the mechanical pump motor are made of permanent magnet materials such as samarium cobalt and neodymium iron boron, the high magnetic energy product also brings about a strong magnetic leakage phenomenon. The existence of a strong magnetic field causes the electron beam to be greatly offset by the Lorentz force when the mechanical pump casing and the motor are welded, and the pump casing and the motor casing cannot be effectively connected. Summary of the invention

[0004] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and provide a magnetic field shielding method and device for mechanical pump electron beam welding, so as to solve the problem that during the electron beam welding of the mechanical pump as a whole, the electron beam current is greatly deviated due to the influence of the strong magnetic field inside the motor and cannot be focused on the weld position.

[0005] The technical solution of the present invention is: a magnetic field shielding method for mechanical pump electron beam welding, comprising the following steps:

[0006] (1) Use magnetic field testing equipment to record the magnetic field strength near the weld of the mechanical pump;

[0007] (2) The magnetic field distribution at the weld of the mechanical pump is simulated and analyzed, and a magnetic field shielding device is designed according to the structural dimensions of the mechanical pump; the magnetic field shielding device is designed as a double-layer structure, including an outer shielding layer and an inner shielding layer, and each layer of the magnetic field shielding device is an axisymmetric body of revolution formed by splicing two half structures;

[0008] (3) Making a magnetic field shielding device;

[0009] (4) The inner shielding layer and the outer shielding layer are sequentially installed on the periphery of the motor of the mechanical pump along the axial direction of the mechanical pump, and the joint seam of the outer shielding layer and the inner shielding layer forms an angle of 90°;

[0010] (5) Use magnetic field testing equipment to record the change in magnetic field intensity near the weld of the mechanical pump after the magnetic field shielding device is installed;

[0011] (6) Conduct welding tests using test pieces to observe beam deflection during mechanical pump electron beam welding;

[0012] (7) If the beam has deflection, the shielding effect does not meet the requirements, and steps (2) to (6) are repeated until the beam has no deflection during the mechanical pump electron beam welding process.

[0013] Furthermore, the magnetic field shielding device is made of Permalloy.

[0014] Furthermore, the end surface of the magnetic field shielding device is at least 1 mm away from the weld along the axial direction of the mechanical pump to prevent shielding of the electron beam.

[0015] The present invention also provides a magnetic field shielding device for electron beam welding of a mechanical pump, comprising an inner shielding layer and an outer shielding layer, wherein the inner shielding layer and the outer shielding layer are both axisymmetric rotating bodies formed by splicing two half structures, the inner shielding layer is installed on the periphery of the mechanical pump motor, covering the axial length of the mechanical pump motor, and the outer shielding layer is sleeved on the side of the inner shield layer close to the weld, and the splicing seam between the outer shielding layer and the inner shielding layer forms a 90° angle.

[0016] Furthermore, the inner wall of the inner shielding layer matches the shape of the mechanical pump motor, the outer wall is a cylindrical surface, the inner and outer walls of the outer shielding layer are both cylindrical surfaces, and the outer wall of the inner shielding layer fits tightly with the inner wall of the outer shielding layer to reduce the air gap between the walls.

[0017] Furthermore, the length of the outer shielding layer along the axial direction of the mechanical pump motor covers at least one third of the axial length of the inner shielding layer.

[0018] Furthermore, the end faces of the inner shielding layer and the outer shielding layer close to the weld of the mechanical pump both have flanges radially pointing to the center of the circle and extending all the way to the weld position.

[0019] Furthermore, the flanges of the inner shielding layer and the outer shielding layer are closely fitted along the axis direction of the mechanical pump motor, thereby reducing the air gap between the two.

[0020] Furthermore, the flange thickness of the inner shielding layer and the outer shielding layer is at least 0.3 mm.

[0021] The advantages of the present invention compared with the prior art are:

[0022] (1) Existing electron beam welding of magnetic products mostly adopts the process method of "demagnetizing-welding-remagnetizing" the product. However, this method has a complicated process and a long production cycle, and is not suitable for mechanical pumps with high assembly precision or equipped with permanent magnets that cannot be demagnetized. The magnetic field shielding method proposed in the present invention enables electron beam welding of mechanical pumps to achieve zero beam deflection during the electron beam welding process without changing the performance of the mechanical pump itself or modifying the electron beam welding equipment, thereby achieving precision welding of the mechanical pump.

[0023] (2) The magnetic field shielding device designed by the present invention is a low-cost, compact magnetic field shielding device for use on-site in production lines. It adopts a double-layer shielding structure to improve the shielding effect. The joint seams of the two layers form a 90° angle, which solves the problem of magnetic leakage at the joint seams of the magnetic field shielding device. The magnetic field shielding device is made of high-permeability Permalloy μ-metal to effectively restrict the direction and spatial distribution of the magnetic induction lines. The "two-half splicing" structure is adopted to further reduce the difficulty of installing the magnetic field shielding device. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the structure of a mechanical pump in the prior art;

[0025] Figure 2 It is a schematic structural diagram of the magnetic field shielding device for electron beam welding of a mechanical pump according to the present invention;

[0026] Figure 3 It is a schematic diagram of the installation of the magnetic field shielding device for electron beam welding of a mechanical pump of the present invention;

[0027] Figure 4 It is a schematic diagram of the "flanged" structure of the end faces of the inner and outer shielding layers. DETAILED DESCRIPTION

[0028] In order to better understand the technical solution of the present invention, the embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0029] like Figure 1 As shown, the mechanical pump is composed of a motor 1, an impeller 2, a pump casing 3 and other parts, wherein the motor is used to provide the power output required for the mechanical pump to work, the pump casing is connected to the motor end face to form a sealed cavity, and the impeller is installed on the motor shaft and rotates at high speed in the above-mentioned sealed cavity to drive the liquid or gas medium to flow.

[0030] The magnetic field shielding method for mechanical pump electron beam welding proposed by the present invention is designed to include the following steps:

[0031] (1) First, use a magnetic field testing device to record the magnetic field strength near the weld of the mechanical pump;

[0032] (2) Conduct simulation analysis on the magnetic field distribution at the weld of the mechanical pump and design a magnetic field shielding device according to the structural dimensions of the mechanical pump; Figure 2 As shown, the magnetic field shielding device is designed as a double-layer structure, including an outer shielding layer 4 and an inner shielding layer 5, both of which are axisymmetric bodies of revolution formed by splicing two half structures;

[0033] (3) Using Permalloy μ-metal to make the magnetic field shielding device;

[0034] (4) Figure 3 As shown, the inner shielding layer and the outer shielding layer are sequentially installed on the periphery of the mechanical pump motor along the axial direction of the mechanical pump, and are spliced ​​into a whole, and the splicing seams of the outer shielding layer and the inner shielding layer are adjusted to form a 90° angle; wherein, the end surface portion of the magnetic field shielding device should be at least 1 mm away from the weld 6 along the axial direction of the mechanical pump to prevent shielding of the electron beam flow;

[0035] (5) Use magnetic field testing equipment to record the change in magnetic field intensity near the weld of the mechanical pump after the magnetic field shielding device is installed;

[0036] (6) Conduct welding tests using test pieces to observe beam deflection during mechanical pump electron beam welding and verify the magnetic field shielding effect;

[0037] (7) If the magnetic field shielding effect does not meet the requirements and the magnetic field strength at the weld position is still large, repeat steps (2) to (6) until the beam does not deflect during the mechanical pump electron beam welding process.

[0038] Specifically, the inner shielding layer and the outer shielding layer are both axisymmetric rotating bodies formed by splicing two half structures. The inner shielding layer is installed on the periphery of the mechanical pump motor, covering the axial length of the mechanical pump motor. The outer shielding layer is sleeved on the outside of the inner shield layer close to the weld, and the joint seam between the outer shielding layer and the inner shielding layer forms a 90° angle.

[0039] The inner shielding layer allows a groove to be opened at a position corresponding to the lead-out line of the mechanical pump to prevent interference with the lead-out line.

[0040] The inner wall of the inner shielding layer matches the shape of the mechanical pump motor, and the outer wall is a cylindrical surface. The inner and outer walls of the outer shielding layer are both cylindrical surfaces. The outer wall of the inner shielding layer fits tightly with the inner wall of the outer shielding layer to reduce the air gap between the walls.

[0041] Preferably, the length of the outer shielding layer along the axial direction of the mechanical pump motor covers at least one third of the axial length of the inner shielding layer.

[0042] The left end faces of the inner shielding layer and the outer shielding layer (the end faces close to the welding seam of the mechanical pump) have "flanges" radially pointing to the center of the circle, such as Figure 2 and Figure 4As shown, the outer shielding layer flange 7 and the inner shielding layer flange 8 extend all the way to the vicinity of the weld position. The flanges of the inner shielding layer and the outer shielding layer fit closely along the axis direction of the mechanical pump motor to reduce the air gap between the two.

[0043] Preferably, the flange thickness of the inner shielding layer and the outer shielding layer is at least 0.3 mm.

[0044] The right end faces of the inner shielding layer and the outer shielding layer (the end faces away from the welding seam of the mechanical pump) may not have a "flange" radially pointing to the center of the circle.

[0045] Preferably, when the space size allows and the electron beam is not blocked, the shielding effect is improved by appropriately increasing the wall thickness of the cylindrical sections and end faces of the inner and outer shielding layers.

[0046] It is to be understood that the present invention is described by way of embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and embodiments that can fall within the scope of the claims of this application all fall within the scope protected by the present invention.

[0047] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A magnetic field shielding method for mechanical pump electron beam welding, characterized in that: The steps include: (1) Use magnetic field testing equipment to record the magnetic field strength near the weld of the mechanical pump; (2) Conduct simulation analysis on the magnetic field distribution at the weld of the mechanical pump and design a magnetic field shielding device according to the structural dimensions of the mechanical pump; The magnetic field shielding device is designed as a double-layer structure, including an outer shielding layer and an inner shielding layer, and each layer of the magnetic field shielding device is an axisymmetric rotating body formed by splicing two half structures; (3) Making a magnetic field shielding device; (4) The inner shielding layer and the outer shielding layer are sequentially installed on the periphery of the motor of the mechanical pump along the axial direction of the mechanical pump, and the joint seam of the outer shielding layer and the inner shielding layer forms an angle of 90°; (5) Use magnetic field testing equipment to record the change in magnetic field intensity near the weld of the mechanical pump after the magnetic field shielding device is installed; (6) Conduct welding tests using test pieces to observe beam deflection during mechanical pump electron beam welding; (7) If the beam has deflection, the shielding effect does not meet the requirements, and steps (2) to (6) are repeated until the beam has no deflection during the mechanical pump electron beam welding process.

2. The magnetic field shielding method for mechanical pump electron beam welding according to claim 1, characterized in that: The magnetic field shielding device is made of Permalloy.

3. The magnetic field shielding method for mechanical pump electron beam welding according to claim 1, characterized in that: The end surface of the magnetic field shielding device is at least 1 mm away from the weld along the axial direction of the mechanical pump to prevent the electron beam from being blocked.

4. A magnetic field shielding device for mechanical pump electron beam welding, characterized in that: It includes an inner shielding layer and an outer shielding layer. Both the inner shielding layer and the outer shielding layer are axisymmetric rotating bodies formed by splicing two half structures. The inner shielding layer is installed on the periphery of the mechanical pump motor to cover the axial length of the mechanical pump motor. The outer shielding layer is sleeved on the side of the inner shield layer close to the weld. The splicing seam between the outer shielding layer and the inner shielding layer forms a 90° angle.

5. The magnetic field shielding device for mechanical pump electron beam welding according to claim 4, characterized in that: The inner wall of the inner shielding layer matches the shape of the mechanical pump motor, and the outer wall is a cylindrical surface. The inner and outer walls of the outer shielding layer are both cylindrical surfaces. The outer wall of the inner shielding layer fits tightly with the inner wall of the outer shielding layer to reduce the air gap between the walls.

6. The magnetic field shielding device for mechanical pump electron beam welding according to claim 4, characterized in that: The length of the outer shielding layer along the axial direction of the mechanical pump motor covers at least one third of the axial length of the inner shielding layer.

7. The magnetic field shielding device for mechanical pump electron beam welding according to claim 4, characterized in that: The end faces of the inner shielding layer and the outer shielding layer close to the welding seam of the mechanical pump are both provided with flanges radially pointing to the center of the circle and extending all the way to the welding seam position.

8. The magnetic field shielding device for mechanical pump electron beam welding according to claim 7, characterized in that: The flanges of the inner shielding layer and the outer shielding layer are closely fitted along the axis direction of the mechanical pump motor to reduce the air gap between the two.

9. The magnetic field shielding device for mechanical pump electron beam welding according to claim 7, characterized in that: The flange thickness of the inner and outer shielding layers shall be at least 0.3 mm.

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