Permanent magnet synchronous motorized spindle assembling method

Abstract

The invention relates to the technical field of working spindles, in particular to a permanent magnet synchronous electric spindle assembling method. An existing permanent magnet synchronous motorized spindle bearing assembling method is improved, after a permanent magnet rotor is fixedly installed on a motorized spindle and before a bearing is assembled on the motorized spindle, the outer side of the permanent magnet rotor is sleeved with a magnetism isolating sleeve with the length not smaller than that of the permanent magnet rotor, the permanent magnet rotor is completely wrapped in the magnetism isolating sleeve, and then the bearing is assembled; and the bearing is arranged on the large-diameter section side of the motorized spindle in a sleeving mode from the small-diameter section of the motorized spindle through the magnetic isolation sleeve till the fixed installation position. In this way, in the bearing assembling process, the permanent magnet rotor cannot magnetize the bearing, the machining performance and reliability of the motorized spindle are remarkably improved, friction and abrasion of the bearing are reduced, the operation precision is improved, and the service life of equipment and the service life of the bearing are prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of working spindles, and in particular to an assembly method of a permanent magnet synchronous electric spindle. Background Art

[0002] As the core component in the field of modern mechanical processing, the permanent magnet synchronous electric spindle is widely used in the fields of aviation, aerospace, automobile manufacturing and precision processing due to its high efficiency, stability and compact structure. Its performance directly affects the processing accuracy and efficiency. In the permanent magnet synchronous electric spindle, the bearing is not only the key component to support the rotating parts, but also directly related to the running stability and life of the motor. Especially in high-speed and high-precision processing occasions, the performance requirements for the bearing are more stringent.

[0003] The Chinese invention patent application with application publication number CN102729146A discloses a grinding wheel electric spindle structure, which includes a housing, a spindle rotatably mounted in the housing through a bearing, a permanent magnet rotor fixedly mounted on the spindle, and a stator mounted in the housing. The characteristics of this electric spindle are that the spindle as a whole is a stepped shaft with a shaft diameter that increases in sections from one end to the other end, the permanent magnet rotor is mounted on the middle diameter section in the middle, and bearings are respectively mounted on the large diameter section and the small diameter section on both sides of the axial direction of the permanent magnet rotor on the spindle. When assembling this electric spindle, the permanent magnet rotor is often fixedly mounted on the spindle, and after ensuring its position accuracy and fixing reliability, other shaft parts such as bearings are installed. However, this assembly method causes the bearing to pass through the strong magnetic field generated by the permanent magnet rotor when installing the bearing, especially when installing the bearing on the large diameter section, and the bearing material will be magnetized during this process. However, excessive residual magnetism in the bearing may cause the bearing to run unsteadily, generate vibration and noise, reduce its running accuracy, and affect the overall performance of the electric spindle; residual magnetism may also generate local current, leading to electrochemical reactions on the bearing surface, causing corrosion, thereby damaging the bearing; the accumulation of magnetic substances on the bearing will destroy the uniformity of the lubricating oil film, reduce the lubrication effect, increase friction, cause temperature rise, further increase bearing wear, shorten its service life, and reduce the reliability of the electric spindle. Therefore, the existing assembly method causes the bearing to be magnetized and affects the reliability and life of the entire electric spindle. Summary of the invention

[0004] The object of the present invention is to provide a permanent magnet synchronous electric spindle assembly method to solve the problem that the bearings in the existing electric spindle assembly method are magnetized, thereby affecting the reliability and life of the entire electric spindle.

[0005] The permanent magnet synchronous electric spindle assembly method of the present invention comprises: after the permanent magnet rotor is fixedly installed on the electric spindle, a magnetic isolation sleeve with a length not less than that of the permanent magnet rotor is sleeved on the outer side of the permanent magnet rotor to completely wrap the permanent magnet rotor; the bearing is sleeved from the small diameter section of the electric spindle to the large diameter section side of the electric spindle through the magnetic isolation sleeve until it is fixedly installed; and the magnetic isolation sleeve is removed.

[0006] Furthermore, the inner diameter of the magnetic isolation sleeve satisfies a clearance fit with the outer peripheral surface of the permanent magnet rotor.

[0007] Furthermore, the outer diameter of the magnetic isolation sleeve satisfies a clearance fit with the inner peripheral surface of the bearing.

[0008] Furthermore, the magnetic isolation sleeve is a double-layer sleeve, the outer layer is a conductive non-ferromagnetic material, and the inner layer is a soft magnetic material with high magnetic permeability.

[0009] Furthermore, the inner layer is made of Permalloy, silicon steel sheet, manganese-zinc ferrite, superconducting material, nanocrystal or magnetic composite material.

[0010] Furthermore, the outer layer is made of aluminum alloy or copper.

[0011] Furthermore, the double-layer sleeves are inserted and fixed together as a whole by interference fit.

[0012] Furthermore, the thickness of the outer layer is more than twice the thickness of the inner layer.

[0013] Furthermore, both the outer edge and the inner edge of the end of the magnetic isolation sleeve are chamfered.

[0014] Furthermore, before removing the magnetic isolation sleeve, the nut for stopping and positioning the bearing is inserted from the small diameter section of the electric spindle through the magnetic isolation sleeve to the large diameter section of the electric spindle, and the bearing is tightened.

[0015] The present invention improves the existing permanent magnet synchronous electric spindle bearing assembly method. After the permanent magnet rotor is fixedly installed on the electric spindle and before the bearing is assembled on the spindle, a magnetic isolation sleeve with a length not less than that of the permanent magnet rotor is sleeved on the outer side of the permanent magnet rotor to completely wrap the permanent magnet rotor inside. Then the bearing is assembled, and the bearing is sleeved from the small diameter section of the electric spindle through the magnetic isolation sleeve to the large diameter section side of the electric spindle until it is fixedly installed. In this way, during the bearing assembly process, the permanent magnet rotor will not magnetize the bearing, which significantly improves the processing performance and reliability of the electric spindle, reduces the friction and wear of the bearing, improves the operating accuracy, and extends the service life of the equipment and the bearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The present invention is a schematic diagram of the process of assembling the bearing after installing the magnetic isolation sleeve on the main shaft; Figure 2The process of installing the nut after the bearing is assembled is schematically shown in the present invention; Figure 3 It is a structural schematic diagram of a magnetic isolation sleeve; Figure 4 for Figure 3 A partial enlarged view of the end of the intermediate magnetic sleeve.

[0017] In the figure: 1, angular contact ball bearing; 2, outer sleeve; 3, inner sleeve; 4, permanent magnet rotor; 50, small diameter section; 51, middle diameter section; 52, large diameter section; 6, nut; 7, set screw. DETAILED DESCRIPTION

[0018] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0019] The present invention aims to improve the problem that the bearings are easily magnetized by the permanent magnet rotor when passing through the permanent magnet rotor to be assembled on the main shaft during the existing electric spindle assembly process. The permanent magnet rotor is wrapped with a magnetic isolation sleeve during the bearing assembly to achieve magnetic shielding of the permanent magnet rotor. In this way, the bearings will not be magnetized by the permanent magnet rotor when passing through the permanent magnet rotor.

[0020] Based on such a concept, the present invention specifically provides different embodiments of a permanent magnet synchronous electric spindle assembly method.

[0021] In one embodiment, the assembly method includes the following steps.

[0022] S1: Place the main shaft upright on a horizontal assembly workbench with the large end at the bottom. The permanent magnet rotor 44 has been installed on the middle diameter section 51 of the main shaft before the bearing is assembled and fixed into a whole; S2: Clean the various components of the spindle and bearings to remove surface dirt, grease and impurities to ensure the cleanliness of the assembly; S3: vertically install the magnetic isolation sleeve on the periphery of the permanent magnet rotor 4. The length of the magnetic isolation sleeve must be greater than or equal to the length of the permanent magnet rotor 4 so as to cover and wrap the entire magnetic pole of the permanent magnet rotor 4. S4: insert the paired angular contact ball bearings 1 from the small diameter end of the main shaft, pass through the small diameter section 50 and the magnetic isolation sleeve in sequence, and finally install them to the required bearing installation position on the large diameter section 52; S5: Take out the magnetic isolation sleeve along the axial direction and proceed to the next step of the other assembly process of the permanent magnet synchronous electric spindle.

[0023] On the basis of the above embodiments, in order to facilitate assembly, in one embodiment, the outer diameter of the manufactured magnetic isolation sleeve is determined by the inner diameter of the required bearing, and the outer diameter of the magnetic isolation sleeve satisfies the clearance fit between it and the inner peripheral surface of the bearing; in the same consideration, in one embodiment, the inner diameter of the double-layer magnetic isolation sleeve is determined by the outer contour size of the permanent magnet rotor 4, and the inner diameter of the magnetic isolation sleeve satisfies the clearance fit between it and the outer peripheral surface of the permanent magnet rotor 4. For example, measuring the outer contour size of the permanent magnet rotor 4, in one embodiment, the outer contour size of the permanent magnet rotor 4 is 80mm, and the inner diameter size of the magnetic isolation sleeve is also 80mm; measuring the inner ring size of the angular contact ball bearing 1, the inner ring size of the angular contact ball bearing 1 is 95mm, and the outer diameter size of the magnetic isolation sleeve is 95mm.

[0024] In an optimized embodiment, Figure 3-4 As shown, when manufacturing the magnetic isolation sleeve, the inner and outer edges of both ends of the magnetic isolation sleeve need to be chamfered to facilitate installation. In this embodiment, the inner and outer circle edges are chamfered by 45°×1mm.

[0025] Based on any of the above embodiments, in a preferred embodiment, the magnetic isolation sleeve is a double-layer sleeve, the outer layer is a conductive non-ferromagnetic material, and the inner layer is a soft magnetic material with high magnetic permeability.

[0026] Using the principle of electromagnetic induction, that is, the changing magnetic field will generate induced eddy currents on the surface of a good conductor. This eddy current will generate a magnetic field in the opposite direction of the original applied magnetic field, which will suppress and offset the original interfering magnetic field to a certain extent, thereby achieving a magnetic field shielding effect. This shielding principle can be vividly described as the "magnetic blocking" principle or the "eddy current suppression" principle. Setting the outer layer to a conductive non-ferromagnetic material, especially a non-ferromagnetic material with high conductivity, can achieve the effect of magnetic shielding.

[0027] Soft magnetic materials with high magnetic permeability are used to form a path with low magnetic resistance, that is, a shielding structure made of soft magnetic materials with high magnetic permeability is placed outside the protected equipment. At this time, the soft magnetic materials with high magnetic permeability form a parallel magnetic circuit with the air medium. In this parallel magnetic circuit, the relative magnetic permeability of the air medium is close to 1, and the relative magnetic permeability of the high magnetic permeability material is at least thousands of times the relative magnetic permeability of the air. Since the magnetic flux conduction follows the "minimum magnetic resistance principle", the magnetic flux passes through the high magnetic permeability soft magnetic material with small magnetic resistance to the greatest extent. This magnetic field shielding principle can be vividly described as the "magnetic repellency" principle or the "magnetic flux shunting" principle.

[0028] Therefore, a double-layer magnetic shielding sleeve is used to combine two magnetic shielding principles, thereby improving the magnetic shielding effect while reducing the amount of material used. Of course, in other embodiments, the magnetic shielding sleeve can be a single layer, such as any of the above layers.

[0029] Specifically, the common optional materials for the outer sleeve 2 include aluminum alloy, copper, etc. Considering the economic cost and material weight, aluminum alloy is selected as the non-ferromagnetic material with high electrical conductivity. The common optional materials for the inner magnetic isolation sleeve include Permalloy (iron-nickel alloy), silicon steel sheet, manganese-zinc ferrite (MnZn), superconducting materials, nanocrystalline and magnetic composite materials. Considering the ease of acquisition, material cost, machining performance, and magnetic permeability, Permalloy (iron-nickel alloy) is selected as the soft magnetic material with high magnetic permeability.

[0030] When a double-layered magnetic isolation sleeve is used, in order to ensure reliable wrapping of the permanent magnet rotor 4 and to achieve a better magnetic shielding effect, preferably, in one embodiment, the double-layered sleeves are inserted and fixed as a whole by interference fit to avoid relative sliding between the two.

[0031] On the basis of the above embodiment, in an optimized embodiment, the thickness of the double-layer structure magnetic isolation sleeve is optimized and designed according to the magnetic field strength of the permanent magnet rotor 4 to ensure that the bearing is in a safe magnetic field range. When the inner and outer diameters are fixed, the thickness of the inner sleeve 3 is more than twice the thickness of the outer sleeve 2. Taking the inner diameter of the magnetic isolation sleeve as 80mm and the outer diameter of the magnetic isolation sleeve as 95mm as an example, the total thickness of the outer sleeve 2 and the inner sleeve 3 is 7.5mm, then the thickness of the outer sleeve 2 is determined to be 2mm, and the thickness of the inner sleeve 3 is determined to be 5.5mm.

[0032] like Figure 1-2 , a more specific embodiment is as follows: S1: Place the main shaft vertically on a horizontal assembly workbench with the large diameter end at the bottom. The permanent magnet rotor 4 has been installed on the main shaft before the bearing is assembled and fixed into a whole; S2: Clean the various components of the spindle and bearings to remove surface dirt, grease and impurities to ensure the cleanliness of the assembly; S3: Making a double-layer magnetic isolation sleeve for bearing assembly, the specific process is: measuring the outer contour size of the permanent magnet rotor 4, the outer contour size of the permanent magnet rotor 4 in this embodiment is 80mm, then the inner diameter size of the inner sleeve 3 is also 80mm; measuring the inner ring size of the angular contact ball bearing 1, the inner ring size of the angular contact ball bearing 1 in this embodiment is 95mm, then the outer diameter size of the outer sleeve 2 is 95mm; making the inner sleeve 3 with a tubular high-permeability soft magnetic material, and making the outer sleeve 2 with a tubular high-conductivity non-magnetic material; assembling the obtained outer sleeve 2 and inner sleeve 3 together to form a double-layer magnetic isolation sleeve; S4: vertically install the double-layer magnetic isolation sleeve made in S3 on the periphery of the permanent magnet rotor 4 to cover the entire magnetic pole of the permanent magnet rotor 4; S5: insert two angular contact ball bearings 1 from the small diameter end of the main shaft, pass through the small diameter section 50 and the double-layer magnetic isolation sleeve in sequence, and finally install them to the required bearing installation position on the large diameter section 52; S6: Insert the nut 6 from the small diameter end of the main shaft, pass through the small diameter section 50 and the double-layer magnetic isolation sleeve in sequence, and connect with the main shaft through the internal thread. The lower end surface of the nut 6 is in close contact with the upper end surface of the inner ring of the angular contact ball bearing 1, and a certain preload force is provided; S7: Install the set screw 7. There is a through threaded hole on the circumferential surface of the nut 6. Screw a suitable set screw 7 into the hole so that the front end of the set screw 7 contacts the spindle to prevent the nut 6 from loosening. S8: Take out the double-layer magnetic isolation sleeve along the axial direction and proceed to the next step of the other assembly process of the permanent magnet synchronous electric spindle.

[0033] In this embodiment, after the bearing is compressed by the nut 6 , the magnetic isolation sleeve is removed, so as to avoid the possibility that the bearing moves relative to the main shaft and approaches the permanent magnet rotor 4 and is magnetized during the assembly of other components.

[0034] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. The patent protection scope of the present invention shall be based on the claims. All equivalent structural changes made using the contents of the description and drawings of the present invention should also be included in the protection scope of the present invention.

Claims

1. A permanent magnet synchronous electric spindle assembly method, characterized in that: include: After the permanent magnet rotor is fixedly installed on the electric spindle, a magnetic isolation sleeve having a length not less than that of the permanent magnet rotor is sleeved on the outer side of the permanent magnet rotor to completely wrap the permanent magnet rotor inside; Install the bearing from the small diameter section of the electric spindle through the magnetic isolation sleeve to the large diameter section of the electric spindle until it is fixed in the installation position; remove the magnetic isolation sleeve.

2. The permanent magnet synchronous electric spindle assembly method according to claim 1 is characterized in that: The inner diameter of the magnetic isolation sleeve satisfies a clearance fit with the outer peripheral surface of the permanent magnet rotor.

3. The permanent magnet synchronous electric spindle assembly method according to claim 1 is characterized in that: The outer diameter of the magnetic isolation sleeve satisfies a clearance fit with the inner peripheral surface of the bearing.

4. The permanent magnet synchronous electric spindle assembly method according to any one of claims 1 to 3, characterized in that: The magnetic isolation sleeve is a double-layer sleeve, the outer layer is a conductive non-ferromagnetic material, and the inner layer is a soft magnetic material with high magnetic permeability.

5. The permanent magnet synchronous electric spindle assembly method according to claim 4 is characterized in that: The inner layer is made of Permalloy, silicon steel sheet, manganese-zinc ferrite, superconducting material, nanocrystal or magnetic composite material.

6. The permanent magnet synchronous electric spindle assembly method according to claim 4 is characterized in that: The outer layer is made of aluminum alloy or copper.

7. The permanent magnet synchronous electric spindle assembly method according to claim 4 is characterized in that: The double-layer sleeves are inserted and fixed into a whole by interference fit.

8. The permanent magnet synchronous electric spindle assembly method according to claim 4 is characterized in that: The thickness of the outer layer is more than twice the thickness of the inner layer.

9. The permanent magnet synchronous electric spindle assembly method according to any one of claims 1 to 3, characterized in that: The outer edge and the inner edge of the end of the magnetic isolation sleeve are both chamfered.

10. The permanent magnet synchronous electric spindle assembly method according to any one of claims 1 to 3, characterized in that: Before removing the magnetic isolation sleeve, install the nut that stops the positioning bearing from the small diameter section of the electric spindle through the magnetic isolation sleeve to the large diameter section of the electric spindle, and tighten the bearing.

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