Static pressure rear-mounted electric spindle assembling method

Abstract

The invention relates to a static pressure rear-mounted electric spindle assembly method, and relates to the technical field of machine tool spindle assembly. Comprising the following steps: mounting a static-pressure front bearing and a static-pressure rear bearing in body shell holes; the spindle is installed in the front bearing hole and the rear bearing hole, and a check ring, a space ring, a static pressure end face bearing and a sealing ring are installed at the rear end of the spindle; guide sleeves are mounted on the rear end surfaces of the spindles; a pressing sleeve is sleeved outside the guide sleeve, a screw rod is upwards connected in the guide sleeve, a gland is arranged on the outer side of the screw rod and above the pressing sleeve, and a thrust bearing, a spherical washer and a flange nut are sequentially arranged above the gland; pressure oil is input into the rotor oil cavity hole; the flange nut is rotated to push the motor rotor to move downwards; the pressure pump releases pressure, and the motor rotor shrinks; removing a flange nut, a spherical washer, a thrust bearing, a gland, a pressing sleeve, a screw and a bent joint from the rear end of the main shaft; and the motor shell, the motor stator and the rear end cover are sequentially mounted. The assembly precision of the motor rotor and the main shaft can be improved, and the dynamic balance performance of a main shaft system is prevented from being affected by main shaft bending.

Description

Technical Field

[0001] The invention relates to the technical field of machine tool spindle assembly, in particular to a static pressure rear-mounted electric spindle assembly method. Background Art

[0002] With the development of mechanical processing technology, high-speed precision CNC machine tools with high cutting speed, high feed speed, high processing accuracy and other characteristics are the development direction of equipment manufacturing technology. High-speed precision CNC machine tools not only have extremely high production efficiency, but also can significantly improve the processing accuracy and surface quality of parts. The working performance of high-speed precision CNC machine tools depends first on the performance of the high-speed spindle unit. The electric spindle structure formed by combining the direct drive motor with the machine tool spindle further improves the machine tool's rotation accuracy, rigidity and speed regulation range, while achieving a smaller moment of inertia and quick start and stop functions.

[0003] Liquid hydrostatic bearings are widely used in precision machine tools due to their excellent load-bearing capacity, vibration resistance and service life. There are two main structural forms of electric spindles designed using the hydrostatic principle. One is the built-in type, which places the spindle motor between the front and rear bearings, effectively shortening the axial size of the spindle unit, improving the spindle stiffness and outputting a larger torque, but its heat dissipation performance is relatively poor. The other is the rear-mounted type, which places the motor on the outside of the rear bearing. This design helps to reduce the span between the bearing supports; since the motor is located on the outside of the support bearing, it has the characteristics of good heat dissipation, etc., but the motor, as the load of the spindle, is located on the outside of the two bearing supports, which can easily cause deformation of the spindle structure, thereby affecting the stiffness of the spindle.

[0004] There are generally two methods for installing the motor rotor: the hot-installation method and the oil pressure method. The hot-installation method is to heat the motor rotor. After the motor rotor expands thermally, the diameter of its inner hole becomes larger, which makes it easier to insert the motor rotor on the spindle. The hot-installation method is limited by the temperature rise of the motor rotor. When the heating temperature is too high, it is easy to cause the rotor to lose magnetism and cause the motor performance to deteriorate or be damaged. For high-speed static pressure rear-mounted electric spindles, this method is not recommended. The main reason is that the interference between the spindle and the motor rotor is large. Not only does it need to treat the spindle and its assembled components at low temperature, but it also needs to heat the motor rotor to a higher temperature. The oil pressure method is to pass pressure oil into the oil cavity of the inner hole of the motor rotor. Under the action of the pressure oil, the inner hole of the motor rotor is expanded, and then the motor rotor is pushed to the appropriate position along the axial direction of the spindle. For the rear-mounted hydrostatic electric spindle, the motor rotor can only be assembled after the front and rear bearings of the spindle are installed. If the motor rotor is not well centered and guided during assembly, the spindle will be deformed. For this kind of cantilever structure at the rear end of the spindle, once the spindle is deformed, the dynamic balance will deteriorate, which is not conducive to improving the performance of the spindle unit.

[0005] Under the above technical background, it is necessary to propose an assembly method for the rear-mounted hydrostatic electric spindle to avoid the spindle bending and affecting the dynamic balance performance of the spindle system. Summary of the invention

[0006] In order to solve at least one technical problem in the background technology, the present invention provides a static pressure rear-mounted electric spindle assembly method, so that the spindle motor rotor can evenly apply the assembly force to the end face of the motor rotor during the assembly process and can move well along the spindle axis, thereby improving the assembly accuracy of the motor rotor and the spindle, and avoiding the spindle bending and affecting the dynamic balance performance of the spindle system.

[0007] To achieve the above object, the present invention provides a method for assembling a static pressure rear-mounted electric spindle, comprising:

[0008] Step S1: Installing a hydrostatic front bearing and a hydrostatic rear bearing in the body shell hole at the front and rear, respectively, and installing a front end cover at the front side of the hydrostatic front bearing;

[0009] Step S2: After the main shaft is sequentially installed into the front bearing hole and the rear bearing hole, a retaining ring, a spacer ring, a static pressure end face bearing and a sealing ring are sequentially installed at the rear end of the main shaft;

[0010] Step S3: Stand up the assembly completed in step S2 so that the rear end of the main shaft faces upward, insert the motor rotor so that the pressure oil channel faces upward, and then the rotor inner hole 1 and the main shaft segment 1 as well as the rotor inner hole 2 and the main shaft segment 3 begin to form a connection;

[0011] Step S4: a guide sleeve is installed on the rear end face of the main shaft, a bent joint is installed at the entrance of the pressure oil channel of the second end face of the motor rotor, and a pressure pump is connected with a hose; a pressing sleeve is installed outside the guide sleeve, a screw rod is connected upward inside the guide sleeve, a pressure cover is installed outside the screw rod and above the pressing sleeve, and a thrust bearing, a spherical washer and a flange nut are installed above the pressure cover in sequence;

[0012] Step S5: inputting pressure oil into the rotor oil cavity hole through the pressure pump via the hose and the pressure oil channel, so that the motor rotor generates static pressure in the oil cavity formed by the rotor oil cavity hole and the main shaft section 2, so that the motor rotor and the main shaft remain coaxial; when the pressure of the pressure pump meets certain requirements, rotate the flange nut, and transmit the force to the motor rotor through the spherical gasket, thrust bearing, pressure cover and pressure sleeve in sequence, gradually pushing the motor rotor to move downward, and stop rotating the flange nut when the first end face of the rotor and the shoulder of the main shaft meet certain distance requirements; then the pressure pump releases pressure, the motor rotor shrinks, and the main shaft section 1 and the rotor inner hole 1, as well as the main shaft section 3 and the rotor inner hole 2 form an interference fit connection; thereafter, remove the flange nut, spherical gasket, thrust bearing, pressure cover, pressure sleeve, screw and elbow from the rear end of the main shaft;

[0013] Step S6: Install the motor body shell, the motor stator and the rear end cover in sequence.

[0014] Furthermore, a locking nut is arranged at the lower end of the screw rod and the outer side of the guide sleeve for fixing the screw rod.

[0015] Furthermore, the thread diameter of the lower end of the screw is smaller than the thread diameter of the upper end of the screw.

[0016] Furthermore, the pressing sleeve is provided with a plurality of symmetrical notches.

[0017] Furthermore, the inner diameter of the pressing sleeve is 0.005 to 0.02 mm larger than the outer diameter of the guide sleeve.

[0018] Furthermore, the material of the compression sleeve is magnetic isolation material, including copper and aluminum.

[0019] The beneficial effects of the present invention are:

[0020] The present invention provides a method for assembling a post-static electric spindle, which uses a guide sleeve concentric with the axis of the spindle to guide the pressing sleeve, which is conducive to achieving the coaxiality of the rotor and the spindle when pushing the rotor; the pressing sleeve is provided with symmetrical notches, which is conducive to ensuring that the rigidity of the pressing sleeve along its center line is symmetrical, so as to achieve uniform transmission of the thrust applied by the flange nut through the pressing sleeve to the motor rotor; a transmission mechanism of a spherical washer and a thrust bearing is arranged on the outside of the pressing sleeve, which is conducive to uniformly transmitting the locking torque of the flange nut to the pressing sleeve outside the guide sleeve through the spherical washer, the thrust bearing and the pressure cover, thereby avoiding the flange nut from generating uneven thrust on the pressing sleeve during the force transmission process. Through this design, it is ensured that the thrust is uniformly transmitted to the motor rotor during the assembly process, and the rotor moves along the axis of the spindle to achieve high-quality assembly, which is conducive to the assembly accuracy of the post-static electric spindle, and thus improves the performance and reliability of the entire electric spindle system. The structural design of the present invention is simple, the implementation is convenient, and it has a certain promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of a static pressure rear-mounted electric spindle involved in the present invention;

[0022] Figure 2 yes Figure 1 Schematic diagram of the spindle shaft section structure of the medium static pressure rear-mounted electric spindle connected to the motor rotor;

[0023] Figure 3 yes Figure 1 Schematic diagram of the inner hole structure of the motor rotor of the medium static pressure rear-mounted electric spindle;

[0024] Figure 4 It is a schematic diagram of the assembly structure of the static pressure rear-mounted electric spindle of the present invention when the motor is not installed;

[0025] Figure 5 is Figure 4 Schematic diagram of the structure of the motor rotor inserted into the foundation;

[0026] Figure 6 This is a schematic diagram of the initial assembly position of the motor rotor of the present invention;

[0027] Figure 7 yes Figure 6 A cross-sectional view of the bent joint connecting the rotor end face of the middle motor;

[0028] Figure 8 This is a schematic diagram of the motor rotor assembly end position of the present invention;

[0029] Fig. 9 It is a display Figure 6 Schematic diagram of the three-dimensional structure of the medium pressure sleeve parts.

[0030] In the figure: 1-spindle, 2-front cover, 3-static front bearing, 4-body shell, 5-static rear bearing, 6-spacer, 7-retaining ring, 8-static end face bearing, 9-sealing ring, 10-motor rotor, 11-motor stator, 12-motor body shell, 13-rear cover, 14-pressing sleeve, 15-guide sleeve, 16-locking nut, 17-screw, 18-pressing cover, 19-thrust bearing, 20-spherical washer, 21 -flange nut, 22-hose, 23-elbow joint, 101-shaft shoulder, 102-spindle section 1, 103-spindle section 2, 104-spindle section 3, 301-front bearing hole, 501-rear bearing hole, 1001-rotor first end face, 1002-rotor inner hole 1, 1003-rotor oil chamber hole, 1004-rotor inner hole 2, 1005-pressure oil channel, 1006-rotor second end face. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0033] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0034] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to specific circumstances.

[0035] In addition, the terms "installed", "set", "provided with", "connected", "connected", and "socketed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0036] like Figure 1-Figure 3As shown, the present invention targets a rear-mounted hydrostatic electric spindle, comprising a spindle 1, a front end cover 2, a hydrostatic front bearing 3, a body shell 4, a hydrostatic rear bearing 5, a spacer 6, a retaining ring 7, a hydrostatic end face bearing 8, a sealing ring 9, a motor rotor 10, a motor stator 11, a motor body shell 12, and a rear end cover 13. The hydrostatic front bearing 3 and the hydrostatic rear bearing 5 are installed at the front and rear ends of the body shell 4. The front end cover 2 is arranged at the front end of the hydrostatic front bearing 3, and the spindle 1 forms a radial support through the hydrostatic front bearing 3 and the hydrostatic rear bearing 5; a spacer 6, a retaining ring 7 and a hydrostatic end face bearing 8 are arranged at the rear end of the spindle 1 to form a hydrostatic thrust support; the motor rotor 10 is installed at the rear end of the spindle 1, the motor body shell 12 is sleeved on the outer side of the motor rotor 10, and the motor stator 11 is installed in the motor body shell 12; the sealing of the hydraulic oil is realized by the sealing ring 9 on one side of the inner hole of the motor body shell 12, and the rear end cover 13 is arranged on one side to form the sealing of the motor. The connection between the motor rotor 10 and the main shaft 1 is an interference fit. The specific structure is that the shaft section connecting the main shaft 1 and the motor rotor 10 has structural features such as a shoulder 101, a main shaft section 1 102, a main shaft section 2 103, and a main shaft section 3 104. The outer diameter of the main shaft section 1 102 is d3, the outer diameter of the main shaft section 2 103 is d2, and the outer diameter of the main shaft section 3 104 is d1, and d3>d2>d1; the motor rotor 10 has a rotor first end face 1001, a rotor The structural features include inner hole 1002, rotor oil cavity hole 1003, rotor inner hole 2 1004, pressure oil channel 1005, and rotor second end face 1006. The diameter of rotor inner hole 1002 is D3, the diameter of rotor oil cavity hole 1003 is D2, and the diameter of rotor inner hole 2 1004 is D1, and D3>D1, and D2 is 0.5-2.0mm larger than D3. The entrance of the pressure oil channel 1005 is provided with threads, and the inside is connected with the rotor oil cavity hole 1003. The main shaft section 102 and the rotor inner hole 1002, as well as the main shaft section 3 104 and the rotor inner hole 2 1004 are interference fit, that is, d3>D3, d1>D1, and the interference amount is determined according to the rotation speed of the main shaft.

[0037] The object of the present invention is to provide a method for assembling a static pressure rear-mounted static pressure electric spindle. When assembling the rotor of the static pressure rear-mounted static pressure electric spindle motor, a guide sleeve concentric with the spindle axis is used to evenly transfer the locking torque of the flange nut to the pressing sleeve outside the guide sleeve through a spherical washer and a thrust bearing.

[0038] To achieve the above object, the present invention provides a method for assembling a static pressure rear-mounted electric spindle, comprising:

[0039] Step S1: Install the hydrostatic front bearing 3 and the hydrostatic rear bearing 5 in the front and rear holes of the housing 4 respectively, and install the front end cover 2 in front of the hydrostatic front bearing 3;

[0040] Step S2: After the main shaft 1 is sequentially installed into the front bearing hole 301 and the rear bearing hole 501, the retaining ring 7, the spacer 6, the static pressure end bearing 8 and the sealing ring 9 are sequentially installed at the rear end of the main shaft 1. Figure 4 As shown;

[0041] Step S3: Stand up the assembly completed in step S2 so that the rear end of the main shaft 1 faces upward, insert the motor rotor 10 so that the pressure oil channel 1005 faces upward, and then the rotor inner hole 1002 and the main shaft segment 1 102 and the rotor inner hole 2 1004 and the main shaft segment 3 104 begin to form a connection, as shown in FIG. Figure 5 As shown;

[0042] Step S4: Figure 6 and Figure 7 As shown, a guide sleeve 15 is installed on the rear end face of the main shaft 1, a bent joint 23 is installed at the entrance of the pressure oil channel 1005 of the second end face 1006 of the motor rotor 10, and a pressure pump is connected with a hose 22; a pressing sleeve 14 is placed outside the guide sleeve 15, a screw 17 is connected upward inside the guide sleeve 15, a pressure cover 18 is installed on the outside of the screw 17 and above the pressing sleeve 14, and a thrust bearing 19, a spherical washer 20 and a flange nut 21 are installed above the pressure cover 18 in sequence;

[0043] Step S5: input pressure oil to the rotor oil cavity hole 1003 through the pressure pump via the hose 22 and the pressure oil channel 1005, so that the motor rotor 10 generates static pressure in the oil cavity formed by the rotor oil cavity hole 1003 and the main shaft section 103, so that the motor rotor 10 remains coaxial with the main shaft 1; when the pressure of the pressure pump meets a certain requirement, rotate the flange nut 21, and transmit the force to the motor rotor 10 through the spherical washer 20, the thrust bearing 19, the pressure cover 18 and the pressure sleeve 14 in sequence, gradually pushing the motor rotor 10 to move downward, and stop rotating the flange nut 21 when the rotor first end face 1001 and the shaft shoulder 101 of the main shaft 1 meet a certain distance requirement; then the pressure pump is depressurized, the motor rotor 10 shrinks, and the main shaft section 102 and the rotor inner hole 1002, as well as the main shaft section 3 104 and the rotor inner hole 2 1004 form an interference fit connection, such as Figure 8 As shown; thereafter, the flange nut 21, the spherical washer 20, the thrust bearing 19, the gland 18, the sleeve 14, the screw 17 and the elbow 23 are removed from the rear end of the main shaft 1;

[0044] Step S6: sequentially install the motor housing 12, the motor stator 11 and the rear end cover 13.

[0045] To further optimize the technical solution, a locking nut 16 is provided at the lower end of the screw 17 and the outer side of the guide sleeve 15 to fix the screw 17 and prevent the screw 17 from tilting during the force transmission process and affecting the force transmission of the press sleeve 14 to the motor rotor 10.

[0046] To further optimize the technical solution, the thread diameter of the lower end of the screw 17 is smaller than the thread diameter of the upper end, thereby increasing the radius of action of the tightening torque of the flange nut 21, which is beneficial for the thrust acting on the spherical washer 20 and the thrust bearing 19 to be located on a larger circumference, so that the force transmission route for transmitting the force to the pressing sleeve 14 through the pressure cover 18 is shorter.

[0047] Further optimize technical solutions, such as Fig. 9 As shown, the pressing sleeve 14 is provided with a plurality of symmetrical notches, which, on the one hand, facilitates the installation of the bent joint 23 , and on the other hand, makes the structure of the pressing sleeve 14 symmetrical and presents a symmetrical structural rigidity, which is beneficial to uniformly transfer the tightening torque of the flange nut 21 to the second end face 1006 of the rotor of the motor rotor 10 .

[0048] To further optimize the technical solution, the inner diameter of the pressing sleeve 14 is 0.005-0.02 mm larger than the outer diameter of the guide sleeve 15, which is conducive to the guide sleeve 15 guiding the pressing sleeve 14 and achieving coaxial adjustment of the motor rotor 10 with the main shaft 1 during the assembly process.

[0049] To further optimize the technical solution, the material of the pressing sleeve 14 is selected from magnetic-isolating materials such as copper and aluminum. When the motor is a permanent magnet synchronous motor, the motor rotor 10 is prevented from having magnetic force that affects the normal assembly.

[0050] The present invention avoids the friction torque generated when the flange nut 21 directly transmits force to the pressure cover 18 through the joint action of the thrust bearing 19 and the spherical washer 20. The friction torque will also generate a friction torque between the pressure sleeve 14 and the motor rotor 10. Since the installation of the screw 17 and the pressure cover 18 during assembly is generally asymmetrical, this will generate uneven thrust on the motor rotor 10, causing the motor rotor 10 to be non-concentric with the center line of the main shaft 1. In this way, the motor rotor 10 is subjected to the combined action of the axial force and the friction torque around the axis, causing the main shaft 1 to bend, and ultimately causing the dynamic balancing accuracy of the main shaft system to decrease.

[0051] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for assembling a static pressure rear-mounted electric spindle, characterized in that: include: Step S1: installing a hydrostatic front bearing (3) and a hydrostatic rear bearing (5) in the front and rear of the hole of the housing (4), and installing a front end cover (2) in front of the hydrostatic front bearing (3); Step S2: After the main shaft (1) is sequentially installed into the front bearing hole (301) and the rear bearing hole (501), a retaining ring (7), a spacer ring (6), a static pressure end face bearing (8) and a sealing ring (9) are sequentially installed at the rear end of the main shaft (1); Step S3: Stand the assembly completed in step S2 upright so that the rear end of the main shaft (1) faces upward, insert the motor rotor (10) so that the pressure oil channel (1005) faces upward, and then the rotor inner hole 1 (1002) and the main shaft segment 1 (102) as well as the rotor inner hole 2 (1004) and the main shaft segment 3 (104) begin to form a connection; Step S4: a guide sleeve (15) is installed on the rear end face of the main shaft (1), a bent joint (23) is installed at the entrance of the pressure oil passage (1005) of the second end face (1006) of the motor rotor (10), and a pressure pump is connected with a hose (22); a pressing sleeve (14) is placed outside the guide sleeve (15), a screw rod (17) is connected upward inside the guide sleeve (15), a pressure cover (18) is installed on the outside of the screw rod (17) and above the pressing sleeve (14), and a thrust bearing (19), a spherical washer (20) and a flange nut (21) are installed in sequence above the pressure cover (18); Step S5: pressure oil is input into the rotor oil cavity hole (1003) through the pressure pump via the hose (22) and the pressure oil channel (1005), so that the motor rotor (10) generates a static pressure effect in the oil cavity formed by the rotor oil cavity hole (1003) and the second main shaft section (103), so that the motor rotor (10) and the main shaft (1) remain coaxial; when the pressure of the pressure pump meets certain requirements, the flange nut (21) is rotated to transmit force to the motor rotor (10) through the spherical washer (20), the thrust bearing (19), the pressure cover (18) and the pressure sleeve (14) in sequence, gradually pushing the motor rotor (10). 0) moves downward, and stops rotating the flange nut (21) when the first end face (1001) of the rotor and the shoulder (101) of the main shaft (1) meet a certain distance requirement; then the pressure pump releases pressure, the motor rotor (10) contracts, and the main shaft section 1 (102) and the rotor inner hole 1 (1002) as well as the main shaft section 3 (104) and the rotor inner hole 2 (1004) form an interference fit connection; thereafter, the flange nut (21), the spherical washer (20), the thrust bearing (19), the pressure cover (18), the pressure sleeve (14), the screw (17) and the elbow (23) are removed from the rear end of the main shaft (1); Step S6: sequentially install the motor housing (12), the motor stator (11) and the rear end cover (13).

2. A method for assembling a static pressure rear-mounted electric spindle as claimed in claim 1, characterized in that: A locking nut (16) is arranged at the lower end of the screw rod (17) and the outer side of the guide sleeve (15) for fixing the screw rod (17).

3. A method for assembling a static pressure rear-mounted electric spindle as claimed in claim 1, characterized in that: The thread diameter of the lower end of the screw rod (17) is smaller than that of the upper end.

4. A method for assembling a static pressure rear-mounted electric spindle as claimed in claim 1, characterized in that: The pressing sleeve (14) is provided with a plurality of symmetrical notches.

5. A method for assembling a static pressure rear-mounted electric spindle as claimed in claim 1 or 4, characterized in that: The inner diameter of the pressing sleeve (14) is 0.005 to 0.02 mm larger than the outer diameter of the guide sleeve (15).

6. A method for assembling a static pressure rear-mounted electric spindle as claimed in claim 5, characterized in that: The material of the compression sleeve (14) is selected from magnetic isolation materials, including copper and aluminum.

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