CN112737241A

CN112737241A - Method of manufacturing a rotor assembly

Info

Publication number: CN112737241A
Application number: CN202011504154.6A
Authority: CN
Inventors: 魏中华; 梅锐; 何剑锋; 祝庆华; 吕婷茹; 何建飞
Original assignee: Zhejiang Innuovo Magnetics Industry Co Ltd
Current assignee: Zhejiang Innuovo Magnetics Industry Co Ltd
Priority date: 2020-12-18
Filing date: 2020-12-18
Publication date: 2021-04-30

Abstract

The invention discloses a method for manufacturing a rotor assembly, which comprises the steps of heating a shaft to enable an adhesive to overflow and be fixed with the shaft; the method specifically comprises the following steps: providing magnetic powder and a binder, and uniformly mixing the magnetic powder and the binder; pressing into an uncured magnet by using a mold; providing a metal shaft required by fixing a magnet, wherein the shaft is made of a metal material easy to be inductively heated; freely mounting the magnet on the shaft, and positioning the magnet through steps on the shaft or other parts mounted on the shaft or an external positioning plate; heating the metal shaft by using a medium-frequency or high-frequency power supply and an induction coil, and heating and overflowing the binder in the inner hole part of the magnet so as to fix the magnet on the shaft; and integrally heating the fixed magnet assembly to solidify the whole magnet.

Description

Method of manufacturing a rotor assembly

Technical Field

The invention belongs to the field of high-speed rotors of motors, and particularly relates to a method for manufacturing a rotor assembly.

Background

The rotor of an electric machine typically includes a rotor core secured to a shaft. The rotor core may include a magnet having a bore through which the shaft is received. Most magnets are brittle and will crack if subjected to excessive tensile stress. Therefore, the magnet is not typically press-fitted to the shaft, but rather bonded to the shaft.

It is now possible to adhere the magnet to the shaft by applying a layer of adhesive to the shaft and then inserting the shaft into the bore of the magnet. During insertion, the shaft may be rotated relative to the magnet in order to obtain better adhesive dispensing. The disadvantages are as follows: 1. as the length of the magnet increases, it becomes increasingly difficult to continuously dispense adhesive along the entire length of the bore, resulting in weaker bond strength; 2. the selection requirement of the adhesive is high, the liquid adhesive is easy to pollute the surfaces of the magnetic steel and the shaft, and the subsequent treatment is troublesome; 3. the shaft and the magnetic steel are bonded only by forming a layer of bonding surface on the surface, and the bonding surface is easy to tear under the condition of high rotating speed, so the strength is not enough.

Alternatively, the magnet may be adhered to the shaft by inserting the shaft into the hole of the magnet and then injecting an adhesive into the gap between the shaft and the magnet. The disadvantages are as follows: 1. the whole contact surface of the shaft and the magnet is generally difficult to be uniformly distributed, and the connection can be weakened; 2. this is particularly true when the gap is relatively small; 3. the operation requirement of the binder post-adding process is high, the operation efficiency is low, the limitation is more, in addition, the influence of the selection of the binder type and the post-treatment is obvious, and the binding strength required by the high-speed rotation condition is difficult to obtain.

By heating the intermediate assembly, the magnetic steel naturally overflows glue and then is bonded to the shaft. The specific method comprises the following steps: providing a magnet in an uncured state, the magnet comprising magnetic powder and a binder; providing a shaft to which the magnet is to be secured; and assembling the intermediate rotor assembly with the uncured magnets on the shaft. The intermediate rotor assembly is then heated and the magnet is cured, allowing a quantity of adhesive to escape from the magnet, thereby forming a bond between the magnet and the shaft. The advantages are that: 1. the process is more convenient compared with the method of adding the adhesive; 2. an adhesive strength satisfying a high rotational speed of the rotor can be formed. The disadvantages are as follows: 1. in order to achieve the bonding performance exceeding a certain strength, the process is relatively limited, and the fit clearance between the magnet and the shaft is required to be as small as possible, so that the requirement on the manufacturing precision of the magnet and the shaft is high, and the manufacturing difficulty is high; 2. the shaft is selected from a shaft (such as a ceramic shaft) with large roughness, and the bonding performance of the optical axis is difficult to meet the use requirement of high rotating speed; 3. the glue overflow amount of the magnetic steel is difficult to control, the size is easily influenced, a plurality of programs are needed to control, and the processing and manufacturing difficulty is high.

While each of the manufacturing approaches described above have certain limitations, there is a need for an improved approach to remedy and alleviate the above-mentioned problems.

Disclosure of Invention

The present invention is directed to overcoming the disadvantages of the prior art and providing a method of manufacturing a rotor assembly. The invention adopts the principle of induction heating to realize the reliable bonding of the rotor magnetic steel and the rotor iron core.

The purpose of the invention is realized by the following technical scheme: a method of manufacturing a rotor assembly, comprising:

(1) the magnetic powder and the binder are mixed uniformly and pressed into an uncured magnet by a die.

(2) Mounting a magnet on a metal shaft;

(3) the induction coil is sleeved outside the magnet and is connected with a power supply, so that the metal shaft is subjected to electromagnetic induction heating, and the bonding agent in the inner hole part of the magnet is heated to overflow onto the shaft, so that the magnet is fixed on the shaft;

(4) and integrally heating the fixed magnet assembly to solidify the whole magnet. Finally, the rotor assembly is manufactured.

Further, the surface of the metal shaft is knurled.

Further, the surface of the metal shaft is provided with one or more grooves.

Further, in the step (2), the intermediate rotor assembly is used for positioning and balancing the rotor assembly.

Further, in the step (2), the positioning is performed through a step on the shaft, other parts mounted on the shaft, or an external positioning plate.

Further, in the step (3), the power supply is at a medium frequency or a high frequency.

Further, in the step (3), the heating temperature is 220-240 ℃.

Further, in the step (4), the heating temperature is 190 ℃ at 170 ℃.

Further, the binder is a thermosetting adhesive.

The invention has the beneficial effects that: the invention relates to a method for manufacturing a rotor assembly, which promotes the overflow of an adhesive in an inner hole area of magnetic steel and bonds the shaft by an induction heating shaft; the induction heating shaft system is a metal shaft easy to be subjected to induction heating, so that the temperature of the shaft required to overflow glue can be quickly reached; in addition, the whole temperature difference of the heated shaft is small, so that the overflowing glue area is uniform, and the glue overflowing area can be integrally and uniformly covered; finally, the whole is heated and cured to a certain extent, so that the bonding effect can be stabilized; furthermore, no additional adhesive is required to secure the magnets to the shaft, and the rotor assembly can be made cheaper.

Drawings

FIG. 1 is a schematic view of a heating shaft of the present invention;

FIG. 2 is a flow chart of the present invention;

FIG. 3 is a schematic view of the assembly of the rotor assembly;

FIG. 4 is a schematic view of a heater shaft of the present invention;

fig. 5 is a schematic view of a rotor assembly made in accordance with the present invention.

Detailed Description

The invention relates to a method for manufacturing a rotor assembly, which adopts an electromagnetic induction heating mode as shown in figure 1, and leads adhesive in a magnet to overflow by heating a metal shaft so as to lead the adhesive to be fixed on the shaft; as shown in fig. 2, specifically:

(1) uniformly mixing magnetic powder and a binder, and pressing the mixture into an uncured magnet by using a die; the binder is a thermosetting adhesive.

(2) As shown in fig. 3, mounting the magnets on the shaft, positioning and balancing the rotor assembly with the intermediate rotor assembly; specifically, the positioning is carried out through steps on the shaft, other parts mounted on the shaft or an external positioning plate; in particular, the material of the shaft is an inductively heatable metallic material.

(3) As shown in fig. 4, the induction coil is sleeved outside the magnet and is connected with a medium-frequency or high-frequency power supply, so that the metal shaft is subjected to electromagnetic induction heating, and the bonding agent in the inner hole part of the magnet is heated and overflows to the shaft, so that the magnet is fixed on the shaft;

(4) and integrally heating the fixed magnet assembly to solidify the whole magnet. The final manufacture results in a rotor assembly as shown in fig. 5.

The manufacturing process of the glue overflowing assembly comprises two steps: first step glue overflowing: the magnetic steel is fixed on the shaft (the temperature is higher and ranges from 220 ℃ to 240 ℃); and a second step of curing: the strength of the magnetic steel is increased (the conventional temperature is in the range of 170 ℃ and 190 ℃). The disadvantage of heating the overflowing glue at the beginning is as follows: the external diameter size of the magnetic steel cannot be controlled, and the invention has more advantages aiming at the size control, and specifically comprises the following steps:

firstly, the metal shaft is heated at high temperature and reacts until the glue overflows into the inner hole of the magnetic steel, so that the shaft and the magnetic steel are fixed.

Secondly, the strength of the magnetic steel is increased by conventional solidification, secondary glue overflow cannot be caused, and the control of other sizes of the magnetic steel is not influenced.

The invention changes the shaft system from the ceramic shaft to the metal shaft which can be inductively heated, promotes the glue overflow on the surface of the inner hole of the magnet through the shaft heating, and improves the difficulty that the glue overflow is difficult to control the glue overflow degree inside and outside to a certain extent caused by the integral heating and curing of the glue overflow. Where the shaft must be a metal shaft system that is susceptible to induction heating, the shaft surface may be knurled. Furthermore, one or more grooves may be provided in the surface of the shaft. The adhesive overflowing from the inner surface of the magnet during induction heating can form firm bonding with the shaft, and through subsequent integral curing, the strength of the magnetic steel is increased and the bonding strength is stabilized, so that the rotor assembly meeting the requirement of high-rotation-speed rotation is obtained.

Claims

1. A method of manufacturing a rotor assembly, comprising:

(2) The magnet is mounted on a metal shaft.

(3) The induction coil is sleeved outside the magnet and is connected with the power supply, so that the metal shaft is subjected to electromagnetic induction heating, and the binder in the inner hole part of the magnet is heated to overflow to the shaft, so that the magnet is fixed on the shaft.

2. The method of manufacturing a rotor assembly of claim 1 wherein the surface of the metal shaft is knurled.

3. A method of manufacturing a rotor assembly according to claim 1, wherein the surface of the metal shaft is provided with one or more grooves.

4. The method of manufacturing a rotor assembly of claim 1, wherein in step (2), an intermediate rotor assembly is used to position and balance the rotor assembly.

5. The method of manufacturing a rotor assembly as claimed in claim 4, wherein in step (2), the positioning is performed by a step on the shaft, other parts mounted on the shaft, or an external positioning plate, etc.

6. The method of manufacturing a rotor assembly according to claim 1, wherein in the step (3), the power source is at a medium frequency or a high frequency.

7. The method for manufacturing a rotor assembly as claimed in claim 1, wherein the heating temperature in the step (3) is about 220-240 ℃.

8. The method for manufacturing a rotor assembly as claimed in claim 1, wherein the heating temperature in the step (4) is about 170-190 ℃.

9. The method of manufacturing a rotor assembly of claim 1, wherein the adhesive is a thermosetting adhesive.