Mechanical pump electron beam welded magnetic field shielding method and apparatus

Abstract

The application discloses a kind of magnetic field shielding method and device of mechanical pump electron beam welding, based on the simulation analysis of the magnetic field distribution at the weld of mechanical pump, according to the shape of mechanical pump, iterative design magnetic field shielding device, adopt high permeability permalloy to make " two half splicing " type double shielding structure, the splicing seam of inside and outside two shielding layers is 90 ° angle, installed in the periphery of mechanical pump, in the premise of not changing the performance of mechanical pump itself, not transforming electron beam welding equipment realizes beam current no deflection in the process of mechanical pump electron beam welding, realizes the precision welding of mechanical pump.

Description

Technical Field

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

[0002] As mechanical pumps continue to develop towards miniaturization and precision, the spatial structure of their various components is becoming more compact, placing higher demands on the overall sealing performance of the mechanical pump.

[0003] To ensure the sealing performance of mechanical pumps, the sealing methods considered mainly include two categories. One is to use a threaded sealing structure to improve the sealing performance. However, the use of threaded sealing structures usually requires increasing the external dimensions and wall thickness of the interface, and using anti-loosening measures such as sealing gaskets, applying thread anti-loosening adhesive, or using locking wires. While increasing the size and weight of the mechanical pump, it also increases the risk of sealing reliability. It is not suitable for operating conditions where there are high requirements for the shape and weight of the mechanical pump, where there are compatibility issues between the sealing gasket / thread anti-loosening adhesive and the working medium, or where there is a vibration environment. Secondly, welding methods such as laser welding, vacuum brazing, and electron beam welding are used to achieve an effective connection between the pump casing and the motor end face through material remelting, resulting in better welding accuracy and sealing performance. However, laser welding is a non-continuous pulse, making it difficult to guarantee high weld quality and product leakage rate. Vacuum brazing is not suitable for the overall welding of mechanical pumps due to its excessively high welding temperature. Electron beam welding is a 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 strong magnetic leakage. The presence of a strong magnetic field causes the electron beam to deviate significantly due to the Lorentz force when welding the pump casing and the motor, making it impossible for the pump casing and the motor casing to be effectively connected. Summary of the Invention

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

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

[0006] (1) Record the magnetic field strength near the weld of the mechanical pump using a magnetic field testing device;

[0007] (2) Simulate and analyze 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. Each layer of the magnetic field shielding device is an axisymmetric rotating body spliced ​​from two halves of the structure.

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

[0009] (4) Install the inner shielding layer and the outer shielding layer sequentially around the mechanical pump motor along the mechanical pump axis, with the splicing seam of the outer shielding layer and the inner shielding layer forming a 90° angle.

[0010] (5) Use magnetic field testing equipment to record the changes in magnetic field strength near the weld of the mechanical pump after the installation of the magnetic field shielding device;

[0011] (6) Use test pieces to conduct welding tests and observe the beam deflection during mechanical pump electron beam welding;

[0012] (7) If the beam deflects, the shielding effect does not meet the requirements. Repeat steps (2) to (6) until the beam deflects during the mechanical pump electron beam welding process.

[0013] Furthermore, permalloy was used to fabricate the magnetic field shielding device.

[0014] Furthermore, the end face 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 obstruction 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. Both the inner shielding layer and the outer shielding layer are axisymmetric rotating bodies spliced ​​together from 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 side of the inner shielding layer near the weld seam. The splicing seam of 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, and the outer wall is cylindrical. Both the inner and outer walls of the outer shielding layer are cylindrical, and the outer wall of the inner shielding layer is tightly fitted to the inner wall of the outer shielding layer, reducing the air gap between the walls.

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

[0018] Furthermore, both the inner and outer shielding layers have radially flared edges on the end faces of the mechanical pump weld seam, extending all the way to the weld seam.

[0019] Furthermore, the flanges of the inner and outer shielding layers are tightly fitted along the axis of the mechanical pump motor to reduce the air gap between them.

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

[0021] The advantages of this invention compared to the prior art are:

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

[0023] (2) The magnetic field shielding device designed in this invention is a low-cost and compact magnetic field shielding device for use on the production line. It adopts a double-layer shielding structure to improve the shielding effect. The splicing seam of the two layers is at a 90° angle, which solves the problem of magnetic leakage at the splicing seam of the magnetic field shielding device. The magnetic field shielding device is made of high permeability permalloy μ-metal to effectively constrain the direction and spatial distribution of magnetic induction lines. The "two-half splicing" structure further reduces the installation difficulty of the magnetic field shielding device. Attached Figure Description

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

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

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

[0027] Figure 4 This is a schematic diagram of the "flanged" structure of the inner and outer shielding layers. Detailed Implementation

[0028] To better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0029] like Figure 1 As shown, the mechanical pump consists of a motor 1, an impeller 2, and a pump casing 3. The motor provides the power output required for the operation of the mechanical pump. The pump casing is connected to the end face of the motor to form a sealed cavity. The impeller is mounted on the motor shaft and rotates at high speed in the sealed cavity to drive the flow of liquid or gas medium.

[0030] The magnetic field shielding method for mechanical pump electron beam welding proposed in this invention is designed with 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) Simulate and analyze the magnetic field distribution at the weld of the mechanical pump, and design a magnetic field shielding device based on the structural dimensions of the mechanical pump; such as 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 rotating bodies spliced ​​together from two halves of the structure.

[0033] (3) The above magnetic field shielding device was made using permalloy μ-metal;

[0034] (4) Figure 3 As shown, the inner and outer shielding layers are sequentially installed around the mechanical pump motor along the mechanical pump axis, each spliced ​​into a whole, and the splicing seam of the outer and inner shielding layers is adjusted to a 90° angle; wherein, the end face of the magnetic field shielding device should be at least 1 mm away from the weld seam along the mechanical pump axis to prevent blocking the electron beam current;

[0035] (5) Use magnetic field testing equipment to record the changes in magnetic field strength near the weld of the mechanical pump after the installation of the magnetic field shielding device;

[0036] (6) Use test pieces to conduct welding tests, observe the 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 current does not deflect during the mechanical pump electron beam welding process.

[0038] Specifically, both the inner and outer shielding layers are axisymmetric rotating bodies composed of two halves of the structure. The inner shielding layer is installed around the mechanical pump motor and covers the axial length of the mechanical pump motor. The outer shielding layer is fitted over the inner shielding layer on the side near the weld seam, and the splicing seam of the outer and inner shielding layers forms a 90° angle.

[0039] The inner shielding layer allows for grooves to be made at the corresponding positions of the mechanical pump leads to prevent interference with the leads.

[0040] The inner wall of the inner shielding layer matches the shape of the mechanical pump motor, and the outer wall is cylindrical. Both the inner and outer walls of the outer shielding layer are cylindrical. The outer wall of the inner shielding layer is tightly fitted to the inner wall of the outer shielding layer, reducing 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] Both the inner and outer shielding layers have radially oriented "flanged edges" on their left end faces (the end faces closest to the mechanical pump weld). Figure 2 and Figure 4As shown, the outer shielding layer flange 7 and the inner shielding layer flange 8 extend to the vicinity of the weld. The flanges of the inner and outer shielding layers fit tightly together along the axis of the mechanical pump motor, reducing the air gap between them.

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

[0044] The right end face (the end face away from the mechanical pump weld) of the inner and outer shielding layers may not have a radially oriented "flanged edge".

[0045] Preferably, where space allows and the electron beam current is not obstructed, the shielding effect can be improved by appropriately increasing the wall thickness of the cylindrical sections and end faces of the inner and outer shielding layers.

[0046] It is understood that this invention has been described through embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of this invention. Furthermore, under the teachings of this invention, these features and embodiments can be modified to adapt to specific circumstances without departing from the spirit and scope of this invention. Therefore, this invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are protected by this invention.

[0047] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A magnetic field shielding method for electron beam welding of a mechanical pump, characterized in that, Includes the following steps: (1) Record the magnetic field strength near the weld of the mechanical pump using a magnetic field testing device; (2) Simulate and analyze the magnetic field distribution at the weld of the mechanical pump, and design a magnetic field shielding device based on the structural dimensions of the mechanical pump; The magnetic field shielding device is designed with a double-layer structure, including an outer shielding layer and an inner shielding layer. Each magnetic field shielding device is an axisymmetric rotating body spliced ​​from two halves of the structure. The inner wall of the inner shielding layer matches the shape of the mechanical pump motor, and the outer wall is cylindrical. The inner and outer walls of the outer shielding layer are also cylindrical, and the outer wall of the inner shielding layer is in close contact with the inner wall of the outer shielding layer. The end faces of the inner and outer shielding layers near the weld of the mechanical pump have flanges that point radially towards the center and extend all the way to the weld. (3) Use permalloy to make magnetic field shielding devices; (4) The inner shielding layer and the outer shielding layer are installed sequentially around the mechanical pump motor along the axial direction of the mechanical pump. The inner shielding layer covers the axial length of the mechanical pump motor. The outer shielding layer is fitted on the side of the inner shielding layer near the weld, and its length along the axial direction of the mechanical pump motor covers at least one-third of the axial length of the inner shielding layer. The end face is at least 1 mm away from the weld along the axial direction of the mechanical pump. The splicing seam of the outer shielding layer and the inner shielding layer forms a 90° angle. (5) Use magnetic field testing equipment to record the changes in magnetic field strength near the weld of the mechanical pump after the installation of the magnetic field shielding device; (6) Use test pieces to conduct welding tests and observe the beam deflection during mechanical pump electron beam welding; (7) If the beam deflects, the shielding effect does not meet the requirements. Repeat steps (2) to (6) until the beam deflects during the mechanical pump electron beam welding process.

2. A magnetic field shielding device for electron beam welding of a mechanical pump, characterized in that: Made of permalloy, the shielding consists of an inner and an outer shielding layer, both of which are axisymmetric bodies of revolution formed by splicing two halves of the structure. The inner wall of the inner shielding layer matches the shape of the mechanical pump motor, while the outer wall is cylindrical. Both the inner and outer walls of the outer shielding layer are cylindrical, and the outer wall of the inner shielding layer is tightly fitted to the inner wall of the outer shielding layer. The end faces of both the inner and outer shielding layers near the weld of the mechanical pump have radially flared edges pointing towards the center, extending all the way to the weld. The inner shielding layer is installed around the mechanical pump motor, covering its axial length. The outer shielding layer is fitted over the inner shielding layer near the weld, and its axial length along the mechanical pump motor covers at least one-third of the axial length of the inner shielding layer. The end face is at least 1 mm away from the weld along the mechanical pump axial direction. The splicing seam between the outer and inner shielding layers forms a 90° angle.

3. The magnetic field shielding device for mechanical pump electron beam welding according to claim 2, characterized in that: The flange thickness of the inner and outer shielding layers is at least 0.3 mm.

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